Method for calibrating at least one apparatus for additively manufacturing three-dimensional objects

Abstract

Method for calibrating at least one apparatus (1) for additively manufacturing three-dimensional objects by means of successive layerwise selective irradiation and consolidation of layers of a build material which can be consolidated by means of an energy beam that can be generated via an irradiation element of an irradiation device (7) of the apparatus (1), wherein a determination unit (2) is provided for determining at least one parameter of radiation (3) inside a process chamber (5), wherein a calibration beam source (4) is arranged or generated inside the process chamber (5) of the apparatus (1), in particular in a build plane (9) or a region above the build plane (9), wherein at least one parameter, in particular the intensity, of radiation (3) emitted by the calibration beam source (4) is determined via the determination unit (2).

Claims

1. A method for calibrating at least one apparatus for additively manufacturing three-dimensional objects via selective irradiation of a build material by an energy beam from an irradiation device, the method comprising: generating radiation by a calibration beam source, wherein the calibration beam source is arranged in a build plane of the at least one apparatus; determining, by a determination unit, at least one parameter of the radiation inside a process chamber from the calibration beam source, wherein the at least one parameter comprises an intensity of the radiation from the calibration beam source; and calibrating the irradiation device dependent on the at least one parameter, wherein the calibration beam source is arranged in a receiving unit in the build plane of the at least one apparatus, and wherein the receiving unit is carried on a carrying element of the at least one apparatus.

2. The method of claim 1, wherein the radiation from the calibration beam source comprises a defined radiation pattern.

3. The method of claim 1, further comprising scanning a region of the process chamber comprising radiation from the calibration beam source, wherein the at least one parameter is determined for at least one or more positions in an x- and y-plane.

4. The method of claim 3, wherein the x- and y-plane comprises the build plane of the at least one apparatus.

5. The method of claim 3, further comprising generating a map comprising the at least one or more positions.

6. The method of claim 1, wherein the at least one parameter comprises a maximum intensity.

7. The method of claim 1, wherein calibrating the irradiation device dependent on the at least one parameter comprises calibrating based on a deviation of the at least one parameter from a nominal parameter.

8. The method of claim 1, wherein determining the at least one parameter at least partially occurs when the energy beam is not irradiating the build material.

9. The method of claim 1, further comprising scanning a region of the process chamber dependent on a position of the calibration beam source in the receiving unit.

10. The method of claim 1, wherein generating radiation by the calibration beam source comprises generating radiation of different intensities, wavelengths and/or spot sizes.

11. The method of claim 1, wherein generating radiation by the calibration beam source comprises generating radiation by at least two calibration beam sources.

12. The method of claim 11, wherein the radiation respectively emitted from the at least two calibration beam sources have different intensities, wavelengths and/or spot sizes.

13. The method of claim 1, wherein determining, by the determination unit, the at least one parameter of the radiation inside the process chamber from the calibration beam source comprises at least two determination units for the at least one apparatus determining the at least one parameter.

Description

(1) Exemplary embodiments of the invention are described with reference to the FIG. The FIG. are schematic diagrams, wherein

(2) FIG. 1 shows an inventive apparatus; and

(3) FIG. 2 shows a top view of a build plane of the inventive apparatus of FIG. 1.

(4) FIG. 1 shows an apparatus 1 for additively manufacturing of three-dimensional objects by means of successive layerwise selective irradiation and consolidation of layers of a build material which can be consolidated by means of an energy beam. The apparatus 1 comprises a determination unit 2 that is adapted to determine at least one parameter, for example the intensity, of radiation 3 emitted by a calibration beam source 4. The calibration beam source 4 is arranged in a process chamber 5 of the apparatus 1, wherein the process chamber 5 encloses a volume in which the additive manufacturing process takes place in a regular operation of the apparatus 1.

(5) The apparatus 1 further comprises a control unit 6 that is adapted to calibrate an irradiation device 7 and/or the determination unit 2 dependent on the at least one determined parameter. In this exemplary embodiment of the apparatus 1, the control unit 6 is used to calibrate the determination unit 2, as will be described below. The irradiation device 7 comprises at least one irradiation element (not shown), for example a laser source or an electron source, wherein the irradiation device 7 is adapted to generate and guide an energy beam 8 in a regular mode of operation of the apparatus 1. In other words, an energy beam 8 can be generated and guided in the build plane 9 in which usually build material is arranged to selectively irradiate and consolidate the build material to additively build the three-dimensional object. As the calibration method is performed, the energy beam 8 is not used, e.g. blanked or switched off (indicated via a dashed line). Although not shown, it is also possible to use the energy beam 8 to generate a calibration beam source by irradiating a defined material, such as build material, with the energy beam 8, wherein the material is preferably arranged in the build plane 9. The generated calibration beam source may emit radiation 3, just like the calibration beam source 4, as described before.

(6) In other words, the calibration beam source 4 is arranged inside the process chamber 5, in particular in the build plane 9, which is positioned in the x- and y-plane. The calibration beam source 4 is adapted to emit radiation 3, for example a calibration beam, such as a laser beam, an electron beam or (visible) light with a defined radiation pattern, in particular a defined intensity. In this exemplary embodiment, radiation 3 which is emitted by the calibration beam source 4 propagates towards the irradiation device 7, in particular to a beam guiding unit, such as a x- and y-scanner (not shown). The beam guiding unit is used to guide the energy beam in the build plane 9 in a regular mode of operation of the apparatus 1. The radiation 3 therefore, can be guided via the beam guiding unit of the irradiation device 7 towards the determination unit 2, wherein the x- and y-plane, in particular the build plane 9, can be scanned due to the movement of the beam guiding unit as indicated via lines 10. Thus, radiation 3 that is emitted via the calibration beam source 4 can be detected via the determination unit 2 and the at least one parameter of the radiation 3 can be determined via the determination unit 2.

(7) In the exemplary embodiment depicted in FIG. 1, 2 the calibration beam source 4 is received within a receiving unit 11 (optional) that is carried on a carrying element 12 of the apparatus 1. The carrying element 12 carries a volume of build material in the regular mode of operation of the apparatus 1, for example carrying a powder bed in which the object is additively built by selective irradiation and consolidation. The receiving unit 11 is preferably a high position precision manufactured element, for example a metal plate with a recess for the calibration beam source 4. As described before, it is also possible to irradiate at least one part of the receiving unit via the at least one energy beam.

(8) As indicated in FIG. 2, which shows a top view onto the calibration beam source 4 and the receiving unit 11, additional calibration beam sources 4 can be provided in recesses 13 (indicated via dashed lines). Thus, it is possible that multiple calibration beam sources 4 can be arranged in different positions in the x- and y-plane (indicated via arrow 14). Each calibration beam source 4 can be provided for emitting radiation with a specific wavelength and a specific intensity or at least one calibration beam source 4 can be provided that is adapted to emit radiation with adjustable wavelength and/or adjustable intensity.

(9) The determination unit 2 may in particular determine the at least one parameter of the radiation 3 emitted via the calibration beam source 4 in multiple positions in the x- and y-plane and further generate a map in which the determined parameter is spatially resolved. In other words, for any point or position in the x- and y-plane a value of the determined parameter can be stored. In particular, it is possible to perform operations on the determined parameter, such as finding a minimum value or a maximum volume, respectively. Thus, a maximum determination procedure can be performed in which the determination unit 2 determines the maximum value of the parameter of the radiation 3 that is emitted via the calibration beam source 4 in the x- and y-plane.

(10) The maximum value of the parameter, for example the maximum intensity, can be used for the calibration process. Thus, the maximum determination procedure allows for a positioning the calibration beam source 4 in an arbitrary position in the build plane 9 (the x- and y-plane), wherein exact position of the calibration beam source 4 is identified over the maximum of the at least one parameter derived in the maximum determination procedure. Hence, the position with the highest intensity in the x- and y-plane can be identified as the position of the calibration beam source 4. Thus, a highly accurate positioning of the calibration beam source 4 is not necessary. However, by having a receiving unit 11 that is highly precise manufactured, the area in which the determination unit 2 determines the at least one parameter (scans the build plane 9) can be reduced significantly.

(11) After the at least one parameter of the radiation 3 emitted via the calibration beam source 4 has been determined, the determined parameter can be compared with the (known) nominal value of the parameter, as the calibration beam source 4 comprises a well-defined radiation pattern, for example a well-defined intensity. Deviations between the determined parameter and the known parameter can be taken as basis for the calibration, as the deviations from the defined parameter indicate whether the determination unit 2 is properly calibrated.

(12) For example, if a calibration beam source 4 is used that emits radiation 3 with an intensity of 10W and the determination unit 2 determines an intensity of 20W, the values determined via the determination unit 2 have to be adjusted (calibrated) accordingly. The determination can in particular be performed for different wavelengths or different intensities as the determination unit 2 may require different calibrations for different intensities and/or wavelengths.

(13) In other words, to calibrate the apparatus 1, the calibration beam source 4 is inserted into the process chamber 5, in particular in the build plane 9, preferably using the receiving unit 11. Thus, radiation 3 emitted via the calibration beam source 4 can be detected with the determination unit 2, wherein at least one parameter of the radiation 3 can be determined. Afterwards, the determined parameter can be compared with a nominal parameter to determine whether a deviation between the determined parameter and the nominal parameter is present. Based on the data acquired, calibration data can be generated by the determination unit 2. Of course, it is also possible to calibrate the irradiation device 7 by using the generated calibration data to take the deviations in the determination process performed by the determination unit 2 into calculation for generating the at least one energy beam 8.

(14) Of course, if more than one determination unit 2 is present or different objects are to be manufactured with different energy beams 8, e.g. in different apparatuses 1 or in the same apparatus 1, the determination and, in particular, the calibration process, can be performed for each determination unit 2 or each irradiation device 7.

(15) Self-evidently, the inventive method can be performed on the apparatus 1. The calibration method can, for example, be performed with different properties, such as intensities, wavelengths or sizes of the calibration beam source 4. Thus, different calibration data may be generated for different properties of the calibration beam source 4.