Effect of bearing preload on the dynamic characteristics of the spindle-bearing system

Abstract

Angular contact ball bearings have been extensively utilized in machine tool spindles and the bearing preload plays a significant role on spindle stiffness, rotating precision, heat generation and service life span. With the development of high speed and high precision machining, especially for high speed grinding and milling, both heavy preload at low speed and light preload at high speed must been abled in series in a single machine tool spindle. In order to investigate the effect of the bearing preload on the performance of the spindle, we developed a spindle test rig. In this paper. The effect of bearing preload on the dynamic characteristics of the spindle-bearing system was investigated. The working principle of fixed position preloading method of the spindle-bearing system are introduced. For the spindle that utilizing fixed position preloading method, the theory of assembly dimensional chain was applied to analyze the preloading state of the spindle-bearing system in static conditions. The equivalent parametric identification model was established. The finite element dynamic analysis model of the spindle assembly was developed by taking the advantage of the spring-damper elements to simulate the bearing supports. Finite element analysis (FEA) was conducted to evaluate the effect of the preload on the dynamic characteristics of the spindle-bearing system. This paper not only provides guidance on how to correctly assembling high speed and high precision spindle, but also lay a foundation for the investigation of thermal-mechanical-dynamic characteristic of high speed spindle-bearing system.