CPC D07B 1/0633 (2013.01) [D07B 1/0666 (2013.01); D07B 1/162 (2013.01); D07B 2201/1036 (2013.01); D07B 2201/1052 (2013.01); D07B 2201/2006 (2013.01); D07B 2201/2037 (2013.01); D07B 2201/2051 (2013.01); D07B 2501/2046 (2013.01)] | 13 Claims |
1. A compact steel cord, comprising a core-filament I steel wire with a diameter of d0, and four middle-layer M steel wires with a diameter of d1 and eight outer-layer O steel wires with a diameter of d2 that are twisted around the core-filament I steel wire in a same lay direction and a same lay length, wherein
gaps L are reserved between the outer-layer O steel wires, an average width of the gaps L is not less than 0.02 mm, and a total size of the gaps L is larger than d0 and smaller than d1;
tensile strengths of the core-filament I steel wire, the middle-layer M steel wire and the outer-laver O steel wire are respectively Ts1, Ts2, and Ts3, which satisfy the following relationships:
50 Mpa<(Ts2−Ts1)<400 Mpa; and
0 Mpa≤(Ts3−Ts2)<400 Mpa.
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