EP0076743B1 - Process for cooling of the cast product in a continuous-casting plant - Google Patents

Process for cooling of the cast product in a continuous-casting plant Download PDF

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Publication number
EP0076743B1
EP0076743B1 EP82401769A EP82401769A EP0076743B1 EP 0076743 B1 EP0076743 B1 EP 0076743B1 EP 82401769 A EP82401769 A EP 82401769A EP 82401769 A EP82401769 A EP 82401769A EP 0076743 B1 EP0076743 B1 EP 0076743B1
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EP
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Prior art keywords
heat
mould
extracted
during
cooling
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EP82401769A
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German (de)
French (fr)
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EP0076743A1 (en
Inventor
Alain Chielens
Philippe Benoit
Bernard Roggo
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Fives Cail Babcock SA
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Fives Cail Babcock SA
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16Controlling or regulating processes or operations
    • B22D11/22Controlling or regulating processes or operations for cooling cast stock or mould
    • B22D11/225Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling

Definitions

  • the invention relates to a cooling method according to the preamble of the claim. Such a method is known from document EP-A-0036342.
  • the flow rate and the heating of the cooling water of the mold are continuously measured; they can also be determined from data stored in the computer memory and established by tests and predictive calculations.
  • the object of the present invention is to provide the process of document EP-A0036342 with an improvement making it possible to determine more precisely the thermal history of each elementary slice of the product poured during its passage through the ingot mold, taking account of the evolution of the heat flow extracted from the top to the bottom of the mold.
  • the process which is the subject of the present invention is characterized in that in order to determine the quantity of heat extracted from each slice during its stay in the ingot mold, the quantity of overall heat extracted from the ingot mold during this interval is determined at regular time intervals. of time, each slice in the ingot mold is allocated during this time interval a fraction of this total amount of heat which is a function of the distance of the slice to the free surface of the metal in the ingot mold and when a slice comes out from the ingot mold we add up all the amounts of fractional heat which have been allocated to it during its stay in the ingot mold.
  • the number of zones is for example between 2 and 20.
  • the number and the lengths of these zones and the distribution of the overall heat flow between these different zones are defined taking into account the evolution of thermal efficiency from top to bottom of the mold and deducted from the results of measurements and tests carried out beforehand.
  • the heat flow extracted by an area of the ingot mold is distributed between the different elementary slices of the cast product contained in this area; this distribution is made, in each zone, in proportion to the lengths of the sections.
  • the machine for the continuous casting of steel shown schematically in FIG. 1 essentially comprises an ingot mold 10, a corset of guide rollers 12, straightening rollers 14 and a cooling device comprising nozzles or spray or atomization booms grouped by section, all the nozzles or booms of the same section being connected in parallel on a supply pipe fitted with a valve 16, the opening of which is controlled by a regulator 18 to maintain the supply flow rate equal to a set flow rate set by a computer 20.
  • the nozzles or booms are distributed all around the casting bar or, in the case of a rectangular section bar, only on its large faces. Means are provided for manually adjusting the distribution between the different nozzles or ramps of a section, followed the position of the total water flow supplying this section.
  • thermometric rod 22 for measuring the temperature of the molten metal in the distributor 24
  • thermometric probes 26 for measuring the temperature of the water of cooling of the ingot mold, at its inlet and outlet
  • flow meter 28 for measuring the flow rate of the cooling water of the ingot mold
  • pulse generator 30 for measuring the extraction speed of the bar and the calculation of the age of the elements of the bar
  • pyrometer 32 for the measurement of the surface temperature of the bar in the vicinity of the straightening point, etc.
  • the latter determines at regular intervals the set values of the water supply flow rates of the various sections of the cooling device.
  • This regular time interval is for example between 1 and 50 s.
  • This calculation is carried out periodically, for example every 10 s, and the bar is divided into elements the length of which is that of the slice poured during the time interval between two successive calculations.
  • the serial number assigned to each section from its production therefore makes it possible at any time to know its age and its position in the machine.
  • the set values of the supply water flow rates of the different sections of the cooling zone are calculated by integration. Cool and the calculated values are transmitted to the respective controllers 18.
  • the total water flow rate of the secondary cooling zone is calculated and deduces the total air flow to be used, using an equation or a curve establishing a relationship between these two flows.
  • Means are provided for manually adjusting the distribution between the different sections of the total air flow supplying the secondary cooling zone.
  • the computer 20 determines from the values of the flow rate and the temperatures at the inlet and at the outlet of the cooling water of the ingot mold, measured continuously by probes 26 and the flow meter 28, or from a file of values established using forecast simulation calculations, the overall amount of heat extracted in the mold during the time period separating two calculations. Using a distribution curve of the heat flows extracted along the mold, we then determine the amount of heat extracted from each elementary slice in the mold during the period considered and we calculate the amount of heat extracted from a mass unit of each slice. In fig.

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

Description

L'invention concerne un procédé de refroidissement conforme au préambule de la revendication. Un tel procédé est connu du document EP-A-0036342.The invention relates to a cooling method according to the preamble of the claim. Such a method is known from document EP-A-0036342.

Ce procédé permet de tenir compte dans le calcul des débits d'eau de la quantité de chaleur extraite en lingotière en décalant parallèlement à l'axe des temps la courbe C = f(t) de façon qu'elle passe par le point dont les coordonnées sont, d'une part, le temps de séjour total de la tranche considérée en lingotière et, d'autre part, la quantité de ohateur totale extraite de cette tranche pendant son séjour dans la lingotière. La correction de la courbe T = g(t), selon le procédé du document EP-A- 0036342, prend aussi en compte la quantité de chaleur extraite en lingotière lorsque la température superficielle du produit coulé à la sortie de la lingotière est calculée à partir de cette grandeur au moyen d'une courbe établie à l'aide de calculs prévisionnels de simulation. Pour déterminer les quantités de chaleur extraites en lingotière des différentes tranches du produit coulé, on mesure en continu le débit et l'échauffement de l'eau de refroidissement de la lingotière; on peut aussi les déterminer à partir de données stockées dans la mémoire du calculateur et établies par des essais et des calculs prévisionnels.This process allows the amount of heat extracted in the mold to be taken into account in the calculation of water flow rates by shifting parallel to the time axis the curve C = f (t) so that it passes through the point whose contact details are, on the one hand, the total residence time of the section considered in the ingot mold and, on the other hand, the total quantity of buyer extracted from this section during its stay in the ingot mold. The correction of the curve T = g (t), according to the process of document EP-A-0036342, also takes into account the quantity of heat extracted in the ingot mold when the surface temperature of the product poured at the outlet of the ingot mold is calculated at from this quantity by means of a curve established using forecast simulation calculations. To determine the quantities of heat extracted in the mold from the various slices of the cast product, the flow rate and the heating of the cooling water of the mold are continuously measured; they can also be determined from data stored in the computer memory and established by tests and predictive calculations.

On sait que pour différentes raisons (influence de la poudre de lubrification, retrait du métal solidifié, etc.) la densité du flux de chaleur extraite par la lingotière est plus élevée dans sa partie supérieure que dans sa partie inférieure et, par conséquent, la mesure de la quantité de chaleur globale extraite par la lingotière ne fournit une information exacte sur la quantité de chaleur extraite d'une tranche quelconque que si tous les paramètres de la coulée et notamment le débit et la température de l'eau de refroidissement de la lingotière et la vitesse d'extraction restent constants pendant tout le séjour de la tranche considérée dans la lingotière. S'il n'en est pas ainsi, ce qui est généralement le cas, on obtient par cette méthode des informations inexactes sur les quantités de chaleur extraites en lingotière des différentes tranches du produit coulé et sur les températures superficielles du produit coulé à la sortie de la lingotière lorsque celles-ci sont calculées à partir de ces quantités de chaleur.It is known that for various reasons (influence of the lubrication powder, removal of the solidified metal, etc.) the density of the heat flow extracted by the ingot mold is higher in its upper part than in its lower part and, consequently, the measurement of the quantity of overall heat extracted by the ingot mold provides exact information on the quantity of heat extracted from any slice only if all the parameters of the casting and in particular the flow rate and the temperature of the cooling water of the ingot mold and the extraction speed remain constant during the entire stay of the section considered in the ingot mold. If this is not the case, which is generally the case, this method gives inaccurate information on the quantities of heat extracted in the mold from the different slices of the cast product and on the surface temperatures of the product cast at the outlet. of the mold when these are calculated from these amounts of heat.

Le but de la présente invention est d'apporter au procédé du document EP-A0036342 un perfectionnement permettant de déterminer avec plus de précision l'histoire thermique de chaque tranche élémentaire du produit coulé lors de son passage dans la lingotière en tenant compte de l'évolution du flux de chaleur extrait du haut au bas de la lingotière.The object of the present invention is to provide the process of document EP-A0036342 with an improvement making it possible to determine more precisely the thermal history of each elementary slice of the product poured during its passage through the ingot mold, taking account of the evolution of the heat flow extracted from the top to the bottom of the mold.

Le procédé objet de la présente invention est caractérisé en ce que pour déterminer la quantité de chaleur extraite de chaque tranche pendant son séjour dans la lingotière, on détermine, à intervalles de temps réguliers, la quantité de chaleur globale extraite de la lingotière pendant cet intervalle de temps, on attribue à chaque tranche se trouvant dans la lingotière pendant cet intervalle de temps une fraction de cette quantité de chaleur globale qui est fonction de la distance de la tranche à la surface libre du métal dans la lingotière et lorsqu'une tranche sort de la lingotière on fait la somme de toutes les quantités de chaleur fractionnelles qui lui ont été attribuées pendant son séjour dans la lingotière.The process which is the subject of the present invention is characterized in that in order to determine the quantity of heat extracted from each slice during its stay in the ingot mold, the quantity of overall heat extracted from the ingot mold during this interval is determined at regular time intervals. of time, each slice in the ingot mold is allocated during this time interval a fraction of this total amount of heat which is a function of the distance of the slice to the free surface of the metal in the ingot mold and when a slice comes out from the ingot mold we add up all the amounts of fractional heat which have been allocated to it during its stay in the ingot mold.

La loi de répartition, en fonction de la distance de la surface libre du métal, de la quantité de chaleur globale extraite dans la lingotière est déduite de mesures expérimentales.The distribution law, as a function of the distance from the free surface of the metal, of the quantity of global heat extracted in the ingot mold is deduced from experimental measurements.

On peut, en particulier, décomposer la partie utile de la lingotière en plusieurs zones et répartir le flux global de chaleur extrait par la lingotière entre ces différentes zones. Dans ce cas le nombre de zones est compris par exemple entre 2 et 20. Le nombre et les longueurs de ces zones et la répartition du flux de chaleur global entre ces différentes zones sont définis en tenant compte de l'évolution de l'efficacité thermique du haut au bas de la lingotière et déduites des résultats de mesures et d'essais effectués au préalable. A chaque calcul, on répartit le flux de chaleur extrait par une zone de la lingotière entre les différentes tranches élémentaires du produit coulé contenues dans cette zone; cette répartition est effectuée, dans chaque zone, proportionnellement aux longueurs des tranches.One can, in particular, decompose the useful part of the ingot mold into several zones and distribute the overall flow of heat extracted by the ingot mold between these different zones. In this case the number of zones is for example between 2 and 20. The number and the lengths of these zones and the distribution of the overall heat flow between these different zones are defined taking into account the evolution of thermal efficiency from top to bottom of the mold and deducted from the results of measurements and tests carried out beforehand. At each calculation, the heat flow extracted by an area of the ingot mold is distributed between the different elementary slices of the cast product contained in this area; this distribution is made, in each zone, in proportion to the lengths of the sections.

La description qui suit se réfère aux dessins l'accompagnant qui illustrent le procédé de l'invention et sur lesquels:

  • la fig. 1 est le schéma d'une installation de coulée continue courbe et du système de contrôle de refroidissement de la barre coulée conforme à l'invention;
  • la fig. 2 est une courbe T = g(t) représentant les variations en fonction du temps de la température superficielle de la barre pendant son déplacement dans la machine de coulée;
  • la fig. 3 est une courbe C = f(t) représentant les variations du temps de la quantité de chaleur extraite d'une masse unitaire du produit coulé pendant son déplacement dans la machine de coulée depuis la surface libre du métal dans la lingotière, et
  • la fig. 4 est une courbe de répartition du flux de chaleur extrait en lingotière.
The description which follows refers to the accompanying drawings which illustrate the process of the invention and in which:
  • fig. 1 is a diagram of a curved continuous casting installation and of the cooling bar cooling control system according to the invention;
  • fig. 2 is a curve T = g (t) representing the variations as a function of time of the surface temperature of the bar during its movement in the casting machine;
  • fig. 3 is a curve C = f (t) representing the variations in time of the quantity of heat extracted from a unit mass of the product cast during its movement in the casting machine from the free surface of the metal in the ingot mold, and
  • fig. 4 is a distribution curve of the heat flow extracted in an ingot mold.

La machine pour la coulée continue de l'acier représentée schématiquement sur la fig. 1 comporte essentiellement une lingotière 10, un corset de rouleaux de guidage 12, des rouleaux redresseurs 14 et un dispositif de refroidissement comportant des buses ou des rampes de pulvérisation ou d'atomisation groupées par section, toutes les buses ou rampes d'une même section étant branchées en parallèle sur une tuyauterie d'alimentation munie d'une vanne 16 dont l'ouverture est commandée par un régulateur 18 pour maintenir le débit d'alimentation égal à un débit de consigne fixé par un calculateur 20. Les buses ou rampes sont réparties tout autour de la barre coulée ou, s'il s'agit d'une barre à section rectangulaire, seulement sur ses grandes faces. Des moyens sont prévus pour régler manuellement la répartition entre les différentes buses ou rampes d'une section, suivant leur position, du débit total d'eau alimentant cette section.The machine for the continuous casting of steel shown schematically in FIG. 1 essentially comprises an ingot mold 10, a corset of guide rollers 12, straightening rollers 14 and a cooling device comprising nozzles or spray or atomization booms grouped by section, all the nozzles or booms of the same section being connected in parallel on a supply pipe fitted with a valve 16, the opening of which is controlled by a regulator 18 to maintain the supply flow rate equal to a set flow rate set by a computer 20. The nozzles or booms are distributed all around the casting bar or, in the case of a rectangular section bar, only on its large faces. Means are provided for manually adjusting the distribution between the different nozzles or ramps of a section, followed the position of the total water flow supplying this section.

La machine est équipée de différents dispositifs de mesure dont les informations sont transmises au calculateur 20: canne thermométrique 22 pour la mesure de la température du métal en fusion dans le répartiteur 24, sondes thermométriques 26 pour la mesure de la température de l'eau de refroidissement de la lingotière, à l'entrée et à la sortie de celle-ci, débitmètre 28 pour la mesure du débit de l'eau de refroidissement de la lingotière, générateur d'impulsions 30 pour la mesure de la vitesse d'extraction de la barre et le calcul de l'âge des éléments de la barre, pyromètre 32 pour la mesure de la température superficielle de la barre au voisinage du point de redressement, etc.The machine is equipped with various measuring devices, the information of which is transmitted to the computer 20: thermometric rod 22 for measuring the temperature of the molten metal in the distributor 24, thermometric probes 26 for measuring the temperature of the water of cooling of the ingot mold, at its inlet and outlet, flow meter 28 for measuring the flow rate of the cooling water of the ingot mold, pulse generator 30 for measuring the extraction speed of the bar and the calculation of the age of the elements of the bar, pyrometer 32 for the measurement of the surface temperature of the bar in the vicinity of the straightening point, etc.

A partir de ces informations et de données stockées en mémoire dans le calculateur, ce dernier détermine à intervalles réguliers les valeurs de consigne des débits d'alimentation en eau des différentes sections du dispositif de refroidissement. Cet intervalle régulier de temps est compris par exemple entre 1 et 50 s.From this information and data stored in memory in the computer, the latter determines at regular intervals the set values of the water supply flow rates of the various sections of the cooling device. This regular time interval is for example between 1 and 50 s.

Le principe de contrôle du refroidissement selon le procédé du document EP-A-0036342 est de maintenir dans le temps l'évolution de la solidification de la barre quel que soit le régime de fonctionnement de la machine de coulée. Pour cela, on impose une loi de variation C = f(t) de la quantité de chaleur extraite par kilo d'acier en fonction du temps de séjour dans la machine (fig. 3) à laquelle est associée une loi de variation T = g (t) de la température superficielle de la barre en fonction du temps de séjour dans la machine (fig. 2). Ces lois dépendent essentiellement de la nuance de l'acier, du format de la barre et de la vitesse d'extraction. En pratique, pour un format de barre donné, on groupera les nuances d'acier et les vitesses d'extraction en différentes classes.The principle of controlling the cooling according to the process of document EP-A-0036342 is to maintain over time the evolution of the solidification of the bar whatever the operating regime of the casting machine. For this, we impose a law of variation C = f (t) of the quantity of heat extracted per kilo of steel as a function of the residence time in the machine (fig. 3) to which is associated a law of variation T = g (t) of the surface temperature of the bar as a function of the residence time in the machine (fig. 2). These laws essentially depend on the grade of steel, the size of the bar and the speed of extraction. In practice, for a given bar format, steel grades and extraction speeds will be grouped into different classes.

Toutes ces courbes sont définies par des équations paramétriques ou par des valeurs ponctuelles introduites en mémoire dans le calculateur. Les données sur la nuance d'acier et le format de la barre sont introduites dans le calculateur, avant chaque coulée, pour lui permettre de sélectionner le jeu de courbes correspondantes. La vitesse d'extraction est mesurée en permanence au moyen du générateur d'impulsions 30 et le calculateur choisit à chaque instant le jeu de courbes correspondant à la vitesse moyenne déduite de ces mesures.All these curves are defined by parametric equations or by point values introduced into memory in the computer. Data on the steel grade and the format of the bar are entered into the computer, before each casting, to allow it to select the set of corresponding curves. The extraction speed is continuously measured by means of the pulse generator 30 and the computer chooses at each instant the set of curves corresponding to the average speed deduced from these measurements.

A partir du jeu de courbes sélectionné, le calculateur peut, à chaque instant, calculer le coefficient d'échange thermique superficiel K pour chaque élément de la barre à partir de C et T et en déduire le débit d'eau spécifique q devant être projeté sur l'unité de surface de l'élément considéré à l'aide d'une courbe K = h (q) stockée dans la mémoire du calculateur; cette courbe peut être unique pour l'ensemble de la zone de refroidissement ou être formée de plusieurs segments de courbe distincts valables dans les différentes sections de la zone.From the selected set of curves, the computer can, at any time, calculate the surface heat exchange coefficient K for each element of the bar from C and T and deduce the specific water flow q to be projected on the unit of area of the element considered using a curve K = h (q) stored in the memory of the computer; this curve can be unique for the entire cooling zone or be formed by several distinct curve segments valid in the different sections of the zone.

Ce calcul est effectué périodiquement, par exemple toutes les 10 s, et la barre est divisée en éléments dont la longueur est celle de la tranche coulée pendant l'intervalle de temps entre deux calculs successifs. Le numéro d'ordre affecté à chaque tranche dès sa production permet donc à tout instant de connaître son âge et sa position dans la machine.This calculation is carried out periodically, for example every 10 s, and the bar is divided into elements the length of which is that of the slice poured during the time interval between two successive calculations. The serial number assigned to each section from its production therefore makes it possible at any time to know its age and its position in the machine.

Connaissant le débit d'eau spécifique q pour chaque tranche élémentaire on peut calculer le débit d'eau Q = q x S à projeter sur la surface latérale S de la tranche.Knowing the specific water flow q for each elementary section, we can calculate the water flow Q = q x S to be projected on the lateral surface S of the section.

Après avoir calculé les débits d'eau à projeter sur chaque tranche de barre se trouvant à un instant donné dans la zone de refroidissement, on calcule par intégration les valeurs de consigne des débits d'eau d'alimentation des différentes sections de la zone de refroidissement et les valeurs calculées sont transmises aux régulateurs respectifs 18.After calculating the water flow rates to be projected on each bar slice located at a given time in the cooling zone, the set values of the supply water flow rates of the different sections of the cooling zone are calculated by integration. cooling and the calculated values are transmitted to the respective controllers 18.

Dans le cas où on utilise des buses ou rampes d'atomisation dans lesquelles les jets d'eau sont divisés en très fines gouttelettes au moyen d'air comprimé, on calcule le débit d'eau total de la zone de refroidissement secondaire et on en déduit le débit d'air total à utiliser, à l'aide d'une équation ou une courbe établissant une relation entre ces deux débits. Des moyens sont prévus pour régler manuellement la répartition entre les différentes sections du débit total d'air alimentant la zone de refroidissement secondaire.In the case where nozzles or atomizing booms are used in which the water jets are divided into very fine droplets by means of compressed air, the total water flow rate of the secondary cooling zone is calculated and deduces the total air flow to be used, using an equation or a curve establishing a relationship between these two flows. Means are provided for manually adjusting the distribution between the different sections of the total air flow supplying the secondary cooling zone.

Pour déterminer la quantité de chaleur à extraire de chaque tranche élémentaire de la barre dans la zone de refroidissement secondaire, il faut tenir compte de la quantité de chaleur réellement extraite en lingotière. Pour cela on utilise une courbe de base C = f(t) (en trait plein sur la fig. 3) correspondant aux conditions de fonctionnement (nuance de l'acier, format de la barre, vitesse d'extraction) que l'on décale parallèlement à l'axe des temps pour la faire passer par le point A dont les coordonnées sont égales, respectivement, au temps de séjour total du produit coûté en lingotière t, et à la quantité de chaleur C1 effectivement extraite en lingotière; cette nouvelle courbe de formule générale C = f(t-a) est représentée en traits interrompus sur la fig. 3.To determine the amount of heat to be extracted from each elementary slice of the bar in the secondary cooling zone, it is necessary to take into account the amount of heat actually extracted in the mold. For this we use a basic curve C = f (t) (in solid lines in Fig. 3) corresponding to the operating conditions (steel grade, bar format, extraction speed) that we shifts parallel to the time axis to pass it through point A whose coordinates are equal, respectively, to the total residence time of the product cost in the ingot mold t, and to the quantity of heat C 1 actually extracted in the ingot mold; this new curve of general formula C = f (ta) is shown in broken lines in FIG. 3.

La température superficielle de la barre à la sortie de la lingotière est calculée pour chaque tranche à partir d'une courbe établie à l'aide de calculs prévisionnels de simulation et donnant l'évolution de cette température en fonction de la quantité de chaleur extraite en lingotière. Si cette température T', est différente de la température théorique T fournie par la courbe T = g(t) (en trait plein sur la fig. 2) correspondant aux conditions de marche de la machine, le calculateur corrigera le débit de cette courbe en admettant, par exemple, une variation linéaire de la température depuis la sortie de la lingotière (point d'abcisse t, ) jusqu'à un point prédéterminé de la partie supérieure de la zone de refroidissement (courbe en trait interrompu sur la fig. 2), de façon à retrouver en ce point la température théorique. C'est cette courbe corrigée que le calculateur utilisera pendant tout le séjour de la tranche considérée dans la zone de refroidissement secondaire pour déterminer la température superficielle entrant dans le calcul des valeurs de consigne des débits d'eau.The surface temperature of the bar at the outlet of the ingot mold is calculated for each slice from a curve established using forecast simulation calculations and giving the evolution of this temperature as a function of the amount of heat extracted in ingot mold. If this temperature T ', is different from the theoretical temperature T provided by the curve T = g (t) (in solid lines in fig. 2) corresponding to the operating conditions of the machine, the computer will correct the flow rate of this curve assuming, for example, a linear variation in temperature from the outlet of the mold (abscissa point t,) to a predetermined point in the upper part of the cooling zone (dashed line in fig. 2), so as to find the theoretical temperature at this point. It is this corrected curve that the computer will use during the entire stay of the section considered in the secondary cooling zone to determine the surface temperature entering into the calculation of the set values for the water flow rates.

A chaque pas de calcul, le calculateur 20 détermine à partir des valeurs du débit et des températures à l'entrée et à la sortie de l'eau de refroidissement de la lingotière, mesurées en continu par des sondes 26 et le débitmètre 28, ou à partir d'un fichier de valeurs établies à l'aide de calculs prévisionnels de simulation, la quantité globale de chaleur extraite en lingotière pendant la période de temps séparant deux calculs. En utilisant une courbe de répartition des flux de chaleur extraits le long de la lingotière, on détermine ensuite la quantité de chaleur extraite de chaque tranche élémentaire se trouvant dans la lingotière pendant la période considérée et on calcule la quantité de chaleur extraite d'une masse unitaire de chaque tranche. Sur la fig. 4 on a représenté deux courbes donnant les variations du flux de chaleur ϕ extrait du métal contenu dans une lingotière, à travers la paroi de celle-ci, en fonction de la distance I à la surface libre du métal et pouvant être utilisées, comme décrit ci-dessus, pour la mise en oeuvre de l'invention. En réalité, le flux de chaleur extrait varie de façon continue d'une extrémité à l'autre de la partie utile de la lingotière, comme représenté par la courbe en trait plein de la fig. 4. En pratique, on peut utiliser une courbe donnant une représentation approchée de la loi de répartition du flux (courbe en tirets sur la fig. 4) en décomposant la partie utile de la lingotière en plusieurs zones (quatre dans l'exemple illustré) et en admettant que le flux de chaleur conserve une valeur constante dans chacune de ces zones.At each calculation step, the computer 20 determines from the values of the flow rate and the temperatures at the inlet and at the outlet of the cooling water of the ingot mold, measured continuously by probes 26 and the flow meter 28, or from a file of values established using forecast simulation calculations, the overall amount of heat extracted in the mold during the time period separating two calculations. Using a distribution curve of the heat flows extracted along the mold, we then determine the amount of heat extracted from each elementary slice in the mold during the period considered and we calculate the amount of heat extracted from a mass unit of each slice. In fig. 4 there are shown two curves giving the variations of the heat flow ϕ extracted from the metal contained in an ingot mold, through the wall thereof, as a function of the distance I to the free surface of the metal and which can be used, as described above, for the implementation of the invention. In reality, the heat flow extracted varies continuously from one end to the other of the useful part of the ingot mold, as represented by the curve in solid lines in FIG. 4. In practice, we can use a curve giving an approximate representation of the law of distribution of the flow (dashed curve in fig. 4) by breaking down the useful part of the mold into several zones (four in the illustrated example) and assuming that the heat flow maintains a constant value in each of these zones.

A chaque pas de calcul, on étudie plus particulièrement la tranche élémentaire de barre située à la sortie de la lingotière et on calcule pour cette tranche l'âge t1 et la quantité de chaleur Ci extraite d'une masse unitaire pendant son séjour dans la lingotière puis sa température superficielle r,. Ce sont ces valeurs qui sont utilisées ensuite, à chaque calcul, pour décaler la courbe C = f(t) et corriger la courbe T = g(t) comme décrit ci-dessus.At each calculation step, we study more particularly the elementary slice of bar located at the outlet of the ingot mold and we calculate for this slice the age t 1 and the quantity of heat Ci extracted from a unit mass during its stay in the ingot mold and then its surface temperature r ,. These are the values which are then used, at each calculation, to shift the curve C = f (t) and correct the curve T = g (t) as described above.

Ce perfectionnement au procédé du document EP-A-0036342 permet de déterminer avec plus de précision la quantité de chaleur extraite en lingotière de chaque tranche élémentaire et, par conséquent, d'améliorer le contrôle du refroidissement.This improvement to the process of document EP-A-0036342 makes it possible to more precisely determine the quantity of heat extracted in the mold from each elementary wafer and, consequently, to improve the cooling control.

Claims (1)

  1. Process for cooling an ingot in a continuous casting plant according to which the ingot is divided into fictitious elements and the water flowrate to be sprayed on each element is periodically determined as a function of its age and by taking into account the quantity of heat extracted from this element during its dwell time in the mould, characterized by the steps of, in order to determine the quantity of heat extracted from each element during its dwell time in the mould, determining at regular time intervals the total quantity of heat extracted from the mould during this time interval, allocating to each element present in the mould during this time interval a fraction of this total quantity of heat which depends on the distance (I) of the element from the free surface of the metal in the mould and, when a portion emerges from the mould, summing up all the fractions of quantities of heat which have been allocated to this portion during its dwell time in the mould.
EP82401769A 1981-10-02 1982-09-29 Process for cooling of the cast product in a continuous-casting plant Expired EP0076743B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8118587A FR2513912A2 (en) 1981-10-02 1981-10-02 METHOD FOR CONTROLLING THE COOLING OF THE COLORED PRODUCT IN A CONTINUOUS CASTING PLANT
FR8118587 1981-10-02

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EP0076743A1 EP0076743A1 (en) 1983-04-13
EP0076743B1 true EP0076743B1 (en) 1985-08-14

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FR2569361B1 (en) * 1984-08-24 1987-02-27 Fives Cail Babcock METHOD FOR ADJUSTING THE INCLINATION OF THE SMALL SIDES OF A SLABS CONTINUOUS LINGOTIERE
DE102008004911A1 (en) * 2008-01-18 2009-07-23 Sms Demag Ag Method for controlling the secondary cooling of continuous casting plants

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EP0036342A1 (en) * 1980-03-13 1981-09-23 FIVES-CAIL BABCOCK, Société anonyme Process for controlling the cooling of an ingot in a continuous-casting plant

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CH552423A (en) * 1972-04-18 1974-08-15 Concast Ag METHOD AND DEVICE FOR CONTROLLING HEAT EXTRACTION IN KOKILLEN DURING CONTINUOUS CASTING.
US4235276A (en) * 1979-04-16 1980-11-25 Bethlehem Steel Corporation Method and apparatus for controlling caster heat removal by varying casting speed

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0036342A1 (en) * 1980-03-13 1981-09-23 FIVES-CAIL BABCOCK, Société anonyme Process for controlling the cooling of an ingot in a continuous-casting plant

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FR2513912A2 (en) 1983-04-08
JPS58125351A (en) 1983-07-26
DE3265439D1 (en) 1985-09-19
EP0076743A1 (en) 1983-04-13
JPS6349589B2 (en) 1988-10-05
FR2513912B2 (en) 1984-02-03

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