Real-Time Observation of Multiphysics Coupling Fields in the Electrochemical Trepanning of Vibrating Cathodes

Abstract

Electrochemical trepanning (ECTr) with a vibrating cathode is widely used to manufacture blisk as a typical electrochemical machining (ECM) technology. The inter-electrode gap (IEG) distribution is very important for the accuracy of ECTr. An ECTr processing system with an observable IEG is designed to study the effects of vibrating cathodes on the IEG distribution. A multiphysics coupled field model for a vibrating cathode ECTr with electric, gas-liquid two-phase flow, and temperature fields is developed based on this system. The distribution laws of the current density, bubble volume fraction, and temperature in the IEG are obtained via multiphysics simulations of the coupled fields. Compared to conventional ECTr, the current density within the IEG increases, the end-gap current density percentage grows by 3%, and the electrolyte renewal within the IEG is promoted. An experimental study of a vibrating cathode ECTr verifies the validity of the simulations. A distinct white bubble layer appeared at the transition corner of the end gap near the cathode side. The bubbles were gradually increasing as the cathode was fed to the workpiece during a cycle. No obvious white bubble layer is seen at the side gap. The observations verify the multiphysics field simulations to study the gas volume fraction distribution law. The experimental results show that the vibrating cathode improves the integrity of the blade profile and surface quality. The rounded corners at the top and root of the workpiece are reduced by 0.33 and 0.59 mm, respectively, and the blade width improves by 0.62 mm. The surface roughness of the sidewalls reduces from Ra 1.385 μm to Ra 0.912 μm and the surface roughness of the runner surface is reduced from 4.925 to 2.187 μm.