Spark machining electrode surface reshaping and realignment - using workpiece to control preferential erosion of electrode in reversed spark regime or abbreviated discharge time

摘要

Before the workpiece is machined by several electrodes (A,B,C) in a single unit, the sparking regime is modified for preferential erosion of the electrodes with the aid of the workpiece itself. This may be achieved either by reversing the spark polarity or by shortening the discharge time, or both. The reversal is triggered when current transformers (8a-8c) monitoring the electrodes individually indicate no erosion of one or more of them, and/or when a calculator (25) shows that the total sparking surface area amounts to less than a given value which is a function of the total cross-section of the electrodes. ADVANTAGE - Electrode surface can be rectified and/or aligned without use of any special mechanical device or machining.