A screw includes a head having a top face and a conical bottom surface, a shank, and thread convolutions. A chip guiding channel is recessedly formed on the conical bottom surface. On the conical bottom surface are spirally disposed a cutting portion which has a plurality cutting units sequentially arranged in a spiral manner, thereby allowing the chip guiding channel to be surrounded by the cutting units along a spiral track. The spiral arrangement of the cutting units assists the head in cutting fibers of a workpiece which are wound around the head into small chips in a continuous and spiral severing manner to reduce drilling torque and resistance, and the spirally-defined chip guiding channel also facilitates a smooth removal of the chips, thereby allowing the head to fit level with a top surface of the workpiece and increasing a fastening effect.

A fastener may include an elongated shank, a head at a distal end of the shank, and a drill point at a terminal end of the shank, which is opposite to the distal end. The fastener may include a primary thread starting at the drill point and extending along the shank towards the head. The fastener may include a secondary thread starting at the drill point, extending along the shank towards the head, and stopping in an axial direction before the primary thread ends. The secondary thread may be radially located 180 degrees from the primary thread. The drill point may include a plurality of radially extending cutting edges and one or more relieved flute portion extending along the surface of the drill point.

A fastener may include an elongated shank, a head at a distal end of the shank, and a drill point at a terminal end of the shank, which is opposite to the distal end. The fastener may include a primary thread starting at the drill point and extending along the shank towards the head. The fastener may include a secondary thread starting at the drill point, extending along the shank towards the head, and stopping in an axial direction before the primary thread ends. The secondary thread may be radially located 180 degrees from the primary thread. The drill point may include a plurality of radially extending cutting edges and one or more relieved flute portion extending along the surface of the drill point.

A gradient insulation screw (1) for adjustable fastening of a roofing membrane (2) on a substrate, in particular a steel sheet (3), the gradient insulation screw (1) comprising a drilling tip (4) with a first direction of rotation; following the drilling tip (4), an assembly thread (7) with a second direction of rotation, which differs from the first direction of rotation; following the assembly thread (7), a first thread-free region (8); following the first thread-free region (8), an adjustment thread (9) with the first direction of rotation, the outer diameter of which is greater than the outer diameter of the assembly thread (7) and the drilling tip (4); and following the adjustment thread (9), a tool holder (10) as well as a system (11) for adjustable fastening of a roofing membrane (2) on a substrate with a gradient insulation screw (1) and a holding element (12) and a method for adjustable fastening of a roofing membrane (2) on a substrate using such a system (11).

A fastening arrangement including a grommet, which is configured as a substantially cylindrical sleeve with a head part, with a hollow-cylindrical shaft and with a conical tip, and also a fastener and a nut, for example made of plastic, which is fitted on the first threaded portion of the fastener. The fastener has two threaded portions, wherein one threaded portion is configured as a right-hand thread and the other threaded portion is configured as a left-hand thread (or vice versa). Moreover, the invention comprises a mounting method for such a fastening arrangement, in which the setting operation (anchoring of the fastener, adjustment of the sheath) can be managed in one step without changing the driving direction of the setting tool.

A drill bit structure of a self-tapping screw is rotated clockwise to screw with a workpiece or is rotated counterclockwise to remove from the workpiece, and the self-tapping screw contains: a head, a shank, and a drill bit. The head is configured to connect with a tool. The shank integrally extends from the head. A conical face has a tip, two arcuate grooves, and two first cutting edges. Each of the first cutting edges is formed on a connection portion of each arcuate groove and the conical face. The drill bit includes two third cutting edges, and each third cutting edge is adjacent to the tip, shapes of the two first cutting edges correspond to shapes of the two third cutting edges respectively, and heights of the two first cutting edges are not less than the conical face. Each first cutting edge has a reinforcement portion.

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 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 method of manufacturing a drill comprises providing an elongate element defining a longitudinal direction and having, in the longitudinal direction, a front end, an intermediate section, and a rear end opposite to the front end; forming by cold forming only, at the front end, a drill tip having a cutting edge; and, forming by cold forming only, on the intermediate section, a channel extending along the longitudinal direction.

The invention relates to a cooking oven comprising at least two entities made of sheet metal (2, 3), each sheet metal entity (2, 3) comprising at least one surface carrying an enamel layer, specifically a vitreous enamel layer, said enamelled sheet metal entities (2, 3) overlapping each other and a screw connection for grounding and coupling said enamelled sheet metal entities (2, 3), wherein a ground element is at least indirectly coupled with one of said enamelled sheet metal entities (2, 3) for grounding said stack of enamelled sheet metal entities (2, 3), wherein at least one screw (5) with a screw shaft (5.1) is provided through said enamelled sheet metal entities (2, 3), wherein the screw (5) is at least indirectly electrically coupled with the ground element and said screw shaft (5.1) comprises a thread for providing an electric coupling between the enamelled sheet metal entities (2, 3).