APPARATUS FOR DYNAMICALLY COOLING AND PUMPING MOLTEN THERMOPLASTIC MATERIAL

摘要

A dynamic cooler apparatus is provided for dynamically cooling molten plastic extrudate while pumping metered amounts of that extrudate to an extrusion die or the like. The dynamic cooler apparatus utilizes bi-helical gears in a gear pump configuration in a housing in which a heat exchange medium is circulated. The heat exchange medium is also circulated internally of the gears so that the gear teeth and the housing act to cool discrete volumes of extrudate from four sides defined by the gear teeth and the internal surface of the housing. The bi-helical gears are driven to minimize loading between the teeth thereof and to permit the teeth to be as small as practical to present more cooling surface for a given cross-section of extrudate and optimize the heat transfer capability of the dynamic cooler apparatus. Provision is also made to use the molten extrudate as a lubricant for the shafts and bearings of the bi-helical gears.