Impact failure analysis of re-circulating mechanism in ball screw

A ball screw driven mechanism is a major component in high-speed/high-precision transmitting systems. In such a mechanism, the return tube has been designed to provide the path for a steel ball rolling in screw grooves. As the driven shaft in the mechanism operates at high rotating speed, forces caused by the impact activity between the steel ball and return tube may generate high stresses and cause damage to the return tube after some significant service times. In order to understand the fracture conditions in the return tube, an impact-contact formula is developed and the transient behavior is investigated based on the finite element method in this paper. From results obtained here, it is shown that the rotational speed of the ball screw may affect the service life of the return tube significantly. Factors that affect the service life of the re-circulating mechanism are then described in detail. Further suggestions for the improvement of the return tube in the design/fabrication processes are also proposed in the final part of this paper. (C) 2004 Elsevier Ltd. All rights reserved.