U.S. patent application number 15/635466 was filed with the patent office on 2017-12-14 for wear resistance in 3d printing of composites.
The applicant listed for this patent is MARKFORGED, INC.. Invention is credited to Gregory Thomas Mark.
Application Number | 20170355138 15/635466 |
Document ID | / |
Family ID | 59560056 |
Filed Date | 2017-12-14 |
United States Patent
Application |
20170355138 |
Kind Code |
A1 |
Mark; Gregory Thomas |
December 14, 2017 |
WEAR RESISTANCE IN 3D PRINTING OF COMPOSITES
Abstract
According to at least one aspect, embodiments of the invention
provide a method comprising supplying a reinforced axial fiber
filament including a matrix material, a plurality of axial fiber
strands extending continuously within the matrix material, and a
multiplicity of fiber rods between 0.2-10 mm long dispersed
throughout the matrix material, at least some of the dispersed
fiber rods being oriented transversely to the fiber strands,
supplying a composite fill separately from the filament, including
a multiplicity of fiber rods between 0.2-10 mm long dispersed
throughout the fill, the fiber rods having hardness at least twice
that of a matrix of the fill, and depositing the filament within a
first region of an outward portion of a part, through a nozzle
throat having a thermal conductivity of at least 35 w/M-K adjacent
a nozzle tip having a Rockwell C hardness of at least C40.
Inventors: |
Mark; Gregory Thomas;
(Cambridge, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MARKFORGED, INC. |
Cambridge |
MA |
US |
|
|
Family ID: |
59560056 |
Appl. No.: |
15/635466 |
Filed: |
June 28, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15436216 |
Feb 17, 2017 |
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15635466 |
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15407740 |
Jan 17, 2017 |
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15436216 |
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15174645 |
Jun 6, 2016 |
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15407740 |
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14944093 |
Nov 17, 2015 |
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15174645 |
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14491439 |
Sep 19, 2014 |
9694544 |
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14944093 |
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14333881 |
Jul 17, 2014 |
9149988 |
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14491439 |
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14297437 |
Jun 5, 2014 |
9370896 |
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14333881 |
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14222318 |
Mar 21, 2014 |
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14297437 |
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14222318 |
Mar 21, 2014 |
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14333881 |
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14297437 |
Jun 5, 2014 |
9370896 |
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14491439 |
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14222318 |
Mar 21, 2014 |
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14297437 |
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14944088 |
Nov 17, 2015 |
9688028 |
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15174645 |
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14491439 |
Sep 19, 2014 |
9694544 |
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14944088 |
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14876073 |
Oct 6, 2015 |
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15174645 |
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14333881 |
Jul 17, 2014 |
9149988 |
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14876073 |
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15404816 |
Jan 12, 2017 |
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15436216 |
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15174645 |
Jun 6, 2016 |
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15404816 |
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62429711 |
Dec 2, 2016 |
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62172021 |
Jun 5, 2015 |
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62080890 |
Nov 17, 2014 |
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61907431 |
Nov 22, 2013 |
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61902256 |
Nov 10, 2013 |
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61883440 |
Sep 27, 2013 |
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61881946 |
Sep 24, 2013 |
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61880129 |
Sep 19, 2013 |
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61878029 |
Sep 15, 2013 |
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61847113 |
Jul 17, 2013 |
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61831600 |
Jun 5, 2013 |
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61815531 |
Apr 24, 2013 |
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61804235 |
Mar 22, 2013 |
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61902256 |
Nov 10, 2013 |
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61881946 |
Sep 24, 2013 |
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61878029 |
Sep 15, 2013 |
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61847113 |
Jul 17, 2013 |
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61831600 |
Jun 5, 2013 |
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62172021 |
Jun 5, 2015 |
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62080890 |
Nov 17, 2014 |
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62172021 |
Jun 5, 2015 |
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62279657 |
Jan 15, 2016 |
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62277953 |
Jan 12, 2016 |
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62296559 |
Feb 17, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 64/165 20170801;
B29K 2105/12 20130101; B29C 64/118 20170801; B33Y 10/00 20141201;
B33Y 70/00 20141201; B29C 31/08 20130101; B29C 64/20 20170801; B29C
64/209 20170801; B33Y 30/00 20141201; B29C 31/042 20130101; B29K
2307/04 20130101 |
International
Class: |
B29C 64/165 20060101
B29C064/165; B33Y 70/00 20060101 B33Y070/00; B33Y 10/00 20060101
B33Y010/00; B33Y 30/00 20060101 B33Y030/00; B29C 31/04 20060101
B29C031/04; B33Y 50/02 20060101 B33Y050/02; B29C 31/08 20060101
B29C031/08; B29C 64/20 20060101 B29C064/20 |
Claims
1. A method for additively manufacturing a part, the method
comprising: supplying a reinforced axial fiber filament including a
matrix material, a plurality of axial fiber strands extending
substantially continuously within the matrix material, and a
multiplicity of fiber rods between 0.2-10 mm long dispersed
throughout the matrix material, at least some of the dispersed
fiber rods being oriented transversely to the axial fiber strands;
supplying a composite fill separately from the continuous/random
fiber reinforced composite filament, including a multiplicity of
fiber rods between 0.2-10 mm long dispersed throughout the
composite fill, the fiber rods having hardness at least twice that
of a matrix of the composite fill; and depositing the reinforced
axial fiber filament within a first region formed in an outward
portion of a part that is closer to an outer wall of the part than
to a centroid of the part, through a nozzle throat formed from a
material having a thermal conductivity of at least substantially 35
w/M-K or higher adjacent a nozzle tip formed from a material having
a Rockwell C hardness at least substantially C40.
2. The method for additively manufacturing a part according to
claim 1, further comprising: applying heated pressure to
continuously melt and spread the reinforced axial fiber filament;
and applying heated pressure to continuously embed a proportion of
the first dispersed fiber rods against a previously deposited
reinforced axial fiber filament.
3. The method for additively manufacturing a part according to
claim 1, wherein depositing the reinforced axial fiber filament
within a first region includes depositing the reinforced axial
fiber filament within a first region formed in an outward portion
of a part that is closer to an outer wall of the part than to a
centroid of the part, through a nozzle throat formed from a
material having a thermal conductivity of at least substantially 35
w/M-K or higher adjacent a nozzle tip formed from a material having
a Rockwell C hardness at least substantially C50.
4. The method for additively manufacturing a part according to
claim 1, further comprising: flowing the matrix material of the
reinforced axial fiber filament and a first proportion of the fiber
rods reinforced axial fiber filament interstitially among the axial
fiber strands, and forcing a second proportion of the fiber rods of
the reinforced axial fiber filament against previously deposited
portions of the part.
5. A method for additively manufacturing a part, the method
comprising: supplying a reinforced axial fiber filament including a
matrix material, a plurality of axial fiber strands extending
substantially continuously within the matrix material, and a
multiplicity of fiber rods between 0.2-10 mm long dispersed
throughout the matrix material, at least some of the dispersed
fiber rods being oriented transversely to the axial fiber strands;
supplying a composite fill separately from the continuous/random
fiber reinforced composite filament, including a multiplicity of
fiber rods between 0.2-10 mm long dispersed throughout the
composite fill, the fiber rods having hardness at least twice that
of a matrix of the composite fill; and depositing the composite
fill through a nozzle throat formed from a material having a
thermal conductivity of at least substantially 35 w/M-K or higher
adjacent a nozzle tip formed from a material having a Rockwell C
hardness at least substantially C40.
6. A method for additively manufacturing a part, the method
comprising: supplying a composite fill including a multiplicity of
fiber rods between 0.2-10 mm long dispersed throughout the
composite fill, the fiber rods having hardness at least twice that
of a matrix of the composite fill; and depositing the composite
fill through a nozzle having a nozzle body through which heat is
applied to the composite material, an interior nozzle throat within
the nozzle body through which the composite material exits and
abrades the nozzle throat, and adjacent an exterior nozzle tip that
contacts and rubs against a top surface of a previously deposited
part and is abraded by the chopped fiber filler, wherein a majority
of the thermal mass of the nozzle body includes a material having a
thermal conductivity of at least substantially 100 w/M-K or higher,
and the interior nozzle throat and exterior nozzle tip are formed
having a thermal conductivity of at least substantially 60 w/M-K as
well as at least a Rockwell C hardness of substantially C50.
7. The method for additively manufacturing a part according to
claim 6, wherein a majority of the thermal mass of the nozzle body
includes a material having a thermal conductivity of substantially
200 w/M-K or higher, and the interior nozzle throat and exterior
nozzle tip are formed having a thermal conductivity of at least
substantially 100 w/M-K as well as at least a Rockwell C hardness
of substantially C60.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 15/436,216, filed Feb. 17, 2017, the disclosure of which
is herein incorporated by reference in its entirety. U.S. patent
application Ser. No. 15/436,216 claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. provisional application Ser. No. 62/296,559,
filed Feb. 17, 2016, is a continuation-in-part of U.S. patent
application Ser. No. 15/404,816, filed Jan. 12, 2017, and is a
continuation-in-part of U.S. patent application Ser. No.
15/407,740, filed Jan. 17, 2017, the disclosures of which are all
herein incorporated by reference in their entireties. U.S. patent
application Ser. No. 15/404,816 claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. provisional application Ser. No. 62/277,953,
filed Jan. 12, 2016, and is a continuation-in-part of U.S. patent
application Ser. No. 15/174,645, filed Jun. 6, 2016, the
disclosures of which are both herein incorporated by reference in
their entireties. U.S. patent application Ser. No. 15/407,740
claims the benefit under 35 U.S.C. .sctn.119(e) of U.S. provisional
application Ser. No. 62/279,657, filed Jan. 15, 2016, and
62/429,711, filed Dec. 2, 2016, the disclosures of which are both
herein incorporated by reference in their entireties. U.S. patent
application Ser. No. 15/407,740 is also a continuation-in-part of
U.S. patent application Ser. No. 15/174,645, filed Jun. 6, 2016.
U.S. patent application Ser. No. 15/174,645 claims the benefit
under 35 U.S.C. .sctn.119(e) of U.S. provisional application Ser.
No. 62/172,021, filed Jun. 5, 2015, the disclosure of which is
herein incorporated by reference in its entirety; and is a
continuation-in-part of each of U.S. patent application Ser. No.
14/944,088, filed Nov. 17, 2015, Ser. No. 14/944,093, filed Nov.
17, 2015, and Ser. No. 14/876,073, filed Oct. 6, 2015, the
disclosures of which are herein incorporated by reference in their
entirety. U.S. patent application Ser. No. 14/876,073 is a
continuation of U.S. patent application Ser. No. 14/333,881 [now
U.S. Pat. No. 9,149,988], filed Jul. 17, 2014. U.S. patent
application Ser. No. 14/944,093 claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. provisional application Ser. No. 62/172,021,
filed Jun. 5, 2015, and 62/080,890 filed Nov. 17, 2014, the
disclosures of which are herein incorporated by reference in their
entirety; and is a continuation-in-part of U.S. patent application
Ser. No. 14/491,439 filed Sep. 19, 2014, the disclosure of which is
herein incorporated by reference in its entirety. U.S. patent
application Ser. No. 14/944,088 claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. provisional application Ser. No. 62/172,021,
filed Jun. 5, 2015, and 62/080,890 filed Nov. 17, 2014, and is a
continuation-in-part of U.S. patent application Ser. No. 14/491,439
filed Sep. 19, 2014. U.S. patent application Ser. No. 14/491,439 is
a continuation-in-part of each of U.S. patent application Ser. No.
14/222,318, filed Mar. 21, 2014; U.S. patent application Ser. No.
14/297,437, filed Jun. 5, 2014; and U.S. patent application Ser.
No. 14/333,881 [now U.S. Pat. No. 9,149,988], filed Jul. 17, 2014;
the disclosures of which are herein incorporated by reference in
their entirety. U.S. patent application Ser. No. 14/222,318 claims
the benefit under 35 U.S.C. .sctn.119(e) of U.S. provisional
application Ser. No. 61/880,129, filed Sep. 19, 2013; 61/881,946,
filed Sep. 24, 2013; 61/883,440, filed Sep. 27, 2013; 61/902,256,
filed Nov. 10, 2013, 61/907,431, filed Nov. 22, 2013; 61/804,235,
filed Mar. 22, 2013; 61/815,531, filed Apr. 24, 2014; 61/831,600,
filed Jun. 5, 2013; 61/847,113, filed Jul. 17, 2013, and
61/878,029, filed Sep. 15, 2013, the disclosures of which are
herein incorporated by reference in their entirety. U.S. patent
application Ser. No. 14/297,437 claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. provisional application Ser. No. 61/881,946,
filed Sep. 24, 2013; 61/902,256, filed Nov. 10, 2013; 61/831,600,
filed Jun. 5, 2013; 61/847,113, filed Jul. 17, 2013, and
61/878,029, filed Sep. 15, 2013. U.S. patent application Ser. No.
14/297,437 is also a continuation-in-part of U.S. patent
application Ser. No. 14/222,318. U.S. patent application Ser. No.
14/333,881 is a continuation-in-part of each of U.S. patent
application Ser. No. 14/222,318, filed Mar. 21, 2014 and U.S.
patent application Ser. No. 14/297,437, filed Jun. 5, 2014.
FIELD
[0002] Aspects relate to three dimensional printing.
BACKGROUND
[0003] "Three dimensional printing" as an art includes various
methods such as Stereolithography (SLA) and Fused Filament
Fabrication (FFF). SLA produces high-resolution parts, typically
not durable or UV-stable, and is used for proof-of-concept work;
while FFF extrudes through a nozzle successive filament beads of
ABS or a similar polymer.
[0004] In the art of "Composite Lay-up", preimpregnated ("prepreg")
composite sheets of fabric impregnated with a resin binder are
layered into a mold, heated, and cured. In "Composite Filament
Winding" sticky "tows" including multiple thousands of individual
carbon strands are wound around a custom mandrel to form a
rotationally symmetric part.
[0005] Continuous fiber prepreg materials (continuous tows of
multiple fiber strands with a thermoplastic, thermosetting, or
energy curing resin matrix) may be manufactured, and may be 3D
printed with certain devices and/or processes.
SUMMARY OF INVENTION
[0006] According to one aspect and some embodiments of the present
invention, a three dimensional printer prints a part with a
composite material including a thermoplastic matrix and a chopped
fiber filler having a hardness more than two times the hardness of
the thermoplastic matrix. The printer includes a drive wheel for
advancing the composite material, and a heated nozzle through which
the composite material is deposited. The heated nozzle includes a
nozzle body through which heat is applied to the composite
material, the nozzle body being formed from a material having a
thermal conductivity of at least substantially 35 w/M-K. An
interior nozzle throat within the nozzle body through which the
composite material exits and abrades the nozzle throat may be
formed from a material having a Rockwell C hardness at least
substantially C50. An exterior nozzle tip that contacts and rubs
against a top surface of a previously deposited part and is abraded
by the chopped fiber filler may be formed from a material having a
Rockwell C hardness at least substantially C40.
[0007] Optionally, the nozzle body is formed from a material having
a thermal conductivity of substantially 50 w/M-K or higher. The
nozzle throat may be formed from a material having a Rockwell C
hardness at least substantially C60. The nozzle throat and nozzle
tip may each be formed from a material having a Rockwell C hardness
at least substantially C60. The nozzle body, the nozzle throat, and
nozzle tip may be unitarily formed from a material having a thermal
conductivity of at least substantially 60 w/M-K as well as Rockwell
C hardness of at least substantially C60. Optionally, a portion of
the nozzle body, the nozzle throat, and nozzle tip may be unitarily
formed from one of a sintered carbine and a sintered nitride.
[0008] Further optionally, and more advantageously with respect to
heat transfer, wear, and available commercial materials, a majority
of the thermal mass of the nozzle body may include a material
having a thermal conductivity of substantially 200 w/M-K or higher,
while the nozzle throat and nozzle tip may be formed within a
nozzle tip insert having a thermal conductivity of at least
substantially 100 w/M-K as well as at least a Rockwell C hardness
of substantially C60.
[0009] Still further optionally, the insert may be a tapered insert
having a nozzle tip with a surface area lower than a nozzle cross
sectional area adjacent the tip, such that the nozzle tip increases
in area and wears at a lower rate as material is worn away. The
nozzle body may include a cavity behind the nozzle throat of larger
internal diameter than the nozzle throat diameter, and/or may
include a chamfer leading from the larger cavity diameter to the
smaller nozzle throat diameter. A nozzle throat and nozzle tip may
be unitary in a nozzle insert held within the nozzle body by one of
a crimp and a braze. The printer may include a cutter arranged
along a composite material supply path from a supply of composite
material to the nozzle tip, the cutter positioned following the
drive wheel for advancing the material, wherein the cutter includes
a blade having a Rockwell C hardness at least substantially C60,
and/or a curved guide tube arranged along the material supply path,
the curved guide tube having at least one curved or curvable
section formed in one or more pieces from a material having a
Rockwell C hardness at least substantially C25. The printer may
include one drive wheel for advancing the composite material, the
at least one drive wheel having a drive surface including a
material having a Rockwell C hardness of at least substantially
C25. At least one drive wheel may be at least one of roughened,
textured, hobbed, and stepped. Alternatively, one drive wheel may
oppose one idle wheel, in which one of the drive wheel and the idle
wheel is at least one of roughened, textured, hobbed, and stepped
and the remaining one of the drive wheel and the idle wheel is
substantially smooth. One drive wheel opposing one idle wheel, in
which both opposing wheels are formed from a material having a
Rockwell C hardness at least substantially C25. When one drive
wheel opposes one idle wheel, and at least one of the drive wheel
and idle wheel may include a relative or absolute encoder for
measuring at least one of rotation speed and motor stall.
[0010] In another aspect and some embodiments of the present
invention, in a method for additively manufacturing a part, a
reinforced axial fiber filament may be supplied including a matrix
material, a plurality of axial fiber strands extending
substantially continuously within the matrix material, and a
multiplicity of fiber rods between 0.2-10 mm long dispersed
throughout the matrix material. At least some of the dispersed
fiber rods may be oriented transversely to the axial fiber
strands.
[0011] A composite fill may be supplied separately from the
continuous/random fiber reinforced composite filament, including a
multiplicity of fiber rods between 0.2-10 mm long dispersed
throughout the composite fill, the fiber rods having hardness at
least twice that of a matrix of the composite fill. The reinforced
axial fiber filament may be deposited in a first region formed in
an outward portion of a part that is closer to an outer wall of the
part than to a centroid of the part, through a nozzle throat formed
from a material having a thermal conductivity of at least
substantially 35 w/M-K or higher adjacent a nozzle tip formed from
a material having a Rockwell C hardness at least substantially
C40.
[0012] Optionally, heated pressure may be applied to continuously
melt and spread the reinforced axial fiber filament. Heated
pressure may also be applied to continuously embed a proportion of
the first dispersed fiber rods against a previously deposited
reinforced axial fiber filament. The reinforced axial fiber
filament may be deposited within a first region formed in an
outward portion of a part that is closer to an outer wall of the
part than to a centroid of the part, through a nozzle throat formed
from a material having a thermal conductivity of at least
substantially 35 w/M-K or higher adjacent a nozzle tip formed from
a material having a Rockwell C hardness at least substantially
C50.
[0013] The matrix material of the reinforced axial fiber filament
and a first proportion of the fiber rods reinforced axial fiber
filament may be flowed interstitially among the axial fiber
strands. A second proportion of the fiber rods of the reinforced
axial fiber filament may be forced against previously deposited
portions of the part.
[0014] Alternatively, a method for additively manufacturing a part
according to the some embodiments of the invention may include
supplying a reinforced axial fiber filament including a matrix
material, with a plurality of axial fiber strands extending
substantially continuously within the matrix material, and a
multiplicity of fiber rods between 0.2-10 mm long dispersed
throughout the matrix material, at least some of the dispersed
fiber rods being oriented transversely to the axial fiber strands.
A composite fill may be supplied separately from the
continuous/random fiber reinforced composite filament, including a
multiplicity of fiber rods between 0.2-10 mm long dispersed
throughout the composite fill, the fiber rods having hardness at
least twice that of a matrix of the composite fill. The composite
fill may be deposited through a nozzle throat formed from a
material having a thermal conductivity of at least substantially 35
w/M-K or higher adjacent a nozzle tip formed from a material having
a Rockwell C hardness at least substantially C40.
[0015] Alternatively, a method for additively manufacturing a part
according to the some embodiments of the invention may include
additively manufacturing a part, the method comprising supplying a
composite fill including a multiplicity of fiber rods between
0.2-10 mm long dispersed throughout the composite fill, the fiber
rods having hardness at least twice that of a matrix of the
composite fill. The composite fill may be deposited through a
nozzle having a nozzle body through which heat is applied to the
composite material, an interior nozzle throat within the nozzle
body through which the composite material exits and abrades the
nozzle throat, and adjacent an exterior nozzle tip that contacts
and rubs against a top surface of a previously deposited part and
is abraded by the chopped fiber filler. Optionally, a majority of
the thermal mass of the nozzle body includes a material having a
thermal conductivity of at least substantially 100 w/M-K or higher,
and the interior nozzle throat and exterior nozzle tip are formed
having a thermal conductivity of at least substantially 60 w/M-K as
well as at least a Rockwell C hardness of substantially C50.
Alternatively, and more advantageously with respect to heat
transfer, wear, and available commercial materials, a majority of
the thermal mass of the nozzle body may induce a material having a
thermal conductivity of substantially 200 w/M-K or higher, and the
interior nozzle throat and exterior nozzle tip are formed having a
thermal conductivity of at least substantially 100 w/M-K as well as
at least a Rockwell C hardness of substantially C60.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1A is a schematic view of a continuous core reinforced
filament deposition and fill material filament extrusion
printer.
[0017] FIG. 1B is a cross-sectional and schematic view of a
compound extrusion and fiber printhead assembly.
[0018] FIG. 1C is a close-up cross-section of a fiber printhead
assembly and a set of different possible compression/consolidation
shapes, including continuous/random core reinforced filament
shapes.
[0019] FIG. 1D is a block diagram and schematic representation of a
three dimensional printer as discussed herein, applicable to all
embodiments.
[0020] FIGS. 1E through 1G are cross-sections of 3D printed
structures that may be deposited by the method and printer of the
present disclosure, wherein FIG. 1E shows continuous/random core
fiber reinforced filament deposited together with polymer, ceramic,
or metal fill material, deposited by a 3D printer (e.g., FDM, SLA,
or other technique); FIG. 1F shows continuous/random core fiber
reinforced filament overmolded with a polymer, ceramic, or
injection or other molding, or continuous (substantially
non-layered or micro-layered) additive manufacturing; and FIG. 1G
shows continuous/random core fiber reinforced filament deposited
together and interacting with polymer, ceramic, or metal fill
material that includes a proportion (e.g., 5-20%) of short (e.g.,
1/10 to 2 mm length) chopped fiber (e.g., carbon, glass, aramid or
the like).
[0021] FIGS. 2A through 2C are schematic representations of a three
dimensional printing system using a continuous core reinforced
filament together with stereolithography or selective laser
sintering in which FIGS. 2A and 2B are schematic views of a
continuous core reinforced filament-SLA/SLS printer and FIG. 2C is
a schematic view of a tacking process.
[0022] FIG. 2D is a schematic representation of a three dimensional
printing system being used to form multiple layers in a printed
circuit board, which may be embedded in a reinforced molding as
disclosed herein.
[0023] FIG. 2E is a schematic representation of a rotatable
printing nozzle including a following feeding and compression
roller.
[0024] FIG. 2F is a schematic representation of a multi-nozzle
three-dimensional printer.
[0025] FIG. 2G is a schematic representation of a three dimensional
printing system including a print arm (e.g., a robot arm having 4
or more degrees of freedom) and selectable printer heads.
[0026] FIG. 2H is a schematic representation of a multi-element
printer head for use in the printing system.
[0027] FIG. 3 is a flow chart describing the overall operation of
the 3D printer of FIG. 3.
[0028] FIGS. 4A-4C show exemplary six-axis shell layup in
contrasting directions.
[0029] FIGS. 4D-4G show exemplary weighted distributions of 3D
printed composite lay-up according to the present embodiments,
e.g., to form sandwich panel structures, to increase effective
moment of inertia.
[0030] FIGS. 4H-4J show exemplary weighted distributions of 3D
printed composite lay-up according to the present embodiments,
e.g., to form sandwich panel shell and fiber cellular interior
structures, using both quasi-isotropic sets of shells or layers and
concentrically reinforced shells or layers, to increase effective
moment of inertia about the entire surface of the part as well as
increase crushing and torsional resistance.
[0031] FIGS. 5A-5D show the structures of FIGS. 4A-4D in which the
internal structures are additively deposited as soluble preforms
instead of structural resin (although in FIGS. 5A-5J the internal
resin structures may also be deposited in part or in whole as
structural resin, either solid or partial, e.g., honeycombed,
infill).
[0032] FIGS. 5E-5G show the structures of FIGS. 4E-4G in which the
internal structures are additively deposited as soluble preforms
instead of structural resin.
[0033] FIGS. 5H-5J show the structures of FIGS. 4H-4J in which some
internal structures are additively deposited as soluble preforms
instead of structural resin.
[0034] FIGS. 5K-5L show the structures similar to those in FIGS.
4A-4J and 5A-5J in which some internal structures are additively
deposited as sandwich panels.
[0035] FIG. 5M-5N show structures similar to those of FIGS. 5I and
5J, in which continuous reinforcing columns bridging layers extend
through multiple layers.
[0036] FIGS. 5O-5Q show the structures of FIGS. 5A-5C in which the
internal structures are additively deposited as non-soluble
preforms.
[0037] FIGS. 6A and 6B show successive steps in a process of
multi-component composite lay-up to build an exemplary bicycle
frame.
[0038] FIGS. 6C and 6D show successive steps in a process of
additive soluble preform and additive continuous fiber
reinforcement preform to build an exemplary bicycle frame.
[0039] FIG. 7A shows crossing points or crossing turns of two fiber
swaths in two forms.
[0040] FIGS. 7B-7F shows various crossing turns made about a hole
(e.g., a lace aperture or through hole), in reinforcement
formations of composite swath or multi-swath track approaches near
the center of the hole and departs beside and parallel to its
entry; approached near a tangent to the hole and departs from the
hole opposite to and parallel to its entry; and in which a bight,
open loop or touching loop may be made away from the reinforced
hole from which the reinforcement formation of composite swath or
multi-swath track returns toward the hole.
[0041] FIGS. 8A-8D show patch fills and concentric fills that may
be used to fill in reinforcement regions as disclosed herein.
[0042] FIG. 9 depicts a flowchart for configuring 3D printer
controller and/or slicer controller operations to permit
multi-layer rule handling, e.g., setting rules for groups of layers
or regions and changing the members of the rule groups.
[0043] FIG. 10A-10C shows an exemplary on-screen part rendering and
logic structure for the rule propagation procedure of FIG. 9.
[0044] FIGS. 11A-11B show schematic representations of a printed
part including a reinforced holes formed therein.
[0045] FIG. 11C shows exemplary composite layup via 3D printing of
composite fibers as disclosed herein in contrasting directions.
[0046] FIG. 12 shows a multi-layer laminate as FIG. 11C deposited
successively in a tubular form.
[0047] FIG. 13 is a schematic representation of a composite part
formed using three-dimensional printing methods.
[0048] FIG. 14 is a scanning electron microscope image of a
reinforcing carbon fiber and perpendicularly arranged carbon
nanotubes.
[0049] FIG. 15 shows a composite swath 2c of a reinforcement
formation in a layer LA.sub.n continuously deposited end-to-end
with an adjacent reinforcement formation continuing into the next
layer LA.sub.n+1, i.e., without cutting the composite swath 2c as
the part 14 is indexed to the next layer.
[0050] FIGS. 16-19 depict schematic representations of components
of a 3D printer's print head that may be hardened in a composite
printing system to resist wear from material flow through the
nozzle as well as rubbing of an already deposited composite part on
the nozzle.
[0051] FIGS. 20A-20E depict schematic representations of components
of a 3D printer's print head that may be hardened in a composite
printing system to resist wear from material flow through the
nozzle as well as rubbing of an already deposited composite part on
the nozzle.
DETAILED DESCRIPTION
[0052] This patent application incorporates the following
disclosures by reference in their entireties: U.S. patent
application Ser. Nos. 61/804,235; 61/815,531; 61/831,600;
61/847,113; 61/878,029; 61/880,129; 61/881,946; 61/883,440;
61/902,256; 61/907,431; 62/080,890; 62/172,021; 14/222,318;
14/297,437; 14/333,881 and 14/491,439 which may be referred to
herein as "Composite Filament Fabrication patent applications" or
"CFF patent applications".
Definitions
[0053] In the present disclosure, "3D printer" is inclusive of both
discrete printers and/or toolhead accessories to manufacturing
machinery which carry out an additive manufacturing sub-process
within a larger process. With reference to FIGS. 1-5, 3D printer is
controlled by a motion controller 20 which interprets dedicated
G-code 1102 and drives various actuators of the 3D printer in
accordance with the G-code 1102.
[0054] As used herein, "extrusion" shall have its conventional
meaning, e.g., a process in which a stock material is pressed
through a die to take on a specific shape of a lower
cross-sectional area than the stock material. Fused Filament
Fabrication (FFF) is an extrusion process. Similarly, "extrusion
nozzle" shall have its conventional meaning, e.g., a device
designed to control the direction or characteristics of an
extrusion fluid flow, especially to increase velocity and/or
restrict cross-sectional area, as the fluid flow exits (or enters)
an enclosed chamber. The present disclosure shall also use the
coined word "conduit nozzle" or "nozzlet" to describe a terminal
printing head, in which unlike a FFF nozzle, there is no
significant back pressure, or additional velocity created in the
printing material, and the cross sectional area of the printing
material, including the matrix and the embedded fiber(s), remains
substantially similar throughout the process (even as deposited in
bonded ranks to the part). As used herein, "deposition head" shall
include extrusion nozzles, conduit nozzles, and/or hybrid nozzles.
Also as used herein, a reference to a Figure numbers with no
following letter suffix shall refer also to all letter suffixes of
the same Figure number, e.g., a reference to "FIG. 1" refers to all
of FIGS. 1A, 1B, 1C, 1D, 1E, 1F, and 1G (or any other letter
suffix).
[0055] Lastly, in the three-dimensional printing art, "filament"
typically refers to the entire cross-sectional area of a spooled
build material, while in the composites art, "filament" refers to
individual fibers of, for example, carbon fiber (in which, for
example, a "1K tow" will have 1000 individual strands). For the
purposes of the present disclosure, "filament" shall retain the
meaning from three-dimensional printing, and "strand" shall mean
individual fibers that are, for example, embedded in a matrix,
together forming an entire composite "filament".
3D Printing System
[0056] The printer(s) of FIGS. 1A-1D, with at least two print heads
18, 10 and/or printing techniques, deposit with one head a fiber
reinforced composite filament (e.g., reinforced axial fiber
filament), and with a remaining head apply pure or neat matrix
resin or fill material (e.g., in some cases a composite fill) 18a
(thermoplastic or curing). The fiber reinforced composite filament
2 (also referred to herein as continuous core reinforced filament)
may be substantially void free and include a polymer or resin that
coats, permeates or impregnates an internal continuous single core
or multistrand core. It should be noted that although the print
head 18 is shown as an extrusion print head, "fill material print
head" 18 as used herein includes optical or UV curing, heat fusion
or sintering, or "polyjet", liquid, colloid, suspension or powder
jetting devices--not shown--for depositing fill material.
[0057] Although FIGS. 1A-1D in general show a Cartesian arrangement
for relatively moving the print-heads in 3 orthogonal translation
directions, other arrangements are considered within the scope of,
and expressly described by, a drive system or drive or motorized
drive that may relatively move a print head and a build plate
supporting a 3D printed part in at least three degrees of freedom
(i.e., in four or more degrees of freedom as well). For example,
for three degrees of freedom, a delta, parallel robot structure may
use three parallelogram arms connected to universal joints at the
base, optionally to maintain an orientation of the print head
(e.g., three motorized degrees of freedom among the print head and
build plate) or to change the orientation of the print head (e.g.,
four or higher degrees of freedom among the print head and build
plate). As another example, the print head may be mounted on a
robotic arm having three, four, five, six, or higher degrees of
freedom; and/or the build platform may rotate, translate in three
dimensions, or be spun.
[0058] The fiber reinforced composite filament 2, 2a is fed,
dragged, and/or pulled through a conduit nozzle 10, 199 optionally
heated to a controlled temperature selected for the matrix material
to maintain a predetermined viscosity, force of adhesion of bonded
ranks, melting properties, and/or surface finish.
[0059] After the matrix material or polymer 4, 4a is substantially
melted, the continuous core reinforced filament 2 is applied onto a
build platen 16 to build successive layers 14 to form a three
dimensional structure. The relative position and/or orientation of
the build platen 16 and conduit nozzle 10 are controlled by a
controller 20 to deposit the continuous core reinforced filament 2
in the desired location and direction.
[0060] A cutter 8 controlled by the controller 20 may cut the
continuous core reinforced filament during the deposition process
in order to (i) form separate features and components on the
structure as well as (ii) control the directionality or anisotropy
of the deposited material and/or bonded ranks in multiple sections
and layers. At least one secondary print head 18 may print fill
material 18a to form walls, infill, UV resistant and/or scratch
resistant protective coatings, and/or removable, dissolvable, or
soluble support material.
[0061] The supplied filament includes at least one axial fiber
strand 6, 6a extending within a matrix material 4, 4a of the
filament, for example a nylon matrix 4a that impregnates hundreds
or thousands of continuous carbon, aramid, glass, basalt, or UHMWPE
fiber strands 6a. The fiber strand material has an ultimate tensile
strength of greater than 300 MPa.
[0062] The driven roller set 42, 40 push the unmelted filament 2
along a clearance fit zone that prevents buckling of filament 2. In
a threading or stitching process, the melted matrix material 6a and
the axial fiber strands 4a of the filament 2 are pressed into the
part 14 and/or into the swaths below 2d, at times with axial
compression. As the build platen 16 and print head(s) are
translated with respect to one another, the end of the filament 2
contacts the ironing lip 726 and is subsequently continually ironed
in a transverse pressure zone 3040 to form bonded ranks or
composite swaths in the part 14.
[0063] FIG. 1B depicts a cross section of a compound (e.g., at
least dual) print head with an extrusion printhead 1800 (as head
18) and extrusion nozzle 1802 for FFF and a fiber deposition
printhead 199 (as head 10) and conduit nozzle 708 for continuous
fiber reinforced thermoplastic deposition. Like numbered features
are similar to those described with respect to FIG. 1A.
[0064] The feed rate (the tangential or linear speed of the drive
42, 40) and/or printing rate (e.g., the relative linear speed of
the platen/part and print head) may be monitored or controlled to
maintain compression, neutral tension, or positive tension within
the unsupported zone as well as primarily via axial compressive or
tensile force within fiber strand(s) 6a extending along the
filament 2.
[0065] As shown in FIGS. 1B and 1C, a transverse pressure zone 3040
includes an ironing lip 726 that reshapes the filament 2. This
ironing lip 726 compacts or presses the filament 2 into the part
and may also melt, heat to cross glass transition into a non-glassy
state, and/or liquefy the matrix material 4a in the transverse
pressure zone 3040. Optionally, the ironing lip 726 in the
transverse pressure zone 3040 flattens the melted filament 2 on the
"top" side (i.e., the side opposite the part 14), applying an
ironing force to the melted matrix material 4a and the axial fiber
strands 6a as the filament 2 is deposited in bonded ranks or
composite swaths 2c. For example, the controller 20 maintains the
height of the bottom of the ironing lip 726 to the top of the layer
below as less than the diameter of the filament (e.g., to compress
to 1/2 the height of the filament, at least at 1/2 the filament
height; to compress to 1/3 the height of the filament, at least at
1/3 the filament height, and so on). The controller 20 may maintain
the height at of the bottom of the ironing lip 726 to the layer
below at zero (e.g., in which case the amount of
consolidation/compression and the fiber swath 2c height may be a
function of system stiffness). Another reshaping force is applied
as a normal reaction force from the platen 16 or part 14 itself,
which flattens the bonded ranks or composite swaths 2c on at least
two sides as the melted matrix material 4a and the axial fiber
strands 6a are ironed to form laterally and vertically bonded ranks
(i.e., the ironing also forces the bonded ranks 2c into adjacent
ranks).
[0066] As shown in FIG. 1C, if the underlying layer or swaths 2d
includes channels, the normal reaction force from the part 14 may
create T-shapes instead. The pressure and heat applied by ironing
improves diffusion and fiber penetration into neighboring ranks or
swaths (laterally and vertically).
[0067] As shown in FIG. 1B, unmelted fiber reinforced filament may
be severed in a gap 62 between a guide tube 72 (having a clearance
fit) and the conduit nozzle 708; or within the conduit nozzle 708,
e.g., upstream of the non-contact zone 3030; and/or at the
clearance fit zone 3010, 3020 or at the ironing lip 726.
[0068] After the matrix material 6a is melted by the ironing lip or
tip 726, the feed and/or printing rate can be controlled by the
controller 20 to maintain neutral to positive tension in the
composite filament 2 between the ironing lip 726 and the part 14
primarily via tensile force within the fiber strands 4a extending
along the filament 2. A substantially constant cross sectional area
of the fiber reinforced composite filament is maintained in the
clearance fit zone, the unsupported zone, the transverse pressure
zone, and also as a bonded rank is attached to the workpiece or
part 14.
[0069] With reference to FIG. 1B, each of the printheads 1800 and
199 may be mounted on the same linear guide or different linear
guides or actuators such that the X, Y motorized mechanism of the
printer moves them in unison. As shown, the FFF printhead 1800
includes an extrusion nozzle 1802 with melt zone or melt reservoir
1804, a heater 1806, a high thermal gradient zone 1808 formed by a
thermal resistor or spacer 1809 (optionally an air gap), and a
Teflon or PTFE tube 1811. A 1.75-1.8 mm; 3 mm; or larger or smaller
thermoplastic filament is driven through, e.g., direct drive or a
Bowden tube provides extrusion back pressure in the melt reservoir
1804.
[0070] The companion continuous fiber embedded filament printhead
199, as shown, includes the conduit nozzle 708, the composite
ironing tip 728, and the limited contact cavity 714, in this
example each within a heating block heated by a heater 715. A cold
feed zone 712 may be formed within a receiving tube 64, including a
capillary-like receiving tube of rigid material and a small
diameter (e.g. inner diameter of 32 thou) Teflon/PTFE tube
extending into the nozzle 708. The cold feed zone is surrounded in
this case by an insulating block 66a and a heat sink 6b, but these
are fully optional. In operation, an unattached terminal end of the
fiber-embedded filament may be held in the cold feed zone, e.g., at
height P1. Distance P1, as well as cutter-to-tip distance R1, are
retained in a database for permitting the controller 20 to thread
and advance the fiber-embedded filament as discussed herein. If P1
and R1 are very similar (e.g., if the cutter location is near or
within the cold feed zone), P1 may be set to be the same or similar
to R1. Further as shown, the controller 20 is operatively connected
to the cutter 8, 8A, and feed rollers 42 facing idle rollers
40.
[0071] FIG. 1C shows a schematic close-up cross section of the
conduit nozzle 708. As shown in FIG. 1C, the inner diameter of the
receiving tube 64 (in this case, at a position where a Teflon/PTFE
inner tube forms the inner diameter) may be approximately 11/2 to
21/2 times (at, e.g., 32 thou) the diameter of the filament 2 (at,
e.g., 12-15, or 13 thou) shown therewithin. The inner diameter or
inner width of the terminal cavity 714 (at, e.g., 40 thou) is from
two to six times the diameter of the filament 2 shown therein.
These are preferred ranges, it is considered the diameter of the
receiving tube may be from 1 1/10 to 3 times the diameter of the
filament, and the inner diameter of the terminal cavity from two to
12 times the diameter of the filament. The terminal cavity is
preferably of larger diameter than the receiving tube.
[0072] FIG. 1C is a close-up cross-section of a fiber printhead
assembly and a set of different possible compression/consolidation
shapes, including continuous/random core reinforced filament
shapes. That is, in the present disclosure, all descriptions
referring to the continuous fiber filament 2, 2a or fiber
reinforced composite filament 2, 2a may refer to a fiber reinforced
composite filament 2, 2a including only continuous fibers 6a
extending along the filament and a matrix material 4, 4a (e.g.,
polymer, ceramic, or metal) but also to a fiber reinforced
composite filament 2, 2a including continuous fibers 6a extending
along the filament and embedding a 1-20% (higher percentages, such
as 30% or 40% are possible) volumetric proportion of short chopped
fibers 6b (referred to as "chopped fiber", "fiber rods", or "short
fiber" herein). The short chopped fibers 6b may be of the same
material as the continuous fiber 6a or a different materiel. For
example, a filament according to the present disclosure may include
a carbon fiber continuous tow reinforcement 6a interspersed with
short rods 6b of fiberglass, or a glass fiber continuous tow
reinforcement interspersed with short rods 6b of carbon fiber, or
any such combination. The short rods 6b may be randomly dispersed
and oriented in random directions, but processes may also be
applied during formation to orient at least a proportion of the
rods non-randomly. In either case, at least a proportion of the
short rods 6b may extend transverse to the filament 2, and some
rods 6b may stick out or be forced partially out of a filament to a
neighboring swath of filament 2c or a neighboring bead of fill
material 18a, either during deposition or during compaction. Some
such rods 6b may extend in a direction with a Z component (e.g.,
vertically, or at an angle), or otherwise partially normal to an
external surface of a deposited swath 2c, and some of these rods 6b
may bridge layers in a Z direction or bridge neighboring fiber
swaths 2c or beads 18a in X and/or Y directions.
[0073] It should be noted that neither the continuous fiber
reinforcement 6a nor the "rods" are shown to scale in the drawings
herein. A continuous fiber reinforcement may typically consist of
500, 1000, 2000 or more strands of fiber 6a within the filament 2.
The aspect ratio of a rod (e.g., length:diameter) may be
20:1-200:1, commonly 40-60:1. The rods 6c may be strands of a fiber
chopped to 0.05-2 mm length (optionally 0.2 mm up to 10 mm in
length).
[0074] In addition, as shown in FIG. 1C, the heated composite
filament ironing tip 726 is moved relative to the part, at a height
above the part 14 of less than the filament diameter and scaled
according to a desired proportion of composite swath, to iron the
fiber reinforced composite filament 2 as it is deposited to reshape
a substantially oval or circular bundle of inelastic axial fiber
strands 6a within the fiber reinforced composite filament
(including any embedded short or chopped fiber rods 6b) to a
substantially flattened block of inelastic fibers strands within a
bonded rank 2c of the part. Axial compression and/or laterally
pressing the melted matrix filament 2 into bonded ranks may enhance
final part properties by acting on either the strands 6a or the
rods 6b or both. For example, FIG. 1C shows a composite fiber
reinforced filament 2 applied with a compaction force, axial
compression, or lateral pressure 62. The compaction pressure from
axial compression and flattening from the ironing lip, compresses
or reshapes the substantially circular cross-section filament 2a
into the preceding layer below and into a second, substantially
rectangular cross-section compacted shape 2c, as well as forcing
rods 6b at or near the surface of the compacted shape 2c and/or
layer below 2d or adjacent ranks to interact with or extend into
any of fill material 18a, matrix 4a, neighboring strands 6a or
neighboring rods 6b. The entire filament 2a forms a bonded rank 2c
(i.e., bonded to the layer below 2d and previous ranks on the same
layer) as it is shaped.
[0075] The filament 2c and/or interior strands 6a of the filament
2c and/or interior rods 6b spread and intrude into adjacent bonded
ranks 2c or 2d on the same layer and the matrix material 4a and
strands 6a or rods 6b are compressed into the underlying shaped
filament or bonded rank of material 2d. This pressing, compaction,
or diffusion of shaped filaments or bonded ranks 2c, 2d reduces the
distance between reinforcing fibers, and increases the strength of
the resultant part (and replaces techniques achieved in composite
lay-up using post-processing with pressure plates or vacuum
bagging). Accordingly, in some embodiments or aspect of the
invention discussed herein, the axial compression of the filament 2
and/or especially the physical pressing by the printer head 70,
conduit nozzle or ironing lip 726 in zone 3040 may be used to apply
a compression/compaction/consolidation pressure directly to the
deposited material or bonded ranks or composite swaths 2c to force
them to spread or compact or flatten into the ranks beside and/or
below. Additionally, the pressure may force rods 6b to interact
with or extend into neighboring ranks beside or below and any of
their components (fill material, matrix, strands 6a, rods 6b).
Cross-sectional area is substantially or identically
maintained.
[0076] Alternatively or in addition, pressure may be applied
through a trailing pressure plate behind the print head; a full
width pressure plate and/or roller 2138 (see, e.g., FIG. 2E)
spanning the entire part that applies compaction pressure to an
entire layer at a time; and/or heat, pressure, or vacuum may be
applied during printing, after each layer, or to the part as a
whole to reflow the resin in the layer and achieve the desired
amount of compaction (forcing of walls together and reduction and
elimination of voids) within the final part.
[0077] FIGS. 1E through 1G are cross-sections of 3D printed
structures that may be deposited by the method and printer of the
present disclosure, wherein FIG. 1E shows continuous/random core
fiber reinforced filament deposited together with polymer, ceramic,
or metal fill material, deposited by a 3D printer (e.g., FDM, SLA,
or other technique); FIG. 1F shows continuous/random core fiber
reinforced filament overmolded with a polymer, ceramic, or
injection or other molding OV10, or continuous (substantially
non-layered or micro-layered) additive manufacturing; and FIG. 1G
shows continuous/random core fiber reinforced filament deposited
together and interacting with polymer, ceramic, or metal fill
material that includes a proportion (e.g., 5-20%) of short (e.g.,
1/10 to 2 mm length, but potentially up to 10 mm) chopped fiber
(e.g., carbon, glass, aramid or the like).
[0078] In the example shown in FIG. 1E, the lowest layer shown may
be at or near a floor of a part and the pattern of FIG. 1E may be
substantially similar at or near a roof of a part. As shown in FIG.
1E, the lowest layer is a layer of 3D printed resin, polymer,
ceramic or metal fill material 18a. Two ranks 2c are shown
deposited upon the lowest layer, next to one another. Within each
rank, continuous fiber strands 6a extend along the length of the
deposited core reinforced filament or swath, and short fiber rods
6b are substantially randomly arranged within the ranks. As shown,
at least a proportion of the short fiber rods 6b extend, under the
application pressure that flattens the filament, into neighboring
(below or beside) swaths or layers. The third layer depicted
extends with fiber strands 6a oriented in a direction substantially
90 degrees turned from the strands 6a in the layer below, with
ranks of fiber reinforcement in this layer also including
continuous strands 6a extending substantially along the entire
filament (e.g., for the lengths of entire segments of filament as
they are deposited and cut) as well as rods 6b dispersed therein.
This arrangement creates strong reinforcement in each of the
directions of the continuous fiber strands 6a as well as strong
interactions between the swaths and beads of fiber reinforcement 2
and fill material 18a. As noted herein, further layers of fiber
reinforcement may be deposited in quasi-isotropic, concentric, or
other patterns. Three layers of fill material 18a (in FIG. 1E, the
fourth through sixth layers from the bottom) are deposited above
the last fiber swaths 2c.
[0079] In the example shown in FIG. 1F, as discussed with respect
to injection molding and overmolding herein, either the fill
material 18a or the matrix 4a of FIG. 1E, or both, would have been
deposited instead as soluble material or in the same material as an
injection molding material to overmold the FIG. 1E with overmold
OV10, treating FIG. 1E in this instance as either a soluble preform
or a fiber reinforcement preform or both. FIG. 1F shows the fiber
material, both fiber strands 6a and short fiber rods 6b, overmolded
with overmold OV10 and embedded in an overmolded reinforced
molding. In this instance, the short fiber rods 6b bridge between
the continuous fibers 6a and the injection molding material of the
overmold OV10.
[0080] In the example shown in FIG. 1G, in contrast to the example
shown in FIG. 1E, the fill material 18 now includes both a matrix
material 18a and short fiber rods 18b. Accordingly, continuous
reinforced fiber filament is printed together with randomly
reinforced fiber filament. Additionally, the continuously
reinforced fiber filament reinforced with continuous fibers 6a is
additionally randomly or omnidirectionally reinforced by rods 6b.
As shown in FIG. 1G, the lowest layer is a layer of 3D printed fill
material 18a having a polymer, ceramic, or metal matrix and a
random or omnidirectionally dispersed short chopped fiber 18b.
Again, two ranks 2c are shown deposited upon the lowest layer, next
to one another. Within each rank 2c, continuous fiber strands 6a
extend along the length of the deposited core reinforced filament
or swath, and short fiber rods 6b are substantially randomly
arranged within the ranks. As shown, at least a proportion of the
short fiber rods 6b extend, under the application pressure that
flattens the filament, into neighboring (below or beside) swaths or
layers. Distinct from FIG. 1E, in this case, the neighboring swaths
or layers also include short fiber rods 6b. The third layer
depicted extends with fiber strands 6a oriented in a direction
substantially 90 degrees turned from the strands 6a in the layer
below, with ranks of fiber reinforcement in this layer also
including continuous strands 6a extending substantially along the
entire filament 2 (e.g., for the lengths of entire segments of
filament 2 as they are deposited and cut) as well as rods 6b
dispersed therein. This arrangement creates strong reinforcement in
each of the directions of the continuous fiber strands 6a as well
as strong interactions between the swaths and beads of fiber
reinforcement 2 (and its matrix 4a and strands and rods 6a, 6b) and
fill material 18a (and its matrix and rods 18b). As noted herein,
further layers of fiber reinforcement may be deposited in
quasi-isotropic, concentric, or other patterns. Three layers of
fill material 18 (in FIG. 1E, the fourth through sixth layers from
the bottom) are deposited above the last fiber swaths 2c.
[0081] In one variation, as shown in FIG. 1F, the chopped rod 18b
reinforced fill material 18a may be used together with pure
polymer, ceramic, or metal fill material 18a (e.g., as shown, in
the lowest layer). In another variation, not shown, core reinforced
filament 2 without fiber rods 6b but only with continuous fiber 6a
may be deposited together with any of pure polymer, ceramic, or
metal fill material 18a, and/or chopped fiber reinforced fill
material 18a (with polymer, ceramic, or metal matrix and chopped
fiber rods 18b), and/or core reinforced filament 2 including both
continuous fiber 6a and dispersed chopped rods 6b. As noted herein,
none of the materials of the reinforcement need be the same among
the reinforcing rods 18b of the chopped reinforced fill material
18a, the reinforcing continuous strands 6a of the core reinforced
filament, or the reinforcing chopped short fiber rods 6b of the
core reinforced filament; however, the matrix material 4a and/or
fill material matrix and/or fill material 18a should be of the same
polymer; of related polymer; of related copolymer; of compatible
polymer or copolymer; or of strongly adhering polymers.
[0082] As discussed herein, a three dimensional printer 1000 for
additive manufacturing of a part may include a supply of a combined
continuous/random fiber reinforced composite filament 2 including a
plurality of axial fiber strands 6a extending substantially
continuously within a matrix material 4 of the fiber reinforced
composite filament as well as a multiplicity of short chopped fiber
rods 6c extending at least in part randomly within the same matrix
material 4. A a deposition head (e.g., 10, 199) including a conduit
continuously transitioning to a substantially rounded outlet tipped
with an ironing lip 726 may be driven by a deposition head drive
that drives the ironing lip to flatten the fiber reinforced
composite filament 2 against previously deposited portions of the
part, as the matrix material 4, and a first proportion of the short
chopped fiber rods 6b, are flowed (e.g., short rods 6b internal to
the filament, amongst the inner strands 6a, may move with the flow)
interstitially among the axial fiber strands 6a spread by the
ironing lip 726, and force a second proportion of the short chopped
fiber rods 6b (e.g., those near the outer surface, on the outer
surface or extending through the outer surface of the filament 2)
against previously deposited portions of the part. A filament drive
may push an upstream portion of the solidified fiber reinforced
composite filament (e.g., more force transmitted along the filament
by the continuous strands 6a than the dispersed rods 6b) to force
the unattached terminal end of the fiber filament 2 through the
conduit to exit the conduit at the ironing lip 726. A controller 20
operatively connected to the filament drive and the deposition head
drive may direct these actions.
[0083] Alternatively, or in addition, a method for manufacturing a
part 14 may include supplying a core reinforced filament 2 having a
solidified matrix material 4 impregnating reinforcing strands 6a
aligned along the core reinforced filament 2 and impregnating
reinforcing chopped fiber rods 6b in part transverse to the core
reinforcing strands 6a. The core reinforced filament 2 may be
received in a cutter 8 and cut there. The cut core reinforced
filament 2 may be received in a nozzle 708 and heated as it 2 is
displaced out of the nozzle 708. A dragging force may be applied
from the part 14 via the reinforcing strands 6a but not via the
reinforcing chopped fiber rods 6b (or, the dragging force may be
greater via the reinforcing strands 6a than via the reinforcing
rods 6b). Pressure may be applied with the nozzle 708 to
continuously compact the core reinforced filament 2 as the core
reinforced filament 2 is fused into the part 14, and also to
continuously embed a proportion of the short chopped fiber rods 6b
(e.g., those near the outer surface, on the outer surface or
extending through the outer surface of the filament 2) against
previously deposited portions of the part 14. The compacted core
reinforced filament 2c, 2d may be fused into the part.
[0084] Alternatively, or in addition, a method for manufacturing a
part 14 may include supplying a core reinforced filament 2 having a
matrix material impregnating continuous reinforcing strands 6a
extending along the entire length of the core reinforced filament 2
and a proportion of first chopped fiber rods 6b, at least some of
which are oriented transversely to the continuous reinforcing
strands 6a. A fill material 18a may be supplied separately from the
core reinforced filament 2 and including a second chopped fiber
rods 18b. The core reinforced filament 2, as shown in FIGS. 1D-1F
and/or 5A-5N and/or 4A-4J, may be deposited within a first region
formed in an outward portion of a part 14 that is closer to an
outer wall of the part than to a centroid of the part 14. Pressure
may be applied with a heated nozzle tip 726 to continuously melt
and compact the core reinforced filament 2, 2c as the core
reinforced filament 2, 2c is fused into the layer of the part 14
and to continuously embed a proportion of the first chopped fiber
rods 6b against a previously deposited core reinforced filament 2
including first chopped fiber rods 6b. Pressure may also be applied
with the heated nozzle tip 726 to continuously melt and compact the
core reinforced filament 2, 2c as the core reinforced filament 2,
2c is fused into the layer of the part 14 and to continuously embed
a proportion of the first chopped fiber rods 6b against a
previously deposited fill material 18 including second chopped
fiber rods 18c. The fill material 18, as shown in FIGS. 1D-1F
and/or 5A-5N and/or 4A-4J, may be deposited within a second region
formed in a portion of the part 14 that is positioned inward from
the first region.
[0085] FIGS. 2A-2H depict embodiments of a three dimensional
printer in applying a fiber reinforced composite filament 2
together with DLP-SLA, SLA, SLS, "polyjet" or other techniques to
build a structure. Like numbered or like appearance features may be
similar to those described with respect to FIG. 1. FIGS. 2A and 2B
depict a hybrid system employing stereolithography (and/or
selective laser sintering) to provide the matrix about the embedded
fiber, i.e. processes in which a continuous resin in liquid or
powder form is solidified layer by layer by sweeping a focused
radiation curing or melting beam (laser, UV) in desired layer
configurations. In order to provide increased strength as well as
the functionalities associated with different types of continuous
core filaments including both solid and multistrand materials, the
stereolithography process associated with the deposition of each
layer can be modified into a two-step process that enables
construction of composite components including continuous core
filaments in desired locations and directions. A continuous core or
fiber may be deposited in a desired location and direction within a
layer to be printed, either completely or partially submerged in
the resin. After the continuous fiber is deposited in the desired
location and direction, the adjoining resin is cured to harden
around the fiber. This may either be done as the continuous fiber
is deposited, or it may be done after the continuous fiber has been
deposited. In one embodiment, the entire layer is printed with a
single continuous fiber without the need to cut the continuous
fiber. In other embodiments, reinforcing fibers may be provided in
different sections of the printed layer with different
orientations. In order to facilitate depositing the continuous
fiber in multiple locations and directions, the continuous fiber
may be terminated using a cutter as described herein, or by the
laser that is used to harden the resin.
[0086] FIG. 2B depicts a part 1600 being built on a platen 1602
using stereolithography or selective layer sintering. The part 1600
is immersed in a liquid resin (photopolymer) material or powder bed
1604 contained in a tray 1606. During formation of the part 1600,
the platen 1602 is moved by a layer thickness to sequentially lower
after the formation of each layer to keep the part 1600 submerged.
During the formation of each layer, a continuous core filament 1608
is fed through a conduit nozzle 1610 and deposited onto the part
1600. The conduit nozzle 1610 is controlled to deposit the
continuous core filament 1608 in a desired location as well as a
desired direction within the layer being formed. The feed rate of
the continuous core filament 1608 may be equal to the speed of the
conduit nozzle 1610 to avoid disturbing the already deposited
continuous core filaments. As the continuous core filament 1608 is
deposited, appropriate electromagnetic radiation (e.g., laser 1612)
cures or sinters the resin surrounding the continuous core filament
1608 in a location 1614 behind the path of travel of the conduit
nozzle 1610. The distance between the location 1614 and the conduit
nozzle 1610 may be selected to allow the continuous core filament
to be completely submerged within the liquid resin or powder prior
to curing. The laser is generated by a source 1616 and is directed
by a controllable mirror 1618. The three dimensional printer also
includes a cutter 1620 to enable the termination of the continuous
core filament as noted above.
[0087] Optionally, the deposited filament is held in place by one
or more "tacks", which are a sufficient amount of hardened resin
material that holds the continuous core filament in position while
additional core material is deposited. As depicted in FIG. 2C, the
continuous core filament 1608 is tacked in place at multiple
discrete points 1622 by the laser 1612 as the continuous core
filament is deposited by a nozzle, not depicted. After depositing a
portion, or all, of the continuous core filament 1608, the laser
1612 is directed along a predetermined pattern to cure the liquid
resin material 1604 and form the current layer. Similar to the
above system, appropriate electromagnetic radiation (e.g., laser
1612), is generated by a source 1616 and directed by a controllable
mirror 1618. The balance of the material can be cured to maximize
cross linking between adjacent strands is maximized, e.g., when a
sufficient number of strands has been deposited onto a layer and
tacked in place, the resin may be cured in beads that are
perpendicular to the direction of the deposited strands of
continuous core filament. Curing the resin in a direction
perpendicular to the deposited strands may provide increased
bonding between adjacent strands to improve the part strength in a
direction perpendicular to the direction of the deposited strands
of continuous core filament. If separate portions of the layer
include strands of continuous core filament oriented in different
directions, the cure pattern may include lines that are
perpendicular or parallel to the direction of the strands of
continuous fibers core material in each portion of the layer.
[0088] FIG. 2D depicts printing of a multi-layer PCB 1800, on a
build platen 16. The PCB 1800 is formed with a conductive core
material 1802 and an insulating material 1804 which are deposited
using a printer head including a heated extrusion nozzle 10 and
cutting mechanism 8. Similar to the multielement printer head, the
conductive core material 1802 and insulating material 1804 may be
selectively deposited either individually or together. Further, in
some embodiments the conductive core material 1802 is solid to
minimize the formation of voids in the deposited composite
material. When the conductive core material 1802 is printed without
the insulating material 1804 a void 1806 can be formed to enable
the subsequent formation of vias for use in connecting multiple
layers within the PCB 1800. Depending on the desired application,
the void 1806 may or may not be associated with one or more traces
made from the conductive core material 1802.
[0089] When desirable, a precision roller set can be used to
maintain a constant thickness along a relatively wider width of
material output from a print head 2102. Such an embodiment may be
of use when dealing with wider materials such as flat towpregs.
FIG. 2E shows a print head 2102 translating in a first direction. A
nozzle 2136 of the print head is attached to a trailing compression
roller 2138. The roller 2138 imparts a compressive force to the
material deposited onto print bed 2140. Depending on the
embodiment, the trailing roller 2138 can articulate around the Z
axis using any number of different mechanisms. For example, in one
embodiment, the print head 2102 is free-rotating on a bearing
(e.g., adding a fourth degree of freedom), such that the roller
always trails the direction of travel of the print head. In another
embodiment, the entire print head 402 is constructed to rotate
(e.g., adding a fourth degree of freedom). Alternatively or in
addition, the print bed 2140 may be rotated (e.g., as a fourth or
fifth degree of freedom) to achieve the desired trailing and
displacement.
[0090] FIG. 2F shows one embodiment of a high-speed continuous core
printer capable of using the above described materials. In the
depicted embodiment, the printer includes a print arm 2200
including a plurality of nozzles. The nozzles include a pure resin
nozzle 2202 adapted to print pure resin (e.g., as fill material)
2208. The print arm 2200 also includes a continuous core filament
nozzle 2204 adapted to print a continuous core filament 2210 for
use in fine detail work. Additionally, the print arm 2200 includes
a tape dispensing head 2206 capable of printing one or more
printable tapes 2212. The tape dispensing head enables large infill
sections to be printed quickly using the noted printable tapes.
However, fine detail work and gaps that cannot be filled in by the
tape can be filled by either the pure resin nozzle 2202 or
continuous core filament nozzle 2204. The above noted method and
system using wide tape fills greatly improves the speed of a
printer, enabling higher throughput, and commensurately lower
cost.
[0091] In FIG. 2G, an (e.g., robot arm) print arm 1400 is capable
of attaching to printer head 1402 at a universal connection 1404. A
continuous core reinforced filament 1406 may be fed into the
printer head 1402 before or after attachment to the printer 1400.
The print arm 1400 may return the printer head 1402 to an
associated holder or turret and then pick up printer head 1408 or
1410 for printing filament and other consumables different in size,
material, color, coating, and/or spray; or even a vision system
1412 (e.g., camera, rangefinder) for part inspection.
[0092] The continuous core reinforced filament may be formed by
adding a resin matrix or coating to a solid continuous core or a
prepreg in a heated conduit or extrusion nozzle. FIG. 2H depicts a
multi-element printer head 1500 that selectively combines (in any
feasible combination) and extrudes material feed options core 1502
(e.g., continuous copper wire, continuous fiber, stranded prepreg
wire or fiber), matrix 1504 (e.g., binding resin such as nylon),
and support 1506 (e.g., a dissolvable support material). For
example, a core 1502 might be surrounded by a matrix binder 1504 on
the bottom surface and a dissolvable/soluble support 1506 on the
top surface (e.g., section 1508). The multi-element printer head
1500 may also deposit the core 1502 coated with either the matrix
binder 1504 or soluble support 1506 separately (e.g., sections 1510
and 1514), or e.g., deposit any of the materials individually
(e.g., the bare core or copper wire at section 1512).
[0093] As shown in FIG. 2H, multi-element printer head 1500 (or any
other print head embodiment depicted herein) may include an air
nozzle 1508 which enables pre-heating of the print area and/or
rapid cooling of the extruded material to aid in forming structures
such as flying leads, gap bridging, and other similar features. For
example, a conductive core material may be deposited by the
multi-element printer head 1500 with a co-extruded insulating
plastic, to form a trace in the printed part. The end of the trace
may then be terminated as a flying lead (the multi-element printer
head lifts and deposits the core and jacket), optionally cooling
the insulating jacket with the air nozzle 1508. The end of the wire
could then be printed as a "stripped wire" where the conductive
core is extruded without the insulating jacket. The cutting
mechanism 8 may then terminate the conductive core. Formation of a
flying, uninsulated lead in the above-noted manner may be used to
eliminate a later stripping step.
[0094] Fully optionally, in addition, one of the two opposing
wheels, typically the idler wheel, may include a relative or
absolute encoder for rotation count or speed, enabling the
controller 20 to sense either or both of a slip or a jam in the
fiber or an out-of-fiber condition (e.g., if gap between wheels 40,
42 is a fixed gap advancing the fiber, and the drive wheel 40 is
commanded to advance the fiber, yet the idler wheel encoder does
not advances, this may mean the fiber is slipping or jammed or no
longer supplied, with a stall condition of the motor in addition
being determined to be a slip or jam rather than an out-of-fiber
condition).
[0095] FIG. 3 depicts a block diagram and control system of the
three dimensional printer which controls the mechanisms, sensors,
and actuators therein, and executes instructions to perform the
control profiles depicted in and processes described herein. A
printer is depicted in schematic form to show possible
configurations of e.g., three commanded motors 116, 118, and 120.
It should be noted that this printer may include the compound
assembly of printheads 199, 1800 depicted in FIG. 1C.
[0096] As depicted in FIG. 1D, the three-dimensional printer 3001
includes a controller 20 which is operatively connected to the
fiber head heater 715, the fiber filament drive 42 and the
plurality of actuators 116, 118, 120, wherein the controller 20
executes instructions which cause the filament drive to deposit
and/or compress fiber into the part. The instructions are held in
flash memory and executed in RAM (not shown; may be embedded in the
controller 20). An actuator 114 for applying a spray coat, as
discussed herein, may also be connected to the controller 20. In
addition to the fiber drive 42, a filament feed 1830 be controlled
by the controller to supply the extrusion printhead 1800. A
printhead board 110, optionally mounted on the compound printhead
199, 1800 and moving therewith and connected to the main controller
20 via ribbon cable, breaks out certain inputs and outputs. The
temperature of the ironing tip 726 may be monitored by the
controller 20 by a thermistor or thermocouple 102; and the
temperature of the heater block holding nozzle 1802 of any
companion extrusion printhead 1800 may be measured by a thermistor
or thermocouple 1832. A heater 715 for heating the ironing tip 726
and a heater 1806 for heating the extrusion nozzle 1802 are
controlled by the controller 20. A heat sink fan 106 and a part fan
108, each for cooling, may be shared between the printheads 199,
1800 and controlled by the controller 20. Rangefinder 15 is also
monitored by the controller 20. The cutter 8 actuator, which may be
a servomotor, a solenoid, or equivalent, is also operatively
connected. A lifter motor for lifting one or either printhead 199,
1800 away from the part (e.g., to control dripping) may also be
controlled. Limit switches 112 for detecting when the actuators
116, 118, 120 have reached the end of their proper travel range are
also monitored by the controller 20.
[0097] As depicted in FIG. 1D, an additional breakout board 122,
which may include a separate microcontroller, provides user
interface and connectivity to the controller 20. An 802.11 Wi-Fi
transceiver connects the controller to a local wireless network and
to the Internet at large and sends and receives remote inputs,
commands, and control parameters. A touch screen display panel 128
provides user feedback and accepts inputs, commands, and control
parameters from the user. Flash memory 126 and RAM 130 store
programs and active instructions for the user interface
microcontroller and the controller 20.
[0098] FIG. 3 depicts a flowchart showing a printing operation of
the printers 1000 in FIGS. 1-2. FIG. 3 describes, as a coupled
functionality, control routines that may be carried out to
alternately and in combination use the co-mounted FFF extrusion
head 1800 and fiber reinforced filament printing head 199 of FIG.
1A-1D.
[0099] In FIG. 3, at the initiation of printing, the controller 20
determines in step S10 whether the next segment to be printed is a
fiber segment or not, and routes the process to S12 in the case of
a fiber filament segment to be printed and to step S14 in the case
of other segments, including e.g., base, fill, or coatings. Step
S12 is described in detail with reference to FIG. 2. After each or
either of routines S12 and S14 have completed a segment, the
routine of FIG. 3 checks for slice completion at step S16, and if
segments remain within the slice, increments to the next planned
segment and continues the determination and printing of fiber
segments and/or non-fiber segments at step S18. Similarly, after
slice completion at step S16, if slices remain at step S20, the
routine increments at step S22 to the next planned slice and
continues the determination and printing of fiber segments and/or
non-fiber segments. "Segment" as used herein corresponds to
"toolpath" and "trajectory", and means a linear row, road, or rank
having a beginning and an end, which may be open or closed, a line,
a loop, curved, straight, etc. A segment begins when a printhead
begins a continuous deposit of material, and terminates when the
printhead stops depositing. A "slice" is a single layer or lamina
to be printed in the 3D printer, and a slice may include one
segment, many segments, lattice fill of cells, different materials,
and/or a combination of fiber-embedded filament segments and pure
polymer segments. A "part" includes a plurality of slices to build
up the part. FIG. 3's control routine permits dual-mode printing
with two different printheads, including the compound printheads
199, 1800 of FIG. 1A-1D.
[0100] All of the printed structures previously discussed may be
embedded within a molded article during a molding process, as
discussed herein, expressly including reinforced fiber structures
of any kind, sparse, dense, concentric, quasi-isotropic or
otherwise as well as fill material or plain resin structures. In
addition, in all cases discussed with respect to embedding in
injection molding, structures printed by fill material head 18
using thermoplastic extrusion deposition may be in each case
replaced with soluble material (e.g., soluble thermoplastic or
salt) to form a soluble preform which may form a printing substrate
for fiber reinforcement and then removed, leaving a continuous
fiber reinforced preform. All continuous fiber structures discussed
herein, e.g., sandwich panels, shells, walls, reinforcement
surrounding holes or features, etc., may be part of a continuous
fiber reinforced preform.
[0101] That is, the present disclosure contemplates a method of
fabricating a reinforced molding, where a "molding" is used as a
noun and a reinforced molding comprises a molded, finished article
with a skeletal or dense internal reinforcement formed by a
continuous fiber structure. Using the 3D printer herein discussed
with reference to FIGS. 1-3 inclusive, which may deposit either
fill material, soluble material, or continuous fiber, the
reinforcing fiber is additively deposited in a reinforcement volume
to form a continuous fiber reinforcement preform. A preform may be
a substrate against which further layers of 3D printing are
deposited (fill material, soluble material, or continuous fiber) or
a shape to be embedded within a molded article, or both. For
example, a continuous fiber reinforcement preform is located within
a mold of a molding apparatus (such as an injection mold's internal
cavity, large enough and shaped appropriately to receive the
reinforcement preform). The mold is loaded (e.g., injected or
otherwise filled) with molten, flowable and/or optionally
substantially isotropic molding material (e.g., thermoplastic,
curable plastic, thermoset, metal, or the like, optionally
including chopped fibers or dispersed particulates). Injection
under heat and pressure of fluidized thermoplastic is "loading".
The molding material is hardened (e.g., cooled or cured) to
overmold the continuous fiber reinforcement preform with the
molding material, thereby forming a reinforced molding surrounding
an internal continuous fiber reinforcement preform with a hardened
substantially isotropic molding material. The reinforcement volume
is smaller than a volume of the entire reinforced molding.
[0102] For example, a schematic representation of a composite
structure is depicted in FIG. 13 which shows a sandwich panel
composite part. This sandwich panel composite part may form part of
or the entirety of a continuous fiber reinforcement preform that is
later embedded in a molded article (reinforced molding). The top
section 1900, and bottom section 1902, are printed using a
continuous core reinforced filament to form relatively solid
portions. In contrast, the middle section 1904 may be printed such
that it has different properties than the top section 1900 and the
bottom section 1902. The middle section 1904 may be printed either
as fill material (to be retained within the reinforced molding),
soluble material or a soluble preform (to be dissolved away before
or during overmolding of the sandwich panel structure within the
mold) or as fiber honeycomb (again, to be retained within the
reinforced molding). For example, the middle section 1904 may
include multiple layers printed in a honeycomb pattern using a
continuous core reinforced filament, a pure resin, or even a three
dimensionally printed foaming material. This enables the production
of a composite part including a lower density core using a three
dimensional printer, and this part may be a skeletal or
reinforcement structure for a reinforced molding.
[0103] In addition to using the continuous core reinforced
filaments to form various composite structures with properties in
desired directions using the fiber orientation, each of which may
form part of the reinforcement preform and be embedded in a
reinforced molding, in some embodiments it is desirable to provide
additional strength in directions other than the fiber direction.
For example, the continuous core reinforced filaments might include
additional composite materials to enhance the overall strength of
the material or a strength of the material in a direction other
than the direction of the fiber core. For example, FIG. 14 shows a
scanning electron microscope image of a carbon fiber core material
2000 that includes substantially perpendicularly loaded carbon
nanotubes 2002. Loading substantially perpendicular small fiber
members on the core increases the shear strength of the composite,
and advantageously increases the strength of the resulting part in
a direction substantially perpendicular to the fiber direction.
Such an embodiment may help to reduce the propensity of a part to
delaminate along a given layer.
[0104] FIGS. 4A-5P depict various parts formed using the printer
head(s) depicted in FIGS. 1A-1D and/or 2A-2G. FIGS. 4A, 5A and 5O
show a part including a plurality of sections 1322 deposited as two
dimensional layers in the XY plane. These sections 1322 may be
deposited as fill material 18 or as soluble material. If they are
deposited as soluble material, they may form the soluble preform.
Sections 1324 and 1326 are subsequently deposited in the ZY plane
to give the part increased strength in the Z direction. As shown in
FIGS. 4A and 5A, if sections 1322 are formed as the soluble preform
or as soluble material and are dissolved away or removed prior to,
during, or after overmolding and/or hardening the molding material
to overmold OV1 the continuous fiber reinforcement preform, a fiber
reinforced molding with an overmold OV1 surrounding an internal
continuous fiber reinforcement preform is formed, the overmold OV1
being a hardened substantially isotropic molding material. In FIGS.
4A and 5A, a box-like or canister-like reinforced molding is formed
with reinforcement concentrated along outer walls. Conversely, as
shown in FIG. 5O, if the support preform is not soluble and both
the support preform and any continuous fiber reinforcement preform
are overmolded with overmold OV11, a molding having both an
internal/embedded support preform (which may be, as discussed
herein, reinforced with rods, chopped, short, long, or particulate
reinforcement) and an internal/embedded fiber reinforcement preform
surrounding the support preform may be formed.
[0105] FIGS. 4B, 5B and 5P shows a related method of shell
printing, where layers 1328 and 1330 are formed in the XY plane and
are overlaid with shells 1332 and 1334 which extend in both the XY
and ZY planes. As depicted in the figure, the shells 1332 and 1334
may either completely overlap the underlying core formed from
layers 1328 and 1330, see portion 1336, or one or more of the
shells may only overly a portion of the underlying core. For
example, in portion 1338 shell 1332 overlies both layers 1328 and
1330. However, shell 1334 does not completely overlap the layer
1328 and creates a stepped construction as depicted in the FIGS. 4B
and 5B, if sections 1328 are formed as the soluble preform or as
soluble material and are dissolved away or removed prior to,
during, or after overmolding and/or hardening the molding material
to overmold OV2 the continuous fiber reinforcement preform, a fiber
reinforced molding with an overmold OV2 surrounding an internal
continuous fiber reinforcement preform is formed, the overmold OV2
being a hardened substantially isotropic molding material. In FIGS.
4A and 5B, a shell-like, cup-like, or open box reinforced molding
is formed, with reinforcement following the contour of the shell or
walls of the cup or open box. Again, as shown in FIG. 5P, if the
support preform is not soluble and both the support preform and any
continuous fiber reinforcement preform are overmolded with overmold
OV12, a molding having both an internal/embedded support preform
(which may be, as discussed herein, reinforced with rods, chopped,
short, long, or particulate reinforcement) and an internal/embedded
fiber reinforcement preform cupping the support preform may be
formed.
[0106] FIGS. 4C and 5C show an alternative embodiment where a
support material 1340 is added to raise the part relative to a
build platen, or other supporting surface, such that the pivoting
head of the three dimensional printer has clearance between the
part and the supporting surface to enable the deposition of the
shell 1342 onto the underlying layers 1344 of the part core. Again,
as shown in FIGS. 4B, 4C and 5B, 5C if sections 1344 and/or 1340
are formed as the soluble preform or as soluble material and are
dissolved away or removed prior to, during, or after overmolding
and/or hardening the molding material to overmold OV3 the
continuous fiber reinforcement preform, a fiber reinforced molding
with an overmold OV3 surrounding an internal continuous fiber
reinforcement preform is formed, the overmold OV3 being a hardened
substantially isotropic molding material. In FIGS. 4C and 5C, a
multi-level reinforced molding is formed, with both flat and curved
shapes in multiple orientations, and reinforcement following the
walls. It should be noted that any of the layers or shells of fiber
reinforcement shown in FIGS. 4A-4C or 5A-5C may be a multi-layer
laminate of differing fiber orientations (e.g., a quasi-isotropic
pattern or an anisotropic, directional pattern). Again, as shown in
FIG. 5Q, if the support preform is not soluble and both the support
preform and any continuous fiber reinforcement preform are
overmolded with overmold OV14, a molding having both an
internal/embedded support preform (which may be, as discussed
herein, reinforced with rods, chopped, short, long, or particulate
reinforcement) and an internal/embedded fiber reinforcement preform
cupping the support preform may be formed.
[0107] The above described printer head may also be used to form a
part with discrete subsections including different orientations of
a continuous core reinforced filament. The orientation of the
continuous core reinforced filament in one subsection may be
substantially in the XY direction, while the direction in another
subsection may be in the XZ or YZ direction.
[0108] The path planning and printing processes may utilize a fill
pattern that uses high-strength composite material in selected
areas and filler material (e.g., less strong composite or pure
resin such as nylon) in other locations, see FIGS. 4D-4G and 5E-5G,
which depict stacks of layers in cross section. As discussed with
reference to the sandwich panel global or region rule, in some
cases, reinforcement is conducted by identifying an internal volume
or volumes in the shape of simplified beams or panel, e.g., an
interior prism or volume spanning and extending beyond bending load
and/or support points. In addition, the part may be oriented during
planning for deposition such that layers within the volume span the
anticipated load and/or support points. Fiber may be fiber added
within the interior prism volume remote from a centroid of a cross
section of the volume, to increase effective moment of inertia
(particularly for bending or compression loads). Fibers may be
deposited in multiple adjacent bonded ranks and/or layers, to
increase fiber rank interaction and reinforcement of neighbors
(particularly for compression and tension loads). Through holes or
mounts through which or into which load members are expected to be
inserted may each be smoothly looped by fiber, optionally directly
at the wall of such mount (particularly for tension and torsion
loads, looping may permit fewer stress concentrations and the
transmission of tension through smooth paths).
[0109] Especially for beam and panel bending, the strength to
weight performance of a beam is optimized by placing fiber ranks as
far as possible (i.e., at the farthest position both within the
part and that does not violating any higher priority rules in
effect at the boundary of the part) from the centroid of a
cross-section to increase effective moment of inertia. A part
formed completely from the fill material or soluble material 1350,
and or a complete soluble preform, is contemplated.
[0110] In FIGS. 4E and 5E, a composite material 1352 is deposited
at the radially outward most portions of the part and extending
inwards for a desired distance to provide a desired increase in
stiffness and strength. The remaining portion of the part is formed
with the fill material 1350. A user may extend the use of composite
versus filler either more or less from the various corners of the
part as illustrated by the series of figures FIGS. 4D-4G and 5E-5G.
For example, a control algorithm controlled by controller 20 may
use a concentric fill pattern that traces the outside corners and
wall sections of the part, for a specified number of concentric
infill passes, the remainder of the part may then be filled using a
desired fill material. FIG. 5D shows a dissolved soluble preform
1340a (as a dotted line). As shown in FIGS. 4D-4F and 5D-5F, if
fill material sections 1350 are instead formed as the soluble
preform 1340a or as soluble material and are dissolved away or
removed prior to, during, or after overmolding and/or hardening the
molding material to overmold OV4-OV6 the continuous fiber
reinforcement preform, a fiber reinforced molding with an overmold
OV4-OV6 embedding an internal continuous fiber reinforcement
preform is formed, the overmold OV4-OV6 being a hardened
substantially isotropic molding material. In FIGS. 4E-4G or 5E-5G,
a box-like, canister-like, or tube-like reinforced molding is
formed with reinforcement concentrated as described.
[0111] FIGS. 4H-4J and 5H-5J depict further parts formed using the
printer head(s) depicted in FIGS. 1A-1D and/or 2A-2G.
[0112] Where FIGS. 4E through 4G or 5E through 5G do not expressly
show outer walls of the part formed from fill material 1350 (e.g.,
the parts in FIGS. 4E-4G may have outer wall(s) of fill material
1350 or outer walls of composite material 1352), FIGS. 4H through
4J show cross sections of parts with the outer wall 1350-OW
specifically shown.
[0113] As shown by FIGS. 5H-5J, in the following description with
reference to FIGS. 4H-4J, if the fill material 1350 is selectively
or entirely replaced with soluble material or considered to form
the soluble preform, the soluble material may be dissolved away
prior to, during, or following overmolding of any of the fiber
reinforcement structures shown in FIGS. 4H-4J and/or FIGS. 5H-5J.
As depicted in FIG. 5H, following the removal of the material
labeled 1350 as a soluble preform or as other soluble material, a
hollow cored reinforcement molding is formed which an overmold OV7
of hardened isotropic material surrounds outer walls, floor, and
ceiling of a continuous fiber reinforcement preform formed from the
quasi-isotropic laminates 1352-QI and concentric laminates
1352-CON. As depicted in FIG. 4I or 5I, following the removal of
the material labeled 1350 as a soluble preform or as other soluble
material, a through-holed but otherwise solid cored reinforcement
molding is formed which an overmold OV8 of hardened isotropic
material surrounds inner walls of the through-hole TH-H, outer
walls, floor, ceiling of a continuous fiber reinforcement preform
formed from the quasi-isotropic laminates 1352-QI and concentric
laminates 1352-CON. As depicted in FIG. 4J or 5J following the
removal of the material labeled 1350 as a soluble preform or as
other soluble material, a solid cored reinforcement molding is
formed which an overmold OV9 of hardened isotropic material
surrounds inner walls of the through-hole TH-H, outer walls, floor,
ceiling of a continuous fiber reinforcement preform formed from
multiple quasi-isotropic laminates 1352-QI and concentric laminates
1352-CON and bridging laminates 1352-CLW.
[0114] Specifically, in FIG. 4H or 5H, a part is built up from the
lowest layer or down from the highest layer, depending on the
printing type or approach. In FIG. 4H, an outer layer of fill
material 1350 is formed by a floor layer of fill material 1350 (the
outer layer may be 1-3 or more successive floor layers). As in
FIGS. 4E-4G, an internal sandwich panel is built of composite
material 1352, in this case as two quasi-isotropic sets 1352-QI
separated by infill material 1350-IF. In this case, a
quasi-isotropic set 1352-QI is formed by four parallel shells or
layers of anisotropic fill or composite fiber swaths, in which the
dominant direction of the fiber swaths is rotated by 45 degrees (in
a known manner for quasi-isotropic laminates of four layers)
between each layer (as noted herein, a quasi-isotropic set of
layers or shells tends be composed of 3 or more layers, the layers
together having a substantially isotropic stiffness behavior as a
laminate). As discussed, the quasi-isotropic sets 1352-QI are
deposited adjacent or proximate the top and bottom of the part to
provide a higher moment of inertia and bending stiffness. The
quasi-isotropic sets 1352-QI also provide twisting or torsion
stiffness. As shown, in contrast to FIGS. 4E-4G, in FIG. 5H outer
walls 1350-OW (including 1-3 or more beads of isotropic fill
material) optionally surround the sets 1352-QI of quasi-isotropic
layers so that the outer surface of the part is fill material
1352.
[0115] Further in contrast to FIGS. 4E-4G, the middle fill material
section 1350-IF is surrounded by outer concentrically deposited
anisotropic composite fiber swaths 1352-CON (e.g., as shown in
single layer form in FIG. 10A, 10B, or 10C). Each concentric fiber
swath fill section 1352-CON may be any number of concentric loops,
e.g., 1-10 or higher. Again, optionally, outer walls 1350-OW
(including 1-3 or more beads of isotropic fill material) optionally
surround the sets 1352-CON of quasi-isotropic layers and fill
material 1352 so that the outer surface of the part is fill
material 1352. In addition, the upper quasi-isotropic layer set
1352-QI is additionally covered by a roof fill of fill material
1350-R (again, 1-3 or more layers of isotropic fill material 1350).
In this manner, the entire outer surface of the part is optionally
sheathed in fill material 1352, but immediately adjacent the fill
material 1352 outer surfaces and displaced outwardly from a
centroid of the part, composite material 1352 is deposited to
increase effective moment of inertia in either anisotropically
deposited quasi-isotropic sets 1352-QI, and/or concentrically
deposited layers 1352-CON. Accordingly, outer contours, perimeters,
roofs, and floors of the 3D geometry, whether formed from layers or
shells of the 3D printing process or formed from walls, beads, or
swaths within a respective layer or shell of the 3D printing
process, are surrounded by an inner shell of composite material
1352. It should be further noted that one exemplary fill approach
for the concentrically deposited outer layers 1352-CON is
concentric loops, spirals, or offsets starting at an outer region
perimeter or contour and spiraling inward 1352-O.CON (outer
concentric fill).
[0116] In a variation of the part of FIG. 4H of a part having a
through-hole TH-H as shown in FIG. 4I, the general approach of FIG.
4H may be followed. In contrast, in FIG. 4I, the negative contours
or holes found in each layer having anisotropically deposited
and/or oriented fiber fill, quasi-isotropic sets of layers 1350-R,
and also found in each layer having anisotropically deposited
and/or oriented fiber fill, outer concentric layers 1352-CON, are
surrounded by these respective fills as well as isotropic, resin or
fill material infill 1350-F. However, immediately adjacent the
negative contour, a reinforcing column formed from an optional
inner wall of isotropic, resin or fill material 1350-IW and an
inner wall of anisotropically deposited and/or oriented fiber fill,
inner fill concentric layers 1352-I.CON (e.g., a tube of concentric
fiber and/or concentric fill material surrounding the through hole
TH-H). A non-through, terminating hole may be similarly structured
(e.g., the sides of the hole being similarly concentric inner fill
of fiber 1352-I.CON and/or inner wall resin or fill material fill
1350-IW, and the bottom of the hole being terminated with, as
permitting, a quasi-isotropic set 1352-QI and/or a roof layer
1350-R). As shown, the reinforcing column may extend through the
infill 1350-IF, the outer concentrically reinforced layers
1352-O.CON or 1352-CON, as well as the quasi-isotropic sets of
layers 1352-QI, such that two or three or more regions, fill
patterns, or toolpath generation approaches are used in these
layers, either in exclusive regions or in overlapping regions with
a set priority among generation rules. As an example, a layer
depicted in FIG. 10B includes an outer concentric fiber fill
surrounding both of an anisotropically deposited and oriented
infill IF that is one layer of a quasi-isotropic set, as well as an
inner concentric fiber fill surrounding a negative contour. The
reinforcing column formed from inner wall resin fill 1350-IW and/or
inner concentric fiber fill 1352-I.CON may surround more than one
hole or negative contour in each layer, e.g., two holes or three
holes, etc., or may be a reinforcing structure distributed among
different layers in a set or laminate. In this manner, negative
contours, through-holes, and similar structures, whether formed
from layers or shells of the 3D printing process or formed as walls
within a layer or shell of the 3D printing process, also are
surrounded by an inner shell of composite material.
[0117] It should be noted that the reinforcing columns may be or
include or one or more continuous fiber columns CRC injected,
inserted, drilled, drawn, lain, stitched, guided, or otherwise
deposited to join layers in the Z-axis direction and resist Z-axis
delamination; and need not surround a through-hole.
[0118] FIG. 5M-5N show structures similar to those of FIGS. 5I and
5J, in which continuous reinforcing columns bridging layers extend
through multiple layers. These continuous reinforcing columns may
be orthogonal/vertical/perpendicular to one or more 2D layers
LA.sub.n, at an angle to one or more layers, or curving through one
or more layers, or take paths joining orthogonal, angled, or curved
paths. For example, the reinforcing columns labeled may include
either concentric fiber surround, concentric fiber surround
combined with continuous reinforcing column(s), or just continuous
reinforcing columns extending parallel to the through hole. As
shown in FIG. 5M, a continuous reinforcing column CRC bridging
layers may extend along the internal surface of a through-hole; may
be embedded in injection overmolding as in FIGS. 5H-5J, or may
extend at an angle through multiple layers but not the entire part
(e.g., having been placed during the successive deposition of
multiple layers). As shown in FIG. 5N, a continuous reinforcing
column CRC may extend at an angle through many layers or the part,
may extend through reinforcing columns in intermediate layers; or
between or through or into sandwich panel laminate layer groups
forming quasi-isotropic laminates and forming sandwich panel
internal structures, or may be arranged to overlap, spanning only
2-10 layers each but each layer being "connected" by offset or
staggered continuous reinforcing columns CRC.
[0119] In a further variation of the part of FIG. 4H of a part
having an internally dense fiber infill pattern, as shown in FIG.
4J, the general approach of FIG. 4H may again be followed. In
contrast, in FIG. 4J, a matrix or cellular arrangement of
concentrically filled anisotropic material walls (of
anisotropically deposited and oriented fiber material) 1352-CLW is
arranged within the part to provide increasing fiber density and/or
stiffness and/or crushing resistance. The pattern of cell walls
1352-CLW may be a honeycomb formed from reinforcement formations.
Further, the pattern of cell walls of anisotropically deposited and
oriented fiber material 1352-CLW may be formed by crossing or
non-crossing outer concentric or inner concentric fills 1352-O.CON
or 1352-I.CON. The pattern of cell walls of anisotropically
deposited and oriented fiber material 1352-CLW may be a mirroring,
repeating, orthogonally varying, or complementary arrangement. The
cells are filled with infill material 1350-IF, in a dense or sparse
arrangement. Additionally in contrast, in FIG. 4J, one or more
intervening sets of quasi-isotropic fill 1352-QI (of
anisotropically deposited and oriented fiber material) may be
formed as an inner wafer other than at the top and bottom regions
remote from the centroid. As shown in FIG. 4J, in contrast to FIG.
4H, the one or more intervening sets of quasi-isotropic fill
1352-QI (of anisotropically deposited and oriented fiber material)
may be further surrounded by an outer concentric fill 1352-O.CON
(in order to provide a consistent outer shell) or may instead fill
a layer to an outer wall of resin material 1350-OW (as with the
upper and lower sets of quasi-isotropic fill 1352-QI.
[0120] It should be further noted that the structures of FIGS. 4I
and 4J may be combined by using exclusive regions or regions having
a priority among them, e.g., through-holes TH-H may penetrate
through or partially through a matrix or cellular arrangement of
fiber fills 1352-CLW and/or 1352-QI combined with fill material
1350-IF and be nonetheless surrounded by wall-reinforcing tubes of
fiber and/or fill material, e.g., as shown in FIG. 10B.
[0121] As shown in each of FIGS. 4H-4J, at least one (e.g., 1-3 or
more) roof layer of resin or isotropic material or infill material
1350-R, solid, filled or densely filled in ox-row or other packed
fashion, may be printed above a set of resin or fill material
infill 1350-IF. The infill 1350-IF may in some cases be a sparse
honeycomb pattern, and the solid, filled or densely filled roof
layer(s) 1350-R provide a complete shell or layer surface upon
which the anisotropic fiber swaths may be compressed and fused.
[0122] As shown in FIGS. 4A-4J, the three-dimensional geometry of
the parts shown in FIGS. 4A-4J may be sliced into shells or layers
as described herein. For each of a set of shells or layers defining
a portion of a 3D printed part, first isotropic fill tool paths
such as 1322, 1328, 1330, 1344, 1350, 1350-R, 1350-OW, and/or
1350-IW may be generated for controlling an isotropic solidifying
head (e.g., head 18 or 1800 or 1616) to solidify, along the
isotropic fill tool paths, a substantially isotropic fill material
such (e.g., material 18a or 1604). For each of an anisotropic fill
subset of the set of shells or layers defining the portion of the
3D printed part (e.g., the different fiber fills throughout a
part), first anisotropic fill tool paths (e.g., 1352-QI or
1352-O.CON or 1352 I.CON) may be generated for controlling an
anisotropic solidifying head to solidify, along the anisotropic
tool paths, a substantially anisotropic fill material having an
anisotropic characteristic oriented relative to a trajectory of the
anisotropic fill tool path. As shown with reference to FIGS.
10A-10C, from among the set of shells or layers defining the
portion of the 3D printed part, a selection of an editing subset of
shells or layers may be received, the editing subset including at
least part of the anisotropic fill subset. For each shell or layer
of the editing subset, one of second isotropic fill toolpaths
different from the first isotropic fill toolpaths and second
anisotropic fill toolpaths different from the first anisotropic
fill toolpaths may be regenerated.
[0123] Similarly, a printer for additive manufacturing of a part
may include an anisotropic solidifying head (e.g., head 10, or 199)
that solidifies, along anisotropic fill toolpaths, fiber swaths
from a supply of anisotropic fiber reinforced material including a
plurality of fiber strands extending continuously within a matrix
material, the fiber swaths having an anisotropic characteristic
oriented relative to a trajectory of the anisotropic fill tool
paths. An isotropic solidifying head (e.g., head 18 or 1800 or
1616) may solidify, along isotropic fill toolpaths, a substantially
isotropic material from a supply of solidifiable isotropic
material. A motorized drive as shown in FIGS. 1A-1D and 2A-2H may
relatively move at least the anisotropic deposition head and a
build plate supporting a 3D printed part in three or more degrees
of freedom. A controller 20 may be operatively connected to and
configured to control the motorized drive, the anisotropic
solidifying head and the isotropic solidifying head, and may
control these to build the 3D printed part by solidifying the
isotropic material along the isotropic fill tool paths, and/or
solidifying the anisotropic fill material in fiber swaths tracking
a non-concentric set (e.g., quasi-isotropic set 1352-QI, or any of
the non-concentric complementary sets in FIGS. 12-14, all suffixes
inclusive) of the of anisotropic fill tool paths for at least a
first sequence of parallel shells. Further, the controller may
control these elements to solidify the anisotropic fill material in
fiber swaths tracking an outer concentric set (e.g., 1352-CON, or
any of the concentric layer types shown herein) of anisotropic fill
tool paths for at least a second sequence of parallel shells. Each
of the non-concentric set and the outer concentric set of
anisotropic tool paths may be located at least partially radially
outward from the centroid of the 3D printed part, as shown in FIGS.
4H-4J.
[0124] With respect to the described structures, including all of
those discussed with respect to FIGS. 4A-4J and 5A-5J, the
reinforcement volume may include a combined volume of reinforcement
fiber and a resin matrix within which the reinforcement fiber is
additively deposited, and the reinforcement volume is less than 20
percent of the entire reinforced molding. With reference to
embodiments shown herein, the continuous reinforcing fiber may be
additively deposited simultaneously by a plurality of deposition
heads (i.e., in parallel or substantially in parallel).
[0125] As discussed with reference to FIGS. 4A-4J and 5A-5J, the
method of fabricating a continuous fiber reinforced injection
molding, may include forming a first shape in a support material to
form a support preform, e.g., using the structures of FIGS. 1A-1D,
2A-2H, and 3. As shown in FIG. 6B, the printer may additively
deposit continuous reinforcing fiber in a second shape following a
contour of the support preform to form a continuous fiber
reinforcement preform. Further as shown in FIG. 6B, the continuous
fiber reinforcement preform may be located within a mold of a
molding apparatus. The mold may be loaded with flowable and
substantially isotropic molding material, and the mold material may
be hardened the molding material to overmold the continuous fiber
reinforcement preform. As a result, a fiber reinforced molding or
molded article is formed, in which an internal continuous fiber
reinforcement preform is surrounded by a hardened substantially
isotropic molding material.
[0126] The support preform may be formed from, and/or the support
material may include, a soluble material (e.g., a polymer and/or
salt soluble in a solvent), and further comprising dissolving the
preform. The support preform may be dissolved before locating the
continuous reinforcement fiber shell within the mold. The support
preform may also be dissolved by the mold loading, where the
support preform material is displaced, melted, or dissolved by the
mold loading. The support preform may also be dissolved after the
mold material is hardened (in which case at least one part of the
preform shape may extend to be contiguous with a surface of the
fiber reinforced molding). The support preform may be dissolved in
a combination of these steps (e.g., partly or in one part before
location in the mold, and partly or in a second part after the
reinforced molding is hardened).
[0127] The support preform may be formed in a rotationally
symmetric shape or mandrel for winding the continuous fiber
reinforcement preform. Alternatively, the support preform is formed
in a non-looped shape permitting winding the continuous fiber
reinforcement preform upon the support preform. In this case, a
robot arm supporting the fiber deposition printhead may reach
concave areas of the support preform to deposit or wind the
continuous fiber reinforcement preform.
[0128] The support preform may be injection molded. The support
preform may be injection molded as a honeycombed structure, with a
contiguous outer surface shell suitable as a winding substrate
(alternatively, without the contiguous outer surface shell). The
support preform and continuous fiber reinforcement preform may be
formed in successive additive and injection molded stages. For
example, a honeycomb structure I-HW may be additively formed from
either a substantially isotropic material additive deposition or by
fiber deposition, followed by insertion of the honeycomb I-HW into
an injection mold for overmolding a substantially isotropic
material contiguous outer surface shell of the support preform,
followed by winding or surface-following raster/coverage continuous
fiber deposition to cover the contiguous outer surface shell of the
preform as the continuous fiber reinforcement preform, followed by
one of additive or molding deposition of a final outer shell of
substantially isotropic hardened material of the reinforced
molding. Winding may use at least two translational and one
rotational relative degrees of freedom between a continuous
reinforcement fiber deposition head and the support preform, and/or
or surface-following coverage additive deposition may use at least
three translational and one rotational relative degrees of freedom
between a continuous reinforcement fiber deposition head and the
support preform.
[0129] The second shape and/or the continuous fiber reinforcement
preform may embed at least one sandwich panel structure E-SP1
(e.g., a first laminate of fiber reinforcement L-CFL, an
intermediate honeycomb I-HW or solid material either of fill
material or fiber reinforcement, and a second laminate of fiber
reinforcement U-CFL substantially parallel to the first laminate
but spaced therefrom). As shown in FIGS. 5K and 5L, the sandwich
panel structure E-SP1 may be a foldable structure, e.g., with the
second laminate U-CFL being continuous and the first laminate L-CFL
and the intermediate material I-HW having linear gaps formed
therein opposite fold line(s) in the second laminate to form hinges
LH1 (e.g., living hinges if the fiber reinforcement is readily
bent, or separation/snapping guides if the fiber reinforcement is
more brittle). Optionally the preform itself embeds at least one
sandwich panel structure E-SP1.
[0130] The support preform may be relatively moved in at least one
rotational degree of freedom with respect to a deposition head that
additively deposits the continuous reinforcing fiber in the second
shape following the contour of the preform to form the continuous
fiber reinforcement preform.
[0131] The overmolding and/or molding may be performed at a molding
material pressure which removes air voids within the fiber
reinforcement matrix material. The continuous fiber reinforcement
preform may be bent or deformed from its formation shape to a
deformed shape within the mold. Two or more continuous fiber
reinforcement preforms may be bonded to one another before location
within the mold. The support preform may be bent or deformed from
its formation shape to a deformed shape for depositing the fiber
reinforcement to form the continuous fiber reinforcement
preform.
[0132] The mold may be an injection mold, and pack pressure of the
injection molded material during molding compresses and/or
consolidates the fiber reinforcement preform into a final shape
and/or removes voids within the fiber reinforcement preform. At
least in the case where the mold is an injection mold, heat from
the injected mold material remelts a matrix material of the fiber
reinforcement preform.
[0133] The fiber deposition or winding of the continuous fiber
reinforcement preform may be additively deposited thermoplastic
continuous fiber reinforced prepreg tape or prepreg tow having a
width at least three times its height.
[0134] The described techniques may further include arranging a
wide prepreg sheet against or on the soluble preform before
additively depositing continuous fiber tow or tape thermoplastic
prepreg.
[0135] The described techniques may further include applying a
vacuum during formation of the continuous fiber reinforcement
preform and/or the molding to remove voids. The vacuum may be
applied at the part perimeter and if the molding material is
injected or pressurized into the middle of the part. The continuous
fiber reinforcement preform may include ribs or air channels to
help air escape.
[0136] In a variation, in a method of fabricating a continuous
fiber reinforced injection molding, continuous reinforcing fiber is
additively deposited by the devices of FIGS. 1A-1D, 2A-2H and 3 in
a second shape following a contour to form a first continuous fiber
reinforcement preform as a flat or curved "A" panel. The first
continuous fiber reinforcement preform may be located within a mold
of a molding apparatus along a first mold plate, and a second mold
plate formed with a honeycombed cavity may be located opposite the
first continuous fiber reinforcement preform. The mold may be
loaded with a flowable and substantially isotropic molding
material. The molding material may be hardened to overmold a
honeycomb of the substantially isotropic molding material against
the continuous fiber reinforcement preform, thereby forming a fiber
reinforced molding including a hardened substantially isotropic
molding material honeycomb integrated with the continuous fiber
reinforcement preform (optionally the continuous fiber
reinforcement preform is further enclosed within the molding
material). Subsequently, a complementary "B" side reinforced fiber
panel may be deposited by continuous fiber deposition against the
honeycomb. Alternatively, a "B" side may be formed as a mirror
process (e.g., first a continuous fiber reinforced preform, then a
honeycomb overmold) then joined or overmolded
honeycomb-to-honeycomb (preferably with other locating or indexing
or interlocking features). Further alternatively, the honeycomb
mold cavity may be formed in as a soluble preform upon which the
fiber reinforced preform is deposited, simplifying the second mold
plate to the match contours of the honeycomb soluble preform shape.
The soluble material is removed before the A and B sides are
joined.
Tubular Framework Example
[0137] As shown in FIGS. 6A and 6B, in composite lay-up of a
bicycle frame, in step CL2 mandrels SMAN-N may be prepared for one
or more (N) junctions of tubes (e.g., head tube joining the top
tube and down tube; bottom bracket joining the seat tube, down
tube, and chain stay; or seat post joining the top tube, seat tube,
and seat stay; or rear dropout joining the seat stay and chain
stay). Often, as in step CL4, seven (N=1 . . . 7) parts are laid up
and compression molded about mandrels SMAN-N or other defining
shapes as in steps CL6 and CL8 into molded components COMP-C and
finally as in step CL10 bonded into a unitary frame FRM (left and
right dropouts, bottom bracket assembly, seat post assembly, head
tube assembly, and v-shaped chain stay frame, and v-shaped seat
stay frame).
[0138] As shown in FIGS. 6C and 6D, in an example of contrasting
in-mold assembly of a reinforced molding RM2 formed by resin
overmolding OV3a a fiber reinforced preform 1342a, in the present
embodiments, an additively deposited soluble preform 1340a may be
printed as in step AP2 to take the place of a steel mandrel that
defines the shape and surfaces of a frame component formed as a
reinforced molding RM2, and steps may take place in a different
order or different form.
[0139] For example, each component (e.g., head tube junction
component) may have a soluble mandrel (soluble preform 1340a)
additively deposited (3D printed) by the printer 1000 as in step
AP2. Pressurizable nylon bladders or heat-activated foam inserts
may be integrated at this time, or may have been printed over (or
printed in an appropriate material). In a second stage as in step
AP4, a printhead 1402 deposits and/or winds and/or wraps continuous
fiber over the soluble preform(s) 1340a including bladders or
heat-activated foam inserts as appropriate, including printing
inner or outer guard layers of plastic about the continuous fiber.
During overmolding, bladders or heat-activated foam may help
pressurize the continuously wound fiber, optionally against a mold
wall, to eliminate internal voids.
[0140] At this stage, as shown in FIGS. 6C and 6D, a component
assembly includes a fiber reinforcement preform 1342a wrapped about
a soluble preform, optionally with the pressure-increasing features
integrated. The soluble preform 1340a, in weight-sensitive
applications, may be dissolved away as in step AP6. In other cases
the role of the soluble preform 1340a to allow winding of the
reinforcement preform 1342a is instead taken by a honeycomb, foam,
or low-density preform that will remain in the final assembly (in
addition to any heat-activated mold cores). The pressure-increasing
features may be left in place.
[0141] As in step AP8, a component including at least the fiber
reinforcement preform 1342a may be placed inside a mold MLD-2
substantially in the shape of the final reinforced molding RM2
(absent molding features such as sprues, runners, etc.). As in step
AP8, the mold MLD-2 is closed, and any bladders may be connected to
pressurized air fittings. As in step Ap8, the mold MLD-2 is filled
with molding material and pressurized or heated as appropriate for
the molding technique (e.g., injection molding). Pressure is
increased by the bladders and/or reacting heat-activated foam
cores. If necessary, curing is performed on the reinforced molding
RM2.
[0142] In an alternative, before or instead of overmolding the
fiber reinforced preform 1342a, a heat-shrinking tape may be
printed or wound about the fiber reinforcement preform 1342a. In
this case, the soluble preform 1340a may be left to provide
internal resistance versus pressure created by heating and/or
curing the heat-shrinking tape. If the component 1342a is not to be
overmolded, once cured, the tape may be removed and the hardened
part may be sanded to its final diameter and shape (additional
layers may be additively printed before sanding and/or additively
sprayed after sanding). As in step AP10, the components may be
bonded into a whole (e.g., frame FRM).
[0143] In this framework example, as with any frame or truss
example, the junction components, whether they have long arms
extending from them or short, are distinct from the entire frame in
that they can be wound or externally traced or printed without a
weaving operation, i.e., the external surface does not connect with
itself in a loop or ring (although the internal surface may be a
hollow tube or a junction of hollow tubes).
[0144] It should be noted with this example, as with any frame or
truss example, that the overmolding may be performed on each
junction component, and then the reinforced moldings RM2 or 1342a
joined (e.g., by nesting tubes or shapes, smaller diameter within
larger diameter, and adhesive or fastener bonding). In an
alternative, the fiber reinforcement preforms RM2 or 1342a may be
first joined to one another (again by nesting tubes or shapes,
smaller diameter within larger diameter or otherwise interlocking,
and adhesive or fastener bonding), and then the joined assembly
overmolded in an entire assembly mold (not shown).
[0145] As discussed herein with reference to the continuous fiber
reinforcement preform, in the case of one, two, or more holes,
airflow holes, negative contours, embedded contours, or overmolded
contours in any reinforced molding component, in many cases
different kinds of reinforcement will be possible. For example:
(1) Reinforcement of inner walls and hole walls may closely follow
the walls, with or without layers of fill material shielding the
innermost wall to prevent print-through of fiber. "Holes" include
negative contours and embedded (e.g., overmolded) contours. (2)
Reinforcement of outer walls may closely follow the walls, with or
without layers of fill material shielding the innermost wall to
prevent print-through of fiber, e.g., "outer" reinforcement
formations. (3) Reinforcement may extend along load lines or stress
lines, e.g., outer reinforcement formation. (4) Reinforcement for
tension load purposes may include multiple straight composite
swaths between the sites at which the tension load is supported.
(5) Reinforcement for torsion, torque, or pressure load purposes
may include multiple circular composite swaths along directions of
hoop stresses. (6) Reinforcement for compression load purposes may
include multiple neighboring composite swaths to provide low aspect
ratio cross sections and/or squat structures, and/or anchors at
1/2, 1/3 fractional, e.g. harmonic lengths to guard vs. buckling;
and/or e.g., more composite swaths for compression struts than for
tension struts. (7) Reinforcement for twisting may include angular
cross bracing in triangle or X shapes. (8) Reinforcement for
bending or combination load purposes may include embedded high
moment of inertia (cross section) structures such as sandwich
panels, tubes, boxes, I-beams, and/or trusses formed from embedded
composite swaths. These may be made in layers spaced from the
centroid of the component cross section, or in outer toolpaths
spaced from the centroid of the component cross section, depending
on the load and the orientation of the reinforced molding during
printing.
[0146] In general, it is preferable to apply strategies in which
compression and/or layer height interference of an overlapping or
crossing layer (e.g., which may correspond in part to layer height)
may be set to deposit two highly compressed layers of composite
swaths 2c-2, 2c-1, and to square up corresponding fill material 18a
at a height of close to twice the highly compressed composite swath
height. It may also be preferable to permit or create crossings of
toolpaths of composite swaths 2c-1, 2c-2, and to square up
corresponding fill material 18a at a height of close to twice the
highly compressed composite swath height. Crossings of highly
compressed composite swaths with one another, and/or crossings of
highly compressed composite swaths with lightly compressed
composite swaths may be used. As shown in the CFF patent
applications, toolpaths for deposition of core reinforced fiber may
be generated within contours and sub-contours, and in order to
maintain parallel paths, and often follow offsets of the contours
and sub-contours.
[0147] It should be noted that only some toolpaths, composite
swaths 2c, and/or multi-swath fiber tracks form "loops", closed
"loops", or "crossing turns" as continuously deposited in a single
layer of an additive manufacturing process. FIG. 7A shows crossing
points or crossing turns of two fiber swaths in two forms. Any of
these loops, crossing points, closed loops, or crossing turns may
form a portion of a continuous fiber reinforcement preform as
discussed herein, and may be printed together with fill material
and/or onto soluble material or a soluble preform.
[0148] FIGS. 7A-7F show three examples of crossing turns, i.e.,
loops or crossed loops that are made about internal geometry, such
as a hole within a layer (a hole represented as a negative
contour); and FIGS. 7B-7C show two examples that may be crossing
turns but could also be distributed between two layers. Each
represented crossing turn may depict either a single composite
swath, or a multi-swath track of parallel composite swaths. "Track"
in this context means closely arranged (often touching), and often
parallel swaths, which may be printed concentrically, spirally, or
in parallel. A track need not have all swaths parallel throughout
its entire length. The followed hole H0 is in each case circular,
but may be any shape having a perimeter that can be followed by a
toolpath (e.g., hexagonal or square). In FIGS. 7A-7F, single layer
or double layer overlaps (i.e., locations where a swath or
multi-swath track is directly over an underlying swath or
multi-swath track within the same printing layer) are depicted as
darker shade and single swaths or multi-swath tracks as
comparatively lighter shade/transparency). In several cases,
parallel or neighboring entering and exiting swaths or multi-swath
tracks are depicted as cleanly separated and cleanly on either side
of the center line, but may overlap and/or cross a center line.
[0149] Crossing points made in a same layer, which may be one
continuous composite swath or different composite swaths, may be
referred to as "intra-layer" crossing points. Crossing points made
between two layers, which in most cases may be different continuous
composite swaths are referred to as "inter-layer" crossing points.
It should be noted that a raster pattern crossed with another
raster pattern on another layer produces a dense array of
inter-layer crossing points, but these crossing points do not
particularly reinforce any neighboring feature or contour. As such,
a single inter-layer crossing point (e.g., such as that in FIG. 7E
or 7F) or a small group of inter-layer crossing points are herein
discussed as "isolated crossing points". As discussed herein,
intra-layer crossing points tend to create protrusions at the
crossing point layers in the case of composite swaths, less so in
the case of extruded fill material alone; while inter-layer
crossing points do not create such protrusions unless otherwise
described.
[0150] FIG. 7B shows a crossing turn made about a hole H0--such as
a lace aperture, airflow aperture, mesh gap, through-hole, in
upper, insole, sole, or orthotic--in which (i) the swath or
multi-swath track approaches the hole H0 approximately parallel to
an (imaginary) line through its center, axis or centroid, (ii)
crosses the line to an opposing side of the hole, (iii) closely
follows the perimeter of the hole H0, (iv) crosses itself and the
line, and (v) departs from the hole H0 approximately parallel to
itself and the line. A diamond-shaped overlap PR13 is formed, which
may extend above the height of a single swath 2c. A buffer-zone
BF15 may be created or marked about the overlap. This type of
crossing turn closely follows and reinforces a hole wall for
greater than 300 degrees of arc, and may be the end loop of a
larger pattern. It should be noted that the entering and exiting
swaths 2c or multi-swath tracks are depicted as cleanly separated
and cleanly on either side of the center line, but may overlap
and/or cross the center line.
[0151] FIG. 7C shows a crossing turn made about a hole H0--such as
an airflow aperture, mesh gap, or through-hole--in which (i) the
swath 2c or multi-swath track approaches the hole H0 approximately
parallel to an (imaginary) line parallel to a tangent to a
perimeter of the hole H0, (ii) crosses the line to follow a
perimeter of the hole H0, (iii) closely follows the perimeter of
the hole H0, (iv) crosses itself and (v) departs from the hole H0
approximately along the same line from which it approached,
continuing the entry toolpath. A C-shaped overlap BF16 is formed,
which may extend above the height of a single swath 2c. A
buffer-zone BF16 may be created or marked about the overlap. This
type of crossing turn closely follows and reinforces a hole wall
for greater than 360 degrees of arc, and may be a middle loop in a
larger pattern. It should be noted that the entering and exiting
swaths 2c or multi-swath tracks are depicted as along the same
line, but may be offset or exit at an angle to the approaching
swath 2c or track. FIG. 7D shows a crossing turn similar to FIG.
7C, except that (i) the approaching swath 2c or multi-swath track
is more offset from the (imaginary) tangent to the hole, and so
turns slightly in an S-shape to approach the tangent at an angle,
and similarly (v) departs from the hole H0 in a manner mirroring
the entry. The C-shaped overlap PR15 and buffer zone BF17 may be of
different or more concave shape.
[0152] FIGS. 7E and 7F show overlaps or crossing points adjacent a
hole--such as an airflow aperture, mesh gap, or through-hole--in
which a bight, open loop or touching loop may be made away from the
reinforced hole H0 from which the swath 2c or multi-swath track
returns toward the hole H0. A different swath 2c or multi-swath
track within the same layer may also form the return path. In the
case of FIG. 7E, (i) the swath 2c or multi-swath track approaches
the hole H0 approximately parallel to an (imaginary) line through
its center, axis or centroid, separated by approximately a track
width, (ii) follows the perimeter of the hole H0, then (iii)
crosses the line to an opposing side of the hole H0, and (iv)
departs from the hole H0 approximately parallel to itself and the
line. Upon returning from the pattern away from the hole H0, the
swath 2c or multi-swath track (v) crosses itself and the line to an
opposing side of the hole H0, (vi) closely follows the perimeter of
the hole H0, and (vii) departs from the hole H0 approximately
parallel to itself and the line, again separated by a swath or
track width. A diamond-shaped overlap PR16, PRis formed, which may
extend above the height of a single swath. A buffer-zone BF18, BF19
may be created or marked about the overlap PR16, PR17. This type of
crossing point closely follows and reinforces a hole wall for 240
degrees of arc, and may be the end loop of a larger pattern. A
crossing point may be complemented by a vertically mirrored version
of itself in a complementary layer without stacking overlaps or
buffer zones. A crossing point may, in contrast, approaches the
hole closer to the center line and crosses itself at both sides of
the hole.
[0153] At least the following strategies are available for
accommodating the protrusion PR in a reinforced molding 14 where
successive layers are nominally of a consistent height--for
example, 0.1 mm height. These strategies would in many cases be
applied during slicing and toolpath or reinforcement formation
planning for the reinforced molding 14, in part so that inter-layer
accommodations may be made. Where the protrusion PR scale (e.g.,
height and/or width) is modeled/predicted/empirically known and
stored as an absolute or relative value or a function of system
variables, the overlap PR or a buffer zone BF larger than the
overlap PR may be marked or planned in the current layer LA.sub.n.
The protrusion or protrusions may be one or more continuous
transverse or fiber columns injected, inserted, drilled, drawn,
lain, stitched, guided, or otherwise deposited to join layers in
the Z-axis direction and resist Z-axis delamination. These
transverse columns may be orthogonal/vertical/perpendicular to one
or more 2D layers LA.sub.n, at an angle to one or more layers, or
curving through one or more layers, or take paths joining
orthogonal, angled, or curved paths.
(1) Subsequent path planning in the same layer (layer LA.sub.n)
may: (a) avoid crossing the overlap within the same layer (e.g.,
layer LA.sub.n by planning toolpaths which do not cross the
overlap, although the new toolpaths may form a crossing point,
jump, crossed loop or crossing turn forming a new overlap). (b)
plan new toolpaths within the same layer (layer LA.sub.n) separated
by more than the buffer zone.
[0154] Subsequent or integrated path planning for a new, adjacent
layer (LA.sub.n+1) adjacent to the layer in which protrusions are
formed (layer LA.sub.n) may:
(c) increase the previous layer height (of layer LA.sub.n) in the
overall slicing approach, and/or decrease the current layer height
(of layer LA.sub.n+1). This is most applicable when no composite
swaths, or composite swaths which do not cross and create
protrusions, will be formed in the current layer. (d) path plan
composite swaths to avoid overlaps and/or buffer zones in the layer
below (layer LA.sub.n); (e) path plan a complementary or partner
patterns in the current layer (LA.sub.n+1) which provide
complementary functionality to a pattern in an adjacent or previous
layer (layer LA.sub.n).
[0155] FIGS. 8A-8D show patch fills and concentric fills that may
be used to fill in reinforcement regions as disclosed herein. Any
of these patch fills or concentric fills may form a portion of a
continuous fiber reinforcement preform as discussed herein, and may
be printed together with fill material and/or onto soluble material
or a soluble preform.
[0156] FIG. 8A shows a variation of FIG. 8B in which the toolpath,
composite swath pattern, or reinforcement formation 99E is of
offset approach, with crossovers OF02 at the opposite side of the
reinforced molding from the spiral start and end of the spiral
strategy toolpath of FIG. 8B. FIG. 8B shows a toolpath, composite
swath strategy or reinforcement formation 99F, as a spiral
strategy, excepting that FIG. 8B shows a paired square hole H2 and
circular hole H5.
[0157] FIG. 8C shows a single layer of a densely filled square
plate of four long side members, with an aperture, space for a
stretchable substrate, hole or negative contour in the middle. In
FIG. 8C, as shown, a lengthwise raster fill reinforcement formation
99X surrounds the contour or region in the middle. There are many
turns in the raster pattern, and two gaps GAP1 and GAP2 (which may
also be stress concentrations, starts, or stops are formed. GAP1 is
formed where the pattern changes regional groups, and GAP 2 is
formed at the end of the composite swath 2c. These gaps may also
occur if the composite swath 2c length is not perfectly predicted
or measured. Within the layer, the gaps may be filled with (i) fill
material 18a, (ii) lengths of composite swath 2c which do not
continue the raster fill (e.g., gap filling patterns, which may be
concentric, wall or region following), (iii) and/or with
overlapping composite swath 2c or protrusion PR. E.g. in order to
fill the GAP1 or GAP2 with overlapping composite swath 2c, each
raster pattern would be widened to overlap (e.g., wherein the gaps
are closed with protrusions PR, which may be varied in position
among layers as discussed herein). In FIG. 6D, two superimposed
reinforcement formations 99X, 99X layers are shown, where the
reinforcement formation 99X is rotated by 90 degrees, optionally in
the subsequent layer. The reinforcement formation 99X may be
rotated at 90 degrees, then again, in an additional two layers to
continue to change the position of the gap, stress concentration,
starts, or stops. Optionally, the pattern is rotated by 45 degrees
in some intervening layers.
[0158] FIG. 9 depicts a flowchart for configuring 3D printer
controller and/or slicer controller operations to permit
multi-layer rule handling, i.e., setting rules for groups of layers
or regions and changing the members of the rule groups. This
routine may be used in preparing a continuous fiber reinforcement
preform. In step S7602, updating or re-slicing of toolpaths from
any toolpath, region, or layer setting change is carried out. In
step S7604, as necessary, any changes in the currently displayed
graphical representation resulting from an updated toolpath (e.g.,
change of a layer, group of layers, or volume) are processed and
displayed. In step S7606, as shown in FIGS. 10A-10C, graphical
representations of rule groups and end points of the rule groups
are rendered as orthogonal bar(s) parallel to an edge of a display.
In step S7610, the display area of the orthogonal bar is monitored
for a pointer PO1 action selecting, an entire group, an endpoint of
a group, or a new range within and/or adjacent an existing group,
and the input handled according to the particular case.
[0159] When an entire group is selected and retaining focus, in
step S7613, one or more interface elements (e.g., a drop down menu,
slider, text or number box, radio button, check box) are monitored
for input reflecting a change in the rule applied to the selected
entire group, and the rule change is captured from the input. When
an endpoint of a group (e.g., a group will have at least two
endpoints, but may have any number for non-contiguous groups) is
selected per step S7614 and retains focus, in step S7618 one or
more interface elements (e.g., a drop down menu, slider, text or
number box, radio button, check box) are monitored for input
reflecting a change in the position of the endpoint, and therefore
a change in the members in the set of layers or regions of the
group, and the rule change is captured from the input. When a new
range is formed or is selected per step S7612 and retains focus, in
step S7616 one or more interface elements (e.g., a drop down menu,
slider, text or number box, radio button, check box) are monitored
for input reflecting a change in the rule applied to the selected
entire group, and the rule change is captured from the input and
the new group created in step S7620. If the new group is within a
previously existing group, three new groups may be created (e.g.,
the new group selected as well as one or two fractional remainder
groups reflecting that part of the previously existing group which
was not changed). In each case, in step S7622, the rule change is
applied and the process proceeds back to step S7602 to update the
toolpaths per the rule change or range change, as well as the
graphical representation (7604) and representation on the
orthogonal bar (S7606).
[0160] FIGS. 10A and 10B show an embodiment of the orthogonal layer
topography bar OB1.2a-OB1.2c. This interface may be used in
preparing a continuous fiber reinforcement preform. As shown and
described, like elements throughout the figures are often like
numbered, but some numbers may be omitted in these views. The
description of elements of substantially identical appearance in
other drawings generally applies to FIGS. 10A and 10B, including
the described associations among displays, processes, and
databases. The orthogonal layer topography bar OB 1.1 is described
in the context of exclusive rule sections RS1-RS4 (although it may
be used with non-exclusive rule sections), FIGS. 10A and 10B are
described in a context of rule sections RS7-RS9 which may overlap.
As shown in FIGS. 10A and 10B, the orthogonal layer topography bar
OB1.2 is formed as a set of independent orthogonal subbars
OB1.2a/RS7 through OB1.2c/RS9, each subbar OB1.2a through 1.2c or
rule section RS7 through RS9 being associated with adjustment
handles at each end of each section.
[0161] As shown in FIG. 10A, extending across a lower part of the
display 1002, the volume fill graph section VFG-B display element
is a topography representation of approximately 150 layers. As
shown by the position of the thumb TH1, the currently displayed
layer is layer 6 within rule section RS9, within which layers 4-44
and 107-147 include approximately 25% fiber fill as shown by the
volume fill graph section VFG4, VFG5. As shown, rule section RS9 is
non-contiguous in two parts, i.e., the display, interface, and
database may record and apply customized or default rules
(toolpath, region, or layer) to non-contiguous but associated
ranges of toolpaths, regions, or layers. Rule section RS9 is
selected via pointer PO1, and is highlighted between rule
adjustment handles HA9 and HA10, and again between handles HA11 and
HA12, with annotation AN2 indicating that the common ranges of the
rule of the selected rule section is layers 4-44 and 107-147, and
annotation AN3 indicating that the rule selectable for an
associated "Volume 1" (e.g., a volume formed by the height of the
layers 4-44 and 107-147 and either an entire layer or a region
within a layer) is a "CONCENTRIC FILL" rule (from among fiber fill
types, with the selectable rule itself being changed, e.g., via the
selection panel 1004). Reflecting the current index layer, the
depicted model shows concentric fill of about 25 percent fiber
content in layer 6 within the rule ranges.
[0162] FIG. 10B shows a set of changes from the state of FIG. 10A
of the display state as well as corresponding processes and
databases. In particular, FIG. 10B shows the addition of two
additional rule sections RS8 and RS7 to the displays, processes,
and databases. Rule set RS8, for example, is a rule applicable from
layer 3 to 150, in this case, for example, a rule prescribing the
concentric, inner negative contour following hole wall
reinforcement pattern HR, surrounding the through-hole W04 which
passes through the part in each layer. Rule set RS7, for example,
is a rule applicable in layers 35 through 70 and 100 through 125,
in which isotropic fill is prescribed for a particular defined
region or volume, or for example for any area which is not
otherwise subject to a higher priority rule (not that the priority
of the rules could be adjusted, e.g., by restacking (rearranging)
the rule layers RS7, RS8, RS9 such that the priority order is the
order of the stack). As shown in FIG. 10B, the position of the
thumb TH1 is shifted to layer 61. The currently displayed layer is
layer 50 spanning rule sections RS7, RS8, and RS9, within which the
displayed layers includes the 25% volume outer perimeter following
concentric fill of rule RS9, the 10% volume circular negative
contour perimeter following concentric fill of rule RS8, and the
75%+ volume isotropic fill IF, at this level a 45 degree
boustrophedon fill, of rule RS7. As noted, an isotropic fill IF
will have a different angle depending on the level (e.g., rotating
among 0, +45, -45, and 90 degrees to form repeating quasi-isotropic
wafers). As shown by the volume fill graph section VFG6, the 10%,
25%, and 75% volume fill are additive on layers where rules
overlap, indicating the simultaneous operation of the rules.
Interface element IE1 is selected via pointer PO1, and is shown in
a configuration in which the layers indicated by annotation AN2,
i.e., layers 35-70 and 100-125, may have a common rule selected for
them, in this case isotropic fill. Similarly to the FIG. 10B,
annotation AN2 indicates that the rule is selectable for an
associated "Volume 3" (e.g., a volume formed by the height of the
layers 35-70 and 100-125, and either an entire layer or a region
within a layer) is an "ISOTROPIC FILL" rule (from among fiber fill
types, with the selectable rule itself being changed, e.g., via the
selection panel 1004).
[0163] In the case where rules may "overlap" per layer, this may
occur in at least two forms. First, within a layer, different
regions may have independent rules (e.g., as shown in FIG. 10B,
each of three regions--outer perimeter of three fiber rings, hole
reinforcement of three fiber rings, and boustrophedon fill of the
remainder--may be defined by region). Second, for any path, region,
layer, or volume, rules may take precedence by a predetermined
priority. One possible priority for rule category precedence is
toolpath rules being of highest priority, followed by region rules,
then layer rules, then volume or global rules. Within each
category, user customizations are of higher priority than default
rules, other than safety or minimum functionality defaults.
[0164] FIG. 10C shows an alternative display approach to that of
FIG. 10A-10B. This display may be used in preparing a continuous
fiber reinforcement preform. The bottom portion of the display 1002
is similar to that of FIG. 10A, with the volume fill graph section
VFG-B display element as a topography representation of
approximately 150 layers, the same as or similar to the volume fill
graphs of FIGS. 10A-10B. As shown by the position of the thumb TH1,
the currently displayed layer is layer 38 within rule section RS9,
within which layers 4-44 and 107-147 include approximately 25%
fiber fill as shown by the volume fill graph section VFG4, VFG5. A
3D rendering of the accumulated layers of the part is shown instead
of a 2D layer plan view. Optionally, the 3D rendering is more
transparent with respect to fill material, walls; and comparatively
less transparent for fiber material; optionally with additional
luminance for highlighted sections of fiber material. As shown,
section RS9 is selected via pointer PO1, and a fiber highlight FHL
corresponding to the fiber tracks of rule section RS9 is arranged
and/or highlighted within the 3D rendering of the part.
[0165] Accordingly, a machine implemented method for displaying 3D
printable model shells on a display 1002 may include displaying a
multidimensional shell of a sliced model (such as the 2D additive
manufacturing layer representations of FIGS. 10A through 10C, or
the 3D rendered additive manufacturing model, mesh, or accumulation
of layers representation of FIG. 10C) on the display. An orthogonal
bar OB1.1, OB1.2 is displayed together with the displayed shell(s)
parallel to an edge of the display. A first proportional grouping
bar RS1-RS9 is displayed relative to a first range,
similarly/respectively RS1-RS9 of the orthogonal bar OB1.1, OB1.2,
the first proportional grouping bar RS1-RS9 representative of a
first toolpath rule (e.g., no fiber, concentric, isotropic) common
to a first range of shells at index positions within the range. A
movement of a pointer PO1 in a direction relative to the display
and/or an actuation of the pointer is detected (e.g., a mouse
click; a touchscreen tap; a button press associated with pointer).
In response to detecting the movement and/or the actuation of the
pointer PO1, one or both of the toolpath rule or the range is
changed. For example, in response, the printer or its slicer
processing may be configured to change the first toolpath rule
common to the first range of shells to a different, second toolpath
rule common to the first range of shells. In the alternative or in
addition, the printer or its slicer processing may be configured to
change the first range of shells to a different, second range of
shells having the first toolpath rule common thereto. Subsequently
or simultaneously, the printer or its slicer processing may be
configured to change the displayed multidimensional shell of the
sliced model so that the change of the toolpath rule and/or the
change of the range of shells is one of highlighted or
displayed.
[0166] Fiber reinforcement strategies, which may in some cases be
used in combination and which may have sub-strategies, include
Concentric Inward, Boustrophedon (ox rows, also known as raster, or
as isotropic, or quasi isotropic when the direction of rows is
rotated or alternated in adjacent layers), Concentric Outward, or
Sandwich Panel.
[0167] Concentric fill is performed within a layer by first
obtaining 80-105% (preferably 85-99%) fiber-width offsets from an
outer perimeter of a region of the layer. That is, the offsets form
concentric paths that are 80-105% (preferably 85-99%) of the
fiber-width as laid. One advantageous globally set region is the
non-wall region adjacent a shell or wall thickness region (e.g.,
1-3 bonded ranks thick). Fiber is deposited by controlling the
deposition head to stroke the center of the concentric fiber fill
offsets. When the offset has been looped, an S-shaped, L-shaped or
U-shaped crossover or bend lays fiber into the neighboring offset.
Concentric fill is suitable for bending and tension loads in
particular, and is efficient (fewer turns) as well as inherently
strong (no fiber separation permits more force to be transmitted
and distributed along the fiber length). As a global setting,
concentric fiber fill may be set to be adjacent a floor and or a
roof, and/or at a set number of layers from the top and/or bottom
of the part. In the alternative, spiral or concentric fill may have
no particular orientation, as its direction depends on the
perimeter of the part. Optionally, the concentric fill algorithm
may be used for other strategies (e.g., for surrounding holes or
hole splines for reinforcement). As noted, other settings can be
used in combination to, e.g., migrate the crossover or bend between
layers, locate crossovers in a particular place, or repeat or vary
concentric fill patterns.
[0168] Ox-row fill or Raster fill is performed in back and forth
rows. U.S. Pat. No. 6,934,600, herein incorporated by reference in
its entirety, discloses various implementations of raster fill for
nanotube impregnated three dimensional printing. Ox-row fill is
performed by specifying an orientation of rows (e.g., lengthwise,
widthwise, or at a specified angle) and a region. One advantageous
globally set region is again a non-wall region adjacent a shell or
wall thickness region. Parallel straight rows, offset by 80-105%
(preferably 85-99%) of the fiber width as laid, are calculated side
by side traversing the region. If a cutter is available
sufficiently close to the tip of the deposition head, the fibers
may be cut at each turn, alternating turns, every 3 turns,
according to a desired fiber length, and so on. However, a
boustrophedon path is optional. Boustrophedon paths can be
connected at end rows by 180 degree curved fiber paths of the same
diameter as the offset, and/or by folded paths of two right angles
(these may alternate). Fiber is again deposited by controlling the
deposition head to stroke the center of the concentric fiber fill
offsets. When the offset has been looped, an S-shaped crossover
lays fiber into the neighboring offset. As a global setting, ox-row
fiber fill may be set to be adjacent a floor and or a roof, and/or
at a set number of layers from the top and/or bottom of the part.
Ox-row fill may be set to substantially repeat a direction of fill
(for increased cumulative strength in that direction, or to provide
arbitrary or predetermined patterns of two, three, four or more
varying directions to increase multi-directional strength (e.g.,
90-90 would represent two adjacent 90 degree perpendicular layers;
60-60-60 three adjacent layers each rotated 60 degrees, 45-45-45-45
or 90-45-90-45 four layers following a repeating pattern of
reinforcing crisscrossing layers).
[0169] In this regard, successive layers of composite may, like
traditional lay-up, be laid down at 0.degree., 45.degree.,
90.degree., and other desired angles to provide part strength in
multiple directions and to increase the strength-to-weight ratio.
The controller 20 may be controlled to deposit the reinforcing
fibers with an axial alignment in one or more particular directions
and locations. The axial alignment of the reinforcing fibers may be
selected for one or more individual sections within a layer, and
may also be selected for individual layers. For example, as
depicted in FIGS. 11C and 12 a first layer 1200 may have a first
reinforcing fiber orientation and a second layer 1202 may have a
second reinforcing fiber orientation (as may further layers 1204 .
. . 1206). Additionally, a first section 1204 within the first
layer 1200, or any other desired layer, may have a fiber
orientation that is different than a second section 1206, or any
number of other sections, within the same layer.
[0170] Concentric fiber outward fill is distinct in from concentric
fill in that (i) the fiber loops are offset from an inner perimeter
formed by an envelope about features or parts to be spanned, rather
than outside in. Otherwise, the description with respect to
concentric fill applies as would be understood by one of ordinary
skill in the art. Fill is performed within a layer by first
determining an interior region to be surrounded, e.g., first
obtaining an envelope about two features to be circled. Offsets are
generated at 80-105% (preferably 85-99%) fiber-width from an outer
perimeter of the envelope. Fiber is deposited by controlling the
deposition head to stroke the center of the concentric fiber fill
offsets. Any S-shaped, L-shaped or U-shaped crossovers may be
concentrated on the lengthwise ends, i.e., the curves, of the
loops. Alternatively, as with concentric, a "spiral" offset of
linearly increasing offset distance may be used to avoid
crossovers, but a spiral offset typically does not fully wrap
features such as holes. Optionally, the envelope generation and
inner perimeter start may be used for other strategies.
Through-hole fill, as an example, may treat each hole as an
envelope, and extend the fill from top to bottom of the part,
lining a hole along greater than 80 percent of its top-to-bottom
length. As noted, other settings can be used in combination to,
e.g., migrate the crossover between layers, locate crossovers in a
particular place, or repeat or vary concentric fill patterns.
[0171] As an example, the embodiment of a part rendered and
processed include, but are not limited to, the operation of the
following rules:
[0172] (i) concentric fiber fill in the region R08 between the
outermost wall region R06 and the neighboring region R10;
[0173] (ii) pure polymer, fill material, or fiber triangular infill
in the region R10, which may be a remainder region (set after the
other regions are defined) extending between the limits of the
fiber fill region R08 and the negative contour W02, W04 outlining
wall regions R02, R04.
[0174] (iii) a sandwich panel, outer shell, inner shell,
outer/inner shell, or cellular rule as discussed below; and
[0175] (iv) a rule to outline or reinforce holes as discussed
below, among other rules.
[0176] In some embodiments, a core reinforced filament 1854 is used
to form a hole (or surround a protrusion, including a Z-axis
direction continuous fiber column orthogonal to, angled with
respect to, or curving through a layer) directly in a part, soluble
preform, or continuous fiber reinforcement preform, see FIGS. 11A
and 11B. More specifically, the core reinforced filament 1854 comes
up to the hole (or protrusion or continuous fiber column), runs
around it, then exits from the direction it came, though
embodiments in which the filament exits in another direction are
also contemplated. A benefit associated with this formation method
is that the hole is reinforced in the hoop direction by the core in
the core reinforced filament. As illustrated in FIG. 11A, the core
reinforced filament 1854 enters the circular pattern tangentially.
Entering tangentially is good for screws that will be torqued in.
In another version illustrated in FIG. 11B, the core reinforced
filament 1854 enter the circular pattern at the center of the
circle. Of course, it should be understood that other points of
entering the pattern are also possible. In one embodiment, the
entrance angle may be staggered in each successive layer. For
example, if there are two layers, the entering angle of the first
layer may be at 0 degrees while the entering angle for the second
layer may be at 180 degrees. This prevents the buildup of a seam in
the part. If there are 10 layers, the entering angle may be every
36 degrees (e.g., staggering the entering angle by 360 degrees/10
layers) or any other desired pattern or arrangement.
[0177] Still further alternative or additionally, with reference to
FIG. 15, the controller 20 of the printer 1000 may control the
actuators and heaters such that depositing the first consolidated
composite swath 2c and the second consolidated composite swath 2c
as a continuous composite swath 2c spanning (e.g., via inter-layer
continuous traverse SP30-A, SP30-B) two shells LA.sub.n, LA.sub.n+1
of an additive manufacturing process. That is, the fiber is not cut
but is continuous between two additive fill material layers. This
technique may be used in preparing a continuous fiber reinforcement
preform.
[0178] Still further alternative or additionally, the controller 20
of the printer 1000 may control the actuators and heaters such that
the first consolidated composite swath 2c is deposited in a first
reinforcement formation 99A-99Z that has a higher strength in
tension between a first negative contour (or hole H.sub.a) and a
second negative contour (or hole H.sub.b) than the second
reinforcement formation 99A-99Z.
[0179] The secondary print head 18 prints fill material or soluble
material to form walls, infill, protective coatings, and/or support
material on each layer, and as described herein, to smooth over
protrusions into neighboring layers, and/or to form a soluble
preform.
Consolidation, Compression and/or Flattening of Composite
Swaths
[0180] A preferred technique for depositing a core-reinforced
filament to become a fused composite swath includes compressing a
core reinforced filament exiting a conduit nozzle to form a
flattened shape (as discussed in the CFF patent applications).
[0181] The flattened shape is of variable height-to-width
proportion, e.g., in cross-section from 1:2 through about 1:12
proportion. Preferably, the height of a compressed composite swath
2c substantially corresponds to the fill material layer height in
the same layer LA.sub.1, so that neighboring composite swaths 2c in
the vertical direction can be tightly packed, yet be built up as
part of the same or adjacent layers as the surrounding,
complementary and/or interstitial fill material 18a.
[0182] Inter-layer interaction among composite swaths 2c and fill
material 18a may be more involved than interlayer interaction among
layers of fill material 18a. In most cases, an optional requirement
for adjacent layers of fill material 18a is that they are
satisfactorily fused in the vertical direction to avoid
delamination, and in many cases the fill material 18a is fused
(melted, or cured) under ambient or room pressure.
[0183] A core-reinforced multi-strand composite filament 2 may be
supplied, for example, as a circular to oval cross section, and/or
of approximately 1/3 mm in diameter and/or "13 thou" diameter.
[0184] As shown in Table 1 below, a circular cross-section filament
2 compressed during deposition becomes a progressively wider
composite swath 2c. The table uses an example dimensionless
diameter of 3 units for "round numbers".
[0185] As shown in the table, for any size of substantially
circular cross section core reinforced filament 2, flattening to
about 1/3 of its diameter becomes about 2.2-2.5 times as wide as
its original diameter, and if flattened to about 1/2 its diameter
becomes about 1.4-1.7 times its original diameter.
TABLE-US-00001 TABLE 1 Example Diameter (Circle): 3 units Rectangle
Compression H W 2/3 D height ~2 ~31/2 1/2 D height ~11/2 ~41/2 1/3
D height ~1 ~7 1/4 D height ~3/4 ~91/2
[0186] For example, to complement an additive manufacturing layer
height of 0.1 mm, a 1/3 mm diameter core reinforced filament 2 may
be flattened to a composite swath 2c of roughly rectangular shape
of proportion 1:6 through 1:12 (herein "highly compressed"), e.g.,
about 0.7-1.1 mm wide by about 0.07-0.12 mm high. One preferred
ratio is roughly 1:9. Even higher compression may be possible,
e.g., 1:12 to 1:20, but may demand significant system stiffness in
the printer 100.
[0187] In contrast, to complement an additive manufacturing layer
height of 0.2 mm, a 1/3 mm diameter core reinforced filament 2 may
be flattened to a composite swath 2c of roughly rectangular shape
of proportion 1:1.5 to 1:4 (herein "lightly compressed"), e.g.,
about a roughly rectangular shape of about 0.4-0.6 mm wide by about
0.2 mm high.
[0188] However, a fiber-embedded rectangular cross section of 1:1.5
to 1:3 is not as compressed or consolidated as one of 1:6 to 1.12
proportion, and in many cases, an relatively higher amount of
consolidation is preferable to reduce voids and improve mingling of
fibers in adjacent ranks 2c-2c or 2c-2d.
[0189] It should be noted that a supplied fiber reinforced filament
2 may have a constant cross-sectional area as supplied and as
deposited (unless coextruded or supplemented); while a supplied FFF
filament 18a has both a very different cross-sectional area as
supplied and as deposited (having a much larger diameter as
supplied), as well as variable cross-sectional area as deposited
(having a bead size depending on extrusion rate). Given that a
highly compressed composite swath is preferable to a lightly
compressed one, combining a larger FFF extrusion rate layer height
(e.g., 0.3 mm) with a highly compressed composite swath (e.g., 1:9
ratio) may be challenging. Accordingly, when a fill material height
is such that the amount of compression is unacceptably reduced,
more than one layer of fiber may be arranged per layer of fill
material (e.g., 2 or 3 1:9 sublayers of 0.1 mm composite swath 2c
per one respective 0.2 or 0.3 mm layer of fill material 18a). In
this case, most or all fill material 18a is deposited after the
composite swaths 2c; although in an alternative mode self-collision
detection may be used to avoid contacting the nozzles to the part
and the order of deposition thereby varied. In addition, in a
modification of this process, the fill material height and
compression amount may be selected to match stacks of 1:6-1:12
"highly compressed" composite swaths 2c (e.g., for a fiber of 1/3
mm diameter, the matching fill material 18a layer height capped at
approximately 0.24 mm, because the highest acceptable "highly
compressed" stack of two fibers is 1:6 ratio x 2, or 0.12
mm.times.2).
[0190] It should be noted that the cross-sectional representation
of reinforcing strands 4a within filament 2a and deposited swaths
2c are schematic only. In most cases, the reinforcing strands are
in the hundreds to thousands of parallel strands within the
filament 2a or swaths 2c.
Extrusion Toolpaths and/or Extrudates
[0191] In general, in the "FFF" or "FDM" extrusion method of
additive manufacturing, extrusion beads in adjacent layers
LA.sub.n, LA.sub.n+1 may be arranged to run either parallel or
transverse to one another, without crossing while within a layer. A
"retract" may be performed in the filament feed path to stop nozzle
flow and move from one isolated area to another to restart
extrusion, but the active printing beads tend to remain uncrossed.
This is reasonable, because continuing to extrude while crossing a
previously printed bead may cause extrudate to jet out horizontally
and unpredictably as the nozzle is partially blocked. Additionally,
any time spent extruding with a blocked nozzle reduces the amount
of active deposition of extrusion. Slicing software generally
avoids creating extrusion toolpaths which cross one another.
[0192] However, in the FFF printer discussed herein, extrusion
toolpaths may cross one another in the same manner as described
with respect to core reinforced fiber toolpaths, partially enabled
by a fast-response clutching in the filament supply for the
extrusion head 18, e.g., a low motor current or other slippable
drive. This is also the case when the fill material or fiber will
form part of a continuous fiber reinforcement preform. In such a
case, crossing extrusion toolpaths should cross at a high angle
(e.g., from 45-90 degrees) and/or limited to short periods of time
or narrow existing beads (e.g., for 1/10 to 1/100 of a second,
e.g., for a printing extrusion speed of 300 mm/s, crossing no more
than 1 mm of previously solidified extrudate, and preferably 1/4 to
1/2 mm of solidified extrudate). This is particularly advantageous
in the case of honeycomb fills of patterned lines (e.g., triangular
tessellation, e.g., of 60-60-60 degree crossing straight paths,
either with all paths intersecting (e.g., triangular honeycomb or
two paths intersecting with one path offset (e.g., Star of David
network or honeycomb).
[0193] Generally, even the fast-response buffered crossing of a
newly extruded bead or road of fill material 18a across a
previously printed extrusion bead or toolpath may not change the
layer height of the current layer LA.sub.n either on top of the
solidified bead crossed or in the currently deposited row, i.e.,
neat plastic does not generally vertically accumulate as beads are
crossed. Rather, fluidized fill material 18a tends to find a least
resistance direction to escape horizontally or downward when the
extrusion nozzle 18 is blocked by a previously deposited bead[0190]
As discussed herein, metal and ceramic matrices are also possible,
for example as a matrix with either the chopped fiber rods, short
fiber, long fiber, or continuous reinforcing fiber, in
approximately 0.1-25% (preferably approx. 5-15%) volume fraction of
carbon fiber strands, each fiber strand coated with a metal that
does not react with carbon at, e.g., sintering temperatures or
below (e.g., nickel, titanium boride). In the case of a 3D printing
deposition that is sintered while or after printing, the ceramic or
metal material of the matrix holds the fiber filler. Carbon fiber
is not the only reinforcing material, e.g., a chopped fiber rods,
short fiber, long fiber, or continuous reinforcing fiber having
approximately 2-10 times the elastic modulus of the metal or
ceramic matrix material is beneficial. In addition or as an
alternative to the chopped fiber rods, short fiber, long fiber, or
continuous reinforcing fiber, other reinforcing particles (e.g.,
particles, whiskers, nanostructures, spheres or irregular dispersed
material) of a material having approximately 2-10 times the elastic
modulus of the metal or ceramic matrix material may also be
beneficial.
[0194] A comparison of elastic modulus may be found in the
following table, of matrix vs. reinforcement:
TABLE-US-00002 Elastic Modulus Elastic Modulus Matrix (10.sup.9
N/m.sup.2, GPa) Fill/Fiber (10.sup.9 N/m.sup.2, GPa) Steel 180-200
Carbon Fiber 200-600 Aluminum 69 Graphite Fiber 200-600 Copper 117
Boron Nitride 100-400 Titanium 110 Boron Carbide 450 Alumina 215
Silicon Carbide 450 Cobalt 209 Alumina 215 Bronze 96-120 Diamond
1220 Tungsten Carbide 450-650 Graphene 1000 Carbon Nanotube
1000+
[0195] Some candidate matrix-filler combinations that may be
deposited by a 3D printer include cobalt or bronze matrix with
tungsten carbide coated graphite (carbon) fibers; aluminum matrix
with graphite (carbon) fibers; steel matrix with boron nitride
fibers; aluminum matrix with boron carbide fibers; aluminum matrix
with nickel coated carbon fibers; alumina matrix with carbon
fibers; titanium matrix with silicon carbide fibers; copper matrix
with aluminum oxide particles (and carbon fibers); copper-silver
alloy matrix with diamond particles. Those fibers that may be
printed via the techniques of the present application and the CFF
Patent Applications may also be embedded as continuous fibers.
Carbon forms for particles or fibers include carbon nanotubes,
carbon blacks, short/medium/long carbon fibers, graphite flakes,
platelets, graphene, carbon onions, astralenes, etc.
[0196] As discussed herein, the 3D printer may additively deposit
one or more of the continuous reinforcing fiber, soluble preform,
or non-soluble support preform in a reinforcement volume to form a
continuous fiber reinforcement preform. The soluble preform may be
dissolved before any overmolding. As an additively manufactured
body, the preform may be far more complex than simply a sheet,
panel, or curved panel, the preform may be a "complex solid", i.e.,
produced by combining and/or removing parts of three dimensional
shapes including at least some of cuboids, cylinders, prisms,
pyramids, spheres, and cones. The continuous fiber reinforcement
preform (optionally with a non-soluble support preform) may be
located within a mold of a molding apparatus, and the mold loaded
with molten molding material. The molding material is hardened to
overmold the continuous fiber reinforcement preform (optionally
with a non-soluble support preform), thereby forming a reinforced
molding surrounding an internal continuous fiber reinforcement
preform (optionally with a non-soluble support preform) with a
hardened molding material, wherein the reinforcement volume is
smaller than a volume of the entire reinforced molding. The
continuous fiber reinforcement volume may include a
continuous/random fiber reinforced composite filament including (a)
a plurality of axial fiber strands extending substantially
continuously within a matrix material of the fiber reinforced
composite filament (b) a multiplicity of chopped fiber, fiber rods,
short fiber, and/or particulates dispersed throughout the matrix
material. The non-soluble support preform may include the matrix
material and a multiplicity of chopped fiber, fiber rods, short
fiber, and/or particulates dispersed throughout the matrix
material. The matrix may be plastic, resin, or polymer (e.g., of
1-5 GPa elastic modulus), metal or ceramic.
[0197] The continuous fiber reinforcement volume may include the
continuous/random fiber reinforced composite filament and a matrix
that may be heated to a liquid state (e.g., a crystalline material
having a melting temperature, an amorphous material having a glass
transition temperature, or a semi-crystalline material having both)
within which the continuous/random fiber reinforced composite
filament is additively deposited, and the reinforcement volume is
less than 20 percent of the entire reinforced molding volume.
[0198] Alternatively, or in addition, the molding is performed at a
molding material pressure which removes air voids within the fiber
reinforcement matrix material. Further, the continuous fiber
reinforcement preform including the continuous/random fiber
reinforced composite filament may be bent or deformed from its
formation shape to a deformed shape within the mold. Further
optionally, two or more continuous fiber reinforcement preforms may
be bonded to one another before location within the mold.
[0199] In some embodiments, the mold is an injection mold, and pack
pressure of the injection molded material during molding
consolidates the fiber reinforcement preform into a final shape and
removes voids within the fiber reinforcement preform. If the mold
is an injection mold, and heat from injected molding material may
remelt a matrix material of the fiber reinforcement preform. In
some examples, the fiber deposition is an additively deposited
thermoplastic continuous fiber reinforced prepreg tape having a
width at least three times its height, which may also include the
multiplicity of chopped fiber, fiber rods, short fiber, and/or
particulates dispersed throughout the matrix material. Optionally,
vacuum may be applied during at least one of formation of the
continuous fiber reinforcement preform and the molding to remove
voids.
[0200] In one optional approach, a support material is formed in a
first shape as a support preform, and the continuous reinforcing
fiber is additively deposited in the reinforcement volume in a
second shape following a contour of the removable support preform
to form a continuous fiber reinforcement preform. Optionally, at
least one part of the support preform extends to be contiguous with
a surface of the reinforced molding. In another example, the
support preform is formed in a non-looped shape for permitting
additively depositing the continuous fiber reinforcement preform by
winding about the support preform. The support preform may itself
be injection molded, and may be injection molded as a honeycombed
structure, with a contiguous outer surface suitable as a winding
substrate. The support preform and continuous fiber reinforcement
preform may be formed in alternating successive additive and
injection molded stages. The support preform may be formed from an
additively deposited or injection molded matrix material, such as
plastic, resin, or polymer (e.g., of 1-5 GPa elastic modulus),
metal or ceramic, and including the multiplicity of chopped fiber,
fiber rods, short fiber, and/or particulates dispersed throughout
the matrix material.
[0201] Optionally, the support preform is formed in a substantially
rotationally symmetric shape or mandrel for permitting additively
depositing the continuous fiber reinforcement preform by winding
about the support preform. In one embodiment, the support preform
is relatively moved in at least one rotational degree of freedom
with respect to a deposition head that additively deposits the
continuous and/or continuous/random reinforcing fiber in the second
shape following the contour of the preform to form the continuous
fiber reinforcement preform.
[0202] A continuous fiber reinforcement preform may embed at least
one sandwich panel structure. The sandwich panel structure is
optionally a foldable structure, having a linear gap formed therein
opposite a fold line to form a hinge.
[0203] Further optionally, the support preform is formed including
a soluble material, and further comprising dissolving the preform.
The support preform may be dissolved before locating the continuous
reinforcement fiber preform (optionally including the
continuous/random reinforcement fiber material) within the mold,
and/or the support preform may be one of displaced, melted, or
dissolved by the mold loading. Alternatively, or in addition, the
support preform may be dissolved after the mold material is
hardened. The support preform may be dissolved at least in part
before location in the mold, and at least in part after the
reinforced molding is hardened. The support preform may be bent or
deformed from its formation shape to a deformed shape for
depositing the fiber reinforcement to form the continuous fiber
reinforcement preform. In one embodiment, a wide prepreg sheet is
arranged against the support preform before additively depositing
continuous fiber tape prepreg.
[0204] Optionally, the continuous reinforcement preform is located
in the reinforcement volume following a contour to form the
continuous fiber reinforcement preform as a first reinforced panel.
In this case, a further step or act may be locating a honeycombed
panel of molding material alongside the first reinforced panel,
wherein the molding material is hardened to overmold the
honeycombed panel against the first reinforced panel, thereby
forming a fiber reinforced molding including a molding material
honeycomb and a continuous fiber reinforcement. Optionally, a
second reinforced panel is additively continuous fiber deposited
upon the honeycombed panel. The second reinforced panel may be
formed having a joining surface mirroring a surface of the first
reinforced panel. A honeycomb structure may be formed as a support
preform upon which the second fiber reinforced preform is
deposited.
[0205] In each case, the molding material may be substantially
isotropic in tensile strength (e.g., a resin, metal, or ceramic,
including some reinforced with additives), and the continuous
reinforcing fiber as well as the continuous/random reinforcing
fiber are substantially anisotropic in tensile strength (e.g.,
carbon, glass, aramid, basalt, UHMWPE, or other continuous and/or
long fibers). According to one aspect of embodiments of the present
invention, a method for manufacturing a part may include supplying
a continuous/random fiber reinforced composite filament including a
matrix material, a plurality of axial fiber strands extending
substantially continuously within the matrix material, and a
multiplicity of fiber rods between 0.2-10 mm long dispersed
throughout the matrix material. The continuous/random fiber
reinforced composite filament is received in a cutter, and may be
cut there. The continuous/random fiber reinforced composite
filament is received in a nozzle. A dragging force is applied from
the part via the axial fiber strands but not via the dispersed
fiber rods. Pressure is applied with the nozzle to continuously
spread and fuse the continuous/random fiber reinforced composite
filament into the part, and also to continuously embed a proportion
of the short chopped fiber rods against previously deposited
portions of the part.
[0206] Alternatively, or in addition, the fiber rods at or near the
surface of a previously deposited layer of the part may be forced
to interact with one or more of a fill material, matrix material,
axial fiber strands or neighboring fiber rods. Optionally, the
continuous/random fiber reinforced composite filament is supplied
with fiber rods forming a 1-20% volume fraction of the
continuous/random fiber reinforced composite filament. The
continuous/random fiber reinforced composite filament may be
supplied with axial fiber strands of a different material from the
fiber rods, and/or with the axial fiber strands formed from glass
and the fiber rods formed from carbon. The continuous/random fiber
reinforced composite filament may supplied with the fiber rods
oriented in random directions, and/or with the fiber rods oriented
at least in part non-randomly. The continuous/random fiber
reinforced composite filament may be supplied with fiber rods
having an aspect ratio from 20:1-200:1, and/or with the fiber rods
including fiber chopped to 0.05-10 mm length (preferably 0.2 to 2
mm length to be managed in a slightly larger, e.g., 0.25 to 2.5 mm
diameter, nozzle without clogging).
[0207] Further optionally, the deposition head may be driven to
force the second proportion of the fiber rods to bridge successive
layers of continuous/random fiber reinforced composite
filament.
[0208] In a further aspect of embodiments of the present invention,
a continuous/random fiber reinforced composite filament may be
supplied similarly with a matrix material, a plurality of axial
fiber strands extending substantially continuously within the
matrix material, and a multiplicity of fiber rods between 0.2-10 mm
long dispersed throughout the matrix material, at least some of the
dispersed fiber rods being oriented transversely to the axial fiber
strands. A fill material may be supplied separately from the
continuous/random fiber reinforced composite filament, including
second dispersed fiber rods between 0.2-10 mm long. The
continuous/random fiber reinforced composite filament may be
deposited within a first region formed in an outward portion of a
part that is closer to an outer wall of the part than to a centroid
of the part, and the fill material may be deposited within a second
region formed in a portion of the part that is positioned inward
from the first region. Heated pressure may be applied to
continuously melt and spread the core reinforced filament, and/or
to continuously embed a proportion of the first dispersed fiber
rods against a previously deposited continuous/random fiber
reinforced composite filament, and/or to continuously embed a
proportion of the first dispersed fiber rods.
[0209] In a still further aspect of embodiments of the present
invention, a three dimensional printer for additive manufacturing
of a part may include a supply of a continuous/random fiber
reinforced composite filament including a matrix material, a
plurality of axial fiber strands extending substantially
continuously within the matrix material, and a multiplicity of
fiber rods between 0.2-10 mm long dispersed throughout the matrix
material. The printer may further include a deposition head
including a conduit transitioning to an ironing lip, a deposition
head drive driving the ironing lip, and a filament drive pushing an
upstream portion of the continuous/random fiber reinforced
composite filament to force an unattached terminal end of the
filament to exit the conduit at the ironing lip. A controller
operatively connected to the filament drive and the deposition head
drive may drive the deposition head to spread the continuous/random
fiber reinforced composite filament against previously deposited
portions of the part to (a) flow the matrix material and a first
proportion of the fiber rods interstitially among the axial fiber
strands, and/or (b) force a second proportion of the fiber rods
against previously deposited portions of the part.
[0210] In a still yet further aspect of embodiments of the present
invention, a method for manufacturing a part may include supplying
a continuous/random fiber reinforced composite filament including a
matrix material, a plurality of axial fiber strands extending
substantially continuously within the matrix material, and a
multiplicity of fiber rods between 0.2-10 mm long dispersed
throughout the matrix material. The continuous/random fiber
reinforced composite filament may be deposited in successive
layers. Pressure may be applied to continuously spread and fuse the
continuous/random fiber reinforced composite filament to previously
deposited layers and to continuously embed a proportion of the
short chopped fiber rods against previously deposited layers. A
fiber reinforced preform may be formed by the application of
pressure to successive layers of continuous/random fiber reinforced
composite filament, and may be inserted in a mold. The fiber
reinforced preform may be overmolded into a fiber reinforced
molding.
[0211] In an additional aspect of embodiments of the present
invention, a continuous fiber reinforced composite filament may be
supplied including a matrix material, with a plurality of axial
fiber strands extending substantially continuously within the
matrix material. The continuous fiber reinforced composite may be
received in a cutter, and cut there. The continuous fiber
reinforced composite may be received in a nozzle. Pressure may be
applied to continuously spread and fuse the continuous/random fiber
reinforced composite filament into the part. Negative contours may
be formed in successive layers of the part, and continuous
reinforcing columns bridging multiple successive layers of the part
inserted through the negative contours.
Wear Resistance
[0212] Thermoplastic composites can cause wear on any soft metal
(brass, aluminum, copper) and even on conventional or softer
steels. Glass fiber filler may have a Mohs hardness substantially
of 5 to 7, where carbon fiber may have a Mohs hardness
substantially of 2 or 3, and tool steels of approximately 4. Parts
that must resist the abrasive effect of carbon or glass fiber
filler may be made with resistant tool steel, such as A-2 or D-2
tool steel hardened to Rockwell C58-C60, or tool steels S-7 or
H-13. These materials may be further or alternatively hardened with
abrasion resistant electroless nickel plating, slow deposition
dense chrome, Nye-Carb (nickel silicon carbide) plating, chrome
plating, or physical vapor deposition plating (PVD). Hardening the
material, e.g., the A-2 or D-2 tool steel, to Rockwell C
.about.60+, may resist most wear.
[0213] Accordingly, in a three dimensional printer 1000 which
prints composite material, the non-matrix fiber (continuous or
chopped) or filler (e.g., also continuous or chopped or
particulate) may have an abrasive effect on the mechanical
components of the system, wearing down these components. As the
non-matrix filler or fiber 6a, 6b, 18b is harder, the abrasive
effect may be more significant. Additionally, higher speeds (e.g.,
in a nozzle throat vs. a nozzle body) and higher pressures (e.g.,
for compressed or consolidated continuous fiber) may also increase
the abrasive effect.
[0214] Some representative hardnesses for filler material and
nozzle and other part material are in the following Table.
Hardness Scales with Approximate Equivalency for the Present
Application.
TABLE-US-00003 Rockwell C Vickers Knoop Mohs Example(s) 1300+ 7.5+
Tungsten Carbide, other carbides and nitrides 66-68 ~900-1100 ~900
6.5 Some W tool steels, powder metallurgy tool steels 60 ~700 ~700
A-2, D-2 Tool Steel 50 ~500 ~500 5 H-13 as quenched, Harder
stainless steels 40 ~400 ~400 Beryllium 25 Copper 35 ~350 ~350 4.2
Some stainless steels 30 ~300 ~300 Softer stainless steels
[0215] In a system with one nozzle which prints a composite
material, the material supply path may include guide tubes or
Bowden subject to wear, one or more drive wheels subject to wear, a
nozzle throat subject to wear, all of these being worn by the
material itself 2 or 18a being transported through the system. In
addition, where a continuous fiber prepreg 2 or other material is
cut (e.g., continuous core material as described herein), the
cutter blade 8a may become worn. Further, as the nozzle tip 1803
moves back and forth upon previously printed lines, roads or swaths
2c, the tip 1803 may also wear. In a system with two or more
nozzles, one of which prints a composite material, even if one or
more of the nozzles prints non-abrasive material, the same effects
occur, except that the non-composite or non-abrasive nozzle may
become worn at the tip 1803 by rubbing against previously deposited
rows of the composite material. In a system with two or more
nozzles in which at least two print a composite material, each
non-composite and composite nozzle tip may be worn by at least two
types of previously deposited composite material.
[0216] With reference to FIGS. 1A-1F and 16-20, a three dimensional
printer 1000 may include a supply of material, the material
including a matrix material (e.g. a polymer, metal, or ceramic) and
a filler or fiber material, in which the filler or fiber material
has a Mohs hardness greater than 3, or a Knoop/Vickers hardness
greater than substantially 300 kg/mm.sup.2, or a Rockwell C
hardness greater than substantially C30 (e.g., continuous fiber 6a
and/or chopped fiber 6b or 18c, such as carbon or glass fiber, and
the like as described herein). A drive wheel 40, 42 or 1830 may for
advance the material 2, 2a, or 18a. Material may be deposited
through a heated conduit nozzle 708 or extrusion nozzle 1802
through which the material is dispensed. The heated nozzle may
include a nozzle body 1802a through which heat is applied to the
material, a nozzle throat such as the small channel at the end of
nozzle 1802 or 714, distal within the nozzle body 1802a, and a
nozzle tip such as 726 or the lower face 1803 of nozzle 1802 also
distal within the nozzle body.
[0217] The material passing through the nozzle throat is deposited
past the nozzle tip, and as shown in FIGS. 16-20, the nozzle tip
1803 may contact a top surface of previously deposited lines 18a or
2d of material (extruded or deposited continuous fiber swaths 2c,
2d) adjacent the currently deposited line of material. A nozzle
body 1802a including a material having a thermal conductivity of
substantially 35 w/M-K or higher (for example, steel, beryllium 25
copper, brass, tungsten carbide, or copper, or similarly heat
conductive materials) permits heat to be transferred to the melt
zone 1804 or nozzle tip 726 or 1803 sufficient to melt material,
while a nozzle throat (such as the fine channel at the very tip of
nozzle 1802) of a material having a Rockwell C hardness
substantially C50 or higher or Knoop/Vickers hardness substantially
500 or higher (for example hardened tool steel A-2, D-2, tungsten
carbide, or similarly hard materials) permits the nozzle throat to
resist abrasion and wear from the material passing through the
nozzle throat. In one configuration, for example in which a
non-abrasive or non-composite extrusion material and an abrasive
composite continuous fiber material are used in a system, a first
supply of a first material, the first material may be a composite
material including a matrix material and a filler or fiber material
(e.g., continuous fiber), in which the filler or fiber material has
a Mohs hardness greater than 1 (carbon fiber considered to be Mohs
2 or 3 for the purposes of the present disclosure), or a
Knoop/Vickers hardness greater than substantially 300 kg/mm.sup.2,
or a Rockwell C hardness greater than substantially C30. In this
case, the cutter 8a for the continuous fiber material 2 may be
arranged along a material supply path from the first supply of
first material. It should be noted that for the purposes of this
description and the claims, a chopped carbon filler is considered
to have a Mohs hardness of greater than 1, and in many cases
greater than 2 or 3.
[0218] In another configuration, for example in which a composite
filler extrusion material and an abrasive composite continuous
fiber material are used in a system together, the first supply of a
first material may include a matrix material and a filler or fiber
material, in which the filler or fiber material has a Mohs hardness
greater than substantially 1 (in some cases greater than 2 or 3),
or a Knoop/Vickers hardness greater than substantially 300
kg/mm.sup.2, or a Rockwell C hardness greater than substantially
C30. The second supply may also include abrasive material. In this
case, in order to responsively control temperature for printing the
composite extrusion material as well as from the continuous fiber
material, either or both nozzle bodies 1802 or 1802a may include a
material having a thermal conductivity of substantially 35 w/M-K or
higher (for example, steel, beryllium 25 copper, brass, tungsten
carbide, copper, or similarly heat conductive materials). In order
to resist abrasion from ongoing extrusion of material or rubbing
previously deposited material, the nozzle throat and nozzle tip
1803, particularly of an extrusion system, may each include a
material having a Rockwell C hardness substantially C40 or higher
or Knoop/Vickers hardness substantially 400 or higher (for example,
hardened beryllium 25 copper, hardened tool steel A-2, D-2,
tungsten carbide). The continuous fiber conduit nozzle 199 may
optionally similarly include a hardened material in order to resist
wear from rubbing.
[0219] In any of these configurations, for resisting wear from the
continuous fiber 6a within the matrix, the cutter 8a may include a
blade having a Rockwell C hardness substantially C60 or higher or
Knoop/Vickers hardness substantially 700 or higher (for example
hardened and/or coated tool steel A-2, D-2, or harder tool steels,
tungsten carbide, or similarly hard materials). At the same time,
the tip of the extrusion nozzle 1802 may be subject to wear from
previously deposited continuous fiber swaths or lines 2c, 2s. The
extrusion system may include a second supply of a second material
18a, and a heated nozzle 1802 through which the second material is
dispensed. The heated nozzle 1802 may include a nozzle body through
which heat is applied to the second material, a nozzle throat
distal within the nozzle body and a nozzle tip 1803 distal within
the nozzle (the end face of the extrusion nozzle 1802). The second
material passes through the nozzle throat at the tip of the
extrusion nozzle 1802 to be deposited past the nozzle tip, but the
nozzle tip of the extrusion nozzle 1802 may contact a top surface
of a previously deposited line of first material 2c, 2d adjacent a
currently deposited line of second material 18a.
[0220] Or, in the case where the material 18a is instead a
composite material with abrasive filler 18b, it may also contact a
top surface of previously deposited extrusion material 18a. In this
case, for a well-controlled extrusion system, the nozzle body 1802,
1802a may include a material having a thermal conductivity of
substantially 35 w/M-K or higher (for example, steel, beryllium 25
copper, brass, tungsten carbide, copper, or similarly heat
conductive materials), and in order to resist wear from the
neighboring system or itself, the nozzle tip 1802c may include a
material having a Rockwell C hardness substantially C40 or higher
or Knoop/Vickers hardness substantially 400 or higher (for example,
hardened beryllium 25 copper, hardened tool steel A-2, D-2,
tungsten carbide). One suitable construction for an extrusion
nozzle 1802 capable of resisting wear from its own composite
material and a neighboring composite deposition system includes a
nozzle throat and nozzle tip 1803 each include a material having a
Rockwell C hardness substantially C50 or higher or Knoop/Vickers
hardness substantially 500 or higher.
[0221] Optionally, for any of these configurations, the nozzle tip,
such as the distal end face 1803 of extrusion nozzle 1802 or nozzle
tip 726, includes a material having a Rockwell C hardness
substantially C40 or higher or Knoop/Vickers hardness substantially
400 or higher (for example, hardened beryllium 25 copper, hardened
tool steel A-2, D-2, tungsten carbide), which permits the nozzle
tip 1803 so hardened to resist abrasion by filler and/or fiber
within any material previously deposited 2d or 18a.
[0222] Further optionally, for any of these configurations, the
nozzle throat and tip 1802b, 1803 (or 726) may be made of a same or
similar material, integral or bonded. A nozzle throat/tip 1802b of
this type may resist abrasion both from material passing through
it, and material against which it rubs. For example, an extrusion
nozzle 1802 having a nozzle throat and nozzle tip 1802b, 1803 each
including a material having a Rockwell C hardness substantially C40
or higher or Knoop/Vickers hardness substantially 400 or higher
(for example, hardened beryllium 25 copper, hardened tool steel
A-2, D-2, tungsten carbide) may resist abrasion from chopped or
particulate filler 18b within the extrusion material 18a, but also
from previously deposited material--extruded 18a or deposited 2c,
2d.
[0223] For any of these configurations, extrusion nozzles 1802 may
often be made of higher thermal conductivity materials for faster
and more efficient control, and the system is superior if the
nozzle body 1802, 1802a includes a material having a thermal
conductivity of substantially 50 w/M-K or higher (for example,
brass, tungsten carbide, or copper, or similarly heat conductive
materials). Moreover, the system may resist harder particulate or
fiber content, or last longer, if it is harder, e.g., if the nozzle
throat includes a material having a Rockwell C hardness
substantially C60 or higher or Knoop/Vickers hardness substantially
700 or higher (for example hardened and/or coated tool steel A-2,
D-2, tungsten carbide, or similarly hard materials).
[0224] As noted, for any of these configurations, it is more
efficient and easier to manufacture systems in which at least the
nozzle throat and nozzle tip 1803 are integrated with one another.
One example of this would be if the nozzle throat and nozzle tip
1803 each include a material having a Rockwell C hardness
substantially C60 or higher or Knoop/Vickers hardness substantially
700 or higher (for example hardened and/or coated tool steel A-2,
D-2, or harder tool steels, tungsten carbide, or similarly hard
materials).
[0225] In one alternative, for any of these configurations, the
features of thermal conductivity and hardness are combined in one
material that both permits better control of applied heat and
resists wear. For example, a portion of the nozzle body 1802a (of
sufficient thermal mass to participate in heating the nozzle throat
and tip), the nozzle throat, and nozzle tip 1803 may be unitarily
formed including a material having a thermal conductivity of
substantially 60 w/M-K or higher as well as a Rockwell C hardness
substantially C60 or higher or Knoop/Vickers hardness substantially
700 or higher. Materials with high thermal conductivity and high
hardness are fewer than materials with only one attribute--in this
case, the nozzle body, sleeve, or tip may be formed from tungsten
carbide and other sintered carbines, qualifying nitrides having
suitable thermal conductivity and hardness, or similarly heat
conductive, hard materials.
[0226] One alternative, for any of these configurations, uses a
combination of very high thermal conductivity nozzle body 1802a and
high thermal conductivity, high hardness insert 1802b--for with a
majority of the thermal mass of the nozzle body 1802 including a
material having a thermal conductivity of substantially 200 w/M-K
or higher (e.g., some brasses, aluminum, copper), an insert 1802b
may be used. For the nozzle throat and nozzle tip 1803 may be
formed within a nozzle tip insert 1802b having a thermal
conductivity of substantially 100 w/M-K or higher as well as a
Rockwell C hardness substantially C60 or higher or Knoop/Vickers
hardness substantially 700 or higher (for example tungsten carbide
and other sintered carbines, qualifying nitrides, or similarly heat
conductive, hard materials).
[0227] As shown in FIGS. 16-20, for any of these configurations,
certain arrangements of insert may wear even more slowly. An
exemplary insert 1802c is a tapered insert having a nozzle tip of a
first diameter widening to a larger second diameter so that the
nozzle tip 1803 wears at a lower rate as material is worn away, and
optionally, includes a cavity behind the nozzle throat of larger
internal diameter than the nozzle throat diameter, and/or further
optionally including a chamfer leading from the larger cavity
diameter to the smaller nozzle throat diameter, and/or further
optionally is held within the nozzle body 1802a by one of a crimp
or a braze.
[0228] For any of these configurations, other arrangements may
similarly resist wear even more, or be particularly suited to
either an extrusion or a continuous fiber deposition path. For
example, a cutter 8A may be used with continuous fiber filament 2.
The cutter 8A may be arranged along a material supply path from the
supply of material to the nozzle tip 726, and in some embodiments
the cutter 8A positioned following the drive wheels 40, 42 for
advancing the continuous fiber reinforced material. The cutter 8A
may resist wear from an abrasive fiber material if it includes a
blade having a Rockwell C hardness substantially C60 or higher or
Knoop/Vickers hardness substantially 700 or higher (for example
hardened and/or coated tool steel A-2, D-2, or harder tool steels,
tungsten carbide, or similarly hard materials), especially in the
case where the cutter 8a may make a plurality of cuts per printed
layer.
[0229] In another example, for any of these configurations, guide
tubes or Bowden tubes may guide composite extrusion filament 18a or
continuous fiber reinforced filament 2 to a print head. In this
case, tight curves (such as 5 inches radius or lower) may encounter
situations in which the filament may consistently rub against the
same portion of interior wall of the tube(s). In such a case, at
least one non-polymer curved guide tube (e.g., of a material having
Rockwell C hardness substantially C25 or higher or Knoop/Vickers
hardness substantially 250 or higher) arranged along the material
supply path may resist wear of the guide tube system, the
non-polymer curved guide tube having at least one curved or
curvable section, which optionally may be formed in one or more
pieces from metal such as aluminum or steel (e.g., of a material
having Rockwell C hardness substantially C25 or higher or
Knoop/Vickers hardness substantially 250 or higher).
[0230] In another example, for any of these configurations, drive
wheels 40, 42 or 40a, 42a may also be constructed to resist wear.
In this case, at least one drive wheel 40, 40a, 42 or 42a for
advancing the continuous fiber reinforced filament material (or in
alternative cases, advancing the extrusion material) may be formed
from a material having a Rockwell C hardness substantially C25 or
higher or Knoop/Vickers hardness substantially 250 or higher (for
example some stainless steels). The rate of wear of a rotating
drive system may not be as high as the rate of wear for a sliding
contact part of the system, and so the material of the wheels need
not be as hard as that of a nozzle throat or tip or a cutter. In
this case, the driving capability/force may be improved if the
drive wheel for advancing the material is roughened, textured,
hobbed, or stepped, and the wear resistance of the driving system
may be improved if both of the two opposing wheels, 40, 42, one
drive and one idle, are of the hard, e.g., Rockwell C25 or higher,
material (e.g., including in the case when one opposing wheel is
roughened, textured, hobbed, or stepped and the other is
substantially smooth).
[0231] As described herein, various hardness scales are used,
substantially with reference to the below chart. The values in the
chart are approximate, for example at about +/-10% between Vickers
200-500. Where two or more hardness substantially scales are
indicated in the description or claims for a single component, the
limitation is a non-exclusive alternative (e.g., "Rockwell C60 or
Knoop/Vickers hardness substantially 700" means a "a hardness
substantially of 60 on the Rockwell C scale or a hardness
substantially of approximately 700 on the Knoop scale or a hardness
substantially of 700 on the Vickers scale). The use of Rockwell C
scale vs. Rockwell B or other scale does not indicate any
preference for metallurgical or other process, annealed or not
annealed, unless otherwise indicated, and any commercial, SAE,
ANSI, ISO, ASTM or other recognized conversion table or formula for
converting one hardness scale to another (among, but not limited
to, Rockwell, Knoop, Vickers, Mohs, etc.) may be used.
[0232] FIGS. 16-20 depict schematic representations of components
of the printer 1000 print head 1800, 199, etc. structures that may
be hardened in a composite printing system, including examples of
printing with polymer extrusion, composite extrusion with chopped
or other filler 18b, fiber deposition with continuous fiber 6a, and
fiber deposition with continuous fiber 6a where the matrix includes
chopped or other filler 6b. As may be seen in the chart above,
effectively resisting the hardest fillers such as glass fiber at
Mohs 5-7, exceeding the hardness of many tool steels, may benefit
from a high hardness material such as tungsten carbide (especially,
as noted herein, where the thermal conductivity of the material is
also very good).
[0233] As shown in FIGS. 16 (and 1B), a polymer filament guide tube
or Bowden tube BT-1 will tend to wear internally in the filament
extrusion system because an abrasive filament will continually rub
against the guiding inner surfaces. For tubes BT-1 that are used to
connect a filament supply with a print head moving in 3 or more
degrees of freedom, the most wear will occur on those curves that
have more frequent contact in different positions of the print head
1800 and different bend shapes of the Bowden tube BT-1. The
material of the guide or Bowden tube BT-1 should or may have a
hardness defined relative to the filler of the abrasive filament.
Similarly a guide tube BT-2 for a continuous composite filament may
tend to wear when a matrix of the filament includes chopped and/or
abrasive filler 6b.
[0234] A filament drive wheel, cog, or hob 40, 42 or 40a, 42a will
tend to wear internally in the filament extrusion system (whether
"direct drive" with no Bowden tube, or where separated from the
print head by a Bowden tube BT-1) because a certain amount of slip
will occur between a round drive element 40, 42 or 40a, 42a and an
abrasive filament 18a. The surface of the drive wheel, cog, or hub
40, 42 or 40a, 42a should have a hardness defined relative to the
filler.
[0235] A melt chamber or 1804 heat break need not, in most cases,
have a high hardness relative to a filler of an abrasive
filament.
[0236] An extrusion nozzle 1802 will tend to wear internally to the
filament extrusion system in the nozzle throat because the linear
velocity of the abrasive extrudate 18a, including chopped or other
filler 18b, is high in the throat. The nozzle 1802 throat should be
made of a material having a hardness defined relative to that of
the filler, reinforcement, or fiber 18b of a composite extrudate.
An extrusion nozzle 1802 will tend to wear externally to the
filament extrusion system at the nozzle tip 1803 because the tip
1803 will be abraded by adjacent, previously deposited abrasive
filament in the same layer, during printing and during non-printing
traverses. Similarly, a conduit nozzle 708 may tend to wear
externally at the ironing lip or tip 726 as abraded by previous
abrasive depositions. A tip 1803 of an extrusion nozzle 1802 may
wear faster than a conduit nozzle 708 ironing lip 726 because of
lower cross sectional area in contact with the previous
deposition.
[0237] As shown in FIG. 17, in a system with two nozzles, in which
at least one nozzle 18, 10, 1802, or 708 applies an abrasive
material 18a including a filler 18b, but a remaining nozzle
deposits a material 18a without an abrasive filler, even the
non-abrasive nozzle 1802 tend to wear at the tip 1803, because the
tip 1803 will be abraded by adjacent previously deposited abrasive
material 18b (or 6a, or 6b) in the same layer, during printing and
during non-printing traverses. If the non-abrasive material 18b (or
6a, or 6b) may always be printed first within a layer, then the
non-abrasive nozzle 1802 may be lifted to avoid wear. However, if
the non-abrasive material 18b (or 6a, or 6b) is printed second
within a layer, both or all nozzles 18, 10, 1802, or 708 should or
may have a hardness defined relative to the filler of the abrasive
material 18b (or 6a, or 6b).
[0238] As shown in FIG. 18, even where the fill material 18a is not
abrasive, the tip 1803 or end face of the extrusion nozzle 1802 may
be worn by previously deposited continuous fiber 6a (and/or filler
6b). Drive wheels 40, 42 for advancing continuous fiber prepreg 2
may be hardened (e.g., steel) to resist wear from the continuous
fiber material 6a (and/or filler 6b). The cutter 8A for severing
continuous fiber reinforced material 2 may be hardened (e.g.
tungsten carbide). Previously deposited continuous fiber swaths 2c,
2d may be abrasive to both extrusion and conduit nozzle tips 1803,
726.
[0239] As shown in FIG. 19, previously deposited composite extruded
material 18a, 18b may be abrasive to both extrusion and conduit
nozzle tips 1803, 726, and the nozzle throat may be worn by the
filler material 18b. Drive wheels 40, 42 for advancing continuous
fiber prepreg 2, 2a may be hardened (e.g., steel) to resist wear
from the continuous fiber material 2, 2a. The cutter 8A for
severing continuous fiber reinforced material 2,2a may be hardened
(e.g. tungsten carbide). Previously deposited continuous fiber
swaths 2c, 2d may be abrasive to both extrusion and conduit nozzle
tips 1803, 726.
[0240] As shown in FIGS. 20A-20D, nozzles 1802 and nozzle tips 1803
may be hardened in the throat and/or tip a variety of ways. As
shown in FIG. 20A, the entire nozzle 1802 may be made of a hard or
hardened material that has sufficient conductivity, such as
beryllium copper alloy, or tungsten carbide. In this case, the
selection of materials is narrow because hardness and high thermal
conductivity are only sometimes found together in one material. In
addition, precision machining operations (such as thread cutting)
are difficult with very hard materials, especially for small parts.
As shown in FIG. 20B, the nozzle body 1802a of the nozzle may be
made of a high thermal conductivity, readily machined material, and
a throat insert 1802b of high hardness may be tightly or
interference fitted or bonded or otherwise integrated with the high
thermal conductivity body 1802a. In this case, the selection of
materials for the throat insert 1802b is wider than would be the
case for a unitary nozzle, because there is no need to cut threads
in the throat insert 1802b--it must be hard, but because of its low
thermal mass in comparison to the nozzle body 1802a, it may have a
lower thermal conductivity than the nozzle body 1802a.
[0241] As shown in FIG. 20C, the nozzle body 1802a may be made of a
high thermal conductivity, readily machined material, and a throat
and full tip insert 1802c of high hardness may be fitted, bonded,
crimped, or otherwise integrated with the high thermal conductivity
body 1802a. Similar to the throat insert 1802b, the selection of
materials is wider because of the low thermal mass of the insert
1802c in comparison to the nozzle body 1802a. In addition, the
throat with full tip insert 1802c resists both internal and
external wear. The nozzle throat/tip insert 1802c may be
constructed with two internal diameters, large then small, so that
back pressure to push plastic through nozzle throat is reduced. The
larger internal diameter and length permits a larger holding
surface for machining and retaining. A ring shape may be preferably
only so tall as the throat length. In addition, or in the
alternative, the outer external rim or outer edge may be made with
a small radius outer edge (not sharp; e.g., larger than 0.01 mm
radius), which avoids damaging previously printed materials,
especially continuous fiber 6a. A tip insert 1802b, 1802c may seal
the insert vs. back pressure using a crimp or braze forcing the top
of the insert 1802b, 1802c against the nozzle body 1802a.
[0242] In contrast, as shown in FIG. 20D, in an alternative insert,
the majority of the thermal mass of the nozzle body 1802a is made
of a relatively high thermal conductivity material (e.g., brass,
copper) while the insert 1802c is a through sleeve of a material
hard both in the nozzle throat and tip. In this case, the seal
formed by the crimp does not retain the pressurized fill material,
but instead retains the insert so that upward force may be applied
by tightening the nozzle body, for example, sealing the upper part
of the nozzle insert as a butt or other end joint, to a heat break
or other upstream channel member.
[0243] As shown in FIG. 20E, the entire nozzle 1802 may be
alternatively made of a surface hardenable material that has
sufficient thermal conductivity, and a hardening treatment or
coating 1802d applied to the nozzle tip 1803 and/or throat. In this
case, the selection of materials is narrow because coating and
hardening operations are difficult in very small sizes (e.g.,
nozzle throats may be 0.15-1.00, e.g., 0.25 mm in diameter). In
addition, few hardening or coating operations are capable of
reaching a hardness sufficient to resist very abrasive materials.
Possible operations include chrome plating, electroless-nickel
plating or low temperature physical vapor deposition (PVD).
[0244] Section headings used herein are dependent upon following
content which they describe, and can only broaden the content
described.
Terminology
[0245] A "composite swath" or "composite swath" may refer to a
deposited fiber-reinforced composite filament, having been
compressed, consolidated and widened by ironing during deposition.
Extending within the composite swath are a plurality of individual
fibers, from 50-5000, preferably 100-2000, within a matrix
material.
[0246] A "multi-swath track" may refer to a set of parallel swaths
that generally follow parallel paths, although individual swaths
may deviate to avoid obstacles or achieve reinforcement goals.
[0247] A "fold" may refer to a composite swath which folds, twists,
or bunches over itself along a curved segment of composite swath
(such as a corner). A "fold" is not limited to sheet-like or
tape-like folds, but includes path changes in which different
fibers within the composite swath may cleanly switch sides of a
swath, but may also cross, twist, or bunch along the curved or
angled segment (such as a corner).
[0248] A "continuous fiber column" generally means a continuous
fiber element (two, tape, prepreg, or strands) extending between
two or more 3d printed layers (orthogonal, at any angle,
transverse, or curved), with at least part of the continuous fiber
strands having a Z direction component bridging two or more
layers.
[0249] "Fill material" includes material that may be deposited in
substantially homogenous form as extrudate, fluid, or powder
material, and is solidified, e.g., by hardening, crystallizing,
transition to glass, or curing, as opposed to the core reinforced
filament discussed herein that is deposited as embedded and fused
composite swaths, which is deposited in a highly anisotropic,
continuous form. "Substantially homogenous" includes powders,
fluids, blends, dispersions, colloids, suspensions and mixtures, as
well as chopped fiber reinforced materials. In any case herein
where "fill material" may be replaced with some soluble material or
form a soluble preform, this disclosure so contemplates. In such a
case, as discussed herein, once the soluble material is removed, a
continuous fiber reinforcement preform remains formed from
continuous fiber deposition patterns. It should be noted that a
coating, wall, shell, roof, ceiling or other buffer of non-soluble
fill material may remain or be deposited even when the fill
material discussed is partially or largely substituted with soluble
material.
[0250] "Honeycomb" includes any regular or repeatable tessellation
for sparse fill of an area (and thereby of a volume as layers are
stacked), including three-sided, six-sided, four-sided,
complementary shape (e.g., hexagons combined with triangles)
interlocking shape, or cellular.
[0251] A "Negative contour" and "hole" are used herein
interchangeably. However, either word may also mean an embedded
contour (e.g., an embedded material or object) or a moldover
contour (e.g., a second object with surfaces intruding into the
layer).
[0252] "Outwardly spiraling" or "outwardly offsetting" meaning
includes that a progressive tracing, outlining, or encircling is
determined with reference to an innermost, generally negative or
reference contour, not necessarily that the composite swath mush
begin next to that contour and be built toward an outer perimeter.
Once the toolpath is determined, it may be laid in either
direction. Similarly, "inwardly spiraling" or "inwardly offsetting"
means that the progressive tracing is determined with reference to
an outer, generally positive contour.
[0253] "3D printer" meaning includes discrete printers and/or
toolhead accessories to manufacturing machinery which carry out an
additive manufacturing sub-process within a larger process. A 3D
printer is controlled by a motion controller 20 which interprets
dedicated G-code (toolpath instructions) and drives various
actuators of the 3D printer in accordance with the G-code.
[0254] "Extrusion" may mean a process in which a stock material is
pressed through a die to take on a specific shape of a lower
cross-sectional area than the stock material. Fused Filament
Fabrication ("FFF"), sometimes called Fused Deposition
Manufacturing ("FDM"), is an extrusion process. Similarly,
"extrusion nozzle" shall mean a device designed to control the
direction or characteristics of an extrusion fluid flow, especially
to increase velocity and/or restrict cross-sectional area, as the
fluid flow exits (or enters) an enclosed chamber.
[0255] A "conduit nozzle" may mean a terminal printing head, in
which unlike a FFF nozzle, there is no significant back pressure,
or additional velocity created in the printing material, and the
cross sectional area of the printing material, including the matrix
and the embedded fiber(s), remains substantially similar throughout
the process (even as deposited in bonded ranks to the part).
[0256] "Deposition head" may include extrusion nozzles, conduit
nozzles, and/or hybrid nozzles. "Solidifying head" may include the
same, as well as laser melting and solidifying, laser curing,
energy curing. A material need not be liquefied to be solidified,
it may be cured, sintered, or the like.
[0257] "Filament" generally may refer to the entire cross-sectional
area of an (e.g., spooled) build material, and "strand" shall mean
individual fibers that are, for example, embedded in a matrix,
together forming an entire composite "filament".
[0258] "Alternating", with respect to reinforcement regions,
generally means in any regular, random, or semi-random strategy,
unless the pattern is described, specified, or required by
circumstances, for distributing different formations within or
among layers. E.g., simple alternation (ABABAB), repeating
alternation (AABBAABB), pattern alternation (ABCD-ABCD), randomized
repeating groups (ABCD-CBDA-CDAB), true random selection
(ACBADBCABDCD), etc.
[0259] "Shell" and "layer" are used in many cases interchangeably,
a "layer" being one or both of a subset of a "shell" (e.g., a layer
is an 2.5D limited version of a shell, a lamina extending in any
direction in 3D space) or superset of a "shell" (e.g., a shell is a
layer wrapped around a 3D surface). Shells or layers may be nested
(within each other) and/or parallel (offset from one another) or
both. Shells or layers are deposited as 2.5D successive surfaces
with 3 degrees of freedom (which may be Cartesian, polar, or
expressed "delta"); and as 3D successive surfaces with 4-6 or more
degrees of freedom. Layer adjacency may be designated using
descriptive notations "LA.sub.1", "LA.sub.2" or LA.sub.n,
LA.sub.n+1", etc., without necessarily specifying unique or
non-unique layers. "LA.sub.1" may indicate the view shows a single
layer, "LA.sub.2" indicating a second layer, and "LA.sub.1,
LA.sub.2" indicating two layers superimposed or with contents of
each layer visible. For example, in a top down view, either of
"LA.sub.1, LA.sub.2, LA.sub.3" or "LA.sub.n, LA.sub.n+1,
LA.sub.n+2" may indicate that three layers or shells are shown
superimposed. "LA.sub.1,LA.sub.2 . . . LA.sub.m" may indicate an
arbitrary number of adjacent layers (e.g., m may be 2, 10, 100,
1000, or 10000 layers).
[0260] Some representative Ultimate/Tensile Strength and
Tensile/Young's Modulus values for reinforcing fibers, core
reinforced fiber matrix materials, fill materials, and comparative
materials are in the following Table.
TABLE-US-00004 Representative Ultimate/Tensile Strength and
Tensile/Young's Modulus values Ultimate Strength Young/Tensile
Modulus MATERIAL MPa GPa reinforcing strands - UHMWPE- Dyneema,
Spectra 2300-3500 0.7 reinforcing strands - Aramid or Aramid Fiber
- Kevlar, 2000-2500 70.5-112.4, 130-179 Nomex, Twaron reinforcing
strands - Carbon Fiber 4000-4500 300-400 reinforcing strands -
Glass Fiber (E, R, S) 3500-4800 70-90 reinforcing strands - Basalt
fiber 1300-1500 90-110 Carbon Fiber reinforced plastic (70/30
fiber/matrix, 1600 170-200 unidirectional, along grain)
Glass-reinforced plastic (70/30 by weight fiber/matrix, 900 40-50
unidirectional, along grain) Steel & alloys ASTM A36 350-450
200 Aluminum & alloys 250-500 65-80 matrix, fill material,
solidifiable material - Epoxy 12-30 3.5 matrix, fill material,
solidifiable material - Nylon 70-90 2-4
* * * * *