Research On Dry Grinding Mechanism And Technology For U71Mn Rail Material Using The Slotted Wheel

A long-term and repeated rolling will give rise to various damages on the surface of the rails that if cannot be prevented or eliminated immediately,it will cause great safety risks to the train operation."Milling and grinding"is the most common method of repairing rails at present.But the milling cutter is expensive and ordinary corundum grinding wheels under the dry grinding condition tend to cause surface burns on the rail.Therefore,a new high-efficiency and low-cost rail repair method needs to be developed urgently.The purpose of this paper is to put forward a new method to replace the milling cutter and the ordinary corundum grinding wheel of repairing the rail,and to meet the requirements of the large cutting depth of the milling cutter and the grinding accuracy of the ordinary corundum grinding wheel.Firstly,the paper designs a slotted monolayer brazed CBN grinding wheel and develops systematically the grinding technological experiments of rail material in way of comparing with non slotted monolayer brazed CBN grinding wheel,and exposes the dry grinding mechanism of slotted grinding wheel,and then a set of dry grinding technology of slotted grinding wheel for rail material was developed.The specific research contents and the conclusions are as follows:1)A high-efficiency and low-cost rail repair method using the slotted monolayer brazed CBN grinding wheel was proposed.Meanwhile,the research designed and developed reasonably the slotted wheel,including the shape and size of the groove And the suitable matrix material,solder and CBN abrasive were selected.Finally,it is proved that the design of the slotted grinding wheel is safe and reasonable based on the finite element modal analysis.2)The systematic experiments on the grinding of rail materials with slotted grinding wheel were carried out.Firstly,the research preliminary probe into the maximum grinding depth a_p and the range of grinding parameters.Secondly,two comparative tests were conducted that are to investigate the effect of slotted grinding wheel on lowering the grinding temperature compared to ordinary grinding wheel and the effect of different grinding parameter on grinding temperature and force under dry grinding conditions,and to explore the cooling effect of air conditioning cooling compared to the dry grinding.The research shows that the cooling effect of slotted grinding wheel with the cooling rate of 15%-20%is better than the ordinary grinding wheel,while the cooling effect of the cold air is not obvious with average decrease of3)The research on the surface integrity of grinding of rail materials was carried out,and the surface morphology,surface roughness,surface microhardness and surface metamorphic layer were analyzed under different grinding parameters.It is found that under different grinding parameters,groove marks and pits are found in the surface of rail material,but the surface roughness basically meets the requirements of the rail repair(R_a?6?m).In summary,the slotted monolayer brazed CBN grinding wheel has achieved a certain effect in cooling with the large cutting deep and the high efficiency grinding process,and satisfied the needs of the quality of the rail surface matching the rail repair after grinding.