DE102020004504A1 - Apparatus and method for a powder system for improved powder usage efficiency in an additive manufacturing process - Google Patents

Abstract

The invention relates to a system (10) for the additive manufacturing of multidimensional structures with a powder system (35) and a method (100) for using powder for the additive manufacturing of multidimensional structures using such a system, comprising a spatially movable application unit (20) for powder (30), a powder system for providing the powder and a control unit for controlling at least the application unit and the powder system, the powder system (35) comprising at least a first powder container and a second powder container, which are provided for alternating the powder to be applied to provide as a temporary powder supply or to take up excess powder after application beyond the substrate platform arranged between the first and second powder container as seen in the direction of movement of the application unit as a temporary overflow container.

Description

The invention relates to a system for the additive manufacturing of multidimensional structures with a powder system and a method for using powder for the additive manufacturing of multidimensional structures using such a system.

State of the art

Additive manufacturing processes are known in the prior art, such as 3D printing, which use a starting material in powder form to build a multidimensional structure. The material to be processed can, for example, be processed by a jet melting process in order to obtain the desired spatial structure. Well-known beam melting methods are, for example, laser powder bed fusion (LPBF), electron beam melting or selective laser sintering. In an LPBF process, the material to be processed in powder form is applied in a thin layer to a substrate platform by a powder application unit. The powdered material applied is completely remelted locally using laser radiation and forms a solid layer of material after solidification. The substrate platform is then lowered by the amount of a layer thickness (typically 20 - 100 µm) and powder is again applied by the powder application unit and sintered by the laser. This cycle is repeated until all layers have been remelted and the component is finished.

However, a well-known problem in the processing of powdery material is that the use efficiency of the powder for powder application needs to be optimized. Two containers are known in the prior art, in which the powder is present in a first container and a substrate platform and the component to be produced are present in a second container. A mobile powder transport unit of the first container pushes powder over an application level and an application unit moves from the first container to the second container and pushes the powder over. Excess powder that should not or could not be applied is further collected in an overflow container. The excess powder in the overflow container is removed from the system at the end of additive manufacturing, the powder is sieved again, partly disposed of and partly made available again for the next process.

The disadvantage of this use of powder is that it is inefficient, since a lot of powder cannot be used for production at all. It is also time-consuming to remove the excess powder at the end of the process and then sieve it again.

It would therefore be desirable to be able to use powder more efficiently during additive manufacturing, so that less powder is used and/or the manufacturing process can be carried out more quickly.

Summary of the Invention

An objective object of the invention is therefore to provide a device with which a more effective use of the powder is possible during additive manufacturing, so that less powder is consumed and/or the manufacturing process can be carried out more quickly.

This object is achieved by a system for the additive manufacturing of multidimensional structures comprising a spatially movable application unit for powder, a powder system for preparing the powder and a control unit for controlling at least the application unit and the powder system. The application unit is intended to apply one or more layers of powder in an application plane to a substrate platform or to a layer of powder that has already been treated with the system. The powder system comprises at least a first powder container and a second powder container, which are intended to alternately provide the powder to be applied as a temporary powder supply or excess powder after application beyond the substrate platform arranged between the first and second powder container, viewed in the direction of movement of the application unit accommodate temporary overflow tank. The control unit is intended to move the application unit from the first powder container as a powder supply via the substrate platform and the second powder container as an overflow container and from there in the opposite direction to move the application unit from the second powder container, which is now used as a powder supply, via the substrate platform and the first To move powder container, which is now used as an overflow container. This means that the excess powder can be used again immediately after application for a new application. The system according to the invention therefore enables more effective use of the powder during additive manufacturing, so that less powder is consumed and/or the manufacturing process can be carried out more quickly.

"System for additive manufacturing" means a manufacturing system in which material is applied layer by layer and multidimensional structures are generated (3D printing). The layered structure is computer-aided controls from one or more liquid or solid materials according to specified dimensions and shapes. During construction, physical or chemical hardening or melting processes take place. Typical materials used for 3D printing are plastics, synthetic resins, ceramics and metals. Carbon and graphite materials can also be used for 3D printing. Beam melting systems are particularly suitable for the production of structures made of metal, which are mainly used in the industrial sector. Beam melting is understood to mean, for example, laser powder bed fusion (also called selective laser melting), electron beam melting and selective laser sintering.

Such a system can include a control unit for controlling the additive manufacturing process. Such a control unit can include a computer unit, a processor, a memory unit, etc. The control unit is designed to control the components of the system according to a control program, for which purpose it is connected to them in a suitable manner, for example with a suitable data line or wirelessly, e.g. via WLAN. The control unit is usually instructed by a control file. This is usually a CAD file that contains the multidimensional structure to be manufactured. The transfer of the 3D models from the control file (CAD) to 3D printing (CAM) usually takes place via an STL interface. This maps information about the geometry representation. Alternatively, other file formats can also be used to exchange additional information. For example, the VRML and OBJ formats store color information in addition to the geometry. The AMF format (defined by the ISO/ASTM 52915 standard) can also display general information such as material properties and also allows the option of storing curved surfaces. Also the 3MF format, stores information in addition to the geometry information.

A “multidimensional structure”, which is to be understood as meaning predominantly three-dimensional structures, can be provided as components for any application. For example, the applications may be suitable for plastic injection tools, aerospace components, special tools, etc. In addition to the finished component, the term "multidimensional structure" also includes the unfinished component, i.e. the deformation in the powder bed during production.

An “application unit” is a device suitable for applying powder to a substrate platform for construction. The application unit is designed to be spatially movable relative to the system in order to transport and apply powder from one location (e.g. a powder container) to the other (e.g. the substrate platform). Various versions of the application unit are detailed in the following paragraphs.

"Powder" means the material to be processed, which is used in powder form. For example, the powder may consist primarily of metal or polymeric material. During manufacture, the powder is applied layer by layer to a substrate platform. For each application by the application unit, a "powder layer" is applied on either the substrate platform (first layer) or on a powder layer already treated with the system. The applied powder layer typically has a layer thickness of z. B. 10 microns or preferably <20 microns. The term "powder layer" can therefore also be understood as meaning the composition of all layers of powder that have already been treated by the plant. Theoretically, "several powder layers" can also be applied before they are treated by the system (e.g. by lasers). The powder can consist mainly of powder grains of the same material. However, a mixture of materials is also possible. However, the powder grains can differ in their size, shape and grain fraction within the powder to be applied/used. This inhomogeneity of the powder is mostly due to the production and/or the after-treatment (e.g. by sieving, air classification, etc.) of the powder. Particularly small and/or spluttering powder grains tend to agglomerate with each other.

A "powder container" is suitable for receiving and conveying the powder. The shape of a powder container is variable. The powder container preferably has a cylindrical shape. This has the advantage that the container can be sealed off from the wall using standard sealing elements, which makes production simple and inexpensive. However, the powder container does not have to be cylindrical. The powder container can also have other geometric shapes (such as a cuboid, rounded cuboid, tetrahedron) that are suitable for receiving powder. Also, the powder container can be equipped with a handle to facilitate use, such as getting it in and out of the system. The powder container may be constructed of light metal such as aluminum alloy materials. This has the advantage that the container can be made particularly light.

Powder containers can (at least the first and at least the second) comprise a mobile powder conveying unit which is controlled by the control unit depending on the mode of operation of the respective powder container moves up or down as a temporary powder supply or overflow container. When the powder feed unit is started up, a quantity of powder is made available for powder application, so that the powder container is used as a powder supply at that moment. When the powder feed unit is moved down, the container is enlarged so that excess powder can be picked up. In this sense, the powder container is used as a surplus container. This means that there is no longer a need for an extra container to hold the excess powder. Otherwise, the extra container would have to be taken out of the system after each manufacturing process, the powder removed and reinstalled.

The term "substrate platform" means a construction platform for supporting the structure to be manufactured. The substrate platform is designed in such a way that it can be moved relative to the system. This enables a further application of a powder layer in an application level if the already treated powder layer is moved downwards (lowered) for this purpose, for example. The substrate platform is most often designed to move with a seal within an enclosed unit. This enclosing unit can be a container, for example the container can be in the form of a cylinder. The container can be configured analogously to a powder container according to the invention, in which case the substrate platform can also be configured analogously to a mobile powder conveying unit according to the invention. However, the substrate platform can theoretically also be arranged freely in space.

In one embodiment, the substrate platform can be lowered, controlled by the control unit, after each application by the layer just applied. This allows powder to be reapplied by the applicator unit.

In one embodiment, a first material can be provided in the first powder container and a second material can be provided in the second powder container before application. In a specific embodiment, the first material may be the same as the second material. This is conventionally the case. In an alternative embodiment, the first material can be different from the second material. This enables, for example, in-situ multi-material processing of the system. The mixing ratio of the different materials to one another can be configured flexibly by controlling the control unit using the at least two overflow containers. It is important that the overflow containers are located at the ends of the movement of the applicator unit. This embodiment has the advantage that it is possible to find out, among other things, how the individual bonding mechanisms between different materials work, which can be easily observed through particularly thin layered bonding systems. This is interesting for research purposes, among other things. In addition, the embodiment has the advantage that a ductile material can be metallurgically bonded to a brittle material to form layers for the application in order to utilize the advantages of both materials.

In a further embodiment, the amount of transported powder above the application level of the powder supply can correspond to a layer thickness of a factor greater than or equal to 1.2, particularly a factor of 2, particularly preferably a factor of 3 or 4, a layer thickness of an applied and/or to be applied powder layer on the substrate platform . In order to be able to use the second powder container as a powder supply, there must be a minimum amount of powder in the container. It is therefore advantageous if a measured amount of powder is pushed from the first container to the second. Conventionally, a factor of 1.2 of the layer thickness to be applied is carried by the powder supply to account for enough powder including powder falling off the edges of the substrate platform. However, the multi-dimensional structure is melted at local locations during manufacture, resulting in certain "valleys". Depending on the structure, these valleys can be relatively large, so that 1.2 times the amount of powder is not sufficient to fill the valleys and apply the desired powder layer thickness. Local areas can also sometimes require more powder because a larger area has to be exposed at the areas. It is therefore advantageous to provide a significantly larger amount of powder, e.g. 2, 3 or 4 times the powder layer to be applied for the powder application. However, this is only advantageous with a system according to the invention, since the device according to the invention can reuse the excess powder during production. In a conventional prior art powder system, the excess powder would fall off the edges and/or be stored unused in a waste bin until the next process.

In order to obtain a particularly high-quality component (multidimensional structure), the applied powder layer should be particularly smooth. In one embodiment, the system according to the invention can therefore comprise an excitation unit which is intended to break up adhesions of individual powder grains to one another and/or to a powder layer already treated with the system when the powder is applied, so that the application unit applies a smooth layer of powder to the substrate plate form and/or can be applied to the previous layer of powder.

The adhesion of individual powder grains to one another can be broken up by "stimulation" in order to counteract agglomeration. The excitation is used, preferably temporarily, when the powder is applied, in order to break up the adhesion of individual powder grains to one another and/or to a layer of previously powder grains that has already been treated with the system. Furthermore, the excitation can also only be used for smoothing a layer of powder, without application taking place. An excitation does not necessarily have to be limited to vibrations, it can also be carried out, for example, by changing the temperature.

In one embodiment, the excitation unit can include a vibration unit that breaks up the adhesions by means of vibration. Due to the oscillations (“vibrations” are also possible), the bonds between the powder grains can be broken particularly efficiently. The vibrations can be generated pneumatically and/or electromagnetically and/or by ultrasound. The pneumatic excitation can take place with the help of a gas, e.g. argon during the application. A vibration unit with pneumatic excitation is advantageous because it is small and compact, can be integrated into an application unit without great technical effort and without many additional components. The disadvantage of pneumatic excitation is that the application speed is relatively low (approx. 20 mm/s) and the quality of the smoothing is worse than with ultrasound. A frequency of the pneumatic excitation can be around 200 Hz. Electromagnetic excitation has the advantage of not requiring any gas. The electromagnetic excitation is also technically easy to implement. However, it has the disadvantage that it is not suitable for all metals, e.g. not for metals with ferromagnetic properties. Excitation with ultrasound has significant advantages in application speed. This can be more than 200 mm/s, i.e. more than ten times the conventional application speed of an application unit without excitation. The frequency of the ultrasound can be e.g. 35 kHz, which is suitable for powder grains with a size of 2 µm (mean diameter). In addition to the good throughput, ultrasound also has the advantage that the quality of the smoothing is particularly good. Accordingly, the vibration unit can be suitable for generating individual such vibrations and/or a combination of such vibrations. The excitation takes place from a direction above the substrate platform (i.e. above the powder layer) so that at least the uppermost powder layer of the powder layer that has already been treated is excited. The excitation also has at least one frequency. In one embodiment, the frequency of the excitation does not overlap with a resonant frequency of the plant. This prevents the system from being damaged by the vibration generated. In a further embodiment, the frequency of the oscillation can have a wavelength which correlates with a grain size of the powder and/or an application speed of the application unit along an application direction. The amplitude of the vibrations correlates with the frequency and thus also with the application speed of the application unit, so that the size of the individual grains corresponds to the vibrating amplitude in terms of magnitude. This has the advantage that the application speed can be increased without loss of quality. Therefore, this embodiment can increase manufacturing efficiency and throughput. In a specific embodiment, the excitation frequency can be between 40 Hz, preferably 80 Hz to 100 kHz. This has the advantage that grain sizes of less than 20 µm can be applied particularly efficiently.

In one embodiment, the excitation unit of the system according to the invention can be arranged stationary relative to the powder layer and/or to the substrate platform.

This can bring structural advantages, e.g. when the excitation unit is connected to or integrated into the substrate platform. This can be realized by a vibrating substrate platform. However, this embodiment has the disadvantage that the effect of the vibration decreases the more the component to be manufactured increases in height. In the case of a vibrating substrate platform, the powder layers would contribute to the damping of the excitation. The technical implementation is also difficult in that the powder can trickle down the edges of the substrate platform due to the vibrations. Therefore, in an alternative embodiment, the excitation unit can be arranged to be spatially movable relative to the powder layer and/or to the substrate platform. This embodiment has the advantage that the strength of the excitation on the powder layers is not influenced by the overall height of the multidimensional structure. This embodiment also makes it possible, for example, for the application unit to include the excitation unit. A compact design is also possible as a result.

In one embodiment, the application unit can include an excitation unit as described above.

In one embodiment, the application unit additionally includes a smoothing tool. the smooth The tool is used for the physical smoothing of the powder layer that has been applied and/or has already been treated with the system. The smoothing tool can include a grinder, a silicone lip, a plastic bar, a brush, or a metal edge. The silicone lip is particularly well suited for low-frequency excitation because it is very soft. The plastic beam has similar advantages. A brush, on the other hand, is well suited for restless processes. A metal edge is well suited if the processes are already stable. In an advantageous embodiment, the grinding unit has a material with a certain degree of hardness, which is suitable for ultrasonic grinding and/or polishing. In this case, the grinding unit can preferably be a conventional grindstone. The property of the special hardness of the grinding unit is particularly suitable for use in high frequency ranges, such as ultrasound, as it is particularly stable. In addition, a conventional grindstone intended for physical grinding can be obtained inexpensively. The grinding unit can be made of ceramic. Furthermore, the grinding unit can be made of aluminum oxide or diamond.

The smoothing of the powder layer is also made more difficult by the inhomogeneous composition of the powder. In one embodiment, the system according to the invention is also suitable for smoothing powder layers if at least part of the powder used has a property of agglomeration and/or a spattered structure. Small powder grains with a grain size of <20 µm tend to agglomerate in particular. The system according to the invention is therefore particularly suitable for powders which have a grain size of <20 μm, of which preferably at least part of the powder used has a grain size of <2 μm. Powder grains that are not spherical and/or have corners and points (“spattered powder grains”) have a spattered structure. Even spattered powder grains can tend to agglomerate without the grain size being particularly small. The grain size of powder grains can be determined according to EN ISO 14688, for example.

In one embodiment, the system according to the invention can be a damping unit that is designed to reduce transmission of the excitation to system components outside of the excitation unit. The advantage of the damping unit is that it particularly dampens the vibrations of the excitation unit in unfavorable directions of the system and thus protects the system. The axes of the system are particularly sensitive to vibrations generated by the vibration unit. If the excitation unit is integrated in the application unit, it is important to dampen in the directions above the powder layer to the axis of movement of the system. The application unit can be held via a holder on guides for executing a defined movement of the application unit, the holder being designed as a damping unit or as part of it if the excitation unit is arranged in the application unit. The holder can be made of a soft material that absorbs vibrations well. Therefore, in addition to stabilizing and holding the application unit, the holder can also have the function of contributing to cushioning. The damping unit is therefore an advantage for the protection and longevity of the system.

In one embodiment, the system according to the invention can be designed to carry out selective laser melting and/or electron beam melting. In these processes in particular, powder with different grain sizes and shapes is used. This also includes powders with small particle sizes and/or spattered shapes. A smooth surface is particularly advantageous for the quality of the manufactured component (multidimensional structure).

The object is also achieved by a method for the additive manufacturing of multidimensional structures by a system according to one of the preceding claims, comprising a spatially movable application unit for powder, a powder system for providing the powder and a control unit for controlling at least the application unit and the powder system, wherein the powder system comprises at least a first powder container and a second powder container, comprising the steps of: providing a temporary powder supply and a temporary overflow container alternately through the first and the second powder container; moving the application unit from the respective powder supply in the direction of the respective overflow container by the control unit; Applying one or more powder layers in an application plane to a substrate platform or to a powder layer already treated with the system using the powder provided by the powder store, the substrate platform being arranged between the powder store and the overflow container; accommodating excess powder after application by the application unit beyond the substrate platform as seen in the direction of movement by the overflow container; and moving the applicator unit in the reverse direction, with the former overflow reservoir now being used as the powder supply, to the former powder supply now being used as the overflow reservoir.

The method according to the invention enables the powder to be used more effectively during additive manufacturing, so that less powder is consumed and/or the manufacturing process can be carried out more quickly.

All features of the method according to the invention which correlate with the features of the system according to the invention also have at least the corresponding advantages.

In one embodiment, the method according to the invention can comprise a further step of lowering the substrate platform by the control unit by a thickness of the powder layer just applied after each application passage through the application unit. In beam melting processes, the multidimensional structure can be built up step by step on the substrate platform.

In a further embodiment, the method according to the invention can include a further step of breaking up adhesions of individual powder grains to one another and/or to a powder layer already treated with the system by means of an excitation unit during the application of the powder, so that the application unit applies a smooth powder layer to the substrate platform and/or can be applied to the previous layer of powder.

In an advantageous embodiment, the above steps can be repeated until the multi-dimensional structure is finished.

The above embodiments can be combined with one another individually or cumulatively in any order, also deviating from the references to the claims.

character list

• 1 a) Schematic representation of an embodiment of the system according to the invention with powder system, application unit and control unit; and b) Detailed view of a);
• 2 An embodiment of an application unit according to the invention with an excitation unit;
• 3 An embodiment of a method according to the invention;
• 4 An embodiment of the method according to the invention; and
• 5 a) An embodiment of a powder system according to the invention and b) system according to the invention.

Detailed description of the figures

1 a) and b) show a system 10 according to the invention for the additive manufacturing of multidimensional structures, comprising a spatially movable application unit 20 for powder 30, a powder system 35 for preparing the powder 30 and a control unit 50 for controlling at least the application unit 20 and the powder system 35. The application unit 20 is intended to apply one or more layers of powder in an application plane 15 to a substrate platform 16 or to a layer of powder that has already been treated with the system. The powder system 35 comprises at least a first powder container 36 and a second powder container 39, which are intended to alternately provide the powder to be applied as a temporary powder supply 33 or excess powder after application via the space between the first and second as viewed in the direction of movement of the application unit 20 Powder container 36, 39 arranged substrate platform 16 also record as a temporary overflow container 38. The control unit 50 is intended to move the application unit 20 from the first powder container 36 as the powder supply 33 via the substrate platform 16 and the second powder container 39 as the overflow container 38, and from there in the opposite direction to move the application unit 20 from the second powder container 39, which is now used as the powder supply 33 is used to move over the substrate platform 16 and the first powder container 36, which is now used as the overflow container 38. The powder containers 36, 39 can each include a mobile powder conveying unit 37 which, controlled by the control unit 50, moves up or down (arrows) as a temporary powder supply 33 or overflow container 38 depending on the mode of operation of the respective powder container 36, 39. The substrate platform 16 can be lowered, controlled by the control unit 50, after each application by the layer just applied. Only after the component has been manufactured can the substrate platform be raised again to restart the manufacturing process. The amount of powder transported above the application level 15 of the powder supply 36, 39 can have a layer thickness of a factor greater than or equal to 1.2, particularly a factor of 2, particularly preferably a factor of 3 or 4, a layer thickness of a layer of powder that has been applied and/or is to be applied on the substrate platform 16 correspond.

2 shows an application unit 20 according to the invention, which includes an excitation unit 40 . The excitation unit 40 is intended to break up adhesions of individual powder grains to each other and/or to a powder layer that has already been treated with the system when the powder is applied, so that the application unit 20 applies a smooth layer of powder to the substrate platform 16 and/or applied to the previous layer of powder. In this embodiment, the application unit is designed as follows (from top to bottom): The application unit 20 of the system 10 has a holder 23 which is held on guides for executing a defined movement of the application unit 20 . The holder 23 can be designed as a damping unit 22 or as a part thereof since the excitation unit is arranged in the application unit in this embodiment. Furthermore, the embodiment includes a damping unit 22 which is designed to reduce transmission of the excitation to system components outside of the excitation unit 40 . These can be arranged on at least two sides of the excitation unit 40 in order to dampen the vibrations and to connect the smoothing tool holder to another holder 23 or damper 22 . The holder 23 is intended to hold the application unit 20 on guides for executing a defined movement of the application unit 20, the holder 23 preferably being designed as a damping unit 22 or as part thereof. The damper unit is also designed to connect the holder 23 to the excitation unit 40 . The application unit 10 comprises an excitation unit 20, the excitation unit 40 being arranged to be spatially movable relative to the powder layer 32 and/or to the substrate platform 16. The excitation unit 40 can include a vibration unit, which breaks up the adhesions of the powder grains 33 to one another by means of vibrations. The excitation unit 40 can be mounted above the decurler and is connected to it. The embodiment shown includes a smoothing tool 21 which may include a grinding unit, a silicone lip, a plastic bar, a brush and/or a metal edge. The material of the grinding unit should have a certain degree of hardness suitable for ultrasonic grinding and/or polishing, preferably the grinding unit is a conventional grindstone. The grinding unit can be made of ceramic, for example. The application unit 20 applies one or more layers of powder to the substrate platform 16 (if it is the first layer) and otherwise to layers of powder 32 already treated by the system. A powder layer that has already been treated by the system 10 therefore includes the multidimensional structure that has already been lasered (shaped).

3 shows a method 100 according to the invention for the additive manufacturing of multidimensional structures by a system 10 according to the invention, comprising a spatially movable application unit 20 for powder 30, a powder system 35 for providing the powder and a control unit 50 for controlling at least the application unit 20 and the powder system 35 Powder system 35 comprises at least a first powder container 36 and a second powder container 39. The method 100 comprises providing 110 a temporary powder supply 33 and a temporary overflow container, each alternating through the first 36 and the second powder container 39; a movement 120 of the application unit 20 from the respective powder supply 33 in the direction of the respective overflow container 38 by the control unit 50; an application 130 of one or more powder layers in an application plane 15 on a substrate platform 16 or on a powder layer already treated with the system using the powder 30 provided by the powder store 33, the substrate platform 16 being arranged between the powder store 33 and the overflow container 38; a collection 140 of excess powder 34 after application by the application unit 20 viewed in the direction of movement beyond the substrate platform 16 by the overflow container 38; a movement 150 of the application unit 20 in the reverse direction, with the former overflow container 38 now being used as the powder supply 33, to the former powder supply 33, which is now used as the overflow container 38. Steps 110 to 150 can be repeated any number of times until the multidimensional structure is produced.

4 shows an embodiment of in 3 illustrated method of the invention. The method 100 further comprises a further step of lowering 160 the substrate platform 16 by the control unit 50 by a thickness of the powder layer just applied after each application passing through the application unit 20. The method 100 further comprises a further step of breaking up 170 adhesions of individual powder grains to one another and /or to a layer of powder already treated with the system by an excitation unit during application of the powder, so that the application unit 20 can apply a smooth layer of powder to the substrate platform 16 and/or to the previous layer of powder. The above steps can be repeated arbitrarily until the multidimensional structure is finished.

5 a) shows a powder system 25 according to the invention with a first powder container 36 and a second powder container 39, both of which function as a powder supply 33 and an overflow container 38 and a container comprising the substrate platform 16 (not shown), which is integrated in the system 10 according to the invention for improving the powder use efficiency .

5b) shows an embodiment of a system 10 according to the invention in a front view.

The embodiments shown here are only examples of the present invention and should therefore not be understood in a restrictive manner. Alternative embodiments contemplated by those skilled in the art are equally encompassed within the scope of the present invention.

Reference List

10

system according to the invention

15

order level

16

substrate platform

20

order unit

21

smooth tool

22

damping unit

23

holder

24

smoothing tool holder

25

direction of application

30

powder

33

powder supply

34

excess powder

35

powder system

36

first powder container

37

mobile powder feed unit

38

overflow tank

39

second powder container

40

excitation unit

50

control unit

100

inventive method

110...170

Steps according to a method according to the invention

Claims (11)

A system (10) for the additive manufacturing of multidimensional structures, comprising a spatially movable application unit (20) for powder (30), a powder system (35) for providing the powder (30) and a control unit (50) for controlling at least the application unit (20 ) and the powder system (35), wherein the application unit (20) is intended to apply one or more powder layers in an application plane (15) to a substrate platform (16) or to a powder layer that has already been treated with the system, wherein the powder system (35) comprises at least a first powder container (36) and a second powder container (39), which are intended to alternately provide the powder to be applied as a temporary powder supply (33) or excess powder after application via the direction of movement to accommodate the substrate platform (16) arranged between the first and second powder container (36, 39) as seen from the application unit (20) as a temporary overflow container (38), wherein the control unit (50) is intended to move the application unit (20) from the first powder container (36) as powder supply (33) via the substrate platform (16) and the second powder container (39) as overflow container (38) and from there into in the opposite direction, the application unit (20) from the second powder container (39), which is now used as a powder supply (33), via the substrate platform (16) and the first powder container (36), which is now used as an overflow container (38). move. The plant (10) after claim 1 , the powder containers (36, 39) each comprising a mobile powder conveying unit (37) which, controlled by the control unit (50) depending on the mode of operation of the respective powder container (36, 39) as a temporary powder supply (33) or overflow container (38) upwards or drives down. The plant (10) after claim 1 or 2 , wherein the substrate platform (16) controlled by the control unit (50) is lowered after each application by the layer just applied. The system (10) according to one of the preceding claims, wherein the system (10) comprises an excitation unit (40) which is intended to break up adhesions of individual powder grains to one another and/or to a powder layer already treated with the system when the powder is applied, so that the application unit (20) can apply a smooth layer of powder onto the substrate platform (16) and/or onto the previous layer of powder. The plant after claim 4 , wherein the application unit (20) comprises the excitation unit (40). The system (10) of any preceding claim, wherein a first material is provided in the first powder hopper (36) and a second material is provided in the second powder hopper (39) prior to application, the first material being the same as the second material or the first material is different from the second material. The system (10) according to any one of the preceding claims, wherein the quantity of transported powder above the application level of the powder supply (36, 39) has a layer thickness of a factor greater than or equal to 1.2, particularly a factor of 2, particularly preferably a factor of 3 or 4, one Layer thickness of an applied and / or applied layer of powder on the substrate platform (16) corresponds. A method (100) for the additive manufacturing of multidimensional structures by a system (10) according to one of the preceding claims, comprising a spatially movable application unit (20) for powder (30), a powder system (35) for providing the powder and a control unit ( 50) for controlling at least the application unit (20) and the powder system (35), the powder system (35) comprising at least a first powder container (36) and a second powder container (39), comprising the steps: - providing (110) a temporary powder supply (33) and a temporary overflow container (38) alternating through the first (36) and the second powder container (39); - Moving (120) the application unit (20) from the respective powder supply (33) in the direction of the respective overflow container (38) by the control unit (50); - Application (130) of one or more powder layers in an application plane (15) on a substrate platform (16) or on a powder layer already treated with the system using the powder (30) provided by the powder supply (33), the substrate platform (16) is arranged between the powder supply (33) and the overflow container (38); - receiving (140) of excess powder (34) after application by the application unit (20) viewed in the direction of movement beyond the substrate platform (16) through the overflow container (38); and - moving (150) the application unit (20) in the reverse direction, with the former overflow container (38) now being used as a powder supply (33), to the former powder supply (33) now being used as an overflow container (38). The method (100) after claim 8 , comprising a further step of lowering (160) the substrate platform (16) by the control unit (50) by a thickness of the powder layer just applied after each application passing the application unit (20). The method (100) according to one of Claims 8 - 9 , comprising a further step of breaking up (170) adhesions of individual powder grains to one another and/or to a powder layer already treated with the system by an excitation unit during the application of the powder, so that the application unit (20) applies a smooth powder layer to the substrate platform (16) and/or applied to the previous layer of powder. The method (100) according to one of Claims 8 - 10 , wherein steps (110 - 170) are repeated until the multidimensional structure is completely fabricated.

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