DE102020004503A1 - Device and method for improved powder application in an additive manufacturing process - Google Patents

Abstract

The invention relates to a system (10) for the additive manufacture of multidimensional structures (11) with an application unit (20), such an application unit (20) and a method (100) for applying powder for the additive manufacture of multidimensional structures using such System (10) comprising a spatially movable application unit (20) for powder (30) and an excitation unit (40), the application unit (20) being provided for applying one or more powder layers (31) in an application plane (15) to a substrate platform (16) or to a layer of powder (32) already treated with the system, the excitation unit (40) being provided to prevent individual powder grains (33) from adhering to one another and/or to a layer of powder already treated with the system when the powder (30) is being applied treated powder layer (32) to break up so that the application unit (20) a smooth powder layer (31, 32) on the substrate platform and / or on the previous one Powder layer (32) can apply.

Description

The invention relates to a system for the additive manufacturing of multidimensional structures with an application unit, such an application unit and a method for applying 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 powdered materials is that the powder can have different properties depending on the production or sieving and powder grain size. Between the individual powder grains are interparticle adhesive forces, in particular van der Waals forces, which can exceed their weight by several orders of magnitude. In addition, when applying the powder, shearing forces are generated, which make the surface of the applied powder on the substrate platform irregular, making it difficult to apply the powder smoothly. Ultimately, this also affects the quality of the component to be manufactured.

In order to smooth the surface of the powder, the company 3DMikroPrint, for example, provides techniques where, after the powder has been applied to the substrate plate, contact pressure is again applied to the substrate plate. The company 3D-Systems hingingen uses a roller as a powder application unit.

A disadvantage of these designs is that they are only suitable for large powder grains with a mainly spherical shape. Both with small grain fractions (e.g. less than 20 µm) and with powder with a spattered shape, which is caused by the production and sieving processes of the powder, the agglomeration properties of the powder, e.g. For example, the roller can destroy a powder bed that has already been applied smoothly. When using contact pressure, a robust and stable powder application for small grain fractions is also not given, since e.g. when building filigree structures the contact pressure can destroy component deformations that have already been made.

It would therefore be desirable if a smooth powder application were possible in additive manufacturing, sometimes at least also changing the physical properties of the powder, such as e.g. B. Size and shape are taken into account.

Summary of the Invention

An objective object of the invention is therefore to provide an apparatus which enables smooth powder application in additive manufacturing, with at least the physical properties of the powder, such as e.g. B. Size and shape are taken into account.

This object is achieved by a system for the additive manufacturing of multidimensional structures, comprising a spatially movable application unit for powder and an excitation unit. The application unit is intended to apply one or more powder layers in an application plane to a substrate platform or to a powder layer that has already been treated with the system. When the powder is applied, the excitation unit is intended to break up adhesions of individual powder grains to one another and/or to a powder layer that has already been treated with the system, so that the application unit can apply a smooth powder layer to the substrate platform and/or to the previous powder layer. The poor flowability of the powder is thus overcome in that the forces between the powder grains are temporarily broken with one another by the excitation. In this way, the powder can be stimulated to flow. A stable and robust laser melting process, even with small powder grains and/or with a spattered shape that tend to agglomerate, can thereby be made possible. The shearing force in the direction of the powder layer that has already been applied is then also relatively low, so that delamination (destruction) of the previous powder layer can be avoided.

"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-controlled 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.

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 for building onto a substrate platform. The application unit is designed to be spatially movable relative to the system in order to transport and apply powder from one location to the other. 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 mainly of metal or polymers. 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 e.g. 10 µm or preferably <20 µm. 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.

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 supply according to the invention, with the substrate platform also being configured analogously to a mobile powder conveying unit according to the invention. However, the substrate platform can theoretically also be arranged freely in space.

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 intermittently, 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 be used only 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.

This is a smooth powder application is provided in an additive manufacturing by the system according to the invention, which at least the physical properties of the powder, such. B. Size and shape are taken into account.

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 be done with the help of a gas, such as 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, for example 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, for example, 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 frequency of the excitation can be between 40 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 application unit additionally includes a smoothing tool. The smoothing 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.

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 the sense that the powder can trickle down the sides 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 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.

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 comprise a powder system which provides powder from at least a first powder supply for applying a powder layer by the application unit. The at least first powder supply can have a mobile powder conveyor unit that conveys a quantity of powder to the application level so that it is subsequently applied by the application unit in one or more powder layers to the substrate platform or to a powder layer that has already been treated with the system. In a further embodiment, the application unit can be provided to push excess powder beyond the substrate platform into an overflow container when the powder is applied. In addition, the overflow container can be designed as a second powder supply analogous to the first powder supply. The application unit is intended to apply the quantity of powder alternately from the first and second powder supply with suitable application directions, with the first powder supply also being used as an overflow container. This has the advantage that the excess powder, which is otherwise simply disposed of, can be reused for the application, thus improving the powder use efficiency. For a particularly optimal use for improving the powder use efficiency, the amount of transported powder above the application level of the powder supply can have a layer thickness of a factor greater than or equal to 1.2, preferably a factor of 2, particularly preferably a factor of 3 or 4, a layer thickness of an applied and/or powder layer to be applied correspond to the substrate platform. A powder supply can be designed in the form of a cylinder. Powder supplies and substrate platform (or a container which includes the substrate platform) can be arranged directly next to one another.

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 an application unit for a system according to the invention for the additive manufacturing of multidimensional structures, the application unit being intended to apply one or more powder layers in an application plane to a substrate platform or to a powder layer already treated with the system by means of a spatial movement . The application unit also includes an excitation unit, which is intended to break up adhesions of individual powder grains to one another and/or to a powder layer that has already been treated with the system when the powder is applied, so that the application unit creates a smooth powder layer on the substrate platform and/or on the previous powder layer can apply. The arrangement of the excitation unit in the application unit allows a particularly precise and local excitation of the powder grains when smoothing (at least when applying). Of course, a second smoothing without powder application can also take place. The arrangement brings about an efficient and smooth powder application, particularly supported by a suitable choice of parameters such as the frequency of the excitation unit.

This enables smooth powder application in additive manufacturing by the application unit according to the invention, which at least improves the physical properties of the powder, such as e.g. B. Size and shape are taken into account.

In one embodiment, the excitation unit can include a vibration unit that breaks up the adhesions by means of vibrations. The vibrations can be generated pneumatically and/or electromagnetically and/or by ultrasound. The frequency of the vibrations should not overlap with a resonant frequency of the system so as not to damage the system. In addition, the frequency of the vibration can have a wavelength that correlates with a particle 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, 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 any loss of quality. Therefore, this embodiment can increase manufacturing efficiency. The frequency of the excitation can preferably be between 40 Hz and 100 kHz.

In one embodiment, the application unit according to the invention comprises a smoothing tool, with the smoothing tool preferably comprising a grinding unit, a silicone lip, a plastic bar, a brush and/or a metal edge. The grinding unit particularly preferably has a material with a certain degree of hardness, which is suitable for ultrasonic grinding and/or polishing, with the grinding unit preferably being a conventional grinding stone, which can particularly preferably be made of ceramic. The property of the special hardness of the grinding unit enables it to be used in high frequency ranges, such as ultrasound, as it is particularly stable. The grinding unit can also be made of aluminum oxide or diamond.

In another embodiment, the applicator unit may include a decurling tool holder configured to hold the decurling tool. The smoothing tool holder can be designed in such a way that the smoothing tool, e.g. In this case, the smoothing tool holder can be designed in such a way that the smoothing tool is pushed into it. Depending on the material, the smoothing tool holder can also help to dampen the excitation if, for example, the excitation unit is arranged above the smoothing tool holder. It is advantageous if the smoothing tool holder is made of a soft material that absorbs vibrations well. In an advantageous embodiment, the smoothing tool holder can be integrated into the excitation unit. This can allow for a more compact construction and alternatively the arrangement can contribute to the damping.

In one embodiment, the application unit according to the invention can include a damping unit which is designed to reduce transmission of the excitation to system components of the system outside the excitation unit. In a further embodiment, the application unit according to the invention can comprise a holder which is intended to hold the application unit on guides for executing a defined movement of the application unit, the holder preferably being designed as a damping unit or as part thereof. The damping unit can be designed to connect the holder to the excitation unit. The holder can be made of a soft material that is particularly suitable for absorbing vibrations. This can be a polymer compound and/or a combination of rubber and metal. Therefore, in addition to stabilizing and holding the application unit, the holder can also have the function of contributing to cushioning. This can enable a more compact design. The arrangement can also contribute to the damping of the vibrations.

All features of the application unit according to the invention that correlate with the features of the system according to the invention also have at least the corresponding advantages.

The object is also achieved by a method for the additive manufacturing of multidimensional structures by a system according to the invention, comprising a spatially movable application unit for powder and an excitation unit, comprising the steps: applying one or more powder layers in an application plane on a substrate platform or on an already the powder layer treated by the plant by the application unit; Stimulating and breaking up adhesions of individual powder grains to one another and/or to a layer of powder already treated with the system by the stimulating unit during at least one application, preferably during each application; and smoothing the powder layer by the application unit.

This is a smooth powder application is provided in an additive manufacturing by the inventive method, which at least the physical properties of the powder, such. B. Size and shape are taken into account.

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

In a further embodiment, a method according to the invention has at least one further step of at least a second smoothing by the application unit, which is moved again over the applied powder layer after the powder layer has been applied without further application of powder. This has the advantage that a layer can be smoothed again without further powder application.

According to the invention, it would be advantageous if a method also included a further step of providing powder from at least a first powder supply of a powder system for applying a powder layer by the application unit. In a further embodiment, a method according to the invention comprises a further step of transporting a quantity of powder to the application level by means of a mobile powder conveying unit of the first powder supply, so that this quantity of powder can subsequently be transported from the application unit as the powder layer onto the substrate platform or onto one already connected to the system treated powder layer applies. A method according to the invention can also include a further step of pushing excess powder when applying the powder beyond the substrate platform into an overflow container, preferably the overflow container is a second powder supply. A method according to the invention can preferably include a further step of alternating application of the quantity of powder by the application unit from the first powder supply or the second powder supply, which is configured analogously to the first powder supply, with the first powder supply also being used as an overflow container.

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) System according to the invention when applying powder by means of an application unit; b) Side view of the embodiment of a);
• 2 a) Application unit according to the invention with an excitation unit; b) cross-section of the application unit;
• 3 a) An embodiment of a powder system according to the invention; and b) An embodiment of the powder system according to the invention with a second powder supply;
• 4 An embodiment of the method according to the invention;
• 5 A further embodiment of the method according to the invention;
• 6 a) Plant according to the invention front view; b) powder system embodiment;
• 7 a) Conventionally applied powder coating; b) Powder layer smoothed by a system or application unit according to the invention.

Detailed description of the figures

1 a) shows a system 10 according to the invention when applying powder 30 by means of an application unit 20. The system 10, suitable for the additive manufacturing of multidimensional structures 11, here includes a spatially movable application unit 20 for powder 30. It also includes an excitation unit 40. The application unit 20 is intended to apply one or more powder layers 31 in an application plane 15 to a substrate platform 16 or to a powder layer 32 that has already been treated with the system. The excitation unit 40 is intended to break up adhesions of individual powder grains 33 to each other and/or to a powder layer 32 that has already been treated with the system when the powder 30 is applied, so that the application unit 20 creates a smooth powder layer 31, 32 on the substrate platform 16 and/or on the previous powder layer 32 can apply. 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 . The damping unit 22 can also have the function here accomplish connecting the holder 23 and the decurler holder 24, which is shown by the broken arrows. 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 tool holder and is connected to it (dashed arrow). 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 31 to the substrate platform 16 (if it is the first layer) and otherwise to layers of powder 32 already treated by the plant. A powder layer 32 that has already been treated by the system 10 therefore includes the multidimensional structure 11 that has already been lasered (shaped).

1 b) FIG. 12 shows a side view of the embodiment of FIG 1 a) , wherein the application unit 20 of the system 10 is moved in an application direction 25 during application. The application unit moves at an application speed over the powder layer 32 already treated by the system or the substrate platform 16. Pneumatic and/or electromagnetic and/or ultrasonic vibrations are generated during the application, which break up the adhesions of the individual powder grains 33 to one another. However, the frequency of the vibrations should not overlap with the resonant frequency of the system in order not to damage the system. The breaking up takes place both at and between the applied powder 30, 31 and the powder layer 32 already treated by the plant 10. The frequency of the vibration can have a wavelength that correlates with a particle size of the powder and/or the application speed of the application unit 20 along an application direction 25 . Preferably this frequency is in the range of 40 Hz to 100 kHz. The grain size of an individual powder grain 33 is mostly smaller than 20 μm here. However, a special feature of the system according to the invention compared to the prior art is that it can also provide a smooth layer if part of the powder 30 used has a grain size of less than 2 μm.

2 a) shows an application unit 20 according to the invention for a system 10 according to the invention for the additive manufacturing of multidimensional structures 11, the application unit 20 being provided for the purpose of applying one or more powder layers in an application plane 15 onto a substrate platform 16 or on a substrate platform 16 already connected to the system 10 by means of a spatial movement treated powder layer 32 to apply. The application unit 20 also includes an excitation unit 40, which is intended to break up adhering individual powder grains 33 to one another and/or to a powder layer 32 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 can be applied to the previous layer of powder.

An embodiment of the application unit 20 is shown in cross section in 2 B) illustrated. The excitation unit 40 of the application unit 20 can include a vibration unit that breaks up the adhesions by means of vibrations. The vibration unit can be switched off in the same way as the vibration unit 1 a) and b) be designed. Also analogous to the embodiments in 1 a) and b) a smoothing tool 21 and a smoothing tool holder 24 of the application unit can be configured. The excitation unit 40 can be arranged above the smoothing tool holder 24 . The application unit also includes a damping unit 22 which is designed to reduce transmission of the excitation to system components of the system 10 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 in order to carry out 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 .

3 a) shows a system 10 according to the invention, which comprises a powder system 35 which provides powder 30 from at least a first powder supply for applying a powder layer by the application unit 20 . At least the first powder supply 36 has a mobile powder conveyor unit 37, which conveys a quantity of powder to the application level 15 (e.g. exposure level) so that it can subsequently be transferred from the application unit 20 in one or more layers of powder onto the substrate platform 16 or onto a layer already connected to the Plant treated powder layer 32 can apply. Excess powder 34 is over after application the substrate platform 16 is pushed out into an overflow bin 38 (not shown) and discarded.

3 b) shows an embodiment of the powder system 35, wherein a second powder supply 39, which is configured analogously to the first powder supply 36, represents an overflow container. The application unit 20 is intended to apply the quantity of powder 30 alternately from the first and second powder supply 39 with suitable application directions 25 in each case, with the first powder supply also being used as an overflow container 38 . In the optimal case, the amount of powder transported above the application level of the powder supply 36, 39 corresponds to a layer thickness of a factor of 2, preferably a factor of 3 or 4, a layer thickness of an applied and/or to be applied powder layer on the substrate platform 16. This embodiment enables a particularly efficient Powder utilization as the excess powder can still be used instead of being discarded.

4 shows a method 100 according to the invention for the additive manufacturing of multidimensional structures 11 by a system 10 according to the invention, comprising a spatially movable application unit 20 for powder 30 and an excitation unit 40. The method comprises applying 110 one or more powder layers in an application plane 15 on a substrate platform or a layer of powder already treated with the installation 10 by the application unit 20; stimulating and breaking up 120 adhesions of individual powder grains to one another and/or to a powder layer 32 that has already been treated with the system by the stimulating unit 40 during at least one application, preferably during each application; and a smoothing 130 of the powder layer 31, 32 by the application unit 20.

The inventive method 100 from 5 a) can with further steps that are in 4 b) are shown can be combined to obtain a smooth surface. A further step consists of at least a second smoothing 140 by the application unit 20, which is moved again over the applied powder layer after the application of the powder layer has taken place without further application of powder. The embodiment also includes providing 150 powder from at least a first powder supply 36 of a powder system 35 for application of a powder layer by the application unit 20. A further step includes conveying 160 a quantity of powder to the application level 15 by means of a mobile powder delivery unit 37 of the first powder supply 36 so that this quantity of powder is subsequently applied by the application unit 20 as the powder layer onto the substrate platform 16 or onto a powder layer 32 already treated with the system. The method also includes pushing 170 excess powder 34 into an overflow container 38 when applying the powder beyond the substrate platform 16. The overflow container 38 is preferably a second powder supply 39. A further step includes alternating application 180 of the amount of powder the application unit 20 from the first powder supply 36 or the second powder supply 39, which is configured analogously to the first powder supply 36, the first powder supply 36 also being used as an overflow container 38.

6 a) shows an embodiment of a system 10 according to the invention in a front view. 6 b) Fig. 1 shows a powder system 25 according to the invention with a first powder supply 36 and a second powder supply 39, both of which function as 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.

7 a) 12 shows a layer of powder (or also called the "powder bed") 31 that was applied without smoothing. 7 b) shows a powder layer 31 which was smoothed by an application unit 20 according to the invention in a system 10 according to the invention.

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

Reference List

10

system according to the invention

11

multidimensional structure

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

31

powder layer

32

powder layer already treated by the plant (aka. previous powder layer)

33

single grain of powder

34

excess powder

35

powder system

36

first powder supply

37

mobile powder feed unit

38

overflow tank

39

second powder supply

40

excitation unit

100

inventive method

110...180

Steps according to a method according to the invention

Claims (42)

A system (10) for the additive manufacturing of multi-dimensional structures (11), comprising a spatially movable application unit (20) for powder (30) and an excitation unit (40), the application unit (20) being intended to apply one or more powder layers (31 ) in an application plane (15) on a substrate platform (16) or on a powder layer (32) already treated with the system, wherein the excitation unit (40) is provided to remove adhesions of individual powder grains (33) when the powder (30) is applied to each other and/or to a powder layer (32) already treated with the system, so that the application unit (20) can apply a smooth powder layer (31, 32) to the substrate platform and/or to the previous powder layer (32). The plant (10) after claim 1 , wherein the excitation unit (40) comprises a vibration unit which breaks up the adhesions by means of vibrations. The plant (10) after claim 2 , The vibrations being generated pneumatically and/or electromagnetically and/or by ultrasound. The plant (10) after claim 2 or 3 , whereby the frequency of the vibrations does not overlap with a resonant frequency of the system. The system (10) according to one of claims 2 - 4 , wherein the frequency of the oscillation has a wavelength which correlates with a particle size of the powder and/or an application speed of the application unit along an application direction (25). The plant (10) after claim 4 or 5 , where the excitation frequency is between 40 Hz and 100 kHz. The system (10) according to any one of the preceding claims, wherein the application unit (20) comprises a smoothing tool (21). The plant (10) after claim 7 , wherein the smoothing tool (21) comprises a grinding unit, a silicone lip, a plastic bar, a brush and/or a metal edge. The plant (10) after claim 8 , wherein the grinding unit comprises a material with a certain degree of hardness, which is suitable for ultrasonic grinding and/or polishing, wherein preferably the grinding unit is a conventional grinding stone. The plant (10) after claim 9 , whereby the grinding unit is made of ceramic. The system (10) according to any one of the preceding claims, wherein the excitation unit (40) is arranged stationary relative to the powder layer (32) and/or to the substrate platform (16). The system (10) according to one of Claims 1 - 10 , wherein the excitation unit is arranged to be spatially movable relative to the powder layer (32) and/or to the substrate platform (16). The plant (10) after claim 12 , wherein the application unit comprises the excitation unit. The system (10) according to any one of the preceding claims, comprising a damping unit (22) which is configured to reduce transmission of the excitation to system components external to the excitation unit (40). The system (10) according to one of the preceding claims, wherein the application unit (20) is held via a holder (23) on guides for executing a defined movement of the application unit (20), the holder (23) in the case of the excitation unit (40 ) arranged in the application unit (20) as a damping unit (22) or as part thereof. The plant (10) according to any one of the preceding claims, wherein at least part of the powder (30) used has a property of agglomeration and/or a spattered structure. The plant (10) after Claim 16 , wherein the powder has a grain size of <20 microns, preferably at least a portion of the powder (30) used has a grain size of <2 microns. The system (10) according to any one of the preceding claims, comprising a powder system (35) which provides powder (30) from at least a first powder supply for application of a powder layer by the application unit (20). The plant (10) after Claim 18 , wherein at least the first powder supply (36) has a mobile powder conveying unit (37) which conveys a quantity of powder to the application level (15) so that this can subsequently be transferred from the application unit (20) in one or more layers of powder onto the substrate platform (16) or applies it to a layer of powder (32) that has already been treated with the system. The plant (10) after Claim 18 or 19 , wherein the application unit is provided for the purpose of pushing excess powder (34) over the substrate platform (16) into an overflow container (38) when the powder (30) is applied. The plant (10) after claim 20 , wherein the overflow container (38) represents a second powder supply (39) configured analogously to the first powder supply (36), the application unit (20) being provided for applying the quantity of powder (30) alternately from the first or to apply the second powder supply (39), the first powder supply also being used as an overflow container (38). The system (10) according to one of claims 18 - 21 , the quantity of powder transported above the application level of the powder supply (36, 39) having 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 powder layer applied and/or to be applied on the Substrate platform (16) corresponds. The system (10) according to any one of the preceding claims, which is designed to carry out selective laser melting and/or electron beam melting. An application unit (20) for a system (10) for the additive manufacturing of multidimensional structures (11) according to one of the preceding claims, wherein the application unit (20) is intended to apply one or more powder layers in an application plane (15) by means of a spatial movement applied to a substrate platform (16) or to a powder layer (32) already treated with the system (10), further comprising an excitation unit (40) which is intended to prevent individual powder grains (33) from adhering to one another when the powder is applied and/or or to break up a layer of powder (32) already treated with the plant, 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 application unit (20) after Claim 24 , wherein the excitation unit (40) comprises a vibration unit which breaks up the adhesions by means of vibrations. The application unit (20) after Claim 25 , The vibrations being generated pneumatically and/or electromagnetically and/or by ultrasound. The application unit (20) after Claim 25 or 26 , whereby the frequency of the vibrations does not overlap with a resonant frequency of the system. The application unit (20) according to one of Claims 25 - 27 , wherein the frequency of the oscillation has a wavelength which correlates with a particle size of the powder and/or an application speed of the application unit (20) along an application direction. The application unit (20) after Claim 27 or 28 , where the excitation frequency is between 40 Hz and 100 kHz. The application unit (20) according to any one of the preceding claims, wherein the application unit comprises a smoothing tool (21), preferably the smoothing tool comprises a grinding unit, a silicone lip, a plastic bar, a brush and/or a metal edge, particularly preferably the grinding unit has a Material with a certain degree of hardness, which is suitable for ultrasonic grinding and/or polishing, the grinding unit preferably being a conventional grinding stone, which can particularly preferably be made of ceramic. The application unit (20) according to one of claims 24 - 30 wherein the application unit comprises a decurler holder (24) adapted to hold the decurler (21). The application unit (20) after Claim 31 , wherein the excitation unit is arranged above the smoothing tool holder (24). The application unit (20) after Claim 31 , wherein the smoothing tool holder (24) is integrated into the excitation unit (40). The application unit (20) according to one of claims 24 - 33 , comprising a damping unit (22) which is designed to reduce transmission of the excitation to system components of the system (10) outside the excitation unit (40). The application unit (20) after Claim 34 , wherein the application unit comprises a holder (23) which is intended to hold the application unit (20) on guides to carry out a defined movement of the application unit (20), the holder (23) preferably being designed as a damping unit (22) or as part thereof. The application unit (20) after Claim 34 or 35 , wherein the damping unit (22) is designed to connect the holder (23) to the excitation unit (40). Method (100) for the additive manufacturing of multidimensional structures (11) by a system (10) according to the invention, comprising a spatially movable application unit (20) for powder (30) and an excitation unit (40), comprising the steps: - Application (110) of one or more powder layers in an application plane (15) on a substrate platform or on a powder layer already treated with the system (10) by the application unit (20); - Stimulating and breaking up (120) adhesions of individual powder grains to one another and/or to a powder layer (32) already treated with the system by the stimulating unit (40) during at least one application, preferably during each application; and - Smoothing (130) of the powder layer (31, 32) by the application unit (20). procedure after Claim 37 , comprising a further step of at least a second smoothing (140) by the application unit (20), which is moved again over the applied powder layer after the application of the powder layer has taken place without further application of powder. procedure after Claim 37 or 38 , comprising a further step of providing (150) powder from at least a first powder supply (36) of a powder system (35) for applying a powder layer by the application unit (20). procedure after Claim 39 , comprising a further step of conveying (160) a quantity of powder to the application level (15) by means of a mobile powder conveying unit (37) of the first powder supply (36), so that this quantity of powder is subsequently applied by the application unit (20) as the powder layer the substrate platform (16) or on a powder layer (32) that has already been treated with the system. procedure after Claim 39 or 40 comprising a further step of pushing (170) excess powder (34) when applying the powder beyond the substrate platform (16) into an overflow container (38), preferably the overflow container (38) is a second powder supply (39). procedure after Claim 41 , comprising a further step of alternately applying (180) the amount of powder by the application unit (20) from the first powder store (36) or the second powder store (39), which is designed analogously to the first powder store (36), wherein the first powder supply (36) is used as an overflow container (38).

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