A building structure including a first building member and a second building member may be connected by a plurality of fasteners, each fastener having a head, a threaded portion having a through hardness of between HRB 70 and HRC 40, a thread-forming portion of at least HRC 50 hardness enabling the fastener to form threads in at least the second steel building member, and a fluted lead portion of at least HRC 50 hardness with a nominal diameter between 70 and 95% of major diameter, such that the fastener is capable of providing a ratio of strip torque to thread-forming torque of at least 3.0 and a ratio of strip torque to drive torque greater than 6.0 when the second steel building member having a thickness of 0.25 inch and the fluted lead portion having at least one diameter within nominal diameter between 80 and 98% of major diameter.

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 self-tapping including a normal thread (10) and a female screw molding thread (12) having a larger diameter than that of the normal thread (10), out of pitches of the normal thread (10) positioned in a head portion side from the female screw molding thread (12), any one pitch is set to be larger than other pitches. The self-tapping not only reduces driving torques but also improves fastening force, and thus can be applied to various workpieces made of the soft material as well as a hard material.

This threaded fastening element (2) comprising a threading (14) extending along a central axis (A), the threading (14) having at least one screw thread having an apical angle decreasing gradually, continuously and monotonously, between a first apical angle (α1) and a second apical angle (α2) strictly smaller than the first apical angle. The threaded fastening element is a screw or a nut.

A fastening tool according to the invention includes: a female screw member (10) having an inverse screw that is fixed to the first member (1); a collar bolt (11) that is screwed with the female screw member (10); a fastening bolt (27) that is inserted into a center hole (19) of the collar bolt (11) from the second member side (2) and rotates the collar bolt (11) through a torque transmitter (25), thereby moving the collar bolt to a position colliding with the second member (2); and a fastening nut (33) that is fixed to the first member (1). An earth claw (21) protruding toward the second member (2) is formed at an outer periphery of an end surface of the collar bolt (11) facing the second member. The earth claw (21) is configured to bite into the second member (2) in an axial direction due to axial force generated by screwing the fastening bolt (7) with the fastening nut (33), thereby breaking an insulating coating layer (3) and thus ensuring electrical conduction.

A self-drilling screw composed of an austenitic or some other non-corrosive base material (1) is provided, having a shank (12), having a cutting or shaping drilling or threaded tip (16) arranged at one shank end and having a hard coating (3) applied at least to the drilling or threaded tip (16) by electrodeposition, this hard coating (3) having a layer containing a transition metal, for example a hard chromium layer. The shank (12) has a hard edge layer (2) at least under the hard coating (3). A topcoat (4) composed of a lubricating and heat-dissipating material, which preferably is metal, wax and/or lacquer, is applied to the hard coating (3).

A self-drilling screw (10) having a head (20), a shaft (30) at least partially wearing a thread (35) and a drill point (40). The base material of the screw (10) including the drill point (40) is integrally manufactured from an austenitic 300 series steel with a surface hardness (uncoated) of 400-600 HV 0.3. The surface of the screw has a top coating of Zn—Ni with a Ni-content between 12-15% deposited on the austenitic base material. This self-drilling screw (10) is manufactured from a blank of raw austenite 300 series steel which is initially squeezed by cold forming to reduce its diameter in a first operation and, in following cold forming operations the head, the drill point and a thread are formed.

The invention relates to a screw (10) including a head (12), a shaft (14), and a thread (16), with the thread (16) having at least two different thread sections (18, 20), with an external diameter D.sub.Gn of a thread section (18) near the head being smaller than an external diameter D.sub.Gf of a thread section (20) distant from the head and greater than an external diameter D.sub.Sf of the shaft (14) in the area of the thread section (20) distant from the head. According to the invention it is provided that the thread (16) extends up to the bottom of the head (12). The invention further relates to a fastening arrangement (24), the use thereof, and a method.

A flange to he assembled to an end portion of a duct member includes a plurality of pre-fabricated fastener entry areas disposed in an inner wall member, and a plurality of first fastener indicators disposed on an outer wall member, wherein the pre-fabricated fastener entry areas are substantially aligned with the first fastener indicators, each of the plurality of first fastener indicators being sized to guide and each corresponding fastener entry areas being sized to receive a self-tapping screw fastener there through to fasten the wall members to the end portion of the duct member. The fastener entry areas and correspondingly aligned fastener indicators, respectively, may be spaced apart such that the fasteners can be inserted at regular intervals along the length of the flange and the length of the end of the duct member.

A method of providing an electrical grounding point on an aluminum structural member of a motor vehicle. The member is hydro-formed to produce a closed cross-section, after which a hole surrounded by a flange is formed in a wall of the member. The flange is generally the shape of a truncated cone and extends toward an interior of the member. A self-tapping fastener having a grounding lead attached thereto is driven into the hole to cut threads into the flange and secure the grounding lead to the member. The self-tapping fastener allows the grounding connection to be achieved without any access to the hollow interior of the member as would otherwise be required.