Process and apparatus for manufacturing tyres

A process for manufacturing a tyre comprising:

• building a carcass sleeve around a forming drum having an application diameter, said carcass sleeve comprising a carcass ply with axially opposite end flaps, each of which is coaxially engaged to an annular anchoring structure defining a fitting diameter smaller than the application diameter, wherein the building of said carcass sleeve comprises:
• providing the drum so that it has two lateral half-portions which are axially moved relative to one another, each lateral half-portion comprising a circumferentially continuous axially outer shoulder and a plurality of teeth which are axially extended from this shoulder towards the other half-portion, the teeth of each half-portion being circumferentially alternating relative to those of the other half-portion so that the teeth of the half-portions mesh with each other and the teeth of each half-portion are slidably inserted in alternating sequence between the teeth belonging to the other half-portion, free spaces which remain by the end of each of the teeth of one of the half-portions and by the two adjacent teeth of the other half-portion providing openings in a discontinuous surface of the drum,
• wherein the drum is further provided with a single plate extending only partly around the circumference of the drum and arranged radially more external relative to the half-portions and providing a continuous surface on the drum such that the continuous surface covers a section of the half-portions and the half-portions slide against the radial interior of the plate as they move axially with respect to one another, the use of the single plate causing the radially peripheral surface of the drum to have the same peripheral diameter, except only for a portion limited to the continuous surface of the drum,
• wherein the step of building the carcass sleeve comprises applying and retaining a leading end of a semi-finished product, which was cut to size from a continuous strip, against the continuous surface of the plate, then rotating the drum so that the cut semi-finished product is wound around the drum until a trailing end of the semi-finished product becomes superimposed on the leading end over the plate while the remaining circumferential portion of the semi-finished product, between the leading and trailing ends, is laid on a central portion of the two lateral half-portions, against the openings;
• after superimposing the leading and trailing ends, pressing the trailing end on the leading end and against the forming drum for mutually joining said leading and trailing ends while the leading end rests against the plate;
• and
• wherein the lateral half-portions are radially contractible and the radial position of the plate is adjusted as a function of the radial configuration of the half-portions by a radially movable structure arranged between the lateral half-portions such that the plate is always radially more external relative to the half-portions.