| 摘要 |
A method for the control of wall thickness of an extruded thermoplastic material. The method includes extruding a thermoplastic material from an extruder through a die gap formed between first and second die lips. One of the die lips has a plurality of separate sectors adjacent the die gap, with each sector having a circulating oil passageway therein. The circulating oil passageways are connected in a series along the die gap. The method includes circulating through each circulating oil passage, within each sector adjacent the die lip, a heat transfer oil from a common source at a selected heating or cooling temperature. The method includes controlling the rate of flow of said heat transfer oil in each sector by an adjustable flow control valve, in order to control the temperature of each sector, and thereby to adjust the viscosity of the thermoplastic material being extruded, and controlling the wall thickness of the extruded thermoplastic material.
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