Process for building tyres and tyre obtained thereby

A process for building a tyre comprising:

• forming a carcass structure comprising at least one carcass ply having end flaps in engagement with respective annular anchoring structures;
• forming a belt structure comprising at least one first belt layer;
• and
• after forming the carcass structure and forming the belt structure, associating said belt structure with said carcass structure,
• wherein forming said carcass structure comprises at least:
• forming at least one carcass ply around a building drum;
• associating a pair of annular anchoring structures with said at least one carcass ply;
• and
• applying sidewall portions on said at least one carcass ply;
• wherein forming said belt structure comprises at least:
• providing an auxiliary drum having a central axis and a radially external laying surface of substantially cylindrical conformation around the central axis;
• circumferentially applying a pair of annular inserts of raw elastomeric material, axially spaced apart from each other, onto said laying surface, wherein said annular inserts each have an axially external end edge and an axially internal end edge lying against said laying surface;
• and
• applying a plurality of strip-like elements onto said laying surface of the auxiliary drum, which strip like elements are disposed in parallel side-by-side relationship with each other in the circumferential extension of said laying surface, so as to form said at least one first belt layer,
• wherein during applying of strip-like elements, the external surfaces of said pair of annular inserts radially exceed the laying surface of the auxiliary drum between the pair of annular inserts, and respectively opposite end portions of each strip-like element are radially superposed, each against one of the annular inserts, in such a manner that each strip-like element has respective axially external end edges at an axially internal position relative to axially external ends of said annular inserts applied on said laying surface;
• and
• wherein said step of associating said belt structure with said carcass structure is carried out by shaping the carcass structure from a cylindrical shape into a toroidal conformation in such a manner that radially external ends of said sidewall portions become joined to the axially external ends of said annular inserts;
• wherein the annular inserts define radially external apices of the sidewalls, and the elastomeric material of the annular inserts has a hardness greater than the hardness of the sidewall portions applied against said at least one carcass ply.

A process for building a tyre comprising:

• forming a carcass structure comprising at least one carcass ply having end flaps in engagement with respective annular anchoring structures;
• forming a belt structure comprising at least one first belt layer;
• and
• after forming the carcass structure and forming the belt structure, associating said belt structure with said carcass structure,
• wherein forming said carcass structure comprises at least:
• forming at least one carcass ply around a building drum;
• associating a pair of annular anchoring structures with said at least one carcass ply;
• and
• applying sidewall portions on said at least one carcass ply;
• wherein forming said belt structure comprises at least:
• providing an auxiliary drum having a central axis and a radially external laying surface of substantially cylindrical conformation around the central axis;
• circumferentially applying a pair of annular inserts of raw elastomeric material, axially spaced apart from each other, onto said laying surface, wherein said annular inserts each have an axially external end edge and an axially internal end edge lying against said laying surface, wherein during circumferentially applying annular inserts, the auxiliary drum is set to a minimum diameter;
• after circumferentially applying annular inserts, expanding the auxiliary drum from the minimum diameter to a first work diameter for applying strip-like elements;
• and
• applying a plurality of strip-like elements onto said laying surface of the auxiliary drum, which strip like elements are disposed in parallel side-by-side relationship with each other in the circumferential extension of said laying surface, so as to form said at least one first belt layer,
• wherein during applying of strip-like elements, the external surfaces of said pair of annular inserts radially exceed the laying surface of the auxiliary drum between the pair of annular inserts, and respectively opposite end portions of each strip-like element are radially superposed, each against one of the annular inserts, in such a manner that each strip-like element has respective axially external end edges at an axially internal position relative to axially external ends of said annular inserts applied on said laying surface;
• and
• wherein said step of associating said belt structure with said carcass structure is carried out by shaping the carcass structure from a cylindrical shape into a toroidal conformation in such a manner that radially external ends of said sidewall portions become joined to the axially external ends of said annular inserts.