Process for production of a bobbin tube for yarn, device for embodiment of such process, bobbin tube obtained and mode of utilisation of said bobbin tube

摘要

A cardboard tube, with respect to a narrow marginal end area of the same provided with a hollow interior roll, is applied against a rotatory die which has a concave surface suitable for forming an entrant perimetric step by means of constriction of the narrow marginal area. The diameter of the riser thereof is equal to the interior diameter of the cardboard tube. At the same time, against the interior hollow roll is applied a force of enough intensity to flatten the cavity of the interior hollow roll and apply the wall thereof against the interior face of the wall of the cantilevered end of the cardboard tube formed by the action of its rotatory die.