Study On The Preload Of High-speed Machine Tool Spindle Bearing

Rolling bearing has many advantages, such as carrying ability, rotation speed and temperature range, low energy consumption, low maintenance easy to change and so on. The high-speed machine tool spindle is the core component of the high-speed precision machine tools, and its support bearing assembly is used more angular contact ball bearing, so angular contact ball bearing performance directly affects the overall performance of the high-speed precision machine tools. In order to improve the service life of the spindle, rotary precision and support stiffness, we need exert axial preload on the spindle bearings. With the improvement of spindle revolutions, preload requirements is also more and more high. Based on the Matlab programming, about the design of high-speed machine tool spindle bearing assembly preload, the main work is as follows:Based on the brief introduction of rolling bearings’fundamental theorem both at home and abroad as well as researches about pre-tightening force in angular contact ball bearing application, the increasing high requirements of bearing technology due to the development of high speed machine tool are highlighted. It is also noted that bearing performances can be dramatically improved given appropriate pre-tightening force and proper control. At last, research objectives and main content of this paper are provided in combination with machine tool application.Basic calculation relationships among bearing parameters are summarized based on fundamental bearing theory. Moreover, the calculation methods of ball bearing’s contact angle and displacement under axial load are derived through the summary and improvement of angular contact ball bearing’s typical static and quasistatic analytical approaches. The calculation method of static stiffness is provided as well based on mechanic analysis.A generalized optimal pre-tightening force computation method which is applicable for high speed machine tool is presented based on the calculation of bearing combination model and rolling bearings’fundamental theorem. It consists of the computation methods for pre-tightening stiffness and temperature field analysis which can be used as the basis for future high speed machine tool pre-tightening force optimization. And the most commonly used bearing combination supporting structure in high speed machine tool spindle is highlighted by a complete exploration of current high speed machine tool spindle structure. Based on fundamental bearing theorem, typical bearing combination’s static and quasistatic analysis methods are presented and in addition, the analytical model and its relevant numerical solution methods under axial as well as combination load is developed respectively. The characteristics of angular contact ball bearing combination such as load distribution, contact load, and contact angle are computed under given working conditions; what’s more, the influences of load, dimension deviation, groove curvature coefficient and rotation speed on bearing’s performance are analyzed (focusing on those factors which influence load distribution); in addition, the necessity of taking dimension deviation into account in bearing combination is derived through theoretical computation and comparison; eventually, the impacts of pre-tightening load and rotation speed on bearing stiffness are computed based on the results of static and quasistatic analysis which provide basis for selecting bearing combination’s pre-tightening force.