Study On Thermal Error Modeling And Compensation Of Worm Wheel Gear Grinding Machine

Worm wheel gear grinding machine is the main equipment for batch finishing of small and medium modulus gears.With the development of aerospace,national defense and other fields towards high precision and sophisticated direction,the demand for high precision and high stability worm wheel gear grinding machines is also increasing.The thermal error can account for more than 70% of the machining error of precision machine tools,which seriously affects the stability of machining accuracy.As a typical precision gear grinding machine,the worm wheel gear grinding machine is difficult to predict and compensate its thermal errors because of its compact overall layout and numerous internal heat sources.Therefore,this paper researches thermal error measurement,modeling,and compensation technology based on the YS7232 worm wheel gear grinding machine,it has theoretical guidance value and engineering application value for improving the worm wheel gear grinding machine processing accuracy stability.The main research contents of this paper are as follows:(1)The thermal characteristics of the worm wheel gear grinding machine are studied.By analyzing the structure and movement characteristics of the worm wheel gear grinding machine,the positions of the heat source and heat transfer modes are determined,and the three-dimensional model of the worm wheel gear grinding machine is established to carry out finite element simulation.Combined with the steady displacement cloud diagram and gear grinding process analysis,it is determined that the thermal error in the X direction is the most important thermal error which affects the machining accuracy of the worm wheel gear grinding machine.Based on the analysis of steady-state displacement and temperature cloud maps of key shafting systems,such as spindle,worktable,and X1-axis,the thermal deformation trend of key shafting systems of worm wheel grinding machine is obtained,and the installation mode of displacement sensors and the position of temperature sensors are planned accordingly.(2)The thermal error measurement system of the worm wheel gear grinding machine is designed.According to the structure,motion,and thermal error characteristics of the key shafting systems of the worm wheel gear grinding machine,such as spindle,worktable,and X1 straight axis,the corresponding temperature and displacement data acquisition systems are designed respectively.To measure the X-direction thermal error of the worm wheel gear grinding machine,sets of thermal error measurement experiments were designed and carried out to simulate the thermal deformation of the worm wheel gear grinding machine under different working conditions.The variation law of temperature and thermal error is found by analyzing the collected temperature and displacement data.And the data are strong support for the thermal error modeling of the worm wheel gear grinding machine.(3)The thermal error modeling method of the worm wheel gear grinding machine is studied.A temperature-sensitive points screening method based on the improved binary grasshopper optimization algorithm(IBGOA)is proposed.The screening method takes the results of multiple regression analysis as the evaluation index and uses the supervised learning mechanism to screen the temperature-sensitive points of key shafting of the worm wheel gear grinding machine.The relationship between X-direction thermal error and component temperature rise is deduced by using flexural deformation theory.According to the characteristics of the derivation formula,the Long Short-Term Memory(LSTM)is used as the modeling method of radial thermal error of worm wheel gear grinding machine,and the training flow of the LSTM thermal error model is designed.(4)The thermal error prediction and real-time compensation of the worm wheel gear grinding machine are studied.According to the experimental data,the thermal error models of the IBGOA-LSTM worm wheel gear grinding machine are established.The effectiveness and superiority of the IBGOA temperature-sensitive points screening method and the LSTM modeling method are verified by the model prediction results.The real-time thermal error compensation technology of the worm wheel gear grinding machine based on PLC communication is studied,and the real-time spindle thermal error compensation experiment of the worm wheel gear grinding machine is carried out to verify the feasibility of the compensation method and the prediction ability of the thermal error model.