Electric discharge machining apparatus

In an electric discharge machining apparatus, the combination comprising:

• a tool housing including an electrode guide, said electrode guide containing an orifice;
• an electrode having a tip end for juxtaposition to a workpiece to establish a spark discharge gap;
• said electrode being held in said tool housing and extending through said electrode guide and said electrode guide orifice wherein said tip end protrudes through said guide orifice, leaving a reserved portion of said electrode located behind said guide orifice within said tool housing;
• spark position monitoring means for monitoring the spatial position of sparks produced off said tip end of said electrode;
• and electrode positioning means for incrementally advancing reserved portions of said electrode through said guide orifice, responsive to said spark position monitoring means.

An electric discharge machining apparatus comprising:

• an electrode;
• an electrode guide containing a passage for said electrode;
• said electrode being movably mounted within said guide to permit positioning of said electrode relative to the end of said guide;
• positioning means for positioning said electrode with a distal end extending beyond said end of said guide;
• first and second light pipes;
• said first light pipe having an input end focused at a predetermined location forward of said distal end of said electrode;
• said second light pipe having an input end focused at a second predetermined location behind said distal end of said electrode;
• optical detector means for monitoring illumination emanating from the output end of each of said first and second light pipes to monitor light originating with said sparks at each of two locations;
• and
• control means for actuating said positioning means to incrementally advance the forward position of said distal end of said electrode responsive to a departure of the relationship between the illumination emanating from the output end of said first light pipe and that emanating from the output end of said second light pipe from said predetermined relationship.

A NC controlled electric discharge machining apparatus comprising:

• an NC controller;
• a plurality of EDM cutting tools;
• a cradle for holding a single EDM cutting tool;
• and
• robotic means, controlled by said NC controller, for retrieving one of said plurality of EDM cutting tools selected by said NC controller and installing said retrieved one into said cradle;
• each of said EDM cutting tools including electrical circuitry and an electrical socket coupled to said electrical circuitry, said electrical socket including at least a pair of electrical contacts supported in electrically insulated relationship to the associated cutting tool;
• said cradle including an electrical socket for interconnection to a mating electrical socket of an EDM cutting tool that is installed in said cradle to connect there through said electrical circuitry of said installed EDM cutting tool;
• and
• an electrical cable coupled to said cradle electrical socket for coupling to said NC controller for permitting said NC controller to access the electrical circuitry of the cutting tool installed in said cradle.

An electric discharge machining apparatus, comprising:

• an electrode guide having first and second ends, said first end including an electrode orifice;
• a discharge electrode having a distal end;
• said discharge electrode being laterally supported by said electrode guide, extending through said electrode guide and being moveable relative thereto through said first and second ends;
• motor means for moving said discharge electrode relative to said electrode guide to position said distal end a predetermined distance from said electrode orifice;
• and
• position monitoring means for automatically initiating operation of said motor means when said distal end is worn back a predetermined increment from said predetermined distance due to wear during machining to immediately automatically restore said distal end of said discharge electrode during machining to said predetermined distance.

An electric discharge machining apparatus, comprising:

• a tool guide;
• a discharge electrode, said discharge electrode comprising an elongate wide metal ribbon, said wide metal ribbon containing a series of notches within and spaced evenly along each of said ribbon's right and left side edges;
• motor means for incrementally advancing said discharge electrode through said tool guide;
• forming means, located within said tool guide, for shaping said ribbon from a straight cross section into a curved cross section responsive to said ribbon's advance there through and for bending said ribbon into a circular curve as said ribbon exits said tool holder to define an exposed electrode portion formed into a circular arc, whereby said circular curve increases in arc as said ribbon is advanced out said tool holder to increase the length of said exposed electrode portion.