Cutting sharpness detection device

A detection arrangement for detecting a wear status of a chopping knife arrangement of a chopping device provided for processing a product flow, wherein the chopping device has a revolving chopping drum receiving the chopping knife arrangement and at least one shear bar which cooperates with chopping knives of the chopping knife arrangement, wherein the detection arrangement comprises:

• at least one sensor arrangement which has a magnetic exciter arrangement and a flux conducting device magnetically coupled thereto, wherein the sensor arrangement provides a pole arrangement which forms at least one magnetic pole with a pole surface for conducting magnetic flux, wherein the sensor arrangement is configured such that at least a portion of the chopping knife passes the pole arrangement during a rotation of the chopping drum, the chopping knife passing the pole arrangement forms an air gap arrangement with at least one air gap with respect to the pole arrangement, and at least one magnetic circuit excited by the exciter arrangement is accordingly closed via the respective chopping knife,
• a measuring arrangement, and an evaluating unit, wherein the measuring arrangement is configured to detect at least one measured magnetic value pertaining to the magnetic flux in at least one magnetic circuit excited by the exciter arrangement, wherein voltage induced when a chopping knife arrangement passes the sensor arrangement forms the measured magnetic value, and
• wherein the evaluating unit is configured to determine the wear status of the respective chopping knife from the at least one detected measured magnetic value by
• determining the induced voltage and recording the induced voltage as a voltage signal,
• resolving the voltage signal into its frequency components by means of frequency analysis,
• separating the frequency components into frequency components of a fundamental oscillation and into frequency components of a superposed oscillation which cause signal distortion,
• inverse-transforming the separated frequency components of the superposed oscillation which cause a signal distortion in a time domain, and
• deriving a measurement for the wear status or cutting sharpness of the chopping knife from the inverse-transformed frequency components of the superposed oscillation.