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AssigneeTokyo Rope Manufacturing Co., Ltd.
InventorsKazuo Matsumaru, Koichi Horikawa
Estimating the term…
A high elongation compact helical steel cord with a high degree of elongation at break of not less than 5% has a (1.times.n) structure comprising three or more base wires which are helically preformed at a predetermined pitch and which are twisted in the same direction and at the same pitch so that the ratio P/D of the cord diameter D to the twisting pitch P is in the range of 8-15 with the base wire preforming pitch being shorter than the cord twisting pitch. The finished cord has a helical composite structure with its elongation under a load of 35 kgf/mm.sup.2 being 0.71%-1.00% and that under a load of 70 kgf/mm.sup.2 being 1.18%-1.57%. A radial tire is reinforced with the steel cord preferably as a steel belt cord. An apparatus for making the steel cord is provided with revolving preformers on the wire introducing portion of a bunching machine such that the bunching machine is rotated in a direction reverse to the rotational direction of the revolving preformers.
A steel cord of a (1.times.n) structure, comprising at least three base wires helically preformed at a pitch shorter than a cord twisting pitch, said base wires being twisted in a same direction and at the same pitch by one twisting operation with an elongation at break of not less than 5% so that a ratio P/D of a cord outer diameter D with respect to a twisting pitch P is in the range of 8-15 and as a result said base wires make a helical composite structure due to said twist and said helical preforming, and an elongation of the steel cord under a load of 35 kgf/mm.sup.2 is in the range of 0.71-1.00% and an elongation of the steel cord under a load of 70 kgf/mm.sup.2 is in the range of 1.18-1.57%.
A radial tire a portion of which is reinforced with steel cord of a (1.times.n) structure including at least three base wires helically preformed at a pitch shorter than a cord twisting pitch, said base wires being twisted in a same direction and at the same pitch by one twisting operation with an elongation at break of not less than 5% so that a ratio P/D of a cord outer diameter D with respect to a twisting pitch P is in the range of 8-15 and as a result said base wires make a helical composite structure due to said twist and said helical performing, and an elongation of the steel cord under a load of 35 kgf/mm.sup.2 is in the range of 0.71-1.00% and an elongation of the steel cord under a load of 70 kgf/mm.sup.2 is in the range of 1.18-1.57%.
Dependencies are inferred from the claim text.