U.S. patent application number 17/072244 was filed with the patent office on 2021-02-11 for triangle hatch pattern for additive manufacturing.
The applicant listed for this patent is General Electric Company. Invention is credited to Justin Mamrak, MacKenzie Redding.
Application Number | 20210039166 17/072244 |
Document ID | / |
Family ID | 1000005168644 |
Filed Date | 2021-02-11 |
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United States Patent
Application |
20210039166 |
Kind Code |
A1 |
Mamrak; Justin ; et
al. |
February 11, 2021 |
TRIANGLE HATCH PATTERN FOR ADDITIVE MANUFACTURING
Abstract
A scanning technique for the additive manufacturing of an
object. The method comprises the irradiation of a portion of a
given layer of powder to form a fused region using an energy
source. When forming an object layer by layer, the irradiation
follows a first irradiation path bounded by a first stripe, wherein
the first irradiation path is formed at an oblique angle with
respect to the first stripe. The first irradiation path further
comprises at least a first scan vector and a second scan vector at
least partially melting a powder and forming a first solidification
line and second solidification line respectively, wherein the first
solidification intersects and forms an oblique angle with respect
to the second solidification line. After a layer is completed, a
subsequent layer of powder is provided over the completed layer,
and the subsequent layer of powder is irradiated. Irradiation of
the subsequent layer of powder follows a second irradiation path
bounded by a second stripe. wherein the second irradiation path is
formed at an oblique angle with respect to the second stripe. The
first irradiation path further comprises at least a third scan
vector and a fourth scan vector at least partially melting a powder
and forming a third solidification line and fourth solidification
line respectively, wherein the third solidification intersects and
forms an oblique angle with respect to the fourth solidification
line
Inventors: |
Mamrak; Justin; (Loveland,
OH) ; Redding; MacKenzie; (Mason, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
1000005168644 |
Appl. No.: |
17/072244 |
Filed: |
October 16, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15451108 |
Mar 6, 2017 |
10828700 |
|
|
17072244 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B33Y 50/02 20141201;
B33Y 10/00 20141201; B22F 10/00 20210101; B33Y 30/00 20141201; Y02P
10/25 20151101; B22F 10/10 20210101 |
International
Class: |
B22F 3/105 20060101
B22F003/105; B33Y 10/00 20060101 B33Y010/00; B33Y 30/00 20060101
B33Y030/00; B33Y 50/02 20060101 B33Y050/02 |
Claims
1. A system comprising an additive manufacturing device for
irradiating a powder, a monitoring device, a computer, and software
integrated together to adjust irradiation settings in the additive
manufacturing device, wherein the system: irradiates a portion of a
layer of powder to form a fused region, wherein the irradiation
follows a first irradiation path within a stripe region bounded by
a first stripe boundary and a second stripe boundary, the first
irradiation path further comprises: forming a first solidification
and an intersecting second solidification line at first oblique
angle with respect to the first solidification line, wherein the
first solidification line is formed at an angle other than
90.degree. with respect to the first stripe.
2. The system of claim 1, wherein a subsequent layer of powder is
provided over the fused region, and the subsequent layer of powder
is irradiated, wherein irradiation of the subsequent layer of
powder follows a second irradiation path within a second stripe
region bounded by at least a first stripe boundary wherein the
second irradiation path further comprises: forming a third
solidification line and an intersecting fourth solidification line
at a second oblique angle with respect to the third solidification
line, wherein the third solidification line is formed at an angle
other than 90.degree. with respect to the second stripe
boundary.
3. The system of claim 1, wherein the system irradiates the powder
using a laser.
4. The system of claim 1, wherein the system irradiates the powder
using an electron-beam.
5. The system of claim 1, wherein an energy source is turned off
over the skywriting path.
6. The system of claim 1, wherein an energy source is defocused
over the skywriting path.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority to U.S. application
Ser. No. 15/451,108 entitled "Triangle Hatch Pattern for Additive
Manufacturing", filed Mar. 6, 2017, the entire disclosure of which
is hereby expressly incorporated by reference herein.
INTRODUCTION
[0002] The disclosure relates to an improved method of producing
components using an additive manufacturing technique. The
disclosure provides an improved method of producing components,
some of examples of which comprise: improved microstructure,
decreased manufacturing time, decreased cost, decreased waste of
materials. In particular, the disclosure relates to a process of
scanning an energy beam (i.e., laser or e-beam) during a
powder-based additive manufacturing build process.
BACKGROUND
[0003] Additive manufacturing (AM) techniques may include electron
beam freeform fabrication, laser metal deposition (LMD), laser wire
metal deposition (LIVID-w), gas metal arc-welding, laser engineered
net shaping (LENS), laser sintering (SLS), direct metal laser
sintering (DMLS), electron beam melting (EBM), powder-fed
directed-energy deposition (DED), and three dimensional printing
(3DP), as examples. AM processes generally involve the buildup of
one or more materials to make a net or near net shape (NNS) object
in contrast to subtractive manufacturing methods. Though "additive
manufacturing" is an industry standard term (ASTM F2792), AM
encompasses various manufacturing and prototyping techniques known
under a variety of names, including freeform fabrication, 3D
printing, rapid prototyping/tooling, etc. AM techniques are capable
of fabricating complex components from a wide variety of materials.
Generally, a freestanding object can be fabricated from a computer
aided design (CAD) model. As an example, a particular type of AM
process uses an energy beam, for example, an electron beam or
electromagnetic radiation such as a laser beam, to sinter or melt a
powder material and/or wire-stock, creating a solid
three-dimensional object in which a material is bonded
together.
[0004] Selective laser sintering, direct laser sintering, selective
laser melting, and direct laser melting are common industry terms
used to refer to producing three-dimensional (3D) objects by using
a laser beam to sinter or melt a fine powder. For example, U.S.
Pat. Nos. 4,863,538 and 5,460,758 describe conventional laser
sintering techniques. More specifically, sintering entails fusing
(agglomerating) particles of a powder at a temperature below the
melting point of the powder material, whereas melting entails fully
melting particles of a powder to form a solid homogeneous mass. The
physical processes associated with laser sintering or laser melting
include heat transfer to a powder material and then either
sintering or melting the powder material. Electron beam melting
(EBM) utilizes a focused electron beam to melt powder. These
processes involve melting layers of powder successively to build an
object in a metal powder.
[0005] AM techniques, examples of which are discussed above and
throughout the disclosure, may be characterized by using a laser or
an energy source to generate heat in the powder to at least
partially melt the material. Accordingly, high concentrations of
heat are generated in the fine powder over a short period of time.
The high temperature gradients within the powder during buildup of
the component may have a significant impact on the microstructure
of the completed component. Rapid heating and solidification may
cause high thermal stress and cause localized non-equilibrium
phases throughout the solidified material. Further, since the
orientation of the grains in a completed AM component may be
controlled by the direction of heat conduction in the material, the
scanning strategy of the laser in an AM apparatus and technique
becomes an important method of controlling microstructure of the AM
built component. Controlling the scanning strategy in an AM
apparatus is further crucial for developing a component free of
material defects, examples of defects may include lack of fusion
porosity and/or boiling porosity.
[0006] FIG. 1 is schematic diagram showing a cross-sectional view
of an exemplary conventional system 110 for direct metal laser
sintering (DMLS) or direct metal laser melting (DMLM). The
apparatus 110 builds objects, for example, the part 122, in a
layer-by-layer manner (e.g. layers L1, L2, and L3, which are
exaggerated in scale for illustration purposes) by sintering or
melting a powder material (not shown) using an energy beam 136
generated by a source such as a laser 120. The powder to be melted
by the energy beam is supplied by reservoir 126 and spread evenly
over a build plate 114 using a recoater arm 116 travelling in
direction 134 to maintain the powder at a level 118 and remove
excess powder material extending above the powder level 118 to
waste container 128. The energy beam 136 sinters or melts a cross
sectional layer (e.g. layer L1) of the object being built under
control of the galvo scanner 132. The build plate 114 is lowered
and another layer (e.g. layer L2) of powder is spread over the
build plate and object being built, followed by successive
melting/sintering of the powder by the laser 120. The process is
repeated until the part 122 is completely built up from the
melted/sintered powder material. The laser 120 may be controlled by
a computer system including a processor and a memory. The computer
system may determine a scan pattern for each layer and control
laser 120 to irradiate the powder material according to the scan
pattern. After fabrication of the part 122 is complete, various
post-processing procedures may be applied to the part 122. Post
processing procedures include removal of excess powder, for
example, by blowing or vacuuming, machining, sanding or media
blasting. Further, conventional post processing may involve removal
of the part 122 from the build platform/substrate through
machining, for example. Other post processing procedures include a
stress release process. Additionally, thermal and chemical post
processing procedures can be used to finish the part 122.
[0007] The abovementioned AM processes is controlled by a computer
executing a control program. For example, the apparatus 110
includes a processor (e.g., a microprocessor) executing firmware,
an operating system, or other software that provides an interface
between the apparatus 110 and an operator. The computer receives,
as input, a three dimensional model of the object to be formed. For
example, the three dimensional model is generated using a computer
aided design (CAD) program. The computer analyzes the model and
proposes a tool path for each object within the model. The operator
may define or adjust various parameters of the scan pattern such as
power, speed, and spacing, but generally does not program the tool
path directly. One having ordinary skill in the art would fully
appreciate the abovementioned control program may be applicable to
any of the abovementioned AM processes. Further, the abovementioned
computer control may be applicable to any subtractive manufacturing
or any pre or post processing techniques employed in any post
processing or hybrid process.
[0008] The above additive manufacturing techniques may be used to
form a component from stainless steel, aluminum, titanium, Inconel
625, Inconel 718, Inconel 188, cobalt chrome, among other metal
materials or any alloy. For example, the above alloys may include
materials with trade names, Haynes 188.RTM., Haynes 625.RTM., Super
Alloy Inconel 625.TM., Chronin.RTM. 625, Altemp.RTM. 625,
Nickelvac.RTM. 625, Nicrofer.RTM. 6020, Inconel 188, and any other
material having material properties attractive for the formation of
components using the abovementioned techniques.
[0009] In the abovementioned example, a laser and/or energy source
is generally controlled to form a series of solidification lines
(hereinafter interchangeably referred to as hatch lines,
solidification lines and raster lines) in a layer of powder based
on a pattern. A pattern may be selected to decrease build time, to
improve or control the material properties of the solidified
material, to reduce stresses in the completed material, and/or to
reduce wear on the laser, and/or galvanometer scanner and/or
electron-beam. Various scanning strategies have been contemplated
in the past, and include, for example, chessboard patters and/or
stripe patterns.
[0010] One attempt at controlling the stresses within the material
of the built AM component involves the rotation of stripe regions
containing a plurality of adjoining parallel vectors, as
solidification lines, that run perpendicular to solidification
lines forming the boundaries of the stripe region. for each layer
during an AM build process. Parallel solidification lines, bounded
by and perpendicular to a stripe, are rotated for each layer of the
AM build. One example of controlling the scanning strategy in an AM
apparatus is disclosed in U.S. Pat. No. 8,034,279 B2.
[0011] FIGS. 2 and 3 represent the abovementioned rotating stripe
strategy. The laser is scanned across the surface of a powder to
form a series of solidification lines 213A, 213B. The series of
solidification lines form a layer of the build and are bound by
solidification lines in the form of stripes 211A, 212A and 211B,
212B that are perpendicular to the solidification lines 213A and
213B forming the boundaries of each stripe region. The stripe
regions bounded by solidification lines 211A and 212A form a
portion of a larger surface of the layer to be built. In forming a
part, a bulk of the part cross section is divided into numerous
stripe regions (regions between two solidified stripes containing
transverse solidification lines). A stripe orientation is rotated
for each layer formed during the AM build process as shown in FIGS.
2 and 3. A first layer may be formed with a series of parallel
solidification lines 213A, in a stripe region, formed substantially
perpendicular to and bounded by solidified stripes 211A. In a
subsequent layer formed over the first layer, the stripes 211B are
rotated as shown in FIG. 3. By creating a stripe boundary for the
solidified lines 213A and 213B through a set of solidified stripes
211B and 212B that are rotated with respect to the previous layer,
solidification lines 213B, which are be formed perpendicular to and
are bounded by stripes 211B are also be rotated with respect the
solidification lines 213A of the previous layer.
[0012] As shown in FIGS. 4 and 5, a built AM component includes a
plurality of layers 215, 216, 217. When built using the
abovementioned strategy, a first layer 217 may be divided by
software into several stripe regions bounded by, stripes 257 and
277 formed as solidification lines. The stripes 257 and 277 may
form a boundary for individually formed parallel adjoining vectors
or solidification lines 267. The surface of the part includes a
plurality of stripes covering the surface to be built. As shown in
FIG. 5, each stripe region is bounded by solidified stripes 257 and
277 in layer 217 form a boundary for a series of parallel
solidified lines 267. The parallel solidification lines 267 are
perpendicular to the solidified stripe boundaries 257 and 277. The
stripes are oriented at a first angle in layer 217 with the
perpendicular solidification lines 267 being formed substantially
perpendicular to the stripes 257 and 277. The stripe region bound
by solidified stripes 256 and 257 on a second layer 216 are angled
with respect to the solidified stripe boundaries 257 and 277 on
previous layer 217. Accordingly, solidification lines 266 that run
perpendicular to solidified stripes 256 and 276 are also be angled
with respect to the solidification lines 267 on previous layer 217.
As the build progresses, a next layer having stripes 265 and 275 on
a third layer 215 are angled with respect to stripes 257 and 277 on
layer 217; and stripes 256 and 276 on layer 216.
[0013] Even with the abovementioned rotating stripe strategy, the
need exists to further create variance in each layer. By employing
the various embodiments disclosed, build efficiency can be further
increased by preventing unnecessary jumps of the energy source,
preventing unnecessary on/off transitions of the laser and/or
improving control and/or efficiency of heat buildup within the
layer. Further the microstructure of the part can be altered by
controlling the pattern of stripe regions and solidification lines
within the stripe region.
SUMMARY OF THE INVENTION
[0014] One challenge associated with laser based AM is producing a
desired melt pattern in the powder while maintaining a desired
speed of the build process. Slowing of the build process and/or
inaccuracies in the melt pattern result, for example, when a laser
is turned on and/or off too early or late at the beginning and/or
end of a hatch line. Turning a laser on too early may result in a
burn-in effect where the melt pool is longer than the desired
length of the hatch. Further, the buildup of heat within the powder
and fused material during a build is a concern, as various material
defects may occur if too much heat is built up in the material
during an AM process and/or if insufficient heat is built up to
properly fuse the powder.
[0015] The disclosure relates to an improved scanning strategy,
having a hatch pattern for scanning a laser during an AM build
process. When controlling the laser during the build process
according to one embodiment, an alternating hatch pattern is used
to form solidification lines on each layer so as to improve the
microstructure of the completed component. In one aspect, a first
layer is formed by scanning a laser across the surface of the
powder to form at least partially melted solidification lines,
wherein each line is scanned and formed as a solidification line
forming two angled segments of a triangle. In other words, a
solidification line is formed along a first liner path and a second
linear path and the first and second linear paths are angled with
respect to one another. The first and second linear paths of the
laser scan and subsequently formed solidification lines may be
contained within a stripe region forming a portion of the component
being built. Once the series of solidification lines are formed on
the layer, a subsequent layer of powder is added on top of the
previously solidified scan lines; and a second series of
solidification lines are formed as a first linear path and a second
linear path, wherein the first linear path is angled with relation
to the second liner path. Further, the abovementioned angle formed
between the first linear path and second linear path may be varied
for each subsequent layer; so that no subsequent layer has the same
angle between the first linear path and the second linear path,
thereby improving build efficiency and/or the balance of stresses
imparted in the finished solidified component formed using the AM
process.
[0016] By dividing up areas of the surface to be scanned as
described below, further variance between layers can be achieved
during an AM build allowing for increased control of the
microstructure of the completed component. Build efficiency can
also be further increased by preventing unnecessary jumps of the
energy source, preventing unnecessary on/off transitions of the
laser and/or by improving control and/or efficiency of heat buildup
within the layer being formed and/or the layers of the build. In
the case of multiple lasers and/or energy sources being used, the
disclosed scanning scheme may be used to further improve the AM
build by employing various strategies for the use of multiple
energy sources (e.g. lasers and/or electron-beams).
[0017] When forming a series of the abovementioned first
solidification line and second solidification lines. The
possibility of a high energy density region may occur near the end
of a stripe or near the end of contour of the component, in order
to balance the heat distribution throughout the layer, a third
series of solidification lines may be formed that are substantially
parallel to a first series of solidification lines and intersect
one of the second solidification lines. By forming the third series
of solidification lines, the distance over which the energy source
is scanned is increased, thus preventing a high concentration of
heat within a certain region of the component being built. By
dividing up areas of the surface to be scanned as described below,
further variance between layers can be achieved during an AM build
allowing for increased control of the microstructure of the
completed component. Build efficiency can also be further increased
by preventing unnecessary jumps of the energy source, preventing
unnecessary on/off transitions of the laser and/or by improving
control and/or efficiency of heat buildup within the layers of the
build. In the case of multiple lasers and/or energy sources being
used, the disclosed scanning scheme may be used to further improve
the AM build by employing various strategies for the use of
multiple energy sources (e.g. lasers and/or electron-beams).
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings, which are incorporated into and
constitute a part of this specification, illustrate one or more
example aspects of the present disclosure and, together with the
detailed description, serve to explain their principles and
implementations.
[0019] FIG. 1 is a side view and top view diagram of a conventional
additive manufacturing technique used to form at least part of a
component;
[0020] FIG. 2 is a top view depicting a conventional hatch and
stripe pattern used to form at least a part of a component;
[0021] FIG. 3 is a top view depicting a conventional hatch and
stripe pattern used to form at least a part of a component;
[0022] FIG. 4 is a perspective view, depicting example layers of
component build during a conventional AM process;
[0023] FIG. 5 is a top view of the individual layers shown in FIG.
4, depicting a conventional hatch and stripe pattern used to form
at least a part of a component;
[0024] FIG. 6 is a top view depicting a hatch and stripe pattern
used to form at least a part of a component in accordance with one
aspect of the disclosure;
[0025] FIG. 7 is a top view depicting a hatch and stripe pattern
used to form at last a portion of a component in accordance with
one aspect of the disclosure;
[0026] FIG. 8 is a perspective view, depicting example layers of
component build during an AM process in accordance with one aspect
of the disclosure;
[0027] FIG. 9 is a top view of the individual layers shown in FIG.
8, depicting a hatch and stripe pattern used to form at least a
part of a component in accordance with one aspect of the
disclosure;
[0028] FIG. 10 is a top view depicting a hatch and stripe pattern
and an example path of the energy source in accordance with one
aspect of the disclosure;
[0029] FIG. 11 is a top view depicting a hatch and stripe pattern
used to form at least a part of a component in accordance with one
aspect of the disclosure;
[0030] FIG. 12 is a top view depicting a hatch and stripe pattern
used to form at least a part of a component in accordance with one
aspect of the disclosure;
[0031] FIG. 13 is a perspective view, depicting example layers of
component build during an AM process in accordance with one aspect
of the disclosure;
[0032] FIG. 14 is a top view of the individual layers shown in FIG.
13, depicting a conventional hatch and stripe pattern used to form
at least a part of a component in accordance with one aspect of the
disclosure;
[0033] FIG. 15 is a top view depicting an example leg elimination
hatch and stripe pattern and an example path of the energy source
in accordance with one aspect of the disclosure;
[0034] FIG. 16 is a top view depicting an example hatch and stripe
pattern and an example path of the energy source using an example
dwell path in accordance with another aspect of the disclosure.
DETAILED DESCRIPTION
[0035] While the aspects described herein have been described in
conjunction with the example aspects outlined above, various
alternatives, modifications, variations, improvements, and/or
substantial equivalents, whether known or that are or may be
presently unforeseen, may become apparent to those having at least
ordinary skill in the art. Accordingly, the example aspects, as set
forth above, are intended to be illustrative, not limiting. Various
changes may be made without departing from the spirit and scope of
the disclosure. Therefore, the disclosure is intended to embrace
all known or later-developed alternatives, modifications,
variations, improvements, and/or substantial equivalents.
[0036] When using any of the abovementioned AM techniques to form a
part by at least partially melting a powder, a scan of the laser
across the powder material, in a raster scan fashion is used to
create hatch scans (hereinafter referred to interchangeably as
hatch scans, rasters, scan lines, or solidification lines). During
an AM build, the abovementioned solidification lines are used to
form the bulk of a part cross section. Contour scans, may further
be used to outline the edges of the part cross section. During a
raster scan process, the energy source or laser is turned on,
increased in power and/or focused in regions where a solid portion
of the AM build is desired, and switched off, defocused, and/or
decreased in power where melt formation of the object's cross
section in that layer are not desired. During a raster scan
process, at least partially melting of powder and formation of
solidification is repeated along adjacent solidification lines, for
example, to form a single melted and fused cross section of the
object to be built, while the contour scans create a discrete
border or edge of the part. In the example AM apparatus using a
powder bed, once the melt formation of one cross section of the
object being built is completed, the apparatus coats the completed
cross-sectional surface with an additional layer of powder. The
process is repeated until the object is complete.
[0037] In the aforementioned and subsequent embodiments, the laser
and/or energy source is controlled to form a series of
solidification lines in a layer of powder using a pattern for at
least the following reasons; to decrease build time, to control the
heat buildup within the powder and/or to increase the efficiency of
the build, to improve and/or control the material properties of the
solidified material, to reduce stresses in the completed material,
and/or to reduce wear on the laser and/or galvanometer scanner.
[0038] FIGS. 6 and 7, represent the scan pattern of one embodiment,
wherein a laser is used to form an angled scan pattern forming
solidification lines (e.g. 311 and 312) within a stripe region
bounded one or more stripes 308 and/or 309. One of or both of the
stripes 308 and/or 309 may either be an imaginary boundary and/or
may be formed as a solidification line. For example as shown in
FIG. 10, the laser or a plurality of lasers may be focused,
increased in power and/or turned on while within the stripe region
having width 314 and having imaginary and/or real boundaries 315
and/or 316; accordingly, while a specific stripe region is being
formed, solidification lines are only formed within a stripe region
bounded by stripe boundaries 315 and 316. When the path of the
laser or plurality of lasers are scanned outside of the boundaries
of the stripe region (e.g. portions 401 and 405) the irradiation
source is turned off, defocused and/or decreased in power so that
melting and solidification of the powder does not occur. As an
alternative, the stripe boundaries 315 and/or 316 may also be at
least partially melted and solidified by a laser or irradiation
source and formed as solidification lines either before, after, or
during a scan and solidification process within the stripe
region.
[0039] FIGS. 6 and 7 represent the angled solidification lines
which may be formed within each stripe region in accordance with
one aspect of the disclosure. The solidification line pattern may
be selected to control and/or improve the stresses and
microstructure within the material during a build process and/or to
improve efficiency of the build process. The pattern shown in FIGS.
6-10 is one example of at least partially melted and subsequently
solidified powder that has been fused using an irradiation source
to form solidification lines. The scan pattern may be contained
within a stripe region bounded by a first stripe boundary 308 and
may further be bounded by a second stripe boundary 309 that is
substantially parallel to the first stripe boundary 308 and located
a distance 310 from the first stripe. It is noted that the
disclosed pattern, or any of the patterns described below, may also
cover a portion and/or entire span of the cross-section of the
layer of the part being formed and each layer may be formed by
forming the pattern within stripe regions, over a span of the
entire surface, or any combination of the two. By forming an angled
scan pattern, an increase in the variance between layers can be
achieved over the abovementioned rotating stripe scheme resulting
in a build process that is more efficient and allowing further
tailoring of the microstructure and material properties of the
completed component.
[0040] In one embodiment, for each layer formed during the AM build
process, a first portion of a first layer is formed with
solidification lines 311A formed at an a angle other that
90.degree. with relation to the boundary 308 of the stripe region;
the solidification lines 311 may be contained or bounded by two or
more stripe boundaries (which may hereinafter be interchangeably
referred to as a stripe and/or boundary stripe). The stripes may
have a stripe boundary spacing 310. The solidification lines 311 of
each layer includes a series of first parallel solidification lines
311A beginning at and/or ending at stripe boundary 308 and a second
set of solidification lines 311B beginning and/or ending at the
opposite stripe boundary 309 of the stripe region. Accordingly,
when forming the solidification lines, the laser and/or energy
source scanning vector changes directions (e.g. from 311A, and then
forms a second solidification line 311B, wherein the second
solidification line 311B is angled .theta..sub.A1 with respect to
first solidification line 311A). In other words, the first series
of solidification lines 311A form an incident angle, represented by
.theta..sub.A1 with respect to the second series of solidification
lines 311B.
[0041] In a subsequent layer formed over the first layer, an
example of which is shown in FIG. 7, at least a first portion of a
second layer is formed with solidification lines 312 formed within
a stripe region having width 314 at an a angle other that
90.degree. with relation to, and bounded by at least one boundary
315 and/or 316. The stripe region spacing 314 having at least two
stripe boundaries 315 and/or 316 may be the same as or different
from the stripe spacing 310 of a previous layer or a subsequent
layer (not shown). Further, the solidification lines 312 of the
layer may include a series of third parallel solidification lines
312A beginning at and/or ending at the stripe region boundary 316.
When forming the raster scan in the exemplary layer shown in FIG.
7, the laser and/or energy source may change directions and form a
fourth series of solidification lines 312B, wherein the fourth
series of solidification lines 312B are angled with respect to the
third series of solidification lines 312A. The third series of
solidification lines 312A are formed at an incident angle
.theta..sub.A2 with respect to the fourth series of scan vectors
312B. Angles .theta..sub.A2 and/or .theta..sub.A2 may be varied so
that no subsequent or previous layer has an angle that is the same.
Further, in one aspect the difference between .theta..sub.A1 and
.theta..sub.A2 may be 10.degree. or greater.
[0042] FIGS. 8-10, represent an AM component comprising built by
the solidification of a plurality of layers 415, 416, 417, and 418
in accordance with one embodiment. When built using any of the
abovementioned AM processes, a first layer 418 may be divided by
the abovementioned software into several stripe regions bounded by
stripe boundaries. For example, stripe boundaries 465, 475, and 476
may form at least one boundary for transversely formed
solidification lines. The stripe boundaries 465 and 475 may form a
boundary for individually formed solidification lines 455. As an
example, each solidification line is formed by at least partially
melting portions 402 and 403 as a first substantially linear
solidification line and a second substantially linear
solidification line respectively. Solidification lines 402 and 403
may be in close proximity to the next set of formed solidification
lines 412 and 413. In at least one embodiment, if the laser and/or
energy source melts the powder corresponding to each of portions
402, 403, 412, and 414 in succession, the portions 402, 403, 412,
and 414 may fuse together. For example, when forming portions 402,
403, 412, and 414 a laser and/or energy source may adjusted to
control the amount of powder melted along a solidification line;
accordingly, a melting width and depth of each solidification line
may be controlled. When the laser melts powder corresponding to
solidification line 412, the material in the portion 402 may not
have cooled and the thin line of powder between the portion 402 and
the portion 412 may at least partially melt. The molten material in
a solidification line 402 may fuse with the molten material in
solidification line 412 and the molten material in solidification
line 413 may fuse with the molten material in solidification line
403. The energy source and/or laser may also be controlled so that
the heat radiating from the solidification line 402, and
solidification line 412 may cause the thin line of powder between
solidification lines 402 and/or 403 and solidification lines 412
and/or 413 to sinter together without melting. Further, the
scanning of the energy source and/or laser to form, for example,
solidification line 402 and solidification line 412 may cause the
thin line of powder between the solidification lines 402 and/or 403
and solidification lines 412 and/or 413 to remain unfused without
sintering and/or melting.
[0043] When forming the individual solidification lines 402, 403,
412, and 413, in an example embodiment using a laser as the energy
source, a galvanometer scanner may guide the laser over a path
starting at 401, and continue subsequently to portions 402, 406,
404, 408, 403, 405, 413 and 412. As shown in FIG. 10, the energy
source may be turned off, decreased in power, and/or defocused
(hereinafter interchangeably referred to as skywriting and/or
skywritten) over the path 408, 404, 406, the. It is noted that
while FIG. 10 shows path 408, 404, 406 between solidification lines
402 and 403, a similar path may be followed by the energy source
guiding portion for each subsequent series of solidification lines
(e.g. 413 and 413, for example). As an alternative, the
galvanometer scanner or other energy source guiding mechanism may
also guide the energy source (e.g. laser) over a path starting at
401 and continue subsequently to portions 402, 414, 403, 405, 413
and 412, in this alternative, the energy source may form a
solidification line 402 and continuously form a curved
solidification portion 414 and solidification line 403. It is noted
that while FIG. 10 shows the alternative curved solidification path
414 between solidification lines 402 and 403, a curved
solidification path, such as shown in reference 414 may be followed
by the energy source guiding portion for each subsequent series of
solidification lines (e.g., 413 and 413, for example) thereby
connecting each of the solidification lines with a curved
solidification path instead of forming a point (e.g. the
intersection between solidification lines 402 and 403) at the
intersection of each set of solidification lines. As yet another
alternative, solidifications lines 402 and 403 may be formed
continuously without the energy source being turned off, defocused
and/or decreased in power. Forming solidification lines 402 and 403
continuously, without any skywriting (e.g. 406, 404, and 408) or
without forming a curved solidification portion (e.g. 414) between
the two solidification lines may be most advantageous when the
incident angle between the each solidification line (e.g. 402 and
403 or 413 and 412 is sufficiently large. In one example, a set of
solidification lines (e.g. 402 and 403) are formed continuously,
without skywriting (e.g. 408, 404, and 406) or forming a curved
solidification portion (e.g. 414) between the two solidification
lines when the incident angle between the subsequent solidification
lines is greater than 120.degree.. Further, the two segments may be
formed continuously, without skywriting or forming a curved
solidification portion (e.g. 414) between the two solidification
lines, when the incident angle between the two subsequent
solidification lines is greater than 150.degree.. When forming the
abovementioned portions, the laser is also turned off, defocused
and/or decreased in power such that skywriting occurs in portions
401 and 405, so when forming solidification lines within the stripe
region bounded by stripe boundaries 315 and/or 316, the laser
and/or energy source only supplies enough energy to the powder to
at least partially melt the powder within the stripe region. It is
noted the abovementioned scan pattern is not limited to one energy
and/or laser source, and may be performed by a plurality of energy
and/or laser sources. For example, a first laser may solidification
lines 402 and 403, and a second laser may form solidification lines
412 and 413. Further, it is noted that each of the abovementioned
alternative paths (e.g. skywrite 404, curved solidification path
414 and/or continuously formed solidification lines without a
curved solidification path or skywrite between two sets of angled
solidification lines) may be formed either consistently throughout
the stripe, layer and/or the build, or the abovementioned paths may
be used in any combination either within a stripe, within a build
layer, and/or throughout the build.
[0044] FIGS. 8 and 9, represent the process of building a component
using an AM technique in accordance with one embodiment. At least a
portion of a component built using an AM technique, an example of
which is shown in FIG. 8, comprises a plurality of at least
partially fused layers 415, 416, 417, and 418. A first layer 418
may be divided by the abovementioned software into several stripe
regions bounded by, for example, stripe boundaries 435, 436, 445,
446, 465, 475, and 476. The stripe regions in layer 418, having a
width 314D, form a boundary for series of individual scan portions
formed as solidification lines 458A and 458B, for example. Each
solidification line is formed at an a angle other that 90.degree.
with relation to stripe boundaries 435 and 445 and is contained
within the stripe region. A first solidification line 458A formed
on layer 418 may be substantially linear and may form an incident
angle .theta..sub.1 with respect a second substantially linear
solidification line 458B. As shown in FIG. 10 the energy source
and/or laser path may follow a first linear path to form
solidification line 458A and may change direction to a second
linear path to form a second portion of the solidification line
458B such that the laser forms portions 458A and 458B along the
surface of the powder. Further, while the exemplary figures show
solidification lines 458A and 458B forming an angle having a point,
the abovementioned raster scans may form an angle having a filleted
or curved transition (e.g. as shown in FIG. 10 reference 414)
between solidification lines 458A and 458B, for example. The stripe
region having a width 314D may further be filled in with a
plurality of solidification lines parallel to, for example,
portions 458A and 458B (e.g. as shown in FIG. 10).
[0045] In a next layer 417 of the AM build, a subsequent layer of
powder is distributed over the surface of layer 418. Based on the
desired geometry of the AM part being built, layer 417 may be
divided into a series of stripe regions having a stripe width 314C.
The stripe width 314C may be the same as or different from stripe
width 314D of the previous layer. Layer 417 may include a series of
solidification lines 457A and 457B which are contained in each
stripe region. Each stripe region may be filled with repeating
solidification lines 457A and 457B which are formed at an a angle
other that 90.degree. with relation to, and bounded by stripe
boundaries 436 and 446. For example, one specific solidification
line 457A may be substantially linear and may form an angle
.theta..sub.2 with respect to a continuously formed substantially
linear solidification line 457B. Angle .theta..sub.2 of layer 417
may be different from angle .theta..sub.1 of layer 418, and may be
varied by 10.degree. or greater from .theta..sub.1 of layer 418 or
any of the previous or the immediately subsequent layers. The
energy source and/or laser path may form the solidification line
457A and change direction to form a second portion of the
solidification line 457B; the laser may form portions 457A and 457B
continuously as shown in the example shown in FIG. 10. The stripe
region having a width 314C may further be filled in with a
plurality of solidification lines parallel to, for example,
portions 457A and 457B (e.g. as shown in FIG. 10).
[0046] Subsequent layers of the AM build may be formed using the
abovementioned methods. For example, layers 416 and 417 may be
divided up into stripe regions based on the desired geometry of the
AM build. As stated above, the energy source and/or laser may form
a solidification lines having angles .theta..sub.3 and
.theta..sub.4, which may be varied for each subsequent layer.
Further, the angle with respect to each stripe boundary (e.g. 465,
475 and 476) may be varied for each additional layer. And the
stripe width 314B and 314A may be the same or different for each
subsequent layer. As mentioned above, the angles between a first
solidification line and a second solidification line .theta..sub.3
in layer 416 and .theta..sub.4 in layer 415 may vary by 10.degree.
or more for each subsequent layer.
[0047] Further, it is understood that the angle with respect to the
stripe boundary for each layer (and the stripe width) may be varied
for each layer so that the angle of the solidification lines is
varied for each layer and the angle .theta. between first and
second portion of each solidification line may be kept constant. It
is also noted that the number of angles and solidification lines
bounded by each stripe is not limited to one angle and two portions
of a solidification line, and may include a solidification line
having three or more portions all angled with relation to one
another. It may further be desirable to keep the stripe width,
angle .theta., and the raster hatch pattern constant between at
least two subsequent layers, so that the solidification lines are
kept parallel between two or more layers. It is further noted that
any combination of the abovementioned features and methods may be
used together in an alternative scheme for building the
component
[0048] FIGS. 11 and 12 represent a top view of a scanning and
solidification pattern according to another embodiment employing
the abovementioned strategies and a leg elimination strategy
respectively. In certain portions of an AM build, depending on at
least a geometry of the layer being built. It may be desirable to
control the heat buildup within the powder and/or in the
solidification lines formed on the layer of powder. As shown in
FIG. 11, when the forming a series of solidification lines (eg. 610
and 620) within a stripe region bounded by stripe boundaries 601
and 602, solidification lines which may be formed within each
stripe region in accordance with one aspect of the disclosure. The
solidification line pattern may be selected to control and/or
improve the stresses and microstructure within the material during
a build process and/or to improve efficiency of the build process.
The pattern shown in FIG. 11 is one example of at least partially
melted and subsequently solidified powder that has been fused using
the laser to form solidification lines. The scan pattern may be
contained within a stripe region bounded by a set of boundary
stripes 601 and 602. Further, the stripe region may be bounded by a
contour scan, the end of the component to be built and/or a stripe
boundary 603 (which will be referred to throughout the disclosure
as a stripe boundary). When filling in the stripe region with
solidification lines having first portions 610 and second portions
620 angle with relation to one another a high energy density
portion 601 may be formed due to the shorter spans of the
solidification lines near a stripe boundary 603. It may be
advantageous for even out the heat distribution within the build by
employing a leg elimination strategy, an example of which is shown
in FIG. 12.
[0049] As shown in FIG. 12, at least a portion of a layer being at
least partially melted during an AM build process may include a
stripe region bounded by stripe boundaries 611 and 612. The region
may further be bounded by stripe 613. A first portion of a first
layer is formed with solidification lines 620A formed at an a angle
other that 90.degree. with relation to the boundary 611 of the
stripe region; the solidification lines 610A may by contained or
bounded by two or more stripe boundaries 611, 612, and 613. The
solidification lines 620 of each layer includes a series of first
parallel solidification lines 620A beginning at and/or ending at
stripe boundary 611 and a second set of solidification lines 620B
beginning and/or ending at the opposite stripe boundary 612 of the
stripe region. Accordingly, when forming the solidification lines,
the laser and/or energy source scanning vector changes directions
while forming solidification line 620A, changes direction, and
forms a second solidification line 620B, wherein the second
solidification line 620B is angled with respect to the first
solidification line 620A. In other words, the first series of
solidification lines 620A form an angle with respect to the second
series of solidification lines 620B. Whenever desired and/or when
it is determined that a high energy density portion of the build
may occur, scanning of the laser and subsequent solidification
lines may be altered to form a third series of solidification lines
630, which are bounded and intersect one of the second series of
solidification line 620B at a point (e.g. intersection 792 in FIG.
15), for example. Further, when the third series of solidification
lines 630 are no longer bounded by the second solidification lines
620B, the third series of solidification lines may be continuously
formed into an adjoining stripe region (e.g. portion 613 formed
beyond stripe boundary 612). The third series of solidification
lines 630B may also continue past boundary stripe 611 until
boundary stripe 613 is reached.
[0050] FIGS. 13 and 14, represent several examples of the process
of building a component using an AM technique in accordance with
the abovementioned embodiment. At least a portion of a component
built using an AM technique, an example of which is shown in FIG.
13, comprises a plurality of at least partially fused layers 717,
716, and 715. A first layer 717 may be divided by the
abovementioned software into several stripe regions bounded by, for
example, stripe boundaries 711 and 712. The stripe regions in layer
717, having a width 714A, form a boundary for series of individual
scan portions formed as solidification lines 710A and 720A, for
example. Solidification lines 710A and 720A are formed at an angle
other that 90.degree. with relation to stripe boundaries 711 and
712 and are contained within the stripe region. A first
solidification line 710A formed on layer 717 may be substantially
linear and may form an angle .theta..sub.1 with respect a second
substantially linear solidification line 720A. For example, the
laser path may follow a pattern as shown in FIG. 10; specifically,
the energy source and/or laser path may follow a first linear path
to form solidification line 710A and may change direction to a
second linear path to form a second portion of the solidification
line 720A such that the laser forms portions 710A and 720A along
the surface of the powder. However, when the laser scanning path is
proximal to a portion a third boundary 713 (e.g. a contour scan,
the end of the component to be built and/or a stripe boundary), a
third solidification line 710B is formed. The third solidification
line 710B may be substantially parallel with a solidification line
710A, however solidification line 710 is formed using a
substantially linear laser path that does not change direction
while at least partially melting the powder. In other words,
solidification line 710B is formed from a first stripe boundary 711
to a second solidification line 720A without changing
direction.
[0051] Further, if a subsequent solidification line of the parallel
series of solidification lines 710B is formed in a portion of the
build where the laser path does not intersect a second
solidification line 720A, the laser path may continue past stripe
boundaries 711 and 712 and the build may begin in the next stripe
region. For example, the solidification lines 710B on layer 717 are
bounded by 720A, when the path at which solidification lines 710B
are formed no longer intersect 720A, the solidification lines 710B
continue past stripe boundary 712 and form solidification line
portion 782B in a bordering stripe region. The laser path forming
solidification line 782A then changes direction and forms a
solidification line 783A which is angled with respect to
solidification line 782A. The build in the next stripe region can
then continue using any combination of the above series of angled
solidification lines and/or linear leg elimination solidification
lines.
[0052] In a next layer 716 of the AM build, a subsequent layer of
powder is distributed over the surface of layer 717. Based on the
desired geometry of the AM part being built, layer 717 may be
divided into a series of stripe regions having a stripe width 414B.
The stripe width 414B may be the same as or different from stripe
width 414A of the previous layer. Layer 417 may include a series of
solidification lines 730A and 740A which are contained in each
stripe region. Each stripe region may be filled with repeating
solidification lines 730A and 740A which are formed at an a angle
other that 90.degree. with relation to, and bounded by stripe
boundaries of a stripe region having width 714B. For example, one
specific solidification line 740A may be substantially linear and
may form an angle .theta..sub.2 with respect to a continuously
formed substantially linear solidification line 730A. Angle
.theta..sub.2 of layer 716 may be different from angle
.theta..sub.1 of layer 717, and may be varied by 10.degree. or
greater from .theta..sub.1 of layer 717 or any of the previous or
the immediately subsequent layers. Similarly to the method above,
the energy source and/or laser path may form the solidification
line 740A and change direction to form a second portion of the
solidification line 730A and the stripe region having a width 714B
may be filled in with a plurality of solidification lines parallel
to, for example, portions 730A and 740A. However, when the laser
scanning path is proximal to a portion a third boundary 714 (e.g. a
contour scan, the end of the component to be built and/or a stripe
boundary), a third solidification line 740B is formed. The third
solidification line 740B may be substantially parallel with a
solidification line 740A, however solidification line 740B is
formed using a substantially linear laser path that does not change
direction while at least partially melting the powder. In other
words, solidification line 740B is formed from a stripe boundary to
a solidification line 730A without changing direction. It is noted
that the leg elimination strategy may be employed in a single
stripe region and/or over a single layer of the build and/or over
the entire build depending on the desired characteristics of the
part. Any combination of the abovementioned and below discussed
strategies may be employed in combination throughout the build
process (e.g., one stripe may employ a subsequent stripe may use
the abovementioned triangle hatch strategy).
[0053] When forming the triangular portion of the stripe region, as
shown in FIGS. 15 and 16, for example, each solidification line may
be formed by at least partially melting portions (703, 802) and
(702, 803) as a first substantially linear solidification line and
a second substantially linear solidification line respectively. As
shown, for example in FIG. 16, the solidification lines 802 and 803
may be in close proximity to the next set of formed solidification
lines 812 and 813. In at least one embodiment, if the laser and/or
energy source melts the powder corresponding to each of portions
802, 803, 812, and 814 in succession, the portions 802, 803, 812,
and 81 may fuse together. For example, when forming portions 802,
803, 812, and 813 a laser and/or energy source may adjusted to
control the amount of powder melted along a solidification line;
accordingly, a melting width and depth of each solidification line
may be controlled. When the laser melts powder corresponding to
solidification line 812, the material in the portion 802 may not
have cooled and the thin line of powder between the portion 802 and
the portion 812 may at least partially melt. The molten material in
a solidification line 802 may fuse with the molten material in
solidification line 812 and the molten material in solidification
line 813 may fuse with the molten material in solidification line
803. The energy source and/or laser may also be controlled so that
the heat radiating from the solidification line 802 and
solidification line 812 may cause the thin line of powder between
solidification lines 802 and/or 803 and solidification lines 812
and/or 813 to sinter together without melting. Further, the
scanning of the energy source and/or laser to form, for example,
solidification line 802 and solidification line 812 may cause the
thin line of powder between the solidification lines 802 and/or 803
and solidification lines 812 and/or 813 to remain unfused without
sintering and/or melting.
[0054] When forming the individual solidification lines 802, 803,
812, and 813, in an example using a laser as the energy source, a
galvanometer scanner may guide the laser over a path starting at
701 (FIG. 15) and/or 801 (FIG. 16), for example. In the
non-limiting embodiment shown in FIG. 15, the laser may then
continue subsequently to portions 702, 703, 704 and/or 719, 705,
707, 708 and 409. When forming the abovementioned portions, the
laser is turned off, defocused and/or decreased in power in the
portions of the path represented by dotted lines (with the
exception of the alternative curved solidification portion
represented by reference 719 explained further below). For example
portions 701, 704, 705, 707 and 709 are portions of the path where
the laser is turned off, defocused and/or decreased in power with
relation to the solid portions of the path, so when forming
solidification lines within the stripe region bounded by stripe
boundaries 747 and/or 748, the laser and/or energy source only
supplies enough energy to melt the powder and/or at least partially
melt the powder within the stripe region.
[0055] The leg elimination patterns shown in FIGS. 12, 14, and 15
may be formed using the abovementioned laser and/or e-beam path as
shown in FIG. 15. In one embodiment, one of or both of the stripes
747 and/or 748 may either be an imaginary boundary and/or may be
formed as a solidification line. An energy source (e.g. a laser,
e-beam, and/or a plurality of lasers and/or e- beams) may be
focused, increased in power and/or turned on while within the
stripe region having stripe boundaries 747 and/or 748; accordingly,
while a specific stripe region is being formed, solidification
lines are only formed within a stripe region bounded by stripe
boundaries 747 and 748. When the path of the energy source is
scanned outside of the boundaries of the stripe region (e.g.
portions 701 and 705) the energy source is turned off, defocused
and/or decreased in power so that full melting and solidification
does not occur. As an alternative, the stripe boundaries 747 and/or
748 may also be at least partially melted and solidified by a laser
or energy source and formed as solidification lines either before,
after, or during a scan and solidification process within the
stripe region.
[0056] An exemplary path of the energy source is shown in FIG. 15.
When forming the individual solidification lines (e.g. 702 and 703)
of the series of solidification lines shown, the energy source may
be guided over a path starting at 701, and continue subsequently to
portions 702, 704, 703, and 705. The energy source may be turned
off, decreased in power, and/or defocused (hereinafter
interchangeably referred to as skywriting and/or skywritten) over
the path portions designated by reference numbers 701, 704, 705,
707 and 709, for example. As an alternative, the galvanometer
scanner or other energy source guiding mechanism may also guide the
energy source (e.g. laser) over a path starting at 701, form a
first solidification line 702 and form a curved solidification
portion (an example of which is shown by reference 719) before
forming a second solidification line 703. In this alternative, the
energy source may form a solidification line 702 and continuously
form a curved solidification portion (an example of which is shown
by reference 719) and solidification line 703. It is noted that
while FIG. 15 shows the alternative curved solidification path 719
as a broken line between only two solidification lines, the curved
solidification path, such as shown in reference 719 may be formed
by the energy source guiding portion for each subsequent series of
solidification lines thereby connecting each of the solidification
lines with a curved solidification path instead of forming a point
(e.g. the intersection between solidification lines 702 and 703) at
the intersection of each set of solidification lines. As yet
another alternative, solidifications lines 702 and 703 may be
formed continuously without the energy source being turned off,
defocused and/or decreased in power. Forming solidification lines
702 and 703 continuously, without any skywriting or without forming
a curved solidification portion (e.g. 719) between the two
solidification lines. This alternative may be most advantageous
when the incident angle between the each solidification line (e.g.
702 and 703 is sufficiently large. In one example, a set of
solidification lines (e.g. 702 and 703) are formed continuously,
without skywriting (e.g. 704) between the two solidification lines
when the incident angle between the subsequent solidification lines
is greater than 120.degree.. Further, the two segments may be
formed continuously, without skywriting between the two
solidification lines, when the incident angle between the two
subsequent solidification lines is greater than 150.degree..
Further, it is noted that each of the abovementioned alternative
paths (e.g. skywrite 704, curved solidification path 719 and/or
continuously formed solidification lines without a curved
solidification path or skywrite between two sets of angled
solidification lines) may be formed either consistently throughout
the stripe, layer and/or the build, or the abovementioned paths may
be used in any combination either within a stripe, within a build
layer, and/or throughout the build.
[0057] As shown in FIG. 15, when the energy source scanning path
and solidification lines are proximal to a portion a third boundary
718 (e.g. a contour scan, the end of the component to be built
and/or a stripe boundary), a third solidification line 706 is
formed. The third solidification line 706 may be substantially
parallel to a the series of solidification lines represented by
reference 703. However, solidification line 706, and the subsequent
series of solidification lines may be formed using a substantially
linear energy source that does not change direction (e.g. segment
706), while at least partially melting the powder. In other words,
solidification lines 706 are formed from a stripe boundary 747 to a
solidification line 791 without changing direction. The remainder
of the solidification lines (e.g. 706) may then be formed as though
solidification line 791 is a stripe boundary. Accordingly, once the
scanning strategy switches to the leg elimination portion of the
scan pattern, the energy source skywrites in portion 707 when it
passes solidification line 791 at point 792, for example. It is
notes that in the abovementioned embodiment using a curved
solidification portion 719, the line segment 706 may be bounded by
the curved solidification portion 719 such that skywriting occurs
once the energy source path passes the intersection point 706B of
the curved solidification portion 719 and the segment 706.
[0058] It is noted the abovementioned scan pattern is not limited
to one energy and/or laser source, and may be performed by a
plurality of energy and/or laser sources. For example, a first
laser may form solidification lines 702 and 703, and a second laser
may form solidification line 706.
[0059] The abovementioned process may be repeated for each
subsequent layer. For example, subsequent layer 715 (FIG. 14) may
include a stripe region having width 714D which is at least
partially filled using solidification lines formed parallel with
exemplary solidification lines 760A and 750A which are formed at an
a angle other that 90.degree. with relation to, and bounded by
stripe boundaries of a stripe region. Exemplary solidification
lines 760A and 750A two segments that are angled .theta..sub.3 with
relation to one another. As mentioned above, when the laser
scanning path is proximal to a portion a third boundary (e.g. a
boundary other than the stripe boundaries for solidification lines
760A and 750A), a third series of solidification lines 760B are
formed that are substantially parallel with solidification line
760A. Solidification lines 760B is formed using a substantially
linear laser path (e.g. the path does not change direction while
forming the solidification line) continuing to a solidification
line 750A without changing direction.
[0060] The abovementioned leg elimination scan strategy may be used
in combination with or as an alternative to any of the
abovementioned scan strategies. Further, depending on the
geometries and desired properties of the component being build
using the AM process, each layer may include a plurality of stripe
regions, wherein each stripe region is filled using any one of or
combination of the abovementioned strategies depending on any one
or combination of reasons including, for example: a part geometry,
a decrease in build time, to control the heat buildup within the
powder and/or to increase the efficiency of the build, to improve
and/or control the material properties of the solidified material,
to reduce stresses in the completed material, and/or to reduce wear
on the laser, e-beam and/or galvanometer scanner.
[0061] In another embodiment, a dwell pattern may be used in
combination with or as an alternative to the above mentioned leg
elimination strategy, a dwell method as shown in FIG. 16, for
example, may be used to control the heat buildup between each
solidification line as well. As an example, each solidification
line may be formed by at least partially melting portions 802 and
803 as a first substantially linear solidification line and a
second substantially linear solidification line respectively.
Solidification lines 802 and 803 may be in close proximity to the
next set of formed solidification lines 812 and 813. In at least
one embodiment, if the laser and/or energy source melts the powder
corresponding to each of portions 802, 803, 812, and 814 in
succession, the portions 802, 803, 812, and 813 may fuse together.
As another example, when forming portions 802, 803, 812, and 813 a
laser and/or energy source may adjusted to control the amount of
powder melted along a solidification line; accordingly, a melting
width and depth of each solidification line may be controlled. When
the laser melts powder corresponding to solidification line 812,
the material in the portion 802 may not have cooled and the thin
line of powder between the portion 802 and the portion 812 may at
least partially melt. The molten material in a solidification line
802 may fuse with the molten material in solidification line 812
and the molten material in solidification line 813 may fuse with
the molten material in solidification line 803. The energy source
and/or laser may also be controlled so that the heat radiating from
the solidification line 802 and solidification line 812 may cause
the thin line of powder between solidification lines 802 and/or 803
and solidification lines 812 and/or 813 to sinter together without
melting. Further, the scanning of the energy source and/or laser to
form, for example, solidification line 802 and solidification line
812 may cause the thin line of powder between the solidification
lines 802 and/or 803 and solidification lines 812 and/or 813 to
remain unfused without sintering and/or melting.
[0062] An exemplary path of the energy source is shown in FIG. 16.
When forming the individual solidification lines (e.g. 802 and 803)
of the series of solidification lines shown, the energy source may
be guided over a path starting at 801, and continue subsequently to
portions 802, 804, 803, 805, 813, and 812. The energy source may be
turned off, decreased in power, and/or defocused (hereinafter
interchangeably referred to as skywriting and/or skywritten) over
the path the paths 801, 804, and 805. As an alternative, the
galvanometer scanner or other energy source guiding mechanism may
also guide the energy source (e.g. laser) over a path forming a
first solidification line 813 and form a curved solidification
portion 814 before forming a second solidification line 812. In
this alternative, the energy source may form a solidification line
813 and continuously form a curved solidification portion 814 and
solidification line 812. It is noted that while FIG. 16 shows the
alternative curved solidification path 814 as a dotted line between
only two solidification lines, the curved solidification path, such
as shown in reference 814 may be formed by the energy source
guiding portion for each subsequent series of solidification lines
thereby connecting each of the solidification lines with a curved
solidification path instead of forming a point (e.g. the
intersection between solidification lines 802 and 803) at the
intersection of each set of solidification lines. As yet another
alternative, solidifications lines 802 and 803 may be formed
continuously without the energy source being turned off, defocused
and/or decreased in power. Forming solidification lines 802 and 803
continuously, without any skywriting within the stripe or without
forming a curved solidification portion (e.g. 814) between the two
solidification lines. This alternative may be most advantageous
when the incident angle between the each solidification line (e.g.
802 and 803 is sufficiently large. In one example, a set of
solidification lines (e.g. 802 and 803) are formed continuously,
without skywriting within the stripe (e.g. without skywritten
portion 804) between the formation of the two solidification lines
when the incident angle between the subsequent solidification lines
is greater than 120.degree.. Further, the two segments may be
formed continuously, without skywriting within the stripe
boundaries between the two solidification lines, when the incident
angle between the two subsequent solidification lines is greater
than 150.degree.. It is noted that each of the abovementioned
alternative paths (e.g. skywrite 704, curved solidification path
719 and/or continuously formed solidification lines without a
curved solidification path or skywrite between two sets of angled
solidification lines) may be formed either consistently throughout
the stripe, layer and/or the build, or the abovementioned paths may
be used in any combination either within a stripe, within a build
layer, and/or throughout the build.
[0063] When forming the individual solidification lines 802, 803,
812, and 813, in an example using a laser, for instance, a
galvanometer scanner may guide the laser over a path starting at
801, and continue subsequently to portions 802, 803, 805, 813, and
812. When forming the abovementioned portions, the laser is turned
off, defocused and/or decreased in power in portions 801 and 805 so
that when forming solidification lines within the stripe region
bounded by stripe boundaries 815 and/or 816, the laser and/or
energy source only supplies enough energy to the powder to at least
partially melt the powder within the stripe region. It is noted
that all of the abovementioned scan patterns are not limited to one
energy and/or laser source, and may be performed by a plurality of
energy and/or laser sources. For example, a first laser may
solidification lines 802 and 803, and a second laser may form
solidification lines 812 and 813.
[0064] Depending on at least a geometry of the layer being built
and/or a stripe boundary. It may be desirable to control the heat
buildup within the powder and/or in the solidification lines formed
on the layer of powder using a dwell strategy. For instance, when
using the triangle hatch pattern disclosed above, a part boundary
or other barrier 820 may be reached at the end of the stripe region
when the forming a series of solidification lines (e.g. 802, 803,
812, and 813) within a stripe region bounded by stripe boundaries
815 and 816. As each solidification line gets shorter near the part
boundary or other barrier 820, the powder which is at least
partially melted to form solidification lines may have insufficient
time to cool before the next set of solidification lines are
formed. If insufficient sufficient cooling time between the forming
of solidification lines occurs, a high energy density portion 830
of the AM build may formed. If the high energy density region, is
not accounted for during a build process by decreasing the amount
of energy and/or increasing the amount of time during which the
energy source is at least partially melting powder, boiling
porosity or other defects in the completed AM build may occur. As
discussed above, one method of preventing boiling porosity is to
form the solidification lines in a pattern that minimizes
concentrated heat build-up (e.g. the leg elimination strategy
discussed above). Another method of preventing excessive heat
buildup is to have the energy source continue on the same path
while the energy source is turned off and/or defocused as described
below.
[0065] As shown in FIG. 16, solidification lines 802 and 803 may be
formed by an energy source path having a length and time t.sub.1.
As shown, solidification lines 802 and 803 are formed with the
energy source at least partially melting and forming solidification
lines over most of the length t.sub.1. When the possibility of a
high density region occurs, for example near a boundary, stripe or
other portion of the build 820, the length and time over which
melting occurs is shortened for each subsequent segment, and the
time and distance over which the energy source follows the path
without melting is increased. For example, when the solidification
lines nearest to portion 830 are formed, the scanning path remains
the same or similar to the scanning length t.sub.1, but the energy
source is primarily not melting and/or partially melting (e.g. over
distance t.sub.2) and is only melting over a short period of the
span (e.g. t.sub.3). By increasing the time over which melting is
not occurring by continuing over substantially the same path, the
solidification lines formed closest to portion 830 are allowed to
cool sufficiently before the next subsequent solidification lines
are formed. Thus the heating and cooling properties of the powder
during formation of the solidification lines near portion 830 can
be controlled so as to be similar to the heating and cooling
properties of the powder when solidification lines 802, 803, 813,
and 812 are formed. By employing the abovementioned strategy,
improvements in the control of the heat buildup within the powder
and/or control the material properties of the solidified material
to reduce stresses in the completed material can be achieved.
Father, advantages such as reduced wear on the laser, e-beam and/or
galvanometer scanner can also be realized.
[0066] Because an increase in build time may result using the
abovementioned strategy, the dwell strategy, an example of which is
shown in FIG. 16, may be used in combination with any of the
abovementioned strategies. For example the dwell strategy may be
used at a portion of the build where the abovementioned leg
elimination strategy is not practical. Further, the strategy may be
used in combination with or as an alternative to any of the
abovementioned scan strategies for any reason. For instance,
depending on the geometries and desired properties of the component
being build using the AM process, each layer may include a
plurality of stripe regions, wherein each stripe region is filled
using any one of or combination of the abovementioned strategies
depending on any one or combination of reasons including, for
example: a part geometry, a decrease in build time, to control the
heat buildup within the powder and/or to increase the efficiency of
the build, to improve and/or control the material properties of the
solidified material, to reduce stresses in the completed material,
and/or to reduce wear on the laser, e-beam and/or galvanometer
scanner.
[0067] In an aspect, the present invention further relates to a
method of forming solidification lines and a stripe pattern used in
additive manufacturing techniques which may be of the present
invention incorporated or combined with features of other powder
bed additive manufacturing methods and systems. The following
patent applications include disclosure of these various aspects and
their use:
[0068] U.S. patent application Ser. No. 15/406,467, titled
"Additive Manufacturing Using a Mobile Build Volume," with attorney
docket No. 037216.00059, and filed Jan. 13, 2017.
[0069] U.S. patent application Ser. No. 15/406,454, titled
"Additive Manufacturing Using a Mobile Scan Area," with attorney
docket No. 037216.00060, and filed Jan. 13, 2017.
[0070] U.S. patent application Ser. No. 15/406,444, titled
"Additive Manufacturing Using a Dynamically Grown Build Envelope,"
with attorney docket No. 037216.00061, and filed Jan. 13, 2017.
[0071] U.S. patent application Ser. No. 15/406,461, titled
"Additive Manufacturing Using a Selective Recoater," with attorney
docket No. 037216.00062, and filed Jan. 13, 2017.
[0072] U.S. patent application Ser. No. 15/406,471, titled "Large
Scale Additive Machine," with attorney docket No. 037216.00071, and
filed Jan. 13, 2017.
[0073] The disclosures of these applications are incorporated
herein in their entirety to the extent that they disclose
additional aspects of powder bed additive manufacturing methods and
systems that can be used in conjunction with those disclosed
herein.
[0074] This written description uses examples to disclose the
invention, including the preferred embodiments, and also to enable
any person skilled in the art to practice the invention, including
making and using any devices or systems and performing any
incorporated methods. The patentable scope of the invention is
defined by the claims, and may include other examples that occur to
those skilled in the art. Such other examples are intended to be
within the scope of the claims if they have structural elements
that do not differ from the literal language of the claims, or if
they include equivalent structural elements with insubstantial
differences from the literal language of the claims. Aspects from
the various embodiments described, as well as other known
equivalents for each such aspect, can be mixed and matched by one
of ordinary skill in the art to construct additional embodiments
and techniques in accordance with principles of this
application.
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