| 摘要 |
1394343 Pre-heating extrudable material NORDENIA KUNSTSTOFFE PETER MAGER KG 11 July 1973 [17 July 1972] 33124/73 Heading B5A Plastics material 3 contained in the hopper 5 of an extruder 2, extruding a film or sheet 7, is pre-heated by air circulated through the hopper 5 and which comprises cold air mixed with air heated by heat produced from heating elements 4 of the extruder. In the Fig. 1 embodiment, the heated air is drawn by a fan 10 from a hood 8 surrounding the extruder 4, and delivered through the material in the hopper via an inlet 11 and an outlet 12 from which the colder air may then be employed in thermal conditioning of the room containing the extruder. The temperature of the air entering the hopper is maintained constant, e.g. at 60‹ C., by admitting the cold air at a further inlet (not shown) to the fan 10, the quantity of which air is regulated by a throttle flap valve. In the Fig. 2 embodiment (not shown) a water cooling coil (14) extends intermediate the extruder heating elements, and as a coil (16) of a heat exchanger (15) through which air is drawn by a fan (18) to be similarly circulated, with similar provision being made for the admission of cold air to maintain a constant temperature. The amount of air conveyed through the hopper may additionally be regulated by driving the fan at a variable speed, e.g. through a D.C. motor, or a three phase motor with reversible poles. |
