Abstract: A device for measuring a stretching force on a film, including an unwinding station to hold and unwind a spool of stretch film via an unwinding motor, and including a first stretching station with a first driven stretch roller and a second driven stretch roller for imparting a predetermined first stretch to the stretch film. The device includes a second stretching station with a third driven stretch roller for imparting a second predetermined stretch to the stretch film. A sensor is provided in the unwinding station in order to measure a release parameter indicative of where the stretch film releases from the spool. A processor is provided to calculate a first and second force, needed to obtain respectively the first stretch and second stretch, on the basis of the release parameter and an output of the first, second, third torque meters and the unwinding torque meter.

Abstract: A method and device for determining tensile force and adhesive force during the unwinding of a film from a roll without affecting the film, and which are usable at any radius of the spool and at any unwinding speed. The method and the device are based on determining the point where the film releases from the spool, and make use of the reflection of an ultrasonic wave. Emitted and reflected waves are radial at least when the emitted wave is incident upon the film which has not released from the spool. The method and device find applicability where tensile force, caused by the resistance of the roll to rotation, and also by adhesion of the film to the roll, must be determined. The method and device also find applicability where the adhesive force of the film to the roll must be determined.

Abstract: A method and device for determining tensile force and adhesive force during the unwinding of a film from a roll without affecting the film, and which are usable at any radius of the spool and at any unwinding speed. The method and the device are based on determining the point where the film releases from the spool, and make use of the reflection of an ultrasonic wave. Emitted and reflected waves are radial at least when the emitted wave is incident upon the film which has not released from the spool. The method and device find applicability where tensile force, caused by the resistance of the roll to rotation, and also by adhesion of the film to the roll, must be determined. The method and device also find applicability where the adhesive force of the film to the roll must be determined.