Experimental Study On The Matching Behavior Of Grinding Wheels And Rails During Rail Grinding

Grinding wheel is an important tool in rail grinding.The performance of grinding wheels is affected by many characteristics such as the abrasive material,granularity,grinding wheel hardness and the binder.The unreasonable selection of grinding wheel will reduce the grinding efficiency and quality,shorten the grinding wheel service life and increase the rail maintenance cost.Therefore,studying the influence of grinding wheel characteristics on rail material removal behaviors,and matching the appropriate grinding wheels to different rails have the great significance to improve the grinding quality and efficiency.Using the rail grinding simulation test machine,five grinding wheels with different abrasive compositions(zircon corundum grinding wheel,brown fused alumina grinding wheel,zircon corundum and brown fused alumina mixed grinding wheels),three grinding wheels with different mixed granularities(F16:F24=1:1,F16:F24:F36=2:1:1,F20:F24=1:1),and four grinding wheels with different hardness grades(N,P,R,T)were used to study the influence of the abrasive compositions,granularity and hardness on the removal behavior of rail material.The grinding amount,surface roughness,surface morphology,surface hardness,the white layer(WEL),residual stress and debris were analyzed.The wear mechanisms of different grinding wheels were analyzed.The matching behavior of grinding wheels and rail materials was studied.The main conclusions are as follows:(1)Zirconium corundum abrasive grinding wheel had a higher grinding amount of rail than brown fused alumina abrasive grinding wheel.With the increase in the content of brown fused alumina grains in the zirconium corundum grinding wheel(0～30%),the grinding amount decreased slightly.Zirconium corundum grinding wheel produced the larger surface roughness of ground rail,but lower level of surface burn,thinner WEL,and smaller parallel residual stress than brown fused alumina grinding wheel.The addition of a small amount of brown fused alumina grains(10～30%)in the zirconium corundum grinding wheel had no significant effect on the grinding quality.(2)With the increase in the granularity of the grinding wheel,the grinding amount and the surface roughness of the rail decreased,and the thickness of WEL increased.With the increase in the grinding wheel hardness,the grinding amount,the surface roughness and the residual stress showed decreasing trends,but the surface hardness and the thickness of WEL increased.(3)The main wear type of zircon corundum grains was macro-fracture and the brown fused alumina abrasive grains was attrition wear.For the zircon corundum grinding wheels,with the increase in grinding wheel hardness,the main wear type of grinding wheel was changed from grain pullout wear to macro-fracture.(4)Considering the grinding efficiency,grinding quality and grinding wheel service life,the hardness of grinding wheels was matched with rails.PG5 rail was suitable for grinding wheel with the lower hardness grade;U75V and U71 Mn were suitable for grinding wheel with the higher hardness grade.