Analysis of lead screw pre-stretching influences on the natural frequency of ball screw feed system

The accurate prediction and test of the dynamic characteristics of the ball screw feed system are of great significance to the design, manufacture and improvement of the machine tool. At present, the dynamic modeling of ball screw feed system mostly ignores the influence of assembly on the dynamic characteristics of the system. In order to solve the above-mentioned problems, this paper studies the machine tool with both ends fixed ball screw, considering the influences of the pre-stretching of the lead screw on the joint of the screw and the nut. With the lead screw divided into three sections, the lumped parameter model of the ball screw feed system is established, and the influences of the lead screw pre-stretching on the natural frequency of the system are analyzed. The designed auxiliary clamping device is used to measure the frequency response of the system, which includes the translational motion and the rotational motion. The results of the experiments show that the established dynamic model can predict the dynamic characteristics of the system well. The torque wrench and the designed adaptor are used to adjust the pre-stretching of the lead screw, and the frequency response of the system are tested under different pre-stretching conditions of the lead screw. Both theoretical and experimental results show that the pre-stretching of the lead screw has a significant effect on the contact state of the screw-nut joint, which makes the natural frequency of the system change obviously.