Process and apparatus for manufacturing tyres for vehicle wheels

A method of building at least one carcass ply during manufacture of a tyre for a vehicle wheel, said carcass ply being built by laying an odd whole number of strip-like elements on a radially external surface exhibited by a forming drum, comprising:

• rotating the forming drum around a geometric rotation axis thereof;
• and
• applying said strip-like elements through a first laying unit and a second laying unit located close to opposite portions of said forming drum relative to the geometric rotation axis,
• wherein, before at least one application of said strip-like elements, the first laying unit is submitted to shifting along an adjustment path which lies in a plane orthogonal to the geometric rotation axis and is substantially tangent to the radially external laying surface of the forming drum.

A process for manufacturing tyres for vehicle wheels, each tyre comprising a carcass structure, a tread band at a radially external position to said carcass structure and a belt structure interposed between said carcass structure and tread band, wherein building the carcass structure comprises at least:

• building at least one carcass ply on a forming drum around at least one radially external laying surface by application of a plurality of strip-like elements, said at least one carcass ply having axially opposite end flaps;
• and
• coaxially engaging an annular anchoring structure around each of the end flaps, wherein building said at least one carcass ply comprises at least:
• setting a fitting diameter of the forming drum;
• setting a radial thickness of components of the tyre present on the forming drum before building said at least one carcass ply;
• calculating a corresponding extension of the radially external laying surface;
• setting a width W of said strip-like elements;
• setting a width of an overlapped part S between two adjacent strip-like elements;
• setting a ply angle γ;
• calculating a whole number of strip-like elements to be applied;
• and
• applying the calculated whole number of strip-like elements by rotating the forming drum around a geometric rotation axis thereof, and applying said strip-like elements through a first laying unit and a second laying unit located close to opposite portions of said forming drum relative to the geometric rotation axis,
• wherein, when the calculated whole number of strip-like elements is an odd number, before at least one application of strip-like elements, a first laying unit is submitted to shifting along an adjustment path that lies in a plane orthogonal to the geometric rotation axis and is substantially tangent to the radially external laying surface of the forming drum.

An apparatus for manufacturing tyres for vehicle wheels, each tyre comprising a carcass structure, a tread band at a radially external position to said carcass structure and a belt structure interposed between said carcass structure and tread band, comprising:

• a forming drum having at least one radially external laying surface;
• devices for building at least one carcass ply around said radially external surface, said at least one carcass ply having axially opposite end flaps;
• and
• devices for coaxially engaging an annular anchoring structure around each of the end flaps,
• wherein the devices for building at least one carcass ply around said radially external surface comprise:
• devices for setting the forming drum in rotation around a geometric rotation axis thereof;
• a first laying unit and a second laying unit mounted at mutually opposite portions of the forming drum and capable of being adapted to apply a plurality of strip-like elements along the circumferential extension of the forming drum;
• an adjustment device for shifting the first laying unit along an adjustment path which lies in a plane orthogonal to the geometric rotation axis and is substantially tangent to said radially external laying surface for applying a single strip-like element.