Thermal Characteristics Analysis And Modeling Simulation Of Direct-Drive Gear Hobbing Machine

Due to the backward manufacturing and assembly technology,the traditional gear hobbing machine has a large machining error and can only process the gear with low precision.Zero transmission gear hobbing machine,as a modern gear cutting machine tool,using the technique of "zero transmission" to remove the period of transmission chain from the motor to the output shaft,which effectively reduce the machining accuracy impacted by geometric error.However,the workpiece spindle and the hob spindle are both the motorized spindle structure,which makes the heating problem of the main shaft become more prominent,and the proportion of thermal error in the total machining error reaches about 70%.This topic takes the direct-drive gear hobbing machine YK3610 as the research object,and uses the theoretical analysis and simulation test to analyze the thermal characteristics of the direct-drive gear hobbing machine,so as to obtain the thermal deformation rule of the main shaft.Firstly,the overall structure and performance of the direct-drive gear hobbing machine are introduced,and the structural characteristics of the transmission system,machine body and chip removal system are described respectively.The structure of the workpiece spindle and the hob spindle is analyzed emphatically,including the selection and cooling of the internal motor,the selection and the pre-tightening of bearings,the clamping of the workpiece and the configuration of the tool pole.The heat source of the direct-drive gear hobbing machine is analyzed,and the main heat source is the heating of the main shaft system.Then analyzing and calculating the loss heat of the motor and the friction heat of the bearing operation.After analyzing the layout of the internal heat source on the main shaft,the heat transfer mode of the heat source was found,which contains: the convection between the stator housing and the cooling water;The convection between rotor and gas;The heat exchange between the two ends of the rotor and the gas;Heat transfer between the spindle housing and the environment;Heat conduction of rolling body and raceway in bearing.The heat dissipation capacity of the main shaft is studied by using thermodynamic theory to analyze and calculate each heat dissipation method.By using ANSYS analysis software to analyze the steady-state heat of the main shaft model,the temperature field distribution of the workpiece spindle and hob spindle is obtained.After the thermal-structure coupling analysis,the main shaft thermal deformation cloud image was obtained.The results show that the deformation of workpiece spindle is very small along the X direction.In the Y direction and Z direction,the deformation is larger.The hob spindle has a small deformation in the Z direction,and the deformation is larger along the X direction and the Y direction.According to the deformation data,the thermal error of gear machining can be analyzed?The structural improvement scheme is adopted to reduce the thermal deformation of spindle.On workpiece spindle the method is to replace the bolt connection of the rear bracket to the pin connection,so that the fixed mode of the shell is changed from completely fixed to the axial movement along the z-axis.on hob spindle the method is to change the position of the contact ball bearing and the cylindrical roller bearing of the front thrust Angle,so as to extend the deformation of more axial core.The results of simulation analysis show that the bending deformation of the workpiece spindle core is improved obviously,and the deformation amount of the front of the hob spindle core is controlled.Therefore,the scheme effectively improves the machining accuracy of the workpiece.