| 摘要 |
An expandible tire-building drum for making toric shaped tire carcasses built in the form of cylindrical sleeves is provided. The cylindrical sleeves have at their extremities, annular bulges which are circumferentially inextensible and are radially developed towards the inside. These bulges form the beads on the carcass. The height of the bead is one-half the difference between the internal diameter of the said sleeve and the internal diameter of the said bead. The drum comprises two co-axial discs, constituted substantially by a hub and an annular flange fixed to the hub, axially slidable reciprocally and fixed with each other in rotation. The said discs are supported on a rotating shaft which projects in cantilever fashion from a driving device. The discs comprise a radially external surface having a first part, capable of receiving the beads of the sleeve, and being defined as "bead-seat". The discs also have an annular co-axial ridge with an external diameter greater than the diameter of the said bead-seat disposed alongside the said seat on the part that is axially inside with respect to the said drum. The drum is characterized by the fact that in the said discs, the radially external surface comprises a second part having a frustoconical form that converges axially outside the drum, coinciding also along its axial inner border, with the axially outer border of the said bead-seat. The annular ridge, projects in cantilever fashion, from the disc axially towards the drum interior, the plane perpendicular to drum axis and tangent to the border axially inside the annular ridge resulting axially innermost of the plane perpendicular to the drum axis and tangent to the axially inner surface of the annular flange. |
