STRIP TRACTION DRIVE MOUNTED IN A THERMO-FORMING DEVICE FOR PRODUCING A BLISTER FILM

摘要

The present invention relates to thermo-forming device comprising a heating and forming device (11, 15) which operates at a given rate. The thermo-forming device also includes an unwinding device for advancing section by section a strip (1) of a thermoplastic material, wherein said unwinding device is located ahead of the heating and forming device. The thermo-forming device further includes an extraction device which is located behind the heating and forming device. In order to provide an even advancement of the strip (1) by the unwinding and extraction devices in the operation area of the heating and forming device and in order to prevent excessive tensile strength on the strip (1) as it moves forward, the extraction device includes an extraction roll (21) which is rotated each time at a given angle, while the unwinding device includes a pre-traction roll (22) which is connected to the drive of the extraction roll (21) by a belt control. A coupling system (32) controlled by photoelectric gates (27, 28, 29) and integrated in the drive system of the pre-traction roll (21) is used for balancing the allowances for the pre-traction of the strip (1).