Bridgestone Metalpha Corporation

Bridgestone Corporation

Hiroki Ishizaka

Kiyoshi Ikehara

A steel cord which is suitable for reinforcing a rubber product and has excellent fatigue resistance. The steel cord has a layer-twisted structure formed by steel filaments respectively having a diameter of 0.15 mm to 0.25 mm. A core of the steel cord is formed by 1 to 4 steel filaments. A least 6 steel filaments are wound around the steel filaments of the core to form at least one layer. When the steel cord is bent from a straight state to a state in which a radius of curvature thereof is d/(17.times.10.sup.-3) wherein d is a diameter in millimeters of each steel filament in an outermost layer of the steel cord, a maximum amount of movement of each steel filament in the outermost layer in a cross-section of the steel cord is less than or equal to (-0.5454d+0.1454).times.10.sup.3 um. The steel cord preferably has a two-layer-twisted structure or a three-layer-twisted structure, and has an arrangement in which the diameters of the steel filaments gradually decrease from the core to the outermost layer.

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Kuroiso, Japan

Hiroki Ishizaka