PIGEs Identification of Rotary Axes Based on PIGEs Influences on Their Owner Rotary Axes for the Five-Axis Machine Tool

The geometric error compensation is one cost-effective approach to enhance the accuracy of the machine tool. Position-independent geometric errors (PIGEs) of rotary axes introduce extra great influence on the accuracy of the five-axis machine tool. In this work, the ballbar-based PIGEs identification of rotary axes is presented by analyzing the influences of PIGEs on the local frames. First, the influences of squareness errors for the rotary axis are explained in detail based on the physical definition-based mechanism analysis, which are angular errors in two directions of the local frame changing with the rotation of the rotary axis. The local error vectors of PIGEs for the rotary axis are established. Second, three measurement strategies and the identification formula for PIGEs of the rotary axis are proposed based on the ballbar reading model-based identification Jacobian matrix. Two reference points of the ballbar on the axial line of the measured rotary axis are designed according to the requirement of full rank of the identification Jacobian matrix. For each measurement strategy, the single motion of the measured rotary axis is needed. The accuracy of three measurement strategies and the universality of different rotary axes are also discussed. Third, simulations are proposed to testify three measurement strategies by considering the influences of position-dependent geometric errors (PDGEs). The comparisons with two existing methods are carried out to validate the effectiveness of the proposed methods. At last, measurement, compensation experiments, and the workpiece cutting experiments are conducted with the SmartCNC-DRTD five-axis machine tool for the validation.