US2983973A - Methods and apparatus for melting and casting metals in a vacuum - Google Patents

Methods and apparatus for melting and casting metals in a vacuum Download PDF

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Publication number
US2983973A
US2983973A US629557A US62955756A US2983973A US 2983973 A US2983973 A US 2983973A US 629557 A US629557 A US 629557A US 62955756 A US62955756 A US 62955756A US 2983973 A US2983973 A US 2983973A
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shroud
mold
chamber
vacuum
interior
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US629557A
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English (en)
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Conrad A Parlanti
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Priority to BE603658A priority patent/BE603658A/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D18/00—Pressure casting; Vacuum casting
    • B22D18/06—Vacuum casting, i.e. making use of vacuum to fill the mould
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B5/00—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated
    • F27B5/04—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated adapted for treating the charge in vacuum or special atmosphere

Definitions

  • zzj-ziz 'Ihis invention relates to the casting of metals, and pertains more particularly to methodsand apparatus for melting and casting metals in a vacuum.
  • Figure 2 is a front elevation.
  • J h r Figure3 is a side elevation.
  • Figure 4 is a section onfthe line 4--4 of Figure 1.
  • Figure 5 is a section through a mold shroud.
  • Vacuum casting apparatuses now known and used in the melting. and casting of metals is of two general types.
  • the apparatus comprises a sealed melting or furnace chamber containing a crucible equipped with. suitable means for melting metal therein, usually by electrical induction.
  • the chamber is connected to a suitable vacuum pump adapted to create and maintain the desired degree of vacuum within the chamber
  • the ehamberis . also provided with suitable means v .
  • the mold or molds are placed within the furnace chamber. But since the vacuum which is maintained within the chamber retards the transfer of heatto the walls of the chamber through which the heat must pass for dissipation, the rate of cooling is slow.
  • the vacuum should be maintained at least until the cast metal isisolidified, andconsiderable time must be permitted to elapse before the vacuumcan be released and the chamber opened for the removal of theca'stings.
  • Means are. usually .provided for water cooling the mold, so that themold' may be removed fairly promptly.
  • y n this type, also, means a'refrequently provided by harged without breaking 2,983,973 Patented May 16, 1961 the vacuum in the furnace chamber.
  • Such means usually comprise an auxiliary, charging chamber provided with suitable valves and connections to permit the auxiliary chamber to be opened to the furnace to permit recharging, and to be sealed ofit while receiving an additional charge.
  • the apparatus may be kept in continuous operation for long periods of time.
  • the walls of the furnace chamber are fabricated of steel and provision is made for water cooling the walls.
  • a common form of construction is a double wall with provision forcirculating cooling water between the walls.
  • I provide a furnace chamber, the walls of which, instead of being water cooled, are constructed of aluminum or aluminum alloy, with both the inside and outside surfaces of said walls anodized to provide a thin skin of aluminum oxide thereon.
  • the anodizing of such surfaces greatly increases the reflectivity of the surfaces and affects very substan- Thus;
  • a mold shroud to receive and hold the casting mold while the molten metal-is being poured and coo-led.
  • Such mold shroud comprises a container having an interior space of a size to receive the mold, which said containerv is also formed of aluminum or aluminum alloy having walls which'are anodized on both their interior and exterior surfaces.
  • the anodized surfaces retard the ab-j sorption of heat from the mold and casting into the shroud and increase the rate of dissipation of heat from the exterior surfaces of the shroud.
  • the tern-. perature of the walls of the shroud remains within toler-I able limits even when relatively high melting point metals such as titanium or steel are being cast.
  • Each mold shroud is provided with a valve closure which may be opened to permit molten metal to be poured into the mold, and which may be closed to seal the shroud and the enclosed mold.
  • Each shroud is also provided with valves and connections through which the sealed shroud may be evacuated to create and maintain a vacuum therein, and through which non-oxidizing and preferably inert gas may be introduced, if desired, all as hereinafter explained.
  • the shroud and furnace chamber are provided with vacuum tight connections by means of which the shroud; may be connected to the furnace chamber while metal is being poured into the mold.
  • the furnace chamber. connection is provided with a valve for sealing the chain ber whenever the shroud is removed.
  • the apparatus com-' prises a furnace chamber 1, preferably cylindical in shape, and having a removable cover 2 at one end.
  • the interior of the chamber is connected by a conduit 3 to a vacuum pump 4 of sufiicient capacity to maintain a relativelyhigh vacuum within the chamber during the,
  • a suitable valve 5 may be mounted in the conduit 3 to seal off the chamber from the vacuum pump when desired.
  • a crucible 6 which is preferably surrounded by an induction coil 7 for heating and melting metal which is charged into the crucible.
  • Suitable connections for the supply of electric current and for cooling the induction coil are supplied as known in the art, and are not shown in detail herein.
  • the crucible may be supported within the chamber in any suitable manner, but means are preferably provided by which the crucible may be manipulated from the exterior of the chamber so that it may be tilted to pour molten metal into a launder or trough 8 through which it is conducted to the casting molds as hereinafter described.
  • Means are also preferably provided for exterior manipulation of the crucible cover Q, and of the stirring rod 10, but all such means are well known in the art, as exemplified by the disclosure of US. Patent No. 2,625,719, and are not shown in detail herein, since they form no part of the present invention.
  • Means are also provided for charging the crucible 6 comprising a conduit 11 terminating in a chute 12 which passes through the chamber wall in position to discharge material into the crucible.
  • the conduit 11 is provided with a vacuum tight valve 13 and, if desired, means (not shown) may be provided for recharging the crucible without breaking the vacuum in the furnace chamber.
  • the launder 8 extends laterally into a cylindrical launder chamber 14 which is in open communication with the furnace chamber, and terminates in a spout 18 located immediately above a vertical passage 15 which extends downwardly from the launder chamber for connection to the mold shrouds as hereinafter described.
  • a vacuum tight valve 16 is mounted in the passage 15 so that the passage may be sealed except when the valve is opened to permit molten metal to be poured into the casting molds as hereinafter described.
  • Said valve is provided with a flange 17 for purposes hereinafter described.
  • the mold shrouds 21 may be of any convenient size and shape to hold a casting mold 22, and in the embodiment illustrated comprise a container having a lid 23 on which the mold is carried by means of an adjustable platform 24 supported on the lid by rods 25.
  • the lid 23 is held in sealed engagement with the flange 26 by clamps 27.
  • a vacuum tight valve 28 is mounted on the lid 23, said valve having a flange 29, adapted to seat against the flange 17 when it is desired to pour molten metal as hereinafter described.
  • the mold shrouds are also provided with means by which the interior of the shroud may be connected to a vacuum pump, or alternatively to a supply of inert or other gas.
  • a vacuum pump or alternatively to a supply of inert or other gas.
  • two separate conduits 30 and 31 controlled by valves 32 and 33, respectively, one of which may be connected to a vacuum pump and the other to a supply of gas.
  • a series of mold shrouds are provided for economical operation of the apparatus, and each of the mold shrouds is preferably encircled by a band 34 which engages and supports the mold shroud on a carriage 35.
  • Each of the carriages 35 is provided with rollers 36 which ride on the rails 37 of track 38.
  • the mold shrouds may be. moved along the rails 37 to a position directly below the passage 15. At this position, the mold shroud is in position to be engaged by the movable platform 41 of the hydraulic jack 42, the operation of which is controlled by an operator through a valve 43 controlled by a pedal 44.
  • the crucible 6 is first charged with the metal to be cast, and valves 13 and 16 are closed tightly. Valve 5 remains open and the vacuum pump 4 is operated to create and maintain the desired degree of vacuum in the furnace chamber. At the same time, the induction heating coil 7 is energized to heat and melt the metal in the crucible.
  • each mold shroud is closed tightly.
  • One of the valves 32, 33 is also closed tightly While the conduit containing the other valve is connected to a vacuum pump to evacuate the interior of the mold shroud.
  • the other valve 32, 33 is closed, and the mold shroud is ready for use.
  • the first of the evacuated mold shrouds is moved into position beneath the passage 15.
  • the hydraulic jack 42 is then operated to raise the mold shroud to bring the flange 29 into sealing engagement with the flange 17.
  • valves 16 and 28 are opened to bring the interior of the mold shroud into open communication with the interior of the furnace chamber.
  • the crucible is now tilted to pour metal into the launder 8 from which it flows through the spout 18 into the mold 22.
  • valves 16 and 28 are closed, the jack 42 and the supported mold shroud are lowered to replace the mold shroud on a carriage 35 on which it may then be moved away.
  • Another evacuated mold shroud may then be moved immediately into casting position.
  • the mold shroud may be moved as soon as metal has been poured, without waiting for even partial solidification of the casting, thus substantially increasing the possible rate of casting.
  • the filled mold and its mold shroud are moved to another position where the conditions within the mold shroud may be controlled as desired while the casting is solidifying and cooling.
  • the shroud may be connected to a vacuum pump with which a vacuum may be maintained for as long a period as desired.
  • the cooling of the metal may be hastened if the shroud is filled with a gaseous atmosphere which may assist in transferring heat, and the mold shroud may be connected to a suitable supply of the desired gas.
  • Non-oxidizing gases such as hydrogen, nitrogen, helium, argon and the like may be introduced, depending on the condition desired.
  • the walls of the furnace cham ber 1 are constructed of aluminum or aluminum alloy, and both the inside and outside surfaces of the walls are anodized to provide a thin skin or layer of aluminum oxide thereon.
  • the method of melting and casting high melting point metals such as titanium and steel in vacuum which comprises placing the metal in a sealed chamber the walls of which are formed of a metal selected from the group consisting of aluminum and aluminum alloys, the interior and exterior surfaces of the walls of said chamber having been anodized to increase the reflectivity of both surfaces thereof, the anodized exterior surface of said chamber being the sole means of dissipating heat from said chamber, creating a vacuum in said chamber, and melting said metal in said chamber while maintaining a vacuum therein.
  • the method claimed in claim 1 which includes placing a mold in a sealed shroud which is separated from said chamber and movable with respect thereto, creating a vacuum in said shroud, moving said shroud into sealed contact with said chamber, establishing open communication between the interior of said chamber and the interior of said shroud while maintaining a vacuum in both, pouring molten metal from said chamber into said mold, breaking communication between the interior of said chamber and the interior of said shroud while continuing to maintain a vacuum in both, removing said shroud from contact with said chamber, and cooling the molten metal in said mold before removing the mold from the shroud.
  • the method claimed in claim 1 which includes placing a mold in a sealed shroud formed of a metal selected from the group consisting of aluminum and aluminum alloys, the interior surfaces of the walls of said shroud having been anodized to increase the reflectivity of both surfaces thereof, said shroud being separated from said chamber and movable with respect thereto, creating a vacuum within said shroud, moving said shroud into sealed contact with said chamber, establishing open communication between the interior of said chamber and the interior of said shroud while maintaining a vacuum in both, forming molten metal from said chamber into said mold, breaking communication between the interior of said chamber and the interior of said shroud while continuing to maintain a vacuum in both, removing said shroud from contact with said chamber, and cooling the molten metal in said mold before removing the mold from the shroud.
  • the method of melting and casting metal in vacuum which comprises placing metal in a sealed chamber, creating a vacuum in said chamber, melting said metal in said chamber while maintaining a vacuum therein, placing a mold in a sealed shroud which is separated from said chamber and movable with respect thereto, creating a vacuum in said shroud, moving said shroud into sealed contact with said chamber and establishing open communication between the interior of said chamber and the interior of said shroud While maintaining a vacuum in both, pouring molten metal from said chamber into said mold, breaking communication between the interior of said chamber and the interior of said shroud while continuing to maintain a vacuum in both, removing said shroud from contact with said chamber, and cooling the molten metal in said mold before removing the mold from the shroud.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
US629557A 1956-12-20 1956-12-20 Methods and apparatus for melting and casting metals in a vacuum Expired - Lifetime US2983973A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US629557A US2983973A (en) 1956-12-20 1956-12-20 Methods and apparatus for melting and casting metals in a vacuum
BE603658A BE603658A (fr) 1956-12-20 1961-05-10 Procédés et appareils pour fondre et couler des métaux sous vide.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US629557A US2983973A (en) 1956-12-20 1956-12-20 Methods and apparatus for melting and casting metals in a vacuum

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3200455A (en) * 1962-04-04 1965-08-17 Howe Sound Co Method of shell mold casting
US3460604A (en) * 1964-12-16 1969-08-12 Howmet Corp Method for vacuum melting and casting
US3658119A (en) * 1968-04-03 1972-04-25 Airco Inc Apparatus for processing molten metal in a vacuum
US3840062A (en) * 1968-07-18 1974-10-08 M Kenney Continuous steel casting method

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1319500A (en) * 1919-10-21 Method
US2085450A (en) * 1934-04-23 1937-06-29 Rohn Wilhelm Apparatus for producing metallic ingots
GB543577A (en) * 1940-07-01 1942-03-04 Conrad Anthony Parlanti Improvements in and relating to the casting of non-ferrous metals
US2392267A (en) * 1943-03-11 1946-01-01 Queen City Steel Treating Co Nitriding apparatus
CA481181A (fr) * 1952-02-19 Aluminum Company Of America Traitement thermique pour articles metalliques
US2625719A (en) * 1950-09-27 1953-01-20 Nat Res Corp Vacuum casting apparatus
US2627014A (en) * 1950-08-25 1953-01-27 Wiegand Co Edwin L Radiant heater
GB723699A (en) * 1951-08-02 1955-02-09 Degussa Improvements relating to vacuum furnaces
GB732298A (en) * 1952-05-03 1955-06-22 Nat Lead Co Apparatus for casting refractory metals
US2825945A (en) * 1955-05-03 1958-03-11 Cons Electrodynamics Corp Apparatus for melting metal and successively casting into molds

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1319500A (en) * 1919-10-21 Method
CA481181A (fr) * 1952-02-19 Aluminum Company Of America Traitement thermique pour articles metalliques
US2085450A (en) * 1934-04-23 1937-06-29 Rohn Wilhelm Apparatus for producing metallic ingots
US2133634A (en) * 1934-04-23 1938-10-18 Rohn Wilhelm Electric induction furnace
GB543577A (en) * 1940-07-01 1942-03-04 Conrad Anthony Parlanti Improvements in and relating to the casting of non-ferrous metals
US2392267A (en) * 1943-03-11 1946-01-01 Queen City Steel Treating Co Nitriding apparatus
US2627014A (en) * 1950-08-25 1953-01-27 Wiegand Co Edwin L Radiant heater
US2625719A (en) * 1950-09-27 1953-01-20 Nat Res Corp Vacuum casting apparatus
GB723699A (en) * 1951-08-02 1955-02-09 Degussa Improvements relating to vacuum furnaces
GB732298A (en) * 1952-05-03 1955-06-22 Nat Lead Co Apparatus for casting refractory metals
US2825945A (en) * 1955-05-03 1958-03-11 Cons Electrodynamics Corp Apparatus for melting metal and successively casting into molds

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3200455A (en) * 1962-04-04 1965-08-17 Howe Sound Co Method of shell mold casting
US3460604A (en) * 1964-12-16 1969-08-12 Howmet Corp Method for vacuum melting and casting
US3658119A (en) * 1968-04-03 1972-04-25 Airco Inc Apparatus for processing molten metal in a vacuum
US3840062A (en) * 1968-07-18 1974-10-08 M Kenney Continuous steel casting method

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Publication number Publication date
BE603658A (fr) 1961-11-10

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