A male screw body comprises a shaft part, a first spiral groove that is formed in a circumferential surface of the shaft part and that is set at an appropriate lead angle and/or lead direction, and a second spiral groove that is set at a lead angle and/or lead direction that is different from the lead angle and/or lead direction of the first spiral groove, wherein the thread angle formed by a pair of inclined surfaces that extend from the apex to the valley of a screw thread that is created as a result of the first spiral groove and the second spiral groove being formed to overlap is established at 61-75. It is thus made possible for a male screw body to have two types of overlapping spiral grooves with different lead angles and/or lead directions to retain high fastening force.

A screw fastener particularly adapted to improve retention while minimizing mushrooming in fibrous workpieces. A single-threaded lower portion neighbours the pointed tip of the screw and a dual-threaded upper portion neighbours the screw head. The upper portion has a first upper thread that spirals in an opposite direction to the singular lower thread, and a second upper thread that spirals in a same direction as the singular lower thread. The lower thread includes a plurality of thread turns that share a same major thread diameter while axially spanning multiple areas of the lower portion of the shaft that vary in diameter, including a bulged area, a reduced upper area of lesser shaft diameter than the bulged area at a location between the bulged area and the head, and a downwardly tapered lower area at which the diameter of the shaft narrows from the bulged area toward the pointed tip.

An electric connector comprises a wall surrounding a receptacle that receives a strand of an electric wire and having a threaded hole extending through the wall and opening into the receptacle, and a fastener bolt screwed into the threaded hole and clamping the electric wire. The fastener bolt includes a bolt part having a head section, a thread section and a shearing section connecting the head section and the thread section. The fastener bolt further includes a nut part screwed onto the thread section. The shearing section is adapted to break if a predetermined fastening torque is exceeded. The thread section is hollow and has a predetermined tensile breaking strength.

A duplex threaded body having a right-handed and left-handed thread on the circumferential surface of a single solid member. A single-nut or double-nut type internally-threaded body demonstrates a locking effect at an intermediate position without substantially loosening by using a combination of a duplex externally-threaded body and one or more internally-threaded bodies. Moreover, a screw structure in which a pair of internally-threaded bodies can only be removed once they are mutually coupled when screwed onto a duplex externally-threaded body, making it possible to impart tamper-proof characteristics and a locking effect. The duplex externally-threaded body has, on the outer circumferential surface, an overlapping region with a clockwise spiral right-handed thread and a counter-clockwise spiral left-handed thread in an overlapping manner. A right-handed internally-threaded body in which a right-handed thread is formed, and a left-handed internally-threaded body in which a left-handed thread is formed, that are screwed onto a duplex externally-threaded body.

Provided is a manufacturing method for a compound screw having a first thread groove and a second thread groove with a different lead angle or lead direction from the first thread groove, wherein at least a portion of the first thread groove is formed by feeding a threading tool that acts on a workpiece a first feed amount toward the workpiece, the workpiece being a rotating object to be machined. Additionally, at least a portion of the second thread groove is formed by feeding the threading tool that acts on the workpiece a second feed amount that differs from the first feed amount. With these steps, a compound thread portion is formed in the workpiece. As a result, it is possible to mass produce a compound screw having two thread structures of differing lead angles and/or lead directions with a high level of quality.

A method of preventing cross-contamination comprising providing a first tank having standard thread fittings, providing a second tank having reverse thread fittings, storing LPG in the second tank, and storing anhydrous ammonia in the first tank.

A hybrid metal plastic shear fastener bolt. The bolt includes a metal body having a first end and an opposing second end including a head and including a threaded shaft extending from the first end towards the second end along a longitudinal bolt axis. The bolt also includes a plastic torque head formed on the metal body configured to shear away from the metal body at a predetermined torque.

A compression nut assembly is provided including a base nut and a compression nut. The base nut includes a base shaft having an interior surface and an exterior surface. The interior surface of the base shaft includes a plurality of internal threads extending in a first handedness direction. The compression nut includes a compression shaft having an interior surface and an exterior surface. The exterior surface of the compression shaft includes a plurality of external threads extending in the first handedness direction and engagable with the internal threads of the base shaft. The interior surface of the compression shaft includes a plurality of internal threads extending in a second handedness direction opposite the first handedness direction.

A relative rotation prevention structure for preventing relative rotation of a screw having a threaded section with respect to a counterpart member, the relative rotation prevention structure being equipped with: a counterpart-side displacement section formed in advance on the counterpart member and capable of displacement in the axial direction or the radial direction; and a screw-side deformation-capable section that is formed on the screw and deforms when pressed into the counterpart-side deformation section by means of fastening force and, due to that deformation, produces a screw-side displacement section that is displaced in the axial direction or the radial direction.

A fastener includes a head, a shank extending from the head, a first threaded portion having a plurality of first threads formed on the shank adjacent to the head, and a second threaded portion having a plurality of second threads formed on the shank distal from the head. The plurality of first threads have a handedness that is different from a handedness of the plurality of second threads.