Patent ID: 7964817

Claim:
An electrical discharge machining apparatus for a wire electrode and having a guide system for the wire electrode for machining bores in a workpiece, the guide system comprising: a guide body for positioning near the workpiece for stabilizing a first portion of the electrode, defining a guide nose at the end of the guide body closest to the workpiece from which a second portion of the electrode extends; the electrode forming a working tip at the end of the second portion of the electrode in communication with the workpiece; feeder means for advancing the electrode within the guide body during the machining; and wobbling means for moving the guide body relative to the longitudinal axis of a desired workpiece bore during the machining such that the working tip of the electrode traces a continuous closed curve across a plane perpendicular to the longitudinal axis, and such that as the electrode advances into the workpiece as the electrode sweeps out a bore having planar cross sections with a shape substantially similar to the closed curve shape, where the wobbling means comprises: a machine frame; a first guide support portion to which the guide body is secured having a first hinge axis substantially perpendicular to the longitudinal axis of the desired workpiece bore; a second guide support portion attached to the first guide support portion and attached to the machine frame, having a second hinge axis which is substantially perpendicular to the first hinge axis and substantially perpendicular to the longitudinal axis of the desired workpiece bore; hinging means for partially rotating the first guide support portion about the first hinge axis and for partially rotating the second guide support portion about the second hinge axis. a first guide support portion to which the guide body is secured having a first hinge axis substantially perpendicular to the longitudinal axis of the desired workpiece bore;