EP0056915A1 - Arrangement for direct induction melting in a cooled vessel with supplementary electromagnetic confinement of the contents - Google Patents

Arrangement for direct induction melting in a cooled vessel with supplementary electromagnetic confinement of the contents Download PDF

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Publication number
EP0056915A1
EP0056915A1 EP81401845A EP81401845A EP0056915A1 EP 0056915 A1 EP0056915 A1 EP 0056915A1 EP 81401845 A EP81401845 A EP 81401845A EP 81401845 A EP81401845 A EP 81401845A EP 0056915 A1 EP0056915 A1 EP 0056915A1
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EP
European Patent Office
Prior art keywords
cage
cold
inductor
confinement
side wall
Prior art date
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EP81401845A
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German (de)
French (fr)
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EP0056915B1 (en
Inventor
Jean Reboux
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Societe dApplications de la Physique Moderne et de lElectronique SAPHYMO Stel
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Societe dApplications de la Physique Moderne et de lElectronique SAPHYMO Stel
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    • 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
    • F27B14/00—Crucible or pot furnaces
    • F27B14/06—Crucible or pot furnaces heated electrically, e.g. induction crucible furnaces with or without any other source of heat
    • F27B14/061—Induction furnaces
    • F27B14/063—Skull melting type
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/22—Furnaces without an endless core
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0001—Heating elements or systems
    • F27D99/0006—Electric heating elements or system
    • F27D2099/0015—Induction heating
    • F27D2099/0016—Different magnetic fields, e.g. two coils, different characteristics of the same coil along its length or different parts of the same coil used

Definitions

  • the invention relates to a device for direct induction melting in a cold cage, known as a "self-crucible”, with additional electromagnetic confinement of the charge, in order to move it away from the inner side wall of this cage.
  • the charge to be melted is generally introduced into the cold cage, the bottom of which is closed by means of a hollow refractory or metallic insulating plate and cooled from above in a powdery or granular form.
  • a hollow refractory or metallic insulating plate When it is made up of a mixture of materials, at least one of which is cold insulating, the latter agglomerates, during melting, in the vicinity of the inner wall of the cold cage so as to form a thin sheath or electrically insulating film which covers it.
  • the load is metallic (that is to say metal or metal alloys) and cold conductive
  • this sheath formed in contact with the cold wall is also conductive and puts the insulated elements (segments in tube copper) of the cage in short circuit.
  • the electromagnetic confinement of a molten metal flow by means of an axial alternating magnetic field is known per se, for example, from the publications GB-A- 893 445, FR-A-1 509 962, 2 106 545, 2 160 281, 2 316 026 and 2 396 612.
  • the axial magnetic confinement field is generated using an inductor supplied with alternating current, coaxially surrounding the crucible or the nozzle carrying the pouring, substantially at its lower opening.
  • the ingot has surface irregularities in the form of longitudinal ridges, at the locations of the partitions between the segments of the cage, where the cooling effect is less effective.
  • a horizontal oven by direct induction with electromagnetic levitation of the load of solid conductive material has been described in the publication FR-A-1 508 992, where an inductor with three longitudinal strands (parallel to the horizontal axis), two of which are connected in parallel and one of which (the lower one) is connected in series with the others to form a levitation cradle, is surrounded by a cylindrical or solenoidal monospire inductor which ensures the heating of the metallic body and contributes to its maintenance in levitation, especially when it is in fusion.
  • Such a horizontal furnace without a crucible cannot be used with divided loads (powdery or grainy) and does not allow continuous casting or drawing of the ingots or crystals.
  • its maximum load is limited to a few kilograms because of the force necessary for levitation which opposes gravitation.
  • these "anti-parallel" inductors are formed using several conductive strands, parallel to the vertical axis of the ingot and connected in series so that the currents which flow through the neighboring strands are respectively in opposite directions, so to exert on the molten upper part of the ingot electromagnetic forces of repulsion (confinement) which are added to those generated by the main inductor and which are similar to those of the above-mentioned publication DE-B-1 147 714.
  • the present invention relates to a device for direct induction melting in a cage whose cylindrical side wall is formed by one or more "antiparallel" inductors which serve at the same time as a cold sheath and an additional containment device, making it possible in particular to receive pulverulent or granular fillers (divided into particles) of various materials which can be insulating or cold conducting or consist of mixtures of such materials.
  • This fusion device is oriented vertically to allow the casting of the molten material or the drawing of ingots (known per se) and, therefore, the additional confinement magnetic field does not have to overcome gravitation and can act on the molten part of the load, when it is cold insulating, to facilitate the formation of the agglomerated shell or gangue which replaces the crucible and whose increased thickness ensures better thermal insulation of the part in fusion.
  • the magnetic field generated by the currents flowing through the sections of the cage can also act on the unmelted upper part of the load, if their intensity exceeds a certain threshold.
  • the cold side wall of the cage is arranged such that it constitutes at the same time a confinement inductor of a type known per se, which is supplied by a second power generator of a high or medium second frequency and which comprises, in addition to the juxtaposed tubular sections, electrical connection means connecting together the adjacent ends of two neighboring tubular sections, so that these are respectively traversed by an alternating current in opposite directions, generating in the conductive part from the periphery of the load of the additional confinement forces.
  • a confinement inductor of a type known per se, which is supplied by a second power generator of a high or medium second frequency and which comprises, in addition to the juxtaposed tubular sections, electrical connection means connecting together the adjacent ends of two neighboring tubular sections, so that these are respectively traversed by an alternating current in opposite directions, generating in the conductive part from the periphery of the load of the additional confinement forces.
  • These electrical connection means can consist of conductive plates or transverse tube sections which join together, for example, by one of their respective adjacent ends, two neighboring tubular sections so as to form pin-shaped segments. to hair which are then juxtaposed in an electrically isolated manner to form the side wall of the cold cage.
  • the hairpin segments forming the side wall are respectively electrically connected in parallel, in series or in various series-parallel combinations, so that a set of inductor elements thus connected can have an impedance adapted to the frequency of the second generator.
  • the additional confining power provided by the second generator being a function of the diameter and the height of the cold cage and, consequently, of the volume of the load. It is generally between one tenth and one fifth of the power supplied by the first generator to the main inductor surrounding the cage.
  • a small proportion of a cold insulating substance is added to the charge to be melted, when all of its components are metallic (cold conductive). a melting point lower than that of the metal or alloy, to form a slag.
  • This slag preferably fluorite (or calcium fluoride) or silica, optionally mixed with adjuvants such as borates, has in the molten state a surface tension significantly lower than that of the metal to which it is mixed in the state pulverulent and it is, therefore, expelled from the stirred molten metal, towards its periphery where, under the effect of the cold cage, it solidifies, becoming again insulating.
  • a proportion by weight of 0.5 to 1.5 percent is used in relation to the total weight of the filler.
  • the conventional melting device of FIG. 1 comprises a heating inductor 1 of helical shape, made of copper tube and comprising several turns which cover a predetermined height.
  • the two ends 3, 4 of this inductor 1 are respectively brought together here at two output terminals (low impedance, for example) of a first power generator 2 which can generate an alternating current Il of high (30kHz - 10MHz) or of medium (1 - 30kHz) (industrial) frequencies which are respectively intended for the fusion of cold insulating refractory materials, such as oxides or silicates for example, or semiconductors, such as silicon, germanium or arsenide gallium, for example, and that of cold conductive materials, such as metals or metal alloys.
  • the power supplied to the inductor 1 is a function, in particular, of the nature (melting point, cold and hot resistivity, relative permeability up to the Curie point etc.) of the material, the volume of the charge to be melted (that is to say the diameter of the cold cage and the height of the inductor 1) and the coupling between the load and the inductor (the thickness of the cage).
  • the generator 2 must therefore be dimensioned so as to provide a power of between 50 and 250 kilowatts, for example.
  • the cold cage or "self-crucible” 5 comprises a cylindrical side wall 6 with vertical axis of symmetry, composed of a large number of juxtaposed tubular segments 7, which are of elongated shape and oriented parallel to the geometric axis or to the generator of the cylinder that they form together.
  • These segments 7 can be produced in sections of metal tube of rectangular, circular, trapezoidal or delimited section, as in FIG. 1, by two concentric arcs of circle whose center coincides with the axis of the wall 6 and by two sections radial lines having an intersection on this axis (see, for example, FR-A-1 492 063).
  • the walls (radial) of the adjacent segments 7 which are located opposite, are insulated from each other by means of an insulating coating 8 in the form of an electrically insulating layer deposited, for example, in a ceramic material (alumina or other) by "shooping", or by means of rigid separation plates or felt tapes or fabrics of a similar insulating material, preferably refractory, inserted between these walls.
  • an insulating coating 8 in the form of an electrically insulating layer deposited, for example, in a ceramic material (alumina or other) by "shooping", or by means of rigid separation plates or felt tapes or fabrics of a similar insulating material, preferably refractory, inserted between these walls.
  • each of the ends of the tubular sections forming the segments 7 is closed by a transverse plate 10 and provided with tubular connection end pieces 11, oriented in radial projection towards the outside.
  • the circulation of the cooling fluid is ensured by means of an intake collecting ring 12 and an evacuation collecting ring 13 of diameters greater than that outside of the wall 6 as well as that of the heating inductor 1.
  • These collecting rings 12 and 13 are respectively provided with connection end pieces 14 and 15, oriented inwardly projecting radially, which are hydraulically connected to those 11 of the segments 7 by means of insulating tubular seals 16, preferably flexible, of so as to maintain the electrical isolation between the segments 7.
  • These collector rings 12, 13 are respectively joined using other tubular ends 17, 18 to a circuit of the refrigerant fluid (not shown) whose circulation takes place in the direction of the arrows W 1.
  • the bottom of the cold cage 5 is closed using a base or sole 19 also cooled, either in the form of a hollow metal disc connected by two end pieces 20, 21 to another fluid circuit represented by arrows W2, or in the form of a ceramic disc (see, for example, GB-A-1 130 070), the underside of which can be sprinkled, for example.
  • This hearth 19 can be produced using sectors isolated from each other or in the form of a ring crossed by a heated discharge nozzle for the molten charge (see FR-A-1 188 576 or 2 054 464, for example).
  • the hearth 19 When the hearth 19 is made of a conductive material and the load to be melted is cold conductive, it may be advantageous to completely cover its upper face with a layer or a lining of insulating material (ceramic).
  • the outer (annular) part of the upper face of the floor 19, which is in contact with the lower end of the side wall 6, is preferably isolated in all cases from the latter, for example, by means of '' a ceramic felt washer or a powder bed of an insulating refractory material (alumina, for example).
  • the heating inductor 1 which surrounds the side wall 6 of the cage 5 and which ensures the direct induction melting of the charge and the stirring of the liquid bath, is also produced in a tube and connected to a fluid circuit cooling symbolized by the arrows W3. It will also be noted that in the cage 5, a necking effect produced by the inductor 1 has been observed on the part of the liquid bath which is at its level.
  • the load is introduced into the cage 5 in powder or granular form by means of a hopper (not shown) from the top, in the direction of the arrow C.
  • FIG. 2 is a perspective view of a possible embodiment of a vertical melting device with additional electromagnetic confinement of the charge, according to the invention.
  • the segments 70 forming the side wall 60 of the cold cage 50 have been produced by means of tubular elements in the form of hairpins (or "U") using two sections of parallel tube 71, 72, placed side by side insulated from each other by a slot 73 which can be closed by felt or by a ceramic layer, and one of which 71 has an end hydraulically and electrically connected to that, adjacent of the neighboring section 72 by means of a transverse (circumferential) joining section 74, perpendicular to the two parallel sections 71, 72.
  • These segments 70 are juxtaposed as in the state of the art, so as to form the cylindrical side wall 60 of the cage 50, the bottom of which is closed by a conventional sole 19 (see FIG. 1 and the state of the art mentioned previously). ).
  • the free adjacent (unconnected) ends of the sections 71, 72 forming the same segment 70 are respectively hydraulically and electrically connected by metallic tubular joints or sections 22, 23 conductive, some (22) of which are perpendicular to the vertical axis of the sheath 50 and the others (23) inclined with respect to this axis, to two hollow metal collecting rings 120, 130 of which the first (120) comprises the intake nozzle 17 and the second (130) the discharge nozzle 18 of the coolant from the cage 50, the circulation of which is indicated by the arrows Wl.
  • the respective electrical connection between the collector rings 120, 130 and the respective ends of the hairpin segments 70 makes it possible, by connecting them respectively to the two output terminals of a second AC power generator 24, to pass through the two parallel sections 71, 72 of the alternating electric currents respectively in opposite directions.
  • the confinement forces generated by the cage 50 according to the invention also act on the parts of the solid charge but having exceeded the inducibility temperature, which are then separated from its inner wall and replaced by particles (grains) insulating from the substance.
  • the preferred method of using the melting device by direct induction in a cold cage, with additional electromagnetic confinement of the charge, when it is purely metallic, consists in adding to it in the divided state (pulverulent or granular), a small amount of cold insulating material and having a melting temperature close to its inducibility temperature and lower than that of the metal or alloy, to form a slag.
  • This slag having to present in the molten state a surface tension notably lower than that of the metallic part of the load, is precipitated from the mass of molten metal towards its periphery, where by cooling under the effect of the cold cage 50, it fills the space provided by the confining forces and becomes insulating and solid again in contact with the interior wall of the latter.
  • the mixture constituting the feed comprises in this case a proportion by weight of between 0.5 and 1.5 percent of the dairy substance, which is preferably constituted by fluorine (or calcium fluoride-CaF 2 ) or silica, optionally mixed with adjuvants such as borates allowing its melting point to be lowered to around 1400 ° C.
  • the cage 50 therefore comprises juxtaposed hairpin inductors formed by the segments 70 and connected in parallel by means of the two collector rings 120, 130 which are respectively connected to the two low-impedance output terminals formed, for example, by the terminals of a secondary winding of an adaptation transformer (not shown), the primary winding of which is connected to the terminals of the second generator 24.
  • These inductors (in U 70) are each supplied with a current I 2 / N of a few tens of effective amps (where N is the number of segments 70 forming the cage 50), the exact intensity of which is then determined experimentally as a function of the dimensions of the bath and of the necking effect already provided by the heating inductor 1, so that they produce an adequate additional electro magnetic confinement of the charge.
  • a significantly lower power than that consumed by the inductor 1 is sufficient to supply the segments 70 of the cage 50 in parallel and to obtain sufficient confinement of the bath.
  • the second generator 24 supplying the inductors of the cage 50 in parallel will therefore have to supply, for example, a power which is between one fifth and one tenth of that supplied by the first generator 2 to the inductor 1 (from 50 to 250 kW ).
  • a power of the order of a few kilowatts to a few tens of kilowatts (10 to 30 kW, for example) is sufficient for the electromagnetic confinement of charges of metal or of metal alloys.
  • the same frequency ranges will be used for fusion-stirring and for confinement by the cage 50, that is to say the high frequencies from 30 kHz to 10 MHz for refractory oxides, silicates and semi -conductive and medium frequencies from 1 to 20 kHz for melting cold conductive and possibly refractory metals or alloys.
  • different frequencies are chosen to carry out the operations of melting and stirring by the heating inductor 1 and the electromagnetic confinement operation by the cage 50, which are distinct functions and separately controllable by means of two generators. It is also possible to use the range of high frequencies for heating and mixing and that of medium frequencies for confinement, or vice versa.
  • the main advantage of the electromagnetic confinement according to the invention by the cage 50 is that the periphery of the conductive part of the load, even composed of a cold conductive material, is spaced from the internal face of the side wall 60 of the latter, over substantially its entire height and not only at the level of the main inductor 1, with the concomitant reduction of the heat losses by conduction, and of the risks of flows through the slots of the side wall 60.
  • each hairpin inductor instead of connecting the two free ends of each hairpin inductor to two separate collecting rings 120, 130, it is possible to connect them electrically and even hydraulically in series, that is to say say to connect together, for example, by means of transver junction sections saux, similar to those designated by the reference 74, the neighboring lower ends of the different segments 70. A serpentine inductor, folded into a cylinder, of high impedance is then obtained. It is also possible to make series-parallel combinations of these hairpin inductors by bringing a number together in series with groups of equal inductance and to bring these groups together in parallel in order to obtain the impedance that the it is desired according to the dimensions of the cage 50 and the frequency of the second generator 24, chosen accordingly.
  • transverse sections 74 which also provide hydraulic continuity. It is also possible to supply the coolant as illustrated in FIG. 1, that is to say by using insulating tubular joints, and the electrical supply in series by means of transverse metallic conductive plates. (in copper, for example) in the form of circular arcs of sufficient length to at least partially cover the ends (10, FIG. 1) of two neighboring sections (7, FIG. 1) to form a segment 70 in hairpin .
  • These connecting plates can be made mechanically and electrically integral with the ends of sections which they cover by welding or brazing. They can even replace the end plates (10, Figure 1) closing the ends of the tubular sections (7, Figure 1) which they must then completely cover.
  • a metal tube of copper or of a copper alloy (brasses, bronzes) or of a nickel alloy with other metals, such as copper or chromium For the fusion of metals or refractory alloys, for example, it is advantageous to use an alloy of nickel, chromium and iron (0.78 Ni + 0.14Cr + 0.07Fe), such as that which is marketed under the name "INCONEL” (trademark registered by the American company International Nickel Co.) and which is particularly suitable for high temperatures.

Abstract

Dispositif de fusion par induction directe en cage froide, dit "auto-creuset" avec confinement électromagnétique de la charge fondue, dans lequel la paroi latérale cylindrique (6) de la cage froide (5) est réalisée à l'aide de nombreux segments en épingle à cheveux (70) juxtaposés, formés chacun par deux tronçons conducteurs (71,72) parallèles, creux et isolés l'un de l'autre sur toute leur interface à l'exception d'un tronçon (74) transverse qui réunit une extrémité de l'un des tronçons (71) à celle, adjacente de l'autre (72). Les autres extrémités de ces deux conducteurs sont respectivement électriquement et hydrauliquement reliées par des conducteurs tubulaires à deux anneaux collecteurs creux (120, 130), respectivement reliés à deux bornes de sortie d'un second générateur de courant alternatif de moyenne ou haute fréquence (24), de sorte qu'ils conduisent respectivement des courants électriques dans des directions opposées qui assurent le confinement supplémentaire de la partie conductrice de la charge en l'écartant de la cage (5).Melting device by direct induction in a cold cage, called "self-crucible" with electromagnetic confinement of the molten charge, in which the cylindrical side wall (6) of the cold cage (5) is produced using numerous segments in hairpin (70) juxtaposed, each formed by two conductive sections (71,72) parallel, hollow and isolated from each other over their entire interface with the exception of a transverse section (74) which joins a end of one of the sections (71) to that, adjacent to the other (72). The other ends of these two conductors are respectively electrically and hydraulically connected by tubular conductors with two hollow collector rings (120, 130), respectively connected to two output terminals of a second medium or high frequency alternating current generator (24 ), so that they respectively conduct electric currents in opposite directions which provide additional confinement of the conductive part of the load by moving it away from the cage (5).

Description

L'invention concerne un dispositif de fusion par induction directe en cage froide, dite "auto-creuset", avec confinement électromagnétique supplémentaire de la charge, afin de l'écarter de la paroi latérale intérieure de cette cage.The invention relates to a device for direct induction melting in a cold cage, known as a "self-crucible", with additional electromagnetic confinement of the charge, in order to move it away from the inner side wall of this cage.

Des procédés et dispositifs de fusion ou fours par induction directe dans une cage froide ayant une paroi latérale constituée par un assemblage de tronçons tubulaires en matériau conducteur, isolés l'un de l'autre et, par conséquent, sensiblement transparente au champ magnétique alternatif engendré par un inducteur qui l'entoure sur au moins une partie de sa hauteur, sont bien connus et décrits, par exemple, dans les publications FR-A-1 492 063 (ou DE-B-1 615 195, GB-A-1 130 070 ou US-A-3 461 215 correspondantes), où le procédé est appliqué notamment à la fusion d'oxydes réfractaires ou de leurs mélanges qui ne sont pas conducteurs à froid, FR-A-2 036 418, où le procédé est appliqué notamment à l'élaboration de certains métaux à partir de leurs halogénures par calciothermie, par exemple, et FR-A- 2 052 082, où le procédé est appliqué notamment à l'élaboration de certains métaux à partir de l'un de leurs oxydes par réduction directe au moyen d'un métal réducteur alcalin ou alcalino-terreux (tel que le calcium) et de son fluorure utilisé comme solvant, ainsi que dans la publication GB-A-1 221 909 qui en décrit une réalisation différente à l'aide d'un assemblage de tubes de section circulaire, utilisable pour faire fondre des charges conductrices à froid.Methods and devices for direct induction melting or furnaces in a cold cage having a side wall constituted by an assembly of tubular sections of conductive material, isolated from each other and, therefore, substantially transparent to the alternating magnetic field generated by an inductor which surrounds it over at least part of its height, are well known and described, for example, in the publications FR-A-1 492 063 (or DE-B-1 615 195, GB-A-1 130,070 or corresponding US-A-3,461,215), where the process is applied in particular to the fusion of refractory oxides or their mixtures which are not cold conductors, FR-A-2,036,418, where the process is applied in particular to the production of certain metals from their halides by calciothermy, for example, and FR-A- 2 052 082, where the process is applied in particular to the production of certain metals from one of their oxides by direct reduction using an alkali or alkaline-earth reducing metal them (such as calcium) and its fluoride used as solvent, as well as in the publication GB-A-1 221 909 which describes a different embodiment thereof using an assembly of tubes of circular section, usable for making melt cold conductive charges.

La charge à fondre est généralement introduite dans la cage froide dont le fond est obturé au moyen d'une plaque isolante réfractaire ou métallique creuse et refroidie, par le haut sous une forme pulvérulente ou granuleuse. Lorsqu'elle est constituée par un mélange de matériaux dont l'un au moins est isolant à froid, ce dernier s'agglomère, lors de la fusion, au voisinage de la paroi intérieure de la cage froide de façon à former une mince gaine ou pellicule électriquement isolante qui la recouvre. Par contre, lorsque la charge est métallique (c'est-à-dire en métal ou en alliages de métaux) et conductrice à froid, cette gaine formée au contact de la paroi froide est également conductrice et met les éléments isolés (segments en tube de cuivre) de la cage en court-circuit. Dans les deux cas précités, une partie assez notable de la chaleur engendrée par induction est transmise par conduction à la cage froide et évacuée en réchauffant le fluide qui y circule et dans le dernier cas, une partie importante du courant induit passe par la face interne de la paroi latérale de la cage froide mise en court-circuit par la charge conductrice.The charge to be melted is generally introduced into the cold cage, the bottom of which is closed by means of a hollow refractory or metallic insulating plate and cooled from above in a powdery or granular form. When it is made up of a mixture of materials, at least one of which is cold insulating, the latter agglomerates, during melting, in the vicinity of the inner wall of the cold cage so as to form a thin sheath or electrically insulating film which covers it. On the other hand, when the load is metallic (that is to say metal or metal alloys) and cold conductive, this sheath formed in contact with the cold wall is also conductive and puts the insulated elements (segments in tube copper) of the cage in short circuit. In the two aforementioned cases, a fairly significant part of the heat generated by induction is transmitted by conduction to the cold cage and evacuated by heating the fluid which circulates therein and in the latter case, a significant part of the induced current passes through the internal face. the side wall of the cold cage short-circuited by the conductive load.

Ces inconvénients pourraient être réduits par un confinement électromagnétique de la charge fondue qui est électriquement conductrice dans tous les cas, à l'aide d'un champ magnétique alternatif.These drawbacks could be reduced by electromagnetic confinement of the molten charge which is electrically conductive in all cases, using an alternating magnetic field.

Le confinement électromagnétique d'une coulée de métal liquide au moyen d'un champ magnétique alternatif axial est connu en soi, par exemple, des publications GB-A- 893 445, FR-A-1 509 962, 2 106 545, 2 160 281, 2 316 026 et 2 396 612. Dans ces dispositifs de confinement connus, le champ magnétique axial de confinement est engendré à l'aide d'un inducteur alimenté en courant alternatif, entourant coaxialement le creuset ou la buse véhiculant la coulée, sensiblement au niveau de son orifice inférieur.The electromagnetic confinement of a molten metal flow by means of an axial alternating magnetic field is known per se, for example, from the publications GB-A- 893 445, FR-A-1 509 962, 2 106 545, 2 160 281, 2 316 026 and 2 396 612. In these known confinement devices, the axial magnetic confinement field is generated using an inductor supplied with alternating current, coaxially surrounding the crucible or the nozzle carrying the pouring, substantially at its lower opening.

Il a été également constaté (voir GB-A-1 221 909) que les courant induits dans les segments de la cage froide au niveau de l'inducteur, qui suivent la circonférence des éléments conducteurs isolés de la cage froide, exercent sur la partie fondue de la charge un effet de striction ou de confinement, grâce auquel elle décolle de la paroi intérieure de la cage froide. Un tel effet de répulsion se limite sensiblement à la zone entourée de l'inducteur de chauffage et consomme une bonne partie de l'énergie qui lui est fournie et qui est évacuée par le fluide de refroidissement parcourant la cage. L'adjonction d'un inducteur de confinement coaxial avec l'inducteur de chauffage présenterait des problèmes de couplage mutuel et d'un couplage insuffisant à la périphérie de la charge, dû au fait de la présence de la paroi latérale de la cage froide entre celle-ci et les inducteurs.It has also been observed (see GB-A-1 221 909) that the currents induced in the segments of the cold cage at the level of the inductor, which follow the circumference of the conductive elements isolated from the cold cage, exert on the part fondue of the load a necking or confinement effect, thanks to which it takes off from the inner wall of the cold cage. Such a repulsion effect is substantially limited to the area surrounded by the heating inductor and consumes a good part of the energy which is supplied to it and which is evacuated by the coolant flowing through the cage. The addition of a coaxial confinement inductor with the heating inductor would present problems of mutual coupling and insufficient coupling at the periphery of the load, due to the presence of the side wall of the cold cage between this and the inductors.

L'expérience a montré que, lorsque le matériau électrofondu a été retiré de la cage froide en forme de lingots obtenus par le déplacement axial (vers le bas) de la "sole" obturant son fond, (voir par exemple, FR-A-2 303 774), le lingot présente des irrégularités superficielles en forme de crêtes longitudinales, aux endroits des séparations entre les segments de la cage, où l'effet de refroidissement est moins efficace.Experience has shown that, when the electrofused material has been removed from the cold cage in the form of ingots obtained by the axial displacement (downwards) of the "sole" closing its bottom, (see for example, FR-A- 2 303 774), the ingot has surface irregularities in the form of longitudinal ridges, at the locations of the partitions between the segments of the cage, where the cooling effect is less effective.

Un autre procédé de confinement électromagnétique a été décrit dans la publication DE-B-1 147 714, où l'on utilise pour- le transfert ou le maintien en lévitation de corps en matériaux conducteurs liquides (coulée) ou solides, un ensemble de conducteurs parallèles qui les entourent à la manière d'une gaine tubulaire et qui sont parcourus de courants alternatifs de telle sorte que les courants dans les conducteurs voisins s'écoulent respectivement dans des sens opposés. Un procédé de confinement analogue a été décrit dans la publication FR-A-2 397 251.Another electromagnetic confinement process has been described in the publication DE-B-1 147 714, in which a set of conductors is used for the transfer or the levitation of bodies made of liquid (casting) or solid conducting materials. parallel which surround them in the manner of a tubular sheath and which are traversed by alternating currents so that the currents in the neighboring conductors flow respectively in opposite directions. A similar confinement process has been described in publication FR-A-2 397 251.

Un four horizontal par induction directe avec lévitation électromagnétique de la charge en matériau conducteur solide a été décrit dans la publication FR-A-1 508 992, où un inducteur à trois brins longitudinaux (parallèles à l'axe horizontal) dont deux sont connectés en parallèle et dont l'un (l'inférieur) est connecté en série avec les autres pour former un berceau de lévitation, est entouré d'un inducteur monospire cylindrique ou solénoîdal qui assure le chauffage du corps métallique et concourt à son maintien en lévitation, notamment lorsqu'il est en fusion. Un tel four horizontal sans creuset n'est pas utilisable avec des charges divisées (pulvérulentes ou granuleuses) et ne permet ni la coulée en continu, ni l'étirage des lingots ou des cristaux. En outre, sa charge maximale est limitée à quelques kilogrammes du fait de la force nécessaire à la lévitation qui s'oppose à la gravitation.A horizontal oven by direct induction with electromagnetic levitation of the load of solid conductive material has been described in the publication FR-A-1 508 992, where an inductor with three longitudinal strands (parallel to the horizontal axis), two of which are connected in parallel and one of which (the lower one) is connected in series with the others to form a levitation cradle, is surrounded by a cylindrical or solenoidal monospire inductor which ensures the heating of the metallic body and contributes to its maintenance in levitation, especially when it is in fusion. Such a horizontal furnace without a crucible cannot be used with divided loads (powdery or grainy) and does not allow continuous casting or drawing of the ingots or crystals. In addition, its maximum load is limited to a few kilograms because of the force necessary for levitation which opposes gravitation.

Un procédé et un dispositif de coulée dite "électromagnétique" de métaux et d'alliages fondus a été décrit dans la publication US-A-4 215 738, où la forme du lingot déterminée à l'aide d'un inducteur monospire de confinement qui l'entoure de manière coaxiale et qui est parcouru d'un courant alternatif (voir publications FR-A-1 509 962 et 2 106 545 précitées, par exemple) et où des inducteurs de confinement supplémentaire en forme de serpentin, dits "anti-parallèles", sont disposés entre l'inducteur monospire principal et certaines parois du lingot pour assurer une meilleure régularité des formes de celles-ci. Plus précisément ces inducteurs "anti-parallèles" sont formés à l'aide de plusieurs brins conducteurs, parallèles à l'axe vertical du lingot et reliés en série de telle sorte que les courants qui parcourent les brins voisins sont respectivement de sens opposés, afin d'exercer sur la partie supérieure fondue du lingot des forces électromagnétiques de répulsion (confinement) qui s'ajoutent à celles engendrées par l'inducteur principal et qui sont analogues à celles de la publication DE-B-1 147 714 précitée.A process and a device known as "electromagnetic" casting of molten metals and alloys has been described in the publication US-A-4 215 738, where the shape of the ingot determined using a monospire confinement inductor which surrounds it coaxially and which is traversed by an alternating current (see publications FR-A-1 509 962 and 2 106 545 above, for example) and where additional confinement inductors in the form of a serpentine, called "anti- parallel ", are arranged between the main single-coil inductor and certain walls of the ingot to ensure better regularity of the shapes thereof. More precisely, these "anti-parallel" inductors are formed using several conductive strands, parallel to the vertical axis of the ingot and connected in series so that the currents which flow through the neighboring strands are respectively in opposite directions, so to exert on the molten upper part of the ingot electromagnetic forces of repulsion (confinement) which are added to those generated by the main inductor and which are similar to those of the above-mentioned publication DE-B-1 147 714.

La présente invention a pour objet un dispositif de fusion par induction directe dans une cage dont la paroi latérale cylindrique est formée par un ou plusieurs inducteurs "antiparallèles" qui sert en même temps de gaine froide et de dispositif de confinement supplémentaire, permettant de recevoir notamment des charges pulvérulentes ou granuleuses (divisées en particules) en matériaux diverses qui peuvent être isolants ou conducteurs à froid ou constitués par des mélanges de tels matériaux. Ce dispositif de fusion est orienté verticalement pour permettre la coulée du matériau fondu ou l'étirage de lingots (connus en soi) et, de ce fait, le champ magnétique de confinement supplémentaire n'a pas à vaincre la gravitation et peut agir sur la partie fondue de la charge, lorsqu'elle est isolante à froid, pour faciliter la formation de la carapace ou gangue agglomérée qui se substitue au creuset et dont l'épaisseur accrue assure un meilleur isolement thermique de la partie en fusion. Lorsque la charge est conductrice à froid, le champ magnétique engendré par les courants parcourant les tronçons de la cage peut également agir sur la partie supérieure non-fondue de la charge, si leur intensité dépasse un certain seuil.The present invention relates to a device for direct induction melting in a cage whose cylindrical side wall is formed by one or more "antiparallel" inductors which serve at the same time as a cold sheath and an additional containment device, making it possible in particular to receive pulverulent or granular fillers (divided into particles) of various materials which can be insulating or cold conducting or consist of mixtures of such materials. This fusion device is oriented vertically to allow the casting of the molten material or the drawing of ingots (known per se) and, therefore, the additional confinement magnetic field does not have to overcome gravitation and can act on the molten part of the load, when it is cold insulating, to facilitate the formation of the agglomerated shell or gangue which replaces the crucible and whose increased thickness ensures better thermal insulation of the part in fusion. When the load is conductive when cold, the magnetic field generated by the currents flowing through the sections of the cage can also act on the unmelted upper part of the load, if their intensity exceeds a certain threshold.

Suivant l'invention, la paroi latérale froide de la cage est agencée de telle sorte qu'elle constitue en même temps un inducteur de confinement de type connu en soi, qui est alimenté par un second générateur de puissance d'une seconde haute ou moyenne fréquence et qui comporte, outre les tronçons tubulaires juxtaposés, des moyens de liaison électrique reliant ensemble les extrémités adjacentes de deux tronçons tubulaires voisins, afin que ceux-ci soient respectivement parcourus d'un courant alternatif dans des sens opposés, engendrant dans la partie conductrice de la périphérie de la charge des forces de confinement supplémentaire.According to the invention, the cold side wall of the cage is arranged such that it constitutes at the same time a confinement inductor of a type known per se, which is supplied by a second power generator of a high or medium second frequency and which comprises, in addition to the juxtaposed tubular sections, electrical connection means connecting together the adjacent ends of two neighboring tubular sections, so that these are respectively traversed by an alternating current in opposite directions, generating in the conductive part from the periphery of the load of the additional confinement forces.

Ces moyens de liaison électrique peuvent être constitués par des plaques conductrices ou des tronçons de tube transversaux qui réunissent ensemble, par exemple, par l'une de leurs extrémités adjacentes respectives, deux tronçons tubulaires voisins de façon à former des segments en forme d'épingles à cheveux qui sont alors juxtaposés de manière électriquement isolée pour former la paroi latérale de la cage froide.These electrical connection means can consist of conductive plates or transverse tube sections which join together, for example, by one of their respective adjacent ends, two neighboring tubular sections so as to form pin-shaped segments. to hair which are then juxtaposed in an electrically isolated manner to form the side wall of the cold cage.

Dans différents modes de réalisation de la cage froide qui est en même temps un inducteur de confinement, les segments en épingle à cheveux formant la paroi latérale sont respectivement électriquement connectés en parallèle, en série ou en divers combinaisons série-parallèle, afin qu'un ensemble d'éléments inducteurs ainsi reliés puisse présenter une impédance adaptée à la fréquence du second générateur.In different embodiments of the cold cage which is at the same time a confinement inducer, the hairpin segments forming the side wall are respectively electrically connected in parallel, in series or in various series-parallel combinations, so that a set of inductor elements thus connected can have an impedance adapted to the frequency of the second generator.

La puissance de confinement supplémentaire fournie par le second générateur étant une fonction du diamètre et de la hauteur de la cage froide et, par conséquent, du volume de la charge. Elle est généralement comprise entre un dizième et un cinquième de la puissance fournie par le premier générateur à l'inducteur principal entourant la cage.The additional confining power provided by the second generator being a function of the diameter and the height of the cold cage and, consequently, of the volume of the load. It is generally between one tenth and one fifth of the power supplied by the first generator to the main inductor surrounding the cage.

Dans un procédé d'utilisation du dispositif de fusion avec confinement supplémentaire suivant l'invention, on ajoute à la charge à fondre, lorsque tous ses composants sont métalliques (conductrices à froid), une faible proportion d'une substance isolante à froid et ayant un point de fusion inférieur à celui du métal ou de l'alliage, pour former un laitier. Ce laitier, de préférence en fluorine (ou fluorure de calcium) ou en silice, éventuellement mélangée à des adjuvants tels que des borates, présente à l'état fondu une tension superficielle notablement inférieure à celui du métal auquel elle est mélangée à l'état pulvérulent et il est, de ce fait, expulsé du métal en fusion brassé, vers sa périphérie où sous l'effet de la cage froide il se solidifie en redevenant isolant. Les forces de confinement n'ayant plus prise sur le laitier isolant, il est alors propulsé par le bain vers les faces internes de la cage en y formant une carapace isolante (non-inductible). On en utilise, de préférence, une proportion pondérale de 0, 5 à 1, 5 pour cent en relation au poids total de la charge.In a method of using the melting device with additional confinement according to the invention, a small proportion of a cold insulating substance is added to the charge to be melted, when all of its components are metallic (cold conductive). a melting point lower than that of the metal or alloy, to form a slag. This slag, preferably fluorite (or calcium fluoride) or silica, optionally mixed with adjuvants such as borates, has in the molten state a surface tension significantly lower than that of the metal to which it is mixed in the state pulverulent and it is, therefore, expelled from the stirred molten metal, towards its periphery where, under the effect of the cold cage, it solidifies, becoming again insulating. As the confining forces no longer take hold on the insulating slag, it is then propelled by the bath towards the internal faces of the cage, forming an insulating shell there (non-inducible). Preferably, a proportion by weight of 0.5 to 1.5 percent is used in relation to the total weight of the filler.

L'invention sera mieux comprise et d'autres de ses caractèris- tiques et avantages ressortiront de la description qui suit et des dessins annexés, donnés à titre d'exemple, sur lesquels :

  • -la figure 1 est une vue schématique en perspective d'un dispositif de fusion par induction directe en cage froide de l'état de la technique antérieure ; et
  • -la figure 2 est une vue schématique en perspective d'un mode de réalisation du dispositif de fusion par induction directe avec confinement électromagnétique supplémentaire de la charge, dans lequel pour la simplicité du dessin, les segments en épingle à cheveux sont connectés en parallèle.
The invention will be better understood and others of its characteristics and advantages will emerge from the description which follows and from the appended drawings, given by way of example, in which:
  • FIG. 1 is a schematic perspective view of a device for melting by direct induction in a cold cage of the state of the prior art; and
  • FIG. 2 is a schematic perspective view of an embodiment of the direct induction melting device with additional electromagnetic confinement of the charge, in which for the simplicity of the drawing, the hairpin segments are connected in parallel.

Le dispositif de fusion classique de la figure 1 comporte un inducteur de chauffage 1 de forme hélicoïdale, réalisé en tube de cuivre et comprenant plusieurs spires qui couvrent une hauteur prédéterminée. Les deux extrémités 3, 4 de cet inducteur 1 sont respectivement réunies ici à deux bornes de sortie (basse impédance, par exemple) d'un premier générateur de puissance 2 pouvant engendrer un courant alternatif Il de hautes (30kHz - 10MHz) ou de moyennes (1 - 30kHz) fréquences (industrielles) qui sont destinées respectivement à la fusion de matériaux réfractaires isolants à froid, tels que des oxydes ou des silicates par exemple, ou semi-conducteurs, tels que le silicium, le germanium ou l'arséniure de gallium, par exemple, et à celle de matériaux conducteurs à froid, tels que des métaux ou des alliages de métaux.The conventional melting device of FIG. 1 comprises a heating inductor 1 of helical shape, made of copper tube and comprising several turns which cover a predetermined height. The two ends 3, 4 of this inductor 1 are respectively brought together here at two output terminals (low impedance, for example) of a first power generator 2 which can generate an alternating current Il of high (30kHz - 10MHz) or of medium (1 - 30kHz) (industrial) frequencies which are respectively intended for the fusion of cold insulating refractory materials, such as oxides or silicates for example, or semiconductors, such as silicon, germanium or arsenide gallium, for example, and that of cold conductive materials, such as metals or metal alloys.

La puissance fournie à l'inducteur 1 est fonction, notamment, de la nature (point de fusion, résistivité à froid et à chaud, perméabilité relative jusqu'au point de Curie etc.) du matériau, du volume de la charge à fondre (c'est-à-dire du diamètre de la cage froide et de la hauteur de l'inducteur 1) et du couplage entre la charge et l'inducteur (de l'épaisseur de la cage). Le générateur 2 doit, par conséquent, être dimensionné de façon à fournir une puissance comprise entre 50 et 250 kilowatts, par exemple.The power supplied to the inductor 1 is a function, in particular, of the nature (melting point, cold and hot resistivity, relative permeability up to the Curie point etc.) of the material, the volume of the charge to be melted ( that is to say the diameter of the cold cage and the height of the inductor 1) and the coupling between the load and the inductor (the thickness of the cage). The generator 2 must therefore be dimensioned so as to provide a power of between 50 and 250 kilowatts, for example.

La cage froide ou "auto-creuset" 5 comprend une paroi latérale cylindrique 6 à axe de symétrie verticale, composée d'un grand nombre de segments tubulaires 7 juxtaposés, qui sont de forme allongée et orientés parallèlement à l'axe géométrique ou à la génératrice du cylindre qu'ils forment ensemble. Ces segments 7 peuvent être réalisés en des tronçons de tube métallique de section rectangulaire, circulaire, trapézoïdale ou délimitée, comme sur la figure 1, par deux arcs de cercle concentriques dont le centre coïncide avec l'axe de la paroi 6 et par deux sections de droite radiales ayant une intersection sur cet axe (voir, par exemple, FR-A-1 492 063). Les parois (radiales) des segments 7 adjacents qui sont situées en regard, sont isolées l'une de l'autre au moyen d'un revêtement isolant 8 sous la forme d'une couche isolante électrique déposée, par exemple, en un matériau céramique (alumine ou autre) par "shoopage", ou au moyen de plaquettes de séparation rigides ou de rubans en feutre ou tissus d'un matériau isolant analogue, de préférence réfractaire, insérés entre ces parois.The cold cage or "self-crucible" 5 comprises a cylindrical side wall 6 with vertical axis of symmetry, composed of a large number of juxtaposed tubular segments 7, which are of elongated shape and oriented parallel to the geometric axis or to the generator of the cylinder that they form together. These segments 7 can be produced in sections of metal tube of rectangular, circular, trapezoidal or delimited section, as in FIG. 1, by two concentric arcs of circle whose center coincides with the axis of the wall 6 and by two sections radial lines having an intersection on this axis (see, for example, FR-A-1 492 063). The walls (radial) of the adjacent segments 7 which are located opposite, are insulated from each other by means of an insulating coating 8 in the form of an electrically insulating layer deposited, for example, in a ceramic material (alumina or other) by "shooping", or by means of rigid separation plates or felt tapes or fabrics of a similar insulating material, preferably refractory, inserted between these walls.

Lorsqu'il s'agit de faire fondre par induction directe des matériaux qui sont conducteurs électriques à froid, tels que des métaux ou des alliages métalliques, il peut s'avérer avantageux de recouvrir d'une couche de matériau céramique isolant et réfractaire, également les parois 9 des segments 7 qui sont adjacentes à la charge et qui forment ensemble la face interne de la paroi latérale 6 de la cage froide 5, ou de la munir d'une mince garniture isolante intérieure de forme cylindrique, en un tel matériau.When it comes to melt by direct induction of materials that are cold electrical conductors, such as metals or metal alloys, it may be advantageous to cover with a layer of insulating and refractory ceramic material, also the walls 9 of the segments 7 which are adjacent to the load and which together form the internal face of the side wall 6 of the cold cage 5, or provide it with a thin inner insulating gasket of cylindrical shape, made of such a material.

En vue d'assurer le refroidissement de cette paroi latérale, chacune des extrémités des tronçons tubulaires formant les segments 7 est obturée par une plaque transversale 10 et munie d'embouts tubulaires de raccordement 11, orientés en saillie radiale vers l'extérieur. La circulation du fluide de refroidissement (eau) est assurée au moyen d'un anneau collecteur d'admission 12 et d'un anneau collecteur d'évacuation 13 de diamètres supérieurs à celui extérieur de la paroi 6 ainsi qu'à celui de l'inducteur de chauffage 1.In order to ensure the cooling of this side wall, each of the ends of the tubular sections forming the segments 7 is closed by a transverse plate 10 and provided with tubular connection end pieces 11, oriented in radial projection towards the outside. The circulation of the cooling fluid (water) is ensured by means of an intake collecting ring 12 and an evacuation collecting ring 13 of diameters greater than that outside of the wall 6 as well as that of the heating inductor 1.

Ces anneaux collecteurs 12 et 13 sont respectivement munis d'embouts de raccordement 14 et 15, orientés en saillie radiale vers l'intérieur, qui sont hydrauliquement reliés à ceux 11 des segments 7 au moyen de joints tubulaires isolants 16, flexibles de préférence, de manière à conserver l'isolement électrique entre les segments 7. Ces anneaux collecteurs 12, 13 sont respectivement réunis à l'aide d'autres embouts tubulaires 17, 18 à un circuit du fluide réfrigérant (non représenté) dont la circulation s'effectue dans le sens des flèches W 1.These collecting rings 12 and 13 are respectively provided with connection end pieces 14 and 15, oriented inwardly projecting radially, which are hydraulically connected to those 11 of the segments 7 by means of insulating tubular seals 16, preferably flexible, of so as to maintain the electrical isolation between the segments 7. These collector rings 12, 13 are respectively joined using other tubular ends 17, 18 to a circuit of the refrigerant fluid (not shown) whose circulation takes place in the direction of the arrows W 1.

Le fond de la cage froide 5 est obturé à l'aide d'une base ou sole 19 également refroidie, soit en forme de disque métallique creux raccordé par deux embouts 20, 21 à un autre circuit de fluide représenté par des flèches W2, soit en forme de disque en céramique (voir, par exemple, GB-A-1 130 070) dont la face inférieure peut être arrosée, par exemple. Cette sole 19 peut être réalisée à l'aide de secteurs isolés l'un de l'autre ou en forme d'anneau traversé par une buse d'évacuation chauffée de la charge fondue (voir FR-A-1 188 576 ou 2 054 464, par exemple).The bottom of the cold cage 5 is closed using a base or sole 19 also cooled, either in the form of a hollow metal disc connected by two end pieces 20, 21 to another fluid circuit represented by arrows W2, or in the form of a ceramic disc (see, for example, GB-A-1 130 070), the underside of which can be sprinkled, for example. This hearth 19 can be produced using sectors isolated from each other or in the form of a ring crossed by a heated discharge nozzle for the molten charge (see FR-A-1 188 576 or 2 054 464, for example).

Lorsque la sole 19 est en un matériau conducteur et la charge à fondre est conductrice à froid, il peut être avantageux de recouvrir entièrement sa face supérieure d'une couche ou d'une garniture de matériau isolant (céramique). La partie extérieure (annulaire) de la face supérieure de la sole 19, qui est au contact de l'extrémité inférieure de la paroi latérale 6, est, de préférence, isolée dans tous les cas de cette dernière, par exemple, au moyen d'une rondelle en feutre de céramique ou d'un lit de poudre d'un matériau réfractaire isolant (alumine, par exemple).When the hearth 19 is made of a conductive material and the load to be melted is cold conductive, it may be advantageous to completely cover its upper face with a layer or a lining of insulating material (ceramic). The outer (annular) part of the upper face of the floor 19, which is in contact with the lower end of the side wall 6, is preferably isolated in all cases from the latter, for example, by means of '' a ceramic felt washer or a powder bed of an insulating refractory material (alumina, for example).

On remarquera ici que l'inducteur de chauffage 1 qui entoure la paroi latérale 6 de la cage 5 et qui assure la fusion par induction directe de la charge et le brassage du bain liquide, est également réalisé en tube et raccordé à un circuit de fluide de refroidissement symbolisé par les flèches W3. On notera également que l'on a observé dans la cage 5, un effet de striction produit par l'inducteur 1 sur la partie du bain liquide qui se trouve à son niveau.It will be noted here that the heating inductor 1 which surrounds the side wall 6 of the cage 5 and which ensures the direct induction melting of the charge and the stirring of the liquid bath, is also produced in a tube and connected to a fluid circuit cooling symbolized by the arrows W3. It will also be noted that in the cage 5, a necking effect produced by the inductor 1 has been observed on the part of the liquid bath which is at its level.

La charge est introduite dans la cage 5 sous une forme pulvérulente ou granuleuse au moyen d'une trémie (non représentée) par le haut, dans le sens de la flèche C.The load is introduced into the cage 5 in powder or granular form by means of a hopper (not shown) from the top, in the direction of the arrow C.

La figure 2 est une vue en perspective d'un mode de réalisation possible dispositif de fusion verticale avec confinement électromagnétique supplémentaire de la charge, suivant l'invention.FIG. 2 is a perspective view of a possible embodiment of a vertical melting device with additional electromagnetic confinement of the charge, according to the invention.

Sur la figure 2, les segments 70 formant la paroi latérale 60 de la cage froide 50 ont été réalisés au moyen d'éléments tubulaires en forme d'épingles à cheveux (ou "U") à l'aide de deux tronçons de tube parallèles 71, 72, posés côte à côte isolés l'un de l'autre par une fente 73 qui peut être obturée par du feutre ou par une couche céramique, et dont l'une 71 a une extrémité hydrauliquement et électriquement reliée à celle, adjacente du tronçon voisin 72 au moyen d'un tronçon de jonction 74 transversal (circonférentiel), perpendiculaire aux deux tronçons parallèles 71, 72.In FIG. 2, the segments 70 forming the side wall 60 of the cold cage 50 have been produced by means of tubular elements in the form of hairpins (or "U") using two sections of parallel tube 71, 72, placed side by side insulated from each other by a slot 73 which can be closed by felt or by a ceramic layer, and one of which 71 has an end hydraulically and electrically connected to that, adjacent of the neighboring section 72 by means of a transverse (circumferential) joining section 74, perpendicular to the two parallel sections 71, 72.

Ces segments 70 sont juxtaposés comme dans l'état de la technique, de façoo à former la paroi latérale cylindrique 60 de la cage 50 dont le fond est obturé par une sole 19 classique (voir figure 1 et l'état de la technique mentionné précedemment).These segments 70 are juxtaposed as in the state of the art, so as to form the cylindrical side wall 60 of the cage 50, the bottom of which is closed by a conventional sole 19 (see FIG. 1 and the state of the art mentioned previously). ).

A la différence de l'état de la technique en ce qui concerne la cage froide 50, les extrémités adjacentes libres (non reliées) des tronçons 71, 72 formant un même segment 70 sont respectivement hydrauliquement et électriquement reliées par des joints ou tronçons tubulaires métalliques 22, 23 conductrices, dont les uns (22) sont perpendiculaires à l'axe vertical de la gaine 50 et les autres (23) inclinés par rapport à cet axe, à deux anneaux collecteurs métalliques creux 120, 130 dont le premier (120) comporte l'embout d'admission 17 et le second (130) l'embout d'évacuation 18 du fluide de refroidissement de la cage 50, dont la circulation est indiquée par les flèches Wl.Unlike the state of the art with regard to the cold cage 50, the free adjacent (unconnected) ends of the sections 71, 72 forming the same segment 70 are respectively hydraulically and electrically connected by metallic tubular joints or sections 22, 23 conductive, some (22) of which are perpendicular to the vertical axis of the sheath 50 and the others (23) inclined with respect to this axis, to two hollow metal collecting rings 120, 130 of which the first (120) comprises the intake nozzle 17 and the second (130) the discharge nozzle 18 of the coolant from the cage 50, the circulation of which is indicated by the arrows Wl.

La liaison électrique respective entre les anneaux collecteurs 120, 130 et les extrémités respectives des segments 70 en épingle à cheveux, permet, en les reliant respectivement aux deux bornes de sortie d'un second générateur de puissance à courant alternatif 24, de faire passer dans les deux tronçons parallèles 71, 72 des courants électriques alternatifs respectivement dans des sens opposés.The respective electrical connection between the collector rings 120, 130 and the respective ends of the hairpin segments 70, makes it possible, by connecting them respectively to the two output terminals of a second AC power generator 24, to pass through the two parallel sections 71, 72 of the alternating electric currents respectively in opposite directions.

Les champs magnétiques engendrés par les courants alternatifs qui parcourent les tronçons juxtaposés 71, 72 de la paroi latérale alternativement dans des sens opposés, induisent à l'intérieur de la périphérie de la charge fondue conductrice des courants sensiblement de même intensité et de phases opposées, par un effet de proximité.The magnetic fields generated by the alternating currents which pass through the juxtaposed sections 71, 72 of the side wall alternately in opposite directions, induce inside the periphery of the conductive molten charge currents substantially of the same intensity and of opposite phases, by a proximity effect.

Ces deux courants réagissent l'un sur l'autre de manière à engendrer, au niveau de la périphérie du bain liquide de forces (de Laplace) centripètes, c'est-à-dire des forces de répulsion sensiblement uniformément reparties à la périphérie du bain et orientées radialement en direction de son axe géométrique.These two currents react one on the other so as to generate, at the periphery of the liquid bath of centripetal forces (de Laplace), that is to say repulsion forces substantially uniformly distributed on the periphery of the bath and oriented radially in the direction of its geometric axis.

Ces forces de répulsion s'ajoutent aux forces de striction dûes à l'inducteur de chauffage 1 alimenté par le premier générateur 2 et constituent ainsi des forces de confinement supplémentaire agissant sur la charge. Lorsque la charge est principalement composée de substances isolantes à froid et conductrices à chaud et présentant des températures d'inductibilité et de fusion proches, ces forces de confinement supplémantaire permettent de former sur toute la hauteur du bain liquide (la charge fondue) entre la périphérie de celui-ci et la face intérieure de la cage 50, une pellicule d'air, de gaz ou de vide (lors d'une fusion sous vide) de quelques dizièmes de millimètre, qui se remplit de parties froides ou refroidies, isolantes des substances sur une plus grande épaisseur que lors de l'utilisation du dispositif de la figure 1, assurant ainsi un meilleur isolement électrique et thermique entre la charge fondue et la paroi latérale intérieure de la cage froide 50. Un tel agencement permet ainsi de réduire notablement les pertes thermiques et électriques par conduction, les risques de fuite (coulée) du matériau fondu et la contamination de la charge en fusion par les matériaux dont la cage 50 est constituée.These repulsion forces are added to the necking forces due to the heating inductor 1 supplied by the first generator 2 and thus constitute additional confinement forces acting on the load. When the charge is mainly composed of cold insulating and hot conducting substances and having close inducibility and melting temperatures, these additional confinement forces make it possible to form over the entire height of the liquid bath (the molten charge) between the periphery of this and the inner face of the cage 50, a film of air, gas or vacuum (during a vacuum fusion) of a few tenths of a millimeter, which fills with cold or cooled parts, insulating substances over a greater thickness than when the device of FIG. 1 is used, thus ensuring better electrical and thermal insulation between the molten charge and the inner side wall of the cold cage 50. Such an arrangement thus makes it possible to significantly reduce the thermal and electrical losses by conduction, the risks of leakage (casting) of the molten material and contamination of the molten charge by the materials of which the cage 50 is made.

Lorsque la charge est principalement composée de substances isolantes à froid et conductrices à chaud, mais dont la température d'inductibilité et très inférieure à celle de fusion (ce qui est le cas pour certains oxydes de métaux réfractaires), les forces de confinement engendrées par la cage 50 suivant l'invention, agissent également sur les parties de la charge solides mais ayant dépassé la température d'inductibilité, qui sont alors écartées de sa paroi intérieuree et remplacées par des particules (grains) isolantes de la substance.When the charge is mainly composed of cold insulating and hot conducting substances, but whose inducibility temperature and much lower than that of melting (which is the case for certain refractory metal oxides), the confinement forces generated by the cage 50 according to the invention, also act on the parts of the solid charge but having exceeded the inducibility temperature, which are then separated from its inner wall and replaced by particles (grains) insulating from the substance.

Il en est de même dans le cas de charges composées de substances conductrices à froid, telles que des métaux et leurs alliages, dont la périphérie est écartée de la paroi intérieure de la cage 50 sensiblement jusqu'aux tronçons transversaux 74 (c'est-à-dire jusqu'aux bouts de la fente 73 séparant les tronçons longitudinaux 71, 72 respectives des segments en épingle à cheveux 70), même en ce qui concerne sa partie pulvérulente, non encore fondue, dans une moindre mesure que celle de la partie fondue qui est dans le champ de l'inducteur de chauffage 1.It is the same in the case of loads composed of cold conductive substances, such as metals and their alloys, the periphery of which is spaced from the inner wall of the cage 50 substantially up to the transverse sections 74 (that is i.e. to the ends of the slot 73 separating the respective longitudinal sections 71, 72 from the hairpin segments 70), even as regards its pulverulent part, not yet melted, to a lesser extent than that of the part fondue which is in the field of the heating inductor 1.

Le procédé d'utilisation préféré du dispositif de fusion par induction directe en cage froide, avec confinement électromagnétique supplémentaire de la charge, lorsque celle-ci est purement métallique, consiste à lui ajouter à l'état divisé (pulvérulent ou granuleux), une faible quantité d'une substance isolante à froid et présentant une température de fusion proche de sa température d'inductibilité et inférieure à celle du métal ou de l'alliage, pour former un laitier. Ce laitier devant présenter à l'état fondu une tension superficielle notablement inférieure à celle de la partie métallique de la charge, est précipité de la masse de métal en fusion vers sa périphérie, où en refroidissant sous l'effet de la cage froide 50, il remplit l'espace ménagé par les forces de confinement et redevient isolant et solide au contact de la paroi intérieure de cette dernière. Plus précisément, le laitier perd son inductibilité sous l'effet de la cage 50 et remplit l'espace périphérique entre celle-ci et la charge, en y formant une carapace électriquement et thermiquement isolante. Le mélange constituant la charge comporte dans ce cas, une proportion pondérale comprise entre 0, 5 et 1, 5 pour cent de la substance formant laitier, qui est, de préférence, constitué par de la fluorine (ou fluorure de calcium-CaF 2) ou de la silice, éventuellement mélangée à des adjuvants tels que des borates permettant d'abaisser son point de fusion jusqu'aux alentours de 1400°C.The preferred method of using the melting device by direct induction in a cold cage, with additional electromagnetic confinement of the charge, when it is purely metallic, consists in adding to it in the divided state (pulverulent or granular), a small amount of cold insulating material and having a melting temperature close to its inducibility temperature and lower than that of the metal or alloy, to form a slag. This slag having to present in the molten state a surface tension notably lower than that of the metallic part of the load, is precipitated from the mass of molten metal towards its periphery, where by cooling under the effect of the cold cage 50, it fills the space provided by the confining forces and becomes insulating and solid again in contact with the interior wall of the latter. More specifically, the slag loses its inducibility under the effect of the cage 50 and fills the peripheral space between the latter and the load, forming therein an electrically and thermally insulating shell. The mixture constituting the feed comprises in this case a proportion by weight of between 0.5 and 1.5 percent of the dairy substance, which is preferably constituted by fluorine (or calcium fluoride-CaF 2 ) or silica, optionally mixed with adjuvants such as borates allowing its melting point to be lowered to around 1400 ° C.

La cage 50 suivant l'invention, comporte donc des inducteurs en épingle à cheveux juxtaposés, formés par les segments 70 et connectés en parallèle au moyen des deux anneaux collecteurs 120, 130 qui sont respectivement reliées aux deux bornes de sortie basse- impédance constituées, par exemple, par les bornes d'un enroulement secondaire d'un transformateur d'adaptation (non-représenté) dont l'enroulement primaire est relié aux bornes du second générateur 24. Ces inducteurs (en U 70) sont alimentés chacun par un courant I2/N de quelques dizaines d'ampères efficace (où N est le nombre de segments 70 formant la cage 50), dont l'intensité exacte est alors déterminée expérimentalement en fonction des dimensions du bain et de l'effet de striction déjà fourni par l'inducteur de chauffage 1, pour qu'ils produisent un confinement électro supplémentaire adéquat magnétique de la charge. L'expérience a montré qu'une puissance notablement plus faible que celle consommée par l'inducteur 1 suffit pour alimenter les segments 70 de la cage 50 en parallèle et pour obtenir un confinement suffisant du bain.The cage 50 according to the invention therefore comprises juxtaposed hairpin inductors formed by the segments 70 and connected in parallel by means of the two collector rings 120, 130 which are respectively connected to the two low-impedance output terminals formed, for example, by the terminals of a secondary winding of an adaptation transformer (not shown), the primary winding of which is connected to the terminals of the second generator 24. These inductors (in U 70) are each supplied with a current I 2 / N of a few tens of effective amps (where N is the number of segments 70 forming the cage 50), the exact intensity of which is then determined experimentally as a function of the dimensions of the bath and of the necking effect already provided by the heating inductor 1, so that they produce an adequate additional electro magnetic confinement of the charge. Experience has shown that a significantly lower power than that consumed by the inductor 1 is sufficient to supply the segments 70 of the cage 50 in parallel and to obtain sufficient confinement of the bath.

Le second générateur 24 alimentant en parallèle les inducteurs de la cage 50 devra donc fournir, par exemple, une puissance qui est comprise entre un cinquième et un dizième de celle fournie par le premier générateur 2 à l'inducteur 1 (de 50 à 250 kW). Il en résulte qu'il suffit d'une puissance de l'ordre de quelques kilowatts à quelques dizaines de kilowatts (10 à 30 kW, par exemple) pour le confinement électromagnétique de charges en métal ou en alliages de métaux.The second generator 24 supplying the inductors of the cage 50 in parallel will therefore have to supply, for example, a power which is between one fifth and one tenth of that supplied by the first generator 2 to the inductor 1 (from 50 to 250 kW ). As a result, a power of the order of a few kilowatts to a few tens of kilowatts (10 to 30 kW, for example) is sufficient for the electromagnetic confinement of charges of metal or of metal alloys.

On utilisera pour la fusion-brassage et pour le confinement par la cage 50, de préférence, les mêmes gammes de fréquence, c'est-à-dire les hautes fréquences de 30 kHz à 10MHz pour les oxydes réfractaires, les silicates et les semi-conducteurs et les moyennes fréquences de 1 à 20 kHz pour la fusion de métaux ou alliages conducteurs à froid et, éventuellement, réfractaires. Toutefois, on choisit, de préférence, des fréquences différentes pour effectuer les opérations de fusion et brassage par l'inducteur de chauffage 1 et l'opération de confinement électromagnétique par la cage 50, qui sont des fonctions distinctes et séparément contrôlables au moyen de deux générateurs. Il est également possible d'utiliser la gamme des hautes fréquences pour le chauffage et le brassage et celle de moyennes fréquences pour le confinement, ou vice versa.The same frequency ranges will be used for fusion-stirring and for confinement by the cage 50, that is to say the high frequencies from 30 kHz to 10 MHz for refractory oxides, silicates and semi -conductive and medium frequencies from 1 to 20 kHz for melting cold conductive and possibly refractory metals or alloys. However, preferably, different frequencies are chosen to carry out the operations of melting and stirring by the heating inductor 1 and the electromagnetic confinement operation by the cage 50, which are distinct functions and separately controllable by means of two generators. It is also possible to use the range of high frequencies for heating and mixing and that of medium frequencies for confinement, or vice versa.

En résumé, le principal avantage du confinement électromagnétique suivant l'invention par la cage 50 est que la périphérie de la partie conductrice de la charge, même composée d'un matériau conducteur à froid, est écartée de la face interne de la paroi latérale 60 de celle-ci, sur sensiblement toute sa hauteur et non seulement au niveau de l'inducteur principal 1, avec la réduction concomittante des pertes thermiques par conduction, et des risques de coulées à travers les fentes de la paroi latérale 60.In summary, the main advantage of the electromagnetic confinement according to the invention by the cage 50 is that the periphery of the conductive part of the load, even composed of a cold conductive material, is spaced from the internal face of the side wall 60 of the latter, over substantially its entire height and not only at the level of the main inductor 1, with the concomitant reduction of the heat losses by conduction, and of the risks of flows through the slots of the side wall 60.

Il est à remarquer ici qu'au lieu de relier les deux extrémités libres de chaque inducteur en épingle à cheveux à deux anneaux collecteurs distincts 120, 130, il est possible de les relier électriquement et même hydrauliquement en série, c'est-à-dire de relier ensemble, par exemple, au moyen de tronçons de jonction transversaux, semblables à ceux désignés par le repère 74, les extrémités inférieures avoisinantes des différents segments 70. On obtient alors un inducteur serpentin, replié en cylindre, de haute impédance. Il est également possible de réaliser des combinaisons série-parallèle de ces inducteurs en épingles à cheveux en réunissant en série un certain nombre entre eux par groupes d'égale inductance et de réunir ces groupes en parallèle afin d'obtenir l'impédance que l'on désire en fonction des dimensions de la cage 50 et de la fréquence du second générateur 24, choisie en conséquence.It should be noted here that instead of connecting the two free ends of each hairpin inductor to two separate collecting rings 120, 130, it is possible to connect them electrically and even hydraulically in series, that is to say say to connect together, for example, by means of transver junction sections saux, similar to those designated by the reference 74, the neighboring lower ends of the different segments 70. A serpentine inductor, folded into a cylinder, of high impedance is then obtained. It is also possible to make series-parallel combinations of these hairpin inductors by bringing a number together in series with groups of equal inductance and to bring these groups together in parallel in order to obtain the impedance that the it is desired according to the dimensions of the cage 50 and the frequency of the second generator 24, chosen accordingly.

Les liaisons électriques entre les tronçons tubulaires longitudinaux 71, 72 ne sont pas obligatoirement réalisées à l'aide de tronçons transversaux 74 qui en assurent également la continuité hydraulique. Il est également possible d'assurer l'alimentation en fluide réfrigérant de la manière illustrée sur la figure 1, c'est-à-dire en utilisant des joints tubulaires isolants, et l'alimentation électrique en série au moyen de plaques conductrices métalliques transversales (en cuivre, par exemple) en forme d'arcs de cercle de longueur suffisante pour recouvrir au moins en partie les bouts (10, figure 1) de deux tronçons (7, figure 1) voisins pour former un segment 70 en épingle à cheveux. Ces plaques de liaison (non représentées) peuvent être rendues mécaniquement et électriquement solidaires des bouts de tronçons qu'elles recouvrent par soudure ou brasage. Elles peuvent même remplacer les plaques en bout (10, figure 1) obturant les extrémités des tronçons tubulaires (7, figure 1) qu'elles doivent alors recouvrir entièrement. En utilisant des plaques de liaison de mêmes dimensions, il est possible de réaliser des inducteurs en serpentin susmentionnés, où les tronçons sont connectés en série.The electrical connections between the longitudinal tubular sections 71, 72 are not necessarily carried out using transverse sections 74 which also provide hydraulic continuity. It is also possible to supply the coolant as illustrated in FIG. 1, that is to say by using insulating tubular joints, and the electrical supply in series by means of transverse metallic conductive plates. (in copper, for example) in the form of circular arcs of sufficient length to at least partially cover the ends (10, FIG. 1) of two neighboring sections (7, FIG. 1) to form a segment 70 in hairpin . These connecting plates (not shown) can be made mechanically and electrically integral with the ends of sections which they cover by welding or brazing. They can even replace the end plates (10, Figure 1) closing the ends of the tubular sections (7, Figure 1) which they must then completely cover. By using connecting plates of the same dimensions, it is possible to produce the above-mentioned serpentine inductors, where the sections are connected in series.

Pour réaliser les segments 70 on peut utiliser de manière connue du tube métalliques de cuivre ou d'un alliage de cuivre (laitons, bronzes) ou d'un alliage de nickel avec d'autres métaux, tels que le cuivre ou le chrome. Pour la fusion des métaux ou d'alliages refractaires, par exemple, il est avantageux d'utiliser un alliage de nickel, de chrome et de fer (0,78 Ni + 0,14Cr + 0,07Fe), tel que celui qui est commercialisé sous la dénomination "INCONEL" (marque déposée par la société américaine International Nickel Co.) et qui est particulièrement adapté pour des températures élevée.To produce the segments 70, it is possible to use, in a known manner, a metal tube of copper or of a copper alloy (brasses, bronzes) or of a nickel alloy with other metals, such as copper or chromium. For the fusion of metals or refractory alloys, for example, it is advantageous to use an alloy of nickel, chromium and iron (0.78 Ni + 0.14Cr + 0.07Fe), such as that which is marketed under the name "INCONEL" (trademark registered by the American company International Nickel Co.) and which is particularly suitable for high temperatures.

Claims (11)

1. Dispositif de fusion par induction directe d'une charge disposée à l'intérieur d'une cage froide (50) comprenant une paroi latérale (60) cylindrique et à axe vertical, composée de tronçons conducteurs tubulaires (71, 72) orientés parallèlement à cet axe, parcourus d'un fluide de refroidissement et disposés côte à côte de manière galvaniquement isolée l'un de l'autre, afin qu'elle soit sensiblement transparente au champ magnétique alternatif d'un inducteur solénoidal (1) entourant coaxialement cette paroi latérale (60) et alimenté par un premier générateur de puissance (2) d'une première haute ou moyenne fréquence, ce champ magnétique engendrant, outre des courants induits dans la charge, des premières forces de confinement agissant sur la périphérie de celle-ci au niveau de l'inducteur (1), caractérisé en ce que la paroi latérale (60) froide de la cage (50) est agencée de telle sorte qu'elle constitue en même temps un inducteur de confinement de type connu en soi, qui est alimenté par un second générateur de puissance (24) d'une second haute ou moyenne fréquence et qui comporte, outre les tronçons tubulaires juxtaposés (71, 72), des moyens de liaison électrique (74) reliant ensemble les extrémités adjacentes de deux tronçons tubulaires voisins, afin que ceux-ci soient parcourus respectivement d'un courant alternatif dans des sens opposés, engendrant dans la partie conductrice de la périphérie de la charge des forces de confinement supplémentaire.1. Device for direct induction melting of a charge placed inside a cold cage (50) comprising a cylindrical side wall (60) and with a vertical axis, composed of tubular conductive sections (71, 72) oriented in parallel to this axis, traversed by a cooling fluid and arranged side by side in a galvanically isolated manner from each other, so that it is substantially transparent to the alternating magnetic field of a solenoidal inductor (1) coaxially surrounding this side wall (60) and supplied by a first power generator (2) of a first high or medium frequency, this magnetic field generating, in addition to the currents induced in the load, first confinement forces acting on the periphery thereof ci at the level of the inductor (1), characterized in that the cold side wall (60) of the cage (50) is arranged so that it constitutes at the same time a confinement inductor of a type known per se, which is powered p ar a second power generator (24) of a second high or medium frequency and which comprises, in addition to the juxtaposed tubular sections (71, 72), electrical connection means (74) connecting together the adjacent ends of two neighboring tubular sections , so that they are respectively traversed by an alternating current in opposite directions, generating in the conductive part of the periphery of the load of the additional confinement forces. 2. Dispositif de fusion suivant la revendication 1, caractérisé en ce que les tronçons tubulaires (71, 72) sont réunies ensemble à l'aide de premiers moyens de liaison électrique (74) agencés de telle sorte que chacun en relie une extrémité d'un premier tronçon (71) à l'extrémité correspondante d'un second tronçon (72) adjacent, pour que chacun des segments (70) de la paroi latérale (60) constitue un inducteur en forme d'épingle à cheveux dont les extrémités opposées, libres, sont couplées au second générateur (24).2. Melting device according to claim 1, characterized in that the tubular sections (71, 72) are joined together using first electrical connection means (74) arranged so that each connects one end thereof. a first section (71) at the corresponding end of an adjacent second section (72), so that each of the segments (70) of the side wall (60) constitutes a hairpin-shaped inductor whose opposite ends , free, are coupled to the second generator (24). 3. Dispositif de fusion suivant la revendication 2, caractérisé en ce que les segments (70) en épingle à cheveux sont électriquement réunis en parallèle.3. Fusion device according to claim 2, characterized in that the hairpin segments (70) are electrically connected in parallel. 4. Dispositif de fusion suivant la revendication 2, caractérisé en ce que les segments (70) en épingle à cheveux sont électriquement réunis en série à l'aide de seconds moyens de liaison électrique qui réunissent respectivement leurs extrémités libres à celles des tronçons adjacents des segments voisins, afin de former un dipôle unique.4. Fusion device according to claim 2, characterized in that the hairpin segments (70) are electrically joined in series using second electrical connection means which respectively join their free ends to those of the adjacent sections of the neighboring segments, in order to form a single dipole. 5. Dispositif suivant la revendication 2, caractérisé en ce que des groupes comportant respectivement un nombre égal de segments (70) en épingle à cheveux, reliés en série à l'aide de seconds moyens de liaison électrique, sont reliées en parallèle pour en former une combinaison dite série-parallèle.5. Device according to claim 2, characterized in that groups respectively comprising an equal number of hairpin segments (70), connected in series by means of second electrical connection means, are connected in parallel to form a combination called series-parallel. 6. Dispositif suivant l'une des revendications précédentes, caractérisé en ce que les moyens de liaison électrique sont respectivement constitués par des tronçons tubulaires transversaux (74) assurant en même temps la continuité électrique et celle du circuit hydraulique de refroidissement.6. Device according to one of the preceding claims, characterized in that the electrical connection means are respectively constituted by transverse tubular sections (74) ensuring at the same time the electrical continuity and that of the hydraulic cooling circuit. 7. Dispositif suivant l'une des revendications précédentes, caractérisé en ce que la puissance fournie par le second générateur (24) à l'inducteur de confinement est comprise entre un dizième et un cinquième de celle fournie par le premier générateur (2) à l'inducteur (1) entourant la paroi latérale (60).7. Device according to one of the preceding claims, characterized in that the power supplied by the second generator (24) to the confinement inductor is between one tenth and one fifth of that supplied by the first generator (2) to the inductor (1) surrounding the side wall (60). 8. Procédé d'utilisation d'un dispositif de fusion par induction directe suivant l'une des revendications précédentes, pour une charge composée de substances métalliques, conductrices à froid, caractérisé en ce que l'on ajoute et mélange à cette charge métallique, une substance isolante à froid, présentant des températures d'inductibilité et de fusion voisines et inférieures au point de fusion du ou des métaux constituant la charge, afin que cette substance isolante constitue, après sa fusion, un laitier qui s'agglomère au voisinage de la paroi latérale froide (60) de la cage (50) et se répende dans l'espace que l'inducteur de confinement à ménagé entre celle-ci et la périphérie de la charge, en y formant après refroidissement, une pellicule isolante solide.8. A method of using a direct induction melting device according to one of the preceding claims, for a charge composed of metallic substances, cold conductive, characterized in that this metallic charge is added and mixed, a cold insulating substance, having inducibility and melting temperatures close to and below the melting point of the metal or metals constituting the filler, so that this insulating substance constitutes, after its melting, a slag which agglomerates in the vicinity of the cold side wall (60) of the cage (50) and is distributed in the space that the confinement inductor has provided between the latter and the periphery of the load, forming thereon after cooling, a solid insulating film. 9. Procédé suivant la revendication 8, caractérisé en ce que la proportion pondérale de la substance isolante additive par rapport au poids total de la charge, est comprise entre 0, 5 et 1, 5 pour cent.9. Method according to claim 8, characterized in that the weight proportion of the additive insulating substance relative to the total weight of the filler is between 0.5 and 1.5 percent. 10. Procédé suivant l'une des revendications 8 et 9, caractérisé en ce que la substance isolante additive est constituée par un composé de calcium et de fluor, tel que le fluorure de calcium (CaF2) ou fluorine.10. Method according to one of claims 8 and 9, characterized in that the additive insulating substance consists of a calcium and fluorine compound, such as calcium fluoride (CaF 2 ) or fluorine. 11. Procédé suivant l'une des revendications 8 et 9, caractérisé en ce que la substance isolante additive est constituée par de la silice (Si02), avec des adjuvants éventuels tels que des borates.11. Method according to one of claims 8 and 9, characterized in that the additive insulating substance consists of silica (Si0 2 ), with optional adjuvants such as borates.
EP81401845A 1980-12-23 1981-11-20 Arrangement for direct induction melting in a cooled vessel with supplementary electromagnetic confinement of the contents Expired EP0056915B1 (en)

Applications Claiming Priority (2)

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FR8027320A FR2497050A1 (en) 1980-12-23 1980-12-23 COLD CAGE DIRECT INDUCTION FUSION DEVICE WITH ELECTROMAGNETIC CONTAINMENT OF MOLTEN LOAD
FR8027320 1980-12-23

Publications (2)

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EP0056915A1 true EP0056915A1 (en) 1982-08-04
EP0056915B1 EP0056915B1 (en) 1984-07-25

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EP81401845A Expired EP0056915B1 (en) 1980-12-23 1981-11-20 Arrangement for direct induction melting in a cooled vessel with supplementary electromagnetic confinement of the contents

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US (1) US4432093A (en)
EP (1) EP0056915B1 (en)
CA (1) CA1179022A (en)
DE (1) DE3165120D1 (en)
FR (1) FR2497050A1 (en)

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EP0273975A1 (en) * 1986-07-04 1988-07-13 Vsesojuzny Nauchno-Issledovatelsky Proektno-Konstruktorsky I Tekhnologichesky Inst. Elektrotermicheskogo Oborudovania Vniieto Induction plasma furnace
FR2621387A1 (en) * 1987-10-06 1989-04-07 Commissariat Energie Atomique INDUCTION OVEN CUP
EP0398821A2 (en) * 1989-05-08 1990-11-22 Howmet Corporation Segmented induction skull melting crucible and method
EP0439900A2 (en) * 1990-01-31 1991-08-07 Inductotherm Corp. Induction heating apparatus and method
EP0538024A1 (en) * 1991-10-16 1993-04-21 Shinko Denki Kabushiki Kaisha Segmented cold-wall induction melting crucible
US5257281A (en) * 1990-01-31 1993-10-26 Inductotherm Corp. Induction heating apparatus and method
DE4429340A1 (en) * 1994-08-18 1996-02-22 Leybold Durferrit Gmbh Crucible for inductive heating/melting of metals
US6400026B1 (en) 1999-06-24 2002-06-04 Nec Corporation Semiconductor device with the copper containing aluminum alloy bond pad on an active region
EP2629037A1 (en) * 2012-02-14 2013-08-21 Korea Hydro & Nuclear Power Co., Ltd. Low temperature melting furnace and metal sector using an external cooling passage
EP2629036A1 (en) * 2012-02-14 2013-08-21 Korea Hydro & Nuclear Power Co., Ltd. Low temperature melting furnace having improved cooling flow and metal sector

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FR2548856A1 (en) * 1983-07-08 1985-01-11 Saphymo Stel Device for fusion by direct induction in a segmented cold cage
FR2566890B1 (en) * 1984-06-29 1986-11-14 Commissariat Energie Atomique COLD CAGE FOR HIGH FREQUENCY ELECTROMAGNETIC INDUCTION MELTING CRUCIBLE
FR2599482B1 (en) * 1986-06-03 1988-07-29 Commissariat Energie Atomique HIGH FREQUENCY INDUCTION FUSION OVEN
FR2609655B1 (en) * 1987-01-15 1989-03-24 Cezus Co Europ Zirconium CONTINUOUS MELTING AND CASTING DEVICE, METHOD FOR IMPLEMENTING SAME AND USE THEREOF
FR2648065A1 (en) * 1989-06-12 1990-12-14 Solvay DEVICE FOR RECOVERING BY MELTING THE METAL CONSTITUTING A FUSE CORE
DE3940029C2 (en) * 1989-12-04 1994-04-14 Leybold Ag Crucibles for induction heating
US5550353A (en) * 1990-01-31 1996-08-27 Inductotherm Corp. Induction heating coil assembly for prevent of circulating current in induction heating lines for continuous-cast products
US5090022A (en) * 1990-05-21 1992-02-18 Inductotherm Corp. Cold crucible induction furnace
FR2665249A1 (en) * 1990-07-26 1992-01-31 Dauphine Ets Bonmartin Laminoi Furnace for smelting by induction in a cold crucible
JP2967092B2 (en) * 1991-12-20 1999-10-25 科学技術庁金属材料技術研究所長 Floating melting equipment
US5275229A (en) * 1992-03-25 1994-01-04 Inductotherm Corp. Magnetic suspension melting apparatus
DE4320766C2 (en) * 1993-06-23 2002-06-27 Ald Vacuum Techn Ag Device for melting a solid layer of electrically conductive material
EP0641146B1 (en) * 1993-08-26 1999-10-06 Inductotherm Corp. Magnetic suspension melting apparatus
DE4423196A1 (en) * 1994-07-01 1996-01-04 Wacker Siltronic Halbleitermat Heating element for heating crucibles
FR2740646B1 (en) * 1995-10-27 1998-01-16 Electricite De France COLD CAGE FOR INDUCTION DEVICE
DE19629636A1 (en) * 1996-07-23 1998-01-29 Ald Vacuum Techn Gmbh Induction heating crucible for electrically conductive materials
FR2871151B1 (en) * 2004-06-07 2006-08-11 Centre Nat Rech Scient Cnrse SILICON REFINING INSTALLATION
FR3092656B1 (en) * 2019-02-07 2021-03-19 Inst Polytechnique Grenoble Cold crucible
FR3092655B1 (en) * 2019-02-07 2021-02-12 Inst Polytechnique Grenoble Cold crucible
CN115896475A (en) * 2022-11-07 2023-04-04 宁波锦越新材料有限公司 Ultra-high purity aluminum fine grain preparation equipment

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FR1508992A (en) * 1966-10-13 1968-01-12 Comp Generale Electricite High load levitation and fusion device
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FR2397251A1 (en) * 1977-07-12 1979-02-09 Anvar METHOD AND DEVICE FOR DIRECTING, IN THE ABSENCE OF WALLS, LIQUID METALLIC VEINS, IN PARTICULAR FOR CENTERING, GUIDING OR CHECKING THEIR CIRCULAR SHAPE
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GB1145769A (en) * 1966-01-28 1969-03-19 Standard Telephones Cables Ltd Improvements in or relating to apparatus for the heat treatment of electrically conductive materials
FR1492063A (en) * 1966-04-05 1967-08-18 Commissariat Energie Atomique Further development of high frequency electric furnaces for the continuous production of electro-cast refractories
US3775091A (en) * 1969-02-27 1973-11-27 Interior Induction melting of metals in cold, self-lined crucibles
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US1801791A (en) * 1930-03-05 1931-04-21 Westinghouse Electric & Mfg Co Induction-furnace protective circuits
DE1147714B (en) * 1957-08-01 1963-04-25 Vacuumschmelze Ag Device and method for holding and transporting electrically conductive, free-floating substances
FR1508992A (en) * 1966-10-13 1968-01-12 Comp Generale Electricite High load levitation and fusion device
GB1221909A (en) * 1969-10-01 1971-02-10 Standard Telephones Cables Ltd Improvements in or relating to apparatus for the heat treatment of electrically conductive materials
FR2397251A1 (en) * 1977-07-12 1979-02-09 Anvar METHOD AND DEVICE FOR DIRECTING, IN THE ABSENCE OF WALLS, LIQUID METALLIC VEINS, IN PARTICULAR FOR CENTERING, GUIDING OR CHECKING THEIR CIRCULAR SHAPE
US4215738A (en) * 1979-03-30 1980-08-05 Olin Corporation Anti-parallel inductors for shape control in electromagnetic casting

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0273975A1 (en) * 1986-07-04 1988-07-13 Vsesojuzny Nauchno-Issledovatelsky Proektno-Konstruktorsky I Tekhnologichesky Inst. Elektrotermicheskogo Oborudovania Vniieto Induction plasma furnace
EP0273975A4 (en) * 1986-07-04 1988-09-28 Vni Pk I T I Elektroterm Oboru Induction plasma furnace.
FR2621387A1 (en) * 1987-10-06 1989-04-07 Commissariat Energie Atomique INDUCTION OVEN CUP
EP0311506A1 (en) * 1987-10-06 1989-04-12 Commissariat A L'energie Atomique Crucible for an induction furnace
US4873698A (en) * 1987-10-06 1989-10-10 Commissariat A L'energie Atomique Induction furnace crucible
EP0398821A2 (en) * 1989-05-08 1990-11-22 Howmet Corporation Segmented induction skull melting crucible and method
EP0398821A3 (en) * 1989-05-08 1991-02-06 Howmet Corporation Segmented induction skull melting crucible and method
EP0439900A3 (en) * 1990-01-31 1993-03-03 Inductotherm Corp. Induction heating apparatus and method
EP0439900A2 (en) * 1990-01-31 1991-08-07 Inductotherm Corp. Induction heating apparatus and method
US5257281A (en) * 1990-01-31 1993-10-26 Inductotherm Corp. Induction heating apparatus and method
EP0538024A1 (en) * 1991-10-16 1993-04-21 Shinko Denki Kabushiki Kaisha Segmented cold-wall induction melting crucible
DE4429340A1 (en) * 1994-08-18 1996-02-22 Leybold Durferrit Gmbh Crucible for inductive heating/melting of metals
DE4429340C2 (en) * 1994-08-18 2003-04-30 Ald Vacuum Techn Ag Crucibles for inductive melting or overheating of metals, alloys or other electrically conductive materials
US6400026B1 (en) 1999-06-24 2002-06-04 Nec Corporation Semiconductor device with the copper containing aluminum alloy bond pad on an active region
EP2629037A1 (en) * 2012-02-14 2013-08-21 Korea Hydro & Nuclear Power Co., Ltd. Low temperature melting furnace and metal sector using an external cooling passage
EP2629036A1 (en) * 2012-02-14 2013-08-21 Korea Hydro & Nuclear Power Co., Ltd. Low temperature melting furnace having improved cooling flow and metal sector
US8767794B2 (en) 2012-02-14 2014-07-01 Korea Hydro & Nuclear Power Co., Ltd. Low temperature melting furnace and metal sector using an external cooling passage

Also Published As

Publication number Publication date
CA1179022A (en) 1984-12-04
DE3165120D1 (en) 1984-08-30
FR2497050B1 (en) 1984-06-22
US4432093A (en) 1984-02-14
EP0056915B1 (en) 1984-07-25
FR2497050A1 (en) 1982-06-25

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