The Measurement Method And Experimental Research Of Lubricating Oil Film Thickness Of Cylindrical Roller Bearings Using Ultrasound

Rolling bearings are the core support components of the engines and spindles.The failure of lubrication can lead to early failure of the rolling bearing in the case of extreme conditions or improper use.As lubricating film thickness is a direct criterion for the lubrication state of the bearing,real-time monitoring of the thickness of the lubricant film is a reliable and effective means of predicting bearing performance.It is of great significance and engineering value for early diagnosis of equipment failure.In this paper,ultrasonic measurement method and experimental study of lubricating film thickness of cylindrical roller bearings are carried out.Based on the ultrasonic propagation law on the interface,the spring model for measuring oil film of bearings was established,otherwise the relationship between the parameters in the spring model and the theoretical calculation error of the film thickness was analyzed.In addition,a new calculation method was proposed to measure the minimum film thickness in the contact zone of rolling bearing.Finite element models of ultrasonic propagation of circular plane sound field and focused sound field were built to analyzing the propagation behavior of ultrasonic waves and the sound field characteristics near the oil film.And the reflection law of the ultrasonic wave at the outer ring-oil film(air)interface and the distribution of the sound field near the oil film layer were obtained.The effects of preset film thickness,ultrasonic excitation parameters and curved surfaces on the calculation results of film thickness were analyzed.According to the comparison of the film thickness calculation results,the focused sound field is more advantageous in measuring the film thickness than the circular plane sound field.In addition,the feasibility of the film thickness distribution of the bearing contact zone and the calculation method of the minimum film thickness were verified by establishing analysis model of the bearing contact zone.On the basis of theoretical and simulation experiments,the related equipment of the ultrasonic measurement system was designed and selected,the ultrasonic measurement system was built,the calibration specimens,calibration test bench and the bearing film thickness measurement test bench were designed.Calibration experiment and bearing film thickness measurement experiment were carried out.The calibration experiment results show that the error of the ultrasonic measurement system is within 10%.The experimental results of the bearing film thickness measurement show that under the fixed load,the minimum film thickness of the bearing increases with the increase of the rotational speed,which is in line with expectations.