| 摘要 |
1,220,399. Extrusion pelletizers. BAKER PERKINS Inc. 6 Dec., 1968 [6 Dec., 1967], No. 58063/68. Heading B5A. An extrusion pelletizer comprises a barrel B, a shaft S carrying interrupted flight 13, a screw impeller 24 and sleeves 27, 30 which support multi-orificed die head 26, the shaft S rotating and reciprocating during operation together with the impeller, the sleeves and the die head which are attached thereto and a knife assembly 43 mounted for axial movement on shaft 42 and which moves axially with die head 26 against which it is held by spring 48. Assembly 43 is mounted via a resilient sleeve 44, e.g. of hard rubber, on a hollow shaft 42 and is rotated thereby in a direction opposite to that of shaft S. Material to be extruded is kneaded in chamber 11 by the action of flight 13 and teeth 12, the barrel B being appropriately heated or cooled by fluid flow in chambers 11a, 11b, and the material in a plastic or plasticized condition is forwarded by screw 24 to annular channel 31 and thence to orifices 29a, 28a. The issuing strands are cut into pellets by knife assembly 43 and are cooled by water which enters a sleeve 50 via pipes 52, passes through peripheral slots 55 in a disc 49 rotated by shaft 42 and then issues radially as at c due to the action of a fan 56, see also Fig. 5 (not reproduced), mounted on sleeve 44. In this manner the coolant does not contact the die head, but sweeps the pellets around housing 34 towards delivery duct 38. Shaft 42 houses a pilot shaft 62 whose end 68 is maintained in engagement with an orifice 67 in die head 26, for rotation and reciprocation therewith, by means of a spring 69. Shafts 42 and 62 are independently axially adjustable, see Fig. 2 (not reproduced). Knife assembly 43 is described in detail, Figs. 6-8 (not shown), and comprises essentially three blades (77) mounted on a hub (75). Reciprocation of shaft S is by means of a cam mechanism, Fig. 3 (not shown), identical to that described in Specification 1,153,678. Specific materials mentioned are polyethylene, P.V.C., polystyrene and polyurethane.
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