Research On Thermal Error Modeling And Compensation Of High-speed Dry-cutting CNC Gear Hobbing Machine

Gear hobbing is the most widely used method to manufacture external gear.With advantages of high efficiency,eco-friendliness,automation and flexibility,the high-speed dry-cutting CNC hobbing machine is becoming more and more widely used for gear hobbing process.With the rapid development of industrial technology,how to improve the accuracy of gear hobbing has become an important research direction in the hobbing process.Since the high-speed dry-cutting CNC hobbing machine has many heat sources,the structure of which is complex,a lot of cutting heat will be generated between the hob and the workpiece during the large-volume hobbing process.With the influence of cutting heat,motor heat and bearing heat,the temperature of the machine tool will rise gradually,forming an uneven temperature field and producing thermal deformation,and eventually forming a thermal error,which will decrease the accuracy of the machine tool seriously.With the optimization of the design method of the gear hobbing machine,the thermal error has become the biggest error source of the hobbing machine,which restricts the development of the hobbing machine and the improvement of the gear hobbing precision seriously.Therefore,the research of thermal error modeling and compensation method for high-speed dry-cutting CNC hobbing machine is of great significance to control the thermal error and improve the hobbing accuracy of gear hobbing machine.In this paper,a type of high-speed dry-cutting CNC hobbing machine is taken as the research object,the thermal error modeling and compensation method of which is analyzed.The main research contents are as follows:(1)Based on the theory of heat transfer,the thermal characteristics of the gear hobbing machine were studied,and the heat transfer mechanism of the gear hobbing machine was preliminarily ascertained.Based on the analysis of the hob assembly structure of the high-speed dry-cutting CNC hobbing machine,the calculation methods of the main heat source and thermal boundary conditions of the hob assembly are studied and clarified,which laid a foundation for the numerical simulation analysis of the thermal characteristics of the hob assembly.(2)The numerical simulation analysis method for the thermal deformation of the hob assembly was studied.In view of the complex structure and the large number of heat sources of the hob assembly,the main heat sources of the hob assembly were calculated and the finite element analysis model of the hob assembly was established basing on the heat transfer and the finite element theory.On this basis,the numerical simulation analysis of the thermal deformation of the hob assembly was carried out,and the steady temperature field distribution and thermal deformation,the transient temperature rise curve and the thermal deformation curve were obtained,which can provide a guidance and reference for the modeling and compensation of the thermal error of the gear hobbing machine.(3)A laser bracket measurement device and platinum resistance temperature sensors were used to obtain the thermal error modeling data of the gear hobbing machine and verify the results of the previous numerical analysis.The cluster regression algorithm was used to obtain the key temperature variables in the temperature measurement points.The thermal error model of the gear hobbing machine was established by the multiple linear regression-least squares method theory,and the relationship between the temperature of the thermal key points of the gear hobbing machine and the relative position change between the hob and the workpiece was revealed.(4)Based on the measurement results of the relative position change between the hob and the workpiece,the influence of the thermal deformation on the machining accuracy was quantitatively analyzed.The thermal error compensation module of the hobbing machine was developed using the SINUMERIK Operate Programming Package for the SINUMERIK 840 D sl CNC system.And the compensation effect was tested,the results of which showed that the thermal error compensation effect of gear hobbing machine is obvious,indicating that the heat error model of the gear hobbing machine is precise and the research method proposed in this paper can provide an effective research tool to improve the machining accuracy of the hobbing machine.