Research On Vibration Characteristic Analysis And Optimization Method Of High-speed Motorized Spindle

The high speed motorized spindle unit is the core component to realize high speed and high precision machining.It integrates the machine tool spindle and the motor,and realizes the "zero transmission" of the machine tool spindle and the motor.This structure greatly reduces the noise and vibration during high speed machining and improves the machining efficiency.The vibration performance of high-speed motorized spindle directly affects the machining accuracy of workpiece,so it is of great engineering significance to study and optimize the vibration characteristics of the whole system of high-speed motorized spindle.Firstly,the vibration characteristics of high-speed motorized spindle system are analyzed.The rotor-bearing-housing dynamic model of motorized spindle was established by transfer matrix method,and the lateral vibration form of motorized spindle was analyzed.For further analyzing the coupling vibration of electric spindle machine system,considering the influence of the main shaft-the handle joint stiffness,established a simplified model of finite element simulation of motorized spindle electric spindle modal analysis of natural frequency and modal vibration mode,the modal analysis results of motorized spindle for harmonic response analysis,the system frequency response characteristic curve,The results show that the second frequency of the motorized spindle is the weak frequency of the system.At the same time,the weak part of the motorized spindle structure is analyzed,which provides reference for the arrangement of vibration measuring points in subsequent experiments.In order to verify the accuracy of the simulation analysis method,modal and dynamic vibration experiments were carried out on a high-speed motorized spindle.According to the results of simulation analysis,the installation position of the acceleration sensor was determined,the modal test of the motorized spindle was carried out by hammering method,and the dynamic vibration test of the motorized spindle was carried out by selecting vibration measuring points.The experimental results were compared with the results of finite element analysis to study the causes of the errors and verify the simulation accuracy of the established finite element model,which provides a simulation model basis for subsequent research.The bearing position parameters of high speed motorized spindle under assembly constraints were taken as optimization design variables.The assembly constraints between bearing positions of motorized spindle were analyzed,and an improved Latin hypercube sampling method in constraint domain was proposed.The universality of the method was verified by comparison of different examples.An improved constraint domain sampling algorithm was used to generate samples of bearing position parameters of motorized spindle under assembly constraints,and the bearing position parameters samples satisfying assembly constraints were obtained,which avoided sampling and simulation calculation of invalid points.Finally,the optimum design of bearing position of high speed motorized spindle is carried out.The influence of bearing position parameters on the vibration characteristics of motorized spindle was analyzed.The bearing position sample points satisfying the assembly constraints were obtained by the improved Latin hypercube sampling method in the constraint domain,and the sample library was used to drive the simulation model to build a Kriging proxy model of bearing position meeting the accuracy requirements.And the NSGA-II algorithm was used to carry out the optimization design of the motorized spindle bearing position.The results show that the vibration performance of the optimized motorized spindle bearing position scheme is significantly improved compared with the initial design.