U.S. patent application number 16/038913 was filed with the patent office on 2018-11-15 for device for producing three-dimensional models with special building platforms and drive systems.
The applicant listed for this patent is VOXELJET AG. Invention is credited to Ingo Ederer, Andreas Dominik Hartmann.
Application Number | 20180326654 16/038913 |
Document ID | / |
Family ID | 48698851 |
Filed Date | 2018-11-15 |
United States Patent
Application |
20180326654 |
Kind Code |
A1 |
Ederer; Ingo ; et
al. |
November 15, 2018 |
DEVICE FOR PRODUCING THREE-DIMENSIONAL MODELS WITH SPECIAL BUILDING
PLATFORMS AND DRIVE SYSTEMS
Abstract
The invention relates to a device for producing
three-dimensional models in a continuous process, comprising a
build surface which has a first end in the direction of movement
and a second end in the direction of movement, at least one dosing
device and at least one solidification unit, characterized in that
the build surface is designed to transport heavy components, and
the components are transportable over the build surface essentially
without distortion, and also comprising a method therefor.
Inventors: |
Ederer; Ingo; (Geltendorf,
DE) ; Hartmann; Andreas Dominik; (Stadtbergen,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VOXELJET AG |
Friedberg |
|
DE |
|
|
Family ID: |
48698851 |
Appl. No.: |
16/038913 |
Filed: |
July 18, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14400957 |
Mar 13, 2015 |
10059062 |
|
|
PCT/DE2013/000271 |
May 17, 2013 |
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16038913 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22F 2003/1056 20130101;
B29C 64/176 20170801; Y02P 10/295 20151101; B29C 64/153 20170801;
B29K 2105/251 20130101; B29C 64/40 20170801; B29K 2103/00 20130101;
B29C 64/141 20170801; B33Y 30/00 20141201; B33Y 10/00 20141201;
Y02P 10/25 20151101 |
International
Class: |
B29C 64/141 20170101
B29C064/141; B29C 64/40 20170101 B29C064/40; B29C 64/153 20170101
B29C064/153 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2012 |
DE |
10 2012 010 272.0 |
Claims
1-16. (canceled)
17. A method for producing three-dimensional models in a continuous
process, comprising the steps: a) building the model in layers on a
building platform in a first position, a first layer being applied;
b) transferring the model from the first position to a second
position by feeding after the first layer is built, the building
platform, which has a first front end and a second rear end, being
transported with the model; c) building a further layer on the
model on the platform; d) transferring the model on the building
platform to another position; and repeating steps a) through
d).
18. A method for producing three-dimensional models according to
claim 17, characterized in that the model on the building platform
is transferred from the first position to the second position
without distortion.
19. A method for producing three-dimensional models according to
claim 17, characterized in that the building platform with the
model is evenly transferred from the first position to the second
position and any further position essentially without deviations in
feed between the first and second ends of the building
platform.
20. The method for producing three-dimensional models according to
claim 19, characterized in that the deviation in feed between the
first front end and the second rear end of the building platform
from the first position to the second position and any further
position is less than 0.1 mm.
21. The method of claim 17, wherein the step of transferring is
carried out with the aid of a step conveyor.
22. The method of claim 17, wherein the step conveyor has lifting
and thrusting grates.
23. The method of claim 20, wherein the deviation in feed between
the first and second ends of the building platform from the first
position to the second position and any further position is less
than 0.03 mm.
24. The method of claim 19, wherein the build platform is
transported on a conveyor, and the building of the model is on a
build surface that is above a portion of the conveyor.
25. The method of claim 24, wherein the conveyor is a horizontal
surface.
26. The method of claim 17, wherein the build platform moves in a
linear direction.
27. The method of claim 17, wherein the build platform moves in a
circular direction around a vertical axis.
28. The method of claim 17, wherein the first layer is applied with
a doing unit and is selectively solidified using a solidification
unit.
29. The method of claim 28, wherein the build platform is moved by
the action of a drive component.
30. The method of claim 29, wherein the drive component includes a
first support and a second support, wherein the first support moves
from a first location to a second location while supporting the
build platform, and the first support returns to the first location
while the second support is supporting the build platform.
31. The method of claim 17, wherein the build platform includes a
link conveyor.
32. A method for producing three-dimensional models in a continuous
process, comprising steps of: i) applying a layer of a particulate
material to a particulate material feedstock using a dosing unit,
while the particulate material feedstock is on a build surface
supported by one or more supports; ii) selectively solidifying the
layer using a solidification unit; iii) advancing the build surface
for the addition of another layer of the particulate material by
moving a one or more first supports from a first position to a
second position while the build surface is supported by the one or
more first supports and then returning the one or more first
supports to the first position while the build surface is supported
by one or more second supports; and iv) repeating steps i), ii),
and iii) until the three-dimensional model is completed.
33. The method of claim 32, wherein the one or more supports
include the one or more first supports, the one or more second
supports, or both.
34. The method of claim 33, wherein the method includes
continuously building one three-dimensional model and then building
another three-dimensional model.
35. The method of claim 34, wherein the three-dimensional models
are different.
36. The method of claim 33, wherein the build surface is a portion
of a conveyor belt.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a system for the continuous
production of three-dimensional models on a horizontal transport
device, using a layering technique.
PRIOR ART
[0002] In layering methods used today for producing
three-dimensional objects based on computer data, methods are used
in which a platform (building platform), which is movable at least
in the vertical direction and which, if necessary, is surrounded by
a container and thus forms a job box, is placed in an uppermost
position at the beginning of the process. A build material, for
example a substance in the form of particulate material in the case
of 3D printing or laser sintering, is then applied in a thin layer
over the entire area of this platform. In another step, the
material is selectively bound with the aid of a physical or
chemical solidification mechanism according to the desired
component shape. This binding step may take place, for example,
using adhesives, which may be printed with the aid of ink jet
techniques. The platform is then lowered by one layer thickness,
and a new layer of particulate material is applied.
[0003] These steps are repeated until the desired body is built,
i.e., all necessary layers have been applied and solidified. The
container is successively filled with particulate material during
these steps, parts thereof being bound to the desired structural
body, while the rest remains loose and is used during the building
process as a support medium for overhanging parts of the object to
be built.
[0004] After completing the layering process, following a waiting
period which may be necessary, the loose particulate material may
be extracted or removed in another manner and the desired object
discharged.
[0005] It is possible in this case to produce components
continuously using an endless, horizontal layer feed.
[0006] In conventional systems for building models in layers, the
components are produced vertically in layers from top to
bottom.
[0007] When the maximum build height of a system is reached, the
building process must be stopped in order to subsequently remove
the components in the system and thereby create space for a
building process, or another build frame must be inserted with the
aid of a changing system in order to be able to thereby start a new
building process. As a result, the construction of components is
limited with respect to size and productivity.
[0008] In the known "continuous 3D printing" method, the layer feed
takes place in the horizontal direction, e.g., on a continuous
conveyor belt.
[0009] Gravity prevents a layer to be applied perpendicularly to
the layer feed, which is why the individual layers are applied at
an angle. The angle is selected in such a way that it is smaller
than the specific angle of repose of the corresponding particulate
material.
[0010] The layering process is followed by an enclosed conveyor
line, whose length is adapted to the method-dependent hardening
duration. At the end of the conveyor line, the finished components
enter a removal area. There, the components are freed of unbound
particle material and removed without having to interrupt the
production of additional parts.
[0011] In the continuous method, different tools and methods may be
used to feed the components, for example continuous conveyor belts
are used.
[0012] Continuous conveyor belts are generally closed belts made of
a flexible material (e.g., woven fabric) that is looped around a
drum at each end to reverse the direction of travel. At least one
of the two drums drives the conveyor belt. Between the drums, the
belt must be pulled over a supporting surface to avoid sagging.
Above a certain width of the conveyor belt or above a certain mass
of the particulate material feedstock, the frictional engagement
between the conveyor belt and the supporting surface is so great
that stick/slip effects may occur, or the drive may fail
completely.
[0013] Link conveyors are furthermore known, which are able to
accommodate very high loads. Link conveyors of this type are driven
in the same way as conveyor belts. A drive drum or return drum is
located at each end of the closed link conveyor. If a link conveyor
is driven in this manner, an uneven feed results. This is because
the plates unwind in the manner of a polygon. At the same time, the
bearing of the individual links may prove to be sensitive to
contaminants. If the links do not ideally abut each other, build
material may enter the space between two plates via the joints and
impair the operation of the flexible connection. In addition,
particulate material may be lost uncontrollably via the joint,
which may result in defects in the particulate material feedstock
and thus in the components.
[0014] Link conveyors are an additional option. Link conveyors are
able to accommodate high loads and are driven in the same manner as
conveyor belts. A drive drum or return drum is located at each end
of the closed link conveyor. If a link conveyor is driven in this
manner, an uneven feed results. This is because the plates unwind
in the manner of a polygon. At the same time, the bearing of the
individual links may prove to be sensitive to contaminants. If the
links do not ideally abut each other, build material may enter the
space between two plates via the joints and impair the operation of
the flexible connection. In addition, particulate material may be
lost uncontrollably via the joint, which may result in defects in
the particulate material feedstock and thus in the components.
[0015] The use of individual plates which are fed in a feed unit
from a magazine is also known. In this case, the build time is
dependent on the number or length of the individual plates.
Continuous building is possible only if the building platforms are
automatically returned to the magazine at the end of the building
process. This is technologically complex, since the plates must,
among other things, be clean for reuse. The vibration-free and
dense placement of a new plate has also proven to be difficult. The
concept of this building device must furthermore be changed to the
extent that the coater is no longer able to travel under the level
of the build plane.
[0016] The known feeding means for use in a continuous process for
building bulky and complex models (components) in layers are thus
subject to a large number of problems. Up to now, no devices and
methods are known which are suitable for producing large and heavy
models and which avoid the disadvantages described above.
[0017] A need thus exists for providing a device and a method for
building models in layers by means of which large and heavy
components may be produced, preferably in the continuous process,
and which are consistent with a preferably precise satisfaction of
the requirements, or by means of which the disadvantages of the
prior art may be at least improved or avoided entirely.
PREFERRED EMBODIMENTS OF THE INVENTION
[0018] The invention relates to a device for producing
three-dimensional models, preferably in a continuous process,
comprising a build surface which has a first end in the direction
of movement and a second end in the direction of movement, at least
one dosing device and at least one solidification unit,
characterized in that the build surface is designed to transport
heavy components, and the components are transportable over the
build surface essentially without distortion. In preferred
embodiments which provide a rotational operation, the first end is
understood to be the start of the process, and the second end is
understood to be the end of the process, or preferably the
unpacking position or the unpacking operation.
[0019] The inventors have advantageously succeeded in providing
drives which are suitable for producing bulky and heavy components,
in particular in continuous processes, for building models in
layers using inclined printing, and which facilitate precise
production without distortion in compliance with the
requirements.
[0020] The inventors thus have developed a device and a method, by
means of which particularly heavy components may be precisely
produced in the continuous layering method (inclined printing) and
which avoid or at least significantly improve the disadvantages of
the prior art. In one preferred embodiment, the work takes place in
batches.
[0021] As illustrated above, different options exist for
transporting the particulate material strand. However, the systems
all have serious problems with regard to precision of the movement
under heavy loads. A conveyor belt must thus be guided over at
least two return rollers, the drive being reasonably integrated
into the rear return roller in the conveyance direction. The
movement precision of the belt would be highest in this location
and correspondingly lowest at the other end, due to slackness in
the belt. However, this is where the layering is carried out, i.e.,
the very place where the belt movement must be precise.
[0022] With the aid of the device according to the invention and
the method according to the invention, it is now possible to move
the feedstock completely forward and to achieve a distortion-free,
precise feed when producing heaving components. Disadvantageous
distortions due to slackness in the drive, which occur in known
methods and systems used therein, are advantageously avoided with
the aid of the invention. The precise production of heavy
components by means of layering in the continuous process is made
possible hereby.
[0023] In preferred devices according to the invention, the build
surface is a horizontal, continuous and/or open conveyor belt, or
it is designed as a rotating platform or a step conveyor.
[0024] The build surface--and thus, in particular, the model or
component--is preferably conveyable with its first and second ends
essentially at the same speed and with the same feed.
[0025] A particularly preferred device is characterized in that the
deviation in the feed between the first and second ends of the
building platform is less than 1 mm, preferably less than 0.5 mm,
most preferably 0.3 mm.
[0026] Preferred devices according to the invention may be
characterized in that the conveyor belt rests and runs on
continuous and/or lateral rollers.
[0027] A device according to the invention may furthermore be
characterized in that the conveyor belt has at least one central
support, the support preferably comprising air cushions and/or
friction bearings and/or rollers and/or ball casters.
[0028] The conveyor belt may have individual links, preferably
connected by hinges, the links having gripping elements which are
driven by worm gear or guide mechanisms.
[0029] The gripping elements may be gripped and positioned with the
aid of horizontally positionable or oscillating or rotating
grippers and/or barbed hooks and/or magnets and/or vacuum
grippers.
[0030] One area of the conveyor belt may be transported on a
liftable base by means of frictional engagement or cohesion of
solid bodies.
[0031] The conveyor belt is preferably driven by at least one
continuous roller or on both sides by at least two lateral
rollers.
[0032] In another preferred device, one area of the conveyor belt
is transported by means of magnetic fields.
[0033] It is also possible for the building platforms of the device
to be automotively driven, preferably on overhead rails or
free-moving.
[0034] The hinges contained in the device preferably have only
limited mobility perpendicularly to the conveyance direction.
[0035] Roller tracks are preferably added to the device.
[0036] The device according to the invention is particularly
preferably characterized in that a horizontal, movable build
surface for applying build material is provided, and a build space
is disposed around it, on which at least one dosing device for
particulate material and a solidification unit for particulate
material are mounted via linear guides, and the horizontal build
surface [is provided] in a Z direction, i.e., at a certain angle to
the transport device which is smaller than the angle of repose of
the build material. The angle is preferably <30 degrees.
[0037] Another aspect of the invention is a device referred to as a
"cone printer" for building components. Its functionality is
apparent, in particular, from FIGS. 10a through 10c.
[0038] A cone printer in the sense of the invention is able to
build components on a building platform in a rotating and outwardly
directed motion from the inside to the outside by layering
particulate material.
[0039] The production of components takes place according to the 3D
method, i.e., a layer of particulate material is applied in the
first step, and a selective solidification of the particulate
material takes place in the second step in the known manner. The
application of particulate material takes place continuously, a
coater (1) completing a circular path for layering the particulate
material. The solidification unit (2) follows this path of the
coater (1) and ensures the selective solidification of the
particulate material and thus the production of components.
[0040] A plurality of components may be advantageously produced on
one building platform simultaneously or in batches.
[0041] The building platform may be selected in dimensions that
allow heavy components to be produced. This preferred design thus
also achieves the object of a distortion-free production of
multiple components.
[0042] The special advantage of the use of a cone printer lies in
the fact that large and heavy components may be produced without
distortion, and a plurality of components may be produced with a
high degree of precision in batches.
[0043] The invention furthermore relates to a method for producing
three dimensional models in the continuous process, comprising the
following steps: a. building the model in layers on a building
platform in a first position, a first layer being applied; b.
transferring the model from the first position to a second position
with the aid of a feed after a layer is built, the building
platform, which has a first front end and a second rear end, being
transported with the model; c. building another layer on the model
on the building platform; d. transferring the model on the building
platform to another position; repeating steps a.) through d.), the
transfer preferably being carried out by means of a step conveyor,
the step conveyor preferably having lifting and thrusting
grates.
[0044] In the method according to the invention for producing
three-dimensional models, the model on the building platform is
transferred without distortion from the first position to the
second position.
[0045] The method according to the invention for producing
three-dimensional models is characterized in that the building
platform with the model is evenly transferred from the first
position to the second position and any further position
essentially without deviations in feed between the first and second
ends of the building platform.
[0046] The deviation in feed between the first and second ends of
the building platform from the first position to the second and any
further position is preferably less than 1 mm, preferably less than
0.5 mm and most preferably less than 0.3 mm.
[0047] When producing large and heavy components, in particular,
the requirements of the horizontal transport device of devices for
the continuous method are particularly critical in order to achieve
a dimensionally accurate and precise reproduction in the
component.
[0048] In this case, a loosely applied feedstock made of sand or
particulate material must be positioned a few micrometers (e.g., 80
.mu.m) with each new layer. The feedstock has only a limited
stability and may weigh several tons.
[0049] The device according to the invention or the conveyor system
according to the invention is preferably characterized by one or
all of the following characteristics:
[0050] Continuous feed (continuous conveyor)
[0051] Vibration-free feed
[0052] High positioning accuracy in the range of just a few
micrometers (e.g., 1 .mu.m)
[0053] High rigidity in the conveyance direction under high loads
(tensile loads up to several tons)
[0054] High rigidity in the vertical direction (weight load up to
several tons)
[0055] Resistance of the supporting surface to contamination with
the build material (e.g., abrasive sands/particulate material or
aggressive solvents)
[0056] Density of the supporting surface in order to prevent runoff
of the build material.
[0057] No stick-slip effects
[0058] Minimal maintenance with almost non-stop operation
[0059] Cost-effective construction
[0060] The present invention advantageously combines the
aforementioned characteristics or at least a subcombination thereof
and thus provides an advantageous device and a method for building
models in layers, the disadvantages of known devices and methods
being avoided or at least partially improved.
[0061] In particular, with regard to load tolerance and positioning
accuracy, the invention provides a superior device and method.
[0062] The device according to the invention may be used, for
example, to produce casting molds from molding sand, in which the
dimensions and thus the weight of the particulate material
feedstock are particularly high.
[0063] One approach according to the invention lies in the use of
link conveyors. Link conveyors whose individual links are connected
by special hinges are particularly suitable in this case. The
hinges have a stop which results in the fact that the link conveyor
is able to bend or roll off from the plane in only one direction
(downward in this case). It is rigid in the other direction (upward
in this case). A sagging of the link conveyor is prevented thereby,
and an even feed with only slight deviations or only slight
distortion is achieved.
[0064] In one particularly preferred embodiment, this link apron is
laid over a roller track and driven by friction engagement. The
roller track is an arrangement of multiple rollers or cylinders.
One, multiple or all rollers may be driven. If all rollers are
driven, an even feed of the link conveyor results. Since the entire
build space of the link conveyor is driven, the belt does not
undergo any tensile loading. The belt is thus unable to lengthen
during operation, and stick-slip effects are ruled out. If the link
conveyor has play in the hinges, this does not have any negative
effect.
[0065] This type of drive also ensures an exact positioning, since
the drive takes place at the point where the plates have already
achieved a horizontal alignment. A polygon effect, which occurs in
known systems, does not take place in the invention.
[0066] The individual rollers or cylinders may be preferably
synchronized by means of coupling elements such as toothed belts,
driving belts, chains, toothed wheels or worm gears. If the rollers
are connected by driving belts, toothed belts or chains, the link
conveyor may also rest directly on the driving belts, toothed belts
or chains. Particularly wide belts require rigid cylinders or
cylinders having a large diameter for support. As the cylinder
diameter increases, so does the distance between the individual
cylinders. Link aprons having low intrinsic rigidity could sag
between the cylinders.
[0067] It may thus be reasonable to attach the drive only to the
sides of the link conveyor and to separately support the
free-hanging links between the side drives.
[0068] All rigid supporting surfaces having good sliding properties
are suitable as the support. These may be, for example, the
following parts: [0069] Roller tracks [0070] Ball tracks [0071]
Sliding materials (e.g., plastics, non-ferrous heavy metals) [0072]
Air cushions [0073] Hydrodynamic bearing of the individual links
[0074] Hydrostatic bearing of the individual links
[0075] In principle, it is also possible to equip each of the links
with rollers or ball casters.
[0076] To improve the static friction, the rollers may also be
pressed onto the driving rollers with the aid of lateral rollers.
The rollers may also be designed as toothed wheels. In this case,
the individual links also have a tooth profile with which the
driving wheels may engage.
[0077] If a link conveyor is used, it is also possible to equip the
underside of individual or all links with a round driving element,
for example. The driving element is then gripped with the aid of a
worm gear or a guide wheel and advanced by the necessary layer
thickness.
[0078] If the individual links are equipped with a driving element,
it is also possible to use a reversing linear drive, which
repeatedly grips and positions the driving element by means of a
gripper. This device may be provided with a particularly rigid
design using simple means.
[0079] In principle, a spring-supported barbed hook may also be
used instead of an active gripper, similarly to a one-way
bearing.
[0080] Switchable vacuum grippers or magnets or hook-and-loop
fasteners are also suitable. They may also be inserted in such a
way that they engage with the belt in a rotating or oscillating
manner. A preferred position would then be within the chain.
[0081] A particularly preferred embodiment of the invention lies in
the use of a discontinuous conveyor line with the aid of a step
conveyor. The transported material is moved along the entire length
in discrete steps. One preferred form of a conveyor mechanism of
this type includes a lever system in the form of a four-bar
linkage, which is driven in a rotary motion at one of the linkage
points. A rigid supporting surface is situated on the side at a
distance from the lever mechanism. The movement sequence begins
with the resting position of the transported material on the
supporting surface. When the four-bar linkage rotates, a lever of
the device will receive the load of the transported material, lift
the transported material and place it back down on the supporting
surface after a discrete distance has passed. The transported
material must travel a horizontal distance on the supporting
surface before the process starts over.
[0082] In the sense of the invention, "step conveyer" is to be
understood as follows: a model or component is built in layers and
transferred from a first position to a second position with the aid
of a step conveyor device, this process continuing or being
repeated in steps, and the component thus being subjected to
step-by-step layering. It is possible that the process takes place
in a longitudinal direction. Alternatively, the step conveyor
device or the method may be designed in such a way that a
repetition of the transfer from position 1 to position 2 and then
back to position 1, etc., takes place. According to the invention,
the step conveyor may be used to transfer the components, which
have a weight of several hundred kilograms to several hundred tons,
without distortion. The feed of each transfer may be from several
centimeters to several meters, depending on the device and the
method of the layer building method. The feed or transfer speed may
be 0.5 to 20 m/min. or 0.1 to 15 minutes per cycle. The step
conveyor may have a fixed frame, including guide rollers, a mobile
frame on lifting rollers and a drive. The drive may have a
mechanical, pneumatic or hydraulic design for the purpose of
achieving the feed or the lift. For example, the mobile frame is
lowered at the start position and the building plate with the model
to be constructed is lowered onto the fixed frame with the aid of,
e.g., hydraulics (a first position) and moved forward in one
direction in order to be lowered again after the transfer (a second
position). This procedure may then be repeated cyclically. The
building plate is lifted and lowered again at the start and end of
the direction of movement. The transfer process may be controlled
from a central unit, e.g., a computer, and be coordinated with the
other components and work steps for layering the component, such as
application of layers and selective solidification or selective
application.
[0083] The advantages of an approach of this type lie in a simple
structure of the conveyor system, the ability to support and to
move the transported material over the entire length. In addition,
the structure may be designed to be extremely resistant to sagging
due to loading by the weight of the transported material.
[0084] If multiple lever systems of this type are built next to
each other, loads of greater width may also be reliably conveyed.
The only requirement for the transported material: it must be stiff
enough to bridge the distance between the lever systems in a freely
supported manner. Flexible or fragile transported materials may
also be transported with the aid of carrier systems such as
palettes. If the transported material is to be moved horizontally
without any vertical movement, the lever system may be equipped
with linear actuators instead of the rotatory drive. In other
words, the transported material again rests on a lever. Another
lever moves against the transported material perpendicularly to the
conveyance direction. The first lever is then lowered, and the
second lever receives the load and shifts it by a discrete length
in the direction of conveyance. The first lever then is raised
again against the transported material and receives the load, while
the second lever is lowered in order to move back into the initial
position. To distribute the weight load better, a lever system of
this type may comprise multiple levers situated side by side, which
mesh with each other like two grates. Since the levers should have
a certain distance from each other for reasons of reduced friction,
a coverage must take place over the gaps between the levers if the
transported material has small components, as in this case. This
may be achieved, for example, by laying down a foil. If the
transported material is a high-density particulate material, as in
the present case, the foil must only be tensile, since the force of
the weight is sufficient to hold the foil in position. The foil may
be guided continuously over the device in the form of a belt as
well as at the two ends of the device with the aid of foil rolling
and unrolling mechanisms.
[0085] In another preferred embodiment, the sealing takes place via
a link apron, which is guided over the lever mechanism.
[0086] A lift/thrust device made of two liftable grates has proven
to be particularly advantageous for transporting a link apron or a
conveyor belt.
[0087] A grate is assembled from parallel plates or rods which are
oriented in the feed direction.
[0088] At least two grates engage with each other in such a way
that each grate is positioned vertically and is able to carry the
link apron. At least one of the two grates must be positioned in
such a way that it may be moved in the feed direction.
[0089] During the building process, both grates are extended all
the way with the aid of linear actuators (e.g., pneumatic
cylinders, spindles), so that they are situated at the same height
and both carry the conveyor belt (link apron). For transporting,
one grate moves down, so that the only grate carrying the conveyor
belt (link apron) is the one which is able to position it in the
feed direction by means of another actuator (thrusting grate). Once
the grate has positioned the conveyor belt (link apron) in the
thrust direction, the other grate (lifting grate) moves out. When
the lifting grate comes to rest, the thrusting grate moves downward
again and subsequently returns to its vertical starting
position.
[0090] In principle, the repositioning of the thrusting grate may
also take place in the thrust direction after multiple individual
steps, if the traveling distance of the linear actuators permits
this. In this case, the thrusting grate is lowered and returned to
the starting position only after multiple individual steps have
been completed. This procedure may be advantageous for the purpose
of reducing positioning errors, e.g., due to the reversing play of
the linear actuators.
[0091] This system is absolutely rigid with respect to a conveyor
belt, and precise positioning may take place simultaneously in both
feed directions.
[0092] Another advantage of the system lies in its easy
scalability, both in the feed direction and also transversely
thereto, e.g., by widening the grates or arranging multiple systems
in a row.
[0093] The structure may preferably have grates, and it is also
possible to lift only the thrusting grate or a thrusting platform
by a minimal amount. Minimal lifting in this case means lifting the
thrusting grate or a thrusting platform only until the force of the
weight produces the corresponding frictional engagement between the
thrusting grate and the conveyor belt. The thrusting grate or a
thrusting platform subsequently positions the conveyor belt
horizontally. If the conveyor belt sags transversely to the
conveyance direction, it may, under certain circumstances, fail to
be fully lifted. The remaining supporting areas are then preferably
designed to have good sliding properties. In these areas, air
cushions or rollers may be mounted on the link apron itself or on
the supporting surface.
[0094] Conveyor belts which are driven by means of frictional
engagement or a form fit (similarly to a toothed belt) are also
suitable up to a certain width. It would also be possible to
incorporate driving elements into a flexible conveyor belt.
Electrically conductive windings, which are incorporated into the
belt, would also be possible, so that the entire belt is driven by
means of self-inductance, similarly to a three-phase motor.
[0095] To avoid sagging in particularly wide belts, intrinsically
rigid inserts may be incorporated transversely to the feed
direction.
[0096] Another option according to the invention is to apply the
particulate material feedstock on individual plates. The plates
could be moved with the aid of the same transport systems as for
link conveyors (see above). For continuous building, the
transportation of the built-upon plates back to the start after
unpacking must be ensured. This may be accomplished with the aid of
robots or conveyor belts.
[0097] However, it is also possible to transport the individual
plates on a rail system.
[0098] The plates may be supported individually, e.g., on rollers
or air cushions, and transported into the system.
[0099] For automation, each plate may be equipped with its own
intelligent drive. All information on the particular building
project may be stored therein, and it may communicate with the
building device and the warehouse.
[0100] The methods described above may also be used for conveyor
belts and link conveyors which are rolled off of and onto rollers.
A design of this type advantageously permits uninterrupted
operation.
[0101] To store as many parts as possible, spiral conveyor belts
may also be used, similarly to those in spiral freezers.
[0102] In principle, both open and closed belts in the form of
foils or sheets may be used to seal link aprons. These sealing
belts may be inserted by rollers in an open or closed manner.
[0103] Rotating plates, on which the material cone is applied
tangentially, are also conceivable.
[0104] It would also be possible to produce a truncated cone on a
rotating plate. The coater and the tool for selective
solidification (e.g., the print head) move axially away from the
rotation axis synchronously with the rotary motion of the
plate.
[0105] In one particularly preferred device or method for producing
components by 3D printing, according to the invention, a coater and
a solidification unit for selective solidification are combined
with a circular building platform (see FIG. 12). The first end and
the second end are to be understood in such a way that a process
start exists (first end), at which the particulate material
application takes place, and a process end exists (second end), at
which the component is finished or the finished components are
preferably unpacked. The selective solidification may take place in
the process with the aid of chemical methods (selective
solidification with the aid of a chemical binder) as well as using
methods such as selective laser sintering or laser melting (SLS,
SLM). The circular building platform may also be combined with
devices for the selective application of material, such as Fused
Deposition Molding (FDM) and other methods known to those skilled
in the art for the selective application of material to
predetermined areas.
[0106] This preferred device according to the invention or the
production method have the further advantage that the components
are produced on a single rotating building platform, and the
component thus does not change its position on the building
platform, whereby the production also takes place without
distortion. This is advantageous, in particular, when producing
large and heavy components. The method may be carried out in
batches or continuously. During continuous operation, a method step
of a continuous unpacking operation, using means which are known to
those skilled in the art, is combined with other device parts and
method steps and coordinated therewith.
DESCRIPTION OF THE FIGURES
[0107] FIG. 1 shows a preferred structure according to the
invention, including a closed conveyor belt (e.g., link conveyor)
(7) and an open sealing belt (6). The conveyor belt is able to bear
the great weight of the particulate material cake while the cover
belt is being unrolled and should only prevent the conveyor belt
from coming into contact with the particulate material cake. The
conveyor belt is unrolled from a roller and rolled up again behind
the conveyor belt. The cover belt may be fed by means of frictional
engagement on the conveyor belt or by winding up.
[0108] FIG. 2 shows a preferred link conveyor according to the
invention, including hinges which permit mobility only in one
direction. The link conveyor is moved by a roller track in this
case. Only one, multiple or all rollers may be driven.
[0109] FIG. 3a shows a preferred transport unit according to the
invention, comprising conveyor belt (7) (preferably a link conveyor
as in FIG. 2), which is driven laterally by driving rollers (14)
and is supported on small rollers (15) in the middle.
[0110] FIG. 3b shows a similar structure, in which conveyor belt
(7) rests on continuous driving rollers (17) over its complete
width. To achieve a better frictional engagement between the
driving rollers (14) or driving cylinders (17) and the conveyor
belt (7), pressing rollers (13) press the conveyor belt onto the
driving rollers (14) or driving cylinders (17).
[0111] FIGS. 4a and 4b show a preferred structure according to the
invention, in which the driving rollers (14) are driven by a shared
driving belt (18). Conveyor belt (7) may then rest on the driving
belt and be additionally supported. In FIG. 4a, the middle of
conveyor belt (7) is supported on sliding elements (19) made of,
e.g., plastic. In FIG. 4b, the middle of the conveyor belt is
carried by air cushions (20).
[0112] FIGS. 5a through 5c show a structure according to the
invention, comprising a link conveyor (7), which has a gripping
element (22) on each link. A gripper, which repeatedly grips and
positions a gripping element, passes beneath the link conveyor. The
sequence is gripping and positioning (FIG. 5a), opening the gripper
(FIG. 5b), returning and regripping a link (FIG. 5c).
[0113] FIG. 6 also shows a structure according to the invention,
including a link conveyor (7), which has a gripping element (22) on
each link, according to the invention. In this case, gripping
elements (22) are positioned by a rotating worm drive (24).
[0114] FIG. 7 shows an oblique view of a preferred feed system
according to the invention, including raised grates according to
the invention.
[0115] FIGS. 8a through 8c show the sequence of the feed system
from FIG. 7, from the front and from the side in each case,
according to the invention.
[0116] FIG. 8a shows the starting position when both lifting grate
(26) and thrusting grate (27) carry the conveyor belt. In FIG. 8a,
lifting grate (26) has been extended and thrusting grate (27)
subsequently lowered.
[0117] In FIG. 8b, lifting grate (26) has been lowered so that only
thrusting grate (27) carries conveyor belt (7). Thrusting grate
(27) then moves conveyor belt (7) into its next position.
[0118] In the lowered state, thrusting grate (27) returns to its
starting position, as illustrated in FIG. 8a.
[0119] FIG. 9 shows a preferred structure according to the present
invention with self-propelled building platforms (31). They are
moved into building device (32).
[0120] FIGS. 10a through 10c show additional preferred embodiments
according to the invention. In this case, the feedstock is not
produced linearly but rotatorily. The process begins at a first
position or end and ends at a second position or end. FIG. 10b is a
view of FIG. 10a from above. FIG. 10c is a side view of FIG. 10b of
the cone printer according to the invention, on sectional plane
A-A. (33) designates the outwardly oriented movement of coater (1)
and solidification unit (2), which is indicated using directional
arrows, the method being carried out on building platform (34), and
a particulate material feedstock (3) being generated and components
[produced], e.g., component (5), following solidification. For this
purpose, round building platform (34) is rotated, while coater (1)
and the print axis move away from the rotation axis. Coater (1) is
rotated 90.degree. with respect to the other preferred devices of
the invention described above and may be operated continuously.
Solidification unit (2) may also work continuously, whereby a
plurality of components may be produced in this manner on one
building platform (34) in one operation (batch). A build cone (21)
may be used to start the system. The alpha angle may be changed,
depending on the particulate material, and thus be optimally
adapted to the particular particulate material used. This device
type requires the data for the molds for the components to be
produced to be skewed not only linearly but also on the basis of
polar coordinates. The dimensions of the cone printer and the
building platform as well as the device as a whole may be selected
in such a way that both very small and very large and heavy
components may be produced without distortion.
[0121] FIG. 11 shows a preferred building device (32) according to
the invention, to the end of which an unpacking area, including a
roller track (35), is connected. The finished components are
deposited directly onto the roller track. Loose particulate
material may run off between the rollers and thus support
unpacking. The roller track may be driven or it may run
passively.
[0122] FIG. 12 shows a preferred building device according to the
invention with a rotating building platform (34). Coater (1) and
solidification unit (2) move only translatorily, while building
platform (34) continues to rotate layer by layer and thus
continuously builds up material feedstock (3). In another preferred
embodiment, the device in FIG. 12 may be configured in such a way
that it is combined with an unpacking station or an unpacking
operation in an arbitrary position. Finished components (5) are
shifted to a position (36) inside or outside or below or above
building platform (34) and freed of the remaining loose particulate
material simultaneously or in another work step. The process begins
at a first position or end, e.g., at the point of the first
particulate material application, and ends at a second position or
end, e.g., upon completion of the component or preferably at the
point of unpacking. The loose particulate material may be
resupplied cyclically to the further continuous process. The
particulate material supply is thus limited to the quantities which
are removed from circulation in the form of components and any
non-reusable quantities.
[0123] FIGS. 13a through 13f show a drive for belts or link aprons
with lifting grates (26) and thrusting grates (27) according to the
principle of the step conveyor. Thrusting grate (27) moves on lever
arms which swivel back and forth. Lifting grate (26) is raised on
the return swiveling motion.
[0124] FIGS. 14a through 14d show a drive for belts or link aprons
with lifting grates (26) and thrusting grates (27) according to the
principle of the step conveyor. Thrusting grate (27) moves on
rotating lever arms.
[0125] FIGS. 15a through 15d show a drive for belts or link aprons
with lifting grates (26) and thrusting grates (27) according to the
principle of the step conveyor. A vertical lifting of lifting grate
(26) alternates with an inclined lifting of thrusting grate
(27).
LIST OF REFERENCE NUMERALS
[0126] 1 Coater [0127] 2 Solidification unit [0128] 3 Powder
cake/particulate material feedstock [0129] 4 Tunnel wall [0130] 5
Component (being built) [0131] 6 Roller for cover belt [0132] 7
Conveyor belt (e.g., link conveyor) [0133] 8 Linear unit [0134] 9
Build space [0135] 10 Link with hinge [0136] 11 Driving cylinder
[0137] 12 Cylinder bearing [0138] 13 Pressing roller [0139] 14
Driving roller [0140] 15 Bearing roller [0141] 16 Motor [0142] 17
Conveyance direction [0143] 18 Driving belt (e.g., toothed belt)
[0144] 19 Sliding element [0145] 20 Air cushion [0146] 21 Gripper
[0147] 22 Gripping element [0148] 23 Linear feed [0149] 24 Worm
wheel [0150] 25 Frame [0151] 26 Lifting grate [0152] 27 Thrusting
grate [0153] 28 Linear bearing [0154] 29 Lifting unit for lifting
grate [0155] 30 Lifting unit for thrusting grate [0156] 31
Self-propelled building platform [0157] 32 Building device [0158]
33 Direction of movement of the coater and the solidification unit
[0159] 34 Rotating building platform [0160] 35 Roller track [0161]
36 Unpacking area
* * * * *