| 摘要 |
PROBLEM TO BE SOLVED: To restrain generation of a burr in vibration composite work for imparting an ultrasonic wave to a rotary drill for boring a nozzle hole in a tip part of a fuel injection valve. SOLUTION: A hardened layer is formed on a surface of a metallic member on a surface of a fuel injection valve tip part 3 composed of case hardened steel in the tip part of the fuel injection valve. The hardening layer 4 having Vickers hardness of 450 or more and having the depth of 0.01 mm or more is formed by carburization quenching. Then, a hole is bored by using the drill 2. COPYRIGHT: (C)2004,JPO
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