Research Of Cathode Design For Electrolytic Dressing Of Metal-bonded Diamond Wheels

Parts with complicated shape, made of high-performance hard-brittle materials such as optical glass, ceramics, semiconductor and artificial crystal, have been applied significantly in the fields of aviation, aerospace, optics, electronics, automobile, military facilities and so on. Those parts need higher precision and lower surface roughness. The precision or ultra-precision machining of parts with complicated profile can be achieved by electrolytic in-process grinding with metal-bonded diamond grinding wheels, which greatly improves the machining efficiency. The shape and dimension accuracy of cathode for wheel dressing decides the precision of profile wheels, and thereby affects the surface precision and roughness of the parts to be ground. Hence, for the ultra-precision grinding of the parts with complicated shape, it is of great significance to design cathode for electrolytic dressing of metal-bonded diamond profile wheels.In this thesis, a mathematical model of electric field was established by analyzing the distribution between the cathode and anode during electrolytic dressing operations. The methods of cathode design were deduced withlaw and the finite element method (FEM), and a concept was put forward to verify the correctness and accuracy of designed results with software ANSYS. The electrolytic dressing cathodes of grinding wheels for the rocker ceramic insert in automobile engines were designed with the law and FEM, respectively. By contrasting and verification, it shows that the cathode design accuracy with FEM is higher than that with the law. Consequently, for the rough grinding of ceramic inserts, the law can be adopted to design the cathode shape for the dressing of profile wheels. However, for a higher grinding precision during the ultra-precision machining of ceramic inserts, the cathode designed with FEM is more accurate and the machined insert is more precise. Base on the mathematical model of the distribution of electric field, key factors, including the profile curvature of the wheels, dressing voltage, the conductivity of electrolyte, current density and current efficiency, etc., were analyzed to achieve more accurate and precise cathode shape for profile wheels dressing Finally, the experiment of electrolytic machining was carried to simulate cathode design. The results indicate that the shape of the cathode designed with FEM is identical with that acquired in the experiment, which proves that it is feasible and accuracy to design electrolytic dressing cathode of profile wheels with FEM.Cathode design with FEM not only indicates the influence of electric field distribution on profile rules exactly, improves the convergence of calculation and gets more precise results, but also supplies with a computer-aided-cathode-design method, which may bring a wide application prospect for the precision and ultra-precision machining and precision electrolytic machining of parts with complicated profile.