| 摘要 |
PROBLEM TO BE SOLVED: To make narrower the interval between a nozzle and an electrode in order to more reduce the outside diameter of a plasma torch. SOLUTION: The electrode (30) has an electrode body (36) made of copper and the rear part (35B) of the electrode body (36) is thicker than the front part (36A). The outer peripheral surface of the rear part (36B) of the electrode body (36) is covered with a thin cylindrical insulator film (42). The insulator film (42) which is a tube made of resin which is externally fitted to the electrode body (36), or a thin ceramic film so on which are made by thermal spray, vapor deposition or the like, is formed integrally with the electrode body (36). Even when the interval between the electrode body (36) and the nozzle (32) is narrow, when a pilot arc is fired, electrical discharge between the rear part (36B) of the electrode body (36) and the nozzle (32) is prevented with the insulator film (42) and the pilot arc is surely generated in the front end part of the electrode body (36). COPYRIGHT: (C)2007,JPO&INPIT
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