Paul Troester Maschinenfabrik

Klaus Koch

The screw for an extruder for working plastic material and rubber comprises along its length several zones with different numbers of threads or webs. In at least one portion of its length, the screw has a plurality of single thread zones alternating with two-thread zones. In each of the two-thread zones there are two webs which are diametrically disposed and extend parallel to the axis of the screw. These axially extending webs have inclined or wedge shaped flanks so that a wedge shaped aperture is formed between the cylinder wall of the extruder and the wedge shaped flanks of the axially extending webs. One web of the two-thread zone joins the web of the preceding single thread zone and the other web of the two-thread zone joins the web of the following single thread zone at the points where the axially extending webs meet the webs of the two-thread zone.

Extruder screw

Apparatus for extruding plastic material, rubber and other thermoplasts and elastomers comprises two screw extruders each having a casing with a cylindrical bore and with a feed inlet and discharge, an extruder screw rotatable in the cylindrical bore of the casing and drive means at the opposite end of the casing from the discharge for rotating the extruder screw. The discharge of the first extruder is connected to the feed inlet of the second extruder so that material extruded by the first extruder is fed into the second extruder. A vacuum is applied to the interior of the casing of the second extruder in the vicinity of the inlet opening in order to degas material received in the second extruder from the first extruder. At a point slightly downstream from the inlet of the second extruder there is provided pressure responsive means for sensing pressure variations in the bore of the extruder. Control means responsive to the pressure sensing means regulates the relative speeds of rotation of the screws of the first and second extruders so that the screw channel of the screw of the second extruder in the vicinity of the inlet opening is not completely filled, thus leaving a space in the passage through which the vacuum is applied to the material to obtain an effective degassing thereof.

Method and apparatus for extruding plastic and similar material

Extruding apparatus comprises a first screw extruder feeding into the inlet of a second screw extruder, such inlet being located at an intermediate position between the driving means and the discharge of the second extruder. Degassing means which applies a vacuum to the material fed into the second extruder tends to draw off particles of material entrained in the gas which is drawn off. The screw of the second extruder has a first screw portion which acts in a direction to propel the main mass of material from the inlet to the discharge of the second extruder and a second screw portion which acts in the opposite direction to propel the drawn off material from the inlet to an outlet which is located between the inlet and the driving means and which opens into a vacuum chamber. A third screw portion located between the outlet and the driving means acts in the same direction as the first portion and hence toward the outlet.

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Gleidingen, undefined

Klaus Koch