Device for manufacturing three-dimensional objects

Abstract

Device for producing three-dimensional objects (2) by successively solidifying layers of a powder-like build-up material (4) that can be solidified by means of radiation (3) at the locations corresponding to the respective cross-section of the object (2), comprising a housing (5), a build-up chamber (6) housed therein in which a support device (7) for carrying the object (2) with a height-adjustable support (8) is arranged, an application device (9) for applying layers of the build-up material (4) to the support device (7) or a previously formed layer, a metering device (12) for supplying the build-up material (4), and an irradiation device for irradiating layers of the build-up material (4) at the locations corresponding to the respective cross-section of the object (2), characterized in that the metering device (12) is designed as a laterally attachable and detachable powder module (20) with a separate housing (21).which can be docked to the housing (5) of the device (1) for producing three-dimensional objects (2) in such a way that the connection of both housings (21, 5) forms a process chamber (22) in which building material (4) can be transported from the metering device (12) to the build chamber (6), wherein at least one protective gas lock is arranged in the area of ​​the feed opening, wherein the application device (9) conveys the building material (4) from the powder module (20) docked to the device (1) through a feed opening which can be closed before the powder module (20) is undocked into the area of ​​the build chamber.

Description

The invention relates to a device for producing three-dimensional objects by successively solidifying layers of a radiation-hardenable build-up material at the locations corresponding to the respective cross-section of the object, with the further features of the preamble of claim 1. Such devices are generally referred to as selective laser sintering (SLS) or selective laser melting (SLM) systems and consist of a housing containing a build chamber. Within this build chamber is a support structure for holding the object, featuring a height-adjustable support. A dispensing device, usually resembling a doctor blade, applies the build material from a metering unit to the support structure or a previously formed layer. Furthermore, the housing of the device incorporates an irradiation unit, which melts or precipitates the layers of build material at the points to be solidified. The irradiation device typically includes a radiation source such as a laser and a scanner, which allows the laser radiation to be directed in a process-controlled manner to the corresponding hardening points of the layer. The dosing system typically consists of a dosing chamber in which a height-adjustable base plate pushes building material upwards, making it available for the coater to take. The coater walks across the cross-section of the dosing system, picks up the appropriate portion of building material, and layers it within the construction area. In known devices, the container-like dosing unit is integrated into the housing of the device itself, next to the installation space. It is state of the art to place the dosing unit, with its open-topped container, directly next to the installation space in the process chamber floor, thus providing short material conveying paths. Furthermore, it is known to design building material application devices as screen coaters or similar. Separately handled powder containers can then be connected to such a coater via powder lines, so that the building material is conveyed from the container to the coater. Devices of this type are known from documents DE 10 2010 029 078 A1 , DE 10 2013 000 511 A1 , DE 10 2009 036 153 A1 , DE 199 39 616 A1 and US 2004 / 0 012 112 A1. The invention is based on the objective of designing a device with the features of the preamble of claim 1 in such a way that the service life of such a device is significantly reduced when changing building materials, the device is less susceptible to contamination with foreign building materials and the filling of the dosing device is easier to handle. This problem is solved by the combination of features according to claim 1. The core of the invention is thus considered to be the maintenance, in principle, of the configuration of adjacent build space and metering chamber, wherein the build material is brought from the metering chamber to the build space by a movable coater, but the housing units are separated in such a way that the metering chamber is depicted as a powder module that can be docked and undogged, with the respective separate housing units together forming a process chamber. The application device or the coating unit pushes the building material from the powder module docked to the device through a feed opening, which can be closed before the module is undocked, into the build chamber area. The invention thus comprises at least two housing sections, two process chamber floor sections, and advantageously a closure for the transition area between the process chamber area surrounding the build chamber and the process chamber area surrounding the metering device. When docked, both inner housing areas together form a unified process chamber in which the construction process can take place in the usual way. At least one inert gas lock must be arranged in the area of ​​the feed opening of the two housing parts. This means that a protective gas atmosphere can be maintained in both the housing area above the build chamber and in the housing area above the metering chamber during both docking and undocking. The separate housing of the powder module can be separately flooded with inert gas; in other words, a protective gas source can be connected to the housing interior, ensuring a certain inert gas overpressure within the powder module. In a manner known per se, the application device is designed as a coating device with at least one horizontally movable lip- or squeegee-like coating unit. It is structurally possible to arrange up to three coating units, movable back and forth in the same plane and on the same rails, guided on at least one rail-like guide device. This rail-like guide device extends both within the housing of the device and within the housing of the powder module. The guide device can be fixed to a wall, e.g., a rear wall of the housing at the bottom of the process chamber of the device, and project into the housing of the docked powder module, or conversely, the guide device can be fixed within the area of ​​the metering unit inside the housing of the powder module and project from the docked powder module into the build chamber area.In this case too, it is advisable to attach the guide device either to a wall or to the bottom of the process chamber. Advantageously, the two housings are docked together such that the upper surfaces of the base plates of the device housing and the powder module are in the same plane. Docking and undocking are advantageously performed automatically, e.g., by a robot or the like. However, rail-like guide elements, a turret-like or row-like arrangement of several powder modules with multiple sub-housings, and a magazine-like powder module arrangement with powder modules that are movable relative to the build chamber are also within the scope of the invention. In a further development of the invention, it is also possible to arrange a plurality of metering devices in the housing of the powder module, which can be automatically and alternately brought into operative contact with the at least one movable coater that moves back and forth on the guide device. Here, too, it is possible to arrange the multiple metering devices in series, rotatably, or pivotably, and so on. Advantageously, the plurality of the metering devices are arranged to be automatically displaceable at right angles to the direction of the guide elements of the coater. It is advantageous to provide two, three, or four such metering devices to be displaceable in the area of ​​the base of the module housing. Furthermore, it is expedient to provide a plurality of groups with multiple metering devices that are arranged, for example, parallel to one another in the longitudinal direction of the guide elements of the coater. It is conceivable, for example, that...In the first group, a number of dosing containers are arranged in a sliding manner, allowing them to be moved into the coater's reach. Behind this is a second group of dosing containers, which can also be moved into the coater's reach, and so on. This makes it possible to provide dosing containers with different materials, different particle sizes, and the like, which can be easily put into operation. All of this can be advantageously controlled automatically. It is also conceivable that when the dosing containers are not within the coater's reach, they are moved under a cover element, effectively sealing them. This prevents air currents within the process chamber, formed by the module interior and the fixture interior, from contaminating the building materials. It is also advantageous to attach a handling station to the lockable feed opening of the device housing when the powder module is detached. This station allows for cleaning the process chamber, removing building materials, and unpacking a finished object. Such a handling station can include a glovebox and, for example, a cleaning chamber into which the object is placed and cleaned of building materials. The invention is explained in more detail with reference to exemplary embodiments in the drawings. These show: Fig. 1 a schematic sectional view of the device with a docked powder module and a powder container; Fig. 2 a detached powder module according to Fig. 1; Fig. 3 a schematic sectional view of a device with a docked powder module and several powder containers; Fig. 4a a top view of the device according to Fig. 2, highly schematic and showing only the essential elements, wherein a middle powder container of a first group of powder containers is within the reach of the coater; Fig. 4b a top view according to Fig. 4a, wherein a powder container of a middle group of powder containers is within the reach of the coater; Fig. 4c a top view corresponding to Fig. 2, wherein a powder container of a third group of powder containers is available to the coater. The device 1 shown in the drawing figures for producing three-dimensional objects 2 by successively solidifying layers of a powder-like build-up material 4, which can be solidified by radiation 3, at the locations corresponding to the respective cross-section of the object 2, has a housing 5 in which a build chamber 6 is located. A support device 7 with a height-adjustable carrier 8 for supporting the object 2 is arranged in this build chamber. Furthermore, an application device 9 is provided for applying layers of the build-up material 4 to the support device 7 or to a previously formed layer. This application device consists of a movable coater 10 or includes, for example, a coater blade 11 suitable for transporting build-up material 4 from a metering device 12 to the build-up surface 13.Furthermore, an irradiation device comprising a laser 14 and a scanner 15 is provided to direct the radiation 3 of the laser 14 to the corresponding locations of the building surface 13. The dosing device 12 is designed as a powder module 20 with a separate housing 21, which can be docked to the housing 5 of the device for producing three-dimensional objects 2 such that the connection of both housings 21, 5 forms a process chamber 22 in which building material 4 can be transported from the dosing device 12 to the build space 6. The term "process chamber 22" means that the interiors of both housings 21, 5 are connected at least in such a way that atmospheric exchange between the two interiors is possible, and furthermore, a feed opening 23 is formed in the abutment area of ​​the two housings 21, 5, through which the building material 4 can pass from the dosing device 12 to the build space. If necessary, the feed opening 23 must be designed so that the building material 4 can be conveyed through the feed opening 23. The feed opening 23 on both housings shall be designed so that it can be closed before the powder module 20 is undocked. Furthermore, at least one inert gas lock 24 may be arranged in the area of ​​the feed opening 23. The separate housing 21 of the powder module 20 can be separately purged with inert gas, for which purpose an inert gas reservoir 25 is provided on the housing 21 of the powder module 20. The horizontally movable coating unit 10 of the application device 9 is guided on a rail-like guide device 30, which runs both in the housing 5 of the device 1 and in the housing 21 of the powder module 20. In principle, it is conceivable to rigidly connect the rail-like guide device 30 to the device 1, i.e., to anchor it somewhere within the housing 5 of the device 1 and allow it to protrude outwards through the feed opening 23 so that it protrudes into the powder module 20 when it docks. Conversely, it is also possible to anchor the rail-like guide device 30 in the housing 21 of the powder module 20 and allow it to protrude from it so that it protrudes into the interior of the housing 5 when it docks.During the docking process, the guide device 30 can be anchored in the other housing interior with its free end projecting from the respective housing to ensure a precisely defined position. A solution in which the guide device 30 is anchored in the housing 21 of the powder module 20 is shown in Fig. 2, which depicts a detached powder module 20. However, it is also conceivable that separate guide devices 30 are arranged in the area of ​​the powder module 20 around the area of ​​the process chamber, which are aligned with each other when the powder module 20 is docked and are designed for the common guidance of the at least one coater 10. Reference is made below to figures 3 and 4 in the drawings. In the housing 21 of the powder module 20, a plurality of container-like metering devices 12 are arranged, which can be alternately brought into operative contact with the at least one coater 10, which is movable back and forth on the guide device 30. The plurality of the metering devices 12 can be arranged to be displaceable at right angles to the direction of the guide device 30 of the coater 10, so that they can be activated alternately. For this purpose, it can be advantageous if at least one displaceable metering device 12 is accompanied by a bridging element 35, which is aligned with the plane of the module base and can be displaced with it or separately. This bridging element can be driven over by the coater with its building material 4 during the transport of building material 4 from at least one adjacent, "rear" metering device. Figures 4a-4c show different movable groups of dosing devices 12 in various configurations. Each figure shows three groups (I, II, III) of dosing containers 12a, 12b, 12c, and 12a and 12c, respectively. In Figure 4a, the configuration of the three groups (I, II, and III) is chosen such that the container-like dosing device 12b of group I is in operative contact with the coater 10. In this configuration, the dosing devices 12a and 12c cannot be reached by the coater 10. Between the containers 12a and 12c of groups II and III, the bridging elements 35 are marked, via which building material 4 from the metering element 12b can be transported by the coater 10 to the left to the construction space 6. In Fig. 4b, group II of the metering devices 12a and 12c is shifted so that the coater 10 can draw build material 4 from metering device 12a and transport it to the build chamber via the bridging element 35 of group III. It should be noted that the bridging elements 35 are arranged in the same plane as the bases of the housing interiors. In the embodiment shown in Fig. 4, the dosing container group III is shifted in such a way that the coater 10 can access the dosing device 12a of group III. For the sake of simplicity, the displaced metering unit groups 12 are shown to extend beyond the schematically indicated housing 21 of the powder module 20. It should be noted that in all displacement positions, the metering containers are to be located within a protective gas atmosphere of the entire device, limited by housings 5 ​​and 21. Reference numeral 16 additionally shows an overflow container into which excess construction material 4 can be dumped that is not needed in the area of ​​the construction level. REFERENCE MARK LIST 1 Device 2 Three-dimensional object 3 Radiation 4 Build material 5 Housing 6 Build space 7 Carrying device 8 Support 9 Application device 10 Coater 11 Coater blade 12 Metering device 13 Build area 14 Laser 15 Scanner 16 Overflow container 20 Powder module 21 Housing 22 Process chamber 23 Feed opening 24 Inert gas lock 25 Inert gas reservoir 30 Guide device 31 Free end of 30 35 Bridging element

Claims

Device for producing three-dimensional objects (2) by successively solidifying layers of a powder-like build-up material (4) that can be solidified by means of radiation (3) at the locations corresponding to the respective cross-section of the object (2), comprising a housing (5), a build-up space (6) housed therein in which a carrying device (7) for carrying the object (2) with a height-adjustable support (8) is arranged, an application device (9) for applying layers of the build-up material (4) to the carrying device (7) or a previously formed layer, a metering device (12) for supplying the build-up material (4), and an irradiation device for irradiating layers of the build-up material (4) at the locations corresponding to the respective cross-section of the object (2), characterized in that the metering device (12) is designed as a laterally attachable and detachable powder module (20) with a separate housing (21).which can be docked to the housing (5) of the device (1) for producing three-dimensional objects (2) in such a way that the connection of both housings (21, 5) forms a process chamber (22) in which building material (4) can be transported from the metering device (12) to the build chamber (6), wherein at least one protective gas lock is arranged in the area of ​​the feed opening, wherein the application device (9) conveys the building material (4) from the powder module (20) docked to the device (1) through a feed opening which can be closed before the powder module (20) is undocked into the area of ​​the build chamber. Device according to claim 1, characterized in that the separate housing (21) of the powder module (20) can be separately flooded with protective gas. Device according to one of the preceding claims, characterized in that the application device (9) is designed as a coating device with at least one horizontally movable coating device (10) which is guided on at least one rail-like guide device (30) which runs both in the housing (5) of the device (1) and in the housing (21) of the powder module (20). Device according to claim 3, characterized in that the guide device (30) is either fixedly arranged in the device (1) and extends into the housing (21) of the docked powder module (20) or conversely, the guide device (30) is fixedly arranged in the area of ​​the metering device (12) within the housing (21) of the powder module (20) and extends from the docked powder module (20) into the area of ​​the installation space (6). Device according to one of the preceding claims, characterized in that the upper surfaces of the base plates of the housing (5) of the device (1) and of the powder module (20) run in the same plane. Device according to one of the preceding claims 3 to 5, characterized in that separate guide devices (30) are arranged in the area of ​​the powder module (20) and in the area of ​​the installation space (6), which are aligned with each other when the powder module (20) is docked and are designed for the common guidance of the at least one coater (10). Device according to one of the preceding claims 3 to 6, characterized in that a plurality of container-like metering devices (12) are arranged in the housing (21) of the powder module (20), which can be automatically alternately brought into operative contact with the at least one coater (10) which can be moved back and forth on the guide device (30). Device according to claim 7, characterized in that the majority of the metering devices (12) are arranged to be displaceable at right angles to the direction of the guide device (30) of the coater (10). Device according to one of the preceding claims, characterized in that at least one movable metering device (12) is accompanied by a bridging element (35) which is movable with or separately from the metering device and is aligned with the plane of the module base, and which is acted upon by the building material (4) from at least one adjacently arranged further metering device (12) during the transport of building material (4). Device according to one of the preceding claims, characterized in that at least one group of metering devices (12 (I, II, III)) comprises at least two metering devices (12) which have a bridging element (35) arranged either between themselves or in series with the metering devices (12), which is acted upon by the building material (4) of another group of metering devices (12) during the transport of building material (4) from at least one adjacently arranged further metering device (12).

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