| 摘要 |
<p>1,181,075. Moving band filter. P. G. KALMAN. 21 Feb., 1967, No. 8122/67. Heading B1D. [Also in Divisions B4 and B5] A movable filtering ribbon 1, of woven stainless steel or Nichrome (T.M.) extends directly or obliquely across passage 16, which carries molten rubber or plastics from the screw to the die of an extruder, some of the rubber/plastics being maintained in a solid or plastic state in ribbon entry and exit slots 14, 15 extending through ports 3, 4 which have electric/hot fluid heaters 6, 7, 10, 11 and coolant passages 8, 9, 12, 13 whereby their temperatures are controlled. Ribbon 1 is moved intermittently or continuously across the passage, impurities being removed as a coating 22 on the ribbon. For intermittent movement, ports 3, 4 are normally cooled to keep the plugs of material in slots 14, 15 solid, and periodically, under control of a timer or pressure switch, either ports 3, 4 are heated or electricity is passed through ribbon 1 itself to melt the plugs. The pressure in passage 16 then extrudes material and ribbon from slot 15 by virtue of its larger crosssection. Alternatively, ports 3, 4 are held at intermediate temperature, material extrudes through both and the ribbon advances continuously (0.42 inch per hour). Ribbon movement may be effected or assisted by a pneumatic ram-operated toggle device on the exit side (Fig. 11, not shown) and retarded by braked rollers on the entry side (Fig. 12, not shown). Instead of or in addition to controlling movement by temperature, the exit slots may be variable in width or partly obturated by grubscrews (Figs. 7, 8, 9, not shown). The exit port may comprise several individually cooled/heated sections (Fig. 4, not shown), and its slot 15 may be tapered, parallel sided or curved (Fig. 10, not shown). In Fig. 13 (not shown), some molten plastics from passage 16 is bled through passages (75, 76) to act on the solid plug in an outer, widened part of the exit slot. In Fig. 5 (not shown), the exit port comprises alternate metal fins and ceramic spacers, for cooling by natural or forced convection. Where it crosses passage 16, ribbon 1 is backed by a disc 17, formed as a grating by two sets of slots cut into opposite faces and intersecting. Ribbon 1 may be an endless band, cleaned by melting or solvent action.</p> |
