Study On Grinding Thermal Characteristics And Grinding Process Optimization Of Tungsten Carbide Coating Sprayed By High Velocity Oxygen Fuel Spraying

Tungsten carbide coatings prepared by supersonic flame spraying(HVOF)as an excellent substitute for hard chromium plating coatings have high hardness,good fracture toughness,excellent wear resistance and corrosion resistance,and have been widely used in many industrial fields.Due to the limitation of supersonic flame spraying process,tungsten carbide coating needs to be grinded with diamond grinding wheel to ensure its surface integrity.In this paper,the grinding experiment of HVOF tungsten carbide coating is carried out,the grinding temperature field is simulated,and the grinding mechanism and grinding process optimization of tungsten carbide coating are explored.The heat transfer ratio of workpiece is calculated theoretically,and the influence of different grinding parameters on the heat transfer ratio of workpiece is explored.Based on the calculation of heat transfer ratio of workpiece,the grinding temperature field was simulated by ANSYS analysis software.The grinding temperature in the grinding center and near surface area was measured,and the influence of different grinding parameters on the grinding temperature was explored.The simulation model of tungsten carbide coating temperature field was validated by the experimental results.The grinding fluid and wheel for tungsten carbide coating were optimized,and the grinding parameters of tungsten carbide coating were optimized by orthogonal test.Through single factor grinding experiments,the grinding force,surface roughness,surface micro-morphology and the grinding mechanism of tungsten carbide coatings under different grinding parameters were investigated.The results show that with the increase of grinding wheel linear speed,the heat transfer ratio of workpiece increases,and the maximum heat transfer ratio reaches0.573.With the increase of worktable speed and grinding depth,the heat transfer ratio of workpiece shows a downward trend.With the increase of grinding wheel linear speed,the grinding center temperature rises sharply.With the increase of the speed and depth of the worktable,the temperature of the grinding zone surface and near the interface gradually slows down.The maximum grinding temperature is 724 C when the cutting depth is 40 um.The results of simulation and measurement show that the finite element simulation can accurately predict the grinding temperature field and reflect the actual grinding temperature change of workpiece.The results show that the inhibitory effect of grinding fluid I(model:HOCUT 795)on cobalt precipitation isthe best.When the grinding wheel size is 400 mesh,the minimum surface roughness is 0.303.Compared with ceramic bond,resin bond grinding wheel can obtain better grinding surface quality.The optimum grinding parameters of tungsten carbide coatings are suggested by orthogonal test:grinding wheel linear speed v_s=120m/s-150m/s,table speed v_w=2400 mm/min-3200 mm/min,and grinding depth a_p=5-12?m.In the process of tungsten carbide coating grinding,grinding force and surface roughness decrease with the increase of grinding wheel linear speed,but increase with the increase of table speed and grinding depth.Plastic removal and brittle removal occur simultaneously,but the degree of the two removal modes is different with the change of grinding parameters.