| 摘要 |
In the production of extruded cellular polymeric material, for instance as a layer on a travelling wire, by feeding polymeric material under pressure in a viscous or fluid state into the inlet end of a screw extrusion machine having a gas injection zone followed by an extrusion zone, the location in the extruder barrel of the transition between the part that is partly filled by the polymeric material and the part that is fully filled is determined by measurement of pressure, in the extruder barrel, and the relationship between the rate of feed of polymeric material into the extruder and the speed of the extruder is controlled to stabilise the position of the transition in accordance with said measurement. Apparatus for use in the method includes two independently driven screw extrusion machines, the first of which feeds polymeric material into the second at a rate controlled in accordance with the measurement of said pressure in the second machine. |
