Research On Thermal-mechanical Coupling Modeling And Optimal Design Method Of High-speed Electric Spindle

As the core component of CNC machine tool,the performance of spindle directly affects the machining quality of CNC machine tool.In the processing process of CNC machine tool,the heat generation of spindle is inevitable,and the resulting thermal deformation is an important reason for the decline of machining quality.Based on model 150 Md24y12.5 the grinding of motorized spindle as the research object,and set up considering bearing dynamic parameters of bearing model,quasi statics analysis of bearing internal heat generating mechanism,by means of finite element simulation analysis combined with experimental verification of its internal temperature field and deformation field is analyzed,according to the results of simulation,optimization of the mechanical structure of shaft.Specific research contents are as follows:(1)The force analysis of a single angular contact ball bearing was carried out,and the corresponding nonlinear equations were established.The equations were solved based on Newton-Raphson algorithm and the dynamic parameters corresponding to the calculation of bearing heal generation were obtabined.Based on the outer ring control theory,the spin friction moment of the ball ball was obtained.The influence law of bearing preload and speed change on bearing heat generation is analyzed.The influence law of the deformation of bearing internal components caused by heat generation on the contact Angle,contact load and contact stiffness of bearing is analyzed.It lays a foundation for the study of temperature field of single angular contact ball bearing and the simulation analysis of thermal characteristics of high speed motorized spindle.(2)According to the first part of the research content to solve the bearing heat production as a result,the bearing temperature field based on the finite element method of heat conduction differential equation,by considering the specified temperature,specify the heat generating,specify the convective heat transfer of three kinds of boundary conditions,and to establish differential equation of heat conduction and thermal analysis of the finite element control equation is derived bearing,Through ANSYS simulation software to calculate the heat flux density and the coefficient of convective heat transfer boundary conditions of loading into a single bearing on the change of the analysis of the temperature field,based on the heat transfer theory,calculate the motor,the bearing heating load and the convective heat transfer between each components and loaded into the corresponding parts,thermal characteristic simulation analysis was carried out on the high speed motorized spindle.For mechanical spindle,only the influence of bearing heat generation on temperature field and deformation field of spindle is studied.(3)Taking the preload and speed of the mechanical spindle bearing as the design variables,the stiffness of the bearing,the stiffness of the shaft system and the natural frequency of the shaft system as the state variables,and taking the minimum thermal displacement of the shaft end as the optimization objective,the shaft system was optimized by means of joint optimization of ANSYS and MATLAB.The results before and after optimization are verified by finite element simulation.(4)According to the thermal characteristics simulation analysis of the high-speed motorized spindle,the temperature rise experimental platform is built,and the accuracy of the thermal characteristics simulation results of the motorized spindle is determined by means of simulation and experimental verification.According to the above simulation results of temperature field and deformation field of mechanical spindle obtained by changing the preloading force,an experimental platform of variable preloading force of mechanical spindle was built to verify the accuracy of the simulation results of temperature field and deformation field of mechanical spindle obtained by changing the preloading force.