Advantages of Single Screw Extruder

     Advantages of Single Screw Extruder

The significant advantages the Single Screw Extruder with barrier according to the present invention has the advantage that the pressure build-up capability is improved. Compared to the known Twin Screw Extruder it is not necessary any more to build up a very high pressure in the so-called feed zone as to enable a predetermined lower pressure at the end of thegravimetric feeder With the according to the present invention it is possible to substantially reduce the pressure between the feed zone and the melting zone. This in turn results in a reduction of wear of the gear pump in the transition area between the feed zone and the melting zone since it is operated with lower pressures.

(1)In a preferred embodiment the barrel comprises several grooves being equally spaced apart in circumferential direction which grooves extend preferably parallel to the longitudinal axis of the barrel. This has the advantage that the process of matching the grooves is simplified compared with the groove helically arranged.

(2)Due to the pressure reduction in the area of the feed zone it does not have to be constructed any more as complicated as in prior solutions and does not have to be provided with cooling means and a “heat separation” towards the heated melting zone. Advantageously, the feed zone and the melting zone may therefore be formed individually.

(3)In a further preferred embodiment the width and/or the depth of the groove varies in a longitudinal direction, preferably the grooves depth decreases towards the downstream end of the melting zone section, preferably to zero.

This has the advantage sheet production extruderthat the groove extends continuously without Single Screw Extruderany break along the feed zone and melting zone thereby further improving the output and the pressure build-up. 

In a further preferred embodiment of the invention at least one groove is provided also in the barrel inner surface (innerwall) in the area of the feed zone section, the groove extending parallel or helically relative to the longitudinal axis. Preferably, the groove in the area of the feed zone section leads into the groove in the area of the melting zone without transition. Preferably both grooves have the same lead angle.