U.S. patent application number 14/913741 was filed with the patent office on 2016-07-21 for apparatus for manufacturing three-dimensional objects.
The applicant listed for this patent is FIT AG. Invention is credited to CARL FRUTH.
Application Number | 20160207259 14/913741 |
Document ID | / |
Family ID | 51357703 |
Filed Date | 2016-07-21 |
United States Patent
Application |
20160207259 |
Kind Code |
A1 |
FRUTH; CARL |
July 21, 2016 |
APPARATUS FOR MANUFACTURING THREE-DIMENSIONAL OBJECTS
Abstract
An apparatus and a method are provided for manufacturing
three-dimensional objects by selective solidification of a build
material applied in layers. In order to improve the manufacturing
process and in particular to optimize heat input, it is proposed to
use a heating element having at least two functional openings, one
of the at least two functional openings serving as a material
passthrough and another of the at least two functional openings
serving simultaneously as a radiation passthrough.
Inventors: |
FRUTH; CARL; (PARSBERG,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FIT AG |
Parsberg |
|
DE |
|
|
Family ID: |
51357703 |
Appl. No.: |
14/913741 |
Filed: |
August 22, 2014 |
PCT Filed: |
August 22, 2014 |
PCT NO: |
PCT/EP2014/002306 |
371 Date: |
February 23, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B28B 1/001 20130101;
B33Y 30/00 20141201; B29C 64/30 20170801; B22F 2003/1056 20130101;
B28B 17/0081 20130101; B29C 64/393 20170801; B29K 2105/251
20130101; B22F 2003/1057 20130101; B33Y 50/02 20141201; Y02P 10/25
20151101; B22F 3/1055 20130101; B29C 64/295 20170801; B29C 64/364
20170801; B29C 64/40 20170801; Y02P 10/295 20151101; B33Y 10/00
20141201; B29C 64/153 20170801 |
International
Class: |
B29C 67/00 20060101
B29C067/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 23, 2013 |
DE |
10 2013 109 162.8 |
Claims
1-6. (canceled)
7. An apparatus for manufacturing three-dimensional objects by
selective solidification of a build material applied in layers, the
apparatus comprising: a build platform on which at least one
three-dimensional object is to be generated in layers, said build
platform being disposed in an X-Y plane; a heating element for
inputting thermal energy into the build material, said heating
element at least partly overlying said build platform; said heating
element having at least two simultaneously usable functional
openings formed therein, one of said at least two functional
openings being embodied as a material passthrough and another of
said at least two functional openings being embodied as a radiation
passthrough; at least one radiation source for selective
solidification of the build material by local heating; and a
plurality of drive devices for generating relative motions in at
least one of an X or a Y direction between at least two components
selected from the group consisting of said build platform, said
heating element and said at least one radiation source.
8. The apparatus according to claim 7, wherein said plurality of
drive devices includes: a first drive device for generating a
relative motion in at least one of an X or a Y direction between
said build platform and said heating element, and a second drive
device for generating a relative motion in at least one of an X or
a Y direction between said at least one radiation source and said
heating element.
9. The apparatus according to claim 7, wherein said at least one
radiation source includes at least two simultaneously operable
radiation sources and a control system for applying control to said
radiation sources to cause radiation regions of said radiation
sources to overlap.
10. The apparatus according to claim 7, wherein said functional
openings have at least one of a shape, a configuration or a size
being modifiable.
11. The apparatus according to claim 7, wherein at least one of
said heating element or said at least one radiation source has a
speed being modifiable during manufacture.
12. A method for manufacturing three-dimensional objects by
selective solidification of a build material applied in layers, the
method comprising the following steps: generating at least one
three-dimensional object in layers on a build platform disposed in
an X-Y plane; inputting thermal energy into the build material by
using a heating element at least partly overlying the build
platform; locally heating the build material for selective
solidification by using at least one radiation source; allowing the
build material and radiation energy to simultaneously pass through
at least two functional openings formed in the heating element; and
using a plurality of drive devices to generate relative motions in
at least one of an X or a Y direction between at least two
components selected from the group consisting of the build
platform, the heating element and the at least one radiation
source.
Description
[0001] The invention relates to an apparatus and a method for
manufacturing three-dimensional objects by selective solidification
of a build material applied in layers.
[0002] A large number of apparatuses and methods for manufacturing
three-dimensional objects by selective solidification of a build
material applied in layers are known from the existing art. Laser
sintering or selective mask sintering, for example, may be recited
here. Systems with which a layer manufacturing method of this kind
can be carried out are also referred to as "rapid prototyping"
systems. These layer manufacturing methods serve to manufacture
components built up in layers from solidifiable material such as
resin, plastic, metal, or ceramic, and are used, for example, to
produce engineering prototypes. Using an additive production
method, three-dimensional objects can be manufactured directly from
CAD data.
[0003] In a layer manufacturing method of this kind, the objects
are built up in layers, i.e. layers of a build material are applied
successively over one another. Before application of the respective
next layers, the locations in the respective layers which
correspond to the object to be manufactured are selectively
solidified. Solidification is accomplished, for example, by local
heating of a usually powdered layering raw material using a
radiation source. An exactly defined object structure of any kind
can be generated by controlled introduction of radiation in
suitable fashion into the desired regions. The layer thickness is
also adjustable. A method of this kind is usable in particular for
the manufacture of three-dimensional bodies by successively
generating multiple thin, individually configured layers.
[0004] The build material to be solidified is typically preheated
to a temperature that is below the processing temperature. The
processing temperature is then attained with the aid of an
additional energy input.
[0005] In a laser sintering process, for example, a plastic
material is preheated to a temperature below the sintering
temperature. The energy introduced by the laser then contributes
only the differential quantity of heat for fusing the powder
particles.
[0006] Preheating is accomplished in many cases by heating the
build platform. With this heating "from below," however, the
preheating heat flow decreases as the component height increases,
due to losses and the increasing volume of the powder charge.
[0007] Other methods also result in an undesired irregular
temperature distribution in the build material. This also applies
in particular to those methods in which preheating is accomplished
by heat delivery "from above." Here devices that can be
intermittently heated are placed above the build layer. Complex
systems for controlling the heat curve, and other laborious
actions, are used in an attempt to achieve a uniform temperature
distribution in the build material to be preheated.
[0008] An object of the present invention is to improve the
manufacturing process, in particular to optimize heat input.
[0009] This object is achieved respectively by an apparatus
according to Claim 1 and by a method according to Claim 10.
Advantageous embodiments of the invention are indicated in the
dependent claims. The advantages and configurations explained below
in connection with the apparatus also apply analogously to the
method according to the present invention, and vice versa.
[0010] The invention proposes no longer pursuing the cycle-timed
manufacturing procedure known from the existing art, in which,
within one clock cycle, after an application of material firstly a
preheating action and then a selective solidification action occur
before another material application is performed in a subsequent
new clock cycle. The invention instead proposes a continuous
manufacturing process in which application of the build material,
preheating, and selective solidification occur simultaneously by
local heating of the build material, specifically at different
sites on the same objects to be manufactured or also on different
objects simultaneously if multiple objects are being manufactured
on the build platform.
[0011] The apparatus according to the present invention encompasses
a build platform, arranged in an X-Y plane, on which at least one
three-dimensional object is generated in layers; a heating element,
at least partly overlying the build platform, for inputting thermal
energy into the build material; and at least one radiation source
for selective solidification of build material by local heating.
The heating element comprises at least two simultaneously usable
functional openings, one of the at least two functional openings
being embodied as a material passthrough and another of the at
least two functional openings being embodied as a radiation
passthrough. According to the present invention the apparatus
encompasses a number of drive devices for generating mutually
independently controllable relative motions in an X and/or Y
direction between at least two of the three following components of
the apparatus: the build platform, the heating element, the at
least one radiation source.
[0012] The method according to the present invention
correspondingly encompasses the steps of: generating the at least
one three-dimensional object, in layers, on a build platform
arranged in an X-Y plane; inputting thermal energy into the build
material with the aid of a heating element at least partly
overlying the build platform; locally heating build material using
a radiation source, for the purpose of selective solidification;
and simultaneously causing build material and radiation energy to
pass through the heating element using at least two functional
openings. According to the present invention the method encompasses
generating, by means of a number of drive devices, mutually
independently controllable relative motions in an X and/or Y
direction between at least two of the three following components of
the apparatus: the build platform, the heating element, the at
least one radiation source.
[0013] A fundamental idea of the invention is the use of a heating
element that serves to preheat the build material and is notable
for functional openings that serve as a material passthrough and
radiation passthrough, therefore as a coating opening for the
application of build material and as an exposure opening for local
heating of the build material. When a heating element of this kind
is moved in suitable fashion relative to the build platform, the
application of build material, preheating, and selective
solidification can occur simultaneously, i.e. non-cycle-timed,
uninterrupted manufacture of the at least one object. In other
words, the object or objects is built up continuously, the build
rate being determined by the relative motion between the build
platform and heating element. The geometric arrangement of the
object regions located in the various manufacturing process phases,
in particular the spacing of said object regions from one another,
is determined by the arrangement of the functional openings in the
heating element, in particular by the spacing of said functional
openings from one another.
[0014] For example, in a first object region the build material in
the form of a freshly applied powder charge is being preheated by
the heating element, while in a second object region arranged
behind the first object region in the motion direction, a layer n
is currently being solidified with the aid of radiation energy
penetrating through an exposure opening. At the same time, in a
third object region that is located behind the second object region
in the motion direction, post-heating of the build layer n, just
previously solidified there, is being performed by the heating
element, while in a fourth object region located behind the third
object region, further build material for a subsequent layer n+1,
introduced through a coating opening, is being applied onto the
layer n that is already present. The object regions can be regions
of one object or regions of different objects if multiple objects
are arranged on the build platform.
[0015] Heat delivery for preheating is accomplished "from above,"
so that the disadvantages of heat delivery via the build platform
do not occur. At the same time, heat delivery is preferably
accomplished not only intermittently, i.e. not only when the
heating element is located (as in the existing art) above the build
layer for a short time, but instead constantly, this being made
possible by the novel continuous working mode. Optimization of heat
input is thereby achieved in simple fashion. At the same time, the
manufacturing process as a whole is improved.
[0016] Thanks to the generation of multiple relative motions
between the participating components (build platform, heating
element, and radiation source), the time-related effects of the
various process conditions in the respective method steps can be
optimized and coordinated with one another in a simple and very
flexible manner. The manufacturing process as a whole is thereby
further improved.
[0017] A decoupling of the motion of the radiation passthrough from
the motion of the radiation source has proven to be particularly
advantageous. In other words, the radiation source can move, over
the build platform or over the build material present thereon, at a
different speed from the heating element.
[0018] In particular when the introduction of radiation energy
occurs through the exposure opening in the absence of complete
illumination of that opening but when instead a controlled
irradiation of the build material arranged beneath that opening
occurs within the boundaries of that opening, for example in such a
way that a laser heats the build material along a defined
trajectory, according to the present invention the radiation source
can move, independently of the motion of the heating element and
thus independently of the motion of the exposure opening, in the
opening region furnished by the radiation passthrough, in such a
way that the radiation power can be introduced particularly
efficiently.
[0019] In a preferred embodiment of the invention this is brought
about by the fact that the apparatus comprises, besides a first
drive device for generating a first relative motion in an X and/or
Y direction between the build platform and the heating element, a
second drive device for generating a second relative motion in an X
and/or Y direction, independent of the first relative motion,
between the radiation source and the heating element.
[0020] For further optimization of the process, especially for
particularly efficient introduction of the radiation power, the
shape, arrangement, and/or size of the exposure openings, in
particular the slit width in the principal motion direction, for
example the X direction, can be adaptable to the respective process
or can also be varied during the manufacturing process. What can be
achieved thereby is, for example, that the region respectively
located directly beneath an illumination opening and not heated by
the heating element is as small as possible. For further
optimization, the speed of individual components, in particular the
speed of the heating element and thus of the exposure openings,
and/or the speed of the radiation source(s), can be varied during
the manufacturing process, in particular can be mutually
coordinated.
[0021] At the same time, the present invention allows elimination
of the need for a uniform temperature distribution. Because the
manufacturing method has made different degrees of progress at
different sites, different temperatures at different sites can be
advantageous. For example, in one region a preheating temperature
can be advantageous in order to prepare the build material for
imminent local heating; in an adjacent region, on the other hand, a
post-heating temperature can be present, as is advantageous for
achieving certain properties of the already solidified layer, for
example in order to prevent warping.
[0022] Because the heating element is constantly available, a
defined inhomogeneous temperature distribution of this kind can be
implemented in particularly simple fashion. In an advantageous
embodiment of the invention, the heating element comprises multiple
regions capable of different temperature control. This is achieved,
for example, with the aid of multiple mutually independently
operable heating modules.
[0023] An additional heat source for furnishing thermal energy can
also be provided, in particular in the form of a radiation source
arranged above the heating element. In this case at least one of
the functional openings is embodied as a heating opening for
additional input of thermal energy. The heating opening can be a
functional opening that already performs another function; for
example, a radiation passthrough already serving as an exposure
opening can serve at the same time as a heating opening.
[0024] An embodiment of the invention in which the heating element
is of substantially plate-shaped configuration has proven to be
particularly advantageous for the transfer of heating energy to the
build material. The plate-like shape of the heating element
simultaneously makes possible a particularly simple embodiment of
the functional openings. Advantageously, the heating element and
build platform are embodied in such a way that they overlie one
another over the largest possible area, preferably completely, or
can be caused during the manufacturing process to overlie one
another over as large an area as possible, preferably
completely.
[0025] In a preferred embodiment of the invention the heating
element is arranged above the build platform. In a variant, the
heating element is spaced away from the respectively topmost build
layer. Heating is accomplished by thermal radiation. In an
alternative variant, the heating element touches the topmost build
layer. Heating is then accomplished by thermal conduction.
[0026] If the build platform is located inside a process chamber
that is closed in the operating state, the heating element can then
serve as a demarcating wall of the process chamber. In other words,
in this case the process chamber is closed off by the heating
element. The heating element is then a part of the process
chamber.
[0027] The coating opening is always an actual opening in the sense
of a material perforation. For the exposure opening, however, the
heating element need not necessarily be perforated. The exposure
opening can also be embodied as a region of suitable material, in
the basic body of the heating element, that is suitable for the
passage of radiation.
[0028] In a preferred embodiment of the invention radiation energy
is introduced through the exposure opening but said opening is not
completely illuminated. Instead, a targeted irradiation of the
build material arranged below said opening occurs, within the
boundaries of said opening. The radiation can derive from one or
more radiation sources. For example, for local heating of the build
material one or more laser beams can execute a linear
back-and-forth motion inside the functional opening within the
window furnished by the functional opening, or the laser beams are
guided in defined fashion inside the window on a nonlinear
trajectory, in each case as a function of the structure to be
generated. The radiation is guided with the aid of a suitable
control system. The build material, previously preheated to a
temperature below the processing temperature, becomes locally
further heated. The processing temperature is reached with the aid
of this additional energy input.
[0029] In a particularly advantageous embodiment of the invention
at least two radiation sources whose radiation is simultaneously
incident, through a shared exposure opening, onto a region of the
build layer located therebeneath and uncovered by said exposure
opening, are used for energy input. Thanks to the simultaneous use
of multiple radiation sources, the radiation energy can be
introduced particularly efficiently. At the same time, as
described, this makes possible a further optimization of energy
delivery.
[0030] In a particularly advantageous embodiment of the invention
provision is made that each radiation source has associated with it
a region of the build layer to be irradiated by it, hereinafter
referred to as a "target region." Adjacent target regions overlap
at least in part, forming an overlap region.
[0031] In other words, the at least two simultaneously operated
radiation sources have control applied to them, in particular are
moved in an X and/or Y direction, in such a way that they (also)
introduce radiation energy into at least one shared area, i.e. one
irradiated by the at least two radiation sources, of the build
layer (the overlap region). The at least two radiation sources
irradiate the overlap region either simultaneously or
successively.
[0032] Control is preferably applied to the at least two radiation
sources in such a way that the manner in which the radiation
regions overlap yields a minimal total processing duration for the
build material; more precisely, that the time span required for
introduction of the energy necessary for solidification of the
build material is minimal. The total manufacturing time span for
the three-dimensional objects is thereby shortened. Preferably
control is at the same time applied in such a way that the
operating times of the individual radiation sources are
minimized.
[0033] To minimize the processing duration, in a preferred
embodiment of the invention the areas to be exposed (the target
regions) are firstly subdivided into individual sub-regions,
hereinafter referred to as "surface segments," or such surface
segments are selected from the respective target region and in that
manner are distinguished from sub-regions that do not need to be
exposed. The region simultaneously capable of irradiation by
multiple radiation sources and predefined by way of the shape and
size of the illumination opening is segmented, for example, in an X
and a Y direction.
[0034] The necessary dwell time of the individual radiation sources
in the respective surface segment is then calculated. Lastly a
suitable (preferably the fastest) exposure strategy is identified:
the paths that the individual radiation sources describe within the
window furnished by the radiation passthrough are identified.
Energy input is accomplished, for example, by the fact that a laser
beam performs a line-by-line scan or sweep over the relevant
surface region, for example forming closely adjacent straight
hatching lines, in order to solidify a region of the build layer.
This exposure pattern can vary from one layer to another.
[0035] Preferably, not only is the exposure strategy for a specific
segmentation identified from the standpoint of time-related
optimization of the manufacturing process, but the segmentation
itself is also carried out in such a way that subsequent exposure
can be accomplished particularly efficiently. For example,
segmentation is accomplished in consideration of the location of
the motion axes of the radiation sources.
[0036] The apparatus according to the present invention for
manufacturing three-dimensional objects encompasses suitable means
for segmenting, for calculating the dwell time, and for identifying
the exposure strategy, or is connected to such means or contains
corresponding information, in particular control data for applying
control to the number of radiation sources for implementing the
identified exposure strategy, from an external data source.
[0037] The control data used to control the apparatus according to
the present invention encompass a data model for describing the
objects to be manufactured, or are generated with the use of such a
data model. The data model describes not only the division of each
object into build layers, but also the location of the objects on
the build platform.
[0038] With the aid of the present invention it is possible for the
data model on which manufacture of the three-dimensional objects is
based to be optimized in such a way that the arrangement of the
objects on the build platform, or the location of the objects with
respect to one another, is selected so that particularly efficient
manufacture, especially particularly rapid manufacture, occurs in
consideration of the exposure strategy. In a particularly
advantageous embodiment of the invention what occurs is therefore
not only an optimum selection of the respective individual exposure
strategy for each build layer, in particular a time-related
optimization of the radiation input, but also, even before that, an
optimization, in consideration of the method according to the
present invention, of the arrangement on the build platform of the
objects to be manufactured.
[0039] In a simple variant of the invention the arrangement and
size of the functional openings is unmodifiable. It has proven
advantageous, for example, to use strip-shaped functional openings
that lie parallel to one another. The functional openings are
advantageously arranged in the heating element perpendicularly to
the direction of relative motion, for example perpendicularly to
the X direction or Y direction. Alternatively, it is possible for
the functional openings to be arranged obliquely, i.e. at an angle
to the motion direction. It is advantageous in the context of the
present invention that the shape, arrangement, and size of the
functional openings can be adapted to the special aspects of the
method. Instead of strip- or slit-shaped functional openings, for
example, orifice-shaped functional openings or functional openings
of any other shape can also be provided for for all or for
individual functions.
[0040] In an advantageous embodiment of the invention the shape,
arrangement, and/or size of the functional openings is modifiable.
For example, it can be advantageous to embody the size of the
exposure opening modifiably, in particular when said functional
opening serves as an aperture stop, i.e. serves to demarcate the
cross section of the introduced radiation. It can likewise be
advantageous to embody the size of the coating opening modifiably,
in particular when the shape and/or size of said opening directly
determine the application location or volume of build material
applied for each unit time. A modification of the functional
openings can also be accomplished in particular during runtime,
i.e. while the manufacturing process is in progress. Additional
suitable drive and control devices are then to be provided for this
as applicable.
[0041] It is not only heat input into the build material that is
improved with the present invention. In addition, thanks to a
suitable interaction of the arrangement and size of the functional
openings and the relative motion between the heating element and
build platform, and the manner in which radiation for local
solidification of the build material is furnished and/or guided,
the manufacturing process can also be carried out particularly
efficiently.
[0042] This purpose is served by a central control system for the
manufacturing process using a data model for description of the
object to be manufactured with the aid of the layer building
method. The control system encompasses all relevant operations of
the manufacturing process that proceeds simultaneously at multiple
sites in different manufacturing phases, i.e. manufacturing
processes that have made different degrees of progress. In other
words, control always occurs in accordance with the actual progress
of the manufacturing process, using for this purpose sensor data of
suitable sensors, in particular temperature sensors. The control
system encompasses in particular control of the heating of the
heating element, here optionally the defined control of individual
temperature regions. The control system also encompasses control of
the drive devices for the relative motions between the heating
element, the build platform, and/or the radiation source(s), i.e.
also control of the guided radiation sources(s) for local heating
of the build material, and control of the furnishing and/or
application device for furnishing and/or applying the build
material and, if applicable, control of the additional radiation
source for controlling the temperature of the build material, as
well as also, if applicable, control of the functional openings of
modifiable arrangement and/or size.
[0043] All calculation operations necessary in connection with
control of the layer manufacturing system and with execution of the
method according to the present invention are performed by one or
more data processing units that are embodied for carrying out said
operations. Each of these data processing units preferably has a
number of functional modules, each functional module being embodied
to carry out a specific function or a number of specific functions
in accordance with the method described. The functional modules can
be hardware modules or software modules. In other words, insofar as
it relates to the data processing unit the invention can be
realized either in the form of computer hardware or in the form of
computer software, or in a combination of hardware and software. If
the invention is realized in the form of software, i.e. as a
computer program product, all the functions described are
implemented by computer program instructions when the computer
program is executed on a computer having a processor. The computer
program instructions are realized in any programming language in a
manner that is known per se, and can be furnished to the computer
in any form, for example in the form of data packets that are
transferred via a computer network, or in the form of a computer
program product stored in a diskette, a CD-ROM, or another data
medium.
[0044] An exemplifying embodiment of the invention will be
described in further detail below with reference to the drawings,
in which:
[0045] FIG. 1 schematically depicts an apparatus according to the
present invention having a highly simplified process chamber
depicted in section;
[0046] FIG. 2 is a schematic plan view of a heating element
arranged above a build platform;
[0047] FIG. 3 shows simplified sectioned depictions of layers of
the object to be built up, in different manufacturing phases;
[0048] FIG. 4 shows an embodiment of the invention having two
radiation sources.
[0049] All the Figures show the invention not to scale, merely
schematically, and only with its essential constituents. Identical
reference characters correspond to elements having an identical or
comparable function.
[0050] An apparatus 1 for laser sintering is described by way of
example on the basis of FIGS. 1 and 2, as an apparatus for
manufacturing at least one three-dimensional object by selective
solidification of a build material applied in layers. The invention
is not, however, limited to this specific method. The invention is
also applicable to other additive production methods, for example
laser melting, mask sintering, drop on powder/drop on bed,
stereolithography, and the like.
[0051] An orthogonal coordinate system (X, Y, Z) is utilized in the
description of the invention.
[0052] Apparatus 1 for laser sintering encompasses a build platform
2, arranged in an X-Y plane, on which a three-dimensional object 3
is generated in layers in known fashion. Build material 4 is a
suitable plastic powder. After production of a layer n, in order to
produce a new layer n+1 the build platform 2 having the already
created and hardened layers is displaced downward over a specific
travel length. This purpose is served by a drive device 5 for
generating a relative motion in a Z direction, i.e. perpendicularly
to the build plane, between build platform 3 and a heating element
6 described later in further detail. This motion in a Z direction
is indicated in FIG. 1 by arrow 33. Drive device 5 is, for example,
an electric motor.
[0053] Between solidification of a layer n and application of new
build material 4 for a subsequent layer n+1, provision can be made
to remove excess build material 4 from build platform 2. In this
case a device suitable for this (not illustrated) is provided, for
example in the form of a wiping blade or the like, which
advantageously is connected to or interacts with heating element
6.
[0054] Apparatus 1 encompasses at least one radiation source 7 that
furnishes radiation energy for local heating of build material 4 in
order to selectively solidify the latter. The at least one
radiation source 7 is, for example, a laser that delivers a laser
beam 8 in guided fashion.
[0055] Apparatus 1 furthermore encompasses at least one furnishing
and/or application device 9 with which build material 4 is
furnished and/or is applied onto build platform 2 or onto a build
layer that is already present. Furnishing and/or application device
9 is, for example, a device for applying a powder charge.
Furnishing and/or application device 9 is connected to a
corresponding control system 10 that controls the application of
material.
[0056] Apparatus 1 further encompasses heating element 6 (already
mentioned above) for introducing thermal energy into build material
4, which element constantly at least partly overlies build platform
2 during the manufacturing process. Heating element 6 is of
substantially plate-like configuration. It is arranged above build
platform 2, being spaced away from the respectively topmost build
layer. The spacing is typically between 100 .mu.m and 10 mm.
Heating of build material 4 is accomplished by thermal radiation 11
delivered by heating element 6, as depicted symbolically in FIGS. 1
and 3.
[0057] Build platform 2 is located inside a process chamber 12,
closed in the operating state, that is merely schematically
indicated in FIG. 1. Heating element 6 serves here as a demarcation
wall of process chamber 12. More precisely, heating element 6 is
embodied as part of upper cover 13 of process chamber 12.
[0058] Apparatus 1 further encompasses a drive device 15 for
generating a relative motion between build platform 2 and heating
element 6 in an X and/or Y direction, i.e. in a layer direction.
This motion in an X and/or Y direction is indicated in FIG. 1 by
arrow 34. Drive device 15 is, for example, an electric motor. The
two drive devices 5, 15 are connected to corresponding drive
control systems 16, 17.
[0059] In the exemplifying embodiment described here, drive device
15 moves build platform 2 relative to the stationary heating
element 6. The principal motion direction is the X direction. In
the simplest case, the motion of build platform 2 is limited to
this principal motion direction. If necessary or advantageous for
the manufacturing process, the motion in an X direction can be
overlaid by a motion of build platform 2 in a Y direction.
[0060] Heating element 6 comprises at least two, in the example
depicted in FIG. 1 three simultaneously usable functional openings
18, 19, 20 spaced apart from one another. Functional openings 18,
19, 20 are slit- or strip-shaped, elongatedly rectangular, and lie
parallel to one another and perpendicular to the principal motion
direction, here the X direction. One of the functional openings is
embodied as a material passthrough 18 and another of the functional
openings as a radiation passthrough 19. During the production of
object 3, both build material 4 and radiation energy, here in the
form of laser beam 8, are allowed to pass simultaneously through
functional openings 18, 19.
[0061] Expressed differently, the one functional opening is
embodied as a coating opening 18 for the application of build
material 4 onto build platform 2 or onto a build layer that is
already present, and the other functional opening is embodied as an
exposure opening 19 for simultaneous introduction of radiation
energy of the at least one radiation source 7 into the applied
build material 4 in order to solidify build material 4.
[0062] Radiation energy for local heating of build material 4 is
introduced by guiding laser beam 8 through exposure opening 19 on a
defined path. Laser beam 8 is guided with the aid of a suitable
drive and control device 21. In other words, not only is first
drive device 15 used to generate a relative motion in an X and/or Y
direction between build platform 2 and heating element 6, but a
second drive device 21 is also used to generate a second relative
motion in an X and/or Y direction, independent of said first
relative motion, between radiation source 7 and heating element 6.
In the example illustrated, second drive device 21 serves to move
radiation source 7. This motion of radiation source 7 in an X
and/or Y direction is indicated in FIG. 1 by arrow 35.
[0063] Instead of a stationary heating element 6 having a build
platform and radiation source 7 that are movable with respect
thereto, in alternative embodiments (not illustrated) the build
platform can also be stationary in the X-Y plane; in this case
heating shield 6 and radiation source 7 are embodied movably with
respect to one another. Alternatively, a stationary radiation
source 7 can be combined with a moving heating element 6 and a
moving build platform 2 in order to furnish the two desired
relative motions.
[0064] Heating element 6 comprises multiple heating modules 23, to
which control can be applied mutually independently and which are
arranged between or next to functional openings 18, 19, 20. All the
heating modules 23 of heating element 6 are connected to a heating
control system 24. The working principle of heating modules 23 is
based, for example, on the principle of electrical induction. Other
suitable functioning modes for the heating modules are likewise
possible.
[0065] In the example illustrated in FIG. 1, apparatus 1 also
encompasses an additional heat source in the form of a radiation
source 25, arranged above heating element 6, for furnishing thermal
energy. This additional radiation source 25 is, for example, an
infrared radiator that delivers infrared radiation 26. A suitable
control system 27 is provided for this radiation source as well.
This additional radiation source 25 has associated with it a
dedicated functional opening 20 that thus serves as a heating
opening.
[0066] A central control system 28 is responsible for controlled
execution of the manufacturing method. Control system 28
encompasses for this purpose all the relevant control sub-systems
10, 16, 17, 21, 24, 27.
[0067] Various phases of manufacture will be described below with
reference to FIG. 3. What is used here is a heating element 6',
different from heating element 6 shown in FIGS. 1 and 2, that
possesses three functional openings, namely two coating openings
18, 18' and one exposure opening 19 arranged between coating
openings 18, 18'.
[0068] In FIG. 3a, build platform 2, driven by drive device 15,
moves through in an X direction beneath first coating opening 18 of
heating element 6. Build material 4 for a layer n becomes deposited
onto build platform 2.
[0069] In FIG. 3b, build platform 2 moves farther in an X
direction. Build material 4 that was applied shortly beforehand
becomes preheated, by a heating module 23 arranged between first
coating opening 18 and exposure opening 19 in the basic body of
heating element 6, to a temperature below the sintering
temperature. At the same time, in an adjacent object region
preheated just previously, additional thermal energy is introduced
with the aid of laser beam 8 through exposure opening 19, with the
result that the powder particles fuse.
[0070] In FIG. 3c, build platform 2 moves farther in an X
direction. Before build platform 2 reaches second coating opening
18', it is moved a requisite travel distance downward in the Z
direction, driven by drive device 5. Build material 4 for a further
layer n+1 is applied through second coating opening 18'. This
object region had just previously been heated again by a further
heating module 23' arranged between exposure opening 19 and second
coating opening 18'.
[0071] In FIG. 3d, build platform 2 has reached its one reversal
point. Layers n and n+1 have been generated. Because there is no
longer an exposure opening 19 located above build platform 2, at
this moment laser irradiation is no longer taking place. The
application of build material 4 also occurs only as long as at
least one of the two coating openings 18, 18' is arranged above
build platform 2.
[0072] In FIG. 3e, build platform 2 moves through beneath heating
element 6 in an X direction, oppositely to the first motion. With
the aid of second coating opening 18', a new application of
material for the next layer n+2 has already occurred, as has
preheating with the aid of a third heating module 23''. Build
platform 2, driven by drive device 5, has previously been moved
down again a necessary distance in the Z direction. A local
irradiation with laser beam 8 occurs through exposure opening 19 in
order to solidify the structure to be generated. First heating
module 23 serves for post-heating. Upon a further motion of build
platform 2, an application of material for layer n+3 will occur
shortly through first coating opening 18.
[0073] FIG. 4 illustrates an exemplifying embodiment in which
radiation 8 from two simultaneously operated radiation sources 7,
14 is incident, through a shared exposure opening 19, onto a build
layer 3 uncovered by that exposure opening 19. For reasons of
clarity, heating element 6 is depicted as transparent; in addition,
only a single functional opening (exposure opening 19) is
illustrated. Each radiation source 7, 14 has a target region 29, 30
associated with it, this association being depicted symbolically
with dashed auxiliary lines. The two target regions 29, 30
intersect one another forming an overlap region 31. Control is
applied to the at least two radiation sources 7, 14, which again
can be lasers, by way of a correspondingly embodied drive and
control device 21, so as to result in a minimum total processing
duration for the build material. In order to bring about an optimum
exposure structure, each radiation source 7, 14 moves on a defined
path 32 in an X and/or Y direction, as indicated for radiation
source 14 in FIG. 4.
[0074] In summary, the invention relates to an apparatus 1 for
manufacturing three-dimensional objects 3 by selective
solidification of a build material 4 applied in layers, having a
build platform 2, arranged in an X-Y plane, on which at least one
three-dimensional object 3 is generated in layers; having a heating
element 6, at least partly overlying the build platform 2, for
inputting thermal energy 11 into the build material 4; having at
least one radiation source for selective solidification of build
material by local heating, heating element 6 having at least two
simultaneously usable functional openings 18, 19, one of the at
least two functional openings being embodied as a material
passthrough 18 and another of the at least two functional openings
being embodied as a radiation passthrough 19. According to the
present invention this apparatus 1 encompasses a number of drive
devices 15, 21 for generating mutually independent relative motions
in an X and/or Y direction between at least two of the three
following components: build platform 2, heating element 6, the at
least one radiation source 7, 14.
[0075] Advantageously, apparatus 1 encompasses a first drive device
15 for generating a relative motion in an X and/or Y direction
between build platform 2 and heating element 6, and a second drive
device 21 for generating a relative motion in an X and/or Y
direction between the at least one radiation source 7, 14 and
heating element 6. Advantageously, apparatus 1 encompasses at least
two simultaneously operable radiation sources 7, 14 and a control
system 21 for applying control to said radiation sources 7, 14 in
such a way that their radiation regions 29, 30 overlap.
[0076] Advantageously, heating element 6 constantly at least partly
overlies build platform 2. Advantageously, heating element 6 and
build platform 2 can be caused to overlie one another completely.
Advantageously, heating element 6 is of substantially plate-shaped
configuration. Advantageously, heating element 6 is arranged above
build platform 2; it either is spaced away from the topmost build
layer or touches the topmost build layer. Advantageously, build
platform 2 is located inside a process chamber 12 that is closed in
the operating state, and heating element 6 serves as a demarcating
wall of process chamber 12. Advantageously, heating element 6
comprises regions capable of different temperature control.
Advantageously, the shape, arrangement, and/or size of functional
openings 18, 19, 20 are modifiable. Advantageously, the speed of
heating element 6 and/or the speed of the at least one radiation
source 7, 14 is modifiable during the manufacturing process.
[0077] The invention furthermore relates to a method for
manufacturing three-dimensional objects 3 by selective
solidification of a build material 4 applied in layers, at least
one three-dimensional object 3 being generated, in layers, on a
build platform 2 arranged in an X-Y plane; a heating element 6 that
at least partly overlies build platform 2 inputting thermal energy
11 into the build material 4; at least one radiation source locally
heating build material for selective solidification; and heating
element 6, using at least two functional openings 18, 19, 20,
allowing build material 4 and radiation energy 8 to pass through
simultaneously. The method encompasses generating mutually
independent relative motions in an X and/or Y direction, by means
of a number of drive devices 15, 21, between at least two of the
three following components: build platform 2, heating element 6,
the at least one radiation source 7, 14.
[0078] All features presented in the specification, in the claims
below, and in the drawings can be essential to the invention both
individually and in any combination with one another.
LIST OF REFERENCE CHARACTERS
[0079] 1 Apparatus for laser sintering [0080] 2 Build platform
[0081] 3 Object, build layer [0082] 4 Build material [0083] 5 Drive
direction (Z) [0084] 6 Heating element [0085] 7 Radiation source,
laser [0086] 8 Laser beam [0087] 9 Furnishing/application device
[0088] 10 Control system for material application [0089] 11 Thermal
radiation [0090] 12 Process chamber [0091] 13 Cover [0092] 14
Radiation source, laser [0093] 15 Drive device (X/Y) [0094] 16
Drive control system (Z) [0095] 17 Drive control system (X/Y)
[0096] 18 Functional opening, material passthrough, coating opening
[0097] 19 Functional opening, radiation passthrough, exposure
opening [0098] 20 Functional opening, heating opening [0099] 21
Drive and control device for laser [0100] 22 (unassigned) [0101] 23
Heating module [0102] 24 Heating control system [0103] 25 Radiation
source, IR radiator [0104] 26 Infrared radiation [0105] 27 Control
system for additional heating [0106] 28 Central control system
[0107] 29 First target region [0108] 30 Second target region [0109]
31 Overlap region [0110] 32 Motion path [0111] 33 Motion of heating
element in Z direction [0112] 34 Motion of heating element in X
and/or Y direction [0113] 35 Motion of radiation source in X and/or
Y direction
* * * * *