U.S. patent application number 15/953347 was filed with the patent office on 2018-12-27 for additive manufacturing with multiple polygon mirror scanners.
The applicant listed for this patent is Applied Materials, Inc.. Invention is credited to David Masayuki Ishikawa, Nag B. Patibandla, Paul J. Steffas.
Application Number | 20180369914 15/953347 |
Document ID | / |
Family ID | 64691785 |
Filed Date | 2018-12-27 |
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United States Patent
Application |
20180369914 |
Kind Code |
A1 |
Ishikawa; David Masayuki ;
et al. |
December 27, 2018 |
ADDITIVE MANUFACTURING WITH MULTIPLE POLYGON MIRROR SCANNERS
Abstract
An additive manufacturing system includes a platform, a
dispenser to dispense a plurality of layers of feed material on a
top surface of the platform, a light source to generate three light
beams, a first polygon mirror scanner, a galvo mirror scanner, and
a second polygon mirror scanner configured to direct the first,
second and third light beams, respectively, to impinge the layer of
the feed material on the platform, and a controller. The controller
is configured to cause the light source and first and second
polygon mirror scanners to apply the first light beam to a region
of the layer of feed material, and to cause the light source and
galvo mirror scanner to apply the second light beam to at least a
portion of the region of the layer of feed material.
Inventors: |
Ishikawa; David Masayuki;
(Mountain View, CA) ; Steffas; Paul J.; (Santa
Clara, CA) ; Patibandla; Nag B.; (Pleasanton,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Materials, Inc. |
Santa Clara |
CA |
US |
|
|
Family ID: |
64691785 |
Appl. No.: |
15/953347 |
Filed: |
April 13, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62524436 |
Jun 23, 2017 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23K 2103/42 20180801;
B22F 3/003 20130101; B23K 26/342 20151001; B23K 2103/26 20180801;
B23K 26/0821 20151001; B33Y 10/00 20141201; B23K 2103/08 20180801;
B23K 2103/10 20180801; G02B 26/105 20130101; B23K 2103/14 20180801;
B33Y 40/00 20141201; B23K 2103/52 20180801; B23K 26/0006 20130101;
G02B 26/123 20130101; B22F 2003/1057 20130101; B23K 2103/05
20180801; B22F 3/1055 20130101; B23K 26/0676 20130101; B23K 26/0604
20130101; B23K 26/0608 20130101; B23K 26/0673 20130101; B22F
2003/1056 20130101; B23K 26/0626 20130101; B33Y 30/00 20141201 |
International
Class: |
B22F 3/105 20060101
B22F003/105; B22F 3/00 20060101 B22F003/00; B33Y 10/00 20060101
B33Y010/00; B33Y 30/00 20060101 B33Y030/00; B33Y 40/00 20060101
B33Y040/00; G02B 26/10 20060101 G02B026/10; G02B 26/12 20060101
G02B026/12 |
Claims
1. An additive manufacturing system comprising: a platform; a
dispenser to dispense a plurality of layers of feed material on a
top surface of the platform; a light source to generate a first
light beam, a second light beam, and a third light beam; a first
polygon mirror scanner configured to direct the first light beam to
impinge a layer of the feed material on the platform; a galvo
mirror scanner configured to direct the second light beam to
impinge the layer of the feed material on the platform; a second
polygon mirror scanner configured to direct the third light beam to
impinge the layer of the feed material on the platform; and a
controller coupled to the light source, the first polygon mirror
scanner, the galvo mirror scanner, and the second polygon mirror
scanner, the controller configured to cause the light source and
first and second polygon mirror scanners to apply the first light
beam to a region of the layer of feed material, and to cause the
light source and galvo mirror scanner to apply the second light
beam to at least a portion of the region of the layer of feed
material.
2. The system of claim 1, wherein the first polygon mirror is
configured to direct the light beam to at least a first half of the
layer of the feed material on the platform, and the second polygon
mirror is configured to direct the light beam to at least a second
half of the layer of the feed material on the platform.
3. The system of claim 1, wherein the controller is configured to
cause the light source and first polygon mirror scanner to cause
the first light beam to pre-heat the feed material before the feed
material has been fused, and to cause the light source and second
polygon mirror scanner to cause the third light beam to apply heat
to the feed material after the feed material has been fused to
control a rate of cooling of the feed material.
4. The system of claim 1, further comprising a beam splitter
configured to split a first light beam emitted from the light
source into a second light beam and a third light beam, the second
light beam directed at the first polygon mirror scanner, the third
light beam directed at the galvo mirror scanner.
5. The system of claim 1, further comprising a three-way beam
splitter configured to split a first light beam emitted from the
light source into a second light beam, a third light beam, and a
fourth light beam, the second light beam directed at the first
polygon mirror scanner, the third light beam directed at the galvo
mirror scanner, and the fourth light beam directed at the second
polygon mirror scanner.
6. The system of claim 1, wherein the light source is a first light
source that directs a first light beam to the first polygon mirror
scanner, the additive manufacturing system further comprising: a
second light source directing a second light beam at the galvo
mirror scanner; and a third light source directing a third light
beam at the second polygon mirror scanner.
7. The system of claim 1, comprising an optical engine including
the first polygon mirror scanner, the galvo mirror scanner, and the
second polygon mirror scanner.
8. The system of claim 7, wherein the first polygon mirror scanner
is positioned adjacent to the galvo mirror scanner in the optical
engine.
9. The system of claim 7, wherein the galvo mirror scanner is
positioned between the first polygon mirror scanner and the second
polygon mirror scanner in the optical engine.
10. The system of claim 1, wherein the first polygon mirror
scanner, galvo mirror scanner, and second polygon mirror scanner
are secured to a common support that is laterally moveable relative
to the platform.
11. The system of claim 1, wherein the controller is configured to
the light source and galvo mirror scanner to cause the second light
beam to fuse an outline of a part in the layer without pre-heating
by the first light beam.
12. An optical engine comprising: a light source configured to emit
a light beam; a beam splitter configured to split a first light
beam emitted from the light source into a second light beam and a
third light beam; a polygon mirror scanner configured to direct the
second light beam to impinge a layer of a feed material on a
platform; and a galvo mirror scanner positioned adjacent to the
polygon mirror scanner, the galvo mirror scanner configured to
direct the third light beam to impinge a layer of the feed material
on the platform.
13. The optical engine of claim 12, wherein the beam splitter
further splits the first light beam into a fourth light beam.
14. The optical engine of claim 12, wherein the polygon mirror
scanner is a first polygon mirror scanner, the optical engine
further comprising a second polygon mirror scanner configured to
direct the fourth light beam to impinge a layer of the feed
material on the platform.
15. The optical engine of claim 12, wherein the first polygon
mirror scanner is capable of scanning at least a first half of the
platform, and the second polygon mirror scanner is capable of
scanning at least a second half of the platform.
16. An additive manufacturing method comprising: pre-heating a
first area of a layer of feed material on a platform below a caking
temperature of the feed material by scanning a first light beam
across the layer of feed material with a first polygon mirror;
fusing at least a portion of the first area of the layer of the
feed material by scanning a second light beam across the layer of
feed material with a galvo mirror scanner after the first area has
been pre-heated; and heat-treating the first area by reflecting the
first light beam off the first polygon mirror or by reflecting a
third light beam off a second polygon mirror onto a first area of
the layer of the feed material after the portion of the first area
has been fused.
17. The method of claim 16, comprising heat-treating the first area
by reflecting the first light beam off the first polygon
mirror.
18. The method of claim 16, comprising heat-treating the first area
by reflecting the third light beam off the second polygon
mirror.
19. The method of claim 16, wherein pre-heating the layer of the
feed material comprises scanning the first light beam on the layer
of feed material with a first scanning pattern, and fusing the feed
material comprises scanning the second light beam on the layer of
feed material with a second scanning pattern, wherein the first
scanning pattern differs from the second scanning pattern.
20. The method of claim 19, wherein heat treating the layer of the
feed material comprises scanning the first light beam or the third
light beam on the layer of feed material with a third scanning
pattern, wherein the third scanning pattern differs from the second
scanning pattern.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is claims priority to U.S. Provisional
Application Ser. No. 62/524,436, filed on Jun. 23, 2017, the entire
disclosure of which is incorporated by reference.
TECHNICAL FIELD
[0002] This specification relates to additive manufacturing, also
known as 3D printing.
BACKGROUND
[0003] Additive manufacturing (AM), also known as solid freeform
fabrication or 3D printing, refers to a manufacturing process where
three-dimensional objects are built up from successive dispensing
of raw material (e.g., powders, liquids, suspensions, or molten
solids) into two-dimensional layers. In contrast, traditional
machining techniques involve subtractive processes in which objects
are cut out from a stock material (e.g., a block of wood, plastic
or metal).
[0004] A variety of additive processes can be used in additive
manufacturing. Some methods melt or soften material to produce
layers, e.g., selective laser melting (SLM) or direct metal laser
sintering (DMLS), selective laser sintering (SLS), fused deposition
modeling (FDM), while others cure liquid materials using different
technologies, e.g., stereolithography (SLA). These processes can
differ in the way layers are formed to create the finished objects
and in the materials that are compatible for use in the
processes.
[0005] In some forms of additive manufacturing, a powder is placed
on a platform and a laser beam traces a pattern onto the powder to
fuse the powder together to form a shape. Once the shape is formed,
the platform is lowered and a new layer of powder is added. The
process is repeated until a part is fully formed.
SUMMARY
[0006] This specification describes technologies relating to
additive manufacturing.
[0007] In one aspect, an additive manufacturing system includes a
platform, a dispenser to dispense a plurality of layers of feed
material on a top surface of the platform, a light source to
generate a first light beam and a second light beam, a polygon
mirror scanner configured to direct the first light beam light to
impinge a layer of the feed material on the platform, a galvo
mirror scanner positioned adjacent to the polygon mirror scanner,
and a controller. The polygon mirror scanner is configured to
direct the second light beam emitted to impinge the layer of the
feed material on the platform. The controller is coupled to the
light source, the polygon mirror scanner and the galvo mirror
scanner, and the controller is configured to cause the light source
and polygon mirror scanner to apply the first light beam to a
region of the layer of feed material, and to cause the light source
and galvo mirror scanner to apply the second light beam to at least
a portion of the region of the layer of feed material.
[0008] Implementations may include one or more of the following
features.
[0009] The controller may be configured to cause the light source
and polygon mirror scanner to cause the first light beam to apply
sufficient heat to raise a temperature of the feed material from a
first temperature to a second temperature that is below a third
temperature (TF) at which the feed material fuses. The controller
may be configured to cause the light source and galvo mirror
scanner to cause the second light beam to apply sufficient heat to
the feed material while the temperature of the feed material has
been raised by the first light beam to further raise the
temperature of the feed material above the third temperature. The
controller may be configured to cause the light source and galvo
mirror scanner to cause the second light beam to apply sufficient
heat to the feed material to further raise a temperature of the
feed material above a temperature (TF) at which the feed material
fuses. The controller may be configured to cause the light source
and polygon mirror scanner to cause the first light beam to apply
heat to the feed material after the feed material has been fused to
control a rate of cooling of the feed material.
[0010] The light source is configured to apply sufficient heat to
melt a metal powder. temperature of the feed material has been
raised from a first temperature to a second temperature that is
below a temperature (TF) at which the feed material fuses. The
first light beam directed by the polygon mirror scanner may have a
lower power density than the second light beam directed by the
galvo mirror scanner.
[0011] A beam splitter may be configured to split a light beam
emitted from a light source into the first light beam and the
second light beam. The light source may include a first light
source to emit the first light beam and a second light source to
emit the second light beam. The polygon mirror scanner may be a
first polygon mirror scanner, and the additive manufacturing system
may include a second polygon mirror scanner. The first polygon
mirror may be configured to direct the light beam to at least a
first half of the layer of the feed material on the platform, and
the second polygon mirror may be to direct the light beam to at
least a second half of the layer of the feed material on the
platform. The controller may be configured to cause the light
source and second polygon mirror scanner to cause a third light
beam to apply heat to the feed material after the feed material has
been fused to control a rate of cooling of the feed material.
[0012] A three-way beam splitter may be configured to split a first
light beam emitted from the light source into a second light beam,
a third light beam, and a fourth light beam. The second light beam
may be directed at the first polygon mirror scanner, the third
light beam may be directed at the galvo mirror scanner, and the
fourth light beam may be directed at the second polygon mirror
scanner. The light source may be a first light source that directs
a first light beam to the first polygon mirror scanner, and the
system may include a second light source directing a second light
beam at the galvo mirror scanner, and a third light source
directing a third light beam at the second polygon mirror
scanner.
[0013] In another aspect, an additive manufacturing method includes
pre-heating a first area of a layer of feed material on a platform
below a caking temperature of the feed material by scanning a first
light beam across the layer of feed material with a polygon mirror
scanner, and fusing at least a portion of the first area of the
layer of the feed material by scanning a second light beam across
the layer of feed material with a galvo mirror scanner after the
first area has been pre-heated.
[0014] Implementations may include one or more of the following
features.
[0015] The first area may be heat-treated by reflecting a third
light beam off the polygon mirror onto a first area of the layer of
the feed material after the portion of the first area has been
fused. The polygon mirror scanner may be a first polygon mirror.
The first area may be heat-treated by reflecting a third light beam
off a second polygon mirror scanner onto the first area of the
layer of the feed material after the portion of the first area has
been fused.
[0016] Pre-heating the layer of the feed material below the caking
temperature may include scanning the first light beam with a first
scanning pattern across the first area of the layer of the feed
material. Fusing the first area of the layer of the feed material
comprises scanning the second light beam with a second scanning
pattern across the portion of the first area of the layer of the
feed material. The first scanning pattern may differ from the
second scanning pattern. An outline of a pattern for a part may be
fused in the first area by the second light beam only.
[0017] After pre-heating the first area of the layer of the feed
material, a second area of the layer of the feed material may be
pre-heated with the polygon mirror scanner reflecting the first
light beam onto the second area of the layer of the feed material,
the second area being different from the first area of the layer of
the feed material. After fusing the first area of the layer of the
feed material, the second area of the layer of the feed material
may be fused with a galvo mirror scanner reflecting the second
light beam onto the second area of the layer of the feed material
after the first area has been pre-heated, the second area being
different from the first area of the layer of the feed
material.
[0018] In another aspect, an optical engine includes a light source
configured to emit a light beam, a beam splitter configured to
split a first light beam emitted from the light source into a
second light beam and a third light beam, a polygon mirror scanner
configured to direct the second light beam to impinge a layer of a
feed material on a platform, and a galvo mirror scanner positioned
adjacent to the polygon mirror scanner, the galvo mirror scanner
configured to direct the third light beam to impinge a layer of the
feed material on the platform.
[0019] Implementations may include one or more of the following
features.
[0020] The beam splitter may further split the first light beam
into a fourth light beam. The polygon mirror scanner may be a first
polygon mirror scanner, and the optical engine may include a second
polygon mirror scanner configured to direct the fourth light beam
to impinge a layer of the feed material on the platform. The first
polygon mirror scanner may be capable of scanning at least a first
half of the platform, and the second polygon mirror scanner may be
capable of scanning at least a second half of the platform.
[0021] Particular implementations of the subject matter described
in this specification can be implemented so as to realize one or
more of the following advantages. Pre-heating and post-heating can
be controlled. The amount of power needed by the beam used for
fusing can be reduced, and/or the beam can move more quickly across
the layer and thus can increase throughput. In addition, the size
of temperature fluctuations can be reduced, and thus thermal stress
can be reduced and material properties of the object being
fabricated can be improved. Use of a rotating polygon to pre-heat
or heat-treat the powder can permit heating to be applied to a
small area at high speed/low power, and the powder can be treated
with repetitive scans to simulate heating by an array of lamps.
[0022] The details of one or more implementations of the subject
matter described in this specification are set forth in the
accompanying drawings and the description below. Other features,
aspects, and advantages of the subject matter will become apparent
from the description, the drawings, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a schematic diagram of a perspective
cross-sectional view of an example additive manufacturing
system.
[0024] FIG. 2A is a schematic diagram of a front view of an example
optical engine.
[0025] FIG. 2B is a schematic diagram of a side view of an example
optical engine.
[0026] FIGS. 3A-3D are schematic diagrams of example scan
paths.
[0027] FIG. 4A is a schematic diagram of a top view of an example
optical engine.
[0028] FIG. 4B is a schematic diagram of a top view of an example
optical engine.
[0029] FIGS. 5A-5B are schematic diagrams of an example active
optical assembly.
[0030] FIG. 6 is a flowchart of an example method of additive
manufacturing.
[0031] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0032] An additive manufacturing process can involve dispensing a
layer of feed material, for example, a powder, on a platen or a
previously deposited layer, followed by a method to fuse portions
of the layer of feed material. An energy source heats up the feed
material and causes it to solidify, e.g., to cause the powder to
fuse. However, temperature fluctuations caused by the
point-by-point sintering or melting of a powdered material can
create thermal stresses within the printed object. These thermal
stresses can cause parts to warp and crack during the manufacturing
process. The thermal stresses can also cause porous regions to
form.
[0033] In an additive manufacturing process, the feed material can
be heated prior to being deposited over the platen. This can reduce
the amount of power needed by the scanning beam to cause a
particular voxel to solidify. This permits the beam to move more
quickly across the layer, and thus can increase throughput. In
addition, this can reduce the size of the temperature fluctuations,
and thus reduce thermal stress and improve material properties.
[0034] Pre-heating a platform that supports the powder can reduce
the thermal fluctuations and increase throughput for shallow parts,
but fails to alleviate cracking and deformation for deeper parts
where the depth of the part is too great for a pre-heated platform
to sufficiently heat. Other pre-heating methods can result in
"caking" of the majority of the powder on the platform and renders
the powder unsuitable for reuse.
[0035] However, a feed powder can be pre-heated by a scanned light
beam prior to fusing in order to reduce the thermal gradient during
the manufacturing process, which can improve sintering quality and
throughput. The reduced thermal gradient can at least partially
reduce thermal stresses during the manufacturing process. Heat can
also be applied by a scanned light beam to the fused sections after
fusing (also referred to as "heat-treating" or "post-heating") in
order to control the rate of cool-down and thereby reduce residual
stresses and further improve sintering quality, e.g., by reducing
the likelihood of warping and cracking of the part. The heat can
also be used to compensate for thermal non-uniformity due to
radiative, convective, and conductive losses.
[0036] This disclosure describes a method and apparatus for
additive manufacturing. The apparatus can include an optical engine
with at least one galvo mirror scanner and at least one polygon
mirror scanner. An optical assembly that includes such an optical
engine is capable of directing one or more light beams to pre-heat,
fuse, and/or heat-treat a feed material during the manufacturing
process.
[0037] FIG. 1 shows an example additive manufacturing system 100.
The additive manufacturing system 100 includes a build platform 116
to hold the object being fabricated, a feed material delivery
system to deliver successive layers of feed material over the
support 102, and an optical assembly 111 to generate multiple light
beams that will be used for fusing, pre-heating and/or
heat-treatment of each layer of feed material.
[0038] In some implementations, such as the implementation
illustrated in FIG. 1, the feed material delivery system 107 can
include a flat blade or paddle to push a feed material from a feed
material reservoir 108 across the build platform 116. In such an
implementation, the feed material reservoir 108 can also include a
feed platform 118 positioned adjacent the build platform 116. The
feed platform 118 can be elevated to raise some feed material above
the level of the build platform 116, and the blade can push the
feed material 104 from the feed platform 118 onto the build
platform 116.
[0039] Alternatively or in addition, the feed material delivery
system 107 can include a dispenser suspended above the platform 116
and that has a plurality of apertures or nozzles through which the
powder flows. For example, the powder could flow under gravity, or
be ejected, e.g., by piezoelectric actuator. Control of dispensing
of individual apertures or nozzles could be provided by pneumatic
valves, microelectromechanical systems (MEMS) valves, solenoid
valves, and/or magnetic valves. Other systems that can be used to
dispense powder include a roller having apertures, and an augur
inside a tube having a plurality of apertures.
[0040] Optionally, the system 100 can include a compaction and/or
levelling mechanism to compact and/or smooth the layer of feed
materials deposited over the build platform 116. For example, the
system can include a roller or blade that is movable parallel to
the surface of the platform 116 by a drive system, e.g., a linear
actuator.
[0041] The feed material 105 can include metallic particles.
Examples of metallic particles include metals, alloys and
intermetallic alloys. Examples of materials for the metallic
particles include aluminum, titanium, stainless steel, nickel,
cobalt, chromium, vanadium, and various alloys or intermetallic
alloys of these metals.
[0042] The feed material 105 can include ceramic particles.
Examples of ceramic materials include metal oxide, such as ceria,
alumina, silica, aluminum nitride, silicon nitride, silicon
carbide, or a combination of these materials, such as an aluminum
alloy powder.
[0043] The feed material can be dry powders or powders in liquid
suspension, or a slurry suspension of a material. For example, for
a dispenser that uses a piezoelectric printhead, the feed material
would typically be particles in a liquid suspension. For example, a
dispenser could deliver the powder in a carrier fluid, e.g. a high
vapor pressure carrier, e.g., Isopropyl Alcohol (IPA), ethanol, or
N-Methyl-2-pyrrolidone (NMP), to form the layers of powder
material. The carrier fluid can evaporate prior to the sintering
step for the layer. Alternatively, a dry dispensing mechanism,
e.g., an array of nozzles assisted by ultrasonic agitation and
pressurized inert gas, can be employed to dispense the first
particles.
[0044] The additive manufacturing system 100 includes a controller
119 that can store digital data representing a pre-defined pattern
that can form the object 106. The controller 119 controls the
optical assembly 111 to generate multiple light beams that will be
used for fusing, pre-heating and/or heat-treatment of the layer of
feed material.
[0045] The optical assembly 111 includes a light source 101 to
generate a light beam 102 to impinge an outermost layer 104 of the
feed material 105. The light beam 102 selectively delivers
sufficient heat to fuse the feed material 105 in the pre-defined
pattern stored in the controller 119. Fusing in the context of this
specification can include melting and solidification, or sintering
while still in solid form, or other processes of fusing a powder.
While the illustrated implementation utilizes a single light source
emitting a single light beam, multiple light sources can be used to
generate multiple light beams. Examples of such implementations are
given in greater detail later within this disclosure.
[0046] The light beam 102 is caused by the optical engine 103 to
scan at least along a first axis (also referred to as a Y-axis).
The optical engine 103 is controlled by the controller 119 and is
described in greater detail later within this disclosure.
[0047] The Y-axis can be parallel to the direction of motion of the
dispenser 107 (e.g., from left to right in FIG. 1), e.g., the blade
or nozzles, across the platform. Alternatively, the Y-axis can be
perpendicular to the direction of motion of the dispenser 107.
[0048] Movement along the X-axis can be facilitated by motion of
platform 116, motion of a support holding the optical engine 103,
by tilting a portion of the optical engine about the Y-axis, or by
a separate galvo mirror scanner positioned before or after the
optical engine 103 and within the path of the light beam to deflect
the light beam along the X-axis. Different light beams can use
different mechanisms, e.g., the rotating polygon scanner can be
moved laterally by an actuator to provide motion along the X-axis,
whereas the galvo mirror scanner can have a second galvo mirror
scanner to provide movement of the light beam along the X-axis. In
some implementations, motion of the different light beams along the
X-axis can be independently controlled. In some implementations,
e.g., where the scanners are attached to the same support that is
laterally movable, the light beams have a fixed relative position
along the X-axis.
[0049] FIGS. 2A-2B show a front and side view, respectively of an
example optical engine 103. The optical engine 103 can include a
galvo mirror scanner 202 that includes a movable mirror 204 and
focusing lenses 206. The galvo mirror scanner 202 can direct a
light beam, such as light beam 102, to impinge a layer of the feed
material 105 on the platform 116. The focusing lenses 206 focus the
light beam 102 in order to gain optimal performance from the
impingement. The galvo mirror scanner 202 can be used for
pre-heating the feed powder 105, fusing the feed powder 105, or
heat-treating the feed powder 105 after it is fused, or any
combination. Heat-treating in the context of this disclosure
includes controlling a rate of cooling of the feed material after
it has been fused.
[0050] The optical engine 103 can also include a polygon mirror
scanner 208a. The polygon mirror scanner can direct a light beam
emitted by the light source 101, such as light beam 102, to impinge
the layer of the feed material 105 on the platform 116. The polygon
mirror scanner 208a can be positioned beside the galvo laser
scanner 202 to be a part of the optical engine 103. The polygon
mirror scanner 208a can be used for pre-heating the feed powder
105, heat-treating the feed powder 105 after the feed powder 105
has been fused, or both.
[0051] In some implementations, the optical engine 103 can include
a second polygon mirror scanner 208b. The second polygon mirror
scanner 208b can also be used for pre-heating the feed powder 105,
heat-treating the feed powder 105 after it is fused, or both. In
implementations where both the first polygon mirror scanner 208a
and the second polygon mirror scanner 208b are used, the first
polygon mirror scanner 208a can be used to pre-heat the feed powder
105 prior to fusing and the second polygon mirror 208b can be used
to heat-treat the feed powder 105 after fusing. For example, light
beams can be sent to both polygon mirror scanners 208a, 208b
simultaneously, so that different portions of the layer of feed
material are being pre-heated and heat-treated simultaneously.
[0052] In some implementation, both the first polygon mirror
scanner 208a and the second polygon laser scanner 208b can be used
for both pre-heating the feed powder 105 and heat-treating the feed
powder 105 after it has been fused. In such an implementation, the
first polygon laser scanner 208a can have a scanning range that
covers at least one half of the platform 116 while the second
polygon laser scanner 208b can have a scanning range that covers at
least one half of the platform 116 that is separate from the half
covered by the first polygon mirror scanner 208a.
[0053] For each light beam, as the light beam sweeps along a path
on the layer, the light beam can be modulated, e.g., by causing the
respective light source to turn the light beam on and off, in order
to deliver energy to selected regions of the layers of feed
material 110. A set of example scan regions is shown in FIGS.
3A-3D. In FIG. 3A, a first light path can be traced with the galvo
laser scanner 202. The light beam following this path can raise the
temperature of a feed material above TF. In FIG. 3B, the first
polygon mirror scanner 208a or the second polygon mirror scanner
208b can direct a light beam to scan the interior of the pattern
outlined in FIG. 3A in order to pre-heat the feed material below
TF. As shown in FIG. 3C, after area is pre-heated, the area can be
fused by a light beam directed by the galvo mirror scanner
following a different scan pattern. As shown in FIG. 3D, after the
material is fused, the area can again be scanned with by a light
beam with a different scan pattern directed by either the first
polygon mirror scanner 208a or the second polygon mirror scanner
208b. While the illustrated implementation shows scans along the
same area, different areas can be scanned simultaneously by the
different optical components. This permits each light beam to
pre-heat, fuse, and/or heat-treat independently selectable regions
of the layer of feed material.
[0054] FIG. 4A shows an example of a light source 101 configuration
that can be implemented with aspects of this disclosure. In the
illustrated implementation, the light source 101 emits a first
light beam 302 towards a beam splitter 304. The beam splitter 304
can split the first light beam 302 emitted from the light source
101 into a second light beam 302a, a third light beam 302b, and a
fourth light beam 302c. The second light beam 302a is directed
towards the first polygon mirror scanner 208a, the third light beam
302b is directed towards the galvo mirror scanner 202, and the
fourth light beam 302c is directed towards the second polygon
mirror scanner 208b. While the illustrated implementation shows the
beam splitter 304 directing a light beam to three different optical
components, the beam splitter 304 can be configured to direct any
number of light beams. For example, if the optical engine 103
included only the first polygon laser scanner 208a and the galvo
laser scanner 202, then the beam splitter 304 may only produce the
second light beam 302a and the third light beam 302b. In some
implementations, power density of the first light beam 302 can be
modulated by the light source 101. In some implementations, the
beam splitter can include a power density modulation mechanism for
one or more of the light beams. In some implementations, one or
more separate, stand-alone power density modulation mechanisms can
be used.
[0055] FIG. 4B shows an example optical engine that configuration
that can be implemented with aspects of this disclosure. The
illustrated implementation includes a first light source 304a, a
second light source 304b, and a third light source 304c. The first
light source 304a emits the first light beam 302a towards the first
polygon laser scanner 208a. The second light source 304b emits the
second light beam 302b towards the galvo mirror scanner 204. The
third light source 304c emits the third light beam 302c towards the
second polygon mirror scanner 208b.
[0056] While the illustrated implementation shows three separate
light sources directing a light beam to three different optical
components, any number of light sources can be used. For example,
if the optical engine 103 included only the first polygon laser
scanner 208a and the galvo laser scanner 202, then the first light
source 304a and the second light source may be the only included
light sources. Each of the light sources can individually modulate
the power density of the light beams. In some implementations, one
or more separate, stand-alone power density modulation mechanisms
can be used.
[0057] While the beam splitter 304 and the use of multiple light
sources 304a, 304b, and 304c have been described in separate
implementations, the two concepts can be used in combination. For
example, a first light beam can be emitted from a first light
source towards a beam splitter. The beam splitter can split the
first light beam into a second and third light beam. The second
light beam can be directed to the first polygon mirror scanner 208a
while the third light beam can be directed towards the second
polygon mirror scanner 208b. A second light source can emit a
fourth light beam towards the galvo mirror scanner 202.
[0058] In some aspects of operation, the controller 119 can cause
the light source 101 and polygon mirror scanner 208a to apply a
first light beam to a region of the layer of feed material 105 as
shown in FIG. 5A. The controller 119 can also cause the light
source 101 and galvo mirror scanner 202 to apply a second light
beam to at least a portion of the region of the layer of feed
material 105 as shown in FIG. 5B.
[0059] In some implementations, the controller 119 can control the
light source 101 and the polygon mirror scanner 208a to cause the
first light beam 302a to apply sufficient heat to raise a
temperature of the feed material 105 from a first temperature to a
second temperature that is below a fusing temperature (a third
temperature, TF, at which the feed material fuses. The second
temperature can be below or above a temperature at which the feed
material cakes. The controller can control the light source 101 and
the galvo mirror scanner 202 to cause the second light beam 302b to
apply sufficient heat to the feed material 105 while the
temperature of the feed material has been raised by the first light
beam 302a to further raise the temperature of the feed material
above the fusing temperature TF.
[0060] In some implementations, the controller 119 can control the
light source 101 and galvo mirror scanner 202 to cause the second
light beam 302b to apply sufficient heat to the feed material 105
to further raise a temperature of the feed material above the
fusing temperature TF, without the temperature being raised by a
previous scanned light beam.
[0061] Independent of whether the polygon mirror scanner 208a is
used to pre-heat the feed material 105, the optical assembly 111
can be used to cause the first light beam 302a to heat-treat the
feed material. For example, the controller 119 can control the
light source 101 and polygon mirror scanner 208a to cause the first
light beam 302a to apply heat to the feed material 105 after the
feed material 105 has been fused to control a rate of cooling of
the feed material 105. As another example, the controller 119 can
control the light source 101 and second polygon mirror scanner 208b
to cause a third light beam 302c to apply heat to the feed material
105 after the feed material 105 has been fused to control a rate of
cooling of the feed material 105.
[0062] In some implementations, the light source is capable of
applying sufficient heat to melt a metal powder to raise a
temperature of the feed material 105 from a first temperature to a
second temperature that is below the fusing temperature TF. In some
implementations, the first light beam 302a directed by the polygon
mirror scanner 208a has a lower power density than the second light
beam 302b directed by the galvo mirror scanner 202. In some
implementations, the third light beam 302c directed by the polygon
mirror scanner 208b has a lower power density than the second light
beam 302b directed by the galvo mirror scanner 202.
[0063] FIG. 6 is a flowchart of an example method 400 that can be
used in conjunction with aspects of this disclosure. At 402, a
first area of a layer of feed material is pre-heated on a platform
below a caking temperature of the feed material by scanning a first
light beam across the layer of feed material with a polygon mirror
scanner, such as polygon mirror scanner 208a. Pre-heating the layer
of the feed material below the caking temperature can include
scanning the first light beam with a first scanning pattern across
the first area of the layer of the feed material.
[0064] At 404, at least a portion of the first area of the layer of
the feed material is fused by scanning a second light beam across
the layer of feed material with the galvo mirror scanner 202 after
the first area has been pre-heated. Fusing the first area of the
layer of the feed material can include scanning the second light
beam with a second scanning pattern across the portion of the first
area of the layer of the feed material. The first scanning pattern
can differ from the second scanning pattern. A timespan between
scanning the first area of the layer of the feed material with the
first light and scanning the first area with the second light is
sufficiently short that the area retains the heat necessary for the
subsequent light beam to fuse the material. For some
implementations, this timespan can be in the millisecond range,
e.g., 1-10 milliseconds.
[0065] At 406, the first area is heat-treated by reflecting a third
light beam off the polygon mirror scanner, such as the polygon
mirror scanner 208a, onto the first area of the layer of the feed
material after the portion of the first area has been fused.
Alternatively, at 408, the first area is heat-treated by reflecting
a third light beam off a second polygon mirror scanner, such as
polygon mirror scanner 208b, onto the first area of the layer of
the feed material after the portion of the first area has been
fused. In some implementations, an outline of a pattern for a part
in the first area can be fused by the second light beam alone.
Thus, in some implementations, the first area is heat-treated by
reflecting a light beam off a polygon mirror scanner, but the area
is not pre-heated (so step 402 does not occur).
[0066] In some implementations, the additive manufacturing system
100 includes another heat source, e.g., one or more IR lamps
arranged to direct heat onto the uppermost layer of the feed
material. After pre-heating the first area of the layer of the feed
material using the other heat source, a second area of the layer of
the feed material can be pre-heated with the polygon mirror
scanner, such as the polygon mirror scanner 208a, reflecting the
first light beam onto the second area of the layer of the feed
material. The second area can be different from the first area of
the layer of the feed material. After fusing the first area of the
layer of the feed material, the second area of the layer of the
feed material can be fused with a galvo mirror scanner, such as the
galvo mirror scanner 202, reflecting the second light beam onto the
second area of the layer of the feed material after the first area
has been pre-heated. The second area can be different from the
first area of the layer of the feed material.
[0067] Controllers and computing devices can implement these
operations and other processes and operations described herein. As
described above, the controller 119 can include one or more
processing devices connected to the various components of the
system 100. The controller 119 can coordinate the operation and
cause the apparatus 100 to carry out the various functional
operations or sequence of steps described above.
[0068] The controller 119 and other computing devices part of
systems described herein can be implemented in digital electronic
circuitry, or in computer software, firmware, or hardware. For
example, the controller can include a processor to execute a
computer program as stored in a computer program product, e.g., in
a non-transitory machine readable storage medium. Such a computer
program (also known as a program, software, software application,
or code) can be written in any form of programming language,
including compiled or interpreted languages, and it can be deployed
in any form, including as a standalone program or as a module,
component, subroutine, or other unit suitable for use in a
computing environment.
[0069] The controller 119 and other computing devices part of
systems described can include non-transitory computer readable
medium to store a data object, e.g., a computer aided design
(CAD)-compatible file that identifies the pattern in which the feed
material should be deposited for each layer. For example, the data
object could be a STL-formatted file, a 3D Manufacturing Format
(3MF) file, or an Additive Manufacturing File Format (AMF) file.
For example, the controller could receive the data object from a
remote computer. A processor in the controller 119, e.g., as
controlled by firmware or software, can interpret the data object
received from the computer to generate the set of signals necessary
to control the components of the system 100 to fuse the specified
pattern for each layer.
[0070] The processing conditions for additive manufacturing of
metals and ceramics are significantly different than those for
plastics. For example, in general, metals and ceramics require
significantly higher processing temperatures. Thus 3D printing
techniques for plastic may not be applicable to metal or ceramic
processing and equipment may not be equivalent. However, some
techniques described here could be applicable to polymer powders,
e.g. nylon, ABS, polyetheretherketone (PEEK), polyetherketoneketone
(PEKK) and polystyrene.
[0071] While this specification contains many specific
implementation details, these should not be construed as
limitations on the scope of any inventions or of what may be
claimed, but rather as descriptions of features specific to
particular implementations of particular inventions. Certain
features that are described in this specification in the context of
separate implementations can also be implemented in combination in
a single implementation. Conversely, various features that are
described in the context of a single implementation can also be
implemented in multiple implementations separately or in any
suitable subcombination. Moreover, although features may be
described above as acting in certain combinations and even
initially claimed as such, one or more features from a claimed
combination can in some cases be excised from the combination, and
the claimed combination may be directed to a subcombination or
variation of a subcombination.
[0072] Similarly, while operations are depicted in the drawings in
a particular order, this should not be understood as requiring that
such operations be performed in the particular order shown or in
sequential order, or that all illustrated operations be performed,
to achieve desirable results. Moreover, the separation of various
system components in the implementations described above should not
be understood as requiring such separation in all implementations,
and it should be understood that the described program components
and systems can generally be integrated together in a single
software product or packaged into multiple software products.
[0073] Thus, particular implementations of the subject matter have
been described. Other implementations are within the scope of the
following claims. [0074] Optionally, some parts of the additive
manufacturing system 100, e.g., the build platform 116 and feed
material delivery system 107, can be enclosed by a housing. The
housing can, for example, allow a vacuum environment to be
maintained in a chamber inside the housing, e.g., pressures at
about 1 Torr or below. Alternatively the interior of the chamber
can be a substantially pure gas, e.g., a gas that has been filtered
to remove particulates, or the chamber can be vented to atmosphere.
Pure gas can constitute inert gases such as argon, nitrogen, xenon,
and mixed inert gases.
[0075] In some cases, the actions recited in the claims can be
performed in a different order and still achieve desirable results.
In addition, the processes depicted in the accompanying figures do
not necessarily require the particular order shown, or sequential
order, to achieve desirable results.
* * * * *