| 摘要 |
This invention relates to a method of and apparatus for manufacturing an extrudate of high temperature thermoplastic material (e.g. vitreous silica). In simplest form the method comprises delivering the thermoplastic material in plastic state to an extrusion die by means of a pump, the pump output and the dimensions of the die being chosen so that the die contains and supports the thermoplastic material throughout its plastic range. Conveniently the apparatus comprises a reciprocating pump submerged in a reservoir of the thermoplastic material in plastic condition, the inlet side of the pump being arranged to take in plastic material directly from the reservoir and the pump outlet being connected directly to an extrusion die in a wall of the reservoir.
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