Research On Electrolytic Polishing Mechanism And Technology Of Cemented Carbide Micro-bits

Electrochemical polishing is a method of surface finishing of metals by electrochemical methods.In this paper,the surface morphology,microstructure,wear resistance and corrosion resistance of the hard alloy micro bit after electrolytic polishing are systematically studied by the method of combining the experimental research and theoretical analysis.The process of Electropolishing of hard alloy micro drill by the orthogonal test method is used in this paper.The RBF neural network model is used to predict the surface roughness of cemented carbide micro drill.The effects of current density,spacing and temperature on the surface roughness,residual stress and surface roughness of cemented carbide samples were studied.Through the friction and wear test,it is found that the surface roughness of the alloy decreases with the increase of current density.When the current density reaches 8 A/dm~2,the polar distance is 20 mm,the polishing time is 120 s,the surface roughness of the hard alloy micro drill reaches a minimum of 0.28.It is found that the influence of process parameters on the surface roughness of the cemented carbide micro drill is the order of current density >time > polar distance.Through the residual stress test,the residual stress of the hard alloy micro drill decreases first and then increases with the increase of the current density.When the current density reaches 8 A/dm~2,the polar distance is 20 mm,the polishing time is 120 s,the residual stress is-238 MPa.Through orthogonal test,the order of influence of process parameters on residual stress is: polar spacing > current density > time.Through the corrosion rate test,the corrosion rate of the hard alloy coating decreases first and then increases with the increase of current density.When the current density is 8 A/dm~2,the polar distance is 20 mm,the polishing time is 120 s,the corrosion rate of the hard alloy coating reaches the minimum of 581 mm/a.The orthogonal experiment shows that the order of influence of process parameters on residual stress is: current density > time > polar spacing.The SEM analysis shows that when the current density is 8 A/dm~2,the polar distance is20 mm and the polishing time is 120 s,the polishing effect is greatly improved,and the wear resistance of the hard alloy micro drill is increased.When the current density is 8 A/dm~2,the spacing is 20 mm,and the polishing time is 120 s,the corrosion products of the cemented carbide micro drill after corrosion are less and the surface is more smooth.From AFM analysis,when the current density is 8 A/dm~2,the spacing between the poles is 20 mm,and the polishing time is 120 s,the particle size of the cemented carbide surface is smaller andevenly distributed on the surface.The RBF neural network prediction model is established by combining the RBF neural network with the hard alloy micro drilling technology.The RBF neural model is used to train the surface roughness data after the cemented carbide micro drill.The final 5sets of experimental data are verified.The minimum error of the surface roughness after the hard alloy micro drill is 3.23%,indicating that the RBF neural network can predict the surface roughness of the cemented carbide micro drill better after the electrolytic polishing.