Corotating twinscrew extruder lines
The co-rotating twin screw extruders of the EBB BiTeCh and EBB BiReC series use modular cylinders and assembled extrusion screws, with self-cleaning sector, mounted on grooved shafts.
The sector cylinders, with different L/D ratios depending on the production process for which they are intended, can be thermo stated by water, oil or air, and are constructed using special chrome steel or, alternatively, bimetallic steel with wear-resistant and/or corrosion resistant additions.
In some cases they can be fitted with special internal, removable and interchangeable bushings made of core-tempered steel with high resistance to wear.
Fully exploiting the principle of modularity, the twin screw extruders can be configured so as to optimize their use depending on the applications for which they are intended.
The sectors that made up an extrusion cylinder can be listed briefly as follows:
Infeed module: the cylinder is fitted with an infeed opening that is also suitable for application of a compacting hopper for materials with low apparent density. Special sectors are mounted on the screw, in this zone, with a profile designed to ensure a high conveyor capacity, especially if the extruder is furnished with a forced infeed system via vertical compacter.
Standard module: the thermoplastic material fed into the extruder is conveyed into this type of cylinder, where it is heated and melts. In this zone, elements for conveying, mixing and homogenizing the material are mounted on the screw, with profiles compatible with the material processed.
Degassing/vent module: the cylinders are equipped with special discharge exhaust pipes, in a vacuum and at atmospheric pressure. In the zone of the degassing hollows, the screw is endowed with a special profile designed to facilitate the expansion and evacuation of the gasses, vapors and all those volatile elements that form during processing.
Lateral infeed module: the cylinders are arranged for lateral (or vertical) infeed of powdered products, resins and/or liquids. The modules differ from one another depending on the additives to be processed. Also in this case the screw profile is adapted to the products introduced.