Analytical Research On Mechanical Properties And The Optimum Preload Of High-speed Angular Contact Ball Bearings In Motorized Spindle

In order to meet modern processing requirements that high-speed, high-efficiency and high-precision, a new type high-speed motorized spindle will need wide speed characteristics, and it can provide high torque when speed is low and high power when speed is high. That means it can provide high rigidity for low speed and good stability for high speed. It is good way to preload for meet the requirements, so it will be a development trend to active control preload, high-speed angular contact ball bearings is widely used in motorized spindle for good high-speed performance and high rigidity, It is basis to analyze mechanical properties and study on the optimum preload of angular contact ball bearings for active control preload. The paper studies on mechanical properties and the optimum preload of high-speed angular contact ball bearings in motorized spindle. Main research contents are including:1. Based on Hertz contact theory and quasi-dynamic analyzing models of high-speed angular contact ball bearings, analyze the factors which affecting contact angle, contact load, contact pressure, contact ellipse parameters, the ratio of spin to roll, film thickness, contact stiffness and friction torque, compared the mechanical properties of ceramic ball bearings and steel ball bearings, that provide a basis theory for the optimum preload. And calculate the nonlinear equations of ball bearing with newton-Raphson algorithm in Matlab.2. Based on the mechanical properties of high-speed angular contact ball bearings, making research on mode of the optimum preload, considering temperature rise and load distribution, and provide a mode for the optimum preload of angular contact ball bearings high-speed motorized spindle.3. Taking a high-speed motorized spindle as an example, built the3D motorize spindle and use the finite element method to do thermodynamic considering contact and film thermal resistance, and give the relationships between preload and bearing temperature rise, then provide recommended values of preload under different speed by considering bearing temperature rise and load distribution for high-speed motorized spindle. Compare the performance of spindle under controlled preload and constant preload.The result show that axial preload significant impact on bearing performance, and can significantly improve the stiffness of the bearing; preload effect on temperature rise of bearing little when low speed, however preload effect on temperature rise of bearing more when high speed, and speed effect on temperature rise of bearing much more; when the preload can control, it can improve the rigidity of spindle when low speed, promotes about14.9%; and reduce the temperature about6%when high speed.