Vibration Performance And Life Analysis Of Axle Box Bearing Cage For The EMU

Axle box bearing is the main component of the running part of EMU,which plays an important role in connecting the bogie frame and wheelsets and transferring the force between them.The working environment of axle box bearing is complicated and bad.Its performance directly affects the safety of the train.As a key component of bearing,the status of cage during operation affects the working performance of bearing.Therefore,the vibration performance analysis and life prediction of cage are of great significance to ensure the safe operation of bearing.This paper takes the axle box bearing of EMU as the research object.Dynamics and finite element models of axle box bearing and vehicle-track coupling dynamics model of EMU are established.Free modal analysis of intact cages,cracked cages and fractured cages is performed.The external impact load on the axle box bearing is obtained by vehicle dynamics simulation and used as the working conditions for dynamic simulation of the bearing.Through simulation,the influences of different radial loads,different bearing speeds and track excitation on the dynamic performance of the cage are analyzed.According to the analysis results of the transient dynamics of the cage,the stress spectrums of different dangerous positions are compiled.The life of each node is calculated with S-N curve.The life of the cage is estimated based on the calculation results of each node.The results show that:(1)The minimum natural vibration frequency of the cage obtained by modal analysis is 261.11 Hz.While the rotational frequency of the cage under normal operation is 14.57 Hz.So the cage will not resonance under normal operation.(2)The larger stress parts of the cage are mostly distributed in the cage lintel and the connection between side beam and lintel.The maximum stress often appears at the connection between side beam and lintel which is determined as the dangerous part of the cage.(3)The change of radial load has little effect on the dynamic performance of the cage.With the increase of radial load,the skid rate of the cage decreases slightly,the impact force between the roller and the cage and the stress of the cage increase slightly,the position of the center of mass of the cage has no obvious change.(4)Within the working rotate speed range of the EMU axle box bearing,the change of speed has more obvious effect on the dynamic performance of the cage.With the increase of rotate speed,the skid rate of the cage increases,the impact force between the roller and the cage and the stress of the cage increase significantly,the collision between the roller and the cage is more frequent.(5)The impact force between the roller and the cage and the cage stress are slightly increased with the addition of the track excitation.The skid rate of the cage increases slightly,which reduces the stability of the cage.It has no obvious effect on the center of mass position of the cage.(6)Under the condition of track disturbance in normal operation,the life of the cage is significantly reduced compared with that without track disturbance.The average life is only 5.87 years,which meets the use requirements of replacing axle box bearings for EMU in 5-6 years.