Patent ID: 6933456

Claim:
A small hole electrical discharge machining apparatus comprising: an electrode holder that holds an upper part of an electrode; an electrode guider that guides a lower part of the electrode; a jet nozzle that injects a water jet to the electrode holder; and a fluid channel that supplies a gas to an electrode guide, wherein the electrode guider comprises: an electrode guide sleeve having the electrode guide at its lower end, the electrode guide sleeve extending into an electrode holding member so that the electrode guide protrudes from a lower end of the electrode holding member; an inner sleeve provided within the electrode guide sleeve and which is coaxial with the electrode guide; a spacer which holds, in the interior of the electrode holding member, an upper electrode guide to be coaxial with the electrode guide; a fluid channel provided in the spacer and guiding a gas supplied from a gas supply port provided in the electrode holding member into an electrode guiding hole of the inner sleeve; and a fixing member provided above the spacer and having a funnel portion for guiding the water jet into a through hole of the upper electrode guide, and wherein the electrode is guided with the water jet toward a workpiece, and small hole electrical discharge machining is performed while the gas is released from the electrode guide into a working liquid via the fluid channel.