Calibrate a CMM with a calibration laser head at the tool center point

Abstract

Calibration method for a coordinate measuring machine (1), the coordinate measuring machine (1) comprising a drive mechanism for moving a tool carrier (15) relative to a base (11) for approaching a measurement point and comprising a calibration laser head (20) implemented so and attached to the tool carrier (15) so that a laser beam (25), which is emittable by the calibration laser head (20,21), is swivelable around at least two basically perpendicular axes (X,Y,Z) and changes in distance are measurable interferometrically by means of the calibration laser head (20). A set of retro-reflectors (16a-d) is arranged in fixed positions relative to and / or onto the base (11). The method comprises emitting and directing the laser beam (25) towards a first of the set of retro-reflectors (16a-d), whereby a measuring path (26) is defined by the orientation of the laser beam (25), moving the calibration laser head (20) along the measuring path (26) so that the laser beam (25) is kept directed towards the first retro-reflector (16a) according to the measuring path (26) and the reflected laser beam is continuously received at the calibration laser head (20), measuring the change in distance to the first retro-reflector (16a) at a plurality of measuring positions along the measuring path (26) and gathering a machine position for each of the plurality of measuring positions, the machine position relating to a position of the tool carrier (15) relative to the base (11).

Description

technical field [0001] The present invention generally relates to a method for generating calibration data for a coordinate measuring machine (CMM) by means of a guided laser emitting unit and several stationary retroreflectors, wherein the distance between the laser emitter and the corresponding retroreflector is determined. distance changes. Background technique [0002] It is common practice to inspect the workpiece after production is complete on a coordinate positioning device such as a coordinate measuring machine (CMM) in order to check the correctness of predetermined object parameters, such as the size and shape of the object. [0003] In a conventional three-dimensional coordinate measuring machine, the probe is supported for movement along three mutually perpendicular axes (in directions X, Y and Z). Thus, the probe can be guided to any arbitrary point within the space of the measurement volume of the coordinate measuring machine and the object can be measured by...

AI Technical Summary

Problems solved by technology

[0016] Here, too, the entire calibration is quite a complex process (setting the laser tracker at different positions and performing the corresponding measurements at the same CMM position), a major disadvantage of this calibration method is that the calibration should be performed by specially trained the fact that people execute

Moreover, providing this method is comparatively very expensive and time consuming, since at least one precise laser tracking device is required and this device should be placed at positions known with varying precision

Alternatively, more than one laser tracker is provided, making the method even more expensive

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