Device for the preforming and transfer of a banderole in a container thermoforming installation

In a device for the pre-forming and transfer of a banderole in a container thermoforming installation which comprises a molding unit equipped with a plurality of vertical cylindrical forming chambers, open at their top part and having at their lower part an opening adapted to be closed by a bottom element movable with respect to the molding unit, in such a way as to be capped over by the corresponding molding chamber which is movable with said molding unit between a high position, called thermoforming position and a low position called container stripping position, the improvement comprising:

• a master-band supporting roller mounted in fixed bearings,
• a cutting unit for cutting the master-band longitudinally into individual bands, which unit is mounted on a first supporting table remote laterally from the molding unit,
• at least one guiding roller of adjustable position for every individual band,
• a pre-winding unit for pre-winding the banderoles, which unit is placed under the molding unit which rests on it, and is mounted on a second supporting table which is vertically movable between a position corresponding to the thermoforming position and a position corresponding to the stripping position of the molding unit, said pre-winding unit comprising a plurality of vertical cylindrical pre-winding chambers, each one in alignment with one of the forming chambers, so that the vertical wall of the pre-winding chamber defines an outline which is homothetic to that of the forming chamber, yet slightly smaller than the outline of the latter, so as to constitute with its upper edge, an annular holding shoulder member which also defines the bottom opening of the forming chamber,
• a banderole introduction and cutting unit for every pre-winding chamber, of which part of the vertical side wall is constituted by the inner face of a support-plate of the introduction and cutting unit which further comprises a vertical access slot provided in said support-plate and issuing obliquely into the pre-winding chamber, a cutter adapted to cooperate with a counter-blade for cutting the back end of the banderole introduced at least partly into the pre-winding chamber, and one pair of introduction rollers placed upstream of the cutter and of said slot and adapted to pinch the individual band and to drive same at a pace equal to the length of one banderole,
• a shaping member comprising a rod which traverses the pre-winding chamber and forms with the vertical wall thereof a narrow annular pre-winding and guiding chamber, and of which the upper part, on the one hand, constitutes at least part of the bottom plate and has a cross-section of similar but smaller shape than that of the vertical wall of the forming chamber, so that the distance between the vertical wall of the forming chamber and the peripheral face of the upper end of the shaping member is at least equal to the thickness of a banderole, and on the other hand, is adapted to penetrate into the forming chamber and to apply said banderole and keep it applied against the vertical side wall of said forming chamber, and
• transfer means provided in the pre-winding and guiding chamber, and adapted to support said banderole until this has been transferred to the forming chamber by a relative movement between said transfer means and said forming chamber, device wherein:
• the shaping member and the transfer member are joined together, and the distance between the upper end of the shaping member and the transfer member is, on the one hand, at least equal to the axial distance between the bottom of the access slot and the central part of the forming chamber and, on the other hand, less than the distance between the upper end of the forming chamber in thermoforming position and the lower end of said forming chamber in stripping position;
• the assembly of the elements constituting the banderole introduction and cutting unit is joined to the pre-winding unit by means of the support-plate and is permanently associated with the access slot of the pre-winding chamber;
• the first supporting table of the unit for longitudinally cutting the master-band into individual bands is mounted for moving synchronous with the vertical displacements of the second supporting table of the pre-winding unit and the molding unit, and
• a tension roller is provided on the path of the master-band between its supporting roller and the longitudinal cutting unit, said tension roller being applied against the master-band so as to compensate the length variations of the unrolled portion of the master-band which are due to the displacements of the longitudinal cutting unit during the vertical displacement of the banderole pre-winding unit.