Abstract: The invention relates to a force sensor for measuring a bearing force of a roller deviating a web of material. The force sensor includes a base element on which at least one sensor element is supported. The sensor element has at least one plate which can be elastically deformed by the bearing force and is provided with at least one force transducer. The sensor element is loaded by a pressure piece into which the bearing force is introduced by means of a spring. The spring has a larger range of spring—in the direction of the force—than the elastically deformable plate for the same load. In order to limit the action of the force on the sensor element, an annular abutment is provided, against which the pressure piece can be pressed flat. The abutment is provided around the sensor element.

Abstract: In a method for measuring the tensile stress of a running web, force sensors (7) are connected in the form of a Wheatstone bridge (11). An amplifier (18) amplifies a diagonal voltage (17) of the Wheatstone bridge (11). In order to be able to detect whether at least one of the force sensors (7) is defective, the Wheatstone bridge (11) can be loaded using at least one resistor (26) by means of at least one switch (24, 25). Comparing the measured values, with loading, with the measured values, without loading, determines whether the force sensors (7) of the Wheatstone bridge (11) are functional. Otherwise, an active error signal (28) is output.

Abstract: The invention relates to a force sensor (10) for measuring a bearing force (3) of a roller deviating a web of material. Said force sensor (10) comprises a base element (20) on which at least one sensor element (25) is supported. The sensor element (25) comprises at least one plate (40) which can be elastically deformed by the bearing force (3) and is provided with at least one force transducer (42). The sensor element (25) is loaded by a pressure piece (29) into which the bearing force (3) is introduced by means of a spring (32). Said spring comprises a larger range of spring—in the direction of the force—than the elastically deformable plate (4) for the same load. In order to limit the action of the force on the sensor element (25), an annular abutment (35) is provided, against which the pressure piece (29) can be pressed flat. Said abutment (35) is provided around the sensor element (25).

Abstract: In a method for measuring the tensile stress of a running web, force sensors (7) are connected in the form of a Wheatstone bridge (11). An amplifier (18) amplifies a diagonal voltage (17) of the Wheatstone bridge (11). In order to be able to detect whether at least one of the force sensors (7) is defective, the Wheatstone bridge (11) can be loaded using at least one resistor (26) by means of at least one switch (24, 25). Comparing the measured values, with loading, with the measured values, without loading, determines whether the force sensors (7) of the Wheatstone bridge (11) are functional. Otherwise, an active error signal (28) is output.