Analysis Of Thermo-solid Coupling Mechanism Of High-speed Electric Spindle

As the core of machine tools,the performance of motorized spindle plays a decisive role in the quality of machining and cutting.With the trend of high precision,high speed and high efficiency in manufacturing industry,people have higher and higher requirements for the performance of motorized spindle.Having a good thermodynamic performance has become an indispensable condition for ensuring reliability and working stability of high-speed motorized spindle.Based on Hertz contact theory,tribology,heat transfer theory and thermoelastic theory,and taking motorized spindle as the research object,this paper has analyzed the coupling relationship among speed,preload,bearing parameters,temperature field,thermal deformation as well as the cooling system of motorized spindle,then the following results are achieved:(1)Based on Hertz contact theory and raceway control theory,the static load model and pseudo-dynamic model of bearing are established.The effects of axial preload on contact load,contact angle and axial displacement of the bearings in static load are analyzed.The effects of speed and axial preload on contact load,contact angle and contact deformation of the bearings in high speed rolling are also analyzed.The stiffness of bearing is calculated.(2)Based on the theory of tribology and heat transfer,the heat generation of bearing is calculated.The heat transfer model of bearing is established by node network method and the temperature distribution of bearing system is obtained.According to the thermoelastic theory,the axial and radial thermal displacement of each part of the bearing system is calculated.Then the thermal-solid coupling of bearing is analyzed,which contains the effect of speed and preload on temperature rise and thermal displacement as well as the effect of thermal displacement on the bearing parameters.(3)According to the heat node network method and Fourier heat conduction differential equation,the transient heat conduction model of motorized spindle system is established.The transient thermal-solid coupling of the motorized spindle system is analyzed,which contains the relationship among the speed,initial preload and transient temperature field,the transient relative thermal displacement of the bearing and the transient thermal induced preload.Then the transient temperature field and thermal deformation field of the motorized spindle model are simulated by ANSYS,which verifies the correctness of the theoretical calculation model.(4)According to the mathematical model of convective heat transfer,the theoretical model of the motorized spindle cooling system is established,and the influencing factors of cooling effect of motorized spindle cooling system arc analyzed.The cooling system is simulated and analyzed according to the cdifferent structure and different section size of the cooling tank,different flow rate of coolant and different initial temperature of coolant,which provides a reference for the optimization of the motorized spindle cooling system.