Improvement on profile accuracy of convex structure during counter-rotating electrochemical machining by periodically changing electrolyte flow direction

Abstract

Counter-rotating electrochemical machining (CRECM) is an innovative electrochemical machining (ECM) method, which can be used to machine thin-walled casings. However, due to the complex electrode movement and the special flow field structure, there are some challenges in the uniformity control of the profile accuracy of convex structure during CRECM. In this paper, to improve machining accuracy of convex structures, a strategy of periodically changing electrolyte flow direction is proposed. A multi-physical field simulation model is established to reveal the CRECM mechanism. The simulation results show that the one-sided electrolyte supply causes the uneven distribution of flow rates, bubbles and temperature on both sides of the convex structure, mainly because the convex structure forces the electrolyte flow path to bend and increase electrolyte flow resistance. The conductivity near the inlet is higher than that at the outlet, which causes the profile of the convex structure to be asymmetric. However, this problem can be effectively solved by changing electrolyte flow direction periodically, because the average conductivity at the symmetrical positions on both sides of convex structure is consistent, the average material removal rate is the same, and the manufactured convex structure is axisymmetric. CRECM experiments are carried out, and the processed convex structure has good symmetry, and the deviation is <0.05 mm. This fully demonstrates that periodically changing electrolyte flow direction can significantly improve the forming accuracy of the convex structure.