EP1551580A1 - Method and device for controlling flows in a continuous slab casting ingot mould - Google Patents

Method and device for controlling flows in a continuous slab casting ingot mould

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Publication number
EP1551580A1
EP1551580A1 EP03776964A EP03776964A EP1551580A1 EP 1551580 A1 EP1551580 A1 EP 1551580A1 EP 03776964 A EP03776964 A EP 03776964A EP 03776964 A EP03776964 A EP 03776964A EP 1551580 A1 EP1551580 A1 EP 1551580A1
Authority
EP
European Patent Office
Prior art keywords
mold
nozzle
sliding
inductors
configuration
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP03776964A
Other languages
German (de)
French (fr)
Other versions
EP1551580B1 (en
Inventor
Siebo Kunstreich
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rotelec SA
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Rotelec SA
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Filing date
Publication date
Application filed by Rotelec SA filed Critical Rotelec SA
Publication of EP1551580A1 publication Critical patent/EP1551580A1/en
Application granted granted Critical
Publication of EP1551580B1 publication Critical patent/EP1551580B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • B22D11/11—Treating the molten metal
    • B22D11/114—Treating the molten metal by using agitating or vibrating means
    • B22D11/115—Treating the molten metal by using agitating or vibrating means by using magnetic fields
    • 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
    • B22D11/16—Controlling or regulating processes or operations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/02—Use of electric or magnetic effects
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/50—Pouring-nozzles
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper

Definitions

  • the invention relates to the continuous casting of metals, in particular steel, in the form of slabs, or any other similar elongated flat product.
  • FIGS. 1A and 1B Attached at the end of this memo. These figures show the stabilized shape of the trajectories of the main currents in a vertical plane passing through the casting axis and parallel to the two large faces of an ingot mold for continuous casting of slabs.
  • the "single loop" mode (fig. 1A) essentially translates, as can be seen, by the fact that the metal jets 1 direct as soon as they exit from the gills 2 of the nozzle 3 rather upwards in the direction of the free surface (or meniscus) 4 of the metal cast in the mold.
  • each jet 1 is then generally reflected downwards in the direction of the extraction of the cast product represented by the thick vertical arrow in the middle of the figure.
  • the precise mapping of speeds is much more complex.
  • the real mapping is much more complex, but it is this global image in "butterfly wings" which marks the observer facing the screen of a modeller or in front of a model operating in "double loop” mode.
  • the operator of the continuous casting machine generally does not have the means to know the stable flow mode of the metal within its ingot mold. Moreover, most often, it must be recognized that he does not care, since in any case, he could not and could not intervene on the cast format or on the extraction speed, which are imposed by the order book and material flow within the factory.
  • the object of the present invention is to offer the operator of the continuous slab casting a simple and efficient tool, added to his machine without having to reconsider its design, to enable it to be assuredly in "double loop” mode without modifying the setting of the casting parameters in any way.
  • the invention relates to a process for controlling the configuration of the flows of the metal cast in a mold for continuous casting of metal slabs or other similar flat product, in particular steel, using a submerged nozzle provided with side outlet openings facing the small faces of the mold, said configuration being able to be in “single loop” or “double loop” or “unstable” mode, a process characterized in that the works of sliding magnetic fields acting, in an ingot mold at the height of the nozzle, on the flows of liquid metal arriving in the ingot mold by the gills of the nozzle, said fields being produced by polyphase linear electromagnetic inductors arranged opposite at least one face of the ingot mold on either side of the nozzle so as to install or stabilize a configuration in "double loop” mode.
  • magnetic fields sliding horizontally outward are used, in the direction going from the nozzle towards each small face, by means of inductors arranged facing at least one large face of the ingot mold on either side of the nozzle.
  • the sliding magnetic fields are made to act during the entire casting operation.
  • the sliding magnetic fields are made to act only if the configuration of the movements is not naturally already in "double loop” mode. Additionally, if the configuration is already naturally in mode
  • double loop horizontally sliding magnetic fields are made to act by means of inductors arranged opposite at least one large face of the ingot mold on either side of the nozzle in accordance with the preferred embodiment variant explained below. before, but the said inductors are adjusted so that the fields produced by each of them all slide in the same direction so as to impart to the liquid metal in the ingot mold an overall movement of rotation around the casting axis.
  • the invention also relates to an installation for implementing the method according to said preferred embodiment comprising at least one pair of linear electromagnetic inductors with sliding magnetic field, mounted facing at least one large face of the mold. and oriented to produce a field magnetic sliding horizontally, and a polyphase controlled electrical power supply connected to the inductors to make them each produce a magnetic field sliding in a direction going from the nozzle towards a small face of the mold.
  • the invention makes use of a well-known and, if one may say, commercially available means, the mobile magnetic field produced by a linear polyphase static inductor , to act dynamically on the liquid metal within the ingot mold in order to establish a "double loop" flow mode, or to stabilize it if it is already naturally present.
  • JMHD magnetohydrodynamics
  • the aim was thus to promote a solidification structure of the equiaxial type from the mold, as well as the improvement of subcutaneous cleanliness by washing the solidification front with the ascending currents of liquid metal taking with them the gas bubbles formed in situ and non-metallic inclusions up to the meniscus where they are fixed by the covering slag which floats.
  • the European Patent Application published under No. 0.151.648 describes the possible choices between vertical mixing of the metal in the mold at using vertically sliding magnetic fields from bottom to top to improve the surface cleanliness of the cast product, and horizontal stirring using horizontally movable fields to then improve subcutaneous inclusion cleanliness by a forehead washing effect solidification.
  • KSC European Patent Application published under No. 0.151.648
  • fields sliding horizontally inwards, in opposite directions from the jets coming from the nozzle, therefore from the small faces towards the nozzle would be favorable for obtaining an inclusive cleanliness situated deep under the skin. solidified.
  • this operating mode of magnetic fields sliding horizontally outward and acting in height at the gills of the nozzle on the incoming metal jets is like a preferred variant of what the invention proposes to do systematically during the entire casting, but, in this case, to impose a stable mode of circulation in "double loop" convection movements of the molten metal within the ingot mold.
  • FIG. 2 is a statistical graph established from a compilation of real data and making it possible to determine as a function of the casting parameters that are the casting speed on the abscissa and the width of the slab casting on the ordinate, the operating domains naturally stable in "single loop” -domain S- and in "double loop” -domain D-.
  • Triangles are “single loop” type events; the diamonds are “double loop” type events.
  • the data corresponding to naturally unstable events, randomly switching from an S to D mode or from D to S have not been carried.
  • FIG. 3 is a general schematic view of what an ingot mold for continuous casting of slabs equipped with the means of the invention
  • - Figure 4 is a view similar to that of Figure 3 but showing a little more detail the technology of linear inductors sliding field usable
  • - Figure 5 is a block diagram, showing seen from above the ingot mold the mode of action of the sliding field inductors implemented according to the invention
  • FIG. 6 shows, coming from a computer simulation by calculation model, three pairs of diagrams A, B, C, arranged one above the other, and each representing the characteristics of the convection movements within a slab ingot mold with different values of the intensity of the sliding magnetic fields applied in accordance with the invention.
  • the same elements are designated with identical reference numbers.
  • FIGS. 1A and 1B have already served to illustrate the definitions given in the introductory part of this memo of what is to be understood under the terms of "single loop” and “double loop” in the context of the invention.
  • the domains S and D corresponding respectively to the two types of stable natural recirculation “Single loop and” Double loop ", are separated by a double P line in broken lines slightly oblique with respect to This dividing line P makes it easy to see that the natural "double loop” recirculation mode, domain D, is rather reserved for high casting speeds, say greater than 1.4 m / min, and whatever the width of the casting strip, while below about 1.2 m / min, we are almost always in the S domain of the "single loop".
  • the dotted line of general hyperbolic appearance R represents a reference flow with a constant metal flow rate of 4.6 tonnes / min, (product between the casting section and the casting speed if it is assumed that the level in meniscus height hardly fluctuates around a fixed value during casting).
  • the separation line P translates to the left, widening the area of the "double loop" when the immersion depth of the nozzle increases or, if an argon bubbling is used to avoid the risks of clogging of the nozzle (flows of low or very low carbon grades calmed with aluminum for example), when the flow of argon decreases.
  • the implementation of the invention consists in fact in making the line P disappear by translating it to the left until it is ousted from the diagram.
  • an ingot mold 18 can be seen for the casting of steel slabs 9 consisting essentially of two pairs of plates of copper, or of copper alloy, vigorously cooled by circulation of cooling water: a pair of large plates facing each other at a distance defining the thickness of the slab: these are the large faces; and a pair of small plates, mounted in a leaktight manner at the end of the large plates in order to ensure the continuity of the internal periphery of the mold which defines the casting space.
  • These lateral closing plates of the pouring space are the small faces.
  • the ingot mold is supplied with fresh metal by a submerged nozzle 3 centered on the casting axis A and the upper end of which is tightly connected to the opening made in the bottom of a distributor not shown.
  • a submerged nozzle 3 centered on the casting axis A and the upper end of which is tightly connected to the opening made in the bottom of a distributor not shown.
  • the free lower end of the nozzle is provided with lateral outlet holes, diametrically opposed, and plunges into the mold at an adjusted depth (about forty centimeters below the upper edge copper plates), with an angular orientation adjusted so that each hole is turned opposite a small face 5 of the mold.
  • the means for implementing the invention are clearly visible in the working position in FIG. 3. They consist of an electromagnetic unit 10 connected to a polyphase electrical supply 11, preferably three-phase.
  • the power supply 11 has thyristors in order to be able to vary the frequency of the current by acting on the thumb wheel 12 on the front panel.
  • Another knob 13 allows him to adjust the intensity of the current.
  • the electromagnetic unit is formed by four linear inductors, preferably identical, of the flat stator type of an asynchronous motor.
  • linear inductors are grouped in pairs, a pair of inductors 14.14 '(and 15.15') per large face of the ingot mold.
  • the two inductors of the same pair, for example the pair 14, 14 ′, are mounted on the same large face, but on either side of the nozzle 3 in a preferably symmetrical relative position.
  • These two inductors 14, 14 ′ can be independent of each other mechanically and electrically.
  • each inductor is of the "salient magnetic pole” type therefore wound, or of the "distributed pole” type, are themselves polyphase and compatible in this respect with power supply 11 so that each can be connected to the terminals of this power supply in an adequate sequential phase order ensuring the sliding of the field in the desired "outward" direction.
  • the field itself, generated by this inductor is generally perpendicular to the plane of this face.
  • it is the component perpendicular to this face which is the only active in the production of useful energy in the form of a metal driving force in the direction of the sliding of the field. It is therefore advantageous, in order to maximize the energy efficiency of the operation, to have inductors whose lines of force of the fields produced are orthogonal to the plane of the faces and which they thus propagate as far as possible inside. metal to be poured.
  • a second pair of inductors is added, such as 15.15 'facing each other on the other large face of the ingot mold.
  • the power supply 11 then supplies these inductors added in phase opposition with respect to the inductors 14, 14 'facing taken in this order, so that the fields produced by two inductors facing each other on the two faces opposite of the ingot mold, in this case 14 and 15, or 14 'and 15', are in the same direction and therefore add up, at any point in the space of the gap thus formed, to constitute a magnetic field passing through the product poured right through, and the advantage of which is known with respect to a longitudinal field since the intensity at the center of the product is hardly lower than in the vicinity of the inductors.
  • FIG. 4 makes it possible to offer a slightly more detailed view of a technological embodiment of the inductors. They are mounted, as can be seen, in the upper cooling water chamber 16 of the mold (drawn in thin lines) in order to benefit from the cooling effect, but also to be able to bring the polar active faces 17 closer together. cast metal.
  • each inductor • carries visible ribs 19, 19 ', 20, intended to ensure the fastenings and alignments necessary between them and to adjust their height position by taking in corresponding support grooves in the supporting frame of the casting machine (not shown).
  • FIG. 6 which we now refer clearly illustrates the benefit derived from this control.
  • Each diagram A, B, or C presents, in its window on the left, the trajectories of the convection current lines of the metal chosen arbitrarily in the right half-space of casting of an ingot mold with slabs, contained on the abscissa L between the casting axis A and the small end face 5, and developing over the height h of the mold from the meniscus 4 (ordinate 0) to a depth of 70 cm.
  • the associated graph on the right gives the corresponding values of the speed "s" of the metal on the ordinate at the meniscus 4 on the median measurement line which connects the outlet port 2 of the nozzle to the small opposite end face 5 placed on the abscissa.
  • This speed is counted algebraically, with a positive sign when the direction of the currents goes from the nozzle to the small face and therefore negatively in the opposite direction.
  • each couple is representative of a different value of the intensity of the magnetic field acting.
  • Torque B is associated with an average magnetic field intensity value, corresponding to an excitation current of inductive windings with effective intensity i of 250 A.
  • Couple C illustrates the situation when the applied magnetic field is produced at an intensity of current i of 450 A.
  • diagram B shows that nothing happens significantly different from the previous situation. Note, however, on the velocity diagram a slight decrease in the positive speed peak (region of the meniscus to the right of the point of inversion M), therefore a slight displacement of this point M towards the small face 5, which expresses in made a start in favor of establishing the desired "double loop” circulation mode.
  • This "double loop" mode is in fact fully obtained with an intensity of the excitation current of the inductors of 450 A eff., As shown in diagram C. In fact, the reversal point has this time completely disappeared to make room for a profile of negative values along the meniscus.
  • the very principle of the operation of polyphase plane inductors with sliding field is that of the asynchronous motor: it is the speed differential between the sliding magnetic field and the current of liquid metal, on which it acts to entrain it in its displacement, which precisely determines the driving force of the metal.
  • the implementation of the invention will have the advantage of stabilizing it, regularizing it, even moderating it if necessary . It is indeed enough for that to intervene on the adjustment of the excitation current frequency.
  • the sliding speed of the mobile magnetic field that it generates is indeed, as we know, proportional to the frequency of the field's pulsation, therefore of the electric current which produces it by traversing the inductor windings. Consequently, the invention will allow the need to automatically calm an overly vigorous meniscus recirculation loop, by choosing a frequency of the excitation current such that the speed of movement of the fields is lower than that of the metal current at the meniscus.
  • the intensity of the magnetic field is regulated by the choice of the intensity of the exciting current; its sliding speed is adjusted via the frequency of this current; and the direction of the sliding of the field is adjusted by an ad hoc connection of the windings of the inductor to the phases of the electrical supply.
  • Figure 2 constitutes in this respect a precious graphic aid which will easily allow the operator to know straight away if it is naturally located, or if it is likely to be already located, in a single or double configuration. loop.

Abstract

The control of the configuration of movement of liquid metal cast in a continuous casting mould uses an immersed nozzle provided with lateral outlet holes turned towards the smaller faces of the mould. The configuration may be naturally in single loop, double loop or unstable mode. Some sliding magnetic fields act on the flow of liquid metal arriving in the mould (18) via the holes of the immersed nozzle (3). The magnetic fields are produced by linear electromagnetic induction coils (14, 14', 15, 15') arranged opposite at least one face of the mould and the nozzle in a manner to induce, or stabilize a permanent configuration in double loop mode. An Independent claim is also included for the equipment putting this method of controlling the configuration of liquid metal movement into service.

Description

PROCEDE ET DISPOSITIF POUR LA MAÎTRISE DES ECOULEMENTS DANS UNE LINGOTIERE DEMETHOD AND DEVICE FOR CONTROLLING FLOWS IN A LINGOTIERE OF
COULEE CONTINUE DE BRAMESCONTINUOUS FLOW OF BRAMES
L'invention a trait à la coulée continue des métaux, de l'acier en particulier, sous forme de brames, ou de tout autre produit plat allongé analogue.The invention relates to the continuous casting of metals, in particular steel, in the form of slabs, or any other similar elongated flat product.
Elle concerne plus précisément l'amélioration de la qualité des produits coulés par une maîtrise de la configuration des mouvements de convection du métal coulé au sein de la lingotière. II est définitivement admis de nos jours, sans toutefois être déjà capable de décrire le lien de causalité, que la manière dont s'organisent les mouvements de convection du métal en fusion en lingotière est un facteur déterminant sur la qualité des produits obtenus, tant pour ce qui concerne la foπnation d'une première peau de solidification bien homogène et régulière sur le pourtour de la lingotière, qu'à l'égard de la propreté superficielle et sous cutanée (incrustations de laitier, piqûres, boursouflures, ou niveau de propreté inclusionnaire interne).More precisely, it relates to improving the quality of the cast products by controlling the configuration of the convection movements of the metal cast within the ingot mold. It is definitely accepted nowadays, without however already being able to describe the causal link, that the way in which the convection movements of molten metal in the mold are organized is a determining factor on the quality of the products obtained, both for as regards the formation of a first homogeneous and regular solidification skin around the periphery of the ingot mold, only with regard to surface and subcutaneous cleanliness (slag encrustations, stings, blisters, or level of inclusiveness cleanliness internal).
On sait de même l'importance que prend à cet égard le développement, dès leur entrée dans l'espace de coulée, des flux de métal liquide arrivant en lingotière par les ouïes de sortie latérales de la busette immergée qui alimente le système en métal à couler. On citera à cet égard, parmi d'autres, l'article de P.H. Dauby, M.B. Assar etWe also know the importance that takes in this respect the development, as soon as they enter the casting space, the flows of liquid metal arriving in the mold through the lateral outlet openings of the submerged nozzle which feeds the metal system to flow. In this regard, we may cite, among others, the article by P.H. Dauby, M.B. Assar and
G.D. Lawson "voyage dans une lingotière de coulée continue. Mesures laser et électromagnétiques de l'hydrodynamique de l'acier" paru dans la Revue de Métallurgie, avril 2001; Vol. A, p. 353-356, et la publication faite par D. Gotthelf, P. Andrzejewski, E. Julius et H. Haubrich "Moldflow monitoring-a tool to improve caster opération" à la 3eme Conférence Européenne sur la Coulée Continue à Madrid (Esp.) en 1998, p. 825-833.GD Lawson "travels in a continuous casting mold. Laser and electromagnetic measurements of the hydrodynamics of steel" published in the Revue de Métallurgie, April 2001; Flight. A, p. 353-356, and the publication made by D. Gotthelf, P. Andrzejewski, E. Julius and H. Haubrich "Moldflow monitoring-a tool to improve caster operation" at the 3 rd European Conference on Continuous Casting in Madrid (Esp. ) in 1998, p. 825-833.
Comme le soulignent avec justesse ces documents, il y a globalement trois types d'écoulement d'acier liquide au niveau de la lingotière: la configuration "simple boucle" et la configuration "double boucle" qui sont des modes stables, et un écoulement de type aléatoire, instable, propre aux régimes transitoires dans l'opération de coulée. Ce dernier peut se décrire schématiquement comme une alternance erratique de modes "simple boucle" et "double boucle" provenant de dissymétries momentanées et incontrôlables des écoulements entre les deux demi-espaces de coulée de part et d'autre de la busette dues notamment à des perturbations, même minimes en énergie, au niveau des ouïes de sorties de la busette, comme par exemple des variations différentielles dans le débit d'argon anti-bouchage entre les deux ouïes.As these documents rightly point out, there are generally three types of liquid steel flow at the level of the ingot mold: the "single loop" configuration and the "double loop" configuration which are stable modes, and a flow of random, unstable type, specific to transient regimes in the casting operation. The latter can be described schematically as an erratic alternation of "single loop" and "double loop" modes originating from momentary and uncontrollable asymmetries of the flows between the two half-spaces of casting on either side of the nozzle due in particular to disturbances, even minimal in energy, at the nozzle outlets, such as for example differential variations in the flow of anti-clogging argon between the two outlets.
Par contre, les deux modes d'écoulement stables précités sont eux plus explicites. Ils sont illustrés sur les figures 1A et 1B jointes à la fin de ce mémoire. Ces figures montrent l'allure stabilisée des trajectoires des courants principaux dans un plan vertical passant par l'axe de coulée et parallèle aux deux grandes faces d'une lingotière de coulée continue de brames. Le mode "simple boucle" (fig. 1A) se traduit essentiellement, comme on le voit, par le fait que les jets de métal 1 se dirigent dès leur sortie des ouïes 2 de la busette 3 plutôt vers le haut en direction de la surface libre (ou ménisque) 4 du métal coulé en lingotière. A ce niveau, ils parcourent la largeur du demi-espace de coulée dans lequel chacun se développe en longeant les grandes faces de la lingotière jusqu'à atteindre les petites faces d'extrémité 5. On rappelle au besoin que ces petites faces, dites également "faces de fermeture" sont montées au droit à l'extrémité des grandes faces afin d'assurer la continuité de la périphérie intérieure de la lingotière et donc l'étanchéité de l'espace de coulée. Parvenus à la petite face, chaque jet 1 est alors globalement réfléchi vers le bas dans le sens de l'extraction du produit coulé représenté par la flèche verticale épaisse au milieu de la figure. Bien entendu, la cartographie précise des vitesses est bien plus complexe. Beaucoup des lignes de courant, telles que 6, empruntent des trajectoires plus typiquement paraboliques en raison du mouvement d'ensemble d'extraction vers le bas, mais schématiquement c'est bien cette forme générale en source jaillissante vers le haut qui frappe le regard quand on observe le mode "simple boucle" dans un simulateur ou sur maquette.On the other hand, the two aforementioned stable flow modes are themselves more explicit. They are illustrated in FIGS. 1A and 1B attached at the end of this memo. These figures show the stabilized shape of the trajectories of the main currents in a vertical plane passing through the casting axis and parallel to the two large faces of an ingot mold for continuous casting of slabs. The "single loop" mode (fig. 1A) essentially translates, as can be seen, by the fact that the metal jets 1 direct as soon as they exit from the gills 2 of the nozzle 3 rather upwards in the direction of the free surface (or meniscus) 4 of the metal cast in the mold. At this level, they cover the width of the half-casting space in which each one develops by following the large faces of the ingot mold until reaching the small end faces 5. It is recalled if necessary that these small faces, also called "closure faces" are mounted at the right end of the large faces to ensure the continuity of the inner periphery of the mold and therefore the sealing of the casting space. Arrived at the small face, each jet 1 is then generally reflected downwards in the direction of the extraction of the cast product represented by the thick vertical arrow in the middle of the figure. Of course, the precise mapping of speeds is much more complex. Many streamlines, such as 6, follow more typically parabolic paths due to the downward movement of the overall extraction, but schematically it is this general shape as a source gushing upward that strikes the eye when we observe the "single loop" mode in a simulator or on a model.
En revanche, selon le mode "double boucle" (fig. 1B), chaque jet 1, arrivant en lingotière par la busette 3, sort des ouïes 2 à l'horizontale dans son ensemble et se propage ainsi vers les petites faces 5 où tout se passe comme si l'impact partageait le jet en deux courants, un courant principal 8 réfléchi vers le bas et un courant secondaire 7 réfléchi vers le haut en direction du ménisque A, et à ce niveau va parcourir alors le demi- espace de coulée dans le sens contraire cette fois, de la petite face 5 vers la busette 3. Là- aussi, la cartographie réelle est bien plus complexe, mais c'est bien cette image globale en "ailes de papillon" qui marque l' observateur face à l'écran d'un modélisateur ou devant une maquette fonctionnant en mode "double boucle". Le progrès des connaissances et le cumul de l'expérience permettent aujourd'hui de savoir assez bien quand et comment, en fonction des paramètres de coulée pertinents, s'établissent de manière stable ou quasi-stable l'un ou l'autre des deux modes d'écoulement prémentionnés. Sans entrer dans les détails, ce qui serait d'ailleurs inutile et surabondant pour la compréhension de l'invention, on peut dire simplement que plus on coule des brames de grande largeur, de même, plus on coule à vitesse d'extraction faible, plus on se situe dans le domaine de la configuration "simple boucle", et inversement pour ce qui concerne la configuration "double boucle".On the other hand, according to the "double loop" mode (fig. 1B), each jet 1, arriving in the mold by the nozzle 3, leaves the gills 2 horizontally as a whole and thus propagates towards the small faces 5 where everything happens as if the impact split the jet into two streams, a main current 8 reflected downwards and a secondary current 7 reflected upwards towards the meniscus A, and at this level will then travel through the half-casting space in the opposite direction this time, from the small side 5 towards the nozzle 3. Again, the real mapping is much more complex, but it is this global image in "butterfly wings" which marks the observer facing the screen of a modeller or in front of a model operating in "double loop" mode. The progress of knowledge and the accumulation of experience make it possible today to know fairly well when and how, depending on the relevant casting parameters, are established in a stable or quasi-stable way one or the other of the two flow modes mentioned above. Without going into details, which would be useless and superabundant for the understanding of the invention, we can simply say that the more we pour slabs of great width, similarly, the more we sink at low extraction speed, the more we are in the "single loop" configuration, and vice versa for the "double loop" configuration.
Il faut dire que l'exploitant de la machine de coulée continue n'a en général pas à disposition les moyens de connaître le mode d'écoulement stable du métal au sein de sa lingotière. D'ailleurs, le plus souvent, il faut reconnaître qu'il ne s'en soucie guère, puisque de toute façon, il ne saurait ni ne pourrait intervenir sur le format coulé ou sur la vitesse d'extraction, lesquels sont imposés par le carnet de commande et le flux de matière au sein de l'usine.It must be said that the operator of the continuous casting machine generally does not have the means to know the stable flow mode of the metal within its ingot mold. Moreover, most often, it must be recognized that he does not care, since in any case, he could not and could not intervene on the cast format or on the extraction speed, which are imposed by the order book and material flow within the factory.
Il se trouve pourtant que les récents travaux du demandeur ont confirmé, sinon démontré l'existence de liens de causalité explicites entre les défauts des produits issus de la coulée d'un côté (versus la disparition de ces défauts) et de l'autre la configuration des mouvements de convection du métal liquide en lingotière. Ainsi, il se trouve que non seulement les écoulements de type instable seraient à l'origine des défauts de qualité observés, ce dont on pouvait se douter, mais également la configuration stable en mode "simple boucle".It turns out, however, that the applicant's recent work has confirmed, if not demonstrated, the existence of explicit causal links between product defects from casting on one side (versus the disappearance of these defects) and on the other the configuration of convection movements of liquid metal in the mold. Thus, it turns out that not only the unstable type flows would be at the origin of the observed quality defects, which one might suspect, but also the stable configuration in "single loop" mode.
Aussi, la présente invention a-t'elle pour but d'offrir à l'exploitant de la coulée continue de brames un outil simple et performant, rajouté à sa machine sans avoir à reconsidérer sa conception, pour lui permettre d'être assurément en mode "double boucle" sans modifier en rien le réglage des paramètres de la coulée. Avec cet objectif en vue, l'invention a pour objet un procédé pour la maîtrise de la configuration des écoulement du métal coulé dans une lingotière de coulée continue de brames métalliques ou autre produit plat analogue, notamment en acier, à l'aide d'une busette immergée dotée d'ouies de sorties latérales tournées en regard des petites faces de la lingotière, ladite configuration pouvant être en mode "simple boucle" ou "double boucle" ou "instable", procédé caractérisé en ce que l'on met en œuvre des champs magnétiques glissants agissant, en lingotière à la hauteur de la busette, sur les flux de métal liquide arrivant en lingotière par les ouies de la busette, lesdits champs étant produits par des inducteurs électromagnétiques linéaires polyphasés disposés en regard d'au moins une face de la lingotière de part et d'autre de la busette de manière à installer ou stabiliser une configuration en mode "double boucle".Also, the object of the present invention is to offer the operator of the continuous slab casting a simple and efficient tool, added to his machine without having to reconsider its design, to enable it to be assuredly in "double loop" mode without modifying the setting of the casting parameters in any way. With this objective in view, the invention relates to a process for controlling the configuration of the flows of the metal cast in a mold for continuous casting of metal slabs or other similar flat product, in particular steel, using a submerged nozzle provided with side outlet openings facing the small faces of the mold, said configuration being able to be in “single loop” or “double loop” or “unstable” mode, a process characterized in that the works of sliding magnetic fields acting, in an ingot mold at the height of the nozzle, on the flows of liquid metal arriving in the ingot mold by the gills of the nozzle, said fields being produced by polyphase linear electromagnetic inductors arranged opposite at least one face of the ingot mold on either side of the nozzle so as to install or stabilize a configuration in "double loop" mode.
Confoπnément à une variante préférée de réalisation, on met en œuvre des champs magnétiques glissants horizontalement vers l'extérieur, dans le sens allant de la busette vers chaque petite face, au moyen d'inducteurs disposés en regard d'au moins une grande face de la lingotière de part et d'autre de la busette. Selon une mise en œuvre, on fait agir les champs magnétiques glissants pendant toute l'opération de coulée.In accordance with a preferred variant embodiment, magnetic fields sliding horizontally outward are used, in the direction going from the nozzle towards each small face, by means of inductors arranged facing at least one large face of the ingot mold on either side of the nozzle. According to one implementation, the sliding magnetic fields are made to act during the entire casting operation.
Selon une autre mise en œuvre, on fait agir les champs magnétiques glissants uniquement si la configuration des mouvements n'est pas naturellement déjà en mode "double boucle". Complémentairement, si la configuration est déjà naturellement en modeAccording to another implementation, the sliding magnetic fields are made to act only if the configuration of the movements is not naturally already in "double loop" mode. Additionally, if the configuration is already naturally in mode
"double boucle", on fait agir des champs magnétiques glissants horizontalement au moyen d'inducteurs disposés en regard d'au moins une grande face de la lingotière de part et d'autre de la busette conformément à la variante de réalisation préférée explicitée ci-avant, mais on règle lesdits inducteurs afin que les champs produits par chacun d'eux glissent tous dans le même sens de manière à imprimer au métal liquide dans la lingotière un mouvement d'ensemble de rotation autour de l'axe de coulée."double loop", horizontally sliding magnetic fields are made to act by means of inductors arranged opposite at least one large face of the ingot mold on either side of the nozzle in accordance with the preferred embodiment variant explained below. before, but the said inductors are adjusted so that the fields produced by each of them all slide in the same direction so as to impart to the liquid metal in the ingot mold an overall movement of rotation around the casting axis.
L'invention a également pour objet une installation pour la mise en œuvre du procédé selon ladite variante de réalisation préférée comprenant au moins une paire d'inducteurs électromagnétiques linéaires à champ magnétique glissant, montés en regard d'au moins une grande face de la lingotière et orientés de manière à produire un champ magnétique glissant horizontalement, et une alimentation électrique polyphasée commandée connectée audits inducteurs pour leur faire produire chacun un champ magnétique glissant dans un sens allant de la busette vers une petite face de la lingotière. Comme on l'aura sans doute déjà compris, l'invention fait un usage d'un moyen bien connu et, si l'on peut dire, disponible de longue date dans le commerce, le champ magnétique mobile produit par un inducteur linéaire statique polyphasé, pour agir dynamiquement sur le métal liquide au sein de la lingotière afin d'instaurer un mode d'écoulement en "double boucle", ou de le stabiliser s'il est déjà naturellement présent.The invention also relates to an installation for implementing the method according to said preferred embodiment comprising at least one pair of linear electromagnetic inductors with sliding magnetic field, mounted facing at least one large face of the mold. and oriented to produce a field magnetic sliding horizontally, and a polyphase controlled electrical power supply connected to the inductors to make them each produce a magnetic field sliding in a direction going from the nozzle towards a small face of the mold. As will no doubt have already been understood, the invention makes use of a well-known and, if one may say, commercially available means, the mobile magnetic field produced by a linear polyphase static inductor , to act dynamically on the liquid metal within the ingot mold in order to establish a "double loop" flow mode, or to stabilize it if it is already naturally present.
Les premières applications de la magnétohydrodynamique (ou JMHD) à la coulée continue des métaux datent maintenant de près de trente ans et leur succès ne s'est jamais démenti jusqu'ici. Au contraire, des progrès continus jalonnent son histoire. Les premières descriptions concernaient les étages de la machine de coulée sous la lingotière, en particulier la zone de refroidissement secondaire en raison de l'absence d'effet d'écran magnétique qu'opposerait sinon les parois en cuivre de la lingotière. Mais, bien vite, sont apparues des alimentations en courant électrique polyphasées à thyristors qui ont permis . de travailler avec des fréquences de courant excitateur basses, disons inférieures à lOhz, de sorte que, compté tenu des puissances disponibles, l'effet d'écran résiduel que pouvaient encore opposer les parois de cuivre ne représentait plus un obstacle à l'application de la MHD au sein de la lingotière elle-même. Des applications en lingotière multiples et variées lui sont ainsi confiées qui vont, pour schématiser, de la simple mise en mouvement du métal, en rotation autour de l'axe de coulée par exemple, à son accélération ou son freinage dans la direction des écoulements qu'il a déjà naturellement ou aux changements imposés de direction. De très nombreux documents publiés (ouvrages, articles, brevets) lui ont été dédiés. On citera simplement ici, pour simple référence historique, le brevet français n° 2.187.465 (IRSID) datant de 1972 et décrivant déjà un brassage remontant le long des parois par action sur le métal d'un champ magnétique glissant verticalement. On visait ainsi à favoriser une structure de solidification de type équiaxe dès la lingotière, ainsi que l'amélioration de la propreté sous-cutanée via un lavage du front de solidification par les courants ascendants de métal liquide emportant avec eux les bulles de gaz formées in situ et les inclusions non métalliques jusqu'au ménisque où elles sont fixées par le laitier de couverture qui surnage.The first applications of magnetohydrodynamics (or JMHD) to the continuous casting of metals are now almost thirty years old and their success has never been denied so far. On the contrary, continuous progress has marked its history. The first descriptions concerned the stages of the casting machine under the mold, in particular the secondary cooling zone due to the absence of a magnetic shielding effect that would otherwise oppose the copper walls of the mold. But very soon, polyphase thyristor electric power supplies appeared which made it possible. to work with low excitation current frequencies, say less than 10 Hz, so that, taking into account the available powers, the residual screen effect which the copper walls could still oppose no longer represented an obstacle to the application of MHD within the mold itself. Multiple and varied ingot mold applications are thus entrusted to it which go, to schematize, from the simple setting in motion of the metal, in rotation around the axis of casting for example, to its acceleration or its braking in the direction of the flows that 'it already naturally or at imposed changes of direction. Numerous published documents (books, articles, patents) have been dedicated to him. We will simply cite here, for simple historical reference, French patent No. 2,187,465 (IRSID) dating from 1972 and already describing a mixing going up along the walls by action on the metal of a vertically sliding magnetic field. The aim was thus to promote a solidification structure of the equiaxial type from the mold, as well as the improvement of subcutaneous cleanliness by washing the solidification front with the ascending currents of liquid metal taking with them the gas bubbles formed in situ and non-metallic inclusions up to the meniscus where they are fixed by the covering slag which floats.
On citera également, plus près de nous, et parce que l'application concernée est peu éloignée de celle de l'invention, voire complémentaire, la Demande de BrevetWe will also cite, closer to us, and because the application concerned is not far from that of the invention, or even complementary, the Patent Application
Européen publiée sous le n° 0.550.785 (NJKK corp.). Ce document propose, en effet, l'utilisation de champs magnétiques glissants vers l'intérieur, c'est à dire des petites faces vers la busette, pour freiner les jets de métal liquide sortant des ouïes afin de modérer la vigueur des écoulements en "double boucle" lorsque les vitesses mesurées au ménisque sont estimées trop élevées.European published under No. 0.550.785 (NJKK corp.). This document proposes, in fact, the use of magnetic fields sliding inwards, that is to say small faces towards the nozzle, to brake the jets of liquid metal leaving the gills in order to moderate the force of the flows in " double loop "when the speeds measured at the meniscus are estimated to be too high.
De même, la Demande de Brevet Européen publiée sous le n° 0.151.648 (KSC) décrit, elle, les choix possibles entre un brassage vertical du métal en lingotière à l'aide de champs magnétiques glissants verticalement de bas en haut pour améliorer la propreté de surface du produit coulé, et un brassage horizontal à l'aide de champs mobiles horizontalement pour améliorer alors la propreté inclusionnaire sous-cutanée par un effet de lavage du front de solidification. Dans ce cas, il est conseillé d'ailleurs de régler les différents inducteurs entre eux de manière que les champs glissants, que chacun produit individuellement indépendamment des autres, génèrent un effet d'ensemble qui soit de préférence un mouvement de convection rotatif du métal autour de l'axe de la lingotière. Il y est également suggéré que des champs glissants horizontalement vers l'intérieur, en sens opposé des jets issus de la busette, donc des petites faces vers la busette, seraient favorables à l'obtention d'une propreté inclusionnaire située en profondeur sous la peau solidifiée. En revanche, des champs glissants horizontalement vers l'extérieur seraient eux favorables, tout comme l'étaient déjà les champs glissants remontant du brevet français de 1972 prémentionné, à un lavage du front de solidification afin de le débarrasser, à l'endroit de l'action du champ, des inclusions non métalliques ainsi que des bulles de CO gazeux formées par la solidification du métal.Likewise, the European Patent Application published under No. 0.151.648 (KSC) describes the possible choices between vertical mixing of the metal in the mold at using vertically sliding magnetic fields from bottom to top to improve the surface cleanliness of the cast product, and horizontal stirring using horizontally movable fields to then improve subcutaneous inclusion cleanliness by a forehead washing effect solidification. In this case, it is also advisable to adjust the different inductors together so that the sliding fields, which each produces individually independently of the others, generate an overall effect which is preferably a rotary convection movement of the metal around of the mold axis. It is also suggested that fields sliding horizontally inwards, in opposite directions from the jets coming from the nozzle, therefore from the small faces towards the nozzle, would be favorable for obtaining an inclusive cleanliness situated deep under the skin. solidified. On the other hand, horizontally outward sliding fields would be favorable, as were already the sliding fields dating back to the French patent of 1972 mentioned above, to washing the solidification front in order to rid it, at the place of the field action, non-metallic inclusions as well as CO gas bubbles formed by the solidification of the metal.
On aura d'ailleurs noté que ce mode opératoire de mise en oeuvre de champs magnétiques glissants horizontalement vers l'extérieur et agissant en hauteur au niveau des ouïes de la busette sur les jets de métal entrant s'inscrit à l'instar d'une variante préférée de ce que l'invention propose de faire systématiquement durant toute la coulée, mais, dans ce cas, pour imposer un mode de circulation stable en "double boucle" des mouvements de convection du métal en fusion au sein de la lingotière.We have also noted that this operating mode of magnetic fields sliding horizontally outward and acting in height at the gills of the nozzle on the incoming metal jets is like a preferred variant of what the invention proposes to do systematically during the entire casting, but, in this case, to impose a stable mode of circulation in "double loop" convection movements of the molten metal within the ingot mold.
L'invention sera de toute façon bien comprise et d'autres aspects et avantages apparaîtront plus clairement au vu de la description qui suit donnée, à titre d'exemple, en référence aux planches de dessins annexées sur lesquelles: - les figures 1 A et 1B montrent, on le rappelle, vue de face et en élévation dans un plan médian vertical axial passant par les ouïes de sortie latérale d'une busette immergée et parallèle aux grandes faces de la lingotière, la forme générale des trajectoires des courants de convection du métal liquide au sein de la lingotière, respectivement dans le cas d'un mode "simple boucle" (1A) et dans le cas d'un mode "double boucle" (1B);The invention will in any case be well understood and other aspects and advantages will appear more clearly in the light of the following description given, by way of example, with reference to the accompanying drawing plates in which: - Figures 1A and 1B show, it will be recalled, front view and in elevation in an axial vertical median plane passing through the lateral outlet gills of a submerged nozzle and parallel to the large faces of the ingot mold, the general shape of the trajectories of the convection currents of the liquid metal within the mold, respectively in the case of a "single loop" mode (1A) and in the case of a "double loop" mode (1B);
- la figure 2 est un graphique statistique établi à partir d'une compilation de données réelles et permettant de déterminer en fonction des paramètres de coulée que sont la vitesse de coulée en abscisses et la largeur de la brame coulée en ordonnées, les domaines de fonctionnement naturellement stable en "simple boucle" -domaine S- et en "double boucle"-domaine D-. Les triangles sont des événements de type "simple boucle"; les losanges sont des événements de type "double boucle". Pour des raisons de clarté, les données correspondantes à des événements naturellement instables, basculant aléatoirement d'un mode S à D ou de D à S n'ont pas été portées.- Figure 2 is a statistical graph established from a compilation of real data and making it possible to determine as a function of the casting parameters that are the casting speed on the abscissa and the width of the slab casting on the ordinate, the operating domains naturally stable in "single loop" -domain S- and in "double loop" -domain D-. Triangles are "single loop" type events; the diamonds are "double loop" type events. For reasons of clarity, the data corresponding to naturally unstable events, randomly switching from an S to D mode or from D to S have not been carried.
- la figure 3 est une vue schématique générale de ce qu'est une lingotière de coulée continue de brames équipées des moyens de l'invention; - la figure 4 est une vue similaire à celle de la figure 3 mais montrant un peu plus en détails la technologie des inducteurs linéaires à champ glissant utilisables; - la figure 5 est un schéma de principe, montrant vu de dessus de la lingotière le mode d'action des inducteurs à champ glissant mis en œuvre selon l'invention; - la figure 6 montre, venant d'une simulation informatique par modèle de calcul, trois couples de schémas A, B, C, disposés les uns au-dessus des autres, et représentant chacun les caractéristiques des mouvements de convection au sein d'une lingotière à brames avec différentes valeurs de l'intensité des champs magnétiques glissants appliqués conformément à l'invention. Sur les figures, les mêmes éléments sont désignés sous des références numériques identiques.- Figure 3 is a general schematic view of what an ingot mold for continuous casting of slabs equipped with the means of the invention; - Figure 4 is a view similar to that of Figure 3 but showing a little more detail the technology of linear inductors sliding field usable; - Figure 5 is a block diagram, showing seen from above the ingot mold the mode of action of the sliding field inductors implemented according to the invention; FIG. 6 shows, coming from a computer simulation by calculation model, three pairs of diagrams A, B, C, arranged one above the other, and each representing the characteristics of the convection movements within a slab ingot mold with different values of the intensity of the sliding magnetic fields applied in accordance with the invention. In the figures, the same elements are designated with identical reference numbers.
Les figures 1A et 1B ont déjà servi à illustrer les définitions données dans la partie introductive du présent mémoire de ce qu'il faut entendre sous les vocables de "simple boucle" et "double boucle" dans le contexte de l'invention. Sur la figure 2, à laquelle on se réfère maintenant, les domaines S et D, correspondants respectivement aux deux types de recirculation naturelle stables "Simple boucle et "Double boucle", sont séparés par une ligne double P en traits discontinus légèrement oblique par rapport à la verticale. Cette ligne de séparation P permet de se rendre compte aisément que le mode de recirculation naturel en "double boucle", domaine D, est plutôt réservé aux vitesses de coulée élevées, disons supérieure à 1,4 m/min, et ce quelle que soit la largeur de la bande coulée, alors qu'en dessous de 1,2 m/min environ, on se situe quasiment systématiquement dans le domaine S du "simple boucle". Entre les deux, il suffit d'une faible modification du format des produits coulés, en l'occurrence d'l/10eme environ, pour passer d'un mode à l'autre. De même, pour les largeurs coulées classiques, allant disons de 1200 à 2100 mm, on peut facilement basculer d'un mode "double boucle" à un mode "simple boucle" simplement sous l'influence d'un changement relativement minime de la vitesse de coulée dans la plage habituelle de 1.2 à 1.4 m/min. En tous cas, on voit qu'à la vitesse habituelle de 1.3 m/min, le pivot sur la largeur du produit est 1500 mm. En dessous, on reste en "double boucle", au-dessus, on passe rapidement en "simple boucle". La ligne pointillée d'allure générale hyperbolique R représente, elle, une coulée de référence avec un débit métal constant de 4,6 tonnes/min, (produit entre la section coulée et la vitesse de coulée si l'on admet que le niveau en hauteur du ménisque oscille peu autour d'une valeur fixe au cours de la coulée). On notera que la ligne de séparation P se translate vers la gauche, élargissant le domaine du "double boucle" quand la profondeur d'immersion de la busette augmente ou, si l'on utilise un bullage à l'argon pour éviter les risques de bouchage de la busette (coulées de nuances bas ou très bas carbone calmées à l'aluminium par exemple), quand le débit d'argon baisse. On aura compris, qu'en somme, la mise en œuvre de l'invention consiste en fait à faire disparaître la ligne P en la translatant vers la gauche jusqu'à son éviction du diagramme.FIGS. 1A and 1B have already served to illustrate the definitions given in the introductory part of this memo of what is to be understood under the terms of "single loop" and "double loop" in the context of the invention. In FIG. 2, to which we now refer, the domains S and D, corresponding respectively to the two types of stable natural recirculation "Single loop and" Double loop ", are separated by a double P line in broken lines slightly oblique with respect to This dividing line P makes it easy to see that the natural "double loop" recirculation mode, domain D, is rather reserved for high casting speeds, say greater than 1.4 m / min, and whatever the width of the casting strip, while below about 1.2 m / min, we are almost always in the S domain of the "single loop". modification of the format of the cast products, in this case around 1/10 th , to switch from one mode to the other. Similarly, for conventional casting widths, ranging from say 1200 to 2100 mm, it is easy to switch from a "double loop" mode to a mod e "simple loop" simply under the influence of a relatively small change in the casting speed in the usual range from 1.2 to 1.4 m / min. In any case, we see that at the usual speed of 1.3 m / min, the pivot on the width of the product is 1500 mm. Below, we stay in "double loop", above, we quickly pass in "single loop". The dotted line of general hyperbolic appearance R represents a reference flow with a constant metal flow rate of 4.6 tonnes / min, (product between the casting section and the casting speed if it is assumed that the level in meniscus height hardly fluctuates around a fixed value during casting). It will be noted that the separation line P translates to the left, widening the area of the "double loop" when the immersion depth of the nozzle increases or, if an argon bubbling is used to avoid the risks of clogging of the nozzle (flows of low or very low carbon grades calmed with aluminum for example), when the flow of argon decreases. It will be understood that, in short, the implementation of the invention consists in fact in making the line P disappear by translating it to the left until it is ousted from the diagram.
A cette fin, les moyens de mise en œuvre de l'invention sont ceux illustrés sur la figure 3 d'abord. Sur cette figure, on voit une lingotière 18 pour la coulée de brames en acier 9 constituée pour l'essentiel de deux paires de plaques de cuivre, ou d'alliage de cuivre, vigoureusement refroidies par circulation d'eau de refroidissement: une paire de grandes plaques en regard l'une de l'autre à une distance définissant l'épaisseur de la brame: ce sont les grandes faces; et une paire de petites plaques, montées de façon étanche au droit à l'extrémité des grandes plaques afin d'assurer la continuité du pourtour intérieur de la lingotière qui définit l'espace de coulée. Ces plaques de fermeture latérale de l'espace de coulée sont les petites faces. Elles sont, en règle générale, montées mobiles en translation et leur position entre les grandes plaques plus ou moins avancée vers le centre est alors un moyen de réglage de la largeur de la brame coulée. La lingotière est alimentée en métal frais par une busette immergée 3 centrée sur l'axe de coulée A et dont l'extrémité haute est reliée de façon étanche à l'ouverture ménagée dans le fond d'un répartiteur non représenté. Comme déjà vu sur les figures 1A et 1B5 l'extrémité inférieure libre de la busette est pourvue d'ouïes de sortie latérales, diamétralement opposées, et plonge dans la lingotière à une profondeur ajustée (une quarantaine de centimètres environ en dessous du bord supérieur des plaques de cuivre), avec une orientation angulaire réglée pour que chaque ouïe soit tournée en regard d'une petite face 5 de la lingotière.To this end, the means of implementing the invention are those illustrated in FIG. 3 first. In this figure, an ingot mold 18 can be seen for the casting of steel slabs 9 consisting essentially of two pairs of plates of copper, or of copper alloy, vigorously cooled by circulation of cooling water: a pair of large plates facing each other at a distance defining the thickness of the slab: these are the large faces; and a pair of small plates, mounted in a leaktight manner at the end of the large plates in order to ensure the continuity of the internal periphery of the mold which defines the casting space. These lateral closing plates of the pouring space are the small faces. They are, as a general rule, mounted mobile in translation and their position between the large plates more or less advanced towards the center is then a means of adjusting the width of the cast slab. The ingot mold is supplied with fresh metal by a submerged nozzle 3 centered on the casting axis A and the upper end of which is tightly connected to the opening made in the bottom of a distributor not shown. As already seen in FIGS. 1A and 1B 5 the free lower end of the nozzle is provided with lateral outlet holes, diametrically opposed, and plunges into the mold at an adjusted depth (about forty centimeters below the upper edge copper plates), with an angular orientation adjusted so that each hole is turned opposite a small face 5 of the mold.
Les moyens pour la mise en œuvre de l'invention sont bien visibles en position de travail sur la figure 3. Ils sont constitués par une unité électromagnétique 10 reliée à une alimentation électrique polyphasée 11 , de préférence triphasée.The means for implementing the invention are clearly visible in the working position in FIG. 3. They consist of an electromagnetic unit 10 connected to a polyphase electrical supply 11, preferably three-phase.
L'alimentation de puissance 11 est à thyristors afin de pouvoir faire varier la fréquence du courant en agissant sur la molette 12 en façade. Un autre bouton molette 13 permet lui de régler l'intensité du courant. ( The power supply 11 has thyristors in order to be able to vary the frequency of the current by acting on the thumb wheel 12 on the front panel. Another knob 13 allows him to adjust the intensity of the current. (
L'unité électromagnétique est formée de quatre inducteurs linéaires, de préférence identiques, de type stator plan de moteur asynchrone. Pour ce qui suit, on se référera conjointement aux figures 3, 4 et 5 afin d'avoir une approche plus complète des moyens mis en oeuvre pour la réalisation de l'invention. Ces inducteurs sont regroupés par paires, une paire d'inducteurs 14,14' (et 15,15') par grande face de la lingotière. Les deux inducteurs d'une même paire, par exemple la paire 14,14', sont montés sur la même grande face, mais de part et d'autre de la busette 3 en position relative de préférence symétrique. Ces deux inducteurs 14,14' peuvent être indépendants l'un de l'autre mécaniquement et électriquement. Ils sont cependant reliés à l'alimentation 11 qui commande leur fonctionnement magnétique de manière coordonnée afin que chacun produise un champ magnétique glissant horizontalement vers l'extérieur de la lingotière, c'est à dire dans un sens allant de la busette 3 vers les petites faces d'extrémité 5. Les maximums de chaque champ n'ont pas non plus besoin d'être à chaque instant situés le long de l'inducteur à égale distance de la busette. Il importe seulement que les enroulements électriques constitutifs de chaque inducteur, que celui-ci soit du type "à pôles magnétiques saillants" donc bobinés, ou du type "à pôles répartis", soient eux- mêmes polyphasés et compatibles sur ce plan avec l'alimentation 11 de manière à pouvoir être chacun relié aux bornes de cette alimentation dans un ordre de phases séquentiel adéquat assurant le glissement du champ dans le sens "vers l'extérieur" souhaité.The electromagnetic unit is formed by four linear inductors, preferably identical, of the flat stator type of an asynchronous motor. For what follows, reference will be made jointly to FIGS. 3, 4 and 5 in order to have a more complete approach of the means used for the realization of the invention. These inductors are grouped in pairs, a pair of inductors 14.14 '(and 15.15') per large face of the ingot mold. The two inductors of the same pair, for example the pair 14, 14 ′, are mounted on the same large face, but on either side of the nozzle 3 in a preferably symmetrical relative position. These two inductors 14, 14 ′ can be independent of each other mechanically and electrically. They are however connected to the power supply 11 which controls their magnetic operation in a coordinated manner so that each one produces a magnetic field sliding horizontally towards the outside of the ingot mold, that is to say in a direction going from the nozzle 3 towards the small end faces 5. The maximums of each field also do not need to be located at all times along the inductor at equal distance from the nozzle. It is only important that the electrical windings constituting each inductor, whether it is of the "salient magnetic pole" type therefore wound, or of the "distributed pole" type, are themselves polyphase and compatible in this respect with power supply 11 so that each can be connected to the terminals of this power supply in an adequate sequential phase order ensuring the sliding of the field in the desired "outward" direction.
On rappelle au besoin que si le glissement du champ magnétique est parallèle à la face à laquelle l'inducteur est appliqué, le champ lui-même, généré par cet inducteur, est globalement perpendiculaire au plan de cette face. En tous cas, on sait que c'est la composante perpendiculaire à cette face qui est la seule active dans la production d'énergie utile sous forme d'une force d'entraînement du métal dans le sens du glissement du champ. On a donc avantage, afin de maximiser le rendement énergétique de l'opération, de disposer d'inducteurs dont les lignes de force des champs produits sont orthogonales au plan des faces et qu'elles se propagent ainsi le plus loin possible à l'intérieur du métal à couler.It is recalled if necessary that if the sliding of the magnetic field is parallel to the face to which the inductor is applied, the field itself, generated by this inductor, is generally perpendicular to the plane of this face. In any case, we know that it is the component perpendicular to this face which is the only active in the production of useful energy in the form of a metal driving force in the direction of the sliding of the field. It is therefore advantageous, in order to maximize the energy efficiency of the operation, to have inductors whose lines of force of the fields produced are orthogonal to the plane of the faces and which they thus propagate as far as possible inside. metal to be poured.
C'est la raison pour laquelle d'ailleurs, en règle générale, on rajoute une seconde paire d'inducteurs, telle que 15,15' en regard sur l'autre grande face de la lingotière. L'alimentation 11 alimente alors ces inducteurs ajoutés en opposition de phase par rapport aux inducteurs 14, 14' en regard pris dans cet ordre, de sorte que les champs produits par deux inducteurs en regard l'un de l'autre sur les deux faces opposées de la lingotière, en l'occurrence 14 et 15, ou 14' et 15', sont dans le même sens et donc s'additionnent pour, en tout point de l'espace de l'entrefer ainsi formé, constituer un champ magnétique traversant le produit coulé de part en part, et dont on sait l'avantage par rapport à un champ longitudinal puisque l'intensité au centre du produit est à peine plus faible qu'au voisinage des inducteurs.This is the reason why, moreover, as a general rule, a second pair of inductors is added, such as 15.15 'facing each other on the other large face of the ingot mold. The power supply 11 then supplies these inductors added in phase opposition with respect to the inductors 14, 14 'facing taken in this order, so that the fields produced by two inductors facing each other on the two faces opposite of the ingot mold, in this case 14 and 15, or 14 'and 15', are in the same direction and therefore add up, at any point in the space of the gap thus formed, to constitute a magnetic field passing through the product poured right through, and the advantage of which is known with respect to a longitudinal field since the intensity at the center of the product is hardly lower than in the vicinity of the inductors.
Quoiqu'il en soit, le schéma de la figure 5 montre clairement que conformément à l'invention, lorsqu'on met en œuvre les champs magnétiques glissants pour instaurer un mode "double boucle", ou pour le stabiliser quand il s'y trouve déjà naturellement, le sens de glissement est le même pour tous les inducteurs agissant dans un même demi-espace de coulée (gauche ou droit), et dans chaque demi-espace le sens de glissement va vers l'extérieur de la lingotière, c'est à dire de la busette 3 vers les petites faces d'extrémité 5. La figure 4 permet d'offrir une vue un peu plus détaillée d'une réalisation technologique des inducteurs. Ils sont montés, comme on le voit, dans la chambre à eau de refroidissement supérieure 16 de la lingotière (dessinée en traits fins) afin de bénéficier de l'effet de refroidissement, mais aussi pour pouvoir rapprocher les faces actives polaires 17 au plus près du métal coulé. On voit également que chaque inducteur • porte des nervures apparentes 19, 19', 20, destinées à assurer les fixations et alignements nécessaires entre eux et à régler leur position en hauteur par prise dans des rainures de support correspondantes dans le châssis porteur de la machine de coulée (non représenté). On notera la forme biseautée des faces actives 17, afin d'être moins exposées lors des manutentions, mais également afin de concentrer un peu plus les lignes de force du champ magnétique produit sur une distance en hauteur plus réduite.Anyway, the diagram in Figure 5 clearly shows that according to the invention, when implementing the sliding magnetic fields to establish a "double loop" mode, or to stabilize it when it is there already naturally, the direction of sliding is the same for all the inductors acting in the same half-casting space (left or right), and in each half-space the direction of sliding goes towards the outside of the mold, it ie from the nozzle 3 towards the small end faces 5. FIG. 4 makes it possible to offer a slightly more detailed view of a technological embodiment of the inductors. They are mounted, as can be seen, in the upper cooling water chamber 16 of the mold (drawn in thin lines) in order to benefit from the cooling effect, but also to be able to bring the polar active faces 17 closer together. cast metal. We also see that each inductor • carries visible ribs 19, 19 ', 20, intended to ensure the fastenings and alignments necessary between them and to adjust their height position by taking in corresponding support grooves in the supporting frame of the casting machine (not shown). Note the beveled shape of the active faces 17, in order to be less exposed during handling, but also in order to concentrate a little more the lines of force of the magnetic field produced over a shorter height distance.
La mise en œuvre d'un tel équipement électromagnétique permet la maîtrise des mouvements de convection du métal au sein de la lingotière conformément à l'invention, et la figure 6 à laquelle on se reporte maintenant illustre bien le profit tiré de cette maîtrise. Chaque schéma A, B, ou C présente, dans sa fenêtre de gauche, les trajectoires des lignes de courant de convection du métal choisi arbitrairement dans le demi-espace droit de coulée d'une lingotière à brames, contenu en abscisses L entre l'axe de coulée A et la petite face d'extrémité 5, et se développant sur la hauteur h de la lingotière depuis le ménisque 4 (ordonnée 0) jusqu'à une profondeur de 70 cm. Le graphe associé à droite donne en ordonnées les valeurs correspondantes de la vitesse "s" du métal au niveau du ménisque 4 sur la ligne de mesure médiane qui relie l'ouïe de sortie 2 de la busette à la petite face d'extrémité opposée 5 placée en abscisses. Cette vitesse est comptée algébriquement, avec un signe positif quand le sens des courants va de la busette vers la petite face et donc négativement dans le sens contraire. Toute chose égale par ailleurs, chaque couple est représentatif d'une valeur différente de l'intensité du champ magnétique agissant. Le couple A est associé à un champ nul (i = 0 A), donc illustre la situation avant la mise en œuvre de l'invention. Le couple B est associé à une valeur d'intensité de champ magnétique moyenne, correspondant à un courant excitateur des enroulements inductifs d'intensité efficace i de 250 A. Le couple C illustre la situation quand le champ magnétique appliqué est produit sous une intensité de courant i de 450 A.The implementation of such electromagnetic equipment allows the control of the convection movements of the metal within the ingot mold in accordance with the invention, and FIG. 6 to which we now refer clearly illustrates the benefit derived from this control. Each diagram A, B, or C presents, in its window on the left, the trajectories of the convection current lines of the metal chosen arbitrarily in the right half-space of casting of an ingot mold with slabs, contained on the abscissa L between the casting axis A and the small end face 5, and developing over the height h of the mold from the meniscus 4 (ordinate 0) to a depth of 70 cm. The associated graph on the right gives the corresponding values of the speed "s" of the metal on the ordinate at the meniscus 4 on the median measurement line which connects the outlet port 2 of the nozzle to the small opposite end face 5 placed on the abscissa. This speed is counted algebraically, with a positive sign when the direction of the currents goes from the nozzle to the small face and therefore negatively in the opposite direction. Everything else being equal, each couple is representative of a different value of the intensity of the magnetic field acting. The couple A is associated with a zero field (i = 0 A), therefore illustrates the situation before the implementation of the invention. Torque B is associated with an average magnetic field intensity value, corresponding to an excitation current of inductive windings with effective intensity i of 250 A. Couple C illustrates the situation when the applied magnetic field is produced at an intensity of current i of 450 A.
Comme on le voit sur A, à l'état naturel, dans l'exemple considéré, la configuration est du type "simple boucle". Le jet, qui sort de l'ouïe 2, suit une trajectoire principale 1 tracée en traits foncés qui est à peu de chose près celle que l'on retrouve sur la figure 1 A. On ne le décrira donc pas à nouveau ici. On notera cependant la présence au voisinage immédiat de la busette d'un petit rouleau 21 tournant à contresens. Ce phénomène local naît du fait que le courant principal 1 remonte certes vers le ménisque après la sortie du jet de métal hors de l'ouïe 2, mais cette remontée n'est, bien entendu, ni immédiate ni parfaitement verticale, de sorte qu'il se crée inévitablement des recirculations locales à contresens dans les zones hydrauliquement "mortes" contre la busette. On le voit d'ailleurs clairement sur le diagramme associé des vitesses au ménisque où l'inversion des vitesses s'opère en un point M à la cote d'abscisse 0.5 m de l'axe de coulée correspondant à l'extrémité du rouleau 21. A gauche de ce point d'inversion M, le métal circule au ménisque dans le sens "petite face vers busette", alors qu'il circule de la busette vers la petite face à droite du point M, avec une intensité d'ailleurs sensiblement plus élevée en moyenne. Cette courbe de vitesse est reproduite sur les deux autres diagrammes afin de servir de comparaison.As seen on A, in the natural state, in the example considered, the configuration is of the "single loop" type. The jet, which comes out of hearing 2, follows a main trajectory 1 traced in dark lines which is about the same as that found in Figure 1 A. We will not describe it again here. Note, however, the presence in the immediate vicinity of the nozzle of a small roller 21 rotating in the opposite direction. This local phenomenon arises from the fact that the main current 1 certainly goes up towards the meniscus after the exit of the metal jet out of the hearing 2, but this ascent is, of course, neither immediate nor perfectly vertical, so that inevitable local recirculations are created in the hydraulically "dead" zones against the nozzle. We can also see it clearly on the associated diagram of the speeds at the meniscus where the speeds are reversed at a point M at the abscissa dimension 0.5 m from the casting axis corresponding to the end of the roller 21 To the left of this reversal point M, the metal flows to the meniscus in the direction "small face towards nozzle", while it flows from the nozzle to the small face to the right of point M, with an intensity moreover significantly higher on average. This speed curve is reproduced on the other two diagrams for comparison.
Lorsqu'on active les inducteurs sous un courant d'excitation de 250 Ampères efficaces sur les 500 disponibles qu'offrait l'équipement considéré, le schéma B montre que rien ne se passe de significativement différent par rapport à la situation précédente. On notera cependant, sur le diagramme des vitesses un léger fléchissement du pic de vitesse positive (région du ménisque à la droite du point d'inversion M), donc un léger déplacement de ce point M vers la petite face 5, ce qui exprime en fait une amorce en faveur de l'instauration du mode de circulation "double boucle" recherché. Ce mode "double boucle" est en effet pleinement obtenu avec une intensité du courant excitateur des inducteurs de 450 A eff., comme le montre le schéma C. En effet, le point d'inversion a cette fois complètement disparu pour laisser place à un profil de valeurs négatives tout du long du ménisque. On voit sur la fenêtre de gauche que ceci se traduit, outre la transformation de la ligne de courant principal 1 remontante en une ligne 8 continûment descendante, par l'apparition d'une boucle de recirculation supérieure 7 qui amène une fraction du jet de métal frais coulé, remontant le long de la petite face, de celle-ci jusqu'à la busette 3 et qui, à peu de chose près, peut se calquer sur la configuration en "double boucle"que l'on retrouve sur la figure 1B.When the inductors are activated under an excitation current of 250 effective amperes out of the 500 available offered by the equipment considered, diagram B shows that nothing happens significantly different from the previous situation. Note, however, on the velocity diagram a slight decrease in the positive speed peak (region of the meniscus to the right of the point of inversion M), therefore a slight displacement of this point M towards the small face 5, which expresses in made a start in favor of establishing the desired "double loop" circulation mode. This "double loop" mode is in fact fully obtained with an intensity of the excitation current of the inductors of 450 A eff., As shown in diagram C. In fact, the reversal point has this time completely disappeared to make room for a profile of negative values along the meniscus. We see on the left window that this translates, in addition to the transformation of the main current line 1 rising into a line 8 continuously descending, by the appearance of an upper recirculation loop 7 which brings a fraction of the metal jet fresh poured, going up along the small face, from this one to the nozzle 3 and which, more or less, can be modeled on the configuration in "double loop" which one finds on figure 1B .
On voit donc sur cet exemple comment la mise en œuvre de l'invention permet d'instaurer très simplement un mode de circulation "double boucle" au métal coulé dans une lingotière qui naturellement était le siège d'une circulation en mode "simple boucle".We therefore see in this example how the implementation of the invention makes it possible to very simply establish a "double loop" mode of circulation in the metal poured into an ingot mold which naturally was the seat of a circulation in "single loop" mode .
Il en aurait été de même si la situation naturelle avait été un régime de type instable. Si la situation d'origine avait été déjà en mode "double boucle", l'invention l'aurait stabilisé. Dans un tel cas, il n'est nullement à craindre que l'invention conduise à des mouvements de convection trop vigoureux au niveau du ménisque, dont on sait qu'ils sont alors préjudiciables à la qualité recherchée du produit coulé obtenu. En effet, le principe même du fonctionnement des inducteurs plans polyphasés à champ glissant est celui du moteur asynchrone: c'est le différentiel de vitesses entre le champ magnétique glissant et le courant de métal liquide, sur lequel il agit pour l'entraîner dans son déplacement, qui détermine précisément la force d'entraînement du métal. Tant que la vitesse de glissement du champ est supérieure à celle de la convection du métal, il y a effet d'entraînement du métal par le champ. Mais, cet effet d'entraînement est d'autant moins puissant que la vitesse de circulation du métal se rapproche de celle de déplacement du champ magnétique, et l'effet devient par principe nul si ces deux vitesses sont égales ou s'égalisent.It would have been the same if the natural situation had been an unstable type of diet. If the original situation had already been in "double loop" mode, the invention would have stabilized it. In such a case, there is no reason to fear that the invention will lead to too vigorous convection movements at the level of the meniscus, which we know to be detrimental to the desired quality of the cast product obtained. Indeed, the very principle of the operation of polyphase plane inductors with sliding field is that of the asynchronous motor: it is the speed differential between the sliding magnetic field and the current of liquid metal, on which it acts to entrain it in its displacement, which precisely determines the driving force of the metal. As long as the sliding speed of the field is higher than that of the convection of the metal, there is an effect of entrainment of the metal by the field. However, this ripple effect is all the less powerful as the speed of movement of the metal approaches that of movement of the magnetic field, and the effect becomes in principle zero if these two speeds are equal or equalize.
En somme, si le mode naturel de circulation du métal en fusion au sein de la lingotière est déjà en "double boucle", la mise en œuvre de l'invention aura l'avantage de le stabiliser, le régulariser, voire le modérer au besoin. Il suffit en effet pour cela d'intervenir sur le réglage de la fréquence du courant excitateur. Pour un pas polaire donné de l'inducteur, la vitesse de glissement du champ magnétique mobile qu'il génère est en effet, comme on le sait, proportionnelle à la fréquence de pulsation du champ, donc du courant électrique qui le produit en parcourant les enroulements de l'inducteur. En conséquence, l'invention permettra au besoin de calmer automatiquement une boucle de recirculation au ménisque trop vigoureuse, en choisissant une fréquence du courant excitateur telle que la vitesse de déplacement des champs soit inférieure à celle du courant de métal au ménisque.In short, if the natural mode of circulation of the molten metal within the ingot mold is already in "double loop", the implementation of the invention will have the advantage of stabilizing it, regularizing it, even moderating it if necessary . It is indeed enough for that to intervene on the adjustment of the excitation current frequency. For a given pole pitch of the inductor, the sliding speed of the mobile magnetic field that it generates is indeed, as we know, proportional to the frequency of the field's pulsation, therefore of the electric current which produces it by traversing the inductor windings. Consequently, the invention will allow the need to automatically calm an overly vigorous meniscus recirculation loop, by choosing a frequency of the excitation current such that the speed of movement of the fields is lower than that of the metal current at the meniscus.
Autrement-dit, on règle l'intensité du champ magnétique par le choix de l'intensité du courant excitateur; on règle sa vitesse de glissement via la fréquence de ce courant; et on règle le sens du glissement du champ par une connexion ad hoc des enroulements de l'inducteur aux phases de l'alimentation électrique. Ceci n'est rien d'autre que ce que l'homme de métier, utilisant les moyens de la M.H.D. sur sa machine de coulée, sait déjà de manière habituelle et de longue date. On exprime là encore une fois la simplicité et la maturité de l'outil que met l'invention à la disposition de l'exploitant pour réaliser sa mise en œuvre industrielle.In other words, the intensity of the magnetic field is regulated by the choice of the intensity of the exciting current; its sliding speed is adjusted via the frequency of this current; and the direction of the sliding of the field is adjusted by an ad hoc connection of the windings of the inductor to the phases of the electrical supply. This is nothing other than what the skilled person, using the means of the M.H.D. on his casting machine, already knows in the usual way and for a long time. Here again we express the simplicity and maturity of the tool that the invention makes available to the operator to carry out its industrial implementation.
Cela dit, il est tout à fait envisageable, dans le cadre de l'invention, de ne faire agir les champs magnétiques que si la configuration des mouvements de convection n'est pas déjà naturellement de type "double boucle". La figure 2 constitue à cet égard une précieuse aide graphique qui permettra aisément à l'opérateur de savoir d'emblée s'il se situe naturellement, ou s'il a de bonnes chances de se situer déjà,, dans une configuration simple ou double boucle.That said, it is entirely possible, within the framework of the invention, to act on the magnetic fields only if the configuration of the convection movements is not already naturally of the "double loop" type. Figure 2 constitutes in this respect a precious graphic aid which will easily allow the operator to know straight away if it is naturally located, or if it is likely to be already located, in a single or double configuration. loop.
De même, si la configuration est déjà naturellement en mode "double boucle" stable, on peut fort bien opter pour une variante particulière de mise en œuvre de l'invention qui consiste à mettre en œuvre, non plus les champs glissants pour la promotion d'un régime "double boucle", mais d'autres champs glissants qui eux se déplacent dans le même sens sur chaque face de la lingotière, mais dans des sens opposés sur les deux faces en regard. Ainsi, on se trouvera dans un système de champs magnétiques mobiles dits longitudinaux et non plus traversants, dont l'effet d'ensemble sur le métal se traduira par un mouvement global de rotation du métal autour de l'axe de coulée. Pour ce faire, l'équipement électromagnétique reste exactement le même. Il suffit simplement de modifier en conséquence l'ordre de connexion des enroulements inductifs de chaque inducteur 14, 14', 15 et 15' aux bornes de l'alimentation polyphasée 11. Au demeurant, cette variante de réalisation permettra également au besoin de calmer automatiquement une boucle de recirculation au ménisque trop vigoureuse, en choisissant là encore une fréquence du courant excitateur telle que la vitesse de déplacement des champs soit inférieure à celle du courant de métal au ménisque.Similarly, if the configuration is already naturally in stable "double loop" mode, one can very well opt for a particular variant of implementation of the invention which consists in implementing, no longer the sliding fields for the promotion of 'a "double loop" regime, but other sliding fields which move in the same direction on each side of the mold, but in opposite directions on the two opposite sides. Thus, we will be in a system of mobile magnetic fields called longitudinal and no longer through, whose overall effect on the metal will result in an overall rotational movement of the metal around the casting axis. To do this, the electromagnetic equipment remains exactly the same. It suffices simply to modify accordingly the order of connection of the inductive windings of each inductor 14, 14 ', 15 and 15' to the terminals of the polyphase supply 11. Furthermore, this variant embodiment will also allow the need to automatically calm down an overly vigorous meniscus recirculation loop, again choosing a frequency of the excitation current such that the speed of movement of the fields is lower than that of the metal current at the meniscus.
Il va de soi que l'invention ne saurait se limiter aux exemples explicités dans le présent mémoire, mais s'étend à de multiples variantes ou équivalents dans la mesure où est respectée sa définition donnée par les revendications jointes. Par exemple, on peut promouvoir le mode "double boucle" avec des champs magnétiques glissants agissant, non plus sur la ou les grandes faces de la lingotière, mais sur les petites faces d'extrémité. L'inducteur à utiliser pour créer chaque champ agissant pourra être le même que précédemment. Mais, il devra être placé sur la petite face en hauteur à un niveau correspondant grosso modo à la plage qui sépare le ménisque de la projection horizontale sur la petite face de l'ouïe de la busette ouverte en regard, et sera orienté différemment afin de produire un champ glissant vertical. Par ailleurs, la connexion de ses enroulements aux phases sur l'alimentation électrique devra être faite pour assurer un déplacement du champ du bas vers le haut. It goes without saying that the invention cannot be limited to the examples explained in the present specification, but extends to multiple variants or equivalents insofar as its definition given by the appended claims is respected. For example, we can promote the "double loop" mode with sliding magnetic fields acting, no longer on the large face (s) of the mold, but on the small end faces. The inductor to be used to create each acting field may be the same as before. But, it should be placed on the small side in height at a level roughly corresponding to the range which separates the meniscus from the horizontal projection on the small side of the hearing of the open open nozzle, and will be oriented differently in order to produce a vertical sliding field. Furthermore, the connection of its windings to the phases on the power supply must be made to ensure a displacement of the field from the bottom to the top.

Claims

REVENDICATIONS
1. Procédé pour la maîtrise de la configuration des écoulements du métal coulé dans une lingotière de coulée continue de brames métalliques ou autres produits plats analogues, notamment en acier, à l'aide d'une busette immergée dotée d'ouies de sorties latérales tournées en regard des petites faces de la lingotière, ladite configuration pouvant être naturellement en mode "simple boucle" ou "double boucle", ou encore "instable", procédé caractérisé en ce que l'on met en œuvre des champs magnétiques glissants agissant sur les flux de métal liquide arrivant en lingotière (18) par les ouïes (2) de la busette immergée (3),' lesdits champs magnétiques étant produits par des inducteurs électromagnétiques linéaires (14, 14'; 15, 15') disposés en regard d'au moins une face de la lingotière de part et d'autre de la busette de manière à installer, ou stabiliser une configuration permanente en mode "double boucle".1. Method for controlling the configuration of flows of metal poured into a mold for continuous casting of metal slabs or other similar flat products, in particular of steel, using an immersed nozzle provided with turned side outlets opposite the small faces of the ingot mold, said configuration possibly being naturally in “single loop” or “double loop” mode, or even “unstable”, process characterized in that sliding magnetic fields acting on the flow of liquid metal arriving in an ingot mold (18) through the gills (2) of the submerged nozzle (3), ' said magnetic fields being produced by linear electromagnetic inductors (14, 14'; 15, 15 ') arranged opposite 'at least one side of the ingot mold on either side of the nozzle so as to install, or stabilize a permanent configuration in "double loop" mode.
2. Procédé selon la revendication 1, caractérisé en ce que l'on met en œuvre des champs magnétiques glissants horizontalement vers l'extérieur, dans le sens allant de la busette (3) vers chaque petite face (5), au moyen d'inducteurs (14, 14'; 15, 15') disposés en regard d'au moins une grande face de la lingotière de part et d'autre de la busette.2. Method according to claim 1, characterized in that one implements magnetic fields sliding horizontally outward, in the direction from the nozzle (3) to each small face (5), by means of inductors (14, 14 '; 15, 15') arranged opposite at least one large face of the ingot mold on either side of the nozzle.
3. Procédé selon la revendication 1 ou 2, caractérisé en ce que l'on fait agir les champs magnétiques glissants pendant toute l'opération de coulée.3. Method according to claim 1 or 2, characterized in that the sliding magnetic fields are made to act during the entire casting operation.
4. Procédé selon la revendication 1 ou 2 caractérisé en ce que l'on met en œuvre lesdits champs magnétiques glissants uniquement si la configuration des écoulements du métal coulé en lingotière n'est pas naturellement en mode "double boucle".4. Method according to claim 1 or 2 characterized in that one implements said sliding magnetic fields only if the configuration of the flows of the metal cast in the mold is not naturally in "double loop" mode.
5. Procédé selon les revendications 2 et A, caractérisé en ce que, si la configuration des écoulements est déjà naturellement en mode "double boucle", on fait agir des champs magnétiques glissants horizontalement au moyen desdits inducteurs (14, 14'; 15, 15') disposés en regard d'au moins une grande face de la lingotière de part et d'autre de la busette après avoir réglé lesdits inducteurs afin que les champs produits par chacun d'eux glissent tous dans le même sens de manière à imprimer au métal liquide dans la lingotière un mouvement d'ensemble de rotation autour de l'axe de coulée.5. Method according to claims 2 and A, characterized in that, if the configuration of the flows is already naturally in "double loop" mode, magnetic fields sliding horizontally are made to act by means of said inductors (14, 14 '; 15, 15 ') arranged opposite at least one large face of the ingot mold on either side of the nozzle after having adjusted said inductors so that the fields produced by each of them all slide in the same direction so as to print liquid metal in the mold an overall rotational movement around the casting axis.
6. Equipement pour la mise en œuvre du procédé selon la revendication 2, comprenant une unité électromagnétique (10) constituée par au moins une paire d'inducteurs linéaires à champ magnétique glissant, montés en regard d'au moins une grande face de la lingotière et orientés de manière à produire un champ magnétique glissant horizontalement, et une alimentation électrique polyphasée commandée (11), ' caractérisé en ce que ladite alimentation électrique est connectée à chaque paire d'inducteurs linéaires (14, 14' ; 15, 15') de ladite unité électromagnétique (10) pour leur faire produire à chacun un champ magnétique glissant dirigé vers l'extérieur, dans un sens allant de la busette immergé (3) vers une petite face de la lingotière (5). 6. Equipment for implementing the method according to claim 2, comprising an electromagnetic unit (10) consisting of at least one pair of linear inductors with sliding magnetic field, mounted facing at least one large face of the mold. and oriented so as to produce a horizontally sliding magnetic field, and a polyphase controlled power supply (11), characterized in that said power supply is connected to each pair linear inductors (14, 14 '; 15, 15') of said electromagnetic unit (10) to make them each produce a sliding magnetic field directed outwards, in a direction from the submerged nozzle (3) towards a small face of the mold (5).
EP03776964A 2002-10-14 2003-10-09 Method and device for controlling flows in a continuous slab casting ingot mould Expired - Lifetime EP1551580B1 (en)

Applications Claiming Priority (3)

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FR0212706 2002-10-14
FR0212706A FR2845626B1 (en) 2002-10-14 2002-10-14 PROCESS FOR CONTROLLING METAL MOVEMENTS IN A BRAMES CONTINUOUS CASTING LINGOTIERE
PCT/FR2003/002978 WO2004035248A1 (en) 2002-10-14 2003-10-09 Method and device for controlling flows in a continuous slab casting ingot mould

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US20060005939A1 (en) 2006-01-12
FR2845626A1 (en) 2004-04-16
AU2003286222A1 (en) 2004-05-04
EP1551580B1 (en) 2011-03-02
JP2006502863A (en) 2006-01-26
TW200408472A (en) 2004-06-01
CA2502089A1 (en) 2004-04-29
DE60336250D1 (en) 2011-04-14
WO2004035248A1 (en) 2004-04-29
ES2358103T3 (en) 2011-05-05
CN1325198C (en) 2007-07-11
CA2502089C (en) 2010-08-31
CN1705530A (en) 2005-12-07
KR20050050141A (en) 2005-05-27
TWI319721B (en) 2010-01-21
JP4794858B2 (en) 2011-10-19
BR0315281B1 (en) 2012-10-02
BR0315281A (en) 2005-08-30
US7201211B2 (en) 2007-04-10
RU2005114523A (en) 2005-10-27
RU2325245C2 (en) 2008-05-27

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