Generic electrode EDM method and apparatus, and assembly for maintaining chip concentration in the gap at an enhanced level

An EDM apparatus for machining a desired three-dimensional pattern in a conductive workpiece, the apparatus comprising:

• at least one tool electrode having a machining surface contour which has a configuration generally independent of the shape of said desired pattern and adapted to be axially juxtaposed with the workpiece to position said machining surface contour in a spaced juxtaposition therewith across an EDM gap supplied with an EDM liquid;
• a bored block member having a central bore and a frontal surface region surrounding said central bore, both adapted to be disposed in the proximity of said workpiece, so as to locate at least a portion of said tool electrode proximate to said machining surface contour in said bore and to position said frontal surface region spaced away from said workpiece with a distance not less than said EDM gap, said member being so constructed as to establish an electrical insulation both from said tool electrode and said workpiece;
• power supply means for producing a succession of electrical discharges across the EDM gap to electroerosively remove stock from a localized portion of said workpiece juxtaposed with said machining surface contour while permitting machining products produced by the electrical discharges to be accumulated in the EDM gap for removal thereof;
• means for holding said block member whereby said frontal surface impedes the removal of the machining products from the EDM gap so that the concentration of the machining products in the machining liquid at said EDM gap is maintained in excess of a predetermined level to stabilize said electrical discharges;
• and
• feed means for effecting a multi-axial machining feed displacement between the tool electrode and the workpiece along a predetermined three-dimensional path defined by three coordinate axes including a pair of coordinate axes defining a plane substantially orthogonal to the longitudinal axis of said tool electrode and a coordinate axis substantially orthogonal to said plane while maintaining said EDM gap substantially constant, thereby three-dimensionally machining said workpiece at least in part by said stabilized electrical discharges to form the desired pattern in the workpiece.

For use with an EDM apparatus for machining a three-dimensional pattern in an electrically conductive workpiece, having at least one tool electrode which has a machining surface contour having a configuration generally independent of the shape of the desired pattern and adapted to be axially juxtaposed with the workpiece to position the machining surface contour in a spaced juxtaposition therewith across an EDM gap supplied with an EDM liquid, power supply means for producing a succession of electrical discharges across the EDM gap to electroerosively remove stock from a localized portion of the workpiece juxtaposed with the machining surface contour while permitting machining products produced by the electrical discharges to be accumulated in the EDM gap for removal therefrom, and feed means for effecting a multi-axial feed displacement between the tool electrode and the workpiece along a predetermined three-dimensional path defined by three coordinate axes including a pair of coordinate axes defining a plane substantially orthogonal to the longitudinal axis of the tool electrode and a coordinate axis substantially orthogonal to said plane while maintaining the EDM gap substantially constant, thereby three-dimensionally machining the workpiece at least in part by the electrical discharges to form the desired pattern in the workpiece, an assembly for maintaining the concentration of the machining products in the EDM liquid at the EDM gap in excess of a predetermined level, the assembly comprising:

• a bored block member having a central bore and a frontal surface region surrounding said central bore, both adapted to be disposed in the proximity of said workpiece so as to locate at least a portion of said tool electrode proximate to said machining surface contour in said bore and to position said frontal surface region spacedly away from the workpiece with a distance not less than said EDM gap, said member being so constructed as to establish an electrical insulation both from said tool electrode and said workpiece, and
• means for holding said block member whereby said frontal surface region mechanically impedes the removal of the machining products from said EDM gap to stabilize said electrical discharges in the three-dimensional machining of the desired pattern in the workpiece.