Rule die set and apparatus for making same

Claim 1

A HYBRID APPARATUS FOR MAKING A PUNCH OF PREDETERMINED SHAPE BY ELECTRO-EROSION WHICH SAID APPARATUS IS SUBSEQUENTLY TRANSFORMABLE INTO A RULE DIE OF A SHAPE CONFORMING TO THE SHAPE OF THE PUNCH, SAID APPARATUS COMPRISING A BASE BLOCK, A RULE DIE SUPPORTED BY SAID BASE BLOCK AND PROJECTING THEREFROM AND DEFINING A HOLLOW ELECTRODE CONFIGURATION CONFORMING TO THE PUNCH TO BE MADE, SAID RULE DIE INCLUDING A FIRST SECTION AND A SECOND SECTION, SAID FIRST SECTION CONSTITUTING A HARDENABLE STEEL RULE DIE HAVING A PORTION CONTAINED WITHIN SAID BASE BLOCK FOR SUPPORT THEREBY AND ANOTHER PORTION PROTRUDING FROM THE BASE BLOCK FOR SERVICE AS A RULE DIE, THE EDGE OF SAID RULE DIE REMOTE FROM THE BASE BLOCK BEING THE WORKING EDGE OF SAID FIRST SECTION, MEANS BONDING SAID SECOND SECTION TO THE WORKING EDGE OF SAID FIRST SECTION, SAID SECOND SECTION BEING COMPOSED OF MATERIAL HAVING GOOD ELECTROEROSION PROPERTIES AND BEING A MATERIAL OF GOOD ELECTRICAL CONDUCTIVITY SELECTED FROM THE CLASS CONSISTING OF BRASS, COPPER, ALUMINUM AND SILVER, AND MEANS FOR SUPPLYING A PULSATING D.C. POTENTIAL TO SAID RULE DIE ELECTRODE, WHEREBY WHEN THE RULE DIE ELECTRODE IS APPROACHED IN A LIQUID DIELECTRIC MEDIUM TO A PUNCH PLATE HAVING A PULSATING D.C. POTENTIAL OF OPPOSITE POLARITY APPLIED THERETO THE RULE DIE ELECTRODE WILL BY ELECTRO-EROSION FORM A PUNCH CONFORMING TO THE SHAPE OF THE RULE DIE ELECTRODE AND WHEREBY THE SECOND SECTION THEREAFTER MAY BE REMOVED TO LEAVE A RULE DIE THAT MATCHES THE SHAPE OF THE THUS FORMED PUNCH.