APPARATUS FOR ADDITIVELY MANUFACTURING THREE-DIMENSIONAL OBJECTS

Abstract

Apparatus (1) for additively manufacturing 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 (5), which apparatus (1) comprises a determination device (8) that is adapted to determine at least one parameter relating to the energy beam (5), wherein the determination device (8) comprises at least one determination unit (9) adapted to determine at least one first parameter of a reflected part (10) of the energy beam (5), which is reflected at a build plane (7), wherein the determination device (8) is adapted to determine a difference between a reference parameter and the at least one first parameter of the reflected part (10).

Claims

1. Apparatus (1) for additively manufacturing 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 (5), which apparatus (1) comprises a determination device (8) that is adapted to determine at least one parameter relating to the energy beam (5), characterized in that the determination device (8) comprises at least one determination unit (9) adapted to determine at least one first parameter of a reflected part (10) of the energy beam (5), which is reflected at a build plane (7), wherein the determination device (8) is adapted to determine a difference between a reference parameter and the at least one first parameter of the reflected part (10).

2. Apparatus according to claim 1, characterized in that the reference parameter is defined or determined.

3. Apparatus according to claim 1, characterized in that the determination device (8) is adapted to determine a second parameter of at least one initial part (12) of the energy beam (5) and adapted to determine at least one first parameter of the reflected part (10) of the energy beam (5).

4. Apparatus according to claim 3, characterized in that the determination device (8) comprises at least one first determination unit (9) adapted to determine the first parameter of the at least one reflected part (10) of the energy beam (5) and at least one second determination unit (11) adapted to determine the at least one second parameter of the initial part (12) of the energy beam (5), wherein the determination device (8) is adapted to determine a difference between the first parameter of the at least one reflected part (10) and the second parameter of the at least one initial part (12).

5. Apparatus according to claim 1, characterized in that the first parameter and/or the second parameter are or relate to an intensity of the energy beam (5) and/or an absorbed intensity that is absorbed in the build material (3).

6. Apparatus according to claim 1, characterized in that the first parameter relates to topography information of the build material (3) that is arranged in the build plane (7).

7. Apparatus according to claim 1, characterized in that the determination device (8) is adapted to determine at least one process parameter, wherein the determination device (8) is adapted to perform the determination of the first parameter dependent on the process parameter.

8. Apparatus according to claim 1, characterized in that the process parameter is or relates to a build material (3), in particular an absorption coefficient of the build material (3), and/or an angle of incidence of the energy beam (5) on the build plane (7) and/or residues generated in the additive manufacturing process.

9. Apparatus according to claim 3, characterized by a beam splitting unit (13) that is adapted to split the initial part (12) off the energy beam (5), wherein an irradiation device (6) of the apparatus (1) is adapted to guide the reflected part (10) of the energy beam (5) in line with the energy beam (5) and to guide the reflected part (10) of the energy beam (5) through the beam splitting unit (13) towards the first determination unit (9).

10. Apparatus according to claim 9, characterized by a second beam splitting unit (16) that is adapted to separate the reflected part (10) of the energy beam (5) from radiation emitted from the build plane (7).

11. Apparatus according to claim 3, characterized in that the or a first determination unit (9) is arranged on a transparent wall element (19) delimiting a process chamber (18) in which the additive manufacturing process is performed, wherein the transparent wall element (19) is transparent for the reflected part (10) of the energy beam (5).

12. Apparatus according to claim 1, characterized in that the determination device (8) comprises at least one optical filter unit (14) that is adapted to filter radiation of a wavelength or a wavelength range differing from the energy beam (5), in particular 1070 nm.

13. Apparatus according to claim 1, characterized in that the determination device (8) comprises two optical filter units (14, 15), wherein a second optical filter unit (15) is arranged between an energy source (4) generating the energy beam (5) and the second determination unit (11) and the first optical filter unit (14) is arranged between the build plane (7) and the first determination unit (9).

14. Determination device (8) for an apparatus (1) for additively manufacturing 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 (5), in particular an apparatus (1) according to claim 1, characterized in that the determination device (8) comprises at least one determination unit (9) adapted to determine at least one parameter of a reflected part (10) of the energy beam (5), which is reflected at a build plane (7), wherein the determination device (8) is adapted to determine a difference between a reference parameter and the at least one parameter of the reflected part (10).

15. Method for determining at least one parameter of an energy beam (5) used in an apparatus (1) for additively manufacturing 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 (5), wherein the energy beam (5) is guided onto build material (3) that is arranged in a build plane (7), wherein the energy beam (5) is partially reflected at the build plane (7), characterized in that at least one parameter of a reflected part (10) of the energy beam (5), which is reflected at the build plane (7) and a difference between a reference parameter and the at least one parameter of the reflected part (10) is determined.

Description

[0031] Exemplary embodiments of the invention are described with reference to the Fig. The Fig. are schematic diagrams, wherein

[0032] FIG. 1 shows an inventive apparatus according to a first embodiment in a; and

[0033] FIG. 2 shows an inventive apparatus according to a second embodiment.

[0034] FIG. 1 shows an apparatus 1 for additively manufacturing three-dimensional objects 2 by means of successive layerwise selective irradiation and consolidation of layers of a build material 3. The apparatus 1 comprises an energy source 4, for example a laser source that is adapted to generate an energy beam 5, for example a laser beam. The build material 3 can be consolidated via the energy beam 5 in that an irradiation device 6 is adapted to selectively guide the energy beam 5 across a build plane 7 in which a layer of build material 3 is arranged.

[0035] The apparatus 1 further comprises a determination device 8 that comprises a first determination unit 9 that is adapted to determine a first parameter of a reflected part 10 of the energy beam 5, which is reflected at the build plane 7. The determination device 8 is further adapted to determine a difference between a reference parameter and the first parameter of the reflected part 10. It is possible that the reference parameter is defined, in particular via a control unit (not shown) or via a user interface (not shown). In this exemplary embodiment the reference parameter is determined via the determination device 8, in particular via a second determination unit 11.

[0036] Via the second determination unit lithe determination device 8 is adapted to determine a second parameter of an initial part 12 of the energy beam 5, wherein the determination device 8 is adapted to determine a difference between the first parameter of the reflected part 10 and the second parameter of the initial part 12. In this exemplary embodiment, the apparatus 1 comprises a first beam splitting unit 13 that is adapted to split the initial part 12 off the energy beam 5 as the energy beam 5 is incident on the first beam splitting unit 13. The energy beam 5 is guided via the first beam splitting unit 13 to the irradiation device 6 which is adapted to guide the energy beam 5 in the build plane 7 or across the build plane 7, respectively.

[0037] The reflected part 10 of the energy beam 5 is reflected at the build plane 7, in particular the surface of build material 3 that is arranged in the build plane 7. The reflected part 10 therefore, propagates towards the irradiation device 6 and is guided in line (in the opposite direction) with the energy beam 5. Thus, the reflected part 10 of the energy beam 5 is incident on the first beam splitting unit 13 and may pass the first beam splitting unit 13 to further propagate towards the first determination unit 9. As can be derived from FIG. 1, the determination device 8 is adapted to determine the first parameter of the reflected part 10 of the energy beam 5 and the second parameter of the initial part 12 of the energy beam 5. The determination of the first parameter is performed via the first determination unit 9 and the determination of the second parameter is determined via the second determination unit 11.

[0038] As can further be derived from FIG. 1, the determination device 8 comprises a first optical filter unit 14 that is arranged between the build plane 7 and the first determination unit 9 with respect to the beam path of the reflected part 10 of the energy beam 5 propagating between the build plane 7 and the first determination unit 9. The first optical filter unit 14 is adapted to filter radiation other than the reflected part 10 of the energy beam 5, in particular to separate the reflected part 10 of the energy beam 5 from other types of radiation, such as thermal radiation emitted from the build plane 7. The first optical filter unit 14 may for example be built as bandpass filter allowing radiation with the wavelength of the reflected part 10 of the energy beam 5 to pass the optical filter unit 14, in particular a wavelength of 1070 nm.

[0039] The determination device 8 further comprises a second optical filter unit 15 that is arranged between the energy source 4 and the second determination unit 11. Similar to the first optical filter unit 14, in particular identical to the first optical filter unit 14, the second optical filter unit 15 is adapted to filter radiation other than the initial part 12 of the energy beam 5. Hence, only the initial part 12 of the energy beam 5 may pass the second optical filter unit 15 and can be incident on the second determination unit 11. The first and second determination unit 9, 11 may be built as optical sensors or may comprise optical sensors, such as a CCD or CMOS sensors, in particular a photo diode and/or a camera. Hence, the first and the second determination unit 9, 11 are adapted to determine various parameters of the reflected part 10 or the initial part 12 of the energy beam 5, in particular the power or the intensity of the respective part 10, 12, in particular spatially resolved.

[0040] The first parameter of the reflected part 10 of the energy beam 5 may also relate to topography information indicating whether the topography of the build material 3 arranged in the build plane 7 is even or whether variances in the topography of the build material 3 occur. As the intensity or the power of the reflected part 10 that is incident on the first determination unit 9 varies, if the surface of build material 3 arranged in the build plane 7 varies in height or is unevenly distributed or the surface of the object 2 arranged in the build plane 7 is not plane. Thus, the reflected part 10 of the energy beam 5 will be scattered or reflected into a different direction and cannot be properly guided in line towards the first determination unit 9. Further, the reflection characteristic in which the energy beam 5 is reflected at the build plane 7 generating the reflected part 10 of the energy beam 5 also varies with the topography of build material 3 that is arranged in the build plane 7.

[0041] Further, the determination device 8 comprises a second beam splitting unit 16 that is adapted to split the radiation that is emitted from the build plane 7, in particular separate the reflected part 10 of the energy beam 5 from other types of radiation, such as thermal radiation emitted from the build plane 7. The determination device 8 comprises a third determination unit 17 that is adapted to determine a parameter of radiation that is emitted from the build plane 7, in particular thermal radiation, such as the intensity of thermal radiation or the temperature of build material 3 arranged in the build plane 7, for instance.

[0042] FIG. 2 shows an apparatus 1 according to a second embodiment, wherein the apparatus 1 that is depicted in FIG. 2 generally is built following the same set up as the apparatus 1 depicted in FIG. 1. Therefore, the same numerals are used for the same parts. In particular, the apparatus 1 that is depicted in FIG. 2 also comprises an energy source 4 for generating an energy beam 5 that is guided via an irradiation device 6 in the build plane 7 which is arranged in a process chamber 18. The energy beam 5 is also partially reflected at the build plane 7, for example at the object 2, wherein the reflected part 10 of the energy beam 5 is guided via the irradiation device 6, wherein the reflected part 10 is propagating towards the first determination unit 11.

[0043] Deviant from the setup that is depicted in FIG. 1, the first determination unit 11 is arranged at a transparent wall element 19 that is transparent for the reflected part 10 of the energy beam 5. The transparent wall element 19 can therefore, be deemed as window. Analog to the setup that is depicted in FIG. 1, the first optical filter unit 14 is arranged between the build plane 7 and the first determination unit 11 with respect to the beam path of the reflected part 10 of the energy beam 5. Besides, the apparatus 1 that is depicted in FIG. 2 also comprises a first beam splitting unit 13 for splitting the initial part 12 off the energy beam 5 which propagates towards the second determination unit 11 to determine the second parameter of the initial part 12 of the energy beam 5. Hence, the determination device 8 of the apparatus 1 is adapted to determine a difference between a reference parameter, in particular the second parameter of the initial part 12 of the energy beam 5 with the first parameter of the reflected part 10 of the energy beam 5. Thus, it can be determined which part or which ratio of the energy beam 5 is absorbed in the build material 3 in the build plane 7 and which part is reflected or scattered at the build plane 7.

[0044] Therefore, a control of the energy that is depleted within the build material 3 is feasible to ensure that a proper amount of energy is absorbed, which directly influences the consolidation behavior of irradiated build material 3 arranged in the build plane 7.

[0045] Further, the determination device 8 according to the exemplary embodiment that is depicted in FIG. 2 comprises a fourth determination unit 20 that is adapted to determine a parameter of radiation emitted from the build plane 7 such as thermal radiation. The third optical filter unit 21 is provided in advance to the fourth determination unit 20 with respect to the propagation path of the radiation emitted from the build plane 7. The third optical filter unit 21 is adapted to filter a part of the energy beam 5, for example the reflected part 10 of the energy beam 5 to ensure that only the thermal radiation is incident on the fourth determination unit 20. For example, it is possible to build the third determination unit 17 as camera and the fourth determination unit 20 as photo diode to ensure that an intensity measurement and a spatially resolved measurement of the intensity distribution of radiation that is emitted from the build plane 7 is possible.

[0046] The determination device 8 of the apparatus 1 depicted in FIG. 1, 2 is further adapted to determine a process parameter, such as the angle of incidence of the energy beam 5 on the build plane 7 and the type of build material that is used, in particular an absorption efficient of the build material 3 used in the additive manufacturing process. Further, the determination device 8 is adapted to determine residues generated in the additive manufacturing process, such as soot, smoke or smolder or non-consolidated build material particles inside the process chamber 18.

[0047] Of course, all features, details and advantages described with respect to the individual embodiments can arbitrarily be exchanged, transferred or combined. Self-evidently, the inventive method can be performed on the inventive apparatus 1, preferably using an inventive determination device 8.