Research On Temperature Distribution And Thermal Displacement Of High Speed Spindle

With the rapid development of manufacturing industry,high-speed machining technology is gradually used in vehicles,ships,grinding tools and high-end CNC machine tools because of its high processing speed,good processing quality and other advantages.High speed motorized spindle as the core components of high-end CNC machine tools,its performance directly affects the machining efficiency of the machine tool.With the proposed "Made in China 2025" related policies,there are more and more requirements for manufacturing industry towards high efficiency and intelligence.In the future,the development of high-grade CNC machine tools is also facing more and more challenges.Among them,the heating and thermal displacement of high speed motorized spindle is one of the first problems to be solved in high grade CNC machine tools.This thesis takes 170SD30 motorized spindle as the research object,by reading the related literature,the basic principle of the internal structure of motorized spindle,the heat release and heat release of motorized spindle were investigated.On this basis,the temperature rise test platform of motorized spindle and the motorized spindle heat transfer model of motorized spindle were established.Specific research contents are as follows:(1)The temperature rise test platform was built for motorized spindle,testing the cooling water flow,the cooling water temperature and the compressed air intake pressure in the oil air system.Under the initial conditions of spindle speed 12000r/min and ambient temperature 16 degrees,the cooling effect of three cooling system parameters on motorized spindle was analyzed.The cooling effect of cooling system on motorized spindle was the best when the cooling water flow rate was 0.4m3/h,the cooling water temperature was 15 degrees,and the intake pressure of compressed air was 0.36MPa.(2)Based on the theory of heat build-up,heat release and test on the temperature test of motorized spindle,the temperature model of motorized spindle was established.The model includes the power input equation,bearing heating equation,heat transfer equation and bearing force of the motorized spindle.The 3D modeling and simulation analysis of the 170SD30 motorized spindle was carried out by using COMSOL Multiphysics finite element software.The highest temperature of the motorized spindle appears in the front bearing.The temperature of the motorized spindle decreased gradually from the bearing,the shaft,the rotor to the stator and the shell;the cooling effect of the water cooling system on the stator and shell of the motorized spindle was obvious;the internal air of the motorized spindle was influenced by the axial airflow and the rotation of the shaft,and the internal heat was also accelerated.The influence factors of the motorized spindle temperature rise analysis showed that:the maximum effect of stator temperature was the cooling water flow on the spindle.The spindle temperature decreased rapidly and then gradually stable,after the flow reached 0.4m3/h,the spindle temperature of each part is basically not affected by the flow of cooling water;the spindle speed has the greatest effect on the motorized spindle bearing temperature with the fastest rate of temperature rise;grinding force parameters had the greatest impact on the bearing temperature,but the temperature rise rate was relatively slow.(3)Based on the empirical formula of grinding force,combined with the basic parameters of 170SD30 motorized spindle,the grinding force model was established.The simulation showed that under the load,the temperature of each part of the motorized spindle increased in different degrees.The shaft and the rotor position near the bearing temperature rise was more obvious,front and rear shaft temperature rise was relatively low;motorized spindle temperature distribution to generate axial and radial elongation,and axial elongation was larger;the axial and radial elongation of the rotating shaft was influenced by the temperature distribution of the spindle,and the axial elongation was larger;the change trend of thermal displacement was close to the temperature influence of axial trend;with the grinding force increasing,displacement increment on front end of shaft axis is larger than increment on midpoint of the line connecting front and rear bearings.Based on the temperature distribution of motorized spindle,the displacement of the shaft was analyzed to provide a theoretical basis to effectively reduce the error caused by the grinding force and thermal deformation in the actual grinding processing.