EP0907442A1 - Process for optimising surface quality of continuous castings - Google Patents

Process for optimising surface quality of continuous castings

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Publication number
EP0907442A1
EP0907442A1 EP97922831A EP97922831A EP0907442A1 EP 0907442 A1 EP0907442 A1 EP 0907442A1 EP 97922831 A EP97922831 A EP 97922831A EP 97922831 A EP97922831 A EP 97922831A EP 0907442 A1 EP0907442 A1 EP 0907442A1
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EP
European Patent Office
Prior art keywords
strand
mold
casting
path
friction
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP97922831A
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German (de)
French (fr)
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EP0907442B1 (en
Inventor
Fritz-Peter Pleschiutschnigg
Lothar Parschat
Hans Günter THURM
Hans Uwe Franzen
Gerd-Joachim Deppe
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SMS Siemag AG
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Mannesmann AG
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Publication date
Application filed by Mannesmann AG filed Critical Mannesmann AG
Publication of EP0907442A1 publication Critical patent/EP0907442A1/en
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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
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/165—Controlling or regulating processes or operations for the supply of casting powder
    • 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
    • B22D11/166—Controlling or regulating processes or operations for mould oscillation

Definitions

  • the present invention relates to a method for optimizing the strand surface quality of steel strands produced in a casting plant.
  • the strand When casting steel strands in continuous casting plants, the strand is generally discharged at a constant take-off speed.
  • the level of the casting level in the mold is kept constant by regulating the inflow of the melt from the distributor.
  • a suitable hydraulic mold drive system is known from DE 35 43 790 C2.
  • the design and quality of the strand surface it is known (see, for example, "Stahl u. Eisen” 108 (1988) No. 3, pages 1125 to 1127) that, in the case of oscillating continuous casting molds, the casting powder used to form a lubricating film between the mold wall and strand shell is of great importance. Attempts have therefore also been made (Stahl and Eisen 107 (1987) No. 14, 15, pages 673 to 677) to obtain information about the behavior of the strand in the mold by measuring the pull-out force during the starting process. For this purpose, a correspondingly designed force measuring device was installed in the cold strand. Of course, this procedure is only suitable for checking during the start-up process. This measurement method cannot be used during the actual operating phase.
  • z. B. caused by oscillation parameters (stroke height, stroke frequency, curve shape) as well as the steel quality itself, the strand withdrawal speed, the cooling conditions and the steel temperature and also the type of strand guidance, especially when casting rolls are important, can only be compared by comparing the mold oscillation profiles in idle operation do not draw any immediate conclusions from the foundry that would be likely to intervene in the foundry.
  • the strand speed in the mold is assumed to be a uniform speed, probably due to the fact that the strand withdrawal is also accomplished by means of uniformly rotating rollers.
  • the actual strand speed is significantly influenced by the friction in the mold. This can be seen from the up and down movement of the strand, which can sometimes be seen with the naked eye (see Stahl and Eisen (1987), No. 14, 15, pages 673 to 677. It is known from DE 38 06 583 A1, to detect the course of movement of the strand in an area as soon as possible after leaving the mold, the measurement signals being fed through a diode line camera to an evaluation unit or a display unit of the line or system and to adjust the driving style of the entire system so that critical areas are avoided.
  • the aim of the invention is to find an improvement in the known measuring methods which allows a direct influence on controllable operating parameters to improve the surface quality.
  • the actual path of the line and thus the time course of the speed are measured with high accuracy.
  • the actual relative speed obtained from this is then compared with other influencing variables which have also been recorded and is related to one another using a suitable correlation method, essentially using a multiple influencing quantity calculation.
  • the measuring method provides the temporal progression of the line path as original information.
  • the time course of the relative path or the relative speed to the nominal path or to the nominal speed is formed by forming the difference with an averaged path.
  • a control signal for changing the composition of the casting powder in the sense of a reduction in the coefficient of friction and / or the mold oscillation is formed from the deviation from the actual and target value.
  • Linking with the cylinder force of the drive determines the friction work or the frictional power in the drive system of the mold lifting table, and influencing variables are optimized according to the given target values.
  • a closed control loop is built up using the correlation relationships found and influence is exerted on the target variable surface contour "e.g. casting mark depth and casting mark distance.
  • the signal for changing the mold oscillation of a control unit of the oscillation drive is in the manner switched on that the motion impulse transmitted from the mold to the strand is as small as possible or is close to zero.
  • a measured value it is proposed to use the measured value formed from the differential pressure in the hydraulic cylinder between idling and the operating state in the hydraulic drive. This value can be obtained from a mechanical system using a load cell.
  • the strand lubrication has a great influence on the coefficient of friction.
  • the casting powder should be changed in such a way that the coefficient of friction is reduced.
  • Fig. 2 shows a typical expression
  • Fig. 3 shows the variations in the path curves of the strand.
  • Fig. 1 shows a strand 11, which leaves a mold 12 and is guided by rollers 14.
  • the mold 12 is connected to a mold powder feed, which is connected to mold powder container 15 via barriers 16.
  • the mold powder feed 17 is also guided through a heating device 18.
  • a sensor is provided on the narrow side of the strand 11, here a diode line camera which detects the diode lines of the strand, the alignment of the camera being the same as the casting direction.
  • the diode line camera 21 is connected via a measuring line 28 to the measuring receptacle 22 for the strand movement with respect to the distance 24 and speed 23.
  • the signals relating to the change in line speed and line path are fed to a computer 26 and possibly a display device 25, possibly a printer.
  • the computer 26 is regularly connected to a gate valve 31 with a control component 32 with actuators 16, gate valves of the mold powder container 15 and via a control component 33 with the heating device 18 for the mold powder.
  • the computer 26 is also linked via a control line 34 to a control component 35 for controlling the oscillation 13.
  • Fig. 2 shows a typical expression of detected measurement signals.
  • the upper part shows a section of the average mold speed, which in the given example oscillates according to a sine curve.
  • the average strand speed of the entire strand is shown and the actual speed of the strand shown in the area immediately below the mold is superimposed on it. This can be clearly seen depending on the friction and, if necessary, brief sticking of the strand shell to the inner wall of the mold of the strand near the mold.
  • the sine curve below shows the actual path of the mold. The actual path of the strand near the mold is shown below.
  • Both the recording of the line speed and the line path are measured values and not calculated values.
  • the curve shown is an example and shows characteristic actual shapes with evaluable points. From the arrangement of the minima, maxima and the turning points, the person skilled in the art is able to draw conclusions about the actual behavior of the strand shell in the mold. For the assessment, he uses the position of the strand at times T with the curve shapes at points A. The distance S is the direct derivative of the speed V. 3 shows variations of the strand path. Note the radii of curvature of the individual curves at points A and any changes of direction that may exist. By influencing the oscillation of the mold and the casting powder, the design of the actual path of the strand is influenced.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Casting Devices For Molds (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
  • General Factory Administration (AREA)
  • Formation And Processing Of Food Products (AREA)
  • Mold Materials And Core Materials (AREA)

Abstract

The invention relates to a process in a casting mill for producing continuous castings, in particular continuously cast steel, in which the movement of the casting is determined and modified. The invention is characterised by the following process steps: (a) the melt surface is covered with a casting powder which forms a liquid slag to produce a lubricating film between the casting outer shell and the mould inner wall; (b) a measured value characterising the friction between the casting outer shell and mould inner wall is determined in the oscillation device and forwarded to the evaluation unit (in the form of a computer); (c) the signal which characterises the path-time behaviour of the casting is likewise forwarded to the computer; (d) the computer correlates and links the measured values or signals for the path-time behaviour of the casting and the friction of the casting in the mould to produce comparable values and compares them to a reference value; (e) the reference value is determined as a mean value of the casting speed from the path-time behaviour of the casting; (f) from the discrepancy between actual and reference values, a signal is generated to adjust the casting powder composition in order to reduce friction and/or mould vibration.

Description

„Verfahren zur Optimierung der Strangoberflächenqualität""Process for Optimizing the Strand Surface Quality"
Die vorliegende Erfindung bezieht sich auf ein Verfahren zur Optimierung der Strangoberflächenqualität von in einer Gießanlage erzeugten Stahlsträngen.The present invention relates to a method for optimizing the strand surface quality of steel strands produced in a casting plant.
Beim Gießen von Stahlsträngen in kontinuierlichen Gießanlagen wird der Strang im allgemeinen mit einer konstanten Abzugsgeschwindigkeit ausgefördert. Das Niveau des Gießspiegels in der Kokille wird durch Regelung des Zulaufes der Schmelze aus dem Verteiler konstant gehalten. Einige Gießanlagen, insbesondere Knüppel- oder Bioomanlagen, gießen mit konstantem Zulauf der Schmelze aus dem Verteiler und regeln das Niveau in der Kokille durch Veränderung der Strangabzugsgeschwindigkeit. Diese beiden Maßnahmen sind dem Fachmann derart geläufig, daß es eines besonderen Literaturnachweises nicht bedarf.When casting steel strands in continuous casting plants, the strand is generally discharged at a constant take-off speed. The level of the casting level in the mold is kept constant by regulating the inflow of the melt from the distributor. Some casting plants, in particular billet or bio-plants, pour from the distributor with a constant inflow of melt and regulate the level in the mold by changing the strand withdrawal speed. These two measures are so familiar to the person skilled in the art that a special literature reference is not required.
In beiden vorgenannten Fällen, im ersten etwas einfacher als im zweiten, werden zur Feststellung von Anomalien im Umfeld der Kokille Versuche zur Messung der Reibungsverhältnisse zwischen Strang und Kokille gemacht. Diese Messungen sind so aufgebaut, daß die für die Kokillenbewegung erforderliche Kraft während des Gießens gemessen und den im Leerlauf auftretenden Kräften gegenübergestellt wird. Dabei werden bisher sowohl mechanisch als auch hydraulisch angetriebene Kokillen- Oszillationsantriebe verwendet und untersucht. Für einen mechanischen Kokillenantrieb sind derartige Systeme aus "Concast Standard News", Volume 30, 1/1991 , Seite 4 bis 5, bekannt.In both of the aforementioned cases, somewhat simpler in the first than in the second, attempts are made to determine the anomalies around the mold in order to measure the frictional relationships between the strand and the mold. These measurements are constructed in such a way that the force required for the mold movement is measured during casting and compared with the forces that occur during idling. So far, both mechanically and hydraulically driven mold oscillation drives have been used and investigated. For a mechanical mold drive, such systems are known from "Concast Standard News", Volume 30, 1/1991, pages 4 to 5.
Ein geeignetes hydraulisches Kokillenantriebssystem ist aus der DE 35 43 790 C2 bekannt. Hinsichtlich der Ausbildung und Qualität der Strangoberfläche ist es bekannt (s. zum Beispiel "Stahl u. Eisen" 108 (1988) Nr. 3, Seiten 1125 bis 1127), daß bei oszillierenden Stranggießkokillen dem zur Anwendung gelangenden Gießpulver zur Bildung eines Schmierfilms zwischen Kokillenwand und Strangschale eine große Bedeutung zukommt. Man hat daher auch versucht (Stahl u. Eisen 107 (1987) Nr. 14, 15, Seite 673 bis 677) Aufschluß über das Verhalten des Stranges in der Kokille durch Messung der Ausziehkraft beim Anfahrvorgang zu erhalten. Hierzu wurde eine entsprechend ausgebildete Kraftmeßeinrichtung in den Kaltstrang eingebaut. Dieses Verfahren eignet sich natürlich nur für eine Überprüfung während des Anfahrvorganges. Während der eigentlichen Betriebsphase ist die Anwendung dieser Meßmethode nicht möglich.A suitable hydraulic mold drive system is known from DE 35 43 790 C2. With regard to the design and quality of the strand surface, it is known (see, for example, "Stahl u. Eisen" 108 (1988) No. 3, pages 1125 to 1127) that, in the case of oscillating continuous casting molds, the casting powder used to form a lubricating film between the mold wall and strand shell is of great importance. Attempts have therefore also been made (Stahl and Eisen 107 (1987) No. 14, 15, pages 673 to 677) to obtain information about the behavior of the strand in the mold by measuring the pull-out force during the starting process. For this purpose, a correspondingly designed force measuring device was installed in the cold strand. Of course, this procedure is only suitable for checking during the start-up process. This measurement method cannot be used during the actual operating phase.
Da für die Ausbildung der Strangoberfläche neben der Art der Schmierung zwischen Kokille und Strangschale auch Veränderungen innerhalb der Kokille, z. B. hervorgerufen durch Oszillationsparameter (Hubhöhe, Hubfrequenz, Kurvenform) sowie die Stahlgüte selbst, die Strangabzugsgeschwindigkeit, die Kühlbedingungen sowie die Stahltemperatur und auch die Art der Strangführung, insbesondere beim Gießwalzen von Bedeutung sind, lassen sich allein aus einem Vergleich der Kokillenoszillationsverläufe im Leerbetrieb gegenüber dem Gießbetrieb keine unmittelbaren Schlüsse ziehen, die geeignet wären in den Gießbetrieb unmittelbar einzugreifen.As for the formation of the strand surface in addition to the type of lubrication between the mold and the strand shell also changes within the mold, z. B. caused by oscillation parameters (stroke height, stroke frequency, curve shape) as well as the steel quality itself, the strand withdrawal speed, the cooling conditions and the steel temperature and also the type of strand guidance, especially when casting rolls are important, can only be compared by comparing the mold oscillation profiles in idle operation do not draw any immediate conclusions from the foundry that would be likely to intervene in the foundry.
Bei all diesen Betrachtungen wird die Stranggeschwindigkeit in der Kokille als gleichförmige Geschwindigkeit angenommen, wahrscheinlich aufgrund der Tatsache, daß auch der Strangabzug mittels gleichförmig umlaufender Walzen bewerkstelligt wird. Die tatsächliche Stranggeschwindigkeit wird jedoch durch die Reibungsverhältnisse in der Kokille wesentlich beeinflußt. Dies ist an einer, zeitweise mit bloßem Auge zu sehenden Auf- und Abbewegung des Stranges erkennbar (s. Stahl u. Eisen (1987), Nr. 14, 15, Seite 673 bis 677. Aus DE 38 06 583 A1 ist es bekannt, den Bewegungsablauf des Stranges in einem Bereich möglichst unmittelbar nach Verlassen der Kokille zu erfassen, wobei die Meßsignale durch eine Diodenzeilenkamera einer Auswerteeinheit oder einer Anzeigeeinheit zugeführt werden. Das aus dieser Schrift bekannte Verfahren dient dazu, Eigenschwingungen des Stranges oder der Anlage zu berücksichtigen und die Fahrweise der gesamten Anlage so einzustellen, daß kritische Bereiche vermieden werden.In all of these considerations, the strand speed in the mold is assumed to be a uniform speed, probably due to the fact that the strand withdrawal is also accomplished by means of uniformly rotating rollers. However, the actual strand speed is significantly influenced by the friction in the mold. This can be seen from the up and down movement of the strand, which can sometimes be seen with the naked eye (see Stahl and Eisen (1987), No. 14, 15, pages 673 to 677. It is known from DE 38 06 583 A1, to detect the course of movement of the strand in an area as soon as possible after leaving the mold, the measurement signals being fed through a diode line camera to an evaluation unit or a display unit of the line or system and to adjust the driving style of the entire system so that critical areas are avoided.
Die Erfindung verfolgt das Ziel, eine Verbesserung der bekannten Meßmethoden zu finden, die eine unmittelbare Einflußnahme auf steuerbare Betriebsparameter zur Verbesserung der Oberflächenbeschaffenheit erlaubt.The aim of the invention is to find an improvement in the known measuring methods which allows a direct influence on controllable operating parameters to improve the surface quality.
Die Erfindung erreicht dieses Ziel durch die kennzeichnenden Merkmale der im Hauptanspruch angegebenen Verfahrensschritte. Weiterentwicklungen der erfindungsgemäßen Lösung sind in den Unteransprüchen enthalten.The invention achieves this goal by the characterizing features of the method steps specified in the main claim. Further developments of the solution according to the invention are contained in the subclaims.
Erfindungsgemäß wird der tatsächliche Weg des Stranges und damit der zeitliche Verlauf der Geschwindigkeit mit hoher Genauigkeit gemessen. Die hieraus gewonnene tatsächliche Relativgeschwindigkeit wird dann mit anderen, ebenfalls erfaßten Einflußgrößen verglichen und mit einem geeigneten Korrelationsverfahren, im wesentlichen mit multipler Einflußgößenrechnung, untereinander in Beziehung gebracht. Das Meßverfahren liefert als Urinformation den zeitlichen Verlauf des Strangweges. Durch Differenzbildung mit einem gemittelten Weg wird der zeitliche Verlauf des Relativweges bzw. der Relativgeschwindigkeit zum Nominalweg bzw. zur Nominalgeschwindigkeit gebildet. Aus der Abweichung vom Ist- und Sollwert wird ein Steuersignal zur Änderung der Gießpulverzusammensetzung im Sinne einer Herabsetzung des Reibungsbeiwertes und/oder der Kokilleπoszillation gebildet.According to the invention, the actual path of the line and thus the time course of the speed are measured with high accuracy. The actual relative speed obtained from this is then compared with other influencing variables which have also been recorded and is related to one another using a suitable correlation method, essentially using a multiple influencing quantity calculation. The measuring method provides the temporal progression of the line path as original information. The time course of the relative path or the relative speed to the nominal path or to the nominal speed is formed by forming the difference with an averaged path. A control signal for changing the composition of the casting powder in the sense of a reduction in the coefficient of friction and / or the mold oscillation is formed from the deviation from the actual and target value.
Durch Verknüpfung mit der Zylinderkraft des Antriebs wird die Reibarbeit bzw. die Reibleistung im Antriebssystem Kokillenhubtisch bestimmt ,und Einflußgrößen werden entsprechend den gegebenen Zielgrößen optimiert.Linking with the cylinder force of the drive determines the friction work or the frictional power in the drive system of the mold lifting table, and influencing variables are optimized according to the given target values.
Durch die One-Iine-Messung wird unter Verwendung der gefundenen Korrelationsbeziehungen ein geschlossener Regelkreis aufgebaut und Einfluß auf die Zielgröße Oberflächenkontur" z.B. Gießmarkentiefe und Gießmarkenabstand genommen.Through the one-line measurement, a closed control loop is built up using the correlation relationships found and influence is exerted on the target variable surface contour "e.g. casting mark depth and casting mark distance.
In einer vorteilhaften Ausgestaltung wird das Signal zur Änderung der Kokillenoszillation einer Steuereinheit des Oszillationsantriebes in der Weise aufgeschaltet, daß der von der Kokille auf den Strang übertragene Bewegungsimpuls möglichst gering ist oder nahe am Wert Null liegt. Als Meßwert wird vorgeschlagen, beim hydraulischen Antrieb den aus dem Differenzdruck im Hydraulikzylinder zwischen Leerlauf und Betriebszustand gebildeten Meßwert zu verwenden. Einer mechanischen Anlage kann dieser Wert durch eine Kraftmeßzelle gewonnen werden.In an advantageous embodiment, the signal for changing the mold oscillation of a control unit of the oscillation drive is in the manner switched on that the motion impulse transmitted from the mold to the strand is as small as possible or is close to zero. As a measured value, it is proposed to use the measured value formed from the differential pressure in the hydraulic cylinder between idling and the operating state in the hydraulic drive. This value can be obtained from a mechanical system using a load cell.
Einfluß auf den Reibwert wird im hohen Maße von der Strangschmierung genommen. Erfindungsgemäß soll bei Abweichung des Istwertes vom Sollwert das Gießpulver in der Weise geändert werden, daß der Reibungsbeiwert herabgesetzt wird. Hierzu wird vorgeschlagen, das Mischungsverhältnis verschiedener Gießpulver zueinander zu verändern und ggf. Einfluß auf den Aggregatzustand des Gießpulvers in der Weise zu nehmen, daß es durch Vorwärmung zumindest erweicht und u.U. verflüssigt wird, bevor es der in der Kokille befindenden Schmelze zugeführt wird.The strand lubrication has a great influence on the coefficient of friction. According to the invention, if the actual value deviates from the target value, the casting powder should be changed in such a way that the coefficient of friction is reduced. For this purpose, it is proposed to change the mixing ratio of different casting powders to one another and, if necessary, to influence the physical state of the casting powder in such a way that it at least softens by preheating and possibly. is liquefied before it is fed to the melt in the mold.
Ein Beispiel der Erfindung ist in den beigefügten Zeichnung dargelegt. Es zeigtAn example of the invention is set out in the accompanying drawings. It shows
Fig 1 die prinzipielle Aufschaltung,1 shows the basic connection,
Fig. 2 einen typischen Ausdruck undFig. 2 shows a typical expression and
Fig. 3 die Variationen der Wegkurven des Stranges.Fig. 3 shows the variations in the path curves of the strand.
Die Fig. 1 zeigt einen Strang 1 1 , der eine Kokille 12 verlassend von Rollen 14 geführt wird.Fig. 1 shows a strand 11, which leaves a mold 12 and is guided by rollers 14.
Die Kokille 12 ist mit einer Gießpulverzuführung verbunden, welche über Absperrungen 16 an Gießpulverbehälter 15 angeschlossen ist. Die Gießpulverzuführung 17 ist darüber hinaus durch eine Aufheizeinrichtung 18 geführt.The mold 12 is connected to a mold powder feed, which is connected to mold powder container 15 via barriers 16. The mold powder feed 17 is also guided through a heating device 18.
An der Schmalseite des Stranges 11 ist ein Sensor vorgesehen, hier eine Diodenzeilenkamera, die die Diodenzeilen des Stranges erfaßt, wobei die Kamera in ihrer Ausrichtung mit der Gießrichtung übereinstimmt.A sensor is provided on the narrow side of the strand 11, here a diode line camera which detects the diode lines of the strand, the alignment of the camera being the same as the casting direction.
Die Diodenzeilenkamera 21 ist über eine Meßleitung 28 mit der Meßaufnahme 22 für die Strangbewegung bezüglich Strecke 24und Geschwindigkeit 23 verbunden. Die Signale bezüglich der Änderung der Stranggeschwindigkeit und des Strangweges werden einem Rechner 26 und ggf. einem Anzeigegerät 25, ggf. einem Drucker, zugeführt.The diode line camera 21 is connected via a measuring line 28 to the measuring receptacle 22 for the strand movement with respect to the distance 24 and speed 23. The signals relating to the change in line speed and line path are fed to a computer 26 and possibly a display device 25, possibly a printer.
Dem Rechner 26 werden darüber hinaus weitere Parameter 27 aufgeschaltet.In addition, further parameters 27 are applied to the computer 26.
Auf der Ausgangsseite ist der Rechner 26 über eine Steuerleitung 31 mit einem Steuerbauteil 32 mit Aktuatoren 16 regelmäßig Absperrschieber der Gießpulverbehälter 15 sowie über ein Steuerbauteil 33 mit der Aufheizeinrichtung 18 für das Gießpulver verbunden.On the output side, the computer 26 is regularly connected to a gate valve 31 with a control component 32 with actuators 16, gate valves of the mold powder container 15 and via a control component 33 with the heating device 18 for the mold powder.
Über eine Steuerleitung 34 ist der Rechner 26 auch noch mit einem Steuerbauteil 35 zur Steuerung der Oszillation 13 verknüpft.The computer 26 is also linked via a control line 34 to a control component 35 for controlling the oscillation 13.
Die Fig. 2 zeigt einen typischen Ausdruck erfaßter Meßsignale. Im oberen Teil ist ein Ausschnitt der mittleren Geschwindigkeit der Kokille aufgezeigt, die im gegebenen Beispiel entsprechend einer Sinuskurve schwingt.Fig. 2 shows a typical expression of detected measurement signals. The upper part shows a section of the average mold speed, which in the given example oscillates according to a sine curve.
Darunter ist zum einen die mittlere Stranggeschwindigkeit des Gesamtstranges aufgezeigt und davon überlagert die im Bereich unmittelbar unterhalb der Kokille aufgezeigte Istgeschwindigkeit des Stranges. Deutlich zu erkennen ist das in Abhängigkeit der Reibung und ggf. kurzzeitigen Anklebens der Strangschale an der Innenwandung der Kokille des Stranges in der Nähe der Kokille. Die darunter aufgeführte Sinuskurve zeigt den Istweg der Kokille. Darunter ist der tatsächliche Weg des Stranges in Nähe der Kokille aufgezeigt.Below this, on the one hand, the average strand speed of the entire strand is shown and the actual speed of the strand shown in the area immediately below the mold is superimposed on it. This can be clearly seen depending on the friction and, if necessary, brief sticking of the strand shell to the inner wall of the mold of the strand near the mold. The sine curve below shows the actual path of the mold. The actual path of the strand near the mold is shown below.
Sowohl bei der Aufnahme der Stranggeschwindigkeit wie des Strangweges handelt es sich um Meßwerte und nicht um errechnete Werte. Die dargestellte Kurve ist ein Beispiel und zeigt charakteristische Istformen mit auswertbaren Punkten. Aus der Anordnung der Minima, Maxima und der Wendepunkte ist dem Fachmann die Möglichkeit gegeben, Rückschlüsse auf das tatsächliche Verhalten der Strangschale in der Kokille zu ziehen. Zur Beurteilung verwendet er die Position des Stranges zu den Zeitpunkten T mit den Kurvenformen bei den Punkten A. Die Strecke S ist hierbei die direkte Ableitung der Geschwindigkeit V. Die Fig. 3 zeigt Variationen des Strangweges. Zu beachten sind hier die Krümmungsradien der einzelnen Kurven bei den Punkten A sowie ggf. vorhandene Richtungswechsel. Durch Einflußnahme auf die Oszillation der Kokille und das Gießpulver wird Einfluß auf die Ausgestaltung des Istweges des Stranges genommen. Both the recording of the line speed and the line path are measured values and not calculated values. The curve shown is an example and shows characteristic actual shapes with evaluable points. From the arrangement of the minima, maxima and the turning points, the person skilled in the art is able to draw conclusions about the actual behavior of the strand shell in the mold. For the assessment, he uses the position of the strand at times T with the curve shapes at points A. The distance S is the direct derivative of the speed V. 3 shows variations of the strand path. Note the radii of curvature of the individual curves at points A and any changes of direction that may exist. By influencing the oscillation of the mold and the casting powder, the design of the actual path of the strand is influenced.

Claims

Patentansprüche claims
1. Verfahren an einer Gießanlage zur Erzeugung von Strängen, insbesondere von Stahlsträngen, bei dem flüssiges Metall in eine Durchlaufkokille eingeführt und im teilerstarrten Zustand aus der Kokille abgezogen wird, der Bewegungsablauf des Stranges in einem Bereich möglichst unmittelbar nach Verlassen der Kokille erfaßt wird, das Erfassen des Bewegungsablaufs berührungslos und verzögerungsfrei durch auf Strahlung ansprechende Sensoren erfolgt und die Sensoren derart ausgelegt und angeordnet sind, daß sie ein auswertbares Meßsignal über das Weg-Zeit-Verhalten des Stranges erzeugen, gekennzeichnet durch folgende Verfahrensschritte,1. Method on a casting plant for the production of strands, in particular steel strands, in which liquid metal is introduced into a continuous mold and withdrawn from the mold in the partially solidified state, the movement sequence of the strand is recorded in an area as soon as possible after leaving the mold, which The movement sequence is recorded in a contactless and delay-free manner by sensors which respond to radiation and the sensors are designed and arranged in such a way that they generate an evaluable measurement signal about the path-time behavior of the strand, characterized by the following method steps,
a) die Gießspiegeloberfläche wird mit einem eine flüssige Schlacke bildenden Gießpulver zur Erzeugung eines Schmierfilmes zwischen Strangschale und innerer Kokillenwand abgedeckt, b) ein die Reibung zwischen Strangschale und Kokillenwand charakterisierender Meßwert wird in der Oszillationseinrichtung erfaßt und der als Rechner ausgebildeten Auswerteinheit zugeführt, c) das das Weg-Zeit-Verhalten des Stranges charakterisierende Meßsignal wird ebenfalls dem Rechner zugeführt, d) im Rechner werden die Meßwerte bzw. Signale aus dem Weg-Zeit- Verhalten des Stranges und der Reibung des Stranges in der Kokille zu vergleichbaren Größen korreliert und verknüpft und mit einem Sollwert verglichen, wobei e) der Sollwert als Mittelwert der Stranggeschwindigkeit aus dem Weg-Zeit- Verhalten des Stranges gebildet ist, f) aus der Abweichung von Ist- und Sollwert wird ein Signal zur Änderung der Gießpulverzusammensetzung im Sinne einer Herabsetzung des Reibungsbeiwertes und/oder der Kokillenoszillation gebildet.a) the surface of the mold level is covered with a casting powder which forms a liquid slag to produce a lubricating film between the strand shell and the inner mold wall, b) a measured value characterizing the friction between the strand shell and the mold wall is recorded in the oscillation device and fed to the evaluation unit designed as a computer, c) this the measuring signal characterizing the path-time behavior of the strand is likewise fed to the computer, d) in the computer, the measured values or signals from the path-time behavior of the strand and the friction of the strand in the mold are correlated and linked to comparable sizes and compared with a target value, e) the target value being formed as the mean value of the strand speed from the path-time behavior of the strand, f) a deviation from the actual and target value is a signal for changing the powder composition in the sense of a reduction in the coefficient of friction and / or the Kokil lenoscillation formed.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, daß das Signal zur Änderung der Kokillenoszillation einer Steuereinheit des Oszillationsantriebes derart aufgeschaltet wird, daß der von der Kokille auf den Strang übertragene Bewegungsimpuls möglichst gering ist oder nahe am Wert Null liegt.2. The method according to claim 1, characterized in that the signal for changing the mold oscillation of a control unit of the oscillation drive is applied such that the movement pulse transmitted from the mold to the strand is as low as possible or close to the value Zero lies.
3. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, daß der die Reibung des Stranges in der Kokille charakterisierende Meßwert bei hydraulischem Antrieb der Kokillenoszillationseinrichtung aus dem Differenzdruck im Hydraulikzylinder zwischen Leerlauf und Betriebszustand gebildet ist.3. The method according to claim 1, characterized in that the measured value characterizing the friction of the strand in the mold with hydraulic drive of the mold oscillation device is formed from the differential pressure in the hydraulic cylinder between idle and operating state.
4. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, daß der die Reibung des Stranges in der Kokille charakterisierende Meßwert bei mechanischem Antrieb einer im Oszillationsgestänge angeordneten Kraftmeßzelle entnommen ist.4. The method according to claim 1, characterized in that the measured value characterizing the friction of the strand in the mold with mechanical drive is taken from a load cell arranged in the oscillating linkage.
5. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, daß das Mischungsverhältnis verschiedener Gießpulver zueinander verändert wird.5. The method according to claim 1, characterized in that the mixing ratio of different casting powders to one another is changed.
6. Verfahren nach den Ansprüchen 5 oder 1 , dadurch gekennzeichnet, daß der Aggregatzustand des Gießpulvers vor seinem Kontakt mit dem flüssigen Metall in der Kokille verändert wird, z.B. Erweichen oder Verflüssigen durch Zufuhr von Wärmeenergie.6. The method according to claims 5 or 1, characterized in that the physical state of the mold powder is changed prior to its contact with the liquid metal in the mold, e.g. Softening or liquefying by supplying thermal energy.
7. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, daß das Weg-Zeit-Verhalten des Stranges optisch durch eine seitlich neben dem Strang an seiner Schmalseite angeordnete Diodenzeilenkamera, die in ihrer Ausrichtung mit der Gießrichtung übereinstimmt, erfaßt wird. 7. The method according to claim 1, characterized in that the path-time behavior of the strand is optically detected by a diode line camera arranged laterally next to the strand on its narrow side, the alignment of which corresponds to the casting direction.
EP97922831A 1996-04-02 1997-04-02 Process for optimising surface quality of continuous castings Expired - Lifetime EP0907442B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19614760 1996-04-02
DE19614760A DE19614760A1 (en) 1996-04-02 1996-04-02 Process for optimizing the strand surface quality
PCT/DE1997/000732 WO1997036706A1 (en) 1996-04-02 1997-04-02 Process for optimising surface quality of continuous castings

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EP0907442A1 true EP0907442A1 (en) 1999-04-14
EP0907442B1 EP0907442B1 (en) 2001-05-30

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ITRM980258A1 (en) * 1998-04-23 1999-10-23 Acciai Speciali Terni Spa PROCEDURE FOR THE CONTINUOUS CASTING PRODUCTION OF SLABS FREE OF SURFACE DEFECTS AND SLABS SO OBTAINED
KR101790001B1 (en) * 2016-03-02 2017-11-20 주식회사 포스코 Melt supply equipment, casting apparatus and casting method
KR102189118B1 (en) * 2016-12-06 2020-12-09 닛폰세이테츠 가부시키가이샤 Slag volume evaluation method on molten metal surface
JP6984728B2 (en) * 2018-03-02 2021-12-22 日本製鉄株式会社 Shard manufacturing method and continuous casting equipment
CN115121771B (en) * 2022-07-27 2023-06-09 西北工业大学 Intelligent ultrasonic continuous casting method and measuring and controlling device for metal section

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DE2743579A1 (en) * 1976-10-05 1978-04-06 Centre Rech Metallurgique METAL CONTROL METHOD FOR CONTINUOUS CASTING
AT367328B (en) * 1980-04-29 1982-06-25 Vnii Avtom Chernoi Metallurg DEVICE FOR AUTOMATIC TENSION FORCE IN CONTINUOUS CASTING
JPH0235622B2 (en) * 1984-08-24 1990-08-13 Nippon Kokan Kk RENZOKUCHUZONIOKERUBUREEKUAUTOYOCHIHOHO
DE3806583A1 (en) * 1988-02-26 1989-09-07 Mannesmann Ag METHOD IN A CASTING SYSTEM FOR PRODUCING STRINGS
DE19515316C1 (en) * 1995-04-19 1996-08-29 Mannesmann Ag Method for operating a mold

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DE19614760A1 (en) 1997-10-09
AU2885797A (en) 1997-10-22
UA44840C2 (en) 2002-03-15
EP0907442B1 (en) 2001-05-30
AU722408B2 (en) 2000-08-03
CN1072067C (en) 2001-10-03
ATE201623T1 (en) 2001-06-15
WO1997036706A1 (en) 1997-10-09
CA2250871A1 (en) 1997-10-09
BR9708495A (en) 1999-08-03
JPH11513936A (en) 1999-11-30
ES2157072T3 (en) 2001-08-01
DE59703679D1 (en) 2001-07-05
JP3130053B2 (en) 2001-01-31
RU2163856C2 (en) 2001-03-10
CN1215357A (en) 1999-04-28

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