The present invention provides a looseness-prevention screw thread structure including a screw thread having a predetermined pitch, a no-load flank which is an inclined surface in a direction in which the screw thread is advanced, and a load flank which is an inclined surface in a direction in which the screw thread is retracted, the no-load flank and the load flank being formed at both sides of the screw thread, in which the no-load flank of the screw thread includes: a first tangential portion which abuts against an arc portion formed at a thread crest of an opposing fastening object; and a second tangential portion which has a preset angle with respect to the first tangential portion and abuts against the arc portion.

The present invention provides a looseness-prevention screw thread structure including a screw thread having a predetermined pitch, a no-load flank which is an inclined surface in a direction in which the screw thread is advanced, and a load flank which is an inclined surface in a direction in which the screw thread is retracted, the no-load flank and the load flank being formed at both sides of the screw thread, in which the no-load flank of the screw thread includes: a first tangential portion which abuts against an arc portion formed at a thread crest of an opposing fastening object; and a second tangential portion which has a preset angle with respect to the first tangential portion and abuts against the arc portion.

A fastener including a bolt having an elongated shank having a first end, a second end opposite the first end, and a threaded portion having an external bolt thread, the bolt thread including a bolt pitch. The fastener includes a nut having a first end, a second end opposite the first end of the nut, and an internal nut thread extending between the first and second ends of the nut and adapted to engage threadedly the bolt thread of the bolt. The nut thread includes a nut pitch and a hardness that changes gradationally between the first and second ends of the nut. The bolt pitch of the bolt thread of the bolt is mismatched with the nut pitch of the nut thread of the nut.

A fastener including a bolt having an elongated shank having a first end, a second end opposite the first end, and a threaded portion having an external bolt thread, the bolt thread including a bolt pitch. The fastener includes a nut having a first end, a second end opposite the first end of the nut, and an internal nut thread extending between the first and second ends of the nut and adapted to engage threadedly the bolt thread of the bolt. The nut thread includes a nut pitch and a hardness that changes gradationally between the first and second ends of the nut. The bolt pitch of the bolt thread of the bolt is mismatched with the nut pitch of the nut thread of the nut.

In a screw-coupling structure between an internally-threaded body and an externally-threaded body, for connecting reinforcing bars: the internally-threaded body includes, on the inner diameter thereof, a parallel-tapered-integrated internal thread section formed by integrating a parallel internal thread section formed as a parallel screw thread, with a tapered internal thread section formed on one end of the parallel internal thread section so that the minor diameter thereof gradually narrows; and the externally-threaded body comprises, on the outer diameter thereof, a parallel-tapered-integrated external thread section formed by integrating a parallel external thread section formed as a parallel screw thread, with a tapered external thread section formed on one end of the parallel external thread section so that the major diameter thereof gradually narrows.

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.

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.

A fastener structure configured to be locked slantingly so as to provide effective and stable electrical conduction can be used to lock a to-be-locked object in place. The fastener structure includes a rod body and at least two inclination adjustment units. The rod body has a thread portion. The at least two inclination adjustment units are offset from each other and are formed on different surface portions of the rod body that are at different heights of the rod body respectively, such that the thread portion is left with an exposed surface portion. The at least two inclination adjustment units allow the rod body to be locked slantingly in the to-be-locked object, with the exposed surface portion of the thread portion in close contact with the thread of the threaded hole of the to-be-locked object to enable effective and stable electrical conduction.

A fastener structure configured to be locked slantingly so as to provide effective and stable electrical conduction can be used to lock a to-be-locked object in place. The fastener structure includes a rod body and at least two inclination adjustment units. The rod body has a thread portion. The at least two inclination adjustment units are offset from each other and are formed on different surface portions of the rod body that are at different heights of the rod body respectively, such that the thread portion is left with an exposed surface portion. The at least two inclination adjustment units allow the rod body to be locked slantingly in the to-be-locked object, with the exposed surface portion of the thread portion in close contact with the thread of the threaded hole of the to-be-locked object to enable effective and stable electrical conduction.

A self-locking screw wherein the self-locking function is maintained during many cutter head building and truing cycles. The inventive screw includes a self-locking feature having high elasticity and high self-locking torque. The screw includes a slot filled with an elastic compliant material.