Research On Self-lubricating Composite Grinding Wheel With Brazed Diamond Inserting Pieces

Rail grinding can effectively improve the service life of rail,and has been widely promoted for its high efficiency and economy.Therefore,it also promotes the development of grinding wheels matching with them.To solve the problem of low service life of the domestic grinding wheel,research group has prepared the composite grinding wheel with brazed diamond inserting pieces,which significantly improved the grinding ratio of the grinding wheel.In order to further improve the grinding performance of the composite grinding wheel to prevent the burn of the rail during the grinding process,embed self-lubricating block by CaF₂ and peek prepare earlier into the original composite wheel to implement self-lubricating performance during the rail grinding.As a result,it improves the lubrication condition in contact zone decreased the grinding force,and finally cuts down the grinding temperature.The main creative contents of this paper are as follows:（1）Based on the structural characteristics of the composite grinding wheel with brazed diamond inserting pieces,design a way of friction reduction which can be used with such wheels:the wheel implements self-lubricating performance.According to the working environment of grinding wheel,CaF₂ is chosen as solid lubricant and PEEK as carrier.（2）Complete the preparation of composite micro-fine powder.Blocks are prepared by cold pressing and pressure-less sintering process.The quality of the sinter and the form of the solid lubricant in the blocks are also investigated.The influence of the content of solid lubricant on the hardness of the block is analyzed,and mainly to the lubrication needs,at the same time take into account the wear resistance and the overall strength of the wheel,the optimum content of CaF₂ is determined to be 30%.（3）Prepare brazed inserting pieces in vacuum sintering furnace with Diamond（40/45）,Ni-Cr alloy filler metal and stainless steel（303^#）,and the binding forms and bonding strength between the interfaces are also verified.（4）Simplified rail grinding model and take completing covering grinding zone as the starting point to calculate how many inserting pieces/blocks per piece of grinding wheel needs at least.Based on the preparation process of phenolic resin grinding wheel,the preparation of self-lubricating composite grinding wheel was completed.（5）The grinding wheels of different standards are tested on the modified rail grinding machine.The grinding performance of self-lubricating grinding wheel was investigated from the increment of grinding motor current and the size and quantity of ball-type debris in grinding.The results show that the new type of self-lubricating grinding wheel has excellent lubrication performance,and the objective of reducing the grinding temperature is realized,and the rationality of the design is confirmed.