| 摘要 |
PROBLEM TO BE SOLVED: To provide a bolt having excellent mass productivity and capable of achieving the excellent safety and reliability which can not be obtained by a conventional screw fastener by providing the considerably improved fatigue strength together with the excellent loose prevention function and excellent fastening force to be hardly loosened even under a cyclic load (vibration). SOLUTION: The bolt includes a male screw part of pitch p<SB>b</SB>formed at least on a fore end side of a bolt shaft section, a tapered section in which a part of a top part of a thread on a bolt head side or on a bolt cylindrical section side of the male screw part is removed, and the outside diameter of the thread is reduced toward the bolt head side or the bolt cylindrical section side, and an incomplete screw removed section which is expanded in a smoothly arc-shaped manner toward the bolt head side or the bolt cylindrical section side from a minimum diameter part of the tapered section. The pitch p<SB>b</SB>of the male screw part and the pitch p<SB>n</SB>of a female screw to be screwed to and fastened by the male screw part satisfy the inequalities 0.003≤(p<SB>n</SB>-p<SB>b</SB>)/p<SB>b</SB>≤0.05. COPYRIGHT: (C)2009,JPO&INPIT
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