POWDER APPLICATION DEVICE, METHOD FOR OPERATING A POWDER APPLICATION DEVICE, AND SYSTEM FOR PRODUCING A THREE-DIMENSIONAL WORKPIECE

Abstract

A powder application device (10) for use in a system (100) for producing a three-dimensional workpiece using a generative layering process comprises a spreading member (12). The spreading member (12) is movable across a surface of a carrier (116) for depositing a raw material powder for producing a workpiece by a generative layering method onto the surface of the carrier (116). Furthermore, the powder application device (10) comprises a powder entrainer (16) which is movable across a carrier plane (E) and which, in the region of a surface (20) facing the carrier plane (E), is provided with a surface profile (22). The surface profile (20) comprises an entraining element (24a, 24b, 24c) and a passage channel (26a, 26b, 26c). The entraining element (24a, 24b, 24c) and the passage channel (26a, 26b, 26c) are shaped and arranged in such a way that, with respect to the movement of the powder entrainer (16) across the carrier plane (E), powdery material deposited in front of the powder entrainer (16) on the carrier plane (E) is entrained by the entraining element (24a, 24b, 24c) during a movement of the powder entrainer (16) across the carrier plane (E) in a first direction of movement (R1), and is guided through the passage channel (26a, 26b, 26c) during a movement of the powder entrainer (16) across the carrier plane (E) in a second direction of movement (R2) opposite to the first direction of movement (R1).

Claims

1-15. (canceled)

16. A powder application device for use in a system for producing a three-dimensional workpiece using a generative layering process, the powder application device comprising: a spreading member movable across a surface of a carrier for depositing a raw material powder for producing a workpiece by a generative layering method onto the surface of the carrier, and a powder entrainer which is movable across a carrier plane and which, in the region of a surface facing the carrier plane, is provided with a surface profile comprising an entraining element and a passage channel, the entraining element and the passage channel being shaped and arranged in such a way that, with respect to the movement of the powder entrainer across the carrier plane, powdery material deposited in front of the powder entrainer on the carrier plane is entrained by the entraining element during a movement of the powder entrainer across the carrier plane in a first direction of movement, and is guided through the passage channel during a movement of the powder entrainer across the carrier plane in a second direction of movement opposite to the first direction of movement.

17. The powder application device according to claim 16, wherein the powder entrainer is fixed to the spreading member and extends in a direction substantially perpendicular to the first and the second direction of movement of the powder entrainer across the carrier plane from a side surface of the spreading member.

18. The powder application device according to claim 16, wherein the surface profile comprises a plurality of entraining elements and a plurality of passage channels arranged between the entraining elements, and wherein at least a part of the entraining elements is designed to be tapered in the region of a, with respect to the movement of the powder entrainer across the carrier plane in the second direction of movement, front end, and/or at least a part of the entraining elements is provided with a powder collecting section in the region of a, with respect to the movement of the powder entrainer across the carrier plane in the first direction of movement, front end.

19. The powder application device according to claim 16, wherein the surface profile comprises a plurality of entraining elements and a plurality of passage channels arranged between the entraining elements, and wherein at least a part of the entraining elements is V-shaped, wedge-shaped and/or hook-shaped.

20. The powder application device according to claim 16, wherein the surface profile of the powder entrainer comprises a first group of entraining elements, which are arranged in a row next to one another in the direction substantially perpendicular to the first and the second direction of movement of the powder entrainer across the carrier plane, wherein a respective passage channel is present between mutually adjacent entraining elements of the first group.

21. The powder application device according to claim 20, wherein the surface profile of the powder entrainer comprises a second group of entraining elements which are arranged in a row next to one another in the direction substantially perpendicular to the first and the second direction of movement of the powder entrainer across the carrier plane and, with respect to the first direction of movement of the powder entrainer across the carrier plane, behind the first group of entraining elements and at least partially in the passage channels present between the entraining elements of the first group.

22. The powder application device according to claim 21, wherein the entraining elements of the second group are shaped and arranged in such a way that they capture and entrain powdery material entering the passageways between the entraining elements of the first group during movement of the powder entrainer across the carrier plane in the first direction of movement.

23. The powder application device according to claim 21, wherein the entraining elements of the second group are shaped and arranged to direct powdery material entering the passageways upon movement of the powder entrainer across the carrier plane in the second direction of movement through the passageways.

24. The powder application device according to claim 21, wherein the entraining elements of the second group, in the direction substantially perpendicular to the first and the second direction of movement of the powder entrainer across the carrier plane, are arranged offset to the entraining elements of the first group, the surface profile of the powder entrainer comprises a third group of entraining elements which are arranged in a row next to one another in the direction substantially perpendicular to the first and the second direction of movement of the powder entrainer across the carrier plane and/or offset relative to the entraining elements of the first and/or of the second group, and/or which, with respect to the first direction of movement of the powder entrainer across the carrier plane, are arranged behind the second group of entraining elements at least partially in passage channels present between the entraining elements of the second group, and/or the entraining elements of the first group, the entraining elements of the second group and/or the entraining elements of the third group are substantially identically shaped.

25. The powder application device according to claim 21, wherein the entraining elements of the second group are completely arranged in the passage channels present between the entraining elements of the first group and/or the entraining elements of the first group and the entraining elements of the second group have a substantially identical basic geometric shape and/or the entraining elements of the second group are smaller than the entraining elements of the first group.

26. A method of operating a powder application device suitable for use in a system for producing a three-dimensional workpiece using a generative layering process, the method comprising the steps of: moving a spreading member across a surface of a carrier to deposit a raw material powder for producing a workpiece by a generative layering method onto the surface of the carrier, and moving a powder entrainer across a carrier plane, wherein the powder entrainer, in the region of a surface facing the carrier plane, is provided with a surface profile comprising an entraining element and a passage channel, the entraining element and the passage channel being shaped and arranged in such a way that, with respect to the movement of the powder entrainer across the carrier plane, powdery material deposited in front of the powder entrainer on the carrier plane is entrained by the entraining element during a movement of the powder entrainer across the carrier plane in a first direction of movement, and is guided through the passage channel during a movement of the powder entrainer across the carrier plane in a second direction of movement opposite to the first direction of movement.

27. The method according to claim 26, wherein the powdery material which, with respect to the movement of the powder entrainer across the carrier plane, is deposited on the carrier plane in front of the powder entrainer, during a movement of the powder entrainer across the surface of the carrier in the first direction of movement, is conveyed into a collecting chamber and/or a collecting area located outside a gas flow-critical area.

28. A system for producing a three-dimensional workpiece using a generative layering process, which comprises a powder application device according to claim 16.

29. The system according to claim 28, further comprising a collecting chamber and/or a collecting area located outside a gas flow-critical area, which is adapted to receive powdery material entrained by the powder entrainer during its movement across the carrier plane in the first direction of movement.

30. The system according to claim 29, wherein the collecting chamber with respect to the movement of the powder entrainer across the carrier plane in the first direction of movement is arranged behind the carrier and/or in the direction substantially perpendicular to the first and the second direction of movement of the powder entrainer across the carrier plane is arranged relative to the carrier.

Description

[0039] The invention is explained in more detail below with reference to the accompanying schematic figures, of which

[0040] FIG. 1 shows a schematic top view of the relevant components of a system for producing a three-dimensional workpiece using a generative layering process,

[0041] FIG. 2 shows a first variant of a surface profile of a powder entrainer, which is used in a powder application device of the system according to FIG. 1,

[0042] FIG. 3 shows a second variant of a surface profile of the powder entrainer used in the powder application device of the system according to FIG. 1, and

[0043] FIG. 4 shows a third variant of an surface profile of the powder entrainer, which is used in the powder application device of the system according to FIG. 1.

[0044] FIG. 1 shows a schematic top view of the relevant components of a system 100 for producing a three-dimensional workpiece using a generative layering process. The system 100 comprises a process chamber 102 and an irradiation device arranged above the process chamber 102, which is not shown in FIG. 1. The process chamber 102 is sealed from the ambient atmosphere so that an inert or reaction gas atmosphere or a pressure reduced from atmospheric pressure can be established in the process chamber 102 if required. For this purpose, the process chamber 102 is connected to a gas circuit 104.

[0045] Gas may be supplied to the process chamber 102 from a gas source 108 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, 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 may contain particulate impurities, 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 from particulate impurities before being circulated through the gas inlet 106 into the process chamber 102.

[0046] A carrier 116 is disposed in the process chamber 102 for receiving raw material powder and the workpiece produced from the raw material powder by a generative layering process. The carrier 116 is vertically displaceable downward relative to the process chamber 102 into a build chamber not illustrated in FIG. 1. Alternatively, a reverse configuration is possible in which the carrier 116 remains stationary while the remaining components are raised.

[0047] A powder application device 10 is movable across the surface of the carrier 116 to apply the raw material powder intended for the manufacture of the workpiece to the surface of the carrier 116 in layers. The powder application device 10 includes a spreading member 12 which, during operation of the powder application device 10, moves in a horizontal direction across the surface of the carrier 116 or a layer of powder already applied to the surface of the carrier 116, thereby applying a new layer of powder. A powder reservoir 14 for receiving the raw material powder to be applied to the carrier 116 is integrated into the spreading member 12 of the powder application device 10 and consequently moves together with the spreading member 12 across the surface of the carrier 116.

[0048] 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 melt fusion or sintering of the particles of the raw material powder, whereby the workpiece is built up layer by layer on the carrier 116 from the raw material powder.

[0049] The irradiation device comprises a beam source, preferably a laser source, emitting for example light at a wavelength of about 1064 nm. The irradiation device further comprises optical elements, such as a scanning unit, a focusing unit and an F-theta lens. The scanning unit is adapted to scan the beam across the top raw material powder layer within a horizontal plane (in x-direction and y-direction). The focusing unit is adapted to change or adjust a focus position of the beam (in the z-direction).

[0050] If desired, the irradiation device may also comprise multiple scanning units and, if necessary, multiple radiation sources.

[0051] Further, the powder application device 10 includes a powder entrainer 16. The powder entrainer 16 is attached to the spreading member 12 and, consequently, moves back and forth in the process chamber 102 together with the spreading member 12. However, since the powder entrainer 16 extends from a side surface 18 of the spreading member 12, the powder entrainer 16, unlike the spreading member 12, does not sweep or travel across the carrier 116, but rather across a carrier plane E. In the embodiment of the apparatus 100 shown in FIG. 1, the carrier plane E is defined by a portion of a bottom plate 118 of the process chamber 102 adjacent to the carrier 116.

[0052] In the area of a surface 20 facing the carrier plane E, the powder entrainer 16 is provided with a surface profile 22. FIGS. 2 to 4 show different variations of the surface profile 22 formed on the surface 20 of the powder entrainer 16. The surface profile 22 includes a plurality of entraining elements 24a, 24b, 24c and a plurality of passage channels 26a, 26b, 26c arranged between the entraining elements 24a, 24b, 24c. The entraining elements 24a, 24b, 24c and the passage channels 26a, 26b, 26c are shaped and arranged in such a way that, with respect to the movement of the powder entrainer 16 across the carrier plane E, powdery material M deposited in front of the powder entrainer 16 on the carrier plane E is entrained by the entraining elements 24a, 24b, 24c during a movement of the powder entrainer 16 across the carrier plane E in a first direction of movement R1. On the other hand, during a movement of the powder entrainer 16 across the carrier plane E in a second direction of movement R2 opposite to the first direction of movement R1, the powdery material M deposited on the carrier plane E is guided through the passage channels 26a, 26b, 26c.

[0053] The paths of movement of the powdery material M relative to the surface profile 22 during a movement of the powder entrainer 16 across the carrier plane E in a first direction of movement R1 are illustrated in FIGS. 2 to 4 by the arrows P1. In contrast, the arrows P2 in FIGS. 2 to 4 illustrate the paths of movement of the powdery material M relative to the surface profile 22 during a movement of the powder entrainer 16 across the carrier plane E in a second direction of movement R2.

[0054] Powdery material M, which accumulates in front of the gas outlet 110 on the carrier plane E, can be removed from this area of the carrier plane E using the powder entrainer 16 and pushed across the carrier plane E by the powder entrainer 16 in the first direction of movement R1 of the powder entrainer 16. At the same time, the powder entrainer 16 is prevented from transporting powdery material M deposited on the carrier plane E into the area of the carrier plane E located in front of the gas outlet 110 during a movement across the carrier plane E in the second direction of movement R2. In this way, an undesirable accumulation of powdery material M in the vicinity of the gas outlet 110 can be avoided.

[0055] As can best be seen from FIGS. 2 to 4, the entraining elements 24a, 24b, 24c formed on the powder entrainer 16 are tapered in the region of a, with respect to the movement of the powder entrainer 16 across the carrier plane E in the second direction of movement R2, front end. As a result, during a movement of the powder entrainer 16 across the carrier plane E in the second direction of movement R2, the powdery 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.

[0056] In contrast, the entraining elements 24a, 24b, 24c are provided with a powder collecting section 28 in the region of a, with respect to the movement of the powder entrainer 16 across the carrier plane E in the first direction of movement R1, front end. In the case of the entraining elements 24a, 24b, 24c illustrated in FIGS. 2 and 3, the powder collecting section 28 is formed in each case by a cavity bounded by side walls of the entraining elements 24a, 24b, 24c. In contrast, the entraining elements 24a, 24b, 24c shown in FIG. 4 each have a powder collecting section 28 formed by a curved surface which, when the powder entrainer 16 moves across 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 entrains it accordingly.

[0057] The entraining elements 24a, 24b, 24c of the surface profile 22 according to FIG. 2 are hook-shaped, while the entraining elements 24a, 24b, 24c of the surface profile 22 according to FIG. 3 are V-shaped. In contrast, the entraining elements 24a, 24b, 24c of the surface profile 22 according to FIG. 4 are wedge-shaped and, as described above, are provided with a powder collecting section 28 defined by a curved surface.

[0058] The entraining elements 24a, 24b, 24c are divided into a plurality of groups in all three surface profile variants shown herein. In particular, each of the surface profiles 22 shown in FIGS. 2 to 4 comprises a first group of entraining elements 24a arranged in a row next to on another in a direction R3 substantially perpendicular to the first and the second direction of movement R1, R2 of the powder entrainer 16 across the carrier plane E. The direction R3, which is perpendicular to the first and the second direction of movement R1, R2, extends parallel to a longitudinal axis L of the powder entrainer 16. A respective passage channel 26a is provided between mutually adjacent entraining elements 24a of the first group.

[0059] Further, each of the surface profiles 22 includes a second group of entraining elements 24b arranged in a row next to on another in the direction R3 substantially perpendicular to the first and the second direction of movement R1, R2. Furthermore, with respect to the first direction of movement R1 of the powder entrainer 16 across the carrier plane E, the entraining elements 24b of the second group are arranged behind the first group of entraining elements 24a, at least partially in the passage channels 26a present between the entraining elements 24a of the first group.

[0060] In the surface profile variant 22 shown in FIG. 2, only a portion of the entraining elements 24b of the second group protrudes into the passage channels 26a provided between the entraining elements 24a of the first group. In contrast, in the surface profile variants shown in FIGS. 3 and 4, the entraining elements 24b of the second group are each completely received in the passage channels 26a present between the entraining elements 24a of the first group.

[0061] However, in all the surface profile variants shown in FIGS. 2 to 4, the entraining elements 24b of the second group are shaped and arranged in such a way that, when the powder entrainer 16 moves across the carrier plane E in the first direction of movement R1, they capture and entrain powdery material M entering the passage channels 26a between the entraining elements 24a of the first group, see arrows P1 in FIGS. 2 to 4. Consequently, when the powder entrainer 16 moves across the carrier plane E in the first direction of movement R1, the entraining elements 24a of the first group first encounter the powdery material M deposited on the carrier plane E. A part of the powdery material M is then already captured and entrained by the entraining elements 24a of the first group, i.e. in particular their powder collecting sections 28. On the other hand, powdery material M which initially enters the passage channels 26a between the entraining elements 24a of the first group encounters the entraining elements 24b of the second group in the further course of the movement of the powder entrainer 16 across the carrier plane E in the first direction of movement R1, and is captured and entrained by these, i.e. in particular their powder collecting sections 28.

[0062] Further, the entraining elements 24b of the second group are shaped and arranged to guide powdery material M entering the passageways 26a during a movement of the powder entrainer 16 across the carrier plane E in the second direction of movement R2 though the passageways 26a, i.e. to allow the powdery material M to pass through the passageways 26a, see arrows P2 in FIGS. 2 to 4.

[0063] In the surface profile 22 shown in FIG. 2, the entraining elements 24a of the first group, with respect to the second direction of movement R2 of the powder entrainer 16 across the carrier plane E, are arranged behind the entraining elements 24b of the second group. Consequently, during a movement of the powder entrainer 16 across the carrier plane E in the second direction of movement R2, first the entraining elements 24b of the second group and only then the entraining elements 24a of the first group encounter the material M deposited on the carrier plane E. In contrast, the surface profiles 22 shown in FIGS. 3 and 4 are designed in such a way that the entraining elements 24b of the second group, with respect to the second direction of movement R2 of the powder entrainer 16 across the carrier plane, are arranged at the same level as the entraining elements 24a of the first group E. In this case, when the powder entrainer 16 moves across the carrier plane E in the second direction of movement R2, the entraining elements 24a, 24b of the first and the second group simultaneously encounter the powdery material M deposited on the carrier 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.

[0064] In the surface profile 22 shown in FIG. 2, the entraining elements 24b of the second group, in the direction R3 substantially perpendicular to the first and the second direction of movement R1, R2 of the powder entrainer 16 across the carrier plane E, are further arranged offset relative to the entraining elements 24a of the first group, whereby an entraining element 24b of the second group projects into each passage channel 26a present between two entraining elements 24a of the first group. Furthermore, the surface profile 22 shown in FIG. 2 comprises a third group of entraining elements 24c. The entraining elements 24c of the third group are arranged in a row next to one another in the direction R3 substantially perpendicular to the first and the second direction of movement R1, R2 of the powder entrainer 16 across the carrier plane E, and offset relative to the entraining elements 24a, 24b of the first and second groups.

[0065] With respect to the first direction of movement R1 of the powder entrainer 16 across the carrier plane E, the entraining elements 24c of the third group are arranged behind the second group 24b of entraining elements and each project into passage channels 26b present between the entraining elements 24b of the second group. Finally, the surface profile 22 shown in FIG. 2 includes passage channels 26c each disposed between two mutually adjacent entraining 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 during a movement of the powder entrainer 6 across the carrier plane E in the second direction of movement R2, see arrows P2 in FIG. 2.

[0066] In the surface profile 22 shown in FIG. 2, the entraining elements 24a of the first group, the entraining elements 24b of the second group and the entraining elements 24c of the third group are identically shaped. In contrast, the entraining elements 24a of the first group and the entraining elements 24b of the second group in the surface profiles 22 according to FIGS. 3 and 4 merely have an identical basic geometric shape, but are of different sizes. In particular, the entraining elements 24b of the second group are smaller than the entraining elements 24b of the first group.

[0067] During operation of the system 100, the powder material M entrained by the powder entrainer 16 during a movement across the carrier plane E in the first direction of movement R1 is conveyed by the powder entrainer 16 into a collecting chamber 120 which, with respect to the movement of the powder entrainer 16 across the carrier plane E in the first direction of movement R1, is arranged behind the carrier 116 and, in the direction R3 substantially perpendicular to the first and the second direction of movement R1, R2 of the powder entrainer 16 across the carrier plane E, offset relative to the carrier 116. Accordingly, the collecting chamber 120 is sufficiently distant from the gas outlet 110 of the process chamber 102.

[0068] The collecting chamber 120 is disposed adjacent to a first overflow chamber 122. The first overflow chamber 122 is for receiving excess raw material powder carried away from the surface of the carrier 116 by the spreading member 12 during movement across the surface of the carrier 116 in the first direction of movement R1. Further, a second overflow chamber 124 is provided for receiving excess raw material powder transported away from the surface of the carrier 116 by the spreading member 12 during movement across the surface of the carrier 116 in the second direction of movement R2.

[0069] The collecting chamber 120 and the first overflow chamber 122 are covered by a common chamber grid 126. However, the collecting chamber 120 is separated from the first overflow chamber 122 by a partition 128. This allows the powdery material M conveyed into the collecting chamber 120 by the powder entrainer 16 to be separated from the excess raw material powder conveyed into the first overflow chamber 122 by the spreading member 12, and discharged separately therefrom from the process chamber 102. The uncontaminated excess raw material powder from the first overflow chamber 122 can then be immediately reused. In contrast, the powdery material M from the collecting chamber 120 can either be disposed of or processed for further use.