Method and apparatus for manufacturing soft metal sheaths for electrical wires

Abstract

Manufacturing of a soft metal sheath formed of aluminum or copper, for example, is improved by suitably selecting the apparatus composing the shaping means employed therein and arranging the capstan and the sinking die in a novel manner. The apparatus selected is made from a wear-resistant synthetic resin such as a molybdenum bisulfide-included nylon. The sheath is manufactured from a metal tape of aluminum or copper through the working stages of applying a cylindrical tube shaped from the tape onto a cable core, butt welding the seam, and then reducing the diameter of the metal tube to connect it to the core.

We claim: 
     
       1. In a method of continuously manufacturing a soft metal sheath electric cable by moving a soft metal tape longitudinally in unison with a core and wrapping said tape about said core, the improvement comprising the steps of, in sequence: surface cleaning said soft metal tape whose width is in excess of that needed to laterally envelope the cable core,   cutting off both side edges of said tape to reduce the width of said tape to a dimension such that the side edges will exactly abut when laterally wrapped about the core and to provide abutting side edges which are oxide free,   bending said tape into an arc in cross section by passing said tape through opposed concave and convex wear resistant plastic rollers,   butting said oxide free tape side edges together by passing said arc-shaped tape through a wear resistant plastic cylindrical shaping tool and a wear resistant plastic forming die having a circular opening therein,   seam welding the butting oxide free side edges,   extracting the tube from said forming die and pushing the tube through a reducing die under lubrication by means of a capstan positioned upstream of the reducing die and downstream of the forming die to uniformly radially inwardly reduce the tube to mechanically couple the soft metal tube to the outer surface of the cable core with true circular cross section provided thereby.