A panel fastener is provided that has a head having a first surface and a second surface opposite the first surface; an engagement feature on the first surface of the head, the engagement feature being configured to be engaged by a driving tool; a shank extending from the second surface of the head; a threaded portion extending from the shank, the threaded portion having first and second helical threads arranged in an intertwined manner; the first thread extending farther radially from the central axis than does the second thread; and the shank being located between the head and the threaded portion.

Various embodiments provide a fastener including a head, a shank connected to the head and having a tip, one or more helical thread formations extending outwardly from the shank, and wherein a bottom portion of the head includes a plurality of ribs that extend towards the tip of the shank and that are shaped to abruptly frictionally engage a surface of a first object being attached to a second object to create an immediate frictional torsional resistance of a desired force level to the tightening of the fastener. This frictional resistance is provided back to the tightening tool to inform the operator of the tightening tool that the head of the fastener has sufficiently engaged the first object and that further tightening or clockwise rotation of the fastener is unnecessary.

A self-tapping screw (10, 30) comprising a drive (12) and a shank (14) bearing a thread comprising a main thread (16, 32), wherein the main thread (16, 32) has a maximum main thread external diameter (D.sub.AF) and a cutting area (F) and a supporting area (T) following in the direction of the drive (12), wherein the shank (14) has a threaded end (18) at an end opposite the drive (12), with the screw end (18) having a diameter (DE) of at least 20% of the maximum main thread external diameter (D.sub.AF), The shank further has, in the region of the screw end (18), a tap flute (20), wherein the tap flute (20) comprises at least two tapping thread turns (20a, 20b, 20c) which attain, in their external diameter (D.sub.AA), no more than 90% of the maximum main thread external diameter (D.sub.AF) and form a tap region in which the tapping thread turns (20a, 20b, 20c) have the same diameter development, and in addition in that the diameter of the main thread (16, 32) in the tap flute region (AB) is less than or equal to the diameter (D.sub.AA) of the tapping thread turns (20a, 20b, 20c).

Various embodiments provide a fastener including a head, a shank connected to the head and having a tip, one or more helical thread formations extending outwardly from the shank, and wherein a bottom portion of the head includes a plurality of ribs that extend towards the tip of the shank and that are shaped to abruptly frictionally engage a surface of a first object being attached to a second object to create an immediate frictional torsional resistance of a desired force level to the tightening of the fastener. This frictional resistance is provided back to the tightening tool to inform the operator of the tightening tool that the head of the fastener has sufficiently engaged the first object and that further tightening or clockwise rotation of the fastener is unnecessary.

A fastening assembly includes a panel defining an aperture, a fastener having a head, a shaft portion extending from the head, and a recess formed in the head, and a sacrificial primary anode insert disposed in the recess. The sacrificial primary anode insert is configured to corrode at a rate faster than a corrosion rate of the fastener.

A self-drilling self-tapping fastener that provides improved performance in both drilling time and pullout force without decreasing performance in any of ductility, tapping torque, torsional strength, and tension strength.

The present invention relates to a screw element (1) comprising a threaded shaft (2), a screw tip (4) formed on one shaft end and a screw head (5), formed on an opposite shaft end and with force application means (7), and comprising a screw thread (12) extending on the threaded shaft (2) and on the screw tip (4), wherein the screw tip (4) has a front tip section (4a) tapering toward the screw element end, when viewed in the screwing-in direction (Z), and a section (4b) formed on the threaded shaft with a polygonal cross section, when viewed in cross section, whose enveloping circle diameter (d.sub.h) is greater than a core diameter (d.sub.k) of the screw tip (4), and the polygonal cross section has a corner point (15) lying on the enveloping circle of the section (4b), and a front edge surface (9), radially oriented with respect to a longitudinal center axis (X-X), ends in said corner point in the sense of an increased diameter. The screw tip (4) has a first tapering tip section (4a) with a circular cross section and a second, cylindrical tip section (4c) with a circular cross section formed between the first tip section (4a) and the polygonal section (4b), wherein the screw thread (12) is continuously formed without interruption across the first and second tip sections (4a, 4c) of the screw tip (4).

A concrete screw is adapted to be driven into a hole predrilled in a concrete structure and includes a head, a shank extending from the head, a thread formed on the shank, and a plurality of bump units. The shank includes front and rear segments spaced along a longitudinal axis. The bump units are distributed on at least the front segment of the shank and staggered along the longitudinal axis. Each bump unit includes a plurality of bumps constitute an inclined pattern relative to the longitudinal axis. Each bump protrudes from the periphery of the shank. In the course of the screw being driven into the hole, the bumps pulverize concrete debris in the hole, and waste debris accumulates at a segment of the shank on which the bump units are distributed for development of a pressing segment and promotion of anti-pullout strength of the screw.

A self-driving masonry anchor that includes ahead configured to receive a driving bit, a threaded section extending from the bottom of the head, a drilling section following the threaded section, and a drill tip at the end of the drilling section. The threaded section includes alternating high and low threads. The high threads include notches or serrations. The low threads are double low threads such that there are two low threads between each high thread. The drilling section includes at least two flutes for the removal of debris. The drill tip includes an abrasive material which is different than the material of the drilling section such that the drill tip and drill section predrill a hole in a masonry material for the threaded section, the threaded section fastening to the masonry material.

A self-driving masonry anchor that includes ahead configured to receive a driving bit, a threaded section extending from the bottom of the head, a drilling section following the threaded section, and a drill tip at the end of the drilling section. The threaded section includes alternating high and low threads. The high threads include notches or serrations. The low threads are double low threads such that there are two low threads between each high thread. The drilling section includes at least two flutes for the removal of debris. The drill tip includes an abrasive material which is different than the material of the drilling section such that the drill tip and drill section predrill a hole in a masonry material for the threaded section, the threaded section fastening to the masonry material.