Abstract: A double extruder for the production of a two-layer tubular extruded product, which extruder comprises a treating screw (8) rotatably mounted in a housing provided in a frame (2) and forming a ring-shaped treating space (21) between the frame and the screw, and inlet and outlet channels (13, 22, 23) extending to the periphery of the treating screw for supplying materials to be extruded into the treating space and for discharging the materials therefrom, and extrusion means (14) mounted in the frame and communicating with the outlet channel. The treating screw is tubular and forms two separate treating spaces together with the frame, each space extending from the outer periphery of the treating screw around the end edge to the inner periphery of the screw. The outlet channel is ring-shaped and joins radially the inner periphery of the tubular treating screw.

Abstract: A method of and a device for adjusting the capacity and the diameter of an electric conductor provided with an insulation coating of foamed plastics material in an extruder press. The press is provided with an adjustably rotating feed screw and adjustable heating means. The deviation of the capacity of the insulated conductor from a preset capacity and the deviation of the diameter of said conductor from a preset diameter are measured at the path of movement of the conductor. The rotation speed of said screw is adjusted in response to said capacity deviation and said diameter deviation and the temperature of said heating means is also adjusted in response to said capacity variation and said diameter deviation in order to correct said deviations.