Multi-layer steel cable for tire crown reinforcement

摘要

A multi-layer cable having an unsaturated outer layer, usable as a reinforcing element for a crown reinforcement of a tire, comprising a core of diameter d₀ surrounded by an intermediate layer (C 1 ) of six or seven wires (N=6 or 7) of diameter d₁ wound together in a helix at a pitch p₁, this layer C 1 itself being surrounded by an outer layer (C 2 ) of P wires of diameter d₂ wound together in a helix at a pitch p₂, P being less by 1 to 3 than the maximum number P_max of wires which can be wound in one layer about the layer C 1 , this cable having the following characteristics (d₀, d₁, d₂, p₁ and p₂ in mm): (i) 0.28<=D₀<0.50; (ii) 0.25<=D₁<0.40; (iii) 0.25<=D₂<0.40; (iv) for N=6: l.10<(D₀/d₁)<1.40; for N=7: 1.40<(D₀/d₁)<1.70; (v) 5.3pi(d₀+d₁)12<4.7pi(D₀+2d₁+d₂); and (vi) the wires of layers C 1 and C 2 are wound in the same direction of twist. The invention furthermore relates to the articles or semi-finished products made of plastics material and/or rubber which are reinforced by such a multi-layer cable, in particular to radial tires and their crown reinforcement plies.