METHOD AND DEVICE FOR PRODUCING A THREE-LAYER CORD

摘要

The invention relates to a method for producing a metal cord having three concentric layers (C1, C2, C3), of the type that is rubberized in situ, i.e. including a composition comprising rubber in the non-crosslinked state, known as "filling rubber". The cord comprises a first inner layer or core (C1), around which N strands of diameter d2 are wound together in the form of a helix with a pitch p2 to form an intermediate layer (C2), N varying between 3 and 12. In addition, P strands of diameter d3 are wound together around this second layer in the form of a helix with a pitch p3 to form a third outer layer (C3), P varying between 8 and 20. The method includes the following steps: a first step in which the core (C1) is coated with the filling rubber; a first step in which the N strands of the second layer (C2) are assembled and twisted around the thus coated core (C1), so as to form an intermediate cord, known as the "core strand" (C1+C2), at a point known as the "assembly point"; downstream from said assembly point, a second step in which the core strand (C1+C2) is coated with the filling rubber; a second step in which the P strands of the third layer (C3) are assembled and twisted around the thus coated core strand (C1+C2); and a final twist value balancing step. The invention also relates to the device used to implement one such method.