Research On Fatigue Life Of High-Speed Train Axle-Box Bearing Under Fluctuant Impact Load

As an important part of high-speed train transmission system,axle-box bearing has a direct impact on the running safety of train.Therefore,it is very important to evaluate the fatigue life of axle box bearing and evaluate the operation status of axle box bearing.In order to accurately evaluate the fatigue life of the axle box bearing,the fluctuating impact load caused by the track irregularity/wheel flat etc.is considered.The residual service life of axle box bearing is evaluated,and the dynamic performance of axle-box bearing cage is studied.The main contents and conclusions of this paper are as follows:1.Based on the theoretical basis of the fatigue life of rolling bearing,a static model is established for the double row tapered roller bearing used in high speed train axle-box.By calculating the contact load between the inner roller and the raceway of the bearing,the rated life of the bearing is studied,and the main factors affecting the fatigue life of the bearing are analyzed,which lays the theoretical foundation for the prediction of the remaining life.2.Through the establishment of vertical train dynamic system,combined with the railway line conditions,the real load of axle box bearings can be obtained,the remaining life of axle-box bearing can be evaluated.And the failure of plastic cage used in the axle box bearing is analyzed.Combined with the fatigue test of bearing with the initial defect,the bearing empirical life model is built,the remaining life of the bearing after the fatigue spall is assessed.3.According to the analysis of this paper,it can be found that the rated life of the bearing decreases with the increase of the radial load as a power function tendency.With the increase of the axial load,the rated life of the back row of the axial load is increased first and then descended,and the rated life of the front row of the axial load tends to decrease linearly.The increase of the bearing radial clearance will significantly reduce the rated life of the bearing;Through the vehicle-bearing coupling system,the dynamic radial load of the bearing is obtained,and the fluctuation amplitude of which is 3.6 times higher than the first suspension force.By analyzing the impact caused by the wheel flat on the bearing plastic cage,the collision force and the collision frequency of the roller and the cage bridge are increased exponentiallywith the increase of the impact acceleration and the impact time.Thus accelerating the fatigue fracture of the cage.From the impact strength and bending strength analysis of the cage,it will lead to the direct fracture of the cage when the wheel axle acceleration reaches 158 g.The relationship between the bearing vibration value and the defect size/the relationship between the defect size and the speed of the propagation are found by fatigue test of bearing with initial spall bearing.The built-in bearing empirical life model can provide an accurate basis for the final failure judgment of the high speed train axle box bearing.Based on the above analysis,a more comprehensive evaluation of the fatigue life of high-speed axle box bearing can be done.