EP0403035B1 - Method for attaining a temperature in a metal bath - Google Patents

Method for attaining a temperature in a metal bath Download PDF

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Publication number
EP0403035B1
EP0403035B1 EP90250080A EP90250080A EP0403035B1 EP 0403035 B1 EP0403035 B1 EP 0403035B1 EP 90250080 A EP90250080 A EP 90250080A EP 90250080 A EP90250080 A EP 90250080A EP 0403035 B1 EP0403035 B1 EP 0403035B1
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EP
European Patent Office
Prior art keywords
temperature
molten mass
target temperature
heating
heating power
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EP90250080A
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German (de)
French (fr)
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EP0403035A3 (en
EP0403035A2 (en
Inventor
Hans Josef Dr. Rer. Nat. Bebber
Karsten Dipl.-Ing. Brabandt
Bernhard Dipl.-Ing. Espendiller
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Vodafone GmbH
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Mannesmann AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/04—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like tiltable
    • B22D41/05—Tea-pot spout ladles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D2/00—Arrangement of indicating or measuring devices, e.g. for temperature or viscosity of the fused mass
    • B22D2/006—Arrangement of indicating or measuring devices, e.g. for temperature or viscosity of the fused mass for the temperature of the molten metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal

Definitions

  • the invention relates to a method for achieving a temperature of a molten metal at the outlet of a distribution channel, the heating energy required for this being generated by at least one plasma torch according to the preambles of claims 1 and 2.
  • EP-A1-0 180 741 discloses a method and a device for maintaining or increasing the temperature of a molten metal in a receptacle by supplying energy, the energy required for this being introduced by one or more plasma torches.
  • this document does not contain any information about how the heating power required for a predeterminable temperature should be measured.
  • the invention was based on the object of specifying a method which ensures that the temperature of a molten metal in a tundish at a predeterminable point, e.g. at the outlet of the vessel, even in the event of any interfering influences, corresponds to a predefinable temperature profile over time, the temperature profile in the simplest case also being constant (maintaining the temperature).
  • the heating power determined by the control which in principle can also have a profile depending on the time, can approximately achieve the desired profile of the target temperature in the event of non-occurring disturbances
  • the feedback of the measured temperature is used to a controller Adaptation of the heating power determined on the basis of the entered values to the heating power actually required to achieve the target temperature in the event of any interference.
  • the temperature profile of the molten metal is thus adjusted to a predefinable tolerance in relation to the target profile.
  • the melt does not remain in the distributor trough, but flows through, it is provided that the temperature of the melt upon entry into the distributor trough, the total mass of melt to be introduced into the distributor trough and its mass flow upon entry and exit of the distributor trough into the control system.
  • the control signal for the heating power must be taken into account, taking into account the system-related dead time, which results from the spatial separation of points along the path of the flowing mass with regard to its temperature profile results, be changed.
  • the distance between the plasma torch and the melt corresponding to the arc length is set to a low initial value and the current intensity is changed in accordance with the required heating power, the heating power required in each case is compared with a heating power characteristic value, which is possible at maximum current and the initial distance between the plasma torch and the melt and the power adjustment required for temperature control, as long as the required heating output is below the heating output characteristic value, only via the current (with the arc length equal to the initial distance) and, insofar as the required heating output is above the heating power value lies exclusively over the distance between the plasma torch and the melt (with the arc current equal to the maximum current).
  • the pouring or distribution channel 10 shown in FIG. 1 has an inlet 11 at one end and one or more outlets 19 to one or each of a continuous casting installation (not shown here) at the other end (such an installation is described, for example, in US Pat. PS 3,333,452).
  • One or more plasma torches 14 are passed through the cover 13 of the distributor trough 10, the distance a from the surface of the melt 12 corresponding to the arc length being changeable by a displacement device 15.
  • the plasma torch or torches 14 are connected to a current source 16.
  • a temperature measuring point T3 is provided at the at least one outlet of the distributor trough 10.
  • control and regulating device 17 which receives the measuring signal of the temperature of the measuring point T3 on the input side and is connected to the moving device 15 and the current source 16 with a separate output each.
  • the control and regulating device 17 for the distribution channel 10 consists of the adaptive control 31 and a control 32 (FIG. 2), which are linked to form a unit 33, and a power adjustment 34, the adaptive control 31 automatically adjusting its control program in accordance with by different Adapts initial conditions caused requirements (adapted).
  • the power adjustment 34 influences the current source 16 and the displacement device 15 within the controlled system 35 with the plasma torch 14 and the metal melt 12.
  • the heating power thus coupled directly influences the temperature T5 of the melt 12 below the at least one plasma torch 14.
  • this temperature T5 is a Dead time element t s is separated from the temperature T3 relevant for the process and thus for the control, which is fed back and compared with the target temperature curve T3 '(t) by a subtraction, the result of which is received in the controller 32.
  • the dead time t s is essentially due to the flow of the melt 12 in the channel 10 and the distance in the flow direction between the heat coupling through the at least one plasma torch 14 and the measuring point T3.
  • the controller 31 determines the control signals for the heating power Q ⁇ (t) required to achieve the temperature curve T3 ′ (t) to be achieved, without taking into account any interference that may occur.
  • the controller 31 also reacts automatically to changes in the process sequence (e.g. extension of a ladle change, delay in pouring, etc.), provided that these are entered by the staff using additional signals.
  • the controlled system 35 is in turn modeled in its various process states and, on the other hand, a reference temperature profile of the melt 12 in the distributor channel 10 is determined in the operating point state.
  • the control 32 in the event of a difference between the actual temperature T3 and the target temperature T3 '(t) which differs from zero or a predetermined torelance.
  • the control signal for heating power Q ⁇ (t) specified by the controller 31 changes taking into account the dead time t s such that the difference (T3 - T3 '(t)) develops back into the predefinable tolerance.
  • the power adjustment 34 queries whether the respective heating power Q ⁇ (t) is less than or equal to the heating power K (also referred to as the heating power characteristic value), the maximum current I max and a predetermined minimum distance a0 of the plasma torch 14 from the surface of the melt 12 can be reached.
  • the heating power Q ⁇ (t) specified by the controller 31 is less than or equal to the heating power K, the current intensity I is increased accordingly and, if the predetermined heating power Q ⁇ (t) is greater than the heating power K, the maximum current intensity I max leave and the distance a of the plasma torch 14 from the surface of the melt 12 is increased according to the predetermined heating power Q ⁇ (t) while increasing the arc voltage.
  • a double temperature feedback is provided in a further embodiment (FIG. 3).
  • a further temperature measuring point T5 which is set up in the distributor channel 10 below the plasma torch 14 (see dash-dotted connecting line in FIG. 3).
  • the measurement signal from the temperature measuring point 15 is fed into the controller 32 '.
  • the temperature of the melt 12 at the measuring point T3 now has essentially the same desired characteristic as the melt of the measuring point T5, since they are now separated from one another by the dead time element t s .
  • the difference between the target temperature T3' (t) and the temperature of the measuring point T3 is taken into account in a controller application control 37, taking into account the dead time t s which influences the control process of the controller 32 'in accordance with the temperature difference (T3' - T3) which is still present and thus adjusts T3 to the target curve T3 '(t).

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Furnace Details (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Description

Die Erfindung betrifft ein Verfahren zum Erzielen einer Temperatur einer Metallschmelze am Austritt einer Verteilerrinne, wobei die dazu erforderliche Heizenergie durch mindestens einen Plasmabrenner erzeugt wird gemäß den Oberbegriffen der Ansprüche 1 und 2.The invention relates to a method for achieving a temperature of a molten metal at the outlet of a distribution channel, the heating energy required for this being generated by at least one plasma torch according to the preambles of claims 1 and 2.

Aus der EP-A1-0 180 741 ist ein Verfahren und eine Vorrichtung zum Halten oder Erhöhen der Temperatur einer in einem Aufnahmegefäß befindlichen Metallschmelze durch Zuführen von Energie bekannt, wobei die dazu notwendige Energie durch einen oder mehrere Plasmabrenner eingebracht wird. Diese Schrift enthält aber keinerlei Angaben darüber, wie die für eine vorgebbare Temperatur notwendige Heizleistung bemessen werden soll. Desweiteren sind dort keinerlei zeitliche Randbedingungen für die zu erzielende Temperatur angesprochen.EP-A1-0 180 741 discloses a method and a device for maintaining or increasing the temperature of a molten metal in a receptacle by supplying energy, the energy required for this being introduced by one or more plasma torches. However, this document does not contain any information about how the heating power required for a predeterminable temperature should be measured. Furthermore, there are no time constraints for the temperature to be achieved.

Daneben sind auch Verfahren bekannt, bei denen die zum Heizen notwendige Energie durch eine mit der Verteilerrinne einer Stranggießanlage fest verbundene Induktionsheizung in die Metallschmelze eingebracht wird (vgl. z.B. EP-A1-0 132 280). Dieses Verfahren hat aber u.a. den Nachteil, daß für jedes Gefäß eine separate Heizeinrichtung vorhanden sein muß, was insbesondere bei Gießpfannen sehr aufwendig und nachteilig ist.In addition, methods are also known in which the energy required for heating is introduced into the metal melt by means of an induction heater which is firmly connected to the distribution channel of a continuous casting installation (cf., for example, EP-A1-0 132 280). However, this method has the disadvantage, among other things, that a separate heating device must be provided for each vessel, which is very complex and disadvantageous, particularly in the case of ladles.

Aus der DE-B-1 288 760, auf welcher die Oberbegriffe der unabhängigen Ansprüche 1 und 2 basieren, ist es bereits bekannt, die Heizleistung von Plasmabrennern automatisch zu steuern. Es liegen dort jedoch keine Hinweise auf ein erforderliches Temperatur-Regime vor.From DE-B-1 288 760, on which the preambles of independent claims 1 and 2 are based, it is already known to automatically control the heating power of plasma torches. However, there is no evidence of a required temperature regime.

Der Erfindung lag die Aufgabe zugrunde, ein Verfahren anzugeben, welches sicherstellt, daß die Temperatur einer Metallschmelze in einer Gießrinne an einer vorgebbaren Stelle, z.B. am Ausgang des Gefäßes, auch bei eventuell auftretenden Störeinflüssen einem vorgebbaren zeitlichen Temperaturverlauf entspricht, wobei der Temperaturverlauf im einfachsten Fall auch konstant sein kann (Halten der Temperatur).The invention was based on the object of specifying a method which ensures that the temperature of a molten metal in a tundish at a predeterminable point, e.g. at the outlet of the vessel, even in the event of any interfering influences, corresponds to a predefinable temperature profile over time, the temperature profile in the simplest case also being constant (maintaining the temperature).

Diese Aufgabe wird dadurch gelöst,

  • daß der zeitliche Verlauf einer Zieltemperatur, die Masse, ggf. der Massenstrom der ausfließenden Schmelze und die spezifischen Werte der Schmelze, wie Dichte, Fließfähigkeit und insbesondere spezifische Wärme, sowie Anlagen-Parameter, wie z.B. die Abmessungen des metallurgischen Gefäßes, die Ausmauerungsart oder die Oberflächenbeschaffenheit, in eine adaptive Steuerung eingegeben werden,
  • daß aus diesen Werten der Verlauf eines zur Verwirklichung des zu erzielenden Temperaturverlaufs erforderlichen Heizleistung entsprechenden Stellsignals ermittelt wird,
  • daß gleichzeitig und fortlaufend die tatsächliche Temperatur der Schmelze gemessen wird
  • und daß das Stellsignal für die Heizleistung im Falle einer von einer vorgebbaren Toleranz überschreitenden Abweichung der tatsächlichen Temperatur der Schmelze von ihrer Zieltemperatur mittels einer Regelung in dem Sinne verändert wird, daß es bei einer die Zieltemperatur überschreitenden tatsächlichen Temperatur erniedrigt und bei einer die Zieltemperatur unterschreitenden tatsächlichen Temperatur erhöht wird.
This task is solved
  • that the temporal course of a target temperature, the mass, possibly the mass flow of the outflowing melt and the specific values of the melt, such as density, flowability and in particular specific heat, as well as system parameters, such as the dimensions of the metallurgical vessel, the type of lining or the Surface condition, can be entered into an adaptive control,
  • that the curve of a control signal corresponding to the heating power required to achieve the temperature curve to be achieved is determined from these values,
  • that the actual temperature of the melt is measured simultaneously and continuously
  • and that the control signal for the heating power in the event of a deviation of a predeterminable tolerance of the actual temperature of the melt from its target temperature is changed by means of a control in the sense that it decreases at an actual temperature exceeding the target temperature and at an actual temperature below the target temperature Temperature is increased.

Während die von der Steuerung ermittelte Heizleistung, die grundsätzlich auch einen Verlauf in Abhängigkeit von der Zeit haben kann, den gewünschten Verlauf der Zieltemperatur für den Fall nicht auftretender Störungen der Erfahrung nach in etwa verwirklichen kann, dient die Rückkopplung der gemessen Temperatur an einen Regler der Anpassung der aufgrund der eingegebenen Werte ermittelten Heizleistung an die zur Verwirklichung der Zieltemperatur bei ggf. auftretenden Störeinflüssen tatsächlich erforderliche Heizleistung. Der Temperaturverlauf der Metallschmelze wird somit dem Zielverlauf gegenüber bis auf eine vorgebbare Toleranz ausgeregelt.While experience has shown that the heating power determined by the control, which in principle can also have a profile depending on the time, can approximately achieve the desired profile of the target temperature in the event of non-occurring disturbances, the feedback of the measured temperature is used to a controller Adaptation of the heating power determined on the basis of the entered values to the heating power actually required to achieve the target temperature in the event of any interference. The temperature profile of the molten metal is thus adjusted to a predefinable tolerance in relation to the target profile.

Da in der Verteilerrinne die Schmelze nicht verharrt, sondern durchfließt, ist vorgesehen, die Temperatur der Schmelze beim Eintritt in die Verteilerrinne, die insgesamt in die Verteilerrinne einzubringende Masse der Schmelze und deren Massenstrom beim Eintritt und beim Austritt der Verteilerrinne in die Steuerung einzugeben. Dabei muß, insoweit die tatsächliche Temperatur der Schmelze am Austritt der Verteilerrinne und nicht unterhalb der Leistungseinkopplung durch den Plasmabrenner gemessen wird, das Stellsignal für die Heizleistung unter Berücksichtigung der systembedingten Totzeit, die sich aus der räumlichen Trennung von Punkten am Wege der Fließmasse hinsichtlich deren Temperaturverlauf ergibt, verändert werden.Since the melt does not remain in the distributor trough, but flows through, it is provided that the temperature of the melt upon entry into the distributor trough, the total mass of melt to be introduced into the distributor trough and its mass flow upon entry and exit of the distributor trough into the control system. Insofar as the actual temperature of the melt is measured at the outlet of the distributor trough and not below the power coupling by the plasma torch, the control signal for the heating power must be taken into account, taking into account the system-related dead time, which results from the spatial separation of points along the path of the flowing mass with regard to its temperature profile results, be changed.

Es ist jedoch nach Anspruch 2 auch möglich, die Regelung des Stellsignals für die jeweils notwendige Heizleistung ohne Berücksichtigung einer systembedingten Totzeit zu betreiben, wenn zusätzlich zur Temperatur am Ausgang der Verteilerrinne die Temperatur in der Schmelze unterhalb des Plasmabrenners, also in der Wärmeeinbringungszone gemessen wird. In diesem Fall ist es sogar möglich, den Temperaturverlauf der Schmelze am Austritt der Verteilerrinne dem Zielverlauf gegenüber bis auf eine vorgebbare Toleranz auch unter Wegfall einer Steuerung auszuregeln.However, it is also possible according to claim 2 to operate the control signal for the heating power required in each case without taking into account a system-related dead time if, in addition to the temperature at the outlet of the distribution channel, the temperature in the melt is measured below the plasma burner, that is to say in the heat introduction zone. In this case, it is even possible to regulate the temperature profile of the melt at the outlet of the distribution channel with respect to the target profile up to a predeterminable tolerance even if a control is omitted.

Um die Anlage bei einem günstigen Wirkungsgrad zu fahren, ist weiterhin vorgesehen, den der Bogenlänge entsprechenden Abstand zwischen dem Plasmabrenner und der Schmelze auf einen geringen Anfangswert einzustellen und die Stromstärke entsprechend der erforderlichen Heizleistung zu verändern, die jeweils erforderliche Heizleistung mit einem Heizleistungskennwert zu vergleichen, der bei maximaler Stromstärke und dem Anfangsabstand zwischen dem Plasmabrenner und der Schmelze möglich ist und dem zur Temperaturführung erforderliche Leistungsanpassung, solange die erforderliche Heizleistung unterhalb des Heizleistungskennwertes liegt, ausschließlich über die Stromstärke (mit der Bogenlänge gleich dem Anfangsabstand) und, soweit die erforderliche Heizleistung über dem Heizleistungskennwert liegt, ausschließlich über den Abstand zwischen dem Plasmabrenner und der Schmelze (mit dem Bogenstrom gleich der Maximalstromstärke) vorzunehmen.In order to operate the plant at a favorable efficiency, it is further provided that the distance between the plasma torch and the melt corresponding to the arc length is set to a low initial value and the current intensity is changed in accordance with the required heating power, the heating power required in each case is compared with a heating power characteristic value, which is possible at maximum current and the initial distance between the plasma torch and the melt and the power adjustment required for temperature control, as long as the required heating output is below the heating output characteristic value, only via the current (with the arc length equal to the initial distance) and, insofar as the required heating output is above the heating power value lies exclusively over the distance between the plasma torch and the melt (with the arc current equal to the maximum current).

Ausführungsbeispiele der Erfindung sind in der Zeichnung zum Teil schematisch dargestellt und werden im folgenden näher erläutert. Es zeigen:

Fig. 1
eine Verteilerrinne für eine Stranggußanlage mit der zugehörigen Einrichtung zum geregelten Heizen der Schmelze,
Fig. 2
die Einrichtung zum geregelten Heizen der Metallschmelze in der Verteilerrinne in symbolischer Darstellung und
Fig. 3
eine abgewandelte Ausführungsform der Einrichtung zum geregelten Heizen der Schmelze in einer Verteilerrinne in symbolischer Darstellung
Exemplary embodiments of the invention are shown schematically in the drawing and are explained in more detail below. Show it:
Fig. 1
a distribution channel for a continuous casting plant with the associated device for controlled heating of the melt,
Fig. 2
the device for controlled heating of the molten metal in the distribution channel in a symbolic representation and
Fig. 3
a modified embodiment of the device for controlled heating of the melt in a distribution channel in a symbolic representation

Die in Fig. 1 dargestellte Gieß- oder Verteilerrinne 10 weist an einem Ende einen Einlaß 11 und am anderen Ende einen oder mehrere Auslässe 19 zu einer bzw. je einer (hier nicht dargestellten) Stranggießanlage auf (eine derartige Anlage ist beispielsweise in der US-PS 3 333 452 offenbart). Durch den Deckel 13 der Verteilerrinne 10 sind ein oder mehrere Plasmabrenner 14 durchgeführt, wobei der der Bogenlänge entsprechende Abstand a von der Oberfläche der Schmelze 12 durch eine Verfahreinrichtung 15 veränderbar ist. Der bzw. die Plasmabrenner 14 sind an eine Stromquelle 16 angeschlossen. An dem wenigstens einen Ausgang der Verteilerrinne 10 ist eine Temperaturmeßstelle T3 vorgesehen. Zwischen der Meßstelle T3 und der Verfahreinrichtung 15 und der Stromquelle 16 ist wiederum eine Steuer- und Regeleinrichtung 17 vorgesehen, die eingangsseitig das Meßsignal der Temperatur der Meßstelle T3 empfängt und mit je einem getrennten Ausgang mit der Verfahreinrichtung 15 bzw. der Stromquelle 16 verbunden ist.The pouring or distribution channel 10 shown in FIG. 1 has an inlet 11 at one end and one or more outlets 19 to one or each of a continuous casting installation (not shown here) at the other end (such an installation is described, for example, in US Pat. PS 3,333,452). One or more plasma torches 14 are passed through the cover 13 of the distributor trough 10, the distance a from the surface of the melt 12 corresponding to the arc length being changeable by a displacement device 15. The plasma torch or torches 14 are connected to a current source 16. A temperature measuring point T3 is provided at the at least one outlet of the distributor trough 10. Between the measuring point T3 and the moving device 15 and the current source 16 there is again a control and regulating device 17 which receives the measuring signal of the temperature of the measuring point T3 on the input side and is connected to the moving device 15 and the current source 16 with a separate output each.

Die Steuer- und Regeleinrichtung 17 für die Verteilerrinne 10 besteht aus der adaptiven Steuerung 31 und einer Regelung 32 (Fig. 2), die zu einer Einheit 33 verknüpft sind, und einer Leistungsanpassung 34, wobei die adaptive Steuerung 31 ihr Steuerprogramm wieder selbsttätig entsprechend den durch unterschiedliche Anfangsbedingungen verursachten Anforderungen anpaßt (adaptiert). Die Leistungsanpassung 34 beeinflußt die Stromquelle 16 und die Verfahreinrichtung 15 innerhalb der Regelstrecke 35 mit dem Plasmabrenner 14 und der Metallschmelze 12. Die so eingekoppelte Heizleistung beeinflußt direkt die Temperatur T5 der Schmelze 12 unter dem mindestens einen Plasmabrenner 14. Diese Temperatur T5 ist jedoch durch ein Totzeitglied ts von der für den Prozeß und somit für die Regelung relevanten Temperatur T3 getrennt, die rückgekoppelt mit dem Zieltemperaturverlauf T3'(t) durch eine Substraktion vergleichen wird, dessen Ergebnis in dem Regler 32 eingeht. Die Totzeit ts ist imwesentlichen durch das Fließen der Schmelze 12 in der Rinne 10 und durch den Abstand in Fließrichtung zwischen der Wärmeeinkopplung durch den mindestens einen Plasmabrenner 14 und der Meßstelle T3 bedingt.The control and regulating device 17 for the distribution channel 10 consists of the adaptive control 31 and a control 32 (FIG. 2), which are linked to form a unit 33, and a power adjustment 34, the adaptive control 31 automatically adjusting its control program in accordance with by different Adapts initial conditions caused requirements (adapted). The power adjustment 34 influences the current source 16 and the displacement device 15 within the controlled system 35 with the plasma torch 14 and the metal melt 12. The heating power thus coupled directly influences the temperature T5 of the melt 12 below the at least one plasma torch 14. However, this temperature T5 is a Dead time element t s is separated from the temperature T3 relevant for the process and thus for the control, which is fed back and compared with the target temperature curve T3 '(t) by a subtraction, the result of which is received in the controller 32. The dead time t s is essentially due to the flow of the melt 12 in the channel 10 and the distance in the flow direction between the heat coupling through the at least one plasma torch 14 and the measuring point T3.

Zum Erreichen des zeitlichen Verlaufs einer Zieltemperatur T3'(t) der Schmelze 12 werden am Anfang des Gießprozesses bzw. zu Beginn einer Prozeßänderung

  • der zeitliche Verlauf der Zieltemperatur T3'(t) und
  • als Anfangs- und Randbedingungen insbesondere
    • . die Temperatur T4 der Schmelze beim Eintritt 11 in die Verteilerrinne 10,
    • . die insgesamt in die Verteilerrinne 10 einzubringende Masse m2 der Schmelze,
    • . der Massenstrom (die Gießrate) ṁ11 der Schmelze beim Eintritt 11 in die Verteilerrinne 10,
    • . der Massenstrom ṁ19 am Ausgang 19 der Verteilerrinne 10,
    • . die spezifische Wärmekapazität der Schmelze 12,
    • . Anlagen-Parameter wie die Dicke der Ausmauerung der Verteilerrinne 10 usw.

in die adaptive Steuerung 31 und die Regelung 32 eingegeben.To achieve the time profile of a target temperature T3 '(t) of the melt 12, at the beginning of the casting process or at the beginning of a process change
  • the time course of the target temperature T3 '(t) and
  • as initial and boundary conditions in particular
    • . the temperature T4 of the melt at the entry 11 into the distribution channel 10,
    • . the total mass m2 of the melt to be introduced into the distribution channel 10,
    • . the mass flow (the pouring rate) ṁ11 of the melt as it enters 11 into the distribution channel 10,
    • . the mass flow ṁ19 at the outlet 19 of the distributor trough 10,
    • . the specific heat capacity of the melt 12,
    • . System parameters such as the thickness of the lining of the distribution channel 10, etc.

entered into the adaptive controller 31 and the controller 32.

Aus diesen Werten ermittelt die Steuerung 31 die Stellsignale für die zur Verwirklichung des zu erzielenden Temperaturverlaufs T3'(t) erforderlichen Heizleistung Q̇(t) ohne Berücksichtigung etwa auftretender Störeinflüsse.From these values, the controller 31 determines the control signals for the heating power Q̇ (t) required to achieve the temperature curve T3 ′ (t) to be achieved, without taking into account any interference that may occur.

Die Steuerung 31 reagiert aber selbsttätig auch auf Veränderungen des Prozeßablaufs (z.B. Verlängerung eines Pfannenwechsels, Verzögerung beim Abgießen usw.), sofern diese durch Zusatzsignale vom Personal eingegeben werden. Als Grundlage zur Steuerungsentwicklung ist dabei wiederum zum einen die Regelstrecke 35 in ihren verschiedenen Prozeßzuständen modelliert und zum anderen ein Referenztemperaturverlauf der Schmelze 12 in der Verteilerrinne 10 im Betriebspunktzustand festgelegt.The controller 31 also reacts automatically to changes in the process sequence (e.g. extension of a ladle change, delay in pouring, etc.), provided that these are entered by the staff using additional signals. As a basis for the control development, the controlled system 35 is in turn modeled in its various process states and, on the other hand, a reference temperature profile of the melt 12 in the distributor channel 10 is determined in the operating point state.

Gleichzeitig mit der Eingabe der genannten Daten und fortlaufend wird die Isttemperatur T3 der Schmelze 12 am Ausgang 19 der Verteilerrinne 10 gemessen, wobei die Regelung 32 im Falle einer von Null oder einer vorgegebenen torelanzabweichenden Differenz zwischen der Isttemperatur T3 und der Zieltemperatur T3'(t) das von der Steuerung 31 vorgegebene Stellsignal zur Heizleistung Q̇(t) unter Berücksichtigung der Totzeit ts derart verändert, daß sich die aufgetretene Differenz (T3 - T3'(t)) in die vorgebbare Toleranz zurückentwickelt.Simultaneously with the input of the above-mentioned data and continuously, the actual temperature T3 of the melt 12 is measured at the outlet 19 of the distributor trough 10, the control 32 in the event of a difference between the actual temperature T3 and the target temperature T3 '(t) which differs from zero or a predetermined torelance. the control signal for heating power Q̇ (t) specified by the controller 31 changes taking into account the dead time t s such that the difference (T3 - T3 '(t)) develops back into the predefinable tolerance.

In der Leistungsanpassung 34 wird abgefragt, ob die jeweilige Heizleistung Q̇(t) kleiner oder gleich der (auch als Heizleistungskennwert bezeichneten) Heizleistung K ist, die mit maximaler Stromstärke Imax und einem am Anfang vorgegebenen Mindestabstand a₀ des Plasmabrenners 14 von der Oberfläche der Schmelze 12 erreichbar ist.The power adjustment 34 queries whether the respective heating power Q̇ (t) is less than or equal to the heating power K (also referred to as the heating power characteristic value), the maximum current I max and a predetermined minimum distance a₀ of the plasma torch 14 from the surface of the melt 12 can be reached.

Sofern die von der Steuerung 31 vorgegebene Heizleistung Q̇(t) jeweils kleiner oder gleich der Heizleistung K ist, wird die Stromstärke I entsprechend erhöht und, sofern die vorgegebene Heizleistung Q̇(t) größer als die Heizleistung K ist, wird die maximale Stromstärke Imax belassen und der Abstand a des Plasmabrenners 14 von der Oberfläche der Schmelze 12 entsprechend der vorgegebenen Heizleistung Q̇(t) unter Erhöhung der Bogenspannung vergrößert.If the heating power Q̇ (t) specified by the controller 31 is less than or equal to the heating power K, the current intensity I is increased accordingly and, if the predetermined heating power Q̇ (t) is greater than the heating power K, the maximum current intensity I max leave and the distance a of the plasma torch 14 from the surface of the melt 12 is increased according to the predetermined heating power Q̇ (t) while increasing the arc voltage.

Um das regelungstechnische Problem der systembedingten Totzeit ts zu umgehen und somit auf eine adaptive Steuerung verzichten zu können, ist in einem weiteren Ausführungsbeispiel eine zweifache Temperaturrückführung vorgesehen (Fig. 3). Dabei wird zusätzlich zu der Temperaturmeßstelle T3 am Ausgang 19 der Rinne 10 von einer weiteren Temperaturmeßstelle T5 Gebrauch gemacht, die in der Verteilerrinne 10 unterhalb des Plasmabrenners 14 eingerichtet ist (vgl. strichpunktierte Verbindungslinie in Fig. 3). Das Meßsignal der Temperaturmeßstelle 15 geht nach einem subtrahierenden Temperaturvergleich in den Regler 32' ein. Durch diese Maßnahme des Erstellens eines totzeitlosen, T5-rückgekoppelten Regelkreises ist es möglich, die Temperatur der Schmelze 12 an der Meßstelle T5 ständig und unabhängig von Störungen auf einem vorgegebenen Wert zu halten bzw. entsprechend einem vorgebbaren Verlauf anzupassen.In order to avoid the control problem of the system-related dead time t s and thus to be able to dispense with an adaptive control, a double temperature feedback is provided in a further embodiment (FIG. 3). In addition to the temperature measuring point T3 at the outlet 19 of the channel 10, use is made of a further temperature measuring point T5, which is set up in the distributor channel 10 below the plasma torch 14 (see dash-dotted connecting line in FIG. 3). After a subtracting temperature comparison, the measurement signal from the temperature measuring point 15 is fed into the controller 32 '. This measure of creating a dead-time-free, T5-feedback control loop makes it possible to keep the temperature of the melt 12 at the measuring point T5 constantly and independently of faults at a predetermined value or to adapt it according to a predeterminable course.

Folglich hat nun auch die Temperatur der Schmelze 12 an der Meßstelle T3 im wesentlichen die gleiche gewünschte Charakteristik wie die Schmelze der Meßstelle T5, da sie nun durch das Totzeitglied ts voneinander getrennt sind. Um die Schmelze 12 der Meßstelle T3 nun auch absolut dem gewünschten Wert des vorgegebenen Temperaturverlaufes T3'(t) anzupassen, geht die Differenz der Zieltemperatur T3'(t) und der Temperatur der Meßstelle T3 unter Berücksichtigung der Totzeit ts in eine Reglereinsatzregelung 37 ein, die gemäß der noch bestehenden Temperaturdifferenz (T3' - T3) den Regelungsprozeß des Reglers 32' beeinflußt und somit T3 dem Zielverlauf T3'(t) anpaßt.Consequently, the temperature of the melt 12 at the measuring point T3 now has essentially the same desired characteristic as the melt of the measuring point T5, since they are now separated from one another by the dead time element t s . In order to also absolutely adapt the melt 12 of the measuring point T3 to the desired value of the predetermined temperature profile T3 '(t), the difference between the target temperature T3' (t) and the temperature of the measuring point T3 is taken into account in a controller application control 37, taking into account the dead time t s which influences the control process of the controller 32 'in accordance with the temperature difference (T3' - T3) which is still present and thus adjusts T3 to the target curve T3 '(t).

Claims (3)

  1. A method of realizing a temporal course of a target temperature of a molten metal mass at the outlet of a distribution channel, the heating energy necessary for this being produced by at least one automatically controlled plasma torch, characterised
    - in that the temporal course of a target temperature (T3'(t)) of the molten mass, the temperature (T4) of the molten mass at the inlet (11) into the distribution channel (10), the mass (m2) of the molten mass that is to be introduced altogether into the distribution channel (10), the mass flow (m11, m19) thereof at the inlet (11) into and respectively at the outlet (19) from the distribution channel (10) and the specific values, such as density, flowability and specific heat, of the molten mass (12) as well as installation parameters, such as dimensions of the metallurgical vessel, type of lining or surface condition, are entered into an adaptive control (31),
    - in that from these values the course of an adjusting signal corresponding to the heating power (Q(t)) necessary for the realization of the temperature course that is to be achieved is ascertained,
    - in that at the same time and continuously the actual temperature T3 of the molten mass (12) at the outlet (19) of the distribution channel (10) is measured,
    - and in that the adjusting signal for the heating power (Q(t)) in the event of a deviation, excessive by a specifiable tolerance, of the actual temperature of the molten mass (12) from its target temperature (T3'(t)) is varied by means of an adjustment (32), taking into account the system-dictated dead time (ts), in the sense that it is lowered in the case of an actual temperature which exceeds the target temperature and is raised in the case of an actual temperature which falls below the target temperature.
  2. A method of realizing a temporal course of a target temperature of a molten metal mass at the outlet of a distribution channel, the heating energy necessary for this being produced by at least one automatically controlled plasma torch, characterised
    - in that the actual temperature (T3) regarding the molten mass (12) at the outlet (19) and the temperature (T5) of the molten mass under the zone of influence of the plasma torch is continuously measured
    - and in that the adjusting signal for the heating power (Q(t)) in the event of a deviation, excessive by a specifiable tolerance, of the actual temperature (T3) of the molten mass (12) from its target temperature (T3'(t)) is varied by means of an adjustment (32') and a regulator operation adjustment (37) in the sense that it is lowered in the case of an actual temperature which exceeds the target temperature and is raised in the case of an actual temperature which falls below the target temperature.
  3. A method according to one of claims 1 or 2, characterised
    - in that the distance (a), corresponding to the arc length, between the plasma torch (4, 14) and the molten mass (2, 12) is set to a low initial value (a₀) and first of all the current intensity (I) is varied in accordance with the necessary heating power (Q(t)),
    - in that the respectively necessary heating power (Q(t)) is compared with a heating-power characteristic value (K) which is possible in the case of maximum current intensity (ImaX) and the initial distance (a₀) between the plasma torch (4, 14) and the molten mass (2, 12)
    - and in that the power adaptation (24, 34) necessary for the temperature profile is effected, so long as the necessary heating power (Q(t)) lies below the heating-power characteristic value (K), exclusively by way of the current intensity (I) and, insofar as the necessary heating power (Q(t)) lies above the heating-power characteristic value (K), exclusively by way of the distance (a) between the plasma torch (4, 14) and the molten mass (2, 12).
EP90250080A 1989-05-12 1990-03-22 Method for attaining a temperature in a metal bath Expired - Lifetime EP0403035B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3915619 1989-05-12
DE3915619A DE3915619A1 (en) 1989-05-12 1989-05-12 METHOD FOR OBTAINING A TEMPERATURE OF A METAL MELT

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EP0403035A2 EP0403035A2 (en) 1990-12-19
EP0403035A3 EP0403035A3 (en) 1991-03-27
EP0403035B1 true EP0403035B1 (en) 1994-01-19

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US5793022A (en) * 1996-09-12 1998-08-11 Applied Materials, Inc. Adaptive temperture controller and method of operation
GB2352992B (en) * 1999-08-05 2002-01-09 Pyrotek Engineering Materials Distributor device
DE102014213744A1 (en) * 2014-07-15 2016-01-21 Primetals Technologies Germany Gmbh Electric arc furnace with a safety device and method for securing peripheral devices to electric arc furnaces
CN114178504B (en) * 2021-12-13 2022-09-02 北京航星机器制造有限公司 Intelligent temperature control method for low-pressure casting aluminum alloy melt

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Publication number Priority date Publication date Assignee Title
US3333452A (en) * 1965-03-03 1967-08-01 Sendzimir Inc T Reduction of thick flat articles
DE1288760B (en) * 1966-06-14 1969-02-06 Coupette Method for controlling temperature and steel analysis during continuous casting and device for this
SU762216A1 (en) * 1978-10-11 1980-09-07 Boris P Polkov Multiphase ore-thermal electric furnace power regulator
US4323763A (en) * 1979-05-14 1982-04-06 Gca Corporation Parametric power controller
US4486211A (en) * 1980-06-27 1984-12-04 Energy Fibers Int'l Corp. Apparatus and methods of operation for converting fly ash into high quality mineral wool
JPS58100951A (en) * 1981-12-09 1983-06-15 Nippon Steel Corp Temperature controlling method for molten steel for continuous casting
US4484947A (en) * 1983-04-22 1984-11-27 North American Manufacturing Company Method for melting a charge of bulk solid metal
DE3443740A1 (en) * 1984-10-11 1986-04-17 Fried. Krupp Gmbh, 4300 Essen METHOD AND DEVICE FOR HOLDING OR INCREASING THE TEMPERATURE OF A METAL MELT
SU1453631A1 (en) * 1987-01-07 1989-01-23 Специальное проектно-конструкторское и технологическое бюро электротермического оборудования Производственного объединения "Сибэлектротерм" Method of automatic control of electric duty of steel-melting arc furnace
DE3810292A1 (en) * 1988-03-25 1989-10-05 Rexroth Mannesmann Gmbh Device for controlling an arc furnace by hydraulically adjusting the height of the electrode

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DE59004280D1 (en) 1994-03-03
JP2925655B2 (en) 1999-07-28
JPH03468A (en) 1991-01-07
KR900017697A (en) 1990-12-19
EP0403035A3 (en) 1991-03-27
DE3915619A1 (en) 1990-11-15
ZA903344B (en) 1991-02-27
EP0403035A2 (en) 1990-12-19
US5081640A (en) 1992-01-14

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