Process and plant for building tyres

A process for building tyres, including:

• arranging a carcass sleeve including at least one carcass ply and a pair of annular anchoring structures;
• arranging a toroidal forming drum in a first, radially contracted, operational condition;
• arranging said carcass sleeve in a position radially external to said forming drum;
• fitting the carcass sleeve around the forming drum;
• arranging an annular contrast element in a radially outer position around said carcass sleeve, then
• toroidally shaping said carcass sleeve against at least one radially inner surface of an annular contrast element while said forming drum is positioned inside the carcass sleeve, wherein during said toroidally shaping the carcass sleeve is in a contactless relationship with the forming drum and is shaped for subsequent coupling with the forming drum by a radial containment action exerted on the carcass sleeve and controlled by the annular contrast element;
• expanding said forming drum up to a second radially expanded, operational condition, wherein the toroidally shaped carcass sleeve is coupled to the forming drum in said second operational condition;
• and
• arranging said forming drum, coupled to said carcass sleeve, in proximity of at least one application device of additional components externally to said carcass sleeve,
• wherein fitting the carcass sleeve around the forming drum includes:
• positioning flange elements in a loading/unloading condition in which they are mutually spaced by an extent greater than an axial dimension of the unshaped carcass sleeve;
• engaging the forming drum coaxially between said flange elements;
• positioning the carcass sleeve coaxially between the flange elements;
• and
• axially translating the carcass sleeve to arrange the carcass sleeve in an axially centred position with respect to the forming drum, and
• wherein arranging said annular contrast element in a radially outer position around the carcass sleeve includes the following actions:
• positioning said annular contrast element coaxially between the flange elements;
• then
• axially translating the annular contrast element away from the forming drum, to move the annular contrast element to a stand-by position laterally arranged with respect to said flange elements, before positioning the carcass sleeve coaxially between the flange elements, and then
• axially moving the annular contrast element from the stand-by position to the radially outer position around said carcass sleeve, after the carcass sleeve has been positioned coaxially between the flange elements.