U.S. patent application number 16/672025 was filed with the patent office on 2020-05-07 for methods, apparatuses and systems for additive manufacturing with preheat.
The applicant listed for this patent is Arevo, Inc.. Invention is credited to Armando ARMIJO, Riley REESE.
Application Number | 20200139694 16/672025 |
Document ID | / |
Family ID | 64014449 |
Filed Date | 2020-05-07 |
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United States Patent
Application |
20200139694 |
Kind Code |
A1 |
ARMIJO; Armando ; et
al. |
May 7, 2020 |
METHODS, APPARATUSES AND SYSTEMS FOR ADDITIVE MANUFACTURING WITH
PREHEAT
Abstract
The present disclosure provides methods for additive
manufacturing of a three-dimensional (3D) object, comprising
preheating a feed comprising a polymer material to a temperature in
excess of a glass transition temperature and below a melting point
of the polymer material. The preheating may occur at a first
location in an additive manufacturing apparatus. Next, the polymer
material may be melted at a second location that is spatially
distinct from the first location.
Inventors: |
ARMIJO; Armando; (Milpitas,
CA) ; REESE; Riley; (Milpitas, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Arevo, Inc. |
Milpitas |
CA |
US |
|
|
Family ID: |
64014449 |
Appl. No.: |
16/672025 |
Filed: |
November 1, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/US2018/030785 |
May 3, 2018 |
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16672025 |
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15587292 |
May 4, 2017 |
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PCT/US2018/030785 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 2035/0872 20130101;
B29C 35/0261 20130101; B29C 2035/0283 20130101; B29C 64/20
20170801; B29B 13/02 20130101; B29C 64/106 20170801; B29C 2035/0838
20130101; B29C 2035/0855 20130101; B33Y 10/00 20141201; B29C
2035/0822 20130101; B29C 2035/046 20130101; B29C 2035/0877
20130101; B29C 64/153 20170801; B33Y 30/00 20141201; B29B 13/08
20130101 |
International
Class: |
B33Y 30/00 20060101
B33Y030/00; B33Y 10/00 20060101 B33Y010/00; B29B 13/02 20060101
B29B013/02; B29C 64/153 20060101 B29C064/153; B29C 64/106 20060101
B29C064/106; B29C 64/20 20060101 B29C064/20; B29B 13/08 20060101
B29B013/08 |
Claims
1-26. (canceled)
27. A system for printing at least a portion of a three-dimensional
(3D) object, comprising: a source of at least one feedstock that is
configured to supply said at least one feedstock for printing said
at least said portion of said 3D object, which said at least one
feedstock comprises a polymer material; a substrate for supporting
said at least said portion of said 3D object during printing; a
printing unit that is configured to direct said at least one
feedstock from said source of said at least one feedstock towards
said substrate; at least one energy source configured to provide
energy; and a controller operatively coupled to said printing unit
and said at least one energy source, wherein said controller is
programmed to direct said at least one energy source to provide
said energy to: (i) preheat, at a first location in said printing
unit, said at least one feedstock to a preheat temperature in
excess of a glass transition temperature and below a melting
temperature of said polymer material, to thereby provide a
preheated feedstock, and (ii) melt, at a second location that is
spatially distinct from said first location, said preheated
feedstock to provide a melted feedstock.
28. The system of claim 27, wherein said at least one energy source
is selected from the group consisting of a direct contact heater, a
hot air blower, and a laser.
29. The system of claim 27, wherein said at least one energy source
is a laser configured to provide said energy comprising a first
light beam and a second light beam.
30. The system of claim 29, wherein said controller is further
programmed, in (i), to direct said at least one energy source to
provide said first light beam to preheat said at least one
feedstock.
31. The system of claim 29, wherein said controller is further
programmed, in (ii), to direct said at least one energy source to
provide said second light beam to melt said preheated
feedstock.
32. The system of claim 29, further comprising a beam splitter
configured to split a light beam from said at least one energy
source into said first light beam and said second light beam.
33. The system of claim 29, wherein said first light beam has a
different intensity than said second light beam.
34. The system of claim 27, wherein said controller is further
programmed, prior to (ii), to use said printing unit to direct said
preheated feedstock to said second location.
35. The system of claim 34, wherein said second location is
external to said printing unit.
36. The system of claim 27, wherein said preheat temperature is in
a range of about 0.7 to 0.95 times the melting temperature of said
polymer material.
37. The system of claim 27, wherein said preheat temperature is in
a range of about 0.8 to 0.9 times the melting temperature of said
polymer material.
38. The system of claim 27, wherein (i) occurs in a first period of
time and (ii) occurs in a second period of time, and wherein said
first period of time is longer than said second period of time.
39. The system of claim 27, wherein said at least one feedstock is
a continuous fiber composite.
40. The system of claim 27, wherein said polymer material comprises
a semi-crystalline polymer.
41. The system of claim 27, further comprising a compaction unit
configured to compact said at least one feedstock along said
substrate.
42. The system of claim 41, wherein said compaction unit comprises
a rigid body, one or more idler rollers, at least one freely
suspended roller, a coolant unit, or any combination thereof.
43. The system of claim 41, wherein said compaction unit is
configured to be positioned along only one side of said melted
feedstock.
44. The system of claim 41, wherein said controller is further
programmed to direct said compaction unit to compact said melted
feedstock.
45. The system of claim 41, wherein said controller is further
programmed to direct said compaction unit to cool said melted
feedstock.
46. The system of claim 27, further comprising one or more sensors
configured to measure one or more feedstock temperatures along said
at least one feedstock during printing.
Description
CROSS-REFERENCE
[0001] The present application is a continuation of International
Patent Application No. PCT/US18/30785, filed May 3, 2018, which
claims priority to U.S. patent application Ser. No. 15/587,292,
filed May 4, 2017, which is entirely incorporated herein by
reference.
BACKGROUND
[0002] Additive manufacturing is the term given to processes that
manufacture objects using sequential-layer material
addition/joining throughout a three-dimensional (3D) work envelope
under automated control. The International Organization for
Standardization/American Society for Testing and Materials 52900-15
(ISO/ASTM52900-15) defines seven categories of additive
manufacturing processes: binder jetting, directed energy
deposition, material extrusion, material jetting, powder bed
fusion, sheet lamination, and vat polymerization.
[0003] Extrusion-based 3D printing processes produce an object by
extruding small beads of material, such as thermoplastics, which
quickly harden to form a layer. Successive layers of material are
deposited to create the object. For material extrusion, two
important factors are control over the extruded filament and the
rate at which the material can be extruded. Regarding the latter
factor, guidelines may be presented in terms of a volume of
material that can be printed per second. Given a thickness for the
extrudate layer, the print speed may be dictated.
SUMMARY
[0004] In an aspect, the present disclosure provides a method for
additive manufacturing of a three-dimensional (3D) object, the
method comprising (a) preheating, at a first location in an
additive manufacturing apparatus, a feed comprising a polymer
material to a temperature in excess of a glass transition
temperature and below a melting point of the polymer material; and
(b) melting, at a second location that is spatially distinct from
the first location, the polymer material. In some embodiments, the
temperature is from about 0.7 to about 0.95 times the melting point
of the polymer material. In some embodiments, the temperature is
from about 0.8 to about 0.9 times the melting point of the polymer
material. In some embodiments, the second location is on a build
surface on which the 3D object is manufactured. In some
embodiments, preheating occurs in a first period of time and
melting occurs in a second period of time. In some embodiments, the
first period of time is longer than the second period of time. In
some embodiments, a rate at which the polymer material is melted is
greater than a rate at which the polymer material is preheated. In
some embodiments, the feed is in a form of a filament. In some
embodiments, the feed is in a form of a powder. In some
embodiments, the polymeric material comprises a semi-crystalline
polymer. In some embodiments, the polymeric material comprises an
amorphous polymer. In some embodiments, the preheating is performed
by a first heating device and melting is performed by a second
heating device. In some embodiments, the method for additive
manufacturing of a 3D object further comprises depositing a portion
of the feed comprising the polymer material melted in (b). In some
embodiments, the portion of the feed is deposited in accordance
with a computer model of the 3D object.
[0005] In some embodiments, the method for additive manufacturing
of a 3D object further comprises depositing a portion of the feed
preheated in (a) over a build surface, and melting the polymer
material in the portion of the feed deposited over the build
surface. In some embodiments, the method for additive manufacturing
of a 3D object further comprises using an energy source to melt the
polymer material. In some embodiments, the energy source is a
laser.
[0006] In another aspect, the present disclosure provides an
apparatus for additive manufacturing of a three-dimensional (3D)
object, comprising a preheater; and an energy source, wherein
energy from the energy source melts the polymer material at a
second location that is spatially distinct from the first location.
In some embodiments, the preheater heats a feed comprising a
polymer material to a temperature in excess of a glass transition
temperature and below a melting point of the polymer material. In
some embodiments, the polymer material is preheated at a first
location. In some embodiments, the apparatus for additive
manufacturing of the 3D object further comprises a feed subsystem.
The feed subsystem may deliver the feed to the first location. In
some embodiments, the second location is proximal to a build
surface. In some embodiments, the preheater is selected from the
group consisting of a direct contact heater, a hot air blower, and
a laser. In some embodiments, the energy source is a laser. In some
embodiments, the preheater heats the feed to the temperature from
about 0.7 to about 0.95 times the melting point of the polymer
material. In some embodiments, the preheater heats the polymer
material for a first period of time that is longer than a second
period of time in which the energy source melts the polymer
material. In some embodiments, the apparatus for additive
manufacturing of the 3D object further comprises a filament shaper,
wherein the filament shaper applies pressure to the feed as it is
melted proximal to the build surface. In some embodiments, the
apparatus for additive manufacturing of the 3D object further
comprises a temperature control system for controlling an amount of
heat supplied by the preheater. In some embodiments, the apparatus
for additive manufacturing of the 3D object further comprises a
controller operative coupled to the preheater and energy source,
wherein the controller comprises one or more computer processors
that are individually or collectively programmed to (i) direct the
preheater to heat the feed comprising the polymer material at the
first location, and (ii) direct the energy source to provide the
energy to melt the polymer material at the second location.
[0007] The polymeric material used for printing may be preheated
prior to being melted. This approach may be used with
three-dimensional (3D) printing methodologies. Examples of 3D
printing methodologies comprise extrusion, wire, granular,
laminated, light polymerization, VAT photopolymerization, material
jetting, binder jetting, sheet lamination, directed energy
deposition, or power bed and inkjet head 3D printing. Extrusion 3D
printing can comprise robo-casting, fused deposition modeling (FDM)
or fused filament fabrication (FFF). Wire 3D printing can comprise
electron beam freeform fabrication (EBF3). Granular 3D printing can
comprise direct metal laser sintering (DMLS), electron beam melting
(EBM), selective laser melting (SLM), selective heat sintering
(SHS), or selective laser sintering (SLS). Power bed and inkjet
head 3D printing can comprise plaster-based 3D printing (PP).
Laminated 3D printing can comprise laminated object manufacturing
(LOM). Light polymerized 3D printing can comprise
stereo-lithography (SLA), digital light processing (DLP) or
laminated object manufacturing (LOM). Furthermore, preheating can
apply to a filament shaping deposition system and method for 3D
printing developed by the inventor(s) and disclosed in U.S. patent
application Ser. No. 15/471,786, which is incorporated by reference
herein.
[0008] In some instances, the speed at which some 3D printing
processes can be operated is limited by the thermal response time
of the feedstock. This response time is technically described as
the relaxation or reptation time under polymer reptation
theory.
[0009] The more quickly the polymer feed to a 3D printer is heated,
the more material the printer can process in a given
period-of-time. But thermal degradation may occur if a feedstock is
heated too quickly. This degradation can involve chain scission
(i.e., breaking). The resulting segments can react with one another
and change the properties of the feedstock. This can lead to
degradation in physical properties in a printed object relative to
initially specified properties. Such property changes include
reduced ductility and embrittlement, chalking, color changes,
cracking, and a general reduction in most other desirable physical
properties.
[0010] In some instances, the feedstock may be a polymer. To avoid
thermal degradation, a polymer may be given time to "relax" to
accommodate the energy it receives. The time it takes for a polymer
chain to relax can be unique to each polymer and can be dictated by
the "reputation" or relaxation time of the polymer. Reptation is
the thermal motion of very long, linear, entangled macromolecules
in the polymer melt stage. The reputation time may be the time a
polymer chain takes to diffuse out of a virtual tube to which the
polymer is considered to be confined. The speed at which a polymer
filament can be processed may be limited by reptation.
[0011] In some instances, a heating profile for 3D printing
processes comprises raising the temperature of the polymer feed to
its melting point in a single step. The temperature increase can
occur either immediately before or after deposition, as a function
of the 3D printing process. The rate at which the temperature is
raised and at which the polymer is processed may be limited by the
reptation time. If the polymer feed is preheated to a temperature
at or above its glass transition temperature (T.sub.g) while in the
3D printer, and subsequently raised to its melting temperature
(either immediately before or after deposition per the specific
process), the polymer can be processed more rapidly.
[0012] In some instances, the polymer feed may have a residence
time in the 3D printer, and to the extent the feed is preheated
during that residence time, there may be no "cost" to the time
required for such preheating. There may be a "cost" for the time it
takes to melt the feedstock, which occurs at the exit of 3D printer
or on the build surface. In other instances when the feed is
entering the melting zone at much higher temperature than may
otherwise be the case, the melting time may be significantly
reduced. In fact, experiments have demonstrated a five- to six-fold
increase in the speed at which polyaryletherketones (PEAK) polymer
feeds can be processed by virtue of the novel preheating step
disclosed herein.
[0013] At the glass transition temperature, the polymer chains may
become increasingly mobile and can slide past one another, thereby
processing the energy received during heating. Since the polymer
feed may be more mobile during the melting step than the preheating
step, the polymer can be heated at a greater rate during the
melting step. This may further increase the processing time.
[0014] Thus, in accordance with the present disclosure, various 3D
printing devices and methods may be improved by preheating the
polymer feed to a temperature at or above its glass transition
temperature, but below its melting point, prior to melting the
polymer for incorporation into the build object.
[0015] In another aspect, the system comprises a filament-shaping
deposition system with preheat for additive manufacturing. In some
embodiments, preheat may be added to other 3D printing processes,
including material extrusion, directed energy deposition, and
material jetting processes.
[0016] In an embodiment, a filament-shaping deposition system can
include a positioning subsystem, a feed subsystem, an optional
preheating subsystem, a focused heat source, and/or a filament
shaper.
[0017] In another embodiment, the positioning subsystem may
comprise a multi-axis end effector (e.g., a robotic arm, etc.). The
multi-axis end effector may have sufficient degrees of freedom
(i.e., six DOF) to enable true three-dimensional printing. The
positioning subsystem may be capable of delivering a feed filament
to an arbitrary location in space, as specified in accordance with
the build instructions.
[0018] The feed subsystem may deliver the feedstock to a build
surface (e.g., a build plate, etc.). The focused heat source may be
used to (a) raise the temperature of the feedstock to its melting
point, and (b) melt the previously deposited layer of material just
below the feedstock currently being deposited. The focused heat
source may be a laser. The filament shaper can apply pressure to
the melted filament, thereby controlling its position/location and
altering its cross section from circle to flat-rectangular (i.e.,
ribbon-like). Altering the filament's cross section in the
aforementioned fashion may result in improvements in the properties
of the printed object.
[0019] The preheating subsystem may be embodied in a variety of
ways, which can be different for different 3D printing processes as
a function of their varying configurations. Some non-limiting
embodiments of the preheating sub-system, for use in context with
applicant's filament-shaping deposition method, are discussed
below.
[0020] The preheating subsystem may comprise a direct contact
heater for the feedstock tube or guide through which the feedstock
passes prior to deposition. In some embodiments, the heater, in the
form of ribbon, wire or other flexible material, may be wrapped
around the exterior of the feed tube below an in-line cutter.
[0021] Alternatively, the preheating subsystem may comprise forced
hot air. The hot air may be delivered from a hot air blower. In
some instances, slots, which are formed in the feed tube below the
in-line cutter, can provide for direct contact between the hot air
and the feedstock.
[0022] A laser may be used to preheat the feedstock. In some
instances, a laser with sufficient power, dedicated for preheating,
may be used. The beam from the laser can be directed at the portion
of the feed tube below the in-line cutter. In other instances, the
beam from the focused heat source may be split into two beams of
unequal intensity. The beam with the lower intensity can be
directed to the portion of the feed tube below the in-line cutter
for preheating the feedstock. The beam with the higher intensity
may be directed to the feedstock and/or the most recently deposited
underlying layer.
[0023] Additional aspects and advantages of the present disclosure
may become readily apparent to those skilled in this art from the
following detailed description, wherein only illustrative
embodiments of the present disclosure are shown and described. As
will be realized, the present disclosure is capable of other and
different embodiments, and its several details are capable of
modifications in various obvious respects, all without departing
from the disclosure. Accordingly, the drawings and description are
to be regarded as illustrative in nature, and not as
restrictive.
INCORPORATION BY REFERENCE
[0024] All publications, patents, and patent applications mentioned
in this specification are herein incorporated by reference to the
same extent as if each individual publication, patent, or patent
application was specifically and individually indicated to be
incorporated by reference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The novel features of the invention are set forth with
particularity in the appended claims. A better understanding of the
features and advantages of the present invention will be obtained
by reference to the following detailed description that sets forth
illustrative embodiments, in which the principles of the invention
are utilized, and the accompanying drawings (also "figure" and
"FIG." herein), of which:
[0026] FIG. 1 depicts a block diagram of the salient components of
a filament-shaping deposition system for additive
manufacturing;
[0027] FIG. 2 depicts a first embodiment of the filament-shaping
deposition system of FIG. 1;
[0028] FIG. 3 depicts a second embodiment of the filament-shaping
deposition system of FIG. 1;
[0029] FIG. 4 depicts a third embodiment of the filament-shaping
deposition system of FIG. 1;
[0030] FIG. 5 depicts a fourth embodiment of the filament-shaping
deposition system of FIG. 1;
[0031] FIG. 6 depicts a side view of a portion of a material
extrusion (fused deposition modeling) 3D printer, in accordance
with the present disclosure;
[0032] FIG. 7 depicts a side view of a portion of a directed energy
deposition three-dimensional (3D) printer, in accordance with the
present disclosure;
[0033] FIG. 8 depicts a method in accordance with an illustrative
embodiment of the present system;
[0034] FIG. 9 depicts a method for using a temperature control loop
to control a preheating operation;
[0035] FIG. 10 depicts the heating profile of the polymer feed, in
accordance with the present disclosure;
[0036] FIGS. 11A-11C depict various embodiments of preheating and
melting zones for various 3D printer configurations; and
[0037] FIG. 12 depicts a computer control system that is programmed
or otherwise configured to implement methods provided herein.
DETAILED DESCRIPTION
[0038] While various embodiments of the invention have been shown
and described herein, it will be obvious to those skilled in the
art that such embodiments are provided by way of example only.
Numerous variations, changes, and substitutions may occur to those
skilled in the art without departing from the invention. It should
be understood that various alternatives to the embodiments of the
invention described herein may be employed.
[0039] The term "three-dimensional printing" (also "3D printing"),
as used herein, generally refers to a process or method for
generating a 3D part (or object). For example, 3D printing may
refer to sequential addition of material layer or joining of
material layers or parts of material layers to form a
three-dimensional (3D) part, object, or structure, in a controlled
manner (e.g., under automated control). In the 3D printing process,
the deposited material can be fused, sintered, melted, bound or
otherwise connected to form at least a part of the 3D object.
Fusing the material may include melting or sintering the material.
Binding can comprise chemical bonding. Chemical bonding can
comprise covalent bonding. Examples of 3D printing include additive
printing (e.g., layer by layer printing, or additive
manufacturing). The 3D printing may further comprise subtractive
printing.
[0040] The term "part," as used herein, generally refers to an
object. A part may be generated using 3D printing methods and
systems of the present disclosure. A part may be a portion of a
larger part or object, or an entirety of an object. A part may have
various form factors, as may be based on a model of such part. Such
form factors may be predetermined.
[0041] The term "composite material," as used herein, generally
refers to a material made from two or more constituent materials
with different physical or chemical properties that, when combined,
produce a material with characteristics different from the
individual components.
[0042] The term "fuse", as used herein, generally refers to
binding, agglomerating, or polymerizing. Fusing may include
melting, softening or sintering. Binding may comprise chemical
binding. Chemical binding may include covalent binding. The energy
source resulting in fusion may supply energy by a laser, a
microwave source, source for resistive heating, an infrared energy
(IR) source, a ultraviolet (UV) energy source, hot fluid (e.g., hot
air), a chemical reaction, a plasma source, a microwave source, an
electromagnetic source, or an electron beam. Resistive heating may
be joule heating. A source for resistive heating may be a power
supply. The hot fluid can have a temperature greater than
25.degree. C., or greater than or equal to about 40.degree. C.,
50.degree. C., 60.degree. C., 70.degree. C., 80.degree. C.,
90.degree. C., 100.degree. C., 150.degree. C., 200.degree. C.,
250.degree. C., 300.degree. C., 350.degree. C., 400.degree. C.,
450.degree. C., 500.degree. C., or higher. The hot fluid may have a
temperature that is selected to soften or melt a material used to
print an object. The hot fluid may have a temperature that is at or
above a melting point or glass transition point of a polymeric
material. The hot fluid can be a gas or a liquid. In some examples,
the hot fluid is air.
[0043] The term "adjacent" or "adjacent to," as used herein,
generally refers to `on,` `over, `next to,` adjoining,` `in contact
with,` or `in proximity to.` In some instances, adjacent components
are separated from one another by one or more intervening layers.
The one or more intervening layers may have a thickness less than
about 10 micrometers ("microns"), 1 micron, 500 nanometers ("nm"),
100 nm, 50 nm, 10 nm, 1 nm, 0.5 nm or less. For example, a first
layer adjacent to a second layer can be on or in direct contact
with the second layer. As another example, a first layer adjacent
to a second layer can be separated from the second layer by at
least a third layer.
[0044] Examples of 3D printing methodologies comprise extrusion,
wire, granular, laminated, light polymerization, VAT
photopolymerization, material jetting, binder jetting, sheet
lamination, directed energy deposition, or power bed and inkjet
head 3D printing. Extrusion 3D printing can comprise robo-casting,
fused deposition modeling (FDM) or fused filament fabrication
(FFF). Wire 3D printing can comprise electron beam freeform
fabrication (EBF3). Granular 3D printing can comprise direct metal
laser sintering (DMLS), electron beam melting (EBM), selective
laser melting (SLM), selective heat sintering (SHS), or selective
laser sintering (SLS). Power bed and inkjet head 3D printing can
comprise plaster-based 3D printing (PP). Laminated 3D printing can
comprise laminated object manufacturing (LOM). Light polymerized 3D
printing can comprise stereo-lithography (SLA), digital light
processing (DLP) or laminated object manufacturing (LOM).
[0045] Examples of methods, systems and materials that may be used
to create or generate objects or parts herein are provided in U.S.
Patent Publication Nos. 2014/0232035, 2016/0176118, and U.S. patent
application Ser. Nos. 14/297,185, 14/621,205, 14/623,471,
14/682,067, 14/874,963, 15/069,440, 15/072,270, 15/094,967, each of
which is entirely incorporated herein by reference.
[0046] Three-dimensional printing may be performed using various
materials. The form of the build materials that can be used in
embodiments of the present disclosure include, without limitation,
filaments, sheets, powders, and inks. In some examples, a material
that may be used in 3D printing includes a polymeric material,
elemental metal, metal alloy, a ceramic, composite material, an
allotrope of elemental carbon, or a combination thereof. The
allotrope of elemental carbon may comprise amorphous carbon,
graphite, graphene, diamond, or fullerene. The fullerene may be
selected from the group consisting of a spherical, elliptical,
linear, tubular fullerene, and any combination thereof. The
fullerene may comprise a buck ball or a carbon nanotube. The
material may comprise an organic material, for example, a polymer
or a resin. The material may comprise a solid or a liquid. The
material may include one or more strands or filaments. The solid
material may comprise powder material. The powder material may be
coated by a coating (e.g., organic coating such as the organic
material (e.g., plastic coating)). The powder material may comprise
sand. The material may be in the form of a powder, wire, pellet, or
bead. The material may have one or more layers. The material may
comprise at least two materials. In some cases, the material
includes a reinforcing material (e.g., that forms a fiber). The
reinforcing material may comprise a carbon fiber, Kevlar.RTM.,
Twaron.RTM., ultra-high-molecular-weight polyethylene, or glass
fiber.
[0047] Prior to printing the part or object, a computer aided
design (CAD) model can be optimized based on specified
requirements. For example, the CAD model may comprise a geometry
"envelop". A geometry envelop may be an initial shell design of the
three-dimensional part comprising design requirements and geometric
features. The geometry of the CAD model may be received by way of
I/O devices. Design requirements can be selected from the group
consisting of strength, structural deflections, stress, strain,
tension, shear, load capacity, stiffness, factor-of safety, weight,
strength to weight ratio, envelop geometry, minimal print time,
thermal performance, electrical performance, porosity, infill,
number of shells, layer height, printing temperature, extruder
temperature, solid density, melt density, printing speed, print
head movement speed, and any combination thereof.
[0048] The CAD model may be initially partitioned according to user
input and built in tool path generator rules to produce numerical
control programming codes of the partitioned computer model.
Partitioning can generate one or more parameters for printing the
part. The One or more parameters may be selected from the group
consisting of filament diameter, layer thickness, infill
percentage, infill pattern, raster angle, build orientation,
printed material width, extrudate width, layer height, shell
number, infill overlap, grid spacing, and any combination thereof.
Partitioning can also generate one or more numerical control
programming code of the partitioned computer model. The numerical
control programming code can comprise G-code files and intermediate
files. G-code files may be a numerical control programming language
and can be used in computer-aided manufacturing as a way of
controlling automated machine tools. The actions controlled by the
G-code may comprise rapid movement, controlled feed in an arc or
straight line, series of controlled feed movements, switch
coordinate systems, and a set of tool information. Intermediate
files may comprise supplemental files and tools for a primary build
output. Additionally, intermediate files can comprise automatically
generated source files or build output from helper tools. The
information from the G-code files and the intermediate files may be
extracted to determine the geometry of the three-dimensional
printed part.
[0049] The 3D object may have a 3D solid model created in CAD
software. Such 3D object can be sliced using an algorithm that
generates a series of two dimensional (2D) layers representing
individual transverse cross sections of the 3D object, which may
collectively depict the 3D object. The 2D slice information for the
layers may be sent to the controller and stored in memory. Such
information can control the process of fusing particles into a
dense layer according to the modeling and inputs obtained during
the build process.
[0050] Prior to printing the three-dimensional object, a model, in
computer memory, of the part for three-dimensional printing may be
received from a material. The material can comprise a matrix and
fiber material. Additionally, in computer memory, one or more
properties for the material may be received. Using the model, a
print head tool path may be determined for use during the
three-dimensional printing of the part. A virtual mesh of analytic
elements may be generated within the model of the part and a
trajectory of at least one stiffness-contributing portion of the
material may be determined based at least in part on the print head
tool path, wherein the trajectory of the at least one
stiffness-contributing portion is determined through each of the
analytic elements in the virtual mesh. Next, one or more computer
processors may be used to determine a performance of the part based
at least in part on the one or more properties received and the
trajectory of the at least one stiffness-contributing portion. The
performance of the part may be electronically outputted. The
three-dimensional object may then be printed along the print head
tool path.
[0051] The present disclosure may provide ways to improve the
mechanical, thermal, and electrical properties of additively
manufactured parts. All additive manufacturing approaches build up
an object in a layer-by-layer fashion. In other words, the layers
of build material are deposited one on top of the next, such that a
successive layer of build material is deposited upon a previously
deposited/constructed layer that has cooled below its melting
temperature. The print head may comprise three or more axes or
degrees of freedom so that the print head can move in the +X
direction, the -X direction, the +Y direction, the -Y direction,
the +Z direction, the -Z direction, or any combination thereof. The
print head may be configured as a six-axis robotic arm.
Alternatively, the print head may be configured as a seven-axis
robotic arm. The print head may be placed at any location in the
build volume of the 3D object, from any approach angle.
[0052] Prior to printing the 3D object, a request for production of
a requested 3D object may be received from a customer. The method
may comprise packaging the three dimensional object. After printing
of the 3D object, the printed three dimensional object may be
delivered to the customer.
[0053] In an aspect, the present disclosure provides for method for
printing at least a portion of a 3D object.
[0054] FIG. 8 depicts method 800 in accordance with the
illustrative embodiment of the present disclosure. The method may
be applicable to various 3D printer technologies. In accordance
with task S801, the polymer feed may be preheated to a temperature
above its glass transition temperature T.sub.g but below the
melting point. This may soften the polymer feed. The temperature to
which the feed is preheated can depend on the polymer and its
relative stiffness at the glass transition temperature. Some
materials may remain relatively stiff at T.sub.g while others can
soften rather quickly above T.sub.g. In some instances, the stiffer
the material is at the glass transition temperature, the higher the
preheat temperature (i.e., closer to the melting point). The feed
may be preheated to a temperature that is at least about 0.3, at
least about 0.35, at least about 0.4, at least about 0.45, at least
about 0.5, at least about 0.55, at least about 0.6, at least about
0.65, at least about 0.7, at least about 0.75, at least about 0.80,
at least about 0.85, at least about 0.9, or at least about 0.95 of
its melting point. In other instances, the feed may be preheated to
a temperature that is at most about 0.95, at most about 0.9, at
most about 0.85, at most about 0.8, at most about 0.75, at most
about 0.7, at most about 0.65, at most about 0.6, at most about
0.55, at most about 0.5, at most about 0.45, at most about 0.4, at
most about 0.35, or at most about 0.3 of its melting point. The
feed may be preheated to a temperature that is in a range of about
0.3 to about 0.95 of its melting point, or about 0.5 to about 0.95
of its melting point, or about 0.7 to about 0.95 of its melting
point, or about 0.7 to about 0.8 of its melting point, or about 0.8
to about 0.9 of its melting point.
[0055] In task S802, the polymer feed may be heated to its melting
point. The separate devices may preheat the feed and can melt the
feed. In some instances, two different type of devices may be used
for the preheat step and the melt step (e.g., a direct contact
heater for preheat and a laser for melting, etc.). Alternatively,
two different instances of the same type of device may be used for
the preheat step and the melt step (e.g., a first laser for
preheat, a second laser for melt, etc). The same device may be used
for both preheat and melt (e.g., a single laser with a beam
splitter, etc.). The device may be selected from the group
consisting of a laser, a microwave source, a resistive heating
source, an infrared energy source, a UV energy source, hot fluid
(e.g. hot air), a chemical reaction, a plasma source, a microwave
source, an electromagnetic source, and an electron beam. Resistive
heating may be joule heating. A source for resistive heating may be
a power supply. The applied energy is primarily a function of the
chemical composition of the build material, such as the build
material's thermal conductivity, heat capacity, latent heat of
fusion, melting point, and melt flow viscosity.
[0056] In some instances, simple experimentation may be used to
determine the heat input required for preheating and melting, as a
function of the polymer feed and feed rate. In other instances, a
temperature control loop may be implemented to control the
preheating operation, such as the notional control loop depicted in
FIG. 9.
[0057] Task S801 may comprise subtasks S901 through S904. In
subtask S901, preheating may begin with the delivery of energy to
the polymer feed. Preheat can be provided by any heating
arrangement suitable for the configuration of the particular 3D
printer being used, some of which arrangements are disclosed later
in this specification.
[0058] In subtask S902, the temperature of polymer feed may be
determined using any appropriate measurement device/technique, such
as thermocouples, resistance temperature devices, infrared
temperature measurement devices, bimetallic temperature measurement
devices, fluid-expansion temperature measurement devices,
change-of-state temperature measurement devices, and the like.
[0059] Query can occur, at subtask S903, if the temperature of the
feed is less than the target (i.e., controller set-point)
temperature, TT, wherein, as previously noted:
T.sub.g.ltoreq.TT<melting point of the polymer feed. The
temperature may be measured at the end of the preheating zone or,
alternatively, right before the feed reaches the zone in which it
will be melted.
[0060] If the measured temperature is less than the target
temperature, processing can loop back to S901 to increase the
amount of energy being delivered to the feed. The loop of subtasks
S901 through S903 may be repeated until the answer to the query at
S903 is "no."
[0061] When the temperature of the feed is not less than the target
temperature, the system can reduce the energy delivered to the
polymer feed at subtask S904. Processing may then loop back to
subtask S902 wherein the temperature of the polymer feed is
measured. The loop of subtasks S902 through S904 can be repeated
until the answer to the query at S903 is "yes".
[0062] In some instances, the operation of a temperature controller
may apply closed-loop feedback control. The temperature control
loop disclosed in FIG. 9 can be implemented using, for example, a
temperature control system including a temperature measurement
device, a controller (e.g., PI or PID, etc.), and an actuator,
etc., to alter the energy being provided to the process by the
preheater. A separate temperature-control loop can be used to
control melting operation S802 of method 800.
[0063] Print speed may be limited to the rate at which the polymer
feed can be melted. In some instances, the rate may be limited by
the relaxation time or reptation time, which is characteristic of
the particular polymer feed. Thus, given the small zone in which
melting occurs and the aforementioned limitation on heating rate
due to relaxation time, a bottleneck can occur.
[0064] In some instances, there may be a certain residence time of
the polymer feed in a 3D printer as a consequence of the printer's
configuration (feed lines, etc.). Since the polymer may traverse
some distance through the printer and can take some time doing so,
that time can be used, at no penalty, to preheat the polymer feed.
When preheated, the polymer feed may approach the melting zone at
or above (in some cases well above) its glass transition
temperature. The feed may enter the melting zone at a high
temperature; consequently, much less of a temperature increase is
required to melt the feed. The system may require much less time to
melt the feed. Since the polymer feed can be melted more quickly,
the polymer feed may also comprise a faster processing speed. The
present method and system can result in at least about a 3 fold, at
least about a 4 fold, at least about a 5 fold, at least about a 6
fold, at least about a 7 fold, or at least about a 10 fold increase
in polymer feed rate (processing speed) for PEAK polymer feeds.
[0065] With reference to FIG. 10, the time it takes to preheat the
feed (i.e., to a temperature well above its glass transition
temperature) can be represented by the time interval (P2-P1). The
time it takes to heat the feed from its preheat temperature to its
melt point may be represented by the time interval (P3-P2). The
time to melt the feed may be reduced by the amount (P2-P1). Thus,
the time spent in the melting zone can be reduced by the fraction
(P2-P1)/(P3-P1). Equivalently, the feed rate can be increased by
the ratio (P2-P1)/(P3-P2).
[0066] For example, a polymer filament may have a heating rate of
500.degree. C./second. The polymer filament can comprise PEEK
(T.sub.g=140.degree. C. and processing temp=360.degree. C.) with a
preheat temperature of 290.degree. C. and a feed temperature of
25.degree. C. The preheat step can occur in (290-25)/500=0.53
seconds. And raising the temperature from 290.degree. C. to
360.degree. C. for the melting step may occur in (360-290)/500=0.14
seconds. Thus, in the absence of the preheat, the melting step can
require 0.53+0.14=0.67 seconds. This represents an increase in the
processing rate of the feed by a factor of 0.67/0.14=4.8. Since the
time to print an object (e.g., a commercial part, etc.) can take
hours, the time-savings afforded by embodiments of the present
disclosure is quite significant.
[0067] In some instances, preheating and melting may occur in two
spatially distinct zones, as represented in FIGS. 11A-11C. FIG. 11A
illustrates a preheating zone Z1 and a melting zone Z2 that are in
two spatially distinct regions 1193 and 1195 in the same element of
the 3D printer, such as in feed line 1191. In other instances, such
as depicted in FIG. 11B, preheating zone Z1 and melting zone Z2 may
be located in two distinct elements of the 3D printer. For example,
preheating zone Z1 can be in feed line 1191 and melting zone Z2 can
be in heating block 1197. Alternatively, FIG. 11C illustrates a
preheating zone Z1 that is located in the 3D printer and a melting
zone Z2 that is located outside of the 3D printer. For example,
preheating zone Z1 can be in feed line 1191 and melting zone Z2 can
be on build surface 1199.
[0068] In some instances, due to the spatial separation between the
preheating zone and the melting zone, the temperature at which the
feed enters the melting zone may be slightly lower than the
temperature at which the feed exits the preheating zone. Thus, in
FIG. 10, for some embodiments, the feed may not exit the preheating
zone and enter the melting zone at the same time P2. Rather, it can
enter the melting zone at some time after P2 and before P3, and the
curve dips (i.e., temperature declines) after P2 due to some
minimal cooling that occurs in the filament before heating in the
melting zone occurs.
[0069] FIG. 1 depicts functional elements of filament-shaping
deposition system 100 in accordance with the present disclosure.
System 100 may comprise positioning subsystem 102, feed subsystem
104, preheating subsystem 106, focused heat source 108, and
filament shaper 110.
[0070] The positioning subsystem 102 may comprises a multi-axis end
effector. Printing with such a multi-axis end effector is
described, for example, in Ser. No. 14/184,010, previously
referenced.
[0071] Feed subsystem 104 may deliver at least one feedstock to a
build surface (e.g., a plate, etc.). In some instances, if the
manufacture of a part has already begun, the at least one feedstock
may be delivered to a previously deposited layer of filament. The
term "build surface," as used in this disclosure and the appended
claims, refers to either a build plate, substrate, or a previously
deposited layer of material, or anything else that the at least one
feedstock may be deposited upon. In some instances, the at least
one feedstock may be a filament material. The source of at least
one filament material may be configured to supply at least one
filament material for generating the three-dimensional object. The
at least one feedstock may comprise a thermoplastic resin. In other
instances, the filament may comprise a thermoplastic composite
material, such as a cylindrical towpreg consisting of a continuous
fiber (e.g., 1K, 3K, 6K, 12K, 24K, etc.) impregnated with
thermoplastic resin. The filament material may be nano milled,
short, long, continuous, or a combination thereof. The continuous
fiber composite may be a continuous core reinforced filament. The
continuous core reinforced filament can comprise a towpreg that is
substantially void free and includes a polymer that coats or
impregnates an internal continuous core. Depending upon the
particular embodiment, the core may be a solid core or it may be a
multi-strand core comprising multiple strands. The continuous fiber
includes, without limitation, carbon, fiberglass, aramid (AKA
Kevlar), cotton, silicon carbide, polymer, wool, metal, and carbon
nanotubes (CNT).
[0072] The thermoplastic can be a semi-crystalline polymer or a
mixture of a semi-crystalline polymer and an amorphous polymer. The
semi-crystalline material can be, for example and without
limitation, a polyaryletherketone (PAEK), such as polyetherketone
(PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK),
polyetheretherketoneketone (PEEKK), and
bolyetherketoneetherketoneketone (PEKEKK). The semi-crystalline
polymer can also be other semi-crystalline thermoplastics, for
example and without limitation, polyamide (PA), polybutylene
terephthalate (PBT), poly(p-phenylene sulfide) (PPS).
[0073] If the feed is a blend of an amorphous polymer with a
semi-crystalline polymer, the semi-crystalline polymer can be one
of the aforementioned materials and the amorphous polymer can be a
polyarylsulfone, such as polysulfone (PSU), polyethersulfone
(PESU), polyphenylsulfone (PPSU), polyethersulfone (PES),
polyetherimide (PEI). In some additional embodiments, the amorphous
polymer can be, for example and without limitation, polyphenylene
oxides (PPOs), acrylonitrile butadiene styrene (ABS), methyl
methacrylate acrylonitrile butadiene styrene copolymer (ABSi),
polystyrene (PS), and polycarbonate (PC).
[0074] The filament material may incorporate one or more additional
materials, such as resins and polymers. For example, appropriate
resins and polymers include, but are not limited to, acrylonitrile
butadiene styrene (ABS), epoxy, vinyl, nylon, polyetherimide (PEI),
Polyaryletherketone (PAEK), Polyether ether ketone (PEEK),
Polyactic Acid (PLA), Liquid Crystal Polymer, polyamide, polyimide,
polyphenylene sulfide, polyphenylsulfone, polysulfone, polyether
sulfone, polyethylenimine, polytetrafluoroethylene, polyvinylidene,
and various other thermoplastics. The core of the continuous fiber
composite may be selected to provide any desired property.
Appropriate core fiber or strands include those materials which
impart a desired property, such as structural, conductive
(electrically and/or thermally), insulative (electrically, and/or
thermally), optical and/or fluidic transport. Such materials
include, but are not limited to, carbon fibers, aramid fibers,
fiberglass, metals (such as copper, silver, gold, tin, and steel),
optical fibers, and flexible tubes. The core fiber or strands may
be provided in any appropriate size. Further, multiple types of
continuous cores may be used in a single continuous core reinforced
filament to provide multiple functionalities such as electrical and
optical properties. A single material may be used to provide
multiple properties for the core reinforced filament. For example,
a steel core may be used to provide both structural properties as
well as electrical conductivity properties.
[0075] Alternatively, the filament material may comprise metal
particles infused into a binder matrix. The metal particles may be
metal powder. The binder matrix may include resins or polymers.
Additionally, such binder matrix can be used a delivery device for
the metal particles. In the blend, the weight ratio of
semi-crystalline material to amorphous material in a range of about
30:70 to about 95:05, inclusive, 40:60 to about 95:05, inclusive,
50:50 to about 95:05, inclusive, about 30:70 to about 90:10,
inclusive, 40:60 to about 90:10, inclusive, about 50:50 to about
90:10, inclusive, about 60:40 to about 95:05, inclusive, about
60:40 to about 90:10, inclusive, about 60:40 to about 80:20,
inclusive, or about 60:40 to about 70:30, inclusive. The weight
ratio of semi-crystalline material to amorphous material in the
blend may be between 60:40 and 80:20, inclusive. The ratio selected
for any particular application may vary primarily as a function of
the materials used and the properties desired for the printed
object.
[0076] The preheating subsystem 106 may heat the at least one
feedstock before it is delivered to the build surface. The at least
one feedstock may be heated to a temperature that is above its
glass transition temperature, T.sub.g and can increase the rate at
which the feedstock-shaping deposition system can process a
feedstock.
[0077] Focused heat source 108 may be used to: (a) raise the
temperature of the feedstock to melting after it is delivered to
the build object. The focused heat source may be an energy source.
The energy source resulting in fusion may supply energy by a laser,
a microwave source, source for resistive heating, an infrared
energy (IR) source, a ultraviolet (UV) energy source, hot fluid
(e.g., hot air), a chemical reaction, a plasma source, a microwave
source, an electromagnetic source, or an electron beam. Resistive
heating may be joule heating. A source for resistive heating may be
a power supply. The hot fluid can have a temperature greater than
25.degree. C., or greater than or equal to about 40.degree. C.,
50.degree. C., 60.degree. C., 70.degree. C., 80.degree. C.,
90.degree. C., 100.degree. C., 150.degree. C., 200.degree. C.,
250.degree. C., 300.degree. C., 350.degree. C., 400.degree. C.,
450.degree. C., 500.degree. C., or higher. The hot fluid may have a
temperature that is selected to soften or melt a material used to
print an object. The hot fluid may have a temperature that is at or
above a melting point or glass transition point of a polymeric
material. The hot fluid can be a gas or a liquid. In some examples,
the hot fluid is air.
[0078] In some instances, focused heat source 108 may be a laser.
The laser may facilitate accurate control of the processing
temperature of the feedstock. In other instances, focused heated
sources 108 other than a laser may be used, such as, without
limitation, a concentrated microwave source (MASER), focused
ultrasonic sound, focused IR, ion beam, electron beam, and focused
hot air.
[0079] Filament shaper 110 can apply pressure to the melted
filament, thereby altering its cross section from substantially
circular (circular, ellipsoidal, or rectangular) to
flat-rectangular (i.e., ribbon-like) facilitating the consolidation
of the melted filament into the geometry of the desired object. The
filament shaper may be a compaction unit.
[0080] In some instances, at least one filament material may be
directed to a compaction unit. Such filament material may be
compacted by the compaction unit to form at least one compacted
filament material. The compaction unit may comprise a rigid body,
one or more idler rollers, at least one freely suspended roller, a
coolant unit, or any combination thereof. The at least one freely
suspended roller may be a compaction roller. The rigid body and one
or more idler rollers may secure the at least one freely suspended
roller. Such freely suspended rollers may have a diameter of at
most about 1 mm, at most about 2 mm, at most about 3 mm, at most
about 4 mm, at most about 5 mm, at most about 6 mm, at most about 7
mm, at most about 8 mm, at most about 9 mm, at most about 10 mm, or
at most about 15 mm. The coolant may be used to cool the compaction
unit so the at least one filament material does not stick to the
roller and adheres to the previously deposited layer of the
three-dimensional object.
[0081] The system for printing at least a portion of the 3D object
may further comprise one or more cooling components. Such cooling
components may be in proximity to the deposited filament material
layer. Such cooling components can be located between the deposited
filament material layer and the energy source. Such cooling
components may be movable to or from a location that may be
positioned between the filament material and the energy source.
Such cooling components may assist in the process of cooling of the
fused portion of the filament material layer. Such cooling
components may also assist in the cooling of the filament material
layer remainder that did not fuse to subsequently form at least a
portion of the 3D object. Such cooling components can assist in the
cooling of the at least a portion of the 3D object and the
remainder at considerably the same rate. Such cooling components
may be separated from the filament material layer and/or from the
substrate by a gap. The gap may comprise a gas. The gap can have a
cross-section that is at most about 0.1 mm, at most about 0.5 mm,
at most about 1 mm, at most about 5 mm, or at most about 10 mm. The
gap can be adjustable. The controller may be operatively connected
to such cooling components and may be able to adjust the gap
distance from the substrate. Such cooling components can track an
energy that may be applied to the portion of the filament material
layer by the energy source. Such cooling components may comprise a
heat sink. Such cooling components may be a cooling fan. The
controller may be operatively coupled to such cooling components
and controls the tracing of such cooling components. Such cooling
components may include at least one opening though which at least
one energy beam from the energy source can be directed to the
portion of the filament layer. The system for printing at least a
portion of the 3D object can further comprise an additional energy
source that provides energy to a remainder of the filament material
layer that did not fuse to subsequently form at least a portion of
the 3D object.
[0082] During printing of the three-dimensional object, certain
parameters may be critical to printing high quality parts. One or
more sensors can be used to measure one or more temperature(s)
along at least one filament material. Such sensors can control
intensities, positions, and/or angles of at least the first energy
beam. The one or more sensors may be an optical pyrometer. Optical
pyrometers may be aimed the substrate to detect the temperature of
the at least one filament materials as they are deposited. Optical
pyrometers may be aimed at the nip points and one or more points
before and/or after the compaction unit to detect the temperature
of the at least one filament materials as they are deposited. The
temperature may vary from region to region of the filament material
layer. Factors that affect temperature variance can include
variable heater irradiance, variations in absorptivity of the
composition, substrate temperature, filament material temperature,
unfused filament material temperature, and the use of modifiers and
additives. Accordingly, image and temperature measurement inputs
based upon layer temperature patterns captured by the one or more
sensors may be used. The real time temperature inputs and the
sintering model may be factors determining an energy requirement
pattern for any one or more subsequent layers.
[0083] Additionally, the system may comprise a real time simulation
program to provide feedback control of a given location, direction,
or angle of at least the first energy beam normal to the substrate
and/or along the substrate among one or more locations, directions,
or angles. The sample real time simulation of the optical beam path
illustrates that choosing the appropriate energy beam orientation
may result in the elliptical beam profile. The real time simulation
program may be a feedback control system. The feedback control
system may be a Zemax simulation of the beam propagation.
[0084] Other parameters critical to printing high quality parts can
include substrate temperature, melt zone temperature, as-built
geometry, surface roughness and texture and density. Other critical
visible or non-visible metrics include characterization of
chemistry, bonding or adhesion strength. Measuring one or more
structural or internal properties of the part can comprise one or
more methods selected from the group consisting of scattered and
reflected or absorbed radiation, x-ray imaging, sound waves,
scatterometry techniques, ultrasonic techniques, X-ray
Photoelectron Spectroscopy (XPS), Four Transform Infrared
Spectroscopy (FTIR), Raman Spectroscopy, Laser-Microprobe Mass
Spectrometry (LMMS), and any combination thereof. Specific
metrology beneficial to the end goals of characterizing the
critical process parameters can be used. This in-situ metrology
coupled with fast processing of data can enable open or closed loop
control of the manufacturing process. Sensors appropriate to the
key parameters of interest can be selected and utilized during the
part printing process. The sensors may also comprise a camera for
detecting light in the infrared or visible portion of the
electromagnetic spectrum. Sensors such as IR cameras may be used to
measure temperature fields. An image processing algorithm may be
used to evaluate data generated by one or more sensors, to extract
one or more structural or internal properties of the part. Visual
(e.g., high magnification) microscopy from digital camera(s) can be
used with proper software processing to detect voids, defects, and
surface roughness. In order to utilize this technique, potentially
large quantities of data may be interrogated using image processing
algorithms in order to extract features of interest. Scatterometry
techniques may be adapted to provide roughness or other data.
[0085] Ultrasonic techniques can be used to measure solid density
and fiber and particle density which in turn may be useful in
characterizing bond strength and fiber dispersion. The
characterization can affect material strength. Ultrasonic
techniques can also be used to measure thickness of features.
Chemical bonding characterization, which may be useful for
understanding fiber and/or matrix adhesion and layer-to-layer
bonding, can be performed by multiple techniques such as XPS (X-ray
Photoelectron Spectroscopy), FTIR (Four Transform Infrared
Spectroscopy) and Raman Spectroscopy and Laser-Microprobe Mass
Spectrometry (LMMS). One or more of these techniques may be
utilized as part of the in-situ metrology for 3D printing. Ex-situ
techniques may also be utilized in order to help provide
appropriate calibration data for the in-situ techniques.
[0086] Sensors may be positioned on the robot end-effector of the
three-dimensional printer in order to provide a sensor moving along
with the deposited material. A robot end-effector may be a device
positioned at the end of a robotic arm. The robot end-effector may
be programmed to interact with its surrounding environment. Sensors
may be also located at other various positions. The positions can
be on-board the robot, on the effector, or deployed in the
environment. Sensors may be in communication with the system. The
system can further comprise one or more processors, a communication
unit, memory, power supply, and storage. The communications unit
can comprise an input and an output. The communication unit can be
wired or wireless. The sensor measurements may or may not be stored
in a database, and may or may not be used in future simulation and
optimization operations. In-situ measurements may also be made
using alternative methods with sensors in a cell but not directly
attached to the robot end-effector.
[0087] FIG. 2 depicts a feedstock-shaping deposition system 100A in
accordance with an illustrative embodiment of the present
disclosure. System 100A may comprise the functional elements of
system 100 depicted in FIG. 1.
[0088] In system 100A of FIG. 2, the positioning subsystem 102 may
be a notional robotic arm 202. The robotic arm can be coupled to
support plate 218, which supports the various subsystems and
elements of system 100A. The robotic arm 202 can move the support
plate 218, and all subsystems/elements attached thereto, so as to
position the system to deliver a feedstock to a desired point in
space consistent with the build instructions.
[0089] In some instances, the robotic arm 202 may be appropriately
configured with rigid members 214 and joints 216 to provide six
degrees of freedom (three in translation: x, y, and z axes; three
in orientation: pitch, yaw, and roll). Printing with such a robotic
arm is described, for example, in Ser. No. 14/184,010, previously
referenced.
[0090] In other instances, the positioning subsystem 102 may
comprise a gantry (not depicted) having one or two translational
degrees of freedom (x and/or y axes). The build plate (on which the
object is printed) may move in the z direction (and possibly the x
or y direction depending on the gantry capabilities), such that
three degrees of freedom are provided for the build. In other
instances (not depicted), a robotic arm can be supported by a
gantry. A robotic arm, other multi-axis end effector, or gantry
system may be designed or specified to provide the requisite
functionality for system 100A.
[0091] In system 100A, feed subsystem 104 includes spool 220, feed
motor 226, feed tube 228, and cutter 230. Spool 220 may be
rotatably coupled to member 222, the latter of which is attached
(e.g., via bolts 224, etc.) to support plate 218. At least one
feedstock 236 may be wound around spool 220. The at least one
feedstock may pass through motor 226, feed tube 228, and cutter
230. Motor 226 can draws the feedstock 236 from spool 220. As it
passes through cutter 230, the feedstock 236 may be sized in
accordance with build instructions. Feed tube 228 may be attached
to support plate 218, such as via clamps 234.
[0092] After sizing using the in-line cutter 230, feedstock 236 may
be heated using the preheating subsystem 106. In system 100A, the
preheating subsystem may be a direct-contact heater 252, such as in
the form of heating tape, heating cord, etc. The heater may be
wrapped around the exterior of feed tube 228 below in-line cutter
230. Direct-contact heater 352 may be controlled to heat feedstock
236 to a temperature at or above its glass transition temperature,
but below its melting point.
[0093] A sized, preheated segment of feedstock 236 may be delivered
to build plate 250 from delivery end 232 of feed tube 228. In some
instances, the delivery end 232 of the feed tube 228 may be
configured and/or positioned to deliver the feedstock directly
underneath the feedstock shaper 110. The feedstock shaper may be a
roller 240. The roller can rotate about pin 241 but may be rigidly
coupled to support plate 218 via member 242 and bolts 244.
Although, the roller 240 may be free to rotate about pin 241 along
the x-direction, the roller may also be rigidly coupled to support
plate 218 with respect to movements in along the y-direction and
the z-direction.
[0094] In system 100A, focused heat source 108 may be laser 246,
such as a diode or fiber laser, although other types of lasers may
suitably be used. Laser 246 can be rigidly coupled to support plate
218, such as via clamps 248.
[0095] Laser 246 may be aligned to illuminate the sized segment of
the at least one feedstock that was delivered to the build plate
250. The laser can heat the feedstock to its melting point for
incorporation into the build object.
[0096] The laser may be used as focused heat source 108 because it
enables precise and accurate control of the processing temperature.
Since the laser spot size may be precisely controlled, the laser
can be directed to heat both an underlying previously deposited
layer, as well as the currently deposited layer, to melting. By
melting the underlying layer during the deposition process, the
bonding and adhesion between the layers can increase, enhancing the
overall mechanical properties of the build object.
[0097] Robotic arm 202 positions support plate 218 such that roller
240 applies pressure to the deposited feedstock. The applied
pressure ensures that the feedstock sticks and adheres to the
underlying layer. In the absence of such pressure, gravity may be
available to bond and adhere the feedstock to the underlying layer,
providing a relatively weak interface.
[0098] Furthermore, the applied pressure can reshape the cross
section of the feedstock from cylindrical to rectangular. The
cylindrical towpreg may be transformed into a rectangular tape,
rather than transforming from a circular cross-section to an
ellipsoidal cross section. Ellipsoidal-shaped filaments may result
in gaps and voids in the build object. The gaps and voids at
interfaces can act as nucleation sites for crack propagation,
negatively impacting the mechanical properties of the build
object.
[0099] The rectangular shape (i.e., tape form factor) may be
desired for the deposited feedstock because an object constructed
therefrom will have minimal void space. The reduction in void space
can result in printed objects having relatively better material
properties.
[0100] FIG. 3 depicts the feedstock-shaping deposition system 100B
in accordance with an illustrative embodiment of the present
disclosure. System 100B can comprise all of the functional elements
of system 100 depicted in FIG. 1.
[0101] The various subsystems/elements of system 100B are embodied
as in system 100B of FIG. 3, with the exception of preheating
subsystem 106. That is, positioning subsystem 102 may be a robotic
arm 202. The feed subsystem 104 can comprise a pulley 220, feed
motor 226, feed tube 228, and cutter 230. The focused heat source
108 may be a laser 246. The feedstock shaper 110 can be a roller
240.
[0102] In system 100B, the preheating subsystem 106 may be a forced
hot air system, such as hot air blower 354. The slots 356 can be
formed in the feed tube 228 below the in-line cutter 230, and the
hot air from blower 354 may be directed at that portion of the feed
tube.
[0103] The hot air blower 354 may be controlled to heat feedstock
236 to a temperature at or above its glass transition temperature,
but below its melting point.
[0104] FIG. 4 illustrates the feedstock-shaping deposition system
100C in accordance with an illustrative embodiment of the present
disclosure. System 100C may comprise all of the functional elements
of system 100 depicted in FIG. 1.
[0105] The various subsystems of system 100C may be embodied as in
systems 100B and 100A, with the exception of preheating subsystem
106. That is, positioning subsystem 102 may comprise one or more
elements selected from the group consisting of robotic arm 202,
feed subsystem 104 includes pulley 220, feed motor 226, feed tube
228, and cutter 230. The focused heat source 108 may be a laser
246. The filament shaper 110 may be a roller 240.
[0106] In system 100C, preheating subsystem 106 may be a laser 458.
The laser 458 may have a lower power rating (or is operated at
lower power) than laser 246. The beam from laser 458 can be
directed at the portion of feed tube 228 below in-line cutter 240.
Laser 458 may be controlled to heat filament 236 to a temperature
at or above its glass transition temperature, but below its melting
point.
[0107] FIG. 5 depicts filament-shaping deposition system 100D in
accordance with an illustrative embodiment of the present
disclosure. System 100D includes all of the functional elements of
system 100 depicted in FIG. 1.
[0108] The various subsystems of system 100D are embodied as in
systems 100C, 100B and 100A, with the exception of preheating
subsystem 106. The positioning subsystem 102 may be a robotic arm
202. The feed subsystem 104 may comprise pulley 220, feed motor
226, feed tube 228, and cutter 230. The focused heat source 108 may
be a laser 246. The filament shaper 110 can be a roller 240.
[0109] In system 100D, laser 246 can serve as focused heat source
108 and preheating subsystem 106. Beam splitter 560 may split the
beam from laser 246 into two beams of unequal intensity. Beam 562,
having relatively lower intensity, may be focused on the portion of
feed tube 228 below in-line cutter 230 for preheating the
feedstock. The split may be controlled so that beam 562 heats
feedstock 236 to a temperature at or above its glass transition
temperature, but below its melting point. Beam 564, having
relatively higher intensity, may be focused on the feedstock that
is delivered to the build surface. The intensity of the beam can be
suitable for raising the temperature of the preheated feedstock to
its melting point.
[0110] FIG. 6 depicts a material-extrusion 3D printer 600B
including pinch rollers 670, feed tube 672, heating block 674,
extrusion nozzle 676, preheating subsystem 678 in accordance with
the present teachings. The pincher rollers 670, which are driven by
a motor (not depicted), may pull feedstock 236 from a spool (not
depicted) through feed tube 672. The feedstock may be heated to
melting into heating block 674. The heated feedstock may be forced
out of extrusion nozzle 676 at a reduced diameter. Preheat can be
applied anywhere along feed tube 672 to a temperature at or above
the glass transition temperature of the feedstock (but less than
the melting point). Preheating subsystem 678 may be a direct
contact heater (as in system 100A of FIG. 2) or a hot-air blower
(as in system 100B of FIG. 3). Other embodiments of preheating
subsystem 678 that is suitable for a material-extrusion-based 3D
printer may suitably be used.
[0111] FIG. 7 depicts a directed energy deposition 3D printer 700B
including preheating subsystem 794 in accordance with the present
teachings. A laser (not depicted) may generate beam 780. The feed
lines 782 may deliver powder feed 784. The shield gas lines 786 can
deliver shield gas 788 to build surface 790. Energy (e.g., laser
light, etc.) may be directed to a narrow, focused region on
substrate 792, melting the substrate and the powdered feed material
784 that is being deposited into the substrate's melt pool. (In
printer 700B, the shield-gas line on the right of FIG. 7B is
omitted for clarity.) Preheat can be applied anywhere along feed
lines 782 to preheat the feed to a temperature at or above the
glass transition temperature of the polymer feed (but less than the
melting point). Preheating subsystem 794 may be a direct contact
heater (as in system 100A of FIG. 2) or a hot-air blower (as in
system 100B of FIG. 3). Other embodiments of preheating subsystem
794 that are suitable for a material-extrusion-based 3D printer may
suitably be used.
Computer Control Systems
[0112] The present disclosure provides computer control systems
that are programmed to implement methods of the disclosure. FIG. 12
shows a computer system 1201 that is programmed or otherwise
configured to implement 3D printing methods and systems of the
present disclosure. The computer system 1201 can regulate various
aspects of methods the present disclosure, such as, for example,
preheating, at a first location in an additive manufacturing
apparatus, a feed comprising a polymer material to a temperature in
excess of a glass transition temperature and below a melting point
of the polymer material.
[0113] The computer system 1201 includes a central processing unit
(CPU, also "processor" and "computer processor" herein) 1205, which
can be a single core or multi core processor, or a plurality of
processors for parallel processing. The computer system 1201 also
includes memory or memory location 1210 (e.g., random-access
memory, read-only memory, flash memory), electronic storage unit
1215 (e.g., hard disk), communication interface 1220 (e.g., network
adapter) for communicating with one or more other systems, and
peripheral devices 1225, such as cache, other memory, data storage
and/or electronic display adapters. The memory 1210, storage unit
1215, interface 1220 and peripheral devices 1225 are in
communication with the CPU 1205 through a communication bus (solid
lines), such as a motherboard. The storage unit 1215 can be a data
storage unit (or data repository) for storing data. The computer
system 1201 can be operatively coupled to a computer network
("network") 1230 with the aid of the communication interface 1220.
The network 1230 can be the Internet, an internet and/or extranet,
or an intranet and/or extranet that is in communication with the
Internet. The network 1230 in some cases is a telecommunication
and/or data network. The network 1230 can include one or more
computer servers, which can enable distributed computing, such as
cloud computing. The network 1230, in some cases with the aid of
the computer system 1201, can implement a peer-to-peer network,
which may enable devices coupled to the computer system 1201 to
behave as a client or a server.
[0114] The CPU 1205 can execute a sequence of machine-readable
instructions, which can be embodied in a program or software. The
instructions may be stored in a memory location, such as the memory
1210. The instructions can be directed to the CPU 1205, which can
subsequently program or otherwise configure the CPU 1205 to
implement methods of the present disclosure. Examples of operations
performed by the CPU 1205 can include fetch, decode, execute, and
writeback.
[0115] The CPU 1205 can be part of a circuit, such as an integrated
circuit. One or more other components of the system 1201 can be
included in the circuit. In some cases, the circuit is an
application specific integrated circuit (ASIC).
[0116] The storage unit 1215 can store files, such as drivers,
libraries and saved programs. The storage unit 1215 can store user
data, e.g., user preferences and user programs. The computer system
1201 in some cases can include one or more additional data storage
units that are external to the computer system 1201, such as
located on a remote server that is in communication with the
computer system 1201 through an intranet or the Internet.
[0117] The computer system 1201 can communicate with one or more
remote computer systems through the network 1230. For instance, the
computer system 1201 can communicate with a remote computer system
of a user (e.g., customer or operator of a 3D printing system).
Examples of remote computer systems include personal computers
(e.g., portable PC), slate or tablet PC's (e.g., Apple.RTM. iPad,
Samsung.RTM. Galaxy Tab), telephones, Smart phones (e.g.,
Apple.RTM. iPhone, Android-enabled device, Blackberry.RTM.), or
personal digital assistants. The user can access the computer
system 1201 via the network 1230.
[0118] Methods as described herein can be implemented by way of
machine (e.g., computer processor) executable code stored on an
electronic storage location of the computer system 1201, such as,
for example, on the memory 1210 or electronic storage unit 1215.
The machine executable or machine readable code can be provided in
the form of software. During use, the code can be executed by the
processor 1205. In some cases, the code can be retrieved from the
storage unit 1215 and stored on the memory 1210 for ready access by
the processor 1205. In some situations, the electronic storage unit
1215 can be precluded, and machine-executable instructions are
stored on memory 1210.
[0119] The code can be pre-compiled and configured for use with a
machine having a processor adapted to execute the code, or can be
compiled during runtime. The code can be supplied in a programming
language that can be selected to enable the code to execute in a
pre-compiled or as-compiled fashion.
[0120] Aspects of the systems and methods provided herein, such as
the computer system 1801, can be embodied in programming. Various
aspects of the technology may be thought of as "products" or
"articles of manufacture," in some cases in the form of machine (or
processor) executable code and/or associated data that is carried
on or embodied in a type of machine readable medium.
Machine-executable code can be stored on an electronic storage
unit, such as memory (e.g., read-only memory, random-access memory,
flash memory) or a hard disk. "Storage" type media can include any
or all of the tangible memory of the computers, processors or the
like, or associated modules thereof, such as various semiconductor
memories, tape drives, disk drives and the like, which may provide
non-transitory storage at any time for the software programming.
All or portions of the software may at times be communicated
through the Internet or various other telecommunication networks.
Such communications, for example, may enable loading of the
software from one computer or processor into another, for example,
from a management server or host computer into the computer
platform of an application server. Thus, another type of media that
may bear the software elements includes optical, electrical and
electromagnetic waves, such as used across physical interfaces
between local devices, through wired and optical landline networks
and over various air-links. The physical elements that carry such
waves, such as wired or wireless links, optical links or the like,
also may be considered as media bearing the software. As used
herein, unless restricted to non-transitory, tangible "storage"
media, terms such as computer or machine "readable medium" refer to
any medium that participates in providing instructions to a
processor for execution.
[0121] Hence, a machine readable medium, such as
computer-executable code, may take many forms, including but not
limited to, a tangible storage medium, a carrier wave medium or
physical transmission medium. Non-volatile storage media include,
for example, optical or magnetic disks, such as any of the storage
devices in any computer(s) or the like, such as may be used to
implement the databases, etc. shown in the drawings. Volatile
storage media include dynamic memory, such as main memory of such a
computer platform. Tangible transmission media include coaxial
cables; copper wire and fiber optics, including the wires that
comprise a bus within a computer system. Carrier-wave transmission
media may take the form of electric or electromagnetic signals, or
acoustic or light waves such as those generated during radio
frequency (RF) and infrared (IR) data communications. Common forms
of computer-readable media therefore include for example: a floppy
disk, a flexible disk, hard disk, magnetic tape, any other magnetic
medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch
cards paper tape, any other physical storage medium with patterns
of holes, a RAM, a ROM, a PROM and EPROM, a FLASH-EPROM, any other
memory chip or cartridge, a carrier wave transporting data or
instructions, cables or links transporting such a carrier wave, or
any other medium from which a computer may read programming code
and/or data. Many of these forms of computer readable media may be
involved in carrying one or more sequences of one or more
instructions to a processor for execution.
[0122] The computer system 1201 can include or be in communication
with an electronic display 1235 that comprises a user interface
(UI) 1240 for providing, for example, a print head tool path to a
user. Examples of UI's include, without limitation, a graphical
user interface (GUI) and web-based user interface.
[0123] Methods and systems of the present disclosure can be
implemented by way of one or more algorithms. An algorithm can be
implemented by way of software upon execution by the central
processing unit 1205. The algorithm can, for example, partition a
computer model of a part and generate a mesh array from the
computer model.
[0124] The computer system 1201 can include a 3D printing system.
The 3D printing system may include one or more 3D printers. A 3D
printer may be, for example, a fused filament fabrication (FFF)
printer. Alternatively or in addition to, the computer system 1201
may be in remote communication with the 3D printing system, such as
through the network 1230.
[0125] While preferred embodiments of the present invention have
been shown and described herein, it will be obvious to those
skilled in the art that such embodiments are provided by way of
example only. It is not intended that the invention be limited by
the specific examples provided within the specification. While the
invention has been described with reference to the aforementioned
specification, the descriptions and illustrations of the
embodiments herein are not meant to be construed in a limiting
sense. Numerous variations, changes, and substitutions will now
occur to those skilled in the art without departing from the
invention. Furthermore, it shall be understood that all aspects of
the invention are not limited to the specific depictions,
configurations or relative proportions set forth herein which
depend upon a variety of conditions and variables. It should be
understood that various alternatives to the embodiments of the
invention described herein may be employed in practicing the
invention. It is therefore contemplated that the invention shall
also cover any such alternatives, modifications, variations or
equivalents. It is intended that the following claims define the
scope of the invention and that methods and structures within the
scope of these claims and their equivalents be covered thereby.
* * * * *