Research on Extreme Value Distribution of Cutting Force in CNC Lathe Based on Generalized Extreme Value Distribution

Abstract

The extreme value of cutting force is one of the important factors affecting the reliability of machine tools. Correctly establishing its distribution is an important prerequisite for the preparation of CNC machine tool cutting force spectrum and the reliability design of CNC machine tools. In this paper, the cutting force data of the CNC lathe under light, medium and heavy load conditions were obtained by the actual cutting test. The cutting force was sampled by the Block Maximum Method (BMM), and the sample was distributed by the generalized extreme value (GEV) distribution. The chi-square test was utilized to test the goodness of the fitted GEV distribution, and then, the optimal number of blocks in BMM model was determined by comparing values of chi-square test. At last the optimal distribution function of the extreme values was obtained. A reliable distribution model of extreme value for the extrapolation of cutting force extremes and establishment of cutting force spectra is provided in this paper.