Quantitative Evaluation and Error Sensitivity Analysis of Accuracy Retentivity of CNC Machine Tools

Aiming at the problem of quantitative evaluation of accuracy retentivity of CNC machine tools. Basic connotation of accuracy retentivity is analyzed. The conception of accuracy retentivity degree is put forward and its accurate mathematical description is also given. On the basis of mathematical description, evaluation model of volumetric accuracy retentivity of machine tools is established based on multi-body theory whereby forming the characterization and expression of accuracy retentivity ability of machine tools. In order to realize error tracing, influence of time varying state of each error term on the volumetric accuracy retentivity degree of machine tools is analyzed by using SOBOL global sensitivity theory. Taking a three-axis vertical machining center as the experimental object, nine kinds of accuracy index were detected for a period of 400 days of long-term tracking test. The variation laws of individual accuracy retentivity degree and volumetric accuracy retentivity degree with time are calculated and analyzed. The sensitivity of error on the accuracy retentivity of machine tool is quantitative evaluated. The effectiveness of proposed method and model are verified.