US3132198A - Electron beam furnace - Google Patents

Electron beam furnace Download PDF

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Publication number
US3132198A
US3132198A US166119A US16611962A US3132198A US 3132198 A US3132198 A US 3132198A US 166119 A US166119 A US 166119A US 16611962 A US16611962 A US 16611962A US 3132198 A US3132198 A US 3132198A
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US
United States
Prior art keywords
electron
electron beam
furnace
enclosure
gun
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US166119A
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English (en)
Inventor
Bois Andrew O Du
Howard R Harker
Charles W Hanks
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Stauffer Chemical Co
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Stauffer Chemical Co
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Filing date
Publication date
Priority to BE627166D priority Critical patent/BE627166A/xx
Priority to NL287742D priority patent/NL287742A/xx
Application filed by Stauffer Chemical Co filed Critical Stauffer Chemical Co
Priority to US166119A priority patent/US3132198A/en
Priority to GB1506/63A priority patent/GB976678A/en
Priority to FR921514A priority patent/FR1354890A/fr
Priority to CH45363A priority patent/CH405528A/de
Application granted granted Critical
Publication of US3132198A publication Critical patent/US3132198A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/16—Remelting metals
    • C22B9/22—Remelting metals with heating by wave energy or particle radiation
    • C22B9/228—Remelting metals with heating by wave energy or particle radiation by particle radiation, e.g. electron beams
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
    • H01J37/305—Electron-beam or ion-beam tubes for localised treatment of objects for casting, melting, evaporating, or etching

Definitions

  • This invention relates to an electron beam furnace, and, more particularly, to an electron beam furnace in which materials are heated to melting and in which the electron beam sources are isolated from materials being melted in order to minimize the risk of gases which are frequently released and ionized during the melting, being attracted to the beam sources to establish a short circuiting flow of electrons.
  • materials are bombarded by high-energy electrons which are projected in a beam from sources called electron guns.
  • the materials may be positioned or fed into the furnace to a target zone overlying the open top of a crucible or mold where the material is melted and caused to drop downwardly into the mold.
  • the top of the material in the mold is itself heated in order to maintain a molten pool of metal on top of the ingot so that, as the lower portion of the ingot cools, it is built up uniformly.
  • an object of this invention to provide an electron beam furnace including means for isolating the electron source from the gases and vapors released during melting.
  • the last-mentioned object is accomplished by providing a magnetic field with curved lines of force arching across the ribbon-shaped beam, after it passes through the slit, whereby the beam is simultaneously deflected in a direction perpendicular to its width and converged to a narrow width.
  • a horizontal shield is provided within the main furnace envelope at or below the level of the target which is to be bombarded and heated, to isolate the electron beam target from the electron guns.
  • the electron guns are disposed below the shield and aimed to project their beams upward through narrow slits in the shield, and for this purpose an elongate gun filament is provided so that the beam is also long and narrow in cross-section, or ribbon-shaped.
  • the beam is then placed under the influence of a magnetic field adapted to reshape it as well as to guide it onto the target.
  • the magnetic field includes arching flux lines crossing the beam path above the shield and disposed with respect to the motion of the electrons, so that the diverting forces imparted at right angles to the lines of force include converging components which act in opposition against the width of the beam, i.e. its long cross-sectional dimension, effectively to compress the width while permitting the beam to spread in the other dimension. Under the influence of these arching lines of force, the cross-section of the beam gradually assumes a more nearly circular configuration.
  • the shield through which the electron beam is projected is at the electric potential of the anode component of the electron gun anode, in order to reduce the tendency for gaseous ions to be attracted past the shield into the field of the electron gun.
  • the electrons after passing through the slit in the shield, the electrons are in an electrically field-free region, and undergo no appreciable change in speed, although their directions are altered by the magnetic field.
  • heavier ions including those of the material vaporized during the melting process are not influenced by the magnetic field to the same extent as are the much lighter electrons, and are not accelerated by an electric field, the region above the field being electrically field-free.
  • any ions that do get through the slits and into the electric field of the guns move in less curved trajectories than the electrons do, and thus do not bombard the cathode. Isolation of the gun from all ions within the melting chamber is enhanced by the extremely limited access to the electron guns afforded by the narrow slit in the shielding enclosure.
  • FIG. 1 is an elevational view in partial section of an electron beam furnace embodying the present invention
  • FIG. 2 is a horizontal section view taken along line 2--2 of FIG. 1;
  • FIG. 3 is a partial horizontal section view showing the influence of the magnetic field 'on the electron beams.
  • FIG. 4 is a partial vertical view showing the influence of the magnetic field in a horizontal plane.
  • the electron beam furnace of this invention includes an outer enclosure or envelope 10 containing a crucible or mold 12 which may, if desired, be formed with a water-cooled jacket 14.
  • the mold 12 is open at the top 15, so that raw material 16 above the mold may be melted at 16a to drip into the mold or crucible and form a molten pool 17 on the top of the ingot 18 into which it is ultimately solidified and withdrawn through an opening 20 in the bottom of the furnace 10 by any suitable means (not shown).
  • the raw material to be melted may be fed by any suitable means, which are here shown merely for purposes of schematic illustration, as feed rollers 21, in order progressively to bring the end portion to a target or melt zone overlying the open top 15 of the mold 12. There, it is subjected to bombardment and progressively melted by a series of electron beams 24 projected from a plurality of electron guns 25, each influencing a filament 26, a cathode 27 and an anode 28.
  • the filament 26 may be an elongated rod or, as shown in FIG. 2, it may be formed of elongated hairpin configuration. Whatever its specific form, the filament 26 is designed to project a thin but wide electron beam.
  • Straddling each electron gun 25 is a generally U-shaped magnet 30 including a coil 31 and pole pieces 32 which converge progressively toward their outer ends, as shown in FIG. 2, for a purpose hereinafter to be described.
  • a floor or shield 40 is provided around the crucible 12 above the level of the electron guns 25 in order to isolate the guns from the target zones, at the end of 16a of the raw material and in the open top of the crucible. From both of the target zones gases may be released during melting and could short out the electron guns if the ions thereof drift into the field of the gun to set up a flow of electrons.
  • the shield 40 is provided to prevent invasion of the electron guns by such gaseous ions. If desired, the shield 40 could be surrounded by a plurality of heat radiating panels which afford a labyrinth path for removal of gases while minimizing heat losses by radiating heat back toward the source at the center of the furnace.
  • a single vertical panel 41 forming a partial heat shield which also further isolates the electron guns from the source of released gases.
  • the floor 40 and panel 41 are formed of non-magnetic material, such as copper, so as to afford no substantial effect upon the magnetic field generated between the pole faces 32.
  • the floor or shield 40 is maintained at the potential of the anode 28, as by means of a mounting strap 43 to form a barrier to gaseous ions that might otherwise be attracted to the field of the electron guns.
  • Both the electron gun and the shield 40 may be energized from a conventional power supply 42.
  • each electron gun 25 Provided in the floor or shield 40 above each electron gun 25 is a narrow slit 44 through which the electron bears are aimed, their particular size and location being closely controlled in View of the electron velocities and the influencing magentic field.
  • the slits are of elongate configuration .so that the electron beam issuing from each gun is of a long and narrow cross-section aimed to pass freely through the appropriate slit 44.
  • the compression deflecting forces are further intensified by the converging paths of the electrons. The strength of the deflecting forces continues through the outward trajectory of the electron beam because the converging pole pieces 32 generate a field between them which is of gradually increasing strength toward their ends to compensate for the reduction in field strength due to vertical distance from the pole pieces.
  • the converging pole pieces also generate arcuate lines of force between them which, acting on the vertical velocity vectors of the electrons, provide converging deflecting forces further to compress the width of the beam.
  • the field lines of force arch outwardly of the furnace 10. Consequently, the deflecting forces at right angles to these lines of force, considered with the vertical velocity vectors of electrons emerging from the plane of the paper in FIG. 4 are also converging as shown by the arrows F.
  • the magnetic field arches in substantially the same direction.
  • the magnetic field is barrellike in configuration and the electrons projected from the guns 25 travel within the barrel. Therefore, throughout the electron trajectory upward between the converging pole pieces, across above the pole pieces and downward beyond the ends of the pole pieces the magentic field continuously arches over the paths of the electrons in the same relative direction, with resultant converging deflecting forces.
  • This barrel configuration can be enhanced by rounding the ends of the pole pieces 32 as shown in FIG. 1 so that the flux path emerging perpendicular to the edge of the pole pieces arches both inwardly and upwardly. Since the electrons follow naturally diverging paths with respect to the other cross-sectional axis of the beam, the beam is spread in the plane of FIG. 1 and compressed in directions parallel to the planes of FIGS. 2 and 3. As a result, the cross-sectional dimensions of the beam are substantially equal along both axes when the beam enters the crucible.
  • Vapor ions formed during vaporization such as those of the metal itself, are of course not influenced by the magnetic field to nearly the same extent as are the much lighter electrons. Consequently, there is little likelihood that such relatively heavy particles would be influenced by the magnetic field to traverse the reverse path of the bombarding electron beams and move from the melt zones into the electron guns. Further, the extremely limited access to the zone of the guns provided by the narrow slits sharply reduces the possibility of vapor molecule deposition of the electron gun components.
  • large windows or ducts 48 In direct communcation with the main furnace envelope 10 through large windows or ducts 48 are evacuation chambers 50 through which the envelope 10 is continuously evacuated by vacuum pumps 52 to a pressure in the order of one micron of mercury.
  • large evacuation windows 56 are formed in the heat radiating panels 41 and they are arranged in substantial alignment with the main furnace evacuation windows 48 so that direct paths of gas and vapor evacuation are provided to the evacuation chambers 50.
  • the windows 56 of the inner panels 41 are provided with a series of vanes or baflles 58 to provide vapor condensation surfaces and heat conserving radiation members.
  • the shield or floor 40 and the pole faces 32 are themselves water-cooled to protect them against the intense heat within the furnace enclosure 10 resulting from electron bombardment. This water-cooling may be accomplished by securing copper tubing or the like (not shown) to these elements.
  • An electron beam furnace comprising a furnace enclosure
  • an electron gun including an elongate thin filament for projecting a high-energy electron beam having a long and narrow cross section upward in said enclosure
  • a horizontal shield disposed adjacent to and above the gun between said electron gun and said melt zone, said shield including a long, narrow slit therethrough through which said electron beam is aimed, and
  • a generally U-shaped magnet having converging pole pieces on opposite sides of said electron gun so that the rearwardly and upwardly arching lines of force tend to exert converging deflecting forces against the width of an electron beam moving upward and forward therethrough after it passes through said slit and to guide the beam in a curved path onto the material to be treated.
  • An electron beam furnace comprising a furnace enclosure
  • said horizontal wall having a narrow slit extending therethrough of substantially the same cross-sectional dimension as that of said electron beam
  • high vacuum evacuating means in direct communication with said furnace enclosure both above and below said horizontal wall for maintaining the furnace enclosure at a high vacuum.
  • An electron beam furnace comprising a furnace enclosure
  • said horizontal wall defining a plurality of long, narrow slits therethrough
  • each of said electron guns being aimed to project a high-energy beam of long and narrow cross-section upward through a separate one of said slits
  • magnetic field generating means establishing a magnetic field exerting laterally inward deflecting forces against the long cross-sectional dimension of said beam while guiding said beam in a curved path to bombard the material
  • high vacuum evacuating means in direct communica tion with said furnace enclosure both above and below said horizontal wall.
  • pole pieces having ends converging toward each other toward said crucible for maximizing the focusing of electrons therein.
  • An electron beam furnace comprising,
  • said horizontal wall having at least one narrow elongated slit therethrough
  • At least one electron gun disposed beneath and on the opposite side of said wall from said melting zone and having an elongate filament for generating a ribbon-shaped beam having substantially the same cross-sectional dimensions as said wall slit,
  • said electron gun being laterally displaced with respect to said wall slit
  • a magnet field generator establishing a magnetic field having lines of force substantially parallel to said electron gun filament in the vicinity thereof for guiding said electron beam in a curved trajectory through said slit for maximized protection of the electron gun from ion bombardment
  • said magnetic field generator further establishing said magnetic field with lines of force in a barrel shape curving over at least a part of said melting zone and concave with respect to said melting zone to laterally converge and longitudinally extend the beam cross-section so that the beam impact pattern is substantially circular for maximized beam heating efiiciency

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Toxicology (AREA)
  • Manufacturing & Machinery (AREA)
  • Health & Medical Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US166119A 1962-01-15 1962-01-15 Electron beam furnace Expired - Lifetime US3132198A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
BE627166D BE627166A (fr) 1962-01-15
NL287742D NL287742A (fr) 1962-01-15
US166119A US3132198A (en) 1962-01-15 1962-01-15 Electron beam furnace
GB1506/63A GB976678A (en) 1962-01-15 1963-01-14 Improvements in or relating to electron beam furnaces
FR921514A FR1354890A (fr) 1962-01-15 1963-01-15 Four à faisceau électronique
CH45363A CH405528A (de) 1962-01-15 1963-01-15 Elektronenstrahlofen

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US166119A US3132198A (en) 1962-01-15 1962-01-15 Electron beam furnace

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US3132198A true US3132198A (en) 1964-05-05

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US166119A Expired - Lifetime US3132198A (en) 1962-01-15 1962-01-15 Electron beam furnace

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US (1) US3132198A (fr)
BE (1) BE627166A (fr)
CH (1) CH405528A (fr)
GB (1) GB976678A (fr)
NL (1) NL287742A (fr)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3202794A (en) * 1963-02-18 1965-08-24 Thermionics Lab Inc Permanent magnet transverse electron beam evaporation source
US3274417A (en) * 1962-05-30 1966-09-20 Haefer Rene Electronic evaporator
US3308325A (en) * 1962-09-08 1967-03-07 Bendix Balzers Vacuum Inc Electron beam tube with ion shield
US3343828A (en) * 1962-03-30 1967-09-26 Air Reduction High vacuum furnace
US3420977A (en) * 1965-06-18 1969-01-07 Air Reduction Electron beam apparatus
US3446934A (en) * 1968-01-30 1969-05-27 Air Reduction Electron beam heating apparatus
US3454814A (en) * 1966-07-29 1969-07-08 Atomic Energy Commission Tubular vapor source
US3469066A (en) * 1966-09-30 1969-09-23 Nasa Method and device for preventing high voltage arcing in electron beam welding
US3472999A (en) * 1967-02-12 1969-10-14 Nippon Electric Co Electron beam generating device
US3474220A (en) * 1967-05-17 1969-10-21 Webb James E Device for preventing high voltage arcing in electron beam welding
US3483417A (en) * 1967-07-26 1969-12-09 Air Reduction Electron beam deflecting means
US3497602A (en) * 1966-12-16 1970-02-24 Air Reduction Apparatus for producing and directing an electron beam in an electron beam furnace
US3857014A (en) * 1971-08-25 1974-12-24 A Khotina Electron beam generator
US4208042A (en) * 1978-05-13 1980-06-17 Leybold-Heraeus Gmbh Evaporating crucible
US4620081A (en) * 1984-08-03 1986-10-28 The United States Of America As Represented By The United States Department Of Energy Self-contained hot-hollow cathode gun source assembly

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2252052A (en) * 1938-10-17 1941-08-12 Hartford Nat Bank & Trust Co Sublimating apparatus
US2291948A (en) * 1940-06-27 1942-08-04 Westinghouse Electric & Mfg Co High voltage X-ray tube shield
US2715693A (en) * 1947-05-05 1955-08-16 Stephen M Macneille Deep collimating slot
US3046936A (en) * 1958-06-04 1962-07-31 Nat Res Corp Improvement in vacuum coating apparatus comprising an ion trap for the electron gun thereof
US3068309A (en) * 1960-06-22 1962-12-11 Stauffer Chemical Co Electron beam furnace with multiple field guidance of electrons

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2252052A (en) * 1938-10-17 1941-08-12 Hartford Nat Bank & Trust Co Sublimating apparatus
US2291948A (en) * 1940-06-27 1942-08-04 Westinghouse Electric & Mfg Co High voltage X-ray tube shield
US2715693A (en) * 1947-05-05 1955-08-16 Stephen M Macneille Deep collimating slot
US3046936A (en) * 1958-06-04 1962-07-31 Nat Res Corp Improvement in vacuum coating apparatus comprising an ion trap for the electron gun thereof
US3068309A (en) * 1960-06-22 1962-12-11 Stauffer Chemical Co Electron beam furnace with multiple field guidance of electrons

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3343828A (en) * 1962-03-30 1967-09-26 Air Reduction High vacuum furnace
US3274417A (en) * 1962-05-30 1966-09-20 Haefer Rene Electronic evaporator
US3308325A (en) * 1962-09-08 1967-03-07 Bendix Balzers Vacuum Inc Electron beam tube with ion shield
US3202794A (en) * 1963-02-18 1965-08-24 Thermionics Lab Inc Permanent magnet transverse electron beam evaporation source
US3420977A (en) * 1965-06-18 1969-01-07 Air Reduction Electron beam apparatus
US3454814A (en) * 1966-07-29 1969-07-08 Atomic Energy Commission Tubular vapor source
US3469066A (en) * 1966-09-30 1969-09-23 Nasa Method and device for preventing high voltage arcing in electron beam welding
US3497602A (en) * 1966-12-16 1970-02-24 Air Reduction Apparatus for producing and directing an electron beam in an electron beam furnace
US3472999A (en) * 1967-02-12 1969-10-14 Nippon Electric Co Electron beam generating device
US3474220A (en) * 1967-05-17 1969-10-21 Webb James E Device for preventing high voltage arcing in electron beam welding
US3483417A (en) * 1967-07-26 1969-12-09 Air Reduction Electron beam deflecting means
US3446934A (en) * 1968-01-30 1969-05-27 Air Reduction Electron beam heating apparatus
US3857014A (en) * 1971-08-25 1974-12-24 A Khotina Electron beam generator
US4208042A (en) * 1978-05-13 1980-06-17 Leybold-Heraeus Gmbh Evaporating crucible
US4620081A (en) * 1984-08-03 1986-10-28 The United States Of America As Represented By The United States Department Of Energy Self-contained hot-hollow cathode gun source assembly

Also Published As

Publication number Publication date
NL287742A (fr)
GB976678A (en) 1964-12-02
CH405528A (de) 1966-01-15
BE627166A (fr)

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