Device for producing three-dimensional objects by successively solidifying layers

Abstract

Device (1) for producing three-dimensional objects (2) by successively solidifying layers of a powder-like building material (4) that can be solidified by means of radiation (3) at the locations corresponding to the respective cross-section of the object (2), with - a housing (5) in which a process chamber (6) is arranged, - a construction chamber (7) housed therein, with a plurality of walls (30) in which a support device (8) for carrying the object (2) with a height-adjustable support (9) is arranged, - a coating device (12) for applying layers of the building material (4) to the support device (8) or a previously formed layer, - a dosing device (11) for supplying the building material (4) and - an irradiation device (14) for irradiating layers of the building material (4) at the locations corresponding to the respective cross-section of the object (2), as well as- a gas injection (18) with which a gas stream is introduced into the process chamber (6) and guided over the build plane (19), characterized in that the build chamber walls (30) are produced either as individual walls or as a single component comprising several or all walls by an additive manufacturing process, in particular laser sintering or laser melting or an electron beam melting (EBM) process, and are penetrated by a plurality of gas channels (31, 40, 50) whose gas outlet side is arranged on the inner side (33) of the walls facing the build space, wherein the gas channels (31, 40, 50) are connected individually or jointly to a gas source for cooling or heating the device components or for cooling or heating or for inerting the build material (4) located in the build chamber (7),wherein the height-adjustable support (9) of the carrying device (8) for carrying an object (2) is also additively manufactured by an additive laser sintering or laser melting process and is permeated by a plurality of gas channels (40) whose opening (41) points towards the top of the support (9).

Description

[0001] The invention relates to a device for producing three-dimensional objects by successively solidifying layers of a powder-like building material that can be solidified by radiation at the locations corresponding to the respective cross-section of the object, with the further features of the preamble of claim 1.

[0002] Typical devices of this type have a housing containing a process chamber. Within the process chamber is a build space with a support structure for the object, featuring a height-adjustable bracket. A coating device is provided to apply the powdered building material. This device dispenses the material from a metering unit, also located within the housing, onto the support structure or a previously formed layer. Additionally, an irradiation device, usually in the form of a laser, is present. The laser beam is directed by a scanner to the points corresponding to the respective cross-section of the object.

[0003] Furthermore, it has also become known to provide a gas injection system, with which a gas stream is introduced into the process chamber and guided over the build level in order to extract soot and other impurities from the atmosphere of the build chamber that arise during the melting process.

[0004] Such a device is known, for example, from DE 10 2010 052 206 A1.

[0005] Further prior art is known from documents DE 10 2007 009 273 A1, concerning a method and a device for producing a three-dimensional object, DE 10 2009 038 241 A1, concerning a method and a device for producing a three-dimensional object, and DE 10 2010 052 206 A1, concerning a device for producing three-dimensional objects.

[0006] Furthermore, document DE 103 42 883 B4 shows a method and a device for producing a three-dimensional molded body.

[0007] 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 device can be designed more flexibly, can be adapted more easily to the thermal requirements of the sintering or melting processes taking place in it, and that more effective gassing of the building material located in the build chamber for the purpose of inerting can take place.

[0008] This problem is solved by the features of claim 1; advantageous further developments of the invention result from the dependent claims.

[0009] The invention provides that the build chamber walls are manufactured either as individual walls or as a single component comprising one, several, or all walls using an additive manufacturing process such as laser sintering or laser melting. The advantages of such processes have not yet been utilized in the production of build chambers and have surprisingly proven to be particularly beneficial, as structural requirements for the build chambers and their walls can be met with great flexibility. Gas channels can be integrated into the build chamber walls, which can be designed in a highly complex manner and used for cooling and heating the build chamber. Stabilizing elements such as ribs or the like can also be selectively produced using an additive manufacturing process.

[0010] Furthermore, as an additional effect, the cooling or heating gas that initially flows through the gas channels of the construction chambers can provide very effective inerting of the building material located in the construction chamber.

[0011] The major advantage of additive manufacturing lies in the fact that the gas channels can be built with a higher density, i.e., with more turns, in thermally stressed areas of the build chamber walls or in areas requiring preheating or cooling, compared to areas less affected by thermal stress. This allows for an improvement in the overall laser sintering or laser melting process through optimized cooling or heating behavior of the build chamber walls.

[0012] Furthermore, it is a significant advantage that the outlet areas of the gas channels can be adapted to the specific requirements of gas introduction into the interior of the build chamber through an additive manufacturing process. For example, a partially diffuse introduction can be achieved if the outlet area is fan-shaped or grid-like, while an intensive introduction is achieved when the outlet channel is designed to direct the gas flow at a particularly high velocity. All these advantages contribute positively to improving the manufacturing process.

[0013] Furthermore, it can be advantageous if the build chamber walls, in addition to the gas channels, are permeated by separate cooling channels that can be connected to a source of a liquid cooling medium. This allows for partial cooling and partial heating of the build chamber walls, as required by the specific building process.

[0014] According to the invention, the height-adjustable support, in other words the height-adjustable bottom wall of the build chamber, is also additively manufactured and permeated by a plurality of gas channels whose openings point towards the top of the support. This allows the build material to be permeated with inert gas from below as well. The opening area of ​​the gas channels can be directed, at least partially, towards the underside of a build plate arranged on the height-adjustable support in order to cool the build plate, in which case the build plate should be attached to the support with a small gap.

[0015] The gas can be supplied to the underside of the carrier via a movable, in particular hose-like, gas guide element.

[0016] It is particularly advantageous if the gas channels in the side walls are arranged in vertical sections and can be switched on and off. Gas channels that are located, for example, below the carrier plate (which is still relatively high up) at the beginning of a build process are then not activated. As the carrier plate is lowered during the build process, further sections of the gas channels are activated, ensuring that the powder volume above the carrier plate is always circulated as evenly as possible over its entire height. The valve assembly responsible for switching the gas channels on and off is controlled depending on the carrier's vertical position.

[0017] Alternatively, the height-adjustable support of the device can be equipped with multiple inert gas channels running through it from the bottom to the top. To prevent powdery building material from trickling into the channels and clogging them internally, the inert gas channels can be designed with a siphon-like bend, limiting the amount of powder that can enter the channels. These inert gas channels, running from the bottom to the top, are supplied by an overpressure of inert gas that builds up beneath the support as a result of gassing through lateral inert gas nozzles. Unlike the arrangement with height sections, these nozzles are not shut off but instead serve to supply the inert gas that flows through the support and floods the building material from below.For this purpose, the construction chamber is designed as a trough that is essentially closed at the bottom, so that an inert gas pressure build-up is possible.

[0018] The invention is explained in more detail with reference to exemplary embodiments shown in the drawings. These show: Fig. 1 a schematic representation of a laser sintering or laser melting device; Fig. 2 a schematic representation of a construction chamber, partially in section; Fig. 3 a representation according to Fig. 2, wherein the carrier plate has inert gas channels; Fig. 4 a detailed view of the outlet areas of inert gas channels at different locations on the construction chamber walls; Fig. 5 an alternative embodiment of the construction chamber with a closed bottom and inert gas channels penetrating the support plate from below;

[0019] In Fig. Figure 1 schematically depicts a device 1 for the production of three-dimensional objects 2 by successively solidifying layers of a powdery building material 4, which can be solidified by radiation 3, at the locations corresponding to the respective cross-section of the object 2. The device 1 comprises a housing 5 in which a process chamber 6 is arranged. A build chamber 7 is provided in the process chamber 6, in which a support device 8 with a height-adjustable carrier 9 is housed. The powdery building material 4 is located on the support device 8, either directly or separately by a build plate (not shown). The support device 8 includes a vertical drive, e.g., designed as a spindle 10, with which the carrier 9 can be raised and lowered.

[0020] The building material 4 is applied layer by layer to the support structure or a previously formed layer in the area of ​​the building chamber by a metering device 11 arranged next to the build chamber 7 using a coating device 12. For this purpose, the coating device 12 has a horizontally movable coating blade 13, which picks up building material 4 from the surface of the metering device 11, transports it to the left, and deposits it as a layer in the area of ​​the build chamber 7. It should be noted that other metering devices and coating devices are also possible within the scope of the invention, e.g., screen coating devices and the like, which are fed from a metering device arranged above.

[0021] The solidification of the building material 4 is achieved via an irradiation device 14, which melts or partially melts the layers of building material 4 and thereby solidifies them as a result of a melting and cooling process. The irradiation device 14 essentially consists of a laser 15, the beam 16 of which is deflected by a scanner 17, typically with two movable mirrors, and directed as radiation 3 against the surface of the building material 4.

[0022] In addition, a gas injection system 18 is provided, with which a gas stream is injected into the process chamber 6, and is guided over the construction level 19 and extracted on the opposite side of the process chamber 6.

[0023] The invention presented here relates in particular to the construction chamber 7 and its walls or elements, which are described below. Fig. Reference is made to 2 - 5.

[0024] In Fig. Figure 2 shows the build chamber 7 with build chamber walls 30. The build chamber walls 30 can be manufactured either as individual walls, which are assembled into the trough-like build chamber after their production, or as a single part comprising several or all walls by an additive laser sintering or laser melting process. In other words, this means that either the build chamber with its build chamber walls 30 is additively manufactured in one piece, i.e., this single-piece additively manufactured part comprises all four build chamber walls, or the build chamber walls are manufactured, for example, individually or in pairs and then assembled.The manufacturing process is additive because it makes it possible to provide the interior of the build chamber walls 30 with a plurality of complex gas channels 31, the gas outlet side 32 of which is located on the inner surface 33 of the walls 30 facing the build space. The gas channels 31 are connected individually or collectively to a gas source for cooling the device components or for cooling, heating, or inerting the building material located in the build chamber. The gas channels thus have multiple functions: firstly, they serve to cool the build chamber walls 30 themselves; secondly, due to their gas outlet, which is directed towards the interior of the build chamber, they also serve to cool, heat, or inert the building material 4 located in the build chamber or the objects 2 already manufactured from it.

[0025] The generative design makes it possible to place the gas channels inside the construction chamber walls 30 as required and to configure the gas outlets 32 in such a way that optimal cooling, heating or inerting of the materials located in the construction chamber is possible.

[0026] In Fig. Figure 2 shows, for example, that the gas channels 31 penetrate the construction chamber walls 30 in a serpentine or meandering pattern to ensure optimal cooling and heating performance. It is possible to provide a higher gas channel density in thermally stressed areas of the construction chamber walls than in thermally less critical areas.

[0027] In Fig. 2 is also indicated to provide the gas channels 31 with branches 34 leading to the gas outlets 35 in the area of ​​the gas outlet side 32 of the gas channels 31.

[0028] In Fig. Figure 3 further shows that the gas outlets 35 are arranged in height sections 36 and can be switched on and off by valve devices 37, wherein the valve devices 37 can be controlled depending on the height position of the height-adjustable support 9.

[0029] In this process, height sections 36 of the gas channels 31, which are arranged above the surface of the support 9 with their gas outlet 35, are pressurized by the valve device 37 and height sections 36, whose gas outlets 35 are arranged below the height-adjustable support 9, are switched off.

[0030] The height-adjustable carrier 9 is also included. Fig. 3 is manufactured by an additive laser sintering or laser melting process and is permeated by a plurality of gas channels 40, the openings of which point towards the top of the support 9. It can be provided that, when using a build plate arranged above the support 9, the opening area of ​​the gas channels is directed at least partially towards the underside of the build plate, thereby cooling the build plate. The build plate, which is not shown in detail, is then attached to the support 9 at a small distance. The gas channels 40 of the support 9 are connected to the gas source via a movable, in particular hose-like, gas guide element 42, the gas guide element 42 being connected to a gas inlet 43 on the underside of the support 9.

[0031] In Fig. Figure 4 shows how the gas outlets 35 or the openings 41 of the gas channels 31 can be designed. A grid- or sieve-like structure is envisioned, which leads to a diffuse blowing of the gas into the interior of the construction chamber. It is within the scope of the invention not to arrange all gas outlets 35 or openings 41 of the gas channels as uniformly as shown in Figure 4. Fig. Figure 4 illustrates this. It is conceivable, for example, to combine diffuse openings with gas outlets that cause a targeted inflow of gas into the interior of the build chamber. This allows, for instance, areas of the build plate that are subject to particularly high thermal stress to be selectively blown from below.

[0032] In Fig. Figure 5 shows an alternative embodiment of the support 9. The support 9 in Fig. 5 is also additively manufactured and has a plurality of gas channels 50 that penetrate the support from the bottom to its top. These gas channels 50 are supplied from the build chamber area below the support 9, in which an overpressure is built up by the build chamber 7 being designed as a trough that is essentially closed at the bottom, such that inert gas introduced into the area below the height-adjustable support 9 of the build space flows upwards through the gas channels 50 of the support 9 under overpressure. For this purpose, the bottom plate 51 of the build chamber 7 is provided with a gas inlet 52, so that gas can flow into the interior of the lower build chamber through one or more openings 53 to build up the overpressure. It is within the scope of the invention to design the trough-like build chamber according to Fig. 5 to be combined with the carrier plate 9 with the gas channels 50 with gas outlets 35, as they are e.g. in Fig. 4 are shown, as well as with a floor-by-floor arrangement of the gas channels, as is the case, for example, in Fig. 3 are shown.

[0033] In Fig. Figure 5a shows a detailed view of the gas channels 50 in the interior of the support 9. The gas channels (50) have a siphon-like bend, which prevents powdery building material from trickling downwards into the area of ​​the build chamber beneath the support. It is within the scope of the invention to make the internal structure of the gas channels 50 even more complex and, for example, to provide several turns of the gas channels 50 between the top and bottom of the support 9 in order to optimize the cooling or heating effect of the gas flowing through the gas channels 50 on the support 9. REFERENCE MARK LIST 1 Device 2 objects 3 Radiation 4 Building materials 5 cases 6th Trial Chamber 7 Construction Chamber 8 Carrying device 9 carriers 10 Spindle drive 11 Dosing device 12 Coating device 13 Coater cooling 14 Irradiation facility 15 lasers 16 beam 17 scanners 18 Gas injection 19 Building Level 30 Construction chamber wall 31 Gas channel 32 Gas outlet unit 33 Inside 34 Junction 35 Gas outlet 36 Altitude section 37 Valve assembly 40 Gas channel 41 Mouth 42 Gas guide element 43 Gas inlet 50 Gas channel 51 Base plate 52 Gas inlet 53 openings

Claims

Device (1) for producing three-dimensional objects (2) by successively solidifying layers of a powder-like building material (4) that can be solidified by radiation (3) at the locations corresponding to the respective cross-section of the object (2), comprising: - a housing (5) in which a process chamber (6) is arranged, - a building chamber (7) housed therein, with a plurality of walls (30) in which a support device (8) for carrying the object (2) with a height-adjustable support (9) is arranged, - a coating device (12) for applying layers of the building material (4) to the support device (8) or a previously formed layer, - a metering device (11) for supplying the building material (4), and - an irradiation device (14) for irradiating layers of the building material (4) at the locations corresponding to the respective cross-section of the object (2), as well as - a gas injection system (18).a gas stream is introduced into the process chamber (6) and guided over the build plane (19), characterized in that the build chamber walls (30) are produced either as individual walls or as a single component comprising several or all walls by an additive manufacturing process, in particular laser sintering or laser melting or an electron beam melting (EBM) process, and are penetrated by a plurality of gas channels (31, 40, 50) whose gas outlet side is arranged on the inner side (33) of the walls facing the build space, wherein the gas channels (31, 40, 50) are connected individually or jointly to a gas source for cooling or heating the device components or for cooling or heating or for inerting the build material (4) located in the build chamber (7),wherein the height-adjustable support (9) of the carrying device (8) for carrying an object (2) is also additively manufactured by an additive laser sintering or laser melting process and is permeated by a plurality of gas channels (40) whose opening (41) points towards the top of the support (9). Device according to claim 1, characterized in that the gas channels (31, 40, 50) from their inlet area on the construction chamber wall (30) to their outlet area on the inside of the construction chamber wall (30) penetrate the construction chamber (7) in several turns or with branches or in a network-like manner. Device according to one of the preceding claims, characterized in that, in addition to the gas channels (31, 40, 50), the construction chamber walls (30) are permeated by cooling channels which can be connected to a source with a liquid coolant or heating medium. Device according to one of the preceding claims, characterized in that the opening area of ​​the gas channels (40) is directed at least partially towards the underside of a building plate arranged on the height-adjustable support (9). Device according to claim 4, characterized in that the building plate is attached to the support (9) at a small distance. Device according to one of the preceding claims, characterized in that the gas channels (40) of the carrier (9) are connected to the gas source via a movable, in particular hose-like, gas guide element (42), wherein the gas guide element (42) is connected to a gas inlet (43) on the underside of the carrier (9). Device according to one of the preceding claims, characterized in that the gas channels (31) of the side walls are assigned to height sections (36) and can be switched on and off by a valve device (37). Device according to claim 7, characterized in that the valve device (37) is controllable depending on the height position of the height-adjustable support (9). Device according to claim 7 or claim 8, characterized in that height sections (36) arranged above the surface of the support (9) with their gas outlet (35) are pressurized by the valve device (37) and height sections (36) whose gas outlets (35) are arranged below the height-adjustable support (9) are switched off. Device according to claim 1, characterized in that the height-adjustable support (9) of the device (1) is provided with a plurality of gas channels (50) which penetrate the support (9) from the bottom side to its top side. Device according to one of the preceding claims, characterized in that the construction chamber (7) is designed as a trough that is essentially closed at the bottom, such that an inert gas introduced in the area under the height-adjustable support (9) of the construction space flows upwards through the gas channels (50) of the height-adjustable support (9) under the build-up of an overpressure.

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