EP1272298A1 - Method and device for controlling metal liquid level in a continuous casting machine - Google Patents

Method and device for controlling metal liquid level in a continuous casting machine

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Publication number
EP1272298A1
EP1272298A1 EP01921445A EP01921445A EP1272298A1 EP 1272298 A1 EP1272298 A1 EP 1272298A1 EP 01921445 A EP01921445 A EP 01921445A EP 01921445 A EP01921445 A EP 01921445A EP 1272298 A1 EP1272298 A1 EP 1272298A1
Authority
EP
European Patent Office
Prior art keywords
liquid metal
height
plunger
metal
continuous casting
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.)
Withdrawn
Application number
EP01921445A
Other languages
German (de)
French (fr)
Inventor
Jacques Griffon
Claude Breysse
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.)
Constellium Issoire SAS
Original Assignee
Pechiney Rhenalu SAS
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Pechiney Rhenalu SAS filed Critical Pechiney Rhenalu SAS
Publication of EP1272298A1 publication Critical patent/EP1272298A1/en
Withdrawn legal-status Critical Current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
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0637—Accessories therefor
    • B22D11/064—Accessories therefor for supplying molten metal
    • 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
    • B22D11/18—Controlling or regulating processes or operations for pouring
    • B22D11/181—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level

Definitions

  • the invention relates to the continuous casting of metal strip, in particular of aluminum or aluminum alloy strip.
  • a machine (1) for continuous casting of metal strip (3) generally contains at least two identical cylinders (1 A and IB) located face to face and a device for injection (6) comprising a tundish (24) and an injector (23).
  • the cylinders are separated by a space (or air gap) E substantially equal to the thickness of the metal strip to be produced and rotating in opposite directions to one another.
  • the metal (2) is supplied, in the liquid state, to one side of the space, using the injection device (6), solidifies on contact with the cylinders and leaves in the solid state, on the other side of the air gap, in the form of a strip (3) having a nominal thickness Eo.
  • the metal solidifies between the two cylinders, at what is known as the solidification front (5). With such a device, bands ranging from a few centimeters thick to a few millimeters or less can be produced.
  • the regularity of the thickness of the strip obtained in particular for small thicknesses, because this regularity determines the properties of use of the strip, in particular of its ability to be transformed.
  • Several factors are known to be responsible for the thickness fluctuations, which fluctuations consist essentially of variations and irregularities.
  • fluctuations in the level of the liquid metal contained in the injection device generate fluctuations in the thickness of the strip.
  • the height of the sheet of metal contained in the injection device is of the order of 40 to 50 mm.
  • the injection device (6) is supplied using a chute (7) provided with means (16, 17) for regulating the flow of liquid metal poured into the casting tray (24).
  • the feed chute (7) is supplied with liquid metal (8) by a holding furnace (which is not illustrated).
  • a float / shutter (16) covers an opening (17) arranged at the end of the feed chute (7) and cooperates with it so as to allow a flow of liquid metal whose flow is function of the float / obturator (16).
  • the latter floats on the surface of the liquid metal (2), follows the variations in the height H of this metal and limits the flow of metal (18) as a function of the height of the metal level.
  • the level of liquid metal is then regulated purely mechanically. With such a device, for a typical flow rate of 3 tonnes / hour, the height fluctuations of the metal level are at best of the order of ⁇ 1 mm.
  • the injection device (6) is supplied using a feed chute (7) provided with means (9-15) for regulating the flow of liquid metal poured into the injection device according to a measured height.
  • the regulation means (9-15) comprise a metal level sensor (11), which is typically a capacitive sensor, an electronic regulation circuit (10) comprising a detection circuit (12) and a control circuit (13 ), an adjustable opening (9) arranged in the bottom of the feed chute (7).
  • the opening (9) can be closed in a controlled manner by a shutter means (15) moved vertically by an actuator (14) under the control of the circuit (13).
  • the Applicant has therefore sought solutions which make it possible to limit the fluctuations, that is to say the variations and irregularities, in the thickness of the metal strips obtained by continuous casting to values less than ⁇ 0.05 mm, while allowing large flows of liquid metal, namely flows of the order of 3 tonnes / h or more, and the production of strips of large width, namely of a width typically greater than 1 meter, or even greater than 2 meters.
  • the Applicant has found that the fluctuations in thickness of the strip coming from a continuous casting machine remain substantially the same, in absolute value, whatever the thickness of the strip. Under these conditions, a range of fluctuations which is tolerable for thick bands becomes unacceptable for bands of thin thickness.
  • the devices of the prior art make it possible to limit the amplitude of the thickness fluctuations at best to about ⁇ 0.05 mm whatever the thickness of the strip. For example, with the known devices, it is not possible to cast strips of a thickness less than 5 mm with a precision on the thickness better than ⁇ 1%.
  • the fluctuations are generally greater the greater the width of the strip.
  • the Applicant has had the idea of using Archimedes' thrust to vary the level of liquid metal contained in the injection device in a simple and controllable manner.
  • the displacement of a plunger in the liquid metal thus makes it possible to finely control the height of the liquid metal, and therefore the hydrostatic pressure which results therefrom, without intervening on the supply of liquid metal.
  • Liquid metal level and flow control can therefore be practically decoupled.
  • the invention has the advantage of separating the fine control of the level of liquid metal and the regulation of the supply of liquid metal.
  • liquid metal feed which mainly aims at controlling the flow rate of liquid metal feed.
  • the subject of the invention is a method for controlling the height H of liquid metal of an injection device of a machine for continuously casting metal strips, method in which: - a determined part P of at least is immersed a plunger in said liquid metal;
  • the, or at least one, plunger is moved in the liquid metal so as to modify the volume of the immersed part of the plunger, to cause a displacement of the level of the liquid metal under the effect of hydrostatic pressure and to modify the said height H.
  • the displacement of a plunger may consist in lowering it a little when the level of the liquid metal is too low and, conversely, raising it a little when the level is too high.
  • the required displacement can be determined by a simple algorithm which is based on the difference between a measured height H of liquid metal and a reference value Ho and which takes account of the geometry of the plunger (s) and of the device d 'injection.
  • the algorithm is typically an inverse function of the difference between the measured height H and the set height Ho (and more advantageously a function of the difference between the measured height Hc and a set height Hco).
  • the algorithm can be more elaborate and can be, for example, a PID (proportional-integral-differential) algorithm.
  • the invention also has the advantage of allowing precise control, that is to say an adjustment and / or regulation of the height of the liquid metal without significant modification of the hydrostatic pressure.
  • the nature of the material of which the plunger (s) is made plays little role in the precision of the process, this which is not the case for processes or devices based on the flotation of one of the control means.
  • the invention also relates to a device for controlling the height H of the liquid metal contained in an injection device of a continuous casting machine, capable of implementing the method of the invention.
  • the subject of the invention is also a process for the continuous casting of a metal strip, characterized in that the height H of the liquid metal contained in an injection device is controlled using the control process of the invention.
  • the invention also relates to a continuous casting machine for a metal strip, characterized in that it includes a device for controlling the height H of the liquid metal according to the invention.
  • the invention is particularly advantageous when the metal strips (3) have a width greater than or equal to approximately 1000 mm, or even greater than or equal to approximately 2000 mm.
  • FIG. 1 shows schematically the basic elements of a continuous casting machine.
  • FIG. 2 represents two devices of the prior art which make it possible to control the flow of metal and the height H of the level of liquid metal in an injection device.
  • FIG. 3 illustrates the operating principle of the method for controlling the level of liquid metal according to the invention.
  • FIG. 4 schematically illustrates a first device of the invention.
  • FIG. 5 schematically illustrates a second device according to the invention.
  • FIG. 6 represents an embodiment of the device according to the invention.
  • the method for controlling the height H of liquid metal (2) of an injection device (6) of a continuous casting machine (1) of metal strips (3) according to the invention is characterized in that:
  • the (at least one or each) plunger (30) is moved in the liquid metal (2) so as to modify the volume of the submerged part P of the plunger, to cause a displacement of the level (20) of the liquid metal (2 ) under the effect of hydrostatic pressure and to modify said height H.
  • the injection device (6) comprises a feed opening (19) and an outlet opening (21) having a width substantially equal to that of the strip (3) to be produced.
  • the injector (6) is supplied with liquid metal using a chute (7), which pours liquid metal (8) into the casting tank (24) through the feed opening (19).
  • the metal strip (3) leaves the air gap E in a direction (22) substantially horizontal or slightly inclined relative to the horizontal.
  • the plunger (30) is immersed in the liquid metal (2) contained in the casting tank (24), which is integral with the injector (23), so that the control of the level of liquid metal takes place directly in the injection device (6) (and not in the feed chute or more upstream, which makes it possible to decouple the flow control and the metal level control).
  • the invention is particularly suitable for cases where the height Hc of metal between the center of the injector and the free surface of the molten metal in the tundish is small compared to the width of the strip (Hc is typically between 5 and 50 mm while the width is typically greater than about 1000 mm).
  • the (at least one or each) plunger is moved as a function of a measured value of the level (20) of the liquid metal. More specifically, the method of the invention is characterized in that:
  • the measured height H is compared to the set value Ho in order to determine the displacement of the plunger (s).
  • the measured height H is compared to the set value Ho and the plunger is moved in inverse function to the difference between the measured height H and the set height Ho.
  • the displacement of the plunger (s) (30) may include additional immersion and emersion operations. For example :
  • - a determined complementary part ⁇ P + of the (at least one or each) plunger (30) is immersed when H ⁇ Ho, so as to raise the level (20) of the liquid metal (2) and to increase said height H ;
  • - a determined part ⁇ P- is made to emerge from (at least one or each) plunger (30) when H> Ho, so as to lower the level (20) of the liquid metal (2) and to reduce said height H.
  • the partial immersion or emersion of the plunger makes it possible to vary the height so as to correct the differences between the measured value H and the reference value Ho.
  • Said determined quantities ⁇ P + and ⁇ P-, for the lowering or raising of, or each, plunger (30) typically depend on the difference between H and Ho, the shape of the plunger (s) (30) and the shape of the device injection (6).
  • These quantities can be determined by geometric calculation, for example using a simple algorithm based on the difference between H and Ho (and therefore based on the volumes of metal to be moved) and taking into account the geometry of (the ) plunger (s) and injection device.
  • ⁇ P + and ⁇ P- can be given by the volume Vm of metal respectively below and above the setpoint level, corresponding to the difference between the actual volume of liquid metal and the volume delimited by the setpoint level, the internal surface of the tundish and the solidification front.
  • the volume Vm is approximately equal to the product of the area of the free surface (20) of the liquid metal (2) and the difference between the set height Ho and the measured height H.
  • the plunger (s) (30) may (may) have any shape, such as a cylindrical or conical shape.
  • the shape and surface area of the plunger (s) are adjusted to ensure the required precision (when a plunger is submerged to its reference depth).
  • At least one plunger is of cylindrical shape of circular section S and the main axis of which is perpendicular to the free surface (20) of the liquid metal (2), in which case the (or each) plunger can be moved vertically d 'a distance ⁇ X approximately equal to (H - Ho) x So / S, where So is the area of the free surface (20) of the liquid metal (2) contained in the injection device (6). If H is less than Ho, then ⁇ H is negative and the plunger can be lowered; if H is greater than Ho, then ⁇ H is positive and the plunger can be raised.
  • the height H of liquid metal is generally given relative to the bottom of the injection device (6), and preferably relative to the center of the injector (23).
  • the plunger (s) is (are) preferably made of a refractory material, inert with respect to the liquid metal, such as a ceramic, so as to be able to remain immersed for a long time (s) in liquid metal without risk of degradation or pollution.
  • the material is preferably non-porous, so as to limit pollution of the liquid metal, in particular during alloy changes.
  • the volume V of the plunger (s) (30) is approximately at least equal to the product of the area of the free surface (20) of the liquid metal (2) and the maximum variations in height to be corrected.
  • a diver whose volume is at least equal to 2 x 0.6 mm x 20,000 cm 2 must be provided 2400 cm. This corresponds, for example, to a plunger of cylindrical shape with a height of about 40 mm and a diameter of about 140 mm.
  • the injection device (6) is supplied with liquid metal (2), typically using a chute (7).
  • the control method of the invention can be combined with a method of controlling the supply of liquid metal (2) to the injection device (6).
  • the control method according to the invention then provides precise regulation and adjustment of the height of the liquid metal which completes the rough control of the height of the metal provided by the feed control method.
  • the control method according to the invention can be included in a control method of the continuous casting machine (1).
  • the invention also relates to a device (40) for controlling the height H of the liquid metal (2) contained in an injection device (6) of a continuous casting machine (1), capable of implementing the method of the invention.
  • This device comprises at least one plunger (30) and means (41, 31, 32) for modifying the position of the (or each) plunger (30).
  • the device also comprises means (11, 12) for detecting the height H of the liquid metal (2).
  • the means (11, 12) for detecting the height H of the liquid metal (2) comprises a metal level sensor (11), which is typically a capacitive sensor, and a detection circuit (12), which can translate, if necessary, the sensor signal into a determined signal representative of the actual height of the liquid metal (2).
  • Figure 4 illustrates such a device.
  • the means (41, 31, 32) for modifying the position of the plunger (s) (30) may typically comprise a control circuit (41), an actuator (32) and a fixing and support means (31 ) of the diver (s) (30).
  • the actuator makes it possible to immerse a determined part of the plunger (s) (30) in the liquid metal (2) and to move it, typically from bottom to top, and vice versa, i.e. lower it by a determined quantity ⁇ X- when H ⁇ Ho, so as to raise the level of liquid metal and raise it by a determined quantity ⁇ X + when H> Ho, so as to lower the level of liquid metal .
  • the control circuit (41) which is typically connected directly to the detection circuit (12), controls the actuator (32) according to the movements of the plunger (s) (30) required to correct the height H of the liquid metal (2).
  • These means can be easily automated or controlled by computer.
  • the control circuit (41) makes it possible to compare the measured height H, known by the signal from the detection circuit (12), with the set height Ho.
  • the height control device (40) is associated with a device for controlling the supply of liquid metal (50), as illustrated for example in FIG. 5.
  • the device control (40) then ensures regulation and precise adjustment of the height of the liquid metal which completes the rough control of the height of the metal provided by the device (50).
  • the device according to the invention can also be included in a device for controlling the continuous casting machine (1).
  • the control device (50) comprises, for example, a feed chute (7) provided with means (9, 11-15) for controlling the flow of liquid metal poured into the injection device (6).
  • the control means (9, 11-15) comprise a metal level sensor (11), which is typically a capacitive sensor, an electronic control circuit comprising a detection circuit (12) and a control circuit (13) , an adjustable opening (9) closed in a controlled manner by means (15), which is actuated by the means (14) under the control of the circuit (13).
  • the level sensor (11) and the detection circuit (12) are advantageously common to the device for controlling the height of the liquid metal according to the invention and to the device for controlling the metal supply liquid.
  • the invention also relates to the use of at least one plunger (30) to control the height of the liquid metal contained in a liquid metal supply device, such as an injection device.
  • the subject of the invention is also a process for the continuous casting of a metal strip (3) in which an injection device (6) is supplied with liquid metal (2), characterized in that the height H of the liquid metal (2) contained in the injection device (6) using the control method of the invention.
  • the supply rate of the injection device (6) in liquid metal (2) can also be regulated.
  • Said metal strip typically has a width greater than or equal to approximately 1000 mm, or even greater than or equal to approximately 2000 mm.
  • Said strip is typically made of aluminum or an aluminum alloy.
  • the invention also relates to a continuous casting machine (1) for a metal strip (3) comprising an injection device (6) and characterized in that it comprises a height control device (40) H of the liquid metal (2) contained in the injection device (6) according to the invention.
  • the continuous casting machine according to the invention is also characterized in that it is capable of allowing the casting of strips having a width greater than or equal to approximately 1000 mm, or even greater than or equal to approximately 2000 mm.
  • the invention is suitable for the continuous casting of strips of aluminum or aluminum alloy, but can be applied to the continuous casting of any liquid metal.
  • FIG. 6 represents a possible embodiment of the mechanical part (30, 31, 32) of the device according to the invention.
  • This comprises a plunger (30), a rod (31) for supporting the plunger and an actuator (32).
  • the actuator (32) comprises a metal bar (33), preferably substantially horizontal, which is fixed to a support (39), so that it can pivot freely around an axis (35), and is provided with a counterweight (36).
  • the actuator (32) further comprises a cam (37) of substantially spiral shape (close to a spiral) whose radius increases regularly from a minimum value RI to a maximum value R2 over an angle ⁇ .
  • the cam (37) bears against the bar (33), preferably on the side of the counterweight (36).
  • the pivoting of the cam (37) around an axis (38) using, for example, a stepping motor, makes it possible to pivot the bar (33) around the axis (35 ) in a controlled manner.
  • the pivoting of the bar (33) causes movements from top to bottom, or from bottom to top, of the plunger (30).
  • the stroke C of these movements is linked to the difference between RI and R2, the support distance D and the distance between axes E.
  • D / E 1.25

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
  • Continuous Casting (AREA)

Abstract

The invention concerns the control of height H of liquid metal (2) in an injecting device (6) of a continuous casting machine. The method is characterised in that it consists in immersing a specific part P of a plunger into said liquid metal and moving the plunger in the liquid metal, so as to modify the volume of the immersed part of the plunger and cause a displacement of the liquid metal level, under the effect of hydrostatic pressure. The inventive device is characterised in that it comprises a plunger (30), means (41, 31, 32) for modifying the position of the plunger (30) and, optionally means (11, 12) for detecting the height H of the liquid metal (2). The invention enables to vary easily and accurately the height of the liquid metal.

Description

PROCEDE ET DISPOSITIF DE CONTROLE DU NIVEAU DE METAL LIQUIDE DANS UNE MACHINE DE COULEE CONTINUE METHOD AND DEVICE FOR MONITORING THE LEVEL OF LIQUID METAL IN A CONTINUOUS CASTING MACHINE
Domaine de l'inventionField of the invention
L'invention concerne la coulée continue de bande métallique, notamment de bande en aluminium ou en alliage d'aluminium.The invention relates to the continuous casting of metal strip, in particular of aluminum or aluminum alloy strip.
Etat de la techniqueState of the art
La coulée continue entre cylindres est une technique bien connue pour produire des bandes métalliques à partir d'une source de métal liquide. Tel qu'illustré schématiquement en coupe transversale à la figure 1, une machine (1) de coulée continue de bande métallique (3) contient en général au moins deux cylindres (1 A et IB) identiques situés face à face et un dispositif d'injection (6) comprenant un bac de coulée (24) et un injecteur (23). Les cylindres sont séparés par un espace (ou entrefer) E sensiblement égal à l'épaisseur de la bande métallique à produire et tournant en sens inverse l'un de l'autre. Le métal (2) est alimenté, à l'état liquide, d'un côté de l'espace, à l'aide du dispositif d'injection (6), se solidifie au contact des cylindres et sort à l'état solide, de l'autre côté de l'entrefer, sous forme d'une bande (3) ayant une épaisseur nominale Eo. Le métal se solidifie entre les deux cylindres, au niveau de ce qui est connu sous le nom de front de solidification (5). Avec un tel dispositif, on peut produire des bandes allant de quelques centimètres d'épaisseur à quelques millimètres ou moins.Continuous casting between cylinders is a well-known technique for producing metal strips from a source of liquid metal. As shown schematically in cross section in Figure 1, a machine (1) for continuous casting of metal strip (3) generally contains at least two identical cylinders (1 A and IB) located face to face and a device for injection (6) comprising a tundish (24) and an injector (23). The cylinders are separated by a space (or air gap) E substantially equal to the thickness of the metal strip to be produced and rotating in opposite directions to one another. The metal (2) is supplied, in the liquid state, to one side of the space, using the injection device (6), solidifies on contact with the cylinders and leaves in the solid state, on the other side of the air gap, in the form of a strip (3) having a nominal thickness Eo. The metal solidifies between the two cylinders, at what is known as the solidification front (5). With such a device, bands ranging from a few centimeters thick to a few millimeters or less can be produced.
Il est en général impératif de maîtriser la régularité de l'épaisseur de la bande obtenue, notamment pour les faibles épaisseurs, car cette régularité détermine les propriétés d'usages de la bande, notamment de son aptitude à être transformée. On vise généralement des fluctuations d'épaisseur inférieures à ± 1 %. Par exemple, pour une bande de 3 mm d'épaisseur, les fluctuations d'épaisseur devraient rester inférieures à ± 30 μm. On connaît plusieurs facteurs à l'origine des fluctuations d'épaisseur, lesquelles fluctuations consistent essentiellement en des variations et des irrégularités. En particulier, il est maintenant bien établi que les fluctuations du niveau du métal liquide contenu dans le dispositif d'injection génèrent des fluctuations d'épaisseur de la bande. Typiquement, la hauteur de la nappe de métal contenue dans le dispositif d'injection est de l'ordre de 40 à 50 mm.It is generally imperative to control the regularity of the thickness of the strip obtained, in particular for small thicknesses, because this regularity determines the properties of use of the strip, in particular of its ability to be transformed. We generally aim for thickness fluctuations of less than ± 1%. For example, for a 3 mm thick strip, the thickness fluctuations should remain less than ± 30 μm. Several factors are known to be responsible for the thickness fluctuations, which fluctuations consist essentially of variations and irregularities. In particular, it is now well established that fluctuations in the level of the liquid metal contained in the injection device generate fluctuations in the thickness of the strip. Typically, the height of the sheet of metal contained in the injection device is of the order of 40 to 50 mm.
Plusieurs solutions ont été développées pour limiter les fluctuations de la hauteur du niveau du métal liquide. La figure 2 illustre deux de ces solutions.Several solutions have been developed to limit fluctuations in the height of the level of the liquid metal. Figure 2 illustrates two of these solutions.
Dans le dispositif de la figure 2A, le dispositif d'injection (6) est alimenté à l'aide d'une goulotte (7) munie de moyens (16, 17) pour réguler le débit de métal liquide déversé dans le bac de coulée (24). La goulotte d'alimentation (7) est alimentée en métal liquide (8) par un four de maintien (qui n'est pas illustré). Selon ce dispositif, un flotteur/obturateur (16) coiffe une ouverture (17) aménagée à l'extrémité de la goulotte d'alimentation (7) et coopère avec celle-ci de manière à permettre un écoulement du métal liquide dont le débit est fonction de l'enfoncement du flotteur/obturateur (16). Ce dernier flotte en surface du métal liquide (2), suit les variations de la hauteur H de ce métal et limite le flux de métal (18) en fonction de la hauteur du niveau de métal. Le niveau de métal liquide est alors régulé de manière purement mécanique. Avec un tel dispositif, pour un débit typique de 3 tonnes/heure, les fluctuations de hauteur du niveau métal sont au mieux de l'ordre de ± 1 mm.In the device of FIG. 2A, the injection device (6) is supplied using a chute (7) provided with means (16, 17) for regulating the flow of liquid metal poured into the casting tray (24). The feed chute (7) is supplied with liquid metal (8) by a holding furnace (which is not illustrated). According to this device, a float / shutter (16) covers an opening (17) arranged at the end of the feed chute (7) and cooperates with it so as to allow a flow of liquid metal whose flow is function of the float / obturator (16). The latter floats on the surface of the liquid metal (2), follows the variations in the height H of this metal and limits the flow of metal (18) as a function of the height of the metal level. The level of liquid metal is then regulated purely mechanically. With such a device, for a typical flow rate of 3 tonnes / hour, the height fluctuations of the metal level are at best of the order of ± 1 mm.
Dans le dispositif de la figure 2B, le dispositif d'injection (6) est alimentée à l'aide d'une goulotte d'alimentation (7) munie de moyens (9-15) pour réguler le débit de métal liquide déversé dans le dispositif d'injection en fonction d'une hauteur mesurée. Les moyens de régulation (9-15) comprennent un capteur de niveau de métal (11), qui est typiquement un capteur capacitif, un circuit électronique de régulation (10) comprenant un circuit de détection (12) et un circuit de commande (13), une ouverture réglable (9) aménagée dans le fond de la goulotte d'alimentation (7). L'ouverture (9) peut être obturée de manière contrôlée par un moyen d'obturation (15) déplacé verticalement par un actionneur (14) sous la commande du circuit (13). Avec un tel dispositif, pour un débit typique de 3 tonnes/heure, les fluctuations de hauteur du niveau métal sont au mieux de l'ordre de ± 0,5 mm.In the device of FIG. 2B, the injection device (6) is supplied using a feed chute (7) provided with means (9-15) for regulating the flow of liquid metal poured into the injection device according to a measured height. The regulation means (9-15) comprise a metal level sensor (11), which is typically a capacitive sensor, an electronic regulation circuit (10) comprising a detection circuit (12) and a control circuit (13 ), an adjustable opening (9) arranged in the bottom of the feed chute (7). The opening (9) can be closed in a controlled manner by a shutter means (15) moved vertically by an actuator (14) under the control of the circuit (13). With such a device, for a typical flow rate of 3 tonnes / hour, the height fluctuations of the metal level are at best of the order of ± 0.5 mm.
La demanderesse a donc recherché des solutions qui permettent de limiter les fluctuations, c'est-à-dire les variations et irrégularités, d'épaisseur des bandes métalliques obtenues par coulée continue à des valeurs inférieures à ± 0,05 mm, tout en permettant des débits importants de métal liquide, à savoir des débits de l'ordre de 3 tonnes/h ou plus, et la production de bandes de grande largeur, à savoir d'une largeur typiquement supérieure à 1 mètre, voire supérieure à 2 mètres.The Applicant has therefore sought solutions which make it possible to limit the fluctuations, that is to say the variations and irregularities, in the thickness of the metal strips obtained by continuous casting to values less than ± 0.05 mm, while allowing large flows of liquid metal, namely flows of the order of 3 tonnes / h or more, and the production of strips of large width, namely of a width typically greater than 1 meter, or even greater than 2 meters.
Description de l'inventionDescription of the invention
Dans ses recherches, la demanderesse a constaté que les fluctuations d'épaisseur de la bande issue d'une machine de coulée continue restent sensiblement les mêmes, en valeur absolue, quelle que soit l'épaisseur de la bande. Dans ces conditions, une fourchette de fluctuations qui est tolérable pour des bandes épaisses devient rédhibitoire pour des bandes de faible épaisseur. Or, typiquement, les dispositifs de l'état de la technique permettent de limiter l'amplitude des fluctuations d'épaisseur au mieux à environ ± 0,05 mm quelle que soit l'épaisseur de la bande. Par exemple, avec les dispositifs connus, il n'est pas possible de couler des bandes d'une épaisseur inférieure à 5 mm avec une précision sur l'épaisseur meilleure que ± 1 %. En outre, les fluctuations sont généralement d'autant plus importantes que la largeur de la bande est grande.In its research, the Applicant has found that the fluctuations in thickness of the strip coming from a continuous casting machine remain substantially the same, in absolute value, whatever the thickness of the strip. Under these conditions, a range of fluctuations which is tolerable for thick bands becomes unacceptable for bands of thin thickness. However, typically, the devices of the prior art make it possible to limit the amplitude of the thickness fluctuations at best to about ± 0.05 mm whatever the thickness of the strip. For example, with the known devices, it is not possible to cast strips of a thickness less than 5 mm with a precision on the thickness better than ± 1%. In addition, the fluctuations are generally greater the greater the width of the strip.
Dans sa recherche de solutions, la demanderesse a émis l'hypothèse que des fluctuations du niveau du métal liquide dans la goulotte de l'ordre de ± 0,5 mm étaient encore trop importantes et pouvaient expliquer une grande partie des fluctuations observées sur l'épaisseur de la bande coulée. Elle a d'ailleurs noté que la hauteur H de métal dans le bac de coulée, et plus précisément la hauteur Hc de métal entre le centre de l'injecteur et la surface libre du métal liquide dans le bac de coulée, qui établit la charge métallostatique au niveau de l'injecteur, déterminait de manière critique les échanges thermiques et la qualité de la bande métallique obtenue. Elle a donc recherché des moyens pour réduire encore davantage l'amplitude des fluctuations du niveau de métal liquide.In its search for solutions, the applicant hypothesized that fluctuations in the level of liquid metal in the chute of the order of ± 0.5 mm were still too large and could explain a large part of the fluctuations observed on the thickness of the casting strip. It also noted that the height H of metal in the tundish, and more precisely the height Hc of metal between the center of the injector and the free surface of the liquid metal in the tundish, which establishes the charge metallostatic at the level of the injector, critically determined the heat exchanges and the quality of the metal strip obtained. She has therefore sought means to further reduce the amplitude of the fluctuations in the level of liquid metal.
La demanderesse a eu l'idée d'utiliser la poussée d'Archimède pour varier de manière simple et contrôlable le niveau du métal liquide contenu dans le dispositif d'injection. Le déplacement d'un plongeur dans le métal liquide permet ainsi de contrôler finement la hauteur du métal liquide, et donc la pression hydrostatique qui en résulte, sans intervenir sur l'alimentation en métal liquide. Le contrôle du niveau et le débit de métal liquide peuvent dès lors être pratiquement découplés. En d'autres termes, l'invention présente l'avantage de séparer le contrôle fin du niveau de métal liquide et de la régulation de l'alimentation en métal liquide. Ainsi, lorsqu'on alimente le dispositif d'injection en métal liquide au cours de la coulée, typiquement à l'aide d'une goulotte, on peut effectuer un contrôle du niveau de métal liquide dans le dispositif d'injection indépendamment de la régulation de l'alimentation en métal liquide, qui vise principalement le contrôle du débit d'alimentation en métal liquide.The Applicant has had the idea of using Archimedes' thrust to vary the level of liquid metal contained in the injection device in a simple and controllable manner. The displacement of a plunger in the liquid metal thus makes it possible to finely control the height of the liquid metal, and therefore the hydrostatic pressure which results therefrom, without intervening on the supply of liquid metal. Liquid metal level and flow control can therefore be practically decoupled. In other words, the invention has the advantage of separating the fine control of the level of liquid metal and the regulation of the supply of liquid metal. Thus, when the injection device is supplied with liquid metal during casting, typically using a chute, it is possible to control the level of liquid metal in the injection device independently of the regulation. liquid metal feed, which mainly aims at controlling the flow rate of liquid metal feed.
L'invention a pour objet un procédé de contrôle de la hauteur H de métal liquide d'un dispositif d'injection d'une machine de coulée continue de bandes métalliques, procédé dans lequel : - on immerge une partie déterminée P d'au moins un plongeur dans ledit métal liquide ;The subject of the invention is a method for controlling the height H of liquid metal of an injection device of a machine for continuously casting metal strips, method in which: - a determined part P of at least is immersed a plunger in said liquid metal;
- on déplace le, ou au moins un, plongeur dans le métal liquide de manière à modifier le volume de la partie immergée du plongeur, à provoquer un déplacement du niveau du métal liquide sous l'effet de la pression hydrostatique et à modifier de ladite hauteur H.- the, or at least one, plunger is moved in the liquid metal so as to modify the volume of the immersed part of the plunger, to cause a displacement of the level of the liquid metal under the effect of hydrostatic pressure and to modify the said height H.
Le déplacement d'un plongeur peut consister à abaisser un peu celui-ci lorsque le niveau du métal liquide est trop faible et, inversement, à le relever un peu lorsque le niveau est trop élevé. Le déplacement requis peut être déterminé par un algorithme simple qui est basé sur l'écart entre une hauteur mesurée H de métal liquide et une valeur de consigne Ho et qui tient compte de la géométrie du (des) plongeur(s) et du dispositif d'injection. L'algorithme est typiquement une fonction inverse de la différence entre la hauteur mesurée H et la hauteur de consigne Ho (et plus avantageusement une fonction de la différence entre la hauteur Hc mesurée et une hauteur de consigne Hco). L'algorithme peut être plus élaboré et peut être, par exemple, une algorithme PID (proportionnel-intégral-différentiel).The displacement of a plunger may consist in lowering it a little when the level of the liquid metal is too low and, conversely, raising it a little when the level is too high. The required displacement can be determined by a simple algorithm which is based on the difference between a measured height H of liquid metal and a reference value Ho and which takes account of the geometry of the plunger (s) and of the device d 'injection. The algorithm is typically an inverse function of the difference between the measured height H and the set height Ho (and more advantageously a function of the difference between the measured height Hc and a set height Hco). The algorithm can be more elaborate and can be, for example, a PID (proportional-integral-differential) algorithm.
L'invention présente également l'avantage de permettre un contrôle, c'est-à-dire un ajustement et/ou une régulation, précis de la hauteur du métal liquide sans modification significative de la pression hydrostatique.The invention also has the advantage of allowing precise control, that is to say an adjustment and / or regulation of the height of the liquid metal without significant modification of the hydrostatic pressure.
Outre les problèmes de tenue au métal liquide et de pollution éventuelle de celui-ci par le (les) plongeur(s), la nature du matériau dont est constitué le (les) plongeur(s) intervient peu dans la précision du procédé, ce qui n'est pas le cas de procédés ou dispositifs basés sur la flottaison d'un des moyens de contrôle.In addition to the problems of resistance to liquid metal and possible pollution thereof by the plunger (s), the nature of the material of which the plunger (s) is made plays little role in the precision of the process, this which is not the case for processes or devices based on the flotation of one of the control means.
L'invention a également pour objet un dispositif de contrôle de la hauteur H du métal liquide contenu dans un dispositif d'injection d'une machine de coulée continue, apte à mettre en œuvre le procédé de l'invention.The invention also relates to a device for controlling the height H of the liquid metal contained in an injection device of a continuous casting machine, capable of implementing the method of the invention.
L'invention a aussi pour objet un procédé de coulée continue d'une bande métallique caractérisé en ce qu'on contrôle la hauteur H du métal liquide contenu dans un dispositif d'injection à l'aide du procédé de contrôle de l'invention.The subject of the invention is also a process for the continuous casting of a metal strip, characterized in that the height H of the liquid metal contained in an injection device is controlled using the control process of the invention.
L'invention a aussi pour objet une machine de coulée continue d'une bande métallique caractérisée en ce qu'elle comporte un dispositif de contrôle de la hauteur H du métal liquide selon l'invention.The invention also relates to a continuous casting machine for a metal strip, characterized in that it includes a device for controlling the height H of the liquid metal according to the invention.
L'invention est particulièrement avantageuse lorsque les bandes métalliques (3) ont une largeur supérieure ou égale à environ 1000 mm, voire supérieure ou égale à environ 2000 mm.The invention is particularly advantageous when the metal strips (3) have a width greater than or equal to approximately 1000 mm, or even greater than or equal to approximately 2000 mm.
Figures La figure 1 représente de manière schématique les éléments de base d'une machine de coulée continue.figures Figure 1 shows schematically the basic elements of a continuous casting machine.
La figure 2 représente deux dispositifs de l'art antérieur qui permettent de contrôler le débit de métal et la hauteur H du niveau de métal liquide dans un dispositif d'injection.FIG. 2 represents two devices of the prior art which make it possible to control the flow of metal and the height H of the level of liquid metal in an injection device.
La figure 3 illustre le principe de fonctionnement du procédé de contrôle du niveau de métal liquide selon l'invention.FIG. 3 illustrates the operating principle of the method for controlling the level of liquid metal according to the invention.
La figure 4 illustre de manière schématique un premier dispositif de l'invention.FIG. 4 schematically illustrates a first device of the invention.
La figure 5 illustre de manière schématique un deuxième dispositif selon l'invention.FIG. 5 schematically illustrates a second device according to the invention.
La figure 6 représente un mode de réalisation du dispositif selon l'invention.FIG. 6 represents an embodiment of the device according to the invention.
Description détaillée de l'inventionDetailed description of the invention
Le procédé de contrôle de la hauteur H de métal liquide (2) d'un dispositif d'injection (6) d'une machine de coulée continue (1) de bandes métalliques (3) selon l'invention est caractérisé en ce que :The method for controlling the height H of liquid metal (2) of an injection device (6) of a continuous casting machine (1) of metal strips (3) according to the invention is characterized in that:
- on immerge une partie déterminée P d'au moins un plongeur (30) dans le métal liquide (2) ;- A determined part P of at least one plunger (30) is immersed in the liquid metal (2);
- on déplace le (au moins un ou chaque) plongeur (30) dans le métal liquide (2) de manière à modifier le volume de la partie immergée P du plongeur, à provoquer un déplacement du niveau (20) du métal liquide (2) sous l'effet de la pression hydrostatique et à modifier de ladite hauteur H.- the (at least one or each) plunger (30) is moved in the liquid metal (2) so as to modify the volume of the submerged part P of the plunger, to cause a displacement of the level (20) of the liquid metal (2 ) under the effect of hydrostatic pressure and to modify said height H.
Le dispositif d'injection (6) comprend une ouverture d'alimentation (19) et une ouverture de sortie (21) ayant une largeur sensiblement égale à celle de la bande (3) à produire. L'injecteur (6) est alimenté en métal liquide à l'aide d'une goulotte (7), qui déverse du métal liquide (8) dans le bac de coulée (24) par l'ouverture d'alimentation (19). La bande métallique (3) sort de l'entrefer E dans une direction (22) sensiblement horizontale ou légèrement inclinée par rapport à l'horizontale. Selon l'invention, le plongeur (30) est immergé dans le métal liquide (2) contenu dans le bac de coulée (24), qui est solidaire de l'injecteur (23), de sorte que le contrôle du niveau de métal liquide s'effectue directement dans le dispositif d'injection (6) (et non dans la goulotte d'alimentation ou plus en amont, ce qui permet de bien découpler le contrôle du débit et le contrôle du niveau de métal). L'invention est particulièrement adaptée aux cas où la hauteur Hc de métal entre le centre de l'injecteur et la surface libre du métal liquide dans le bac de coulée est faible par rapport à la largeur de la bande (Hc est typiquement comprise entre 5 et 50 mm alors que la largeur est typiquement supérieure à environ 1000 mm).The injection device (6) comprises a feed opening (19) and an outlet opening (21) having a width substantially equal to that of the strip (3) to be produced. The injector (6) is supplied with liquid metal using a chute (7), which pours liquid metal (8) into the casting tank (24) through the feed opening (19). The metal strip (3) leaves the air gap E in a direction (22) substantially horizontal or slightly inclined relative to the horizontal. According to the invention, the plunger (30) is immersed in the liquid metal (2) contained in the casting tank (24), which is integral with the injector (23), so that the control of the level of liquid metal takes place directly in the injection device (6) (and not in the feed chute or more upstream, which makes it possible to decouple the flow control and the metal level control). The invention is particularly suitable for cases where the height Hc of metal between the center of the injector and the free surface of the molten metal in the tundish is small compared to the width of the strip (Hc is typically between 5 and 50 mm while the width is typically greater than about 1000 mm).
Selon un mode de réalisation préféré de l'invention, on déplace le (au moins un ou chaque) plongeur en fonction d'une valeur mesurée du niveau (20) du métal liquide. Plus précisément, le procédé de l'invention est caractérisé en ce que :According to a preferred embodiment of the invention, the (at least one or each) plunger is moved as a function of a measured value of the level (20) of the liquid metal. More specifically, the method of the invention is characterized in that:
- on détermine, de préférence de manière périodique ou continue, la hauteur H du métal liquide (2) contenu dans dispositif d'injection (6), typiquement à partir d'une mesure du niveau (20) du métal liquide ;- Determining, preferably periodically or continuously, the height H of the liquid metal (2) contained in the injection device (6), typically from a measurement of the level (20) of the liquid metal;
- on déplace le, au moins un ou chaque, plongeur (30) dans le métal liquide de manière à annuler l'écart entre H et une valeur de consigne Ho déterminée.- Moving the, at least one or each, plunger (30) in the liquid metal so as to cancel the difference between H and a setpoint value Ho determined.
Dans une version simple du contrôle, on compare de la hauteur mesurée H à la valeur de consigne Ho afin de déterminer le déplacement du (des) plongeur(s). Typiquement, on compare la hauteur mesurée H à la valeur de consigne Ho et on déplace le plongeur en fonction inverse de la différence entre la hauteur mesurée H et la hauteur de consigne Ho. Le déplacement du (des) plongeur(s) (30) peut comprendre des opérations d'immersion et d'émersion complémentaires. Par exemple :In a simple version of the control, the measured height H is compared to the set value Ho in order to determine the displacement of the plunger (s). Typically, the measured height H is compared to the set value Ho and the plunger is moved in inverse function to the difference between the measured height H and the set height Ho. The displacement of the plunger (s) (30) may include additional immersion and emersion operations. For example :
- on immerge une partie complémentaire déterminée ΔP+ du (d'au moins un ou de chaque) plongeur (30) lorsque H < Ho, de manière à faire remonter le niveau (20) du métal liquide (2) et à augmenter ladite hauteur H ; - on fait émerger une partie déterminée ΔP- du (d'au moins un ou de chaque) plongeur (30) lorsque H > Ho, de manière à faire baisser le niveau (20) du métal liquide (2) et à diminuer ladite hauteur H.- a determined complementary part ΔP + of the (at least one or each) plunger (30) is immersed when H <Ho, so as to raise the level (20) of the liquid metal (2) and to increase said height H ; - a determined part ΔP- is made to emerge from (at least one or each) plunger (30) when H> Ho, so as to lower the level (20) of the liquid metal (2) and to reduce said height H.
Comme le montre la figure 3, l'immersion ou l'émersion partielle du plongeur permet de faire varier la hauteur de manière à corriger les écarts entre la valeur mesurée H et la valeur de consigne Ho. Lesdites quantités déterminées ΔP+ et ΔP-, pour l'abaissement ou le relèvement du, ou de chaque, plongeur (30), dépendent typiquement de l'écart entre H et Ho, de la forme du (des) plongeur(s) (30) et de la forme du dispositif d'injection (6). Ces quantités peuvent être déterminées par calcul géométrique, par exemple à l'aide d'un algorithme simple basé sur l'écart entre H et Ho (et donc basé sur les volumes de métal à déplacer) et tenant compte de la géométrie du (des) plongeur(s) et du dispositif d'injection. Par exemple, ΔP+ et ΔP- peuvent être données par le volume Vm de métal respectivement au-dessous et au- dessus du niveau de consigne, correspondant à la différence entre le volume réel de métal liquide et le volume délimité par le niveau de consigne, la surface interne du bac de coulée et le front de solidification. Le volume Vm est égal approximativement au produit de l'aire de la surface libre (20) du métal liquide (2) et de l'écart entre la hauteur de consigne Ho et la hauteur mesurée H.As shown in FIG. 3, the partial immersion or emersion of the plunger makes it possible to vary the height so as to correct the differences between the measured value H and the reference value Ho. Said determined quantities ΔP + and ΔP-, for the lowering or raising of, or each, plunger (30), typically depend on the difference between H and Ho, the shape of the plunger (s) (30) and the shape of the device injection (6). These quantities can be determined by geometric calculation, for example using a simple algorithm based on the difference between H and Ho (and therefore based on the volumes of metal to be moved) and taking into account the geometry of (the ) plunger (s) and injection device. For example, ΔP + and ΔP- can be given by the volume Vm of metal respectively below and above the setpoint level, corresponding to the difference between the actual volume of liquid metal and the volume delimited by the setpoint level, the internal surface of the tundish and the solidification front. The volume Vm is approximately equal to the product of the area of the free surface (20) of the liquid metal (2) and the difference between the set height Ho and the measured height H.
Le (ou les) plongeur(s) (30) peut (peuvent) avoir une forme quelconque, telle qu'une forme cylindrique ou conique. La forme et l'aire de la surface du (des) plongeur(s) sont ajustées de manière à assurer la précision requise (lorsqu'un plongeur est immergé à sa profondeur de référence).The plunger (s) (30) may (may) have any shape, such as a cylindrical or conical shape. The shape and surface area of the plunger (s) are adjusted to ensure the required precision (when a plunger is submerged to its reference depth).
De préférence, au moins un plongeur est de forme cylindrique de section circulaire S et dont l'axe principal est perpendiculaire à la surface libre (20) du métal liquide (2), auquel cas le (ou chaque) plongeur peut être déplacé verticalement d'une distance ΔX approximativement égale à (H - Ho) x So / S, où So est l'aire de la surface libre (20) du métal liquide (2) contenu dans le dispositif d'injection (6). Si H est inférieure à Ho, alors ΔH est négatif et le plongeur peut être abaissé ; si H est supérieure à Ho, alors ΔH est positif et le plongeur peut être relevé. La hauteur H de métal liquide est généralement donnée par rapport au fond du dispositif d'injection (6), et de préférence par rapport au centre de l'injecteur (23).Preferably, at least one plunger is of cylindrical shape of circular section S and the main axis of which is perpendicular to the free surface (20) of the liquid metal (2), in which case the (or each) plunger can be moved vertically d 'a distance ΔX approximately equal to (H - Ho) x So / S, where So is the area of the free surface (20) of the liquid metal (2) contained in the injection device (6). If H is less than Ho, then ΔH is negative and the plunger can be lowered; if H is greater than Ho, then ΔH is positive and the plunger can be raised. The height H of liquid metal is generally given relative to the bottom of the injection device (6), and preferably relative to the center of the injector (23).
En outre, le (les) plongeur(s) est (sont) constitué(s) de préférence d'un matériau réfractaire, inerte vis-à-vis du métal liquide, tel qu'une céramique, de manière à pouvoir rester longtemps immergé(s) dans le métal liquide sans risque de dégradation ou de pollution. Le matériau est de préférence non-poreux, de manière à limiter la pollution du métal liquide, notamment lors des changements d'alliage.In addition, the plunger (s) is (are) preferably made of a refractory material, inert with respect to the liquid metal, such as a ceramic, so as to be able to remain immersed for a long time (s) in liquid metal without risk of degradation or pollution. The material is preferably non-porous, so as to limit pollution of the liquid metal, in particular during alloy changes.
Le volume V du (des) plongeur(s) (30) est approximativement au moins égal au produit de l'aire de la surface libre (20) du métal liquide (2) et des variations maximales de hauteur à corriger. Typiquement, pour corriger des variations de hauteur de ± 0,3 mm sur une surface libre égale à environ 20 000 cm2, il faut prévoir un plongeur dont le volume est au moins égal à 2 x 0,6 mm x 20 000 cm2 = 2 400 cm . Ceci correspond, par exemple, à un plongeur de forme cylindrique d'une hauteur de 40 mm environ et d'un diamètre de 140 mm environ.The volume V of the plunger (s) (30) is approximately at least equal to the product of the area of the free surface (20) of the liquid metal (2) and the maximum variations in height to be corrected. Typically, to correct height variations of ± 0.3 mm on a free surface equal to approximately 20,000 cm 2 , a diver whose volume is at least equal to 2 x 0.6 mm x 20,000 cm 2 must be provided = 2400 cm. This corresponds, for example, to a plunger of cylindrical shape with a height of about 40 mm and a diameter of about 140 mm.
Lors de la coulée continue, on alimente le dispositif d'injection (6) en métal liquide (2), typiquement à l'aide d'une goulotte (7). Le procédé de contrôle de l'invention peut être associé à un procédé de contrôle l'alimentation du dispositif d'injection (6) en métal liquide (2). Le procédé de contrôle selon l'invention assure alors une régulation et un ajustement précis de la hauteur du métal liquide qui complète le contrôle grossier de la hauteur du métal assuré par le procédé de contrôle de l'alimentation. Le procédé de contrôle selon l'invention peut être compris dans un procédé de contrôle de la machine de coulée continue (1).During continuous casting, the injection device (6) is supplied with liquid metal (2), typically using a chute (7). The control method of the invention can be combined with a method of controlling the supply of liquid metal (2) to the injection device (6). The control method according to the invention then provides precise regulation and adjustment of the height of the liquid metal which completes the rough control of the height of the metal provided by the feed control method. The control method according to the invention can be included in a control method of the continuous casting machine (1).
L'invention a également pour objet un dispositif (40) de contrôle de la hauteur H du métal liquide (2) contenu dans un dispositif d'injection (6) d'une machine de coulée continue (1), apte à mettre en œuvre le procédé de l'invention. Ce dispositif comprend au moins un plongeur (30) et des moyens (41, 31, 32) pour modifier la position du (ou de chaque) plongeur (30). Dans une version préférée de l'invention, le dispositif comprend également des moyens (11, 12) pour détecter la hauteur H du métal liquide (2). Les moyens (11, 12) pour détecter la hauteur H du métal liquide (2) comprennent un capteur de niveau de métal (11), qui est typiquement un capteur capacitif, et un circuit de détection (12), qui peut traduire, si nécessaire, le signal du capteur en un signal déterminé représentatif de la hauteur réelle du métal liquide (2). La figure 4 illustre un tel dispositif.The invention also relates to a device (40) for controlling the height H of the liquid metal (2) contained in an injection device (6) of a continuous casting machine (1), capable of implementing the method of the invention. This device comprises at least one plunger (30) and means (41, 31, 32) for modifying the position of the (or each) plunger (30). In a preferred version of the invention, the device also comprises means (11, 12) for detecting the height H of the liquid metal (2). The means (11, 12) for detecting the height H of the liquid metal (2) comprises a metal level sensor (11), which is typically a capacitive sensor, and a detection circuit (12), which can translate, if necessary, the sensor signal into a determined signal representative of the actual height of the liquid metal (2). Figure 4 illustrates such a device.
Les moyens (41, 31, 32) pour modifier la position du (des) plongeur(s) (30) peuvent comprendre typiquement un circuit de commande (41), un actionneur (32) et un moyen de fixation et de support (31) du (des) plongeur(s) (30). L'actionneur permet d'immerger une partie déterminée du (des) plongeur(s) (30) dans le métal liquide (2) et de le déplacer, typiquement de bas en haut, et inversement, c'est-à-dire de l'abaisser d'une quantité déterminée ΔX- lorsque H < Ho, de manière à faire remonter le niveau de métal liquide et de le relever d'une quantité déterminée ΔX+ lorsque H > Ho, de manière à faire baisser le niveau de métal liquide.The means (41, 31, 32) for modifying the position of the plunger (s) (30) may typically comprise a control circuit (41), an actuator (32) and a fixing and support means (31 ) of the diver (s) (30). The actuator makes it possible to immerse a determined part of the plunger (s) (30) in the liquid metal (2) and to move it, typically from bottom to top, and vice versa, i.e. lower it by a determined quantity ΔX- when H <Ho, so as to raise the level of liquid metal and raise it by a determined quantity ΔX + when H> Ho, so as to lower the level of liquid metal .
Le circuit de commande (41), qui est typiquement raccordé directement au circuit de détection (12), commande l'actionneur (32) en fonction des mouvements du (des) plongeur(s) (30) requis pour corriger la hauteur H du métal liquide (2). Ces moyens peuvent être aisément automatisés ou pilotés par ordinateur. Dans ce cas, le circuit de commande (41) permet de comparer la hauteur mesurée H, connue par le signal issu du circuit de détection (12), à la hauteur de consigne Ho.The control circuit (41), which is typically connected directly to the detection circuit (12), controls the actuator (32) according to the movements of the plunger (s) (30) required to correct the height H of the liquid metal (2). These means can be easily automated or controlled by computer. In this case, the control circuit (41) makes it possible to compare the measured height H, known by the signal from the detection circuit (12), with the set height Ho.
En pratique, il peut être avantageux de regrouper les circuits de détection (12) et de commande (41) dans un coffret (42), éventuellement unique, de manière à les isoler des perturbations électromagnétiques et à diminuer les risques d'endommagement de ceux-ci.In practice, it may be advantageous to group the detection (12) and control (41) circuits in a box (42), possibly unique, so as to isolate them from electromagnetic interference and to reduce the risk of damage to those -this.
Selon une variante de l'invention, le dispositif de contrôle de la hauteur (40) est associé à un dispositif de contrôle de l'alimentation en métal liquide (50), tel qu'illustré par exemple à la figure 5. Le dispositif de contrôle (40) assure alors une régulation et un ajustement précis de la hauteur du métal liquide qui complète le contrôle grossier de la hauteur du métal assuré par le dispositif (50). Le dispositif selon l'invention peut aussi être compris dans un dispositif de contrôle de la machine de coulée continue (1).According to a variant of the invention, the height control device (40) is associated with a device for controlling the supply of liquid metal (50), as illustrated for example in FIG. 5. The device control (40) then ensures regulation and precise adjustment of the height of the liquid metal which completes the rough control of the height of the metal provided by the device (50). The device according to the invention can also be included in a device for controlling the continuous casting machine (1).
Le dispositif de contrôle (50) comprend, par exemple, une goulotte d'alimentation (7) munie de moyens (9, 11-15) pour contrôler le débit de métal liquide déversé dans le dispositif d'injection (6). Les moyens de contrôle (9, 11-15) comprennent un capteur de niveau de métal (11), qui est typiquement un capteur capacitif, un circuit électronique de contrôle comprenant un circuit de détection (12) et un circuit de commande (13), une ouverture réglable (9) obturée de manière contrôlée par un moyen (15), qui est actionné par le moyen (14) sous la commande du circuit (13). Comme le montre la figure 5, le capteur de niveau (11) et le circuit de détection (12) sont avantageusement communs au dispositif de contrôle de la hauteur du métal liquide selon l'invention et au dispositif de contrôle de l'alimentation en métal liquide. En pratique, il peut être avantageux de regrouper les circuits de détection (12) et de commande (13, 41) dans un coffret (52), de manière à les isoler des perturbations électromagnétiques et à diminuer les risques d'endommagement de ceux-ci.The control device (50) comprises, for example, a feed chute (7) provided with means (9, 11-15) for controlling the flow of liquid metal poured into the injection device (6). The control means (9, 11-15) comprise a metal level sensor (11), which is typically a capacitive sensor, an electronic control circuit comprising a detection circuit (12) and a control circuit (13) , an adjustable opening (9) closed in a controlled manner by means (15), which is actuated by the means (14) under the control of the circuit (13). As shown in FIG. 5, the level sensor (11) and the detection circuit (12) are advantageously common to the device for controlling the height of the liquid metal according to the invention and to the device for controlling the metal supply liquid. In practice, it may be advantageous to group the detection (12) and control (13, 41) circuits in a box (52), so as to isolate them from electromagnetic disturbances and to reduce the risks of damage to them. this.
L'invention a aussi pour objet l'utilisation d'au moins un plongeur (30) pour contrôler la hauteur du métal liquide contenu dans un dispositif d'alimentation en métal liquide, tel qu'un dispositif d'injection.The invention also relates to the use of at least one plunger (30) to control the height of the liquid metal contained in a liquid metal supply device, such as an injection device.
L'invention a aussi pour objet un procédé de coulée continue d'une bande métallique (3) dans lequel on alimente un dispositif d'injection (6) en métal liquide (2), caractérisé en ce qu'on contrôle la hauteur H du métal liquide (2) contenu dans le dispositif d'injection (6) à l'aide du procédé de contrôle de l'invention. On peut éventuellement réguler, en outre, le débit d'alimentation du dispositif d'injection (6) en métal liquide (2). Ladite bande métallique a typiquement une largeur supérieure ou égale à environ 1000 mm, voire supérieure ou égale à environ 2000 mm. Ladite bande est typiquement en aluminium ou en alliage d'aluminium. L'invention a aussi pour objet une machine de coulée continue (1) d'une bande métallique (3) comprenant un dispositif d'injection (6) et caractérisée en ce qu'elle comporte un dispositif de contrôle (40) de la hauteur H du métal liquide (2) contenu dans dispositif d'injection (6) selon l'invention. De préférence, la machine de coulée continue selon l'invention est également caractérisée en ce qu'elle est apte à permettre la coulée de bandes ayant une largeur supérieure ou égale à environ 1000 mm, voire supérieure ou égale à environ 2000 mm.The subject of the invention is also a process for the continuous casting of a metal strip (3) in which an injection device (6) is supplied with liquid metal (2), characterized in that the height H of the liquid metal (2) contained in the injection device (6) using the control method of the invention. Optionally, the supply rate of the injection device (6) in liquid metal (2) can also be regulated. Said metal strip typically has a width greater than or equal to approximately 1000 mm, or even greater than or equal to approximately 2000 mm. Said strip is typically made of aluminum or an aluminum alloy. The invention also relates to a continuous casting machine (1) for a metal strip (3) comprising an injection device (6) and characterized in that it comprises a height control device (40) H of the liquid metal (2) contained in the injection device (6) according to the invention. Preferably, the continuous casting machine according to the invention is also characterized in that it is capable of allowing the casting of strips having a width greater than or equal to approximately 1000 mm, or even greater than or equal to approximately 2000 mm.
L'invention est adaptée à la coulée continue de bandes en aluminium ou en alliage d'aluminium, mais peut être appliquée à la coulée continue de tout métal liquide.The invention is suitable for the continuous casting of strips of aluminum or aluminum alloy, but can be applied to the continuous casting of any liquid metal.
ExempleExample
La figure 6 représente un mode de réalisation possible de la partie mécanique (30, 31, 32) du dispositif selon l'invention. Celle-ci comporte un plongeur (30), une tige (31) pour supporter le plongeur et un actionneur (32). L'actionneur (32) comprend une barre métallique (33), de préférence sensiblement horizontale, qui est fixée à un support (39), de manière à pouvoir pivoter librement autour d'un axe (35), et est munie d'un contrepoids (36). L'actionneur (32) comprend en outre une came (37) de forme sensiblement spiroïdale (proche d'une spirale) dont le rayon croît régulièrement d'une valeur minimale RI à une valeur maximale R2 sur un angle θ. La came (37) s'appuie contre la barre (33), de préférence du côté du contrepoids (36). Le pivotement de la came (37) autour d'un axe (38) à l'aide, par exemple, d'un moteur pas-à-pas, permet de faire pivoter la barre (33) autour de l'axe (35) de manière contrôlée. Les pivotements de la barre (33) entraînent des mouvements de haut en bas, ou de bas en haut, du plongeur (30). La course C de ces mouvements est liée à la différence entre RI et R2, à la distance d'appui D et à l'entre axe E. Par exemple, pour RI = 12,5 mm et R2 = 37,5 mm, D / E = 1,25, on obtient une course de ± 20 mm. FIG. 6 represents a possible embodiment of the mechanical part (30, 31, 32) of the device according to the invention. This comprises a plunger (30), a rod (31) for supporting the plunger and an actuator (32). The actuator (32) comprises a metal bar (33), preferably substantially horizontal, which is fixed to a support (39), so that it can pivot freely around an axis (35), and is provided with a counterweight (36). The actuator (32) further comprises a cam (37) of substantially spiral shape (close to a spiral) whose radius increases regularly from a minimum value RI to a maximum value R2 over an angle θ. The cam (37) bears against the bar (33), preferably on the side of the counterweight (36). The pivoting of the cam (37) around an axis (38) using, for example, a stepping motor, makes it possible to pivot the bar (33) around the axis (35 ) in a controlled manner. The pivoting of the bar (33) causes movements from top to bottom, or from bottom to top, of the plunger (30). The stroke C of these movements is linked to the difference between RI and R2, the support distance D and the distance between axes E. For example, for RI = 12.5 mm and R2 = 37.5 mm, D / E = 1.25, a stroke of ± 20 mm is obtained.

Claims

REVENDICATIONS
1. Procédé de contrôle de la hauteur H du métal liquide (2) d'un dispositif d'injection (6) d'une machine de coulée continue (1) de bandes métalliques caractérisé en ce que :1. Method for controlling the height H of the liquid metal (2) of an injection device (6) of a continuous casting machine (1) of metal strips, characterized in that:
- on immerge une partie déterminée P d'au moins un plongeur (30) dans ledit métal liquide (2) ;- A determined part P of at least one plunger (30) is immersed in said liquid metal (2);
- on déplace le, au moins un ou chaque, plongeur (30) dans le métal liquide (2) de manière à modifier le volume de la partie immergée P du plongeur (30), à provoquer un déplacement du niveau (20) du métal liquide (2) sous l'effet de la pression hydrostatique et à modifier de ladite hauteur H.- the, at least one or each, plunger (30) is moved in the liquid metal (2) so as to modify the volume of the submerged part P of the plunger (30), to cause a displacement of the level (20) of the metal liquid (2) under the effect of hydrostatic pressure and to be modified from said height H.
2. Procédé de contrôle selon la revendication 1, caractérisé en ce que :2. Control method according to claim 1, characterized in that:
- on détermine la hauteur H du métal liquide (2) contenu dans ledit dispositif d'injection (6) ;- the height H of the liquid metal (2) contained in said injection device (6) is determined;
- on déplace le, au moins un ou chaque, plongeur (30) dans le métal liquide (2) de manière à annuler l'écart entre H et une valeur de consigne déterminée Ho.- Moving the, at least one or each, plunger (30) in the liquid metal (2) so as to cancel the difference between H and a determined set value Ho.
3. Procédé selon la revendication 2, caractérisé en ce qu'on compare la hauteur mesurée H à la valeur de consigne Ho et on déplace le plongeur en fonction inverse de la différence entre la hauteur mesurée H et la hauteur de consigne Ho.3. Method according to claim 2, characterized in that the measured height H is compared to the set value Ho and the plunger is moved in inverse function to the difference between the measured height H and the set height Ho.
4. Procédé selon la revendication 3, caractérisé en ce que :4. Method according to claim 3, characterized in that:
- on immerge une partie complémentaire déterminée ΔP+ du, d'au moins un ou de chaque, plongeur (30) lorsque H < Ho, de manière à faire remonter le niveau- a determined complementary part ΔP + of the, of at least one or each, is immersed (30) when H <Ho, so as to raise the level
(20) du métal liquide (2) et à augmenter ladite hauteur H ;(20) liquid metal (2) and increasing said height H;
- on fait émerger une partie déterminée ΔP- du, d'au moins un ou de chaque, plongeur (30) lorsque H > Ho, de manière à faire baisser le niveau (20) du métal liquide (2) et à diminuer ladite hauteur H. - a determined part ΔP- of, from at least one or each, is made to emerge (30) when H> Ho, so as to lower the level (20) of the liquid metal (2) and to reduce said height H.
5. Procédé selon la revendication 4, caractérisé en ce que les quantités ΔP+ et ΔP- sont égales au produit de l'aire de la surface libre (20) du métal liquide (2) et de l'écart entre la hauteur de consigne Ho et la hauteur mesurée H.5. Method according to claim 4, characterized in that the quantities ΔP + and ΔP- are equal to the product of the area of the free surface (20) of the liquid metal (2) and the difference between the set height Ho and the height measured H.
6. Procédé selon la revendication 5, caractérisé en ce qu'au moins un plongeur est de forme cylindrique, de section circulaire S, dont l'axe principal est perpendiculaire à la surface libre du métal liquide, et en ce que le, ou chaque, plongeur de forme cylindrique est déplacé verticalement d'une distance ΔX approximativement égale à (H - Ho) x So / S, où So est l'aire de la surface libre (20) du métal liquide (2) contenu dans le dispositif d'injection (6).6. Method according to claim 5, characterized in that at least one plunger is of cylindrical shape, of circular section S, the main axis of which is perpendicular to the free surface of the liquid metal, and in that the, or each , cylindrical plunger is moved vertically by a distance ΔX approximately equal to (H - Ho) x So / S, where So is the area of the free surface (20) of the liquid metal (2) contained in the device d injection (6).
7. Procédé selon la revendication 2, caractérisé en ce qu'on déplace le, au moins un ou chaque, plongeur (30) dans le métal liquide (2) selon un algorithme PID, c'est-à-dire selon un algorithme proportionnel-intégral-différentiel.7. Method according to claim 2, characterized in that one displaces the, at least one or each, plunger (30) in the liquid metal (2) according to a PID algorithm, that is to say according to a proportional algorithm -intégral-differential.
8. Procédé selon l'une des revendications 1 à 7, caractérisé en ce que lesdites bandes métalliques ont une largeur supérieure ou égale à environ 1000 mm.8. Method according to one of claims 1 to 7, characterized in that said metal strips have a width greater than or equal to about 1000 mm.
9. Procédé de contrôle d'une machine de coulée continue comprenant le procédé de contrôle selon l'une quelconque des revendications 1 à 8.9. A method of controlling a continuous casting machine comprising the control method according to any one of claims 1 to 8.
10. Dispositif de contrôle (40) de la hauteur H du métal liquide (2) contenu dans un dispositif d'injection (6) d'une machine de coulée continue (1), apte à mettre en œuvre le procédé selon l'une quelconque des revendications 1 à 8, caractérisé en ce qu'il comprend au moins un plongeur (30) et des moyens (41, 31, 32) pour modifier la position du (ou de chaque) plongeur (30).10. Control device (40) of the height H of the liquid metal (2) contained in an injection device (6) of a continuous casting machine (1), capable of implementing the method according to one any one of claims 1 to 8, characterized in that it comprises at least one plunger (30) and means (41, 31, 32) for modifying the position of the (or each) plunger (30).
11. Dispositif de contrôle selon la revendication 10, caractérisé en ce qu'il comprend en outre des moyens (11, 12) pour détecter la hauteur H du métal liquide (2). 11. Control device according to claim 10, characterized in that it further comprises means (11, 12) for detecting the height H of the liquid metal (2).
12. Dispositif selon la revendication 10 ou 11, caractérisé en ce qu'au moins un plongeur (30) présente une forme cylindrique dont l'axe principal est de préférence perpendiculaire à la surface libre (20) du métal liquide (2).12. Device according to claim 10 or 11, characterized in that at least one plunger (30) has a cylindrical shape whose main axis is preferably perpendicular to the free surface (20) of the liquid metal (2).
13. Dispositif selon l'une quelconque des revendications 10 à 12, caractérisé en ce que le, au moins un ou chaque, plongeur est constitué d'un matériau réfractaire non-poreux et inerte vis-à-vis du métal liquide.13. Device according to any one of claims 10 to 12, characterized in that the, at least one or each, plunger is made of a non-porous refractory material and inert vis-à-vis the liquid metal.
14. Dispositif selon l'une quelconque des revendications 10 à 13, caractérisé en ce que les moyens (11, 12) pour détecter la hauteur H du métal liquide (2) comprennent un capteur de niveau de métal (11), qui est typiquement un capteur capacitif, un circuit de détection (12), qui traduit le signal du capteur en un signal déterminé représentatif de la hauteur réelle du métal liquide (2).14. Device according to any one of claims 10 to 13, characterized in that the means (11, 12) for detecting the height H of the liquid metal (2) comprise a metal level sensor (11), which is typically a capacitive sensor, a detection circuit (12), which translates the sensor signal into a determined signal representative of the actual height of the liquid metal (2).
15. Dispositif selon l'une quelconque des revendications 10 à 14, caractérisé en ce que les moyens (41, 31, 32) pour modifier la position du, ou de chaque, plongeur (30) comprennent un circuit de commande (41), un actionneur (32) et un moyen de fixation et de support (31) du, ou de chaque, plongeur (30).15. Device according to any one of claims 10 to 14, characterized in that the means (41, 31, 32) for modifying the position of the, or each, plunger (30) comprise a control circuit (41), an actuator (32) and a means for fixing and supporting (31) the, or each, plunger (30).
16. Dispositif selon l'une quelconque des revendications 10 à 15, caractérisé en ce que les moyens (11, 12) pour détecter la hauteur H du métal liquide (2) et les moyens (41, 31, 32) pour modifier la position du, ou de chaque, plongeur (30) sont automatisés ou pilotés par ordinateur.16. Device according to any one of claims 10 to 15, characterized in that the means (11, 12) for detecting the height H of the liquid metal (2) and the means (41, 31, 32) for modifying the position of, or each, diver (30) are automated or computer controlled.
17. Dispositif de contrôle de la machine de coulée continue (1) caractérisé en ce qu'il comprend un dispositif selon l'une quelconque des revendications 10 à 16.17. Control device for the continuous casting machine (1) characterized in that it comprises a device according to any one of claims 10 to 16.
18. Dispositif de contrôle selon la revendication 17, caractérisé en ce qu'il comprend en outre un dispositif de contrôle de l'alimentation en métal liquide (50).18. Control device according to claim 17, characterized in that it further comprises a device for controlling the supply of liquid metal (50).
19. Utilisation du procédé selon l'une quelconque des revendications 1 à 8 pour la coulée continue de bandes en aluminium ou en alliage d'aluminium. 19. Use of the method according to any one of claims 1 to 8 for the continuous casting of aluminum or aluminum alloy strips.
20. Utilisation du dispositif selon l'une quelconque des revendications 10 à 18 pour la coulée continue de bandes en aluminium ou en alliage d'aluminium.20. Use of the device according to any one of claims 10 to 18 for the continuous casting of strips of aluminum or aluminum alloy.
21. Procédé de coulée continue d'une bande métallique (3) dans lequel on alimente un dispositif d'injection (6) en métal liquide (2), caractérisé en ce qu'on contrôle la hauteur H du métal liquide (2) contenu dans le dispositif d'injection (6) à l'aide du procédé de contrôle selon l'une quelconque des revendications 1 à 8.21. Continuous casting method for a metal strip (3) in which an injection device (6) is supplied in liquid metal (2), characterized in that the height H of the liquid metal (2) contained is controlled in the injection device (6) using the control method according to any one of claims 1 to 8.
22. Procédé de coulée continue selon la revendication 21, caractérisé en ce qu'on régule le débit d'alimentation de le dispositif d'injection (6) en métal liquide (2).22. Continuous casting method according to claim 21, characterized in that the supply rate of the injection device (6) in liquid metal (2) is regulated.
23. Procédé selon la revendication 21 ou 22, caractérisé en ce que ladite bande métallique, a une largeur supérieure ou égale à environ 1000 mm.23. The method of claim 21 or 22, characterized in that said metal strip, has a width greater than or equal to about 1000 mm.
24. Procédé selon l'une des revendications 21 à 23, caractérisé- en ce que ladite bande est en aluminium ou en alliage d'aluminium.24. Method according to one of claims 21 to 23, characterized in that said strip is made of aluminum or aluminum alloy.
25. Machine de coulée continue (1) d'une bande métallique (3) comprenant un dispositif d'injection (6) et caractérisée en ce qu'elle comporte un dispositif de contrôle (40) de la hauteur H du métal liquide (2) contenu dans le dispositif d'injection (6) selon l'une quelconque des revendications 10 à 18.25. Continuous casting machine (1) for a metal strip (3) comprising an injection device (6) and characterized in that it comprises a control device (40) for the height H of the liquid metal (2 ) contained in the injection device (6) according to any one of claims 10 to 18.
26. Machine de coulée continue selon la revendication 25, caractérisée en ce que la largeur de ladite bande est supérieure ou égale à environ 1000 mm. 26. Continuous casting machine according to claim 25, characterized in that the width of said strip is greater than or equal to about 1000 mm.
EP01921445A 2000-04-04 2001-04-02 Method and device for controlling metal liquid level in a continuous casting machine Withdrawn EP1272298A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR0004307 2000-04-04
FR0004307A FR2806947B1 (en) 2000-04-04 2000-04-04 METHOD AND DEVICE FOR MONITORING THE METAL LEVEL OF A CONTINUOUS CASTING MACHINE
PCT/FR2001/000975 WO2001074517A1 (en) 2000-04-04 2001-04-02 Method and device for controlling metal liquid level in a continuous casting machine

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EP1272298A1 true EP1272298A1 (en) 2003-01-08

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EP (1) EP1272298A1 (en)
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GB2524962B (en) 2014-04-07 2016-12-07 Cambridge Entpr Ltd Strip casting
ITUA20162539A1 (en) * 2016-04-13 2017-10-13 Bruno Presezzi S P A EQUIPMENT FOR THE AUTOMATIC STARTING OF A CONTINUOUS CASTING LINE

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US3605863A (en) * 1966-07-06 1971-09-20 Battelle Development Corp Apparatus for manufacturing wire and the like
CH461715A (en) * 1966-07-06 1968-08-31 Battelle Development Corp Process for manufacturing a continuous product from a molten material
JPS58188544A (en) * 1982-04-30 1983-11-04 Nippon Kokan Kk <Nkk> Continuous casting device of metallic plate
JPS63215357A (en) * 1987-03-02 1988-09-07 Mitsui Eng & Shipbuild Co Ltd Continuous casting method
US4977951A (en) * 1990-01-10 1990-12-18 Ribbon Technology Corporation Apparatus for flow control of molten material by force detection

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See references of WO0174517A1 *

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FR2806947B1 (en) 2002-08-09
AU4843701A (en) 2001-10-15
WO2001074517A1 (en) 2001-10-11
FR2806947A1 (en) 2001-10-05

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