A method for temporarily releasing a screw anchorage includes unscrewing and removing a primary screw having a thread that is tappingly engaged in a mating thread in an ungrouted hole in a mineral substrate from the ungrouted hole. Subsequently to the unscrewing and removing, a retrofitting screw is screwed into the hole to form an annular gap between the retrofitting screw and the mineral substrate. A hardenable grout is placed in the annular gap and the hardenable grout is hardened in the annular gap.

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.b≥10.0, preferably ≥12.0, particularly preferably ≥15.0, and in particular ≥30.0.

The invention relates to a system for securing an anchor in a borehole in a mineral substrate, in particular concrete, mortar, or brickwork, comprising an anchor with a core section and a threaded section and comprising a furrowing tool for furrowing an internal thread in the borehole, wherein the furrowing tool comprises the following: a main part with a leading end and a trailing end, said main part having an outer surface on which a furrowing thread is formed that is suitable for furrowing the internal thread into the wall of the borehole. The outer surface of the main part is equipped with a plurality of elevations, each of which has a cutting edge, and all of the cutting edges lie at least partly on an imaginary cylinder with a diameter (do). The cutting edges are suitable for at least partially removing the inner wall of the borehole when the furrowing tool is rotated into the borehole in order to adapt the internal wall of the borehole to the imaginary cylinder.

A self-tapping screw made of synthetic material has a threaded shank defining a screw center line. The screw has proximal and distal insertion ends, the shank including first and second portions, the second proximal to the first. The pitch is the same in the first and second portions, and has a complete thread cross-section in the second portion. In the first portion, in the direction of the thread, the thread is divided into segments having an incomplete thread cross-section, the thread segments having leading end and trailing ends. The leading end of one thread segment extends further radially than the leading end of the thread segment preceding it and forms a cutting edge. In most of the thread segments the thread top in question, for substantially its full length, starting with the leading end, considered in thread direction, is situated at a constant radial distance from the center line.

A wood screw, including a cylindrical screw shank, at the end of which there is formed a tip, a screw head, which is formed at the other end of the screw shank, as well as a threaded section, which extends from the tip in the direction of the screw head, wherein the threaded section has a thread core and a thread winding having several threaded turns circulating the thread core, wherein several successive threaded turns have projections, which are formed alternatingly in essentially the direction of the screw head and in essentially the direction of the tip.

A first and second electric members respectively having electrical connection portions are electrically connected in a state that mutual positions are regulated by guide pins, and fastening screws which are inserted through fastening screw insertion holes of the second electric member are screwed into screw holes for fastening of the first electric member, and thereby the first and second electric members are fastened. At least one of the screw holes for fastening has large-diameter portions into which the guide pin is detachably inserted, and small-diameter portions equipped with female screw portions. The female screw portions are not arranged in the large-diameter portions, and inner diameters of the large-diameter portions are larger than root diameters of the female screw portions, and outer circumferential surfaces of the fastening screws which are screwed with the female screw portions and inner circumferential surfaces of the large-diameter portions are not in contact with each other.

A screw includes a shank with an outer periphery, a head connected to the shank, and thread convolutions spiraling around the shank in a right-hand direction. The outer periphery defines opposite first and second peripheral envelope surfaces. A cutting slot unit is formed on the shank and arranged on the first peripheral envelope surface. The cutting slot unit includes a first cutting slot with two first edges and a second cutting slot with two second edges. The first edge extends in an extension direction opposite to the right-hand direction. One first edge of the first cutting slot is parallel to one second edge of the second cutting slot. The opposite extension of the cutting slot unit assists the screw in screwing quickly, attains quick removal of chips, and increases the fastening effect by pressing chips downwards.

A screw includes a shank with an outer periphery, a head connected to the shank, and thread convolutions spiraling around the shank in a right-hand direction. The outer periphery defines opposite first and second peripheral envelope surfaces. A cutting slot unit is formed on the shank and arranged on the first peripheral envelope surface. The cutting slot unit includes a first cutting slot with two first edges and a second cutting slot with two second edges. The first edge extends in an extension direction opposite to the right-hand direction. One first edge of the first cutting slot is parallel to one second edge of the second cutting slot. The opposite extension of the cutting slot unit assists the screw in screwing quickly, attains quick removal of chips, and increases the fastening effect by pressing chips downwards.

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 presently disclosed subject matter generally relates to vehicle fastening systems that include head bolts. The disclosed head bolts are adapted to be used in internal combustion engines in a wide variety of vehicles. Specifically, the disclosed head bolts are used to fasten an engine's cylinder head to the engine block housing the pistons. Advantageously, the disclosed head bolt is constructed from carbon fiber material, providing several advantages over prior art fasteners. For example, the head bolt is lightweight, temperature resistant, and exhibits increased strength when compared to conventional head bolts constructed from steel and other metals.