Thermal Deformation Behavior Monitoring And Intelligent Prediction Of High-speed Motorized Spindle

As an important symbol of national industrial modernization,high speed and high precision CNC machining center will have a huge impact on the national machinery and equipment manufacturing,livelihood,national defense and other important areas.At the same time,high-grade CNC machine tool technology is one of the key areas of breakthrough of "Made in China 2025".As the core component of high-speed CNC machine tools,the performance of motorized spindle greatly affects the machining precision.With a high speed,motorized spindle will inevitably produce the loss,temperature rise and thermal deformation,which will reduce the machining precision,even the performance and life of the motor and bearings.Therefore,to ensure the use of machine tools in the process of stability and reliability,it is of practical significance to focus on the analysis of the temperature rise and thermal deformation of motorized spindle.In this thesis,the relationship between the temperature field and the thermal deformation of the motorized spindle was analyzed.By combining the experimental data with the finite element model,a thermal deformation prediction model of the motorized spindle,based on the optimization of heat transfer coefficient,was established.The main research work were as follows:(1)A test experimental bench for the spindle temperature was set up,a hybrid measurement method for the surface temperature of the spindle was proposed.The contact measurement and non-contact measurement were combined by means of infrared thermal imaging instrument,thermocouple and data acquisition instrument.A hybrid method of measuring temperature was proposed by using contact measurement results to correct non-contact measurement results,which could be used to get more accurate results.(2)The thermal deformation characteristics of motorized spindle were analyzed by the experimental method,and the dynamic and nonlinear laws of the thermal deformation were revealed.The temperature and thermal deformation of spindle were measured by Spindle Error Analyzer.Besides,two significant relationships for spindle,including thermal deformation and spindle speed,the thermal deformation and the surface temperature,were investigated;at the same time,the influence of spindle structure on thermal deformation was also analyzed.(3)Based on the theory of electric machinery,heat transfer,thermoelasticity and finite element,the thermal deformation prediction model of 150MD24Z7.5 spindle was established with the boundary conditions of heat and heat transfer coefficient.The heat transfer coefficients in the model,based on the monitoring temperature data of the spindle,were optimized by Levenberg-Marquardt optimization algorithm.The method could obtain the real-time dynamic heat transfer coefficient.(4)In this thesis,sensitivity of the loss to the prediction error was analyzed.The experimental results showed that the accuracy of the prediction model could reach 91.829%、97.05%、8.47%and 93.36%,respectively,at speed of 5000r/min、8000r/min、10000r/min and 12000r/min.Experimental results showed that the prediction model had a high accuracy.The model can provide the basis for the intelligent prediction of motorized spindle thermal deformation,and lay the foundation for thermal error compensation.