Analysis of the shaping law of numerical controlled electrochemical contour evolution machining

Numerical Controlled Electrochemical Contour Evolution Machining (NC-ECCEM) is one of the most important development in Electrochemical Machining (ECM), the study on its shaping law is significant for improving the machining accuracy of workpiece profile. In this paper, the shaping law of machining grooves by use of a kind of inner-spraying cathode with triangle section was studied. First, the basic differential equations of shaping law in the case of cathode movement were established. Then, considering the structure of the cathode, the methods for calculating the bottom gap and the side gap in machining vertical grooves, inclined grooves and circular grooves were given respectively. Finally, the experiments of machining vertical grooves, inclined grooves and circular grooves were carried out. Experiments show that the calculated bottom gaps are better consistent with the actual values in machining process, and the calculated side gaps are bigger than actual values, but the change trend of calculated side gaps with machining process parameters is coincident with the actual side gap change trend. In order to estimate correctly the side gap, a method for modifying calculated side gaps was put forward. Through the experiments, a special shaping characteristic that the side gap is less than bottom gap in NC-ECCEM was found too.