Abstract: To provide a screw thread which achieves a further reduction in screwing torque while securing removability of a coating film or the like and which is capable of stabilizing conductivity. In a screw thread in which a recessed portion (7) is partially provided on a flank surface (131) of a screw thread ridge provided on a screw thread shaft main body (5), a screw thread ridge (13) in a section where the recessed portion (7) is formed is smaller than a regular screw thread ridge (3), and a ridge height (H12) in a distal end portion in a screwing direction is lower than a ridge height (H11) in a rear end portion in the screwing direction W.

Abstract: An external thread member capable of preventing oblique entry or insertion by a short screw tip shape is provided including, in its shank portion (20), a normal thread area (22), a guide thread area (24) provided at a tip side of the shank portion with respect to the normal thread area (22) and in which a guide screw thread (23) is formed, and a rising area (26) in which a transition screw thread (25) gradually rising from the guide screw thread (23) to the complete screw thread (21) is formed. A tapered guide portion (30) is provided at a tip end side of the normal thread area (22) and includes at least the guide thread area (24). The guide screw thread (23) is formed on an outer periphery of the tapered guide portion (30) which has a maximum diameter equal to or smaller than an inner diameter of an internal thread.

Abstract: An external screw member includes a parallel screw portion and a tapered screw portion provided on a side further toward a tip end than the parallel screw portion, and a plurality of sets of step portion and a transition screw thread portion are provided on at least one of the parallel screw portion and the tapered screw portion, the step portion having a reduced thread height in a radial direction and the transition screw thread portion gradually increasing in diameter from the step portion in an anti-driving rotation direction so as to reach a thread height of a normal screw thread portion. A top portion of the transition screw thread portion is positioned at an offset toward a pressure side relative to a position of a regular screw pitch in a minimum diameter portion of the step portion, and transitions to the regular screw pitch in the anti-driving rotation direction.

Abstract: To provide a screw thread which achieves a further reduction in screwing torque while securing removability of a coating film or the like and which is capable of stabilizing conductivity. In a screw thread in which a recessed portion (7) is partially provided on a flank surface (131) of a screw thread ridge provided on a screw thread shaft main body (5), a screw thread ridge (13) in a section where the recessed portion (7) is formed is smaller than a regular screw thread ridge (3), and a ridge height (H12) in a distal end portion in a screwing direction is lower than a ridge height (H11) in a rear end portion in the screwing direction W.

Abstract: An aluminum alloy contains 0.7% to 1.8% of silicon, 0.5% to 2.1% of copper, 0.4% to 1.8% of manganese, 0.6% to 1.6% of magnesium, and 0.1% to 0.7% of zinc in terms of mass ratio and the balance aluminum with inevitable impurities.

Abstract: An external thread member capable of performing a fastening operation efficiently without increasing the number of parts by assembling a collar into the external thread member. The external thread member 1 includes a shaft portion 5 inserted into a mounting hole 105 of a mounting member 101 through a collar 7, and the mounting member 101 is fastened to a fastening member 102. The shaft portion 5 includes a threaded portion 51 and a neck portion 52. The collar 7 is mounted on the neck portion 52 so as to be rotatable relative to each other and is engaged with the threaded portion 51 whereby retention is achieved. A counterbore hole 106 is formed in an opening close to the mounting hole 105 of an internal thread hole 104 with a tubular portion 71 inserted into the mounting hole 105 of the collar 7.

Abstract: An external screw member includes a head, a shank, a parallel threaded portion, a tapered threaded portion, a screw thread, a convex portion and a screw driving side end face of the convex portion. The convex portion protruding more radially outward than the crest of the screw thread is formed in at least one of the parallel threaded portion and the tapered threaded portion over the tapered threaded portion and the parallel threaded portion. The screw driving side end face of the convex portion is configured to form an inclined plane which gradually rises from a root position of the end face at the side of the crest of the screw thread toward a crest of the convex portion in a direction opposite to a screw driving direction of the screw thread to reach the crest of the convex portion.

Abstract: An aluminum alloy contains 0.7% to 1.8% of silicon, 0.5% to 2.1% of copper, 0.4% to 1.8% of manganese, 0.6% to 1.6% of magnesium, and 0.1% to 0.7% of zinc in terms of mass ratio and the balance aluminum with inevitable impurities.

Abstract: A fastening member includes a first alloy portion and a second alloy portion. The first alloy portion is made of an aluminum alloy including 0.005 wt % to 5.0 wt % zinc and 0.6 wt % to 2.0 wt % magnesium and is provided to a part that comes into contact with at least one of a plurality of members serving as a fastening target. The second alloy portion is made of an aluminum alloy including more than 2.0 wt % and 5.0 wt % or less magnesium and more than 5.0 wt % and 10 wt % or less zinc and is joined to the first alloy portion.

Abstract: A threaded fastener is provided in which a head bearing surface can be in full intimate contact with a counterpart. The threaded fastener is provided with a head (10), and a screw shank (20) extending from the head (10). The screw shank (20) is provided with a parallel thread portion (22) having a complete screw thread formed therein, a neck portion (24) having no screw thread, a transition thread portion (26) having an incomplete screw thread formed to extend from the parallel thread portion (22) toward the neck portion (24) with its root diameter being the same as that of the complete screw thread and with its thread height gradually becoming lower to reach the neck portion, and an underneck rounded portion (28) formed in a corner angle portion between the neck portion (24) and a head bearing surface (11), wherein the neck portion (24) is work hardened with its diameter being narrowed from a root diameter of the parallel thread portion (22).

Abstract: By changing the timing of applying a heat treatment, a high-strength aluminum based alloy-made fastening part having an unprecedented tensile strength or other strength property and a method for manufacturing of the same are provided. The method is characterized in that an aluminum based alloy-made material is subjected to a solution treatment and is then age-hardened; work hardening is further applied to a shaft portion by drawing thereof in a heading process; and the shaft portion is thereafter subjected to a process of rolling male threads.

Abstract: A tapping screw provides sufficient tightening force even if used with a thin screwed member and tightening target member. The tapping screw (100) includes a first ridge (11) and a second ridge (12) configured to have incomplete threads that are 180° out of phase. The tapping screw (100) includes a first tightening force improvement ridge (13) and a second tightening force improvement ridge (14) that are set so as to be smaller than the outside diameters of complete thread sections of parallel threaded portions of the first ridge (11) and the second ridge (12) but larger than the inside diameter of the prepared hole are provided in each of areas which are 90° out of phase with the first ridge (11) and the second ridge (12), respectively, such that the tightening force improvement ridges bite into the prepared hole when the screw is fully screwed in.

Abstract: A novel loosening prevention threaded fastener in which a clearance side protrusion portion protruding radially outwardly toward a clearance flank surface of a female screw thread is formed on a clearance flank surface of a male screw thread, and the clearance side protrusion portion is constructed such that a tip end portion thereof interferes with the clearance flank surface of the female screw thread, in a state where a pressure flank surface of the male screw thread is in contact with a clearance flank surface of the female screw thread. At the time of screw fastening, the crest end portion of the clearance side protrusion portion is pushed to the pressure flank surface of the female screw thread so that it is deformed in a deflective manner to apply a predetermined contact pressure to a contact surface due to its elastic restoring force, thus providing resistance against a loosening direction.

Abstract: Provided are a coating agent capable of forming, on the periphery of a tapping screw, a coating layer which can hold female-thread-forming chips generated during screwing of the tapping screw into a prepared hole of a workpiece, thereby preventing scattering of the female-thread-forming chips; and a tapping screw having thereon a coating layer formed from the coating agent. The coating agent is a composition containing, as primary components, calcium montanate or a calcium-montanate-containing montanic acid species mixture, a thermoplastic resin emulsion, and water. The coating agent can form, on the periphery of a tapping screw, a coating layer which exhibits a lubricating function, and a function of capturing female-thread-forming chips.

Abstract: By changing the timing of applying a heat treatment, a high-strength aluminum based alloy-made fastening part having an unprecedented tensile strength or other strength property and a method for manufacturing of the same are provided. The method is characterized in that an aluminum based alloy-made material is subjected to a solution treatment and is then age-hardened; work hardening is further applied to a shaft portion by drawing thereof in a heading process; and the shaft portion is thereafter subjected to a process of rolling male threads.

Abstract: It is possible to prevent a screwing torque from becoming excessively high even when a screw is threadedly engaged into a deep guide hole. In a tapping screw 100 comprising a parallel screw 22, a taper thread 23 provided closer to a tip end of the tapping screw than the parallel screw 22, and a plurality of projections 30 which partially project along an apex and flanks on both sides of a screw thread and which form an internal thread on a surface of a guide hole formed in a to-be fastened member, the plurality of projections 30 are provided from a region where the taper thread 23 is provided to a portion of a region where the parallel screw 22 is provided, and a diameter of a virtual cylinder which comes into contact with tip ends of some of the projections 30 including a projection provided in a region where the parallel screw 22 is provided is larger than an outer diameter of a external thread of the parallel screw 22.

Abstract: Provided are a coating agent capable of forming, on the periphery of a tapping screw, a coating layer which can hold female-thread-forming chips generated during screwing of the tapping screw into a prepared hole of a workpiece, thereby preventing scattering of the female-thread-forming chips; and a tapping screw having thereon a coating layer formed from the coating agent. The coating agent is a composition containing, as primary components, calcium montanate or a calcium-montanate-containing montanic acid species mixture, a thermoplastic resin emulsion, and water. The coating agent can form, on the periphery of a tapping screw, a coating layer which exhibits a lubricating function, and a function of capturing female-thread-forming chips.

Abstract: It is possible to prevent a screwing torque from becoming excessively high even when a screw is threadedly engaged into a deep guide hole. In a tapping screw 100 comprising a parallel screw 22, a taper thread 23 provided closer to a tip end of the tapping screw than the parallel screw 22, and a plurality of projections 30 which partially project along an apex and flanks on both sides of a screw thread and which form an internal thread on a surface of a guide hole formed in a to-be fastened member, the plurality of projections 30 are provided from a region where the taper thread 23 is provided to a portion of a region where the parallel screw 22 is provided, and a diameter of a virtual cylinder which comes into contact with tip ends of some of the projections 30 including a projection provided in a region where the parallel screw 22 is provided is larger than an outer diameter of a external thread of the parallel screw 22.

Abstract: A surface-treating method of of screw parts, which method consists of coating beforehand a liquid organic resin based coating composition capable of forming a film having a volume resistivity of 1014 &OHgr;·cm or more at normal temperature onto a thread of screw parts to be mounted onto an automobile body by welding prior to a coating step of the automobile body, followed by heating and drying.

Abstract: A bolt provided with a pilot of the present invention is formed with a pilot portion, on the front end side of a shank portion, having an axis aligning with an axis of the shank portion. The pilot portion is formed with a guide thread portion continuous to the normal thread portion to about half portion of the pilot portion. The connecting portion between the normal thread portion and the guide thread portion has a connection thread portion having an outer diameter gradually reducing from the normal thread portion toward the front end portion of the pilot portion. According to such structure, workability can be improved.