Geometric error modeling and sensitivity analysis of a five-axis machine tool

Abstract

It is widely acknowledged that precision design and error compensation are two basic methods to achieve high geometrical accuracy for machine tools. And for these two methods, error modeling and sensitivity analysis are key issues. In this paper, an error modeling method based on multi-body system (MBS) is used to construct the error mapping between error sources and the cutting tool pose error for a five-axis machine tool. According to the error mapping, the traditional definitions of local sensitivity indices (LSIs) and global sensitivity indices (GSIs) are introduced. Based on the LSIs and GSIs, the general local sensitivity indices (GLSIs), general global sensitivity indices (GGSIs), and general global sensitivity fluctuation indices (GGSFIs) are proposed. By using these new indices, error sensitivity analysis of the five-axis machine tool is conducted. According to the error sensitivity analysis results, the precision design of angular error components is conducted in numerical simulation. The results show that by using the proposed sensitivity analysis method, we can improve less error components but get more improvement for the cutting tool accuracy. It indicates that the proposed sensitivity indices and sensitivity analysis method are very effective and meaningful. The proposed sensitivity indices and sensitivity analysis method can also be used in the precision design and error compensation for other machine tools.