Patent ID: 6235135
Filing Date: 2001-05-22
Classification: B29C,B29D

Abstract:
A process for constructing a green tire on a radially expandable drum including a plurality of metal segments, said metal segments being contractible to a first diameter D0, the drum having a substantially horizontal axis of rotation, and a casing mountable on the metal segments at said first diameter and extending across the metal segments, the casing being formed of an elastic material and having an inner diameter, measured in a relaxed state, at least as great as said first diameter D0, and said drum further includes a plurality of voids coupled to an evacuation pump;the process comprising:bringing the expandable drum to a second diameter D3 measured across the casing whereby the second diameter D3 is greater than the sum D1 of said first diameter D0 plus twice the thickness of said casing,producing a carcass on the drum periphery at second diameter D3, the carcass comprising at least one of sidewalls and an air-tight inner layer, and further comprising at least one carcass ply;generating a vacuum in the voids to suction the carcass onto the drum periphery;radially contracting at least axial end areas of the expandable drum to a third diameter D4 to enable bead cores to traverse the drum periphery without touching the drum periphery;sliding the bead cores over at least the axial end areas of the drum periphery and axially positioning the bead cores over the axial end areas of the drum periphery;radially expanding at least the axial end areas of the radially expandable drum to a fourth diameter D5 sufficient to radially press the carcass against the inner side of the bead cores to provide adequate bonding between an inner surface of the bead cores and an external surface of the carcass, said fourth diameter D5 being substantially the same as the second diameter D3;radially contracting the radially expandable drum to a fifth diameter D6 that is smaller than said second diameter D3 but greater than the sum D1 of said first diameter D0 plus twice the thickness of said casing, andpulling the carcass with set bead cores off the radially expandable drum for further processing in a preshaping device,wherein, upon conclusion of the bead core placement, the carcass is substantially free of internal compressive stress and internal tensile stress.