EP0990474B1 - Inert gas shrouding device for moulds for the continuous casting of metals - Google Patents

Inert gas shrouding device for moulds for the continuous casting of metals Download PDF

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Publication number
EP0990474B1
EP0990474B1 EP99402209A EP99402209A EP0990474B1 EP 0990474 B1 EP0990474 B1 EP 0990474B1 EP 99402209 A EP99402209 A EP 99402209A EP 99402209 A EP99402209 A EP 99402209A EP 0990474 B1 EP0990474 B1 EP 0990474B1
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European Patent Office
Prior art keywords
membrane
mould
gas
mold
liquid metal
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EP99402209A
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German (de)
French (fr)
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EP0990474A1 (en
Inventor
Eric Perrin
Cosimo Salaris
Edouard Weisseldinger
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Ugine-Savoie Imphy En Sollac En SA
Forges et Acieries de Dilling SA
Sollac SA
Ugitech SA
Original Assignee
Forges et Acieries de Dilling SA
Ascometal SA
Sollac SA
Ugine Savoie Imphy SA
Lorraine de Laminage Continu SA SOLLAC
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/106—Shielding the molten jet
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds

Definitions

  • the invention relates to the continuous casting of metals such as steel. More specifically, it relates to devices ensuring the protection of the liquid metal present in the mold against possible chemical reactions with ambient air.
  • Continuous steel casting facilities include an ingot mold without bottom, the walls of which are energetically cooled internally by circulation of water, and are made of a metal that is a good conductor of heat such as copper or its alloys.
  • the liquid steel is continuously introduced into the ingot mold, coming from a container called “distributor” which overhangs it, and it begins its solidification by forming a solid crust against the internal walls of the mold.
  • the product (called slab, bloom or billet according to its shape and dimensions) is continuously extracted from the mold and completes its solidification at heart outside the mold, thanks to an external cooling by spraying water.
  • Liquid steel entering the ingot mold must be protected from ambient air, in order to avoid an increase in its nitrogen content and the formation of oxidized inclusions within it.
  • the jet of liquid metal flowing from the distributor is most often protected by a tube of refractory material whose lower end plunges into the bath metallic present in the mold.
  • cover powder usually the free surface of the liquid steel present in the mold is covered by an oxide-based powder, called "cover powder". Its functions are multiple. Besides the protection of steel against ambient air, it stops the radiation from the surface, and thus reduces the metal heat losses. And by infiltrating between the solidified crust and the mold, it provides lubrication of the mold-product interface which allows the extraction of product is produced without risk of tearing of the solidified crust. This extraction is also facilitated by vertical oscillations, and possibly also vibrations ultrasonic printed in the mold.
  • Burning the oil reduces the oxygen content of the ambient atmosphere, but it can only imperfectly protect the metal against reoxidation.
  • This action must then be supplemented by gaseous inerting of the surface environment metal.
  • This inerting is conventionally carried out by insufflation of argon (or nitrogen for casting grades which tolerate high levels of this element) around the jet and on the free surface of the liquid metal.
  • argon or nitrogen for casting grades which tolerate high levels of this element
  • the object of the invention is to propose a device for inerting the environment of the surface of the liquid metal bath in an ingot mold more efficient than the devices existing.
  • the invention relates to a space inerting device surrounding the free surface of the molten metal poured into a continuous casting mold metals located under a distributor, according to claim 1.
  • the invention consists in interposing between the bottom of the distributor and the upper edge of the mold an annular seal which is inflated by a gas under pressure. It is made of a material resistant to heat and sufficiently permeable gas (preferably due to its natural porosity) so that gas leaking from the joint come fill the space delimited by the gasket, the bottom of the distributor and the upper edge of the ingot mold, and in which are the pouring jet and the free surface of the liquid metal poured into the mold.
  • This seal is fixed to the bottom of the distributor or to the upper edge of the ingot mold, and must, once inflated, have a thickness such that it is sufficient to fill the space separating the distributor and the ingot mold when this space has its width maximum (i.e. when the mold, during its oscillation cycle, is in its lowest position).
  • the single figure shows schematically the upper part of an installation continuous casting of steel billets.
  • a distributor 1 containing liquid steel 2, and of which only the bottom 3 is shown.
  • the bottom 3 has a calibrated nozzle 4 through which the liquid steel 2 flows to form a pouring jet 5.
  • This enters the interior space of a bottomless ingot mold 6 whose walls 7, 8, 9 are energetically cooled internally by water circulating in non-ducts represented.
  • the liquid steel 2 present in the mold 6 gradually solidifies against the walls 7, 8, 9 to form the outer crust 10 of a cast product 11 which is extract from the mold 6 by known means not shown.
  • the product 11 is sprayed with water through nozzles 12, 13, 14, 15 to accelerate its cooling.
  • a layer of lubricating oil 16 covers the surface 17 of the steel liquid 2 present in the ingot mold 6. This is driven by an oscillating movement vertical according to arrow 18, by known means not shown.
  • the amplitude of these oscillations can be of the order of a few mm to a few cm, and their frequency of in the order of a few Hz.
  • Oil can also, in known manner, be supplied in various points of the wall interface 7, 8, 9-crust 10 by orifices (not shown) formed in the walls 7, 8, 9.
  • the felt is in the form of a commercial strip which is rolled up to form a tube which is closed according to a generator by sewing or gluing, then which is closed on itself to form a ring.
  • the membrane 19 can be coated, on its portion facing the outside of the space 27, by a gas-tight material, so that all the gas leaving the membrane 19 is effectively introduced into the space 27.
  • the plate 25 can also be given a relatively thick important and integrate a transparent window, through which we can have access visual on the surface 17 of the liquid metal 2 in an ingot mold, so as to make it possible the use of a device for regulating the level of this surface 17 of a type comprising a camera or any other device requiring optical access to the surface 17.
  • Another variant would be to fix the plate 25 either on the bottom 3 of the distributor 1, but on the upper edge 26 of the mold 6.
  • the plate 25 is only one example of a means of fixing the membrane 19, and any other type of fixing means which can play the same function is usable.
  • the device according to the invention in addition to its effectiveness for protecting the metal liquid, has the advantages of ease of installation and use. In particular, it is very tolerant of slight variations in height positioning of the distributor 1 (a few mm) that can usually be encountered.
  • the device according to the invention can also be used on installations for casting which include, instead of an oscillating ingot mold, an ingot mold to which prints low amplitude and high frequency movements using transmitters ultrasonic, as well as molds on which such movements are superimposed on classic oscillations. It is also applicable in the case of ingot molds which are extended upwards by an extension of refractory material inside which maintains the surface of the liquid steel.
  • the device according to the invention can also be used in the case where the casting jet 5 is itself protected by a tube of refractory material. It is applicable to the casting of products of all formats. Likewise, it is applicable to continuous casting other metals than steel.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)

Abstract

Continuous steel casting device, comprises a blanketing device having a ring shaped inflatable membrane made of a gas permeable material in order to protect the surface of the molten metal. Blanketing device of the gap (27) surrounding the free surface (17) of the liquid metal (2) which is continuously cast in an ingot mould (6) positioned under an adaptor (1) having a cast gate (5) of liquid metal (2) feeding the ingot mould, comprises a ring-shaped inflatable membrane (19) made of a gas permeable material. The thickness of the membrane (when inflated) is superior to the maximal distance between the top flange (26) of the ingot mould and the bottom (3) of the adaptor during casting. A tubular armature (20) is positioned inside the membrane and is provided with at least one intake manifold (21,22) for an inert gas. The device also comprises outlets (23,24) for releasing the gas into the membrane, fixing elements (25) for fixing the membrane on the bottom (3) of the adaptor or on the top flange (26) of the ingot mold, the membrane surrounding the casting gate, inflating means to inflate the membrane and to keep it inflated and in seal contact with the bottom of the adaptor and the top flange of the ingot mold.

Description

L'invention concerne la coulée continue des métaux tels que l'acier. Plus précisément, elle concerne les dispositifs assurant la protection du métal liquide présent dans la lingotière contre les possibles réactions chimiques avec l'air ambiant.The invention relates to the continuous casting of metals such as steel. More specifically, it relates to devices ensuring the protection of the liquid metal present in the mold against possible chemical reactions with ambient air.

Les installations de coulée continue de l'acier comportent une lingotière sans fond, dont les parois sont énergiquement refroidies intérieurement par une circulation d'eau, et sont réalisées en un métal bon conducteur de la chaleur tel que le cuivre ou ses alliages. L'acier liquide est introduit en continu dans la lingotière, en provenance d'un récipient appelé « répartiteur » qui la surplombe, et il y amorce sa solidification en formant une croûte solide contre les parois internes de la lingotière. Le produit (appelé brame, bloom ou billette selon sa forme et ses dimensions) est continûment extrait de la lingotière et achève sa solidification à coeur hors de la lingotière, grâce à un refroidissement externe par aspersion d'eau.Continuous steel casting facilities include an ingot mold without bottom, the walls of which are energetically cooled internally by circulation of water, and are made of a metal that is a good conductor of heat such as copper or its alloys. The liquid steel is continuously introduced into the ingot mold, coming from a container called “distributor” which overhangs it, and it begins its solidification by forming a solid crust against the internal walls of the mold. The product (called slab, bloom or billet according to its shape and dimensions) is continuously extracted from the mold and completes its solidification at heart outside the mold, thanks to an external cooling by spraying water.

L'acier liquide qui pénètre dans la lingotière doit être protégé de l'air ambiant, afin d'éviter une augmentation de sa teneur en azote et la formation d'inclusions oxydées en son sein. A cet effet, le jet de métal liquide s'écoulant du répartiteur est le plus souvent protégé par un tube en matériau réfractaire dont l'extrémité inférieure plonge dans le bain métallique présent dans la lingotière. D'autre part, habituellement, la surface libre de l'acier liquide présent dans la lingotière est recouverte par une poudre à base d'oxydes, appelée « poudre de couverture ». Ses fonctions sont multiples. Outre la protection de l'acier contre l'air ambiant, elle arrête le rayonnement de la surface, et ainsi diminue les pertes thermiques du métal. Et en s'infiltrant entre la croûte solidifiée et la lingotière, elle assure une lubrification de l'interface lingotière-produit qui permet que l'extraction du produit s'effectue sans risque de déchirement de la croûte solidifiée. Cette extraction est également facilitée par des oscillations verticales, et aussi éventuellement des vibrations ultrasonores imprimées à la lingotière.Liquid steel entering the ingot mold must be protected from ambient air, in order to avoid an increase in its nitrogen content and the formation of oxidized inclusions within it. For this purpose, the jet of liquid metal flowing from the distributor is most often protected by a tube of refractory material whose lower end plunges into the bath metallic present in the mold. On the other hand, usually the free surface of the liquid steel present in the mold is covered by an oxide-based powder, called "cover powder". Its functions are multiple. Besides the protection of steel against ambient air, it stops the radiation from the surface, and thus reduces the metal heat losses. And by infiltrating between the solidified crust and the mold, it provides lubrication of the mold-product interface which allows the extraction of product is produced without risk of tearing of the solidified crust. This extraction is also facilitated by vertical oscillations, and possibly also vibrations ultrasonic printed in the mold.

Il y a cependant des cas où l'utilisation d'une poudre de couverture n'est pas possible, à savoir lorsque le produit coulé est de petit format et que l'utilisation d'un tube de protection risquerait de provoquer la formation de « ponts » de métal solidifié entre le tube et la lingotière. Il faut alors couler avec un jet de métal exposé à l'atmosphère ambiante, dont l'impact sur une surface revêtue de poudre de couverture provoquerait un entraínement de poudre au sein du métal, donc une grave pollution du produit. La présence de poudre de couverture doit donc être exclue, et la lubrification de l'interface lingotière-produit est alors assurée par une amenée de lubrifiant liquide sur la surface du métal, voire aussi à travers la paroi de la lingotière, à différents points de l'interface paroi-croûte solidifiée. La combustion de l'huile réduit la teneur en oxygène de l'atmosphère ambiante, mais elle ne peut assurer qu'imparfaitement la protection du métal contre les réoxydations. Il faut alors compléter cette action par un inertage gazeux de l'environnement de la surface du métal. Cet inertage est classiquement réalisé par une insufflation d'argon (ou d'azote pour la coulée de nuances qui tolèrent des teneurs importantes en cet élément) autour du jet et sur la surface libre du métal liquide. Pour réaliser un meilleur confinement de cette atmosphère protectrice, on relie souvent le fond du répartiteur et le bord supérieur de la lingotière par un soufflet en réfractaire fibreux qui, par sa souplesse, autorise les déplacements verticaux de la lingotière oscillante. L'amplitude de ces déplacements peut atteindre quelques dizaines de mm. L'expérience montre cependant que ces méthodes de protection ne sont pas totalement satisfaisantes et n'empêchent parfois pas suffisamment le métal de se réoxyder. On ne mesure que très rarement une teneur en oxygène au voisinage de la surface inférieure à 3%, ce qui est encore trop élevé. Cette oxydation excessive du métal se traduit par la formation d'inclusions oxydées dont certaines décantent à la surface du métal et doivent être périodiquement enlevées manuellement par les opérateurs. Mais si on utilise un soufflet isolant l'environnement de la lingotière de l'atmosphère extérieure, cet enlèvement n'est pas possible. Quant aux inclusions qui ne décantent pas, elles demeurent au sein du métal et détériorent sa qualité.There are however cases where the use of a covering powder is not possible, i.e. when the cast product is small and the use of a tube could cause the formation of "bridges" of solidified metal between the tube and ingot mold. It is then necessary to sink with a metal jet exposed to the atmosphere ambient, the impact of which on a surface coated with covering powder would cause a entrainment of powder within the metal, therefore serious pollution of the product. The presence covering powder must therefore be excluded, and lubrication of the ingot mold-product interface is then provided by a supply of liquid lubricant to the surface of the metal, or even also through the wall of the mold, at different points of the wall-crust interface solidified. Burning the oil reduces the oxygen content of the ambient atmosphere, but it can only imperfectly protect the metal against reoxidation. This action must then be supplemented by gaseous inerting of the surface environment metal. This inerting is conventionally carried out by insufflation of argon (or nitrogen for casting grades which tolerate high levels of this element) around the jet and on the free surface of the liquid metal. To achieve better containment of this protective atmosphere, we often connect the bottom of the distributor and the upper edge of the ingot mold by a fibrous refractory bellows which, by its flexibility, allows vertical movements of the oscillating ingot mold. The amplitude of these displacements can reach a few tens of mm. However, experience shows that these methods of protection are not completely satisfactory and sometimes do not sufficiently prevent the metal to reoxidize. Oxygen content is only very rarely measured in the vicinity of the surface less than 3%, which is still too high. This excessive oxidation of the metal results in the formation of oxidized inclusions, some of which settle on the surface metal and must be periodically removed manually by operators. But if a bellows is used which isolates the environment of the mold from the external atmosphere, this removal is not possible. As for the inclusions which do not settle, they remain within the metal and deteriorate its quality.

Le but de l'invention est de proposer un dispositif d'inertage de l'environnement de la surface du bain de métal liquide en lingotière plus efficace que les dispositifs existants.The object of the invention is to propose a device for inerting the environment of the surface of the liquid metal bath in an ingot mold more efficient than the devices existing.

A cet effet, l'invention a pour objet un dispositif d'inertage de l'espace environnant la surface libre du métal liquide coulé dans une lingotière de coulée continue des métaux située sous un répartiteur, selon la revendication 1.To this end, the invention relates to a space inerting device surrounding the free surface of the molten metal poured into a continuous casting mold metals located under a distributor, according to claim 1.

Comme on l'aura compris, l'invention consiste à interposer entre le fond du répartiteur et le bord supérieur de la lingotière un joint annulaire que l'on gonfle par un gaz sous pression. Il est réalisé en une matière résistant à la chaleur et suffisamment perméable aux gaz (de préférence sous l'effet de sa porosité naturelle) pour que du gaz fuyant du joint vienne remplir l'espace délimité par le joint, le fond du répartiteur et le rebord supérieur de la lingotière, et dans lequel se trouvent le jet de coulée et la surface libre du métal liquide coulé dans la lingotière. Ce joint est fixé au fond du répartiteur ou au rebord supérieur de la lingotière, et doit, une fois gonflé, présenter une épaisseur telle qu'elle suffise à combler l'espace séparant le répartiteur et la lingotière lorsque cet espace présente sa largeur maximale (c'est à dire lorsque la lingotière, au cours de son cycle d'oscillation, est dans sa position la plus basse).As will be understood, the invention consists in interposing between the bottom of the distributor and the upper edge of the mold an annular seal which is inflated by a gas under pressure. It is made of a material resistant to heat and sufficiently permeable gas (preferably due to its natural porosity) so that gas leaking from the joint come fill the space delimited by the gasket, the bottom of the distributor and the upper edge of the ingot mold, and in which are the pouring jet and the free surface of the liquid metal poured into the mold. This seal is fixed to the bottom of the distributor or to the upper edge of the ingot mold, and must, once inflated, have a thickness such that it is sufficient to fill the space separating the distributor and the ingot mold when this space has its width maximum (i.e. when the mold, during its oscillation cycle, is in its lowest position).

L'invention sera mieux comprise à la lecture de la description qui suit, donnée en référence à la figure unique annexée, qui montre vu de face et en coupe transversale un dispositif selon l'invention, installé sur une machine de coulée continue des métaux.The invention will be better understood on reading the description which follows, given in reference to the attached single figure, which shows a front view and in cross section a device according to the invention, installed on a continuous metal casting machine.

La figure unique montre schématiquement la partie supérieure d'une installation de coulée continue de billettes d'acier. De manière classique, elle comporte un répartiteur 1 renfermant de l'acier liquide 2, et dont seul le fond 3 est représenté. Le fond 3 comporte une busette calibrée 4 par laquelle s'écoule l'acier liquide 2 pour former un jet de coulée 5. Celui-ci pénètre dans l'espace intérieur d'une lingotière sans fond 6 dont les parois 7, 8, 9 sont énergiquement refroidies intérieurement par de l'eau circulant dans des canaux non représentés. L'acier liquide 2 présent dans la lingotière 6 se solidifie progressivement contre les parois 7, 8, 9 pour former la croûte extérieure 10 d'un produit coulé 11 qui est extrait de la lingotière 6 par des moyens connus non représentés. A sa sortie de la lingotière 6, le produit 11 est arrosé avec de l'eau par des buses 12, 13, 14, 15 pour accélérer son refroidissement. Une couche d'huile de lubrification 16 recouvre la surface 17 de l'acier liquide 2 présent dans la lingotière 6. Celle-ci est animée d'un mouvement d'oscillation verticale selon la flèche 18, grâce à des moyens connus non représentés. L'amplitude de ces oscillations peut être de l'ordre de quelques mm à quelques cm, et leur fréquence de l'ordre de quelques Hz. De l'huile peut aussi, de manière connue, être amenée en divers points de l'interface paroi 7, 8, 9-croûte 10 par des orifices (non représentés) ménagés dans les parois 7, 8, 9.The single figure shows schematically the upper part of an installation continuous casting of steel billets. Conventionally, it includes a distributor 1 containing liquid steel 2, and of which only the bottom 3 is shown. The bottom 3 has a calibrated nozzle 4 through which the liquid steel 2 flows to form a pouring jet 5. This enters the interior space of a bottomless ingot mold 6 whose walls 7, 8, 9 are energetically cooled internally by water circulating in non-ducts represented. The liquid steel 2 present in the mold 6 gradually solidifies against the walls 7, 8, 9 to form the outer crust 10 of a cast product 11 which is extract from the mold 6 by known means not shown. On leaving the mold 6, the product 11 is sprayed with water through nozzles 12, 13, 14, 15 to accelerate its cooling. A layer of lubricating oil 16 covers the surface 17 of the steel liquid 2 present in the ingot mold 6. This is driven by an oscillating movement vertical according to arrow 18, by known means not shown. The amplitude of these oscillations can be of the order of a few mm to a few cm, and their frequency of in the order of a few Hz. Oil can also, in known manner, be supplied in various points of the wall interface 7, 8, 9-crust 10 by orifices (not shown) formed in the walls 7, 8, 9.

L'installation de coulée continue est munie d'un dispositif d'inertage évitant que le jet de coulée 5 et la surface 17 de l'acier liquide 2 présent dans la lingotière 6 ne soient exposés à une atmosphère réactive telle que l'air ambiant. Selon l'invention, ce dispositif comporte :

  • une membrane gonflable 19 de forme annulaire, réalisée en un matériau réfractaire souple poreux, pouvant résister à des températures de l'ordre de 800 à 900°C environ ;
  • une armature métallique tubulaire 20, logée à l'intérieur de la membrane 19 ; elle est pourvue de tuyaux 21, 22 d'amenée d'un gaz d'inertage neutre tel que de l'argon ou de l'azote dans son intérieur et d'orifices 23, 24 de quelques mm de diamètre par lesquels ce gaz neutre s'échappe à l'intérieur de la membrane 19 pour assurer son gonflage, puis l'inertage de l'espace environnant le jet de coulée 5 et la surface 17 de l'acier liquide 2 présent dans la lingotière 6 ;
  • une plaque annulaire 25 à laquelle sont fixées les parties supérieures de la membrane 19 et de l'armature 20, et qui est elle-même fixée au fond 3 du répartiteur 1, de manière à ce que la membrane 19 entoure le jet de coulée 5.
The continuous casting installation is provided with an inerting device preventing the casting jet 5 and the surface 17 of the liquid steel 2 present in the mold 6 from being exposed to a reactive atmosphere such as ambient air. . According to the invention, this device comprises:
  • an inflatable membrane 19 of annular shape, made of a porous flexible refractory material, capable of withstanding temperatures of the order of about 800 to 900 ° C .;
  • a tubular metal frame 20, housed inside the membrane 19; it is provided with pipes 21, 22 for supplying a neutral inerting gas such as argon or nitrogen in its interior and orifices 23, 24 a few mm in diameter through which this neutral gas escapes inside the membrane 19 to ensure its inflation, then the inerting of the space surrounding the casting jet 5 and the surface 17 of the liquid steel 2 present in the mold 6;
  • an annular plate 25 to which the upper parts of the membrane 19 and of the frame 20 are fixed, and which is itself fixed to the bottom 3 of the distributor 1, so that the membrane 19 surrounds the pouring jet 5 .

Des moyens classiques non représentés d'insufflation d'un gaz neutre alimentent les tuyaux 21, 22 dans des conditions de débit et de pression telles que l'on obtient un gonflage de la membrane 19 qui lui procure une forme s'approchant de celle d'un tore. Les dimensions de la membrane sont calculées pour qu'une fois gonflée, elle puisse combler à l'état comprimé, à la manière d'un joint torique, l'espace séparant le fond 3 du répartiteur 1 et le rebord supérieur 26 de la lingotière 6, même lorsque la lingotière 6 et le répartiteur 1 se trouvent à leur distance maximale lors du cycle d'oscillation de la lingotière 6. Sous l'effet de la pression interne régnant dans la membrane 19, celle-ci est en permanence en contact souple et étanche avec le rebord supérieur 26 de la lingotière 6, qui est lui-même mis en mouvement par les oscillations de la lingotière 6.Conventional means, not shown, for insufflating a neutral gas supply pipes 21, 22 under flow and pressure conditions such that a inflation of the membrane 19 which gives it a shape approaching that of a torus. The dimensions of the membrane are calculated so that once inflated, it can fill at the compressed state, like an O-ring, the space separating the bottom 3 from the distributor 1 and the upper edge 26 of the mold 6, even when the mold 6 and the distributor 1 are at their maximum distance during the oscillation cycle of the ingot mold 6. Under the effect of the internal pressure prevailing in the membrane 19, the latter is permanently in flexible and sealed contact with the upper edge 26 of the mold 6, which is itself set in motion by the oscillations of the mold 6.

Du fait du caractère poreux de la membrane 19, une fraction du gaz qui la gonfle s'échappe dans l'espace intérieur 27 délimité par la membrane 19, le répartiteur 1 et la lingotière 6, et contribue à rendre son atmosphère inerte vis-à-vis du jet de coulée 5 et de la surface 17 de l'acier liquide 2 présent dans la lingotière. Surtout si on assure également une bonne étanchéité du contact entre la plaque 25 et le fond 3 du répartiteur 1, on peut ainsi obtenir une teneur en oxygène de l'ordre de 0,5% dans l'espace 27, ce qui est suffisamment bas pour y supprimer les réoxydations significatives du métal liquide 2. On n'observe, en effet, plus de formation d'oxydes à la surface du bain 17, et il n'est plus nécessaire de procéder à un nettoyage périodique de cette surface 17.Due to the porous nature of the membrane 19, a fraction of the gas which swells it escapes into the interior space 27 delimited by the membrane 19, the distributor 1 and the ingot mold 6, and contributes to making its atmosphere inert with respect to the casting jet 5 and the surface 17 of the liquid steel 2 present in the mold. Especially if we also provide a good sealing of the contact between the plate 25 and the bottom 3 of the distributor 1, it is thus possible obtain an oxygen content of the order of 0.5% in space 27, which is sufficient down there to suppress significant reoxidation of the liquid metal 2. We do not observe, in effect, more formation of oxides on the surface of the bath 17, and it is no longer necessary to carry out periodic cleaning of this surface 17.

A titre d'exemple, on peut utiliser une membrane 19 en feutre réfractaire à base de graphite, présentant une porosité de l'ordre de 70% et une épaisseur de 8 mm. Initialement, le feutre se présente sous la forme d'une bande du commerce que l'on enroule pour former un tube que l'on ferme selon une génératrice par couture ou collage, puis que l'on referme sur lui-même pour former un anneau. Pour assurer le gonflage de la membrane 19, on injecte 150 Nl/mn d'azote sous une pression de 1 bar. Cette injection gazeuse permet également de refroidir suffisamment la membrane 19 pour éviter sa détérioration thermique.By way of example, a membrane 19 made of refractory felt based on graphite, having a porosity of around 70% and a thickness of 8 mm. Initially, the felt is in the form of a commercial strip which is rolled up to form a tube which is closed according to a generator by sewing or gluing, then which is closed on itself to form a ring. To ensure the inflation of the membrane 19, we injects 150 Nl / min of nitrogen under a pressure of 1 bar. This gas injection allows also to sufficiently cool the membrane 19 to avoid its deterioration thermal.

Optionnellement, on peut revêtir la membrane 19, sur sa portion tournée vers l'extérieur de l'espace 27, par un matériau étanche au gaz, de manière à ce que tout le gaz sortant de la membrane 19 soit effectivement introduit dans l'espace 27.Optionally, the membrane 19 can be coated, on its portion facing the outside of the space 27, by a gas-tight material, so that all the gas leaving the membrane 19 is effectively introduced into the space 27.

En variante, on peut aussi donner à la plaque 25 une épaisseur relativement importante et lui intégrer une fenêtre transparente, par laquelle on peut avoir un accès visuel à la surface 17 du métal liquide 2 en lingotière, de manière à rendre possible l'utilisation d'un dispositif de régulation du niveau de cette surface 17 d'un type comportant une caméra ou tout autre dispositif nécessitant un accès optique à la surface 17. Alternatively, the plate 25 can also be given a relatively thick important and integrate a transparent window, through which we can have access visual on the surface 17 of the liquid metal 2 in an ingot mold, so as to make it possible the use of a device for regulating the level of this surface 17 of a type comprising a camera or any other device requiring optical access to the surface 17.

Une autre variante consisterait à fixer la plaque 25 non plus sur le fond 3 du répartiteur 1, mais sur le rebord supérieur 26 de la lingotière 6.Another variant would be to fix the plate 25 either on the bottom 3 of the distributor 1, but on the upper edge 26 of the mold 6.

Bien entendu, la plaque 25 n'est qu'un exemple de moyen de fixation de la membrane 19, et tout autre type de moyen de fixation pouvant jouer la même fonction est utilisable.Of course, the plate 25 is only one example of a means of fixing the membrane 19, and any other type of fixing means which can play the same function is usable.

Le dispositif selon l'invention, outre son efficacité pour la protection du métal liquide, a pour avantages la facilité de sa mise en place et de son utilisation. En particulier, il est très tolérant vis-à-vis des légères variations de positionnement en hauteur du répartiteur 1 (quelques mm) que l'on peut habituellement rencontrer.The device according to the invention, in addition to its effectiveness for protecting the metal liquid, has the advantages of ease of installation and use. In particular, it is very tolerant of slight variations in height positioning of the distributor 1 (a few mm) that can usually be encountered.

Le dispositif selon l'invention peut aussi être employé sur les installations de coulée qui comportent, au lieu d'une lingotière oscillante, une lingotière à laquelle on imprime des mouvements de faible amplitude et de forte fréquence au moyen d'émetteurs ultrasonores, ainsi qu'aux lingotières sur lesquelles de tels mouvements se superposent aux oscillations classiques. Il est également applicable au cas des lingotières qui sont prolongées vers le haut par une réhausse en matériau réfractaire à l'intérieur de laquelle on maintient la surface de l'acier liquide.The device according to the invention can also be used on installations for casting which include, instead of an oscillating ingot mold, an ingot mold to which prints low amplitude and high frequency movements using transmitters ultrasonic, as well as molds on which such movements are superimposed on classic oscillations. It is also applicable in the case of ingot molds which are extended upwards by an extension of refractory material inside which maintains the surface of the liquid steel.

Il va de soi que le dispositif selon l'invention est utilisable aussi dans le cas où le jet de coulée 5 est lui-même protégé par un tube en matériau réfractaire. Il est applicable à la coulée de produits de tous formats. De même, il est applicable à la coulée continue d'autres métaux que l'acier.It goes without saying that the device according to the invention can also be used in the case where the casting jet 5 is itself protected by a tube of refractory material. It is applicable to the casting of products of all formats. Likewise, it is applicable to continuous casting other metals than steel.

Claims (4)

  1. Device for inerting the space surrounding the free surface of a liquid metal poured into a mould for the continuous casting of metals which is located beneath a tundish from which a pouring jet of liquid metal feeding the mould flows, which device comprises an annular membrane which is made of a gas-permeable flexible refractory material, said membrane being associated with a tubular support member that is provided with means for fastening the membrane in a position such that it surrounds the pouring jet and is provided with an inlet for injecting an inerting gas into its interior and with outlet holes via which said gas escapes inside said membrane, and characterized in that, for the purpose of forming a flexible annular seal connecting the upper rim (26) of the mould (6) at the bottom (3) of the tundish (1 );
    said membrane (19) has, in the inflated state, a thickness greater than the maximum distance separating the upper rim (26) of the mould (6) from the bottom (3) of the tundish (1) during casting;
    said tubular support member (20) is housed inside membrane (19);
    and means for blowing said inerting gas into said inlet (21,22) are provided, allowing the membrane (19) to be inflated and maintained in the compressed state in simultaneous sealed contact with the bottom (3) of the tundish (1) and with the upper rim (26) of the mould (6).
  2. Device according to Claim 1, characterized in that said membrane (19) is made of a graphite-based refractory felt.
  3. Device according to Claim 1 or 2, characterized in that said membrane (19) is coated, on its portion facing the outside of the space (27) surrounding the free surface (17) of the liquid metal (2) present in the mould (6), with a material impermeable to the inerting gas.
  4. Device according to one of Claims 1 to 3, characterized in that the said membrane fastening means consist of an annular plate (25) comprising a window made of a transparent material giving optical access to the free surface (17) of the liquid metal (2) present in the mould (6).
EP99402209A 1998-09-28 1999-09-09 Inert gas shrouding device for moulds for the continuous casting of metals Expired - Lifetime EP0990474B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9812128 1998-09-28
FR9812128A FR2783732B1 (en) 1998-09-28 1998-09-28 INERT DEVICE FOR CONTINUOUS METAL CASTING LINGOTIER

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EP0990474A1 EP0990474A1 (en) 2000-04-05
EP0990474B1 true EP0990474B1 (en) 2003-12-17

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EP99402209A Expired - Lifetime EP0990474B1 (en) 1998-09-28 1999-09-09 Inert gas shrouding device for moulds for the continuous casting of metals

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JP (1) JP2000176614A (en)
KR (1) KR20000023354A (en)
AT (1) ATE256517T1 (en)
BR (1) BR9904398A (en)
CA (1) CA2284375A1 (en)
DE (1) DE69913631T2 (en)
ES (1) ES2213337T3 (en)
FR (1) FR2783732B1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4999627B2 (en) * 2007-10-04 2012-08-15 日本冶金工業株式会社 Molten alloy sealing device, casting method using this device, and method for shutting off air at the start of continuous casting
JP5008516B2 (en) * 2007-10-10 2012-08-22 日本冶金工業株式会社 Molten alloy sealing device, casting method using this device, and method for shutting off air at the start of continuous casting

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE445983C (en) * 1927-06-21 Siemens Schuckertwerke G M B H Device for sealing the glow area of glow ovens
JPS5072709U (en) * 1973-11-12 1975-06-26
CH660700A5 (en) * 1983-08-12 1987-06-15 Finanz Handels Invest Fhi SHIELDING DEVICE FOR A MOLDING BEAM FROM LIQUID MATERIAL.
SU1675049A1 (en) * 1989-03-09 1991-09-07 Научно-производственное объединение по механизации, роботизации труда и совершенствованию ремонтного обеспечения на предприятиях черной металлургии "Черметмеханизация" Device for protecting metal stream against oxidation
US5131573A (en) * 1991-03-22 1992-07-21 Allegheny Ludlum Corporation Method and device for shrouding a stream of molten metal

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Publication number Publication date
FR2783732B1 (en) 2000-10-27
ATE256517T1 (en) 2004-01-15
KR20000023354A (en) 2000-04-25
DE69913631T2 (en) 2004-12-23
DE69913631D1 (en) 2004-01-29
EP0990474A1 (en) 2000-04-05
FR2783732A1 (en) 2000-03-31
BR9904398A (en) 2000-12-26
JP2000176614A (en) 2000-06-27
ES2213337T3 (en) 2004-08-16
CA2284375A1 (en) 2000-03-28

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