| 摘要 |
1,109,447. Plasticization units for extrusion machines. PHILIPS PETROLEUM CO. 30 July, 1965 [13 Aug., 1964 (2)], No. 32838/65. Heading B5A. A " dynamic " or " impulse " extrusion machine which may be used to produce elongated hollow or solid sections of synthetic thermoplastic material, or to coat cores with such material, comprises a reciprocable single or two-part ram (14), Fig. 1 (not shown), a plasticization unit (13), an extended die (11) and an after-treatment, e.g. cooling, section (27). The plasticization unit (13) comprises a mandrel 33, Fig. 2, provided with rings of teeth 34 which slope in a downstream direction with the teeth of a downstream ring being more numerous and generally projecting further radially than those of a ring upstream thereof. As shown, the rings are grouped as at A, B and C and the variations in the teeth are shown at 34A, 34B and 34C, Fig. 4. The upstream end 42, Fig. 2, of mandrel 33 forms a flow control mandrel by being tapered and defining an annular gap 41 with barrel 31 which decreases in cross-section in the downstream direction. However, end 42 is grooved in such a manner, Fig. 4, that the flow-path cross-section increases in the downstream direction. Lands 43 between the grooves are a sufficiently close fit within barrel 31 to prevent displacement of end 42 therein. Mandrel 33, Fig. 2, is provided with heaters 37 operated electrically or by fluid, or are of the dielectric type, and further heaters may be placed in or on barrel 31. The feed system for the starting material includes a proportioning device (24), Fig. 1 (not shown), and die (11) may incorporate a sizing device. Specific materials mentioned are nylon, polyvinyl acetate, polyvinyl chloride, polyethylene and polypropylene.
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