Current supply including high frequency component for spark erosion machining apparatus

Claim 1

IN AN APPARATUS FOR SPARK EROSION MACHINING OPERATIONS ON AN ELECTRICALLY CONDUCTIVE WORKPIECE, A MACHINING ELECTRODE A TERMINAL SPACED FROM SAID ELECTRODE TO DEFINE A SPARK DISCHARGE GAP THEREBETWEEN, MEANS FOR POSITIONING SAID ELECTRODE IN PREDETERMINED SPACED RELATIONSHIP WITH SAID TERMINAL TO MAINTAIN SAID SPARK DISCHARGE GAP, A SINGULAR PULSATING HIGH FREQUENCY DIRECT CURRENT SOURCE AND CIRCUIT MEANS CONNECTING SAID ELECTRODE AND SAID TERMINAL SERIALLY THEREWITH TO FORM A MACHINING CIRCUIT TO SUPPLY A PULSATING CHARGING CURRENT ACROSS SAID GAP, THE FREQUENCY OF SAID PULSATING CHARGING CURRENT RANGING FROM 200 TO 20,000 PULSES PER SECOND, SAID CIRCUIT MEANS INCLUDING MEANS FOR SUPPLYING PULSATIONS OF SAID CHARGING CURRENT HAVING A WAVE-FORM SUBSTANTIALLY THE SHAPE OF ONE-HALF OF A SINE WAVE AND RISING FROM SUBSTANTIALLY ZERO TO A PEAK AND DROPPING TO SUBSTANTIALLY ZERO WITH SAID PULSATIONS RECURRING CONTINUOUSLY WITHOUT ANY TIME LAPSE THEREBETWEEN, SAID LAST-NAMED MEANS INCLUDING RESISTANCE-CAPACITANCE RELAXATION CIRCUIT MEANS CONNECTED BETWEEN SAID SOURCE AND SAID ELECTRODE-TERMINAL GAP AND INCLUDING A RESISTANCE IN SERIES WITH SAID SOURCE AND SAID ELECTRODE AND A CONDENSER ACROSS SAID GAP AND ACROSS SAID SOURCE AND SAID RESISTANCE, FOR DISCHARGING AT A FREQUENCY GREATER THAN THE FREQUENCY OF PULSATIONS OF SAID CHARGING CURRENT ACROSS SAID GAP.