twin screw extruders

This can be achieved according to the invention, by providing a second transverse opening in the degassing housing segment arranged relative to the first opening symmetrically with respect to a vertical longitudinal plane midway between the longitudinal axes of the twin screw extruder screws.

The outer surface of the insert member is flush with the outer surface of the housing. Hence, a smooth unbroken outer contour of the housing is provided which enables application of heating shells onto the housing as in the conventional screw extruder.

A twin screw extruder for processing plastic material having a housing provided with a plurality of juxtaposed housing segments arranged axially in succession and defining two longitudinal, overlapping bores respectively containing two coaxially arranged extruder screws, rotatable about respective solar panel manufacturer, and having intermeshing threads.

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In one extreme, the diameter of the driven pinion gears cannot be greater than the distance between two co-rotating shafts. In another extreme where the drive gear pinions are axially offset from the other, one of the pinion gears cannot have a radius that is greater than the difference between the distance between the shafts and the radius of twin screw extruder.

The relatively small distance required between the axes of the screw shafts of a twin screw extruder has historically limited the diameters of final drive pinion gears of a torque splitting transmission for driving the closely spaced twin screws. The pinion gear size is limited as a function of the center distance between the shafts.

Unfortunately, the torque capacity of a gear varies with the cube of its diameter and the small diameter of the pinion gear is a limiting factor of the torque that can be delivered to the twin screws whose torque capacity is typically greater than the torque capacity of the pinion gear. In operation, twin screws generate an axial force that is carried as a thrust load into the torque splitting transmission. There are several prior art solutions to enhance the torque limitations associated with a small diameter pinion gear and bearing loads induced by the pinion gear and granulator.

The twin screw extruder was first invented in 1930s in Italy, while in the late 1960s and early 1970s, it experienced a rapid development. With the development of RPVC products, counter-rotating twin screw extruder came into being; while co-rotating twin screw extruder appeared, companying with the polymer modification. It is useful to study the twin screw extruding theory, because it can not only be applied effectively, but also has become a consensus and a hot research in the world.

The design of twin screw extruder and optimization of extruding process could be improved by material change laws, conveying theory ,including convey of solid and melt, also gas filling and ejecting characteristics, which can form a mathematics and physical model in the extruding process.

A Twin Screw Extruder not only shares the common operation principles with a single screw extruder: solid conveying, melting, admixture of pressurizing and pumping up, etc., but also owns its distinct characteristics. There are several factors that tackle the study of basic principles of co-rotating twin screw extruder, such as the late research of  PVC pipe, various types, complex screw geometry, and complicated extruding process.