Abstract: To regulate the flushing liquid medium in the cutting zone of a TW electroerosion apparatus an elongate element is introduced into the cutting slot formed behind the advancing wire electrode and is maintained immediately behind the wire electrode and in parallel therewith, and thus dams the flushing medium in the space between the wire electrode and the element while serving to hold the wire electrode against deflecting rearwards. The elongate element is advantageously a tube having one or more apertures formed in a lateral wall thereof juxtaposed with the wire electrode, through which apertures the cutting liquid medium is discharged into the cutting zone and/or the flushing liquid medium in the cutting zone is sucked to assure an equalized distribution in the rate of flow in the cutting zone across the thickness of the workpiece. During a course of the cutting operation, the elongate element may be axially moved or reciprocated, or laterally oscillated.

Abstract: In a generic-electrode NC-EDM process, the electrode tool oriented in the direction of a z-axis is translationally retracted, from a position of a defective gap condition on a prescribed two-dimensional feed path in an x-y plane, by a prescribed distance in a prescribed direction which is transverse generally to all of the x-y, y-z and z-x planes so that the electrode end portion with a generic form is removed from the machined surfaces adjacent the machining gap of the defective condition. This retraction displacement may be performed under numerical control by displacing the electrode tool translationally by a first predetermined distance in an x-y plane and orthogonally to a portion of the feed path which is immediately prior to that position and simultaneously retracting the electrode axially in the direction of the z-axis by a second predetermined distance.

Abstract: A numerical-control (NC) method and system for machining a desired three-dimensional contour in a workpiece with an axial tool, e.g. a rotary milling cutter or electroerosion electrode, formed at its axial end with an active machining surface which is spherical about a center intersected by the axis of the tool. According to the invention, numerical coordinate values for the positions of this center of the tool to be displaced relative to the workpiece need not to be preprogrammed and stored on a record medium.

Abstract: An electrode positioning method and apparatus for NC-EDM wherein a tool electrode and a workpiece are relatively displaced under commands of an NC unit while EDM stock removal of the workpiece is advanced by developing effective electrical discharges between the tool electrode and the workpiece. The method comprises counting the effective electrical discharges, deriving a corrective amount of displacement from a prescribed amount of electrode wear per single effective discharge, the effective machining area of the tool electrode and the counted number of the electrical discharges. The corrective amount is used to correct the commanded relative displacement.

Abstract: An improved electrode feed system for use in effecting electrical machining between a working electrode and a workpiece electrode across a machining gap has a quick-response electrode retraction and reciprocation capability. The movable electrode is securely supported by an axially movable machining head into which a feed screw extends, the latter being driven by a servo motor responsive via a control circuit to the progress of machining in the gap. In the machining head, the feed screw is in mesh with a feed nut which is restrained from rotation for axially moving the head when the feed screw is rotated by the gap-responsive servo motor, thereby displacing the movable electrode as machining proceeds. The improved system includes a cylinder formed within the machining head and the feed nut is slidably received in the cylinder for axial movement relative thereto, the feed nut being constructed and arranged to define a pair of separate chambers in the cylinder.

Abstract: An apparatus for and method of electroerosively drilling a thin hole, e.g. of 1 mm diameter, of a high depth-to-diameter ratio, e.g. 5 or more, in a workpiece with a tubular electrode of corresponding high slenderness. The system utilizes a novel liquid-delivery mechanism which comprises a cylindrical reservoir communicating through an outlet opening thereof with the internal bore of the tubular electrode and hence with the machining gap and a plunger member for operative reception in the reservoir to be movable therein. Prior to a drilling operation, the reservoir is charged via a check valve with a given amount of the machining liquid from a source thereof. During the drilling operation, a motor advances the plunger member to move it within the chamber at a controlled rate. The charged machining liquid in the reservoir chamber is thus pressurized by the plunger member and discharged from and delivered through the internal bore of the tubular electrode into the machining gap at a regulated rate of flow.