Post-processing in a 3D printing system

Abstract

Methods and apparatus for 3D post-printing processing are disclosed. The methods and apparatus provide a container for an additive manufacturing system for receiving a build body formed from fused build material and unfused build material. The container includes a connector for connecting the container to a pressure source and at least one air hole for allowing air to enter or exit the container. When the connector is connected to the pressure source, an air flow through the container is created between the connector and the at least one air hole in order to remove unfused build material from the container and facilitate cooling of the build material.

Description

BACKGROUND

[0001] A method and apparatus for post-processing of 3D printed objects is disclosed. The method and apparatus facilitate extraction of unfused build material from a build body and provide cooling of the build body to improve post-processing of 3D printed objects. BRIEF DESCRIPTION OF DRAWINGS

[0002] An apparatus and method for post-processing 3D printed objects is shown in the drawings, wherein:

[0003] Figure 1A An example of a three-dimensional (3D) printing system is schematically illustrated;

[0004] Figure 1B An example of a material management station is schematically illustrated Figure 1A

[0005] Figure 1C A working area of a material management station of an example is schematically illustrated Figure 1B

[0006] Figure 2A An internal circuit diagram of one example of a material management station is schematically illustrated

[0007] Figure 2B A table schematically illustrating valve setting information for an internal circuit of a material management station of Figure 2A

[0008] A build material trap geometry used in a tank of an internal circuit of a material management station of Figure 2C Figure 2A

[0009] Figure 3 An example of a post-processing apparatus is shown; and

[0010] Figure 4 Examples of various uses of a post-processing apparatus are shown. DETAILED DESCRIPTION

[0011] As shown in Figure 1A A three-dimensional (3D) printing system 100 (or additive manufacturing system) according to one example includes a cart 102, a 3D printer 104, and a material management station 106. The material management station 106 manages build material.

[0012] ​​​​The trolley 102 is arranged to insert into a docking position in the printer 104 to allow the printer 104 to generate 3D objects within the trolley. The trolley is also arranged (at different times) to insert into a docking position 107 in the material management station 106. The trolley 102 can be docked into the material management station 106 prior to the 3D printing process to load the trolley with build material in preparation for the subsequent 3D printing process.

[0013] The build material loaded into the trolley may include recycled or recovered build material from one or more previous printing processes, new build material, or a combination of new and recycled build material. Some build materials may be non-recyclable, and in such cases, non-recoverable build material may be used to load the trolley. Build materials may be or include, for example, powdered metal materials, powdered composite materials, powdered ceramic materials, powdered glass materials, powdered resin materials, powdered polymer materials, etc. In some examples where the build material is a powder-based build material, the term "powder-based material" is intended to include both dry and wet powder-based materials, particulate materials, and granular materials. It should be understood that the examples described herein are not limited to powder-based materials, and other suitable build materials may be used if appropriately modified. In other examples, the build material may be, for example, in the form of spheres, or any other suitable form of build material.

[0014] return Figure 1A The trolley 102 can also be docked in docking position 107 in the material management station 106. Figure 1A (As shown in the diagram, not docked with trolley 102) to clean at least some parts of trolley 102 after it has been used in the 3D printing manufacturing process. The cleaning process may include recovering and storing unfused build material from previous printing jobs in material management station 106 for subsequent reuse. During the 3D printing process, a portion of the supplied build material can be fused to form a 3D object, while, depending on the type of build material used, the remainder of the supplied build material may remain unfused and potentially recyclable. Some treatment of the unfused build material may be performed by material management station 106 before storage for recycling, such as reducing any agglomeration.

[0015] It should be understood that the material management station 106 may also include an access panel (not shown) to cover the docking position 107 when the trolley 102 is fully docked with the material management station 106 and when the trolley 102 is fully removed from the material management station 106.

[0016] A material management station 106 can be used to service one or more different 3D printers. A given 3D printer can interchangeably use one or more carts 102, e.g., with different carts for different build materials. The material management station 106 can clean the cart 102 of a given build material after a 3D printing manufacturing process, allowing the cart 102 to be filled with a different build material for a subsequent 3D printing manufacturing process. The cleaning of the cart 102 can also include cleaning of the material management station 106, or alternatively, it can include separation of different build materials in the material management station 106 to prevent contamination of one build material type with another build material type.

[0017] In this example, the cart 102 has a build platform 122 on which an object being manufactured is built. In this example, the cart 102 also includes a build material reservoir 124 located below the build platform 122. The build platform 122 can be arranged to have an actuation mechanism (not shown) that allows it to move gradually downward toward a base of the cart 102, such as in a step-wise fashion, as the 3D object is printed upon and as the build material reservoir 124 within the cart 102 becomes depleted, when the build platform 122 is docked in the printer 104 and during the 3D printing manufacturing process. This provides a gradually increasing distance between a base level of the build platform 122 and a print carriage (not shown) to accommodate the 3D object being manufactured. In this example, the size of the object being printed can gradually increase as the object being printed is built up layer by layer during the 3D printing process.

[0018] The 3D printer 104 of this example can generate a 3D object by using a build material depositor carriage (not shown) to form layers of build material onto the build platform 122. Certain areas of each deposited layer are fused by the printer 104 to gradually form the object according to object specification data. The object specification data is based on the 3D shape of the object, and can also provide object attribute data, such as a length or roughness corresponding to the entire 3D object or portions of the 3D object. In examples, desired 3D object attributes can also be supplied to the 3D printer 104 via a user interface, via a software driver, or via predetermined object attribute data stored in memory.

[0019] After a layer of build material has been deposited on the build platform 122 by the printer 104, a page-wide array of thermal (or piezoelectric) print heads on a carriage (not shown) of the 3D printer 104 can be traversed across the build platform 122 to selectively deposit fusing agent in a certain pattern based on where the particles of build material are to be fused together. Once the fusing agent has been applied, the layer of build material can be exposed to fusing energy using one or more heating elements (not shown) of the 3D printer 104. The build material deposition, fusing agent, and fusing energy application processes can be repeated in successive layers until a complete 3D object has been generated. The material management station 106 can be used with any additive manufacturing technology and is not limited to use with a printer that uses print heads on a carriage to deposit fusing agent as in the example described above. For example, the material management station 106 can be used with a selective laser sintering additive manufacturing technology.

[0020] Figure 1B schematically illustrates Figure 1A the material management station 106 of the example, and the cart 102 that is docked therein. Figure 1A

[0021] As shown in the example of Figure 1B The material management station 106 has two interfaces for receiving two new build material supply tanks (or cartridges) 114a, 114b that can be releasably insertable in the material management station 106. In this example, each new build material supply tank 114a, 114b has a capacity of between about thirty and fifty liters. In one example, the build material can be a powdered semi-crystalline thermoplastic material. Providing two new build material supply tanks 114a, 114b allows for a "hot swap" to be performed so that if the build material of the currently in-use container becomes empty or near empty when the cart 102 is filled with build material by the material management station 106 in preparation for an additive manufacturing process, the new build material supply source can be dynamically changed to the other of the two tanks. The material management system 106 can have one or more weight measuring devices to estimate how much new build material is present in one or more of the new build material supply tanks 114a, 114b at a given moment. For example, new build material from the tanks 114a, 114b can be consumed when the cart 102 is loaded with build material prior to installation of the cart 102 in the printer 104 for a 3D printing manufacturing run.

[0022] In this example, a vacuum system (see below with reference to Figure 2A ​The vacuum system facilitates cleaning within the system and allows recycling of at least a portion of the build material between successive 3D printing jobs, where the type of build material used is recyclable. Reference to a vacuum system in this specification includes a partial vacuum, or a reduced pressure relative to atmospheric pressure, for example. The vacuum can correspond to a "negative pressure", which can be used to indicate a pressure lower than atmospheric pressure in a circuit surrounded by atmospheric pressure.

[0023] The total cart usage time for printing of a 3D object can depend on the print time of the printer 104 while the cart 102 is in the printer 104 and the cooling time of the build volume's contents before the cart 102 can be reused. It will be appreciated that after a print operation, the cart 102 can be removed from the printer 104, allowing the printer 104 to be reused for other print operations using build material within a different cart before the total cart usage time has elapsed. The cart 102 can be moved to the material management station 106 at the end of the print time. In some examples, a vacuum system can be used, facilitating faster cooling of the build volume contents after the 3D printing manufacturing process compared to what would occur without use of the vacuum system. Alternative examples of vacuum systems, such as compressed air systems, can generate excess dust, potentially making the cleaning process more difficult.

[0024] In this example, the material management station 106 has a recycle build material tank 108 (see Figure 1B), if appropriate, recovered build material from the cart 102 by the vacuum system is stored in the recovery build material tank 108 for subsequent reuse. Some build material can be recyclable, while others can be non-recyclable. In the initial 3D printing manufacturing cycle, 100% new build material can be used. However, in the second and subsequent printing cycles, depending on build material characteristics and user selection, build material for a print job can include a proportion of new build material (e.g. 20%) and a proportion of recycled build material (e.g. 80%). Some users can select to use predominantly or exclusively new build material in the second and subsequent printing cycles, for example, to maintain the quality of printed objects. The internal recovery build material tank 108 can become full during the post-manufacturing cleaning process, although it can become full after, rather than before, two or more post-manufacturing cleaning processes have been performed. Accordingly, an overflow tank in the form of an external overflow tank 110 can be provided as part of the material management station 106 to provide additional capacity for recovered build material for use once the capacity of the internal recovery build material tank 108 has been full or nearly full. Alternatively, the external overflow tank 110 can be a removable tank. In this example, one or more ports are provided as part of the material management station 106 to allow build material to be output to and / or received from the external overflow tank 110. A sieve 116 or alternative build material refining apparatus can be provided for use with the internal recovery build material tank 108 to make the un-fused build material recovered from the 3D printing manufacturing process for recycling more granular, that is, to reduce agglomeration (clumping).

[0025] In this example, the material management station 106 has a mixing tank (or doping tank) 112 including mixing blades (not shown) for mixing recycled build material from the internal recovery build material tank 108 with new build material from one of the new build material supply tanks 114a, 114b for supply to the cart 102 when the cart 102 is loaded prior to the printing manufacturing process. In this example, the mixing tank (or doping tank) 112 is provided on top of the material management station 106, above the location of the build platform 122 when the cart 112 is docked in the build platform 122. The mixing tank 112 is connected to a mixer build material trap 113 (described below with reference to Figure 2A

[0026] The new build material supply tanks 114a, 114b, the external overflow tank 110 and the main body of the material management station 106 can be configured to fit together in a modular manner, allowing several alternative geometric configurations for the fully assembled material management station 106. In this way, the material management station 106 can be adapted to fit into different housing spaces in a manufacturing environment.​

[0027] The new build material supply tanks 114a, 114b can be releasably connected to the body of the material management station 106 via respective supply tank connectors 134a, 134b. These supply tank connectors 134a, 134b can include a security system to reduce the likelihood of using an improper build material in the 3D printing system. In one example, a proper new build material supply tank 114a, 114b is provided with a secure memory chip that can be read by a chip reader (not shown) or other processing circuitry on the body of the material management station 106 to verify the authenticity of any replacement supply tank (cartridge) 114a, 114b that has been installed. In this example, the chip reader can be provided on the supply tank connectors 134a, 134b and an electrical connection can be made once the new build material supply tank 114a, 114b is attached to the respective connector 134a, 134b. The processing circuitry in the material management station 106 can also be used to write the measured weight of the build material that will be in the respective new build material supply tank 114a, 114b onto the secure memory chip of the tank to store and / or update that value. Thus, the amount of authorized build material that remains in the new build material supply tank 114a, 114b at the end of the cart loading process can be recorded. This allows the amount of particulate build material withdrawn from the new build material supply tank 114a, 114b to be prevented from exceeding the amount of particulate build material filled by the manufacturer. For example, in a situation where the authorized new build material of the tank manufacturer has been completely withdrawn from the new build material supply tank 114a, 114b previously, this prevents further withdrawal of build material that can damage the printer or print quality if the new build material supply tank is refilled with alternative new build material.

[0028] The secure memory chip of the new build material supply tank 114a, 114b can store the material type of the build material contained within the new build material supply tank. In one example, the material type is the material such as ceramic, glass, resin, etc. In this way, the material management station 106 can determine the material type that is to be used by the material management station 106.

[0029] Figure 1C The working area of the material management station 106 is schematically illustrated Figure 1B of an example, showing the build platform 122 of the cart 102 and a build material loading hose 142 that provides a path between the mixing tank 112 of the Figure 1B and the build material storage chamber 124 of the cart 102. The loading hose 142 is used to load the cart 102 with build material prior to using the cart 102 in the printer 104. Figure 1CA recirculation hose 144 is also shown for removing a fabricated 3D object, cleaning the build platform 122 of the cart 102, and the surrounding work area within the material management station 106. In one example, the recirculation hose 144 operates by suction provided via the pump 204 (see Figure 2A ) and provides a closed path to the recycle build material tank 108 (see Figure 1B ) for receiving and holding build material for reuse in subsequent 3D printing processes. In one example, the recirculation hose 144 can be manually operated by a user to recycle build material and / or clean the work area of the material management station 106 from the work area of the material management station 106.

[0030] Figure 2A An internal circuit diagram 200 of one example of a build material management system in the form of a material management station 106 is schematically illustrated. The material management station 106 can be used in conjunction with the cart 102 of Figure 1A .

[0031] As previously described, a printed part can be transported from the 3D printer 104 with un-fused build material to the material management station 106 via the cart 102. Subsequently, the material management station 106 can be used to process the build material and printed part from the cart 102.

[0032] In another example, a printed part can be transported from the 3D printer 104 with un-fused build material to the material management station 106 via another suitable container, such as a box or bin (not shown) in place of the cart 102. Subsequently, the material management station 106 can be used to process the powder-based material and printed part from the container.

[0033] The material management station circuit 200 includes a network of pipes (or guide channels) and a pump 204 for providing a pressure differential across the network of pipes to transport un-fused build material between different components, as described below with reference to Figure 2A . In this example, the pump 204 is a suction pump that operates to generate a pressure differential across the suction pump to create a flow of air from an air inlet at substantially atmospheric pressure through the network of pipes towards an upstream side of the suction pump at a pressure below atmospheric pressure or at "negative pressure". In one example, the pump 204 can be provided as an integral component of the material management station 106, but in another example, the material management station 106 provides a negative pressure / reduced pressure interface via which a suction pump can be detachably coupled or coupled in a fixed configuration. Although the following description refers to a first pipe, a second pipe, a third pipe, etc. of the network of pipes, there is no implied ordering in the number of pipes other than to distinguish one pipe from another.

[0034] The collection hose 206 is connected to the recycle build material tank (RBMT) 208 via a work zone port in the form of a work zone inlet port 273 and a first conduit (hose to RBMT conduit) 272 of the conduit network. The recycle build material tank 208 includes a recycle build material tank (RBMT) inlet region including a recycle build material tank (RBMT) build material trap 218b, and a recycle build material tank (RBMT) material outlet. The RBMT inlet region is where fluidized streams of build material are received for storage in the recycle build material tank 208. The first conduit 272 provides a path between the work zone inlet port 273 and the RBMT inlet region. The work zone inlet port 273 is for receiving build material from the collection hose 206, and is provided at an end of the first conduit 272 that is connected to the collection hose 206. In other examples, the RBMT inlet region can be in direct communication with the work zone 203 or the collection hose 206 without the first conduit 272 therebetween.

[0035] In this example, the recycle build material tank 208 is provided internally to the material management station 106. A hose to RBMT valve 242 is positioned along the first conduit 272 for opening and closing the path through the first conduit 272. The collection hose 206 extends from the work zone inlet port 273 into the work zone 203. The work zone 203 includes at least a portion of the cart 102 (or another container), and can be maintained at substantially atmospheric pressure. Build material from the cart 102 can be collected by the collection hose 206, and transported through the first conduit 272 to the recycle build material tank 208. The recycle build material tank 208 can be used to store any unfused build material from the cart 102 that is suitable for use again in other 3D printing (additive manufacturing) processes. In this way, the recycle build material tank 208 can be used as a buffer storage tank to temporarily store unfused build material prior to supplying the unfused build material for use in other 3D printing (additive manufacturing) processes.

[0036] A second pipe 274 (hose to spill pipe) of the pipe network connects the collection hose 206 to the spill tank 210. The spill tank 210 includes a spill inlet region, and the second pipe 274 provides a path between the collection hose 206 and the spill inlet region, which in this example includes a spill build material trap 218a (filter). A spill tank port, in the form of a spill tank outlet port 275, can also be provided at an end of the second pipe 274. The spill tank 210 can be selectively sealed by an openable flap (not shown). In the sealed configuration, the spill tank 210 is in fluid communication with one or more spill inlet ports of the pipe network and the spill outlet port. Further, in the sealed configuration, the spill tank 210 is not directly vented to atmosphere. Build material from the work area 203 can be transported into the spill tank 210 through the second pipe 274 and the spill tank outlet port 275. A hose to spill valve 244 is positioned along the second pipe 274 for opening and closing the path through the second pipe 274. Unfused build material from the cart 102 (or another container) can be collected by the collection hose 206 and transported to the spill tank 210 through the first pipe 272. The spill tank 210 is an external tank that is removable and can be used to store excess recyclable (recycled) build material when the recycle build material tank 208 is full. Alternatively, the spill tank 210 can be used as a waste storage tank to store unfused build material from the cart 102 that is not suitable for recycling. In another alternative, the spill tank 210 can be used as a purge build material storage tank to store unfused build material from the cart 102 and from elsewhere in the material management station 106 when the material management station 106 purges unfused build material.

[0037] The pump 204 is connected to the recycle build material tank 208 via a third pipe (pump to RBMT pipe) 276 of the pipe network. The third pipe 276 provides a path between the pump 204 and an RBMT inlet region. An RBMT to pump valve 246 is positioned along the third pipe 276 for opening and closing the path through the third pipe 276.

[0038] The pump 204 is also connected to the spill tank 210 via a fourth pipe (pump to spill pipe) 278 of the pipe network. The fourth pipe 278 provides a path between the pump 204 and the spill inlet region. A spill tank port, in the form of a spill tank vacuum port 279, can also be provided at an end of the fourth pipe 278. Fluid (e.g., air) can be conveyed from the spill inlet region toward the pump 204 through the spill tank vacuum port 279. A spill to pump valve 248 is positioned along the fourth pipe 278 for opening and closing the path through the fourth pipe 278.

[0039] The collection hose 206 can be used to collect unfused build material in the cart 102 and transport it to the recycled build material tank 208 or to the overflow tank 210, or both. The tank to be used at a given moment can be selected by opening the appropriate valves along the circuit of pipes Figure 2A The tanks to be used at a given moment can be selected by opening the appropriate valves along the circuit of pipes

[0040] Reference is made herein to Figure 2A The valves can be controlled by a controller 295, which can be for example a programmable logic controller that forms part of the processing circuitry of the build material management station 106. The controller 295 can electronically open one or more valves to open one or more paths in the respective circuit of pipes based on the material transport operation being performed. The controller 295 can also electronically close one or more valves to close one or more paths in the respective circuit of pipes. The valves can be butterfly valves, for example, and can be actuated using compressed air. In another example, one or more valves can be manually opened and closed by a user.

[0041] The controller controls the general operation of the material management system 200. The controller can be a microprocessor-based controller coupled to a memory (not shown) via a communication bus (not shown), for example. The memory stores machine executable instructions. The controller 295 can execute the instructions and thus control the operation of the build material management system 200 in accordance with those instructions.

[0042] Figure 2B is a table that schematically illustrates, for each of several different build material source locations and build material destination locations, the appropriate valve configuration corresponding to the valves labeled in Figure 2A The notation in the appropriate column of the table indicates that the respective valve is controlled by the controller 295 to be open for the particular build material transport operation. For example, when build material is transported from the recycled build material tank 208 to the mixing tank 212, the valves 256, 258, and 254 are set to open by the controller 295, while the valves 250, 244, 276, 248, 242, 262, 260, 252a, and 252b are set to close. In an alternative example, some valves can be set to open at the same time.

[0043] In an example, a recyclability indicator is determined by the processing circuitry of the build material management station 106. The recyclability indicator can indicate whether the build material in the cart 102 (or container) includes recyclable or recoverable material. When it is determined that the unfused build material in the cart 102 is not recyclable or when the recycled build material tank 208 is full, the unfused build material can be transported to the overflow tank 210.

[0044] To deliver unfused build material from the cart 102 (or container) to the overflow tank 210, the hose-to-overflow valve 244 in the second conduit 274 between the collection hose 206 and the overflow tank 210, and the overflow-to-pump valve 248 in the fourth conduit 278 between the pump 204 and the overflow tank 210 can be electronically opened, e.g., by the controller 295. When the pump is in use, a pressure differential is provided from the pump to the collection hose 206. That is, the pressure at the pump 204 is lower than the pressure at the collection hose 206. The pressure differential enables build material to be delivered from the cart 102 (or container) to the overflow tank 210. Build material (and air) near the end of the collection hose 206 (at approximately atmospheric pressure) is delivered from the collection hose 206 along the second conduit 274 and through the hose-to-overflow valve 244 to the overflow tank 210. The overflow tank 210 is provided in a sealed configuration. At the overflow tank 210, the build material is separated from the air stream and falls into the overflow tank 210 from the overflow inlet region. The air (and any residual build material) continues on along the fourth conduit 278 and through the overflow-to-pump valve 248 towards the pump 204, which is at a reduced pressure.

[0045] To help prevent unfused build material from passing through the overflow inlet region of the overflow tank 210 into the fourth conduit 278 towards the pump 204, the overflow inlet region can include an overflow build material trap 218a (e.g., a powder trap). The overflow build material trap 218a is arranged to collect build material from the second conduit 274 and divert the build material (e.g., powder) into the overflow tank 210. Thus, the overflow build material trap 218a helps prevent build material that passes through the overflow inlet region of the overflow tank 210 and enters the fourth conduit 278 via the overflow tank vacuum port 279 from moving towards the pump 204.

[0046] The overflow build material trap 218a can include a filter (e.g., a wire mesh) that collects build material delivered from the overflow tank 210. Thus, the filter separates the build material from the air stream in the overflow inlet region. The holes in the filter are small enough to prevent at least 95% of the build material from passing through, but allow air to flow relatively freely through the filter. The holes in the filter can be small enough to prevent at least 99% of the build material from passing through, while still allowing air to flow relatively freely through the filter. The build material collected by the filter can fall into the overflow tank 210 from the overflow inlet region.

[0047] Recyclable un-fused build material in the cart 102 (or container) can be delivered to the recycle build material tank 208 in a similar manner. To deliver un-fused build material from the cart 102 to the recycle build material tank 208, the hose-to-RBMT valve 242 in the first conduit 272 between the collection hose 206 and the recycle build material tank 208, and the RBMT-to-pump valve 246 in the third conduit 276 between the pump 204 and the recycle build material tank 208 can be electronically opened by the controller 295 as described above. When the pump is in use, a pressure differential is provided from the pump to the collection hose 206. That is, the pressure at the pump 204 is lower than the pressure at the collection hose 206. The pressure differential enables build material to be delivered from the cart 102 (or container) to the recycle build material tank 208. Build material (and air) near the end of the collection hose 206 (at approximately atmospheric pressure) is delivered from the collection hose 206 along the first conduit 272 and through the hose-to-RBMT valve 242 to the recycle build material tank 208. At the recycle build material tank 208, the build material is separated from the air stream and falls into the recycle build material tank 208 from the RBMT inlet region. The air (and any residual build material) continues on along the third conduit 276 and through the RBMT-to-pump valve 246 towards the pump 204, which is at a reduced pressure relative to atmospheric pressure.

[0048] Each of the recycle build material tank 208, the overflow tank 210, and the mix tank 212 has a build material trap 218b, 218a, 218c, respectively. These build material traps 218a, 218b, 218c perform as described above with respect to the build material trap 218a in the overflow tank 210. Figure 2CCyclonic filtration of the input fluidized flow of build material and air is shown schematically. The inlet 296 of the build material trap 218 receives the fluidized flow of build material and centrifugal forces generated by the suction of the pump 204 push the build material to the outer sidewall 297 of the build material trap 218. In one example, the outer sidewall 297 of the build material trap 218 has a circular cross-section and the input build material migrates to the outer sidewall 297 of the build material trap 218 via cyclonic action until the input air reaches the lower outlet, whereupon the build material particles fall downward into the vacuum-sealed receptacle 299 in the build material trap 218. Thus, the build material trap 218 separates the fluidized flow of build material into a powder component that is deposited in the associated tank, and an air component that is drawn toward the pump 204 via the air outlet 298 provided in the build material trap 218 to the interface of the pump 204. A filter (not shown) can be provided in the air outlet 298 of the build material trap 218 to reduce the likelihood of any remaining build material separating the air flow to the pump 204. The build material trap 218 provides efficient powder separation via its geometry that facilitates the formation of a cyclone within the build material trap used. It provides for the transport of build material in the air flow and storage of powder in the tank, while at the same time diverting the air flow out of the tank toward the pump 204. The build material trap provides a filter to capture residual powder that escapes the cyclone in the air flow to prevent it from reaching the pump 204. The build material trap 218 is one example of a build material filter that has the function of separating air from build material flow at the respective tank inlet region. In other examples, the air flow is separated from the fluidized build material once it reaches the destination tank that uses a filter other than a cyclonic filter. For example, a diffusion filter can be used.

[0049] Returning Figure 2A The RBMT inlet region of the recycle build material tank 208 can also include an RBMT build material trap 218b (e.g., a powder trap) or another type of RBMT build material filter to separate build material and air from the input fluidized flow of build material. The RBMT build material trap 218b works in the same or similar manner as the overflow build material trap 218a in the overflow tank 210 to help collect build material and divert the build material into the recycle build material tank 208 to help limit the movement of build material through the third conduit 276 toward the pump 204.

[0050] As described above, when collecting material from the cart 102 via the collection hose 206, the user can move the end of the collection hose 206 around the work area 203 that includes the cart 102 to collect as much build material as possible from the cart 102.

[0051] The fifth pipe (overflow to RBMT pipe) 280 of the pipe network also connects back to the recycled build material tank 208. An overflow tank port in the form of an overflow tank inlet port 281 can also be provided at the end of the fifth pipe 280. Build material from the overflow tank 210 can be delivered through the fifth pipe 280 and the overflow tank inlet port 281 into the recycled build material tank 208.

[0052] The fifth pipe 280 between the recycled material tank 208 and the overflow tank inlet port 281 includes an overflow to RBMT valve 250 in the path to the RBMT build material trap. In the event that the recycled build material tank 208 needs to be refilled with recycled build material, the overflow to RBMT valve 250 in the fifth pipe 280 between the recycled build material tank 208 and the overflow tank 210 can be opened, as well as the RBMT to pump valve 246 in the third pipe 276 between the recycled build material tank 208 and the pump 204. As described above, each of the valves can be electronically opened by the controller 295. When the pump is in use, a pressure differential is provided from the pump to the overflow tank 210. That is, the pressure at the pump 204 is lower than the pressure at the overflow tank 210. In this example, the overflow tank 210 is provided in an unsealed configuration, the overflow tank 210 including an air inlet (not shown) to atmosphere to maintain an approximately atmospheric pressure within the overflow tank 210. The pressure differential enables build material to be delivered from the overflow tank 210 to the recycled build material tank 208. Air flows into the overflow tank 210 through the air inlet. Build material (and air) in the overflow tank is delivered from the overflow tank 210 along the fifth pipe 280 and through the overflow to RBMT valve 250 to the recycled build material tank 208. At the recycled build material tank 208, the build material is separated from the air flow and falls into the recycled build material tank 208 from the RBMT inlet region. The air (and any residual build material) continues on towards the pump 204 along the third pipe 276 and through the RBMT to pump valve 246, the pump 204 being at a reduced pressure.

[0053] The material management station circuit 200 also includes a mixing tank 212. The mixing tank 212 can be used to mix recycled build material from the recycled build material tank 208 with fresh build material from the fresh build material supply tank 214a or 214b, ready for use in a 3D printing process.

[0054] Although two fresh build material supply tanks 214a, 214b are shown in this example, in other examples, one or more fresh build material supply tanks 214a, 214b can be used. More fresh build material supply tanks 214a, 214b can be used when appropriate.

[0055] Each new build material supply tank 214a, 214b is connected to the mixing tank 212 via a sixth pipe (new build material pipe) 282 of the pipe network and a new build material supply tank port 283a, 283b. The new build material supply tank port 283a, 283b is used to output build material from the respective new build material supply tank 214a, 214b. Each new build material supply tank 214a, 214b has an associated material supply tank cartridge to mixer valve 252a, 252b in the sixth pipe 282 between the respective new build material supply tank 214a, 214b and the mixing tank 212. Each new build material supply tank 214a, 214b also includes an air inlet valve, thereby ensuring that air can enter the new build material supply tank 214a, 214b to maintain the air pressure within the new build material supply tank 214a, 214b at approximately atmospheric pressure.

[0056] The mixing tank 212 is connected to the pump 204 via a seventh pipe (pump to mixer pipe) 284 of the pipe network. The seventh pipe 284 between the mixing tank 212 and the pump 204 includes a mixer to pump valve 254, which can be opened or closed to open and close the passage through the seventh pipe 284.

[0057] To deliver new build material from the new build material supply tank 214a or 214b to the mixing tank 212, the material supply tank cartridge to mixer valve 252a or 252b and the mixer to pump valve 254 in the seventh pipe 284 between the mixing tank 212 and the pump 204 are opened. As described above, each of the valves can be electronically opened by the controller 295. When the pump 204 is in use, a pressure differential is provided from the pump 204 to the new build material supply tank 214a or 214b. That is, the pressure at the pump 204 is lower than the pressure at the new build material supply tank 214a or 214b. The pressure differential enables build material to be delivered from the new build material supply tank 214a or 214b to the mixing tank 212. The build material (and air) in the new build material supply tank 214a or 214b is delivered from the new build material supply tank 214a or 214b along the sixth pipe 282 and through the cartridge to mixer valve 252a or 252b to the mixing tank 212. At the mixing tank 212, the build material is separated from the air stream and falls into the mixing tank 212 from the mixer inlet region. The air (and any residual build material) continues along the seventh pipe 284 and through the mixer to pump valve 254 towards the pump 204, which is at a reduced pressure.

[0058] The mixer inlet region of the mixing tank 212 can also include a mixer build material trap 218c (e.g., a powder trap) or any type of mixer build material filter to separate the air flow from the build material flow, which operates in the same or similar manner as the overflow build material trap 218a and the RBMT build material trap 218b. The mixer build material trap 218c helps collect build material and divert the build material into the mixing tank 212 and helps prevent build material from moving toward the pump 204 through the seventh conduit 284.

[0059] The mixing tank 212 is also connected to the recycled build material tank 208 via an eighth conduit (RBMT-to-mixer conduit) 286 of the conduit network that extends sequentially from the recycled build material tank 208 to the mixing tank 212, and a ninth conduit 288 of the conduit network. The ninth conduit 288 can be part of the RBMT-to-mixer conduit 286.

[0060] In some examples, a sieve 216 can be located in the RBMT-to-mixer conduit 286, or between the eighth conduit 286 and the ninth conduit 288, between the recycled build material tank 208 and the mixing tank 212. The sieve 216 can be used to separate agglomerates and larger portions of material from the recycled build material or the recycled build material that is being transported from the recycled build material tank 208. Generally, agglomerates and larger portions of material are not suitable for recycling in other 3D printing processes, so the sieve can be used to remove these portions from the build material. The sieve 216 includes an air inlet (not shown) to ensure that air can enter the sieve 216 to maintain the air pressure within the sieve 216 at approximately atmospheric pressure. In some examples, the RBMT-to-mixer conduit 286 can not be connected to a build material outlet of the recycled build material tank 208. In other examples, the conduit connecting the outlet of the recycled build material tank 208 to the build material inlet in the mixer build material trap 218c of the mixing tank 212 can form a closed loop.

[0061] The RBMT-to-sieve valve 256 is located in the eighth conduit 286 between the recycled build material tank 208 and the sieve 216, and the sieve-to-mixer valve 258 is located in the ninth conduit 288 between the sieve 216 and the mixing tank 212. The RBMT-to-sieve valve 256 and the sieve-to-mixer valve 258 can be opened or closed to open and close the passage between the recycled build material tank 208 and the mixing tank 212 through the eighth conduit 286 and the ninth conduit 288. The valves can be electronically opened or closed by the controller 295.

[0062] To deliver build material from the recycled build material tank 208 to the mixing tank 212, both the RBMT to sieve valve 256 and the sieve to mixer valve 258 in the eighth and ninth conduits 286, 288 between the recycled build material tank 208 and the mixing tank 212 can be opened, as well as the mixer to pump valve 254 in the seventh conduit 284 connecting the mixing tank 212 to the pump 204. Build material in the recycled build material tank 208 can fall by gravity through the eighth conduit 286 down into the sieve 216, for example. When the pump 204 is in use, a pressure differential is provided from the pump 204 to the sieve 216. That is, the pressure at the pump 204 is lower than the pressure at the sieve 216. The pressure differential enables build material to be delivered by gravity from the recycled build material tank 208 to the sieve 216, and by suction to the mixing tank 212. Build material in the recycled build material tank 208 is delivered through the RBMT material outlet, along the eighth conduit 286, and through the RBMT to sieve valve 256 to the sieve 216. Build material (and air) in the sieve 216 is delivered from the sieve 216 along the ninth conduit 288, and through the sieve to mixer valve 258, to the mixing tank 212. At the mixing tank 212, the build material is separated from the air stream and falls into the mixing tank 212 from the mixer inlet region. The air (and any residual build material) continues along the seventh conduit 284, and through the mixer to pump valve 254, towards the pump 204, which is at a reduced (negative) pressure.

[0063] The currently selected ratio of recycled build material from the recycled build material tank 208 and new build material from the new build material supply tank 214a or 214b can be delivered to the mixing tank 212 as described above. The ratio of new build material to recycled build material can be any selected ratio. The ratio can depend on the type of build material and / or the type of additive manufacturing process. In a selective laser sintering process, the ratio can be 50% new build material to 50% recycled build material, for example. In one example of a printhead cartridge 3D printing process, the ratio can be 80% recycled build material to 20% new build material. For some build materials, 100% new build material can be used, but for other build materials, up to 100% recycled build material can be used. The new build material and recycled build material can be mixed together within the mixing tank 212, for example, using rotating mixing blades 213.

[0064] Once the new build material and the recycled build material are thoroughly mixed, the mixed build material can be transported from the mixing tank 212 through the mixer to the cart valve 260, the tenth conduit (mixer to cart conduit) 290 of the conduit network, the work area port in the form of a work area outlet port 291 to the work area 203 and into the cart 102. Build material from the mixing tank 212 can pass through the work area outlet port 291 into the work area 203. The cart 102 (or container) can be positioned substantially below the mixing tank 212 so that gravity can assist in transporting the mixed build material from the mixing tank 212 through the mixer to the cart valve 260, the tenth conduit 290, the work area outlet port 291 and the work area 203 to the cart 102.

[0065] Once the cart 102 is filled with sufficient build material for a given 3D printing run, the cart 102 can be returned to the 3D printer 104. The controller 295 of the material management station 106 can control the appropriate amount of build material to fill the cart 102 for a print job based on how much build material the material management station 106 detects in the cart when the cart is docked in the material management station 106 at the beginning of the cart filling workflow. Subsequently, the controller can fill the cart with the specific amount (dose) of build material that the user intended for the specific print job. Dosing is achieved by using a fill level sensor (not shown), such as a load cell in the mixing tank 212, to output a fill level value indicative of the amount of unfused build material in the mixing tank. The fill level sensor can be one or more load cells, or any other type of sensor, such as a laser-based sensor, a microwave sensor, radar, sonar, a capacitive sensor, etc. When the fill level sensor is a load cell, the fill level value can be an electrical signal indicative of the mass of unfused build material in the storage container.

[0066] Several different workflows can be implemented in the material management station 106. These workflows are managed by the user, but some degree of automation can be provided by the data processor on the material management station 106. For example, the user can select a workflow from a digital display on the material management station 106. For a user with one material management station 106 and one printer 104, an example workflow cycle can be to fill the cart 102, then print a 3D object, then remove the object from the build volume in the material management station 106, then a subsequent print operation and corresponding removal of the build volume, etc. However, the material management station 106 can serve two or more printers so that continuous removal and cart filling operations can be performed by the material management station 106. The user can also choose to perform the cart filling, printing, and removal functions in a random order.

[0067] For each of the workflow operations, the user interface of the material management station 106 can direct the user to take specific manual actions that can be performed as part of the workflow operation. For example, to perform a take-out operation, the user interface can instruct the user to move the collection hose 206 around the collection area 203 as previously described. In addition, the material management station 106 can automatically begin other functions of the workflow operation. For example, to perform a take-out operation, the material management station 106 can automatically operate the pump 204 while the user moves the collection hose 206 around the collection area 203 to recover build material from the cart 102. Any workflow operation that the material management station 106 can perform completely automatically can send a signal to the user through the user interface without requiring user confirmation to continue. Additional workflow operations that are completely automated can require user confirmation to continue if there is a potential safety risk with the workflow operation.

[0068] For example, to load the cart 102 with build material, the user sets up the workflow operation, and then the material management station 106 automatically initiates the different operations in sequence as needed. The material management station 106 is controlled to send build material from the recovered build material tank 208 to the mixing tank 212. The material management station 106 is further controlled to send new build material from at least one of the new build material supply tanks 214a, 214b to the mixing tank 212. The material management station 106 is then controlled to blend the mixture in the mixing tank 212. The mixed build material in the mixing tank 212 can then be discharged to the cart 102. In an example, the workflow operation is completed as a batch process, and thus the cycle can be repeated continuously to completely fill the cart 102.

[0069] In some processes, a small fraction (e.g., 1%) of build material can pass through the build material traps 218a, 218b, 218c (e.g., powder traps) and can move toward the pump 204.

[0070] In some examples, an additional RBMT build material trap 220 (e.g., a powder trap) can be located in an eleventh pipe (pump feed pipe) 292 of the pipe network connecting each of the third pipe 276, the fourth pipe 278, and the seventh pipe 284 to the pump 204. The additional RBMT build material trap 220 is connected to the RBMT inlet region. The additional RBMT build material trap 220 collects build material that can have passed through any of the overflow build material trap 218a, the RBMT build material trap 218b, or the mixer build material trap 218c to help prevent it from reaching the pump 204. Build material collected in the additional RBMT build material trap 220 can be delivered to the recycled build material tank 208 by opening the trap to RBMT valve 262. The trap to RBMT valve 262 can be opened electronically by the controller 295. The RBMT build material trap 220 can work in the same or similar manner as each of the overflow build material trap 218a, the RBMT build material trap 218b, and the mixer build material trap 218c. Build material can be delivered by gravity from the RBMT build material trap 220 to the recycled build material tank 208.

[0071] A pump filter 222 can also be located in a twelfth pipe 294 of the pipe network adjacent to the pump 204. This pump filter 222 helps collect any build material that can have passed through any of the overflow build material trap 218a, the RBMT build material trap 218b, or the mixer build material trap 218c, and the additional RBMT build material trap 220. This helps prevent build material from reaching the pump 204, thereby reducing the likelihood of the pump 204 being impaired in its function, which can occur if a large amount of build material reaches the pump.

[0072] At any time, when the material management station 106 is to process build material for a different material type (e.g., a different material), the material management station circuit 200 can be controlled to implement a cleaning process to clean all build material of substantially the current material type from the material management station circuit 200 to the overflow tank 210. The new build material supply tanks 214a, 214b can be disconnected from the build material station circuit 200 and stored for use to prevent loss of new build material of the current material type.

[0073] In one example, the cleaning process is performed when build material that is not fused in the cart 102 has been collected using the collection hose 206 and delivered to the recycled build material tank 208 or to the overflow tank 210 or both. Alternatively, the cleaning process can include using the collection hose 206 to deliver build material that is not fused in the cart 102 to the overflow tank 210, as previously described.

[0074] The purge process includes conveying any un-fused build material in the recycle build material tank 208 to the overflow tank 210. To convey the un-fused build material from the recycle build material tank 208 to the overflow tank 210, the RBMT to sieve valve 256 and the sieve to mixer valve 258 in the eighth 286 and ninth 288 conduits between the recycle build material tank 208 and the mixing tank 212, the mixer to cart valve 260 in the tenth conduit 290, the hose to overflow valve 244 in the second conduit 274 between the collection hose 206 and the overflow tank 210, and the overflow to pump valve 248 in the fourth conduit 278 between the pump 204 and the overflow tank 210 can be opened. Any build material in the recycle build material tank 208 falls by gravity through the eighth conduit 286 down into the sieve 216. The collection hose 206 can be connected directly to the tenth conduit 290 either before or after any cleaning of the un-fused build material in the cart 102 has been completed. When the pump 204 is in use, a pressure differential is provided from the pump 204 to the sieve 216 via the overflow to pump valve 248, the overflow tank 210, the hose to overflow valve 244, the collection hose 206, the mixer to cart valve 260, the mixing tank 212, and the sieve to mixer valve 258. The build material in the recycle material tank 208 is conveyed to the sieve 216 by gravity via the eighth conduit 286 and the RBMT to sieve valve 256. That is, the pressure at the pump 204 is lower than the pressure at the sieve 216. The pressure differential enables the build material to be conveyed from the recycle build material tank 208 to the sieve 216 and to the overflow tank 210. At the overflow tank, the build material is separated from the air stream and falls into the overflow tank 210 from the overflow inlet region. The air (and any residual build material) continues on towards the pump 204 along the fourth conduit 278 and through the overflow to pump valve 248, which is at a reduced pressure. As such, any unused build material in the sieve 216, the mixing tank 212, or in any of the eighth 286, ninth 288, tenth 290, or second 274 conduits can also be conveyed to the overflow tank 210. In this way, substantially all of the un-fused build material in the material management station circuit 200 can be conveyed to the overflow tank 210.

[0075] Alternatively, the un-fused build material in the recycle build material tank 208 can be conveyed to the cart 102 as previously described. Subsequently, the un-fused build material in the cart 102 can be conveyed to the overflow tank 210, also as previously described. Thus, an alternative way of conveying the un-fused build material from the recycle build material tank 208 to the overflow tank 210 can be provided without directly connecting the collection hose 206 to the tenth conduit 290.

[0076] The cleaning process can also include one or more additional cleaning process elements in which any portion of the network of pipes through the material management station loop 200 is conveyed with sacrificial material, which can still contain at least some amount of unfused build material of the current material type. The sacrificial material can be used to remove at least some of the current build material remaining in the material management station loop 200. In one example, the sacrificial material can be build material of a different build material type that is to be subsequently used in the material management station 106. The sacrificial material can alternatively be an inert material (e.g., silicon) that is not build material. In this way, any small amount of sacrificial material remaining in the material management station 106 at the end of the cleaning process is unlikely to interfere with further operation of the material management station 106.

[0077] After the cleaning process is completed and substantially all of the unfused build material in the material management station loop 200 is in the overflow tank 210, the overflow tank 210 can then be removed from the material management station 106, e.g., for storage or disposal, and another overflow tank (not shown) can be connected to the material management station 106. The other overflow tank can be empty, or the other overflow tank can contain build material previously cleaned out of the material management station 106.

[0078] The cleaning process can be performed in response to user input or automatically. When performed automatically, the material management station loop 200 can be controlled to implement the cleaning process when a cart 102 containing a different material is inserted into the docking location 107 in the material management station 106. In this example, the material type is electronically recorded on a memory chip of the cart 102 (or another container). The memory chip is readable by the processing circuitry of the material management station 106 to determine the material type of the material in the cart 102 (or another container). Alternatively or in addition, the material management station loop 200 can be controlled to implement the cleaning process when one or more new build material supply tanks 214a, 214b containing a different material type are connected to the material management station loop 200. In this example, the material type is electronically recorded on a memory chip of the new build material supply tanks 214a, 214b. The memory chip is readable by the processing circuitry of the material management station 106 to determine the material type of the material in the new build material supply tanks 214a, 214b. In other examples, the material management station loop 200 can be controlled to implement the cleaning process when both of the new build material supply tanks 214a, 214b are removed from the material management station loop 200. It should be appreciated that the material management station 106 can be controlled to provide an indication to the user that the cleaning process can be performed based on the rules discussed previously.

[0079] To improve the efficiency of the overall 3D printing system, a post-processing apparatus and method for rapidly and cleanly removing un-fused powder from a container containing a volume of fused build material and un-fused build material is disclosed. Additionally, the system can also provide cooling or rapid cooling.

[0080] In one example of the post-processing apparatus, a container is provided as shown in Figure 3 and Figure 4 The container is used to receive a build body formed of fused build material and un-fused build material from a 3D printer, the fused build material and un-fused build material underlying the build body 1162.

[0081] The build body 1162 is a volume of processed build material layer, where some portions of the build material have been fused to form a 3D object, some portions of which remain as un-fused powder.

[0082] The first portion of the container is provided with a connector 1142 for connecting to a pressure source 1144, and the second portion is provided with at least one air hole 11142, 11144.

[0083] In one example of the apparatus, the first portion of the container can be a lid 1146. The lid 1146 can be provided with a connector 1142 for connecting to a pressure source 1144.

[0084] In another example of the apparatus, the first portion of the container can be a door (not shown).

[0085] The first portion of the container can be an integral wall of the container.

[0086] In another example, the second portion of the container can be opposite or adjacent to the first portion of the container.

[0087] When the post-processing apparatus is connected to the pressure source 1144 via the connector 1142 and a pressure difference is applied between the pressure source 1144 and the internal space, an air flow is generated through the internal space between the connector 1142 and the at least one air hole 11142, 11144. The air flow sucks the un-fused material from the build body 1162 in the internal space of the container.

[0088] Figure 3 An example of the post-processing apparatus in the material management system 1106 is shown.

[0089] In one example, the container can be independent of the printer and independent of the material management system 1106, the post-processing device is provided for removing the build 1162 from the cart 1102 and suctioning unfused build material from the interior space of the container. An advantage of providing a separate device for post-processing the build 1162 is that the container can replace the cart 1102 of the build 1162, so that the cart 1102 can be used for a subsequent build job.

[0090] In another example, the container can be an integrated component of the cart 1102. The container can be an interior space of the cart 1102 for building manufactured objects.

[0091] The post-processing device can be provided to allow suctioning of unfused material from the build 1162 in the interior space of the container. The post-processing device can be provided for removing the manufactured object from the build 1162 in the interior space. Also, the post-processing device can be used to cool the build 1162.

[0092] Figure 3 An example of a post-processing device is shown. A lid 1146 is provided that includes a connector 1142 for connecting to a pressure source 1144. The lid 1146 includes a connector 1142 for receiving a tube for the pressure source 1144. The connector 1142 is capable of passing unfused build material from the interior space therethrough. In one example of the lid 1146, the top surface extends to the second portion of the container, the lid 1146 can additionally include a flange portion that extends around the perimeter of the top surface. The flange can be provided to improve coupling with the second portion of the container.

[0093] In one example, the lid 1146 can be used with the cart 1102 that has a container forming an interior space in which the produced 3D object is formed. When the post-processing device is an integral part of the cart 1102, the lid 1146 can be used corresponding to the first portion of the container. The lid 1146 can be positioned over the interior space of the cart 1102 that defines the space in which the manufactured object is printed on the build platform.

[0094] In another example, the build 1162 can be transferred from the cart 1102 to a separate container.

[0095] The container can be any suitable shape for containing the build 1162.

[0096] The post-processing device has several advantages. In one example, the post-processing device can be used to remove unfused build material from the build 1162 once the build 1162 has been previously cooled.

[0097] In one example, the post-processing device can be used to cool the build 1162 and remove unfused build material. By providing a connector 1142 that can be connected to a pressure source 1144 and applying a pressure differential between the interior space and the pressure source 1142, unfused build material can be drawn through the connector 1142 and into the tube 1144' for recycling. The material management system 1106 as described above can be used to recycle the drawn unfused material for later use in the 3D printer. Drawing unfused material from the build 1162 can reduce the cooling time of the 3D object being produced within the build 1162. One advantage of removing unfused material is to aid in cooling the 3D object being produced within the build 1162. This is because, as a portion of the hot unfused build material is removed from the interior space of the container, removing the hot unfused build material 1162 from the interior space containing the build 1162 allows the 3D object being produced to cool more quickly, thus resulting in a decrease in the density of the hot build 1162.

[0098] The connector 1142 can be located in a central portion of the lid 1146. Positioning the connector 1142 on the lid 1146 makes it easy to attach and detach the pressure source 1144 to the connector 1142. In another example, the connector 1142 can be located in an off-center position. The connector 1142 can be mounted in the lid 1146 at an angle greater than or less than 90 degrees relative to the plane of the lid 1146, or it can be mounted on the lid 1146 at 90 degrees relative to the plane of the lid 1146. Changing the angle at which the connector 1142 is mounted on the lid 1142 changes the flow path of air in the interior space and can be used to preferentially draw unfused build material from specific portions of the build 1162.

[0099] In another example, the connector 1142 can be located on a different portion of the container.

[0100] The pressure source 1144 can be a pump, such as a pneumatic pump, a suction pump, or other type of pump, or a fan or blower. The pressure source 1144 can be controlled to cause air to flow within the interior space of the container for drawing unfused material from the build 1162 or for cooling the 3D object being produced in the build 1162. The pressure source 1144 is used to create a pressure differential between the pressure source 1144 and the interior space and can be a negative pressure source or a positive pressure source.

[0101] In one example, the post-processing device is provided with at least one air hole 11142, 11144. One or more residual air gaps in the container between the first portion and the second portion of the container can themselves define one or more air holes to allow air to flow through the interior space.

[0102] The post-processing apparatus provides the advantage that un-fused build material is drawn from various different locations of at least one air hole in the container.

[0103] Determining the location of the at least one air hole in the lid of the container is most advantageous early in the post-processing of the build. This is because the at least one air hole is required in the post-processing apparatus, and if the interior space is filled with the build, it is challenging to provide air flow through the interior space from the connector to the at least one air hole. At an early stage, the shorter flow path between the connector and the at least one air hole is advantageous because the build is less likely to block air flow through the shorter flow path.

[0104] As the build becomes less dense as a result of un-fused material being drawn from the build, air holes provided at other locations in the container become free to allow air to pass therethrough.

[0105] An air hole in the lid close to the connector can be arranged such that it jets high speed air around the build. This has the effect of eroding the perimeter of the build.

[0106] As the perimeter of the build is eroded, air holes provided in other parts of the container, for example air holes close to the bottom of the container, are exposed, air can come from air holes located at or near the bottom of the container.

[0107] In one example, at least one air hole 11142, 11144 is provided in the lower part of the container. Such air holes 11142, 11144 are most effective in the later stages of post-processing of the build 1162. This is because air holes 11142, 11144 located in the lower part of the container help air flow around the build 1162. This has the additional effect of cooling the 3D object, and advantageously, the air is more likely to entrain un-fused material in the air flow. The entrained un-fused material is removed by the air flow through the connector, or alternatively, by the air flow through the at least one air hole 11142, 11144.

[0108] The at least one air hole 11142, 11144 can have a size in the range of about the average particle size of the build material to about the smallest dimension of the object being manufactured. In another example, the at least one air hole 11142, 11144 can be provided with a mesh (not shown) so as to prevent the object being manufactured from passing through the at least one air hole 11142, 11144. Air holes located in the lid can be smaller than air holes located in the lower part of the container. This is advantageous in that the flow rate of air through a smaller hole is greater than the flow rate of air through a larger hole when the pressure source 1144 provides the same pressure differential.

[0109] The location of the at least one air hole 11142, 11144 can be selected to achieve a flow path of air through the interior space when a pressure differential is stored between the pressure source 1144 and the interior space of the container.

[0110] Multiple air holes can be provided in the container so that the amount of un-fused material drawn from the interior space is maximized. Although at least one air hole 11142, 11144 is shown in the figures as being in the lower portion of the container, in other examples other locations of the air holes can be provided as described above.

[0111] For example, for a post-processing device integrated with the cart 1102, the at least one air hole can be located in the cart 1102. In another example, the at least one air hole can be located in a build platform (not shown) of the cart 1102.

[0112] When a pressure differential is applied between the pressure source 1144 and the interior space, the pressure differential induces an air flow through the interior space. The air flow causes un-fused build material 1162 from the interior space to be drawn into the flow path of the air and to be drawn from the interior space through the connector or through the at least one air hole 11142, 11144, depending on whether reduced pressure is applied to the container or interior space or increased pressure is applied to the container or interior space.

[0113] The lid 1146 can include a flange or channel in which to receive a portion of the wall of the container, the flange or channel forming the side of the lid 1140.

[0114] Alternatively, the container can be provided with a flange on which the lid 1146 is clamped using a clamping member.

[0115] The container can further include a guillotine member 1150 as a base of the container. The guillotine member 1150 can be used to separate the build 1162 from the build platform. A small amount of build 1162 can be left on the platform due to deviations during the cutting. Most of the build 1162 is located above the guillotine member 1150 after the cutting. The guillotine member 1150 can be selectively adjusted between an open configuration and a closed configuration. In the closed configuration, the guillotine member 1150 is provided with a closed cover that is closed by a plurality of through-holes, thereby preventing the build 1162 from falling out of the container or interior space. In the open configuration, the guillotine member 1150 has a plurality of through-holes to allow air and / or build material to pass through.

[0116] With the post-processing device as described above, an improved method of removing the build 1162 is possible.

[0117] The post-processing device can further comprise a temperature detection device, such as a thermocouple or temperature sensor. The temperature sensor can be provided at the air outlet so that it determines the temperature of the aspirated air and the un-fused build material. The pressure source 1144 can be controlled in response to the detected temperature, so as to produce a suitable air flow profile through the container. The air flow profile can be adapted to different detected temperatures, so as to control the cooling of the build 1162. For example, a higher air flow rate can be preferred at lower temperatures, so as to compensate for a lower temperature difference between the air and the build. An initially lower air flow rate can be preferred in some examples, so as to provide a cooling effect without risking damage to a fragile hot object. Once the object has been sufficiently cooled, the air flow can be increased, so as to remove the un-fused material and continue the cooling process.

[0118] Figure 4 Various uses of the post-processing device are shown, for aspirating un-fused material from the build 1162 and for cooling a manufactured object from the 3D printer. In Figure 4 In (a), the post-processing device is shown for a natural cooling process. The natural cooling process can take several hours, or tens of hours, depending on numerous parameters including: the size and density of the build; the environmental conditions; the type of build material; the fusing parameters; and the thermal properties of the internal space. The natural cooling allows the build 1162 to cool naturally under the environmental conditions.

[0119] Figure 4 (b) shows the post-processing device for a rapid cooling method. The rapid cooling method comprises providing a container as described above for holding the build 1162 from the 3D printer, the container defining an internal space for the build 1162, the container having a connector 1142 for connecting to a pressure source 1144 and at least one air hole 11142, 11144 for allowing air to enter or exit the container. The pressure source 1144 is connected to the connector 1142 of the container and is controlled to provide a pressure difference between the pressure source 1144 and the internal space. The pressure difference causes air to flow through the internal space between the connector 1142 and the at least one air hole 11142, 11144, to aspirate un-fused build material from the container.

[0120] It is advantageous that the pressure source 1144 is relied upon to cause the air flow in the internal space. The air flow carries the un-fused build material through the internal space and aspirates it from the build 1162. If the pressure source 1144 is used to create an aspiration at the connector 1142, the un-fused build material is aspirated from the internal space and past the connector 1142 and through the tube 1144'. Connecting a reduced pressure source to the connector 1142 causes air to flow through the internal space and towards the connector 1142, which receives the un-fused build material from the container or internal space and advances it to the tube 1144'.

[0121] The hot, un-fused build material can be recycled for re-use in the printer. If the pressure source 1144 is used to create an air flow through the interior space from the connector 1142 to the at least one air hole 11142, 11144, then the hot, un-fused build material is carried through the interior space and through the at least one air hole 11142, 11144 and is sucked from the interior space. Connecting an increased pressure source to the connector 1142 causes air to flow through the interior space and towards the at least one air hole 11142, 11144, whereby the un-fused build material from the interior space is sucked through the at least one air hole. In this example, the cutting member 1150 can form a base of the container and can allow the un-fused build material to pass through the cutting member 1150 in order to suck the un-fused material from the interior space.

[0122] Again, the hot, un-fused build material can be recycled for subsequent use.

[0123] The above method can significantly reduce the cooling time of the manufactured object compared to natural cooling. On average, using the above method, the cooling time of the manufactured object can be reduced by up to 50% compared to the cooling time of natural cooling.

[0124] The method can optionally include sequentially performing surges or pulses on the pressure source 1144 to pull air into the interior space and includes measuring the air temperature in the interior space. The system is flexible enough to have different air flow profiles. A simple air flow profile can be defined as "flow on". However, other air flow profiles are also conceivable. Even the "flow on" air flow profile can include the pressure source 1144 to apply an air flow through the interior space at different constant speeds. In one example, the air flow starts with a lower flow speed through the interior space, which gradually increases. However, the air flow can be controlled to perform pulses on the air flow through the interior space in a "flow on-off on" manner. This is advantageous in providing the ability to suck some un-fused material while reducing the amount of cooling air introduced into the interior space, which would only occur during a constant air flow.

[0125] Once the air in the interior space reaches a predetermined temperature, the pressure source 1144 can be controlled to perform another surge or pulse on the air in the container or interior space, or to gradually increase the air flow. This method is advantageous in reducing the risk of thermal shock in the container or interior space. More air can surge into the container or interior space when the temperature of the interior space reaches a predetermined temperature, and the air already present in the container or interior space no longer provides a cooling effect.

[0126] The method may optionally include vibrating the construct 1162 within the internal space during a cooling cycle as shown in 4(c). Vibrating the cover 1146 or the internal space, thereby vibrating the construct space 1162, has been shown to further reduce the cooling time of the construct 1162. On average, vibrating the cover 1146, the container, or the internal space provides approximately 80% reduction in cooling time compared to natural cooling. Vibration helps to... Figure 4 (c) shows the fracturing of the construct 1162, where the solid line represents the fracturing of the construct 1162. The fracturing of the construct 1162 thus allows unfused construct material to more easily enter the airflow and allows more unfused construct material to be entrained by the airflow. Moreover, areas where the airflow is stagnant can form clumps of unfused material in certain areas of the construct 1162. Vibrating the construct 1162 can cause micro-collapses, which then allow unfused powder to slide out of the construct 1162 and into the airflow.

[0127] Vibration of the cover 1146, container, or interior space can be performed in various ways. The entire cover 1146 can be vibrated. Alternatively or additionally, pulses can be applied to the pressure source 1144 to provide vibration to the airflow rate through the connector 1142, providing vibration sufficient to vibrate the build objects in the container or interior space. The build platform of the trolley 1102 can also be vibrated, either additionally or alternatively. The interior space can be vibrated by vibrating a first or second portion of the container's wall structure.

[0128] In another example, the container can provide, as shown below: Figure 4 (d) shows the cutting member 1150 as the base. The method may further include: as shown in Figure 1150. Figure 4 As shown in (d), by selecting a perforated configuration for the cut member 1150, vents are formed in the base of the container using the cut member 1150. A pressure source 1144 is controlled to provide increased pressure to the connector 1142, causing air to flow through the connector 1142 in the cover 1146 to the cut member 1150. The pressure source 1144 is also controlled to draw unfused building material 1162 from the container through the cut member 1150, thereby drawing the unfused building material 1162 from the container through multiple vents in the cut member 1150. The building material 1162 is vibrated, as described above.

[0129] Figure 4 (e) shows a container where unfused build material has been removed from the container or interior space and the build object remains inside. The shaded area shows... Figure 4 (e) shows the construct 1162, and shows some remaining unfused material, with the shaded blank areas indicating that some unfused material has been removed.

[0130] Figure 4(f) shows an example of automated removal, in which the container is rotated to remove the manufactured object.

[0131] Once removed from the container, the 3D object can also be blasted, brushed, or otherwise managed through other post-processing procedures in order to further remove any residual unfused build material from the built object.

Claims

1. A method for post-processing a build formed of fused and unfused material in an additive manufacturing system, the additive manufacturing system including a vessel for holding the build, a three-dimensional printer, and a material management station, the vessel including a connector for connecting the vessel to a source of pressure in the material management station, and a plurality of air holes for allowing air to enter or exit the vessel, the method comprising: inserting the vessel into a docking position in the three-dimensional printer; receiving the build in the vessel; inserting the vessel into a docking position in the material management station after receiving the build in the vessel; connecting the connector to the source of pressure; and generating an air flow through the vessel from an air inlet to an air outlet to remove unfused build material from the vessel, wherein (i) the connector acts as the air inlet and the plurality of air holes act as the air outlet, or (ii) the plurality of air holes act as the air inlet and the connector acts as the air outlet, wherein: the connector is located on a lid of the vessel; and the plurality of air holes includes: at least one first air hole positioned in the lid of the vessel and located in a portion of the vessel adjacent to the connector such that air can be ejected to a perimeter of the build to erode the perimeter of the build; and at least one second air hole positioned proximate to a bottom of the vessel and located in a portion of the vessel opposite the connector. a source of negative pressure is connected to the connector to generate an air flow through the vessel from the plurality of air holes toward the connector that transports unfused build material out of the vessel and into the material management station.

2. The method of claim 1, wherein, a source of positive pressure is connected to the connector to generate an air flow through the vessel from the connector toward the plurality of air holes that transports unfused build material out of the vessel and into the material management station.

3. The method of claim 1, wherein, 4. The method of claim 1, further comprising vibrating the build in the vessel. the air flow cools the build.

5. The method of claim 1, wherein, the source of pressure is controlled to generate a variable air flow profile through the vessel.

6. The method of claim 1, wherein, the source of pressure is controlled to apply a pulsed air flow through the vessel.

7. The method of claim 1, wherein, 8. The method of claim 1, further comprising detecting a temperature of air exiting the vessel and adjusting the source of pressure to change the air flow in response to the detected temperature.

9. The method of claim 1, further comprising: providing a cutting member in the vessel, the cutting member being selectively adjustable between an open configuration having a plurality of third air holes and a closed configuration in which the third air holes are closed; selecting the open configuration of the cutting member; and connecting a source of positive pressure to the connector to generate an air flow through the vessel from the connector toward the cutting member and blow unfused build material from the vessel through the plurality of third air holes in the cutting member. ​ ​ 10. A post-processing enclosure for an additive manufacturing system, the post-processing enclosure comprising a receptacle for receiving a build body formed from fused build material and unfused build material and a material management station, the receptacle being arranged to be inserted into a docking position in the material management station after receiving the build body, and the receptacle comprising: a connector for connecting the receptacle to a pressure source in the material management station; and a plurality of air holes for allowing air to enter or exit the receptacle, wherein: the connector is on a lid of the receptacle and the connector is connectable to the pressure source so as to allow air flow from an air inlet through the receptacle to an air outlet to remove unfused build material from the receptacle, wherein (i) the connector acts as the air inlet and the plurality of air holes acts as the air outlet or (ii) the plurality of air holes acts as the air inlet and the connector acts as the air outlet; and the plurality of air holes comprises: at least one first air hole positioned in the lid of the receptacle and in a portion of the receptacle adjacent to the connector so that air can be injected to a perimeter of the build body to erode the perimeter of the build body; and at least one second air hole positioned proximate to a bottom of the receptacle and in a portion of the receptacle opposite to the connector.

11. The enclosure of claim 10, wherein the connector is a hose for connecting the receptacle to the material management station.

12. The enclosure of claim 11, wherein a negative pressure source is applied, creating air flow through the receptacle from the plurality of air holes to the connector, thereby drawing unfused build material from the receptacle to the material management station through the hose.

13. The enclosure of claim 11, wherein a positive pressure source is applied, creating air flow through the receptacle from the connector to the plurality of air holes, thereby drawing unfused build material from the receptacle to the material management station through the plurality of air holes.

14. The enclosure of claim 10, wherein the receptacle further comprises a cutting member that is selectively adjustable between an open configuration having a plurality of third air holes and a closed configuration in which the plurality of third air holes are closed.

15. The enclosure of claim 10, further provided with a vibrator.

16. The enclosure of claim 10, further comprising a temperature sensor for detecting a temperature of air exiting the receptacle and a controller for controlling the pressure source in response to the detected temperature.

17. A material management apparatus for an additive manufacturing system, the apparatus comprising: a material management station; a pressure source; a receptacle having an interior space for receiving a build body formed from fused build material and unfused build material, the receptacle being arranged to be inserted into a docking position in the material management station after receiving the build body, and the receptacle comprising a connector in communication with the interior space and a plurality of air holes for allowing air to enter or exit the interior space, wherein: The connector is on a lid of the container and is connectable to the pressure source to allow air flow from an air inlet through the interior space to an air outlet to remove unfused build material from the container, wherein (i) the connector acts as the air inlet and the plurality of air holes act as the air outlet, or (ii) the plurality of air holes act as the air inlet and the connector acts as the air outlet; and The plurality of air holes includes: at least one first air hole positioned in the lid of the container and in a portion of the container adjacent to the connector so that air can be ejected to a perimeter of the build to erode the perimeter of the build; and at least one second air hole positioned near a bottom of the container and in a portion of the container opposite the connector.

18. The apparatus of claim 17, further comprising a temperature sensor for detecting a temperature of air exiting the container and a controller for controlling the pressure source in response to the detected temperature.

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