Basic Research On Grinding Steel Rail Based On Brazed Diamond Sheet Composite Grinding Wheel

Under the repeated rolling action of the train wheel,significant signs of wear will appear on the surface of the rail,which needs to be polished and repaired to ensure the safety of the train operation.There is a big gap between the grinding performance of the domestic rail grinding wheel and the foreign grinding wheel.In order to improve the performance of domestic grinding wheel and replace imported wheels,this thesis proposes to embed the brazed diamond abrasive sheet into the resin zirconium corundum grinding wheel,develop a new composite grinding wheel and conduct grinding performance test research on it.The main research work completed in this thesis includes the following aspects.(1)The brazed diamond abrasive sheet of the rail grinding composite grinding wheel was proposed,designed and manufactured,and its shape was improved.The calculation formula of the number of brazing sheets required for a single composite grinding wheel under different grinding conditions is derived,and the wear characteristics of the brazed diamond sheet grinding rail are studied.The results show that as the working pressure increases or the duration of continuous grinding increases,the wear rate of the brazing sheet increases,the grinding ratio decreases,the grinding temperature rises faster,and the proportion of oxides in the wear debris increases.Research shows that brazing sheets are completely feasible for rail grinding.(2)A rail grinding composite grinding wheel with brazing sheet was designed and fabricated.The relationship between the rotary performance of composite grinding wheel and the placement angle of the sheet was studied to improve it.The centrifugal force during the turning of the composite grinding wheel and the stress of the brazing sheets in the wheel are calculated.The brazing sheet in the composite grinding wheel produces a cutting action on the bonding agent,and the cutting action formula is deduced.The composite grinding wheel has good rotary performance when the brazing insert is placed at an angle of 55 degrees,followed by 45 degrees or 60 degrees.For the composite grinding wheel with a diameter of 260 mm,the rotating speed range with strong resonance is 4600 to 4800 rpm.(3)The finite element analysis of the influence of multiple parameters on the rotary performance of the composite wheel shows that: the overall elastic modulus of the composite grinding wheel increases with the increase of the number of brazing sheets.When the brazing sheet is in the middle of the grinding wheel,the width is 15 mm,and the number of brazing sheets contained in a single grinding wheel is 8 pieces or 12 pieces,the composite grinding wheel has better rotation performance.The grinding thermal test and finite element simulation analysis of the composite grinding wheel show that when the composite grinding wheel is used to grind the rail,the grinding surface temperature rise is reduced by more than 9.7 percent,and there is no obvious burn on the rail surface,which shows obvious excellence.(4)Derivation and calculation of grinding force of composite grinding wheel.The diamond and corundum abrasives were simplified into octahedrons and decahedrons respectively,and the formula of unit grinding force of composite grinding wheel was deduced.Based on the measurement of the morphology and spacing of the abrasive of composite wheel,combined with the derivation formula,the basic theory of low grinding force and grinding heat of composite grinding wheel compared with resin grinding wheel is established.(5)The performance test of the brazed diamond sheet composite grinding wheel rail grinding operation was carried out.The test results show that the wear resistance of the developed composite grinding wheel is more than 50 percent compared with the original domestic grinding wheel;compared with the imported optimal grinding wheel,the wear resistance is improved by 16 percent.Compared with the imported grinding wheel,the composite grinding wheel also has the advantages of low surface roughness,small wave grinding,and has stronger adaptability under severe wet conditions.