Device for shaping a pneumatic tire comprising a conditional assistance system for the rotation of the flanges carrying the beads of the tire

A device for shaping a tire, comprising a first flange intended to receive a first bead of a tire;

• a second flange intended to receive a second bead of said tire;
• a translation mechanism allowing movement of at least one of the first flange and the second flange in translation along a common central axis in order to modify a center distance which axially separates the first flange from the second flange, so that the flanges can be brought axially closer together and hence the beads closer together, to accompany a radial expansion of the tire;
• a rotation mechanism which allows rotation of at least one of the first flange and the second flange around the central axis so as to allow modification of an angular difference which is the relative azimuthal angular position of the first flange relative to the second flange;
• wherein said device comprises a control system configured to apply a control law which comprises a conditional assistance mode in which i) over a first application region, the control law associates with each center distance value of a permitted region a range of permitted angular differences, which has a predetermined amplitude delimited by a low boundary and a high boundary separate from the low boundary;
• and in which ii) when a mutual axial convergence of the flanges is performed and the center distance thus passes through the first application region, the rotation mechanism remains passive if the angular difference lies inside the permitted region, so as to allow the first flange and the second flange to rotate freely relative to one another under the effect of a natural reaction of the tire to the radial expansion of said tire and to the mutual axial convergence of said flanges, and said rotation mechanism selectively triggers an assistance with rotation if the angular difference reaches one of the boundaries of the permitted region or leaves said permitted region, in order to actively manage the relative rotation of the flanges so as to force the angular difference to remain in or return within said permitted region, wherein the control law is realized as a mechanical guide comprising a guide groove holding by engagement a finger fixed to one of the flanges, side edges of which guide groove form, against said finger, guide profiles allowing an axial movement of said finger on modifications of the center distance while forming the boundaries of the permitted region in azimuth around the center axis, so as firstly to offer said finger and hence the corresponding flange, in each of the axial positions of said finger and hence of said flange, an angular displacement which corresponds to the amplitude of the permitted region for the axial position concerned, and secondly to retain said finger within the permitted region by forming circumferential stops against the azimuthal rotation of the finger and hence of the corresponding flange when said finger reaches an azimuthal position which corresponds to one of the boundaries of said permitted region.