| 摘要 |
1,163,308. Insulating conductors by extrusion. WESTERN ELECTRIC CO. Inc. 10 Oct., 1966 [11 Oct., 1965], No. 45085/66. Heading B5A. [Also in Division H1] An insulating tube is extruded around a conductor and after inflation helically bound with a filament which forces the engaged portions of the tube into contact with the conductor. As shown, the central conductor 16 of a coaxial cable has a polyethylene tube 20 extruded around it by an extruder 11 heated by coils not shown. Pressurized gas enters at 22 and inflates the tube which is still in the plastic state to the internal diameter of a cylinder 31. A rotating assembly 41 winds a filament of nylon (or copper if it is to be subsequently removed) around the tube to form it into a spiral spacer fin. The tube passes to a cylinder 32 in which it is cooled by an inert refrigerated gas entering at 66. The speed of rotation of the assembly and thus the lay of the filament is automatically adjusted to keep the capacitance of the cable constant. An outer conductor which may be corrugated or embossed, a sheath comprising alternate layers of rubber and aluminium and a polyethylene jacket are subsequently applied in known manner. In a modification, the cylinder 31 rotates with the assembly and the filament passes through an aperture in the cylinder. |
