Shear bar adjustment apparatus including vibration sensor means with adjustable threshold

摘要

Cutting apparatus having an adjustable shear bar (102) cooperable with a rotatable cutter head (100) to cut material passing between the shear bar and cutter head; said apparatus comprising an adjustment mechanism (110, 112, 116, 118, 122) for adjusting the clearance between the shear bar (102) and the cutter head (100) and including motor means (110, 112) operatively coupled to the shear bar (102), vibration sensor means (118) for sensing contact between the shear bar (102) and the cutter head (100) and electrical control means (116) operable to energise the motor means (110, 112) and responsive to the vibration sensor means (118) for automatically adjusting the shear bar (102) relative to the cutter head (100); said cutting apparatus being characterised in that the control means (116) comprises means for adapting the threshold of the vibration sensor means (118) in accordance with the level of background noise resulting from normal operation of the apparatus so that vibrations in the shear bar (102) resulting from contact between the shear bar (102) and the rotating cutter head (100) are distinguished from vibrations resulting from said background noise. <IMAGE>