Study On Formation Mechanism And Suppression Of Saw Tooth In Surface Grinding Of Cemented Carbide Blade

Cemented carbide is widely used in blade processing because of its good properties.The cemented carbide blades are generally processed by grinding,and there are serrated defects on the edge of the cemented carbide blades after grinding.In this paper,the influence factors of the saw tooth defects on the circular edge of cemented carbide inserts were studied,and the formation mechanism of the saw tooth defects was analyzed,so as to seek the best grinding process parameters to match the machine tools.The quality of cemented carbide inserts can be improved by reducing the saw tooth size and scrap rate of blades.The main work of this paper is as follows:(1)The motion track,maximum undeformed chip thickness and grinding force of the circular arc grinding of cemented carbide blade by a single abrasive particle were deduced.The finite element simulation model of grinding cemented carbide with single abrasive particle was established.By calculating the critical value of brittle fracture/plastic removal of cemented carbide material and according to the actual grinding parameters,the simulation experiment parameters were determined.The influences of the grinding process,the maximum undeformed chip thickness,grinding speed and the size of abrasive particles on the grinding force and temperature were studied.(2)The saw tooth defects formation mechanism was studied.The saw tooth defects formation was mainly related to the blade material,structure and the stress generated by grinding.The results show that the large size of WC particles increases the saw tooth rate.Appropriate increase of Co content could reduce cutting edge damage;The large inclination Angle of the blade maked the cutting edge more easily crack and form saw tooth during grinding.Different grinding process parameters would produce different grinding stresses.When the critical value of material fracture was reached,fracture would occur.At the edge,it was easier to form sawtooth.(3)The effect of grinding process parameters on the saw tooth defects and surface roughness was studied.By using single factor experiment and orthogonal experiment,the influences of wheel speed,blade arc rotation speed,grinding depth and grinding wheel size on the saw tooth defects on the circular arc of cemented carbide blade and the surface roughness of the circular arc were analyzed.The results show that the grinding force,saw tooth depth and surface roughness could be reduced with the increase of grinding wheel speed.The increase of arc rotation speed would increase the grinding force,the saw tooth depth and the surface roughness.The reduction of grinding depth could reduce grinding force,saw tooth depth and surface roughness.The increase of grinding wheel size increased the contact area between the abrasive grain and the blade,which increased the grinding force,the saw tooth depth and the surface roughness.(4)In actual processing,the surface quality of the circular arc of the blade could be improved by increasing the grinding wheel speed,reducing the arc rotation speed,reducing the grinding depth,controlling the quality of the blade material and designing the blade structure reasonably.The grinding effect was better when the grinding speed of the wheel was 24m/s,the speed of the wheel was 8°/s,and the grinding depth was0.05 mm,and the grinding force,saw tooth and surface roughness are smaller.