Research Of Influence Of Oil-air Lubrication On Temperature Characteristic Of High-speed Mechanical Spindle

Thermal error led by temperature rise of rolling bearings in high-speed spindle leads to considerable positioning uncertainty in machining.Thus,it is critical important to control temperature of rolling bearings in mechanical spindle.Oil-air lubrication is effective in controlling temperature rise of rolling bearing in high-speed spindle.This paper focuses on mechanical spindle using oil-air lubrication,develops a mechanical spindle platform,and conducts theoretical and experimental investigations into temperature characteristics of mechanical spindle.Firstly,heat transfer relationship within a mechanical spindle using oil-air lubrication is investigated considering its structures.Based on theory of heat transfer,differential equation of heat conduction in mechanical spindle is derived and solved.Based on emprical equations,heat dissipation equation of forced heat convection led by air stream in oil-air lubrication is introduced.Related examples are given,calculated and analyzed,respectively.Results indicate that temperature rise and distribution is influenced by geometry of mechanical spindle;the larger the flow of air stream in oil-air lubrication is,the stronger heat convection in rolling bearing is.Secondly,a mechanical spindle platform using oil-air lubrication with a dynamic loading device is developed.Concerning existing problems in primary test platform,an improved test platform of mechanical spindle using oil-air lubrication is designed and built,including new air supply system,parameter sensing and measuring system.Thus,equipments and facilities are selected and installed in the improved platform.Furthermore,a dynamic loading device simulating spindle load is developed and installed.Thirdly,evaluation criterion of temperature characteristics of mechanical spindle is proposed based on Taguchi method.Followed by experimental schemes and steps introduced in detail,experiments of influence of oil quantity per hour and air pressure on temperature rise and distribution are carried out.Results show that among all oil-air lubrication parameters,oil quantity per hour weights the most in temperature performance of mechanical spindle while air pressure is second to it,the interaction between these two parameters hardly influences the temperature performance;the best oil quantity per hour is 0.1ml/h in this paper;the increase or decrease of the best oil quantity per hour tends to lead to a larger increase of temperature rise;the increase of air pressure in oil-air lubrication tends to lead to a lower temperature rise in mechanical spindle.Finally,based on theory of BP neural network,a self-study model simulating and predicting temperature performance of mechanical spindle under oil-air lubrication is established.Furthermore,the trained model is used to predict temperature rise in mechanical spindle and validated by experiments.Results show that the biggist result error between experiment and model prediction is within 0.1 centigrade,it demonstrates the neural network model well reflects the non-linear relationship between parameters of oil-air lubrication and temperature characteristics of mechanical spindle using oil-air lubrication.