Degassing means for a twin screw extruder
Degassing means for a twin 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 longitudinal axes, and having intermeshing threads. One of the housing segments serves as a degassing housing segment for degassing the plastic material and it is connected to a degassing chamber. The degassing housing segment has a transverse, radial opening in which an insert member is fitted, the insert member having a degassing opening providing communication between the degassing chamber and the bores in the housing. T
An object of the single screw extruder is to provide degassing means which is effective, in a simple way, to remove volatile components from melted plastic materials within a broad viscosity range thereof.
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 screw extruder.
In the case of intense degassing conditions and/or highly viscous melt sheet production extruder, it is advantageous to use multiple degassing stages. 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 extruder screws, and installing a second insert member in the second opening having a degassing opening connected to an associated degassing chamber, said degassing opening having a longitudinal axis coincident with the longitudinal axis of the degassing opening in the first insert member on the other side of the degassing segment.
If only twin screw extruder degassing opening is to be utilized on either side of the housing, a sealing insert member is inserted into the radial opening at the other side to close the same.
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 the housing segments serves as a degassing housing segment for degassing the plastic material and it is connected to a degassing chamber. The degassing housing segment has a transverse, radial opening in which an insert member is fitted, the insert member having a degassing opening providing communication between the degassing chamber and the bores in the housing. T
An object of the single screw extruder is to provide degassing means which is effective, in a simple way, to remove volatile components from melted plastic materials within a broad viscosity range thereof.
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 screw extruder.
In the case of intense degassing conditions and/or highly viscous melt sheet production extruder, it is advantageous to use multiple degassing stages. 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 extruder screws, and installing a second insert member in the second opening having a degassing opening connected to an associated degassing chamber, said degassing opening having a longitudinal axis coincident with the longitudinal axis of the degassing opening in the first insert member on the other side of the degassing segment.
If only twin screw extruder degassing opening is to be utilized on either side of the housing, a sealing insert member is inserted into the radial opening at the other side to close the same.