Study On Analysis Of Grinding Chips Morphology And Wear Behavior Of Grinding Stone In Rail Grinding

Rail grinding is one of the most common maintenance techniques for rail disease treatment.In the process of rail grinding,it is difficult to monitor the material removal process,and detect the wear state of grinding stone,and the rail grinding quality detection method is single.But the grinding chips contain important information about the rail grinding process.Therefore,it is of great significance to study the morphology of grinding chips and the wear behavior of grinding stone in rail grinding to improve the quality of rail grinding.In this paper,the influence of grinding pressure and rail head position on morphology of grinding chips and wear of grinding stone was studied using rail grinding simulation test machine.The formation mechanism of grinding chips and the wear behavior of grinding stone during rail grinding were also discussed;Based on the influence of different grinding stone state on grinding quality and grinding chips morphology,the relationship between rail grinding quality,grinding chips morphology and wear of grinding stone were established.The main conclusions are as follows:（1）According to the different morphology,the grinding chips could be divided into flowing chips,knife chips,slice chips and spherical chips.Flowing chips showed slight burn and the oxidation degree was low;When the proportion of flowing chips was higher,the surface roughness of the rail was smaller.When the proportion of flowing chips was more than 10%,the surface roughness of the rail was less 10μm.The knife chips were burn severely and the degree of oxidation was high.When the proportion of knife chips was higher,the grinding quality was poorer;The slice chips were burn more severely,but the degree of oxidation was low.When the proportion of slice chips was higher,the grinding quality was poorer;The oxidation degree of spherical chips was high,and its proportion was proportional to the grinding temperature.When the proportion of spherical chips was higher than 50%,the rail surface was burn severely and the thickness of the white layer was high.（2）The microstructure of grinding chips was composed of acicular martensite and ferrite.There were about 90%Fe₃O₄ and 8%Fe O in the grinding chips.In addition,it also contained a small amount of Fe₂O₃ and Al Fe₂O₄.Al Fe₂O₄ is the product of chemical reaction between abrasive grains and rail material caused by high temperature during rail grinding.It was easy to produce plastic flow and aggravate abrasive wear.（3）When the grinding position on the rail head was changed from R13 to R80 and R300,the grinding width was increased,and the grinding depth was decreased.The pressure of a single abrasive grain was reduced,the proportion of flowing chips was increased,and the proportion of spherical chips was decreased.With the increase in grinding pressure,the grinding efficiency was improved;the proportion of flowing chips was decreased,and the proportion of spherical chips was increased;the surface scratches and the size of the same type of grinding chips were increased.With the increase in grinding pressure,the amounts of abrasive grains broken,falling off and adhesion clogging were all increased.When the grinding pressure was 2000N,the grinding ratio was the largest.（4）The rail surface quality after grinding was better when the grinding stone was mainly abrasive wear.With the increase in abrasive grains breakage and adhesion clogging,the removal ability of rail material was increased,but the grinding stone wear was intensified,which eventually led to the decrease of grinding ratio.In the process of rail grinding,the grinding stone which was mainly abrasion should be selected for grinding.When the grinding stone was mainly abrasive grains breakage and adhesion clogging,the grinding stone should be replaced.