Method for manufacturing a stranded conductor constituted of insulated strands

Abstract

A method is disclosed in which an insulating film of an oxide of metal, of which a stranded conductor (30) is made, is formed on the surface of all strands in a stranded conductor, while the stranded conductor is held in the stranded form. In a step of oxidation-treating the strands of an electric cable the pressure of an oxidation treatment solution at the outer portion of the stranded conductor immersed therein is made higher than the pressure in the inner portion of the stranded conductor (30), causing the oxidation treatment solution (48) to be adequately penetrated from the outer portion into the inner portion of the stranded conductor to permit a desired oxide film to be formed on the surface of all the strands in the stranded conductor. In order to more facilitate the penetration of the oxidation treatment solution (48) wholly into the interior of the stranded conductor (30) and the more facilitate an oxidation reaction, vibrations are, in addition to this method, imparted to the stranded conductor (30) in the oxidation treatment step (40) to cause the untwisting of the stranded conductor (30) to be effected to some extent, while the stranded conductor being heated is entered into this step.

Dependencies are inferred from the claim text.