Patent ID: 7528340
Filing Date: 2009-05-05
Classification: B23H

Abstract:
1. An electric discharge machining apparatus for machining a workpiece by electric discharge using a tool electrode, comprising: a power supply for applying a voltage to a work gap formed between the tool electrode and the workpiece to cause electric discharge; a motor that moves the tool electrode relative to the workpiece; an electric discharge counter for counting a number of electric discharge occurrences within a first specified period and generating a first count; a gap controller for multiplying the first count by a first gain to generate position command or speed command for driving the motor; a gap voltage detector for detecting a gap voltage; an inversion counter for counting a number of inversions of the gap voltage upwards or downwards within a second specified period and generating a second count; and an electric discharge discriminator for discriminating the occurrence of electric discharge when the second count reaches a set value.