Theoretical And Experimental Study On Temperature Characteristics Of Railway Double-row Tapered Roller Bearings

The double-row tapered roller bearing is an important supporting component of the axle box unit of the railway vehicle.Its temperature characteristics are one of the main reasons that affect the safe operation of the train.Therefore,the temperature field of the bearing unit with small and uniform temperature rise is very important for the safe operation of the railway vehicle.Based on the theory of quasi-statics,tribology,and heat transfer of rolling bearings,combined with the method of finite element simulation,this paper analyzes the influence of structural parameters and dynamic indexes of high-speed railway double-row tapered roller bearings on the contact load distribution of bearings,and explores the various tribological factors that cause the temperature rise of high-speed railway double-row tapered roller bearings.Based on the multi-point temperature measurement technology,the railway double-row tapered roller bearings are tested,and the circumferential,axial,and radial temperature distribution of the bearings when different parts of the railway double-row tapered roller bearings fail is studied.The main research contents are as follows:（1）The quasi-static contact model of high-speed railway axle box bearing is established respectively when the train is running in straight line and curve.The geometric relationship and kinematic relationship of double row tapered roller bearing are analyzed,and the relevant position size and relative velocity of feature points are obtained.Considering the influence of train load,train running speed,train turning radius,train turning inclination angle,initial preload of axle box bearing and different roller generatrix,the distribution characteristics of internal contact load of railway double row tapered roller bearing under different working conditions are obtained.By comparing with the calculated values of classical bearing mechanical model,the correctness of the model analysis results in this paper is verified.This work provides preparation for the finite element three-dimensional temperature field simulation calculation of railway double row tapered roller bearings.（2）To obtain the temperature field distribution of double row tapered roller bearings for high-speed railway axle box,firstly,the local heat generation at each contact position of the bearing is obtained by calculating the tangential friction force and relative sliding speed between the contact parts of the railway axle box bearing by using the local temperature analysis method.Then,the contact mechanics model of the axle box bearing under the composite load is established,and the heat flow load is applied to the model.Based on the quasi-static model,based on the heat transfer theory and the Elasto-Hydrodynamic Lubrication theory（EHL）,the finite element simulation model of the three-dimensional temperature field analysis of the railway axle box double-row tapered roller bearing is established respectively when the train is running straight and on the curve.The temperature distribution law of the circumferential,axial,and radial directions of the railway axle box bearing under various working conditions is revealed,and the temperature field distribution characteristics of the railway axle box double-row tapered roller bearing are obtained.The results show that with the increase of train running speed,the average temperature rise of inner ring and roller of axle box bearing is higher than that of outer ring,and the steady-state temperature difference can even reach more than 10°C.The simulation results can provide a basis for the design of adaptive thin film thermocouple temperature sensor.（3）Design an adaptive thin film thermocouple temperature sensor for rolling element temperature measurement of railway double-row tapered roller bearings,a fixture for coating and a multi-functional mask.The sensor is prepared by magnetron sputtering technology.Al₂O₃ insulating film,Ni Cr electrode film,Ni Si electrode film and Si O₂ protective film were successively deposited on clean aluminum alloy substrate by JEM-2100 F scanning electron microscope（SEM）.The surface morphology of the prepared films was characterized by Energy Dispersive Spectrometer（EDS）and Scanning Electron Microscope Multimode8Atomic Force Microscope（AFM）.The results show that the surface of each layer is dense and evenly distributed without obvious defects,which meets the preparation requirements of thin film thermocouple temperature sensors.According to the temperature range of the axle box bearing during the actual operation of the train,the static and dynamic calibration and repeatability test of the developed adaptive thin film thermocouple temperature sensor are carried out.The results show that the sensitivity of the sensor can reach 40.69μμμ°C,the maximum repeatability error is 4.55%,and the dynamic response time is 1.42μs.It meets the transient measurement requirements of rolling element temperature when the train runs at high speed.（4）Through the above method,the theoretical and simulation analysis of 353130 B bearing of railway freight car is carried out,and the temperature field distribution characteristics of the bearing are consistent with the TAROL unit,which verifies the feasibility of replacing the TAROL unit experiment of high-speed railway bearing with353130 B bearing of railway freight car.Under the condition of limited space of the bearing,the multi-point temperature measurement test of the inner,outer rings and rollers of the bearing is designed to verify the correctness of the theory and simulation analysis.Through the temperature measurement test of the bearing,the temperature of the roller is higher than that of the inner ring and the outer ring after the temperature is stable.The stable temperature of the roller is 72.02°C,the stable temperature of the inner ring is 65.55°C,and the stable temperature of the outer ring is 64.67°C.According to the experimental conditions,the fault temperature measurement experiment of 353130 B bearing of railway freight car is designed,and the circumferential,axial,and radial temperature distribution characteristics of bearing when different faults occur in railway axle box bearing are obtained.The experimental results of fault bearing temperature measurement show that the bearing temperature field distribution trend will be affected when the bearing fails,and the bearing outer ring fault has the greatest influence on the bearing temperature field.When the bearing outer ring or roller fails,the temperature of the bearing outer ring will gradually be higher than that of the inner ring.Through the research of this paper,an analysis method suitable for the temperature characteristics of railway axle box double row tapered roller bearings is proposed,which breaks through the technical limitation of inaccurate temperature measurement of bearings due to harsh environment and narrow space.The influence of train load,running speed,turning radius and inclination angle on the mechanical characteristics of railway axle box double row tapered roller bearings is revealed.The temperature field distribution of railway axle box double row tapered roller bearings under different working conditions is obtained,and the temperature rise characteristics of railway axle box double row tapered roller bearings when different parts fail is studied.It provides theoretical support and technical guidance for the design,analysis,experimental test,and fault diagnosis of railway double row tapered roller bearings.