Experimental Study On Surface Grinding Of Quenching Bearing Steel With Pttterned Grinding Wheels

GCr15harden bearing steel has been widely used in industry due to its high strength and high Hardness.Grinding is one of the most important manufacturing processes for harden bearing steel.However,often the grinding performance is limited by workpiece failure due to a high thermal load in the contact zone.Therefore,in thispaper a new patterning grinding will be introduced.The research focus onreducing the heat in the contact zone by grinding with new kinds ofgrinding tools with a modified grinding wheel topography.In order to investigate the potential of patterned aluminum oxide grinding wheel for enhancing the overall process efficiency,grindingexperiments were conducted.In this paper,the grinding surface temperature,grinding force,surface and subsurface damage are investigated deeply through experiments and theoreticalanalysis.The main studies include:(1)Diamond whisker cutting device was prepared elaborately.Aninnovative method for the machining of patterns into the grindingwheel topography in a flexible and productiveway by using fly-cutting kinematics withdiamond whisker cutting device was presented.Moreover,some cutting parameters,such as the velocities of grinding wheel and patterning tool(vs and vt),as well as the depth of patterning cut(aed)and the feedrate(vf),were selected according to the analysis of the implementation strategy.And experiment of patterning was conducted.(2)The thermocouple technique is the method used formeasuring grinding temperatures in surface grinding experiments with the patterned grinding wheels.The twin pole thermocouple was made by hand which consists of a nickel-chromiumfoil and a nickel-siliconinsulated by three mica sheets sandwiched between twosections of the workpiece.In surface grinding experiments the patterned grinding wheels showed great potential to enhancethe overall grinding performance by significantly decreasing temperatures.Thereduction of the thermal load in the contact zone can be explained by an improved coolant flow throughthe contact zone,which was testified by comparativeexperiments in dry and wet grinding state.(3)During the grinding process of GCr15 annealed bearing steel,the grinding force was measured on line by using the 3–axis piezoelectric dynamometer.Grinding with patterned wheels a reduction of process force up to 30% compared to a non-patterned standard grinding wheel was measured.The patterning process reduces the number of cutting edges and therefore the total amount of microscopic rubbing and ploughing effects,which directly influences the process forces.In addition,workpiece surface roughness,the thickness of the rehardened zone,the grinding burn intensity were measured.The results indicate that the patterned aluminum oxide grinding wheel reducing the effective contact area,decreases process forces,grinding burn and reduce the hardening layer.