Abstract: To form the housing of a double-screw extrude, the housing body or a segment thereof is provided with auxiliary bores along a segment of the housing at which the hardening material is to be thicker or a hardening material is to be provided. The screw-receiving bores are then formed and overlap each other and the auxiliary bores and the hardening material is provided at least in the auxiliary bores by a division process, preferably a hot isostatic pressing (HIP) process.

Abstract: To form the housing of a double-screw extrude, the housing body or a segment thereof is provided with auxiliary bores along a segment of the housing at which the hardening material is to be thicker or a hardening material is to be provided. The screw-receiving bores are then formed and overlap each other and the auxiliary bores and the hardening material is provided at least in the auxiliary bores by a division process, preferably a hot isostatic pressing (HIP) process.

Abstract: An extruder cylinder is heated by resistance heaters surrounding cooling coils around respective segments of the extruder cylinder which is subdivided into heating and heating or cooling zones therealong. The rate of flow of the heat-carrier oil in the coil or the rate of flow of a cooling medium in heat exchange therewith can be regulated to control the cooling effect of the heat-carrier oil which can continue to flow through the coil even during purely heating phases for temperature equalization over the zone.

Abstract: An extruder cylinder is heated by resistance heaters surrounding cooling coils around respective segments of the extruder cylinder which is subdivided into heating and heating or cooling zones therealong. The rate of flow of the heat-carrier oil in the coil or the rate of flow of a cooling medium in heat exchange therewith can be regulated to control the cooling effect of the heat-carrier oil which can continue to flow through the coil even during purely heating phases for temperature equalization over the zone.

Abstract: Advantageous water treatment compositions are provided, which remain stable prior to their intended use in an aqueous environment. The compositions comprise sodium chlorite and an acid activator. Preferred as an acid activator is citric acid, anhydrous. The composition may also comprise, if desired, activated carbon, which may optionally be ion-impregnated. A method of treating water utilizing the compositions is disclosed, and water treatment kits are also provided.

Abstract: A preheater and feeder for thermoplastifiable material supplied to an extruder for synthetic resin has the counterrotating worms in a heated housing delivering the material at a rate determined by the worm speeds. The worms are hollow and the major portion of the heat, apart from friction heat, contributed to the material is delivered by passing a heating fluid through the hollow worms.

Abstract: A step-down transmission for driving a plurality of extrusion screws from a common power source comprises a main shaft, directly connected with one screw and coupled with the source via a reduction gearing, and one or more pairs of corotating ancillary shafts coupled with the main shaft via gear trains each including a cylindrical gear in mesh with two spur gears respectively keyed to the shafts of the corresponding pair. The paired ancillary shafts carry helical gears in mesh with a common pinion on a shaft of another screw closely adjoining and possibly intermeshing with the first-mentioned screw.

Abstract: A screw extruder of the type in which a pair of counter-rotating screws of progressively increasing diameter plasticize and extrude thermoplastic resins and in which an equal ratio of power conversion in shear and convective heating to throuput of material is obtained over the length of the screws.