Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1997-10-20
2001-11-06
Arbes, Carl J. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C505S110000, C505S739000, C505S740000
Reexamination Certificate
active
06311384
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing an oxide superconducting wire by plastically working an oxide superconductor into a wire, and more particularly, it relates to an improvement in a plastic working step.
2. Description of the Background Art
In general, an oxide superconducting wire is manufactured by filling up a metal pipe with oxide raw material powder, working the same into a wire through a step of plastic working such as extrusion, wire drawing, rolling or the like, and thereafter heat treating the wire. It is known that such plastic working and heat treatment are effectively repeated in order to improve critical current density of the as-formed wire.
In relation to such a method of manufacturing an oxide superconducting wire, densification of the oxide superconductor filling up the metal pipe contributes to improvement of critical current density. In order to densify the oxide superconductor, therefore, it has been necessary to perform flat working on the basis of press working, roll working or the like. The flat working is adapted to compress a round wire, for example, along its sectional direction, thereby working the same into a wire having a flat section. Such flat working is generally carried out in a plurality of stages in order to reasonably attain a desired sectional configuration or desired dimensions. Thus, flat working based on press working is inferior in high-volume production capability since it is necessary to perform flat working in sequence on every portion of a wire, while that based on roll working is inferior in workability since a plurality of working steps are carried out.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a method of manufacturing an oxide superconducting wire, which can efficiently obtain a superconducting wire having high critical current density.
The inventor has made deep study and experiments as to relations between working conditions and critical current density values of oxide superconducting wires obtained by flat working capable of continuously manufacturing long members, and found that an oxide superconducting wire having high critical current density can be obtained by performing flat working at a draft of at least 80% and not more than 98%, even if such a flat working step is carried out only once.
According to the present invention, a method of manufacturing an oxide superconducting wire at least comprises a step of plastically working an oxide superconductor for working the same into a wire, and in order to solve the aforementioned technical problem, the plastic working step includes a step of performing flat working at a draft of at least 80% and not more than 98%.
Thus, according to the present invention, the plastic working step includes a step of performing flat working at a draft of at-least 80% and not more than 98% in order to improve density of the oxide superconductor, whereby it is possible to efficiently obtain an oxide superconducting wire, which exhibits high and homogeneous critical current density along its longitudinal direction after heat treatment.
Thus, the oxide superconducting wire obtained according to the inventive method is effectively applicable to the field of a cable or a magnet, which is prepared from a long wire, in particular.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
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