Drum and method for assembling a tire adapter on a rim

A radially expandable building drum intended for the manufacture of an adapter for mounting a tire on a rim, the drum comprising a central axis and an assembly zone coaxial with the central axis and comprising a first set of segments and a second set of segments, all the segments being arranged circumferentially around the central axis, and the segments of the first set and the segments of the second set facing one another axially,

• wherein an external circumferential face of each segment comprises a groove for accommodating a bead wire, and
• wherein the drum is produced in such a manner as to pass, in the assembly zone, from a retracted first position of substantially cylindrical shape into an expanded second position of substantially frustoconical shape when the segments of the first set are driven by a first cam and the segments of the second set by an adjacent second cam.

A method of assembly for the manufacture of a tire adapter used for mounting a tire on a wheel rim, comprising the following steps:

• laying rubber components on a cylindrical surface, forming an assembly zone, of a radially expandable drum with a central axis and comprising two sets of segments facing one another axially, by rotating it;
• positioning two bead wires coaxially around the central axis on the rubber components in grooves provided for this purpose in each set of the segments;
• differently radially expanding the segments of the first set in relation to the segments of the second set between two working positions in order to entrap the rubber components around the bead wires by making the segments of the first set collaborate with a first cam and the segments of the second set collaborate with an adjacent second cam.