APPARATUS FOR ADDITIVELY MANUFACTURING THREE-DIMENSIONAL OBJECTS

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 ( 16 a , 16 b ) intersecting each other at an intersecting point (P 1 ) of pre-definable coordinates within the process chamber ( 8 ) and an optical detecting unit ( 17 ) configured to detect the intersecting point (P 1 ) of the measurement beams ( 16 a , 16 b ) 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 ( 16 a , 16 b ) intersecting each other at a first intersecting point (P 1 ) 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 ).