Abstract: In order to improve the wear-resistance of highly stressed surfaces of a kneading disc in a helical extruding machine, the exposed tips of the kneading disc are provided with inserts of an extremely wear-resistant, hard material. In a variety of embodiments, the tips of the lenticular kneading disc are provided with bores and recesses for receiving the hard inserts. Advantageously, the recesses are cylindrical wells in which cylindrical inserts are soldered or cemented. The inserts may be made from hard metals or ceramics, for example tool steel or tungsten carbide or the like.

Abstract: A wear-resistant lining is provided in the work chamber of a screw extruder by providing an internal cavity in the extruder housing of a shape corresponding to the external cross-section of a wearing insert but sufficiently larger such that a gap of predetermined width is provided between the walls. A layer of soft, hardenable material is applied to the outer surface of the wearing insert to a thickness slightly greater than the gap. The extruder housing is heated until the cavity expands to a degree sufficient to allow insertion of the insert. The insert is then placed into the cavity and the material is allowed to harden, as by heat hardening due to the temperature of the extruder housing.

Abstract: An internal mixer for kneading and rolling includes a mixing chamber containing two parallel spaced shafts. Kneading blades and arcuate roller surfaces are provided on the outer peripheries of the shafts. The arcuate surfaces are so disposed on the shafts such that a gap is formed therebetween when in their innermost positions. The arcuate surfaces and kneading blades are disposed serially in the peripheral direction on the shafts. The shafts rotate in opposite directions and so as to provide the same peripheral speed for the arcuate surfaces.

Abstract: A screw extruder housing is made wear-resistant by providing a non-metallic lining formed of brittle material, the lining being divided into a multiplicity of individual wearing units firmly anchored in place in the casing.

Abstract: A method of and device for feeding into the charging funnel of a worm machine strip-shaped or irregularly formed partial pieces of material, especially rubber, dosed by weight as components of a mixture, according to which the pieces are weighed individually and are conveyed to the worm machine in a cycle sequence time compensating for the difference of the rated value or preselected weight and the actual value of the weight of the individual piece. The device for practicing the method according to the invention has an electric scale preferably connected to an analog converter, which scale feeds a starting voltage proportional to the actual weight of the partial pieces to a rated value -- actual value comparator and to an electric calculator which latter determines the change in the cycle sequence time in conformity with the deviation from the preselected weight of the respective partial piece.