APPARATUS FOR ADDITIVELY MANUFACTURING THREE-DIMENSIONAL OBJECTS

Abstract

Apparatus (1) for additively manufacturing three-dimensional objects (2) by 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) comprising: a process chamber (8) comprising a build plane (7) in which layers of build material (3) are successively layerwise selectively irradiated and consolidated by means of an energy beam (4) during operation of the apparatus (1); a gas stream generating device (9) configured to generate a gas stream at least partly streaming through the process chamber (8) during operation of the apparatus (1), the gas stream being capable of being charged with non-consolidated build material particles (25); and an optical determining device (12) configured to optically determine at least one parameter suitable for characterizing the streaming properties of the gas stream streaming through the process chamber (8).

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 (4), the apparatus (1) comprising: a process chamber (8) comprising a build plane (7) in which layers of build material (3) are successively layerwise selectively irradiated and consolidated by means of an energy beam (4) during operation of the apparatus (1); a gas stream generating device (9) configured to generate a gas stream at least partly streaming through the process chamber (8) during operation of the apparatus (1), the gas stream being capable of being charged with non-consolidated build material particles (25), particularly smoke or smoke residues generated during operation of the apparatus (1), while streaming through the process chamber (8); and an optical determining device (12) configured to optically determine at least one parameter suitable for characterizing the streaming properties of the gas stream streaming through the process chamber (8) during operation of the apparatus (1) at at least one defined location within the process chamber (8).

2. Apparatus according to claim 1, wherein the optical determining device comprises at least one optical measuring unit (13) configured to optically measure at least one measurement value within the process chamber (8), the measurement value being related to the gas stream, and at least one evaluating unit (14) configured to evaluate measurement values measured by the optical measuring unit (13) so as to determine the at least one parameter suitable for characterizing the streaming properties of the gas stream.

3. Apparatus according to claim 2, wherein the at least one optical measuring unit (13) is configured to measure measurement values at different locations within the process chamber (8).

4. Apparatus according to claim 3, wherein the optical measuring unit (13) is configured to measure a plurality of measurement values at different locations within the process chamber.

5. Apparatus according to claim 4, wherein the evaluating unit (14) is configured to evaluate the plurality of measurement values so as to determine the at least one parameter suitable for characterizing the streaming properties of the gas stream in at least one multi-dimensional representation.

6. Apparatus according to claim 1, wherein the optical determining device (12) is configured to optically determine at least one parameter suitable for characterizing the streaming properties of the gas stream on basis of laser-doppler-anemometry and/or on basis of light-sectioning.

7. Apparatus according to claim 6, wherein the optical determining device (12) is configured to optically determine at least one parameter suitable for characterizing the streaming properties of the gas stream on basis of laser-doppler-anemometry, whereby the or at least one optical measuring unit (13) being configured to optically measure at least one measurement value within the process chamber (8), the measurement value being related to the gas stream, comprises a measurement beam generating unit (15) configured to generate a plurality of measurement beams (16a, 16b) intersecting each other at an intersecting point (P1) of pre-definable coordinates within the process chamber (8) and an optical detecting unit (17) configured to detect the intersecting point (P1) of the measurement beams (16a, 16b) within the process chamber (8).

8. Apparatus according to claim 7, wherein the measurement beam generating unit (15) is configured to generate a first plurality of measurement beams (16a, 16b) intersecting each other at a first intersecting point (P1) of pre-definable coordinates within the process chamber (8) and configured to generate a second plurality of measurement beams intersecting each other at a second intersecting point of pre-definable coordinates within the process chamber (8), and the optical detecting unit (17) is configured to detect the first and second intersecting points of the measurement beams within the process chamber (8).

9. Apparatus according to claim 1, wherein the optical determining device (12) is configured to optically determine at least one parameter suitable for characterizing the streaming properties of the gas stream on basis of light-sectioning, whereby the or at least one optical measuring unit (13) configured to optically measure at least one measurement value within the process chamber (8), the measurement value being related to the gas stream, comprises a measurement beam generating unit (15) configured to generate a pulsed measurement beam (16) extending through the process chamber (8), particularly parallel to the build plane (7), and an optical detecting unit (17) configured to detect scattered light generated by interactions between the measurement beam (16) and the gas stream, in particular non-consolidated build material particles (25) within the gas stream, in at least one detection region within the process chamber (8).

10. Apparatus according to claim 1, wherein the least at least one parameter suitable for characterizing the streaming properties of the gas stream streaming through the process chamber (8) during operation of the apparatus (19 is the streaming velocity of the gas stream.

11. Apparatus according to claim 1, wherein the stream generating unit (9) is configured to control the streaming properties of the gas stream on basis of the at least one determined parameter suitable for characterizing the streaming properties of the gas stream.

12. Apparatus according to claim 1, comprising an output interface unit (31) configured to output the at least one determined parameter suitable for characterizing the streaming properties of the gas stream, particularly at least one multi-dimensional representation of the streaming properties of the gas stream.

13. Optical determining device (12) 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 (4), the optical determining device (12) being configured to optically determine at least one parameter suitable for characterizing the streaming properties of a gas stream streaming through a process chamber (8) of the apparatus (1) during operation of the apparatus (1) at at least one defined location within the process chamber (8).

Description

[0037] Exemplary embodiments of the invention are described with reference to the Fig., whereby

[0038] FIG. 1, 2 each show a principle drawing of an apparatus for additively manufacturing three-dimensional objects according to an exemplary embodiment.

[0039] FIG. 1, 2 each show a principle drawing of an apparatus 1 for additively manufacturing three-dimensional objects 2, e.g. technical components, by means of successive layerwise selective irradiation and accompanying consolidation of layers of a powdered build material 3, e.g. a metal powder, which can be consolidated by means of an energy beam 4, e.g. a laser beam or an electron beam. The apparatus 1 can be a selective laser melting apparatus or a selective electron beam melting apparatus, for instance.

[0040] The apparatus 1 comprises a number of structural and/or functional units.

[0041] One exemplary functional unit is an irradiation device 5, particularly an energy beam generating device and/or an energy beam deflecting device, e.g. a scanning device, which serves for selectively irradiating build material layers with at least one energy beam 4.

[0042] Another exemplary functional unit is a build material application device 6, particularly a coating device, serving for applying a layer of build material 3, e.g. in a build plane 7 of a process chamber 8 of the apparatus 1.

[0043] Another exemplary functional unit is a stream generating device 9, e.g. a sucking and/or blowing device, which is configured to generate a gas stream (indicated by arrows 10) streaming through the process chamber 8, i.e. between an process chamber gas inlet 11 and a process chamber gas outlet (not shown). The gas stream is capable of being charged with non-consolidated build material particles 25, particularly smoke or smoke residues generated during operation of the apparatus 1, while streaming through the process chamber 8. The gaseous fluid stream is inert, i.e. a stream of an inert gas, e.g. argon, nitrogen, carbon dioxide, etc.

[0044] The apparatus 1 further comprises an optical determining device 12 configured to optically determine at least one parameter suitable for characterizing the streaming behavior or the streaming properties, respectively of the gas stream streaming through the process chamber 8 during operation of the apparatus 1 at one or more definable or defined location(s) within the process chamber 8. The optical determining device 12 is configured to optically determine respective parameters suitable for characterizing the streaming properties of the gas stream directly inside the process chamber 8. The optical determining device 12 is therefore, configured to directly monitor the streaming properties of the gas stream directly inside the process chamber 8. Hence, the optical determining device is capable of providing direct and extensive information about the streaming properties of the gas stream inside the process chamber 8.

[0045] A respective parameter suitable for characterizing the streaming properties of the gas stream may be the streaming velocity, the streaming profile, etc. Of course, changes, distributions, gradients, etc. of the respective parameter, e.g. streaming velocity, streaming profile, etc., suitable for characterizing the streaming properties of the gas stream can be determined.

[0046] The optical determining device 12 comprises an optical measuring unit 13 configured to optically measure at least one measurement value within the process chamber 8, the measurement value being related to the gas stream, and an analysis and/or evaluating unit 14 (evaluating unit) configured to analyze and/or evaluate measurement values measured by the optical measuring unit 13 so as to determine the respective parameter suitable for characterizing the streaming properties of the gas stream. In other words, the optical measuring unit 13 is configured to provide measurement values related to the gas stream which can be analyzed and/or evaluated so as to determine respective parameters suitable for characterizing the streaming properties of the gas stream, the evaluating unit 14 is configured to analyze and/or evaluate respective measurement values related to the gas stream so as to determine respective parameters suitable for characterizing the streaming properties of the gas stream.

[0047] The optical measuring unit 13 is configured to measure respective measurement values at different locations within the process chamber 8. The optical measuring unit 13 is also configured to measure a plurality of measurement values at different locations within the process chamber 8. In other words, the optical measuring unit 13 is configured to measure a first measurement value at a first location having first spatial coordinates within the process chamber 8 and (simultaneously or subsequently) measure at least one further measurement value at at least one further location having further spatial coordinates within the process chamber 8. Hence, the location at which a measurement value is measured can be automatically or manually arbitrarily defined, chosen, changed, etc.

[0048] The evaluating unit 14 is configured to evaluate the plurality of measurement values so as to determine the respective parameter suitable for characterizing the streaming properties of the gas stream in at least one multi-dimensional representation of the streaming properties of the gas stream streaming through the process chamber 8. The multi-dimensional representation may be a real-time representation.

[0049] According to the exemplary embodiment of FIG. 1, the optical determining device 12 is configured to optically determine the parameter suitable for characterizing the streaming properties of the gas stream on basis of laser-doppler-anemometry.

[0050] According to this embodiment, the optical measuring unit 13 comprises a measurement beam generating unit 15 configured to generate a plurality of measurement beams 16, 16a, 16b intersecting each other at an intersecting point P1 of pre-definable coordinates within the process chamber 8 and an optical detecting unit 17 configured to detect the intersecting point P1 of the measurement beams 16, 16a, 16b within the process chamber 8.

[0051] The measurement beam generating unit 15 may be configured to generate a first plurality of measurement beams 16, 16a, 16b intersecting each other at a first intersecting point P1 of pre-definable coordinates within the process chamber 8 and configured to generate a second plurality of measurement beams intersecting each other at a second intersecting point of pre-definable coordinates within the process chamber 8. Respective first and second pluralities of measurement beams may be generated in simultaneous or timely shifted manner. The optical detecting unit 17 may be configured to detect the first and second intersecting points of the measurement beams within the process chamber 8.

[0052] FIG. 1 shows an exemplary configuration of the optical measuring unit 13. According to this exemplary configuration, the optical measuring unit 13 comprises the measurement beam generating unit 15, an optical assembly 18, and the optical detecting unit 17.

[0053] The measurement beam generating unit 15 is configured to generate a measurement beam 16 and comprises a measurement beam generating source 27, e.g. a laser source, configured to generate the measurement beam 16, e.g. a laser beam.

[0054] The optical assembly 18 is configured to generate a plurality of measurement beams 16a, 16b extend in a vertical direction, i.e. typically in a (substantially) parallel direction to the energy beam 4 used for selectively irradiating and consolidating build material, through the process chamber 8 and intersecting each other at intersecting points P1 within the process chamber 8 and comprises a measurement beam splitter 19 configured to split the measurement beam 16 generated by the measurement beam generating unit 15 in two measurement beams 16a, 16b, an optical modulator 20, e.g. Bragg-cells, configured to modulate the two measurement beams 16a, 16b generated by the measurement beam splitter 19, and an optical refractor 21 (lens).

[0055] The optical refractor 21 is movably supported in at least one translatory degree of freedom of motion (indicated by arrow A1) and a rotatory degree of freedom of motion (indicated by arrow A2) so as to arbitrarily change the intersecting point P1 of the measurement beams 16a, 16b within the process chamber 8 by being moved in the respective degree of freedom of motion. The optical refractor 21 forms part of or is disposed in front of a beam entrance window 22 arranged in a horizontally extending process chamber wall (top-wall) allowing for the measurement beams 16a, 16b to enter the process chamber 8. The beam entrance window 22 may also be movably supported in at least one respective degree of freedom of motion.

[0056] The optical detecting unit 17 comprises at least one optical detector 23, e.g. a photo diode or photo multiplier. The optical detector 23 is movably supported in at least one translatory degree of freedom of motion and/or rotatory degree of freedom of motion (indicated by arrow A3) so as to arbitrarily change the detection region/volume in order to assure detection of the intersecting points P1 of the measurement beams 16a, 16b at different locations within the process chamber 8 by being moved in the respective degree of freedom of motion. The optical detector 23 forms part of or is disposed in front of a detection window 24 arranged in a vertically extending process chamber wall (side-wall) allowing for detecting of intersecting points P1 of the measurement beams 16a, 16b at different locations within the process chamber 8. The detection window 24 may also be movably supported in at least one respective degree of freedom of motion.

[0057] The evaluating unit 14 is assigned to the optical detecting unit 17 by a communication link and hence, communicates with the optical detecting unit 17 to evaluate the measurement values so as to determine the parameter suitable for characterizing the streaming properties of the gas stream.

[0058] According to the exemplary embodiment of FIG. 2, the optical determining device 12 is configured to optically determine the parameter suitable for characterizing the streaming properties of the gas stream on basis of light-sectioning.

[0059] According to this embodiment, the optical measuring unit 13 comprises a measurement beam generating unit 15 configured to generate a pulsed measurement beam 16 extending through the process chamber 8 parallel to the build plane 7 and an optical detecting unit 17 configured to detect scattered light generated by interactions between the measurement beam 16 and the gas stream, in particular interactions between the measurement beam 16 and non-consolidated build material particles 25 within the gas stream, in a detection region/volume within the process chamber 8.

[0060] FIG. 2 shows an exemplary configuration of the optical measuring unit 13. According to this exemplary configuration, the optical measuring unit 13 comprises the measurement beam generating unit 15 and the optical detecting unit 17.

[0061] The measurement beam generating 15 unit is configured to generate a pulsed measurement beam 16 and comprises a measurement beam generating source 27, e.g. a laser source, configured to generate the pulsed measurement beam 16, e.g. a pulsed laser beam, extending in a horizontal direction/plane through the process chamber 8, i.e. in a (substantially) perpendicular direction to the energy beam 4 used for selectively irradiating and consolidating build material 3, through the process chamber 8. The measurement beam generating unit 15 may be movably supported in at least one translatory and/or rotatory degree of freedom of motion so as to arbitrarily change the plane 28 in which the pulsed measurement beam 16 extends within the process chamber 8 by being moved in the respective degree of freedom of motion. The measurement beam generating unit 15 forms part of or is disposed in front of a beam entrance window 29 arranged in a vertically extending process chamber wall (side-wall) allowing for the measurement beam 16 to enter the process chamber 8. The beam entrance window 29 may also be movably supported in at least one respective degree of freedom of motion.

[0062] The optical detecting unit 17 is configured to detect tracer particles, i.e. non-consolidated build material particles 25 within the gas stream, in detection plane 28, i.e. the plane in which the measurement beam 16 extends, within the process chamber 8. The optical detecting unit 17 comprises an optical detector 23, e.g. a camera. The optical detector 17 may be movably supported in at least one translatory and/or rotatory degree of freedom of motion so as to arbitrarily change the detection plane 28 in order to assure detection of tracer particles in different detection planes 28 within the process chamber 8 by being moved in the respective degree of freedom of motion. The optical detector 23 forms part of or is disposed in front of a detection window 30 arranged in a horizontally extending process chamber wall (top-wall) allowing for detecting of tracer particles at different detecting planes within the process chamber 8. The detection window 30 may also be movably supported in at least one respective degree of freedom of motion.

[0063] The evaluating unit 14 is assigned to the optical detecting unit 17 by a communication link and hence, communicates with the optical detecting unit 17 to evaluate the measurement values so as to determine the parameter suitable for characterizing the streaming properties of the gas stream.

[0064] In both embodiments, the stream generating unit 9 may be configured to control the streaming properties of the gas stream, e.g. the streaming velocity, on basis of the determined parameter suitable for characterizing the streaming properties of the gas stream. Hence, on basis of the information on the streaming properties of the gas stream within the process chamber 8, a control loop may be implemented so as to control the streaming properties of the gas stream, i.e. to assure/maintain a gas stream with desired streaming properties.

[0065] Also in both embodiments, the apparatus 1 may further comprise an output interface unit 31 configured to output the at least one determined parameter suitable for characterizing the streaming properties of the gas stream or the streaming properties of the gas stream, respectively, particularly in at least one multi-dimensional representation of the streaming properties of the gas stream. The output interface unit 31 may comprise a graphical interface, e.g. a display, allowing for outputting a graphical representation of the output and/or may comprise a communication interface allowing for communicating a the output via a communication link, e.g. a communication network, to at least one communication partner.