Thread-guide device for the production of bobbins with traversing modulation

A thread-guide device (14) for the collection of yarns on a bobbin (10), wherein the yarn (F) is distributed on the surface of the bobbin by a thread-guide (12) which moves with a back-and-forth movement parallel to the axis of the rotating roll (11) in contact with the bobbin (10), and the thread-guide device (14) is driven with a back-and-forth movement by means of a flexible element (15), to which the thread-guide (12) is fixed, the flexible element (15) being moved by two pulleys (16a, 16b) which move with an alternating clockwise/anticlockwise movement by the activation of an electric motor piloted in frequency, characterized in that

• the flexible element (15) is an open flexible element;
• both of the pulleys (16a, 16b) are driving pulleys activated by at least one electric motor (17a, 17b) for each pulley, each motor being controlled by means of respective position detectors and piloted by a control unit, which coordinates the piloting of said motors (17a, 17b) to produce the desired transversing movement;
• the ends of the open flexible element (15) are wound onto the two driving pulleys (16a, 16b), to which they are physically fixed with a constraint (26a, 26b);
• the driving pulleys (16a, 16b) are connected with elastic elements (18a, 18b;
• 22a, 22b;
• 38a, 38b), which tend to rotate them in the opposite direction to each other, bringing the thread-guide (12) to its own part and providing, for each run of said thread-guide (12), in addition to the torque exerted by the motors (17a, 17b), also the difference in elastic energy accumulated by the elastic elements (18a, 18b;
• 22a, 22b;
• 38a, 38b) in the previous run.