EP0116030B1 - Process for controlling a bow-type continuous casting machine - Google Patents

Process for controlling a bow-type continuous casting machine Download PDF

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Publication number
EP0116030B1
EP0116030B1 EP84890003A EP84890003A EP0116030B1 EP 0116030 B1 EP0116030 B1 EP 0116030B1 EP 84890003 A EP84890003 A EP 84890003A EP 84890003 A EP84890003 A EP 84890003A EP 0116030 B1 EP0116030 B1 EP 0116030B1
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Prior art keywords
strand
stiffness
withdrawal speed
permissible
value
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German (de)
French (fr)
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EP0116030A2 (en
EP0116030A3 (en
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Aktiengesellschaft Voest-Alpine
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Voestalpine AG
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Voestalpine AG
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16Controlling or regulating processes or operations
    • B22D11/20Controlling or regulating processes or operations for removing cast stock

Definitions

  • the invention relates to a method for monitoring a continuous sheet caster, in particular a steel continuous caster, in which a strand emerging from the strand guide is straightened in a straightening unit.
  • Two types of continuous sheet casting plants are known, firstly continuous sheet casting plants in which the strand is cast in an arc mold and straightened after deflecting into the horizontal in a straightening unit, and secondly continuous sheet casting plants in which the strand is cast in a straight mold, in a bending unit is diverted into a circular arc path and straightened in a straightening unit after deflection into the horizontal.
  • Both types can experience line standstills due to malfunctions, i.e. the line remains in the system for a short time until the malfunctions have been remedied.
  • Such strand stoppages or reductions in the strand pull-out speed cause the strand to solidify within the system, so that increased bending or straightening forces are required for bending or straightening the strand as a result of its increased rigidity.
  • the invention aims to avoid these disadvantages and difficulties and has as its object to provide a method for monitoring a continuous sheet casting installation by which the pulling of an excessively cooled strand from the installation can be prevented or recognized in good time or by which it is possible, To avoid excessive cooling of the strand within the curved strand guide, so that damage to the system caused thereby can be reliably avoided.
  • This object is achieved in that, depending on the stiffness, i.e. the measure of the resistance to changes in shape of the strand on its way from the mold to the end of the straightening unit is determined by process parameters, such as the strand pull-out speed, the permitted still permitted remaining pull-out time or the still permitted maximum downtime or the still permitted minimum pull-out speed of the rod If the remaining pull-out time or the maximum permitted standstill time is exceeded or if the pull-out speed falls below the minimum pull-out speed, an alarm signal is given and / or the system control is corrected, either by increasing the pull-out speed or by interrupting the casting.
  • process parameters such as the strand pull-out speed, the permitted still permitted remaining pull-out time or the still permitted maximum downtime or the still permitted minimum pull-out speed of the rod If the remaining pull-out time or the maximum permitted standstill time is exceeded or if the pull-out speed falls below the minimum pull-out speed, an alarm signal is given and / or the system control is corrected, either by increasing the pull-out speed or by interrupt
  • a value is preferably assigned to each strand cross-sectional element at a certain distance from the mold level, the size of which corresponds approximately to the rigidity of the element and the determination of which is primarily based on the pull-out speed (s) of the cross-sectional element on its way from the mold level to the specific distance from the mold level the value thus determined for each element is compared with a permissible limit value dependent on the current casting speed, and from the positive differences between the limit values and the determined values, the minimum positive difference is used as a determining factor for the maximum permissible remaining pull-out time.
  • each strand cross-sectional element is assigned a permissible limit value for the stiffness depending on the position it currently occupies, and the determined value of the stiffness of each element is compared with the associated permitted limit value and from all positive differences between the respective limit values and the minimum positive difference is selected from the determined values and used as a determining factor for the still permissible maximum downtime.
  • a value is advantageously given to each strand cross-sectional element at a certain distance from the casting level assigned, the size of which corresponds approximately to the stiffness of the element and for determining which the pull-out speed (s) of the cross-sectional element on its way from the mold level to the specific distance from the mold level is primarily used, a stiffness increase is determined based on the value determined for each element , which on the way of the element from its current distance from the mold level to the end of the straightening unit with a constant pull-out speed results in a stiffness value that is just below all the maximum permissible limit values, and this increase in stiffness is used as a determining factor for each pull-out speed of each element and from these pull-out speeds, the maximum pull-out speed is determined as the minimum pull-out speed still permissible.
  • the cooling conditions are used to determine the rigidity of each element in addition to the pull-out speed, as a result of which the determined rigidity of the strand elements corresponds particularly precisely to the actual conditions.
  • a particularly precise method is characterized in that, in addition to the pull-out speed, the strand cross-sectional format is used to determine the rigidity of each element, the strand quality also being expediently taken into account.
  • the permissible limit values used to determine the maximum permissible remaining pull-out time or the maximum still permissible standstill time or to determine the permissible minimum pull-out speed as a function of the construction-related strength values of the strand guide and, if appropriate, additionally of the strand cross-sectional format and / or the strand quality, thereby determining under Another consideration is the fact that individual machine parts of the continuous caster are more robust than the other machine parts loaded by the strand.
  • the straightening unit is designed for significantly higher loads than the bending unit and the circular arc-shaped strand guide arranged between these units.
  • Fig. 1 shows a schematic representation of a continuous sheet caster
  • 2 and 3 show diagrams in which the rigidity of the strand as a function of the distance from the mold level is illustrated.
  • a pan denotes a pan arranged above an intermediate vessel 2, from which molten steel flows into the intermediate vessel 2.
  • the molten steel flows from the intermediate vessel 2 into a water-cooled straight mold 3.
  • a bending unit 4 is provided, which is followed by an arcuate strand guide 5.
  • a straightening unit 6 is provided, which is followed by a run-out roller table (not shown) with a flame cutting device.
  • a process computer is designated 10.
  • the straight lines 11, 12 illustrate upper limit values for the rigidity of the strand 9, etc. depending on the distance from the mold level 13 to the end 14 of the straightening unit 6.
  • these maximum permissible limit values 11, 12 it is not just machine-dependent factors, i. factors due to the construction of the strand guide (rigidity of the rollers 7, 8, load capacity of their bearings etc.), but also the strand cross-sectional format set on the continuous casting machine and the steel quality to be cast are taken into account.
  • the stiffness 15 of the strand 9 is also entered as a function of the distance from the casting level, as occurs at a certain time during casting.
  • This function thus corresponds to the current stiffness curve at a specific moment and thus represents a kind of "snapshot" of the stiffness of the strand.
  • This "snapshot” can be obtained by dividing the strand 9 into strand cross-sectional elements, which in FIG. 2 are a to n are designated.
  • Each of these elements a to n is assigned a rigidity that takes into account the "history" of the strand, ie each element is assigned due to the "events” that occur on the way from the mold level 13 to the respective position of the element (maximum to End 14 of the straightening unit 6) have experienced a rigidity assigned.
  • This assignment includes any downtimes of the strand, the pull-out speeds v that occurred, and possibly changing cooling conditions (for example the amount of coolant with which each element was acted upon on its way from the mold level 13 to the momentary system of the respective element) or the cross-sectional format of the strand and / or the strand quality is taken into account.
  • the stiffness the temperature of the Melt or the strand surface are taken into account.
  • the element n was first removed from the mold level at a uniform speed V (straight line 16 '), followed by a standstill v o (straight line 16 "), whereupon the element again with a constant pulling speed v 2 (Line 16 "') was moved further, with the speed v 2 being greater than the speed V1 , as can be seen from the lower inclination of the straight line 16'".
  • the element n (and thus also all other elements of the line) was included greatly reduced pull-out speed v 3 , as can be seen from the more inclined straight line 16 "" of the course 16 of the "history" of the nth element.
  • the "history" of the kth element is furthermore with dash-dotted lines 17 that corresponds to the last part of the "history" of the nth element.
  • Fig. 2 Also shown in Fig. 2 is the increase in stiffness 18 of the nth element when the strand is pulled out by the distance between the individual elements, i.e. the nth element, which was initially at the position of the element n-1, experienced an increase in stiffness 18 during the further extension on the way from the position of the (n-1) element to the end of the straightening unit 18. Approximately, it can be assumed be that all elements have experienced approximately the same increase in stiffness 18 during this last pull-out step, including elements a and k.
  • V limit V2 according to FIG. 2.
  • This straight line 19 thus illustrates the minimum permissible rigidity.
  • the rigidity increases only slightly due to the increased cooling water supply (the cooling water is specified with the help of a process computer), so that approximately the same rigidity increase is always assumed for drawing speeds greater than vg renz .
  • the stiffness to be expected for the future period (which the element will need to cover the remaining distance to the end of the straightening unit) is calculated and this stiffness to be expected compared with the maximum permissible stiffnesses 11, 12 If one of the elements on its way to the end 14 of the straightening unit 6 is assigned a higher stiffness at any point on the path still to be covered than is assigned to this point on the path due to the limit curves 11, 12, either an alarm signal is issued or it is given in the control of the system intervened to correct it. This can e.g. by either increasing the pull-out speed or stopping the casting.
  • Fig. 1 From Fig. 1 it can be seen that from the process computer 10 control lines 20, 21, 22 to a ladle slide 23 for setting or closing the same, to a distributor plug 24 for setting or closing the same and to a line control unit 25 for setting a specific line pull-out speed . Another line 26 leads to an alarm system 27.
  • the maximum permissible limit values 11, 12 of the stiffness, the measured value of the current casting speed or pull-out speed, as well as information about the steel quality and the strand cross-sectional format and, if appropriate, about the cooling via input lines 28 are fed into the process computer 10.
  • the calculation of the rigidity of the individual strand elements can be adapted to the current conditions of the casting process on the basis of the current measurement data acquisition.
  • Fig. 3 is shown in a manner analogous to Fig. 2 in a graphical representation that for the elements a to 1 and the element p with the current pull-out speed v the sufficiency is no longer found by the increase in stiffness as it continues with the pouring current casting speed is to be expected (and which is illustrated by the dashed straight lines 29, 30), is drawn from these elements in the diagram. It can be seen that the straight lines 29, 30, which start from the elements a to 1 and from the element p, result in intersections with the maximum permissible limit values 11, 12 for the stiffnesses.
  • the differences between the current stiffness values of the elements a to n and the current locally associated limit values 11, 12 are formed and from these differences (in FIG. 3, one of these differences for the element q is denoted by 33).
  • the minimum difference 34 is given for the element p +, i.e. the element p + is responsible for the maximum permitted downtime.
  • FIG. 3 shows the increase in stiffness ( dash-dotted line 35) for element q during casting with a minimum permissible pull-out speed v rnin.
  • This element q represents the critical element in the instantaneous recording of the stiffness values of the elements shown in FIG. 3, ie The minimum pull-out speed v n ⁇ n must be based on this element; all other elements would allow a lower pull-out speed and thus a higher specific increase in stiffness
  • curves 29, 30 and 35 are used instead of straight lines.
  • Another advantage of the method according to the invention can be seen in the fact that, on the basis of the stiffness values achieved by the individual elements a to n in the individual zones of the strand guide or the maximum stiffness values that occur, statistics about the load on the continuous casting installation or the elements of the strand guide are created can be determined based on the overhaul times of the system.

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

Description

Die Erfindung betrifft ein Verfahren zum Überwachen einer Bogenstranggießanlage, insbesondere einer Stahl-Bogenstranggießanlage, bei der ein gebogen aus der Strangführung austretender Strang in einem Richtaggregat geradegerichtet wird.The invention relates to a method for monitoring a continuous sheet caster, in particular a steel continuous caster, in which a strand emerging from the strand guide is straightened in a straightening unit.

Es sind zwei Typen von Bogenstranggießanlagen bekannt, und zwar erstens Bogenstranggießanlagen, bei denen der Strang in einer Bogenkokille gegossen und nach Umlenken in die Horizontale in einem Richtaggregat geradegerichtet wird, und zweitens Bogenstranggießanlagen, bei denen der Strang in einer geraden Kokille gegossen, in einem Biegeaggregat in eine Kreisbogenbahn umgelenkt und nach Umlenken in die Horizontale in einem Richtaggregat geradegerichtet wird. Bei beiden Typen kann es infolge von Betriebsstörungen zu Strangstillstandszeiten kommen, d.h. der Strang verweilt stillstehend kurzzeitig in der Anlage, bis die Betriebsstörungen behoben sind. Weiters kann es erforderlich sein, die Strangausziehgeschwindigkeit (Gießgeschwindigkeit) zeitweise stark zu verringern, beispielsweise dann, wenn man ohne Unterbrechen des Gießens das Strangquerschnittsformat ändern will. Solche Strangstillstände bzw. Verringerungen der Strangausziehgeschwindigkeit bedingen ein Verfestigen des Stranges innerhalb der Anlage, so daß zum Biegen bzw. Geraderichten des Stranges infolge dessen erhöhter Steifigkeit erhöhte Biege- bzw. Richtkräfte erforderlich sind.Two types of continuous sheet casting plants are known, firstly continuous sheet casting plants in which the strand is cast in an arc mold and straightened after deflecting into the horizontal in a straightening unit, and secondly continuous sheet casting plants in which the strand is cast in a straight mold, in a bending unit is diverted into a circular arc path and straightened in a straightening unit after deflection into the horizontal. Both types can experience line standstills due to malfunctions, i.e. the line remains in the system for a short time until the malfunctions have been remedied. Furthermore, it may be necessary to temporarily greatly reduce the strand pull-out speed (casting speed), for example if you want to change the strand cross-sectional format without interrupting the casting. Such strand stoppages or reductions in the strand pull-out speed cause the strand to solidify within the system, so that increased bending or straightening forces are required for bending or straightening the strand as a result of its increased rigidity.

Verweilt der Strang zu lange in der Anlage, kann es beim nachfolgenden Ausziehen des übermäßig abgekühlten Stranges zu schweren Schäden an der Anlage, insbesondere an der Rollenführung und dem Richtaggregat kommen, die mit entsprechend langen Stillstandszeiten und mit hohen Kosten für die Reparaturen verbunden sind.If the strand remains in the system for too long, the subsequent pulling out of the excessively cooled strand can result in serious damage to the system, in particular to the roller guide and the straightening unit, which are associated with correspondingly long downtimes and high costs for repairs.

Die Erfindung bezweckt die Vermeidung dieser Nachteile und Schwierigkeiten und stellt sich die Aufgabe, ein Verfahren zum Überwachen einer Bogenstranggießanlage zu schaffen, durch welches das Ausziehen eines zu stark abgekühlten Stranges aus der Anlage verhindert bzw. rechtzeitig erkannt werden kann oder durch welches es möglich ist, ein zu starkes Abkühlen des Stranges innerhalb der gebogenen Strangführung zu vermeiden, so daß dadurch verursachte Beschädigungen an der Anlage zuverlässig vermieden werden.The invention aims to avoid these disadvantages and difficulties and has as its object to provide a method for monitoring a continuous sheet casting installation by which the pulling of an excessively cooled strand from the installation can be prevented or recognized in good time or by which it is possible, To avoid excessive cooling of the strand within the curved strand guide, so that damage to the system caused thereby can be reliably avoided.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß in Abhängigkeit von den die Steifigkeit, d.h. das Maß für den Widerstand gegen Formänderungen des Stranges auf seinem Weg von der Kokille bis zum Ende des Richtaggregates beeinflussenden Verfahrensparametern, wie der Strangausziehgeschwindigkeit, die erlaubte noch zulässige Restausziehzeit oder die noch zulässige maximale Stillstandszeit oder die noch zulässige minimale Ausziehgeschwindigkeit des Stanges ermittelt wird und bei Überschreiten der noch zulässigen Restausziehzeit bzw. der noch zulässigen maximalen Stillstandszeit oder bei Unterschreiten der minimalen Ausziehgeschwindigkeit bei der augenblicklichen Ausziehgeschwindigkeit ein Alarmsignal abgegeben wird und/oder in die Steuerung der Anlage korrigierend eingegriffen wird, entweder durch Erhöhung der Ausziehgeschwindigkeit oder durch Abbrechen des Gießens. Dies bedeutet, daß die Ereignisse des Stranges auf seinem Weg von der Kokille bis zum Ende des Richtaggregates, so weit sie die Steifigkeit des Stranges beeinflussen, aufgezeichnet und daraus die Steifigkeit des Stranges (ohne Messungen am Strang selbst durchführen zu müssen) ermittelt wird. Es wird somit die "Geschichte" des Stranges zur Überwachung der Bogenstranggießanlage herangezogen.This object is achieved in that, depending on the stiffness, i.e. the measure of the resistance to changes in shape of the strand on its way from the mold to the end of the straightening unit is determined by process parameters, such as the strand pull-out speed, the permitted still permitted remaining pull-out time or the still permitted maximum downtime or the still permitted minimum pull-out speed of the rod If the remaining pull-out time or the maximum permitted standstill time is exceeded or if the pull-out speed falls below the minimum pull-out speed, an alarm signal is given and / or the system control is corrected, either by increasing the pull-out speed or by interrupting the casting. This means that the events of the strand on its way from the mold to the end of the straightening unit, as far as they influence the rigidity of the strand, are recorded and from this the rigidity of the strand (without having to carry out measurements on the strand itself) is determined. The "history" of the strand is thus used to monitor the continuous sheet casting installation.

Vorzugsweise wird jedem in einem bestimmten Abstand vom Gießspiegel entfernten Strangquerschnittselement ein Wert zugeordnet, dessen Größe etwa der Steifigkeit des Elementes entspricht und zu dessen Ermittlung primär die Ausziehgeschwindigkeit(en) des Querschnittselementes auf seinem Weg vom Gießspiegel bis zum bestimmten Abstand vom Gießspiegel herangezogen wird, wird der so für jedes Element ermittelte Wert jeweils mit einem von der aktuellen Gießgeschwindigkeit abhängigen zulässigen Grenzwert verglichen und aus den positiven Differenzen zwischen den Grenzwerten und den ermittelten Werten die minimale positive Differenz als Bestimmungsfaktor für die maximal noch zulässige Restausziehzeit herangezogen.A value is preferably assigned to each strand cross-sectional element at a certain distance from the mold level, the size of which corresponds approximately to the rigidity of the element and the determination of which is primarily based on the pull-out speed (s) of the cross-sectional element on its way from the mold level to the specific distance from the mold level the value thus determined for each element is compared with a permissible limit value dependent on the current casting speed, and from the positive differences between the limit values and the determined values, the minimum positive difference is used as a determining factor for the maximum permissible remaining pull-out time.

Zur Bestimmung der noch zulässigen maximalen Stillstandszeit wird zweckmäßig jedem in einem bestimmten Abstand vom Gießspiegel entfernten Strangquerschnittselement ein Wert zugeordnet, dessen Größe etwa der Steifigkeit des Elementes entspricht und zu dessen Ermittlung primär die Ausziehgeschwindigkeit(en) des Querschnittselementes auf seinem Weg vom Gießspiegel bis zum bestimmten Abstand vom Gießspiegel herangezogen wird, wird jedem Element in Abhängigkeit von der von ihm augenblicklich eingenommenen Position ein zulässiger Grenzwert für die Steifigkeit zugeordnet und wird der ermittelte Wert der Steifigkeit jedes Elementes mit dem zugehörigen zulässigen Grenzwert verglichen und aus sämtlichen positiven Differenzen zwischen den jeweiligen Grenzwerten und den ermittelten Werten die minimale positive Differenz ausgewählt und als Bestimmungsfaktor für die noch zulässige maximale Stillstandszeit herangezogen.To determine the maximum permissible downtime that is still permissible, it is advisable to assign a value to each strand cross-sectional element at a certain distance from the mold level, the size of which corresponds approximately to the stiffness of the element and to determine it primarily the pull-out speed (s) of the cross-sectional element on its way from the mold level to the specific one Distance from the mold level, each element is assigned a permissible limit value for the stiffness depending on the position it currently occupies, and the determined value of the stiffness of each element is compared with the associated permitted limit value and from all positive differences between the respective limit values and the minimum positive difference is selected from the determined values and used as a determining factor for the still permissible maximum downtime.

Zur Ermittlung der noch zulässigen minimalen Ausziehgeschwindigkeit wird Vorteilhaft jedem in einem bestimmten Abstand vom Gießspiegel entfernten Strangquerschnittselement ein Wert zugeordnet, dessen Größe etwa der Steifigkeit des Elementes entspricht und zu dessen Ermittlung primär die Ausziehgeschwindigkeit(en) des Querschnittselementes auf seinem Weg vom Gießspiegel bis zum bestimmten Abstand vom Gießspiegel herangezogen wird, wird von dem so fur jedes Element ermittelten Wert ausgehend jeweils ein Steifigkeitszuwachs bestimmt, der auf dem Weg des Elementes von seinem augenblicklich eingenommenen Abstand vom Gießspiegel bis zum Ende des Richtaggregates bei konstanter Ausziehgeschwindigkeit einen Steifigkeitswert ergibt, der gerade noch unter sämtlichen maximal zulässigen Grenzwerten liegt, und wird dieser Steifigkeitszuwachs als Bestimmungsfaktor für jeweils eine Ausziehgeschwindigkeit jedes Elementes herangezogen und von diesen Ausziehgeschwindigkeiten die maximale Ausziehgeschwindigkeit als noch zulässige minimale Ausziehgeschwindigkeit bestimmt.In order to determine the minimum permissible pull-out speed, a value is advantageously given to each strand cross-sectional element at a certain distance from the casting level assigned, the size of which corresponds approximately to the stiffness of the element and for determining which the pull-out speed (s) of the cross-sectional element on its way from the mold level to the specific distance from the mold level is primarily used, a stiffness increase is determined based on the value determined for each element , which on the way of the element from its current distance from the mold level to the end of the straightening unit with a constant pull-out speed results in a stiffness value that is just below all the maximum permissible limit values, and this increase in stiffness is used as a determining factor for each pull-out speed of each element and from these pull-out speeds, the maximum pull-out speed is determined as the minimum pull-out speed still permissible.

Gemäß einem bevorzugten Verfahren werden zur Ermittlung der Steifigkeit jedes Elementes neben der Ausziehgeschwindigkeit die Kühlbedingungen herangezogen, wodurch die ermittelte Steifigkeit der Strangelemente besonders genau mit den tatsächlichen Verhältnissen übereinstimmt.According to a preferred method, the cooling conditions are used to determine the rigidity of each element in addition to the pull-out speed, as a result of which the determined rigidity of the strand elements corresponds particularly precisely to the actual conditions.

Ein besonders genaues Verfahren ist dadurch gekennzeichnet, daß zur Ermittlung der Steifigkeit jedes Elementes neben der Ausziehgeschwindigkeit das Strangquerschnittsformat herangezogen wird, wobei zweckmäßig auch die Strangqualität berücksichtigt wird.A particularly precise method is characterized in that, in addition to the pull-out speed, the strand cross-sectional format is used to determine the rigidity of each element, the strand quality also being expediently taken into account.

Vorteilhaft werden die zur Ermittlung der maximal noch zulässigen Restausziehzeit bzw. der maximalen noch zulässigen Stillstandszeit oder zur Ermittlung der noch zulässigen minimalen Ausziehgeschwindigkeit herangezogenen zulässigen Grenzwerte in Abhängigkeit von den konstruktionsbedingten Festigkeitswerten der Strangführung sowie gegebenenfalls zusätzlich vom Strangquerschnittsformat und/oder der Strangqualität bestimmt, wodurch unter anderem dem Umstand Rechnung getragen wird, daß einzelne Maschinenteile der Stranggießanlage robuster gestaltet sind als die übrigen vom Strang belasteten Maschinenteile. Beispielsweise ist das Richtaggregat für wesentlich höhere Belastungen ausgelegt als das Biegeaggregat und die zwischen diesen Aggregaten angeordnete kreisbogenförmige Strangführung.The permissible limit values used to determine the maximum permissible remaining pull-out time or the maximum still permissible standstill time or to determine the permissible minimum pull-out speed as a function of the construction-related strength values of the strand guide and, if appropriate, additionally of the strand cross-sectional format and / or the strand quality, thereby determining under Another consideration is the fact that individual machine parts of the continuous caster are more robust than the other machine parts loaded by the strand. For example, the straightening unit is designed for significantly higher loads than the bending unit and the circular arc-shaped strand guide arranged between these units.

Die Erfindung ist nachfolgend anhand eines Ausführungsbeispieles näher beschrieben. Fig. 1 zeigt eine schematische Darstellung einer Bogenstranggießanlage; die Fig. 2 und 3 zeigen Diagramme, in denen die Steifigkeit des Stranges in Abhängigkeit vom Abstand vom Gießspiegel veranschaulicht ist.The invention is described in more detail below using an exemplary embodiment. Fig. 1 shows a schematic representation of a continuous sheet caster; 2 and 3 show diagrams in which the rigidity of the strand as a function of the distance from the mold level is illustrated.

Mit 1 ist eine über einem Zwischengefäß 2 angeordnete Pfanne bezeichnet, aus der Stahlschmelze in das Zwischengefäß 2 fließt. Aus dem Zwischengefäß 2 strömt die Stahlschmelze in eine wassergekühlte gerade Kokille 3. Unterhalb der Kokille ist ein Biegeaggregat 4 vorgesehen, dem eine kreisbogenförmige Strangführung 5 nachgeordnet ist. Am Ende der sich etwa über einen Viertelkreisbogen erstreckenden Strangführung 5 ist ein Richtaggregat 6 vorgesehen, dem ein nicht dargestellter Auslaufrollgang mit einer Brennschneideinrichtung folgt.1 denotes a pan arranged above an intermediate vessel 2, from which molten steel flows into the intermediate vessel 2. The molten steel flows from the intermediate vessel 2 into a water-cooled straight mold 3. Below the mold, a bending unit 4 is provided, which is followed by an arcuate strand guide 5. At the end of the strand guide 5, which extends approximately over a quarter-circle arc, a straightening unit 6 is provided, which is followed by a run-out roller table (not shown) with a flame cutting device.

In der kreisbogenförmigen Strangführung 5 und im Richtaggregat 6 sind neben nicht antreibbaren Rollen 7 angetriebene Rollen 8 vorgesehen, die den Strang 9 mit einer vorgewählten Ausziehgeschwindigkeit aus der Kokille 3 fördern. Ein Prozeßrechner ist mit 10 bezeichnet.In the arcuate strand guide 5 and in the straightening unit 6, in addition to non-drivable rollers 7, driven rollers 8 are provided, which convey the strand 9 from the mold 3 at a preselected pull-out speed. A process computer is designated 10.

Zur Überwachung der Bogenstranggießanlage wird wie folgt vorgegangen:To monitor the continuous sheet caster, proceed as follows:

In dem in Fig. 2 dargestellten Diagramm sind durch die Geraden 11,12 obere Grenzwerte für die Steifigkeit des Stranges 9 veranschaulicht, u.zw. in Abhängigkeit des Abstandes vom Gießspiegel 13 bis zum Ende 14 des Richtaggregates 6. Bei der Festlegung dieser maximal zulässigen Grenzwerte 11, 12 sind nicht nur maschinenabhängige Faktoren, d.h. durch die Konstruktion der Strangführung bedingte Faktoren (Steifigkeit der Rollen 7, 8, Belastbarkeit deren Lager etc.), sondern es sind auch das an der Stranggießmaschine eingestellte Strangquerschnittsformat und die zu gießende Stahlqualität berücksichtigt.In the diagram shown in FIG. 2, the straight lines 11, 12 illustrate upper limit values for the rigidity of the strand 9, etc. depending on the distance from the mold level 13 to the end 14 of the straightening unit 6. When determining these maximum permissible limit values 11, 12, it is not just machine-dependent factors, i. factors due to the construction of the strand guide (rigidity of the rollers 7, 8, load capacity of their bearings etc.), but also the strand cross-sectional format set on the continuous casting machine and the steel quality to be cast are taken into account.

In Fig. 2 ist weiters die Steifigkeit 15 des Stranges 9 als Funktion des Abstandes vom Gießspiegel, wie sie zu einem bestimmten Zeitpunkt während des Gießens auftritt, eingetragen. Diese Funktion entspricht somit dem aktuellen Steifigkeitsverlauf zu einem bestimmten Moment und stellt somit eine Art "Momentaufnahme" der Steifigkeit des Stranges dar. Zu dieser "Momentaufnahme" gelangt man, indem der Strang 9 in Strangquerschnittselemente geteilt wird, die in Fig. 2 mit a bis n bezeichnet sind. Jedem dieser Elemente a bis n wird vom Prozeßrechner eine die "Geschichte" des Stranges berücksichtigende Steifigkeit zugeordnet, d.h. es wird jedem Element aufgrund der "Ereignisse", die diese Elemente auf dem Weg vom Gießspiegel 13 bis zur jeweiligen Lage des Elementes (maximal bis zum Ende 14 des Richtaggregates 6) erfahren haben, eine Steifigkeit zugeordnet. Bei dieser Zuordnung werden etwaige Stillstandszeiten des Stranges, die jeweils aufgetretenen Ausziehgeschwindigkeiten v sowie gegebenenfalls wechselnde Kühlbedingungen (beispielsweise die Kühlmittelmenge, mit der jedes Element auf seinem Weg vom Gießspiegel 13 bis zur Momentanlage des jeweiligen Elementes beaufschlagt wurde) bzw. das Querschnittsformat des Stranges und/oder die Strangqualität berücksichtigt. Bei der Ermittlung der Steifigkeit kann weiters die Temperatur der Schmelze bzw. der Strangoberfläche berücksichtigt werden.In Fig. 2, the stiffness 15 of the strand 9 is also entered as a function of the distance from the casting level, as occurs at a certain time during casting. This function thus corresponds to the current stiffness curve at a specific moment and thus represents a kind of "snapshot" of the stiffness of the strand. This "snapshot" can be obtained by dividing the strand 9 into strand cross-sectional elements, which in FIG. 2 are a to n are designated. Each of these elements a to n is assigned a rigidity that takes into account the "history" of the strand, ie each element is assigned due to the "events" that occur on the way from the mold level 13 to the respective position of the element (maximum to End 14 of the straightening unit 6) have experienced a rigidity assigned. This assignment includes any downtimes of the strand, the pull-out speeds v that occurred, and possibly changing cooling conditions (for example the amount of coolant with which each element was acted upon on its way from the mold level 13 to the momentary system of the respective element) or the cross-sectional format of the strand and / or the strand quality is taken into account. When determining the stiffness, the temperature of the Melt or the strand surface are taken into account.

Die "Geschichte" des Steifigkeitszuwachses des n-ten Elementes ist in Fig. 2 mit strichlierten Linien 16 eingetragen, wobei der Steifigkeitszuwachs in Abhängigkeit von den Wegabschnitten, entlang der das Element n mit konstanter Ausziehgeschwindigkeit bewegt wurde, in guter Annäherung an den tatsächlichen Steifigkeitszuwachs durch die Geraden 16', 16", 16"', 16"" veranschaulicht sind.The "history" of the increase in stiffness of the nth element is entered in FIG. 2 with dashed lines 16, the increase in stiffness depending on the path sections along which the element n was moved at a constant pull-out speed, in a good approximation of the actual increase in stiffness the straight lines 16 ', 16 ", 16"', 16 "" are illustrated.

Vom Gießspiegel weg wurde, wie aus Fig. 2 ersichtlich ist, das Element n zunächst mit gleichmäßiger Geschwindigkeit V, (Gerade 16') ausgezogen, dann folgte ein Strangstillstand vo (Gerade 16"), worauf das Element wiederum mit konstanter Ausziehgeschwindigkeit v2 (Gerade 16"') weiterbewegt wurde, wobei die Geschwindigkeit v2 größer war als die Geschwindigkeit V1, wie aus der geringeren Neigung der Geraden 16'" ersichtlich ist. Zuletzt wurde das Element n (und damit auch alle anderen Elemente des Stranges) mit stark verringerter Ausziehgeschwindigkeit v3 ausgefördert, wie sich aus der stärker geneigten Geraden 16"" des Verlaufes 16 der "Geschichte" des n-ten Elementes ergibt. In Fig. 2 ist weiters mit strichpunktierten Linien 17 die "Geschichte" des k-ten Elementes, die mit dem letzten Teil der "Geschichte" des n-ten Elementes übereinstimmt, eingetragen.As can be seen from FIG. 2, the element n was first removed from the mold level at a uniform speed V (straight line 16 '), followed by a standstill v o (straight line 16 "), whereupon the element again with a constant pulling speed v 2 (Line 16 "') was moved further, with the speed v 2 being greater than the speed V1 , as can be seen from the lower inclination of the straight line 16'". Finally, the element n (and thus also all other elements of the line) was included greatly reduced pull-out speed v 3 , as can be seen from the more inclined straight line 16 "" of the course 16 of the "history" of the nth element. In FIG. 2, the "history" of the kth element is furthermore with dash-dotted lines 17 that corresponds to the last part of the "history" of the nth element.

In Fig. 2 ebenfalls eingetragen ist der Steifigkeitszuwachs 18 des n-ten Elementes beim Ausziehen des Stranges um den zwischen den einzelnen Elemente liegenden Abstand, d.h. das n-te Element, das sich zunächst an der Stelle des Elementes n-1 befunden hatte, erfuhr während des weiteren Ausziehens beim Weg von der Stelle des (n-1) Elementes bis zum Ende des Richtaggregates einen Steifigkeitszuwachs 18. Näherungsweise kann davon ausgegangen werden, daß sämtliche Elemente während dieses letzten Ausziehschrittes den etwa gleichen Steifigkeits zuwachs 18 erfahren haben, also auch die Elemente a und k.Also shown in Fig. 2 is the increase in stiffness 18 of the nth element when the strand is pulled out by the distance between the individual elements, i.e. the nth element, which was initially at the position of the element n-1, experienced an increase in stiffness 18 during the further extension on the way from the position of the (n-1) element to the end of the straightening unit 18. Approximately, it can be assumed be that all elements have experienced approximately the same increase in stiffness 18 during this last pull-out step, including elements a and k.

Eine weitere Gerade 19, die in Fig. 2 eingetragen ist, stellt den Steifigkeitsverlauf dar, wie er sich bei kontinuierlichem Ausziehen des Stranges mit einer Gießgeschwindigkeit Vgrenz (=V2 gemäß Fig. 2) einstellt. Diese Gerade 19 veranschaulicht somit die minimal zulässige Steifigkeit. Für Gießgeschwindigkeiten größer als Vgrenz nimmt die Steifigkeit aufgrund der erhöhten Kühlwasserbeaufschlagung (die Kühlwasservorgabe wird mit Hilfe eines Prozeßrechners vorgenommen) nur geringfügig zu, so daß näherungsweise für Ausziehgeschwindigkeiten größer als vgrenz stets dieselbe Steifigkeitszunahme angenommen wird.Another straight line 19, which is entered in FIG. 2, represents the course of stiffness as it occurs when the strand is continuously pulled out with a casting speed V limit (= V2 according to FIG. 2). This straight line 19 thus illustrates the minimum permissible rigidity. For casting speeds greater than Vg renz , the rigidity increases only slightly due to the increased cooling water supply (the cooling water is specified with the help of a process computer), so that approximately the same rigidity increase is always assumed for drawing speeds greater than vg renz .

Erfindungsgemäß wird unter Zugrundelegung der aktuellen Gießgeschwindigkeit für jedes der Elemente die für den zukünftigen Zeitabschnitt (den das Element zur Zurücklegung des restlichen Weges bis zum Ende des Richtaggregates benötigt) zu erwartende Steifigkeit errechnet und diese zu erwartende Steifigkeit verglichen mit den maximal zulässigen Steifigkeiten 11, 12. Wenn einem der Elemente auf seinem Weg bis zum Ende 14 des Richtaggregates 6 an irgendeiner Stelle des noch zurückzulegenden Weges eine höhere Steifigkeit zugeordnet wird als dieser Stelle des Weges aufgrund der Grenzkurven 11, 12 zugeordnet ist, wird entweder ein Alarmsignal abgegeben oder es wird in die Steuerung der Anlage korrigierend eingegriffen. Dies kann z.B. dadurch erfolgen, daß entweder die Ausziehgeschwindigkeit erhöht wird oder das Gießen abgebrochen wird.According to the invention, based on the current casting speed for each of the elements, the stiffness to be expected for the future period (which the element will need to cover the remaining distance to the end of the straightening unit) is calculated and this stiffness to be expected compared with the maximum permissible stiffnesses 11, 12 If one of the elements on its way to the end 14 of the straightening unit 6 is assigned a higher stiffness at any point on the path still to be covered than is assigned to this point on the path due to the limit curves 11, 12, either an alarm signal is issued or it is given in the control of the system intervened to correct it. This can e.g. by either increasing the pull-out speed or stopping the casting.

Aus Fig. 1 ist ersichtlich, daß vom Prozeßrechner 10 Steuerleitungen 20, 21, 22 zu einem Pfannenschieber 23 zwecks Einstellen bzw. Schließen desselben, zu einem Verteilerstopfen 24 zwecks Einstellen bzw. Schließen desselben und zu einer Strangsteuereinheit 25 zur Einstellung einer bestimmten Strangausziehgeschwindigkeit geführt sind. Eine weitere Leitung 26 ist zu einer Alarmanlage 27 geführt. In den Prozeßrechner 10 werden die maximal zulässigen Grenzwerte 11, 12 der Steifigkeit, der Meßwert der aktuellen Gießgeschwindigkeit bzw. Ausziehgeschwindigkeit sowie Angaben über die Stahlqualität und das Strangquerschnittsformat sowie gegebenenfalls über die Kühlung über Eingabeleitungen 28 zugeleitet.From Fig. 1 it can be seen that from the process computer 10 control lines 20, 21, 22 to a ladle slide 23 for setting or closing the same, to a distributor plug 24 for setting or closing the same and to a line control unit 25 for setting a specific line pull-out speed . Another line 26 leads to an alarm system 27. The maximum permissible limit values 11, 12 of the stiffness, the measured value of the current casting speed or pull-out speed, as well as information about the steel quality and the strand cross-sectional format and, if appropriate, about the cooling via input lines 28 are fed into the process computer 10.

Die Berechnung der Steifigkeit der einzelnen Strangelemente kann aufgrund der aktuellen Meßdatenerfassung an die aktuellen Gegebenheiten des Gießverlaufes angepaßt werden.The calculation of the rigidity of the individual strand elements can be adapted to the current conditions of the casting process on the basis of the current measurement data acquisition.

In Fig. 3 ist in zu Fig. 2 analoger Weise in graphischer Darstellung gezeigt, daß für die Elemente a bis 1 und das Element p mit der aktuellen Ausziehgeschwindigkeit v nicht mehr das Auslangen gefunden wird, indem der Steifigkeitszuwachs, wie er bei Weitergießen mit der aktuellen Gießgeschwindigkeit zu erwarten (und der durch die strichlierten Geraden 29, 30 veranschaulicht ist) ist, von diesen Elementen ausgehend in das Diagramm eingezeichnet ist. Es ist ersichtlich, daß die Geraden 29, 30, die von den Elementen a bis 1 und vom Element p ausgehen, Schnittpunkte mit den maximal zulässigen Grenzwerten 11, 12 für die Steifigkeiten ergeben.In Fig. 3 is shown in a manner analogous to Fig. 2 in a graphical representation that for the elements a to 1 and the element p with the current pull-out speed v the sufficiency is no longer found by the increase in stiffness as it continues with the pouring current casting speed is to be expected (and which is illustrated by the dashed straight lines 29, 30), is drawn from these elements in the diagram. It can be seen that the straight lines 29, 30, which start from the elements a to 1 and from the element p, result in intersections with the maximum permissible limit values 11, 12 for the stiffnesses.

Zur Bestimmung der erlaubten noch zulässigen Restausziehzeit wird für jedes Element ein in Zukunft - bei Weitergießen mit der aktuellen Gießgeschwindigkeit - auf dem Weg jedes Elementes zum Ende des Richtaggregates zu erwartender Steifigkeitszuwachs ermittelt (vgl. die Gerade 29 in Fig. 3 Steifigkeitszuwachs für die Elemente a bis q). Für sämtliche Elemente, bei denen es zu einer Kollision (in Fig. 3 z. B. für die Elemente a bis q durch Punkt 31 und für die Elemente 1 und p durch Punkt 32 veranschaulicht) der zu erwartenden Steifigkeitswerte mit den Grenzwerten 11, 12 kommt, werden aus den Differenzen zwischen dem Grenzwert (Kollisionspunkt) und dem aktuellen Steifigkeitswert die Ausziehzeiten bestimmt, die benötigt werden, um von der aktuellen Steifigkeit bis zum Kollisionspunkt zu gelangen. Von diesen Ausziehzeiten wird die minimale Ausziehzeit ausgewählt und diese stellt die erlaubte noch zulässige Restausziehzeit des Stranges zum Zeitpunkt dieser Berechnung dar.In order to determine the permitted remaining permissible pull-out time, an increase in stiffness to be expected for each element in the future - if the pouring continues at the current casting speed - on the path of each element to the end of the straightening unit (see straight line 29 in FIG. 3 Stiffness increase for elements a to q). For all elements in which there is a collision (illustrated in FIG. 3, for example, for elements a to q by point 31 and for elements 1 and p by point 32), the expected stiffness values with limit values 11, 12 comes from the differences between the limit value (collision point) and the current one Stiffness value determines the extension times required to get from the current stiffness to the collision point. The minimum pull-out time is selected from these pull-out times and this represents the permitted and still permitted remaining pull-out time of the strand at the time of this calculation.

Zur Ermittlung der noch zulässigen maximalen Stillstandszeit werden die Differenzen zwischen den aktuellen Steifigkeitswerten der Elemente a bis n und den momentanen örtlich zugehörigen Grenzwerten 11, 12 gebildet und von diesen Differenzen (in Fig. 3 ist eine dieser Differenzen für das Element q mit 33 bezeichnet) die minimale Differenz ausgewählt. Diese minimale Differenz wird der Errechnung der noch zulässigen maximalen Stillstandszeit zugrundegelegt. In der Fig. 3 die minimale Differenz 34 für das Element p + gegeben, d.h. das Element p + ist verantwortlich für die noch zulässige maximale Stillstandszeit.To determine the maximum permissible downtime that is still permissible, the differences between the current stiffness values of the elements a to n and the current locally associated limit values 11, 12 are formed and from these differences (in FIG. 3, one of these differences for the element q is denoted by 33). the minimum difference selected. This minimum difference is used as the basis for calculating the maximum permitted downtime. In Fig. 3 the minimum difference 34 is given for the element p +, i.e. the element p + is responsible for the maximum permitted downtime.

Es ist mit dem Prozeßrechner weiters möglich, die für die Zukunft zulässige minimale noch zulässige Strangauziehgeschwindigkeit vmin zu bestimmen, indem für alle Elemente a bis n-1 jene Ausziehgeschwindigkeiten ermittelt werden, die für diese Elemente auf ihrem Weg bis zum Ende 14 des Richtaggregates 6 Steifigkeitswerte ergeben, die gerade noch unter den maximal zulässigen Grenzwerten 11, 12 liegen, und von diesen errechneten Ausziehgeschwindigkkeit die maximale Ausziehgeschwindigkeit ausgewählt wird.It is also possible with the process computer to determine the minimum still permissible strand pull-out speed v min that is permissible in the future by determining for all elements a to n-1 those pull-out speeds that are on their way to the end 14 of the straightening unit 6 for these elements Stiffness values result that are just below the maximum permissible limit values 11, 12, and from this calculated pull-out speed, the maximum pull-out speed is selected.

In Fig. 3 ist der sich bei Gießen mit minimal zulässiger Ausziehgeschwindigkeit vrnin ergebende Steifigkeitszuwachs (strichpunktierte Linie 35) für das Element q eingezeichnet Dieses Element q stellt in der in Fig. 3 dargestellten Momentanaufnahme der Steifigkeitswerte der Elemente das kritische Element dar, d.h. die minimale Ausziehgeschwindigkeit vnµn muß sich nach diesem Element richten, alle anderen Elemente würden eine geringere Ausziehgeschwindigkeit und damit einen höheren spezifischen Steifigkeitszuwachs gestattenFIG. 3 shows the increase in stiffness ( dash-dotted line 35) for element q during casting with a minimum permissible pull-out speed v rnin. This element q represents the critical element in the instantaneous recording of the stiffness values of the elements shown in FIG. 3, ie The minimum pull-out speed v n µ n must be based on this element; all other elements would allow a lower pull-out speed and thus a higher specific increase in stiffness

Wie ersichtlich, werden zur Bestimmung der noch zulässigen Restausziehzeit, der noch zulässigen maximalen Stillstandszeit und der noch zulässigen minimalen Ausziehgeschwindigkeit jeweils unterschiedliche Grenzwerte der die maximal zulässigen Steifigkeitswerte darstellenden Geraden 11 und 12 ausgewählt, u.zw. einmal zur Bestimmung der noch zulässigen Restausziehzeit die Schnittpunkte (z. B. 31, 32) mit Verlängerungen der den Steifigkeitszuwachs bei Weitergießen mit der aktuellen Gießgeschwindigkeit v darstellenden Geraden (z. B. 29,30); zur Bestimmung der maximal zulässigen Strangstillstandszeit die Werte der Geraden 11, 12, die sich beim Schnitt mit zur Ordinate der Fig. 2 und 3 parallelen Geraden (z. B. 33, 34) ergeben, und letztlich zur Bestimmung der noch zulässigen minimalen Ausziehgeschwindigkeit die Werte der Geraden, an die Tangenten (z. B. Gerade 35) an den Geradenzug 11, 12 ausgehend von den aktuellen Steifigkeitswerten gelegt werden.As can be seen, different limit values of the straight lines 11 and 12 representing the maximum permissible stiffness values are selected, etc., in order to determine the still permissible remaining pull-out time, the still permissible maximum downtime and the still permissible minimum pull-out speed. once to determine the remaining allowable pull-out time, the intersection points (e.g. 31, 32) with extensions of the straight line representing the increase in stiffness when pouring further at the current casting speed v (e.g. 29.30); to determine the maximum permissible strand standstill time, the values of the straight lines 11, 12 which result when intersecting with straight lines parallel to the ordinate of FIGS. 2 and 3 (e.g. 33, 34), and ultimately to determine the still permissible minimum pull-out speed Values of the straight line to which tangents (e.g. straight line 35) are placed on straight line 11, 12 based on the current stiffness values.

Wird die Kühlung des Stranges zur Bestimmung der zulässigen maximalen Restausziehzeit und der zulässigen minimalen Ausziehgeschwindigkeit ebenfalls berücksichtigt, so treten anstelle der Geraden 29, 30 und 35 entsprechende Kurven.If the cooling of the strand is also taken into account to determine the permissible maximum remaining pull-out time and the permissible minimum pull-out speed, curves 29, 30 and 35 are used instead of straight lines.

Ein weiterer Vorteil des erfindungsgemäßen Verfahrens ist darin zu sehen, daß aufgrund der von den einzelnen Elementen a bis n erreichten Steifigkeitswerte in den einzelnen Zonen der Strangführung bzw. den maximal auftretenden Steifigkeitswerten eine Statistik über die Belastung der Stranggießanlage bzw. der Elemente der Strangführung erstellt werden kann, aufgrund der Uberholzeiten der Anlage festgelegt werden können.Another advantage of the method according to the invention can be seen in the fact that, on the basis of the stiffness values achieved by the individual elements a to n in the individual zones of the strand guide or the maximum stiffness values that occur, statistics about the load on the continuous casting installation or the elements of the strand guide are created can be determined based on the overhaul times of the system.

Claims (8)

1. Method of surveying a bow-type continuous casting plant, in particular a bow-type continuous steel casting plant, where a curved strand (9) exiting from the strand guiding means (5) is straightened in a straightening means (6), characterised in that, in dependence upon the process parameters influencing the stiffness (15), i.e. the measure for the resistance to deformations, of the strand (9) on its way from the mould (3) to the end (14) of the straightening means (6), such as the strand withdrawal speed (v) , the allowed still permissible residual withdrawal time or the still permissible maximum standstill time or the still permissible minimum withdrawal speed (vnµn) of the strand (9) is determined and, upon exceeding of the still permissible residual withdrawal time or the still permissible maximum standstill time or upon passing below the minimum withdrawal speed based on the instantaneous withdrawal speed, an alarm signal is provided and/or the control of the plant is interfered with in a correcting manner, either by increasing the withdrawal speed (v) or by stopping casting.
2. Method according to claim 1, characterised in that a value is coordinated to each strand cross sectional element (a, b,... n) disposed at a certain distance from the casting level, the magnitude of which value corresponds to about the stiffness (15) of the element and for the determination of which primarily the withdrawal speed(s) (v) of the cross sectional element (a, b,...n) on its way from the casting level (13) to the definite distance from the casting level is employed, that the thus determined value for each element is each compared with a permissible limit value (31, 32 on 11, 12) depending upon the actual casting speed (v) , and that from the positive differences between the limit values and the determined values the minimum positive difference is used as the determining factor for the maximumly still permissible residual withdrawal time (Fig.3).
3. Method according to claim 1 or 2, characterised in that a value is coordinated to each strand cross sectional element (a, b,... n) disposed at a certain distance from the casting level, the magnitude of which value corresponds to about the stiffness (15) of the element and for the determination of which primarily the withdrawal speed(s) (v) of the cross sectional element (a, b, ...n) on its way from the casting level (13) to the definite distance from the casting level is employed, that a permissible limit value for the stiffness is coordinated to each element depending on the momentary position of the element, and that the determined value of the stiffness of each element is compared with the pertaining permissible limit value (11, 12) and that the minimum positive difference from all the positive differences (33, 34) between the limit values (11, 12) in each case and the determined values is selected and employed as the determining factor for the still permissible maximum standstill time (Fig. 3).
4. Method according to claims 1 to 3, characterised in that a value is coordinated to each strand cross sectional element (a, b,... n) disposed at a certain distance from the casting level, the magnitude of which value corresponds to about the stiffness (15) of the element and for the determination of which primarily the withdrawal speed(s) (v) of the cross sectional element (a, b,...n) on its way from the casting level (13) to the definite distance from the casting level is employed, that, departing from the value thus determined for each element a stiffness increase is determined, which, on the way of the element from its momentary distance from the casting level to the end (14) of the straightening means (6) at constant withdrawal speed, results in a stiffness value that is just below all the maximumly permissible limit values (11, 12), and that this stiffness increase is employed as the determining factor for a withdrawal speed of each element in each case, and that from these withdrawal speeds the maximum withdrawal speed is determined as the still permissible minimum withdrawal speed (Vmin) (Fig. 3).
5. Method according to claims 2 to 4, characterised in that the cooling conditions, in addition to the withdrawal speed, are employed, for the determination of the stiffness (15) of each element.
6. Method according to claims 2 to 5, characterised in that the cross sectional format, in addition to the withdrawal speed, is employed for the determination of the stiffness of each element.
7.Method according to claims 2 to 6, characterised in that the strand quality, in addition to the withdrawal speed, is employed for the determination of the stiffness of each element.
8. Method according to claims 2 to 7, characterised in that the permissible limit values (11, 12) employed for the determination of the maximumly still permissible residual withdrawal time or the maximum, still permissible standstill time or for the determination of the still permissible minimum withdrawal speed (vnµn) are determined in dependence upon construction conditioned strength values of the strand guiding means as well as, if desired, additionally upon the strand cross sectional format and/or the strand quality.
EP84890003A 1983-01-11 1984-01-05 Process for controlling a bow-type continuous casting machine Expired EP0116030B1 (en)

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AT0007483A AT378707B (en) 1983-01-11 1983-01-11 METHOD FOR MONITORING A CONTINUOUS CASTING PLANT
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EP0116030A2 EP0116030A2 (en) 1984-08-15
EP0116030A3 EP0116030A3 (en) 1985-09-11
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US4588020A (en) 1986-05-13
JPS59133960A (en) 1984-08-01
CA1196766A (en) 1985-11-19
AT378707B (en) 1985-09-25
DE3469855D1 (en) 1988-04-21
ATA7483A (en) 1985-02-15
EP0116030A2 (en) 1984-08-15
EP0116030A3 (en) 1985-09-11

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