| 摘要 |
<p>An extruder has a barrel 1 with screw section 9 of larger diameter and coarser pitch and screw section 10 of smaller diameter and finer pitch both separately rotatable therein in the same sense, to move material from inlet 6c to melt outlet 8c. Section 10 is mounted on shaft 17 passing through section 9. Separate drives for screws 9, 10 are provided by motors 4, 5, separately controlled by gearboxes 20, 21 respectively, or separate gear control from a single motor. Thus feed section 6 of the barrel, fed through orifice 6c with non-uniform scrap polymer is controlled separately from metering section 8 feeding outlet 8c, whereby non-uniformity of feed does not overload the extruder. Separate control can be effected by feedback of electrical load signals to control the speed of the motors. Seal 19 prevents molten polymer getting inside screw portion 9. <IMAGE></p> |
