Design And Tribological Performance Improvement Of Sliding Bearing For Precision Spindle Of Machining Center

The application of hhybrid bearing as a support for high-speed motorized spindle is a developing trend.The hybrid bearing has the characteristics of high rigidity and high accuracy and long operating life.It can improve the stability,reliability and precision of motorized spindle in high speed machining.Based on the research background of precision manufacturing equipment CNC machining center,the design,performance simulation and tribological performance improvement of precision spindle sliding bearing are studied in view of the application requirements of high stability,high reliability and high precision in precision machining.The main contents of this paper are as follows:Aiming at the application requirements of CNC machining center for high speed and precision,the operation environment and characteristics of high precision motorized spindle are analyzed.The design requirement of precision spindle bearing with stiffness and bearing capacity as main parameter is proposed,and the design scheme of bearing is formulated.Several parameters which have great influence on the bearing performance,including the radius clearance h0,the oil cavity depth t0 and the throttle aperture dc,are designed in detail,and three groups of design parameters of bearing are obtained.Then static and dynamic characteristics of-the three groups of bearing is simulated and analyzed,static characteristics include bearing flow Q,bearing capacity F,temperature rise ?T and friction power loss Pf,dynamic characteristics include vertical and horizonal stiffness.According to the result of static and dynamic characteristics,a group of optimal bearing parameters was selected.The fluid-solid-heat coupling charcteristic of hybrid bearing was simulated and analyzed in virtue of Solidworks and Ansys finite element analysis softwares,simulated performances include bearing temperature rise ?T and thermal deformation ?,researching on temperature rise and thermal deformation of hybrid bearing within rated speed.In order to further improve the tribological properties of the hybrid bearing under the condition of particular cases,the microtexture was manufactured on bearing anti-friction layer to improve lubricating performance of bearing,and the performance was estimated with friction-wear test.The abrasive resistance and thermal resistance were improved by adding traces of Ag and graphite to traditional babbitt bearing material,which were estimated with fricyion-wear test and high temperature hardness test.