Industrial electric heating furnaces – Electron beam furnace device
Reexamination Certificate
1999-07-15
2001-01-16
Hoang, Tu Ba (Department: 3742)
Industrial electric heating furnaces
Electron beam furnace device
C373S016000, C219S121210
Reexamination Certificate
active
06175585
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
FEDERALLY SPONSORED RESEARCH
Not applicable.
BACKGROUND OF THE INVENTION
Field of the Invention
The subject invention relates to electron beam furnaces for processing metallic materials and, more particularly, to apparatuses and methods for controlling and limiting the interaction of electron beams generated by adjacent electron beam guns mounted within an electron beam furnace.
DESCRIPTION OF THE INVENTION BACKGROUND
A variety of different processes and apparatuses have been developed over the years for obtaining relatively pure metals or alloys. One such apparatus that has been developed to separate the slag and burn off or evaporate volatile impurities from molten metal material is known as an electron beam furnace. Such furnaces are disclosed, for example, in U.S. Pat. No. 4,027,722 to Hunt and U.S. Pat. No. 4,932,635 to Harker.
In general, an electron beam furnace includes a vacuum chamber that has a hearth and crucible system therein. A number of electron beam guns are typically mounted in the vacuum chamber above the hearth to melt metals that are introduced into the chamber. As the metal is melted, it flows into the crucible to be re-solidified into an ingot. The electron beam from each gun can be deflected and scanned over the surfaces of the metal. The deflection of the electron beam is typically controlled by computers and electromagnetic coils in the base of each electron beam gun which serve to deflect the beam in accordance with changes in the magnetic fields. The use and construction of such electron beam guns are known in the art as exemplified by those electron beam guns disclosed in U.S. Pat. No. 3,857,014 to Prudkovsky et al. and U.S. Pat. No. RE 35,024 to Hanks.
The generation of electron beams by multiple electron beam guns in close proximity to each other can result in undesirable electromagnetic interaction between the beams. Changes in deflection or beam power of one gun can cause a change of deflection in an adjacent gun, which also influences the gun adjacent to it and so on. That interaction can make it difficult to control the beams to obtain the desired result. In addition, because the interaction of the electron beams is largely a function of the location of the electron beam guns relative to each other within the vacuum chamber, the further away from the metal that the electron guns are located, the greater the likelihood of electron beam interaction. Thus, the size of the vacuum chamber is often dictated by the number and location of electron beam guns. Small vacuum chambers require more frequent cleaning to remove the buildup of condensate material therein that could hamper and possibly lead to contamination of the material passing therein.
Thus, there is a need for apparatuses and methods for limiting the interaction between beams of adjacently mounted electron beam guns.
There is a further need for apparatuses and methods for improving the ability to control electron beam guns within an electron beam furnace.
There is still another need for apparatus having the above-mentioned advantages that is relatively inexpensive to manufacture and install.
Another need exists for an electron beam furnace that has means for limiting the interaction between the beams generated by electron beam guns mounted therein.
SUMMARY OF THE INVENTION
In accordance with a particularly preferred form of the present invention, there is provided an apparatus for limiting interaction between beams generated by at least two electron beam guns mounted within an electron beam furnace having a superstructure. The apparatus may include a planar barrier sized to extend between at least two electron beam guns and a superstructure hanger connected to the planar barrier.
The subject invention may also comprise an electron beam furnace that includes a vacuum chamber that has an upper portion and a lower portion. The furnace also has a hearth assembly located within the lower portion of said vacuum chamber and at least two electron beam guns mounted within the vacuum chamber above the hearth assembly. In addition, the furnace includes at least one planar barrier suspended from the upper portion of the vacuum chamber such that it extends between at least two electron beam guns.
The subject invention may also comprise a method for limiting interaction between electron beams generated by at least two electron beam guns within a vacuum chamber of an electron beam furnace. The method includes suspending a barrier from an upper portion of the vacuum chamber such that the barrier extends between the electron beams produced by the electron beam guns.
It is a feature of the present invention to provide magnetic shield barriers within an electron beam furnace to limit undesirable interaction between the beams of adjacent guns.
It is another feature of the present invention to provide magnetic shield barriers that are relatively inexpensive to manufacture and install.
Yet another feature of the present invention is to provide magnetic shield barriers that enable the electron beam guns to be positioned farther from their targets which enables larger vacuum chambers to be employed in electron beam furnaces. Larger chambers reduce the frequency of clean-outs required because the condensate collection can be placed further away from the melting process and can be provided with a larger surface area which results in a slower buildup of condensate.
Accordingly, the present invention provides solutions to the shortcomings of prior furnaces that employ electron beam guns. Those of ordinary skill in the art will readily appreciate, however, that these and other details, features and advantages will become further apparent as the following detailed description of the preferred embodiments proceeds.
REFERENCES:
patent: Re. 32932 (1989-05-01), Harket et al.
patent: Re. 35024 (1995-08-01), Hanks
patent: 3265801 (1966-08-01), Eaton
patent: 3303320 (1967-02-01), Muller
patent: 3343828 (1967-09-01), Hunt
patent: 3857014 (1974-12-01), Prudkovsky et al.
patent: 4027722 (1977-06-01), Hunt
patent: 4932635 (1990-06-01), Harker
patent: 5034590 (1991-07-01), Yamamoto
patent: 5100463 (1992-03-01), Harker
patent: 5263689 (1993-11-01), Menzies et al.
patent: 5291940 (1994-03-01), Borofka et al.
Grosse Ingo A.
Hainz, II Leonard C.
Hall Mark A.
Hoang Tu Ba
Oregon Metallurgical Corporation
Viccaro Patrick J.
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