A screw with multiple thread angles includes a shank, a main threaded portion having thread convolutions, and a head. Each thread convolution defines different thread angles from a root to a thread crest in sequence, namely a first thread angle ranging between 70 degrees and 75 degrees, a second thread angle ranging between 37 degrees and 43 degrees, and a third thread angle ranging between 20 degrees and 23 degrees. Notches are recessed into the thread crest for attaining a smooth removal of cut chips. The third thread angle assists each thread convolution in cutting a workpiece sharply to facilitate a quick cutting operation. The second thread angle and the first thread angle help widen a cutting track caused by the cutting operation gradually so that the thread convolutions are continuously drilled into the workpiece by a multi-stage reaming and drilling operation to achieve a quick screwing effect.

Various embodiments of a fastener driveable into a substrate are provided. The fastener includes a head, a shank, and a helical thread formation. Portions of the shank and helical thread formations may be tapered. The outer diameter of the shank may decrease in a direction away from the head. An outer diameter of the thread formation may increase in a direction away from the head. The head may include a plurality of extending ribs. The helical thread formation may be formed with a plurality of grooves that are respectively each partially defined by a straight cutting edge. These improvements reduce torsional failure of the fastener from over tightening.

The invention relates to a screw (1), having a shank (3) which is provided with a thread (2) with at least one asymmetrical thread turn (4) with a plurality of windings, wherein the thread has an external diameter (Da), a core diameter (Dk) and a thread pitch (P), wherein the thread turn (4) has thread flanks (7, 8) with a flank angle (phi), wherein the thread flanks (7, 8) have a load-bearing flank (7) and a counter-flank (8) which abut one another directly or indirectly in a thread bottom (9) and at a thread tip (10), and wherein a flank angle (phiL) of the load-bearing flank (7) is smaller than a flank angle (phiG) of the counter-flank (8). The flank angle (phiL) of the load-bearing flank is at least 25°, preferably from 25° to 35°, in particular 30°, and the flank angle (phiG) of the counter-flank is at least 40°, preferably from 40° to 60°, in particular 50°, wherein the flank angle (phi) is from at least 65° to at most 95°. Screws of said type are used, in particular, for direct screw connection in light metal cast components.

A metal anchoring fastener fastens millwork onto walls constructed with wall cladding fastened to steel studs. The load typical of a loaded cabinet is borne by the steel stud anchors owing to the mate between the profile of the steel stud anchor and the layers of millwork and wall cladding and steel stud that said anchor penetrates. The pitch of the thread adorning the profile of the steel stud anchor progresses non-linearly along the length of said shaft, the shaft is generally non-linear in profile, and the thread profile is non-uniform along the length of said shaft. The anchor can also support a secondary screw concentrically penetrating the void at the center of the anchor, in order to hang loads from a wall, with or without millwork. Predrilling of the holes can enable installation of these zinc anchors.

A screw including a shank having a tip, a rear end, which is located opposite the tip, and a longitudinal axis, which extends through the tip and through the rear end, and a screw thread helix, which is arranged on the shank, wherein the screw thread helix has a screw thread ridge for engaging into an internal screw thread groove, wherein the shank has a rearwardly facing abutment structure, which extends alongside the screw thread helix, for axial abutment of the screw thread helix. The pitch of the screw thread ridge increases as the axial distance of the screw thread ridge from the tip increases, and the screw thread helix has axial tipward play with respect to the rearwardly facing abutment structure, so as to permit axial compression of the screw thread helix.

A cement board screw a high thread that begins on the tapered end, extends onto the shank and terminates at a second axial location along the shank. The high thread defines a high peripheral edge, where a leading flank and a trailing flank meet at the high peripheral edge and together define a high thread angle that is between about thirty degrees and about fifty-five degrees. A low thread begins on the tapered end, extends onto the shank and terminates substantially at a first axial location along the shank such that an axial length of the low thread is less than an axial length of the high thread. The low thread includes a leading flank and a trailing flank that meet at a low peripheral edge and together define a low thread angle that is between about fifty degrees and about seventy degrees.

A self-tapping screw includes a head portion, a lower side thereof configured with a screw rod, a front end thereof configured with a drill tail, a first thread segment formed on a front end of the screw rod above the drill tail, a second thread segment with at least two threads formed on a rear end of the screw rod immediately below the head portion, a crest angle of any one of the threads of the second screw segment being 1.15 to 1.2 times of a crest angle of any thread of the first thread segment, and a thread root diameter of the second thread segment increasing proportionally with the crest angle of the second thread segment. Whereby, the present invention provides a self-tapping screw capable of tight locking without idling.

A multipurpose screw is provided. The screw comprises: a head having a tool engaging formation, a self-drilling drill tip, and a shank extending between the head and the drill tip. The shank includes a threaded portion and an unthreaded portion. The threaded portion includes a major thread extending from the drill tip. The ratio between the major diameter of the major thread and the pitch of the major thread is from 1.2 to 2.4.

A screw includes a shank having a tip, a rear end which is disposed opposite the tip, and a longitudinal axis which extends through the tip and through the rear end. The shank consists of a first steel material. A screw thread helix is disposed on the shank and protrudes from the shank. The screw thread helix consists of a second steel material that is different from the first steel material. Both the first steel material and the second steel material are stainless steels.

A screw for particle board includes a head; a threaded shank; and a plurality of screw threads formed on the threaded shank. The head includes a slot on a top. The threaded shank is formed with the head and includes a shank and a tip at an end of the shank. The screw threads are formed on both the shank and the tip. The shank includes a plurality of longitudinal recesses and a plurality of longitudinal projections. Each recess is adjacent to each projection. Each screw thread is disposed between one of the recesses and the projection adjacent to the recess.