Multi-shaft single screw extruder, in particular twin screw extruder
A multi- shaft single screw extruder, in particular twin screw extruder having a casing with two parallel intersecting casing bores and two shafts drivably disposed in the casing bores. Screw elements intermeshing kneading disks are fixed on the shafts. The widths of the respective crest portions of the kneading disks are smaller than the disk width and form mixing-and-scraping-studs on the periphery of the disks. The mixing-and-scraping-studs on each kneading disk are axially misaligned relative to each other such that their peripheral faying surfaces jointly cover the entire disk width.
A single screw extruder according to the prior art is known from DE 25 50 969 C2. It is provided with kneading disks which are non-rotatably mounted on the two screw shafts, providing for a processing of the material conveyed through the extruder, for instance homogenizing, mixing, kneading, plasticizing and the like. Depending on the number of their flights, the kneading disks may have a lenticular (two-flight kneading disk), trochoidal (three-flight kneading disk) etc. contour.
According to the sheet production extruder, this object is attained in a screw-type extruder comprising a casing; several, preferably two, parallel and partially intersecting casing bores; several, preferably two, shafts disposed in the casing bores to rotate in the same or counter direction and preferably drivable to rotate in the same direction; screw elements fixed on the shafts; and intermeshing kneading disks, which are fixed on the shafts and the respective crest portions of which are reduced in relation to the disk width for mixing-and-scraping-studs to form, which are located on the periphery; wherein the mixing-and-scraping-studs on each kneading disk are misaligned in the axial direction such that peripheral faying surfaces jointly cover the entire disk width. Thus, the material resting on the casing wall is removed in a single operation upon a full rotation of the kneading disk over its width at each axial position. The prior art drawbacks mentioned at the outset are efficiently avoided. Thus, an excellent mixing effect of these kneading disks is accompanied with complete scraping of the casing wall.
Further features, details and advantages of the twin screw extruder will become apparent from the ensuing description of preferred embodiments, taken in conjunction with the drawing single screw extruder.