| 摘要 |
PURPOSE: To obtain a favorable bead destruction power without bringing the volume up of a bead part or dropping a power utilization rate as a bead ring by giving a specific relation between a downward twist coefficient and an upward twist coefficient. CONSTITUTION: An organic fiber or a composite cord in which an organic fiber is reinforced with a resin or rubber is used as a cord for a tyre bead core. There is, used twice time twisted cords in which are arranged plural primary twisted threads and is applied the final twist, whose final twist coefficient prescribed by a formula in an opposite direction to the primary twist is N2 , are used, after applying a primary twist to the cord, whose primary twist coefficient prescribed by a formula is N1 . Wherein n1 is the number of primary twist (time/10cm), n2 is the number of final twist (time/10cm), D1 is the indicated denier number of a primary twisted thread, D2 is a total indicated denier number,ρis the specific weight of the fiber N1 is N1 =n1×(0.139×D1 /ρ)<1/2>×10<-3> , N2 =n2×(0.139×D2 /ρ)<1/2>×10<-3> .
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