| 摘要 |
<PICT:0783723/III/1> A synthetic plastic material, e.g. polymethyl methacrylate, nylon, cellulose acetate or polystyrene is extruded through a die 14 as a sheet, rod or tube and during passage through a heated extrusion chamber 1 a volatile component, e.g. a solvent or an impurity (water vapour), is removed by suction through a port 8 and passage 9 in the extrusion screw 2. The screw comprises four sections:-a feed section A, a metering section B having a large root diameter 6, an extraction section C in which the port 8 is located and the conveying capacity of the section is suddenly increased, and an extrusion section D which forces the material through the die 14. The section C is so arranged that it is not completely filled with material and thus the port 8 does not get blocked with material. The pitch may vary instead of being constant, as shown, and the barrel may have two screws which may or may not intermesh.ALSO:A synthetic plastic material, e.g. polymethyl methacrylate, nylon, cellulose acetate or polystyrene is extruded through a die 14 as a sheet, rod or tube and during passage through a heated extrusion chamber 1 a volatile component, e.g a solvent or an impurity (water vapour), is removed by suction through a port 8 and passage 9 in the extrusion screw 2. The screw comprises four sections:-a feed section A, a metering section B having a large root diameter 6, an extraction section C in which the port 8 is located and the conveying capacity of the section is suddenly increased, and an extrusion section D which forces the material through the die 14. The section C is so arranged that it is not completely filled with material and thus the port 8 does not get blocked with material. The <PICT:0783723/IV (a)/1> pitch may vary instead of being constant as shown, and the barrel may have two screws which may or may not intermesh.
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