Study On The Effects Of Grinding Rotational Speed And Granularity On Removal Behavior Of Rail Material

Railway has an irreplaceable position in the transportation owing to its characteristics of celerity, safety, convenience and large-carrying capacity. It also has the advantages of little pollution and less restraint affected by natural conditions compared with other transportation. With the rapid development of railway, especially the implementation of high-speed and heavy-haul strategy, the load transfer of the rail/wheel system grows and the wear, damage, etc. appear. Rail grinding has become an economic and effective measure to maintain the rail under the prerequisite of ensuring safety. The interactions between the rail and grinding stone show complicated tribological behavior during grinding process. And the removal of rail material is affected by many factors. Thus, the study on the removal behavior and process of rail material has a guiding significance on improving the grinding quality.A rail grinding friction testing apparatus is developed according to the contact consisting of a grinding stone and two rail specimens. Rail grinding experiments can be carried out under different conditions of grinding rotational speed, rail materials, grinding stone materials and grinding pressure. The influences of grinding rotational speed and granularity on removal behavior of rail material are investigated by the apparatus. And the wear of rail specimens, surface roughness, hardness, temperature-rise, friction coefficient, surface morphology, plastic deformation, micrographs and compositions of wear debris and chatter between the rail and grinding stone are explored.The main conclusions are as follows:1 With the increase of the grinding rotational speed, the friction coefficient of interactions between rail and grinding stone, surface roughness and width of the grooves decrease. The surface of the specimens became smoother. Temperature-rise, wear of the rail specimens, microindentation hardness of rail specimens increase so does the thickness of the plastic deformation layer.2 With the increasing granularity of grinding stone, the friction coefficient of interactions between rail and grinding stone, temperature-rise, microindentation hardness and thickness of the plastic deformation layer increase. The wear of the rail specimens, surface roughness and width of the grooves decreases. The surface of the specimens became smoother, too.3 Wear debris collected during the test and fields is composed of round particles and curled cutting chips and their main compositions are Fe3O4, FeO and Fe. With an increase of the speed of the grinding train, the content of the oxide decrease while the thickness and width of curled cutting chips increase during the grinding process in the fields. In the laboratory, the width of curled cutting chips decrease with the increasing grinding speed and granularity while the content of the oxide increase.4 The higher grinding speed and smaller granularity of grinding stone, the larger grinding accelerations between rail and grinding stone are. And the accelerations decrease gradually during grinding process.