| 摘要 |
PURPOSE:To make fixation of a tip by simple and uncostly method, by furnishing a hole at a spark discharge part of at least one of the electrodes, and fixing the tip in this hole in mechanically contacting state through pressurization and hot deformation. CONSTITUTION:Metal tips 3a, 3b with higher resistance against wear because of sparks than the mother metal are fixed to the spark discharge opposing parts of a center electrode 1 and a grounding electrode 2. Here the grounding electrode 2 is provided with a through hole 4, wherein the two surfaces 4a, 4b are greater and which consists of a three-step construction with smaller central part 4c. The tip 3b to be inserted in said through hole 4 is formed convex and located by major dia. part 4a by inserting from the spark part side. Thereafter current is supplied to the tips 3bb in pressurized condition, and the tip 3b is hot deformed into a specified configuration to be fixed to the grounding electrode 2. Accordingly the tip 3b and grounding electrode 2 are in mechanical contact simply, which should prevent generation of thermal stress at the interface between the two.
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