Research On Influence Of Tool Edge Chamfering On High-Speed Milling Performance And Surface Quality Of Rail Materials

With the vigorous development of railway transportation in China,the damage of rails is becoming more and more serious,which not only reduces the service life of rails,but also affects the stability and safety of train operation.Rail milling and grinding technology is a new type of line maintenance method,in which the milling process is the key step.Milling removes a large amount of material.One-time milling can remove the damage layer on the surface of the rail,and can improve the contour accuracy and smoothness of the rail.However,in the process of high-speed milling,the tools are subjected to periodic mechanical and thermal shocks,causing serious wear and even chipping and damage,which seriously affects the repair efficiency of railway rails.In order to improve the strength and wear resistance o f high-speed milling tools,it is necessary to chamfer the cutting edge of the insert.The chamfer structure will increase the milling force and milling temperature,thus affecting the milling quality.In this paper,for the high-speed milling of U71 Mn high-strength steel,a series of simulation and experimental studies are carried out on the influence of tool edge chamfering on the milling process and tool wear.The main research contents are as follows:(1)Based on the basic theory of metal cutting,the cutting performance of U71 Mn high strength steel is analyzed according to the mechanical prop erties and chemical composition.The material properties and cutting angle parameters of rail milling tools at home and abroad are compared,and the selection bas is of U71 Mn high-speed milling tools is analyzed.(2)The key model parameters of cutting simulation are obtained through literature research and basic experiments.The simulation model of U71 Mn high-speed cutting of rail material is established by DEFORM-2D simulation software,and the influence of chamfering angle,chamfering width and chamfering radius on cutting force,temperature and tool wear is analyzed.And carry out milling experiments to verify the reliability and accuracy of cutting simulation through milling force.(3)Carry out the wear experiment of high-speed milling tools.Explore the influence of tool material and milling speed on the wear of the flank face of the chamfered tool,and analyze the wear form and wear mech anism of the front and flank faces of the tool.Combined with cutting simulation,the wear model of high-speed milling U71 Mn high-strength steel with carbide chamfered tool is established.(4)Carry out the technological test of high-speed milling of U71 Mn with chamfered tools.The single factor method is used to study the influence of milling speed,feed per tooth and radial depth of cut on milling force,milling temperature and surface quality.And establish a multi-objective optimization model of process parameters to provide reference for the development of U71 Mn high-speed and highefficiency milling process.