Patent ID: 8933361
Filing Date: 2015-01-13
Classification: B23H

Abstract:
1. A microhole electric discharge machining apparatus that forms on a workpiece by a thin wire electrode a conical inverse-tapered hole having a larger hole diameter on a lower surface than a hole diameter on a workpiece upper surface, the microhole electric discharge machining apparatus comprising: an electrode holder that is configured to move in upward and downward directions on a hole-machining axis, that holds an upper part of the thin wire electrode, and that feeds a lower part of the thin wire electrode downward to stretch the lower part to the workpiece by rotating the thin wire electrode around the hole-machining axis; a first guide member that is arranged near the workpiece upper surface and is provided with a first guide hole through which the thin wire electrode is penetrated on the hole-machining axis; a second guide member that is arranged between the first guide member and the electrode holder and is provided with a second guide hole through which the thin wire electrode is penetrated at a position eccentric from the hole-machining axis; and a swivel driving unit that circularly swivels the second guide member around the hole-machining axis while maintaining a state where the hole-machining axis is an axis which extends in a same direction through an axis of the electrode holder, an axis of the second guide member, an axis of the first guide member, and an axis of the workpiece.