Process and apparatus for manufacturing tyres

摘要

A plurality of strip-like elements is applied onto a forming drum externally having a substantially cylindrical laying surface. The strip-like elements are disposed in mutually approached relationship to form at least one first annular reinforcing layer on the forming drum itself set to a first work diameter at which each of the applied strip-like elements on the laying surface subtends an arc of a circumference of a width as large as a submultiple integer of the overall circumferential extension of the laying surface itself. Adjustment devices operating on the forming drum subsequently carry out expansion of the latter to a second work diameter larger than the first work diameter, while maintaining its laying surface substantially cylindrical.

主权项

1. A process for producing tyres wherein building of each tyre comprises:
separately manufacturing a carcass structure and a belt structure, wherein manufacture of said belt structure comprises the steps of:
providing a forming drum externally having a substantially cylindrical laying surface; andapplying a plurality of strip-like elements on the forming drum,wherein during said applying step the strip-like elements are laid in mutually approached relationship according to the circumferential extension of said laying surface, to form at least one first belt layer;wherein before the applying step, the forming drum is set to a first work diameter, at a value such that each of the strip-like elements applied thereto, on the laying surface, subtends an arc of a circumference of a width corresponding to a submultiple integer of the overall circumferential extension of the laying surface;further comprising a step of making at least one second belt layer at a radially external position to said first belt layer, wherein the second belt layer comprises strip-like elements laid in mutually approached relationship;wherein after said applying step and after formation of said at least one second belt layer, the forming drum is radially expanded while keeping the laying surface thereof at a substantially cylindrical shape, up to a predetermined second work diameter, to determine a permanent expansion of said first and second belt layers; andwherein a difference between the circumferential extension of the forming drum set to the first work diameter and the circumferential extension of the forming drum set to the second work diameter is smaller than a width of each strip-like element.