| CPC B29D 30/247 (2013.01) [B29D 2030/3214 (2013.01)] | 10 Claims |
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1. A drum for manufacturing a tire, the drum comprising at least one annular bead wire, the drum having a central axis and being provided with a clamping device which comprises a shaft fitted along the central axis, the shaft bearing a plurality of clamping jaws which are distributed in several angular sectors about the central axis and which are placed under the control of a deployment system which makes it possible to modify a radial distance of the clamping jaws with respect to the central axis such that the clamping jaws define an expandable seat that the deployment system moves alternately from a retracted configuration, in which the expandable seat occupies a first diameter, the first diameter being a resting diameter, which is less than an inside diameter of the bead wire, to a deployed configuration, in which the clamping jaws are radially further away from the central axis than in the retracted configuration, such that the expandable seat extends over a second diameter, the second diameter being a clamping diameter, which is greater than the resting diameter and which allows the expandable seat to engage against the inside diameter of the bead wire and to exert a centrifugal clamping force on the bead wire,
wherein the deployment system comprises an articulated parallelogram, the four apexes of which respectively form a first, a second, a third and a fourth pivot, the first pivot and the second pivot being secured to the shaft and positioned respectively at a first radial distance from the central axis and at a second radial distance from the central axis, greater than the first radial distance, so as to define a first base, the first base being a fixed base of the articulated parallelogram which extends transversely to the central axis, while the third pivot and the fourth pivot are secured to a clamping jaw and define a second base, the second base being a mobile base of the articulated parallelogram, which is kept parallel to the fixed base by a first arm which connects the first pivot to the third pivot so as to define a first side of the articulated parallelogram, and by a second arm which connects the second pivot to the fourth pivot so as to define a second side of the articulated parallelogram, parallel to the first side,
wherein the deployment system comprises a drive mechanism designed to cooperate with the articulated parallelogram so that it is possible to select and modify the radial position of the mobile base with respect to the fixed base in order to pass from the retracted configuration to the deployed configuration and vice versa, and
wherein the drive mechanism of the deployment system comprises:
a slider which is guided on the shaft so as to be able to move, under control of a driving member, at least along an axial movement component that is parallel to the central axis;
a pusher which is secured to the mobile base of the articulated parallelogram and which has, with respect to the slider and to the central axis, a convex curved ramp; and
a connecting shoe which is carried by the slider, which has a concave cradle with which the ramp of the pusher cooperates in sliding contact, and which is mounted on the slider in a tilting manner by means of a pitch pivot so as to be able to adapt its inclination with respect to the central axis depending on a position of the connecting shoe along the ramp of the pusher,
such that a movement of the slider on the shaft along the central axis is converted by the sliding of the connecting shoe on the ramp of the pusher into a variation in the radial distance of the pusher from the central axis, and therefore into a corresponding variation in the radial distance of the mobile base of the parallelogram with respect to the central axis.
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