A structure of a screw is provided, including a shank extending downward from a screw head. The shank has an outer circumferential surface on which a thread extending spirally around is formed. The shank has a lower end forming a tapering tail section. The thread does not extend into the tapering tail section. The tapering tail section is provided with at least one rib raised on a surface thereof. The rib has an edge that is made in a wavy-toothed form so as to improve the capability of the screw for cutting and chip removal and also to reduce a screw-in torque of a screwing operation of the screw to thereby achieve an effect of saving labor and time in conducting an operation and also to prevent the occurrence of defects of wood cracking to enhance the quality of an operation conducted with the screw.

The present invention provides a general use tapping screw, which is a two-line screw having a cylindrical body, and main threads and auxiliary threads which are formed on the outer circumferential surface of the body, wherein the outer diameter of the auxiliary threads is 9297% the outer diameter of the main threads, the angle of the front flank surfaces of the main threads and the auxiliary threads is in the range of 123 degrees, the angle of the rear flank surfaces of the main threads is in the range of 253 degrees, the angle of the rear flank surfaces of the auxiliary threads is in the range of 203 degrees, and intervals between a first pitch from the main thread to the auxiliary thread and a second pitch from the auxiliary thread to the next main threads have a difference in the range of 10-20%.

The invention relates to a fastening element, comprising an insertion segment for inserting into a bore, having a self-tapping threaded segment having an external thread for screwing and tapping into the bore on a fastening object, and comprising a mounting segment for arranging outside of the bore, having an interface geometry for applying a torque to the fastening wherein it should be possible to fix a fixing part to the fastening element in a simple manner. This aim is achieved in that the mounting segment is additionally provided with a fixing device for indirectly or directly, in particular interlockingly and/or frictionally, fixing a fixing part on the mounting

A threaded fastener including a head, a shank connected to the head at a first end of the shank, the shank includes a first portion, a second portion, a third portion, and a tip at an end of the shank opposite the head. The fastener includes a first helical thread formation extending outwardly from the second and third portions of the shank, and a second helical thread formation extending outwardly from a section of the third portion of the shank that is adjacent to the tip. The first helical thread formation defines grooves in the section of the third portion of the shank that is adjacent to the tip.

A screw for securing dense wood material has a head with a specially configured drive socket and an underside with an array of lobes. The lobes preferably have a left-handed orientation and have chamfered extremities. The shank is specially configured with an upper thread, an intermediate unthreaded portion and a lower thread which terminates with a half-point tip. In one embodiment, the upper thread major diameter is slightly smaller than the major diameter of the lower thread. The upper thread has a greater thread density than the lower thread. The upper to lower thread-per-inch density is preferably in the range of 1.3:1 to 1.7:1. The screw is specifically configured to assist in applications where there are wet fibers near the wood deck surface.

Disclosed herein is a system for fastening an anchor in a borehole in a mineral substrate, in particular concrete, mortar or masonry, comprising an anchor having a core section and a thread section, and a grooving tool for grooving an internal thread in the borehole, the grooving tool comprising the following: a base body having a leading and a trailing end, a force application device being provided, via which a torque for screwing the grooving tool into the borehole and for grooving the thread is transmitted to the base body, the base body having an outer surface on which a grooving thread is formed, which is suitable for grooving the internal thread into the wall of the borehole, the following applying to the ratio of the length h.sub.eff of the thread section of the anchor and the nominal diameter d.sub.b of the borehole: h.sub.eff/d.sub.b10.0, preferably 12.0, particularly preferably 15.0, and in particular 30.0.

The present invention relates to a screw structure, including a head part, a rod part, a first thread and a second thread. The head part is arranged at one end of the rod part. The other end of the rod part is opposite to the head part to form a tapered tap-lock screw-in end. The first thread is arranged on the surface of the rod part with a clockwise spiral ring and extends to the tap-lock screw-in end. The second thread is arranged on the surface of the tap-lock screw-in end with a counterclockwise spiral ring. The crest height of the second thread is lower than 50% of the crest height of the first thread, and several teeth are formed on the second thread. Accordingly, through the setting of the second thread, the screw has multiple functions such as crushing and chip removal.

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 fastener includes a shank having a first end and a second end. The fastener includes a first thread region adjacent to the first end having a first helical thread and a second helical thread interposed with the first helical thread in the first thread region. A second thread region is provided adjacent to the first thread region, the second thread region including only the second helical thread with the second helical thread having a diameter greater than a diameter of the first helical thread. A third thread region having a third helical thread is provided extending from the second thread region toward the second end. A head is provided on the second end and includes a disk and an octagonal boss between the disk and the third thread region, the boss including four major sides extending perpendicular to the disk and four chamfered sides, the chamfered sides being flush with a side edge of the disk.

A screw includes a shank having an insertion tip and a head end which has an upper portion with a cutting portion and a lower portion from which a plurality of anti-screw-out teeth protrude. Each anti-screw-out tooth includes a guide face and a stop face intersecting a circumferential surface of the lower portion for development of a recessed channel. A first thread on the shank includes a plurality of asymmetrical thread convolutions each having a first cutting face facing onto the insertion tip and a second cutting face backing onto the insertion tip. The first cutting face and a horizontal axis form an included angle between 25 and 45 degrees. The second cutting face and the horizontal axis form an included angle between 3 and 23 degrees. The screw is in favor of surface flatness of a to-be-connected plank and pull-out as well as anti-screw-out properties of the screw.