Synchronous Measurement and Verification of Position-Independent Geometric Errors and Position-Dependent Geometric Errors of Rotary Axes on Five-Axis Machine Tools

This paper presents a synchronous measurement methodology aimed at identifying four position-independent geometric errors (PIGEs) and six position-dependent geometric errors (PDGEs) of the rotary axis in five-axis machine tools. Previous studies and literature have emphasized the challenge of simultaneously measuring and identifying PIGEs and PDGEs of the rotary axis in five-axis machine tools. Therefore, the primary objective of this paper is to propose a measurement methodology that can identify these errors simultaneously through a single measuring process. Compared to commercially available measuring instruments, this measurement system offers several advantages: it is easy to install, cost-effective, and can be applied to various types of five-axis machine tools. These benefits enable the establishment of a fast on-machine error measurement. The initial phase of the research involves establishing a mathematical model and computing the geometric error equations based on the specific type of machine tools in use. Subsequently, the difference between the ideal and actual center positions of the calibration sphere is determined by utilizing a touch-trigger probe while positioning the machine's rotary table at various angles. Finally, the experimental data is inputted into the mathematical algorithm to obtain the PIGEs and PDGEs of the rotary table. Post-experimentation, the PIGEs and PDGEs obtained through the proposed measurement method are incorporated into the controller as compensations. The feasibility of this approach is evaluated by measuring the volumetric errors of the machine tools both with and without compensation. The results demonstrate a significant reduction in the deviation of the volumetric errors, decreasing from 11.97 to 2.31 µm after compensation. This outcome underscores the potential of the proposed method for simultaneous measurement of geometric errors in the rotary axis of machine tools across various types and scenarios.