Process and plant for building tyres for vehicle wheels

A process for building a tyre for a vehicle wheel wherein each tyre comprises a carcass structure and a crown structure, said crown structure comprising a belt structure comprising a first radially inner belt layer and at least one second belt layer radially external to the first belt layer, comprising:

• a) placing an annular assembly comprising a first radially inner belt layer and at least one second radially outer belt layer on at least one auxiliary turning up drum;
• b) defining at least one pair of folding lines in axially opposite positions of said annular assembly by respective abutment devices radially external to said auxiliary turning up drum;
• c) adjusting an axial position of said folding lines relative to a centre line plane of the auxiliary turning up drum;
• and
• d) turning up, at said folding lines, at least a part of end portions of said first belt layer axially protruding relative to said at least one second belt layer on said at least one second belt layer of said annular assembly.

An apparatus for building a tyre for vehicle wheels, said tyre comprising a carcass structure and a crown structure, said crown structure comprising a belt structure comprising a first radially inner belt layer and at least one second belt layer radially external to the first belt layer comprising:

• at least one auxiliary turning up drum capable of being adapted for supporting an annular assembly, comprising a first radially inner belt layer and at least one second belt layer radially external to said first belt layer;
• and
• a plurality of abutment devices, radially external to said auxiliary turning up drum capable of being adapted for defining at least one pair of folding lines in axially opposite positions of said annular assembly,
• wherein said abutment devices are adjustable in axial direction relative to a centre line plane of the auxiliary turning up drum.