During building of tires, at least one first forming drum is employed which has a deposition surface and includes sectors radially movable relative to a geometric rotation axis, and circumferentially distributed one after the other. A plurality of strip-like elements is deposited in circumferential side by side relationship on the deposition surface set in the first deposition configuration, to form at least one component of at least one first crown structure. Setting of the deposition surface includes the actions of radially moving the sectors to give the deposition surface a predetermined diameter and carry out a relative movement between a central portion and axially external end portions of each sector to shape the deposition surface according to a predetermined curvature outline.

Disclosed are a two-stage feeding system, a two-stage forming machine, a unistage forming machine and a feeding method, wherein in the two-stage feeding system, the control device firstly controls the laminating drum to operate to a first pre-set position, when the laminating drum moves to a first pre-set position, the control device controls the first belt layer conveying template to move in a direction close to the laminating drum so as to laminate the first belt layer onto the laminating drum, then the control device further controls the movement of the second belt layer conveying template in the direction close to the laminating drum so as to laminate the second belt layer onto the laminating drum; finally, the control device controls the operation of the laminating drum to a second pre-set position, and when the laminating drum operates to the second pre-set position, the control device controls the movement of the tread conveying template in a direction close to the laminating drum so as to laminate the tread onto the laminating drum. In the system, the belt drum is not deformed in the vertical direction due to the large inertia force, thereby effectively improving the bonding quality of the green tire.

A tire building drum has a drum shaft and a circumferential surface for receiving a tire component, wherein the circumferential surface is defined by segments which are radially movable between a contracted position in which the circumferential surface has a first radius and an expanded position in which the circumferential surface has a second, greater radius. The tire building drum includes cover plates, wherein each segment is provided with a first section having a first support surface for supporting the tire component and a second section with a second support surface for supporting the cover plate. Each second section is movable relative to its respective first section from a recessed position in which the second support surface is recessed with respect to first radius and an extended position in which the second support surface is raised towards the second radius.

A tire building drum (10) is used to build a large green tire. The tire building drum (10) comprises: a cylindrical drum main body (12) haying an outer peripheral surface (14) a diameter of which is capable of being increased and reduced; and a coating (16) formed on the outer peripheral surface of the drum main body. The coating (16) includes a silicon layer (26) defining a surface of the coating (16), and the silicon layer has a surface roughness Ra of 10 m or greater. The tire building drum (10) requires no application of stearic acid onto the surface thereof in release of the green tire.

A method for building belt assemblies for tyres for vehicle wheels is described. The method includes building a crossed belt structure on a forming drum. Depending on the type of tyre to be produced, the method selects whether to build a belt assembly having a cylindrical shaping or a belt assembly having a toroidal shaping. In order to build a belt assembly having a cylindrical shaping, a zero degrees belt layer is deposited on the forming drum in a radially outer position with respect to the crossed belt structure. In order to build a belt assembly having a toroidal shaping, the crossed belt structure is picked up from the forming drum. The crossed belt structure is then toroidally shaped and transferred onto another forming drum. A zero degrees belt layer is then deposited on the other forming drum in a radially outer position with respect to the toroidally shaped crossed belt structure.

A process and a plant for producing tyres for vehicle wheels are described. Building of a crown structure of the tyre includes building a crossed belt structure on a substantially cylindrical first forming drum, transferring the crossed belt structure from the first forming drum to an annular holding member, positioning a second forming drum in a radially inner position with respect to the annular holding member, transferring the crossed belt structure from the annular holding member to the second forming drum by radially expanding the second forming drum until it is brought into contact with the crossed belt structure so as to toroidally shape the crossed belt structure, and depositing at least one zero degrees belt layer on the second forming drum in a radially outer position with respect to the toroidally-shaped crossed belt structure.

A plant for producing tyres for vehicle wheels is described. The plant includes a building line configured to build a crown structure. The building line includes a building device configured to build a belt assembly. The building device includes a trolley, a first forming drum, a second forming drum, a first working area including a belt building device, a second working area downstream from the first working area including a depositing device, a first service area downstream from the second working area including a stationary annular holding member, and a second service area downstream from the first service area including a first support member.