Apparatus for additively manufacturing of three-dimensional objects

Abstract

Apparatus (1) for additively manufacturing of three-dimensional objects (2) by means of successive layerwise selective irradiation and consolidation of layers of a build material (3) which can be consolidated by means of an energy beam (4), wherein a measuring unit (5) is provided that is configured to generate information relating to a collimated part (6) of the energy beam (4) and information relating to a focused part (7) of the energy beam (4).

Claims

1. Apparatus for additively manufacturing of three-dimensional objects by means of successive layerwise selective irradiation and consolidation of layers of a build material which is consolidated by means of an energy beam, characterized by a measuring unit comprising: a first beam splitter located between a collimating optic and a focusing optic; a first measuring device is configured to generate information relating to a collimated part of the energy beam; a protective glass arranged between the focusing optic and a build plane, wherein the protective glass is configured to reflect at least a part of a focused part of the energy beam before contacting the build plane; and a second measuring device configured to generate information relating to the focused part of the energy beam reflected from the protective glass.

2. Apparatus according to claim 1, wherein a first optical beam path extends from the collimating optic through the focusing optic onto the build plane and a second optical beam path extends from the collimating optic to the first measuring device and a third optical beam path extends from protective glass through the focusing optic to the second measuring device, wherein the first measuring device is configured to generate information relating to a current focal length of the collimating optic, and wherein the second measuring device is configured to generate information relating to a current focal position of the focusing optic and/or an optical parameter of the focusing optic.

3. Apparatus according to claim 2, characterized in that the first measuring device comprises a second beam splitter configured to split a second energy beam travelling the second optical beam path into two sub-parts and/or the second measuring device comprises a second beam splitter configured to split the part of the energy beam travelling the third optical beam path into two sub-parts.

4. Apparatus according to claim 3, characterized in that the first measuring device and/or the second measuring device comprise two optical sensors, wherein the first sub-part is measured via the first optical sensor and the second sub-part is measured via the second optical sensor.

5. Apparatus according to claim 4, characterized in that at least two optical sensors of the same measuring device are arranged in different distances and/or movable relative to the second beam splitter.

6. Apparatus according to claim 2, characterized in that the second measuring device comprises a dichroic beam splitter configured to split radiation traveling the third optical beam path into a first sub-path extending from a zone of the build plane to a meltpool monitoring unit and a second sub-path reflected from a surface between the focusing optic and the build plane to the second beam splitter of the second measuring device.

7. Apparatus according to claim 1, characterized in that the information generated by the first measuring device comprises or relates to: a current beam power and/or a current focal length of the collimating optic.

8. Apparatus according to claim 1, characterized in that the information generated by the second measuring device comprises or relates to: a current focal position and/or, an optical parameter of the focusing optic.

9. Apparatus according to claim 1, characterized by an optical diaphragm located in a focal position of the energy beam reflected by the protective glass.

10. Apparatus according to claim 1, characterized in that at least one information generated by the measuring unit is transferable to a quality management system.

11. Apparatus according to claim 1, characterized by a control unit configured to control at least one process parameter of the energy beam dependent on at least one information generated by the measuring unit.

Description

(1) An exemplary embodiment of the invention is described with reference to the FIGURE. The sole FIGURE is a schematic diagram and shows an inventive apparatus.

(2) The FIGURE shows an apparatus 1 for additively manufacturing of three-dimensional objects 2 by means of successive layerwise selective irradiation and consolidation of layers of a build material 3 which can be consolidated by means of an energy beam 4. The apparatus 1 comprises a measuring unit 5 that comprises two measuring devices 14, 16 configured to generate information relating to a collimated part 6 of the energy beam 4 and information relating to a focused part 7 of the energy beam 4. The measuring devices 14, 16 are, therefore, configured to measure different parts 6, 7 of the energy beam 4 at the same time enabling the measuring unit 5 to generate information relating to the different parts 6, 7 of the energy beam 4.

(3) The measuring unit 5 comprises a first beam splitter 8 that splits the energy beam 4, wherein a first optical beam path 9 extends from a collimating optic 10 through the first beam splitter 8 and a focusing optic 11 onto a build plane 12. The part of the energy beam 4 that extends along the first optical beam path 9 therefore, is not reflected by the first beam splitter 8 and is used to irradiate the build material 3 in the build plane 12.

(4) The first beam splitter 8 splits a part off the energy beam 4 extending along a second optical beam path 13 from the collimating optic 10 to the first measuring device 14. Further, the first beam splitter 8 reflects a reflected part of the energy beam 4 that extends along a third optical beam path 15 from the build plane 12 or a surface between the build plane 12 and the focusing optic 11 through the focusing optic 11 to the second measuring device 16. Thus, the first beam splitter 8 is used to split the energy beam 4, wherein a first optical beam path 9 passes through the first beam splitter 8 and a second energy optical beam path 13 is reflected by the first beam splitter 8 to the first measuring device 14 and, wherein a third energy optical beam path 15 is reflected by the first beam splitter 8 to the second measuring device 16.

(5) The first measuring device 14 comprises a second beam splitter 17 splitting the part of the energy beam 4 that extends along the second optical beam path 13 into a first sub-part 18 and a second sub-part 19, wherein the first sub-part 18 is imaged on a first optical sensor 20 and the second sub-part 19 is measured via a second optical sensor 21. The first optical sensor 20 and the second optical sensor 21 are arranged in different distances to the second beam splitter 17. Thus, the optical path lengths of the sub-parts 18, 19 of the part of the energy beam 4 extending along the second optical beam path 13 are different. This enables for measuring whether the collimated part 6 of the energy beam 4 is properly collimated or whether the focal length of the collimating optic 10 has to be adapted. Further parameters of the energy beam 4 and/or the collimating optic 10 can be measured via the optical sensors 20, 21 such as the power of the energy beam 4.

(6) The setup of the second measuring device 16 is analog to the first measuring device 14. Therefore, same numerals are used for same parts. The second measuring device 16 also comprises a second beam splitter 17 and two optical sensors 20, 21, wherein the two optical sensors 20, 21 are arranged in different distances to the second beam splitter 17. The second beam splitter 17 of the second measuring device 16 also splits the part of the energy beam 4 incident on the second beam splitter 17 into a first sub-part 18 and a second sub-part 19.

(7) Additionally, the second measuring device 16 comprises an optical diaphragm 22 that is arranged in a focal position of a part of the energy beam 4 reflected by a protective glass 23. The diaphragm 22 allows for a filtering of radiation, wherein only the part of the energy beam 4 that is reflected by the protective glass 23 is allowed to pass the optical diaphragm 22 and to pass on to the second beam splitter 17 of the second measuring device 16. Radiation other than the part of the energy beam 4 reflected at the protective glass 23 is blocked by the optical diaphragm 22.

(8) The measuring unit 5 further comprises a dichroic beam splitter 24 assigned to the second measuring device 16, wherein the dichroic beam splitter 24 is configured in that radiation is selectively filtered (reflected) or passes through the dichroic beam splitter 24 dependent on the wavelength of the radiation. In particular, the part of the energy beam 4 that is emitted from a zone of the build plane 12 or reflected at the protective glass 23, i.e. extends along the third optical beam path 15, is filtered by the dichroic beam splitter 24 dependent on the wavelength. This allows for a filtering of the two different parts of the energy beam 4, i.e. the part reflected at the protective glass 23 or at the build plane 12 or a part emitted from a zone of the build plane 12, in particular thermal radiation. Thus, radiation that is emitted by the build plane 12, in particular by zones adjacent to a consolidation zone in which the energy beam 4 irradiates the build material 3 directly, can be measured.

(9) Particularly, the dichroic beam splitter 24 can be designed in that the wavelength of the energy beam 4 is only reflected to a minor degree or in other words, radiation with a wavelength of the energy beam 4 can pass the dichroic beam splitter 24 in its greatest part. Thus, a part 25 of the energy beam 4 that passes the dichroic beam splitter 24 is mainly the part of the energy beam 4 that has been reflected at the protective glass 23 or at the consolidation zone passing through the focusing optic 11 and reflected at the first beam splitter 8. The part 25 of the energy beam 4 is guided to the second measuring device 16 and again filtered by the optical diaphragm 22 and, subsequently, split by the second beam splitter 17 into two sub-parts 18, 19 and imaged onto the optical sensors 20, 21.

(10) Further, a part 26 (thermal radiation emitted by a zone of the build plane 12) is mainly reflected by the dichroic beam splitter 24 as the wavelength of the part 26 differs from the wavelength the dichroic beam splitter 24 is designed to let through. The part 26 is mainly emitted by the build plane 12, in particular by zones adjacent to the consolidation zone. The part 26 therefore, is emitted by the build plane 12 and passes through the protective glass 23 and the focusing optic 11. Subsequently, the part 26 is reflected by the first beam splitter 8 and the dichroic beam splitter 24 and guided to a meltpool monitoring unit 27. The meltpool monitoring unit 27 is configured to measure the part 26, in particular the meltpool monitoring unit 27 comprises at least one optical sensor (not shown), for example to determine the temperature of the zone of the build plane 12 the part 26 is emitted from.

(11) As can be derived from the sole FIGURE the apparatus 1, in particular the measuring unit 5, allows for a determination of various parts of the energy beam 4 and radiation that is emitted from the build plane 12. In particular, it is possible to generate information relating to a collimated part 6 and a focused part 7 as well as a part 26 of radiation emitted from the build plane 12. This allows for a defined adjustment of various process parameters, in particular the focal lengths of the collimating optic 10 and the focusing optic 11 so as to avoid or correct focus shifts of the energy beam 4, for example due to temperature differences. Further, temperature gradients between the consolidation zone and adjacent zones can be determined by measuring the temperature in the consolidation zone and the adjacent zones. Thus, respective process parameters, in particular the power of the energy beam 4 can be adjusted, in particular reduced, if the determined temperature gradient exceeds a predefined value.

(12) Self-evidently, the method described above may be performed on the apparatus 1 depicted in the FIGURE.