EP1100639B1 - Method and device for casting a strand of liquid metal - Google Patents

Method and device for casting a strand of liquid metal Download PDF

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Publication number
EP1100639B1
EP1100639B1 EP99948676A EP99948676A EP1100639B1 EP 1100639 B1 EP1100639 B1 EP 1100639B1 EP 99948676 A EP99948676 A EP 99948676A EP 99948676 A EP99948676 A EP 99948676A EP 1100639 B1 EP1100639 B1 EP 1100639B1
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European Patent Office
Prior art keywords
value
casting
level
tolerance
liquid metal
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EP99948676A
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German (de)
French (fr)
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EP1100639A1 (en
Inventor
Uwe STÜRMER
Bernhard Weisshaar
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Siemens AG
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Siemens AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/18—Controlling or regulating processes or operations for pouring
    • 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 a method and a device for casting a strand of liquid metal into a The mold is poured and pulled out of the mold.
  • a regulation of the mold level is for example from the patent Abstracts of Japan, vol. 1997, no. 01 & JP-A-08 243703 known. In the latter publication is used as an input variable the control deviation for a fuzzy setting controller of the liquid level.
  • the object is achieved according to the invention by a method claims 1 to 7 and a device according to the claims 8 to 12 solved.
  • This is used to cast a strand poured liquid metal into a mold and as a strand pulled out of the mold, the casting level, i.e. the level of the liquid metal in the mold, by means of a Casting level controller to a predetermined casting level setpoint is regulated.
  • the mold level controller gives a control output value depending on a given additional value is formed, the additional value being output, if the difference between the actual level and the target level exceeds a tolerance value, with several staggered tolerance values are provided with which the difference between the actual level and the target level is compared, each with a specific additional value is assigned, and in the case of a detected excess of a tolerance value its specific additional value is issued.
  • the respective additional value becomes the control output value of the slurry level regulator added or the additional value replaced the standard output value of the slurry level controller.
  • the task is solved particularly advantageously in that for pouring a strand of liquid metal into a mold poured and pulled out of the mold as a strand, where the mold level, i.e. the level of the liquid metal in the mold, by means of a slurry level controller with at least an integrator to a predetermined casting level setpoint is regulated, and being the difference between Casting level actual value and casting level setpoint advantageously is monitored.
  • the output of the integrator of the slurry level controller is replaced by a predetermined additional value, if the difference between the actual level and Casting level setpoint exceeds a tolerance threshold.
  • the tolerance threshold especially depending on the standard deviation the difference between the actual level and Casting level setpoint or one of the standard deviation equivalent Size, adapted to the casting process. In this way it is possible to have mold level fluctuations due to possible faulty Detection of a termination even though there is no termination, to prevent.
  • the tolerance threshold to a value between 0.02 and 0.1, limited between 0.04 and 0.1 and / or between 0.06 and 0.1. In this way, the stability of an inventive Procedure increased.
  • the liquid metal flows from the distribution channel 7 via a dip tube 5 with outlet opening 6 into the mold 3.
  • In the mold 3 forms a strand from the liquid metal 1, which is pulled out of the mold 3 via rollers 4.
  • the inflow of liquid metal 13 through the dip tube 5 in the Chill mold 3 is influenced by a plug 8 which has a Mechanism 9, which has a support arm and a lifting rod, is moved.
  • the lifting rod is in turn powered by a hydraulic cylinder 10 driven by an automation device 12 depending on a hydraulic cylinder manipulated variable S is controlled or regulated.
  • the position of the lifting rod and so that the stopper position h is by means of a position measuring device 15 measured and to the automation device 12 transfer.
  • the arrangement has a mold level measuring device 11, which the casting level g, i. the stand liquid Measures metal in the mold 3.
  • the mold level measuring device 11 is as well as the position measuring device 15 and the hydraulic cylinder 10 technically connected to the automation device 12.
  • the automation device 12 controls the mold level g.
  • the strand 1 pulled out of the mold 3 has a sump tip, d. H. a liquid core 2, and a solidified shell 14 on.
  • the slurry level regulator 20 has a P element 21 and an integrator 22.
  • the Casting level controller 20 determines a stopper position setpoint h * as a function of the difference from a set level g * and the casting mirror g.
  • the stopper positioner 23 determines a manipulated variable s for the lifting cylinder 10 as a function of a stopper position control difference ⁇ h.
  • the Plug position control difference ⁇ h is the difference Stopper position setpoint h * and stopper position h.
  • the termination pre-control determines an additional value depending on the control deviation ⁇ g c.
  • the output of the integrator 22 is supplemented by the additional value c and set again, if the negative control deviation - ⁇ g a certain tolerance value exceeds.
  • the control deviation ⁇ g is the difference from the set level g * and the set level g.
  • FIG. 3 shows a particularly advantageous exemplary embodiment the invention.
  • Abort pre-control 24 and abort pre-control 25 differ essentially in that the tolerance thresholds as a function of the abort feedforward control 25 the standard deviation ⁇ the control deviation ⁇ g can be determined over a certain time window.
  • the standard deviation ⁇ can also be an equivalent Size can be used.
  • the standard deviation ⁇ is calculated using of the statistical block 26 determined in the present embodiment a standard deviation generator about a particular one Time window is. However, it can be more complex statistical function blocks, as well as fuzzy logic or neuronal Nets to be replaced.
  • FIG. 4 shows a simple exemplary embodiment for an abort pre-control 24 according to FIG. 2.
  • This has a negator 30 for negating the control deviation ⁇ g.
  • the abort pre-control has a tolerance value checker 31, a holding element 32 and a switch 33.
  • the tolerance value checker 31 checks whether the negative control deviation - ⁇ g exceeds a certain tolerance value. If the tolerance value checker 31 detects that the negative control deviation - ⁇ g exceeds a certain tolerance value, the holding element 32 closes the switch 33 for one scanning step. In this sampling step, the abort pre-control 24 outputs an additional value c. If the scan pre-control 24 outputs an additional value c, the output value of the integrator 22 in FIG.
  • the additional value c is composed of a plurality of staggered values c 1 , c 2 , c 3 , as is exemplified in FIG. 5.
  • the particularly advantageous embodiment of the breakaway pilot control 25 includes a negator 30, holding members 32, tolerance tester 40, 41, 42, P-members 43, 44, 45, with the gains K 3 , K 2 , K 1 , limiter 46, 47, 48 and switches 49, 50 and 51 on.
  • tolerance values are provided for the tolerance value checkers 40, 41, 42, which are advantageously adapted to the casting process.
  • the standard deviation ⁇ is multiplied by the P terms 43, 44, 45 by a gain K 3 , K 2 , K 1 and then limited by the delimiters 46, 47, 48.
  • the output value of the limiters 46, 47, 48 is the tolerance value that is used in the tolerance value checker 40, 41, 42.
  • the tolerance value checkers 40, 41, 42 it is checked whether the negative control deviation - ⁇ g exceeds this tolerance value. If one of the tolerance value checkers 40, 41, 42 determines that its tolerance value has been exceeded by the negative control deviation - ⁇ g, the corresponding holding element 32 closes the corresponding switch 49, 50, 51. According to the combination of closed switches 49, 50, 51, an additional value c output. If an additional value c is present, the output of the integrator 22 in FIG. 3 is supplemented by the additional value c in this sampling step and reset.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)

Abstract

A method and device are provided for casting a strand of liquid metal which is cast into a mold, and which is drawn as a strand out of the mold. The casting level, e.g., a level of the liquid metal in the mold, is regulated to a predetermined casting-level desired value using a casting-level controller having at least one integrator. The output of the integrator of the casting-level controller is replaced by a predetermined value when the difference between the casting-level actual value and the casting-level desired value exceeds a tolerance threshold.

Description

Die Erfindung betrifft ein Verfahren sowie eine Einrichtung zum Gießen eines Stranges aus flüssigem Metall, das in eine Kokille gegossen und aus der Kokille herausgezogen wird.The invention relates to a method and a device for casting a strand of liquid metal into a The mold is poured and pulled out of the mold.

Beim Stranggießen wird, mittels einer Kokille, aus flüssigem Metall ein Strang gegossen, der aus der Kokille herausgezogen wird. Ein wesentlicher Faktor für eine gute Qualität des so gegossenen Stranges ist eine Konstanthaltung des Gießspiegels, d. h. des Standes von flüssigem Metall in der Kokille.In the case of continuous casting, a mold is used to turn liquid Metal cast a strand that pulled out of the mold becomes. An essential factor for a good quality of the sun cast strand is a constant level of the casting level, d. H. the level of liquid metal in the mold.

Eine Regelung des Gießspiegels ist beispielsweise aus den Patent Abstracts of Japan, vol. 1997, no. 01 & JP-A-08 243703 bekannt. In der letztgenannten Druckschrift wird als Eingangsgröße für einen Fuzzy-Einstellregler die Regelabweichung des Gießspiegels herangezogen.A regulation of the mold level is for example from the patent Abstracts of Japan, vol. 1997, no. 01 & JP-A-08 243703 known. In the latter publication is used as an input variable the control deviation for a fuzzy setting controller of the liquid level.

Die Reglerauslegung beim Stranggießen ist schwierig, da die Parameter der Regelstrecke, d.h. der Gießapparatur und der Kokille, zum Teil starken Schwankungen unterworfen sind oder Störgrößen auf den Gießspiegel einwirken. Wie in FIG 1 dargestellt, fließt beim Stranggießen flüssiges Metall über ein Tauchrohr mit Auslaßöffnung in die Kokille. Der Zufluß flüssigen Metalls über das Tauchrohr in die Kokille wird über einen Stopfen beeinflußt. Insbesondere bei ferritischen Stählen kommt es zur Ablagerung am Stopfen oder im Bereich des Tauchrohres, wodurch der Zufluß verringert wird. Diese langsamen Störeinflüsse können auf einfache Weise durch eine Regelung des Gießspiegels kompensiert werden. Dabei wird durch die Regelung die Öffnung entsprechend dem Ausmaß der Ablagerungen erhöht. Brechen jedoch diese Ablagerungen ab, so kommt es zu einer sprunghaften Erhöhung des Zuflusses flüssigen Metalls in die Kokille. Es hat sich gezeigt, daß derartige sprunghafte Veränderungen des Zuflusses flüssigen Metalls in die Kokille zu starken Erhöhungen des Gießspiegels und somit zu Qualitätseinbußen im gegossenen Strang führen.The controller design in continuous casting is difficult because the Control system parameters, i.e. the casting apparatus and the Chill, are sometimes subject to strong fluctuations or Influencing disturbances on the mold level. As shown in FIG 1 liquid metal flows in during continuous casting Immersion tube with outlet opening in the mold. The inflow liquid Metal over the dip tube into the mold is over a Plug affected. Especially with ferritic steels there is deposits on the stopper or in the area of the dip tube, thereby reducing the inflow. This slow Interference can be easily controlled of the mold level can be compensated. Thereby the regulation the opening according to the extent of the deposits elevated. However, if these deposits break off, it happens a sudden increase in the inflow of liquid metal into the mold. It has been shown that such erratic Changes in the flow of liquid metal into the mold too high increases in the mold level and thus too Loss of quality in the cast strand.

Entsprechend ist es Aufgabe der Erfindung, ein Verfahren bzw. eine Einrichtung zum Gießen eines Stranges aus flüssigem Metall mittels einer Kokille anzugeben, mittels dessen bzw. mittels derer die Auswirkungen auf den Gießspiegel durch Abbrüche von Ablagerungen, z.B. am Stopfen oder im Bereich des Tauchrohres verringert werden.Accordingly, it is an object of the invention to provide a method or a device for casting a strand of liquid metal by means of a mold, by means of which by means of which the effects on the mold level by chipping of deposits, e.g. on the stopper or in the area of the Dip tube can be reduced.

Die Aufgabe wird erfindungsgemäß durch ein Verfahren gemäß den Ansprüchen 1 bis 7 sowie eine Einrichtung gemäß den Ansprüchen 8 bis 12 gelöst. Dabei wird zum Gießen eines Stranges flüssiges Metall in eine Kokille gegossen und als Strang aus der Kokille herausgezogen, wobei der Gießspiegel, d.h. der Stand des flüssigen Metalls in der Kokille, mittels eines Gießspiegelreglers auf einen vorgegebenen Gießspiegel-Sollwert geregelt wird. Der Gießspiegelregler gibt einen Regelausgangswert aus, der in Abhängigkeit eines vorgegebenen Zusatzwerts gebildet ist, wobei der Zusatzwert ausgegeben wird, wenn die Differenz zwischen Gießspiegel-Istwert und Gießspiegel-Sollwert einen Toleranzwert überschreitet, wobei mehrere gestaffelte Toleranzwerte vorgesehen sind, mit denen die Differenz zwischen Gießspiegel-Istwert und Gießspiegel-Sollwert verglichen wird, denen jeweils ein spezifischer Zusatzwert zugeordnet ist, und wobei bei einer festgestellten Oberschreitung eines Toleranzwertes dessen spezifischer Zusatzwert ausgegeben wird. Nach einer vorteilhaften Ausbildung der Erfindung wird der jeweilige Zusatzwert zum Regelausgangswert des Gießspiegelreglers addiert oder der Zusatzwert ersetzt den Regelausgangswert des Gießspiegelreglers. The object is achieved according to the invention by a method claims 1 to 7 and a device according to the claims 8 to 12 solved. This is used to cast a strand poured liquid metal into a mold and as a strand pulled out of the mold, the casting level, i.e. the level of the liquid metal in the mold, by means of a Casting level controller to a predetermined casting level setpoint is regulated. The mold level controller gives a control output value depending on a given additional value is formed, the additional value being output, if the difference between the actual level and the target level exceeds a tolerance value, with several staggered tolerance values are provided with which the difference between the actual level and the target level is compared, each with a specific additional value is assigned, and in the case of a detected excess of a tolerance value its specific additional value is issued. After an advantageous training of Invention, the respective additional value becomes the control output value of the slurry level regulator added or the additional value replaced the standard output value of the slurry level controller.

Die Aufgabe wird besonders vorteilhaft dadurch gelöst, daß zum Gießen eines Stranges flüssiges Metall in eine Kokille gegossen und als Strang aus der Kokille herausgezogen wird, wobei der Gießspiegel, d.h. der Stand des flüssigen Metalls in der Kokille, mittels eines Gießspiegelreglers mit zumindest einem Integrator auf einen vorgegebenen Gießspiegel-Sollwert geregelt wird, und wobei die Differenz zwischen Gießspiegel-Istwert und Gießspiegel-Sollwert vorteilhafterweise überwacht wird. Der Ausgang des Integrators des Gießspiegelreglers wird durch einen vorgegebenen Zusatzwert ersetzt, wenn die Differenz zwischen Gießspiegel-Istwert und Gießspiegel-Sollwert eine Toleranzschwelle überschreitet. Unter Ergänzen in diesem Sinne ist zu verstehen, daß der Ausgang des Integrators durch den Zusatzwert ersetzt wird, oder daß in besonders vorteilhafter Weise der Zusatzwert zum Integratorausgang hinzuaddiert wird, wobei die Summe aus Zusatzwert und bisherigem Ausgangswert des Integrators den neuen Ausgangswert des Integrators bildet.The task is solved particularly advantageously in that for pouring a strand of liquid metal into a mold poured and pulled out of the mold as a strand, where the mold level, i.e. the level of the liquid metal in the mold, by means of a slurry level controller with at least an integrator to a predetermined casting level setpoint is regulated, and being the difference between Casting level actual value and casting level setpoint advantageously is monitored. The output of the integrator of the slurry level controller is replaced by a predetermined additional value, if the difference between the actual level and Casting level setpoint exceeds a tolerance threshold. Under Supplement in this sense is to be understood as the exit of the integrator is replaced by the additional value, or that in a particularly advantageous manner the additional value to the integrator output is added, the sum of the additional value and the previous output value of the integrator is the new one Output value of the integrator forms.

In besonders vorteilhafter Ausgestaltung der Erfindung wird die Toleranzschwelle, insbesondere in Abhängigkeit der Standardabweichung der Differenz zwischen Gießspiegel-Istwert und Gießspiegel-Sollwert oder einer der Standardabweichung äquivalenten Größe, an den Gießprozeß adaptiert. Auf diese Weise ist es möglich, Gießspiegelschwankungen durch mögliches fehlerhaftes Erkennen eines Abbruchs, obwohl kein Abbruch vorliegt, zu verhindern.In a particularly advantageous embodiment of the invention the tolerance threshold, especially depending on the standard deviation the difference between the actual level and Casting level setpoint or one of the standard deviation equivalent Size, adapted to the casting process. In this way it is possible to have mold level fluctuations due to possible faulty Detection of a termination even though there is no termination, to prevent.

In weiterhin vorteilhafter Ausgestaltung der Erfindung wird die Toleranzschwelle auf einen Wert zwischen 0,02 und 0,1, zwischen 0,04 und 0,1 und/oder zwischen 0,06 und 0,1 begrenzt. Auf diese Weise wird die Stabilität eines erfindungsgemäßen Verfahrens erhöht. In a further advantageous embodiment of the invention the tolerance threshold to a value between 0.02 and 0.1, limited between 0.04 and 0.1 and / or between 0.06 and 0.1. In this way, the stability of an inventive Procedure increased.

Weitere Vorteile und Einzelheiten ergeben sich aus der nachfolgenden Beschreibung von Ausführungsbeispielen. Im einzelnen zeigen:

FIG 1
eine Anordnung zum Stranggießen,
FIG 2
ein Ausführungsbeispiel der Erfindung,
FIG 3
ein besonders vorteilhaftes Ausführungsbeispiel der Erfindung,
FIG 4
ein Ausführungsbeispiel für eine Abbruchvorsteuerung gemäß FIG 2,
FIG 5
ein besonders vorteilhaftes Ausführungsbeispiel für eine Abbruchvorsteuerung gemäß FIG 3.
Further advantages and details emerge from the following description of exemplary embodiments. In detail show:
FIG. 1
an arrangement for continuous casting,
FIG 2
an embodiment of the invention,
FIG 3
a particularly advantageous embodiment of the invention,
FIG 4
1 shows an exemplary embodiment for an abort pre-control according to FIG. 2,
FIG 5
A particularly advantageous embodiment for a pre-termination control according to FIG. 3.

In einer beispielhaften Anordnung gemäß FIG 1 wird flüssiges Metall 13, in diesem Falle Stahl, in eine Verteilerrinne 7 gegossen. Aus der Verteilerrinne 7 fließt das flüssige Metall über ein Tauchrohr 5 mit Auslaßöffnung 6 in die Kokille 3. In der Kokille 3 bildet sich aus dem flüssigen Metall ein Strang 1, der über Rollen 4 aus der Kokille 3 herausgezogen wird. Der Zufluß flüssigen Metalls 13 über das Tauchrohr 5 in die Kokille 3 wird über einen Stopfen 8 beeinflußt, der über eine Mechanik 9, die einen Tragarm und eine Hubstange aufweist, bewegt wird. Die Hubstange wird wiederum durch einen Hydraulikzylinder 10 angetrieben, der über ein Automatisierungsgerät 12 in Abhängigkeit einer Hydraulikzylinder-Stellgröße S gesteuert bzw. geregelt wird. Die Position der Hubstange und damit die Stopfen-Position h wird mittels eines Positionsmeßgerätes 15 gemessen und an das Automatisierungsgerät 12 übertragen. Außerdem weist die Anordnung ein Gießspiegelmeßgerät 11 auf, das den Gießspiegel g, d.h. den Stand flüssigen Metalls in der Kokille 3 mißt. Das Gießspiegelmeßgerät 11 ist ebenso wie das Positionsmeßgerät 15 und der Hydraulikzylinder 10 datentechnisch mit dem Automatisierungsgerät 12 verbunden. Das Automatisierungsgerät 12 regelt den Gießspiegel g. Der aus der Kokille 3 herausgezogene Strang 1 weist eine Sumpfspitze, d. h. einen flüssigen Kern 2, und eine erstarrte Hülle 14 auf.In an exemplary arrangement according to FIG. 1, liquid Metal 13, in this case steel, into a distribution channel 7 cast. The liquid metal flows from the distribution channel 7 via a dip tube 5 with outlet opening 6 into the mold 3. In the mold 3 forms a strand from the liquid metal 1, which is pulled out of the mold 3 via rollers 4. The inflow of liquid metal 13 through the dip tube 5 in the Chill mold 3 is influenced by a plug 8 which has a Mechanism 9, which has a support arm and a lifting rod, is moved. The lifting rod is in turn powered by a hydraulic cylinder 10 driven by an automation device 12 depending on a hydraulic cylinder manipulated variable S is controlled or regulated. The position of the lifting rod and so that the stopper position h is by means of a position measuring device 15 measured and to the automation device 12 transfer. In addition, the arrangement has a mold level measuring device 11, which the casting level g, i. the stand liquid Measures metal in the mold 3. The mold level measuring device 11 is as well as the position measuring device 15 and the hydraulic cylinder 10 technically connected to the automation device 12. The automation device 12 controls the mold level g. The strand 1 pulled out of the mold 3 has a sump tip, d. H. a liquid core 2, and a solidified shell 14 on.

FIG 2 zeigt ein Ausführungsbeispiel der Erfindung. Zur Regelung des Gießspiegels g sind ein Gießspiegelregler 20 und ein Stopfenpositionsregler 23 vorgesehen. Der Gießspiegelregler 20 weist ein P-Glied 21 sowie einen Integrator 22 auf. Der Gießspiegelregler 20 ermittelt einen Stopfen-Positionssollwert h* in Abhängigkeit der Differenz von einem Gießspiegel-Sollwert g* und dem Gießspiegel g. Der Stopfenpositionsregler 23 ermittelt eine Stellgröße s für den Hubzylinder 10 in Abhängigkeit einer Stopfen-Positionsregeldifferenz Δh. Die Stopfen-Positionsregeldifferenz Δh ist die Differenz aus Stopfen-Positionssollwert h* und der Stopfen-Position h.2 shows an embodiment of the invention. For regulation of the casting level g are a level control 20 and a Plug position controller 23 is provided. The slurry level regulator 20 has a P element 21 and an integrator 22. The Casting level controller 20 determines a stopper position setpoint h * as a function of the difference from a set level g * and the casting mirror g. The stopper positioner 23 determines a manipulated variable s for the lifting cylinder 10 as a function of a stopper position control difference Δh. The Plug position control difference Δh is the difference Stopper position setpoint h * and stopper position h.

Zur Kompensation von Abbrüchen von Ablagerungen an Stopfen 8 bzw. von Ablagerungen im Bereich des Tauchrohrs 5 ist eine Abbruchvorsteuerung 24 vorgesehen. Die Abbruchvorsteuerung ermittelt in Abhängigkeit der Regelabweichung Δg einen Zusatzwert c. In besonders vorteilhafter Ausgestaltung ist vorgesehen, daß in einem Abtastschritt der Ausgang des Integrators 22 um den Zusatzwert c ergänzt und neu gesetzt wird, wenn die negative Regelabweichung -Δg einen bestimmten Toleranzwert überschreitet. Die Regelabweichung Δg ist die Differenz aus Gießspiegel-Sollwert g* und Gießspiegel-Istwert g.To compensate for breakage of deposits on plugs 8 or of deposits in the area of the dip tube 5 is one Abort pre-control 24 is provided. The termination pre-control determines an additional value depending on the control deviation Δg c. In a particularly advantageous embodiment, that in one sampling step the output of the integrator 22 is supplemented by the additional value c and set again, if the negative control deviation -Δg a certain tolerance value exceeds. The control deviation Δg is the difference from the set level g * and the set level g.

FIG 3 zeigt ein besonders vorteilhaftes Ausführungsbeispiel der Erfindung. Dabei sind anstelle der Abbruchvorsteuerung 24 in FIG 2 eine Abbruchvorsteuerung 25 sowie ein Statistikblock 26 vorgesehen. Die Abbruchvorsteuerung 24 und die Abbruchvorsteuerung 25 unterscheiden sich im wesentlichen dadurch, daß die Toleranzschwellen gemäß der Abbruchvorsteuerung 25 in Abhängigkeit der Standardabweichung σ der Regelabweichung Δg über ein bestimmtes Zeitfenster ermittelt werden. Anstelle der Standardabweichung σ kann jedoch auch eine äquivalente Größe verwendet werden. Die Standardabweichung σ wird mittels des Statistikblocks 26 ermittelt, der im vorliegenden Ausführungsbeispiel ein Standardabweichungsbildner über ein bestimmtes Zeitfenster ist. Er kann jedoch durch komplexere statistische Funktionsbausteine, sowie Fuzzy-Logic oder neuronale Netze ersetzt werden.3 shows a particularly advantageous exemplary embodiment the invention. In this case, instead of the pre-termination 24 in FIG. 2 an abort feedforward control 25 and a statistical block 26 provided. Abort pre-control 24 and abort pre-control 25 differ essentially in that the tolerance thresholds as a function of the abort feedforward control 25 the standard deviation σ the control deviation Δg can be determined over a certain time window. Instead of the standard deviation σ can also be an equivalent Size can be used. The standard deviation σ is calculated using of the statistical block 26 determined in the present embodiment a standard deviation generator about a particular one Time window is. However, it can be more complex statistical function blocks, as well as fuzzy logic or neuronal Nets to be replaced.

FIG 4 zeigt ein einfaches Ausführungsbeispiel für eine Abbruchvorsteuerung 24 gemäß FIG 2. Diese weist einen Negierer 30 zum Negieren der Regelabweichung Δg auf. Ferner weist die Abbruchvorsteuerung einen Toleranzwertprüfer 31, ein Halteglied 32 sowie einen Schalter 33 auf. Der Toleranzwertprüfer 31 prüft, ob die negative Regelabweichung -Δg einen bestimmten Toleranzwert überschreitet. Detektiert der Toleranzwertprüfer 31, daß die negative Regelabweichung -Δg einen bestimmten Toleranzwert überschreitet, so schließt das Halteglied 32 den Schalter 33 für einen Abtastschritt. In diesem Abtastschritt gibt die Abbruchvorsteuerung 24 einen Zusatzwert c aus. Wenn die Abtastvorsteuerung 24 einen Zusatzwert c ausgibt, so wird der Ausgangswert des Integrators 22 in FIG 2 um den Zusatzwert c ergänzt und neu gesetzt. In vorteilhafter nicht dargestellter Ausgestaltung der Abbruchvorsteuerung 24 setzt sich der Zusatzwert c aus mehreren gestaffelten Werten c1, c2, c3 zusammen, wie dies beispielhaft in FIG 5 ausgeführt ist. Durch eine derartige Staffelung von Toleranzschwellen werden die Auswirkungen von Abbrüchen auf den Gießspiegel besonders stark gemindert.FIG. 4 shows a simple exemplary embodiment for an abort pre-control 24 according to FIG. 2. This has a negator 30 for negating the control deviation Δg. Furthermore, the abort pre-control has a tolerance value checker 31, a holding element 32 and a switch 33. The tolerance value checker 31 checks whether the negative control deviation -Δg exceeds a certain tolerance value. If the tolerance value checker 31 detects that the negative control deviation -Δg exceeds a certain tolerance value, the holding element 32 closes the switch 33 for one scanning step. In this sampling step, the abort pre-control 24 outputs an additional value c. If the scan pre-control 24 outputs an additional value c, the output value of the integrator 22 in FIG. 2 is supplemented by the additional value c and reset. In an advantageous embodiment of the pre-control 24, not shown, the additional value c is composed of a plurality of staggered values c 1 , c 2 , c 3 , as is exemplified in FIG. 5. By staggering tolerance thresholds in this way, the effects of abortions on the mold level are particularly greatly reduced.

FIG 5 zeigt ein besonders vorteilhaftes Ausführungsbeispiel für eine Abbruchvorsteuerung gemäß FIG 3. Die besonders vorteilhafte Ausgestaltung der Abbruchvorsteuerung 25 weist einen Negierer 30, Halteglieder 32, Toleranzwertprüfer 40, 41, 42, P-Glieder 43, 44, 45, mit den Verstärkungen K3, K2, K1, Begrenzer 46, 47, 48 sowie Schalter 49, 50 und 51 auf. Gemäß dieser Ausgestaltung der Abbruchvorsteuerung 25 sind für die Toleranzwertprüfer 40, 41, 42 Toleranzwerte vorgesehen, die an den Gießprozeß vorteilhafterweise adaptiert werden. Dazu wird die Standardabweichung σ mittels der P-Glieder 43, 44, 45 mit einer Verstärkung K3, K2, K1 multipliziert und anschließend durch die Begrenzer 46, 47, 48 begrenzt. Der Ausgangswert der Begrenzer 46, 47, 48 ist der Toleranzwert, der in dem Toleranzwertprüfer 40, 41, 42 verwendet wird. In den Toleranzwertprüfern 40, 41, 42 wird überprüft, ob die negative Regelabweichung -Δg diesen Toleranzwert überschreitet. Ermittelt einer der Toleranzwertprüfer 40, 41, 42 das Überschreiten seines Toleranzwertes durch die negative Regelabweichung -Δg, so schließt das entsprechende Halteglied 32 den entsprechenden Schalter 49, 50, 51. Entsprechend der Kombination von geschlossenen Schaltern 49, 50, 51 wird ein Zusatzwert c ausgegeben. Liegt ein Zusatzwert c an, so wird der Ausgang des Integrators 22 in FIG 3 in diesem Abtastschritt um den Zusatzwert c ergänzt und neu gesetzt.5 shows a particularly advantageous embodiment for a termination pilot control in accordance with FIG 3. The particularly advantageous embodiment of the breakaway pilot control 25 includes a negator 30, holding members 32, tolerance tester 40, 41, 42, P-members 43, 44, 45, with the gains K 3 , K 2 , K 1 , limiter 46, 47, 48 and switches 49, 50 and 51 on. According to this embodiment of the pre-control 25, tolerance values are provided for the tolerance value checkers 40, 41, 42, which are advantageously adapted to the casting process. For this purpose, the standard deviation σ is multiplied by the P terms 43, 44, 45 by a gain K 3 , K 2 , K 1 and then limited by the delimiters 46, 47, 48. The output value of the limiters 46, 47, 48 is the tolerance value that is used in the tolerance value checker 40, 41, 42. In the tolerance value checkers 40, 41, 42 it is checked whether the negative control deviation -Δg exceeds this tolerance value. If one of the tolerance value checkers 40, 41, 42 determines that its tolerance value has been exceeded by the negative control deviation -Δg, the corresponding holding element 32 closes the corresponding switch 49, 50, 51. According to the combination of closed switches 49, 50, 51, an additional value c output. If an additional value c is present, the output of the integrator 22 in FIG. 3 is supplemented by the additional value c in this sampling step and reset.

Claims (12)

  1. Method for casting a billet (1) of liquid metal which is cast into a mould (3) and is drawn out of the mould as a billet, the casting level (g), that is to say the level of liquid metal in the mould (3), being regulated to a predetermined casting-level desired value (g*) by means of a casting-level controller (20), the casting-level controller (20) issuing an initial regulating value which is formed as a function of a predetermined additional value, the additional value being issued when the difference (Δg) between the casting-level actual value (g) and casting-level desired value (g*) exceeds a tolerance value, characterized in that a plurality of staggered tolerance values are provided, with which the difference (Δg) between the casting-level actual value (g) and the casting-level desired value (g*) is compared and to which a specific additional value (c1, c2, c3) is assigned in each case, and, when the exceeding of a tolerance value is detected, the specific additional value (c1, c2, c3) of the latter is issued.
  2. Method according to Claim 1, characterized in that the respective additional value is added to the initial regulating value of the casting-level controller (20), or in that the additional value replaces the initial regulating value of the casting-level controller (20).
  3. Method according to Claim 1 or 2, characterized in that the initial regulating value of the casting-level controller (20) is supplied by an integrator (22).
  4. Method according to one of the preceding claims, characterized in that a tolerance value is determined as a function of the standard deviation (σ) of the difference (Δg) between the casting-level actual value (g) and the casting-level desired value (g*).
  5. Method according to one of the preceding claims, characterized in that the tolerance value is limited to a value of between 0.02 and 0.1.
  6. Method according to one of the preceding claims, characterized in that the tolerance value is limited to a value of between 0.04 and 0.1.
  7. Method according to one of the preceding claims, characterized in that the tolerance value is limited to a value of between 0.06 and 0.1.
  8. Device for carrying out the method according to one of Claims 1 to 7 for casting a billet (1) of liquid metal which is cast into a mould (3) and is drawn out of the mould as a billet, the device for casting the billet (1) having a casting-level controller (20) for regulating the casting level (g), that is to say the level of liquid metal in the mould (3), said casting-level controller issuing an initial regulating value formed as a function of an additional value which is issued when the difference (Δg) between the casting-level actual value (g) and casting-level desired value (g*) exceeds a tolerance value, characterized in that, to issue the additional value, a termination pilot control (24, 25) is provided, which is designed to compare the difference (Δg) between the casting-level actual value (g) and casting-level desired value (g*) with a plurality of staggered tolerance values and to issue the respective additional value (c1, c2, c3) assigned to a tolerance value when the difference exceeds a defined tolerance value.
  9. Device according to Claim 8, characterized in that the termination pilot control (24, 25) is designed to add the additional value to the initial regulating value or to replace the initial regulating value by the additional value.
  10. Device according to Claim 8 or 9, characterized in that the casting-level controller (20) has an integrator (22) supplying the initial regulating value.
  11. Device according to one of Claims 8 to 10, characterized in that the termination pilot control (24, 25) is designed to determine a tolerance value as a function of the standard deviation (σ) of the difference (Δg) between the casting-level actual value (g) and casting-level desired value (g*).
  12. Device according to Claim 11, characterized in that a statistics block (26) is provided for determining the standard deviation (σ).
EP99948676A 1998-08-05 1999-07-23 Method and device for casting a strand of liquid metal Expired - Lifetime EP1100639B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19835421A DE19835421C2 (en) 1998-08-05 1998-08-05 Method and device for casting a strand of liquid metal
DE19835421 1998-08-05
PCT/DE1999/002273 WO2000007756A1 (en) 1998-08-05 1999-07-23 Method and device for casting a strand of liquid metal

Publications (2)

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EP1100639A1 EP1100639A1 (en) 2001-05-23
EP1100639B1 true EP1100639B1 (en) 2002-11-06

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EP99948676A Expired - Lifetime EP1100639B1 (en) 1998-08-05 1999-07-23 Method and device for casting a strand of liquid metal

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US (1) US6505676B1 (en)
EP (1) EP1100639B1 (en)
KR (1) KR100621266B1 (en)
AT (1) ATE227182T1 (en)
DE (2) DE19835421C2 (en)
WO (1) WO2000007756A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101837368B (en) * 2010-04-27 2012-02-01 新星化工冶金材料(深圳)有限公司 Continuous casting and rolling molding method for magnesium alloy plate
CN101862819B (en) * 2010-06-18 2011-05-11 新星化工冶金材料(深圳)有限公司 Control mechanism capable of automatically adjusting height of liquid level and magnesium alloy plate continuously-casting system thereof

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4597048A (en) * 1983-09-07 1986-06-24 United States Steel Corporation Digital flow regulation of liquid-level control for a continuous casting mold
JPH04339552A (en) 1991-05-16 1992-11-26 Sumitomo Metal Ind Ltd Method for controlling molten steel surface level in continuous caster
CA2094029C (en) 1991-09-12 1997-04-29 Kazuya Asano Molten metal level control method and device for continuous casting
JPH07232252A (en) 1993-12-27 1995-09-05 Kawasaki Steel Corp Method for controlling molten metal level in mold in continuous casting
JPH08243703A (en) * 1995-03-14 1996-09-24 Kawasaki Steel Corp Method for controlling molten metal surface level in continuous casting
EP0798061A4 (en) * 1995-10-18 1999-06-30 Sumitomo Metal Ind Method for controlling the level of molten metal for a continuous casting machine
DE19633738C5 (en) * 1996-08-22 2006-03-09 Siemens Ag Method and device for casting a strand of liquid metal

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DE59903333D1 (en) 2002-12-12
EP1100639A1 (en) 2001-05-23
WO2000007756A1 (en) 2000-02-17
ATE227182T1 (en) 2002-11-15
KR100621266B1 (en) 2006-09-13
DE19835421C2 (en) 2001-11-15
US6505676B1 (en) 2003-01-14
KR20010053632A (en) 2001-06-25
DE19835421A1 (en) 2000-02-24

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