It is made possible to give prevailing torque to an adjustment bolt in a simple manner without troublesome adjustment work. An anti-loosening adjustment bolt assembly includes: a cylindrical pipe (6) adapted to be fitted on the screw shaft (2a) of the adjustment bolt (2); and a nut (7) having a threaded hole for allowing the screw shaft (2a) to be threadably mounted thereon; the bottom of the nut (7) includes a recess (7a) adapted to allow the upper end of the cylindrical pipe (6) to be fitted therein; the inner peripheral surface of the recess (7a) is a taper surface decreasing in diameter toward the interior; and the axis of the taper surface is slightly eccentric from the axis of the threaded hole such that, when the nut (7), threadably secured to the screw shaft (2a), is screwed toward the cylindrical pipe (6), a circumferential portion of the eccentric taper surface comes into pressure-contact with the upper end of the cylindrical pipe (6) and the axis (Q) of the threaded hole of the nut (7) is eccentric and/or inclined from the axis (O) of the screw shaft (2a) to generate prevailing torque depending on the amount of tightening of the nut (7) on the adjustment bolt (2).

There is provided an implant having a slack prevention function by an eccentric fitting structure. An engaging shaft 53, which is decentered with a screw shaft 52, is provided at the end of an abutment screw 5, and is engaged with an engaging hole 45 provided in the bottom of a screw hole 44, into which an abutment screw 5 is screwed, and thus, the screw shaft 52 is inclined to and eccentric from the screw hole 44. Thereby, the screw shaft 52 comes to be strongly pressed partially in a circumferential direction toward the screw hole 44, so that internal stress in the horizontal direction is accumulated on the screw shaft 52. The screw 5 is threaded with maintaining prevailing torque caused by the internal stress, which enables the screw 5 to be fastened to the right position.

An object of the present invention is to provide an anti-loosening device that exhibits its anti-loosening effect by means of an eccentric fit between a protrusion 12 of a nut 10 and a recess 22 in a nut 20, wherein the inclination of the nut 20 relative to the nut 10 when they have been tightened is minimized. The outer peripheral surface of the protrusion 12 and the inner peripheral surface of the recess 22 are constructed in such a manner that, with the nuts screwed to a threaded shaft S and an eccentric fit established between the protrusion 12 of the nut 10 and the recess 22 in the nut 20, the tapered outer peripheral surface portion 12a of the protrusion 12 interferes with the tapered inner peripheral surface portion 22a of the recess 22 along part of the circumference while a gap is formed between the distal-end outer peripheral surface portion 12b of the protrusion 12 and the closer-to-bottom inner peripheral surface portion 22b of the recess 22 along the entire circumference.

A threaded fastening assembly includes a nut body and a screw body. The internal thread of the nut body includes a nut thread crest and a nut thread root. The external thread of the screw body includes a screw thread crest, a screw thread root, a fourth side wall located on one side of the screw thread crest, and a fifth side wall located on the other side of the screw thread crest. A locking notch located on one side of the nut thread crest is arranged on the internal thread. The locking notch includes a first side wall and a bottom wall. One end of the first side wall is connected to the nut thread crest, and the other end of the first side wall is connected to one end of the bottom wall. The bottom wall is spirally distributed around the axis of the nut body.

Disclosed is a ring type locknut, where a frustum-shaped internal thread concave cavity is arranged on a nut, inside which an annular member with frustum-shaped internal and external threads matching the concave cavity nut is provided, an eccentric value based on a specification thread fit clearance is set between internal threads and external threads of the annular member, so that when the annular member is screwed into a bolt together with the nut for locking, the expected objective that the nut will not loosen by only locking a single structure is achieved thanks to a comprehensive effect of the formed original nut structure, the eccentricity of the annular member and the structure of multiple properties of the tapered thread; the single-structure nut is used in a superposed mode, or the annular member is arranged on another nut, so that the overall anti-loosening effect is improved by the double-nut structure.

A lock tight nut and bolt system resistant to loosening due to vibration. The lock tight nut and bolt system includes an upper nut that has a shank part. The upper nut has first threads that are off center from a center of a bolt. The upper nut is configured to receive the bolt. A lower nut has a socket part and second threads that are centered with the center of the bolt. The socket part corresponds with the shank park of the upper nut. The upper nut and the lower nut are concentric with the center of the bolt. The system further may include the bolt.

A lock tight nut and bolt system resistant to loosening due to vibration. The lock tight nut and bolt system includes an upper nut that has a shank part. The upper nut has first threads that are off center from a center of a bolt. The upper nut is configured to receive the bolt. A lower nut has a socket part and second threads that are centered with the center of the bolt. The socket part corresponds with the shank park of the upper nut. The upper nut and the lower nut are concentric with the center of the bolt. The system further may include the bolt.

A manufacturing process includes drilling a hole through a polyhedron; cutting a first surface from an outer surface of the polyhedron to the hole and subsequently clockwise cutting the outer surface of the polyhedron until the cutting meets a bottom edge of the first surface to form first and second nuts; rotating the first nut with about the second nut along the spiral cut surface to separate the first nut from the second nut, thereby forming a second surface, increasing height of the polyhedron, and forming a gap from the first surface to the second surface between the first nut and the second nut; fastening the first and second nuts together by spot welding; and disposing a sleeve on the polyhedron and driving a tap through the axial hole to create female threads in the first and second nuts respectively. An eccentric, internally threaded fastener is finished.

A combination positive locking and prevailing torque fastener system including a fastener nut, a helical wire insert, a nut cap, and a shaft. The nut cap is longitudinally movable from an engaged position to a disengaged position such that in the engaged position the fastener nut and the nut cap are rotationally locked, and in the disengaged position the nut cap rotates independent of the fastener nut.

A threaded fastening assembly includes a nut body and a screw body. The internal thread of the nut body includes a nut thread crest and a nut thread root. The external thread of the screw body includes a screw thread crest, a screw thread root, a fourth side wall located on one side of the screw thread crest, and a fifth side wall located on the other side of the screw thread crest. A locking notch located on one side of the nut thread crest is arranged on the internal thread. The locking notch includes a first side wall and a bottom wall. One end of the first side wall is connected to the nut thread crest, and the other end of the first side wall is connected to one end of the bottom wall. The bottom wall is spirally distributed around the axis of the nut body.