| 摘要 |
PROBLEM TO BE SOLVED: To effectively prevent the failure in fastening such that the vibration of shaft of an underhead shaft part often occurs when a clearance is larger than a fastening inlet, an underhead radius part of a bolt and the fastening inlet hole are interfered with each other when a female screw and the fastening inlet hole are displaced, and the radius part is dislocated by the vibration and the like after the passage of a certain period, and the bolt is loosened when the vibration of shaft is reduced, in fastening the bolt, and to provide the bolt of low cost. SOLUTION: A cylindrical part 3 of a diameter slightly smaller or larger than an upper diameter 21 of an underhead radius is mounted at a part just under the underhead radius part 2 of a head part 1 of the bolt, a hollow width part 4 approximately same as a screw flute diameter or slightly larger than the same is formed at a lower side of the cylindrical part 3, further an effective diameter shaft part 5 is formed, and further a fastening screw part 6 is formed. The cylindrical part 3 and the hollow width part 4 just under the underhead radius 2 are formed by drawing an upper part of the effective diameter shaft part 5 by a rolling drawing die 7, and the fastening screw part 6 is simultaneously formed by a rolling die 9, whereby the failure in fastening can be resolved at low cost. COPYRIGHT: (C)2004,JPO&NCIPI
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