| 摘要 |
The invention is an anti-loose lock nut which prevents a screw coupling between a bolt 12 and a nut 10 by a coil spring 11 which is mounted in the inner circumferential surface of the nut 10 from loosening, the anti-loose lock nut characterized in that: an extended diameter portion 50 whose inner diameter is wider than the thread 13 of the nut 10 and in the inside of which a spiral groove is not formed, is formed in the inner circumferential surface of the nut 10; an insertion groove 52 into which a bent end portion 51 is fit-coupled is formed in the end of the extended diameter portion 50, in which the end of the coil spring 11 is outwardly bent to form the bent end portion 51; a semicircular curved portion 53 is protrudingly formed in the inner surface of the coil spring 11, and the outer surface of the coil spring 11 is formed of a flat cross-sectional plane; clearance spaces 54 and 55 which are respectively wider by one pitch than a thread pitch P of the bolt 12, are formed in the lengthy width of the extended diameter portion 50 and the insertion groove 52, after the coil spring 11 has been mounted.
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