subject: Degassing Means For A Twin Screw Extruder For Plastic Materials [print this page] In 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 longitudinal axes, and having intermeshing threads, one of said housing segments serving for degassing the plastic material and communicating with a degassing chamber, said one housing segment having a transverse, radial opening in which an insert member is fitted, said insert member having a degassing opening providing communication between the degassing chamber and the bores in said housing, the improvement wherein said degassing opening in said insert member tapers in widening fashion in the direction from said longitudinal bores to said degassing chamber, said degassing opening having a longitudinal axis disposed in a plane passing through the longitudinal axes of said screws.
The invention relates to a twin screw extruder for processing plastic material having a housing formed by a plurality of juxtaposed housing segments arranged axially in succession and defining two longitudinal overlapping bores respectively containing coaxially arranged extruder screws, rotatable about respective longitudinal axes and having intermeshing threads. At least one of the housing segments serves for degassing the plastic material and is in communication with a degassing chamber attached at a lateral side of the housing. The degassing housing segment has a transverse radial opening in which is fitted an insert member having a degassing opening providing communication between the degassing chamber and the bores in the housing.
In a simplified arrangement which is easy to handle, the housing segment which is to receive the insert member has an opening of rectangular cross-section and the insert member includes a projection of corresponding rectangular cross-section which can be tightly fitted in the opening in the housing segment. 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 twin screw extruder.
