| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug for internal combustion engines with high binding strength between a spark-exhaustion resistant electrode-material and an outside electrode, and to realize its manufacturing method. SOLUTION: Under the condition before forming a spark discharging gap by bending an outside electrode 16, a tip-shaped, spark-exhaustion resistant electrode-material 18 is fitted on the clamp face 16b of the outside electrode 16, the border part between the spark-exhaustion resistant electrode-material 18 and the outside electrode 16 is irradiated with pulse YAG laser L at an incidence angleθ, and the spark-exhaustion resistant electrode-material 18 is welded with the outside electrode 16. Here, in the case the distance from the intersection point 11d between the installation surface 16b and the edge face 11b of a main fittings 11 to the farthest intersection point 11e of the edge face 11b is designated as X, and the distance from the intersection point 11d to the intersection point (nearest point) 18a of the spark-exhaustion resistant electrode-material 18 is designated as Y, by setting up an incidence angleθsatisfying the conditions of (X/Y)<tanθandθ<=90 deg. the whole circumference of the border part can be welded.
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