Equipment for powder bed fusion

Abstract

To provide an apparatus for powder bed fusion capable of favorably preventing a loosened powder from transferring into an undesired region and of reducing or excluding the fall-off of a foreign matter into a formed constituent element.SOLUTION: An apparatus includes a wall that defines a shaft, a powder platform that supports a powder bed within the shaft and moves through the shaft, and a sealing device that is in a compression state thoroughly from an outer periphery to an inner periphery so as to form a seal between the powder platform and the wall with the outer periphery of the sealing device in contact with the wall and the inner periphery of the sealing device in contact with the powder platform. Another apparatus includes a wall that defines a shaft, a powder platform that supports a powder bed within the shaft and moves through the shaft, and a sealing device that includes a non-fibrous material fixed to the powder platform and allowed to stretch in a manner leaving the powder platform, and that comes in contact with the wall to form a seal between the powder platform and the wall.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to an apparatus and method for powder bed fusion, and more particularly to an apparatus and method for powder bed fusion involving a sealing device. [Background technology]

[0002] Powder bed fusion is an additive manufacturing technique that typically involves a laser or electron beam used to form rigid components (e.g., aircraft components) from a powder bed of material such as metal. The beam is selectively scanned over exposed areas of the powder bed to sinter the powder at desired locations, thereby forming the desired contours of the component. A powder platform supporting the powder bed is then lowered, providing additional powder on top of the powder bed, and the beam is used to form the contours of higher levels of the component, and so on. Summary of the Invention [Problem to be solved by the invention]

[0003] A fibrous material, such as a woven nylon ring, is often used to form a basic seal between the powder platform and the powder bed and shaft surrounding the powder platform. However, loose powder tends to fall past the ring and below the powder platform, typically requiring periodic removal of the powder from below the powder platform. Additionally, friction of the ring rubbing against the shaft can cause the ring to shed fibers onto the powder bed, potentially contaminating and damaging components being formed by the device. Therefore, there is a need for a powder bed fusion device that can better prevent loose powder from migrating to undesired areas and reduce or eliminate the shedding of foreign material into the components being formed. [Means for solving the problem]

[0004] One aspect of the present disclosure is an apparatus for powder bed fusion comprising: a wall defining a shaft; a powder platform supporting the powder bed within the shaft and moving through the shaft; and a sealing device in compression from its outer periphery to its inner periphery such that an outer periphery of the sealing device contacts the wall and an inner periphery of the sealing device contacts the powder platform to form a seal between the powder platform and the wall.

[0005] Another aspect of the present disclosure is an apparatus for powder bed fusion comprising: a wall defining a shaft; a powder platform supporting the powder bed within the shaft and moving through the shaft; and a sealing device comprising a non-fibrous material secured to the powder platform and extending away from the powder platform, the sealing device contacting the wall to form a seal between the powder platform and the wall.

[0006] Another aspect of the present disclosure is a method of performing powder bed fusion, the method including the steps of providing a powder bed supported by a powder platform within a shaft defined by a wall; selectively sintering a portion of an exposed layer of the powder bed; and moving the powder platform downwardly within the shaft while a sealing device maintains a seal between the powder platform and the wall, the sealing device being in compression from an outer periphery of the sealing device in contact with the wall to an inner periphery of the sealing device in contact with the powder platform.

[0007] Another aspect of the present disclosure is a method of performing powder bed fusion, the method including the steps of providing a powder bed supported by a powder platform within a shaft defined by a wall; selectively sintering a portion of an exposed layer of the powder bed; and moving the powder platform downwardly within the shaft while a sealing device maintains a seal between the powder platform and the wall, the sealing device including a non-fibrous material secured to and extending away from the powder platform.

[0008] The terms "about" or "substantially" with respect to a quantity or measurement described herein mean that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including, for example, tolerances, measurement errors, measurement accuracy limits, and other factors known to those skilled in the art, may occur in an amount that does not eliminate the effect that the characteristic was intended to provide.

[0009] The described features, functions, and advantages can be achieved independently in various examples or can be combined in yet other examples, further details of which can be understood with reference to the following description and drawings.

[0010] The novel features believed characteristic of the illustrative examples are set forth in the appended claims. However, the illustrative examples, as well as their preferred modes of use, further objects and explanations, will best be understood by reference to the following detailed description of illustrative examples of the present disclosure, when read in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view of an apparatus, according to an example. [Figure 2] 1 is a perspective view of an apparatus, according to an example. [Figure 3] FIG. 1 is an exploded view of a device, according to an example. [Figure 4] 1 is a perspective view of an apparatus, according to an example. [Figure 5] FIG. 1 is an exploded view of a device, according to an example. [Figure 6] 1 is a cross-sectional view of an apparatus, according to an example. [Figure 7] 1 is a perspective view of an apparatus, according to an example. [Figure 8] FIG. 1 is an exploded view of a device, according to an example. [Figure 9] 1 is a perspective view of an apparatus, according to an example. [Figure 10] FIG. 1 is an exploded view of a device, according to an example. [Figure 11] FIG. 1 is a block diagram of a method, according to an example. [Figure 12] FIG. 1 is a block diagram of a method, according to an example. DETAILED DESCRIPTION OF THE INVENTION

[0012] As discussed above, there is a need for a powder bed fusion apparatus that can better prevent loose powder from migrating to undesired areas and reduce or eliminate the shedding of foreign matter into the component being formed. In some examples, an apparatus for powder bed fusion includes a wall defining a shaft, a powder platform that supports a powder bed (e.g., powder metal) within the shaft and moves through the shaft, and a sealing device that is in compression from its outer periphery to its inner periphery such that an outer periphery of the sealing device contacts the wall and an inner periphery of the sealing device contacts the powder platform to form a seal between the powder platform and the wall.

[0013] In another example, an apparatus for powder bed fusion includes a wall defining a shaft, a powder platform that supports the powder bed within the shaft and moves through the shaft, and a sealing device that is secured to the powder platform and includes a non-fibrous material (e.g., a metal coated with a solid lubricant) that extends away from the powder platform, the sealing device contacting the wall to form a seal between the powder platform and the wall.

[0014] The above-described apparatus can better prevent loose powder from migrating to undesired areas and can reduce or eliminate the shedding of foreign material into the component being formed compared to conventional apparatus for powder bed fusion.

[0015] The disclosed examples will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, of the disclosed examples are shown. Indeed, several different examples may be described and should not be construed as limited to the examples set forth herein. Rather, these examples are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0016] 1 to 10 are schematic diagrams of an apparatus 100 and associated functionality.

[0017] 1 is a cross-sectional view of an apparatus 100 for powder bed fusion. The apparatus 100 includes a wall 102 that defines a shaft 104. The apparatus 100 also includes a powder platform 106 that supports a powder bed 108 within the shaft 104 and moves through the shaft 104. The apparatus 100 also includes a sealing device 110 that is in compression from the outer periphery 112 to the inner periphery 114 such that an outer periphery 112 of the sealing device 110 contacts the wall 102 and an inner periphery 114 of the sealing device 110 contacts the powder platform 106 to form a seal 116 between the powder platform 106 and the wall 102.

[0018] Wall 102 may be formed of metal, although other materials are possible. In the examples described below, wall 102 completely or partially defines shaft 104. That is, wall 102 forms the perimeter of shaft 104. In the examples described below, shaft 104 may have a rectangular, square, or circular shape.

[0019] The powder platform 106 is also typically formed of metal. The powder platform 106 supports the powder bed 108 during the formation of a component from the powder bed 108. The powder platform 106 includes a body 136, a first member 138 that extends away from the body 136 toward the wall 102, and a second member 140 that extends away from the body 136 toward the wall 102 than the first member 138. The body 136, the first member 138, and the second member 140 form a pocket or void into which the sealing device 110 (e.g., the inner periphery 114) fits.

[0020] The powder bed 108 typically comprises powdered metal, although other examples are possible. A laser or electron beam is used to selectively sinter portions of the powder bed 108, layer by layer, to form a component (e.g., an aircraft component). This process is described in more detail below.

[0021] The sealing device 110 can be formed of a bendable or resilient metal. That is, the sealing device 110 can return to its original (e.g., relaxed) shape after being deformed to fit between the wall 102 and the powder platform 106. In FIG. 1 , the sealing device 110 is compressed and applies a force 128 against the wall 102 via the outer periphery 112 and against the powder platform 106 via the inner periphery 114. The sealing device 110 acts as a gasket that forms a seal 116 between the powder platform 106 and the wall 102. The seal 116 generally prevents a significant amount of the powder bed 108 from falling between the wall 102 and the powder platform 106 (e.g., as the powder platform 106 moves up and down).

[0022] The sealing device 110 includes a first arm 142 in contact with the first member 138, a second arm 144 in contact with the wall 102, and a base 146 joining the first arm 142 and the second arm 144 and in contact with the second member 140. When the sealing device 110 is in a compressed state, the first arm 142 deflects toward the second arm 144 and the sealing device 110 stores mechanical energy. For example, the dimensions of the powder platform 106 (e.g., the body 136, the first member 138, and / or the second member 140) may require the sealing device 110 to be in a compressed state to fit between the first member 138, the second member 140, and the wall 102, as shown in FIG. 1 . The compressed state can include any state in which the sealing device 110 is under a compressive force and / or exerting an expansion force on the powder platform 106 and / or the wall 102.

[0023] The periphery 112 includes a non-textile surface 118 that contacts the wall 102. The exterior of the sealing device 110 may be formed with a solid lubricant coating, such as polytetrafluoroethylene, that forms the non-textile surface 118. The periphery 112 substantially conforms to the wall 102.

[0024] A portion 213 of the powder bed 108 between the first arm 142 and the second arm 144 generally pushes the first arm 142 and the second arm 144 away from each other via gravity, thereby contributing to force 128 and forming a more effective seal 116. A portion 215 of the powder bed 108 above the sealing device 110 also contributes to force 128.

[0025] 2 is a perspective view of device 100. As shown, device 100 further includes a second wall 122, a third wall 124, and a fourth wall 126. Shaft 104 has a rectangular shape (e.g., a square shape) defined by wall 102, second wall 122, third wall 124, and fourth wall 126. In applications in which device 100 is used to form components having rectangular symmetry or shape, it may be useful for wall 102, second wall 122, third wall 124, and fourth wall 126 (e.g., shaft 104) to also have rectangular symmetry and / or shape.

[0026] In FIG. 2 , powder platform 106 is shown in dashed lines, and wall 102, second wall 122, third wall 124, and fourth wall 126 are transparent, allowing sealing device 110 to be more easily identified. Additionally, only exposed layer 352 of powder bed 108 is shown. In FIG. 2 , sealing device 110 has a square or rectangular shape that substantially matches wall 102, second wall 122, third wall 124, and fourth wall 126. That is, perimeter 112 forms seal 116 against wall 102, second wall 122, third wall 124, and fourth wall 126. Piston 107 is used to move powder platform 106 up and down through shaft 104 as needed.

[0027] FIG. 3 is an exploded view of the device 100.

[0028] FIG. 4 is a perspective view of apparatus 100 illustrating an example in which apparatus 100, wall 102, and shaft 104 all have circular shapes. In FIG. 4, powder platform 106 is shown in dashed lines, and wall 102 is transparent, allowing sealing device 110 to be more easily identified. Additionally, only exposed layer 352 of powder bed 108 is shown. In FIG. 4, sealing device 110 has a circular shape that substantially matches wall 102. That is, perimeter 112 forms seal 116 with wall 102. In applications in which apparatus 100 is used to form components with rotational symmetry, it may be useful for wall 102 (e.g., shaft 104) to have a circular shape and / or rotational symmetry.

[0029] FIG. 5 is an exploded view of the device 100 shown in FIG.

[0030] 6 is a cross-sectional view of an apparatus 200 for powder bed fusion. The apparatus 200 includes a wall 102 that defines a shaft 104. The apparatus 200 also includes a powder platform 206 that supports a powder bed 108 within the shaft 104 and moves through the shaft 104. The apparatus 200 also includes a sealing device 210 that is secured to the powder platform 206 and includes a non-fibrous material that extends away from the powder platform 206. The sealing device 210 contacts the wall 102 and forms a seal 216 between the powder platform 206 and the wall 102.

[0031] Powder platform 206 may include one or more forms of powder platform 106, although powder platform 206 has a different shape than powder platform 106 as shown.

[0032] Sealing device 210 can include one or more forms of sealing device 110, although sealing device 210 has a different shape than sealing device 110 as shown. Sealing device 210 can include and / or be formed from a non-fibrous material, such as a metal, and can be coated with a solid lubricant, such as polytetrafluoroethylene. In other examples, the non-fibrous material is a foam material or graphite.

[0033] The sealing device 210 acts as a gasket that forms a seal 216 between the powder platform 206 and the wall 102. The seal 216 generally prevents a significant amount of the powder bed 108 from falling between the wall 102 and the powder platform 206 (e.g., as the powder platform 206 moves up and down). The sealing device 210 is configured to scrape powder 154 that has accumulated on the wall 102 from the wall 102 (e.g., as the powder platform 206 moves downward through the shaft 104). For example, the second arm 150 can move relative to the wall 102 as the powder platform 206 moves downward, thereby pushing the powder 154 away from the wall 102 and downward through the shaft 104. In some examples, the powder 154 is completely separated from the wall 102 by the second arm 150 and falls downward through the shaft 104.

[0034] The sealing device 210 includes a first arm 148 that contacts the powder platform 206. As shown, the first arm 148 is bolted onto the powder platform 206. The sealing device 210 also includes a second arm 150 that contacts the wall 102 and a tip 152 that joins the first arm 148 and the second arm 150 and scrapes powder 154 that has accumulated on the wall 102 from the wall 102.

[0035] A portion 213 of the powder bed 108 between the first arm 148 and the second arm 150 generally pushes the first arm 148 and the second arm 150 away from each other via gravity, thereby contributing to force 128 and forming a more effective seal 216. A portion 215 of the powder bed 108 above the sealing device 210 also contributes to force 128.

[0036] The sealing device 210 (eg, the first arm 148 ) is secured to the powder platform 206 via one or more bolts 212 .

[0037] 7 is a perspective view of device 200. As shown, device 200 further includes second wall 122, third wall 124, and fourth wall 126. Shaft 104 has a rectangular shape (e.g., a square shape) defined by wall 102, second wall 122, third wall 124, and fourth wall 126.

[0038] In FIG. 7 , the bottom of powder platform 206 is shown in dashed lines, and wall 102, second wall 122, third wall 124, and fourth wall 126 are transparent, allowing sealing device 210 to be more easily identified. Additionally, only exposed layer 352 of powder bed 108 is shown. In FIG. 7 , sealing device 210 has a square or rectangular shape that substantially matches wall 102, second wall 122, third wall 124, and fourth wall 126. That is, second arm 150 forms seal 216 against wall 102, second wall 122, third wall 124, and fourth wall 126. Piston 107 is used to move powder platform 206 up and down through shaft 104 as needed.

[0039] FIG. 8 is an exploded view of the device 200.

[0040] 9 is a perspective view of apparatus 200 illustrating an example in which apparatus 200, wall 102, and shaft 104 all have a circular shape. In FIG. 9, the bottom of powder platform 206 is shown in dashed lines, and wall 102 is transparent, allowing sealing device 210 to be more easily identified. Additionally, only exposed layer 352 of powder bed 108 is shown. In FIG. 9, sealing device 210 has a circular shape that substantially matches wall 102. That is, second arm 150 forms seal 116 with wall 102.

[0041] FIG. 10 is an exploded view of the device 200 shown in FIG.

[0042] 11 and 12 are block diagrams of methods 300 and 400 for performing powder bed fusion. Methods 300 and 400 provide examples of methods that can be used with apparatus 100 or apparatus 200, such as those shown in FIGS. 1 through 10. As shown in FIGS. 11 and 12, methods 300 and 400 include one or more operations, functions, or actions, as indicated by blocks 302, 304, 306, 402, 404, and 406. While the blocks are shown in sequential order, these blocks may also be performed in parallel and / or in a different order than described herein. Additionally, various blocks may be combined into fewer blocks, divided into additional blocks, and / or eliminated based on the desired implementation.

[0043] At block 302, the method 300 includes providing a powder bed 108 supported by a powder platform 106 within a shaft 104 defined by walls 102. This functionality is described above, for example, with reference to Figures 1-5.

[0044] At block 304, the method 300 includes selectively sintering portions of the exposed layer 352 of the powder bed 108. For example, an electron beam or a laser can be used to selectively sinter the portions of the exposed layer 352 shown in FIGS.

[0045] At block 306, the method 300 includes moving the powder platform 106 downward within the shaft 104 while the sealing device 110 maintains a seal 116 between the powder platform 106 and the wall 102. The sealing device 110 is in compression from an outer periphery 112 of the sealing device 110 in contact with the wall 102 to an inner periphery 114 of the sealing device 110 in contact with the powder platform 106. For example, a piston 107 may be used to lower the powder platform 106 shown in FIGS.

[0046] At block 402, the method 400 includes providing a powder bed 108 supported by a powder platform 206 within a shaft 104 defined by walls 102. This functionality is described above, for example, with reference to Figures 6-10.

[0047] At block 404, the method 400 includes selectively sintering portions of the exposed layer 352 of the powder bed 108. For example, an electron beam or a laser can be used to selectively sinter the portions of the exposed layer 352 shown in FIGS.

[0048] At block 406, the method 400 includes moving the powder platform 206 downward within the shaft 104 while the sealing device 210 maintains the seal 216 between the powder platform 206 and the wall 102. The sealing device 210 is secured to the powder platform 206 and includes a non-fibrous material that extends away from the powder platform 206. For example, a piston 107 may be used to lower the powder platform 206 shown in FIGS. 6-10 .

[0049] Thus, examples of the present disclosure may relate to one of the following listed articles (EC):

[0050] EC1 is an apparatus for powder bed fusion comprising: a wall defining a shaft; a powder platform supporting a powder bed within said shaft and moving through said shaft; and a sealing device in compression from its outer periphery to its inner periphery such that an outer periphery of said sealing device contacts said wall and an inner periphery of said sealing device contacts said powder platform to form a seal between said powder platform and said wall.

[0051] EC2 is the apparatus of EC1, wherein the sealing device comprises a non-textile surface that contacts the wall at the perimeter.

[0052] EC3 is the apparatus of EC2, wherein the non-textile surface comprises a solid lubricant.

[0053] EC4 is the apparatus of any one of EC1 to 3, wherein the wall has a substantially circular shape.

[0054] EC5 is a device described in any one of EC1 to EC3, wherein the wall is a first wall, the device further comprises a second wall, a third wall, and a fourth wall, and the shaft has a rectangular shape defined by the first wall, the second wall, the third wall, and the fourth wall.

[0055] EC6 is the apparatus of any one of EC1 to EC5, wherein the sealing device exerts a force against the wall via the outer periphery and against the powder platform via the inner periphery.

[0056] EC7 is the device of any one of EC1 to EC6, wherein the perimeter substantially conforms to the wall.

[0057] EC8 is the apparatus of any one of EC1 to EC7, wherein the powder platform comprises a body, a first member extending away from the body toward the wall, and a second member extending toward the wall farther from the body than the first member, and the sealing device comprises a first arm in contact with the first member, a second arm in contact with the wall, and a base joining the first arm and the second arm and in contact with the second member.

[0058] EC9 is the apparatus of EC8, wherein a portion of the powder bed between the first arm and the second arm pushes the first arm and the second arm away from each other.

[0059] EC10 is an apparatus for powder bed fusion comprising: a wall defining a shaft; a powder platform supporting a powder bed within said shaft and moving through said shaft; and a sealing device comprising a non-fibrous material secured to said powder platform and extending away from said powder platform, said sealing device contacting said wall to form a seal between said powder platform and said wall.

[0060] EC11 is the apparatus of EC10, wherein the sealing device comprises a first arm that contacts the powder platform, a second arm that contacts the wall, and a tip that joins the first arm and the second arm and scrapes powder accumulated on the wall from the wall.

[0061] EC12 is the apparatus of EC11, wherein a portion of the powder bed between the first arm and the second arm pushes the first arm and the second arm away from each other.

[0062] EC13 is the device of any one of EC10 to 12, wherein the non-fibrous material comprises a foam material.

[0063] EC14 is the device of any one of EC10 to 13, wherein the non-fibrous material comprises graphite.

[0064] EC15 is the apparatus of any one of EC10 to 14, wherein the sealing device has a periphery that substantially conforms to the wall.

[0065] EC16 is the apparatus of any one of EC10 to 15, wherein the non-fibrous material comprises a solid lubricant.

[0066] EC17 is the apparatus of any one of EC10 to 16, wherein the wall has a substantially circular shape.

[0067] EC18 is a device described in any one of EC10 to 16, wherein the wall is a first wall, the device further comprises a second wall, a third wall, and a fourth wall, and the shaft has a rectangular shape defined by the first wall, the second wall, the third wall, and the fourth wall.

[0068] EC19 is the apparatus of any one of EC10 to 18, wherein the sealing device is configured to scrape powder accumulated on the wall from the wall.

[0069] EC20 is a method of performing powder bed fusion, the method including the steps of providing a powder bed supported by a powder platform within a shaft defined by a wall; selectively sintering a portion of an exposed layer of the powder bed; and moving the powder platform downwardly within the shaft while a sealing device maintains a seal between the powder platform and the wall, the sealing device being in compression from an outer periphery of the sealing device in contact with the wall to an inner periphery of the sealing device in contact with the powder platform.

[0070] The description of different advantageous configurations has been presented for purposes of illustration and explanation and is not intended to be exhaustive or limited to the disclosed examples. Many modifications and variations will be apparent to those skilled in the art. Furthermore, different advantageous examples may exhibit different advantages over other advantageous examples. The selected example or examples have been chosen and described to explain the principles, practical applications of the examples, and to enable those skilled in the art to understand the present disclosure of the various examples with various modifications suitable for the particular use contemplated. [Explanation of symbols]

[0071] 100 devices 102 Wall 104 Shaft 106 Powder Platform 107 Piston 108 Powder bed 110 Sealing Devices 112 Outer circumference 114 inner circumference 116 Stickers 118 Non-fibrous surfaces 120 Solid Lubricants 122 The Second Wall 124 The Third Wall 126 The Fourth Wall 128 Power 136 Main Unit 138 First Component 140 Second member 142 First Arm 144 Second Arm 146 base 148 First Arm 150 Second Arm 152 Point 154 Powder 200 equipment 206 Powder Platform 210 Sealing Devices 212 volts 213 Part of the powder bed 215 Part of the powder bed 216 Stickers

Claims

1. An apparatus (100) for powder bed fusion, comprising: a wall (102) defining a shaft (104); a powder platform (106) configured to support a powder bed (108) within said shaft and configured to move through said shaft, a main body (136); a first member (138) extending away from said body toward said wall; a second member (140) extending toward the wall farther from the body than the first member; wherein the body, the first member, and the second member form a cavity; and a sealing device (110) in compression from its outer periphery (112) to its inner periphery such that an outer periphery (112) of the sealing device contacts the wall and an inner periphery (114) of the sealing device contacts the powder platform to form a seal (116) between the powder platform and the wall; Equipped with the sealing device is located within the cavity; The sealing device comprises: a first arm (142) in contact with the first member and positioned within the cavity; a second arm (144) in contact with the wall; a base (146) joining the first arm and the second arm and contacting the second member; Equipped with a portion (213) of the powder bed between the first arm and the second arm exerts a first force on the first arm toward the powder platform and a second force on the second arm toward the wall.

2. The apparatus of claim 1 , wherein the sealing device comprises a non-textile surface (118) in contact with the wall at the perimeter.

3. The apparatus of claim 2 , wherein the non-textile surface comprises a solid lubricant.

4. The device according to claim 1 , wherein the wall has a circular shape.

5. 5. The device of claim 1, wherein the wall is a first wall, the device further comprises a second wall (122), a third wall (124), and a fourth wall (126), and the shaft has a rectangular shape defined by the first wall, the second wall, the third wall, and the fourth wall.

6. 6. The apparatus of claim 1, wherein the sealing device exerts a force (128) against the wall via the outer periphery and against the powder platform via the inner periphery.

7. The device of claim 1 , wherein the perimeter conforms to the wall.

8. 8. The apparatus of claim 1, wherein the sealing device is configured to scrape powder accumulated on the wall from the wall.

9. An apparatus (200) for powder bed fusion, comprising: a wall (102) defining a shaft (104); a powder platform (206) configured to support a powder bed (108) within said shaft and configured to move through said shaft; a sealing device (210) secured to the powder platform and including a non-fibrous material extending away from the powder platform, the sealing device (210) contacting the wall to form a seal (216) between the powder platform and the wall; Equipped with The sealing device comprises: a first arm (148) in contact with the powder platform; a second arm (150) in contact with the wall; Equipped with a portion (213) of the powder bed between the first arm and the second arm exerts a first force on the first arm toward the powder platform and a second force on the second arm toward the wall.

10. 10. The apparatus of claim 9, wherein the portion (213) of the powder bed between the first arm and the second arm pushes the first arm and the second arm away from each other.

11. 11. The device of claim 9 or 10, further comprising a tip (152) joining the first arm and the second arm.

12. 12. The device of claim 11, wherein the tip is configured to scrape powder accumulated on the wall from the wall.

13. 12. The apparatus of claim 9, wherein the sealing device is configured to scrape powder accumulated on the wall from the wall.

14. The apparatus of claim 9 , wherein the sealing device comprises a foam material.

15. The apparatus of claim 9 , wherein the sealing device comprises graphite.

16. 16. Apparatus according to any one of claims 9 to 15, wherein the sealing device has a periphery (234) that conforms to the wall.

17. 17. The apparatus of any one of claims 9 to 16, wherein the sealing device comprises a solid lubricant (120).

18. 18. The device of claim 9, wherein the wall has a circular shape.

19. 19. The apparatus of any one of claims 9 to 18, further comprising a base (146) joining the first arm and the second arm.

20. 20. The apparatus of claim 19, wherein the portion of the powder bed that exerts the first force and the second force additionally exerts a force on the base parallel to the wall.

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