U.S. patent application number 17/135120 was filed with the patent office on 2021-04-22 for method for reducing layer shifting and smearing during 3d printing.
This patent application is currently assigned to Desktop Metal, Inc.. The applicant listed for this patent is Desktop Metal, Inc.. Invention is credited to George Hudelson, Alexander Nicholas LeGendre, Kelvin Wiebe.
Application Number | 20210114308 17/135120 |
Document ID | / |
Family ID | 1000005307529 |
Filed Date | 2021-04-22 |
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United States Patent
Application |
20210114308 |
Kind Code |
A1 |
Hudelson; George ; et
al. |
April 22, 2021 |
Method for Reducing Layer Shifting and Smearing During 3D
Printing
Abstract
An additive manufacturing system, and corresponding method,
prints a sacrificial component using a 3D printing system that
includes a spreading mechanism for spreading unbound powder to form
layers of a powder bed and a printing mechanism for jetting binder
fluid into the unbound powder to form the sacrificial component.
The system forms the sacrificial component with a feature that
provides a resistive force to a shear force imposed by the
spreading mechanism during the spreading. The system prints a part
with the 3D printing system in a coupled arrangement with the
sacrificial component. The coupled arrangement in combination with
the resistive force is sufficient to immobilize each printed layer
of the part to resist the shear force imposed by the spreading
mechanism during spreading of the unbound powder above each printed
layer of the part. After printing, and before or after
post-processing, the part and sacrificial component are
separated.
Inventors: |
Hudelson; George;
(Billerica, MA) ; LeGendre; Alexander Nicholas;
(Boston, MA) ; Wiebe; Kelvin; (Chelmsford,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Desktop Metal, Inc. |
Burtington |
MA |
US |
|
|
Assignee: |
Desktop Metal, Inc.
Burlington
MA
|
Family ID: |
1000005307529 |
Appl. No.: |
17/135120 |
Filed: |
December 28, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15971541 |
May 4, 2018 |
10906249 |
|
|
17135120 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B33Y 10/00 20141201;
B29C 64/40 20170801; B28B 1/001 20130101; B28B 11/243 20130101;
B29C 64/393 20170801; B28B 17/0081 20130101; B33Y 50/02 20141201;
B29C 64/165 20170801; B22F 10/00 20210101; B33Y 30/00 20141201 |
International
Class: |
B29C 64/40 20060101
B29C064/40; B22F 10/00 20060101 B22F010/00; B33Y 10/00 20060101
B33Y010/00; B33Y 30/00 20060101 B33Y030/00; B33Y 50/02 20060101
B33Y050/02; B29C 64/393 20060101 B29C064/393; B29C 64/165 20060101
B29C064/165; B28B 1/00 20060101 B28B001/00; B28B 11/24 20060101
B28B011/24; B28B 17/00 20060101 B28B017/00 |
Claims
1. A method of forming a part via additive manufacturing, the
method comprising: producing a model of a part, wherein a surface
of the model facing in a negative z-direction includes portions
that extend different amounts in the negative z-direction;
producing a model of a sacrificial component, wherein a surface of
the model facing in a positive z-direction has a complementary
shape to the surface of the model facing in the negative
z-direction, such that the surface of the model facing in the
positive z-direction includes portions that extend different
amounts in the positive z-direction; forming the sacrificial
component according to the model of the sacrificial component by
depositing one or more layers of a loose powder and depositing a
fluid onto at least a portion of each of the one or more layers of
the loose powder to bind the loose powder where the fluid is
deposited; forming the part according to the model of the part by
depositing a plurality of layers of the loose powder and depositing
the fluid onto at least a portion of each of the plurality of
layers of the loose powder; and forming a boundary of the loose
powder between the sacrificial component and the part onto which
the fluid is not deposited, wherein the boundary of the loose
powder separates the sacrificial component from the part.
2. The method of claim 1, wherein a surface of the sacrificial
component facing the part has a complementary shape of a surface of
the part facing the sacrificial component.
3. The method of claim 1, wherein at least a portion of the part is
formed after the sacrificial component is formed.
4. The method of claim 1, wherein the boundary of the loose powder
extends through more than one layer of the plurality of layers of
layers of the loose powder from which the part is formed.
5. The method of claim 1, wherein depositing the one or more layers
of the loose powder and depositing the plurality of layers of the
loose powder includes spreading the loose powder using a spreading
mechanism.
6. The method of claim 1, wherein the sacrificial component extends
laterally beyond the part.
7. The method of claim 1, wherein forming the sacrificial component
includes depositing a first amount of fluid at a first saturation
level, wherein forming the part includes depositing a second amount
of fluid at a second saturation level, and wherein the first
saturation level is lower than the second saturation level.
8. The method of claim 1, wherein forming the sacrificial component
includes forming a lattice structure.
9. The method of claim 1, wherein the boundary completely extends
from a first lateral edge of the part to a second lateral edge of
the part.
10. The method of claim 7, wherein the complementary shape of the
surface of the model facing in the positive z-direction enables the
boundary to couple the part to the sacrificial component via an
indirect mechanical coupling.
11. A method of forming a part via additive manufacturing, the
method comprising: producing a model of the part, wherein a surface
of the model facing in a negative z-direction includes portions
that extend different amounts in the negative z-direction;
producing a model of the sacrificial component, wherein a surface
of the model facing in a positive z-direction has a complementary
shape to the surface of the model facing in the negative
z-direction, such that the surface of the model facing in the
positive z-direction includes portions that extend different
amounts in the positive z-direction; forming the sacrificial
component according to the model of the sacrificial component by
depositing a first amount of fluid onto a first region of the
powder to bind the powder; and forming the part according to the
model of the part by depositing a second amount of fluid onto a
second region of the powder to bind the powder; wherein a surface
of the sacrificial component facing the part has a complementary
shape of a surface of the part facing the sacrificial component,
and wherein the powder that is disposed between the first region
and the second region, is free of any deposited fluid.
12. The method of claim 11, wherein at least a portion of the part
is formed after the sacrificial component.
13. The method of claim 11, wherein forming the sacrificial
component includes depositing a first one or more layers of the
powder.
14. The method of claim 13, wherein forming the part includes
depositing a second one or more layers of powder.
15. The method of claim 11, wherein the sacrificial component
extends laterally beyond the part.
16. The method of claim 11, wherein forming the sacrificial
component includes depositing the first amount of fluid at a first
saturation level, wherein forming the part includes depositing the
second amount of fluid at a second saturation level, and wherein
the first saturation level is lower than the second saturation
level.
17. The method of claim 11, wherein forming the sacrificial
component includes forming a lattice structure.
Description
RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/614,132, filed on Jan. 5, 2018. The entire
teachings of the above application are incorporated herein by
reference.
BACKGROUND
[0002] Binder jetting is an additive manufacturing technique based
on the use of a liquid binder to join particles of a powder
material, also referred to interchangeably herein as powder, to
form a three-dimensional (3D) object. In particular, a controlled
pattern of the liquid binder may be applied to successive layers of
the powder material in a powder bed such that the layers of the
powder material adhere to one another to form the 3D object.
Through subsequent processing, such as sintering, the 3D object may
be formed into a finished object that may be referred to as a
finished 3D part.
SUMMARY
[0003] According to an example embodiment, an additive
manufacturing method may comprise printing a sacrificial component
using a three-dimensional (3D) printing system. The 3D printing
system may include (i) a spreading mechanism for spreading unbound
powder to form layers of a powder bed and (ii) a printing mechanism
for jetting binder fluid into the unbound powder to form the
sacrificial component. The sacrificial component is formed with a
feature that provides a resistive force to a shear force imposed by
the spreading mechanism during the spreading. The method may
comprise printing a part with the 3D printing system in a coupled
arrangement with the sacrificial component. The coupled arrangement
in combination with the resistive force is sufficient to immobilize
each printed layer of the part in the powder bed to resist the
shear force imposed by the spreading mechanism during spreading of
the unbound powder above each printed layer of the part.
[0004] The feature of the sacrificial component may be a given
number of printed layers, an inverse geometric feature that
complements a geometric feature of the part, or a combination
thereof.
[0005] The part and the sacrificial component may be coupled in the
coupled arrangement via an indirect mechanical coupling formed of
unbound powder.
[0006] Printing the part may include printing at least a portion of
the part above the sacrificial component. The part and the
sacrificial component may be coupled in the coupled arrangement via
a direct mechanical coupling. The method may further comprise
forming the direct mechanical coupling by spreading one or more
layers of the unbound powder and jetting binder fluid into same in
a manner that creates a lattice connection between the at least a
portion of the part and the sacrificial component.
[0007] Printing the part may include printing at least a portion of
the part above the sacrificial component. The part and the
sacrificial component may be coupled in the coupled arrangement via
a direct mechanical coupling formed of an anti-sintering agent. The
method may further comprise applying the anti-sintering agent to a
surface of the sacrificial component to form a separation layer
between the at least a portion of the at least a portion of the
part and the sacrificial component and decoupling the sacrificial
component from the part via sintering of the coupled
arrangement.
[0008] Printing the part may include printing at least a portion of
the part above the sacrificial component and the at least a portion
of the part may be the entire part.
[0009] Printing the sacrificial component may include: printing the
sacrificial component with a component shape that extends laterally
beyond a part shape of the part; printing one or more layers of the
sacrificial component and the part to extend the sacrificial
component and the part vertically upward and alongside each other;
or a combination thereof.
[0010] Printing the sacrificial component may include creating the
sacrificial component with one or more gaps of unbound powder, the
one or more gaps facilitating decoupling of the sacrificial
component from the part.
[0011] Printing the sacrificial component may include jetting the
binder fluid into the unbound powder in a manner that prints the
sacrificial component as a lattice structure.
[0012] Printing the sacrificial component may include printing
multiple sacrificial components each having a direct or indirect
mechanical coupling with a respective sacrificial component-facing
surface of the part.
[0013] The part may have a part shape. Printing the sacrificial
component may include printing the sacrificial component with a
complementary shape relative to the part shape. The complementary
shape may conform to a topography of the part shape at least
sufficiently enough to provide for the coupled arrangement.
[0014] The method may further comprise creating a 3D computer-aided
design (CAD) model of the coupled arrangement by duplicating a part
3D CAD model for the part to produce a copy of the part 3D CAD
model; translating the copy in a translation direction to produce a
translated copy; performing a 3D Boolean subtraction to subtract
the part 3D CAD model from the translated copy to produce a
sacrificial component 3D CAD model for the sacrificial component;
and applying an offset between the part 3D CAD model and the
sacrificial component 3D CAD model, wherein the part and the
sacrificial component are printed according to the part 3D CAD
model and the sacrificial component 3D CAD model, respectively.
[0015] The method may further comprise creating a 3D CAD model of
the coupled arrangement by approximating surfaces of a part 3D CAD
model for the part to produce an approximated version, the
approximated version being offset from the part 3D CAD model in an
outward direction; translating the approximated version in a
translation direction to produce a translated approximated version;
performing a 3D Boolean subtraction to subtract the approximated
version from the translated approximated version to produce a
sacrificial component 3D CAD model for the sacrificial component;
and applying an offset between the part 3D CAD model and the
sacrificial component 3D CAD model, wherein the part and the
sacrificial component are printed according to the part 3D CAD
model and the sacrificial component 3D CAD model, respectively.
[0016] Printing the sacrificial component may include jetting
binder fluid at a first saturation level. Printing the part may
include jetting binder fluid at a second saturation level. The
first saturation level may be lower relative to the second
saturation level.
[0017] According to another example embodiment, an additive
manufacturing system may comprise a spreading mechanism, printing
mechanism, and controller. The controller may be configured to (i)
drive the spreading mechanism to spread unbound powder to form
layers of a powder bed and (ii) drive the printing mechanism to jet
binder fluid into the unbound powder to print a sacrificial
component and a part. The controller may be further configured to
drive the printing mechanism to form the sacrificial component with
a feature that provides a resistive force to a shear force imposed
by the spreading mechanism during the spreading and print the part
in a coupled arrangement with the sacrificial component. The
coupled arrangement in combination with the resistive force is
sufficient to immobilize each printed layer of the part in the
powder bed to resist the shear force imposed by the spreading
mechanism during spreading of the unbound powder above each printed
layer of the part.
[0018] The feature of the sacrificial component may be a given
number of printed layers, an inverse geometric feature that
complements a geometric feature of the part, or a combination
thereof.
[0019] The part and the sacrificial component may be coupled in the
coupled arrangement via an indirect mechanical coupling formed of
unbound powder.
[0020] The controller may be further configured to drive the
printing mechanism to print at least a portion of the part above
the sacrificial component. The part and the sacrificial component
may be coupled in the coupled arrangement via a direct mechanical
coupling. The controller may be further configured to form the
direct mechanical coupling by driving the spreading mechanism to
spread one or more layers of the unbound powder and driving the
printing mechanism to jet binder fluid into same in a manner that
creates a lattice connection between the at least a portion of the
part and the sacrificial component.
[0021] The controller may be further configured to drive the
printing mechanism to print at least a portion of the part above
the sacrificial component. The part and the sacrificial component
may be coupled in the coupled arrangement via a direct mechanical
coupling formed of an anti-sintering agent. The system may further
comprise a sintering mechanism. The controller may be further
configured to drive the printing mechanism to apply the
anti-sintering agent to a surface of the sacrificial component to
form a separation layer between the at least a portion of the part
and the sacrificial component and drive the sintering mechanism to
sinter the coupled arrangement to decouple the at least a portion
of the part from the sacrificial component.
[0022] The controller may be further configured to drive the
printing mechanism to print at least a portion of the part above
the sacrificial component and the at least a portion of the part
may be the entire part.
[0023] The controller may be further configured to: drive the
printing mechanism to print the sacrificial component with a
component shape that extends laterally beyond a part shape of the
part; print one or more layers of the sacrificial component and the
part that extend the sacrificial component and the part vertically
upward and alongside each other; or a combination thereof.
[0024] The controller may be further configured to drive the
printing mechanism to create the sacrificial component with one or
more gaps of the unbound powder to facilitate decoupling of the
sacrificial component from the part.
[0025] The controller may be further configured to drive the
printing mechanism to jet the binder fluid into the unbound powder
in a manner that prints the sacrificial component as a lattice
structure.
[0026] The controller may be further configured to drive the
printing mechanism to print the sacrificial component as multiple
sacrificial components each having a direct or indirect mechanical
coupling with a respective sacrificial component-facing surface of
the part.
[0027] The part may have a part shape and the controller may be
further configured to drive the printing mechanism to print the
sacrificial component with a complementary shape relative to the
part shape. The complementary shape may conform to a topography of
the part shape at least sufficient enough to provide for the
coupled arrangement.
[0028] The controller may be further configured execute
instructions or interpret codes that were generated according to a
3D computer-aided design (CAD) model to drive the printing
mechanism to print the sacrificial component and the part in the
coupled arrangement.
[0029] The controller may be further configured to drive the
printing mechanism to: print the sacrificial component by jetting
binder fluid at a first saturation level; and print the part by
jetting binder fluid at a second saturation level, wherein the
first saturation level may be lower relative to the second
saturation level.
[0030] According to yet another example embodiment, a
non-transitory computer-readable medium may have encoded thereon a
sequence of instructions which, when loaded and executed by at
least one processor, causes a three-dimensional (3D) printing
system to drive a spreading mechanism of the 3D printing system to
spread unbound powder to form layers of a powder bed and drive a
printing mechanism of the 3D printing system to jet binder fluid
into the unbound powder to print a sacrificial component and a
part. The sequence of instructions may further cause the 3D
printing system to drive the printing mechanism to form the
sacrificial component with a feature that provides a resistive
force to a shear force imposed by the spreading mechanism during
the spreading and print the part in a coupled arrangement with the
sacrificial component. The coupled arrangement in combination with
the resistive force is sufficient to immobilize each printed layer
of the part in the powder bed to resist the shear force imposed by
the spreading mechanism during spreading of the unbound powder
above each printed layer of the part.
[0031] It should be understood that example embodiments disclosed
herein can be implemented in the form of a method, apparatus,
system, or computer readable medium with program codes embodied
thereon.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The patent or application file contains at least one drawing
executed in color. Copies of this patent or patent application
publication with color drawing(s) will be provided by the Office
upon request and payment of the necessary fee.
[0033] The foregoing will be apparent from the following more
particular description of example embodiments, as illustrated in
the accompanying drawings in which like reference characters refer
to the same parts throughout the different views. The drawings are
not necessarily to scale, emphasis instead being placed upon
illustrating embodiments.
[0034] FIG. 1A is a block diagram of an example embodiment of a
sacrificial component and a part within a powder bed.
[0035] FIG. 1B is a block diagram of another example embodiment of
a sacrificial component and a part within a powder bed.
[0036] FIG. 2A is a block diagram of an example embodiment of an
additive manufacturing system.
[0037] FIG. 2B is a block diagram of an example embodiment of
another additive manufacturing system.
[0038] FIG. 3 is a block diagram of an example embodiment of
printing stages for printing a sacrificial component and a
part.
[0039] FIG. 4 is a flow diagram of an example embodiment of an
additive manufacturing method.
[0040] FIG. 5A is a block diagram of an example embodiment of a
sacrificial component.
[0041] FIG. 5B is a block diagram of the sacrificial component of
FIG. 5A with a layer of unbound powder above the sacrificial
component.
[0042] FIG. 5C is a block diagram of the sacrificial component of
FIG. 5A with multiple layers of unbound powder located between the
sacrificial component and the part within a powder bed.
[0043] FIG. 6A is a block diagram of another example embodiment of
a sacrificial component.
[0044] FIG. 6B is a block diagram of the sacrificial component of
FIG. 6A with a thin lattice structure printed above the sacrificial
component.
[0045] FIG. 6C is a block diagram of a part printed in a coupled
arrangement with a sacrificial component.
[0046] FIG. 7A is a block diagram of an example embodiment of
another sacrificial component.
[0047] FIG. 7B is a block diagram of the sacrificial component of
FIG. 7A with an anti-sintering agent (ASA) applied to a top surface
of the sacrificial component.
[0048] FIG. 7C is a block diagram of another example embodiment of
a part printed in a coupled arrangement with a sacrificial
component.
[0049] FIGS. 8A-D disclose example embodiments of coupled
arrangements of parts and sacrificial components.
[0050] FIGS. 9A-D disclose example embodiments of various
geometries for the sacrificial component of the coupled
arrangements disclosed in FIGS. 8A-D.
[0051] FIG. 10A is a block diagram of an example embodiment of a
part and a sacrificial component printed as a lattice
structure.
[0052] FIG. 10B is a block diagram of another example embodiment of
a part and a sacrificial component printed as a lattice
structure.
[0053] FIG. 10C is a block diagram of yet another example
embodiment of a part and a sacrificial component printed as a
lattice structure.
[0054] FIG. 11A is a screen view of an example embodiment of a
lattice structure.
[0055] FIG. 11B is an oblique view of an example embodiment of a
part and a lattice structure.
[0056] FIG. 11C is a cross-sectional view of an example embodiment
of the part and lattice structure of FIG. 11B.
[0057] FIG. 11D is a cross-sectional view of another example
embodiment of the part and lattice structure of FIG. 11B.
[0058] FIG. 12 is a block diagram of an example embodiment of a
part and multiple sacrificial components.
[0059] FIG. 13A is a block diagram of an example embodiment of a
part with a part shape that includes multiple downward-facing
surfaces.
[0060] FIG. 13B is a block diagram of an example embodiment of a
part and a copy of the part.
[0061] FIG. 13C is a block diagram of an example embodiment of a
result from a 3D Boolean subtraction with an offset applied
thereto.
[0062] FIG. 14A is a block diagram of another example embodiment of
a part with a part shape that includes multiple downward-facing
surfaces.
[0063] FIG. 14B is a block diagram of an example embodiment of an
approximated version of the part of FIG. 14A.
[0064] FIG. 14C is a block diagram of an example embodiment of a
translated approximated version of the approximated version of FIG.
14B.
[0065] FIG. 14D is a block diagram of an example embodiment of
another result from a 3D Boolean subtraction with an offset applied
thereto.
[0066] FIG. 15A-D are block diagrams of example embodiments of
coupled arrangements of part and sacrificial components.
[0067] FIG. 16A is an image of an example embodiment of a portion
of a part 1610 with layer shifting.
[0068] FIG. 16B is an image of an example embodiment of the part
1610 of FIG. 16A without layer shifting and a sacrificial component
1624.
[0069] FIG. 16C is an image of the example embodiment of the part
1610 of FIG. 16B without layer shifting.
[0070] FIG. 17 is a block diagram of an example internal structure
of a computer optionally within an embodiment disclosed herein.
DETAILED DESCRIPTION
[0071] A description of example embodiments follows.
[0072] In a binder jetting process, a thin layer of powder (e.g.,
50 .mu.m) is spread onto a powder bed, followed by deposition of a
liquid binder in a two-dimensional (2D) pattern or image that
represents a single "slice" of a three-dimensional (3D) shape.
After deposition of the liquid binder, another layer of powder is
spread, and the process is repeated to form the 3D shape of bound
powder material inside the powder bed. Powder spreading may be
accomplished by means of a dispensing apparatus that deposits a
pile of powder onto the powder bed. The pile of powder may then be
spread, rolled, smoothed, or compacted by means of a spreading
mechanism, such as a counter-rotating roller, doctor blade, or
other means for spreading. After printing, the bound part is
removed from the excess unbound powder, and sintered at high
temperature to bind the particles together. Sintering may be
performed to densify the part to full density (i.e., removal of all
void space) or may be performed to bond the particles only lightly
without substantial removal of void space.
[0073] During the process of spreading a new layer of powder onto
the powder bed, the spreading mechanism can apply a shear force,
also referred to interchangeably herein as a shearing force, that
can cause defects in one or more previously printed layers. These
defects can include: "shifting" (i.e., translation of layers in the
powder bed); and "cracking" (i.e., breakup of the layers). Such
defects may be referred to collectively herein as "smearing,"
"shifting," or "cracking," but all generally refer to the "smeared"
or "shifted" layers of a printed part. An example embodiment
disclosed herein prevents such layer "shifting," "smearing," and
"cracking" of layers of printed parts by means of immobilizing the
layers during printing by printing a sacrificial component, also
referred to interchangeably herein as a "raft," under one or more
portions of the part being printed. As such, a method may reduce
layer shifting and smearing during 3D printing by means of
sacrificial printed raft(s).
[0074] FIG. 1A is a block diagram of an example embodiment of a
sacrificial component 24 and a part 10 within a powder bed 20. The
sacrificial component 24 is printed using a three-dimensional (3D)
printing system (not shown), such as the 3D printing system 250 of
FIG. 2A, disclosed further below, or any other suitable 3D printing
system that includes (i) a spreading mechanism 15 for spreading
unbound powder 4 to form layers of a powder bed 20, such as the
layer 35 of the powder bed 20, and (ii) a printing mechanism 19 for
jetting binder fluid 22 into the unbound powder 4 to form the
sacrificial component 24. Jetting the binder fluid 22 into the
unbound powder 4 produces the bound powder 33. Regions of the bound
powder 33 may be referred to as "printed" regions. The sacrificial
component 24 is formed with a feature (not shown) that provides a
resistive force (not shown) to a shear force 12 imposed by the
spreading mechanism 15 during the spreading. The resistive force
may be represented as one or more vector arrows (not shown) that
are equal and opposite to vector arrows of the shear force 12. The
part 10 is printed with the 3D printing system in a coupled
arrangement 26 with the sacrificial component 24. The coupled
arrangement 26 in combination with the resistive force is
sufficient to immobilize each printed layer of the part 10 in the
powder bed 20 to resist the shear force 12 imposed by the spreading
mechanism 15 during spreading of the unbound powder 4 above each
printed layer of the part 10.
[0075] According to an example embodiment, at least a portion of
the unbound powder 4 provides the resistive force. The part 10 and
the sacrificial component 24 may be coupled in the coupled
arrangement 26 via a mechanical coupling 5. The mechanical coupling
5 may be a direct or indirect mechanical coupling. For example, the
mechanical coupling 5 may be a direct mechanical coupling formed by
at least a portion of the part 10 being bound directly to the
sacrificial component 24 or by at least of portion of the part 10
and the sacrificial component 24 each being bound to a printed
structure interposed therebetween, such as the lattice structure
1121 of FIG. 11A, disclosed below, or any other suitable printed
structure. The part 10 and the sacrificial component may be printed
as a single printed part in the coupled arrangement 26. According
to an example embodiment, the part 10 and the sacrificial component
24 may be printed in a coupled arrangement 26 with a mechanical
coupling 5 that is an indirect mechanical coupling, for example,
the indirect mechanical coupling may be formed of unbound powder
4.
[0076] The feature of the sacrificial component 24 may be a given
number of printed layers, an inverse geometric feature that
complements a geometric feature of the part, or a combination
thereof. Example embodiments of the feature are disclosed, further
below.
[0077] FIG. 1B is a block diagram of another example embodiment of
a sacrificial component 124 and a part 110 within a powder bed 120.
The sacrificial component 124 and the part 110 may be printed by a
3D printing system (not shown) in a coupled arrangement, as
disclosed above. In the example embodiment of FIG. 1B, at least a
portion of the part 110 is printed above the sacrificial component
124 and is coupled to the sacrificial component 124 via a direct
mechanical coupling 105 as the printed layer 108a of the part is
bound to at least a portion of the printed layer 102e of the
sacrificial component 124. In the example embodiment of FIG. 1B,
the sacrificial component 124 is formed with a feature that
provides a resistive force (not shown) to a shear force 112 imposed
by spreading of the unbound powder 104 by the spreading mechanism
115. In the example embodiment, the feature of the sacrificial
component 124 includes a given number of printed layers, that is,
five, in the example embodiment, namely, the printed layers 102a-e
that are located below the mechanical coupling 105.
[0078] The sacrificial component 124 and the part 110 reside within
a powder bed 120. Printing of the sacrificial component 124 and the
part 110 includes jetting binder fluid (not shown) into layers of
the unbound powder 104 of the powder bed 120 spread by the
spreading mechanism 115 on a layer-by-layer basis, such as
disclosed below with reference to FIG. 2A.
[0079] In the example embodiment of FIG. 1B, printing of the
sacrificial component 124 includes jetting binder fluid into the
powder layers 106b, 106c, 106d, 106e, and 106f, while printing of
the part 110 includes jetting binder fluid into the powder layers
106g, 106h, and 106i, of the plurality of powder layers 106a-j that
are spread by the spreading mechanism 115, yielding the printed
layers 102a-e of the sacrificial component and the printed layers
108a-c of the part 110.
[0080] According to the example embodiment, the coupled arrangement
of the part 110 and the sacrificial component 124 in combination
with the resistive force of the feature, that is, the given number
of layers of the sacrificial component 124, is sufficient to
immobilize each printed layer of the part 110, that is, the printed
layers 108a-c, to resist the shear force 112 imposed by the
spreading mechanism 115 during spreading of the unbound powder 104
at powder layers 106h, 106i, and 106j, each above a printed layer
of the part 110. It should be understood that the powder layers
106b-f include the printed layers 102a-e and that the printed
layers 102a-e reflect portions of their respective powder layers
106b-f that have binder fluid applied thereto. Further, the powder
layers 106g-i include the printed layers 108a-c and the printed
layers 108a-c reflect portions of their respective powder layers
106g-i that have binder fluid applied thereto. The shear force 112
is imposed by physical interaction of the spreading mechanism 115
with the powder layers 106b-j. After printing, and before or after
post-processing, the part 110 is separated from the sacrificial
component 124. Following decoupling from the part 110, the
sacrificial component 124 may be disposed of, having served to
ensure quality of the part 110 (e.g., preventing smearing of the
part 110) during the printing process.
[0081] As illustrated in FIG. 1B, the printed layers 102a-e of the
sacrificial component 124 experience shifting, relative to a
respective original printed location 107, due to the shear force
112. Because the sacrificial component 124 already absorbed effects
of the shear force 112 and because the part 110 is printed in a
coupled arrangement with the sacrificial component 124, the printed
layers 108a-c of the part 110 resist the shear force 112 and, thus,
do not experience shifting. In the example embodiment, the given
number of layers of the sacrificial component 124 is five; however,
the given number may be any suitable number that enables printed
layer(s) of the part 110 to resist the shear force 112 caused by
the spreading mechanism 115. Further, it should be understood that
the part 110 may have any suitable shape or number of printed
layers to form a target 3D part. In addition, while FIG. 1B
discloses spreading of the powder layer 106j, it should be
understood that such spreading is shown for illustrative purposes
to show the shear force 112 and that a powder layer may not be
spread over the part 110 following printing of the part 110.
[0082] FIG. 2A is a block diagram of an example embodiment of an
additive manufacturing system 250. The additive manufacturing
system 250 comprises a spreading mechanism 215, printing mechanism
219, and controller 230. The controller 230 is configured to (i)
drive the spreading mechanism 215 to spread unbound powder 204 to
form layers of a powder bed 220 and (ii) drive the printing
mechanism 219 to jet binder fluid 222 into the unbound powder 204
to print a sacrificial component 224 and a part 210. The controller
230 is further configured to drive the printing mechanism 219 to
form the sacrificial component 224 with a feature that provides a
resistive force to a shear force 212 imposed by the spreading
mechanism 215 during the spreading and print the part 210 in a
coupled arrangement 226 with the sacrificial component 224. The
coupled arrangement 226 in combination with the resistive force is
sufficient to immobilize each printed layer of the part 210 in the
powder bed 220 to resist the shear force 212 imposed by the
spreading mechanism 215 during spreading of the unbound powder 204
above each printed layer of the part 210.
[0083] The feature of the sacrificial component 224 may be a given
number of printed layers, an inverse geometric feature that
complements a geometric feature of the part 210, or a combination
thereof. It should be appreciated that any one or more methods
described with respect to the formation of a given layer of the
part 210 or sacrificial component 224 may be repeated as necessary
to form a respective plurality of layers making up the part 210 or
sacrificial component 224. The sacrificial component 224 and the
part 210 are three-dimensional (3D) objects. The unbound powder 204
may include, without limitation, metallic particles, ceramic
particles, polymeric particles, and combinations thereof. The
additive manufacturing system may further comprise a sintering
mechanism (not shown). The part 210, sacrificial component 224, or
a combination thereof, may be subsequently processed (e.g.,
sintered) by the sintering mechanism (not shown) to form a finished
part that is separate from the sacrificial component 224. In
addition to sintering, other processing of the part 210 may be
performed to form the finished part.
[0084] The additive manufacturing system 250 may further comprise a
powder supply 217, print box 214, and nozzle 218. The print box 214
includes a build platform 213, such as a piston, that is moveable
within the print box 214. The print box 214 may have any suitable
shape and includes walls which, in combination with a top surface
of the build platform 213, contains the powder bed 220 which is
formed by spreading layers of the unbound powder 204 above the
build platform 213. The powder supply 217 is a dispensing apparatus
that deposits a pile of the unbound powder 204 onto the powder bed
220. According to the example embodiment, the dispensing apparatus
is a hopper with an opening from which the unbound powder 204 flows
to deposit the pile of unbound powder 204. The pile of unbound
powder 204 may then be spread, rolled, smoothed, or compacted by
means of the spreading mechanism 215, such as a counter-rotating
roller, doctor blade, or other means for spreading.
[0085] The build platform 213 is configured to move downward within
the print box 214 following spreading of a layer of the unbound
powder 204 and, optionally, jetting the binder fluid 222 into same.
The spreading mechanism 215 is moveable along the print box 214 to
spread successive layers of the unbound powder 204 across the
powder bed 220. The powder bed 220 may have a maximum number of
layers defined by the print box 214.
[0086] The nozzle 218 and the printing mechanism 219 may be movable
(e.g., in coordination with one another and, optionally, in
coordination with movement of the spreading mechanism 215) across
the powder bed 220 to form a plurality of layers and, ultimately,
to form the sacrificial component 224 and the part 210. The
spreading mechanism 215, nozzle 218, and printing mechanism 219 may
be movable over the print box 214. It should be understood that any
manner and form of relative movement of components of the additive
manufacturing system 250 may be used to carry out any one or more
of the binder jetting processes described herein. Thus, for
example, the print box 214 may be, further or instead, movable with
respect to one or more of the spreading mechanism 215, nozzle 218,
and printing mechanism 219 to achieve relative movement of
components, as necessary to carry out any one or more of the binder
jetting processes described herein.
[0087] The spreading mechanism 215 may generally span at least one
dimension of the powder bed 220 such that the spreading mechanism
215 may distribute a layer of the unbound powder 204 on top of the
powder bed 220 in a single pass. As an example, the spreading
mechanism 215 may include a roller rotatable about an axis
perpendicular to an axis of movement of the spreading mechanism 215
across the print box 214.
[0088] The roller may be, for example, substantially cylindrical.
In use, rotation of the roller about the axis perpendicular to the
axis of movement of the spreading mechanism 215 may spread the
unbound powder 204 that flows from the powder supply 217 to the
print box 214 to form a layer of the unbound powder 204 of the
powder bed 220. It should be appreciated, therefore, that the
plurality of sequential layers of the unbound powder 204 of the
powder bed 220 may be formed through repeated movement of the
spreading mechanism 215 across the powder bed 220. The thickness of
each layer of the unbound powder 204 may be substantially uniform
and, in particular, may be about 50 microns. Other dimensions are
additionally or alternatively possible.
[0089] The printing mechanism 219 may direct binder fluid into the
powder bed 220 as the printing mechanism 219 moves across the
powder bed 220. While the printing mechanism 219 may be illustrated
as a single printhead, it should be appreciated that the printing
mechanism 219 may, additionally or alternatively, include a
plurality of printheads from which the binder fluid 222 may be
jetted into the powder bed 220. Further, it should be understood
that jetting of the binder fluid 222 into the unbound powder 204 of
the powder bed may be jetted from any direction.
[0090] The controller 230 may be in electrical communication with
the powder supply 217, build platform 213, print box 214, spreading
mechanism 215, printing mechanism 219, and nozzle 218 to drive
functionality of same. The controller 230 may include one or more
processors 231 operable to control the powder supply 217, build
platform 213, print box 214, spreading mechanism 215, printing
mechanism 219, and nozzle 218, and combinations thereof.
[0091] The one or more processors 231 of the controller 230 may
execute instructions to control movement of one or more of the
powder supply 217, build platform 213, print box 214, spreading
mechanism 215, printing mechanism 219, and nozzle 218 relative to
one another as the sacrificial component 224 and the part 210 are
being formed. For example, the one or more processors 231 of the
controller 230 may execute instructions to move the powder supply
217 to direct the unbound powder 204 toward powder bed 220, move
the spreading mechanism 215 to spread the unbound powder 204 across
the powder bed, move the printing mechanism 219 to jet binder fluid
into a layer of unbound powder of the powder bed, and to move the
build platform 213 in a z-axis direction away from the spreading
mechanism 215 to accept each new layer of the powder 204 along the
top of the powder bed 220 as the spreading mechanism 215 moves
across the powder bed 220. In general, the controlled movement of
the build platform 213 is based on a thickness of a corresponding
layer being formed in the powder bed 220.
[0092] Additionally, or alternatively, the one or more processors
231 of the controller 230 may execute instructions to control
movement of the spreading mechanism 215 to spread successive layers
of the unbound powder 204 across the powder bed 220. For example,
the one or more processors 231 of the controller 230 may control
speed of movement of the spreading mechanism 215 across the powder
bed 220. As a further or alternative example, the controller 230
may control one or more features of the spreading mechanism 215
useful for packing the top layer of the powder bed 220 as the
spreading mechanism 215 moves across the powder bed 220. Returning
to the specific example of the spreading mechanism 215 being
rotatable, the one or more processors 231 of the controller 230 may
control rotation (e.g., speed, direction, or both) of the spreading
mechanism 215.
[0093] The one or more processors 231 of the controller 230 may,
further or instead, control the printing mechanism 219. For
example, the one or more processors 231 of the controller 230 may
control movement (e.g., speed, direction, timing, and combinations
thereof) of the printing mechanism 219 across the powder bed 220 as
well as jetting of the binder fluid 222 from the printing mechanism
219 into unbound powder of the powder bed 220. The one or more
processors 231 may control the printing mechanism 219 to jet the
binder fluid 222 into unbound powder of the powder bed 220 along a
controlled two-dimensional pattern associated with a given layer.
The controlled two-dimensional pattern may vary from
layer-to-layer, as necessary, according to a component shape of
sacrificial component 224 and a part shape of the part 210 being
formed in the powder bed 220.
[0094] The additive manufacturing system 250 may further, or
instead, include a non-transitory, computer readable storage medium
232 in communication with the controller 230 and having stored
thereon a three-dimensional model(s) 234 and instructions for
causing the one or more processors 231 to carry out any one or more
of the methods described herein. In general, as a plurality of
sequential layers of the powder unbound powder 204 are introduced
to the powder bed 220, the sacrificial component 224 and the part
210 are formed according to the three-dimensional model(s) 234
stored in the non-transitory, computer readable storage medium 232.
In certain implementations, the controller 230 may retrieve the
three-dimensional model(s) 234 in response to user input, and
generate machine-ready instructions for execution by the additive
manufacturing system 250 to fabricate the sacrificial component 224
and the part 210.
[0095] In the example embodiment of FIG. 2A, at least a portion of
the part 210 is printed above the sacrificial component 224 and is
coupled to the sacrificial component 224 via a mechanical coupling
205 that may be an indirect or direct mechanical coupling, as
disclosed herein. The controller 230 may be further configured to
drive the printing mechanism 219 to print the at least a portion of
the part above the sacrificial component 224.
[0096] According to an embodiment, the part 210 and the sacrificial
component 224 may be coupled in the coupled arrangement 226 via an
indirect mechanical coupling formed of the unbound powder 204.
According to another embodiment, the part 210 and the sacrificial
component 224 may be coupled in the coupled arrangement 226 via a
direct mechanical coupling. For example, the controller 230 may be
further configured to form the direct mechanical coupling by
driving the spreading mechanism 215 to spread one or more layers of
the unbound powder 204 and driving the printing mechanism 219 to
jet the binder fluid 222 into same in a manner that creates a
lattice connection, such as the lattice structure 1121 of FIG. 11A,
disclosed further below, that may be created between the at least a
portion of the part and the sacrificial component.
[0097] The controller 230 may be further configured to drive the
printing mechanism 219 to print at least a portion of the part 210
above the sacrificial component. The part 210 and the sacrificial
component 224 may be coupled in the coupled arrangement via a
direct mechanical coupling formed of an anti-sintering agent (ASA),
as disclosed further below with reference to FIG. 7B. The
controller 230 may be further configured to drive the printing
mechanism 219 to apply the ASA to a surface of the sacrificial
component 224 to form a separation layer between the at least a
portion of the part 210 and the sacrificial component 224 and drive
the sintering mechanism (not shown) to sinter the coupled
arrangement 226 to decouple the at least a portion of the part 210
from the sacrificial component 224.
[0098] According to an example embodiment, the controller 230 may
be further configured to drive the printing mechanism 219 to print
at least a portion of the part 210 above the sacrificial component
224 and the at least a portion of the part 210 may be the entire
part.
[0099] According to an example embodiment, the controller 230 may
be further configured to: drive the printing mechanism 219 to print
the sacrificial component 224 with a component shape that extends
laterally beyond a part shape of the part 210; print one or more
layers of the sacrificial component 224 and the part 210 that
extend the sacrificial component 224 and the part 210 vertically
upward and alongside each other; or a combination thereof, such as
disclosed below with reference to FIG. 8B and FIG. 8C.
[0100] According to an example embodiment, the controller 230 may
be further configured to drive the printing mechanism 219 to create
the sacrificial component 224 with one or more gaps of the unbound
powder 204 to facilitate decoupling of the sacrificial component
224 from the part 210, such as disclosed further below with
reference to FIG. 8D.
[0101] According to an example embodiment, the controller 230 may
be further configured to drive the printing mechanism 219 to jet
the binder fluid 222 into the unbound powder 204 in a manner that
prints the sacrificial component 224 as a lattice structure, such
as the lattice structure 224, disclosed further below with
reference to FIG. 11A.
[0102] According to an example embodiment, the controller 230 may
be further configured to drive the printing mechanism 219 to print
the sacrificial component 224 as multiple sacrificial components
each having a direct or indirect mechanical coupling with a
respective sacrificial component-facing surface of the part, such
as disclosed below with reference to FIG. 12.
[0103] According to an example embodiment, the part 210 may have a
part shape and the controller 230 may be further configured to
drive the printing mechanism 219 to print the sacrificial component
224 with a complementary shape relative to the part shape. The
complementary shape may conform to a topography of the part shape
at least sufficient enough to provide for the coupled
arrangement.
[0104] According to an example embodiment, the controller 230 may
be further configured execute instructions or interpret codes that
were generated according to the 3D CAD model(s) 234 to drive the
printing mechanism 219 to print the sacrificial component 224 and
the part 210 in the coupled arrangement 226.
[0105] According to an example embodiment, the controller 230 may
be further configured to drive the printing mechanism 219 to: print
the sacrificial component 224 by jetting the binder fluid 222 at a
first saturation level; and print the part 210 by jetting the
binder fluid 222 at a second saturation level, wherein the first
saturation level may be lower relative to the second saturation
level, such as disclosed further below with reference to FIGS.
15A-D.
[0106] FIG. 2B is a block diagram of another example embodiment of
an additive manufacturing system 2250. The example embodiment of
the additive manufacturing system 2250 includes an alternative
embodiment of the powder supply 217 relative to the example
embodiment of the additive manufacturing system 250 of FIG. 2A,
disclosed above.
[0107] According to the example embodiment, the print box 214
includes the powder supply 217 for depositing the pile of unbound
powder 204. As in the example embodiment of FIG. 2A, disclosed
above, the pile of unbound powder 204 may then be spread, rolled,
smoothed, or compacted by means of the spreading mechanism 215,
such as a counter-rotating roller, doctor blade, or other means for
spreading.
[0108] According to the example embodiment of FIG. 2B, the
spreading mechanism 215 may be movable from the powder supply 217
to the powder bed 220 and along the powder bed 220 to spread
successive layers of the unbound powder 204 across the powder bed
220. As in the example embodiment of FIG. 2A, disclosed above, the
nozzle 218 and the printing mechanism 219 may be movable (e.g., in
coordination with one another and, optionally, in coordination with
movement of the spreading mechanism 215) across the powder bed 220
to form a plurality of layers and, ultimately, to form the
sacrificial component 224 and the part 210.
[0109] According to the example embodiment of FIG. 2B, the one or
more processors 231 of the controller 230 may execute instructions
to control z-axis movement of one or more of the powder supply 217
and the build platform 213 relative to one another as the
sacrificial component 224 and the part 210 are being formed. For
example, the one or more processors 231 of the controller 230 may
execute instructions to move the powder supply 217 in a z-axis
direction toward the spreading mechanism 215 to direct the unbound
powder 204 toward the spreading mechanism 215 as each layer is
formed and to move the build platform 213 in a z-axis direction
away from the spreading mechanism 215 to accept each new layer of
the unbound powder 204 along the top of the powder bed 220 as the
spreading mechanism 215 moves across the powder bed 220. Movement
of the powder supply 217 may be performed by driving movement of a
powder supply platform 229. The powder supply platform may be any
suitable moveable platform, such as a piston.
[0110] In general, the controlled movement of the build platform
213 relative to the powder supply 217 is based on a thickness of a
corresponding layer being formed in the powder bed 220. Movement of
the powder supply 217 may be upward via a powder supply platform
Additionally, or alternatively, the one or more processors 231 of
the controller 230 may execute instructions to control movement of
the spreading mechanism 215 from the powder supply 217 to the
powder bed 220 to spread successive layers of the unbound powder
204 across the powder bed 220.
[0111] FIG. 3 is a block diagram of an example embodiment of
printing stages for printing a sacrificial component 324 and a part
310 in a coupled arrangement. In a first printing stage 321, a
first printed layer 302a of the sacrificial component 324 is
printed by jetting binder fluid into unbound powder of the powder
bed layer 306b spread on top of the unbound powder of the powder
bed layer 306a of a powder bed 320.
[0112] In a second printing stage 323, a next layer of unbound
powder is spread across a current top surface of the powder bed
320, where the current top surface in the second printing stage 323
is the powder bed layer 306b that includes the printed layer 302a
of the sacrificial component 324 and unbound powder. A spreading
mechanism 315, such as a roller or any other suitable spreading
mechanism, is used to spread the unbound powder of the powder bed
layer 306c across the current top surface of the powder bed 320 and
applies a shear force 312a during the spreading. In response to the
shear force 312a, the printed layer 302a shifts 303 relative to its
original printed location 307a. As such, the shear force 312a from
the spreading mechanism 315 causes the previously printed layer,
that is, the printed layer 302a of the sacrificial component 324,
to shift relative to its original printed location 307a.
[0113] In a third printing stage 325, binder fluid is jetted into
unbound powder of the powder bed layer 306c to form a next printed
layer of the sacrificial component 324, that is, the printed layer
302b. The powder bed layer 306c includes the printed layer 302b of
the sacrificial component 324 and unbound powder and becomes the
current top surface layer of the powder bed 320.
[0114] In a fourth printing stage 327, additional layers of the
sacrificial component 324 are printed, namely the printed layers
302c, 302d, and 302e, by spreading unbound powder to successively
form the powder bed layers 306d, 306e, and 306f and jetting binder
fluid into same. Following the printing of a given number of layers
of the sacrificial component 324, that is, five in the example
embodiment, a feature of the sacrificial component 324 is formed
that provides a resistive force to the shear force imposed by the
spreading mechanism 315 during spreading. Additional layers of
unbound powder are spread to form additional powder bed layers of
the powder bed 320, namely, the powder bed layers 306g, 306h, and
306i, and binder fluid is jetted into same to print the printed
layers 308a, 308b, and 308c of the part 310.
[0115] As disclosed in FIG. 3, there is no shifting of the printed
layers 308a, 308b, and 308c of the part 310, relative to an
original printed location 307b, due to the shear force 312b imposed
by the spreading mechanism 315 during spreading of unbound powder
above such layers. Shifting due to the shear force 312b is limited
to the five printed layers of the sacrificial component 324. The
five printed layers of the sacrificial component 324 serve as an
anchor for printed layers of the part 310 and form a feature of the
sacrificial component 324 that provides a resistive force to the
shear force imposed by the spreading mechanism during spreading of
unbound powder. As disclosed in the example embodiment of FIG. 3,
at least a portion of the part 310 is above the sacrificial
component 324 in the coupled arrangement. In the example
embodiment, the mechanical coupling 305 between the part 310 and
the sacrificial component 324 is a direct mechanical coupling.
[0116] The five printed layers 306b-f of the sacrificial component
324 are lower in the powder bed relative to the printed layers
308a-c. The coupled arrangement of the part 310 and the sacrificial
component 324 in combination with the resistive force provided by
at least the given number of layers, that is, the five printed
layers 306b-f of the sacrificial component 324, is sufficient to
immobilize each printed layer of the part 310 in the powder bed
320, that is, the printed layers 308a-c, to resist the shear force
312b imposed by the spreading mechanism 315 during spreading of
unbound powder above each printed layer of the part 310.
[0117] FIG. 4 is a flow diagram 401 of an example embodiment of an
additive manufacturing method. The method begins (402) and prints a
sacrificial component using a three-dimensional (3D) printing
system including (i) a spreading mechanism for spreading unbound
powder to form layers of a powder bed and (ii) a printing mechanism
for jetting binder fluid into the unbound powder to form the
sacrificial component with a feature that provides a resistive
force to a shear force imposed by the spreading mechanism during
the spreading (404). The method prints a part with the 3D printing
system in a coupled arrangement with the sacrificial component, the
coupled arrangement in combination with the resistive force being
sufficient to immobilize each printed layer of the part in the
powder bed to resist the shear force imposed by the spreading
mechanism during spreading of the unbound powder above each printed
layer of the part (406), and the method thereafter ends (408) in
the example embodiment.
[0118] FIG. 5A is a block diagram of an example embodiment of a
sacrificial component 524. In the example embodiment, shifting is
present in lower layers of the sacrificial component 524 referred
to interchangeably herein as a raft.
[0119] FIG. 5B is a block diagram of the sacrificial component 524
of FIG. 5A with a layer 505a of unbound powder spread above the
sacrificial component 524. The layer 505a of unbound powder may
serve as an indirect mechanical coupling between the sacrificial
component 524 and a printed layer of the part (not shown) that is
printed above the layer 505a of unbound powder.
[0120] FIG. 5C is a block diagram of the sacrificial component 524
of FIG. 5A with multiple layers of unbound powder 505b located
between the sacrificial component 524 and the part 510 within a
powder bed 520. The multiple layers of unbound powder 505b may
serve as an indirect mechanical coupling between the sacrificial
component 524 and the part 510. The part 510 is printed in a
coupled arrangement with the sacrificial component 524 and, in the
coupled arrangement, the sacrificial component 524 (i.e., "raft")
is printed underneath the part 510, and any smearing or layer
shifting occurs on the sacrificial component 524. After the raft is
at least some number of layers in thickness (at least one layer,
preferably at least 10 layers, most preferably at least 30 layers),
the raft has been formed with a feature that provides a resistive
force to a shear force imposed by a spreading mechanism (not shown)
during spreading. Subsequently, in the example embodiment, at least
one layer of powder, such as the layers 505a or 505b, may be spread
without binder (preferably between one layer and 20 layers, more
preferably between 2 and 10 layers, most preferably between 3-5
layers of powder), followed by printing of the part 510.
[0121] FIG. 6A is a block diagram of another example embodiment of
a sacrificial component 624. In the example embodiment, shifting is
present in lower layers of the sacrificial component referred to
interchangeably herein as a raft.
[0122] FIG. 6B is a block diagram of the sacrificial component 624
of FIG. 6A with a thin lattice structure 605 printed above the
sacrificial component 624. The lattice structure 605 may serve as a
direct mechanical coupling between the sacrificial component 624
and a printed layer of the part (not shown) that is printed above
the lattice structure 605.
[0123] FIG. 6C is a block diagram of a part 610 printed in a
coupled arrangement with a sacrificial component 624. The
sacrificial component 624 is formed with a feature that provides a
resistive force to a shear force imposed by a spreading mechanism
(not shown). After the raft is at least some number of layers in
thickness (at least one layer, preferably at least 10 layers, most
preferably at least 30 layers), the feature is formed, and a
tenuous connection, that is, the lattice structure 605, is printed
between the raft and the bottom of the part, in the example
embodiment. The printed part 610 is coupled to the sacrificial
component 624 by the thin lattice structure 605 that is printed
above the sacrificial component 624 in the coupled arrangement. The
coupled arrangement in combination with the resistive force, locks
the printed part 610 in place in the powder bed 620 and the part
610 is free from shifting and any smearing or layer shifting occurs
on the sacrificial component 624.
[0124] FIG. 7A is a block diagram of an example embodiment of
another sacrificial component 724. In the example embodiment,
shifting is present in lower layers of the sacrificial component
724 referred to interchangeably herein as a raft.
[0125] FIG. 7B is a block diagram of the sacrificial component 724
of FIG. 7A with an anti-sintering agent (ASA) applied to the top
surface 705 of the sacrificial component 724 to form a
sinter-resistant layer. The top surface 705 of the sacrificial
component 724 may serve as a direct mechanical coupling between the
sacrificial component 724 and a printed layer of the part (not
shown) that is printed above the top surface 705 having the ASA
applied. The ASA may include a material that is less sinterable
than at least a portion of the particles of the unbound powder with
binder fluid jetted into same. The ASA may be miscible with the
binder fluid and applied in combination with jetting of the binder
fluid to print the top surface 705. The ASA may be employed to
introduce an area of weakness that is useful for separating the
part (not shown) that is printed in the coupled arrangement with
the sacrificial component 724 after sintering.
[0126] Other suitable techniques for forming a sinter-resistant
layer on a sinterable three-dimensional object are described by way
of non-limiting examples, in Khoshnevis, et al, "Metallic part
fabrication using selective inhibition sintering (SIS)," Rapid
Prototyping Journal, Vol. 18:2, pp. 144-153 (2012) and U.S. Pat.
No. 7,291,242 to Khoshnevis, each of which is hereby incorporated
by reference in its entirety. By way of non-limiting example,
suitable techniques for inhibiting sintering on a surface of an
object include the use of a ceramic as a macroscopic mechanical
inhibitor, an application of lithium chlorate and aluminum sulfate
as microscopic mechanical inhibitors, and an application of
sulfuric acid and hydrogen peroxide as chemical inhibitors. More
generally, any technique for mechanically, chemically or otherwise
inhibiting sintering may be usefully employed to form the
sinter-resistant layer to facilitate post-sintering separation of
the part and the sacrificial component 724.
[0127] FIG. 7C is a block diagram of another example embodiment of
a part 710 printed in a coupled arrangement with a sacrificial
component 724. In the coupled arrangement of the example
embodiment, the sacrificial component 724 is printed underneath the
part 710. The sacrificial component 724 is formed with a feature
that provides a resistive force to a shear force imposed by a
spreading mechanism (not shown). After the sacrificial component
724 is at least some number of layers in thickness (at least one
layer, preferably at least 10 layers, most preferably at least 30
layers), the feature is formed, an ASA is applied to the top
surface 705 of the sacrificial component 724, and the part is
printed. The ASA forms a direct mechanical coupling between the
part 710 and the sacrificial component 724, in the example
embodiment. The coupled arrangement in combination with the
resistive force, locks the printed part 710 in place in the powder
bed 720 and the part 710 is free from shifting and any smearing or
layer shifting occurs on the sacrificial component 724.
[0128] FIGS. 8A-D, disclosed below, disclose example embodiments of
coupled arrangements of parts and sacrificial components.
[0129] FIG. 8A is a block diagram of an example embodiment of a
coupled arrangement of a part 810 and a sacrificial component 824.
In the example embodiment, the sacrificial component 824 (i.e.,
raft) is under the part 810 and separated from the part 810 by an
indirect mechanical coupling 805 formed of a layer of loose (i.e.,
unbound) powder 804. In the example embodiment, at least a portion
of the part 810 is printed above the sacrificial component 824 and
the at least a portion is the entire part 810. The sacrificial
component and the part 810 are printed parts, that is, formed of
bound powder 833.
[0130] FIG. 8B is a block diagram of an example embodiment of a
coupled arrangement of a part 810 and a sacrificial component 824.
In the example embodiment, the sacrificial component 824 (i.e.,
raft) is under the part 810 and separated from the part 810 by an
indirect mechanical coupling 805 formed of a layer of loose (i.e.,
unbound) powder 804. At least a portion of the part 810 is printed
above the sacrificial component 824 and the sacrificial component
824 is printed with a component shape that extends laterally beyond
a part shape of the part 810.
[0131] FIG. 8C is a block diagram of an example embodiment of a
coupled arrangement of a part 810 and a sacrificial component 824.
In the example embodiment, the sacrificial component 824 (i.e.,
raft) is under the part 810 and separated from the part 810 by an
indirect mechanical coupling 805 formed of a layer of loose (i.e.,
unbound) powder 804. At least a portion of the part 810 is printed
above the sacrificial component 824 and the sacrificial component
824 is printed with a component shape that extends laterally beyond
a part shape of the part 810. One or more layers of the sacrificial
component 824 and the part 810 extend vertically upward and
alongside each other.
[0132] FIG. 8D is a block diagram of an example embodiment of a
coupled arrangement of a part 810 and a sacrificial component 824.
In the example embodiment, a sacrificial component 824 (i.e., raft)
is under the part 810 and separated from the part 810 by an
indirect mechanical coupling 805 formed of a layer of loose (i.e.,
unbound) powder 804. The sacrificial component 824 is created with
a gap 837 of the unbound powder 804 to facilitate decoupling of the
sacrificial component 824 from the part 810. The gap 837 may be
referred to interchangeably herein as a "split." The sacrificial
component 824 and the part 810 are printed parts formed of the
bound powder 833.
[0133] FIGS. 9A-D disclose example embodiments of various
geometries for the sacrificial component of the coupled
arrangements disclosed above in FIGS. 8A-D. The example embodiment
of FIGS. 9A-D illustrate arbitrary shapes for the sacrificial
component (i.e., raft) 924 that follow a surface topology of the
part 910. The sacrificial component 924 and the part 910 are
printed parts formed of the bound powder 933. An indirect
mechanical coupling formed of the unbound powder 904 is created
between the sacrificial component 924 and the part 910. As in the
example embodiment of FIG. 8D, disclosed above, in the example
embodiment of FIG. 9D, there is a gap 937 in the sacrificial
component 924.
[0134] It should be understood that the example embodiments of
FIGS. 8A-9D may be combined with an ASA layer between the
sacrificial component and the part, such as disclosed with
reference to FIG. 7B and FIG. 7C, above.
[0135] FIG. 10A is a block diagram of an example embodiment of a
part 1010 and a sacrificial component 1024 printed as a lattice
structure. The part 1010 has multiple downward-facing surfaces
1011. In the example embodiment, the part 1010 and the sacrificial
component 1024 are printed in a coupled arrangement. The part 1010
and the sacrificial component 1024 are formed of bound powder 1033.
Printing of the sacrificial component 1024 included jetting the
binder fluid into the unbound powder 1004 in a manner that formed
the sacrificial component 1024 as the lattice structure. The part
1010 and the sacrificial component 1024, printed as the lattice
structure, are separated by an indirect mechanical coupling 1005
formed of a layer of loose (i.e., unbound) powder 1004. The lattice
structure may be separated from the part 1010 by one or more layers
of unbound powder (also referred to interchangeably herein as loose
powder), by a layer of ASA 1039 as disclosed in FIG. 10C, below, or
may be connected to the part via a direct mechanical coupling, as
disclosed in FIG. 10B.
[0136] FIG. 10B is a block diagram of another example embodiment of
a part 1010 and a sacrificial component 1024 printed as a lattice
structure. In the example embodiment, the lattice structure is
connected to the part 1010 via multiple direct connections that
form a direct mechanical coupling between the part 1010 and the
sacrificial component 1024.
[0137] FIG. 10C is a block diagram of another example embodiment of
a part 1010 and a sacrificial component 1024 printed as a lattice
structure. In the example embodiment, the lattice structure is
separated from the part 1010 by an ASA layer that is formed by the
ASA 1039 having been applied at multiple locations of the lattice
structure to form the mechanical coupling 1005 that is a direct
mechanical coupling between the part 1010 and the sacrificial
component 1024 in the example embodiment.
[0138] FIG. 11A is a screen view of an example embodiment of a
lattice structure 1121. As disclosed above, such a lattice
structure is not a contiguous body and may be employed as a
sacrificial component in a coupled arrangement with a part, such as
the sacrificial component 24 in the coupled arrangement 26 with the
part 10 of FIG. 1A, disclosed above. Alternatively, the lattice
structure 1121 may be employed as a mechanical coupling between the
part and the sacrificial component, such as the mechanical coupling
5 between the part 10 and the sacrificial component 24 of FIG. 1A,
disclosed above. For example, the lattice structure 1121 may be
printed to form a direct mechanical coupling between a sacrificial
component and part in a coupled arrangement, as disclosed above
with reference to FIG. 6C.
[0139] FIG. 11B is an oblique view of an example embodiment of a
part 1110 and a lattice structure 1121. The lattice structure 1121
may be employed as a sacrificial component in a coupled arrangement
with the part 1110 or as a mechanical coupling, or portion thereof,
that is formed between the part 1110 and the sacrificial component,
as disclosed above. The lattice structure 1121 may have a direct
mechanical coupling with the part 1110, such as shown in FIG. 11C,
disclosed below. Alternatively, the lattice structure 1121 may have
an indirect mechanical coupling with the part 1110, such as shown
in FIG. 11D, disclosed further below.
[0140] FIG. 11C is a cross-sectional view of an example embodiment
of the part 1110 and lattice structure 1121 of FIG. 11B, disclosed
above. In the example embodiment of FIG. 11C, the lattice structure
1121 has been printed such that it is mechanically coupled,
directly, to the part 1110.
[0141] FIG. 11D is a cross-sectional view of another example
embodiment of the part 1110 and lattice structure 1121 of FIG. 11B,
disclosed above. In the example embodiment of FIG. 11D, at least
one layer of unbound powder 1104 has been formed between the part
1110 and the lattice structure 1121. The part 1110 and the lattice
structure 1121 are indirectly coupled, mechanically, via the at
least one layer of unbound powder 1104.
[0142] FIG. 12 is a block diagram of an example embodiment of a
part 1210 and multiple sacrificial components 1224a and 1224b. As
disclosed in FIG. 12, creating a sacrificial component to prevent
smearing on downward-facing surfaces can be applied to any
downward-facing surfaces of the part 1210, not just the bottom of
the part 1210. Each of the multiple sacrificial components 1224a
and 1224b may have a direct or indirect mechanical coupling with a
respective sacrificial component-facing surface of the part 1210,
that is, the downward-facing surfaces 1211a and 1211b, in the
example embodiment. In the example embodiment, the downward-facing
surfaces 1211a and 1211b are indirectly coupled, mechanically, with
the sacrificial components 1224a and 1224b, respectively, via the
unbound powder 1204. The part 1210 and the sacrificial components
1224a and 1224b are formed of the bound powder 1233.
[0143] Turning back to FIG. 1A, the part 10 may have a part shape.
Printing the sacrificial component 24 may include printing the
sacrificial component 24 with a complementary shape relative to the
part shape. The complementary shape may conform to a topography of
the part shape at least sufficiently enough to provide for the
coupled arrangement.
[0144] FIG. 13A is a block diagram of an example embodiment of a
part 1310 with a part shape that includes multiple downward-facing
surfaces 1311. FIG. 13B and FIG. 13C, disclosed below, disclose
embodiments of a method for creating a 3D computer-aided design
(CAD) model of the coupled arrangement based on the part shape of
the part.
[0145] FIG. 13B is a block diagram of an example embodiment of the
part 1310 of FIG. 13A and a translated copy 1314 of the part 1310.
The method for creating a 3D computer-aided design (CAD) model of
the coupled arrangement may include duplicating a part 3D CAD model
for the part 1310 to produce a copy of the part 3D CAD model and
translating the copy in a translation direction to produce the
translated copy 1314. The method may further comprise performing a
3D Boolean subtraction to subtract the part 3D CAD model for the
part 1310 from the translated copy 1314 to produce a sacrificial
component 3D CAD model for the sacrificial component; and applying
an offset 1325 between the part 3D CAD model and the sacrificial
component 3D CAD model.
[0146] FIG. 13C is a block diagram of an example embodiment of a
result 1324 that results from performing the 3D Boolean subtraction
to subtract the part 3D CAD model for the part 1310 from the
translated copy 1314 to produce a sacrificial component 3D CAD
model for the sacrificial component; and applying an offset between
the part 3D CAD model and the sacrificial component 3D CAD model. A
coupled arrangement of the part and the sacrificial component may
be printed according to the part 3D CAD model and the sacrificial
component 3D CAD model.
[0147] FIG. 14A is a block diagram of another example embodiment of
a part 1410 with a part shape that includes multiple
downward-facing surfaces 1411. FIG. 14B-D, disclosed below,
disclose embodiments of another method for creating a 3D model of a
coupled arrangement based on the part shape of the part.
[0148] FIG. 14B is a block diagram of an example embodiment of an
approximated version 1416 of the part 1410 of FIG. 14A. The method
for creating the 3D model of the coupled arrangement based on the
part shape of the part 1410 may comprise approximating surfaces of
a part 3D CAD model for the part 1410 to produce and approximated
version 1416, the approximated version 1416 being offset from the
part 3D CAD model of the part 1410 in an outward direction via the
offset 1425.
[0149] FIG. 14C is a block diagram of an example embodiment of a
translated approximated version 1414 of the approximated version
1416 of FIG. 14B. The method for creating the 3D model of the
coupled arrangement may comprise translating the approximated
version 1416 in a translation direction to produce the translated
approximated version 1416. The method may further comprise
performing a 3D Boolean subtraction to subtract the approximated
version 1416 from the translated approximated version 1414.
[0150] FIG. 14D is a block diagram of an example embodiment of a
result 1424 from a 3D subtraction performed to subtract the
approximated version 1416 from the translated approximated version
1414 with an offset applied thereto. The result 1424 may be used as
a model for printing the sacrificial component. As such,
sacrificial components may be printed for parts with complex
features on the downward facing surfaces by printing the
sacrificial component with features that, while complementary, do
not interlock. Such interlocking features may be difficult to
de-powder.
[0151] FIG. 15A is a block diagram of another example embodiment of
a coupled arrangement of a part 1510 and a sacrificial component
1524. In the example embodiment, the sacrificial component 1524 is
printed at a lower binder saturation level than the part 1510. The
sacrificial component may be printed from powder material that is
bound only lightly. In the example embodiment, a separation layer
between the part 1510 and the "lightly bound" powder, that is, the
sacrificial component 1524, is loose (i.e., unbound) powder that
forms an indirect mechanical coupling between the part 1510 and the
sacrificial component 1524.
[0152] FIG. 15B is a block diagram of another example embodiment of
a coupled arrangement of a part 1510 and a sacrificial component
1524. In the example embodiment, the sacrificial component 1524 is
printed at a lower binder saturation level than the part 1510. The
sacrificial component may be printed from powder material that is
bound only lightly. In the example embodiment, a separation layer
between the part 1510 and the "lightly bound" powder, that is, the
sacrificial component 1524, is loose (i.e., unbound) powder and the
sacrificial component 1524 surrounds the part 1510 and forms an
indirect mechanical coupling between the part 1510 and the
sacrificial component 1524.
[0153] FIG. 15C is a block diagram of another example embodiment of
a coupled arrangement of part 1510 and a sacrificial component
1524. In the example embodiment, the sacrificial component 1524 is
printed at a lower binder saturation level than the part 1510. The
sacrificial component may be printed from powder material that is
bound only lightly. In the example embodiment, there is no
separation layer between the part 1510 and the "lightly bound"
powder, that is, the sacrificial component 1524. The part 1510 and
the sacrificial component 1524 have a direct mechanical coupling
formed between the bound powder of the part 1510 and the "lightly
bound" powder of the sacrificial component 1524.
[0154] FIG. 15D is a block diagram of another example embodiment of
a coupled arrangement of part 1510 and a sacrificial component
1524. In the example embodiment, the sacrificial component 1524 is
printed at a lower binder saturation level than the part 1510. The
sacrificial component may be printed from powder material that is
bound only lightly. In the example embodiment, there is no
separation layer between the part 1510 and the "lightly bound"
powder, that is, the sacrificial component 1524, and the
sacrificial component 1524 surrounds the part 1510. The part 1510
and the sacrificial component 1524 have a direct mechanical
coupling formed between the bound powder of the part 1510 and the
"lightly bound" powder of the sacrificial component 1524.
[0155] According to the example embodiments of FIGS. 15A-D,
disclosed above, binder may be printed (i.e., jetted) into the
powder bed beneath and/or surrounding the part, at a lower
concentration (saturation level) of binder than is required to
fully bind the powder together, effectively locking the powder in
place and preventing layer shifting. After drying/crosslinking, the
"lightly bound" powder would not be held together and, thus, could
be removed (i.e., de-coupled) from the printed part. Such a method
could be applied using a separation layer between the part and the
"lightly bound" powder, that is, the sacrificial component, or with
no separation therebetween.
[0156] FIG. 16A is an image of an example embodiment of a portion
of a part 1610 with layer shifting.
[0157] FIG. 16B is an image of an example embodiment of the part
1610 of FIG. 16A without layer shifting and a sacrificial component
1624.
[0158] FIG. 16C is an image of the example embodiment of the part
1610 of FIG. 16B without layer shifting.
[0159] FIG. 17 is a block diagram of an example of the internal
structure of a computer 1700 in which various embodiments of the
present disclosure may be implemented. The computer 1700 contains a
system bus 1702, where a bus is a set of hardware lines used for
data transfer among the components of a computer or processing
system. The system bus 1702 is essentially a shared conduit that
connects different elements of a computer system (e.g., processor,
disk storage, memory, input/output ports, network ports, etc.) that
enables the transfer of information between the elements. Coupled
to the system bus 1702 is an I/O device interface 1704 for
connecting various input and output devices (e.g., keyboard, mouse,
displays, printers, speakers, etc.) to the computer 1700. A network
interface 1706 allows the computer 1700 to connect to various other
devices attached to a network. Memory 1708 provides volatile or
non-volatile storage for computer software instructions 1710 and
data 1712 that may be used to implement embodiments of the present
disclosure, where the volatile and non-volatile memories are
examples of non-transitory media. Disk storage 1714 provides
non-volatile storage for computer software instructions 1710 and
data 1712 that may be used to implement embodiments of the present
disclosure. A central processor unit 1718 is also coupled to the
system bus 1702 and provides for the execution of computer
instructions.
[0160] Further example embodiments disclosed herein may be
configured using a computer program product; for example, controls
may be programmed in software for implementing example embodiments.
Further example embodiments may include a non-transitory
computer-readable medium containing instructions that may be
executed by a processor, and, when loaded and executed, cause the
processor to complete methods described herein. It should be
understood that elements of the block and flow diagrams may be
implemented in software or hardware, such as via one or more
arrangements of circuitry of FIG. 17, disclosed above, or
equivalents thereof, firmware, a combination thereof, or other
similar implementation determined in the future. In addition, the
elements of the block and flow diagrams described herein may be
combined or divided in any manner in software, hardware, or
firmware. If implemented in software, the software may be written
in any language that can support the example embodiments disclosed
herein. The software may be stored in any form of computer readable
medium, such as random access memory (RAM), read only memory (ROM),
compact disk read-only memory (CD-ROM), and so forth. In operation,
a general purpose or application-specific processor or processing
core loads and executes software in a manner well understood in the
art. It should be understood further that the block and flow
diagrams may include more or fewer elements, be arranged or
oriented differently, or be represented differently. It should be
understood that implementation may dictate the block, flow, and/or
network diagrams and the number of block and flow diagrams
illustrating the execution of embodiments disclosed herein.
[0161] The teachings of all patents, published applications and
references cited herein are incorporated by reference in their
entirety.
[0162] While example embodiments have been particularly shown and
described, it will be understood by those skilled in the art that
various changes in form and details may be made therein without
departing from the scope of the embodiments encompassed by the
appended claims.
* * * * *