Study on the forming law of ECM of non-planar “T” shaped cavities based on multi-physical field coupling

In order to solve the problem of complicated electrochemical machining and unpredictable moulding morphology of shaped hot forging model cavities, this paper takes the “T” shaped cavity made of 40CrNiMoV as the research object. Firstly, the electrolyte formulation development test was carried out for 40CrNiMoV material, and the most suitable electrolyte formulation was selected as 8%NaCl + 11%NaNO 3 composite electrolyte through the measurement and analysis of the polarisation characteristic curve. Secondly, a multi-physical field coupling simulation model of electric field, gas–liquid two-phase flow field, temperature field and structural field is established, and based on the COMSOL software, the flow rate, temperature and bubble rate of electrolyte under different process parameters affect the law of anode surface forming accuracy, and the simulation results show that when the inlet pressure is low, the gap electrolyte flow rate of less than 5 m/s is larger, and it is easy to produce the phenomenon of passivation, which will lead to the temperature and bubble cannot be discharged in time, making the forming accuracy lower; in the electrolytic processing of the cavity bubble rate compared to the temperature has a greater impact on the conductivity, accompanied by the voltage increases, more heat and bubbles are generated in the processing gap, making the cavity forming accuracy worse; higher cathode feed rate can effectively improve the taper of the cavity side wall, so the cathode side wall insulation can avoid excessive corrosion of the non-processing surfaces, and the processing accuracy is significantly improved compared to the uninsulated. Therefore, insulating the cathode side wall can avoid excessive corrosion on the non-machining surface and improve the machining accuracy significantly. Finally, validation tests were carried out to obtain the measured values of the non-planar “T” shaped cavity inner wall profile and to compare the theoretical values of the simulation. The results show that the theoretical values of the coupled multi-physical field simulation are close to the measured values and can simulate the actual electrolytic process more accurately, providing a technological reference for the electrolytic machining of complex-shaped cavities.