HEATING DEVICE WITH INFRARED RADIATING ELEMENTS

Abstract

A heating device for heating a powder during the production of a 3D shaped part. The heating device has an infrared (IR) lamp and a housing in which a construction chamber is provided. The construction chamber is bounded at the bottom by a construction platform for receiving the shaped part and is supported on a support plate. The IR lamp heats the powder during production of the 3D shaped part in the construction chamber. For ensuring an optimized heat transfer to the sintering or melting powder with a particularly homogeneous temperature distribution, a partition wall composed of an IR radiation transparent material is arranged between the construction chamber and the IR lamp.

Claims

1. A heating device for heating a powder during the production of a 3D shaped part, the heating device comprising, an infrared (IR) lamp; a housing in which a construction chamber is provided and which is bounded at the bottom by a construction platform for receiving the shaped part, a support plate on which the construction platform is supported; and a partition wall composed of an IR radiation transparent material arranged between the construction chamber and the infrared lamp.

2. The heating device according to claim 1, wherein the material of the IR radiation transparent partition wall consists of fused silica or of a glass ceramic.

3. The heating device according to claim 1, wherein the construction chamber is surrounded in the radial direction by a cylindrical-sleeve-shaped side wall which is formed at least in part, as the partition wall.

4. The heating device according to claim 1, further comprising at least one reflector located on a side of the infrared lamp facing away from the shaped part.

5. The heating device according to claim 4, the IR lamp has a cladding tube which is covered on its side facing away from the shaped part with a primary reflector in the form of a reflector layer deposited on the cladding tube, and the housing has a housing wall with a reflective inside facing the shaped part that forms a secondary reflector.

6. The heating device according to claim 5, wherein the housing wall is equipped with a thermal insulation layer and/or a cooling plate.

7. The heating device according to claim 1, wherein the construction chamber comprises at least one measuring cell for detecting the temperature of the powder and/or of the shaped part.

8. The heating device according to claim 1, wherein the partition wall is of a double-walled configuration forming at least one intermediate space, and the IR lamp is arranged in the intermediate space.

9. The heating device according to claim 8, wherein the double-walled partition wall comprises a double-walled side wall of the construction chamber and the IR lamp comprises individual heating filaments that are mechanically and electrically separated from each other by webs in the double-walled side wall.

10. The heating device according to claim 1, wherein the IR lamp comprises an IR-B lamp with at least one heating filament having an emission spectrum in the IR-B range.

11. The heating device according to claim 1, further comprising a lamp arrangement having a plurality of IR lamps that are individually electrically controllable.

12. The heating device according to claim 1, wherein the IR lamp comprises an IR-A lamp with an emission spectrum in the IR-A range which is matched to the absorption characteristics of the powder.

13. The heating device according to claim 3, further comprising a heating unit having a frame and wherein the IR lamp and the side wall are arranged in the frame of the heating unit, which heating unit is insertable into the housing.

14. The heating device according to claim 13, wherein the frame comprises a frame outer wall with a reflective inside facing the shaped part, which forms a reflector.

15. The heating device according to claim 13, wherein the frame surrounds a closed inner space in which the IR lamp is arranged.

16. A method of producing a 3D shaped part using the heating device according to claim 1.

17. A heating device for heating a powder during the production of a 3D shaped part, the heating device comprising: an infrared (IR) lamp; a housing in which a construction chamber is provided and which is bounded at the bottom by a construction platform for receiving the shaped part; a support plate on which the construction platform is supported; a partition wall composed of an IR radiation transparent material of fused silica or of a glass ceramic arranged between the construction chamber and the infrared lamp; at least one measuring cell located in the construction chamber for detecting the temperature of the powder and/or of the shaped part; and at least one reflector located on a side of the infrared lamp facing away from the shaped part.

18. The heating device according to claim 17, wherein the IR lamp has a cladding tube with a side facing away from the shaped part covered by a primary reflector in the form of a reflector layer deposited on the cladding tube, and the housing has a housing wall with a reflective inside facing the shaped part that forms a secondary reflector.

19. The heating device according to claim 17, wherein the partition wall is of a double-walled configuration forming at least one intermediate space, and the IR lamp is arranged in the intermediate space.

20. The heating device according to claim 19, wherein the double-walled partition wall comprises a double-walled side wall of the construction chamber and the IR lamp comprises individual heating filaments that are mechanically and electrically separated from each other by webs in the double-walled side wall.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0033] The invention is explained in more detail below with the aid of a patent drawing and exemplary embodiments. The individual figures of the drawing are schematic diagrams in which:

[0034] FIG. 1 is an embodiment of the heating device according to the invention in a side view; and

[0035] FIG. 2 is a further embodiment of the heating device with a partial view of the construction chamber.

DETAILED DESCRIPTION

[0036] FIG. 1 is a schematic diagram of an embodiment of the heating device. The construction chamber 1 has a peripheral, cylindrical side wall or partition wall 2 composed of fused silica. A plurality of IR lamps 3, 3′ are mounted on the outside of the partition wall 2 and emit IR radiation towards the powder P or the 3D shaped part 5 on the construction platform 4 in the construction chamber 1. For detecting the temperature of the powder P and of the shaped part 5, the construction chamber 1 has a measuring cell 13 in the form of a thermal imaging camera. Above the construction chamber 1, the process chamber 6 is located, in which units (not shown here) for controlling the build process of the shaped parts 5 are accommodated. At the upper end of the process chamber 6, a laser unit 7 is arranged, shown schematically, which is capable of selectively sintering and/or melting the powder P with a high-energy laser beam issuing therefrom for producing the 3D shaped part 5.

[0037] The powder P is typically a metal powder, but plastic powders can also be employed. The powder P is located on the construction platform 4, which is arranged on a support plate 9, which is made height-adjustable by a piston 9.1, as indicated by the double direction arrow 8. The construction platform 4 is mounted on an assembly plate 10 which facilitates the replacement of the construction platform 4.

[0038] The IR lamps 3, 3′ emit radiation in the IR-A range and are provided with a reflector 11 on their side facing away from the shaped part 5. The reflector 11 causes the IR radiation to be directed onto the powder P and/or the 3D shaped part 5 on the construction platform 4. The reflector 11 is formed as a so-called primary reflector in the form of a reflector layer 11.1 deposited on the cladding tube 3.1 of the IR lamp 3, 3′. The reflector layer 11.1 is, for example, a gold layer or a layer of opaque white fused silica. The primary reflector can alternatively also be present as a separate sheet metal part 11.2, which rests against the cladding tube 3.1 of the IR lamp 3, 3′.

[0039] Furthermore, a reflective inside 12.2 of the housing wall 12.1 of the housing 12 facing the shaped part 5 additionally forms a secondary reflector. The reflective inside 12.2 is formed by a gold or aluminium layer.

[0040] In the case of a circular cylindrical construction chamber 1 with a correspondingly circular construction platform 4 and a circular cylindrical side wall 2 around the construction chamber 1, the IR lamp 3, 3′ from FIG. 1 shows two portions of a ring lamp (also known as an omega lamp), which is arranged externally around the cylindrical side wall 2.

[0041] If the construction chamber 1 is provided with a construction platform 4 having a rectangular base surface, the IR lamps 3, 3′ are to be understood as individual linear lamps which are mounted on a plurality of levels on the outside of the partition wall 2, the partition wall 2 having the shape of a rectangular cylinder.

[0042] To limit heat generation in the region of the housing 12, the housing wall 12.1 is furthermore equipped with a cooling mechanism 12.4 in the form of a cooling plate and/or an insulation mechanism 12.3 in the form of an insulation layer.

[0043] FIG. 2 shows a variant of the heating device, wherein the construction chamber 1 is shown only schematically with the measuring cell 13 in the form of a pyrometer and a partition wall 2 in the form of a double-walled side wall 22 composed of fused silica with an intermediate space 23. In the intermediate space 23 of the double-walled side wall 22, heating filaments 30 composed of Kanthal wires are arranged, which emit IR radiation in the IR-B range. Kanthal is a trademark owned by Sandvik Intellectual Property AB of Sweden for a family of iron-chromium-aluminium alloys used in a wide range of resistance and high-temperature applications. Kanthal FeCrAl alloys consist of mainly iron, chromium (20-30%), and aluminium (4-7.5%). The alloys have intermediate electric resistance and are known for their ability to withstand high temperatures; ordinary Kanthal FeCrAl alloys have a melting point of 1,500° C. Therefore, they are frequently used in heating elements.

[0044] The double-walled side wall 22 has the function of a cladding tube for the heating filaments 30. The heating filaments 30 can be configured either as a single, long filament, which is laid in coils from bottom to top in the intermediate space 23 of the double-walled side wall 22, or can be present in the form of individually electrically controllable rings. To separate the rings or coils, webs 40 composed of heat-resistant, electrically insulating material are provided. The webs 40 consist of fused silica, glass ceramic, or ceramic, such as a calcium silicate ceramic available from Calsitherm Silikatbaustoffe GmbH of Germany under the trade name Calcast®. On the outside of the double-walled side wall 22, a reflector layer 24 composed of gold is deposited, which reflects the IR-B radiation from the heating filaments 30 towards the powder P and the shaped part 5 such that an efficient operation of the heating device is obtained. A housing 25 includes a cooling mechanism 25.1 in the form of a cooling plate and an insulation mechanism 25.2 in the form of an insulation layer.

[0045] Although illustrated and described above with reference to certain specific embodiments and examples, the present disclosure is nevertheless not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the spirit of the disclosure.