Investigation Of Dynamic Loads And Reliability Of Axle Box Bearing For Type 25 Passenger Vehicle

The operating mileage of China’s ordinary speed railway has exceeded 100,000 km,which is in the backbone position of railway transportation and plays an important role in economic and social development.As the main type passenger vehicle of China’s ordinary speed railway,the type 25 passenger vehicle continues to move on the highest operating speed under the condition of long-distance traffic and large passenger volume.With the deterioration of wheel-rail service load,axle box bearing is prone to fatigue failure,which further affects driving safety.Therefore,based on dynamics and finite element method,this thesis studies the dynamic load and reliability of axle box bearingfor type 25 passenger vehicle,which has certain engineering application value.The main work includes:(1)Studied the service boundary of axle box bearing for type 25 passenger vehicle.Nine rolling bearing faults of type 25 passenger vehicles in a company are analyzed.It is found that the main phenomenon is the fracture of plastic roller cage,and the radial runout amplitude of the wheel on which the fault bearing is located is more than 2mm.The line test results show that the bearing service load of the vehicle is even worse when the radial runout amplitude of the wheel is much bigger.(2)Studied the bearing vehicle track dynamic coupling model for type 25 passenger vehicle.Based on the rigid-flexible coupling dynamics theory,the wheel set and axle box are considered as flexible bodies.Considering the stiffness characteristics of the bearing,based on the quasi-static theory,the equivalent bearing model is established and embedded into the vehicle model.Finally,the bearing vehicle track dynamic coupling model is constructed.(3)The service dynamic load of type 25 passenger vehicle is studied from the perspectives of vehicle speed,curve radius and wheel polygon wear.The results show that the dynamic response of the bearing increases significantly when the wheel is out of round.Compared with the new wheel,the radial load of the bearing will increase when the order,wave depth of the wheel polygon and vehicle speed are increasing.(4)The internal contact stress and life of the bearing are studied by using the bearing finite element model and ISO281:2007 standard.Compared with the new wheel,the results show that when the wheel is out of round,the contact stress of the outer ring,inner ring and roller for the bearing increase about 3 times,and the bearing life is reduced significantly.Therefore,lathing the wheel regular can improve the service life of the bearing enormously.