Abstract: A mixing element for a screw extruder comprises an element including opposing lobes and a central portion having common opposing broad surfaces; one lobe broad surface being formed into a taper. The elements may be used individually or combined in blocks, with the elements of a block oriented in various combinations. The blocks may comprise two or more elements. The tapered lobes provided reduced pressure and temperature of the process as compared to prior art mixing elements. Also, more graduated control over temperature and pressure are provided according to the value of the taper magnitude, the number of elements used in a process and the relative lobe orientations in a machine.

Abstract: A single flighted multi-screw conveying bushing that has only one helical screw element extending the length of the bushing. The bushing has a cross-section shape that has a segmented circular base and a lobe extending from the base. The lobe has a truncated crest that is sized to have a circumferential angle of from 15.degree. to 30.degree. and preferably from 22.degree. to 24.degree.. Also, a twin screw extruder having a pair of side by side drive shafts with at least two of the single flighted screw bushings mounted end to end on each shaft.

Abstract: A stationary axle is secured adjacent to an extruder of plastic or other material forming a strand. A rotor rotates about the axle and carries a plurality of axially extending cutters for pelletizing the strand. The shaft has an internal fluid conduit carrying pressurized air. A sleeve is fixed to and over the shaft and has a recess forming a fluid manifold in communication with the conduit and the rotor. The recess has a given angular extent about the sleeve. A plurality of annularly spaced linear arrays of passages in the rotor communicate with the recess manifold in accordance with their angular position about the shaft. The passages of each array are aligned with the edge of a different cutter for sequentially generating arrays of streams of pressurized air impinging upon the cutters after pelletizing as the rotor rotates.

Abstract: In a housing for co-rotational twin screw machine for longitudinally conveying non-free flowing materials, the housing having two intersecting cyclindrical bores for receiving two intermeshing screws and means forming at least one port thereover, the improvement wherein the means forms an anti-bridging port comprising one planar longitudinal side wall having the lower edge thereof disposed adjacent the intersecting area of the two bores and wherein the sidewall slopes outwardly from the lower edge above one bore at about 60.degree. to 90.degree. with respect to the horizontal plane and extends approximately tangentially with respect to said one bore.