Simulation Study On Temperature Field And Residual Stress During Rail Grinding

Rail grinding is a common rail maintenance measure.During rail grinding,a large amount of grinding heat is generated by the interaction between the grinding wheel and rail.Improper grinding parameters will cause the rail temperature to rise too high,leading to rail burns and large residual stresses,and aggravating rail fatigue damage during the consequent service.Therefore,it has important theoretical significance and engineering guidance value to study the influences of grinding parameters and grinding patterns on the temperature field,thermomechanical coupling stress,and residual stress on the rail.In this paper,a three-dimensional model of rail grinding by a single grinding wheel was established based on the virtual grinding wheel,and the DEFORM finite element software was used to simulate the rail grinding process.The effects of different rail head radii(R13,R80,R300)and grinding parameters(feed speed,grinding depth,rotational speed of the grinding wheel)on the grinding temperature and thermo-mechanical coupling stress were analyzed,and the distributions of residual stress and hardness on the rail after grinding were explored.Meanwhile,the moving heat source method was introduced to transform a grinding wheel into a moving rectangular heat source,and the ABAQUS finite element software was used to simulate and analyze the temperature field of rail ground by PGM96 grinding train(the reparative grinding pattern)and GMC96 grinding train(the rail top grinding pattern and the edge grinding pattern).Main conclusions of this paper are as follows:(1)When the rail was ground by a single grinding wheel,the maximum grinding temperature decreased with the rail head radius and feed speed,and increased with the grinding depth and rotational speed of grinding wheel.(2)In the temperature field of rail ground by the PGM96 grinding train(the reparative grinding pattern),the maximum temperature at different rail head radii on the rail was different:R13>R80>R300.To prevent excessive grinding temperature,the running speed of rail grinding train should be greater than 16 km/h.Compared to the PGM96 grinding train,the grinding temperature field distributions on the rail ground by the GMC96 grinding train(the rail top grinding pattern and the edge grinding pattern)were sparser.When ground by the whole grinding train,the temperature of a certain area on the rail was affected by the grinding wheels at the same and nearby grinding angles.As the distance between the nearby grinding angle and the current angle increased,the effects of the nearby grinding wheel on the grinding temperature of current area were reduced.When multiple grinding wheels were arranged at the same grinding angle,the grinding temperature could gradually increase.(3)During rail grinding by a single grinding wheel,the thermo-mechanical coupling stress was greater than the tensile strength of rail material,and the thermo-mechanical coupling stress increased with the rail head radius and grinding depth,decreased with the feed speed and rotational speed of grinding wheel.(4)After rail grinding by a single grinding wheel,the distributions and shapes of residual stress field on the rail were similar with the grinding temperature field.The residual stress decreased with the rail head radius and feed speed,increased with the grinding depth and rotational speed of grinding wheel.(5)After rail grinding by a single grinding wheel,the hardness of rail in the grinding area increased obviously.The hardness of the center area on the grinding belt was higher,and gradually decreased to the surrounding area.The hardness on the rail section decreased with the depth of rail material.