EP0028761B1 - Method of stirring during continuous casting - Google Patents

Method of stirring during continuous casting Download PDF

Info

Publication number
EP0028761B1
EP0028761B1 EP80106596A EP80106596A EP0028761B1 EP 0028761 B1 EP0028761 B1 EP 0028761B1 EP 80106596 A EP80106596 A EP 80106596A EP 80106596 A EP80106596 A EP 80106596A EP 0028761 B1 EP0028761 B1 EP 0028761B1
Authority
EP
European Patent Office
Prior art keywords
stirrer
phase
stirring
current
phases
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP80106596A
Other languages
German (de)
French (fr)
Other versions
EP0028761A1 (en
Inventor
Sten Dipl.Ing. Kollberg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB Norden Holding AB
Original Assignee
ASEA AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ASEA AB filed Critical ASEA AB
Publication of EP0028761A1 publication Critical patent/EP0028761A1/en
Application granted granted Critical
Publication of EP0028761B1 publication Critical patent/EP0028761B1/en
Expired legal-status Critical Current

Links

Images

Classifications

    • 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
    • B22D11/12Accessories for subsequent treating or working cast stock in situ
    • B22D11/122Accessories for subsequent treating or working cast stock in situ using magnetic fields

Definitions

  • the invention relates to a method for stirring during continuous casting according to the preamble of claim 1. Such a method is known from DE-A-2911842.
  • the frequency f of the multiphase current can be in the range 0 ⁇ f ⁇ 10 Hz, normally when stirring in so-called slabs (plates) which have a large cross section.
  • it is usually a stirring in the transverse direction, the stirring direction being approximately perpendicular to the pouring direction, while in the other case it is usually a stirring in the longitudinal direction, that is, in the pouring direction.
  • a disadvantage of the aforementioned type of asymmetrical stirring is the relatively poor utilization of the stirrer, since the iron core and the winding of the stirrer are not fully used.
  • a stirrer in the casting strand creates, on the one hand, a stirring force which migrates in the longitudinal direction of the stirrer and is shaped according to the square of a sine function and runs between zero and a maximum and which, when integrated at a fixed location on the casting strand for a certain time, creates a stirring force results in the longitudinal direction of the stirrer resulting stirring force, and on the other hand a substantially sinusoidal, in the longitudinal direction of the stirrer wandering, between an absolutely equal positive maximum and negative minimum, transverse force acting across the surface of the stirrer or the corresponding pole piece, the integral of which at a fixed Position of the casting strand over a certain period of time gives the value zero and therefore does not provide any resulting force, and a (superposed) stationary, temporally and spatially associated in the longitudinal direction of the stirrer, which periodically changes between 0 and a maximum, transverse force acting essentially transversely to the surface of the stirrer or the corresponding pole piece, this superposed trans
  • the last-mentioned force is generated by the asymmetric stirring, while the two first-mentioned forces in the 'essentially by the symmetrical stirrer, however partially also generated by the asymmetric stirrer.
  • the symmetrical agitation is therefore essentially responsible for the motor agitation, while the asymmetric agitation is essentially responsible for the turbulence that occurs, which reduces the viscosity of the melt and contributes to avoiding the so-called white bands.
  • the invention has for its object to develop a method for stirring in continuous casting, in which the stirrers are better used and with which the turbulence in the liquid region of the strand can be adjusted very well.
  • the first and / or second stirrer are / are fed by a phase-asymmetrical current source, wherein the stirrer (s) can be constructed symmetrically or asymmetrically.
  • the stirrer (s) can also be supplied with a different current intensity in one phase relative to at least one other phase.
  • the asymmetry of the stirrer and the current source should correspond to a current difference of 10% (with a pure current asymmetry).
  • the vector diagram according to FIG. 4 shows a three-phase current system R, S, T, the current asymmetry being produced, for example, by the current vector of phase T being smaller than the current vectors of phases R and S, which are of equal size.
  • Figure 5 shows the current vector diagram of a three-phase current system R, S, T in which phase asymmetry has been introduced.
  • the phase angle between the phases R and T is increased by ⁇ ° compared to the symmetrical value of 120 ° and the phase angle between the phases T and S is reduced accordingly by ⁇ °.
  • a is preferably more than 5 °.
  • This phase asymmetry can be achieved, for example, by later ignition of the thyristor feeding the phase T.
  • the phase-asymmetrical feed causes an asymmetrical stirring, which results in a better casting structure, for example in the case of an asymmetrical stirrer 1 (see FIG. 1) which stirs the non-solidified region of a casting strand 3 in accordance with the invention.
  • Figure 1 shows the stirring in the transverse or longitudinal direction of the strand in billets, blooms or slabs with, for example, an electromagnetic, multi-phase-fed stirrer 1, which is designed for asymmetrical stirring, that the supply is either two-phase with a deviation of 90 ° between the two phases or three-phase with a shift between the phases deviating from 120 °.
  • the second stirrer 2 is fed with the same phase system as the first stirrer, but either symmetrically or with a different type of asymmetry than the first stirrer.
  • the stirrers can possibly face each other and both can be designed for stirring in the transverse direction or both for stirring in the longitudinal direction. In special cases, the arrangement angle between the stirrer and the pouring direction can be different for the two stirrers 1 and 2. In both cases, the two stirrers 1, 2 can also be supplied with a phase-asymmetrical stirrer.
  • FIG. 2 shows two three-phase stirrers 1, 2 which are arranged opposite one another on the casting strand 3 emerging from the casting mold 4. Both stirrers have the same direction of stirring. The course of the stirring is indicated by the arrows 5.
  • the second stirrer 2 can work with a mutual phase shift, and with an asymmetry in the phase currents such that the current of one phase deviates by at least 10% from the current of another phase. So a stirrer is used here, in which two options for creating an asymmetry are used simultaneously.
  • the second stirrer 2 can also work with a mutual displacement of the phase currents and an asymmetrical configuration of the phase windings with one another, so that a combination of phase asymmetry and amplitude asymmetry arises.
  • FIG. 3 shows two stirrers 1 and 2 which are arranged one behind the other along the casting strand, for example when pouring billets; here too the same deviations between the two stirrers 1 and 2 can be provided as in the arrangements according to FIGS.
  • both stirring in the transverse direction and stirring in the longitudinal direction can be provided for the two stirrers 1 and 2, as indicated in FIG. 3.
  • Efforts are made to adapt the stirring forces between the stirrers 1 and 2 so that the stirring extends into the mold, ie the stirring flow should extend high into the mold and the white bands should disappear. It is necessary to adjust the stirring force of the stirrer 1 relative to the stirring force of the stirrer 2 so that one of the two stirrers does not dominate too much, which worsens the stirring effect.
  • the ampere turns number for at least one phase deviates by at least 10% from the ampere turn number in another phase.
  • a magnetic traveling wave and a stationary field are thus obtained, and the stirrers are linear and straight.
  • a greater turbulence is obtained under the stirrer, which can be achieved with the various combinations which have been explained above and are shown in the figures.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Mixers With Rotating Receptacles And Mixers With Vibration Mechanisms (AREA)

Description

Die Erfindung betrifft ein Verfahren zum Umrühren beim Stranggießen gemäß dem Oberbegriff des Anspruches 1.'- Ein solches Verfahren ist bekannt aus der DE-A-2911842.The invention relates to a method for stirring during continuous casting according to the preamble of claim 1. Such a method is known from DE-A-2911842.

Das Umrühren der nicht erstarrten Bereiche eines Gießstranges ist bereits in verschiedenen Ausführungen bekannt. U.a. ist es bekannt, diese Bereiche mittels eines elektromagnetischen Umrührers quer zur Gießrichtung an einer oder mehreren Stellen umzurühren. Ein Grund für diese Umrührung besteht darin, daß man Lunker (sogenannte mini-ingots) und Seigerungen in dem fertigen Gußstück (Rohling) vermeiden möchte und daß man eine möglichst gleichmäßige Erstarrungsfront anstrebt. Ein Problem bei dieser Art der Umrührung besteht jedoch darin, daß sogenannte weiße Bänder, d.h. Bänder mit negativer Seigerung entstehen, wenn die Schmelze hierbei allzu plötzlich in eine allzu kräftige Rührbewegung versetzt wird. Beim Erstarren von Stahl bilden sich nämlich Kristalle, sogenannte Dendrite, zwischen denen eine Anreicherung von Schwefel und Kohlenstoff stattfindet. Bei einer üblichen Umrührung werden diese Anreicherungen unter die Schmelze , gerührt und durch eine andere Schmelze ersetzt, wordurch die sogenannten weißen Bänder entstehen.The stirring of the non-solidified areas of a casting strand is already known in various designs. Among other things it is known to stir these areas by means of an electromagnetic stirrer at one or more points transversely to the pouring direction. One reason for this stirring is that cavities (so-called mini-ingots) and segregations in the finished casting (blank) are to be avoided and that the solidification front is as uniform as possible. A problem with this type of stirring, however, is that so-called white bands, i.e. Bands with negative segregation are formed when the melt is suddenly set into an all too vigorous stirring movement. When steel solidifies, crystals, so-called dendrites, form between which there is an accumulation of sulfur and carbon. In the case of a normal stirring, these accumulations are stirred under the melt and replaced by another melt, resulting in the so-called white bands.

Eine Möglichkeit, das vorgenannte Problem zu Iösen,` ist aus der DE-A-2911842 bekannt. Danach wird der elektromagnetische Umrührer mit mehrphasigem Strom gespeist, wobei das Umrühren dadurch asymmetrisch erfolgt, daß entweder der Phasenstrom in einer Phase um mindestens 10% vom Phasenstrom in einer anderen Phase abweicht und/oder daß die Phasenspulen untereinander asymmetrisch ausgeführt sind. Hierdurch erhält man eine bessere Gußstruktur als bei einer symmetrischen Speisung. Der Umrührer kann normalerweise symmetrisch aufgebaut sein, doch ist es auch vorstellbar, die Phasenspulen im Umrührer asymmetrisch aufzubauen, so daß man eine asymmetrische Umrührung bei symmetrischer Speisung erhält.One way of solving the above-mentioned problem is known from DE-A-2911842. Thereafter, the electromagnetic stirrer is fed with multiphase current, the stirring being effected asymmetrically, either that the phase current in one phase deviates by at least 10% from the phase current in another phase and / or that the phase coils are asymmetrical to one another. This gives a better casting structure than with a symmetrical feed. The stirrer can normally be constructed symmetrically, but it is also conceivable to construct the phase coils in the stirrer asymmetrically, so that one obtains an asymmetrical stirring with symmetrical feeding.

Die Frequenzf des mehrphasigen Stromes kann im Bereich 0<f≦10 Hz liegen, und zwar normalerweise beim Umrühren in sog. slabs (Platten), die einen großen Querschnitt haben. Jedoch kann man auch eine Frequenz zwischen 10 bis 30 Hz bei sog. blooms (Luppen), also mittelgroßen Rohlingen, oder eine Frequenz zwischen 50 bis 60 Hz bei kleineren Rohlingen, sog. billets (Barren) anwenden. In dem erstgenannten Fall handelt es sich normalerweise um ein Umrühren in Querrichtung, wobei die Umrührrichtung etwa senkrecht zur Gießrichtung liegt, während es sich in dem anderen Fall normalerweise um eine Umrühren in Längsrichtung, also in Gießrichtung handelt. Ein Nachteil bei der vorgenannten Art der asymmetrischen Umrührung besteht in der verhältnismäßig schlechten Ausnutzung des Umrührers, da Eisenkern und Wicklung des Umrührers nicht voll ausgenutzt werden.The frequency f of the multiphase current can be in the range 0 <f ≦ 10 Hz, normally when stirring in so-called slabs (plates) which have a large cross section. However, one can also use a frequency between 10 to 30 Hz for blooms (loops), i.e. medium-sized blanks, or a frequency between 50 to 60 Hz for smaller blanks, so-called billets. In the former case, it is usually a stirring in the transverse direction, the stirring direction being approximately perpendicular to the pouring direction, while in the other case it is usually a stirring in the longitudinal direction, that is, in the pouring direction. A disadvantage of the aforementioned type of asymmetrical stirring is the relatively poor utilization of the stirrer, since the iron core and the winding of the stirrer are not fully used.

In bekannter Weise entstehen durch einen Umrührer im Gießstrang einerseits eine in Längsrichtung des Umrührers wandernde, entsprechend dem Quadrat einer Sinusfunktion geformte, zwischen Null und einem Maximum verlaufende Umrührkraft, die, wenn sie an einer festen Stelle des Gießstrangs über eine bestimmte Zeit integriert wird, eine in Längsrichtung des Umrührers resultierende Umrührkraft ergibt, und andererseits eine im wesentlichen sinusförmige, in Längsrichtung des Umrührers wandernde, zwischen einem absolut gleich großen positiven Maximum und negativen Minimum verlaufende, quer zur Oberfläche des Umrührers oder des entsprechenden Polschuhs wirkende Querkraft, deren Integral an einer festen Stelle des Gießstrangs über eine bestimmte Zeit den Wert Null ergibt und die somit keine resultierende Kraft liefert, und eine diesen beiden Kräften zugeordnete (superponierte), stationäre, zeitlich und räumlich in Längsrichtung des Umrührers sich periodisch zwischen 0 und einem Maximum ändernde, im wesentlichen quer zur Oberfläche des Umrührers oder des entsprechenden Polschuhs wirkenden Querkraft, wobei diese superponierte Querkraft eine starke Erhöhung der Turbulenz in der Strömung im flüssigen Kern des Gießstranges erzeugt. Die letztgenannte Kraft entsteht durch das asymmetrische Umrühren, während die beiden erstgenannten Kräfte im' wesentlichen durch den symmetrischen Umrührer, jedoch teilweise auch von dem asymmetrischen Umrührer erzeugt werden. Die symmetrische Umrührung ist also im wesentlichen für 'die motorische Umrührung verantwortlich, während die asymmetrische Umrührung im wesentlichen für die auftretende Turbulenz verantwortlich ist, welche die Viskosität der Schmelze verringert und zu einer Vermeidung der sogenannten weißen Bänder beiträgt.In a known manner, a stirrer in the casting strand creates, on the one hand, a stirring force which migrates in the longitudinal direction of the stirrer and is shaped according to the square of a sine function and runs between zero and a maximum and which, when integrated at a fixed location on the casting strand for a certain time, creates a stirring force results in the longitudinal direction of the stirrer resulting stirring force, and on the other hand a substantially sinusoidal, in the longitudinal direction of the stirrer wandering, between an absolutely equal positive maximum and negative minimum, transverse force acting across the surface of the stirrer or the corresponding pole piece, the integral of which at a fixed Position of the casting strand over a certain period of time gives the value zero and therefore does not provide any resulting force, and a (superposed) stationary, temporally and spatially associated in the longitudinal direction of the stirrer, which periodically changes between 0 and a maximum, transverse force acting essentially transversely to the surface of the stirrer or the corresponding pole piece, this superposed transverse force producing a strong increase in the turbulence in the flow in the liquid core of the casting strand. The last-mentioned force is generated by the asymmetric stirring, while the two first-mentioned forces in the 'essentially by the symmetrical stirrer, however partially also generated by the asymmetric stirrer. The symmetrical agitation is therefore essentially responsible for the motor agitation, while the asymmetric agitation is essentially responsible for the turbulence that occurs, which reduces the viscosity of the melt and contributes to avoiding the so-called white bands.

Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren zum Umrühren beim Stranggießen zu entwickeln, bei welchem die Umrührer besser ausgenutzt werden und mit welchem sich die Turbulenz in dem flüssigen Bereich des Stranges sehr gut einstellen läßt.The invention has for its object to develop a method for stirring in continuous casting, in which the stirrers are better used and with which the turbulence in the liquid region of the strand can be adjusted very well.

Zur Lösung dieser Aufgabe wird ein Verfahren gemäß dem Oberbegriff des Anspruches 1 vorgeschlagen, welches erfindungsgemäß die im kennzeichnenden Teil des Anspruches 1 genannten Merkmale hat.To achieve this object, a method is proposed according to the preamble of claim 1, which according to the invention has the features mentioned in the characterizing part of claim 1.

Vorteilhafte Ausgestaltungen der Erfindung sind in den weiteren Ansprüchen genannt.Advantageous embodiments of the invention are mentioned in the further claims.

Durch die Verwendung von zwei Umrührern gemäß der Erfindung erhält man eine Verbesserung der Struktur des durch eine kontinuierliche Stranggießmaschine gegossenen Stranges. Durch die Phasenasymmetrische Speisung des einem Umrührers und die amplitudenasymmetrische Speisung des anderen Umrührers erhält man zwei einstellbare Parameter, mit denen sich die Turbulenz in sehr genauer und gezielter Weise einstellen läßt. Zugleich wird durch die phasenasymmetrische Speisung des mindestens einen Umrührers eine bedeutend bessere Ausnutzung dieses Umrührers erreicht, da der Strombelag an allen Stellen des Umrührers gleich groß ist.By using two stirrers according to the invention, there is an improvement in the structure of the strand cast by a continuous casting machine. The phase-asymmetrical supply of one stirrer and the amplitude-asymmetrical supply of the other stirrer result in two adjustable parameters with which the turbulence changes can be set in a very precise and targeted manner. At the same time, the phase-asymmetrical feeding of the at least one stirrer achieves a significantly better utilization of this stirrer, since the current coating is of the same size at all points of the stirrer.

Der erste und/oder zweite Umrührer werden/wird von einer phasenasymmetrischen Stromquelle gespeist, wobei der/die Umrührer symmetrisch oder asymmetrisch aufgebaut sein kann/können.The first and / or second stirrer are / are fed by a phase-asymmetrical current source, wherein the stirrer (s) can be constructed symmetrically or asymmetrically.

Der/die Umrührer kann/können auch mit abweichender Stromstärke in einer Phase relativ zu mindestens einer anderen Phase gespeist werden.The stirrer (s) can also be supplied with a different current intensity in one phase relative to at least one other phase.

Insgesamt soll die Asymmetrie des Umrührers und der Stromquelle einem Stromunterschied von 10% (bei einer reinen Stromasymmetrie) entsprechen.Overall, the asymmetry of the stirrer and the current source should correspond to a current difference of 10% (with a pure current asymmetry).

Anhand der Figuren soll die Erfindung näher erläutert werden. Es zeigen

  • Fig. 1 eine erste Art der Anordnung vom Umrührern zur Durchführung des Verfahrens nach der Erfindung,
  • Fig. 2 eine zweite Art der Anordnung vom Umrührem zur Durchführung des Verfahrens gemäß der Erfindung,
  • Fig: 3 eine dritte Art der Anordnung der Umrührer zur Durchführung des Verfahrens gemäß der Erfindung,
  • Fig. 4 das Stromzeigerdiagramm bei stromasymmetrischer Umrührung,
  • Fig. 5 das Stromzeigerdiagramm bei phasenasymmetrischer Umrührung.
The invention will be explained in more detail with reference to the figures. Show it
  • 1 shows a first type of arrangement of stirrers for carrying out the method according to the invention,
  • 2 shows a second type of arrangement of the stirrer for carrying out the method according to the invention,
  • 3 shows a third type of arrangement of the stirrers for carrying out the method according to the invention,
  • 4 shows the current vector diagram with current-symmetrical stirring,
  • Fig. 5 shows the current vector diagram with phase-asymmetrical stirring.

Das zeigerdiagramm gemäß Figur 4 zeigt ein Dreiphasenstromsystem R, S, T, wobei die Stromasymmetrie beispielsweise dadurch hergestellt wird, daß der Stromvektor der Phase T kleiner ist als die unter sich gleich großen Stromvektoren der Phasen R und S.The vector diagram according to FIG. 4 shows a three-phase current system R, S, T, the current asymmetry being produced, for example, by the current vector of phase T being smaller than the current vectors of phases R and S, which are of equal size.

Figur 5 zeigtdas Stromzeigerdiagramm eines Dreiphasenstromsystems R, S, T, bei dem eine Phasenasymmetrie eingeführt worden ist. Zu diesem Zweck ist der Phasenwinkel zwischen den Phasen R und T gegenüber dem symmetrischen Wert von 120° um α° vergrößert und der Phasenwinkel zwischen den Phasen T und S entsprechend um α° verkleinert. a beträgt vorzugsweise mehr als 5°. Diese Phasenasymmetrie kann beispielsweist durch eine spätere Zündung des die Phase T speisenden Thyristors erreicht werden. Die phasenasymmetrische Speisung bewirkt ein asymmetrisches Umrühren, was eine bessere Gußstruktur zur Folge hat, beispielsweise bei einem asymmetrischen Umrührer 1 (siehe Figur 1), der den nicht erstarrten Bereich eines Gießstranges 3 entsprechend der Erfindung umrührt.Figure 5 shows the current vector diagram of a three-phase current system R, S, T in which phase asymmetry has been introduced. For this purpose, the phase angle between the phases R and T is increased by α ° compared to the symmetrical value of 120 ° and the phase angle between the phases T and S is reduced accordingly by α °. a is preferably more than 5 °. This phase asymmetry can be achieved, for example, by later ignition of the thyristor feeding the phase T. The phase-asymmetrical feed causes an asymmetrical stirring, which results in a better casting structure, for example in the case of an asymmetrical stirrer 1 (see FIG. 1) which stirs the non-solidified region of a casting strand 3 in accordance with the invention.

Figur 1 zeigt das Umrühren in Quer- oder Längsrichtung des Stranges bei billets, blooms oder slabs mit beispielsweise einem elektromagnetischen, mehrphasig gespeisten Umrührer 1, der dadurch für asymmetrisches Umrühren ausgebildet ist, daß die Speisung entweder zweiphasig mit einer von 90° abweichenden Verschiebung zwischen den beiden Phasen oder dreiphasig mit einer von 120° abweichenden Verschiebung zwischen den Phasen erfolgt. Der zweite Umrührer 2 wird mit demselben Phasensystem wie der erste Umrührer gespeist, jedoch entweder symmetrisch oder mit einer anderen Art von Asymmetrie als der erste Umrührer. Die Umrührer können sich eventuell gegenüberstehen und beide Können für ein Umrühren in Querrichtung oder beide für ein Umrühren in Längsrichtung ausgebildet sein. In besonderen Fällen kann der Anordnungswinkel zwischen dem Umrührer und der Gießrichtung für die beiden Umrührer 1 und 2 unterschiedliche sein. In beiden Fällen kann die Speisung der beiden Umrührer 1, 2 auch mit phasenasymmetrischer Umrührung erfolgen.Figure 1 shows the stirring in the transverse or longitudinal direction of the strand in billets, blooms or slabs with, for example, an electromagnetic, multi-phase-fed stirrer 1, which is designed for asymmetrical stirring, that the supply is either two-phase with a deviation of 90 ° between the two phases or three-phase with a shift between the phases deviating from 120 °. The second stirrer 2 is fed with the same phase system as the first stirrer, but either symmetrically or with a different type of asymmetry than the first stirrer. The stirrers can possibly face each other and both can be designed for stirring in the transverse direction or both for stirring in the longitudinal direction. In special cases, the arrangement angle between the stirrer and the pouring direction can be different for the two stirrers 1 and 2. In both cases, the two stirrers 1, 2 can also be supplied with a phase-asymmetrical stirrer.

Figur 2 zeigt zwei dreiphasig gespeiste Umrührer 1, 2, die einander gegenüberstehend an dem aus der Gießkokille 4 austretenden Gießstrang 3 angeordnet sind. Beide Umrührer haben dieselbe Umrührrichtung. Der Verlauf der Umrührung ist durch die Pfeile 5 angedeutet. Der zweite Umrührer 2 kann hierbei mit einer gegenseitigen Phasenverschiebung arbeiten, und mit einer Unsymmetrie in dem Phasenströmen von solcher Art, daß der Strom einer Phase um mindestens 10% von Strom einer anderen Phase abweicht. Man verwendet hier also einem Umrührer, bei dem gleichzeitig von zwei Möglichkeiten zur Schaffung einer Asymmetrie Gebrauch gemacht wird.FIG. 2 shows two three-phase stirrers 1, 2 which are arranged opposite one another on the casting strand 3 emerging from the casting mold 4. Both stirrers have the same direction of stirring. The course of the stirring is indicated by the arrows 5. The second stirrer 2 can work with a mutual phase shift, and with an asymmetry in the phase currents such that the current of one phase deviates by at least 10% from the current of another phase. So a stirrer is used here, in which two options for creating an asymmetry are used simultaneously.

Der zweite Umrührer 2 kann auch mit einer gegenseitigen Verschiebung der Phasenströme und einer asymmetrischen Ausbildung der Phasenwicklungen untereinander arbeiten, so daß eine Kombination aus Phasenasymmetrie und Amplitudenasymmetrie entsteht.The second stirrer 2 can also work with a mutual displacement of the phase currents and an asymmetrical configuration of the phase windings with one another, so that a combination of phase asymmetry and amplitude asymmetry arises.

Figur 3 zeigt zwei Umrührer 1 und 2, die, beispielsweise beim Gießen von billets, hintereinander längs des Gießstranges angeordnet sind; auch hier können dieselben Abweichungen zwischen dem beiden Umrührern 1 und 2 untereinander wie bei den Anordnungen nach Figur 1 und 2 vorgesehen werden. Somit kann für die beiden Umrührer 1 und 2 sowohl ein Umrühren in Querrichtung wie auch ein Umrühren in Längsrichtung vorgesehen werden, wie es in Figur 3 angedeutet ist. Man ist bestrebt, die Umrührkräfte zwischen dem Umrührern 1 und 2 so einander anzupassen, daß sich die Umrührung bis in die Kokille hinein erstreckt, d.h. die Umrührströmung soll hoch in die Kokille hineinreichen und die weißen Bänder sollen verschwinden. Es gilt, die Umrührkraft des Umrührers 1 relativ zur Umrührkraft des Umrührers 2 anzupassen, damit nicht einer der beiden Umrührer zu stark dominiert, was den Umrühreffekt verschlechtert. Bei dem Ausführungsbeispiel mit unterschiedlichen Windungszahlen der Phasenspuien ist es wichtig, daß die Amperewindungszahl für mindestens eine Phase um mindestens 10% von der Amperewindungszahl in einer anderen Phase abweicht. Man erhält somit eine magnetische Wanderwelle und ein stationäres Feld, und die Umrührer sind linear und gerade. Man erhält unter dem Umrührer eine größere Turbulenz, was mit dem verschiedenen Kombinationen erreicht werden kann, die vorstehend erläutert wurden und in den Figuren gezeigt sind.FIG. 3 shows two stirrers 1 and 2 which are arranged one behind the other along the casting strand, for example when pouring billets; here too the same deviations between the two stirrers 1 and 2 can be provided as in the arrangements according to FIGS. Thus, both stirring in the transverse direction and stirring in the longitudinal direction can be provided for the two stirrers 1 and 2, as indicated in FIG. 3. Efforts are made to adapt the stirring forces between the stirrers 1 and 2 so that the stirring extends into the mold, ie the stirring flow should extend high into the mold and the white bands should disappear. It is necessary to adjust the stirring force of the stirrer 1 relative to the stirring force of the stirrer 2 so that one of the two stirrers does not dominate too much, which worsens the stirring effect. In the embodiment with different numbers of turns of the phase coils, it is important that the ampere turns number for at least one phase deviates by at least 10% from the ampere turn number in another phase. A magnetic traveling wave and a stationary field are thus obtained, and the stirrers are linear and straight. A greater turbulence is obtained under the stirrer, which can be achieved with the various combinations which have been explained above and are shown in the figures.

Die vorstehend beschriebenen Verfahren können im Rahmen des offenbarten allgemeinen Erfindungsgedankens in vielfacher Weise variiert werden.The methods described above can be varied in many ways within the scope of the general inventive concept disclosed.

Claims (3)

1. Method for stirring the non-solidified portions of a cast strand extruding from a continuous casting machine, the strand is being formed in a mould (4) and the stirring being performed asymmetrically by an electromagnetic stirrer, characterized in that the stirring is performed by at least one first and at least one second stirrer, whereby said first stirrer (1) works asymmetrically by being supplied either by two phases having a mutual phase displacement differing from 90°, or by three phases having a mutual phase displacement differing from 120°, while the second stirrer (2) works with the same number of phases as the first stirrer but either symmetrically or with a different type of asymmetry than said first stirrer, for example with a current in one phase deviating at least 10 percent from the current in one of the other phases, or with correspondingly asymmetrically constructed phase coils.
2. Method according to claim 1, characterized in that the asymmetrical stirring is performed with a mutual phase displacement deviating at least 5° from the phase displacement of the symmetrical phase systems.
3. Method according to claim 1 or 2, characterized in' that said first and/or said second stirrer are/is supplied in a phase-asymmetric manner as well as in a current-asymmetric manner, whereby the current asymmetry is achieved by having the current in one phase deviating by at least 10 percent from the current in one of the other phases and/or by having constructed the phase coils in a correspondingly asymmetrical manner.
EP80106596A 1979-11-06 1980-10-27 Method of stirring during continuous casting Expired EP0028761B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE7909163 1979-11-06
SE7909163A SE430223B (en) 1979-11-06 1979-11-06 METHOD OF CHARACTERIZATION BY STRING

Publications (2)

Publication Number Publication Date
EP0028761A1 EP0028761A1 (en) 1981-05-20
EP0028761B1 true EP0028761B1 (en) 1985-02-20

Family

ID=20339257

Family Applications (1)

Application Number Title Priority Date Filing Date
EP80106596A Expired EP0028761B1 (en) 1979-11-06 1980-10-27 Method of stirring during continuous casting

Country Status (4)

Country Link
EP (1) EP0028761B1 (en)
JP (1) JPS5686661A (en)
DE (1) DE3070220D1 (en)
SE (1) SE430223B (en)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5890358A (en) * 1981-11-06 1983-05-30 Kobe Steel Ltd Electromagnetic induction agitating method in continuous casting of molten metal
AT378138B (en) * 1983-11-04 1985-06-25 Voest Alpine Ag STIRRING DEVICE ON A CONTINUOUS CASTING SYSTEM
AT379976B (en) * 1984-04-06 1986-03-25 Voest Alpine Ag STIRRING DEVICE ON A CONTINUOUS CASTING SYSTEM
JPS61212456A (en) * 1985-03-15 1986-09-20 Mitsubishi Heavy Ind Ltd Electromagnetic stirrer of continuous casting installation
GB2184674A (en) * 1985-12-19 1987-07-01 Ti Stirring of molten metal during continuous casting
JPS63286257A (en) * 1987-05-19 1988-11-22 Sumitomo Metal Ind Ltd Electromagnetic stirring method
SE465306B (en) * 1987-11-02 1991-08-26 Asea Ab SEAT AND DEVICE FOR MOVING STRING
US20090242165A1 (en) * 2008-03-25 2009-10-01 Beitelman Leonid S Modulated electromagnetic stirring of metals at advanced stage of solidification
AT518460B1 (en) * 2016-03-21 2021-07-15 Primetals Technologies Austria GmbH Stirring coil partially encompassing a metal strand
IT202100012824A1 (en) * 2021-05-18 2022-11-18 Ergolines Lab S R L METHOD AND DEVICE FOR SHAKING INGOT MOLD FOR ALUMINUM OR ALLOYS AND INGOT MOLD AND CASTING MACHINE INCLUDING SUCH A DEVICE

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2803503A1 (en) * 1977-02-03 1978-08-10 Asea Ab TWO- OR MULTI-PHASE CONVERTER
DE2810876A1 (en) * 1977-03-14 1978-09-21 Arbed METALS AND APPARATUS FOR STIRRING MELTED METALS DURING CONTINUOUS SLAB CASTING
EP0008376A1 (en) * 1978-07-28 1980-03-05 Concast Holding Ag Method for continuously casting metal in a mould and influence of an electro-magnetic field
EP0009803A1 (en) * 1978-10-06 1980-04-16 Concast Holding Ag Method for continuously casting steel

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5252895Y2 (en) * 1973-04-18 1977-12-01

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2803503A1 (en) * 1977-02-03 1978-08-10 Asea Ab TWO- OR MULTI-PHASE CONVERTER
DE2810876A1 (en) * 1977-03-14 1978-09-21 Arbed METALS AND APPARATUS FOR STIRRING MELTED METALS DURING CONTINUOUS SLAB CASTING
EP0008376A1 (en) * 1978-07-28 1980-03-05 Concast Holding Ag Method for continuously casting metal in a mould and influence of an electro-magnetic field
EP0009803A1 (en) * 1978-10-06 1980-04-16 Concast Holding Ag Method for continuously casting steel

Also Published As

Publication number Publication date
SE7909163L (en) 1981-05-07
SE430223B (en) 1983-10-31
EP0028761A1 (en) 1981-05-20
DE3070220D1 (en) 1985-03-28
JPH0131979B2 (en) 1989-06-28
JPS5686661A (en) 1981-07-14

Similar Documents

Publication Publication Date Title
DE2756112C3 (en) Method and device for horizontal continuous casting
DE2731238A1 (en) METHOD AND DEVICE FOR CONTINUOUS PASTING, IN PARTICULAR STEEL, UNDER THE EFFECT OF A MAGNETIC WALKING FIELD
CH619385A5 (en)
EP0028761B1 (en) Method of stirring during continuous casting
EP0040383A1 (en) Method and apparatus for stirring the molten metal in a continuous-casting strand
EP1815925B1 (en) Method and apparatus for the continuous casting of double-T-bleam blanks
DE2720391A1 (en) ARRANGEMENT IN CONTINUOUS CASTING
DE3122155C2 (en)
DE2626824A1 (en) METHOD OF WELD PLATE
EP1427553B1 (en) Method and device for producing a metal strip in a strip casting machine with rolls
EP0008376B2 (en) Method for continuously casting metal in a mould and influence of an electro-magnetic field
DE2911842A1 (en) PROCEDURE FOR STIRRING IN CONTINUOUS CASTING
EP0009803B1 (en) Method for continuously casting steel
DE69818658T2 (en) METHOD FOR COATING BY MEANS OF ELECTRIC SLAG METHOD
DE2945018A1 (en) METHOD FOR STIRRING THE UNDERGROUND AREAS OF A CASTING STRAND
DE2810876A1 (en) METALS AND APPARATUS FOR STIRRING MELTED METALS DURING CONTINUOUS SLAB CASTING
DE2853049A1 (en) Device for continuous casting
DE2827240A1 (en) Metal agitator in continuous casting plant - applies magnetic field in solidification phase superposed to direct current
EP0013441A1 (en) Apparatus and method for electromagnetical stirring in a continuous steel casting plant
DE2731239A1 (en) PROCESS FOR CONTINUOUS PASTING, IN PARTICULAR STEEL, UNDER THE EFFECT OF A MAGNETIC WALKING FIELD
EP0019118A1 (en) Installation for stirring metal melts in continuous casting plants
DE3030377A1 (en) METHOD AND IMPLEMENTING ARRANGEMENT FOR STIRRING THE SQUEEZE OF A BIT STRING EXITING FROM A CONTINUOUS CASTING MACHINE.
DE3039491A1 (en) METHOD FOR STIRRING THE NON-SETTING AREAS IN A CASTING LEAF EXITING FROM A CONTINUOUS CASTING MACHINE
WO1988005353A1 (en) Process and device for magnetically stirring metal bars
EP0815987A1 (en) Electromagnetic stirrer and brake for a continuous casting apparatus

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): DE FR GB

17P Request for examination filed

Effective date: 19810926

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Designated state(s): DE FR GB

REF Corresponds to:

Ref document number: 3070220

Country of ref document: DE

Date of ref document: 19850328

PLBI Opposition filed

Free format text: ORIGINAL CODE: 0009260

26 Opposition filed

Opponent name: AEG ELOTHERM GMBH

Effective date: 19851028

PLBN Opposition rejected

Free format text: ORIGINAL CODE: 0009273

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: OPPOSITION REJECTED

27O Opposition rejected

Effective date: 19870221

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19911007

Year of fee payment: 12

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19911015

Year of fee payment: 12

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19911129

Year of fee payment: 12

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19921027

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19921027

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Effective date: 19930630

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19930701

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST