| 摘要 |
1,156,402. Screw extruders. LABORAZIONE MATERIE PLASTICHE S.p.A. 8 Nov., 1966 [13 Nov., 1965], No. 49901/66. Heading B5A. A screw extruder for use with plastics, in particular thermoplastics such as P.V.C. and polypropylene, comprises a screw impeller 10 whose conical downstream end P and at least its terminal thread Sn are cooled by flow of coolant through axial conduit 21, chamber 19 and chamber 18, turn Sn and possibly the two adjacent upstream turns being provided with at least three notches 30 to prevent the formation of a boundary layer between cool and not so cool plastics material. The coolant, which may be a mineral oil, leaves chamber 18 via a series of orifices 23 in a casing 17 and flows upstream through an annular chamber 22. The thread from turn S1 upstream, i.e. upstream of metering section GS is not cooled directly and an insulating sleeve 25 is provided between these turns and chamber 22. The geometrical relationships between turn Sn, notches 30 and conical end P are described, Figs. 2 and 3 (not shown). |
