Electrolytic cavity sinking apparatus

Claim 1

IN AN ELECTROLYTIC CAVITY SINKING APPARATUS FOR FORMING CAVITIES IN AN ELECTRICALLY CONDUCTIVE AND ELECTROCHEMICALLY ERODIBLE WORKPIECE, THE COMBINTION COMPRISING, A HOLLOW ELECTRODE HAVING AN ELECTRICALLY CONDUCTIVE WORKING FACE, THE BORE OF SAID ELECTRODE FORMING A FIRST ELECTROLYTE PASSAGE, MEANS MOUNTING SAID ELECTRODE AND THE WORKPIECE FOR MOVEMENT RELATIVELY TOWARD EACH OTHER, ELECTRIC POWER MEANS CONNECTED TO SAID ELECTRODE WORKING FACE AND THE WORKPIECE TO PASS A LOW VOLTAGE, HIGH DENSITY DIRECT CURRENT BETWEEN SAID ELECTRODE WORKING FACE AND THE WORKPIECE IN A SENSE TO MAKE THE WORKPIECE ANODIC, A BUSHING HAVING A BORE THERETHROUGH THROUGH WHICH SAID ELECTRODE MOVABLY EXTENDS WITH THE OUTER SURFACE OF SAID ELECTRODE AND THE INNER SURFACE OF SAID BUSHING BORE DEFINING IN A SECOND ELECTROLYTE PASSAGE, MEANS SEALING SAID BUSING AGAINST THE ENTRY FACE OF THE WORKPIECE AT THAT END OF SAID BUSHING BORE FROM WHICH SAID ELECTRODE WORKING FACE PROJECTS, MEANS HOLDING SAID BUSHING AND SAID SEALING MEANS AGAINST THE ENTRY FACE OF THE WORKPIECE TO HOLD THEM RELATIVELY STATIONARY AS SAIDELECTRODE IS MOVED RELATIVELY INTO AND THROUGH SAID BUSHING DURING THE CAVITY SINKING OPERATION, AN ELECTROLYTE INLET TO ONE OF SAID ELECTROLYTE PASSAGES, MEANS CONNECTED TO SAID INLET FOR PUMPING AN ELECTROLYTE THROUGH BOTH SAID PASSAGES AND A WORK GAP BETWEEN SAID ELECTRODE WORKING FACE AND THE WORKPIECE UNDER SUPERATMOSPHERIC PRESSURE, AN ELECTROLYTE OUTLET FROM SAID OTHER PASSAGE, AND MEANS AT SAID OUTLET TO RESTRICT THE ELECTROLYTE FLOW THERETHROUGH, THEREBY TO PLACE A BACK PRESSURE ON THE ELECTROLYTE IN THE WORK GAP.