Sliding Bearing Static And Dynamic Characteristics Analysis Of Linear Feed System

With the increased high demands of processing quality and efficiency, feed system of CNC machine tool should not only meet the requirements of static stiffness, but also with good vibration resistance. In this paper, a typical sliding bearing linear feed system was taken as the research object, and its static and dynamic characteristics were studied.Firstly, based on the Hertz Contact, the mathematical model of the ball screw and bearing’s static characteristics was established considering the factor of lead angle and using Traversal method to calculate the dimensionless contact displacement, the influencing of axial working load on the ball screw’s axial contact deformation and stiffness were analyzed, the relationships between helix angle and ball screw statics properties. On this basis, the static model of a feed system was established; the relationships between axial stiffness of feed system and load were established. The calculation results showed that the axial stiffness of feed system increased with the increase of ball screw and bearing’s preload.Secondly, the structural characteristics of the sliding bearing linear feed system was analyzed, and a simplified three-dimensional CAD model was established reasonably using Catia software, feed system was meshed by Hypermesh. In ANSYS, MATRIX27element was used to simulate the dynamic character of joints. The dynamic finite element model of sliding bearing linear feed system was set up.At last, modal and harmonic analysis theory were elaborated. The feed system’s modal was calculated, the first30natural frequencies were listed, and the first10vibration modes were described. Based on the feed system’s Harmonic response analysis, and the relationship among first, second dynamic flexibility and frequency were drawn, and the weak joints were found.The dynamic performance of the feed system was enhanced through optimization scheme.