Study On The Relationship Between Oil-Air Lubrication Parameters And Thermal Balance Of High-Speed Bearings

Rolling bearing is an important part in the field of machinery industry.With the continuous development of Chinese industry,the application of bearings is more and more extensive,and the speed of bearings is also increasing.When the bearing rotates at high speed,there will be slippage between the roller and the inner and outer rings,the friction between the roller and the inner and outer rings will intensify,which will result in a rapid increase in bearing temperature.If the bearing is not sufficiently lubricated,the raceway surface will be damaged by the excessive temperature,even cause the bearing raceway peeling in serious cases,resulting in instantaneous failure of the bearing,which poses a serious threat to production safety.As a representative of advanced lubrication technology,oil-air lubrication is widely used in high-speed rolling bearings because of its good lubrication performance,low air pollution and suitable for high speed bearings.Although oil-air lubrication has been used in lubrication of most key components,the temperature field distribution of high-speed rolling bearings and the effect of oil-air lubrication parameters on temperature rise of bearings under oil-air lubrication still need to be further studied.Based on the theory of tribology and two-phase flow of rolling bearings and taking the high-speed angular contact ball bearings under oil-air lubrication as the research object in this paper,the oil film distribution simulation model of oil-air lubricated pipeline and nozzle,the temperature field simulation model between high-speed rolling bearings and fluid field are established.The fluid simulation software Fluent was used to simulate the flow state of oil film in oil pipeline and the temperature field distribution between high-speed angular contact ball bearing and fluid under oil-air lubrication.The effects of oil supply,lubricant viscosity,air supply pressure,number of nozzles,rotational speed and preload on the temperature rise of bearing were studied.The results show that the supply pressure and nozzle structure of the oil-air lubrication system have a great influence on the stability and continuity of the oil-liquid annular flow in the oil pipeline under the condition of oil-air lubrication.Optimizing the nozzle structure is beneficial to improving the lubrication stability and lubrication efficiency.In the temperature field distribution,the temperature distribution of the bearing and the fluid field is not uniform.The highest temperature region of the bearing is located on the contact surface between the rolling body and the raceway.The temperature of the rolling element in the bearing is the highest,and the overall temperature distribution of the inner and outer rings is relatively uniform,continuous flow of fluid in the fluid field contributes to heat dissipation of bearings.Under the working conditions,bearing speed and pre-tightening force are important factors affecting friction heat generation of bearings,the temperature of bearings increases with the increase of speed and pre-tightening force.In oil-air lubrication parameters,increasing the air supply pressure and the number of nozzles can increase the air intake and enhance the convective heat transfer between the flowing air and the bearing,which is conducive to the heat dissipation of the bearing and cooling the bearing.Bearing temperature rise is obviously affected by oil supply,the temperature of bearing rise first decreases and then increases with the increase of oil supply.There is an optimum oil supply for bearing under oil-air lubrication condition.The influence of lubricating oil viscosity on bearing temperature rise is related to speed,lubricating oil viscosity has little effect on temperature rise of bearings at low viscosity,but has greater effect on temperature rise of bearings at high viscosity,and the effect increases with the increase of rotational speed.In order to verify the validity of the numerical simulation model,the influence of bearing speed on bearing temperature rise was tested and verified on the basis of the aero-engine dual-rotor bearing test-bed designed by ourselves.The results obtained are in agreement with the numerical simulation conclusions,and the correctness of simulation model is verified.