Cathode design and structure optimization of the ECM for special-shaped deep holes

Electrochemical machining (ECM) is adopted to solve the problem of machining special-shaped deep holes (SSDH) with a large depth-to-diameter ratio. Firstly, the cathode for ECM of SSDH was initially designed by analyzing the structural characteristics of the SSDH workpieces. Secondly, the gap flow field model was established, and the flow field simulation analysis was carried out with COMSOL for different machining gaps, the replenishment structures, and liquid-injected hole angles. The results indicate that when adopting the optimization scheme with a machining gap of 0.3 mm, the replenishment structure with a liquid-increasing hole and a 3° liquid-increasing slot, and a liquid-injected hole angle of 15° in the cathode structure, the flow characteristic of electrolyte in the machining gap has good uniformity, stable flow field, and no turbulence. This scheme solves the problem of low electrolyte velocity near the liquid-injected holes and uneven flow field at the liquid-increasing hole slots and achieves cathode structure optimization. Finally, the optimized cathode was used in the process test of ECM, and the results showed that the optimized cathode solved the problems of workpiece closing and hole wall flowlines, and the surface of the machined hole wall was flat and free of burrs; the dimensional accuracy met the production requirements of the workpieces. The simulation greatly improves the machining efficiency and quality of SSDH, which provides process technical reference for the machining of complex SSDH in mining, petroleum, natural gas equipment, and other fields.