WO2022231570A1

WO2022231570A1 - Build unit housing devices

Info

Publication number: WO2022231570A1
Application number: PCT/US2021/029229
Authority: WO
Inventors: Victor RUIZ RIVAS; Andreu OLIVER GONZALEZ; Marti SALA CASANOVAS
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2021-04-26
Filing date: 2021-04-26
Publication date: 2022-11-03

Abstract

According to an example, a device is for sealing a print chamber of an additive manufacturing device from a build unit. The device comprises a surface and the surface comprises an opening. The device further comprises a three-dimensional volume bounded by the surface which is for receipt of the build unit for use in an additive manufacturing process. The opening in the surface is to permit fluid communication between the three-dimensional volume and the print chamber of the additive manufacturing device. The device also comprises a cover which is movable between a first position in which the cover seals the opening of the device to seal the print chamber from the volume, and a second position in which the opening is at least partially uncovered.

Description

BUILD UNIT HOUSING DEVICES

BACKGROUND [0001] Some additive manufacturing systems generate three-dimensional objects on a layer-by-layer basis through the selective solidification of build material.

BRIEF DESCRIPTION OF DRAWINGS

[0002] Examples will now be described, by way of non-limiting example, with reference to the accompanying drawings, in which:

[0003] Figures 1 A and 1 B are simplified schematics of an example device;

[0004] Figures 2A and 2B are cross-sections through the devices of Figures 1A and 1 B, respectively;

[0005] Figures 3A and 3B are a simplified schematics of an example cover; [0006] Figures 4A and 4B are simplified schematics of an example cover;

[0007] Figure 4C is a simplified schematic of an example cleaning element;

[0008] Figures 5A and 5B are simplified schematics of an example frame; and [0009] Figure 6 is a simplified schematic of an example housing. DETAILED DESCRIPTION

[0010] Additive manufacturing techniques may generate a three-dimensional object through the solidification of a build material. In some examples, the build material may be a powder-like granular material, which may for example be a plastic, ceramic or metal powder. The properties of generated objects may depend on the type of build material and the type of solidification mechanism used. Build material may be deposited, for example on a print bed and processed layer by layer. According to one example, a suitable build material may be PA12 build material commercially known as V1 R10A “HP PA12” available from HP Inc.

[0011] In some examples, selective solidification is achieved through directional application of energy, for example using a laser or electron beam to solidify build material to which the directional energy is applied. A print agent, for example, a ‘coalescence agent’ or ‘coalescing agent’ (which may comprise a fusing agent in examples where the build material comprises a plastics powder, or a binder agent in examples where the build material comprises a metal powder, e.g. comprising stainless steel) may be selectively distributed onto portions of a layer of build material in a pattern derived from data representing a slice of a three-dimensional object to be generated (which may be generated from structural design data). The fusing agent may have a composition which absorbs energy such that, when energy (e.g., heat) is applied to the layer, the plastic build material coalesces and solidifies to form a slice of the three-dimensional object in accordance with the pattern. The binder agent may have a composition that, when heated or when UV energy is applied, causes the particles of build material to which binder agent is applied to adhere to one another. In other examples, coalescence may be achieved in some other manner. The generation of objects through the selective solidification of a build material may therefore involve depositing build material in layers on a print bed, or build platform, and selectively depositing a print agent, for example using printheads to jet the agent, onto portions of a layer of build material. When heat is applied to a layer of build material, those portions of build material to which fusing agent (or binder agent) was applied will heat and coalesce.

[0012] This layer-wise deposition of build material may be accomplished by a recoater that is movable within a print chamber (or a fabrication chamber) of an additive manufacturing apparatus. A build unit, comprising a movable build platform, may be disposed underneath the print chamber of the additive manufacturing apparatus. The movable recoater can move in a back-and-forth manner in passes and, in a first pass, may be to deposit a layer of build material onto a build platform thereunder through an opening in a bottom surface of the print chamber, while a movable carriage comprising printheads may move in a back-and-forth manner in passes to deposit a print agent onto the build material. For the additive manufacturing process to take place, an open, top, surface of the build unit is exposed to an open, bottom, surface of the print chamber, thereby exposing the build unit to a number of elements of the additive manufacturing apparatus (such as material recoater mechanism, a printhead, a heating and/or fusing lamp etc.). A build material comprising plastic particles may be stored in the build unit below the platform. A build material comprising metal particles may be supplied from a supply chamber separate to the build unit but that are adjacent to the print chamber. As the layers of build material are deposited through the print chamber opening onto the build platform, a central platform may move downwards in the build unit as the recoater of the additive manufacturing apparatus moves build material from an adjacent platform, creating space for the subsequent layer of build material and ensuring that the final 3D-printed volume is contained in the build unit, which may then be sealed and removed, and a new build unit may be inserted into the apparatus for a subsequent print operation.

[0013] Removing the build unit from the additive manufacturing apparatus following the conclusion of a print operation may create a risk that build material contained in the print chamber could come into contact with a user. Some examples herein relate to providing an apparatus, which may be part of the additive manufacturing apparatus or which may be standalone apparatus, that is able to seal the opening of the print chamber from a volume therebelow (for example, that may contain a build unit) to prevent build material from migrating out of the print chamber and to contain the build material in the print chamber. In these examples, a three-dimensional volume which is to receive the build unit may therefore be sealed from the print chamber meaning that a user can access this volume (e.g. to remove the build unit and/or to install a new build unit) and do so safely since the print chamber is sealed. The opening may therefore comprise a passage, or area of interaction, between an internal volume of the device and an additive manufacturing apparatus (e.g. a print chamber thereof), said passage being able to be sealed by the cover. A cover, or sheet, for example a flexible element may seal the opening and may comprise a first position where the cover is to seal the opening and a second position where the opening is at least partially uncovered. The first position may comprise a deployed, or advanced, position and the second position may comprise a stowed, or retracted, position. The cover, in its first position, may comprise an orientation that is 90- degrees to its orientation when in the second position, such that the cover, in its second position, may be remote from the opening. Having regard to an orientation of the device when in use, the cover, in its first position, may be horizontal and the cover, in its second position, may be vertical. The seal provided by the cover may be an air-tight or hermetic seal and may therefore be able to maintain an internal environment of the print chamber at a target level (e.g. at a target temperature or pressure), and the seal may therefore provide a thermal or pressure-tight seal.

[0014] Figures 1A and 1 B show perspective views of an example device 100 and Figures 2A and 2B show side cross-sections through the middle of the Figure 1A and 1 B devices. The device 100 is for sealing a print chamber, indicated at 150 in Figures 2A and 2B, of an additive manufacturing device from a build unit (not shown). As shown in Figures 2A and 2B, the print chamber 150 is disposed above the device 100. The device 100 comprises a surface 102, which may comprise a top surface having regard to an orientation of the device in use. The surface 102 comprising an opening 104 which is depicted in the figures as being a substantially rectangular opening but which may comprise an opening of any shape. The device 100 comprises, or defines, a three- dimensional volume 101 which is bounded, at least partially, by the surface 102, and which is for receipt of a build unit. The device 100 is therefore for receipt of a build unit, the build unit being receivable in the three-dimensional volume 101 . The opening 104 in the surface 102 is to permit fluid between the three-dimensional volume 101 and the print chamber 150 of the additive manufacturing device. The device 100 also comprises a cover 106 which is movable between a first position in which the cover 106 seals the opening 104 of the device 100 to seal the print chamber 150 from the volume 101 , and a second position in which the opening 104 is at least partially uncovered. Figure 1A shows the device 100 with the opening 104 uncovered while Figure 1 B shows the opening 104 covered, e.g. the cover 106 is in its first position in Figure 1 B. Examples of the cover 106 being in its second position, and how it may be movable between positions, will be described later with reference to Figures 3 and 4. As shown in Figures 1A and 1 B the opening 104 in the top surface may be surrounded by at least a part of the surface, depicted as a perimeter or circumferential rim of the surface 102.

[0015] A build unit may be inserted into the device 100, e.g. slidably inserted into the device 100 in the direction of the arrow Y through a side opening 105 in the device, as shown in Figures 1A and 1 B. The device 100 may therefore be for the slidable receipt of a build unit. For this purpose (and as shown in Figures 1A and 1 B) the device 100 may comprise three sidewalls 103a-c and the opening 105 may either be formed by the absence of a fourth sidewall (as shown in Figures 1 A and 1 B), or which may comprise an opening in a fourth sidewall, e.g. a hole in a fourth sidewall for receipt of the unit. The opening 105 may comprise a lateral opening in the device 105. As will be explained below with reference to Figures 3 and 4, in some examples when the cover 106 is in the second position it seal, or at least partially cover, the lateral opening 105 in the device 100 for receipt of the build unit. In this way, in the first position the cover 106 my seal the top opening in the device 100 (permitting a user to access the internal volume) but, during a print operation when the print chamber opening is left unsealed, the lateral opening may be sealed by the cover 106 in its second position, thereby preventing a user from having access to the internal volume during such a print operation. In this way, the cover 106 in its second position may function as a door (e.g. a side door) for the device 100, sealing the internal volume 101 from the exterior of the device 100. The sidewalls 103 may be perpendicular to the top surface 102 of the device 100 such that the sidewalls 103 and top surface 102 are at 90-degrees to one another. In other examples however, the sidewall 103 and top surface 102 may be otherwise oriented, e.g. in some examples the sidewall and/or top surface may comprise a curved surface. As shown in Figure 1 B the cover 106, in its first position sealing the opening, may be parallel with the top surface 102 of the device 100 where, in its second position where the opening 104 is left at least partially (or fully) uncovered, the cover 106 may be parallel to a sidewall of the device 100. The cover 106 in its second position may therefore be 90-degrees to its orientation in the first position. For example, in the first position the cover 106 may adopt a horizontal configuration to seal the (top) opening 104 and in the second position the cover 106 may adopt a vertical configuration to seal the (lateral or side) opening 105, the two openings being perpendicular and therefore the cover’s second position being perpendicular to its orientation in the first position.

[0016] The cover 106 may be retractable to within a sidewall of the device 100 such that its second position may be an at least partially, or fully, stowed or retracted position, and may, in its first position, protrude from a sidewall of the device 100 to cover and seal the opening 104. The cover 106 may be movable between its first or second positions in a number of ways. For example, the cover 106 may be attached to a shaft (e.g. a rotatable shaft) mounted to a portion of the device 100 (e.g. a sidewall or the top surface thereof) such that movement (e.g. rotation) of the shaft causes the cover 106 to move between its first and second positions. In another example, the cover 106 may be attached to a movable belt, the belt being attached to the shaft, such that movement of the shaft causes the cover 106 to move via movement of the belt. This will be expanded upon below. In other examples, the cover 106, in its second position may be retracted (e.g. telescopically retracted) and in its second position may be extended (e.g. telescopically extended) or the cover 106, in its second position, may be wound (e.g. around a shaft) and in its first position may be unwound. Therefore, movement of the cover 106 from its second position to its first position may comprise an extending, or unwinding, movement.

[0017] As shown in Figures 2A and 2B, the device 100 may be receivable in an additive manufacturing device such that the device 100 is disposed beneath a print chamber 150 of the additive manufacturing device. The print chamber 150 comprises a print chamber opening 151 and, when the device 100 is received in the additive manufacturing device, the opening 104, when the cover 106 is in its second position shown in Figures 1 A and 2A forms a passage or conduit between the print chamber 150 and the internal volume 101 of the device 100, thereby permitting fluid communication between the print chamber 150 and the volume 101 . When the cover 106 is in its first position shown in Figures 1 B and 2B the opening 104 is sealed such that this passage is closed and fluid communication between the print chamber 150 and the volume 101 is prevented. Figures 1A and 2A, when the cover 106 is in its second position, may therefore show the device 100 being used in conjunction with the print chamber 150 during a print operation where fluid communication is to be permitted between the chamber 150 and a build unit (received in the internal volume 101), and the opening 104 is therefore left uncovered. However, during times where a user or operator wishes to access the internal volume 101 (such as, for example, prior to a print operation where a user may be inserting a build unit into the volume 101 , or following a print operation where a user may remove a build unit from the volume 101 ), or even during times when no build unit is present in the internal volume 101 , the cover 106 may be in its first position to seal the opening 104, as depicted in Figures 1 B and 2B. As Figure 2B shows, when the cover 106 is in the first position to seal the opening 104, the cover 106 also seals the print chamber 150 from the volume 101 and therefore from the external environment. Any build material contained in the chamber 150 is therefore sealed therein and prevented from migrating into the volume 101 when the cover 106 is in the first position sealing the opening 104. The device 100 can seal the print chamber 150 such that, when a user is accessing the internal volume 101 (e.g. when removing or installing a build unit via the side opening 105) they may do so safely since build material is not permitted to leave in the chamber and come in contact with the user. The opening 104 may comprise a sealing element, such as a gasket, that may comprise a flexible material, such as a resiliently deformable material, such as a foam or a rubber element such that when the cover 106 seals the opening 104 in its first position, a top surface of the cover 106 is in sealing contact with a corresponding sealing element of the opening 104. Therefore, in some examples, in the first position, the cover 106 may be in sealing contact with the opening 104 to seal the opening 104.

[0018] The seal provided by the cover 106, in its first position, may therefore be a fluid-tight seal and the cover 106 may therefore be to fluid-seal the opening 104. The cover 106, in its first position, may be to hermetically seal the opening 104 (put another way, the cover 106, in its first position, may provide a hermetic seal) such that the print chamber 150, when the cover 106 is in the first position, may be held at a pressure or atmosphere. In this way, the cover 106 may seal the print chamber 150 at a setpoint pressure or atmosphere such that the internal conditions of the print chamber 150 may be maintained even when the build unit is being removed. Any one of the sidewalls 103a-c of the device 100 may be sealed against the floor, or ground. In this way, no gaps between the device 100 and the floor or ground may be present such that the internal volume 101 may be sealed against the environment. The cover 106 may also provide a thermal seal such that the print chamber may be maintained at a target temperature. As stated above, however, the cover 106 may be to seal the side opening 105 when in its second position. In the second position the cover 106 may therefore be to seal the internal volume 101 . Therefore, the cover 106 may also be to hermetically seal, or fluid-seal, or thermal or pressure seal the side opening 105. Therefore, in some examples, the cover 106 may be to seal both the openings 104 and 105, e.g. when in a respective position. In this way, in the first position the cover may be to seal the opening 104 and the print chamber 151 (as described above) and, in another position, the cover is to seal the opening 105 and the internal volume 101.

[0019] Figures 3A and 3B show an example cover 306, which may comprise the cover 106 as described above, in a first position (Figure 3A) and in a second position (Figure 3B). In this example, the cover 306 is attached to and windable or rotatable around a rotatable shaft 301 . As indicated by the arrow in Figure 3A, rotation about the shaft in a first direction causes the cover 306 to advance, or extend, and rotation in a second, opposing, direction causes the cover 306 to retract or wind around the shaft 301 . The cover 306, in the first position shown in Figure 3A comprises a first extension, in that the cover 306 extends from the shaft 301 by a first amount or first distance. In the second position the cover 306 extends from the shaft 301 by a second amount, or second distance, being greater than the first. In other words, the cover 306 of the Figure 3 example is such that its first position corresponds to the cover 306 protruding from the shaft 301 by a first amount and that the second position corresponds to the cover 306 protruding from the shaft 301 by a second, greater, amount. In the first position shown in Figure 3A the cover 306 is to seal the opening of the device, the opening of the device being indicated by the dotted box 304. In the second position, however, the cover 306 has further advanced from the shaft and, as indicated by the curved arrow in Figure 3B, has changed its direction. In this example, the cover therefore comprises a movement path from its first position to its second position and the path comprises a change in the direction. Due to the change in direction, a portion of the cover 306 in its second position seals a lateral opening of the device that is for receipt of the build unit (said opening being indicated by the dotted box 313). Therefore, Figure 3 shows one example mechanism according to which the cover 306 in the first position seals a top opening of the device and therefore seals the internal volume from the print chamber and, in the second position, the cover 306 seals a lateral opening of the device and therefore seals the internal volume from the external environment.

[0020] Since, when the cover 306 is in the second position, a passage is permitted between the print chamber 150 and a build unit received in the device, the cover comprises an opening 310. The opening 310 may be comprise a size and/or shape that is substantially equal to the opening 304 in the device. Therefore, in this example, the cover 306 comprises a first portion that is to seal part of the opening 304 in the first position and is to seal part of the opening 305 in the second position, and a second portion which comprises the opening 310 permitting fluid communication between a print unit and the internal volume of the device when in the second position. The opening 310 in the cover may comprise a sealing element such as a gasket.

[0021] Although in the Figure 3 example the cover 306 in its second position extends further from the shaft 301 such that it is longer in the second position than in the first position, in another example the cover 306 in its second position may be wound around the shaft, e.g. having a shorter length in the second position. In this example the cover 306 in its second position may be at least partially retracted or wound around the shaft 301.

[0022] Figure 4A and 4B show an example part of a device 400, which may comprise any of the devices described herein, showing an example cover 406 (which may comprise a cover as describes above) and another example mechanism via which the cover 406 is movable between its first and second positions. Not all of the device 400 is shown for brevity to illustrate the mechanism via which the cover 406 moves but the opening 402 of the device 400 and the internal volume 401 for receipt of a build unit are shown. The device 400 in this example comprises two belts 411 , 412 each forming a closed loop and each extending around a perimeter (e.g. a lateral perimeter having regard to an orientation of the device in use) of the device 400. comprises the surface and opening etc. The device 400 of this example comprises a rotatable shaft 410 which is attached to the device 400 (e.g. a housing thereof such as a wall or rail etc.) and each belt 411 , 412 is attached to the shaft 410. In this way, rotation of the shaft causes the belts 411 , 412 to move. In this example, six pulleys 416 are provided, three of which are associated with each belt 411 , 412, each pully 416 being disposed at a corner of the device. Each belt 411 , 412 is wound around three pulleys 416 such that belt is not attached to the pulleys 416 but is movable about and relative to the pulleys. Each pulley 416 may be to facilitate or encourage movement of the belts 411 , 412. The cover 406 is attached to each belt 411 , 412 such that the rotation of the shaft 410 which causes the belts 411 , 412 to move about the pulleys 416 therefore causes the cover 406 to move relative to the opening. The cover 406 is shown in its first position in Figure 4A sealing the opening 402 and in its second position in Figure 4B in which the opening 402 is (in this example) fully uncovered.

[0023] The shaft 410 is rotatable in first and second opposing direction (e.g. clockwise and anticlockwise), with rotation in the first direction being to advance the cover 406 toward its first (Fig. 4A) position and rotation in the second direction being to advance the cover 406 toward its second (Fig. 4B) position. In the example of Figure 4, two belts 411 , 412 are provided and therefore the cover 406 is attached to the belt at two areas of contact (one for each belt). Each contact area comprises a length and width, the length being substantially equal to the length of the belt and the width being substantially equal to the width of the belt. However, one belt may be provided in some examples. The shape of the belts 411 , 412 may be determined, at least in part, by the number or arrangement of pulleys about which it is wound. Each belt comprises a closed loop such that, in the Figure 4 example, each belt extends substantially around a perimeter of the device. In this way, rotating the shaft in either direction may, after enough rotation, cause the belt to rotate 360 degrees back to its starting point. Each pulley 416 in the Figure 4 examples facilitates a change in direction of the belts 411 , 412. In the Figure 4 example, each belt defines a movement path of the cover 406 in that the cover 406 follows the movement of each belt 411 , 412. The movement path of the cover 406 may comprise a path of the cover 406 between its first and second positions. As indicated by the arrow 415, the movement path comprises a change in direction such that when the cover 406 is in its first position it adopts a different orientation relative to the remainder of the device 400 than in its second position. In this example, in the first position, the cover 406 is ninety degrees to its orientation in the second position. Having the cover 406 change orientations between positions allows for the cover 406 to be remote from the opening 402, as can be seen in Figure 4B. The shaft 410 and pulleys 416 may be rotatably attached to the device 400 (such as a wall or housing or frame element etc. thereof).

[0024] The Figure 4A example depicts the cover 406 in its first position to seal the opening 404, in which the cover 406 is in a horizontal position. In the Figure 4B example the cover 406 is in its second position, which is a vertical position which may, in some examples be to seal a side, or lateral, opening in the device 400 that is to receive the build unit. For example, as discussed above with respect to Figure 3B, the Figure 4B position of the cover may cause the opening in the device to receive the build unit to be sealed, e.g. hermetically or thermally, effectively sealing the internal volume 401 of the device, e.g. at a particular temperature or pressure. In these examples, a user may not be able to access the internal volume when the cover 406 is in the second position shown in Figure 4B. In other examples, in the second position, the cover 406 may be located elsewhere in the device (e.g. parallel to a rear or side wall) and may be remove from the lateral opening for receipt of the build unit. Therefore, in the first position where the cover may be horizontal and parallel to the floor, the cover 406 acts as seal between the print chamber and the build unit volume (and in this case a the user can insert/extract a build unit) and, in the second position, where the cover may be vertical and perpendicular to the floor, the cover may act as a door/seal between a user (or exterior) and the build unit volume (and in this case, the build unit is inside the volume, with the build unit platform and print chamber being connected via the opening 404 since the opening 404 is uncovered, a printing process can start). In other examples, however, in the second position the cover 406 may not seal the side opening and may be disposed parallel to a different side wall of the device 400.

[0025] Figure 4C shows an example of a device 400 (which may comprise any of the devices described herein) comprising a cleaning module 450 which is to clean the cover 406 when the cover 406 moves to its second position. In this example, the cleaning module 450 is disposed such that the cover 406 comes into contact with the cleaning module 450 when advancing from the first position to the second position. In this example the cleaning module 450 is depicted as a wiper whereby, when the cover 406 moves to its second position (as indicated by the arrow 406) the cover 406 comes into contact with the wiper blade which cleans the cover 406 by wiping or scraping any build material remnant deposited thereon. In other examples, the cleaning module 450 may be other than a wiper blade, for example the cleaning module 450 may comprise a vacuum element or source of suction pressure to remove any build material from the cover 406 by negative pressure. In any example, the cleaning device 450 may be disposed along a movement path of the cover 406 so that the cover 406 is cleaned as it transitions from its first to its second position. As the cover 406 moves, build material may be collected and urged towards a contained, for example that a user may empty. The cleaning device 450 may be to clean and/or maintain a surface of the cover 406 that is to come into contact with a user, for example an external surface of the cover 406.

[0026] Figures 5A and 5B show an example frame 500. The frame 500 defines an internal volume 501 for receipt of a (not shown) build unit. The frame 500 comprises a frame element, which may comprise any one of the top rails 510a-d that least partially defines a surface 502 which at least partially bounds the internal volume 501 and which defines an opening 504 of the frame 500 for permitting fluid communication between a print chamber of an additive manufacturing device and a build unit received in the internal volume 501 , for example as described above with reference to Figures 1 and 2. The frame 500 also comprises a sheet element 506 that is movable between a stowed and a deployed position. The deployed position of the sheet element 506 is depicted in Figure 5B. In the deployed position of Figure 5B, the sheet element 506 is to seal the opening 504 to prevent fluid communication between the print chamber and a build unit received in the internal volume 510 and, in the stowed position, the opening 504 is at least partially uncovered to permit fluid communication between the print chamber and a build unit received in the internal volume 501. In the deployed position the sheet element 506 may be to hermetically seal the internal volume 501 , for example to maintain a pressure the print chamber of the additive manufacturing device.

[0027] The cover 506 may comprise any of the covers as described above and the deployed and stowed positions may respectively comprise the first and second positions as described above, for example the movement of the cover 506 may be according to any one of the example mechanisms as described above (such that that of Figure 3 or Figure). For example, the sheet element 506 may be attached to a rotatable shaft wherein rotation of the shaft in a first direction causes the sheet element 506 to move toward its stowed position and movement of the shaft in a second direction causes the sheet element to move toward its deployed position, for example as described above with respect to Figure 3 or Figure 4. The flexible sheet 506 may be movable along a movement path between the first and second positions, and wherein the movement path comprises a bend, such as a change in direction as described above with reference to Figure 4. In the stowed and deployed positions, the sheet element 506 may adopt different orientations relative to the internal volume 501 , for example the sheet element 506 in the stowed position may be 90- degrees to its orientation in the deployed position.

[0028] In this example, the frame 500 comprises a frame structure comprising a number of frame elements, or rails. In the Figure 5 example, the frame 500 comprises two opposing sets 510a, 510b and 510c, 51 Od of frame elements defining the top surface 502 of the frame 500. and the opening 504 in this example is defined between frame elements. The frame 500 further comprises four side rails 512a-d, and three bottom rails 513a, 513b, and 513d, a pair of which 513b,d are opposing. In this example, top rail 510a, bottom rail 513a and siderails 512a, b define a first sidewall, top rail 510b, siderails 512b, c, and bottom rail 513b define a second sidewall, and top rail 51 Od, sidewalls 512a,d, and bottom rail 513d define a third sidewall of the device. The top rail 510c and side rails 512c,d define the 505 opening for receipt of the build unit. In other words, the top rail 510 and side rails 512c,d define a fourth sidewall which comprises an opening 505 for receipt of the build unit. The frame of this example therefore comprises frame elements that define six surfaces, including a top and bottom surface and four sidewalls, although, as stated above, the frame may comprise curved frame elements defining curved sidewalls. For example, the frame 500 may comprise a single, solid, frame element comprising an opening through which the build unit is insertable.

[0029] The frame 500 may define all, or part, of any of the devices as described herein. For example, any of the frame elements, alone, or in combination, may define any of a top surface, bottom surface, or sidewall of any of the devices described herein, or any surfaces forming a top, bottom or sidewall of the device may be attached to the frame of the Figure 5 example.

[0030] Figure 6 shows an example build unit housing 600 which may comprise the frame 500 as described above or any of the devices described above, the housing 600 comprising a sidewall 603 having a sidewall opening 605 for receipt of a build unit (not shown) and a volume 601 adjacent the sidewall opening 503 for housing the build unit. The build unit housing 600 comprises an opening 604 in the housing 600 providing a passage between a print chamber of an additive manufacturing device through to the volume 601 of the build unit housing, and into a build unit if a build unit is received in the volume 601 . Further, the housing 600 comprises a movable covering device 606 to cover the opening 604 to thereby prevent build material to pass from the print chamber through to the volume 601 of the build unit housing, the movable covering being movable between advanced and retracted positions, wherein, in the advanced position, the opening 604 is covered by the covering device 606 and, in the retracted position, the opening 604 is at least partially uncovered by the covering device 606. The movable covering device 606 may comprise the cover or sheet as described above with reference to Figures 1-5 and the advanced and retracted positions may respectively comprise the first, or deployed, and second, or stowed, positions as described above.

[0031] The build unit housing 600 further comprises a top surface 602 which comprises the opening 604, the opening is at least partially defined by a housing element (in this example, rear portion of the top surface 602a) and, in the advanced position, the cover 606 protrudes from the housing element 602a to cover the opening 604 and, in the retracted position, the cover 606 is at least partially enclosed by the housing element 602a. Three positions of the covering device 603 are shown in Figure 6 as indicated by the dotted lines. In an advanced, or fully advanced, position the covering device 603 is parallel with the top surface 602 and perpendicular to a rear surface 607, or rear wall, of the housing. In this position the covering device 603 is parallel to the floor and completely covers and seals the opening 604 from the environment. In a fully retracted position the covering device 603 is parallel to the rear surface 607 of the housing 600 and perpendicular to its position in the advanced position. In a partially advanced position, a portion of the covering device 603 is perpendicular to the top surface 602 and another portion is parallel to the top surface 602.

[0032] The build unit housing 600 also comprises a rotatable element 610, which may comprise a shaft, and the cover element 606 is attached to the rotatable element 610 such that wherein movement of the rotatable element 610 causes the cover to transition between its advanced and retracted positions. Rotation of the shaft 610 in a first direction may cause the covering device to move toward its fully advanced position where it fully covers the opening 604 and rotation of the shaft 610 in a second, opposite, direction may cause the covering device to move toward its fully retracted position inside the housing 600. In the retracted position the cover element 606 may be partially, or fully, enclosed by the housing 600. The cover 606, in its second or advanced position, in this example retracts to seal, or cover, the opening 605 for receipt of the build unit. In these examples the rotatable element 610 may be located proximate the opening. The cover element 606 is therefore movable between a position in which it seals the (top) opening 604 to a position in which it seals the (side) opening 605. In other words, the cover element 606 may comprise an intermediate position in which it at least partially seals both openings 604 and 605.

[0033] Apparatuses (e.g. the devices, frame, or housing disclosed herein) may therefore provide a powder containment system to seal (e.g. in a fluid-tight manner or hermetically) an internal volume from the wider environment. In this way, an apparatus disclosed herein may be to separate an area of an additive manufacturing apparatus (such as the print chamber) wherein build material may be present from an external portion of the additive manufacturing apparatus (this external portion being a portion in which apparatuses according to this disclosure are received). Some apparatuses herein therefore are to prevent leakages from a print chamber of an additive manufacturing apparatus by sealing the print chamber. The covers or sheet elements described herein may comprise a flexible element and may comprise a cloth, metal or plastic material or a compound material having flexible properties. Some examples may provide a tensioner to adjust or fix the tension of the cover or sheet element such that it can function as an improved seal to seal any gaps as a result of the cover or sheet element being loose in a particular area. When the cover or sheet element is in its second position a use may clean the internal volume while the opening of the apparatus is sealed or insert or a remove a build unit from the internal volume and may do so safely since the opening of the device that permits fluid communication to the print chamber of the additive manufacturing apparatus is sealed, and therefore powder leakages from the print chamber to the internal volume are eliminated. Moreover, the temperature and/or pressure of the print chamber may also be sealed and therefore maintained at a target level even when the internal volume is being accessed by a user.

[0034] The present disclosure is described with reference to flow charts and/or block diagrams of the method, devices and systems according to examples of the present disclosure. Although the flow diagrams described above show a specific order of execution, the order of execution may differ from that which is depicted. Blocks described in relation to one flow chart may be combined with those of another flow chart.

[0035] While the method, apparatus and related aspects have been described with reference to certain examples, various modifications, changes, omissions, and substitutions can be made without departing from the spirit of the present disclosure. It is intended, therefore, that the method, apparatus and related aspects be limited only by the scope of the following claims and their equivalents. It should be noted that the above- mentioned examples illustrate rather than limit what is described herein, and that those skilled in the art will be able to design many alternative implementations without departing from the scope of the appended claims.

[0036] The word “comprising” does not exclude the presence of elements other than those listed in a claim, “a” or “an” does not exclude a plurality, and a single processor or other unit may fulfil the functions of several units recited in the claims.

[0037] The features of any dependent claim may be combined with the features of any of the independent claims or other dependent claims.

Claims

1. A device for sealing a print chamber of an additive manufacturing device from a build unit, the device comprising: a surface comprising an opening; a three-dimensional volume bounded by the surface, the volume being for receipt of the build unit for use in an additive manufacturing process, wherein the opening in the surface is to permit fluid communication between the three- dimensional volume and the print chamber of the additive manufacturing device; and a cover movable between a first position in which the cover seals the opening of the device to seal the print chamber from the volume, and a second position in which the opening is at least partially uncovered.

2. The device of claim 1 , further comprising: a movable belt, wherein the cover is attached to the belt, wherein movement of the belt causes the cover to transition between its first and second positions.

3. The device of claim 2, further comprising a shaft, wherein the belt is attached to the shaft, and wherein the shaft is rotatable such that rotation of the shaft causes the belt, and cover, to move.

4. The device of claim 1 , wherein, in the first position, the cover is ninety degrees to its orientation in the second position.

5. The device of claim 1 , wherein the cover is movable along a movement path between the first and second positions, and wherein the movement path comprises a change in direction.

6. The device of claim 1 , wherein, in the first position, the cover is to hermetically seal the opening.

7. The device of claim 1 , further comprising a cleaning module, wherein the cleaning module is disposed such that the cover comes into contact with the cleaning module when moving from the first position to the second position.

8. The device of claim 1 , wherein the device comprises a lateral opening for receive of the build unit, and wherein the cover, in the second position, seals the lateral opening.

9. A frame defining an internal volume for receipt of a build unit, the frame comprising: a frame element at least partially defining a surface bounding the internal volume and defining an opening of the frame for permitting fluid communication between a print chamber of an additive manufacturing device and a build unit received in the internal volume; and a sheet element movable between a stowed and a deployed position, wherein, in the stowed position, the sheet is to seal the opening to prevent fluid communication between the print chamber and a build unit received in the internal volume and, in the stowed position, the opening is at least partially uncovered to permit fluid communication between the print chamber and a build unit received in the internal volume.

10. The frame of claim 9, further comprising a rotatable shaft, wherein the sheet element is attached to the shaft such that rotation of the shaft causes the sheet element to move toward its stowed position and deployed positions.

11. The frame of claim 9, wherein the flexible sheet is movable along a movement path between the first and second positions, and wherein the movement path comprises a bend.

12. The frame of claim 9 wherein, in the stowed and deployed positions, a portion of the sheet element adopts different orientations relative to the internal volume.

13. A build unit housing comprising: a sidewall having a sidewall opening for receipt of a build unit; a volume adjacent the sidewall opening for housing the build unit; an opening in the housing providing a passage between a print chamber of an additive manufacturing device through to the volume of the build unit housing, and into a build unit if a build unit is received in the volume; and a movable covering device to cover the opening to thereby seal the passage, the movable covering being movable between advanced and retracted positions, wherein, in the advanced position, the opening is covered by the covering device to seal the passage and, in the retracted position, the opening is at least partially uncovered by the covering device.

14. The build unit housing of claim 13 further comprising a top surface, wherein the top surface comprises the opening, wherein the opening is at least partially defined by a housing element and wherein, in the advanced position, the covering device protrudes from the housing element to cover the opening and, in the retracted position, the covering device is at least partially enclosed by the housing element.

15. The build unit housing of claim 13 further comprising a rotatable element attached to the covering device, wherein movement of the rotatable element causes the covering device to transition between its advanced and retracted positions.