USH135H - Electromagnetic levitation casting apparatus having improved levitation coil assembly - Google Patents

Electromagnetic levitation casting apparatus having improved levitation coil assembly Download PDF

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Publication number
USH135H
USH135H US06/622,131 US62213184A USH135H US H135 H USH135 H US H135H US 62213184 A US62213184 A US 62213184A US H135 H USH135 H US H135H
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United States
Prior art keywords
slotted annular
electromagnetic
slugs
field producing
liquid metal
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Abandoned
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US06/622,131
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English (en)
Inventor
John P. Wallace
Hugh R. Lowry
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General Electric Co
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General Electric Co
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Assigned to GENERAL ELECTRIC COMPANY, A NY CORP. reassignment GENERAL ELECTRIC COMPANY, A NY CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: WALLACE, JOHN P., LOWRY, HUGH R.
Priority to US06/622,131 priority Critical patent/USH135H/en
Priority to ZA852453A priority patent/ZA852453B/xx
Priority to AU40835/85A priority patent/AU578086B2/en
Priority to IN286/CAL/85A priority patent/IN164073B/en
Priority to HU851719A priority patent/HU194755B/hu
Priority to FI852086A priority patent/FI78852C/fi
Priority to BR8502605A priority patent/BR8502605A/pt
Priority to PH32378A priority patent/PH23690A/en
Priority to JP60126397A priority patent/JPH0688103B2/ja
Priority to ES544134A priority patent/ES8700099A1/es
Priority to AT85107459T priority patent/ATE41338T1/de
Priority to CA000484022A priority patent/CA1240476A/en
Priority to DE8585107459T priority patent/DE3568721D1/de
Priority to EP85107459A priority patent/EP0166346B1/de
Priority to KR1019850004328A priority patent/KR920000514B1/ko
Priority to PT80668A priority patent/PT80668B/pt
Priority to MX205702A priority patent/MX159204A/es
Publication of USH135H publication Critical patent/USH135H/en
Application granted granted Critical
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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
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/02—Use of electric or magnetic effects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/14—Plants for continuous casting
    • B22D11/145—Plants for continuous casting for upward casting
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/20—Metals
    • G01N33/205—Metals in liquid state, e.g. molten metals

Definitions

  • This invention relates to an improved apparatus for the casting of continuous metal rods.
  • the invention relates to an electromagnetic levitation casting apparatus having an improved levitation coil assembly for the continuous casting of metals in long lengths using an electromagnetic levitation casting process described in U.S. Pat. No. 4,414,285--issued Nov. 8, 1983 for "Continuous Metal Casting Method, Apparatus and Product"--Hugh R. Lowry and Robert T. Frost, inventors, and assigned to the General Electric Company.
  • the levitation electromagnetic field is in the form of an upwardly travelling electromagnetic field that both constrains the molten metal column and maintains it in a substantially weightless condition with reduced hydrostatic head in the solidification region of the heat exchanger/casting vessel whereby the solidified rod product can be continuously withdrawn by a rod removal mechanism acting on the solidified rod product after it has passed through the heat exchanger/casting vessel.
  • the General Electric levitation casting process (hereinafter referred to as the GELEC (TM) process) requires a strong, upward travelling electromagnetic field to be created in the interior of the tubular casting vessel/heat exchanger assembly which supports and contains the liquid metal column while it is solidifying.
  • the levitating field is generated by currents in the range of 500-1,000 amperes flowing in a 36-turn levitation coil. Since reasonably sized insulated wires cannot carry such currents continuously, water cooled copper tubing currently is used for the levitation coil. This coil is placed in close proximity to the exterior wall of the heat exchanger which in turn surrounds a tubular casting vessel made of refractory material. Such a coil maximizes the magnetic field intensity within the interior of the tubular casting vessel.
  • a practical solid state generator of high frequency polyphase power in the range of 10-50 kilowatts has an output voltage of roughly 100-500 volts.
  • This high voltage, low current output must go through a step-down transformer with forced air or water cooling in order to produce the low voltage, high current required to energize the present levitation coil design described briefly above.
  • a high frequency 10-50 kilowatt, three phase step-down transformer (or three single phase transformers) is expensive, large and somewhat difficult to design and fabricate. Further, the step-down transformer and associated high current supply cables or bus bars feeding the levitation coil assembly used to date have not been entirely satisfactory and a simpler, less expensive design is very desirable.
  • the present invention provides a unique and non-obvious solution to the above-discussed problems through the use of an improved levitation coil assembly that makes use of a novel arrangement of flux concentration devices. While the use of flux concentration devices in the production of large magnetic fields in order to improve the coil life of multi-turn coils used to produce the large magnetic fields has been described in the prior art, it has not been used or suggested for use heretofore with respect to the electromagnetic levitation of molten metals.
  • One prior art description of a flux concentrator appears in an article entitled "Flux Concentrator For High Intensity Pulsed Magnetic Field" by Y. B. Kim and E. D. Platner in the Review of Scientific Instruments--7/59--pages 524-533.
  • a unique and non-obvious levitation coil assembly employing flux concentration devices for use in the electromagnetic levitation of molten metal
  • Each of the slotted annular slugs is inductively coupled to an electromagnetic field producing coil having a large number of turns surrounding the slug.
  • Each slotted annular slug serves to concentrate the magnetic field produced by the coil to substantially the interior cross sectional area of the tubular casting vessel it surrounds, and functions as a current step-up transformer.
  • a separate slotted annular slug (or stack of thin slugs) and associated surrounding electromagnetic field producing coil is provided for each phase of the multi-phase excitation provided for the GELEC (TM) levitation coil assembly.
  • slotted annular slug magnetic flux concentrator devices provide a number of important and non-obvious advantages.
  • One advantage is that it will minimize or eliminate coil induced field variations caused by inevitable variations in the construction of multi-turn liquid cooled copper tube coils used heretofore.
  • a further advantage is that the slotted annular slug members will be uniformly closer to the cast metal column and will increase the electromechanical restoring force on the column thereby allowing better control of the cast metal column diameter.
  • the improved levitator assembly using the slotted annular slug flux concentrators allows a higher levitating magnetic field to be generated with a lower impedance device. This in turn reduces the voltage requirements for the levitator coil assembly and the total power requirements and provides greater electrical efficiency.
  • a 40% decrease in impedance would reduce both the required driving voltage and input power by 40%.
  • the flux density at the inside periphery of the energizing coil is effectively transferred to, and reproduced at, the inner periphery of the central opening in the flux concentrator disk.
  • This displacement of the flux from the energizing coil periphery to the disk inner periphery of the central opening in the disk i.e., the surface closest to the levitated metal
  • the flux density at the center of the coil is higher with the flux concentrator disk in place than without it, which is desirable.
  • the gradient (i.e., change in flux density with distance) of the flux from the center point outward is also much higher with the flux concentrator disk in place.
  • the gradient of the flux is what determines the inward containment pressure on the levitated metal column so a higher value of gradient is desirable.
  • the input impedance of the levitator coil changes considerably when the molten copper rises up into the levitator coil/heat exchanger assembly at the start of a casting run.
  • This impedance change is caused by the electrical load coupled into the levitator coil when copper (molten and solidified) exists in the interior of the coil.
  • a desired value of the levitator coil current set before the run by adjusting the inverter output voltage must therefore be reset quickly to the desired value after the start of the run because of this change in coil impedance.
  • the addition of the flux concentrator device virtually eliminates this problem because the highly conductive disks will have already lowered the energizing coil impedance drastically and introduction of molten metal in close proximity to the central opening of the concentrator disks will have little or no further effect on the energizing coil impedance.
  • the flux concentrator device therefore makes it possible to more accurately set an optimum levitator coil current before casting starts and hold this value of current during the critical start-up operation.
  • FIG. 1 is a diagramatic sketch of a slotted, annular slug flux concentrator device employed in constructing an improved electromagnetic levitating coil assembly according to the invention
  • FIG. 2 is a voltage versus distance characteristic curve indicative of the flux field of a multi-turn electromagnetic induction coil and illustrates the difference in flux concentration achieved where the coil has only an open air center as opposed to a coil having a slotted annular slug flux concentrator such as shown in FIG. 1, inserted therein;
  • FIG. 3 is a cross sectional view of one embodiment of an improved levitation coil assembly constructed according to the invention.
  • FIG. 4 is a schematic functional block diagram of an electromagnetic levitation casting apparatus having an improved levitation coil assembly constructed according to the invention
  • FIG. 5 is a plan view of an alternative construction for a slotted annular slug flux concentrator employed in fabricating an alternative form of the improved levitation coil assembly shown in cross section in FIG. 6;
  • FIGS. 7, 7A and 7B illustrate still another embodiment of the invention suitable for use in casting flat plate having a rectangular cross section.
  • FIG. 1 is a planar end view showing a slotted annular slug 11 surrounded by a multi-turn coil 12 of insulated wire which surrounds the outer periphery of annular slug 11.
  • the multi-turn coil 12 is excited from an alternating current power source 13.
  • a central opening 14 is formed in annular slug 11 and a non-conductive slot 15 extends from the outer periphery of slug 11 all the way through to central opening 14.
  • An instantaneous current flow through the outer primary multi-turn coil 12 in the direction indicated by the arrows 16 induces an opposite current flow around the outer periphery of annular slug 11 indicated by the arrows 17.
  • the ampere-turns in slug 11 must essentially equal the ampere-turns in the energizing primary coil 12, the current flow in the slug 11 (which is the equivalent of a single-turn secondary coil) will be very large. Without a non-conductive slot as shown at 15 in the slug, the current 17 would be equally high but, because of the skin effect phenomena, would flow predominately near the outer edge of the disc and the electromagnetic field produced within the interior central opening 14 would be minimal.
  • the outer multi-turn primary energizing coil 12 and slotted slug arrangement 11 acts as a current step-up transformer so that a high voltage, low current energizing coil 12 of relatively large diameter and having a large number of turns will produce a low voltage, high current flow around the central opening 14 of annular slug 11. Opening 14 is much smaller in diameter than coil 12 and hence creates a high magnetic flux within the central opening. It is this highly concentrated, central magnetic flux which is needed for practicing the GELEC (TM) process.
  • the field producing current flow that provides the levitating electromagnetic force necessary in the GELEC (TM) process is essentially the flow around the inner periphery of central opening 14 of slotted annular slug 11.
  • This feature provides a major advantage in that the apparent inner diameter of the energizing coil that produces the levitating field is reduced by the insertion of the slotted annular slug as if it were replaced by a coil of the same number of turns per meter, but with the inner diameter of the slotted annular slug 11.
  • the annular slotted slug member 11 therefore acts as a flux concentrator and effectively increases the flux produced by the multi-turn coil by a factor substantially equal to the total area of multi-turn coil 12 cross section divided by the inside area of central opening 14.
  • FIG. 2 of the drawings The results of measurement tests run with a magnetic field sensing probe on the concentrating effects of a slotted annular slug member 11 is shown in FIG. 2 of the drawings.
  • the curve shown in dotted line illustrates the magnetic field flux density B measured in Gausses from the center of a multi-turn coil such as 12 without the presence of a field concentrating slotted annular slug member 11.
  • the curve shown in solid line in the upper right corner of FIG. 2 illustrates the results of the measurements taken after insertion of a slotted annular field concentrator 11. This data was taken with respect to a multi-turn energizing coil having ten turns wound in a planar loop having a 6.5 centimeter diameter.
  • the slotted annular slug member 11 of copper had a corresponding 6.5 cm outer diameter, a 1.5 cm diameter central opening and was 0.6 cm thick.
  • the multi-turn coil was excited by a 1.0 microsecond pulse repeated at a frequency of one kilohertz. From FIG. 2, it will be seen that the introduction of the slotted annular slug member 11 results in a large integrated increase in flux within the central opening 14.
  • the levitating field producing current flow that will drive the metal casting process is essentially the flow around the central opening 14 of the slotted annular slug member 11.
  • This provides a major advantage over previously used multi-turn coil driving arrangements in that the current flow path is not constrained so that the current flow path and resulting electromagnetic force it produces can concentrate at those points around the periphery of the central opening 14 where the molten metal column passing through opening 14 has a larger diameter. This in effect increases the apparent stiffness of the containment effects of the levitating electromagnetic fields acting as a mold and should assist in decreasing the mean variation in the cast solidified rod product diameter.
  • FIG. 3 of the drawings illustrates a preferred construction for an improved levitation coil assembly for use in the GELEC (TM) apparatus which employs a plurality of slotted annular slug members such as shown in FIG. 1 as flux concentration devices.
  • TM GELEC
  • FIG. 3 an elongated tubular casting vessel is shown at 19 which is fabricated from a high temperature refractory material such as, but not limited to, ceramics, graphite, zirconia or the like. Casting vessel 19 is cooled by an annular liquid cooled heat exchanger 21 that immediately surrounds tubular casting vessel 19.
  • means are provided for continuously supplying a liquid coolant through the annular heat exchanger 21.
  • liquid metal shown at 23 is delivered into the lower end of tubular casting vessel 19 where it rises.
  • molten metal 23 rises in the tubular casting vessel 19 it will be levitated by the levitating electromagnetic field and cooled substantially at a molten metal-solidified metal interface shown at 24 and thereafter can be withdrawn from the top portion of tubular casting vessel 19 as solidified rod product 25.
  • the manner in which the solidified rod product 25 is withdrawn also will be described more fully hereafter with respect to FIG. 4 of the drawings.
  • a small gap indicated at 22 is created between the exterior surfaces of the levitated metal column 23 and the interior surrounding surfaces of the tubular casting vessel 19 by the containment effect of the electromagnetic field. When the liquid metal column solidifies it will further shrink in diameter thus maintaining this gap as the rod cools.
  • electromagnetic levitation field producing means are provided.
  • This means is comprised by a novel levitator coil flux concentrator assembly according to the invention for producing an electromagnetic levitation field that reduces the hydrostatic head of the liquid metal column in the solidification region 24 and maintains the liquid metal column in a substantially weightless condition within this region while simultaneously maintaining a predetermined dimensional relationship between the outer surface of the liquid metal column and the interior surrounding surfaces of the casting vessel 19 by the containment affect of the levitating electromagnetic field.
  • a novel levitator coil flux concentrator assembly for producing an electromagnetic levitation field that reduces the hydrostatic head of the liquid metal column in the solidification region 24 and maintains the liquid metal column in a substantially weightless condition within this region while simultaneously maintaining a predetermined dimensional relationship between the outer surface of the liquid metal column and the interior surrounding surfaces of the casting vessel 19 by the containment affect of the levitating electromagnetic field.
  • tubular casting vessel 19 serves not only as a casting vessel but also as a heat exchanger. Accordingly, hereafter, this component will be referred to as tubular casting vessel/heat exchanger 19, 21.
  • the new and improved levitator assembly shown in FIG. 3 is comprised by a plurality of slotted arrays of annular slugs shown at 11A, 11B and 11C which surround the portion of the length of the tubular casting vessel/heat exchanger 19, 21 within which the liquid metal column is to be levitated while simultaneously being cooled.
  • each of the slotted annular slug arrays 11A, 11B and 11C is comprised by a stacked array of slotted annular unitary monolithic discs or slugs which are electrically insulated one from the other and are similar in construction to the slotted annular member shown in FIG. 1.
  • each of the slug arrays 11A, 11B, 11C may vary in accordance with design criteria for a particular installation.
  • Each monolithic slug is provided with a thin electrical insulating coating which in the case of aluminum slugs may comprise an anodized layer of aluminum oxide.
  • Each of the slug arrays 11A, 11B, 11C thus comprised are also electrically insulated from each other by insulating members 10.
  • Each of the respective slug arrays 11A, 11B and 11C are inductively coupled to an associated multi-turn electromagnetic field producing coil such as 12A, 12B or 12C with the multi-turn coils being formed from a large number of turns of insulated wire which may optionally be further insulated from the exterior circumferential surfaces of the respective associated slug member 11A, 11B or 11C by respective cylindrically shaped insulated surfaces 10A, 10B or 10C in the manner shown in FIG. 3.
  • each of the respective multi-turn windings 12A, 12B and 12C is excited with a respective phase excitation current supplied from a multi-phase power source as will be described hereafter with relation to FIG. 4.
  • the slug arrays 11A, 11B and 11C will operate in the manner described above with relation to FIG. 1 as a current step-up transformer for converting the relatively high voltage, low current supplied to the respective phase windings 12A, 12B and 12C to a low voltage, high current that flows around the periphery of central opening 14.
  • This high current produces a concentrated flux passing through the central openings of the respective slug array and acts on the liquid metal column 23 contained in the tubular casting vessel/heat exchanger 19, 21.
  • an upwardly travelling electromagnetic wave is produced which acts on liquid metal column 23 in the solidification region 24 so as to maintain the liquid metal column in this region in a substantially weightless condition and which simultaneously provides a containment field effect that maintains a minimal gap space between the exterior surfaces of the liquid metal column 23 and the interior surfaces of the tubular casting vessel/heat exchanger 19, 21.
  • molten metal to be cast is contained in a holding furnace (not shown) from which it is delivered into a casting crucible 31 as shown by the arrow 32 on an as required basis to maintain a desired level of liquid metal within the casting assembly 35 comprised by the tubular casting vessel/heat exchanger portion 19, 21 and slotted annular slug member assembly 11A, 11B, 11C and surrounding multi-turn coils 12A, 12B and 12C described with relation to FIG. 3.
  • the casting assembly 35 is mounted on and extends vertically upward from crucible 10 to an open upper end through which the freshly cast solidified rod product 25 is withdrawn by means for removing solidified metal and for controlling the rate of production of solidified metal comprised by a withdrawal assembly for supplying the solidified metal to a precooling station 36 via an intermediate quenching station 36A.
  • a withdrawal assembly for supplying the solidified metal to a precooling station 36 via an intermediate quenching station 36A.
  • the freshly cast and precooled solidified rod product 25 may be delivered via withdrawal rolls 37 and 38 to tandem hot-rolling stations 39 and 41 (should such be required) and then finally cooled to ambient temperature and coiled at a coiling station 42 for storage and delivery to a user of the cast product.
  • the solidified rod product 25 can be withdrawn by withdrawal rolls 37 and 43, cooled to ambient temperature and then stored without further processing.
  • the rate of withdrawal of the solidified metal product is controlled.
  • molten metal is displaced from crucible 31 as a liquid metal column such as shown at 23 in FIG. 3 into the casting assembly 35 by gravity or pressurized flow from the holding furnace (not shown).
  • the holding furnace delivers the molten metal into crucible 31 at intervals or continuously as necessary during the continuous casting process.
  • the molten metal column 23 (FIG. 3) is thus initially established and thereafter maintained at a level above that at which the upwardly travelling levitation electromagnetic wave produced by the levitator coil assembly becomes effective to reduce or even eliminate the column hydrostatic head.
  • the upwardly travelling, levitation electromagnetic waves are produced in the manner described previously with respect to FIG.
  • Controller 26 is controlled independently in frequency and power by a respective frequency control circuit 27 and power control circuit 28 of known construction.
  • FIG. 4 While a three phase arrangement has been shown in FIG. 4 for simplicity of illustration, six phase excitation of the levitating coil assembly is preferred. However, it is believed obvious to those skilled in the art that other multi-phase power supply systems and coil arrangements could be employed. For example, as shown in FIG. 6, twelve multi-turn coils 12A, 12(-B'), 12C, 12(-A'), 12B and 12(-C'), repeated a second time, are disposed in vertical spaced relationship around the improved levitation coil assembly 35 as windings arranged substantially normal to the casting vessel/heat exchanger tube 19 axis.
  • These coils are electrically interconnected to form a serially arranged, two-six phase coil system that physically extends over two wavelengths at the excitation frequency of the coils to thereby determine the length of the levitation zone.
  • Such an arrangement also is illustrated schematically in FIG. 5 of the above referenced U.S. Pat. No. 4,414,285, the disclosure of which is hereby incorporated into this application in its entirety, but is described as a twelve phase system. If it is desired to employ only a single, six phase coil system extending over a single wavelength of the excitation frequency of the coils, then the number of multi-turn coils 12A, 12(-B'), etc., shown in FIG.
  • the improved multiphase levitator coil assembly described above produces a progressive upwardly travelling wave which will move at a speed proportional to the distance between successive closed flux loops and the frequency of excitation.
  • the primary multi-turn excitation windings 12A, 12B and 12C are arrayed vertically upward along the length of the levitator tube assembly 35 so that the liquid metal column and newly solidified metal product in all but the lowermost section of levitator tube assembly 35 can be levitated throughout the casting operation to a substantially weightless condition. In this condition the liquid metal column 23 has substantially a zero hydrostatic head within the solidification region of levitator tube 35 so that the liquid metal column is substantially pressureless.
  • pressureless it is meant that there is no substantial continuous pressure contact between the outer surface of the liquid metal column and the interior surrounding surfaces of the casting vessel 19 and the liquid metal column is without substantial hydrostatic head in the critical solidification zone 24.
  • frictional and adhesive forces as well as the force of gravity acting on the solidifying column are reduced to a minimum in the solidification zone.
  • the heat exchanger arrangement shown in FIG. 3 provides in effect a condition approaching a water quench by effectively enveloping the rising liquid metal column 23 in a continuous (during operation), rapidly flowing, turbulent but fairly small cross section annular stream of liquid coolant supplied via the upper manifold or header 33 and drained through the lower header 34.
  • This heat transfer capability can be further enhanced by the inclusion of short, internal, annular ribs within annular cooling chamber 21 which serve as barriers to laminar flow of the liquid coolant, causing turbulence in the cooling liquid as it travels downwardly through the annular heat exchanger from the upper manifold 33 to the lower manifold 34.
  • the inside diameter of the tubular graphite casting vessel 19 shown in FIG. 3 and the operating parameters of the system such as the frequency and field strength of the upwardly travelling levitating electromagnetic field are selected so that there is a minimum annular gap such as indicated at 22 between the exterior surfaces of the liquid metal column 23 and the interior surfaces of tubular casting vessel 19 in the solidification region defined by the interface 24. This is true below the point where solidification of the liquid metal column results in shrinkage of the column cross section area although such shrinkage is quite small.
  • the gap indicated at 22 in FIG. 3 is schematic and not intended as an accurate representation of the location or the magnitude of the dimensions of this annular gap.
  • the temperature of the solidified rod product is quite critical and must be maintained within a relatively narrow range. For example, if the cast rod product is copper and is much above 1,000 degrees Centigrade (white hot) it will be too weak to support itself and transmit the tensile forces needed to move the rod from the casting operation in levitator tube assembly 35 through the optionally employed prequenching and precooling chambers 36A, 36 via withdrawal rolls 37, 38.
  • the rod temperature is less than about 850 degrees Centigrade, it will be too cold for the "hot” rolling which optionally may be provided by tandem rolls 39, 41 if this is desired to create a fine grain, homogenous structure which is optimum for subsequent cold drawing (or cold working) of the solidified metal.
  • the intense agitation and stirring action of the electromagnetic levitation field results in cast rod having a moderate size grain structure that appears to be useable "as-is”.
  • the casting speed i.e. line speed of movement of the liquid metal column through the levitator tube assembly 35
  • the levitation field strength and excitation frequency should be established at a value calculated for the particular size and resistivity of the metal being cast to give a levitation ratio in the range between 75% to 200% where levitation ratio is defined as the ratio of the levitation force per unit of length of the liquid metal to the weight per unit length of the liquid metal as expressed in U.S. Pat. No. 4,414,285 at the bottom of column 11 and the top of column 12.
  • the multi-turn coils 12A, 12B and 12C are fabricated from ordinary high temperature insulated wire. Since the wires would be carrying relatively modest currents, it is likely that they would not have to be cooled separately with their own liquid cooled heat exchanger arrangement although the provision of forced cooling air flow over the coils may be necessary.
  • the slotted annular slug members 11 of course are in close proximity to the annular heat exchanger water jacket 21 and have a relatively large conducting cross section so that they can be maintained at a modest temperature despite the high currents flowing through them.
  • the thickness of the slotted annular discs comprising annular slugs 11A, 11B and 11C can be adjusted over a wide range to enhance this capability.
  • the slots 15 formed in the discs comprising the slotted annular slugs do not have to be lined-up vertically, since the discs comprising the slug are insulated one from the other, but instead could be oriented from one disc to another in such a way that the overall field distortion (if any) resulting from the slots can be minimized.
  • the central opening within the slotted annular slug members 11A, 11B, 11C, etc. can be of any desired shape in cross section. For example, either oval, hexagonal or other desired cross sectional configuration could be used to cast solidified rod product of a similar cross section.
  • the outer periphery of the slotted annular slugs do not have to be circular in shape and could be oval, hexagonal, or other desired configurations.
  • the outer surfaces of the flux concentrator slotted annular slugs do not have to be smooth but in an effort to get better coupling to their respective multi-turn energizing windings, they could be provided with grooves cut annularly around the outer surface. If a single continuous multi-turn winding is to be used, a continuous spiral groove could be employed. Additionally, in accordance with good engineering practice, it may be desireable to make the multi-turn energizing coils 12A, 12B, 12C from one or a few layers of square or rectangularly cross section conductors instead of several layers of wound round conductors. This type of construction would minimize the effective air gap between the energizing coil and its associated flux concentrator slotted annular slug.
  • Energizing coils formed from rectangular cross section conductors because of their larger effective conducting cross sections, also would have lower I 2 R heating losses than coils made from multiple turns of insulated round wires.
  • the choice of insulation used in fabricating the multi-turn energizing coil conductors also is a matter of good engineering practice. For example, use of a high temperature wire enamel, polymeric coatings or tape, and other similar newly developed high temperature insulating materials conceivably could eliminate the need for or reduce the cost and complexity of cooling arrangements for the coil assemblies.
  • ferromagnetic ferrite material flux shaping members could be incorporated into the assembly along with the slotted annular slug members in order to "shape-up" the electromagnetic field produced by the flux concentrator assembly into a desired field pattern.
  • Another method of field shaping might be to cut out segments or additional field shaping slots around either the inner or outer peripheries of the slotted annular slug members whereby currents flowing in an undesired manner are forced into current paths providing a more optimum magnetic field configuration.
  • a user of the GELEC process incorporating the new and improved levitation coil assembly constructed in this manner then could change over from making 8 mm diameter rod, for example, to 5 mm diameter rod by only changing the internal slotted annular slug flux concentrator-heat exchanger assembly and not have to remove or alter the primary, multi-turn, outer energizing coils themselves.
  • FIGS. 7, 7A and 7B of the drawings illustrate one such arrangement.
  • FIG. 7 is a top planar view of only one phase winding of an installation suitable for use in fabricating plates from molten metal having a rectangular cross section as shown at 59 in FIGS. 7 and 7A.
  • the rectangular cross section molten metal plate 59 is formed by reason of the generally rectangular flux concentrator slug member 55 having an elongated rectangular central opening 61 and a gap formed therein as shown at 58 in both FIGS. 7 and 7B of the drawings.
  • the rectangular-shaped flux concentrator 55 is disposed within an outer primary multi-turn coil 56 best seen in FIGS. 7 and 7B.
  • a plurality of nonconducting, thin ferrite plates shown at 57 are disposed over and under the multi-turn primary coil 58 and flux concentrator slug member 55 subassembly as best shown in FIG. 7A.
  • the thin ferrite plate members 57 have specially-shaped trapezoidal configurations as best seen in FIG. 7 for concentrating the magnetic flux in the longer dimension flat section of the molten metal plate 59 whereby the plate is provided with a generally flat rectangular cross section as illustrated in FIG. 7. Similar to the embodiment of the invention shown in FIGS.
  • a graphite lined, water cooled heat exchanger that comprises the casting vessel/heat exchanger 19, 21 is positioned between the flux concentrator slotted annular slug assembly 11A, 11B and 11C and the liquid metal column 23 being levitated. It will be appreciated therefor that relatively heavy currents will be induced in the liquid cooled heat exchanger in this construction and will result in rather substantial losses. In order to avoid such losses, a preferred embodiment of the invention is provided which is illustrated in FIGS. 5 and 6 of the drawings.
  • the slotted annular slug flux concentrator plate asssembly shown generally at 11 in FIG. 6 is mechanically strong and rigid. If the flux concentrator slugs 11 are made of a metal having good heat conductivity but also capable of providing electrical isolation between the respective slug members, such an assembly would also be capable of transfering a considerable amount of heat to a liquid coolant flowing from the upper and lower electrically insulating header manifolds 33 and 34 down through a series of cooling apertures shown at 51 in FIG. 5 formed in each of the slug members 11.
  • tubular casting vessel 19 could comprise a refractory lining vessel such as graphite, zirconia, TZM and the like which is press fit directly into the inner opening 14 of the stacked array of slotted annular slugs 11A, 11(-B'), 11C, etc., that form a liquid cooled slotted annular slug flux concentrator assembly 35.
  • Assembly 35 functions in the same manner as the flux concentrator assembly 35 described with relation to FIG. 4. However, in the FIGS.
  • each of the slotted annular slug flux concentrators 11A, 11(-B'), 11C, etc. comprises a relatively thick monolithic slug whose axial dimensions are substantially equal to the axial dimension of its associated primary multi-turn driving coil such as 12A, 12(-B'), 12C, etc.
  • These multi-turn coils are respectively excited from a three phase current supply and controller 26 and are connected thereto in the manner described more fully above and with respect to FIG. 5 of the drawings of U.S. Pat. No. 4,414,285 referenced above.
  • the improved levitator coil and heat exchanger assembly should be designed so that the slotted annular slug members are press fit within the surrounding associated primary multi-turn driving coil and still are electrically insulated from their associated primary multi-turn coil, the tubular refractory liner 19 and from adjacent slug members.
  • the slotted annular slug members 11 employed in the FIG. 6 arrangement would be fabricated from a soft aluminum material such as aluminum 1100.
  • the cooling passageway 51 could be drilled or cast therein and each of the annular slug members then anodized by known electrochemical means. The anodizing treatment will result in the production of an aluminum oxide film being grown around all of the exposed surfaces of the slug to a thickness of about 2/1000 of an inch.
  • the aluminum oxide film thus provided will electrically insulate each of the slotted annular slug members one from the other as well as from its associated primary multi-turn driving coil and the tubular refractory liner 19.
  • the stacked array of slotted annular slug members 11A, 11(-B'), 11C, etc. is pressed together with cooling passageways 51 aligned and forming liquid tight seals between the respective slug members. Since the interior surfaces of the cooling passageways 51 likewise will have an aluminum oxide insulating surface grown therein, the liquid coolant will be unable to electrically short out between adjacent slug members.
  • copper, aluminum or other tubes could be inserted into the aligned openings 51 and then expanded to provide a press fit, thereby further insuring that no leakage occurs between adjacent slug members.
  • the anodized coating of aluminum oxide prevents the copper or other conductive tubes from shorting between the slotted annular slug members.
  • the individual slotted annular slug flux concentrator members will be electrically insulated one from the other by the anodized aluminum coating so that the large flux producing currents induced around the periphery of the inner openings 14 thereof can be individually controlled to produce the desired upwardly travelling electromagnetic levitation field required to practice the GELEC (TM) process.
  • TM GELEC
  • the thermal resistivity of thin aluminum oxide anodized coating is minimal because of its thinness.
  • the cooling characteristics of the assembled levitating coil structure are comparable to or perhaps even better that the cooling provided with the assembly shown in FIG. 3.
  • other aluminum materials such as aluminum 2024 could be employed in forming the slugs although such material is known to have a somewhat higher resistivity than aluminum 1100 and would lead to somewhat higher losses during operation of the levitator coil assembly.
  • Such cooling channels should be positioned several electrical skin depths away from the inner and outer peripheries of the respective slug members so as not to impede or distort the flow of the levitation field producing currents.
  • This invention describes an electromagnetic levitation casting apparatus having an improved levitator coil assembly for use in the continuous casting of metal products of long length such as rod made from copper, aluminum, nickle and various alloys of these and other metals.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Food Science & Technology (AREA)
  • Continuous Casting (AREA)
  • General Induction Heating (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)
  • Reciprocating, Oscillating Or Vibrating Motors (AREA)
  • Investigating Or Analysing Biological Materials (AREA)
  • Medicines Containing Material From Animals Or Micro-Organisms (AREA)
  • Control Of Vehicles With Linear Motors And Vehicles That Are Magnetically Levitated (AREA)
  • Control And Other Processes For Unpacking Of Materials (AREA)
  • Treatment Of Fiber Materials (AREA)
  • Mold Materials And Core Materials (AREA)
  • Disintegrating Or Milling (AREA)
  • Apparatuses For Generation Of Mechanical Vibrations (AREA)
US06/622,131 1984-06-19 1984-06-19 Electromagnetic levitation casting apparatus having improved levitation coil assembly Abandoned USH135H (en)

Priority Applications (17)

Application Number Priority Date Filing Date Title
US06/622,131 USH135H (en) 1984-06-19 1984-06-19 Electromagnetic levitation casting apparatus having improved levitation coil assembly
ZA852453A ZA852453B (en) 1984-06-19 1985-04-01 Electromagnetic levitation casting apparatus having improved levitation coil assembly
AU40835/85A AU578086B2 (en) 1984-06-19 1985-04-02 Electromagnetic levitation in continuous casting
IN286/CAL/85A IN164073B (de) 1984-06-19 1985-04-12
HU851719A HU194755B (en) 1984-06-19 1985-05-07 Continuous casting apparatus of electromagnetic suspension with improved suspension winding
FI852086A FI78852C (fi) 1984-06-19 1985-05-24 Kontinuerligt arbetande gjutanordning.
BR8502605A BR8502605A (pt) 1984-06-19 1985-05-27 Aparelho de fundicao continua e aperfeicoamento no dito aparelho de fundicao continua
PH32378A PH23690A (en) 1984-06-19 1985-06-07 Electromagnetic levitation casting apparatus having improved levitation coil assembly
JP60126397A JPH0688103B2 (ja) 1984-06-19 1985-06-12 改良した浮揚コイルアセンブリを有する電磁浮揚鋳造装置
ES544134A ES8700099A1 (es) 1984-06-19 1985-06-13 Aparato para la colada con solidificacion continua
AT85107459T ATE41338T1 (de) 1984-06-19 1985-06-14 Elektromagnetische schwebegiesseinrichtung mit einer spulenanordnung.
CA000484022A CA1240476A (en) 1984-06-19 1985-06-14 Electromagnetic levitation casting apparatus having improved levitation coil assembly
DE8585107459T DE3568721D1 (en) 1984-06-19 1985-06-14 Electromagnetic levitation casting apparatus having improved levitation coil assembly
EP85107459A EP0166346B1 (de) 1984-06-19 1985-06-14 Elektromagnetische Schwebegiesseinrichtung mit einer Spulenanordnung
KR1019850004328A KR920000514B1 (ko) 1984-06-19 1985-06-19 전자 부양 주조 장치
PT80668A PT80668B (pt) 1984-06-19 1985-06-19 Equipamento de fundicao com levitacao electromagnetica com montagem de uma bobina de levitacao aperfeicoada
MX205702A MX159204A (es) 1984-06-19 1985-06-19 Mejoras en un aparato de colado continuo con sistema de levitacion electro-magnetica

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US06/622,131 USH135H (en) 1984-06-19 1984-06-19 Electromagnetic levitation casting apparatus having improved levitation coil assembly

Publications (1)

Publication Number Publication Date
USH135H true USH135H (en) 1986-09-02

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US06/622,131 Abandoned USH135H (en) 1984-06-19 1984-06-19 Electromagnetic levitation casting apparatus having improved levitation coil assembly

Country Status (17)

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US (1) USH135H (de)
EP (1) EP0166346B1 (de)
JP (1) JPH0688103B2 (de)
KR (1) KR920000514B1 (de)
AT (1) ATE41338T1 (de)
AU (1) AU578086B2 (de)
BR (1) BR8502605A (de)
CA (1) CA1240476A (de)
DE (1) DE3568721D1 (de)
ES (1) ES8700099A1 (de)
FI (1) FI78852C (de)
HU (1) HU194755B (de)
IN (1) IN164073B (de)
MX (1) MX159204A (de)
PH (1) PH23690A (de)
PT (1) PT80668B (de)
ZA (1) ZA852453B (de)

Families Citing this family (5)

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Publication number Priority date Publication date Assignee Title
JPH0660087U (ja) * 1993-01-22 1994-08-19 カツラ電工株式会社 レールコンセント用接続器
GB9304340D0 (en) * 1993-03-03 1993-04-21 Atomic Energy Authority Uk Metal casting
EP1361432B1 (de) * 1995-03-14 2012-02-22 Nippon Steel Corporation Verfahren und Vorrichtung zur Bestimmung die Sauberkeit von Metal
CA2207579A1 (fr) 1997-05-28 1998-11-28 Paul Caron Piece frittee a surface anti-abrasive et procede pour sa realisation
CN118268514B (zh) * 2024-06-03 2024-08-23 成都利华强磁浮连铸科技有限责任公司 一种推斥力均匀的磁悬浮连铸系统

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3872379A (en) 1973-08-29 1975-03-18 Magnetic Analysis Corp Eddy current testing apparatus using slotted monoturn conductive members
US4294304A (en) 1976-06-14 1981-10-13 Cem - Compagnie Electro-Mecanique Electromagnetic centrifuging inductor for rotating a molten metal about its casting axis
US4414285A (en) 1982-09-30 1983-11-08 General Electric Company Continuous metal casting method, apparatus and product

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2352612B1 (fr) * 1976-05-26 1980-11-14 Pont A Mousson Procede et installation pour la coulee continue par centrifugation de produits tubulaires en fonte notamment
SE443525B (sv) * 1980-07-02 1986-03-03 Gen Electric Sett och apparat for kontinuerlig gjutning
LU82874A1 (fr) * 1980-10-20 1982-05-10 Arbed Procede et installation pour la fabrication continue d'ebauches creuses en metal
ZA852590B (en) * 1984-07-02 1986-02-26 Gen Electric Continuous metal tube casting method,apparatus and product

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3872379A (en) 1973-08-29 1975-03-18 Magnetic Analysis Corp Eddy current testing apparatus using slotted monoturn conductive members
US4294304A (en) 1976-06-14 1981-10-13 Cem - Compagnie Electro-Mecanique Electromagnetic centrifuging inductor for rotating a molten metal about its casting axis
US4414285A (en) 1982-09-30 1983-11-08 General Electric Company Continuous metal casting method, apparatus and product

Also Published As

Publication number Publication date
FI852086L (fi) 1985-12-20
ES8700099A1 (es) 1986-10-16
EP0166346B1 (de) 1989-03-15
CA1240476A (en) 1988-08-16
DE3568721D1 (en) 1989-04-20
PT80668A (en) 1985-07-01
JPH0688103B2 (ja) 1994-11-09
ES544134A0 (es) 1986-10-16
HU194755B (en) 1988-03-28
MX159204A (es) 1989-04-27
BR8502605A (pt) 1986-02-04
JPS6127147A (ja) 1986-02-06
FI78852C (fi) 1989-10-10
KR860000111A (ko) 1986-01-25
IN164073B (de) 1989-01-07
AU578086B2 (en) 1988-10-13
KR920000514B1 (ko) 1992-01-14
FI78852B (fi) 1989-06-30
ZA852453B (en) 1986-03-26
EP0166346A3 (en) 1986-08-20
ATE41338T1 (de) 1989-04-15
FI852086A0 (fi) 1985-05-24
PH23690A (en) 1989-09-27
AU4083585A (en) 1986-01-02
PT80668B (pt) 1987-06-17
EP0166346A2 (de) 1986-01-02
HUT38856A (en) 1986-07-28

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