Contactless detection of vibrations in metal belts

A measuring assembly in a transport device for a metal belt,

• wherein the measuring assembly is arranged between a front device and a rear device arranged downstream of the front device of the transport device,
• wherein the measuring assembly has a mechanical excitation device by means of which the metal belt is excitable in its thickness direction at an excitation frequency (fA) to produce a mechanical vibration,
• wherein the measuring assembly has a plurality of sensor elements,
• wherein the sensor elements are arranged offset in relation to one another when viewed in the width direction of the metal belt,
• wherein an analog measurement signal (MA) which is characteristic of the amplitude (A) of the excited mechanical vibration of the respective region of the metal belt is detectable in each case by means of the sensor elements for a plurality of regions of the metal belt which are offset in relation to one another in the width direction,
• wherein digitization devices are arranged inside the measuring assembly, by means of which the detected analog measurement signals (MA) are digitized and of which the digitized measurement signals or signals derived therefrom are transmitted as transmitted signals (MA′) to an evaluation device arranged outside the measuring assembly, and
• wherein the sensor elements comprise eddy current sensors, the eddy current sensors of sensor elements that are arranged directly adjacent to one another when viewed in the width direction are operated in each case at one of two or three operating frequencies (f1, f2, f3) which differ from one another, and that the number of sensor elements is greater than the number of operating frequencies (f1, f2, f3) so that, when the sensor elements are viewed as a whole, a plurality of sensor elements are operated in each case at the same operating frequency (f1, f2, f3).