| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel cord for reinforcing rubber, while securing a sufficient bonding property between the cord and rubber, avoiding the contact of a core element wire with side element wires and also enabling the suppression of dimensional change, and a pneumatic radial tire by using the same. SOLUTION: This steel cord 10 used for a belt layer 6 is provided by arranging with twisting the 5 pieces of side element wires 12 having the same wire diameter with the core element wire 11 at the outside of the single core element wire 11 treated with spiral forming, having a flat structure that each of circumscribed circle C11 of the core element wire and circumscribed circle C12 of the side element wires forms an elliptical shape and having 1.1≤D1/Ds≤2.0 range ratio of the longer diameter D1 of the circumscribed circle C12 of the side element wires to the shorter diameter Ds of the same. The twist direction of the core element wire 11 is the same direction of the twisting direction of the side element wires 12, the twist pitch P12 of the side element wires 12 is substantially 5 times of the magnitude of forming pitch 11 of the core element wire 11 and the central point O of the core element wire 11 is on an elliptic orbit CO having substantially 1/5 times diameter dimension to the diameter dimension of the circumscribe circle C12 of the side element wires 12. COPYRIGHT: (C)2008,JPO&INPIT
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