Fujikura Limited

Teruyuki Takayama

Haruo Tominaga

Tetsuo Yamaguchi

Hiroki Nagasawa

Sumihisa Aoki

Kenichi Miyauchi

Kazuo Yokoyama

Yoshio Ogura

First, a steel wire is continuously dipped in molten copper or molten copper alloy so that copper or copper alloy builds up and solidifies on the peripheral surface of said steel wire, thereby obtaining an initial copper-clad steel wire. Then, the initial copper-clad steel wire is subjected to a first cycle of hot rolling by a caliber roll. The hot-rolled wire is dipped in molten copper or molten copper-alloy at least once so that copper or copper alloy builds up and solidifies thereon, thereby obtaining a final copper-clad steel wire. The final copper-clad steel wire is hot-rolled at a temperature of 750.degree. to 850.degree. C. and with a rolling ratio of 10 to 40%. Then, the hot-rolled wire is cold-rolled with a reduction of area of 20% or more. Thus, 75 to 95% of the cross sectional area of the obtained copper-clad steel trolley wire is occupied by the copper or copper alloy covering layer so that the electric conductivity of the trolley wire is as high as 80% IACS or more. Moreover, the cast rod is hot-rolled so that the core and the covering layer are metallurgically bonded to each other, thereby obtaining a copper-clad steel trolley wire whose core and covering layer are firmly bonded. Also, the hot-rolled wire is cold-rolled so that a trolley wire with high strength is obtained.

Method for manufacturing high-conductivity copper-clad steel trolley wire

A dip forming apparatus for continuously forming a cast rod includes a furnace for holding molten metal, and a crucible having an open top and a bottom wall. The crucible has a core wire-passing region vertically extending therethrough. The crucible has a hole formed through the bottom wall. A passage connects the furnaces to the core wire-passing region. A device is provided for keeping the molten metal in the furnace at a predetermined level so as to flow the molten metal from the furnace to the core wire-passing region through the passage. A partition wall is disposed in the passage and has a throttling orifice of a predetermined size formed therethrough so as to allow the molten metal to pass therethrough to limit the flow of the molten metal from the furnace to the core wire-passing region. A drive device moves the core wire upwardly at a preselected speed through the hole and the core wire-passing region, so that the molten metal in the core wire-passing region accretes on the core wire to form the cast rod.

Dip forming apparatus for continuously forming cast rod

An electrode wire for wire electric discharge machining a workpiece at high speed and high accuracy and a process for preparing the same are provided. The electrode wire comprises a core wire made of a copper clad steel wire, 10 to 70% of the sectional area of the copper clad steel wire being occupied by copper, and a copper-zinc alloy layer covering the core wire. The copper-zinc alloy layer is prepared by coating the core wire with zinc by electroplating or hot galvanizing, followed by heating to disperse copper in the zinc layer to convert the same into a copper-zinc alloy layer wherein the concentration of zinc is increased gradually along the radially outward direction. The preferable thickness of the copper-zinc alloy layer ranges from 0.1 to 15 microns and the average concentration of zinc in the copper-zinc alloy layer is preferably less than 50% by weight but not less than 10% by weight.

Electrode wire for use in electric discharge machining and process for

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Chiba, Japan

Teruyuki Takayama