High repetition rate spark machining apparatus

Claim 1

A SPARK-MACHINING APPARATUS FOR DISLODGING PARTICLES FROM A CONDUCTIVE WORKPIECE BY A SERIES OF TIMESPACED SPARK-OVER DISCHARGES THROUGH AN IONIZABLE DIELECTRIC FLUID-FILLED NORMAL SPARK GAP SPACING MAINTAINED BETWEEN THE WORKPIECE AND AN ELECTRODE TOOL, COMPRISING AN OSCILLATOR HAVING A GIVEN FREQUENCY FOR PRODUCING A SIGNAL OF A GIVEN HIGH FREQUENCY AND AMPLITUDE WITH RESPECT TO GROUND, A STORAGE CAPACITOR, AN ELECTRIC DISCHARGE DEVICE RECTIFIER HAVING AN ANODE AND A HEATED CATHODE, MEANS FOR HEATING THE CATHODE INCLUDING A TRANSFORMER WITH A SECONDARY WINDING CONNECTED FOR HEATING THE RECTIFIER CATHODE AND A PRIMARY WINDING CONNECTED TO AN ALTERNATING VOLTAGE SOURCE REFERENCED TO GROUND, SAID TRANSFORMER HAVING DISTRIBUTED CAPACITANCE BETWEEN ITS PRIMARY AND SECONDARY WINDING SO AS TO DEFINE A GIVEN FIRST CAPACITANCE BETWEEN THE RECTIFIER CATHODE AND GROUND CHARGEABLE DURING ALTERNATE HALF CYCLES OF SAID OSCILLATOR SIGNAL, CIRCUIT MEANS CONNECTING SAID ANODE TO ONE TERMINAL OF SAID OSCILLATOR OUTPUT TERMINAL WHEREBY SAID CAPACITANCE IS CHARGED DURING ALTERNATE HALF CYCLES, A SECOND CAPACITANCE HAVING THE SAME ORDER OF MAGNITUDE AS THE FIRST CAPACITANCE, AND DISCHARGE CIRCUIT MEANS CONNECTING THE FIRST AND SECOND CAPACITANCES IN SERIES ACROSS THE SPARK GAP FOR DISCHARGE THERETHROUGH WHENEVER SPARK-OVER OCCURS.