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.

A wood screw includes a head end, a shank and a tapered end, the head end including a tool engaging part, the head end located at a first end of the shank and the tapered end located at a second end of the shank. A thread is formed along the shank. The head end includes a neck running from the first end of the shank to a head cap, wherein the head cap includes an underside facing the tapered end, wherein the underside includes a plurality of serrations extending around the underside, each serration having a leading face and a trailing face that define a cutting edge, wherein the trailing face of each serration tapers away from the tapered end. A reaming section may be provided between the thread and the head end. The thread may include a notch configuration. The thread may be a dual start thread.

A fastener includes a shank having a first end and a second end defining a length. The fastener includes a thread provided on the shank, the thread including a first region adjacent to the first end and a second region between the first region and a head at the second end, the thread includes a leading edge and a trailing edge, each edge forming an angle with a surface of the shank, the leading edge forming a non-normal angle with the surface of the shank and the trailing edge forming an angle about normal to the surface of the shank. The fastener may include an arcuate detent region in the shank between respective turns of the thread, the detent region having a length, the length decreasing from the first end toward the second end between the respective turns. The fastener may include a plurality of flutes positioned along a length of the shank.

The invention provides a low-wear screw structure which comprises a screw head, a rod body, a first thread and at least a crushing rib, wherein the rod body extending out from the screw head and being successively formed with a rod extension part, a reaming part and a taper part, the first thread being annularly arranged on an outer peripheral surface of the rod body at a distance from the taper part to the rod extension part through the reaming part, the crushing ribs being arranged on the rod body at the reaming part, wherein a first included angle is formed between the first side surface and the outer peripheral surface of the rod body, a second included angle is formed between the second side surface and the outer peripheral surface of the rod body, and the first included angle is different from the second included angle.

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 fastener has a head and a shank extending from the head to a tip. The shank has a threaded distal portion that includes primary threads defining a major diameter, a minor diameter, and at least one helical rib or scalloped surface at the minor diameter. The at least one rib extends between adjacent primary threads of the threaded portion and extends in a helical configuration. The configuration of the fastener with helical ribs in the minor diameter reduces contact surface area between the fastener and building material substrate, like wood, during installation of the fastener, which thereby results in less torquing force required for installation.

A structural screw usable in multiple different substrates/materials includes a head end, a shank and a tapered end, the head end including a tool engaging part, the head end located at a first end of the shank and the tapered end located at a second end of the shank. A thread is formed along the shank, wherein the thread begins on the tapered end, extends onto the shank and terminates at a first axial location along the shank that is spaced from the head end. The thread (i) is a multiple start thread formed by at least a first helical thread and a second helical thread and/or (ii) includes a thread angle of between fifteen degrees and thirty degrees. The screw may also include a reaming section with leading and trailing wedge sections and/or an asymmetric notch pattern along at least part of the thread edge.

A screw includes a shank, a first thread, and a second thread. The shank includes a screw-in portion, a head portion, and a straight rod portion between the screw-in portion and the head portion. The first thread surrounds the shank spirally and includes an upper thread portion formed around the straight rod portion, a lower thread portion formed around the screw-in portion, and a middle thread portion continuously connected between the upper and lower thread portions. A plurality of serrate cutting teeth is provided on the middle thread portion of the first thread. The second thread is helically formed around the screw-in portion of the shank and includes a plurality of thread convolutions spaced from thread convolutions of the lower thread portion of the first thread. The screw can be quickly driven into articles to be joined without degradation of binding capacity between the screw and the articles.

A screw includes at least one helical thread with a peripheral edge having notched regions spaced apart by notch-free regions. An underside of a head of the screw includes projecting nibs.