| 摘要 |
1,225,417. Extruding thermoplastics sections. VERENIGD PLASTIC VERKOOPKANTOR N.V. 8 July, 1968 [8 July, 1967], No. 32554/68. Heading B5A. In the extrusion of thermoplastic polymeric solid sections, the extrudate from extrusion nozzle 1 passes through an air gap before entering a cooled sizing die 3 having a converging inlet passageway 4, the arrangement being such that extrudate accumulates as a cavity-free mass in the air gap prior to being drawn through die 3 by take-off rollers 8. As shown, extrusion orifice 2 is circular in cross-section whereas the product 9 is of I cross-section. However, if the product is considerably elongated, orifice 2 may be elongated in the same sense. Die 3 is cooled by liquid, e.g. water, from a spray ring 6. The preferred length of the air gap is between 1 and 5 inches and the crosssectional area of the accumulated material is at least 1À5 times and preferably at least 6 times that of orifice 2. Specific polymers mentioned are PVC, polystyrene, polyethylene, polyaminocaproic acid and polyethylene terephthalate. |
