Optical measuring probe calibration
The invention relates to a calibration device ( 1 ) and to a coordinate measuring system for measuring the signal-inducing sensing deflection I Tr of tactile measuring probes ( 2 ). A reference surface ( 8 ) of the reference element ( 7 ) is arranged with respect to the field of view ( 9 ) of the detector ( 5 ) in such a way that, in the event of signal-inducing contact of the sensing surface ( 4 ) of the sensing element ( 3 ) with the reference surface ( 8 ), the sensing surface ( 4 ) or parts of the sensing surface ( 4 ) lies or lie in the field of view ( 9 ) of the detector ( 5 ), the detector ( 5 ) and the calculation unit ( 6 ) being able to calculate the precise position of the sensing element ( 3 ) from the detected part of the sensing surface ( 4 ).
1. A calibration device ( 1 ) for measuring the signal-inducing sensing deflection I Tr of tactile measuring probes ( 2 ) which have a deflectable sensing element ( 3 ) having a sensing surface ( 4 ), the calibration device ( 1 ) comprising a detector ( 5 ), preferably a camera or a laser measuring instrument, having a field of view ( 9 ) for detecting the sensing surface ( 4 ) of the sensing element ( 3 ), a reference element ( 7 ) having a reference surface ( 8 ), and a calculation unit ( 6 ), wherein the reference surface ( 8 ) of the reference element ( 7 ) is arranged with respect to the field of view ( 9 ) of the detector ( 5 ) in such a way that, in the event of signal-inducing contact of the sensing surface ( 4 ) of the sensing element ( 3 ) with the reference surface ( 8 ), the sensing surface ( 4 ) or parts of the sensing surface ( 4 ) lies or lie in the field of view ( 9 ) of the detector ( 5 ), the detector ( 5 ) and the calculation unit ( 6 ) being configured to calculate the precise position of the sensing element ( 3 ) from the detected part of the sensing surface ( 4 ).
2. A calibration device ( 1 ) according to claim 1 , wherein the reference element ( 7 ), or the reference surface ( 8 ) thereof, lies inside or outside the field of view ( 9 ) of the detector ( 5 ).
3. A calibration device ( 1 ) according to claim 1 , wherein the reference element ( 7 ) is equipped with one or more nozzles ( 10 ), the nozzles ( 10 ) preferably being oriented towards the reference surface ( 8 ).
4. A calibration device ( 1 ) according to claim 1 wherein the sensing element ( 3 ), or the sensing surface ( 4 ) thereof, is configured in the shape of a sphere or spherical cap.
5. A calibration device ( 1 ) according to claim 1 wherein the calibration device also detects and calculates the position of tools, in particular milling tools.
6. A coordinate measuring system ( 15 ) for machine tools ( 11 ), having a calibration device ( 1 ) according to claim 1 and having a tactile measuring probe ( 2 ), which can be clamped on the tool head ( 12 ) of the machine tool ( 11 ) and has a deflectable sensing element ( 3 ) and a sensing surface ( 4 ) assigned to the sensing element ( 3 ), it being possible for the signal-inducing sensing deflection I Tr of the sensing element ( 3 ) to take place in the direction of the measuring probe longitudinal axis ( 14 ), perpendicularly thereto, or in a direction inclined by an angle (α) with respect to the longitudinal axis ( 14 ).
7. A coordinate measuring system ( 15 ) for machine tools ( 11 ), having a calibration device ( 1 ), according to claim 6 , wherein the sensing element ( 3 ) is deflectable by compression or traction.
8. A coordinate measuring system ( 15 ) for machine tools ( 11 ), having a calibration device ( 1 ), according to claim 6 , wherein the calculation unit ( 6 ) calculates the signal-inducing sensing deflection I Tr of the sensing element ( 3 ) with the aid of the position of the sensing element ( 3 ), determined by the detector ( 5 ), and the position of the tool head ( 12 ).
9. A measurement method for a coordinate measuring system ( 15 ) using the device of claim 6 wherein, in order to measure the signal-inducing sensing deflection I Tr of the measuring probe ( 2 ), the sensing element ( 3 ) of the measuring probe ( 2 ) is initially brought in contact with the reference surface ( 8 ) of the reference element ( 7 ) in such a way that the contact signal is initiated, following which the coordinate measuring system ( 15 ) calculates the sensing deflection I Tr of the measuring probe ( 2 ) with the aid of the previously known length of the measuring probe ( 2 ) and from the position of the clamping point ( 17 ) of the measuring probe ( 2 ) on the tool head ( 12 ) and the position of the sensing element ( 3 ), determined by the detector ( 5 ) and the calculation unit ( 6 ) of the calibration device ( 1 ).
10. A measurement method for a coordinate measuring system ( 15 ) according to claim 9 , wherein, before the measurement of the signal-inducing sensing deflection I Tr , the length of the measuring probe ( 2 ) is determined by the sensing surface ( 4 ) or parts of the sensing surface ( 4 ) of the sensing element ( 3 ) being positioned in the field of view ( 9 ) of the detector ( 5 ), without the sensing element ( 3 ) touching other objects in the process, the detector ( 5 ) and the calculation unit ( 6 ) calculating the precise position of the sensing element ( 3 ) from the detected part of the sensing surface ( 4 ), and the calculation unit ( 6 ) calculating the length of the measuring probe ( 2 ) with the aid of this determined position of the sensing element ( 3 ) and the position of the clamping point ( 17 ) of the measuring probe ( 2 ) on the tool head ( 12 ).
11. A measurement method for a coordinate measuring system ( 15 ) according to claim 9 wherein the position of the deflectable sensing element ( 3 ) is detected again when the measuring probe ( 2 ) is reclamped in the tool head ( 12 ).
12. A machine tool ( 11 ), in particular milling machine or electrical discharge machine, having a coordinate measuring system ( 15 ) or a calibration device ( 1 ) according to claim 1 .