| With the high speed,high precision and high performance development of CNC machine tool.the spindle system supported by hybrid bearings has been widely used in CNC machine tool industry.As one of the core parts of the spindle system,the good bearing capacity and temperature rise characteristics of the hybrid bearing are important for improving the design and manufacturing level of CNC machine tools,and further improving the final machining accuracy of CNC machine tools.At the same time,the spindle system is one of the important components of CNC machine tools,its thermal performance has a great impact on the overall processing quality of the machine tool.In the work process of the spindle system,the heat generation by the hybrid bearing and the motor will cause different thermal deformation of the spindle system,and then affect the machining accuracy of machine tools.Therefore,In the paper,the spindle system and its components of CNC machine tool are taken as the research object,and the thermal characteristics of the hybrid bearings and the spindle system are analyzed.The main contents of this paper include:(1)On the basis of the research of the related literature at home and abroad,the research status and the latest development of the oil film characteristics and the thermal characteristics of the spindle system are summarized.The main content and research method are confirmed.(2)Researching the composition and work principle of the deep-shallow hybrid bearings,theoretical model for the deep-shallow hybrid bearings is built.The pressure distribution of the deep-shallow hybrid bearing is analyzed by the finite difference method and calculates the oil film pressure distribution.(3)3D solid modeling software is used to estabilish the oil film geometric model,the block processing of the oil film,the meshing of the oil film,the physical parameters,the boundary conditions and the solution parameters are setted in the FLUENT.The influence of different oil cavity shape and spindle rotation direction on the oil film load capacity was analyzed.Solving the change condition of the pressure field,temperature field,bearing capacity and flow rate under different parameters,such as speed,oil pressure,eccentricity,oil film thickness,angle of deep cavity and the diameter of the oil inlet hole,and its variation law was analyzed.(4)A three-dimensional model of a spindle system supported by hybrid bearing is established and analyzing the heat resources and heat transfer mechanism,the thermal load and convection heat transfer coefficient of component of the spindle system are calculated and loaded into the finite element model of the spindle system.And then the thermal structure coupling analysis of the spindle system is carried out.The thermal deformation of spindle system is analyzed;the influence of oil supply pressure and spindle speed on the spindle end and radial maximum deformation is analyzed;the influence of motor cooling water flow on the temperature rise and thermal deformation of the motor is analyzed.(5)Based on a set of spindle system thermal characteristics testing system,the temperature of key points on headstock and thermal deformation of spindle were tested.The experimental results were compared with the results of finite element simulation analysis,and the correctness of the simulation results was verified.In this paper,the high precision CNC lathe spindle system and its assembly was taked as the research object,its thermal characteristics were studied.The change of oil film characteristics of bearings under different working conditions and structural parameters is mainly studied,and the temperature field and thermal deformation of the spindle system are analyzed in detail.The research results provide reference for the design of hybrid bearings,and have certain guiding significance for improving the machining accuracy of machine tools. |
PDF Full Text Request