| 摘要 |
<p>1527235 Extruding multilayer parisons for blow moulding TOPPAN PRINTING CO Ltd 3 Sept 1975 [12 Aug 1975] 36349/75 Heading B5A A die head for extruding multilayer parisons comprises a core holder 30 having a die core 9 at one end, a hollow mandrel surrounding the core holder, a series of axially aligned sleeves 14, 19, 24 surrounding the mandrel, and a housing 16 surrounding the sleeves and having molten resin inlets 11, 12, 13 connected to respective passages 15, 20, 25 which are formed between the sleeves and the mandrel and which change the direction of flow three times before leading to a common extrusion orifice 28 formed between the core pin 9 and a surrounding die 8, the flow of resin in the passages 15, 20, 25 being controlled adjustable rings 17, 21. The cross head die is mounted to a main extruder which extrudes an inner layer of modified polyethylene or polypropylene, and subsidiary extruders are connected at angles of 25 to 90 degrees to form an outer layer, e.g. of nylon. Alternatively the flow from the main extruder may be divided to feed inlets for both the inner and outer layers. The thickness of the parison is modified by moving the core pin 9 within the die under the control of an electronic programmer.</p> |
