Patent ID: 8720176

Claim:
A method of manufacturing a metal cord with three concentric layers rubberized in situ, i.e. incorporating a composition made of rubber in an uncrosslinked state referred to as “filling rubber”, the cord comprising a first, internal, layer or core (C 1 ), consisting of M wires of diameter d 1 , M varying from 1 to 4, wherein the diameter d 1 is in a range from 0.08 to 0.50 mm around which there are wound together in a helix, at a pitch p 2 , in a second, intermediate, layer (C 2 ), N wires of diameter d 2 , N varying from 3 to 12, around which second layer there are wound together as a helix at a pitch p 3 , in a third, outer, layer (C 3 ), P wires of diameter d 3 , P varying from 8 to 20, the method comprising: sheathing the core (C 1 ) with a first filling rubber; twisting the N wires of the second layer (C 2 ) around the sheathed core (C 1 ) to form, at a point named an “assembling point”, an intermediate cord named “core strand” (C 1 +C 2 ); sheathing the core strand (C 1 +C 2 ) with a second filling rubber downstream of the assembling point; twisting the P wires of the third layer (C 3 ) around the sheathed core strand (C 1 +C 2 ); and twist-balancing to uniformly distribute said first and second filling rubber in the uncrosslinked state into capillaries formed by the N wires of the second layer (C 2 ) and the P wires of the third layer (C 3 ).