| 摘要 |
978,001. Extrusion machines. NATIONAL RUBBER MACHINERY CO. July 6, 1962 [Nov. 13, 1961], No. 26028/62. Heading B5A. A breaker plate assembly 25 located between an extruder screw 4 and a die 6 is provided with a rotary valve device 43 comprising a flattened nozzle 47 adapted to register with a limited number of the breaker plate apertures to permit a reverse flow of material through the latter to remove plugs therefrom. The nozzle 47 is vented to the atmosphere through a pipe 46. The breaker plate assembly comprises perforated plates 26, 27 keyed together and clamping between them a screen pack 29. The device 43 may be rotated by an electric or hydraulic motor energized by a pressure responsive element when a predetermined back pressure is attained upstream of the breaker plate assembly. U.S.A. Specifications 2,661,497, 2,763,308, 2,771,636, 2,786,504 and 2,838,084 are referred to. |
