Method and device for the perforated cutting of a reinforcing ply
A cutting blade, which is useable for cutting a reinforcing strip into reinforcing plies, includes one or more notches disposed at given intervals. When a volume of rubber separating two reinforcing threads is cut by the cutting blade, bridges of rubber are left between a rear edge of a first reinforcing ply and a front edge of a second reinforcing ply.
1. A method for producing a reinforcing ply used in a tyre, the ply including reinforcing threads that are coated in a rubber mixture, the threads being arranged parallel to one another and forming a given angle (α) with a longitudinal direction of the ply, the method comprising steps of:
cutting through a rubber portion located between two adjacent threads of a reinforcing strip, so as to separate a rear edge (N 1r ) of a first reinforcing ply (N 1 ) of the reinforcing strip from a front edge (N 2f ) of a second reinforcing ply (N 2 ) of the reinforcing strip; and
removing the first reinforcing ply (N 1 ) from the reinforcing strip after a predetermined relaxation period has elapsed, the first reinforcing ply (N 1 ) having a given length,
wherein, in the cutting step, cutting of the rubber portion is interrupted at predetermined intervals in order to leave bridges of rubber between the rear edge (N 1r ) of the first reinforcing ply (N 1 ) and the front edge (N 2f ) of the second reinforcing ply (N 2 ).
2. The method according to claim 1 , wherein the threads of the reinforcing ply form an angle (α) of between 45° and 90° with a longitudinal direction of the reinforcing ply.
3. The method according to claim 1 , wherein the bridges of rubber have a length, measured along a thread at an edge, of between 0.5 mm and 2 mm.
4. The method according to claim 1 , wherein the bridges of rubber are spaced apart by a length, measured along a thread at an edge, of between 1 cm and 15 cm.
5. The method according to claim 1 , wherein, during the step of removing the first reinforcing ply (N 1 ) from the reinforcing strip, the first reinforcing ply (N 1 ) is detached from the reinforcing strip by stretching the bridges of rubber located between the rear edge (N 1r ) of the first reinforcing ply (N 1 ) and the front edge (N 2f ) of the second reinforcing ply (N 2 ) until the bridges of rubber break.
6. The method according to claim 1 , wherein the relaxation period is at least greater than ten seconds.