Nitto Seiko Co., Ltd.

Kazuhiro Ueba

Naoki Nishimura

Sinnichi Hamano

Kinya Kowada

Disclosed herein is a tapping screw () exerting an excellent anti-loosening effect with regard to a workpiece made of a soft material such as resin and an aluminum alloy. The tapping screw () includes a shaft part (), and a normal thread () which is formed on the outer circumferential surface of the shaft part. A clearance groove () is formed by cutting out a portion of a ridge of the normal thread, and an engaging protrusion () is provided on a bottom of the clearance groove along a portion or an entirety of an edge of the bottom that continuously extends from a flank surface of the normal thread. The tapping screw () exerts an excellent anti-loosening effect even when a workpiece expands, contracts or oscillates because the engaging protrusions () are embedded into portions of the workpiece which have been embedded into the clearance grooves ().

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Kyoto, Japan

Kazuhiro Ueba