EP0527717B1 - Method and device for continuous casting a molten metal - Google Patents
Method and device for continuous casting a molten metal Download PDFInfo
- Publication number
- EP0527717B1 EP0527717B1 EP92870117A EP92870117A EP0527717B1 EP 0527717 B1 EP0527717 B1 EP 0527717B1 EP 92870117 A EP92870117 A EP 92870117A EP 92870117 A EP92870117 A EP 92870117A EP 0527717 B1 EP0527717 B1 EP 0527717B1
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- European Patent Office
- Prior art keywords
- tubular element
- refractory material
- mould
- casting
- molten metal
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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
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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
- B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
Definitions
- the present invention relates to a process for the continuous casting of a molten metal, in particular steel according to the preamble of claim 1. It also relates to a device for carrying out this process according to the preamble of the claim 2.
- Continuous casting is a widely used technique which allows steel to be poured directly from a casting container into a bottomless ingot mold, from which it is extracted in the form of a continuous, partially solidified strand.
- the pouring container is usually a ladle or a distribution basket; for simplicity, we will refer here, in a generic way, to a distribution basket.
- the bottom of the distribution basket is pierced with a hole with which a shutter member of known type cooperates.
- a pouring nozzle Under the bottom of the basket and coaxially to the pouring hole is fixed a pouring nozzle, which plunges freely into the upper part of the mold itself.
- This ingot mold is made of copper and is cooled with water.
- the ingot mold is usually driven in an oscillating movement, of an amplitude of a few millimeters, intended to prevent the steel from sticking to its walls.
- the steel from the distribution basket flows through the nozzle into the mold, where it gradually solidifies, forming a skin of increasing thickness.
- the lower end of the nozzle is immersed in liquid steel, the upper level, or meniscus, is located in the upper portion of the mold.
- the current technique of continuous casting has various drawbacks which are the source of the defects observed in the cast products.
- it is very difficult to maintain a rigorously constant level of steel in the ingot mold, mainly when the steel flow rate is high and the ingot mold is of small section; these variations in level disturb the start of solidification and cause surface defects in the products.
- the casting speed therefore remains limited, in particular for products of small cross-section.
- it is not possible to completely prevent the formation of internal cracks and axial segregation in the cast products, despite all the precautions that can be taken to achieve precise control of equipment and manufacturing conditions.
- the object of the present invention is to provide a method, as well as an implementation device, for the continuous casting of a molten metal, which enables high quality products to be cast at high speed as regards surface condition and internal health.
- the basic idea of the invention is to prevent the meniscus from establishing itself in the region where the skin of the metal begins to solidify.
- a process for the casting of a molten metal in which the molten metal is poured into an ingot mold where it solidifies, is characterized in that the upper level, or meniscus, is established, of said molten metal in a region located upstream from the point where solidification of said metal begins in the mold.
- an oscillation movement preferably vertical, having an amplitude less than 0.5 mm, and advantageously of the order of 0.2-0.3 mm, is applied to the ingot mold.
- a forced lubrication of the ingot mold is carried out, preferably by injecting a lubricant through at least one of its walls.
- the solidification of the molten metal begins and always continues in the ingot mold, as in the conventional casting processes; however, the meniscus is thrown upstream from where this solidification begins.
- the variations in the level of the metal that is to say the position of the meniscus, therefore no longer disturb the start of solidification and no longer result in surface defects in the cast product.
- the invention also relates to a device for the continuous casting of a molten metal, which comprises a pouring vessel provided with a pouring orifice and a bottomless ingot mold placed under said pouring orifice, characterized in that it comprises a tubular element of refractory material disposed between the pouring container and the mold, in alignment with the latter, in that said tubular element of refractory material is rigidly fixed, by its lower end, to the upper part of the mold, and in that said tubular element of refractory material is connected by its upper end to said casting container.
- the mold is advantageously equipped with means intended to reduce the friction between the cast product and the wall of the mold, in particular means for applying to the mold a vibration having an amplitude less than 0.5 mm, preferably of the order of 0.2-0.3 mm, and / or means for carrying out forced lubrication by injecting a lubricant through at least one wall.
- An elastic seal is preferably interposed between said tubular element of refractory material and the casting container, in order to absorb the vibrations originating from the mold and not to damage the tubular element.
- Different devices can be placed between the bottom of the casting container and the upper end of said tubular element of refractory material, under the essential condition that these devices constitute a closed assembly between the casting container and said tubular element, and preferably with interposition of the aforementioned elastic seal between said closed assembly and the tubular element.
- tubular element made of refractory material can be equipped with means for causing intense agitation of the metal which it contains, in particular inductors intended to put the metal in rotation in said tubular element.
- the section of said tubular element of refractory material preferably has a shape which corresponds to that of the mold. It is advantageously slightly smaller than the latter.
- Fig. 1 shows the principle of the casting device of the invention, which consists in making a closed enclosure from the casting container to the mold and establishing the meniscus in a region where the metal remains in the liquid state.
- the casting device of the invention comprises a distribution basket 1 with, in the bottom, a tap hole 2 which can be closed by a stopper 3.
- a stopper 3 In this respect, it goes without saying that any other type could be used known shutter member, for example a drawer shutter.
- a tubular element 4 of refractory material is placed under the bottom of the distributor basket 1, coaxially with the tap hole 2.
- the tubular element 4 is assembled to the mold 5, by means of a seal made of refractory material 6.
- the mold 5 is made of copper and is equipped with a cooling system. , not shown.
- it is driven by a low amplitude oscillation movement, applied by means not shown here; the vibrations are absorbed by an elastic seal 21 and they are therefore not transmitted to the distribution basket.
- the seal in refractory material 6 is of the "break ring" type used in horizontal continuous casting machines; it is for example made of boron nitride.
- the ingot mold 5 is followed by a secondary cooling system 7, which is not part of the present invention and which can be a conventional system composed of support rollers and sprinklers.
- the steel is poured from the distributor basket 1 into the tubular element 4 made of refractory material and then into the cooled copper ingot mold 5.
- the meniscus 8 is located in the tubular element 4 made of refractory material, and the position of this meniscus is controlled by a flow control device of known type; in the present invention, it is not necessary for the control of this position to be carried out very precisely.
- Solidification of the steel surface begins at the entrance to the mold, immediately after the refractory seal 6; it continues in the usual way in the mold 5 and in the secondary cooling system 7, to form a solidified skin 20 of increasing thickness.
- a variation in the position of the meniscus 8 during casting therefore has no effect on the place where the solidification of the steel surface begins and therefore no longer results in the formation of surface defects.
- the section of the mold 5 can be as small as desired, for example for the continuous casting of thin slabs, since the device no longer comprises a submerged nozzle.
- the tubular element 4 may have a section of small dimensions, proportionate to those of the mold. It suffices that the inlet section of the tubular element 4 can receive the pouring jet 9 coming from the distributor basket 1.
- this tubular element 4 is shown here with a constant section over its entire length; it goes without saying that this section could vary over the length of the tubular element 4, preferably with at least one section having a smaller section than the ingot mold, to give this element the profile of a funnel for example.
- the casting speed is limited in particular by the instability of the position of the meniscus 8, which increases when the casting speed increases and which therefore multiplies the risks of formation of surface defects. Thanks to the device of the invention, this risk is largely eliminated and the casting speed can be significantly increased.
- Fig. 2 illustrates a particular continuous casting installation which applies the principle set out in FIG. 1.
- This installation comprises several additional devices, known per se, which make it possible in particular to cast the steel with low overheating and to accelerate the cooling of the cast product. All these devices are placed in series and they are aligned along the axis of the casting installation; in the representation of FIG. 2, this axis is vertical, but it could just as easily be curved, as is the case in different types of continuous casting machines.
- a vertical duct 10 also called a hollow jet nozzle, composed of a refractory section 11 and a cooled metal section 12.
- a dome 13 of refractory material defining a peripheral channel with the inner wall of the refractory section 11.
- the dome 13 is equipped with a cane 14 for injecting gas inside the metal section 12.
- the refractory section 11 is generally cylindrical, while the metal section 12 is advantageously convergent, to take account of a certain contraction due to the start of cooling and solidification, as will be recalled below.
- the vertical conduit 10 opens at its lower end into the tubular element 4 made of refractory material which has been defined above.
- the elastic seal 21 is placed between the vertical duct 10 and the tubular element 4.
- This tubular element 4 is provided with inductors 15, intended to stir the steel present in the tubular element 4.
- the tubular element 4 is connected to the ingot mold 5 made of copper, cooled with water.
- the ingot mold is here equipped with a forced lubrication system, symbolized by the arrows 16 which indicate the channels for introducing the lubricant. This is introduced into the area at the start of the solidification of the steel.
- a secondary cooling device 7 comprising a system 18 of intense cooling by means of a layer of water under pressure, and a system 19 of moderate cooling in the calmer water of the cast product. .
- the volume occupied by the water is shown in dotted lines.
- the steel poured from the distributor basket 1 through the taphole falls on the refractory dome 13, which deflects it towards the inner wall of the section refractory 11 of the conduit 10. Through the peripheral channel, the steel then flows in a thin film along the inner wall of the section 12. This film is maintained along the wall by the pressurized gas blown through the cane 14 .
- the steel initially exhibits a slight overheating, for example of the order of 20 ° C., it can undergo in the metal section 12 a start of cooling, which makes it slightly pasty.
- This steel then reaches the tubular element 4 of refractory material, where it does not undergo significant cooling.
- the inductors 15 give it a rotational movement which produces an intense mixing of the steel, makes it very homogeneous and provides it with a sufficiently low viscosity.
- the steel finally enters the ingot mold 5 where, upon contact with the seal 6, it begins to solidify in a conventional manner, with a solidified skin 20 of increasing thickness.
- Solidification continues in the secondary cooling device 7: the system 18 ensures intense cooling of the skin of the product, and the moderate cooling system 19 prevents too rapid heating of the skin after the intense cooling. This secondary cooling in two stages makes it possible to greatly reduce the formation of internal cracks in the cast product.
- slightly pasty steel solidifies with a homogeneous structure, exhibiting almost zero axial segregation.
- the method of the invention and its implementation device therefore make it possible to flow steel products more quickly which have an excellent surface condition and very good internal health.
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Abstract
Description
La présente invention concerne un procédé pour la coulée continue d'un métal en fusion, en particulier de l'acier suivant le préambule de la revendication 1. Elle porte également sur un dispositif pour la mise en oeuvre de ce procédé suivant le préambule de la revendication 2.The present invention relates to a process for the continuous casting of a molten metal, in particular steel according to the preamble of
Pour fixer les idées, la description qui suit fait référence plus particulièrement à la coulée continue de l'acier. Ce choix n'a cependant qu'un caractère d'exemple et n'entraîne aucune limitation de l'objet de l'invention, lequel est défini par les revendications annexées.To fix the ideas, the following description refers more particularly to the continuous casting of steel. This choice is however only an example and does not limit the subject of the invention, which is defined by the appended claims.
La coulée continue est une technique largement répandue, qui permet de couler l'acier directement d'un récipient de coulée dans une lingotière sans fond, de laquelle il est extrait sous la forme d'un brin continu partiellement solidifié. Le récipient de coulée est habituellement une poche de coulée ou un panier répartiteur; pour simplifier, on se réfèrera ici, d'une manière générique, à un panier répartiteur.Continuous casting is a widely used technique which allows steel to be poured directly from a casting container into a bottomless ingot mold, from which it is extracted in the form of a continuous, partially solidified strand. The pouring container is usually a ladle or a distribution basket; for simplicity, we will refer here, in a generic way, to a distribution basket.
Dans la pratique courante, le fond du panier répartiteur est percé d'un trou avec lequel coopère un organe d'obturation de type connu. Sous le fond du panier et coaxialement au trou de coulée est fixée une busette de coulée, qui plonge librement dans la partie supérieure de la lingotière proprement dite. Cette lingotière est en cuivre et est refroidie à l'eau. De plus, la lingotière est habituellement animée d'un mouvement d'oscillation, d'une amplitude de quelques millimètres, destiné à empêcher le collage de l'acier à ses parois.In current practice, the bottom of the distribution basket is pierced with a hole with which a shutter member of known type cooperates. Under the bottom of the basket and coaxially to the pouring hole is fixed a pouring nozzle, which plunges freely into the upper part of the mold itself. This ingot mold is made of copper and is cooled with water. In addition, the ingot mold is usually driven in an oscillating movement, of an amplitude of a few millimeters, intended to prevent the steel from sticking to its walls.
En fonctionnement, l'acier provenant du panier répartiteur s'écoule par la busette dans la lingotière, où il se solidifie progressivement en formant une peau d'épaisseur croissante. L'extrémité inférieure de la busette est immergée dans l'acier liquide, dont le niveau supérieur, ou ménisque, est situé dans la portion supérieure de la lingotière.In operation, the steel from the distribution basket flows through the nozzle into the mold, where it gradually solidifies, forming a skin of increasing thickness. The lower end of the nozzle is immersed in liquid steel, the upper level, or meniscus, is located in the upper portion of the mold.
La technique actuelle de la coulée continue présente divers inconvénients qui sont à l'origine de défauts observés dans les produits coulés. Il est notamment très difficile de maintenir un niveau rigoureusement constant de l'acier dans la lingotière, principalement lorsque le débit d'acier est élevé et que la lingotière est de petite section; ces variations du niveau perturbent le démarrage de la solidification et provoquent des défauts de surface dans les produits. La vitesse de coulée reste de ce fait limitée, en particulier pour les produits de petite section. Enfin, il n'est pas possible d'empêcher complètement la formation de criques internes et de ségrégations axiales dans les produits coulés, malgré toutes les précautions qui peuvent être prises pour réaliser un contrôle précis des équipements et des conditions de fabrication.The current technique of continuous casting has various drawbacks which are the source of the defects observed in the cast products. In particular, it is very difficult to maintain a rigorously constant level of steel in the ingot mold, mainly when the steel flow rate is high and the ingot mold is of small section; these variations in level disturb the start of solidification and cause surface defects in the products. The casting speed therefore remains limited, in particular for products of small cross-section. Finally, it is not possible to completely prevent the formation of internal cracks and axial segregation in the cast products, despite all the precautions that can be taken to achieve precise control of equipment and manufacturing conditions.
La présente invention a pour objet de proposer un procédé, ainsi qu'un dispositif de mise en oeuvre, pour la coulée continue d'un métal en fusion, qui permet de couler à grande vitesse des produits de haute qualité en ce qui concerne l'état de surface et la santé interne.The object of the present invention is to provide a method, as well as an implementation device, for the continuous casting of a molten metal, which enables high quality products to be cast at high speed as regards surface condition and internal health.
L'idée de base de l'invention est d'éviter que le ménisque s'établisse dans la région où commence la solidification de la peau du métal.The basic idea of the invention is to prevent the meniscus from establishing itself in the region where the skin of the metal begins to solidify.
Conformément à la présente invention, un procédé pour la coulée d'un métal en fusion, dans lequel on coule le métal en fusion dans une lingotière où il se solidifie, est caractérisé en ce que l'on établit le niveau supérieur, ou ménisque, dudit métal en fusion dans une région située en amont du point où commence la solidification dudit métal dans la lingotière.In accordance with the present invention, a process for the casting of a molten metal, in which the molten metal is poured into an ingot mold where it solidifies, is characterized in that the upper level, or meniscus, is established, of said molten metal in a region located upstream from the point where solidification of said metal begins in the mold.
Il est intéressant de réduire le frottement entre le produit coulé et la paroi intérieure de la lingotière. A cet effet, on applique à la lingotière un mouvement d'oscillation, de préférence vertical, ayant une amplitude inférieure à 0,5 mm, et avantageusement de l'ordre de 0,2 -0,3 mm. De même, on réalise une lubrification forcée de la lingotière, de préférence en injectant un lubrifiant à travers au moins une de ses parois.It is advantageous to reduce the friction between the cast product and the internal wall of the mold. To this end, an oscillation movement, preferably vertical, having an amplitude less than 0.5 mm, and advantageously of the order of 0.2-0.3 mm, is applied to the ingot mold. Similarly, a forced lubrication of the ingot mold is carried out, preferably by injecting a lubricant through at least one of its walls.
Dans le procédé de l'invention, la solidification du métal en fusion commence et se poursuit toujours dans la lingotière, comme dans les procédés de coulée conventionnels; toutefois, le ménisque est rejeté vers l'amont par rapport à l'endroit où commence cette solidification. Les variations du niveau du métal, c'est-à-dire de la position du ménisque, ne perturbent dès lors plus le démarrage de la solidification et ne se traduisent plus par des défauts de surface dans le produit coulé.In the process of the invention, the solidification of the molten metal begins and always continues in the ingot mold, as in the conventional casting processes; however, the meniscus is thrown upstream from where this solidification begins. The variations in the level of the metal, that is to say the position of the meniscus, therefore no longer disturb the start of solidification and no longer result in surface defects in the cast product.
L'invention concerne également un dispositif pour la coulée continue d'un métal en fusion, qui comprend un récipient de coulée pourvu d'un orifice de coulée et une lingotière sans fond placée sous ledit orifice de coulée, caractérisé en ce qu'il comporte un élément tubulaire en matière réfractaire disposé entre le récipient de coulée et la lingotière, en alignement avec celle-ci, en ce que ledit élément tubulaire en matière réfractaire est rigidement fixé, par son extrémité inférieure, à la partie supérieure de la lingotière, et en ce que ledit élément tubulaire en matière réfractaire est relié par son extrémité supérieure audit récipient de coulée.The invention also relates to a device for the continuous casting of a molten metal, which comprises a pouring vessel provided with a pouring orifice and a bottomless ingot mold placed under said pouring orifice, characterized in that it comprises a tubular element of refractory material disposed between the pouring container and the mold, in alignment with the latter, in that said tubular element of refractory material is rigidly fixed, by its lower end, to the upper part of the mold, and in that said tubular element of refractory material is connected by its upper end to said casting container.
La lingotière est avantageusement équipée de moyens destinés à réduire le frottement entre le produit coulé et la paroi de la lingotière, notamment des moyens pour appliquer à la lingotière une vibration ayant une amplitude inférieure à 0,5 mm, de préférence de l'ordre de 0,2-0,3 mm, et/ou des moyens pour réaliser une lubrification forcée en injectant un lubrifiant à travers au moins une paroi.The mold is advantageously equipped with means intended to reduce the friction between the cast product and the wall of the mold, in particular means for applying to the mold a vibration having an amplitude less than 0.5 mm, preferably of the order of 0.2-0.3 mm, and / or means for carrying out forced lubrication by injecting a lubricant through at least one wall.
Un joint élastique est de préférence interposé entre ledit élément tubulaire en matière réfractaire et le récipient de coulée, afin d'absorber les vibrations provenant de la lingotière et de ne pas endommager l'élément tubulaire.An elastic seal is preferably interposed between said tubular element of refractory material and the casting container, in order to absorb the vibrations originating from the mold and not to damage the tubular element.
Différents dispositifs peuvent être placés entre le fond du récipient de coulée et l'extrémité supérieure dudit élément tubulaire en matière réfractaire, sous la condition essentielle que ces dispositifs constituent un ensemble fermé entre le récipient de coulée et ledit élément tubulaire, et de préférence avec interposition du joint élastique précité entre ledit ensemble fermé et l'élément tubulaire.Different devices can be placed between the bottom of the casting container and the upper end of said tubular element of refractory material, under the essential condition that these devices constitute a closed assembly between the casting container and said tubular element, and preferably with interposition of the aforementioned elastic seal between said closed assembly and the tubular element.
En particulier, on peut monter un dispositif à tiroir de fermeture de l'orifice de coulée sous le fond dudit récipient de coulée, et assembler ledit élément tubulaire à ce dispositif de fermeture.In particular, it is possible to mount a device for closing the pouring orifice drawer under the bottom of said pouring container, and to assemble said tubular element to this closing device.
Il est également intéressant de monter, entre le récipient de coulée et ledit élément tubulaire, un dispositif de coulée à jet creux du genre de celui qui est décrit dans le document EP-A-0269180 sur lequel les preámbules des revendications 1 et 2 sont basésIt is also advantageous to mount, between the casting container and said tubular element, a hollow jet casting device of the type described in document EP-A-0269180 on which the preambles of
De même, ledit élément tubulaire en matière réfractaire peut être équipé de moyens pour provoquer une agitation intense du métal qu'il contient, en particulier des inducteurs destinés à mettre le métal en rotation dans ledit élément tubulaire.Likewise, said tubular element made of refractory material can be equipped with means for causing intense agitation of the metal which it contains, in particular inductors intended to put the metal in rotation in said tubular element.
La section dudit élément tubulaire en matière réfractaire a de préférence une forme qui correspond à celle de la lingotière. Elle est avantageusement légèrement plus petite que cette dernière.The section of said tubular element of refractory material preferably has a shape which corresponds to that of the mold. It is advantageously slightly smaller than the latter.
D'autres particularités et avantages de la présente invention sont indiqués dans la description détaillée qui va suivre, et qui est illustrée par les dessins annexés, dans lesquels la
- Fig. 1 présente le principe du dispositif de coulée de l'invention; et la
- Fig. 2 montre une installation de coulée continue verticale faisant application de ce principe.
- Fig. 1 shows the principle of the casting device of the invention; and the
- Fig. 2 shows a vertical continuous casting installation applying this principle.
Ces figures constituent des représentations schématiques, sans échelle particulière, dans lesquelles on n'a reproduit que les éléments nécessaires à la compréhension de l'invention. Des éléments identiques ou analogues sont désignés par les mêmes repères numériques dans toutes les figures.These figures constitute schematic representations, without any particular scale, in which only the elements necessary for understanding the invention have been reproduced. Identical or analogous elements are designated by the same reference numerals in all the figures.
La Fig. 1 présente le principe du dispositif de coulée de l'invention, qui consiste à réaliser une enceinte fermée depuis le récipient de coulée jusqu'à la lingotière et à établir le ménisque dans une région où le métal reste à l'état liquide.Fig. 1 shows the principle of the casting device of the invention, which consists in making a closed enclosure from the casting container to the mold and establishing the meniscus in a region where the metal remains in the liquid state.
Le dispositif de coulée de l'invention comprend un panier répartiteur 1 avec, dans le fond, un trou de coulée 2 qui peut être obturé par une quenouille 3. A cet égard, il va de soi que l'on pourrait utiliser tout autre type connu d'organe d'obturation, par exemple un obturateur à tiroir. Un élément tubulaire 4 en matière réfractaire est placé sous le fond du panier répartiteur 1, coaxialement au trou de coulée 2.The casting device of the invention comprises a
A son extrémité inférieure, l'élément tubulaire 4 est assemblé à la lingotière 5, par l'intermédiaire d'un joint en matière réfractaire 6. De façon connue, la lingotière 5 est en cuivre et elle est équipée d'un système de refroidissement, non représenté. De plus, elle est animée d'un mouvement d'oscillation de faible amplitude, appliqué par des moyens non représentés ici; les vibrations sont absorbées par un joint élastique 21 et elles ne sont donc pas transmises au panier répartiteur.At its lower end, the
Le joint en matière réfractaire 6 est du type du "break ring" utilisé dans les machines de coulée continue horizontale; il est par exemple réalisé en nitrure de bore.The seal in
La lingotière 5 est suivie d'un système de refroidissement secondaire 7, qui ne fait pas partie de la présente invention et qui peut être un système conventionnel composé de rouleaux de support et de gicleurs.The
Dans le présent dispositif, l'acier est coulé du panier répartiteur 1 dans l'élément tubulaire 4 en matière réfractaire puis dans la lingotière en cuivre refroidie 5. Le ménisque 8 est situé dans l'élément tubulaire 4 en matière réfractaire, et la position de ce ménisque est contrôlée par un dispositif de régulation du débit de type connu; dans la présente invention, il n'est pas nécessaire que le contrôle de cette position soit réalisé de manière très précise.In the present device, the steel is poured from the
La solidification de la surface de l'acier commence à l'entrée de la lingotière, immédiatement après le joint en matière réfractaire 6; elle se poursuit de la manière habituelle dans la lingotière 5 et dans le système de refroidissement secondaire 7, pour former une peau solidifiée 20 d'épaisseur croissante.Solidification of the steel surface begins at the entrance to the mold, immediately after the
Une variation de la position du ménisque 8 pendant la coulée n'a dès lors aucun effet sur l'endroit où commence la solidification de la surface de l'acier et elle n'entraîne donc plus la formation de défauts de surface.A variation in the position of the
Par ailleurs, la section de la lingotière 5 peut être aussi petite qu'on le désire, par exemple pour la coulée continue de brames minces, puisque le dispositif ne comporte plus de busette immergée. De même, l'élément tubulaire 4 peut avoir une section de petites dimensions, proportionnées à celles de la lingotière. Il suffit que le tronçon d'entrée de l'élément tubulaire 4 puisse recevoir le jet de coulée 9 provenant du panier répartiteur 1. A cet égard, cet élément tubulaire 4 est représenté ici avec une section constante sur toute sa longueur; il va de soi que cette section pourrait varier sur la longueur de l'élément tubulaire 4, de préférence avec au moins un tronçon ayant une section plus petite que la lingotière, pour donner à cet élément le profil d'un entonnoir par exemple.Furthermore, the section of the
Dans la pratique conventionnelle, la vitesse de coulée est limitée en particulier par l'instabilité de la position du ménisque 8, qui s'accroît lorsque la vitesse de coulée augmente et qui multiplie ainsi les risques de formation de défauts de surface. Grâce au dispositif de l'invention, ce risque est largement éliminé et la vitesse de coulée peut être sensiblement accrue.In conventional practice, the casting speed is limited in particular by the instability of the position of the
La Fig. 2 illustre une installation particulière de coulée continue qui applique le principe exposé dans la Fig. 1. Cette installation comprend plusieurs dispositifs supplémentaires, connus en soi, qui permettent notamment de couler l'acier avec une faible surchauffe et d'accélérer le refroidissement du produit coulé. Tous ces dispositifs sont placés en série et ils sont alignés suivant l'axe de l'installation de coulée; dans la représentation de la Fig. 2, cet axe est vertical, mais il pourrait tout aussi bien être courbe, comme c'est le cas dans différents types de machines de coulée continue.Fig. 2 illustrates a particular continuous casting installation which applies the principle set out in FIG. 1. This installation comprises several additional devices, known per se, which make it possible in particular to cast the steel with low overheating and to accelerate the cooling of the cast product. All these devices are placed in series and they are aligned along the axis of the casting installation; in the representation of FIG. 2, this axis is vertical, but it could just as easily be curved, as is the case in different types of continuous casting machines.
Sous le panier répartiteur 1 est placé un conduit vertical 10, également appelé busette à jet creux, composé d'un tronçon réfractaire 11 et d'un tronçon métallique refroidi 12. Dans le tronçon réfractaire 11 et sous le trou de coulée 2 est disposé un dôme 13 en matière réfractaire définissant un canal périphérique avec la paroi intérieure du tronçon réfractaire 11. Le dôme 13 est équipé d'une canne 14 d'injection de gaz à l'intérieur du tronçon métallique 12. Le tronçon réfractaire 11 est généralement cylindrique, tandis que le tronçon métallique 12 est avantageusement convergent, pour tenir compte d'une certaine contraction due à un début de refroidissement et de solidification, comme on le rappellera plus loin.Under the
Le conduit vertical 10 débouche par son extrémité inférieure dans l'élément tubulaire 4 en matière réfractaire qui a été défini plus haut. Le joint élastique 21 est placé entre le conduit vertical 10 et l'élément tubulaire 4. Cet élément tubulaire 4 est muni d'inducteurs 15, destinés à agiter l'acier présent dans l'élément tubulaire 4.The
Par le joint en matière réfractaire 6, l'élément tubulaire 4 se raccorde à la lingotière 5 en cuivre, refroidie à l'eau.By the seal made of
La lingotière est ici équipée d'un système de lubrification forcée, symbolisé par les flèches 16 qui indiquent les canaux d'introduction du lubrifiant. Celui-ci est introduit dans la zone du début de la solidification de l'acier.The ingot mold is here equipped with a forced lubrication system, symbolized by the
On a également représenté un dispositif 17 pour appliquer à la lingotière des vibrations de faible amplitude. Ces vibrations sont absorbées par le joint élastique 21.There is also shown a device 17 for applying vibrations of low amplitude to the mold. These vibrations are absorbed by the
Enfin, sous la lingotière 5 est installé un dispositif de refroidissement secondaire 7, comprenant un système 18 de refroidissement intense au moyen d'une couche d'eau sous pression, et un système 19 de refroidissement modéré dans l'eau plus calme du produit coulé. Le volume occupé par l'eau est représenté en pointillé.Finally, under the
Cette installation fonctionne de la manière suivante:This installation works as follows:
L'acier coulé du panier répartiteur 1 par le trou de coulée tombe sur le dôme réfractaire 13, qui le dévie vers la paroi intérieure du tronçon réfractaire 11 du conduit 10. Par le canal périphérique l'acier s'écoule ensuite en un film mince le long de la paroi intérieure du tronçon 12. Ce film est maintenu le long de la paroi par le gaz sous pression insufflé par la canne 14.The steel poured from the
Si l'acier présente initialement une surchauffe faible, par exemple de l'ordre de 20°C, il peut subir dans le tronçon métallique 12 un début de refroidissement, qui le rend légèrement pâteux.If the steel initially exhibits a slight overheating, for example of the order of 20 ° C., it can undergo in the metal section 12 a start of cooling, which makes it slightly pasty.
Cet acier parvient ensuite dans l'élément tubulaire 4 en matière réfractaire, où il ne subit pas de refroidissement sensible. Les inducteurs 15 lui impriment un mouvement de rotation qui réalise un brassage intense de l'acier, le rend très homogène et lui assure une viscosité suffisamment basse.This steel then reaches the
L'acier pénètre enfin dans la lingotière 5 où, dès le contact avec le joint 6, il commence sa solidification de manière conventionnelle, avec une peau solidifiée 20 d'épaisseur croissante. La solidification se poursuit dans le dispositif de refroidissement secondaire 7: le système 18 assure un refroidissement intense de la peau du produit, et le système 19 de refroidissement modéré empêche un réchauffement trop rapide de la peau après le refroidissement intense. Ce refroidissement secondaire en deux étapes permet de diminuer fortement la formation de criques internes dans le produit coulé.The steel finally enters the
De plus, l'acier légèrement pâteux se solidifie avec une structure homogène, présentant une ségrégation axiale quasi nulle.In addition, the slightly pasty steel solidifies with a homogeneous structure, exhibiting almost zero axial segregation.
Le procédé de l'invention et son dispositif de mise en oeuvre permettent donc de couler plus rapidement des produits en acier qui présentent un excellent état de surface et une très bonne santé interne.The method of the invention and its implementation device therefore make it possible to flow steel products more quickly which have an excellent surface condition and very good internal health.
Claims (9)
- Process for the continuous casting of a molten metal, in which the molten metal is cast in a mould (5) where it solidifies, characterized in that the upper level, or meniscus, (8) of the said molten metal is established in a region located upstream of the point where solidification of the said metal in the mould (5) starts.
- Device for the continuous casting of a molten metal according to the process of Claim 1, which comprises a casting vessel (1) provided with a tap hole (2) and a bottomless mould (5) placed under the said tap hole (2), characterized in that it includes a tubular element (4) made of refractory material arranged between the said casting vessel (1) and the mould (5), in alignment with the latter, in that the said tubular element (4) made of refractory material is rigidly fixed, by its lower end, to the upper part of the mould (5) and in that the said tubular element (4) made of refractory material is connected by its upper end to the said casting vessel (1).
- Device according to Claim 2, characterized in that an elastic seal (21) is interposed between the casting vessel (1) and the tubular element (4) made of refractory material.
- Device according to either of Claims 2 and 3, characterized in that a seal made of refractory material (6) is interposed between the said tubular element (4) made of refractory material and the mould (5).
- Device according to any one of Claims 2 to 4, characterized in that the said tubular element (4) is equipped with means for stirring the metal which it contains.
- Device according to any one of Claims 2 to 5, characterized in that the said tubular element (4) has, in at least one section of its length, a smaller cross-section than that of the mould (5).
- Device according to any one of Claims 2 to 6, characterized in that the whole assembly comprising the casting vessel (1), the tubular element (4) and the mould (5) forms a conduit closed to the atmosphere.
- Device according to any one of Claims 2 to 7, characterized in that it includes a hollow jet nozzle (10) with a refractory dome (13) arranged between the casting vessel (1) and the tubular element (4) made of refractory material.
- Device according to any one of Claims 2 to 8, characterized in that it includes a secondary cooling device (7) comprising an intense cooling system (18) and a moderate cooling system (19), placed immediately after the mould (5).
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
BE9100734 | 1991-08-12 | ||
BE9100734A BE1005165A3 (en) | 1991-08-12 | 1991-08-12 | Method and device for the continuous casting of metal fusion. |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0527717A1 EP0527717A1 (en) | 1993-02-17 |
EP0527717B1 true EP0527717B1 (en) | 1997-02-19 |
Family
ID=3885646
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP92870117A Revoked EP0527717B1 (en) | 1991-08-12 | 1992-08-06 | Method and device for continuous casting a molten metal |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0527717B1 (en) |
AT (1) | ATE149005T1 (en) |
BE (1) | BE1005165A3 (en) |
DE (1) | DE69217521T2 (en) |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE519819A (en) * | 1953-05-08 | 1955-05-13 | ||
JPS619949A (en) * | 1984-06-25 | 1986-01-17 | Nippon Steel Corp | Continuous casting method while preventing oxidation in initial period of casting |
EP0269180B1 (en) * | 1986-11-26 | 1992-01-02 | CENTRE DE RECHERCHES METALLURGIQUES CENTRUM VOOR RESEARCH IN DE METALLURGIE Association sans but lucratif | Device for casting pasty metals |
-
1991
- 1991-08-12 BE BE9100734A patent/BE1005165A3/en not_active IP Right Cessation
-
1992
- 1992-08-06 DE DE69217521T patent/DE69217521T2/en not_active Revoked
- 1992-08-06 AT AT92870117T patent/ATE149005T1/en active IP Right Revival
- 1992-08-06 EP EP92870117A patent/EP0527717B1/en not_active Revoked
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 13, no. 310 (M-850)(3658) 14 Juillet 1992 & JP-A-62 129 848 (KOBE STEEL) 18 Avril 1989 * |
Also Published As
Publication number | Publication date |
---|---|
DE69217521D1 (en) | 1997-03-27 |
ATE149005T1 (en) | 1997-03-15 |
EP0527717A1 (en) | 1993-02-17 |
DE69217521T2 (en) | 1997-09-11 |
BE1005165A3 (en) | 1993-05-11 |
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