Topura Co., Ltd.

Nhk Spring Co., Ltd.

Kabushiki Kaisha Topura

Shigeto Mori

Mayumi Matsuno

Naoki Horiuchi

Yousuke Okamura

Takeshi Suzuki

Toshio Kazama

Takeki Sawanishi

Seiya Hoshino

Yoshie Sato

Shunji Tozawa

Hiroshi Nakano

Akihide Umada

Takehiro Okuwaki

Yosuke Okamura

Minoru Sugiyama

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 () is partially provided on a flank surface () of a screw thread ridge provided on a screw thread shaft main body (), a screw thread ridge () in a section where the recessed portion () is formed is smaller than a regular screw thread ridge (), and a ridge height (H) in a distal end portion in a screwing direction is lower than a ridge height (H) in a rear end portion in the screwing direction W.

Screw thread

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.

External screw member

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.

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.

Fastening member and rod-like member for fastening member

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 (), and a screw shank () extending from the head (). The screw shank () is provided with a parallel thread portion () having a complete screw thread formed therein, a neck portion () having no screw thread, a transition thread portion () having an incomplete screw thread formed to extend from the parallel thread portion () toward the neck portion () 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 () formed in a corner angle portion between the neck portion () and a head bearing surface (), wherein the neck portion () is work hardened with its diameter being narrowed from a root diameter of the parallel thread portion ().

Threaded fastener

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.

Loosening prevention threaded fastener

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.

Coating agent for tapping screw, method for preparing the coating agent, method for forming coating layer on the periphery of tapping screw using the coating agent, and tapping screw having coating layer formed from the coating agent

The present invention provides a tightening structure with which a reduction in processing steps is achieved without modifying the shape of a partner member an improvements in bolt strength and fatigue strength are achieved, and with which the fitting length of a thread ridge is not altered greatly in comparison with a conventional tightening structure such that a size reduction can be achieved, thereby contributing greatly to a reduction in the weight of a vehicle.

Growing community of inventors

Hadano, Japan

Shigeto Mori