Tyre Carcass Forming Method and Drum

1) A drum for forming a tyre carcass, the drum having a longitudinal axis, and comprising two half-drums and two turn-up bladders, each of which is mounted on a respective half-drum and comprises an intermediate portion and an annular portion, wherein the annular portion is arranged, at rest, in contact with the respective half-drum and beneath the intermediate portion;

• the half-drums being of fixed axial length, being movable in opposite directions along the longitudinal axis to and from a centre plane of the drum, and being covered externally with the respective turn-up bladders, each of which has at least a first annular shoe connected directly to the respective half-drum;
• and pneumatic inflation means for distending a given annular portion of each turn-up bladder;
• the drum comprising, on each half-drum, guide means, which are axially fixed with respect to the half-drum, are rigidly connected to said annular portion so as to move therewith and are activated by the pneumatic inflation means to move the annular portion into a given final position,
• wherein the guide means are rigidly connected to the half-drum at a fixed point which is axially arranged outside the respective annular portion when the annular portion is both at rest and distended;
• and wherein the guide means are axially more rigid than the turn-up bladders to result, when each turn-up bladder is distended, in the guide means acting as a substantially conical brace to prevent substantially axial movement, and only permit substantially radial movement of any point of the annular portion along a substantially radial trajectory with respect to the longitudinal axis, and also to result in the intermediate portion being axially pushed towards the respective sidewall.