A composite screw includes a tapping end portion that includes a circular bottom surface, a peripheral surface and a main thread. The peripheral surface extends from the circular bottom surface. The main thread is formed around the peripheral surface. A reception recess is recessed from the circular bottom surface and the peripheral surface. The main thread has a discontinuation where the reception recess opens at the peripheral surface. A rigid body and a weld material fill the reception recess. The rigid body has an outer surface and an auxiliary thread. The outer surface is exposed from the reception recess. The auxiliary thread is formed on the outer surface and connected to the main thread to fill the discontinuation.

A building structure including a first building member and a second building member may be connected by a plurality of fasteners, each fastener having a head, a threaded portion having a through hardness of between HRB 70 and HRC 40, a thread-forming portion of at least HRC 50 hardness enabling the fastener to form threads in at least the second steel building member, and a fluted lead portion of at least HRC 50 hardness with a nominal diameter between 70 and 95% of major diameter, such that the fastener is capable of providing a ratio of strip torque to thread-forming torque of at least 3.0 and a ratio of strip torque to drive torque greater than 6.0 when the second steel building member having a thickness of 0.25 inch and the fluted lead portion having at least one diameter within nominal diameter between 80 and 98% of major diameter.

A low energy wood screw that may be inserted quickly and using less energy than conventional screws. In various embodiments, the screw may include a countersunk head having a recess for accommodating a driving tool, a tapered neck, a plurality of crown ribs extending over the head and neck, a lubricating coating, main threads with a large thread lead, and lower threads having an asymmetrical profile and extending onto a gimlet point.

A self-tapping screw head structure includes a screw head, a rod, a cone and a thread. A direction of the thread surrounding the cone and the rod determines a tapping direction. The screw head includes a top portion, a first neck portion connected to the top portion and having a circumference decreasing towards away from the top portion, a plurality of recesses recessed at a surface of the first neck portion, and a second neck portion connected to the first neck portion and having a circumference gradually decreasing towards away from the first neck portion. Each of the plurality of recesses includes a cutting end, a crumb guiding end away from the cutting end, a first accommodating groove and a second accommodating groove. A recess depth of the first accommodating groove is greater than that of the second accommodating groove.

A screw having a head and a tip at opposite ends, and a shank extending between the head and the tip, the head including: a top portion, and a frustoconical portion arranged between the top portion and the shank, wherein the frustoconical portion includes a step defining an annular recess towards the shank; and at least one radial rib arranged in the recess and extending towards the shank.

A fire protective fastening system connects a non-load bearing wall to a truss. A fire protective interface is disposed between a top plate structure and a load bearing member. Fasteners connect between the load bearing member and a non-load bearing member to form a floating connection between the non-load bearing member and the load bearing member. The fire protective medium may take a number of forms including a batt of mineral wool, an intumescent tape and an elongated barrier formed of light gauge metal or spring steel.

A wood screw includes a shank, a head connected thereto, a drilling portion opposite to the head, a plurality of threads spirally disposed on the shank and the drilling portion, and at least two first ribs extending on the drilling portion between two adjacent thread convolutions of the threads. The first ribs extend in a direction different from a screwing direction. Each first rib has two first surfaces protruding from the shank and converging at a first edge. The first edges of the first ribs are orientated in the screwing direction. Accordingly, the first ribs assist the drilling portion in enlarging a cutting area to increase the cutting effect and reduce the screwing resistance derived from the screwing operation. The first ribs and the thread convolution cooperate to form three cutting points in cross section, thereby achieving a stable, speedy and effort-saving screwing effect.

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.

A method of producing fastening assembly (10) including a series of layers (12, 14, 16) and a screw (18), the screw (18) having a screw head (20), a shaft (24), a thread (26) extending into a displacement tip (22) and an unthreaded shaft portion (28). The method includes screwing the screw (18) into the series of layers (12, 14, 16), the layer (14) in the series of layers (12, 14, 16) that is furthest from the screw head (20) being deformed in the screw-in direction, so that a thickness D.sub.p of the series of layers (12, 14, 16) is increased in a region around the screw (18), and continuing to screw in the screw (18) until the screw head (20) strikes the series of layers, a maximum thickness D.sub.p, max of the series of layers being reached at this moment and the length L.sub.F of the unthreaded shaft portion (28) being up to 10% less than and up to 30% greater than the maximum thickness D.sub.p, max of the series of layers.

An impact-driven threaded nail includes a threaded portion with a lead angle of about 45, the threaded portion being defined along an outer circumference of a nail shank that includes a first end defined as a pointed tip; and a head having a larger diameter than the nail shank, the head being integrally provided at a second end of the nail shank, wherein a tapered portion of the head on a back-surface side in continuation with the nail shank is defined in a pyramidal shape having one of regular pentagonal to octagonal cross-sections with a diameter decreasing gradually toward the nail shank, and the threaded nail is configured to be impact-driven and rotate into a mounting member when impacted.