| 摘要 |
PROBLEM TO BE SOLVED: To provide screws having a locking mechanism with reliable stop locking property. SOLUTION: A plurality of projections are provided on both face and back sides of a spring washer, or either side thereof. The projections on one side are engaging projections engaged with locking projections of the screws, and the projections on the other side are biting projections capable of biting a tightening work to be tightened by the screws. The screws having the locking mechanism have recesses capable of accommodating a flat washer or the spring washer with or without projections on the back side of the screws. A locking projection is provided in the recess. The locking projection in the recess has a ride-over inclined surface which is rotatable over the tightening inclined surface of the engagement projections of the flat washer or spring washer having the projections in the recess, and a loosening regulation part which is locked to a loosening regulation surface of the engagement projection for regulating the rotation of the screws in the loosening direction is provided opposite to the ride- over inclined surface. A locking projection is provided on a back side of an outer circumferential wall of the recess. The spring washer is built in the back side of a bolt and a nut.
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