The Design Of High-Speed Mechanical Spindle And Fault Diagnosis Method Research For Rolling Element Bearing

The spindle system is one of the most important equipment in high speed machining,whose performance affects the accuracy and efficiency of high speed machining directly.Factors that restrict the performance of spindle system are spindle stiffness and thermal characteristics,the heat problem of spindle bearing and pulley are must be considered in the spindle system.In this paper,a double-end high-speed mechanical spindle is designed based on the requirements of the project.The dynamic and thermal problems of the mechanical spindle are analyzed,and a new method for diagnosing the spindle bearing failure,aiming at the severe spindle vibration problem in the application,is proposed.The main research contents in this paper are as followings:Firstly,in accordance with the requirements of project,a double-end high-speed machine spindle is designed,of which constituent parts such as motor and bearings are selected,and the dynamic analysis is carried out for the mechanical system.Then,the static characteristics are analyzed in Ansys Workbench software,calculating the static stiffness,and static stiffness is caculated by Matlab as well.The rationalisation of the simulation results in Ansys Workbench is testified by comparing the two results.Meanwhile,the optimal values of the front overhang value and bearing span is obtained in Matlab.Then,the dynamic characteristics study of the spindle system are studied in Ansys Workbench to analyze the modal characteristics,which varify that the first-order critical speed is much higher than the designed speed,so that the spindle system can avoid the resonance frequencies range and run steadily.The static and dynamic simulation shows that the structure design is reasonable.Secondly,the thermal characteristics of high-speed spindle bearings and spindle pulley are studied,the heat transfer equation is esablished by thermal resistance network method,and the temperature of the bearing outer ring's center node is calculated by this equation,The rationalisation of the simulation results are testified by comparing the simulation result of Abaqus software with the computed result.The temperature rise of spindle system when changing spindle speed and the viscosity of bearing grease is analyzed with the help of Abaqus software,and the influence rule of spindle speed and the viscosity of bearing grease on temperature rise is obtained.The simulation results show that the spindle system bearings temperature rise are lower than the national standard.Finite element method is used to analyzed thermal deformation of the spindle system under the maximum speed,the thermal deformation analysis results show that the spindle maximum deformation meet the design requirements.Thirdly,the advantages and disadvantages of some fault diagnosis algorithms are studied,then the H-DT-CWT algorithm is proposed for diagnosing bearing fault of spindle system.As an example,Western Reserve University's bearing test data is analyzed by different algorithms,and then the superiority of H-DT-CWT algorithm is determined.Finally,the test platform of spindle system is constructed,researchment of temperature rise of spindle system on different rotate speed is carried out,the test results are in coincidence with finite element analysis results,which indicates that the simulation analysis is reasonable,temperature rise of spindle system's bearing and the pulley are in a reasonable scope.Spindle vibration signal is acquired,and different algorithms are used to analyze test signal under the spindle rotate speed of 1200 r/min,further prove the correctness of H-DT-CWT method for spindle system's bearing fault information recognition.Through theoretical design,simulation analysis and experimental study,the high-speed mechanical spindle system is designed in this paper,and the studies on dynamic and static characteristics of the spindle,thermal characteristics of bearings and belt pulley are carried out for the optimal design of the spindle system.Then,aiming at the severe spindle vibration problem in the application,the algorithm of H-DT-CWT is proposed to diagnose the fault of bearings,which provides a guidance for the design and application of high-speed spindle.