Process and drum for constructing a green tire

Abstract

Process and drum for constructing a green tire on a radially expandable drum having a substantially horizontal axis of rotation. The process includes collapsing the radially expandable drum at a minimum first diameter, and positioning a casing on the radially expandable drum to form a drum periphery being composed of an elastic material, and having an inner diameter at least as great as the first diameter, and including a plurality of voids coupled to an evacuating pump. The radially expandable drum is radially expanded from the first diameter to a second diameter greater than the first diameter to expand the casing, and producing a carcass, having at least one carcass ply with at least one of sidewalls and an air-tight inner layer, on the drum. A vacuum is produced in the voids to suction the carcass onto the drum periphery and at least axial end areas of the expandable drum are radially compressed to a third diameter to enable bead cores to traverse the drum periphery without touching the drum periphery. The bead cores are slid over at least the axial end areas of the drum periphery and are axially positioned over the axial end areas of the drum periphery, which are radially expanded at least the axial end areas of the radially expandable drum to a fourth diameter sufficient to radially compress the bead cores and the carcass against each other, providing adequate bonding between a bead core inner surface and a carcass external surface. The fourth diameter is substantially the same as the second diameter, the radially expandable drum is radially compressed to a fifth diameter between the first and second diameters, and the carcass with set bead cores is pulled off the radially expandable drum for further processing in a preshaping device. Upon conclusion of the bead core placement, the carcass is substantially free of compressive stress and tensile stress.