In a ribbon cable extrusion die assembly, a large plurality of fine electrical conductor wires, numbering from 20 up to 50, 60 or more, are led through a core tube via individual quills. Molten plastic insulating material is delivered to the exterior of the core tube, and surrounds the plurality of the conductor wires as they emerge from the core tube to enter the extrusion die. The aligned array of conductor wires and the molten plastic insulating material pass together through the extrusion die, which incorporates a cylndrical die passage for each individual conductor wire, with web passages connectng the cylindrical passages to form a unitary ribbon cable extrusion emerging from the extrusion die. The guiding quills are individually removable from the core tube, in response to the actuation of automatic wire breakage sensing and alarm systems for quick replacement of a broken conductor wire by a new unbroken conductor wire. Fine adjustment of the extruded insulation thickness, and extremely sensitive positioning of the conductor wires within the cylindrical die passages, are both achieved by translational and rotational rocking adjustment movement of the extruder die within the housing, controlled by five separate adjustable set screws which permit the equalization of insulation thickness on all sides of all of the arrayed parallel conductor wires forming the ribbon cable extrusion.

Method and apparatus for producing sealing strips and similar profiled strips of rubber and rubber-like elastomers. Rubber-like profiled sealing strips for window or door openings are frequently provided with overlay strips to facilitate installation, to enhance the relative movements, or for aesthetic-visual reasons. The material of these overlay strips generally differs considerably from the material of the base main strip. The manufacture of such two-material profiles can be undertaken in a single extrusion step by joining and directly combining a prefabricated overlay strip with the main strip in the extrusion head of an extrusion press, where the shape is provided for the profiled strip. By stretching the overlay strip, the adhesion of the latter to the main strip is significantly improved.

A hybrid extruder provides plastic insulation which is as uniformly and tightly disposed about a substrate as that produced in a conventional pressure extruder and accommodates irregular substrates. The hybrid extruder includes a core tube which is positioned in a die cavity to form a flow passage which includes a restriction to the flow at the end of the core tube to maximize the pressure in the plastic material. The leading end of the core tube is spaced a distance from the land of a die which is substantially less than in conventional pressure extruders to form another portion of the flow passage having a predetermined configuration. After flowing through the restriction, the plastic material expands. This avoids any backflow of the plastic material into the core tube in the event the core tube is to allow the passage of oversized spliced portions of the substrate. Advantageously, this arrangement also prevents the occurrence of melt fracture when extruding relatively high molecular weight plastic materials which because of excellent mechanical and dielectric properties are desired for insulating particular substates.