Research On Residual Stress State And Influence Factors Of Rail Grinding With Abrasive Belt

With the increasing demand of railway transportation in China,rail maintenance has become more and more important.At present,rail abrasive belt grinding is gradually adopted as a new method of rail maintenance,and the distribution of residual stress after grinding has an important impact on the service of rail,so it is important to study the residual stress after rail abrasive belt grinding and its influencing factors for improving the grinding effect.The main contents of this paper are as follows:Firstly,the grinding force in the process of rail abrasive belt grinding is studied.According to the actual working conditions of rail grinding,the contact state is preliminarily analyzed.The relationship between grinding force and grinding power and belt speed is discussed The range of grinding force ratio in the process of belt grinding is obtained through experiments.Using Hertz contact theory,the contact stress acting on rail surface is modeled theoretically,and the theoretical formulas of contact width and contact length are deduced,which provide a basis for theoretical modeling and finite element simulation of temperature field and stress field.Secondly,based on the research of grinding force in grinding process,the model of total heat flux in grinding area is established.Then,considering the actual grinding process parameters and material parameters,the distribution model of grinding heat flux is established,and the theoretical model of heat flux into rail is deduced.Combining with the theory of heat conduction in grinding principle,the heat source in grinding area is integrated,and the theoretical model of temperature field in grinding area is established.According to the transient module of the finite element method,the temperature distribution in the grinding zone under different grinding parameters is simulated and analyzed.The error between the theoretical results and the simulation results is analyzed,which provides a basis for the analysis of the influence of grinding temperature field on residual stress.Thirdly,according to the analysis results of grinding force and heat,the residual stress field of rail abrasive belt grinding is studied.According to the principle of elasticity,the theoretical models of stress-strain changes caused by grinding force and heat are established respectively.According to the principle of superposition,the stress-strain changes caused by grinding force and heat are superposed.Then,the principle model of residual stress under the coupling effect of force and heat is established by combining the real stress-strain study of rail materials by Tianyue.Using the transient module of structure and temperature in the finite element simulation software,the material properties and environmental factors of rail are set up.The residual stress distribution of rail surface under the coupling of mechanical and thermal forces is simulated respectively.The generation principle and process of surface residual stress are discussed,and the influence of grinding parameters on residual stress is studied.Finally,the residual stress measurement experiments before and after polishing were carried out,and the residual stress values before and after polishing were measured repeatedly at different locations on the rail surface to verify the correctness of the influence of polishing parameters on the distribution of residual stress on the rail surface.The distribution of residual stress on rail surface is an important factor affecting rail service,which provides a theoretical reference for the selection of technological parameters in practical engineering application of rail abrasive belt grinding technology.