Design and Research on Working Teeth of Separable-Tooth Cathode for Electrochemical Machining

In the electrochemical machining (ECM) of variable-pitch internal helical grooves, a conventional integral cathode is subject to a kinematic constraint: the working teeth are rigidly fixed to the cathode body and therefore cannot follow a helix angle that varies continuously along the axis, and the resulting angular mismatch widens the groove and degrades the lands. To address these critical issues, this paper proposes a novel separable-tooth cathode design. As the cathode feeds along the variable-pitch helical path, each toothed disk is independently rotated to the corresponding angle by a built-in micro-motor embedded within the cathode body. This adaptive rotation ensures that the envelope of the working teeth remains consistently aligned with the real-time helix angle, thereby enabling the precise forming of variable-pitch helical features. Furthermore, inspired by the biomimetic reduction mechanism, four groups of bionic surface structures with different geometric parameters are designed and fabricated on the working teeth. Numerical simulations are conducted using COMSOL Multiphysics to investigate the correlations among the bionic structural parameters, electrolyte flow velocity, turbulent characteristics, and wall shear rate. The results indicate that the optimized bionic morphology with a spacing s = 0.2 mm and a height h = 0.05 mm significantly reduces the near-wall frictional resistance and effectively stabilizes the flow field distribution in the inter-electrode gap. Finally, systematic ECM verification experiments are performed using the proposed split-type bionic cathode. A metrological analysis of the sectioned workpiece reveals that the machined inner hole achieves a surface roughness of Sₐ1.6 μm, a roundness error of 0.02 mm, and a dimensional consistency within 0.02 mm. The experimental results demonstrate that the developed separable-tooth cathode satisfies the stringent design specifications, simultaneously guaranteeing a high machining accuracy and efficient material removal in the precision ECM of complex helical components.