Identification of Rotary Axes PIGEs of Five-axis CNC Machines with Double Rotary Tables
Aiming at the problems of the accuracy in identifying geometric errors of rotation axis of five-axis CNC machines with double rotary tables,an identification model of PIGEs of rotation axis on absolute coordinate system was proposed.The actual initial coordinates of the tool ball and the workpiece ball in the machine coordinate system were established,and the actual initial position of the workpiece ball in the measured axis was obtained by the inverse matrix.The mathematical model of the double ball bar length changing included installation errors and the PIGEs of the rotation axis was established based on the four measurement patterns.The effects of PIGEs on the measurement pattern were analyzed by simulation.The results show that the parallelism error may not affect double ball bar length changing when the tool ball is at the intersection of the two rotation axis.Finally,8 PIGEs of the rotary axis were identified through experiments,and 4 positional deviations of the rotary axis PIGEs were compensated.The experimental results show that the maximum absolute value of the compensated positional error is reduced from 203.5 μm to 5.1 µm,and the proposed identification model may effectively improve the accuracy of five-axis CNC machines.
five-axis CNC machinerotation axisposition-independent geometric error(PIGE)machine coordinate systemdouble ball bar
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