Adaptive Identification of the Position-independent Geometric Errors for the Rotary Axis of Five-axis Machine Tools to Directly Improve Workpiece Geometric Errors

Identification of, and compensation for, geometric errors is a cost-effective way to reduce the volumetric errors of five-axis machine tools and thus reduce workpiece geometric errors. An adaptive identification method is introduced to directly reduce workpiece geometric errors. We determined the relation between the root-sum-square values of geometric error sensitivity coefficients and workpiece geometric errors. Then, an optimal measurement path minimizing those values was adaptively determined to identify position-independent geometric errors of the rotary axis. We applied our method to improve the radial deviation of the cone-shaped ISO 10791-7 testpiece, as an example. The radial deviations were 22.6 and 27.6 μm in the counterclockwise (CCW) and clockwise (CW) directions, respectively, after compensating for the position-independent geometric errors identified using a common measurement path. These values improved by 27% and 17% to 16.4 and 22.9 μm in the CCW and CW directions, respectively, after compensating for the position-independent geometric errors identified using the optimal measurement path, thus confirming the validity of our approach.