Sodick Co., Ltd.

Daisuke Sadamitsu

Yuji Kaneko

Tatsuo Toyonaga

Tatsuo Kuloda

A power supply for an electric discharge machine which provides electrical power intermittently for discharge machining in a machining gap formed between an electrode and a work piece. The power supply comprises a direct current power source, a switching element connected between the direct current power source and the processing gap, a gate pulse generating circuit which generates a gate pulse signal for energizing the switching element and a protection network connected between the switching element and the gate pulse generating circuit. The protection network comprises a clock pulse generator which generates clock pulses, a counter which counts clock pulses while gate pulse signals are being received and generates an output having a predetermined level when the count reaches a predetermined value, a latch circuit which maintains the output of the predetermined level of the counter while the gate pulse signal is being received, and an AND gate which prevents gate pulse signal from being supplied to switching element while the latch circuit maintains the output of the counter as the predetermined level.

Electric discharge processing power supply having a protection network for the switching element

A power supply device for electric discharge machining apparatus, for supplying power to a gap formed between a workpiece and a tool electrode comprises a d.c. power source, a bridge circuit supplied with d.c. voltage from the d.c. power source and having switching transistors provided on each side, and a control circuit for controlling the on/off switching operation of switching transistors of the bridge circuit so that a.c. voltage pulses are applied from the bridge circuit to the gap. A first resistor limits current flowing when the workpiece is negatively poled and the tool electrode is positively poled. A second resistor having a larger value than the first resistor limits current flowing when the workpiece is positively poled and the tool electrode is negatively poled.

Power supply device for electric discharge machining apparatus

A wire-cut EDM method and apparatus for machining to a fine surface roughness of 1 .mu.m Rmax or less. Two power supplies and a electrode polarity switching system are used. A first high energy power source is used for initial profile cutting and may also be used for one or more later cuts while the machining pulse parameters, and feed rate and offset are adjusted for increasing less rough surface finishes. The wire electrode is held at negative machining potential. A second power supply and smaller offset values are used for later cuts to create lower values of surface roughness, while still maintaining the wire electrode at a negative machining potential. Finally, in order to create a fine finished surface (Rmax.ltoreq.1 .mu.m), the offset is further reduced and the wire electrode polarity is reversed.

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Kanagawa, Japan

Daisuke Sadamitsu