Cathode tool design and experimental study on electrochemical trepanning of blades

Electrochemical trepanning process is known as an economical approach for manufacturing ruled surface blade made of hard-to-cut material. The machining accuracy of blade fabricated by electrochemical trepanning relies on the designed profile of cathode tool and distribution of machining gap. When trepanning blades, the electric field often concentrates at the leading and trailing edges, because the curvature radius of leading and trailing edges are much smaller than that at concave and convex parts. The local concentration of electric field will result in large difference of machining gap distribution between the blade profile and cathode profile. So, designed cathode profile cannot be obtained by simply offsetting the desired blade profile by a certain distance. In this paper, an iterative correction method is introduced to design the profile of trepanning cathode. In this method, the cathode and blade profile are divided into a series of nodes, gap between each blade node and its corresponding cathode node is differently designed based on the electric field intensity. Experiment results show that the machining accuracy of blade is improved hugely by cathode after iterative correction design.