Abstract: A lock nut capable of improving a fastening force of a fastening nut and the lock nut is provided. The lock nut includes a body having a threaded throughhole and a groove formed at a circumferential edge thereof. A plurality of projections are formed in the groove and each includes an outer side face directed toward a center of the body from a border between a seat surface and the groove. An inner side face serves as an extension of an inner face of the threaded throughhole. A depth of the groove is such that if the projections are crushed when the lock nut is fastened against a bolt, they do not enter a space between a seat surface on the side of the body of the fastening nut and the seat surface of the lock nut body.

Abstract: A lock nut capable of improving a fastening force of a fastening nut and the lock nut is provided. The lock nut 1 preventing the fastening nut 7 fastened against a bolt 6 from being loosened comprises: a nut body 2 wherein a threaded hole 4 is formed inside and a groove 30 is formed at a circumferential edge of the threaded hole 4 of one seat surface 3; and a plurality of projections 5 being formed in the groove 30 of the nut body 2 and made from the same material as that of the nut body 2. The projection 5 comprises: an outer side face on the opposite side of the threaded hole 4 directed toward a center of the nut body 2 from the border between the seat surface 3 and the groove 30 of the nut body 2; and an inner side face 32 on the side of the threaded hole 4 so made as to be an extension of an inner face of the threaded hole 4 of the nut body 2.

Abstract: This invention relates to a lock nut in which, when a double nut is fastened against a bolt, projections at the lock nut are deformed and crushed to be applied around the threaded part of the bolt and a frictional force is increased to improve an effect of looseness-prevention. A seat surface of a circumferential edge of the threaded hole 4 of the nut 2 is formed with a plurality of projections 5, 5, 5, the nut 2 is fastened against the fastening nut 7 already fastened against the bolt 6 acting as a member M to be fastened with its projections 5 being faced to the nut, the projections 5 deformed between seat surfaces 3, 8 of both nuts 2, 7 are applied around the threaded part between the threaded hole 4 of the nut 2 and the threaded part 9 of the bolt 6 so as to enable both nuts 2, 7 to be prevented from being loosened.