Method and device for producing a three-layer cord

Abstract

Method of manufacturing a metal cord with three concentric layers (C, C, C), of the type rubberized in situ, i.e. incorporating a composition made of rubber in the uncrosslinked state referred to as 'filling rubber', the said cable comprising a first, internal, layer or core (C), around which there are wound together in a helix, at a pitch p, in a second, intermediate, layer (C), N wires of diameter d, N varying from 3 to 12, around which second layer there are wound together as a helix at a pitch p, in a third, outer, layer (C), P wires of diameter d, P varying from 8 to 20, the said method comprising the following steps: a first sheathing step in which the core (C) is sheathed with the filling rubber; a first assembling step by twisting the N wires of the second layer (C) around the core (C) thus sheathed in order to form, at a point named the 'assembling point', an intermediate cord named “core strand” (C+C); downstream of the said assembling point, a second sheathing step in which the core strand (C+C) is sheathed with the filling rubber; a second assembling step in which the P wires of the third layer (C) are twisted around the core strand (C+C) thus sheathed; a final twist-balancing step.