Cutter support for underwater granulator for thermoplastics - locks axial movement of cutter shaft as cutter passes extrusion holes to reduce vibration

摘要

An underwater granulator has a removable water chamber attached at the extrusion end of a thermoplastics extruder. A rotating cutter is held aganst the nozzle plate by a shaft which is mounted in a housing so that it can rotate and move axially. Constant pressure is exerted through a hydraulic actuatng cylinder which compensates for the wear of the cutter. A locking mechanism intermittently prevents axial movement of the cutter shaft. A pick-up provides signals which coincide with the cutter blades covering the extrusion holes and thus being exposed to the full extrusion pressure. An auxiliary hydraulic actuating cylinder moves a clamping screw in unison to prevent axial movement during this period. The constant pressure provided by the main cylinder can therefore be of relatively low value so that wear on the cutter is reduced. USE/ADVANTAGE - The invention reduces vibration of the cutter shaft and cutter wear.