Formation of metal wire

Details Formation of metal wire Formation of metal wire

2000-07-11

2001-10-16

Hoang, Tu Ba (Department: 3742)

Industrial electric heating furnaces

Induction furnace device

C373S156000, C373S059000, C219S605000, C219S635000

Reexamination Certificate

active

06304590

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the formation of metal wire by freezing molten metal onto a feed wire as it passes through a liquid metal bath.
BACKGROUND OF THE INVENTION
Wire can be formed by running a small diameter feed wire through a liquid metal bath held in a refractory container. As the feed wire passes through the bath, liquid metal freezes onto the feed wire to produce a wire of increased diameter. Consequently, the process can be referred to as “freeze-forming.”
A prior art freeze-forming process, as illustrated in FIG.
1
and further described below, has been used to make stainless steel wire, but is unsuitable for the manufacture of wire formed from a metal that will react with the refractory materials used for the molten metal container
130
, the nozzle
125
and the stopper rod
122
. A chemically reactive metal, in its molten state, will attack and decompose refractory materials with which it comes into contact.
A suitable substitute for the refractory container, namely a cooled, segmented, metallic crucible, is disclosed in U.S. Pat. No. 4,058,668 entitled Cold Crucible. However, this does not solve the problem of reactive metal attack on the refractory stopper rod and nozzle shown in FIG.
1
. In the present invention, the stopper rod is eliminated and the refractory nozzle is replaced by a water-cooled nozzle, inside which the metal is heated. Therefore, the present invention overcomes the problems of the prior art for freezing-forming a reactive metal wire.
SUMMARY OF THE INVENTION
The invention in its broadest aspect is a method for forming an increased diameter wire from a feed wire. A cooled crucible is provided. A liquid metal bath is established in the cooled crucible. The liquid metal bath is heated, for example, by induction heating. The crucible has a cooled nozzle disposed at least partially below the upper surface of the liquid. Both the crucible and nozzle may be of a segmented design. The liquid metal bath in the vicinity of the nozzle may be separately heated, for example, by induction heating, to prevent the deleterious attachment of skull to the feed wire. Optionally, a dc magnetic field may be applied to the metal bath to control the dynamic fluid properties of the bath. By passing the feed wire sequentially through the opening in the nozzle and the liquid metal bath, metal freezes onto to the feed wire and produce an increased diameter wire.
The increased diameter wire maybe optionally drawn through a die or squeezed between rolls to achieve further control of the diameter. Gas at a positive pressure may be applied around the external opening of the nozzle, preferably at a pressure greater than the pressure applied to the upper exposed surface boundary of the liquid metal bath. The method may use multiple nozzles with each nozzle having a feed wire drawn through it to form multiple freeze-formed wire products. The method is particularly applicable to chemically reactive molten metal compositions.
In another aspect, the invention is an apparatus for forming a freeze-formed wire product from a feed wire. The apparatus includes a cooled crucible that has a cooled nozzle. A liquid metal bath is contained within the crucible. The cooled crucible and nozzle may be segmented. The liquid metal bath is heated, for example, by an induction heating system. The feed wire is drawn sequentially through the opening in the cooled nozzle and liquid metal bath to form a freeze-formed wire product. A separate heating system may be provided for heating metal liquid in and in the vicinity of the cooled nozzle. The apparatus may also include means for applying a dc magnetic field to the liquid metal bath. Means may be provided for applying a gas at a positive pressure by, for example, providing an enclosure around the exterior opening of the cooled nozzle and injecting gas into the enclosure.
A reading of the following description and appended claims will provide a thorough understanding of the invention.


REFERENCES:
patent: 4058668 (1977-11-01), Clites
patent: 5537849 (1996-07-01), Kawakami et al.
patent: 5698124 (1997-12-01), DiMarcello et al.
patent: 5848093 (1998-12-01), Goudeau et al.
patent: 5957005 (1999-09-01), Einset et al.
patent: 6104742 (2000-08-01), Carter, Jr. et al.

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