초록 ▼

An electrical discharge detector (30) which detects electrical discharge generated at a machining gap; a pulse generator (41) which generates a pulse signal which stops after the commencement of electrical discharge in response to the electrical discharge detector; first switching circuits (22A, 22D

An electrical discharge detector (30) which detects electrical discharge generated at a machining gap; a pulse generator (41) which generates a pulse signal which stops after the commencement of electrical discharge in response to the electrical discharge detector; first switching circuits (22A, 22D) which apply voltage pulses of one polarity in response to the pulse signal; second switching circuits (22B, 22C), which apply voltage pulses of the opposite polarity to the machining gap in response to the pulse signal; a flip-flop (46) which retains one of two states; a gate circuit (42, 43) which supplies a pulse signal to the first switching circuit when one state is retained in the flip-flop, and supplies a pulse signal to the second switching circuit when the other state is retained in the flip-flop; circuits (CK, 48, 49) which supply a high frequency pulse to the flip-flop for the duration of the pulse signal; a circuit (44) which supplies a single pulse to the flip-flop each time the pulse signal is inactive; and a machining current supply circuit (10), which supplies a machining current to the machining gap after the commencement of electrical discharge.

대표청구항 ▼

[ We claim:] [1.] In an electrical discharge machining apparatus for machining a workpiece by generating an electrical discharge in a machining gap formed between a workpiece and a tool electrode, the electrical discharge machining apparatus comprises:an electrical discharge detection device for det

[ We claim:] [1.] In an electrical discharge machining apparatus for machining a workpiece by generating an electrical discharge in a machining gap formed between a workpiece and a tool electrode, the electrical discharge machining apparatus comprises:an electrical discharge detection device for detecting electrical discharges occurring at the machining gap;a pulse generator for generating a pulse signal and responsive to the electrical discharge detector to interrupt said pulse signal after electrical discharge commences;a first voltage pulse application means responsive to the pulse signal for applying a voltage pulse of one polarity to the machining gap;a second voltage pulse application means responsive to the pulse signal for applying a voltage pulse of the opposite polarity to the machining gap;a state-retaining means for retaining either or a first or a second state; ate means for supplying a pulse signal to said first voltage pulse application means when the first state is retained in said state retaining means, and for supplying a pulse signal to a second voltage pulse application means when the second state is retained in said state retaining means;a means for changing the state in said state retaining means while the pulse signal is ongoing;a means for changing the state retained in said state retaining means from one to the other state each time the pulse signal is interrupted; anda machining current supply, responsive to the electrical discharge detector, for supplying machining current to the machining gap after electrical discharge commences.