SHREDDING MACHINE

摘要

A shredding machine for domestic or office use having a feed passage 3 leading to a cutting mechanism 10, 11 powered by an electric motor, has a thickness measuring device 15 for measuring the thickness of bundles of paper fed through the feed passage and the machine is controlled by a microprocessor which receives signals from the thickness measuring device and prevents the cutting mechanism from being energised if the thickness measured is above a threshold determined by the microprocessor. The microprocessor varies the threshold in accordance with electrical supply voltage, the electric motor temperature and the electric current drawn by the motor during a previous shredding operation, so that the maximum thickness the shredder will accept can be reduced automatically when motor temperature increases or as the effectiveness of the machine deteriorates throughout its working life.

主权项

1. A shredding machine for shredding sheet material, the machine comprising a feed aperture and a cutting mechanism powered by an electric motor, the feed aperture being arranged to receive sheets for shredding and to direct such sheets to the cutting mechanism for shredding, the machine having a detector for detecting the thickness of sheet material passed into said feed aperture for shredding which sheet material may comprise a plurality of superimposed sheets which together provide such thickness, said detector controlling said cutting mechanism so as to permit energisation of the cutting mechanism where the thickness of sheet material measured thereby is below a controlling threshold and to prevent such energisation where the thickness of sheet material measured is above said controlling threshold, characterised in that the machine includes at least one sensor sensing a variable motor performance parameter relevant to such shredding and a controller operable to adjust said controlling threshold automatically in dependence upon the value of the motor performance parameter sensed.