Measurement and adjustment of pressure applied by plastics granulator blades against perforated plate involves pressure measurement by sensors on blades and variation of blade pressure by control unit

Blades(9) attached to a holder(3) make a rotating or oscillating movement relative to a perforated plate(1) and are pressed against the plate with a prescribed pressure. A pressure sensor(11) on each blade(9) is connected to a control unit which sets the required pressure and/or adjusts the blade position relative to the perforated plate. Each sensor(11) comprises a piezo resistive component, preferably a thin diamond-like carbon layer with piezo resistive properties. Sensors are arranged at the connection between each blade(9) and blade holder(3). preferably mounted directly on a component, a blade or blade holder. Several sensors can be arranged along the blade length. Strain gauges may act as additional sensors on the blades or additional piezo actuators(12) may be incorporated between blade and blade holder. Blades can be adjusted on the holder. An independent claim is included for a method for measuring and adjusting blade pressure against a perforated plate with a wear resistant coating in which: a) the forces between each blade and perforated plate are measured by a piezo resistive type pressure sensor; b) the results are sent to a control unit for comparison with both a set minimum pressure of the blade holder and also a value for the maximum permissible pressure applied onto the plate coating; c) the applied pressure of the blade holder can be varied up or down if required depending on the comparison. Ein mit Messern (9) oder Rackeln bestückter Messerhalter (3) ist mit einem vorgegebenen Anpressdruck gegen eine Lochplatte (1) gedrückt, wobei zwischen der Lochplatte (1) und den Messern (9) oder Rackeln eine Relativbewegung in rotierender oder oszillierender Form erfolgt. Zum Messen und Anpassen des Anpressdruckes der Messer (9) oder Rackeln ist an jedem Messer (9) mindestens ein Drucksensor (11) angeordnet, der mit einem Steuergerät zur Anpassung des Anpressdruckes und/oder zur Anstellung des jeweiligen Messers (9) mit Hilfe von Piezoaktoren (12) gegenüber der Lochplatte (1) verbunden ist.