Accuracy decay mechanism of ball screw in CNC machine tools for mixed sliding-rolling motion under non-constant operating conditions

Abstract

The ball screw (BS) has become an indispensable key functional component in many fields, such as CNC machine tools, precision transmission system, and special service requirements. Its accuracy reliability is a key performance in many application fields. There is a phenomenon of mixed slip-roll motion during the BS operation; however, both non-constant working conditions and mixed sliding-rolling motion mode affect its accuracy decay. In this paper, the modeling method of accuracy decay for mixed sliding-rolling motion behavior is established under non-constant operating conditions. The accuracy reliability of the BS is analyzed under single non-constant operation condition or multiple non-constant operating conditions, and the accuracy decay is predicted though modeling method proposed. In addition, the experimental analysis of the BS accuracy degradation is carried out under three different amplitudes of AL (non-constant axial load), FR (non-constant feed rate), and AL + FR combination conditions. The average value of the accuracy loss relative error (5.90 ~ 8.50%) between theoretical model and experimental test results is smaller than that (11.18 ~ 12.66%) under pure sliding motion. It shows that the accuracy decay analysis model established is beneficial to predict the BS accuracy reliability.