U.S. patent application number 11/337079 was filed with the patent office on 2006-07-27 for method and apparatus for manufacturing three-dimensional objects.
This patent application is currently assigned to Aisan Kogyo Kabushiki Kaisha. Invention is credited to Hiroyuki Hara, Shigeki Yamada.
Application Number | 20060165546 11/337079 |
Document ID | / |
Family ID | 36696935 |
Filed Date | 2006-07-27 |
United States Patent
Application |
20060165546 |
Kind Code |
A1 |
Yamada; Shigeki ; et
al. |
July 27, 2006 |
Method and apparatus for manufacturing three-dimensional
objects
Abstract
The present invention teaches a method and an apparatus for
manufacturing a three-dimensional object having a smooth outer
surface, without any step of removing a surface layer each time a
sintered layer is formed so as to manufacture a three-dimensional
object consisting of integrally built-up sintered layers. The
method may include the steps of: (i) supplying powder particles
(10) onto a moving area while heating the powder particles (10)
with heat (20) from a high-density energy heat source so as to form
a sintered layer (16); and (ii) supplying powder particles 10 onto
a moving area on the sintered layer while heating the powder
particles (10) with heat (20) from the high-density energy heat
source so as to form another sintered layer (18) integrally on the
sintered layer (16), wherein the step (ii) is repeated a
predetermined number of times.
Inventors: |
Yamada; Shigeki; (Aichi-ken,
JP) ; Hara; Hiroyuki; (Aichi-ken, JP) |
Correspondence
Address: |
DENNISON, SCHULTZ, DOUGHERTY & MACDONALD
1727 KING STREET
SUITE 105
ALEXANDRIA
VA
22314
US
|
Assignee: |
Aisan Kogyo Kabushiki
Kaisha
|
Family ID: |
36696935 |
Appl. No.: |
11/337079 |
Filed: |
January 23, 2006 |
Current U.S.
Class: |
419/6 |
Current CPC
Class: |
B33Y 30/00 20141201;
B22F 10/20 20210101; Y02P 10/25 20151101; B22F 12/00 20210101; B33Y
10/00 20141201; B22F 10/10 20210101 |
Class at
Publication: |
419/006 |
International
Class: |
B22F 7/02 20060101
B22F007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 24, 2005 |
JP |
2005-015483 |
Claims
1. A method for manufacturing a three-dimensional object formed
from a plurality of integrally built-up sintered layers, comprising
the steps of: (i) supplying powder particles onto a moving area
while heating the powder particles with heat irradiated from a
high-density energy heat source so as to form a sintered layer; and
(ii) supplying powder particles onto a moving area on the sintered
layer while heating the powder particles with heat irradiated from
the high-density energy heat source so as to form another sintered
layer integrally on the sintered layer, wherein the step (ii) is
repeated a predetermined number of times.
2. The method as in claim 1, wherein the powder particles are
operably supplied onto the moving areas so that the surface region
of the three-dimensional object to be obtained has higher density
than the inside region thereof.
3. The method as in claim 1, wherein the powder particles, for
forming the inside region of the three-dimensional object to be
obtained, have a larger particle diameter than the powder particles
for forming the surface region thereof.
4. The method as in claim 1, wherein the powder particles, for
forming the inside region of the three-dimensional object to be
obtained, are prepared by granulating the powder particles for
forming the surface region thereof.
5. The method as in claim 1, wherein the powder particles, for
forming the surface region of the three-dimensional object to be
obtained, are metal powder particles while the powder particles for
forming the inside region thereof are metal powder particles mixed
with an organic binder.
6. The method as in claim 1, wherein a supplying rate for the
powder particles, for forming the inside region of the
three-dimensional object to be obtained, is greater than a
supplying rate for the powder particles for forming the surface
region thereof.
7. The method as in claim 1, wherein the high-density energy heat
source is a laser.
8. The method as in claim 1, wherein a supplying rate of the powder
particles is adjustable.
9. The method as in claim 1, wherein the powder particles are
selectable from a group of two or more different types of powder
particles.
10. An apparatus for manufacturing a three-dimensional object
formed from a plurality of integrally built-up sintered layers,
comprising: a powder particle supplying means for supplying powder
particles in a adjustable supplying rate; a high-density energy
heat source for heating the powder particles supplied by the powder
particle supplying means; and a driving means for moving an area
onto which the powder particles are supplied by the powder particle
supplying means.
11. A method for manufacturing a three-dimensional object having a
surface region and an inside region, both of the regions formed
from a plurality of integrally built-up sintered layers, comprising
the steps of: (i) supplying first powder particles while heating
and sintering the first powder particles into a plurality of
sintered layers forming the surface region of the three-dimensional
object; and (ii) supplying second powder particles while heating
and sintering the second powder particles into a plurality of
sintered layers forming the inside region of the three-dimensional
object, wherein the average particle diameter of the second powder
particles is greater than the average particle diameter of the
first powder particles.
12. The method as in claim 11, wherein the second powder particles
are prepared from a same powder type as the first powder
particles.
13. A three-dimensional object having a surface region and an
inside region, both of the regions formed from a plurality of
sintered layers integrally built-up, wherein the three-dimensional
object is manufactured by the method as in claim 11.
14. A three-dimensional object having a surface region and an
inside region, both of the regions formed from a plurality of
sintered layers integrally built-up, wherein the three-dimensional
object is manufactured by the method as in claim 12.
Description
[0001] This application claims priority to Japanese patent
application serial number 2005-15483, the contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The present invention relates to a method and an apparatus
for manufacturing three-dimensional objects consisting of
integrally built-up sintered layers.
[0004] 2. Description of the Related Art
[0005] In order to manufacture three-dimensional objects consisting
of integrally built-up sintered layers, Japanese Laid-Open
Publication Nos. 2002-115004 and 2003-159755 disclose a rapid
prototyping method including the steps of: forming a powder layer
of inorganic or organic material on a sintering table; sintering a
predetermined portion of the powder layer by irradiating with an
optical beam to form a sintered layer; covering the sintered layer
with a new powder layer; and repeating the aforementioned steps to
form a plurality of sintered layers united together.
[0006] According to the aforementioned rapid prototyping method, in
which a powder layer is formed and then an optical beam is
irradiated on a predetermined portion of the powder layer,
unnecessary powder adheres to the sintered and hardened portions
because of the heat transferred from the circumference thereof. In
this case, the adhered powder forms a low-density surface layer so
that the resulting three-dimensional object may not have a smooth
and accurate outer surface.
[0007] In this respect, Japanese Laid-Open Publication No.
2003-159755 discloses a method including a step of removing the
low-density surface layer by a cutting tool or the like each time a
predetermined portion of the powder layer is sintered by
irradiating with an optical beam to form another sintered layer.
However, according to this method, it will be necessary to remove
the surface layer each time a sintered layer is formed. This
requires additional processing time and costs for the removal step
as compared to a method without such a removal step.
SUMMARY OF THE INVENTION
[0008] It is one object of the present invention to teach a method
and an apparatus for manufacturing a three-dimensional object
having a smooth outer surface, without any additional steps of
removing a surface layer each time a sintered layer is formed so as
to manufacture a three-dimensional object consisting of integrally
built-up sintered layers.
[0009] According to one aspect of the present teachings, a method
for manufacturing a three-dimensional object consisting of a
plurality of integrally built-up sintered layers is taught that may
include the steps of: (i) supplying powder particles onto a moving
area while heating the powder particles with heat irradiated from a
high-density energy heat source so as to form a sintered layer;.
and (ii) supplying powder particles onto a moving area on the
sintered layer while heating the powder particles with heat
irradiated from the high-density energy heat source so as to
integrally form another sintered layer on the previous sintered
layer, wherein the step (ii) is repeated a predetermined number of
times. This method makes it possible to manufacture a
three-dimensional object having a complex and precise shape in a
short time and with reduced costs. The three-dimensional object
manufactured by the method of the present invention is applicable,
for example, to a mold for injection molding having a complex
internal structure, or to a part or its prototype having a complex
three-dimensional shape.
[0010] The method may include further features: that the powder
particles are operably supplied onto the moving area so that the
surface region of the three-dimensional object has a higher density
than the inside region thereof; that the powder particles for
forming the inside region of the three-dimensional object have a
larger particle diameter than the powder particles for forming the
surface region thereof; that the powder particles for forming the
inside region of the three-dimensional object are obtained by
granulating the powder particles for forming the surface region
thereof; that the powder particles for forming the inside region of
the three-dimensional object are metal particles while the powder
particles for forming the surface region thereof are metal
particles mixed with an organic binder; that a supplying rate for
the powder particles for forming the inside region of the
three-dimensional object is greater than a supplying rate for the
powder particles for forming the surface region thereof; that the
high-density energy heat source is a laser; that a supplying rate
of the powder particles is adjustable; and that the powder
particles are selectable from a group of two or more different
types of powder particles.
[0011] The term "powder particles" herein refers to powder
materials or particles that are sintered by heating. The term
"sintering" refers to causing at least a portion of powder
particles to be softened or melted by heating so as to integrally
adhere to the surrounding powder particles on the softened or
melted portion. "Sintering" may be either liquid phase sintering,
which causes a portion of powder particles to be melted so as to
integrally adhere to the surrounding powder particles, or solid
phase sintering, which causes powder particles to integrally adhere
by contacting each other without melting. Preferably, the powder
particles used in the present invention may integrally adhere to
each other through solid phase sintering, which enables a
three-dimensional object to be formed having a smoother outer
surface and a more accurate shape than through liquid phase
sintering. Solid phase sintering also enables a three-dimensional
object to be formed in a shorter time, because it requires less
heating.
[0012] The "powder particles" used in the present invention may
include, but are not limited to, metal powder particles of steel or
stainless steel such as SUS420 or SUS410L, and ceramic powder
particles. It is also possible to use a mixture of the
aforementioned powder particles.
[0013] A process for preparing such powder particles may include,
but is not limited to, an atomization process and a mechanical
process such as crushing, grinding, and milling. Preferably, powder
particles used in the present invention may be prepared to be
spherical and as uniform as possible with respect to particle
diameter distribution. For example, powder particles pulverized
into fine spherical particles through an atomization process are
preferable in the present invention. The average particle diameter
may include, but is not limited to, the range generally between 1
.mu.m and 100 .mu.m, and preferably between 10 .mu.m and 50 .mu.m.
It should be noted that the "average particle diameter" refers to a
representative particle diameter corresponding to a cumulative
oversize weight percentage of 50% estimated from a cumulative
oversize weight percentage versus particle diameter curve.
[0014] The "high-density energy heat source" used in the present
invention refers to a heat source for locally heating a supplied
powder area. For example, a plasma-transferred arc, a
non-transferred plasma arc, a laser, or a mixture of these
high-density energy heat sources may be used as the high-density
energy heat source. In particular, the laser may include a carbon
dioxide laser and a YAG laser. Such a heat source may be
appropriately selected according to factors such as the type, the
volume, and the particle diameters of the powder particles, and the
accuracy requirements for forming the surface of the
three-dimensional object. Using such a local heating heat source
enables the target powder particles supplied onto a predetermined
area to be intensively heated and sintered. Also, it is possible to
prevent various defects such as lower forming accuracy and
deposition of the powder particles onto the surface portions,
otherwise caused by heat transferred to areas other than the
desired sintering area.
[0015] In particular, the high-density energy heat source may heat
powder particles supplied on a predetermined area either
concurrently with or immediately subsequent to the supply of the
powder particles. Thus, it is possible to intensively heat the
target powder particles supplied onto a predetermined area, which
results in preventing the heat from transferring to a portion
surrounding the target portion to be sintered and hardened.
Further, since there exist no extra powder particles surrounding
the target portion to be sintered and hardened, it is possible to
prevent unnecessary powder particle depositions, which are caused
by transferred heat, onto the three-dimensional object to be
obtained. As a result, without removing the low-density surface
layer by a cutting tool or the like each time a sintered layer is
formed, it is possible to manufacture a three-dimensional object
having a smooth and accurate outer surface.
[0016] According to another aspect of the present invention, an
apparatus is taught for manufacturing a three-dimensional object
consisting of a plurality of integrally built-up sintered layers
that may include: a powder particle supplying device for supplying
powder particles at a adjustable supplying rate; a high-density
energy heat source for heating the powder particles supplied by the
powder particle supplying device; and a driving device for moving
an area onto which the powder particles are supplied by the powder
particle supplying device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Additional objects, features and advantages of the present
invention will be readily understood after reading the following
detailed description together with the claims and the accompanying
drawings, in which:
[0018] FIG. 1 is a schematic view showing one representative
embodiment of a sintered layer forming process;
[0019] FIG. 2 is a perspective view of a three-dimensional object
formed on a work table according to the present invention; and
[0020] FIG. 3 is a cross-sectional view of the three-dimensional
object taken along the line III-III shown in FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Each of the additional features and teachings disclosed
above and below may be utilized separately or in conjunction with
other features and teachings to provide an improved method and
apparatus for manufacturing a three-dimensional object.
Representative examples of the present invention, which examples
utilize many of these additional features and teachings both
separately and in conjunction with one another, will now be
described in detail. This detailed description is merely intended
to teach a person of skill in the art further details for
practicing preferred aspects of the present teachings and is not
intended to limit the scope of the invention. Only the claims
define the scope of the claimed invention. Therefore, combinations
of features and steps disclosed in the following detailed
description may not be necessary to practice the invention in the
broadest sense, and are instead taught merely to particularly
describe representative examples of the invention. Moreover,
various features of the representative examples and the dependent
claims may be combined in ways that are not specifically enumerated
in order to provide additional useful embodiments of the present
teachings.
[0022] As shown in FIG. 1, powder particles 10 are heated and
sintered into sintered layers 16 and 18. It should be noted that
the boundary lines between the sintered layers 16 and 18 are shown
in FIG. I for the convenience of the explanation, although the
sintered layers 16 and 18 are actually integrally built-up as shown
in FIGS. 2 and 3. In particular, the powder particles 10 are
supplied onto a work table 14 from a powder supplying nozzle 12.
The nozzle 12 is moved in a predetermined direction so that the
supplied powder area is moved. Thus, while the area, onto which the
powder particles 10 are supplied, is moved, the powder particles 10
supplied onto the area are heated by a laser beam 20 downwardly
irradiated from a laser as a high-density energy heat source.
Accordingly, the powder particles 10 are sintered by heating so as
to be formed into a sintered layer 16. Preferably, the thickness of
the sintered layer 16 may be configured operably within, but is not
limited to, the range between 0.01 mm and 0.5 mm.
[0023] In order to form a new sintered layer 18, the powder
particles 10 are supplied from the powder supplying nozzle 12 onto
the sintered layer 16, which has been previously built up on the
work table 14. Thus, while the area, onto which the powder
particles 10 are supplied, is moved with the nozzle 12, the powder
particles 10 supplied onto the area are heated by the laser beam 20
irradiated from the laser. Accordingly, the new sintered layer 18
is integrally formed on the previous sintered layer 16. The
thickness of the new sintered layer 18 may preferably be configured
operably within, but is not limited to, the range between 0.01 mm
and 0.5 mm.
[0024] By repeating the aforementioned process a predetermined
number of times, in which a new sintered layer 18 is formed on the
previous sintered layer 16 in a layer-by-layer manner, it is
possible to manufacture a three-dimensional object consisting of a
plurality of integrally built-up sintered layers.
[0025] Further, by controlling the two-dimensional shape of each
sintered layer, a three-dimensional object may be manufactured in a
desired shape. In particular, it is required to control the
trajectory of the moving area onto which the powder particles 10
are supplied. This is achieved, for example, by controlling the
physical relationship between the nozzle 12 and the table 14. In
this case, either the nozzle 12 or the table 14 may be moved to
control the physical relationship therebetween. It will of course
be appreciated that both the nozzle 12 and the table 14 may be
moved. In order to move the nozzle 12 and/or the table 14, a
conventional feed mechanism or an XY drive unit driven by linear
motors and the like may be used.
[0026] The trajectory of the area onto which the powder particles
10 are supplied may be defined by three-dimensional CAD data or the
like of the three-dimensional object to be obtained. For example,
the trajectory may be defined by contour data corresponding to each
cross-section of the three-dimensional object to be obtained. Or
otherwise, when a prototype of a part, for example, is to be
manufactured, a geometrical shape sensor such as an optical sensor
is used to measure the geometrical shape of the surface on the
target part. Based on the measured geometrical shape data, the
trajectory of the area may be defined onto which the powder
particles 10 are supplied.
[0027] Preferably, the trajectory of the area onto which the powder
particles 10 are supplied may appropriately be compensated, for
example, by interposing a compensation calculation while the sensor
recognizes each shape of a sintered layer that is being actually
formed. Such a compensation technique is particularly useful when a
layer to be formed with powder particles 10 has either a
contraction or an expansion property during the heating and
sintering. When powder particles 10 are used that may cause a layer
to be contracted during the heating and sintering, the trajectory
is preferably controlled by the movement of the nozzle 12 so as to
trace a contour shape slightly larger than the actual contour shape
corresponding to the target cross-section of the three-dimensional
object to be obtained. On the other hand, when powder particles 10
are used that may cause a layer to be expanded during the heating
and sintering, the trajectory is preferably controlled by the
movement of the nozzle 12 so as to trace a contour shape slightly
smaller than the actual contour shape corresponding to the target
cross-section of the three-dimensional object to be obtained. It
should be noted that the trajeciory of the area onto which the
powder particles 10 are supplied by the nozzle 12 may be controlled
by such as a conventional numerical control device.
[0028] When a prototype of a part having a certain
three-dimensional shape is manufactured, the prototype is required
to be accurately reproduced to the original shape of the target
part. In this case, as long as the reproducibility of the outside
appearance of the target part is maintained, the inside region of
the prototype may not be required to be manufactured in high
density. Namely, the highest priority is given to the outside
appearance of the target part being manufactured in high density,
while the inside density of the target part may not required to be
uniform with the outside density.
[0029] Thus, it is preferable to supply powder particles 10 so that
the surface region of the three-dimensional object to be obtained
has higher density than the inside region thereof. The
"three-dimensional object to be obtained" described above refers to
a three-dimensional object to be manufactured by a manufacturing
method according to the present invention. The "surface region" of
the three-dimensional object to be obtained refers to a portion
near the outside surface of the three-dimensional object, or a
portion in particular from the outer surface to a predetermined
depth, such as a depth generally in a range from 0.1 mm to 10
mm.
[0030] Also, the "inside region" of the three-dimensional object to
be obtained refers to a portion inside of the "surface region," or
toward the center of the three-dimensional object. The sentence
"the surface region of the three-dimensional object to be obtained
has higher density than the inside region thereof" refers to a
density relationship between the surface region and the inside
region, while the boundary therebetween is not required to be
particularly distinct. The boundary may be formed in such a manner
that the density of the three-dimensional object gradually
decreases from the surface region to the inside region.
[0031] By way of example, FIGS. 2 and 3 show a three-dimensional
object 30 manufactured according to the present invention. A
surface region 32 is formed with sintered layers of a higher
density, while an inside region 34 is formed with sintered layers
of a lower density. Since the surface region 32 is formed with
high-density sintered layers, the accurate reproducibility of the
original part may be maintained even if the three-dimensional
object 30 is formed with a complex shape. Thus, it is possible to
manufacture a prototype generally having the same shape as the
three-dimensional shape of the original part. It should be noted
that the surface region 32 shown in FIG. 2 is not formed on the top
and bottom surfaces, but is formed around the side surfaces of the
inside region 34.
[0032] Further, since the surface region 32 is formed with
high-density sintered layers, it is possible to minimize the
distortion generally caused in the three-dimensional object 30 by
thermal contraction and the like. Thus, even if the
three-dimensional object 30 to be obtained is larger than
conventional objects, the accurate reproducibility of the
three-dimensional shape may be ensured.
[0033] Still further, since the surface region 32 is formed with
high density, it is possible to manufacture the three-dimensional
object 30 having the surface region 32 with a sufficient
strength.
[0034] It should be noted that the aforementioned prototyping
according to the present invention may be achieved with reduced
costs and increased speed as compared to the case where the
three-dimensional object 30 is entirely manufactured with a uniform
high density, since the present invention enables the inside region
34 to be formed with a lower density so as to save the amount of
the powder particles otherwise consumed.
[0035] In summary, in order to form the surface region 32 with a
higher density while forming the inside region 34 with a lower
density, at least one of the following processes may be performed:
[0036] (a) supplying fewer powder particles for forming the surface
region 32 than for forming the inside region 34; [0037] (b)
supplying powder particles at a lower supplying rate for forming
the surface region 32 than for forming the inside region 34,
wherein the "supplying rate" refers to the supplying amount of
powder particles per unit of time; [0038] (c) supplying powder
particles 10 of smaller particle diameter for forming the surface
region 32, while supplying powder particles 10' of larger particle
diameter for forming the inside region 34, wherein the terms
"smaller" and "larger" refers to the relationship of particle
diameters between the powder particles 10 for forming the surface
region 32 and the powder particles 10' for forming the inside
region 34; [0039] (d) supplying powder particles 10 to form the
surface region 32, while supplying granulated powder particles 10'
prepared by granulating the powder particles 10 of the same type
supplied to form the surface region 32, wherein the particle
diameter of the granulated powder particles 10' are larger than
that of the mere powder particles 10 due to the granulation; and
[0040] (e) supplying metal powder particles 10 to form the surface
region 32, while supplying metal powder particles 10' mixed with an
organic binder to form the inside region 34.
[0041] By performing at least one of the processes (a) to (e),
powder particles 10, 10' may be supplied so that the surface region
32 of the three-dimensional object 30 to be obtained is formed with
a higher density, while the inside region 34 thereof is formed with
a lower density. Thus, it is possible to manufacture the
three-dimensional object 30 having a surface region 32 formed with
a high density and high strength, while having the inside region
34, which is not seen, formed with a low density.
[0042] In the process (c), larger powder particles 10' are supplied
to form the inside region 34 so that less thermal energy is
required to heat and sinter the powder particles 10'. This is
because larger powder particles 10', which have fewer contact areas
with other powder particles 10' than the smaller powder particles
10, generally require less thermal energy to soften or melt the
contact areas. This may also contribute to reduced costs and
increased speed in manufacturing the three-dimensional object
30.
[0043] In the process (d), the granulated powder particles 10' for
forming the inside region 34 are prepared by granulating the
smaller powder particles 10 supplied for forming the surface region
32. Thus, the three-dimensional object 30 is manufactured with the
surface region 32 formed with a higher density, while the inside
region 34 is formed with the larger, granulated powder particles
10'. Also, since both the surface region 32 and the inside region
34 are sintered with the same type of powder particles, a binding
affinity may be increased between the surface region 32 and the
inside region 34 so that the binding strength therebetween may be
enhanced. As a result, it is possible to prevent such defects as a
release between the surface region 32 and the inside region 34.
[0044] In the process (e), the metal powder particles 10' mixed
with an organic binder may be prepared as granulated powder
particles, which may be obtained by processes of: mixing metal
powder particles with a synthetic resin binder; heating the
binder-mixed particles into a slurry form with the melted binder;
atomizing the slurry into droplets with a spray dryer; and
solidifying the droplets into granulated powder particles. In this
case, the average particle diameter of the granulated powder
particles may include, but is not limited to, the range generally
between 50 .mu.m and 1000 .mu.m, and preferably between 100 .mu.m
and 500 .mu.m. Further, the organic binder may include, but is not
limited to, a polyester resin. In the present invention, the
organic binder integrally surrounding the powder particles 10' may
be removed due to the heat during sintering. This may make it
easier to form the inside region 34 with a lower density.
[0045] In order to supply the powder particles 10, 10' onto a
predetermined area, a powder particle supplying device may
preferably be adjustable in the supplying rate of the powder
particles 10, 10', or selectable in the type of powder particles
10, 10'.
[0046] Thus, in order to manufacture a three-dimensional object 30
consisting of a plurality of integrally built-up sintered layers,
the following apparatuses may used: [0047] (f) apparatuses that
include a powder particle supplying device for supplying powder
particles at an adjustable supplying rate; a high-density energy
heat source for heating the powder particles supplied by the powder
particle supplying device; and a driving device for moving an area
onto which the powder particles are supplied by the powder particle
supplying device; and [0048] (g) apparatuses that include a powder
particle supplying device for supplying powder particles selectable
from a group of two or more different types of powder particles; a
high-density energy heat source for heating the powder particles
supplied by the powder particle supplying device; and a driving
device for moving an area onto which the powder particles are
supplied by the powder particle supplying device.
[0049] With respect to the apparatus (f), an example of the powder
particle supplying device with an adjustable supplying rate of
powder particles 10 is disclosed in Japanese Laid-Open Publication
No. 2003-302281, which is owned by the applicant of the present
invention and is hereby fully incorporated herein by reference. The
device includes an ultrasonic vibration powder supplier. Such
device enables the supplying rate of the powder particles 10 to be
finely controlled. Or otherwise, when the powder particles 10, 10'
are supplied for forming a sintered layer, the supplying rate may
be switched between a higher supplying rate of the powder particles
10 for the surface region 32 and a lower supplying rate of the
powder particles 10' for the inside region 34. Using such a device
may eliminate the necessity for a plurality of supplying devices
configured with the different supplying rates. Thus, it is possible
to manufacture the three-dimensional object 30 with reduced costs
and increased speed.
[0050] With respect to the apparatus (g), an example of the powder
particle supplying device with a selectable type of powder
particles 10, 10' is disclosed in Japanese Laid-Open Publication
No. 2002-273201, which is also owned by the applicant of the
present invention and is hereby fully incorporated herein by
reference. The device includes a plurality of supplying hoppers,
which enable the type of powder particles 10, 10' to be selectable,
if required, from a group of two or more different types of powder
particles. In the aforementioned manner, a plurality of different
types of powder particles 10, 10' may be prepared in one device so
that powder particles 10, in a smaller average particle diameter,
are selected to be supplied for forming the surface region 32,
while powder particles 10', in a larger average particle diameter,
are selected to be supplied for forming the inside region 34.
Therefore, a plurality of supplying devices may not be required to
be used according to the different types of powder particles 10,
10' to be supplied. Thus, it is possible to use one powder particle
supplying device for manufacturing the three-dimensional object 30
with reduced costs and increased speed.
[0051] In addition, the surface region 32 may be formed by a
high-density energy heat source such as a laser, while the inside
region 34 may be formed by a non-transferred plasma arc or a cold
spray technique. The cold spray technique is a spray technique in
which the powder particles are supplied with a high velocity gas
jet from a high pressure gas supply.
[0052] The driving device in the apparatuses (f) and (g) may move
either the powder supplying nozzle 12, which is provided in the
powder particle supplying device, or the work table 14, onto which
sintered layers are formed. It will of course be appreciated that
both the nozzle 12 and the table 14 may be moved. In order to move
the nozzle 12 and/or the table 14, a conventional feed mechanism or
an XY drive unit driven by linear motors and the like may be
used.
[0053] By way of example, a manufacturing system may be constructed
so that the high-density energy heat source such as a laser for the
surface region 32 may be aligned with respect to a high pressure
gas jet device such as a cold spray for the inside region 34, with
a powder particles supplying device and a workpiece-moving table
included.
[0054] As described above, according to the present invention, a
method and an apparatus are provided for manufacturing a
three-dimensional object having a smooth outer surface, without any
additional steps of removing a surface layer each time a sintered
layer is formed so as to manufacture a three-dimensional object
consisting of integrally built-up sintered layers. Such a
manufacturing method or apparatus requires less thermal energy to
heat and sinter the powder particles so as to contribute to reduced
costs and increased speed in manufacturing the three-dimensional
object. This also has the effect of saving an amount of the powder
particles otherwise consumed.
EXAMPLE
[0055] A more specific embodiment of the present invention will be
described below. In this representative embodiment, a Model PF-01
disc-type powder feeder, available from Nihon Welding Rod Co.,
Ltd., Japan, was used as the powder particle supplying device. A
Model 2012H CO.sub.2 laser having a 50C oscillator, a rated power
of 5 kW, and an argon shielding gas, available from Mitsubishi
Electric Corporation, Japan, was used as the high-density energy
heat source. Further, two types of powder particles, as shown in
Table 1, are used as the powder particles in this representative
embodiment. TABLE-US-00001 TABLE 1 Details of Powder Particles No.
Type of Powder Particles Material Average Particle Diameter 1
Spherical Powder SUS420 30 .mu.m 2 Granulated Powder SUS410L 200
.mu.m (Granulated from 10 .mu.m Powder Particles)
[0056] As shown in FIG. 2, by using the aforementioned devices, a
three-dimensional object 30 having an outside dimension of 100
mm.times.100 mm.times.100 mm was manufactured. As shown in Table 1,
with respect to the surface region 32, the powder particles of No.
1 were used. Manufacturing parameters for the surface region 32
were: a laser power of 2.8 kW; a laser spot diameter of 1.0 mm; and
a speed for moving the powder particle supplied area of 1000
mm/min. With respect to the inside region 34, the powder particles
of No. 2 shown in Table 1 were used. Manufacturing parameters for
the inside region 34 were: a laser power of 2.0 kW; a laser spot
diameter of 3.0 mm; and a speed for moving the powder particle
supplied area of 4000 mm/min. It should be noted that the laser
spot diameter for the inside region 34 was greater than that of the
surface region 32. Also, the moving speed for the inside region 34
was greater than that of the surface region 34. These parameter
settings contributed to achieving higher-speed manufacturing.
[0057] The three-dimensional object 30 obtained as above was formed
with an outside appearance with a high density. The appearance was
generally comparable to a three-dimensional object manufactured
entirely with spherical powder particles. Also, the time spent in
the manufacturing was 2.0 hours for the surface region 32, 4.8
hours for the inside region 34, and 6.8 hours in total, which was
approximately one third as long as compared to a manufacturing time
through a conventional layer-building prototyping method. Thus, it
has been found that the manufacturing method of the present
invention can achieve significantly high-speed prototyping.
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