Development Of Spindle Bearing Group Reliability Test Bench Based On Variable Preload

With the rapid development of computer and modern design technology,domestic CNC machine tools in research and development,production,assembly and other aspects of the technical level have been significantly improved,but the competitiveness of CNC machine tools is still not strong,the most important reason is machine tools and functional parts of the frequent failure,poor reliability.It is urgent to improve the reliability of CNC machine tools and their functional components.As the core functional component of CNC machine tool,the failure rate of spindle is high because it is in the state of high-speed rotation and complex cutting load impact damage for a long time in the process of machining.Bearing as an important bearing part of the spindle,once the failure will lead to spindle stiffness and rotary accuracy reduced,vibration increased or even can not continue to work,directly affect the machining accuracy and reliability level of the machine tool.In this paper,with the support of the National Natural Science Foundation of China,a reliability test bench for spindle bearing group with variable preload is developed to provide a test bench for its reliability test.The main research contents of this paper are as follows:(1)Overall design of the test bench.Taking a domestic spindle bearing group as the test object,the cutting load condition of the spindle was analyzed,and the axial and radial loading methods were adopted to simulate the cutting load in the actual work.Through statics analysis of single row angular contact ball bearings,combined with bearing preload method,the overall design scheme of reliability test bench of spindle bearing group with variable preload is put forward.(2)Mechanical structure design of test bench.According to the function of the test bench,the mechanical structure of the test bench is designed,including the bearing group test system,the loading system,the mechanical structure of the drive system and supporting equipment.High precision motorized spindle drive bearing group test system operation;The servo motor cylinder simulates the cutting load of the actual working condition;In addition,in order to adjust the preload of the bearing,a preload adjusting device is designed,and a piezoelectric actuator is used to adjust the preload of the bearing.(3)Test bench control and test system design.According to the demand of control and test,choose suitable hardware equipment and test sensor to realize the control of the test bench and the state monitoring of the bearing group;Lab VIEW software is used to design the man-machine interface of the upper computer to realize the control of the test bench and data collection.(4)Carry out the reliability test of spindle bearing group.After completing the assembly and debugging of the test bed,the reliability test of the spindle bearing group is carried out.The stiffness,vibration,rotation accuracy and temperature rise of spindle bearing group under different preload were tested,and the performance of the bearing group was analyzed through the data,providing a basis for reasonable selection of spindle bearing group preload.