Theoretical Study On Microscopic Contact Of Grains And Material Removal For Rail Grinding Using Abrasive Belt

Rail grinding can effectively repair various damages and defects on the rail surface,improve the wheel-rail matching relationship,improve the running stability and safety of the train,and reduce the railway operating costs.Compared with the traditional grinding method of the rail grinding wheel,the rail belt grinding is a new type of grinding technology,which relies on the complicated contact between the contact wheel,the belt and the rail to realize the material removal of the rail surface.Abrasive belt grinding has the characteristics of "elastic contact",and it is not easy to damage the surface of the rail during the grinding process.However,the current research is mainly to combine the abrasive belt and the contact wheel to study the contact mechanism between the contact wheel and the rail,ignoring the topographical characteristics of the abrasive grain on the surface of the abrasive belt,which seriously restricts the actual engineering of the grinding technology.application.Therefore,this paper will deeply study the micro-contact and material removal theory of abrasive abrasive belts,and verify the correctness and effectiveness of the theoretical model by finite element simulation.The main research contents are as follows:The three-dimensional point cloud data of the abrasive grain distribution on the surface of the abrasive belt was measured by a three-dimensional surface profiler based on the white confocal principle.The characteristics of the abrasive grain parameters were extracted according to the "static sanding" process characteristics of the abrasive belt and the international surface texture standard,and the Matlab software was used.The extracted point cloud data is processed,the data file(.ibl)that the system can recognize is generated,and the interface program with Pro/Engineer is written,and the sand strip shape entity modeling of the real parameter features is completed in Pro/Engineer.According to the elastoplastic contact theory,the static contact force balance equation between the abrasive belt and the rail is established,and the contact force and contact state between each abrasive grain and the rail are determined,and the grinding pressure and the abrasive grain of each abrasive grain are obtained.The mathematical relationship between the process parameters such as radius of curvature,negative rake angle,and depth of indentation and the shape and stress distribution of the contact area.At the same time,the ABAQUS finite element software simulation model is established,and the validity of the theoretical model is verified by theoretical and simulation comparison analysis.Based on the static interaction mechanism between the abrasive grains on the surface of the abrasive belt and the surface of the rail,considering the actual working conditions of the abrasive belt grinding,the physics model of abrasive grinding on the surface of the abrasive belt is established according to the cutting theory to determine the grinding force of the abrasive grains.The time course of the process,the dynamic change of the stress and the grinding depth in the contact area between the abrasive grain and the rail on the surface of the abrasive belt,and the process parameters such as the grinding pressure and the negative rake angle of the abrasive grain,the internal stress and the grinding in the contact area between the abrasive grain and the rail.The influence law of depth is used to establish the dynamic contact model of abrasive belt grinding in the grinding process.The finite element simulation model is established by ANSYS/LS-DYNA,and the simulation verification and analysis are carried out.According to the dynamic contact model of the abrasive grain grinding on the surface of the abrasive belt,combined with the characteristic size of the abrasive grain parameters,the method of material removal rate of the abrasive belt grinding belt is established from a single abrasive grain to multiple abrasive grains and two-way integral method.The theoretical model is used to analyze the influence of various process parameters on the material removal rate.At the same time,experiments were carried out by a rail grinding test bench to verify the theoretical model.