Device for the production of three-dimensional objects

Abstract

Device (1) for producing three-dimensional objects (2) by successively solidifying layers of a powdered build-up material (3) that can be solidified by means of electromagnetic radiation, in particular focused radiation such as laser radiation or electron radiation, at the locations corresponding to the respective cross-section of the objects, wherein the device has a support device (4) for supporting the object (2) on a top surface of a carrier facing the object (2), and a coating device (5) for applying layers of the build-up material (3) to the support device (4) or a previously filtered layer, as well as an irradiation device for irradiating layers of the build-up material (3) at the locations corresponding to the respective cross-section of the object (2), wherein the carrier comprises a chamber table (9) which is arranged vertically displaceable within a build chamber with a chamber shaft (11).wherein the chamber table (9) is sealed at its edge against the walls (10) of the chamber shaft (11) and has at least one sealing device (13) for this purpose, characterized in that the sealing device (13) consists of an outer sealing element (14) bearing against the walls (10) of the chamber shaft (11) and an inner adjusting element (15) located behind it, which is designed to be volume-variable in order to adjust and maintain a contact pressure of the sealing device (13) against the walls (10) of the chamber shaft (11).

Description

The invention relates to a device for producing three-dimensional objects by successively solidifying layers of a powdery building material which can be solidified by means of electromagnetic radiation, in particular bundled radiation, such as laser radiation or electron radiations, at the locations corresponding to the respective cross section of the objects, wherein the device has a carrying device for carrying the object on an upper side of a carrier facing the object. Furthermore, a coating device is provided for applying layers of the building material to the carrier device. An irradiation device serves for irradiating layers of the building material at the locations corresponding to the respective cross section of the object. The carrier comprises a chamber table which is arranged within a construction chamber with a chamber shaft such that it can be displaced in height. The chamber table is sealed at the edge side with respect to the walls of the chamber shaft and has at least one sealing device for this purpose.A chamber table as described above can be heated if necessary and must move with very high accuracy in a chamber shaft which is usually unheated. The chamber is filled with the powdery building material, whereby care must be taken that the powdery building material does not pass out of the chamber through gaps or leaks. Due to the temperature expansion of the table and the constant dimension of the chamber shaft, a temperature-dependent expansion joint results in a negative manner in the prior art. Due to the high positioning accuracy of the table, the sealing resistance must be kept low, and the tightness of the joint must not be lost.For this purpose, in the prior art, a silicone mat tongue is provided in the sealing joint, which is firmly connected to the chamber table and loosely bears against the chamber wall. However, since the pressing pressure of the seal is not precisely defined, sufficient safety is not always available. As a further prior art, it has already become known to provide a spring pack behind a felt seal which seals with respect to the chamber wall, which spring pack presses the felt seal against the chamber with a defined pressure. Different expansion joint widths can thus already be better compensated.EP 2 193 863 A1 discloses a carrier arrangement for a plant for producing workpieces by applying electromagnetic radiation or particle radiation to powder layers.WO 95 / 34 468 A1 discloses an additive manufacturing facility.The object of the invention is to design a device with the features of the preamble of claim 1 in such a way that the seal ensures a high degree of tightness even at a wide range of temperatures of the chamber table and chamber wall and, in addition, does not adversely affect the positioning accuracy of the table. This object is achieved by the characterizing features of claim 1, according to which the sealing device consists of an outer sealing element, which acts on the walls of the chamber shaft, and an inner matching element located behind it, which is designed variably for maintaining a defined contact pressure of the sealing device against the walls of the chamber shaft. As a result, the tightness and the positioning accuracy can always be set to an optimum even in the case of large temperature expansions in the expansion joint.Advantageous further developments are evident from the dependent claims. Thus, it is advantageously provided that the outer sealing element and the matching element are arranged in a circumferential groove in the side region of the chamber table facing the walls of the chamber shaft. The outer sealing element comprises a silicone tongue which abuts against the walls of the chamber shaft, wherein the silicone tongue is supported by a supporting body. The support body is acted upon with variable pressure on its side opposite the chamber walls by the adapter element. The adaptation element is advantageously formed by at least one inflatable tube section, the support material is advantageously made of felt, which is siliconized on its upper side and thereby forms the silicone tongue.As a result, the seal is not only designed to be powder-tight, but also gas-tight, since according to the invention the contact pressure of the silicone tongue on the walls of the chamber shaft can be varied and can be adapted to the circumstances (standstill of the chamber table, movement of the chamber table). In a further development of the invention, it is also possible, in the case of a rectangular or substantially square chamber table, to arrange four separately inflatable hose sections at the respective edges of the chamber table. These separately inflatable tube sections can be designed to be separately volume-variable, so that by blowing on the tube sections differently, the position of the chamber table within the chamber relative to the chamber walls can be varied. If the chamber table is changed in height, the contact pressure can be lowered during the travel movement by reducing the pressure in the matching elements, i.e. in the hose sections.The invention is explained in more detail in the drawing figure on the basis of an exemplary embodiment. This shows a partial section through a device at the height of a chamber table which is arranged in a chamber shaft such that it can be displaced in height.The device 1 for producing three-dimensional objects 2 by successively solidifying layers of a powdery radiation such as laser radiation at the locations corresponding to the respective cross section of the objects, in particular, bundled radiation, has a support device 4, on which the object is constructed and on which the powdery construction material 3 is applied for this purpose by a coating device 5, which is only shown in outline. The laser beam 6 is generated by a laser 7, wherein the laser beam 6 is guided via a scanner 8 in order to be able to strike the applied powder layer variably for selective solidification. The support device 4 comprises a chamber table 9 which points with its edge region 12 to the wall 10 of the chamber shaft 11. In the edge region 12 a sealing device 13 is arranged, which consists of an outer sealing element 14 and an inner matching element 15 lying behind it, which is designed to be variable in volume for setting and maintaining a predeterminable contact pressure of the sealing device 13 on the walls 10 of the chamber shaft 11. The outer sealing element 14 and the matching element 15 are arranged in a preferably circumferential groove 16 in the edge regions 12 of the chamber table 9 pointing towards the walls of the chamber shaft 11. The outer sealing element 14 comprises a silicone tongue 18 which bears against the walls 10 of the chamber shaft 11. Furthermore, the outer sealing element 14 comprises a support body 17 which supports the silicone tongue 18 from the inside. The support body 17 is acted upon by variable pressure on its side opposite the chamber walls 10 by the matching element 15. For this purpose, the adaptation element 15 is formed by a hose section 19 that can be filled or inflatable with at least one pressure medium and that supports the supporting body 17, which can be formed by a felt, from the inside. The support body 17 is generally siliconized on its upper side, so that the silicone tongue 18 is formed as a result. The hose section 19 is connected to a pressure pump 20 by means of which the contact pressure is generated by control valves or another control unit. However, it is also possible to generate the contact pressure by connection to a pressure bottle or the like and to blow a gaseous medium, for example, into the atmosphere when reducing the pressure in the hose section 19.Advantageously, in the case of a rectangular or substantially square chamber table 9, four separate hose sections 19 can be provided, which are configured to be separately variable in volume. As a result, the position of the chamber table 9 relative to the chamber walls 10 can be changed. If the chamber table 9 is moved upwards and downwards within the construction chamber, the pressure can be reduced, whereby wear of the sealing elements is reduced. By siliconizing the outer sealing element, the entire device can also be formed in a gas-tight manner.It can be seen from the exemplary embodiment that the outer sealing element 14 is arranged in an outer groove section 20 with a first groove width and the inflatable tube section 19 is arranged in a second groove section 21 with a smaller groove width lying behind it.LIST OF REFERENCE CHARACTERS1 Device 2 Object 3 Construction material 4 Carrying device 5 Coating device 6 Laser beam 7 Laser 8 Scanner 9 Chamber table 10 Wall 11 Chamber shaft 12 Edge region 13 Sealing device 14 Sealing element 15 Matching element 16 Groove 17 Supporting body 18 Silicone tongue 19 Hose section 20 Groove section 21 Second groove section

Claims

Device (1) for producing three-dimensional objects (2) by successively solidifying layers of a building material (3) in powder form, which can be solidified by means of electromagnetic radiation, in particular bundled radiation such as laser radiation or electron radiation, at the locations corresponding to the respective cross section of the objects, wherein the device has a support device (4) for supporting the object (2) on an upper side of a carrier facing the object (2), and a coating device (5) for applying layers of the building material (3) to the support device (4) or a previously filtered layer, and an irradiation device for irradiating layers of the building material (3) at the locations corresponding to the respective cross section of the object (2), wherein the carrier comprises a chamber table (9) which is arranged within a building chamber so as to be vertically displaceable with a chamber shaft (11), wherein the chamber table (9) is sealed at the edge with respect to the walls (10) of the chamber shaft (11) and for this purpose has at least one sealing device (13), characterized in that the sealing device (13) consists of an outer sealing element (14) acting on the walls (10) of the chamber shaft (11) and an inner matching element (15) lying behind it, which is designed to be variable in volume for setting and maintaining a contact pressure of the sealing device (13) against the walls (10) of the chamber shaft (11).Device according to claim 1, characterised in that the outer sealing element (14) and the matching element (15) are arranged in a preferably circumferential groove in the edge regions (12) of the chamber table (9) pointing towards the walls (10) of the chamber shaft (11).Device according to one of the preceding claims, characterized in that the outer sealing element (14) comprises a silicone tongue (18) which bears against the walls (10) of the chamber shaft (11).Device according to claim 3, characterised in that the outer sealing element (14) comprises a support body (17) supporting the silicone tongue (18).Device according to one of the preceding claims, characterized in that the support body (17) is subjected to variable pressure on its side opposite the chamber walls (10) by the matching element (15).Device according to one of the preceding claims, characterized in that the adaptation element (15) is formed by at least one inflatable tube section (19) which can be filled.Device according to one of the preceding claims, characterized in that the supporting material is formed by a felt.Device according to claim 3, characterised in that the support material is siliconized on its upper side and the silicone tongue (18) is thereby formed.Device according to one of the preceding claims, characterized in that four separate inflatable tube sections (19) are arranged on the four edges of a substantially rectangular or substantially square chamber table (9).Device according to claim 9, characterised in that the inflatable tube sections (19) are designed to be separately variable in volume.Device according to one of the preceding claims 9 or 10, characterised in that the position of the chamber table (9) relative to the chamber walls (10) can be changed by the variable hose sections (19).Device according to one of the preceding claims and claim 6 or claim 9, characterised in that the pressure within the hose sections (19) can be automatically regulated in such a way that the contact pressure of the outer sealing element (14) on the walls (10) of the chamber shaft (11) is constant.Device according to claim 12, characterised in that the pressure can be reduced during a height displacement movement of the chamber table (9) within the construction chamber.Device according to one of the preceding claims, characterized in that the outer seal is formed in a gas-tight manner.Device according to one of the preceding claims, characterized in that the outer sealing element (14) is arranged in an outer groove section (20) with a first groove width and the inflatable hose section (19) is arranged in a second groove section (21) with a smaller groove width lying behind it.

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