U.S. patent application number 15/513483 was filed with the patent office on 2017-10-26 for lighting for additive manufacturing.
The applicant listed for this patent is Hewlett-Packard Development Company, L.P.. Invention is credited to James Elmer Abbott, Jr., Sivapackia Ganapathiappan, Alexander Govyadinov, Vladek Kasperchik, Krzysztof Nauka, Hou T. Ng, Howard S. Tom, Lihua Zhao, Yan Zhao.
Application Number | 20170305066 15/513483 |
Document ID | / |
Family ID | 55581673 |
Filed Date | 2017-10-26 |
United States Patent
Application |
20170305066 |
Kind Code |
A1 |
Nauka; Krzysztof ; et
al. |
October 26, 2017 |
LIGHTING FOR ADDITIVE MANUFACTURING
Abstract
In one example, a non-transitory processor readable medium
having instructions thereon that when executed cause an additive
manufacturing machine to expose build material to a light source
emitting monochromatic light within a band of wavelengths that
includes a peak light absorption of a liquid coalescing agent to be
dispensed on to the build material.
Inventors: |
Nauka; Krzysztof; (Palo
Alto, CA) ; Ganapathiappan; Sivapackia; (Los Altos,
CA) ; Zhao; Lihua; (Sunnyvale, CA) ; Tom;
Howard S.; (San Jose, CA) ; Zhao; Yan; (Palo
Alto, CA) ; Ng; Hou T.; (Campbell, CA) ;
Abbott, Jr.; James Elmer; (Albany, OR) ; Govyadinov;
Alexander; (Corvallis, OR) ; Kasperchik; Vladek;
(Corvallis, OR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hewlett-Packard Development Company, L.P. |
Houston |
TX |
US |
|
|
Family ID: |
55581673 |
Appl. No.: |
15/513483 |
Filed: |
September 26, 2014 |
PCT Filed: |
September 26, 2014 |
PCT NO: |
PCT/US2014/057715 |
371 Date: |
March 22, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 64/165 20170801;
B29C 64/393 20170801; B33Y 10/00 20141201; B33Y 50/02 20141201;
B29C 64/264 20170801 |
International
Class: |
B29C 64/264 20060101
B29C064/264; B33Y 10/00 20060101 B33Y010/00; B33Y 50/02 20060101
B33Y050/02; B29C 64/393 20060101 B29C064/393 |
Claims
1. A non-transitory processor readable medium having instructions
thereon that when executed cause an additive manufacturing machine
to expose build material to a light source emitting monochromatic
light within a band of wavelengths that includes a peak light
absorption of a liquid coalescing agent to be dispensed on to the
build material.
2. The processor readable medium of claim 1, where the instructions
include instructions to expose the build material to a light source
emitting monochromatic light with a spectral intensity at least
1.times.10.sup.12Wm.sup.-3s.sup.-1.
3. The processor readable medium of claim 1, where the instructions
include: instructions to expose first build material to a first
light source emitting a first monochromatic light within a first
band of wavelengths that includes a first peak light absorption of
a first coalescing agent to be dispensed on to the first build
material; and instructions to expose second build material to a
second light source emitting a second monochromatic light within a
second band of wavelengths that includes a second peak light
absorption of a second coalescing agent to be dispensed on to the
second build material different from the first coalescing
agent.
4. The processor readable medium of claim 3, where the instructions
include instructions to expose build material to: the first light
source emitting the first monochromatic light with a spectral
intensity at least 1.times.10.sup.12Wm.sup.-3sr.sup.-1; and the
second light source emitting the second monochromatic light with a
spectral intensity at least
1.times.10.sup.12Wm.sup.-3sr.sup.-1.
5. A computer program product that includes the processor readable
medium of claim 4.
6. An additive manufacturing machine controller that includes the
processor readable medium of claim 4.
7. An additive manufacturing process, comprising: dispensing a
liquid coalescing agent on to build material in a pattern
corresponding to a slice; and exposing patterned build material to
monochromatic light within a band of wavelengths that includes a
peak light absorption of the coalescing agent.
8. The process of claim 7, where the exposing includes exposing the
build material to the monochromatic light with a spectral intensity
at least 1.times.10.sup.12Wm.sup.-3sr.sup.-1.
9. The process of claim 8, where the exposing includes exposing the
build material to the monochromatic light until raising the
temperature of the patterned build material by 20.degree. C. to
50.degree. C.
10. An additive manufacturing process, comprising: dispensing a
liquid coalescing agent on to build material in a pattern
corresponding to a slice, the coalescing agent containing a light
absorbing component that absorbs at least 60% of light in a band of
wavelengths; and exposing patterned build material to monochromatic
light within the band of wavelengths under conditions sufficient to
coalesce the patterned build material exposed to the monochromatic
light.
11. The process of claim 10, where the conditions include raising
the temperature of the patterned build material by 20.degree. C. to
50.degree. C.
12. The process of claim 10, where the conditions include exposing
patterned build material to monochromatic light having a spectral
intensity at least 1.times.10.sup.12Wm.sup.-3sr.sup.-1 in the band
of wavelengths.
13. The process of claim 10, where the light absorbing component
includes one or more of a colorless dye, a cyan colorant, a magenta
colorant, a yellow colorant, and black colorant and: for a
colorless dye, exposing the patterned build material to
monochromatic light in the band of 800 nm to 1350nm; for a yellow
colorant, exposing the patterned build material to monochromatic
light in the band of 380 nm to 500 nm; for a magenta colorant,
exposing the patterned build material to monochromatic light in the
band of 420 nm to 600 nm; for a cyan colorant, exposing the
patterned build material to monochromatic light in the band of 520
nm to 700 nm; and for a black colorant, exposing the patterned
build material to monochromatic light in the band of 380 nm to 700
nm.
14. The process of claim 10, where the coalescing agent includes
one or more of yellow ink, magenta ink, cyan ink and black ink and:
for yellow ink, exposing the patterned build material to
monochromatic light in the band of 380 nm to 500nm; for magenta
ink, exposing the patterned build material to monochromatic light
in the band of 420 nm to 600 nm; for cyan ink, exposing the
patterned build material to monochromatic light in the band of 520
nm to 700 nm; and for black ink, exposing the patterned build
material monochromatic light in the band of 380 nm to 700 nm.
15. The process of claim 10, comprising, before exposing patterned
build material to monochromatic light, dispensing a coalescence
modifier agent on to build material bordering patterned build
material, on to patterned build material, or on to build material
bordering patterned build material and on to patterned build
material.
Description
BACKGROUND
[0001] Additive manufacturing machines produce 3D
(three-dimensional) objects by building up layers of material. Some
additive manufacturing machines are commonly referred to as "3D
printers" because they often use inkjet or other printing
technology to apply some of the manufacturing materials. 3D
printers and other additive manufacturing machines make it possible
to convert a CAD (computer aided design) model or other digital
representation of an object directly into the physical object.
DRAWINGS
[0002] FIGS. 1-9 present a sequence of sections illustrating one
example for additive manufacturing a two slice object.
[0003] FIGS. 10-13 are flow diagrams illustrating example additive
manufacturing processes.
[0004] FIG. 14 is a graph showing one example of light absorption
as a function of wavelength for black, yellow, magenta, cyan and
colorless coalescing agents.
[0005] FIG. 15 is a graph showing one example of spectral intensity
as a function of wavelength for monochromatic light sources that
emit light near the peak absorptions of some of the coalescing
agents shown in FIG. 14.
[0006] FIG. 16 illustrates one example of a processor readable
medium with lighting instructions for additive manufacturing.
[0007] FIG. 17 is a block diagram illustrating one example of an
additive manufacturing machine implementing a controller that
includes a processor readable medium with lighting instructions,
such as the medium shown in FIG. 16.
[0008] FIG. 18 is a block diagram illustrating one example of an
additive manufacturing system implementing a CAD computer program
product that includes a processor readable medium with lighting
instructions, such as the medium shown in FIG. 16.
[0009] FIG. 19 illustrates one example of a carriage assembly with
a coalescing agent dispenser and a monochromatic light source for
an additive manufacturing machine, such as the machine shown in
FIG. 17 or FIG. 18.
[0010] The same part numbers designate the same or similar parts
throughout the figures.
DESCRIPTION
[0011] Additive manufacturing machines make a 3D object through the
solidification of one or more layers of a build material. Additive
manufacturing machines make objects based on data in a 3D model of
an object generated, for example, with a CAD computer program
product. The model data is processed into slices each defining that
part of a layer or layers of build material to be solidified.
Examples of additive manufacturing described below use a technique
sometimes referred to as "light area processing" (LAP) in which an
ink or other suitable coalescing agent is dispensed on to a layer
of build material in the desired pattern and then exposed to light.
Light absorbing components in the coalescing agent absorb light to
generate heat that sinters, melts or otherwise coalesces the
patterned build material, allowing the patterned build material to
solidify.
[0012] LAP heating may occur in two steps. First, the build
material is heated to and maintained at temperature just below its
coalescing temperature, for example with a combination of resistive
heaters and a lower intensity heater lamp. Second, a coalescing
agent is "printed" or otherwise dispensed on to the build material
in the desired pattern and exposed to a higher intensity coalescing
lamp emitting light absorbed into the patterned build material,
Presently, halogen lamps emitting light over a broad spectrum are
usually used in both steps. Accordingly, carbon black ink is often
used as the coalescing agent to absorb light over a broad spectrum
to generate enough heat to effectively coalesce the patterned build
material. The use of black ink, however, limits the color of the
manufactured objects to black and grey.
[0013] A variety of different color objects may be manufactured
with LAP using colored and colorless inks that have high light
absorption within a narrow band of wavelengths. Colorless inks that
absorb only infrared light may be particularly desirable coalescing
agents because they enable manufacturing objects that are the same
color as the starting build material. The colorless dyes described
in the international patent applications filed by Hewlett-Packard
Development Company in September 2014 under attorney docket nos.
84030477 and 84030486 and titled 3-Dimensional Printing, for
example, have been developed for use as ink based LAP coalescing
agents, Broad band halogen lamps, however, may be inadequate for
heating build material patterned with colored and colorless inks
because only a small portion of the light emitted falls within the
band of wavelengths where high light absorption occurs, and thus
the amount of absorbed radiative energy may be inadequate to heat
the patterned build material to a coalescing temperature. In
addition, light emitted outside this band of wavelengths may have
undesirable heating effects.
[0014] New LAP lighting techniques have been developed to
manufacture color objects (other than black and grey) using color
and colorless coalescing agents, including the colorless dyes
described in the 84030477 and 84030486 patent applications.
Examples of the new techniques utilize monochromatic light covering
the peak light absorption of the coalescing agent to develop the
heat needed to reach coalescing temperatures. In one example, an
additive manufacturing process includes dispensing a liquid
coalescing agent on to build material in a pattern corresponding to
an object slice and then exposing the patterned build material to
monochromatic light within a band of wavelengths that includes a
peak light absorption of the coalescing agent. Although the
intensity of the monochromatic light needed for adequate heating
may vary depending on the characteristics of the build material and
coalescing agent, it is expected that monochromatic light with a
spectral intensity at least 1.times.10.sup.12Wm.sup.-3sr.sup.-1
(watts per cubic meter per steradian) will be sufficient for many
implementations.
[0015] In another example, a carriage assembly for an additive
manufacturing machine carries an array of individually addressable
monochromatic light sources along with an inkjet printhead to
dispense the coalescing agent. Individual light sources may be
energized selectively to illuminate only patterned build material
to limit unwanted effects on surrounding build material and to
reduce power consumption. Also, the array may include a single set
of monochromatic light sources (only one wavelength band)
corresponding to a coalescing agent with an absorption peak within
the band, or multiple sets of light sources (multiple wavelength
bands) to accommodate a greater range of coalescing agents. The use
of a monochromatic lighting array enables an integrated carriage
assembly to carry both the printhead(s) and the light sources for
immediate, targeted lighting.
[0016] The electronic instructions to control monochromatic
lighting in an additive manufacturing machine may reside on a
processor readable medium implemented, for example, in a CAD
computer program product, in an object model processor, or in the
controller for the additive manufacturing machine.
[0017] These and other examples described below and shown in the
figures illustrate but do not limit the scope of this disclosure,
which is defined in the Claims following this Description.
[0018] As used in this document: "coalesce" means to become a
coherent mass by heating, for example by sintering or melting; a
"coalescing agent" means a substance that causes or helps cause a
build material to coalesce; a "coalescence modifier agent" means a
substance that inhibits or prevents coalescence of a build
material, for example by modifying the effect of a coalescing
agent; "monochromatic" means within a band of wavelengths 30 nm or
narrower; "polychromatic" means a band of wavelengths broader than
30 nm; and a "slice" means one or more slices of a multi-slice
object or the object itself for a single slice object.
[0019] The sequence of sections presented in FIGS. 1-9 illustrate
one example for manufacturing a three dimensional object 10 shown
in FIG. 9. FIGS. 10 and 11 are flow diagrams illustrating example
additive manufacturing processes 100 and 130, respectively,
implemented in the example of FIGS. 1-9. Referring first to FIG. 1,
in this example a supply 12 of powdered build material 14 is held
on a delivery piston 16 in a supply bed 18. A roller or other
suitable layering device 20 moves build material 14 from supply bed
18 to a receiving piston 22 in a manufacturing bed 24, as indicated
by arrow 26. Pistons 16 and 22 move up and down, respectively, as
build material 14 is moved from supply bed 18 to manufacturing bed
24. Any suitable build material 14 may be used to make the desired
solid object, which may be hard or soft, rigid or flexible, elastic
or inelastic. Also, while a powdered build material 14 is depicted
by particles 28 in this example, suitable non-powdered build
materials could be used.
[0020] Referring now also to FIG. 10, a first layer 30 of build
material 14 is formed in manufacturing bed 24 as shown in FIG. 1
(block 102 in FIG. 11). In some implementations, it may be
desirable to pre-heat build material 14, particularly in the first
few layers, to help keep each layer flat during coalescence and
solidification. Individual layers of build material 14 may be
pre-heated in manufacturing bed 24, as shown in FIG. 1 (block 104
in FIG. 10), or build material 14 may be pre-heated in supply bed
18, or a combination of heating in both beds 18 and 24.
"Pre-heating" in this context refers to heating before light is
applied to coalesce build material for coalescence, as described
below with reference to FIG. 4. While the pre-heating temperature
will vary depending on the characteristics of build material 14,
the pre-heating temperature usually will be 20.degree. C. to
50.degree. C. below the melting point or the sintering point for a
nylon 12 powdered build material. Any suitable heater 32 may be
used. In the example shown in FIG. 1, heater 32 includes a heating
lamp positioned over bed 24. In other examples, heater 32 may
include a resistive heater in the powder bed used alone or with a
heating lamp.
[0021] In FIG. 2, a coalescing agent 34 is dispensed on to build
material 14 in layer 30 in a pattern corresponding to the first
object slice (block 106 in FIG. 10), for example with an inkjet
type dispenser 36. This pattern for coalescing agent 34 is depicted
by an area 38 of dense stippling in the figures. If desired, a
coalescence modifier agent 40 may be dispensed on to build material
14 in layer 30 for example with an inkjet type dispenser 44, as
shown in FIG. 3 (block 108 in FIG. 10). Modifier agent 40 blocks or
neutralizes the effects of the coalescing agent and may be applied
before or after coalescing agent (or both before and after) to help
control the degree of coalescence of targeted areas of build
material for improved dimensional accuracy and overall quality of
the manufactured object. In the example shown in FIG. 3, modifier
agent 40 is dispensed on to an area 42 covering the area where a
second object slice will overhang the first slice. Overhang area 42
covered by coalescence modifier agent 40 is depicted by light
stippling in the figures. Coalescence modifier agent 40 may also be
dispensed on to other areas of build material layer 30 to help
define other aspects of the object slice, including interspersed
with the pattern of the coalescing agent to change the material
characteristics of the slice. Although two dispensers 36, 44 are
shown, agents 34 and 40 could be dispensed from the same dispensers
integrated into a single device, for example using different
printheads (or groups of printheads) in a single inkjet printhead
assembly.
[0022] Coalescing agent 34 includes a light absorbing component to
absorb light to generate heat that sinters, melts or otherwise
coalesces patterned build material 38. The rate of light absorption
for different types of coalescing agents 34 will vary over
different parts of the electromagnetic spectrum depending on the
characteristics of the light absorbing component. For example, a
yellow colorant may have a peak light absorption at about 450 nm
wavelength light. A cyan colorant, by contrast, may have a peak
light absorption at about 700 nm wavelength light. Black ink may
have high absorption across a broad band of wavelengths compared to
high absorption for yellow and cyan across narrow bands of
wavelengths.
[0023] As noted above, it may not always be desirable to use black
ink as a coalescing agent 34. However, because other colors absorb
light across a narrower band of wavelengths, the time it takes to
generate coalescing heat with a polychromatic, halogen lamp using
cyan ink, for example, may be too long to be practical for additive
manufacturing. Heating time may be reduced to practical levels for
cyan and other color inks, and even for colorless inks, by using
monochromatic light matching the color absorption band of
coalescing agent 34. Thus, in FIG. 4, the area of layer 30
patterned with coalescing agent 34 is exposed to monochromatic
light 46 from a light source 48 to coalesce build material
patterned with coalescing agent 34, allowing the patterned build
material to solidify and form first object slice 50 (block 110 in
FIG. 10). In one example, as described in the more detail below,
light source 48 is configured to emit monochromatic light 46 within
a band of wavelengths that includes the peak light absorption of
coalescing agent 34 with sufficient intensity to coalesce patterned
build material. Any suitable light source 48 may be used to emit
monochromatic light including, for example, LEDs, laser diodes and
other sources that emit monochromatic light directly as well as
light sources that emit monochromatic light by filtering,
splitting, dispersing, refracting or otherwise producing
monochromatic light from polychromatic light.
[0024] The process may be repeated for second and subsequent layers
to form a multi-slice object. For example, in FIG. 5 a second layer
52 of build material 14 is formed in manufacturing bed 24 over
first layer 30 (block 112 in FIG. 10) and pre-heated (block 114 in
FIG. 10). In FIG. 6, a coalescing agent 34 is dispensed on to build
material 14 in layer 52 in a pattern 54 corresponding to the second
object slice (block 116 in FIG. 10), including along the edge of an
area 56 overhanging first slice 50. In FIG. 7, a coalescence
modifier agent 40 is dispensed on to build material 14 in layer 52
in area 58 to help prevent the unwanted coalescence and
solidification of build material along the edge of the overhang
(block 118 in FIG. 10). In FIG. 8, the area 54 of layer 52
patterned with coalescing agent 34 is exposed to monochromatic
light 46 to coalesce build material and form second object slice 60
overhanging first slice 46 (block 120 in FIG. 10).
[0025] Agent dispensers 36 and 44 may be carried back and forth
across manufacturing bed 24 together with light source 48, as
indicated by arrows 62 in FIGS. 1-8, on a single carriage or on two
or more separate carriages. Also, it may be possible in some
implementations to use stationary agent dispensers 36, 44 and/or
light sources 48. Coalescing agent 34 dispensed on to build
material 14 in second layer 52 may be the same as or different from
the coalescing agent dispensed on to first layer 30. Accordingly,
monochromatic light 46 to coalesce patterned build material in
second layer 52 may be the same or different wavelength from the
light to coalesce patterned build material in first layer 30. Also,
while distinct first and second slices 50 and 60 are shown in FIG.
8, the two slices actually fuse together into a single part upon
coalescing and solidification of the second slice. The now fused
slices 50, 60 may be removed from manufacturing bed 24 as a
finished object 10 shown in FIG. 9. Although a simple two-slice
object 10 is shown, the same process steps may be used to form more
complex, multi-slice objects.
[0026] FIG. 11 illustrates another example of an additive
manufacturing process 130. Referring to FIG. 11, a liquid
coalescing agent is dispensed on to build material in a pattern
corresponding to a slice (block 132) and patterned build material
is exposed to monochromatic light within a band of wavelengths that
includes a peak light absorption of the coalescing agent (block
134). The wavelength of the monochromatic light will vary depending
on the peak absorption of the light absorbing component in the
coalescing agent. Several examples are described below with
reference to the graphs shown in FIGS. 14 and 15. Also, the
intensity of the monochromatic light should be great enough to
allow the patterned build material to reach a coalescing
temperature within a practical period of time. Thus, as shown in
FIG. 12, exposing patterned build material to monochromatic light
in block 134 of FIG. 11 may be performed, for example, by exposing
patterned build material to monochromatic light with a spectral
intensity at least 1.times.10.sup.12Wm.sup.-3sr.sup.-1. Referring
to FIG. 13, in one specific example described below, exposing
patterned build material to monochromatic light in block 134 of
FIG. 11 may be performed by exposing patterned build material to
monochromatic light with a spectral intensity at least
1.times.10.sup.12Wm.sup.-3sr.sup.-1to raise the temperature of the
patterned build material 20.degree. C. to 50.degree. C. in a quite
practical time of 1 second or less.
[0027] Several examples of coalescing agent and matching
monochromatic light to generate coalescing heat are described below
with reference to the graphs of FIGS. 14 and 15. FIG. 14 shows
light absorption as a function of wavelength for black, yellow,
magenta, cyan and colorless ink coalescing agents. A colorant acts
as the light absorbing component in each ink which, for the color
inks represented in FIG. 14, is a color pigment. The pigment based
inkjet inks represented in FIG. 14 are commercially available from
Hewlett-Packard Company as C8750 (black), C4905 (yellow), C4904
(magenta), and C4903 (cyan). A colorless dye acts as the light
absorbing component in the colorless dye based ink represented in
FIG. 14. Two such dyes are described in the 84030477 and 84030486
patent applications noted above.
[0028] FIG. 15 shows spectral intensity as a function of wavelength
for several examples of commercially available light sources that
emit monochromatic light near the peak absorptions for the color
coalescing agents shown in FIG. 14. (Suitable light sources that
emit monochromatic light near the peak absorption for the colorless
coalescing agent shown in FIG. 14 are not yet readily available
commercially.) FIG. 15 also shows the spectral intensity of a 2500K
halogen lamp relative to the monochromatic light sources.
[0029] A colorless ink such as that represented in FIG. 14 will
absorb 60% or more light in the band of 800 nm to 1350 nm,
including 808 nm light emitted by the infrared laser diode in FIG.
15. A yellow ink such as that represented in FIG. 14 will absorb
60% or more light in the band of 380 nm to 500 nm, including the
450 nm light emitted by the blue laser diode and the 470 nm light
emitted by the blue LED in FIG. 15. A magenta ink such as that
represented in FIG. 14 will absorb 60% or more light in the band of
420 nm to 600 nm, including the 590 nm light emitted by the yellow
LED in FIG. 15. A cyan ink such as that represented in FIG. 14 will
absorb 60% or more light in the band of 520 nm to 700 nm, including
the 590 nm light emitted by the yellow LED and the 640 nm red LED
in FIG. 15. A black ink such as that represented in FIG. 14 will
absorb 60% or more light across the full spectrum of visible light
(380 nm to 700 nm), including light emitted by any of the color
LEDs and laser diodes in FIG. 15.
[0030] As shown in FIG. 15, the spectral intensity of the
monochromatic light is significantly higher at or near peak
absorption than the spectral intensity of the polychromatic light
emitted by a 2500K halogen lamp. It has been demonstrated that
monochromatic light sources such as the LEDs and laser diodes
represented in FIG. 15 produce enough energy to generate the heat
needed to coalesce polymer build materials when matched to the
proper light absorbing component in the coalescing agent. In one
example, a nylon 12 build material powder that coalesces at about
185.degree. C. is pre-heated to about 150.degree. C., patterned
with a yellow ink from FIG. 14, and exposed to a blue LED emitting
470 nm light from a distance less than 2 cm. The yellow ink
absorbing nearly 100% of the incident light should generate
sufficient heat to reach the coalescing temperature of about
185.degree. C. at least 10 times faster than with a 2500K halogen
lamp. If the patterned build material is exposed to a blue laser
diode emitting 450 nm light, the coalescing temperature may be
reached even faster. While the threshold absorption for adequate
heating will vary depending on the build material and the
monochromatic light source, it is expected that sufficient heat may
be generated in an exposure time less than 1 second if the
coalescing agent absorbs incident light at a rate of 60% or more
for matching light with a spectral intensity at least
1.times.10.sup.12Wm.sup.-3sr.sup.-1.
[0031] FIG. 16 is a block diagram illustrating a processor readable
medium 64 with instructions 66 to control lighting during the
manufacture of a 3D object. A processor readable medium 64 is any
non-transitory tangible medium that can embody, contain, store, or
maintain instructions for use by a processor. Processor readable
media include, for example, electronic, magnetic, optical,
electromagnetic, or semiconductor media. More specific examples of
suitable processor readable media include a hard drive, a random
access memory (RAM), a read-only memory (ROM), memory cards and
sticks and other portable storage devices.
[0032] Lighting instructions 66 include instructions to control
monochromatic lighting during the manufacture of a 3D object, for
example by exposing patterned build material to monochromatic light
at block 134 in FIGS. 11-13. Instructions 66 may include other
lighting instructions, for example instructions to pre-heat build
material at block 104 in FIG. 10 with a heating lamp 32 in FIGS.
1-8. Processor readable medium 64 with instructions 66 may be
implemented, for example, in a CAD computer program product, in an
object model processor, or in a controller for an additive
manufacturing machine. Control data to inhibit solidification can
be generated, for example, by processor readable instructions on
the source application, usually a CAD computer program product, in
an object model processor, or by processor readable instructions on
the additive manufacturing machine.
[0033] FIG. 17 is a block diagram illustrating one example of an
additive manufacturing machine 68 implementing a controller 70 with
lighting instructions 66. Referring to FIG. 17, machine 68 includes
controller 70, a manufacturing bed or other suitable support 24, a
roller or other suitable build material layering device 20, a
coalescing agent dispenser 36, a coalescence modifier agent
dispenser 44, a heater 32 and a light source 48. The in-process
object structure is supported on support 24 during manufacturing.
In some machines 68, support 24 is movable at the urging of
controller 70 to compensate for the changing thickness of the
in-process structure, for example as layers of build material are
added during manufacturing.
[0034] Build material layering device 20 layers build material on
support 24 and on the in-process structures and may include, for
example, a device to dispense the build material and a blade or
roller to distribute the build material uniformly to the desired
thickness for each layer. Coalescing agent dispenser 36 dispenses
coalescing agent selectively at the direction of controller 70 on
to build material, for example as described above with reference to
FIGS. 2 and 6. Coalescence modifier agent dispenser 44 dispenses
modifier agent selectively at the direction of controller 70 on to
build material, for example as described above with reference to
FIGS. 3 and 7. While any suitable dispensers 36, 44 may be used,
inkjet printheads are often used in additive manufacturing machines
because of the precision with which they can dispense agents and
their flexibility to dispense different types and formulations of
agents. Manufacturing machine 68 may include a heater 32 if it is
desired to pre-heat the build material. Manufacturing machine 36
includes a light source 48 to apply light energy to coalesce build
material treated with coalescing agent, for example as described
above with reference to FIGS. 5 and 8.
[0035] Controller 70 represents the processor (or multiple
processors), the associated memory (or multiple memories) and
instructions, and the electronic circuitry and components needed to
control the operative elements of machine 68. In particular,
controller 70 includes a memory 72 having a processor readable
medium 64 with lighting instructions 66 and a processor 74 to read
and execute instructions 66. For example, controller 70 would
receive control data and other instructions from a CAD program to
make an object and execute local lighting instructions 66 as part
of the process of making the object.
[0036] Alternatively, lighting instructions 66 may be embodied in a
processor readable medium 64 separate from controller 70, for
example as part of a CAD computer program product shown in FIG. 18.
Referring to FIG. 18, an additive manufacturing system 76 includes
an additive manufacturing machine 68 operatively connected to a CAD
computer program product 78 with lighting instructions 66 residing
on a processor readable medium 64. Any suitable connection between
machine 68 and CAD program product 78 may be used to communicate
instructions and control data to machine 68 including, for example,
a wired link, a wireless link, and a portable connection such as a
flash drive or compact disk.
[0037] FIG. 19 illustrates one example of a carriage assembly 79
for an additive manufacturing machine such as machine 68 shown in
FIGS. 17 and 18. Referring to FIG. 19, carriage assembly 79
includes a carriage 80 carrying agent dispensers 36, 44 and a light
source 48. Carriage 80 is movable back and forth over manufacturing
bed 24 to dispense coalescing and modifier agents 34, 40, for
example as shown in FIGS. 2-3 and 6-7, and to expose patterned
build material to monochromatic light 46, for example as shown in
FIGS. 4 and 8. In the example shown in FIG. 19, agent dispensers 36
and 44 are configured as elongated inkjet printheads that span the
width of bed 24 with an array of nozzles 82 through which the
agents are dispensed on to build material supported on bed 24, or
that span so much of the width of bed 24 corresponding to a build
zone 88 for layering and coalescing the build material. While two
printheads 36, 44 with only a single line of dispensing nozzles are
shown, other configurations are possible. For example, more or
fewer printheads could be used each with a different array of
dispensing nozzles, including printheads and nozzles to dispense
multiple different color (or colorless coalescing agents.
[0038] Also, in the example shown, light source 48 is configured as
a pair of light bars 84 that span the width of bed 24 with an array
of individually addressable LEDs, laser diodes or other
monochromatic light sources 86, or that span so much of the width
of bed 24 corresponding to a build zone 88 for layering and
coalescing the build material. Each of the light sources 86 or each
of multiple groups of the light sources 86 is individually
addressable in the array to emit light selectively independent of
any other light source in the array or of any other group of light
sources in the array. Each light bar 84 is positioned outboard of
agent dispensers 36, 44 to enable illuminating patterned build
material on bed 24 immediately after dispensing an agent 34, 40, if
desired, when carriage 80 is moving in either direction across bed
24. Individual light sources 86 may be energized selectively at the
direction of the controller 70 to illuminate only patterned build
material to limit unwanted effects on surrounding build material
and to reduce power consumption. In addition, each light bar 84 may
include a single set of monochromatic lights (only one wavelength
band) corresponding to coalescing agents with absorption peaks
within that band, or multiple sets of lights (multiple wavelength
bands) to accommodate a greater range of coalescing agents. Other
suitable lighting configurations are possible. For example, light
source 48 may he supported on a carriage distinct from the carriage
supporting the agent dispenser(s). For another example, light
source 48 may be configured as a stationary array of monochromatic
light sources 86 covering build zone 88.
[0039] In one example, each light bar 84 includes a line of
monochromatic red light sources, a line of monochromatic green
light sources and a line of monochromatic blue light sources to
cover corresponding absorption peaks for cyan, magenta, and yellow
coalescing agents, respectively. Lines or other arrays of multiple
monochromatic light sources enable manufacturing an object with
different color parts using a single light source 48. Thus, for
example, a first color (or colorless) coalescing agent 34 may be
dispensed at block 106 in FIG. 10 and exposed to a corresponding
first color (or colorless) monochromatic light 46 at block 110, and
a second color (or colorless) coalescing agent 34 dispensed at
block 116 and exposed to a corresponding second color (or
colorless) monochromatic light 46 at block 120. Other processes are
possible. For another example, dispensing a coalescing agent at one
or both blocks 106 and 116 may include patterning build material
with multiple, different coalescing agents 34 and exposing the
different patterns to corresponding multiple, different
monochromatic light 46 to obtain different colors within the same
layer of build material.
[0040] While a powdered polymer build material is often used for
additive manufacturing, other suitable build materials may be used,
including metals and other non-polymers and/or liquids, pastes, and
gels. Suitable coalescing agents include water or solvent based
dispersions with a light absorbing component. As one example, the
coalescing agent may be an ink that includes colored or colorless
pigments or dyes as the light absorbing component.
[0041] Suitable coalescence modifier agents may separate individual
particles of the build material to prevent the particles from
joining together and solidifying as part of the slice. Examples of
this type of coalescence modifier agent include colloidal,
dye-based, and polymer-based inks, as well as solid particles that
have an average size less than the average size of particles of the
build material. The molecular mass of the coalescence modifier
agent and its surface tension should be such that it enables the
agent to penetrate sufficiently into the build material to achieve
the desired mechanical separation. In one example, a salt solution
may be used as a coalescence modifier agent. In other examples,
inks commercially known as CM996A and CN673A available from
Hewlett-Packard Company may be used as a coalescence modifier
agent. Suitable coalescence modifier agents may act to modify the
effects of a coalescing agent by preventing build material from
reaching its coalescing temperature during heating. A fluid that
exhibits a suitable cooling effect may be used as this type of
coalescence modifier agent. For example, when build material is
treated with a cooling fluid, heat in the build material may be
absorbed evaporating the fluid to help prevent build material from
reaching its coalescing temperature. Thus, for example, a fluid
with a high water content may be a suitable coalescence modifier
agent. Other types of coalescence modifier agent may be used.
[0042] "A" and "an" used in the Claims means one or more.
[0043] The examples shown in the figures and described above
illustrate but do not limit the scope of this disclosure, which is
defined in the following Claims.
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