Device and method for producing a breaker ply

An assembly for almost simultaneously manufacturing two breaker plies for a tyre, comprising two devices for manufacturing a breaker ply having a longitudinal axis, a breaker ply length and mutually parallel cords at a pre-set cord angle to the longitudinal axis, wherein each device comprises:

• an extrusion device for producing at least one continuous rubber strip having substantially mutually parallel embedded longitudinal cords having a centre-to-centre distance and having a strip width;
• a first transport device for transporting the continuous rubber strip in the direction of the longitudinal cords;
• a second transport device for transporting the breaker ply in the longitudinal direction of the breaker ply in a transport direction comprising a support surface for the breaker ply;
• a cutting device for cutting bands from the continuous strip diagonally at the cord angle;
• a building drum for receiving the breaker ply coming from the second transport device, wherein the building drum has an axis of rotation, wherein the first transport device is adapted for transporting the continuous strip to the second transport device, the second transport device is positioned with its transport direction at an angle having the size of a cord angle to the direction of the longitudinal cords, the longitudinal direction of the breaker ply substantially corresponds to the transport direction and the building drum is positioned with its axis of rotation substantially transverse to the second transport direction, wherein the second transport devices of the devices for manufacturing a breaker ply are positioned with their transport directions substantially parallel to each other.

A method for producing a breaker ply having a longitudinal axis, a breaker ply length and mutually parallel cords at a pre-set cord angle to the longitudinal axis, wherein a continuous rubber strip provided with substantially parallel longitudinal cords, a set strip width and set centre-to-centre distance between the longitudinal cords one to the other, is produced in the longitudinal direction by means of an extrusion process, the continuous rubber strip is cut into bands at the cord angle, a predetermined number of bands with cords substantially parallel and adjacent to each other at a set band distance with respect to each other for forming a breaker ply having a pre-set breaker ply length are placed on a support surface, wherein the mutual distance of the bands is calculated to obtain a set length of the breaker ply, when the breaker ply has reached the target breaker ply length the breaker ply is transported in longitudinal direction to a building drum, and is wound on the building drum, wherein a predetermined mutual centre-to-centre distance of the cords and the width of the continuous strip is set, the length of the breaker ply is measured during manufacturing, and the mutual distance of the bands is each time adjusted for realising a pre-set breaker ply length, wherein the adjustment of the mutual distance at the most is the centre-to-centre distance of the cords, preferably at the most 20% of the centre-to-centre distance.