Powder application device, method for operating a powder application device and system for producing a three-dimensional workpiece

Abstract

Powder application device (10) for use in a plant (100) for producing a three-dimensional workpiece using an additive manufacturing process, wherein the powder application device (10) comprises: - a distribution element (12) that is movable over a surface of a carrier (116) in order to apply a raw material powder to the surface of the carrier (116) for the production of a workpiece by means of an additive layer manufacturing process, and - a powder carrier (16) movable over a support plane (E), which is provided in the region of a surface (20) facing the support plane (E) with a surface profile (22) comprising a driving element (24a, 24b, 24c) and a passage channel (26a, 26b, 26c), wherein the driving element (24a, 24b, 24c) and the passage channel (26a, 26b, 26c) are shaped and arranged such that, with respect to the movement of the powder carrier (16) over the support plane (E), powdered material deposited on the support plane (E) in front of the powder carrier (16) is carried along by the driving element (24a, 24b, 24c) when the powder carrier (16) moves over the support plane (E) in a first direction of movement (R1), and when the powder carrier (16) moves over the support plane (E) is guided through the passage channel (26a, 26b, 26c) in a second direction of movement (R2) opposite to the first direction of movement (R1).

Description

[0001] The invention relates to a powder application device for use in a system for producing a three-dimensional workpiece using a generative layer-by-layer process. Furthermore, the invention relates to a method for operating such a powder application device. Finally, the invention relates to a system equipped with such a powder application device for producing a three-dimensional workpiece using a generative layer-by-layer process.

[0002] In additive processes for the production of three-dimensional workpieces, and in particular in additive layering processes, it is known to apply a raw material powder layer by layer to a carrier and to solidify it by site-specific irradiation, e.g., by fusing or sintering, in order to ultimately obtain a workpiece of the desired shape. Irradiation can be carried out using electromagnetic radiation, in particular laser radiation, or particle radiation. Once a workpiece layer has solidified, a new layer of unprocessed raw material powder is applied to the previously produced workpiece layer. Known coating arrangements or powder application devices can be used for this purpose. Subsequently, the now uppermost and still unprocessed raw material powder layer is irradiated again.Consequently, the workpiece is built up successively layer by layer, with each layer defining a cross-sectional area and / or contour of the workpiece. In this context, it is also known to use CAD or comparable workpiece data to produce the workpieces essentially automatically.

[0003] Known devices for producing three-dimensional workpieces can be found, for example, in EP 2 961 549 A1 and EP 2 878 402 A1. The devices described in these documents each comprise a carrier which can be lowered vertically, layer by layer. A corresponding vertical movement of the carrier always takes place in these known devices when a layer of the raw material powder has been completely irradiated and before the next powder layer is applied. This ensures that a focal plane of the irradiation unit is always located in the layer to be solidified (i.e. in the uppermost layer) of the raw material powder. Furthermore, these devices comprise a process chamber connected to a gas circuit. A gas, in particular a protective gas, can be supplied to the process chamber via a gas inlet.After flowing through the process chamber, the gas is discharged from the process chamber via a gas outlet.

[0004] A powder application device is typically used to apply the raw material powder to the carrier. The powder application device comprises a distribution element that can be moved across the surface of the carrier. This distribution element moves over the surface of the carrier or over a powder layer that has already been applied to the surface of the carrier and is at least partially solidified, thereby applying a new layer of powder. The distribution element can comprise a roller, a slider, or another component suitable for applying and distributing the raw material powder onto the carrier. The powder to be applied can be taken from a powder reservoir that is integrated with the distribution element of the powder application device that can be moved across the surface of the carrier.Alternatively, the powder application device can also comprise a stationary powder reservoir, which is arranged, for example, adjacent to the carrier, and from which the distribution element, which can be moved over the carrier, removes powder and distributes it over the surface of the carrier. Powder application devices suitable for use in a system for producing a three-dimensional workpiece using a generative layer-by-layer construction process are described, for example, in EP 2 818 305 B1 or WO 2018 / 029059 A1.

[0005] CN 107 303 608 A discloses a powder application device for a generative layer build-up process. A new, flat powder layer is created by moving a powder distributor in a direction parallel to the new powder layer to be created and distributing accumulated powder in tracks for the new powder layer. For this purpose, the powder distributor is designed with a comb-like design on a front side, with prongs, and a prong divides an upper part of a track with accumulated powder, so that the powder for the new layer is displaced into furrows between the tracks, thus creating a flat powder layer. Excess material from a track with accumulated powder that cannot be absorbed in the furrows is transported away on an upper side of the powder distributor.

[0006] The object of the invention is to provide a powder application device that is suitable for use in a system for producing a three-dimensional workpiece using a generative layer-by-layer process and that facilitates the efficient production of high-quality workpieces. Furthermore, the invention is based on the object of providing a method for operating a powder application device that is suitable for use in a system for producing a three-dimensional workpiece using a generative layer-by-layer process and that facilitates the efficient production of high-quality workpieces. Finally, the invention is directed to the object of specifying a system equipped with such a powder application device for producing a three-dimensional workpiece using a generative layer-by-layer process.

[0007] This object is achieved by a powder application device having the features of patent claim 1, a method for operating a powder application device having the features of patent claim 11 and a system for producing a three-dimensional workpiece having the features of patent claim 13.

[0008] A powder application device for use in a system for producing a three-dimensional workpiece using a generative layer-by-layer process, comprising a distribution element that can be moved across a surface of a carrier to apply a raw material powder to the surface of the carrier for producing a workpiece using a generative layer-by-layer process. The carrier can have a horizontal surface onto which the raw material powder can be applied layer by layer, i.e., in horizontal layers. Furthermore, the carrier can be configured to be lowered vertically, layer by layer.

[0009] A powder reservoir can be integrated with the distribution element of the powder application device, which can be moved across the surface of the carrier, and can also move across the surface of the carrier during operation of the powder application device. By appropriately controlling the powder discharge from the powder reservoir, a desired amount of the raw material powder can then be applied to the carrier during the movement of the distribution element across the surface of the carrier. Alternatively, however, the powder application device can also comprise a stationary powder reservoir, which is arranged, for example, adjacent to the carrier and from which the distribution element of the powder application device withdraws powder and distributes it across the surface of the carrier.

[0010] The raw material powder applied to the carrier can be, for example, a metallic or ceramic raw material powder. The raw material powder can have different particle sizes and particle size distributions depending on the desired properties of the workpiece to be manufactured. However, the particle size of the raw material powder is preferably less than 100 µm.

[0011] The powder application device further comprises a powder carrier movable across a carrier plane. The carrier plane is a plane that extends parallel to the surface of the carrier and, at least in certain operating states of the carrier, for example when the carrier is in its maximum raised position, can also be arranged coplanar with the surface of the carrier and can be at least partially defined by the surface of the carrier. Additionally or alternatively, the carrier plane can be defined by a region of a base plate of a process chamber of the system for producing a workpiece using a generative layer building process, said region being adjacent to the carrier.

[0012] The powder carrier is provided with a surface profile in the region of a surface facing the carrier plane, said surface profile comprising a carrier element and a passage channel. The carrier element and the passage channel are shaped and arranged such that, with respect to the movement of the powder carrier across the carrier plane, powdery material deposited on the carrier plane in front of the powder carrier is carried along by the carrier element when the powder carrier moves across the carrier plane in a first direction of movement. However, when the powder carrier moves across the carrier plane in a second direction of movement opposite to the first direction of movement, the powdery material deposited on the carrier plane is guided through the passage channel.

[0013] The powder carrier is therefore able to entrain powdery material deposited in front of the powder carrier on the carrier plane in relation to the movement of the powder carrier over the carrier plane and to push it over the carrier plane when it moves in the first direction of movement over the surface of the carrier. In contrast, powdery material deposited in front of the powder carrier on the carrier plane in relation to the movement of the powder carrier over the carrier plane remains essentially in its original position when the powder carrier moves in the second direction of movement over the surface of the carrier. The powder carrier can thus be used to remove powdery material that accumulates in a region of the carrier plane from this region by moving the powder carrier in the first direction of movement.At the same time, the powder carrier is prevented from transporting powdery material into this area of ​​the carrier plane when shifted in the second direction of movement.

[0014] During operation of a system for producing a three-dimensional workpiece using a generative layer building process, powder and / or condensate entrained by a gas stream passing through the process chamber can deposit in an area of ​​the support plane adjacent to a gas outlet of the process chamber. This powder and / or condensate can be transported away from the area of ​​the support plane by means of the powder carrier by moving the powder carrier in the first direction of movement and, for example, conveyed into a collecting chute. At the same time, the design of the surface profile of the powder carrier prevents powder and / or condensate particles from being undesirably transported into the area of ​​the support plane adjacent to the gas outlet when the powder carrier is moved in the second direction of movement.

[0015] This prevents the gas flow through the gas outlet from being impeded by the accumulation of powder and / or condensate on the support plane in the area of ​​the gas outlet. Furthermore, contamination of the gas flow leading out of the process chamber via the gas outlet by powder and / or condensate particles accumulating in the area of ​​the gas outlet is minimized. A gas filter, which is located in a gas discharge line connected to the gas outlet and serves to filter particulate contaminants from the gas flow flowing through the gas discharge line, is thus protected from premature clogging. The powder application device thus facilitates the efficient production of a high-quality three-dimensional workpiece using a generative layering process.

[0016] In principle, the distribution element and the powder carrier can be formed separately from one another and can be moved separately and independently of one another over the surface of the carrier or the carrier plane. Preferably, however, the powder carrier is fastened to the distribution element and is thus moved together with the distribution element during operation of the powder application device. For example, the powder carrier can extend from a side surface of the distribution element in a direction substantially perpendicular to the first and second directions of movement of the powder carrier across the carrier plane. During the joint movement of the distribution element and the powder carrier, the powder carrier then sweeps over a region of the carrier plane which is arranged adjacent to the carrier in the direction substantially perpendicular to the first and second directions of movement of the powder carrier across the carrier plane.

[0017] The surface profile can comprise a plurality of entraining elements and a plurality of passage channels arranged between the entraining elements. Alternatively, a entraining element can be designed such that its shape defines a plurality of passage channels. At least some of the entraining elements of the surface profile provided on the powder driver can be tapered in the region of a front end relative to the movement of the powder driver across the carrier plane in the second direction of movement. "Tapered" can also be understood here as a design of the ends of the entraining elements with a minimal radius.Such a design of the entraining elements ensures that powdery material deposited on the support plane in front of the powder entraining element relative to the movement of the powder entraining element across the support plane in the second direction of movement is guided past the entraining elements into the passage channels located between the entraining elements. It is understood that the tapered end of the entraining elements forms a rear end of the entraining elements when the powder entraining element moves across the support plane in the first direction of movement.

[0018] In contrast, at least some of the entraining elements can be provided with a powder-collecting section in the region of a front end relative to the movement of the powder carrier across the carrier plane in the first direction of movement. As a result, powdery material that is deposited on the carrier plane in front of the powder carrier relative to the movement of the powder carrier across the carrier plane in the first direction of movement is collected and carried along by the entraining elements. It is understood that the end of the entraining elements provided with a powder-collecting section forms a rear end of the entraining elements when the powder carrier moves across the carrier plane in the second direction of movement.

[0019] At least some of the entraining elements can be V-shaped, wedge-shaped and / or hook-shaped. The entraining elements are then oriented in particular such that their tapered end forms a front end with respect to the direction of movement of the powder entraining element over the support plane when the powder entraining element is moved over the support plane in the second direction of movement. As described above, this ensures that when the powder entraining element moves over the support plane in the second direction of movement, powdery material deposited on the support plane is guided, starting from the tapered ends of the entraining elements and along outer surfaces of the entraining elements, into the passage channels present between the entraining elements. A passage cross-section of the passage channels delimited by the outer surfaces of the entraining elements preferably decreases in the second direction of movement of the powder entraining element over the support plane.In a particularly simple embodiment, at least some of the driving elements are designed in the form of a straight line.

[0020] At the same time, the entraining elements are oriented in particular such that their end provided with a powder-collecting section forms a front end relative to the direction of movement of the powder entraining element across the support plane when the powder entraining element is moved across the support plane in the first direction of movement. As described above, this ensures that, when the powder entraining element moves across the support plane in the first direction of movement, powdery material deposited on the support plane is collected and carried along by the powder-collecting sections of the entraining elements.

[0021] In a preferred embodiment of the powder application device, the surface profile of the powder carrier comprises a first group of carrier elements which are arranged next to one another in a row in the direction substantially perpendicular to the first and second directions of movement of the powder carrier across the carrier plane. Between adjacent carrier elements of the first group there is preferably a respective passage channel. The distance between adjacent carrier elements of the first group then determines the dimensions of the passage channels defined between the carrier elements and can, for example, be determined depending on the particle size, the particle size distribution and the tendency to agglomerate of the particles deposited on the carrier plane and, depending on the direction of movement of the powder carrier across the carrier plane, either to be carried along or guided through the passage channels and, if necessary,The height of the powder particles influenced by the process in the process chamber can be selected. The height of the carrier elements can be selected as needed. For example, the carrier elements can be constructed higher to carry more powder if the powder carrier is moved less frequently, e.g., independently of the distribution element, across the carrier plane.

[0022] Furthermore, the surface profile of the powder carrier can comprise a second group of carrier elements, which are arranged next to one another in a row in the direction substantially perpendicular to the first and second movement directions of the powder carrier across the carrier plane. Furthermore, the carrier elements of the second group are preferably arranged behind the first group of carrier elements, with respect to the first movement direction of the powder carrier across the carrier plane, at least partially in the passage channels present between the carrier elements of the first group. When the powder carrier moves across the carrier plane in the first movement direction, the carrier elements of the first group then first strike the powdery material deposited on the carrier plane. A portion of the powdery material is then already carried by the carrier elements of the first group, ieIn particular, their powder collection sections, are collected and carried along. Powder material that initially enters the passage channels between the carrier elements of the first group, however, encounters the carrier elements of the second group as the powder carrier moves further across the carrier plane in the first direction of movement.

[0023] The entrainment elements of the second group are preferably shaped and arranged such that, when the powder entrainment element moves across the carrier plane in the first direction of movement, they capture and entrain powdery material entering the passageways between the entrainment elements of the first group. The entrainment elements of the second group, i.e., in particular their powder entrainment sections, then capture the powdery material not entrained by the entrainment elements of the first group. This ensures that at least a large portion of the powdery material deposited on the carrier plane is entrained when the powder entrainment element moves across the carrier plane in the first direction of movement.

[0024] Furthermore, the entraining elements of the second group are preferably shaped and arranged such that, upon movement of the powder carrier across the support plane in the second direction of movement, they guide powdery material entering the passage channels through the passage channels. In other words, the entraining elements of the second group are preferably shaped and arranged such that they do not close the passage channels, but rather allow the powdery material to pass through the passage channels upon movement of the powder carrier across the support plane in the second direction of movement.

[0025] With respect to the second direction of movement of the powder carrier across the support plane, the carrier elements of the second group can be arranged in front of the carrier elements of the first group. When the powder carrier moves across the support plane in the second direction of movement, the carrier elements of the second group then impact the material deposited on the support plane in front of the carrier elements of the first group.

[0026] Alternatively, however, it is also possible to design the surface profile of the powder carrier such that the carrier elements of the second group are arranged at the same height as the carrier elements of the first group with respect to the second direction of movement of the powder carrier across the carrier plane. In this case, when the powder carrier moves across the carrier plane in the second direction of movement, the carrier elements of the first and second groups simultaneously impact the powdery material deposited on the carrier plane, so that the powdery material is guided past the carrier elements of the second group through the passage channels provided between the carrier elements of the first group.

[0027] In a preferred embodiment of the powder application device, the entraining elements of the second group are arranged offset relative to the entraining elements of the first group in the direction substantially perpendicular to the first and second directions of movement of the powder entrainment device across the support plane. For example, entraining elements of the second group, which are arranged behind the entraining elements of the first group not only relative to the first direction of movement of the powder entrainment device across the support plane, but also relative to the second direction of movement of the powder entrainment device across the support plane, can be arranged offset relative to the entraining elements of the first group in the direction substantially perpendicular to the first and second directions of movement in such a way that a entraining element of the second group is arranged in each passage channel present between two entraining elements of the first group.

[0028] Furthermore, the surface profile of the powder driver can comprise a third group of driver elements. The driver elements of the third group can be arranged next to one another in a row in the direction substantially perpendicular to the first and second directions of movement of the powder driver across the support plane. Additionally or alternatively, the driver elements of the third group can be arranged offset from the driver elements of the first and / or second group in the direction substantially perpendicular to the first and second directions of movement. The driver elements of the third group can be arranged behind the second group of driver elements, at least partially in passage channels present between the driver elements of the second group, with respect to the first direction of movement of the powder driver across the support plane.The carrier elements of the third group then fulfill the same functions with respect to the carrier elements of the second group as described above for the carrier elements of the second group with respect to the carrier elements of the first group. If desired or necessary, the surface profile of the powder carrier can also include additional groups of carrier elements, for example, depending on its area.

[0029] The carrier elements of the first group, the carrier elements of the second group, and / or the carrier elements of the third group can be shaped essentially identically. For example, all carrier elements can be essentially hook-shaped and / or of the same size. The carrier elements of the second group then preferably only partially protrude into the passage channels present between the carrier elements of the first group, while the carrier elements of the third group then similarly preferably only partially protrude into the passage channels present between the carrier elements of the second group.

[0030] In an alternative embodiment of the powder application device, the carrier elements of the second group are arranged entirely within the passage channels present between the carrier elements of the first group. Such a configuration of the carrier elements is suitable, for example, for a surface profile in which the carrier elements of the second group are arranged at the same height as the carrier elements of the first group with respect to the second direction of movement of the powder carrier across the support plane.

[0031] The carrier elements of the first group and the carrier elements of the second group can have a substantially identical basic geometric shape. For example, both the carrier elements of the first group and the carrier elements of the second group can be V-shaped or wedge-shaped. However, the carrier elements of the second group are preferably smaller than the carrier elements of the first group.

[0032] In a method for operating a powder application device suitable for use in a system for producing a three-dimensional workpiece using a generative layer-by-layer process, a distribution element is moved across a surface of a carrier to apply a raw material powder to the surface of the carrier for producing a workpiece using a generative layer-by-layer process. A powder carrier is moved across a carrier plane, wherein the powder carrier is provided with a surface profile in the region of a surface facing the carrier plane. The surface profile comprises a carrier element and a passage channel.The entraining element and the passage channel are shaped and arranged such that, with respect to the movement of the powder driver over the carrier plane, powdery material deposited on the carrier plane in front of the powder driver is entrained in a first direction of movement when the powder driver moves over the carrier plane and is guided through the passage channel when the powder driver moves over the carrier plane in a second direction of movement opposite to the first direction of movement.

[0033] The powdery material deposited on the support plane in front of the powder carrier relative to the movement of the powder carrier over the support plane is preferably conveyed into a collecting shaft and / or a collecting area located outside a gas flow-critical area when the powder carrier moves over the surface of the support in the first direction of movement. The powdery material can be collected in the collecting shaft and subsequently processed or disposed of.

[0034] A system for producing a three-dimensional workpiece using a generative layer building process comprises a powder application device as described above.

[0035] Preferably, the system further comprises a collecting shaft and / or a collecting area located outside a gas flow-critical region, which is configured to receive powdery material entrained by the powder carrier during its movement across the carrier plane in the first direction of movement. With respect to the movement of the powder carrier across the carrier plane in the first direction of movement, the collecting shaft can be arranged behind the carrier.

[0036] The system for producing a three-dimensional workpiece can further comprise at least one overflow chute for receiving excess raw material powder, which is carried along by the distribution element as it moves over the surface of the carrier and pushed from the surface of the carrier into a region of the carrier plane adjacent to the carrier. The system preferably comprises two overflow chutes, which are arranged on either side of the carrier with respect to the movement of the distribution element over the surface of the carrier. The distribution element can then, as it moves over the surface of the carrier in the first direction of movement, convey excess raw material powder from the surface of the carrier into a first overflow chute, which is arranged behind the carrier with respect to the first direction of movement of the distribution element over the surface of the carrier.When moving over the surface of the carrier in the second direction of movement, the distribution element can, however, convey excess raw material powder from the surface of the carrier into a second overflow shaft which is arranged behind the carrier with respect to the second direction of movement of the distribution element over the surface of the carrier.

[0037] The collecting shaft can be arranged adjacent to the first overflow shaft in the direction substantially perpendicular to the first and second directions of movement of the powder carrier across the support plane. If desired, the collecting shaft and the first overflow shaft can be covered by a common shaft grid. However, the collecting shaft is preferably separated from the first overflow shaft by a partition wall. This allows the powdery material conveyed into the collecting shaft by the powder carrier to be separated from the excess raw material powder conveyed into the first overflow shaft by the distribution element. The powdery material from the collecting shaft and the excess raw material powder from the first overflow shaft can then be discharged from the process chamber separately from one another.While the uncontaminated excess raw material powder from the first overflow shaft can then be immediately reused, the powdered material from the collection shaft can either be disposed of or processed for further use.

[0038] The invention is explained in more detail below with reference to the attached schematic figures, of which Fig. 1 shows a schematic plan view of the relevant components of a system for producing a three-dimensional workpiece using a generative layer construction process, Fig. 2 shows a first variant of a surface profile of a powder carrier used in a powder application device of the system according to Fig. 1 is used, Fig. 3 shows a second variant of a surface profile of the powder carrier used in the powder application device of the system according to Fig. 1 is used, and Fig. 4 shows a third variant of an upper wing profile of the powder carrier used in the powder application device of the system according to Fig. 1 is used.

[0039] Fig. Figure 1 shows a schematic top view of the relevant components of a system 100 for producing a three-dimensional workpiece using a generative layer construction process. The system 100 comprises a process chamber 102 and a Fig. 1, an irradiation device (not shown) is arranged above the process chamber 102. The process chamber 102 is sealed from the ambient atmosphere, so that an inert or reactive gas atmosphere, or a pressure lower than atmospheric pressure, can be set in the process chamber 102 as needed. For this purpose, the process chamber 102 is connected to a gas circuit 104.

[0040] Gas from a gas source 108 can be supplied to the process chamber 102 via a gas inlet 106. After flowing through the process chamber 102, the gas is discharged from the process chamber 102 via a gas outlet 110. To convey the gas through the gas circuit 104, a conveying device 112, designed, for example, in the form of a blower, is arranged in the gas circuit 104. Gas discharged from the process chamber 102 via the gas outlet 110 can contain particulate contaminants, such as powder particles, welding fume particles, or condensate particles. Therefore, a gas filter 114 is arranged in the gas circuit 104, through which the gas discharged from the process chamber 102 is passed and freed of particulate contaminants before it is circulated through the gas inlet 106 into the process chamber 102.

[0041] A carrier 116 is arranged in the process chamber 102, which serves to hold the raw material powder as well as the workpiece produced from the raw material powder by a generative layer construction process. The carrier 116 is arranged vertically downwards relative to the process chamber 102 in a Fig. 1. Alternatively, a reverse configuration is possible, in which carrier 116 remains stationary while the remaining components are raised.

[0042] A powder application device 10 is movable over the surface of the carrier 116 in order to apply the raw material powder intended for producing the workpiece layer by layer to the surface of the carrier 116. The powder application device 10 comprises a distribution element 12, which, during operation of the powder application device 10, moves horizontally over the surface of the carrier 116 or over a powder layer already applied to the surface of the carrier 116, thereby applying a new powder layer. A powder reservoir 14 for receiving the raw material powder to be applied to the carrier 116 is integrated into the distribution element 12 of the powder application device 10 and thus moves together with the distribution element 12 over the surface of the carrier 116.

[0043] The raw material powder applied to the carrier 116 by the powder application device 10 is selectively exposed to the radiation emitted by the irradiation device. The heat input into the raw material powder caused by the irradiation causes the particles of the raw material powder to melt or sinter, whereby the workpiece is built up layer by layer from the raw material powder on the carrier 116.

[0044] The irradiation device comprises a beam source, preferably a laser source, which emits light at a wavelength of approximately 1064 nm, for example. The irradiation device further comprises optical elements, such as a scanning unit, a focusing unit, and an F-theta lens. The scanning unit is configured to scan the beam across the uppermost raw material powder layer within a horizontal plane (in the x-direction and y-direction). The focusing unit is configured to change or adjust a focus position of the beam (in the z-direction). If desired, the irradiation device can also comprise multiple scanning units and possibly also multiple radiation sources.

[0045] Furthermore, the powder application device 10 comprises a powder carrier 16. The powder carrier 16 is attached to the distribution element 12 and consequently moves back and forth together with the distribution element 12 in the process chamber 102. Since the powder carrier 16 extends from a side surface 18 of the distribution element 12, the powder carrier 16, unlike the distribution element 12, does not sweep or move over the carrier 116, but rather a carrier plane E. In the Fig. In the embodiment of the system 100 shown in Figure 1, the support plane E is defined by a region of a base plate 118 of the process chamber 102 adjacent to the support 116.

[0046] In the area of ​​a surface 20 facing the carrier plane E, the powder driver 16 is provided with a surface profile 22. In the Fig. 2 to 4 show various variants of the surface profile 22 formed on the surface 20 of the powder carrier 16. The surface profile 22 comprises a plurality of carrier elements 24a, 24b, 24c and a plurality of passage channels 26a, 26b, 26c arranged between the carrier elements 24a, 24b, 24c. The carrier elements 24a, 24b, 24c and the passage channels 26a, 26b, 26c are shaped and arranged such that, with respect to the movement of the powder carrier 16 across the carrier plane E, powdery material M deposited in front of the powder carrier 16 on the carrier plane E is carried along by the carrier elements 24a, 24b, 24c when the powder carrier 16 moves across the carrier plane E in a first direction of movement R1.When the powder carrier 16 moves over the carrier plane E in a second movement direction R2 opposite to the first movement direction R1, the powdery material M deposited on the carrier plane E is guided through the passage channels 26a, 26b, 26c.

[0047] The movement paths of the powdery material M relative to the surface profile 22 during a movement of the powder carrier 16 over the carrier plane E in a first movement direction R1 are shown in the Fig. 2 to 4 by the arrows P1. In contrast, the arrows P2 in the Fig. 2 to 4 show the movement paths of the powdery material M relative to the surface profile 22 during a movement of the powder driver 16 over the carrier plane E in a second movement direction R2.

[0048] Powdery material M that accumulates in front of the gas outlet 110 on the support plane E can be removed from this area of ​​the support plane E with the help of the powder carrier 16 and pushed over the support plane E by the powder carrier 16 in the first direction of movement R1 of the powder carrier 16. At the same time, the powder carrier 16 is prevented from transporting powdery material M deposited on the support plane E into the area of ​​the support plane E in front of the gas outlet 110 when moving over the support plane E in the second direction of movement R2. This can prevent an undesirable accumulation of powdery material M in the vicinity of the gas outlet 110.

[0049] How best to use the Fig. As can be seen from Figures 2 to 4, the entraining elements 24a, 24b, 24c formed on the powder entraining element 16 are tapered in the region of a front end relative to the movement of the powder entraining element 16 across the support plane E in the second movement direction R2. As a result, the powdered material M can be guided past the entraining elements 24a, 24b, 24c into the passage channels 26a, 26b, 26c present between the entraining elements 24a, 24b, 24c when the powder entraining element 16 moves across the support plane E in the second movement direction R2.

[0050] In contrast, the driving elements 24a, 24b, 24c are provided with a powder collecting section 28 in the region of a front end relative to the movement of the powder driver 16 over the carrier plane E in the first movement direction R1. Fig. 2 and Fig. 3, the powder collecting section 28 is formed by a cavity defined by side walls of the driving elements 24a, 24b, 24c. In contrast, the Fig. 4 each have a powder collecting section 28 which is formed by a curved surface which, when the powder driver 16 moves over the carrier plane E in the first direction of movement R1, comes into contact with the powdery material M deposited on the carrier plane E and accordingly carries it along.

[0051] The driving elements 24a, 24b, 24c of the surface profile 22 according to Fig. 2 are hook-shaped, while the driving elements 24a, 24b, 24c of the surface profile 22 according to Fig. 3 are V-shaped. The driving elements 24a, 24b, 24c of the surface profile 2 20 according to Fig. 4, on the other hand, are wedge-shaped and, as described above, are provided with a powder collecting section 28 defined by a curved surface.

[0052] The carrier elements 24a, 24b, 24c are divided into several groups in all three surface profile variants shown here. In particular, each of the Fig. 2 to 4, a first group of carrier elements 24a are arranged next to one another in a row in a direction R3 substantially perpendicular to the first and second movement directions R1, R2 of the powder carrier 16 across the support plane E. The direction R3 perpendicular to the first and second movement directions R1, R2 extends parallel to a longitudinal axis L of the powder carrier 16. A passage channel 26a is provided between each adjacent carrier element 24a of the first group.

[0053] Furthermore, each of the surface profiles 22 comprises a second group of carrier elements 24b, which are arranged in a row next to one another in the direction R3, which is substantially perpendicular to the first and second movement directions R1, R2. Furthermore, the carrier elements 24b of the second group are arranged behind the first group of carrier elements 24a, at least partially in the passage channels 26a present between the carrier elements 24a of the first group, relative to the first movement direction R1 of the powder carrier 16 across the support plane E.

[0054] At the Fig. 2, only a portion of the carrier elements 24b of the second group protrudes into the passage channels 26a present between the carrier elements 24a of the first group. In contrast, the carrier elements 24b of the second group in the variants shown in the Fig. 3 and Fig. 4 are each completely accommodated in the passage channels 26a present between the driving elements 24a of the first group.

[0055] For all in the Fig. However, in the surface profile variants shown in Figures 2 to 4, the carrier elements 24b of the second group are shaped and arranged in such a way that, when the powder carrier 16 moves over the carrier plane E in the first direction of movement R1 between the carrier elements 24a of the first group, they catch and carry powdery material M entering the passage channels 26a, see arrows P1 in the Fig. 2 to 4. Consequently, when the powder carrier 16 moves across the support plane E in the first direction of movement R1, the carrier elements 24a of the first group initially strike the powdery material M deposited on the support plane E. A portion of the powdery material M is then caught and carried along by the carrier elements 24a of the first group, i.e. in particular their powder collecting sections 28. In contrast, powdery material M initially entering the passage channels 26a between the carrier elements 24a of the first group strikes the carrier elements 24b of the second group as the powder carrier 16 continues to move across the support plane E in the first direction of movement R1, and is caught and carried along by these, i.e. in particular their powder collecting sections 28.

[0056] Furthermore, the driving elements 24b of the second group are shaped and arranged in such a way that, when the powder driver 16 moves over the carrier plane E in the second direction of movement R2, they guide powdery material M entering the passage channels 26a through the passage channels 26a, ie they allow the powdery material M to pass through the passage channels 26a, see arrows P2 in the Fig. 2 to 4.

[0057] In the in the Fig. 2, the carrier elements 24a of the first group are arranged behind the carrier elements 24b of the second group relative to the second movement direction R2 of the powder carrier 16 over the carrier plane E. Consequently, when the powder carrier 16 moves over the carrier plane E in the second movement direction R2, the carrier elements 24b of the second group first and only then the carrier elements 24a of the first group impact the material M deposited on the carrier plane E. In contrast, the carrier elements 24a of the first group are arranged behind the carrier elements 24b of the second group relative to the second movement direction R2 of the powder carrier 16 over the carrier plane E. Fig. 3 and Fig. 4 are designed such that the entraining elements 24b of the second group are arranged at the same height as the entraining elements 24a of the first group with respect to the second direction of movement R2 of the powder entraining element 16 across the support plane E. In this case, when the powder entraining element 16 moves across the support plane E in the second direction of movement R2, the entraining elements 24a, 24b of the first and second groups simultaneously impact the powdery material M deposited on the support plane E, so that the powdery material is guided past the entraining elements 24b of the second group through the passage channels 26a provided between the entraining elements 24a of the first group.

[0058] In the Fig. 2, the carrier elements 24b of the second group are further arranged offset from the carrier elements 24a of the first group in the direction R3, which is substantially perpendicular to the first and second movement directions R1, R2 of the powder carrier 16 across the carrier plane E, wherein a carrier element 24b of the second group projects into each passage channel 26a present between two carrier elements 24a of the first group. Furthermore, the Fig. 2, a third group of carrier elements 24c. The carrier elements 24c of the third group are arranged in a row next to one another in the direction R3, which is substantially perpendicular to the first and second movement directions R1, R2 of the powder carrier 16 across the support plane E, and are offset from the carrier elements 24a, 24b of the first and second groups.

[0059] With respect to the first direction of movement R1 of the powder carrier 16 over the carrier plane E, the carrier elements 24c of the third group are arranged behind the second group 24b of carrier elements and each protrude into passage channels 26b present between the carrier elements 24b of the second group. Finally, the surface profile 22 comprises Fig. 2 passage channels 26c, each arranged between two adjacent carrier elements 24c of the third group. Each passage channel 26a is connected to a passage channel 26b, and each passage channel 26b is in turn connected to a passage channel 26c, so that material M deposited on the carrier plane E can pass successively through the passage channels 26c, 26b, 26a when the powder carrier 6 moves over the carrier plane E in the second movement direction R2, see arrows P2 in Fig. 2.

[0060] In the Fig. 2, the driving elements 24a of the first group, the driving elements 24b of the second group, and the driving elements 24c of the third group are identically shaped. In contrast, the driving elements 24a of the first group and the driving elements 24b of the second group in the surface profiles 22 according to Fig. 3 and Fig. 4 merely have an identical basic geometric shape, but are different sizes. In particular, the carrier elements 24b of the second group are smaller than the carrier elements 24b of the first group.

[0061] During operation of the system 100, the powder material M carried by the powder carrier 16 during a movement across the carrier plane E in the first movement direction R1 is conveyed by the powder carrier 16 into a collecting shaft 120, which is arranged behind the carrier 116 relative to the movement of the powder carrier 16 across the carrier plane E in the first movement direction R1 and offset from the carrier 116 in the direction R3 substantially perpendicular to the first and second movement directions R1, R2 of the powder carrier 16 across the carrier plane E. Accordingly, the collecting shaft 120 is sufficiently far away from the gas outlet 110 of the process chamber 102.

[0062] The collecting shaft 120 is arranged adjacent to a first overflow shaft 122. The first overflow shaft 122 serves to receive excess raw material powder that is transported away from the surface of the carrier 116 by the distribution element 12 during a movement over the surface of the carrier 116 in the first movement direction R1. Furthermore, a second overflow shaft 124 is provided, which serves to receive excess raw material powder that is transported away from the surface of the carrier 116 by the distribution element 12 during a movement over the surface of the carrier 116 in the second movement direction R2.

[0063] The collecting shaft 120 and the first overflow shaft 122 are covered by a common shaft grid 126. However, the collecting shaft 120 is separated from the first overflow shaft 122 by a partition wall 128. This allows the powdered material M conveyed into the collecting shaft 120 by the powder carrier 16 to be separated from the excess raw material powder conveyed into the first overflow shaft 122 by the distribution element 12 and removed from the process chamber 102 separately. The uncontaminated excess raw material powder from the first overflow shaft 122 can then be immediately reused. The powdered material M from the collecting shaft 120, on the other hand, can either be disposed of or processed for further use.

Claims

[1] Powder application device (10) for use in a system (100) for producing a three-dimensional workpiece using a generative layer construction process, the powder application device (10) comprising: - a distribution element (12) which is movable over a surface of a carrier (116) in order to apply a raw material powder to the surface of the carrier (116) for producing a workpiece by a generative layer construction process, and - a powder carrier (16) which is movable over a support plane (E) and which is provided in the region of a surface (20) facing the support plane (E) with a surface profile (22) which comprises a carrier element (24a, 24b, 24c) and a passage channel (26a, 26b, 26c), wherein the carrier element (24a, 24b, 24c) and the passage channel (26a, 26b, 26c) are shaped and arranged such that, with respect to the movement of the powder carrier (16) over the support plane (E), powdery material deposited in front of the powder carrier (16) on the support plane (E) is carried along by the carrier element (24a, 24b, 24c) during a movement of the powder carrier (16) over the support plane (E) in a first direction of movement (R1), and during a movement of the powder carrier (16) is guided over the support plane (E) in a second movement direction (R2) opposite to the first movement direction (R1) through the passage channel (26a, 26b, 26c). [2] Powder application device according to claim 1, wherein the powder driver (16) is fastened to the distribution element (12) and extends in particular in a direction (R3) substantially perpendicular to the first and second movement directions (R1, R2) of the powder driver (16) across the support plane (E) from a side surface of the distribution element (12). [3] Powder application device according to claim 1 or 2, wherein the surface profile (22) comprises a plurality of carrier elements (24a, 24b, 24c) and a plurality of passage channels (26a, 26b, 26c) arranged between the carrier elements (24a, 24b, 24c), and wherein - at least some of the driving elements (24a, 24b, 24c) are tapered in the region of a front end relative to the movement of the powder driver (16) over the carrier plane (E) in the second direction of movement (R2), and / or - at least some of the entraining elements (24a, 24b, 24c) are provided with a powder collecting section (28) in the region of a front end relative to the movement of the powder entraining element (16) over the carrier plane (E) in the first direction of movement (R1). [4] Powder application device according to one of claims 1 to 3, wherein the surface profile (22) comprises a plurality of driving elements (24a, 24b, 24c) and a plurality of passage channels (26a, 26b, 26c) arranged between the driving elements (24a, 24b, 24c), and wherein at least some of the driving elements (24a, 24b, 24c) are V-shaped, wedge-shaped and / or hook-shaped. [5] Powder application device according to one of claims 1 to 4, wherein the surface profile (22) of the powder driver (16) comprises a first group of driver elements (24a) which are arranged next to one another in a row in the direction (R3) substantially perpendicular to the first and second movement directions (R1, R2) of the powder driver (16) across the support plane (E), wherein a passage channel (26a) is provided between each of the adjacent driver elements (24a) of the first group. [6] Powder application device according to claim 5, wherein the surface profile (22) of the powder driver (16) comprises a second group of driver elements (24b) which are arranged in a row next to one another in the direction (R3) substantially perpendicular to the first and second movement directions (R1, R2) of the powder driver (16) across the support plane (E) and, with respect to the first movement direction (R1) of the powder driver (16) across the support plane (E), behind the first group of driver elements (24a) at least partially in the passage channels (26a) present between the driver elements (24a) of the first group. [7] Powder application device according to claim 6, wherein the entraining elements (24b) of the second group are shaped and arranged such that, when the powder entraining element (16) moves over the support plane (E) in the first direction of movement (R1), they catch and entrain powdery material entering the passage channels (26a) between the entraining elements (24a) of the first group. [8] Powder application device according to claim 6 or 7, wherein the driving elements (24b) of the second group are shaped and arranged such that they guide powdery material entering the passage channels (26a) through the passage channels (26a) when the powder driver (16) moves over the support plane (E) in the second direction of movement (R2). [9] Powder application device according to one of claims 6 to 8, wherein - the carrier elements (24b) of the second group are arranged offset from the carrier elements (24a) of the first group in the direction (R3) substantially perpendicular to the first and second movement directions (R1, R2) of the powder carrier (16) across the carrier plane (E), - the surface profile (22) of the powder driver (16) comprises a third group of driver elements (24c) which are arranged in a row next to one another and / or offset from the driver elements (24a, 24b) of the first and / or second group in the direction (R3) substantially perpendicular to the first and second movement directions (R1, R2) of the powder driver (16) across the support plane (E), and / or which are arranged behind the second group of driver elements (24b) at least partially in passage channels (26bc) present between the driver elements (24b) of the second group, relative to the first movement direction (R1) of the powder driver (16) across the support plane (E), and / or - the driving elements (24a) of the first group, the driving elements (24b) of the second group and / or the driving elements (24c) of the third group are substantially identically shaped. [10] Powder application device according to one of claims 6 to 8, wherein - the driving elements (24b) of the second group are arranged completely in the passage channels (26a) present between the driving elements (24a) of the first group and / or - the driving elements (24a) of the first group and the driving elements (24b) of the second group have a substantially identical basic geometric shape and / or the driving elements (24b) of the second group are smaller than the driving elements (24a) of the first group. [11] Method for operating a powder application device (10) suitable for use in a system (100) for producing a three-dimensional workpiece using a generative layer construction process, the method comprising the following steps: - moving a distribution element (12) over a surface of a carrier (116) in order to apply a raw material powder to the surface of the carrier (116) for producing a workpiece by a generative layer construction process, and - Moving a powder carrier (16) over a support plane (E), wherein the powder carrier (16) is provided in the region of a surface (20) facing the support plane (E) with a surface profile (22) which comprises a carrier element (24a, 24b, 24c) and a passage channel (26a, 26b, 26c), wherein the carrier element (24a, 24b, 24c) and the passage channel (26a, 26b, 26c) are shaped and arranged such that, with respect to the movement of the powder carrier (16) over the support plane (E), powdery material deposited in front of the powder carrier (16) on the support plane (E) is carried along by the carrier element (24a, 24b, 24c) during a movement of the powder carrier (16) over the support plane (E) in a first direction of movement (R1) and Movement of the powder driver (16) over the carrier plane (E) in a second movement direction (R2) opposite to the first movement direction (R1) is guided through the passage channel (26a, 26b, 26c). [12] Method according to claim 11, wherein the powdery material deposited on the support plane (E) in front of the powder carrier (16) in relation to the movement of the powder carrier (16) over the support plane (E) is conveyed into a collecting shaft (120) and / or a collecting region located outside a gas flow-critical region during a movement of the powder carrier (16) over the surface of the support (116) in the first direction of movement (R1). [13] Plant (100) for producing a three-dimensional workpiece using a generative layer construction process, comprising a powder application device (10) according to one of claims 1 to 10. [14] Plant according to claim 13, further comprising a collecting shaft (120) and / or a collecting region located outside a gas flow-critical region, which is adapted to receive powdery material carried along by the powder carrier (16) during its movement over the carrier plane (E) in the first direction of movement (R1). [15] Plant according to claim 14, wherein the collecting shaft (120) - related to the movement of the powder driver (16) over the carrier plane (E) in the first direction of movement (R1) behind the carrier (116) and / or - is arranged offset from the carrier (116) in the direction (R3) substantially perpendicular to the first and second movement directions (R1, R2) of the powder driver (16) across the carrier plane (E).

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