Static load distribution analysis of ball screws with nut position variation

The load distribution of balls is the key to affect the gradual wear and the life of the ball screw. Because the structure of ball screw mechanism is complex and closed, it is difficult to experimentally determine the contact loads of balls between the nut and the screw. This paper presents a novel method to analyze the static load distribution of ball screws, which takes into account the nut position variation. In order to investigate the load distribution conveniently, an appropriate transformation coordinate system is established. The axial, torsional and lateral elastic deformations are comprised into the geometric relationship of the groove centers of the screw and the nut by representing the ball screw as beam elements. The nonlinear equations, which take into account the Hertzian contact deformation, are solved iteratively by using the Newton-Raphson numerical method to determine the contact load of each ball. The detailed analysis for the distribution of contact load, contact angle and torsion angle when the nut is located at different positions of the screw. Furthermore, the effects of axial load and original contact angle on load distribution are analyzed. (c) 2020 Elsevier Ltd. All rights reserved.