Patent ID: 7722518

Claim:
A device for producing a yarn bobbin tube made of cardboard and having a beaded end formed as an interior hollow roll comprising: a cup-shaped rotatory die having a recess forming a perimetric wall and a base, an interior face of the perimetric wall having a stepped profile with diameters increasing from said base to a die mouth, a diameter of said die mouth being slightly larger than an exterior of the cardboard tube provided with the interior roll; a shaft mounted to said base of said die; means disposed in an interior of said die for exerting pressure on said interior roll by applying, radially and centrifugally, a force in a continual sequential manner with increasing intensity that traverses point by point along an inner circumference of said interior roll so as to successively transform said interior roll into an entrant perimetric step, wherein the means for exerting pressure on the roll of the cardboard tube comprise a roller mounted off-centre to the shaft in a freely rotating manner and arranged so that the distance between a lateral surface of the roller and an interior area of lesser diameter of the perimetric wall of said rotatory die is of a magnitude no more than double a thickness of the cardboard tube provided with the interior roll.