METHOD AND DEVICE FOR DETECTING FAULTS AFFECTING ROTATING BLADES USING ACOUSTIC EMISSION

摘要

The present invention relates to a method and apparatus for detecting errors on rotating knives. In the method, the room sound generated by a rotating blade (3a, 3b, 3c, 3d) is picked up by a microphone (1), which has a spatial distance from the rotating blade, forwarded and passed through a signal conditioning unit (6) and a data acquisition unit (7) processed, converted into digital signals and processed in a data processing unit (13), wherein a threshold value for the sound pressure of a respective blade circulation is determined and each individual amplitude signal of the following on a knife circulation (M_i) subsequent blade rotation (M_i + 1) with the threshold value (SW_i) of the last artefact-free knife revolution (M_i) is compared, whereupon a defect indication is triggered if, in at least three successive knife revolutions (M_i + 1 to M_i + 3) periodically at the same position in the knife circulation recurring amplitude signals, each above the threshold value of last artefact-free knife circulation lie occur.