Patent ID: 7160236
Filing Date: 2007-01-09
Classification: B31F,B65H

Abstract:
1. Process for producing a yarn bobbin tube, more particularly a cylindrical cardboard tube which, being one of such as is designed for storage, transport and handling of yarn wound into reels, allow one tube by means of a given end thereof to be coupled in linear succession by light fitting together in the opposite end of another analogous tube, comprising: preparing a cardboard tube, of a length which is suitable for the size of the bobbin tube to be obtained; securing said cardboard tube so that it has a cantilevered free end part, said free end part of the cardboard tube being beaded to form an interior hollow roll having a substantially toric configuration, applying the cardboard tube, which is provided at its cantilevered end with an interior hollow roll and has, firstly, a narrow marginal area thereof, situated in the exterior face of the wall of said cantilevered end opposite said interior hollow roll, against a rotatory die that has a concave operative surface, which is defined by a progressive former adopting the negative form of the profile of an entrant perimetric step; forming an entrant step in the cardboard tube by constriction of said narrow marginal area, the diameter of a riser thereof being of equal or lesser magnitude than that of the interior diameter of said cardboard tube; and simultaneously and radially with respect to the straight section of said cardboard tube, applying a force of enough intensity interiorly against said interior hollow roll to flatten the cavity thereof and apply the wall thereof against the interior face of the wall of the cantilevered end of the cardboard tube which is formed by the action of said rotatory die.