EP3173166B1 - Method and device for setting the width of a continuously cast metal strand - Google Patents

Description

The invention relates to a method for adjusting the width of a continuously cast by a mold metal strand in a continuous casting plant according to the preamble of claim 1, and a corresponding device according to the preamble of claim 17.

In the continuous casting of metals in a continuous casting the width B of a metal strand can be adjusted with adjustable narrow sides of the mold. In the area of secondary cooling, ie below or downstream of the mold, the metal strand is guided by means of rollers arranged parallel to the broad side of the strand. This ensures the thickness d of the metal strand. The narrow sides of the metal strand have in the area below the mold usually a short support, consisting of only a few pairs of rollers following this support begins the spreading of the metal strand .. Due to the ferrostatic pressure, the metal strand spreads and bulges thus in the area below the mold in the width direction, ie transverse to the casting direction. The spread of the metal strand can reach several percent of the nominal width.

In the articles " Numerical Simulation of Slab Broadening in Continuous Casting of Steel ", Intech, Chapter 23, 2012 and " Effect of Casting Speed on Slab Broadening in Continuous Casting, "Steel Research Int. 82, No. 11, 2011 by Jian-Xun Fu and Wenig-Sing Hwang Numerical simulations are performed which simulate the continuous casting process in relation to the unwanted spread of the metal strand.

The Japanese patent application JP S 61232049 discloses a method for adjusting the width of a continuous casting mold. Specifically, the target width of the mold, the changes in the mold width at the beginning and at the end of a continuous casting process and the casting speed is input as a parameter into a computing unit, which calculates suitable manipulated variables for actuators for setting the mold width from these input parameters. This allows high-speed casting, in which the variations in the mold width are reduced, even if otherwise the mold width varies greatly during continuous casting.

EP 2 762 251 B1 discloses a method for casting a metal strand, in which a width correction for the metal strand is calculated as a function of a determined volumetric flow difference from the measured actual value and the measured nominal value of the volume flow of a liquid metal in a regulator, taking into account the thickness of the metal strand to be cast and the casting speed , Subsequently, the calculated width correction is output as a manipulated variable to an actuator for adjusting at least one narrow side of the continuous casting mold, so that there is a change in the width B of the metal strand to be cast. A disadvantage of the method according to
EP 2 762 251 B1 is that for this purpose the knowledge of the volume flow of the liquid metal is necessary, which makes a corresponding flow sensor or the like required at an outlet opening of the continuous casting mold.

EP 0 947 265 A2 discloses a generic method having the features of the preamble of claim 1, and a generic device having the features of the preamble of claim 17.

Out US 5 205 345 A For example, there is known a method for adjusting the width of a continuous metal slab cast in a continuous casting machine. Here, temperature, speed and ferrostatic pressure are measured periodically, a computer calculates from these values a correction factor for the mold width and controls Kokillenstellglieder accordingly.

Accordingly, the invention has for its object to optimize the continuous casting of a metal strand to the effect that by a suitable setting of Narrow sides of the continuous casting mold as accurate as possible width tolerance for the metal strand, especially at the end of the continuous casting is guaranteed.

The above object is achieved by a method having the features of claim 1, and by a device having the features of claim 17. Advantageous developments of the invention are defined in the dependent claims.

A method according to the present invention is for adjusting the width of a continuously cast by a mold metal strand in a continuous casting plant. In this method, a width correction for the metal strand is calculated and output as a manipulated variable for adjusting at least one narrow side of the mold. Based on a Breitungsmodells is calculated by a computing device, the width of the metal strand or a slab formed therefrom at the end of the continuous casting taking into account at least one calculation parameter and compared with a predetermined setpoint, wherein at least one narrow side of the mold depending on the calculated width for the end of the continuous casting of the metal strand is set. Preferably, both narrow sides of the mold are set here. Here, the adjustment of the at least one narrow side of the mold can be made regulated, for which purpose a corresponding control circuit is set up in the computing device. A width of the metal strand or a slab formed therefrom is determined at at least one measuring point, using a measuring device suitable for this purpose. The measuring point is located at a predetermined and preferably small distance from the outlet opening of the mold, namely within the strand guide of a continuous casting in its upper part, preferably at a distance of
4 - 12 meters to the exit opening of the mold. More preferably, this distance can also be 5-8 meters.

In connection with the present invention is to be understood that the width of a continuously cast metal strand, or the width of slabs formed therefrom, determined by a bulge of the narrow side and the spread of the metal strand within the strand guide, as well as by the thermal Shrinkage of the metal strand from the pouring mirror until it reaches room temperature. The cause of the change in width of the continuously cast metal strand lies in the ferrostatic load of the liquid melt in the interior of the metal strand. Here, the tendency of the increase of a width due to the ferrostatic load is substantially greater than the counteracting shrinkage, which results from the density change of the metal strand as a result of its temperature decrease or -kühlkühlung.

In general, the spreading of a continuously cast metal strand or slab formed therefrom, i. the resulting width in the fully solidified state compared to the width at which the metal strand leaves the exit opening of the mold, depending on the type of steel used. For most steels, the spread is greater than the shrinkage, except for very hard steels (e.g., C100) where this is reversed. Furthermore, the spread is strongly dependent on the geometry of the metal strand. This manifests itself in the fact that thick metal strands have a much stronger preparation than thin metal strands.

The invention is based on the essential finding that it is possible with the calculation based on the Breitungsmodells to determine the actual width of the metal strand or a slab formed therefrom, which adjusts itself at the end of the continuous casting, exactly. The calculation in the Breitungsmodell takes place in dependence on at least one calculation parameter, which may be a process parameter of the casting process and / or a material-specific size. By comparing the thus calculated width with a target value for the width, which is predetermined for the metal strand or a slab formed therefrom at the end of the continuous casting process, then a control signal is generated by the computing device, with which an actuator is controlled, which with the at least one narrow side of the mold is in operative connection. As a result, then said setting of the mold narrow side.

It should be noted at this point that "end of the continuous casting plant" is also to be understood in terms of time. In other words, this is a time when the metal strand or one formed from it Slab is completely cooled, in which case no further change in the width of the cast product occurs. In this regard, it is irrelevant whether the metal strand is already separated into a slab. In any case, with the Breitungsmodell according to the present invention, a resulting width of the metal strand or a slab formed therefrom is calculated, namely for a time when the metal strand or the slab have cooled so far that their width assumes a constant value.

As explained, according to the present invention, on the basis of the Breitungsmodells the width of the metal strand or a slab formed therefrom can be calculated exactly at the end of the continuous casting. A measurement of the width of the metal strand or a slab by a measuring device is not necessary here. The possibly variable boundary conditions during the continuous casting process, e.g. As a result of using another type of steel, changing the geometry of the metal strand or changing the cooling conditions or the like, can be detected solely by the at least one calculation parameter, depending on the Breitungsmodell the width of the metal strand or a slab is calculated.

In an advantageous embodiment of the invention, the spreading of the metal strand or a slab formed therefrom is calculated in the Breitungsmodell as a function of at least one calculation parameter, this calculation parameter at least the physical properties of the material of the metal strand, the temperature of the metal in the mold, the casting speed of the metal strand, the overheating and / or the geometry of the metal strand comprises. Conveniently, this one calculation parameter can be determined during the continuous casting process in real time ("online"), whereby rapid reactions to possible process changes are ensured. The employment of the mold narrow side is thus based on the Breitungsmodells, for which, inter alia, the temperature measurements in the narrow sides of the mold and the heat flows discharged via the Kokillenkühlwasser can be considered for all Kokillenseiten. Furthermore, the water supply to the mold narrow sides can be predetermined for the secondary cooling.

In an advantageous embodiment of the invention, the measuring point at which the width of the metal strand or a slab formed therefrom is determined using a measuring device suitable for this purpose, additionally also be arranged at the end of the continuous casting or outside thereof.

By measuring the width at the measuring point, it is thus possible to determine the width of the metal strand or a slab formed therefrom, i. the change in the width of the metal strand or a slab at this measuring point in comparison to the width of the metal strand has at the outlet opening of the mold determined. The resulting measured value, which is recorded at the at least one measuring point, is then passed to the computing device, and then taken into account for the calculation with the Breitungsmodell. In other words, the measured value which is recorded by the measuring device at the measuring point for the width of the metal strand or a slab formed therefrom then serves as a further calculation parameter for the calculation in the spreading model.

In an advantageous embodiment of the invention, the Breitungsmodell comprises a thermodynamic model and a mathematical-physical model, these models are coupled together. Specifically, by means of the thermodynamic model, temperatures and strand shell thicknesses of the metal strand are determined at each position of the metal strand in the continuous casting plant. By means of the mathematical - physical model, a creep of the metal strand is determined. Preferably, the values calculated by the thermodynamic model for the subsequent calculation by the mathematical-physical model are taken into account here. Thus, by coupling the thermodynamic model to the mathematical-physical model, it is possible to calculate the spread for the metal strand or slab formed therefrom, based on this and, as explained, taking into account a predetermined target value for the width at least to set a narrow side of the mold.

It should be noted that by setting a narrow side of the mold is understood that either a distance of this narrow side on their Whole length is changed with respect to the opposite narrow side of the mold, ie increased or decreased, wherein an angle of the surface of this narrow side remains unchanged with respect to the vertical. Additionally or alternatively, a surface of this at least one narrow side of the mold in the course of said setting can also be changed with respect to a vertical, whereby the angle of the surface of this narrow side is changed with respect to the vertical. In other words, the narrow side is "tilted" with respect to the vertical. This is also referred to as "taping" in the field of continuous casting. These two adjustment options can also be superimposed in the context of the present invention. This means that in a change in width of the mold, so if at least one narrow side of the mold is changed in their distance with respect to the opposite narrow side, optionally also the taper, ie the angle of this narrow side with respect to the vertical at the outlet opening of the mold is changed to a constant concern of the molten metal to the mold wall and thus to ensure good cooling and to prevent detachment of the melt from the mold wall.

By the present invention, it is possible, the always occurring in the continuous casting of a metal strand in the course of continuous casting propagation by calculating the width, which is expected at the end of the continuous casting, and a corresponding adjustment of the width of the mold, ie by changing the distance the narrow sides of the mold, suitable to compensate, so that in particular at the end of the continuous casting, if there is already cooled, the metal strand, to ensure an accurate measure of the width of the cooled metal strand. In addition to improved accuracy for the resulting width of the metal strand at the end of the continuous casting results from the invention, the further advantage that the setting of at least one narrow side of the mold during the production process z. B. to changed process parameters and / or other materials from which the metal strand is poured, can be adjusted. This then leads to considerable material savings and to a shortened production time.

For the calculation of the width of the metal strand at the end of the continuous casting a computing device is provided, which is provided with the Breitungsmodell, wherein the width, which has been calculated for the metal strand at the end of the continuous casting, is then compared by means of the computing device with a predetermined target value. Based on this and depending on the calculated for the end of the continuous casting width of the metal strand is then set as explained above, the at least one narrow side of the mold. It is advantageous in this case if the computing device is operated in such a way that the setting of the at least one narrow side of the mold is regulated as a function of the calculated width for the end of the continuous casting machine, ie. H. by providing a corresponding control loop in the computing device. Such a regulation of the employment of the at least one narrow side can react very quickly to changes during the production process during the continuous casting of a metal strand, for example to changed temperatures of the molten metal and / or to changed casting speeds.

In an advantageous development of the invention, state changes of the entire metal strand in a thermodynamic model are calculated in a mathematical simulation model, including a heat conduction equation. On the basis of this, it is then possible to draw conclusions about the temperature of the metal strand along the continuous casting plant, and thus in the casting direction of the metal strand.

It should again be pointed out here that according to the present invention with the Breitungsmodell, preferably formed by a coupling of a thermodynamic model with a mathematical-physical model, and the information about the casting process, the course of the propagation of the metal strand within the strand guide and in particular for the end of a continuous casting plant can be calculated with great accuracy. Thus, it is possible to react quickly to process changes such as the casting temperature or casting speed or the secondary cooling and immediately initiate a width adjustment of the mold. This is ensured by calculating the differential changes for the occurring process variations in the Breitungs model. If such process changes occur, you can now very quickly the change of the expected width to the width adjustment as "pre-control" will be conducted. As already explained above, to control the width adjustment of the at least one narrow side, a measurement takes place at the predetermined measuring point below the mold. By comparison between this measurement and the Breitungsberechnung can be concluded that the expected width of the metal strand at the end of the continuous casting.

In an advantageous development of the invention, the adjustment of the at least one narrow side of the mold can also be effected as a function of the temperature of the molten metal within the mold. For this purpose, the temperature of the metal within the mold is detected by the temperature of at least one side wall of the mold, preferably characterized in that drawn by the heat flows through the Kokillenkühlwasser on at least one Kokillenseite a conclusion on the temperature of the liquid metal within the mold.

In an advantageous embodiment of the invention, the width of the metal strand in individual cross-sectional segments along the casting direction can be calculated on the basis of the Breitungsmodells. Here are the strains that are transverse to the casting direction for the individual cross-sectional segments of the metal strand, d. H. set in a width of the metal strand, added up, and then calculated on the basis of which or the width of the metal strand or the width of the end of the continuous casting or determined.

In an advantageous embodiment of the invention, the Breitungsmodell, or its mathematical-physical model, take into account a creep. In this regard, it may be pointed out that for this purpose the so-called simplified Garofalo creep approach is suitable or proven. In any case, for the Breitungsmodell is generally a creep for the secondary creep in the solidified part of the metal strand suitable.

In an advantageous embodiment of the invention, material-specific parameters of the metal strand and / or the process temperature of the metal strand are when using the Breitungsmodells and Kriechensatzes for secondary creep during continuous casting. This is preferably done "on-line" and thus in real-time during the continuous casting process to allow for rapid adjustments to eventual process changes.

In an advantageous embodiment of the invention, a shrinkage of the metal strand along the casting direction can be taken into account in the Breitungsmodell. In the same way as in the determination of the spreading of the metal strand, its shrinkage can preferably be calculated in individual cross-sectional segments along the casting direction, which leads to a high degree of accuracy of calculation.

In an advantageous embodiment of the invention, a setting and / or pitch for the at least one narrow side of the mold can be determined on the basis of the Breitungsmodells. This is particularly advantageous for a planned change in the casting speed with which the metal strand is cast. In the same way, the employment of the at least one narrow side of the mold, and possibly also the employment speed selected for this purpose, can be calculated as a function of an overheating of the liquid metal, a secondary cooling and / or an analysis change. Here, the temperature of the melt or the liquid metal within the mold or in the upstream Thundish be permanently determined or calculated by means of a ladle and distributor model. By temporary temperature measurements of the melt in the pan or in a distributor, the ladle and distributor model is adapted.

In order to achieve the above object, according to the present invention, there is also provided an apparatus for adjusting the width of a continuous metal casting by a mold in a continuous casting machine, comprising a computing device in which a latitudinal model is set up and based on which, depending on at least one calculation parameter, the width the metal strand or a slab formed therefrom is calculated at the end of the continuous casting plant and compared with a predetermined desired value, wherein the computing device subsequently generates a control signal. The device further comprises an actuator which is in operative connection with at least one narrow side of the mold and which can be actuated by the actuating signal to at least one Set narrow side of the mold, and at least one measuring device with which a width of the metal strand or a slab formed therefrom at a measuring point, which is arranged at a predetermined distance from the outlet opening of the mold, can be measured. This measuring device is disposed within the strand guide of the continuous casting in the upper part and preferably at a short distance from Kokillenunterkante. This leads to a further improved accuracy with respect to the determination of the spread of the metal strand or a slab formed therefrom.

In an advantageous development of the device according to the invention, at least one measuring device can also be arranged at the end of the continuous casting plant or outside thereof. For this case, two measuring devices are provided, of which one as described within the strand guide, and the other at the end of the continuous casting or are arranged outside thereof.

Another advantage of such a measuring device arises in the case when along the continuous casting unforeseen disturbances such. with the cooling water supply or similar should occur - by the measuring device, in particular in an arrangement at the end of the continuous casting or outside of it, then it is possible in such a fault case to measure the actual width of the metal strand or a slab formed therefrom at the end of the continuous casting process, then at least as explained adjust a narrow side in the mold accordingly. In this way, the disturbances can then be compensated, at least temporarily, for example in order to obtain e.g. finish a production cycle in an orderly manner.

With regard to the adjustment of the at least one narrow side of the mold, which is possible with the device according to the invention may be made to avoid repetition of the above explanations regarding the adjustment options for at least one narrow side of the inventive method.

Embodiments of the invention are described in detail with reference to a schematically simplified drawing.

Fig. 1

ein Diagramm für den Verlauf der Temperatur in einem stranggegossenen Metallstrang in Abhängigkeit des Abstands vom Gießspiegel, errechnet auf Basis der vorliegenden Erfindung und zu deren Durchführung,

Fig. 2

eine schematisch vereinfachte Darstellung einer zur Durchführung des erfindungsgemäßen Verfahrens eingerichteten Stranggießanlage,

Fig. 3

eine prinzipiell vereinfachte Darstellung einer erfindungsgemäßen Vorrichtung, die bei der Stranggießanlage von Fig. 2 zur Durchführung der Erfindung vorgesehen ist,

Fig. 4

eine prinzipiell vereinfachte Darstellung von Schmalseiten einer Kokille von Fig. 2, zur Veranschaulichung der Veränderung eines Abstands der Stranggießanlage 20 zwischen diesen Schmalseiten,

Fig. 5

eine prinzipiell vereinfachte Darstellung einer Schmalseite einer Kokille der Stranggießanlage 20 von Fig. 2, zur Veranschaulichung der Veränderung einer Neigung dieser Kokille,

Fig. 6

vereinfachte Querschnittsansichten eines stranggegossenen Metallstrangs, zur Veranschaulichung der Breitung des Metallstrangs,

Fig. 7

ein Diagramm zur Veranschaulichung eines Breitenanteils an der Position einer Messstelle, an welcher die Breitung eines Metallstrangs erfindungsgemäß gemessen wird,

Fig. 8

ein Diagramm zur Veranschaulichung eines Verlaufs der Breite eines Metallstrangs innerhalb der Strangführung einer Stranggießanlage von Fig. 2,

Fig. 9

ein Diagramm zur Veranschaulichung einer Berechnung der Breitung eines Metallstrangs auf Grundlage des Breitungsmodells nach der vorliegenden Erfindung, für eine Variation der Gießgeschwindigkeit,

Fig. 10

ein Diagramm zur Veranschaulichung einer Berechnung der Breitung eines Metallstrangs auf Grundlage des Breitungsmodells nach der vorliegenden Erfindung, für eine Variation der Überhitzung der Metallschmelze, und

Fig. 11

ein Flussdiagramm zur Veranschaulichung des erfindungsgemäßen Verfahrens.

Show it:

Fig. 1

a diagram for the course of the temperature in a continuously cast metal strand as a function of the distance from the casting level, calculated on the basis of the present invention and for its implementation,

Fig. 2

a schematically simplified representation of an established for carrying out the method continuous casting,

Fig. 3

a simplified schematic representation of a device according to the invention, in the continuous casting of Fig. 2 is provided for carrying out the invention,

Fig. 4

a simplified representation of narrow sides of a mold of Fig. 2 to illustrate the change in a distance of the continuous casting 20 between these narrow sides,

Fig. 5

a simplified representation of a narrow side of a mold of the continuous casting 20 of Fig. 2 to illustrate the change in an inclination of this mold,

Fig. 6

simplified cross-sectional views of a continuously cast metal strand, illustrating the spreading of the metal strand,

Fig. 7

a diagram illustrating a width proportion at the position of a measuring point, at which the propagation of a metal strand is measured according to the invention,

Fig. 8

a diagram illustrating a profile of the width of a metal strand within the strand guide of a continuous casting of Fig. 2 .

Fig. 9

4 is a diagram illustrating a calculation of the expansion of a metal strand based on the spreading model according to the present invention, for a variation of the casting speed;

Fig. 10

a diagram illustrating a calculation of the expansion of a metal strand based on the Breitungsmodells according to the present invention, for a variation of the overheating of the molten metal, and

Fig. 11

a flowchart illustrating the method according to the invention.

During the solidification of a continuously cast metal strand 10 in a continuous casting plant 20 (cf. Fig. 2 ) decreases the average temperature of the metal strand Leaving the mold steadily. As a result of a reduction in the specific volume of the metal as the temperature decreases, the metal strand shrinks. At the same time, the width of the continuously cast metal strand increases during the casting process within the strand guide of a continuous casting plant, namely because of the ferrostatic load within the metal strand and as a result of creep of the material or creep process within the metal strand. In this case, depending on the type of steel used, the spread may be greater than the shrinkage by a few factors. The propagation effect is also dependent on the material or the liquid metal to be cast and its solidification structure, the ferrostatic load, as well as process parameters, such as casting speed, superheating secondary cooling and the strand thickness

The present invention aims to calculate the resulting expansion of a continuously cast metal strand, possibly also taking into account its shrinkage, in particular for the end of a continuous casting plant, in order to adjust at least one narrow side of a mold of the continuous casting plant accordingly. This is particularly important in the case when the width of the metal strand or of slabs formed therefrom after cooling must be within a narrow tolerance specified by the customer.

The temperature distribution for a continuously cast metal strand depends, inter alia, on the enthalpy curve, which can be calculated, for example, on the basis of Gibbs energies. This temperature distribution is in the diagram of Fig. 1 represented, namely over the strand length and as a function of the distance from the casting mirror. In each case, the temperatures in the strand center are shown on the surface and in the core. In addition, the average temperature is shown. The solidus and liquidus lines indicate where solidification of the metal strand occurs. The calculation of the temperature distribution, as in the diagram of Fig. 1 shown with the help of Gibbs energy can with a Procedures are carried out which DE 10 2011 082 158 A1 is known. In this case, the temperature distribution which prevails inside a continuously cast metal strand is calculated by means of a temperature calculation model based on a dynamic temperature control, for example the DSC ( Dynamic Solidification Control) . In this case, the total enthalpy can be calculated from the sum of the free molar enthalpy (Gibbs energies) of all present in the material of the metal strand existing phases and / or phase components.

Fig. 2 shows in a simplified schematic representation of a continuous casting plant 20 for continuous casting of a metal strand 10, with this continuous casting 20, a method according to the invention can be performed. For this purpose, the continuous casting plant 20 is equipped with a computer device 120 or computing device, wherein this computing device 120 is equipped with a temperature calculation model designed as a metallurgical process model, which has or is based on a temperature control. With the temperature calculation model, for example the DSC ( Dynamic Solidification Control) already mentioned above, the temperature distribution prevailing inside a metal strand cast from liquid metal can be calculated.

The aforementioned metallurgical process model is part of a spreading model BM that is set up in the computing device 120. Preferably, the Breitungsmodell BM includes both a thermodynamic model TM for determining the temperatures and the strand shell thicknesses of the metal strand 10 and a mathematical-physical model MPM for determining the creep of the metal strand 10, wherein the models TM and MPM are coupled together ( Fig. 3 ).

The metal strand 10 has a liquid or swampy portion 14 before its solidification in the core. In the embodiment according to Fig. 2 is a Sump tip 16, which defines the solidification length of the metal strand 10, formed in a, considered in the casting direction, end portion of a secondary cooling 22. To the metal strand 10, a plurality of roller segments 24 or generally segments are arranged for its deformation and support, which are provided with support rollers or strand guide rollers 26 and formed hydraulically adjustable. The strand guide rollers 26 are adjustable and partially formed rotationally driven.

The continuous casting plant 20 has a distribution vessel or casting distributor 28 and a continuous casting mold 130 connected thereto. From a ladle 32 molten steel runs in the Gießverteiler 28 and from there into the mold 130. Below the mold 130, a plurality of strand guide rollers 26 are provided for supporting an upper and lower side of the metal strand 10, wherein the metal strand in this area initially has a very thin strand shell. The metal strand 10 then passes through a circular arc-shaped area, and then runs out in a straightening zone and can e.g. be separated in slabs in a downstream scissors or flame cutting machine.

In the Fig. 2 is symbolized by the reference numeral "21" greatly simplified one end of the continuous casting 20, which means the invention, inter alia, a resulting width of a metal strand 10 is calculated at this end 21, as a basis for a subsequent adjustment of at least one narrow side of the mold 130th Das At the end 21 of the continuous casting plant 20, the metal strand 10 is cooled and essentially solidified, wherein the metal strand 10 may also already be singulated into individual slabs.

According to the invention is in the continuous casting 20 of Fig. 2 at least one measuring device 100 is provided. The measuring device 100 may be arranged at a measuring point 102, namely below an outlet opening 132 of the mold 130 and at a comparatively small distance therefrom, by the width of the Metal strand 10 at this point to measure. Additionally or alternatively, a measuring device 100 may also be arranged at a measuring point 104, namely at the end 21 of the continuous casting plant 20 or outside thereof, in order to measure the width of the thoroughly solidified and cooled metal strand 10 or the width of a slab formed therefrom. With regard to the arrangement of a measuring device 100 may be noted that the associated measuring point is located at a predetermined distance from the outlet opening 132 of the mold 130. The measuring device 100 is connected by a signal line 122 to the above-mentioned computing device 120, so that the measured at the measuring point 102, 104 width of the metal strand 10 is transmitted to the computing device 120. With regard to the signal line 122, it should be pointed out that this can either be a physical signal line or a suitable radio link or the like.

Fig. 3 shows in principle and greatly simplified a device 1 according to the present invention, with the explained above at the measuring point 102, for example in a continuous casting 20 of Fig. 2 , the width B of a metal strand 10 can be measured. In addition, the width of the metal strand 10 or a slab formed therefrom can also be determined at the measuring point 104, namely at the end 21 of the continuous casting plant 20. For this purpose, the device 1 comprises a measuring device 100, which at the measuring point 102 or 104 (see. Fig. 2 ), and the computing device 120 to which the measuring device 100 is connected via the signal line 122. Accordingly, with the computing device 120, a change in the width of the metal strand 10 at the measuring point 102, or a change in the width of the metal strand 10 or a slab formed therefrom at the measuring point 104, compared to the width of the metal strand 10 at the outlet opening 132 of the mold 130, are determined.

For the purposes of the present invention, the computational device 120 has the breadth model BM based on which the width of the Metal strand 10 at the end 21 of the continuous casting 20 (see. Fig. 2 ) is calculated and compared with a predetermined setpoint value, wherein the computing device 120 subsequently generates an actuating signal thereto. This control signal is transmitted via a further signal line 122 to a standing with at least one narrow side 134 of the mold 130 in operative connection actuator 136, whereby then the narrow side 134 of the mold 130 is suitably employed.

Fig. 4 shows in principle simplified, the two narrow sides 134 of the mold 130, which are spaced apart by a distance A. By means of a control by an actuator 136, the distance A between these narrow sides 134 can be suitably changed, thereby affecting the width of the metal strand 10 at the outlet opening 132 of the mold 130. Optionally, it is also possible to change the inclination of a narrow side 134 with respect to the vertical V, as it is simplified in principle in the representation of Fig. 5 is shown. In this case, for example, an upper edge of the narrow side 134 can be displaced by a distance N with respect to the lower edge of the narrow side 134, so that a surface of the narrow side 134 encloses an angle with the vertical V.

Fig. 6 2 shows simplified cross-sectional views of a continuously cast metal strand 10, and illustrates the increase of the metal strand 10 in its width B as a result of propagation. Here are the areas I in the middle of Fig. 6 the width change of the metal strand 10 as a result of Wreitung or a creep of the material. The areas II in the lower part of Fig. 6 illustrate a change in width of the metal strand 10 due to spreading and bulging.

The invention now works as follows:
In the continuous casting of a metal strand 10 is calculated by the computing device 120 based on the Breitungsmodells BM, the width of the metal strand 10 or a slab formed therefrom for the end 21 of the continuous casting 20 and compared with a predetermined setpoint, then at least one narrow side 134 of the mold 130 through an associated actuator 136 is suitably set, namely as a function of the calculated for the end 21 of the continuous casting width B of the metal strand 10th

For the calculation of the width of the metal strand 10 at the end 21 of the continuous caster 20 calculation parameters are taken into account, the at least the physical properties of the material of the metal strand, the temperature of the metal in the mold 130, the casting rate of the metal strand 10, overheating and the geometry of the metal strand 10th include. In Fig. 3 the reference character "140" is to be understood that from the Breitungsmodell BM in the computing device 120, a change in the process parameters of the continuous casting process, such as overheating, casting speed and water cooling, can be considered, and then in the control of the actuator 136 for hiring the at least one narrow side 134 flows.

As explained above, a measuring device 100 may be provided at the measuring point 102 and at the measuring point 104 in order there to determine the width of the metal strand 10 (at the measuring point 102) or the width of the metal strand 10 or a slab formed therefrom (at the measuring point 104). With the width measurement by the measuring device 100 can thus be determined a change in the width of the metal strand 10 or a slab at the respective measuring point 102, 104 compared to the width of the metal strand 10 at the outlet opening 132 of the mold 130, and then with a predetermined setpoint for the width of the metal strand 10 or a slab formed therefrom. In this case, the measured value generated by the measuring device 100 then forms for the width of the metal strand 10 or a slab formed therefrom another calculation parameter for the calculation in the Breitungsmodell BM.

Regarding the in Fig. 4 may be noted that such a width adjustment of the mold 130 can also take place in consideration of a change in the liquid steel temperature or superheating, the casting speed and the secondary cooling, which then the width deviation of the metal strand 10 as a result is minimized by its spread.

Regarding the in Fig. 5 may be noted that thereby a bulge II of the metal strand 10 can be minimized, possibly in conjunction with a suitable adaptation of the water cooling in the secondary cooling 22, and possibly in conjunction with a Adaptation of a cooling of the narrow sides 134 of the mold 130.

Fig. 7 shows a diagram for defining the width proportion of the metal strand 10 at the position of the measuring point 102, for example, for two different casting speeds (with v1> v2). It can be seen that the increase in width decreases steadily with increasing distance from the casting mirror or from the outlet opening 132 of the mold 130 and, for example, does not increase any further at a distance of 15 meters from the casting mirror or proceeds from there to constant.

Fig. 8 shows a diagram illustrating the course of the propagation of the metal strand 10 within the strand guide in the continuous casting 20 of Fig. 2 , where the graph G1 represents the spread and the graph G2 represents the shrinkage of the metal strand 10.

In Fig. 9 and Fig. 10 In each case diagrams are shown with which the calculation of the expansion of the metal strand 10 based on the Breitungsmodells according to the present invention is illustrated, this being for a variation of the casting speed ( Fig. 9 , with v1> v2) or for a variation of overheating ( Fig. 10 , with overheating H1> overheating H2).

Fig. 11 FIG. 12 is a flow chart illustrating the above-described aspects of the present invention again. FIG. The parameters a, b, c and d shown herein, which govern the mathematical-physical model MPM, may be the parameters of the Garofalo approach and its regression coefficients.

LIST OF REFERENCE NUMBERS

10

metal rod

20

continuous casting plant

21

End of the slab

100

measuring device

102

measuring point

104

measuring point

120

computing device

130

mold

132

outlet opening

134

narrow side

136

actuator

BM

Breitungsmodell

B

Calculated width

H1

overheating

H2

overheating

TM

thermodynamic model

MPM

mathematical-physical model

Claims (18)

1. Method for setting the width of a metal strip (10), which is continuously cast by a mould (130), in a continuous casting plant (20), in which a width correction for the metal strip (10) is calculated and output as a setting variable for adjustment of at least one narrow side of the mould (130), wherein the width (B) of the metal strip (10) or of a slab, which is formed therefrom, at the end (21) of the continuous casting plant (20) is calculated on the basis of width model (BM) by a computing device (120) in dependence on at least one computation parameter and is compared with a predetermined target value, wherein at least one narrow side (134) of the mould (130), preferably both narrow sides (134) of the mould (130), is or are set in dependent on the width (B), which is calculated for the end (21) of the continuous casting plant (20), of the metal strip (10) or the slab, wherein a width (B) of the metal strip (10) is measured at at least one measuring point (102; 104) at a predetermined spacing from the outlet opening (132) of the mould (130) and the corresponding measurement value of this width (B) is passed to the computing device (120) so as to be taken into consideration in the width model (BM), characterised in that the at least one measuring point (102) is present within the strip guide of the continuous casting plant (20) in the upper part thereof, preferably at a distance of 4 to 12 metres from an outlet opening (132) of the mould (130).
2. Method according to claim 1, characterised in that the setting of the at least one narrow side (134) of the mould (130) is set, preferably regulated, in dependence on the width (B), which is calculated for the end (21) of the continuous casting plant (20), of the metal strip (10) by the computing device (120).
3. Method according to claim 1 or 2, characterised in that the width model (BM) comprises a thermodynamic model (TM) and a mathematical/physical model (MPM), wherein temperatures and strip skin thicknesses of the metal strip (10) at every position of the metal strip (10) in the continuous casting plant (20) are determined by means of the thermodynamic model (TM), and wherein creep of the metal strip (10) is determined by means of the mathematical/physical model (MPM), wherein the thermodynamic model (TM) and the mathematical/physical model (MPM) are coupled with one another so that the width (B) of the metal strip (10) or of a slab, which is formed therefrom, at the end (21) of the continuous casting plant (20) is determined by these models.
4. Method according to claim 3, characterised in that thermodynamic changes in state of the entire metal strip (10) are calculated in the thermodynamic model (TM) in a mathematical simulation model, which includes a heat conductivity equation and on the basis thereof a conclusion about the temperature of the metal strip (10) along the continuous casting plant (20) is possible.
5. Method according to claim 3 or 4, characterised in that the mathematical/physical model (MPM) takes into consideration a creep formula, particularly a formula for secondary creep.
6. Method according to claim 5, characterised in that material-specific parameters of the metal strip (10) and/or the process temperature of the metal strip (10) during the continuous casting is or are taken into consideration for the creep formula.
7. Method according to any one of claims 3 to 6, characterised in that the values, which are determined by means of the thermodynamic model (TM), for the calculation are taken into consideration by the mathematical/physical model (MPM).
8. Method according to any one of claims 1 to 7, characterised in that the at least one computation parameter taken into consideration in the width model (BM) comprises at least the physical characteristics of the material of the metal strip (10), the temperature of the metal in the mould (130), the casting speed of the metal strip (10), the overheating and/or the geometry of the metal strip (10).
9. Method according to claim 8, characterised in that the at least one computation parameter is determined during the continuous casting process and thus in real time ('online').
10. Method according to any one of claims 1 to 9, characterised in that the width of the metal strip (10) is calculated on the basis of the width model (BM) in individual cross-sectional segments of the metal strip (10) along its casting direction.
11. Method according to any one of claims 12 to 10, characterised in that shrinkage of the metal strip (10) along the casting direction is taken into consideration in the width model (BM).
12. Method according to any one of claims 1 to 11, characterised in that an additional measuring point (104) is present within the strip guide of the continuous casting plant (20) at the end of the continuous casting plant (20) or outside thereof.
13. Method according to any one of claims 1 to 12, characterised in that the temperature of the metal within the mould (130) is detected by the temperature of at least one side wall of the mould (130), preferably in that the temperature of the metal within the mould (130) is detected by the removed flows of heat across the mould cooling water at at least one mould side.
14. Method according to any one of claims 1 to 13, characterised in that an adjustment and/or a rate of adjustment for the at least one mould narrow side (134) is determined on the basis of the width model (BM).
15. Method according to any one of claims 1 to 14, characterised in that an adjustment and/or a rate of adjustment for the at least one mould narrow side (134) is determined in dependence on an overheating (H1; H2) of the liquid metal, from which the metal strip (10) is cast, a secondary cooling and/or an analysis change.
16. Method according to any one of claims 1 to 15, characterised in that the casting temperature is derived from a temperature measuring point in the ladle or in the tundish or is calculated by a ladle or tundish model.
17. Device (1) for setting the width (B) of a metal strip (10), which is continuously cast by a mould (130), in a continuous casting plant (20), comprising:

    a computing device (120) in which a width model (BM) is provided and on the basis of which the width (B) of the metal strip (10) or of a slab, which is formed therefrom, at the end (20) of the continuous casting plant (20) is calculated in dependence on at least one computation parameter and is compared with a predetermined target value, wherein the computing device (120) subsequently thereto generates a setting signal,

    a setting element (136), which is disposed in operative connection with at least one narrow side (134) of the mould (130) and which is controllable by the setting signal so as to set the at least one narrow side (134) of the mould (130) and

    at least one measuring device (100) by which a width (B) of the metal strip (10) or of a slab formed therefrom is measurable at a measuring point (102; 104) arranged at predetermined spacing from the outlet opening (132) of the mould (130),

    characterised In that

    the measuring device (100) is arranged at a measuring point (102) within the strip guide of the continuous casting plant (20) at the upper part thereof, preferably at a distance of 4 to 12 metres from an outlet opening (132) of the mould (130).
18. Device according to claim 17, characterised in that the measuring device (100) is additionally arranged at a measuring point (104) at the end of the continuous casting plant (20) or outside thereof.

Images