EP3515634A1 - Controlling the narrow-side conicity of a continuous casting mould: method and device - Google Patents

Abstract

Controlling the narrow-side taper of a continuous casting mould. The invention relates to a method and a device for controlling the narrow-side conicity of a continuous casting mould on the basis of measuring the forces applied to the narrow sides with the aid of actuators. To achieve a narrow-side conicity that is as optimum as possible, with which the temperature-induced shrinkage of the metal strand is compensated as precisely as possible, and thus contact with the metal strand is established over as large an area as possible, by placing the narrow side plates against the cast metal strand, the invention proposes a closed-loop control circuit of which the system deviation is based on measuring the forces occurring at the actuators during the continuous casting. By means of suitable parameterization of the controlled variable, the control specification and filters of the closed-loop control circuit, a very rapid and reliable control behaviour can be obtained. Double-acting hydraulic cylinders are proposed as actuators for a device according to the invention.

Description

description

The invention relates to a method for controlling the narrow-side conicity of a continuous casting mold based on the measurement of the forces applied to the narrow sides.

Furthermore, the invention relates to a continuous casting mold whose narrow side plates are made by means of actuators located at different distances from the pouring side in accordance with the method according to the invention.

Continuous casting molds are used in the casting of metal slabs, in particular when casting steel slabs. In this case, a continuous casting mold, in which the method according to the invention is used, consists of four individual, mutually displaceably arranged metal plates, the so-called mold plates, which are preferably made of a copper alloy and have a substantially parallelepiped shape.

With regard to the casting direction of the continuous casting mold, all four mold plates have approximately the same extent, which is consequently designated as mold height H. In addition, two of the mold plates each have the same dimension in the width direction. The chill plates of the larger widthwise pair are also referred to as wide side plates, those having the smaller widthwise dimension than narrow side plates.

The four mold plates of a continuous casting mold are, with respect to the casting direction, arranged at the same height, wherein the two wide side plate plates and the two narrow side plates each face each other. This results in a mold open on both sides, the openings of which are designated as inflow-side or outlet-side end and which-with respect to a sectional plane normal to the casting direction-have a rectangular cross-section. The arrangement of the mold plates to one another is such that each of the two broad side plates during the casting process with its inner face the two narrow side panels, and vice versa, each narrow side plate contacted with two mutually ge ^¬ genüberliegenden outer surfaces of the two broad-side plates. In this case, the distance between the outlet-side ends of the narrow side plates is referred to as a casting width, since this distance defines the dimension of the cast metal strand as it leaves the mold.

This arrangement enables on the one hand, that the narrow sides ^¬ plates can also be moved during the casting operation parallel to the inner surfaces of the broad side plates ^¬. On the other hand, by applying the wide side plates mechanically to the narrow side plates, a clamping force can be exerted on the narrow side plates.

The - relative to the casting direction - enclosed by the mold plates space is referred to as the interior of the mold, accordingly the internal space supplied ^¬ facing surfaces of the mold plates are referred to as the inner surfaces are analogous to the opposed inner surfaces of each ^¬ weiligen cuboidal mold plates Surfaces also referred to as outer surfaces of the mold plates.

So-called backup plates are usually attached to the outer surfaces of the mold plates, which on the one hand ensure sufficient mechanical stability of the mold plates and on the other hand contain a cooling device which dissipates the heat of the molten metal released during continuous casting from the mold plates. Such devices, e.g. Milled recesses on the outer surfaces of the mold plates, which together with the backup plates form cooling channels through which water flows, are well known from the prior art.

The displaceable arrangement of the mold plates relative to one another takes place by means of corresponding actuators, which make it possible to to move spatially zelne mold plates and thereby vary the maßgebli ^¬ che for the dimension of the metal slab produced cross-sectional area of the mold. Such actuators may be, for example, motor-driven spindles or hydrauli- raulische actuators, which are also known from the prior Tech ^¬ technology.

During the casting process, a molten metal is introduced into the interior of the mold at the inflow end, wherein the metal melt begins to solidify on the mold plates in the contact area with the mold plates due to the heat release and forms a so-called strand shell in this region, the thickness of which during the passage of the corresponding strand section continuously increased by the mold. The thus partially solidified metal strand is drawn out by corre ^¬ sponding extraction devices, such as driven drive rollers in the mold subsequent roller table, at the outlet end of the mold from this, this process is supported by mechanical oscillatory movements of the mold itself.

The surface of the liquid metal melt in the interior of the continuous casting mold is also referred to as a casting mirror, the ^¬ accordingly, the so-called. Gießspiegelhöhe h is defined as the distance of the casting mirror from the outlet end of the mold.

Furthermore, casting powder is applied to the molten metal at its inflow end, which is melted on the surface of the still molten metal melt by the heat given off and subsequently forms a sliding film between the forming strand shell and the inner surfaces of the mold plates, the reduces the mechanical friction between the strand shell and the inner sides of the mold plates.

Despite the formation of a strand shell, most of the portion of the metal strand inside the mold remains in the liquid phase. Therefore, a corresponding ferrostatic pressure acts on the strand shell, which must be compensated by a corresponding back pressure of the mold plates, since the strand shell itself can not build up sufficient back pressure. For this reason, a corresponding pressure force is applied during the casting especially on the narrow side plates by means of their actuators, since the clamping action that exert the wide side plates on the narrow side plates is usually not sufficient.

An actuator arranged on a narrow side plate has a point of application, at which a force is transmitted to the narrow side plate and wherein the narrow side plate is moved at this position by a spatial displacement of the point of application by the actuator. This attack ^¬ point can be configured articulated when beispielswe- the inclination of the narrow side plate se during the displacement by the actuator changes. In this sense, the point of application is assigned a position displaceable in space, which is referred to as an actuator position in the further. Furthermore, an actuator comprises a sensor with which the current value of the actuator position is detected, which is also referred to as the actual position of the actuator and which is transmitted to a control unit. In a position control of the actuator is this of the

Control unit specified a certain position value, which is referred to below as the desired position of the actuator. In this case, the actual position of the actuator is compared with its setpoint position and the actuator is controlled by the control unit in such a way that the actual position and setpoint position coincide. This activation takes place by acting on the actuator with a corresponding mechanical force, which is transmitted to the narrow side plate via the point of application of the actuator and as a result of which the position of the narrow side plate is changed at this point. The application of the actuator with a mechanical force is also caused by the control unit and can be done for example by modifiers ^¬ alteration of the hydraulic pressure when the actuator is in the form of a hydraulic cylinder. During the casting process all actuators of the continuous casting mold individual default positions are given and thus controlled the inward forces of the individual actuators so that the cooperation of all actuators during the casting process - with the exception of the process of a position adjustment of the narrow side plates - the outward forces Metal melt are ^{ausgegli ¬ Chen} exactly, otherwise the narrow side plates would move. There is thus a balance of forces Zvi ^¬ rule the outwardly, caused by ferrostatic pressure of the molten metal forces and the inwardly directed forces of the actuators. Since metal alloys in their solidification and subsequent

Cooling down experience a reduction of their spatial volume, shrinks the cast metal strand as it passes through the mold accordingly. It is also known that in order to achieve a qualitatively high-quality result of the cast metal strand as it passes through the

Mold should have as large as possible mechanical contact with the inner surfaces of the mold plates. However, the strand shell stands out due to thermal shrinkage of the mold inner surface, it reduces at the loading taken place the outflow of heat from the metal strand to any significant extent, resulting in inconsistent quality of the strand surface result and until the on ^¬ tear in extreme cases, the strand shell can lead. A measure to achieve a large area as possible and gleichmäßi ^¬ ges concern of light passing through the mold the metal strand, is to specify a minor Nei ^¬ movement between the respective opposite mold plates so that the cross section of the mold from the pouring end to the exit-side End tapered according to the shrinkage of the metal strand.

The inclination of the opposite broad side plates is usually characterized by a trapezoidal shape of the narrow side plates. Since the narrow side plates contact the two wide side plates along their height extension, there is a different distance between the respective upper, inflow side ends of the two wide side plates than between the lower, outlet side ends of the wide side plates. The quotient of the difference between the upper distances f and the lower distances d between the wide side plates and the mold height H corresponding to K _b = (f - d) / h is also referred to as broad side conicity.

Similarly, the taper of the narrow side plates - hereinafter also referred to as narrow-side conicity K _s - usually as a difference of the distance e of Eingießseiti ^¬ gene ends of the narrow side plates to each other and the distance b of the outlet-side ends of the narrow side plates to each other, which is identical to the casting width b, according to

K _s = (e - b) / b defined. However, there are other definitions of

Narrow side conicity possible, it being essential that they depend on the inclination of at least one of the narrow side plates with respect to the casting direction. Thus, it is conceivable to relate a definition for the narrow-side conicity only on a single narrow side plate, for example ^¬ example

K _s, i = (ei - bi) / i with le {l, 2}, wherein the index 1, the first and second Schmalseitenplat ^¬ te and ei to the pouring and bi the exit-side normal distance of the narrow side plate 1 to the geometric With ^¬ tenlinie designate the continuous casting mold. In the case of one of the ^¬ like, only on a narrow side plate related definition of the narrow side conicity of the continuous casting mold are subsequently assigned ^¬ two values for the narrow-side conicity. Since the Breitseitenkonus is determined solely by the geometric shape of the narrow side plates, it can be taken during the casting operation no influence. Therefore, in order to improve the contact of Kokilleninnenseite with the strand shell during the casting process, are known from the prior Tech ^¬ technology solutions that influence the shape of the narrow ^¬ side plates of a mold. The formation of the strand shell in the passage of the metal ^¬ strand through the continuous casting mold depends on unterschiedli ^¬ Chen factors, such as the casting speed, the composition of the molten metal itself, the properties of the casting powder or from the cooling capacity of the cooling device of the mold from which the heat transfer from the cast Metal strand to the mold and thus also affect the mechanical contact of the metal ^¬ strand with the mold.

From JP 2010 253548 A a construction for strand is ingot molds are known which suggests to bend the narrow side plates mechanically during casting depending on the Gießgeschwindig ^¬ ness, the carbon content of the molten metal or the trespassing of the metal strand at the mold heat stream, the heat flow from temperature values of the cooling water of the cooling device of the mold is calculated. The aim of this invention is to keep by the dar ^¬ te bending the narrow side plates both the solidification course of the strand shell and the frictional forces that occur on the inner surfaces of the mold plates as constant as possible under changing casting conditions and thus the formation of longitudinal cracks in the cast metal strand to avoid. In this case, a complex bending mechanism according to FIG. 15 and FIG. 18 is used to apply the required bending forces.

JP H03 210953 A proposes a continuous molding, each having their narrow side plates, a vertically extending in the horizontal direction to the casting direction groove 15 whose ^¬ because at this point under the action of force, a kink forms according to Fig.l. The regulation of this force is effected in dependence on measured by a Ther ^¬ moelementes temperature values in the vicinity of the outlet-side end of the narrow side plates. The grooves of the narrow side plates represent a mechanical weak point.

JP H02 247 059 A proposes to turn the narrow side plates together with the backup plates mounted thereon in dependence of the measured heat flow or the casting speed to ver ^¬. The required bending forces are very high, the inner surfaces of the narrow side plates take a curved along the casting direction course. A disadvantage of all the above publications is that high mechanical forces or correspondingly complex trades are necessary for bending the narrow side plates.

Moreover, in the cited publications a hypothetical solidification course of the strand shell is assumed, for which a physical model formation is necessary, which in turn depends on various influencing factors and is therefore subject to corresponding uncertainties, since no direct measurement of the actual contact surface between strand shell and the Inner surfaces of the mold plate takes place.

A further disadvantage of the above-mentioned publications is that a control based on a measured temperature value or a measured heat flow has a corresponding inherent inertia and therefore can not react fast enough to rapidly changing production conditions.

To circumvent adverse mechanical loads on the narrow side plates, the subject invention therefore proposes that instead of bending the narrow side plates this during the casting in their spatial position to changed ^¬ countries by being guided along the inside of the wide side plates. This happens because the clamping force exerted on the narrow side plates by the wide side plates is reduced, then the narrow side plates are correspondingly adjusted by means of corresponding position-controlled actuators and finally the contact pressure of the wide side plates is restored to the original value. Such an adjustment process is controlled and such that, despite the outward-acting forces of the liquid molten metal, there is no sudden tearing of the strand shell.

In particular, the narrow side conicity can thus be adapted to the shrinkage of the metal strand resulting from the formation of the strand shell, so that the contact surface of the narrow side plates with the strand shell is as large as possible. In this case, no forces are applied to the bending of the Schmalsei ^¬ tenplatten itself and the frictional forces between the strand shell and the inner surfaces of the mold plates are not unnecessarily increased. In an optimal narrow-side conicity in this sense, the employment of the narrow sides of the mold corresponds exactly to the shrinkage of the strand, which is caused by the growth of the strand shell. Typical values of the narrow ^¬ seitenkonizität be between 0.9% and 1.3% of the casting width according to the above definition.

Too much conicity of the narrow side plates, which causes a pinch of the strand through the mold, causes not only an increased wear of the mold surface, an increase in the friction between the mold and strand. Under certain circumstances, as the metal strand passes through the continuous casting mold in the edge region where the narrow side ^plates and the broad side plates meet, bulging of the strand shell also occurs inwardly, which in turn leads to longitudinal defects in the metal strand.

By too low a Schmalseitenkonizität other hand ent ^¬ is a gap between the strand shell and the Schmalsei- tenplatten of the mold, resulting in a reduced Strangscha- lenwachstum due to a low heat dissipation can lead over the mold walls. A thus evoked from ^¬ dents of the strand in the mold can also cause only increased breakdown probability to quality problems in the edge region of the metal strand.

The optimal Schmalseitenkonizität depends on various production ^¬ tion parameters, such as the shrinkage characteristics of the cast molten metal or from the actual heat dissipation, inter alia, by the properties of the

Casting powder and the casting speed is determined from. It therefore makes sense that Schmalseitenkonizität dynamically anzupas ^¬ sen to Vorherr ^¬ dominant casting conditions during casting.

The setting of the Schmalseitenkonizität a Stranggussko ^¬ kille during the casting operation in response to a production parameter is known from the prior art. In order to ensure a rapid narrow side adjustment, the clamping of the wide side plates, for example, permanently by a preset spring clamp, the clamping action of a corresponding Entklemmvorrichtung only briefly during the adjustment of the narrow side conicity is opened by actuators of the Entklemmvorrichtung cancel the clamping force of the spring clamp.

For example, DE 10 2014 227 013 A1 describes the adjustment of the narrow-side conicity of a continuous casting mold as a function of a temperature distribution in the mold plates and the mechanical contact of the strand shell derived therefrom against the inner surfaces of the mold plates. The temperature distribution is preferably determined by means of optical fiber sensors ^¬, being deduced the mechanical contact or on the formation of air gaps from the ratio of measured values between the centrally located and near the edge temperature sensors.

On the one hand, the temperature-based regulation of the narrow side cone described in DE 10 2014 227 013 A1 is relatively slow - so, for example, the lifting of the strand shell can only be detected with a corresponding time delay. On the other hand, this control method is based only on the heat flow passing from the cast metal strand to the mold plates and the associated temperature changes, but without taking frictional forces into account, and thus represents only an indirect method for determining the appropriate conicity, which is associated with corresponding inaccuracies ,

JP S56 119646 A describes a continuous casting mold, the plates of which are moved under pressure during casting. In this case, the narrow side plates are each movably connected at their pouring end to a base plate, which can be moved and fixed in the horizontal direction. Near the pouring outlet end of the narrow side plates is the point of application of a pressure-controlled actuator, e.g. a hydraulic cylinder, which presses the narrow side plates against the cast metal strand, with a small gap distance of 0.1 - 0.2mm in the casting direction between the narrow side plates and the wide side plates to allow their relative movement.

Although this invention allows because of the pressure-controlled control of the lower actuators rapid reaction to changing production conditions with respect to the contact of the narrow side plates with the metal strand, but with the movements of the actuators simultaneously adjusting the narrow side cone itself, so that the contact behavior of the narrow side plates on the one hand and the optimal value of

On the other hand, narrow side cone can not be adjusted independently of each other. In addition, a uniform casting width can not be maintained because tilting of the narrow side plates at its lower end occurs during a control operation and, moreover, it can not be ensured that the narrow side cone is identical on both sides, which can lead to inconsistent growth of the strand shell.

Furthermore, it is customary from known production parameters such as the composition of the molten metal, the casting width, the casting speed current or calculated from measured temperature values ge ^¬ heat flow to calculate a value for the Schmalseitenkonizität and manually to specify this value by means of the automation system of the Subject Author ^¬ fenden caster. This approach ^¬ be resting either on experience or model assumption concerning the strand shell growth and therefore with ent speaking ^¬ many uncertainties, also a precise overall reproducibility due to manual intervention is not given.

It is therefore an object of the present invention to overcome the disadvantages of the aforementioned methods and to disclose a method for controlling the narrow-side conicity of a continuous casting mold which, depending on the current process conditions, enables the optimum value of the narrow-side ^{conicity to be} as fast and reproducible as possible the largest possible contact area between the strand shell and mold inside allowed without unnecessarily increasing the Rei ^¬ training forces.

The object is achieved by the features of claim 1. An ^¬ . Advantageous embodiments of the invention are the subject of the dependent claims.

The following is based on a continuous casting mold, the narrow side plates can be moved over each at least two mechanical actuators along the inner sides of the broad side plates and whereby an inwardly directed force is exerted on the strand shell of the cast metal strand to the outward-acting ferrostatic pressure not yet counteract solidified molten metal, since the clamping action of the narrow side plates by the broad side plates and the intrinsic cohesion force of the strand shell itself are not sufficient to prevent tearing of the strand. These forces transmitted from the narrow side plates to the strand shell are referred to below as narrow side forces. It is believed that the casting direction of the Stranggussko ^¬ kille 1 is oriented substantially in the direction of gravity; Therefore, the ferrostatic pressure of the introduced into the mold 1 molten metal in the casting direction increases according to the behavior of a liquid linearly with the distance to the surface of the molten metal, which is located in the casting direction at a distance corresponding to the Gießspiegelho ^¬ hehe over the outlet-side ends of the mold plates ,

The pressure increase within the molten metal melt naturally continues below the outlet end of the continuous casting mold. A deviation from the linear arrival Stieg behavior due to the temperature dependence of you ^¬ te of the molten metal can be disregarded in this analysis to a good approximation, as the temperature of the introduced into the mold melt is only slightly above the solidification temperature.

The ferro-static pressure of the molten metal caused by au ^¬ SEN directed forces that have to be compensated by correspondingly inward ge ^¬ taught opposing forces to an On ^¬ tear the strand shell to prevent.

When passing the molten metal through the Stranggussko ^¬ kille occurs due to the cooling effect to form a strand shell along the inner surfaces of the mold plates. The strand shell has inherent strength, which depends on its thickness locally and which partially compensates for the outward-acting ferro- static pressure of the molten metal. The further part of the ferrostatic pressure must be compensated inside the continuous casting mold by appropriate counterpressure of the mold plates, in order to avoid a rupture of the strand shell.

While automatically set by the fixed set clamping the wide ^¬ side plates of the corresponding back pressure, the back pressure along the narrow side plates be actively controlled, since there is no complete clamping action of the narrow side plates through the wide side plates. The spatial position and orientation of the Schmalsei ^¬ tenplatten is therefore carried out by an active position control of the narrow side plates moving mechanical actuators.

After exiting the metal strip from the Stranggussko ^¬ kille the strand shell is already so far grown that the intrinsic strength of the strand shell border FER rostatische pressure can be easily compensated by spatially permanently set or position-controlled strand guide rollers, wherein the strand guiding rollers the surface of the solid metal strand directly support. Experiments show that the narrow side forces with small ^¬ dender casting speed, always remove (less than 0.6 meters per minute) due to the formation of the strand shell and the resulting strand shrinkage until the metal strip at very low casting speeds (0 to 0.2 meters per minute) to Contact with the Kokillenschmalseiten almost completely loses and the narrow side forces tend to zero.

Furthermore, experiments show that an adjustment of the narrow-side conicity has a direct influence on the required narrow side forces.

Thus, there is an empirical relationship between the narrow side forces and the casting speed. Furthermore, there is a relationship between the narrow side forces and the narrow side conicity.

The present invention for adjustment of the narrow side plates against the forming of a possible op ^¬ timalen value of Schmalseitenkonizität, wherein said appointing

Strand shell exactly equal to the shrinkage of the metal strand ^¬ , based on the use of this relationship and suggests A method for setting a Schmalseitenkonizität K _s of a continuous molding for the production of a metal strand with the help of at least one control loop in front, whereby the strand ^¬ casting ingot mold a first and vice summarizes a second narrow side plate at each of which at least two position-controlled Ak ^¬ motors for positioning the respective narrow side plate at different distances to the pouring end of the

Continuous casting mold are arranged and wherein in the effective direction of each actuator during operation of the continuous casting mold corresponding forces occur, characterized in that during a cycle through the at least one control loop - a reference pressure P _ref as a reference variable and

- an average surface pressure P _med between the Schmalsei ^¬ tenplatten and the metal strand as a control variable, wherein the average surface pressure P _med from occurring in the effective direction of the actuators is determined forces, are used and that

- A controller in response to a control deviation P _dlf = P _ref - P _med as input the narrow-side conicity K _{s determined} as a control variable of the control loop and that

- The position of the first and / or the second narrow side plate is adjusted according to the narrow-side conicity K _s via a controlled system by means of the actuators. According to the invention, each of the two narrow side plates of the continuous casting mold can be positioned by its own, independent control loop, which controls only the actuators of the respective narrow side plate. In this case, the adjusting ^¬ size of the respective control loop is dependent on the inclination of the JE weiligen narrow side plate with respect to the casting direction, and the method of the invention thus comprises two inde ^¬ dependent values for the Schmalseitenkonizität - each have a value for the first and a value for the second Schmalsei ^¬ tenplatte - the continuous casting mold. Alternatively, however, a common control loop for both narrow side plates are used, which accordingly controls the actuators of both narrow side plates. In this case, the inventive method comprises a ge ^¬ common value for the Schmalseitenkonizität the strand ^¬ casting ingot mold, the definition with respect to the casting direction is dependent on the inclinations of the two narrow side panels alike.

Furthermore, the controller of the control loop may also comprise filtering, either condition the input signal for a given rule ^¬ circular control law or further process the detected signal from the control law, before it is fed to the controlled system.

The inventive method allows rapid Rea ^¬ crave to changing process conditions, since the detection of the narrow side forces that are influenced by the process conditions, as opposed to methods based on temperature or heat flow measurements, virtually in real time. The inventive method is also based on a empi ^¬ step relation between the narrow side forces on the one hand, and the momentary casting parameters such as casting speed, the behavior of mold powder or together ^¬ mensetzung of the molten metal on the other hand, this em- pirical connection by the action of the controller model ^¬ liert. Therefore, the method according to the invention does not require any physical modeling of the effects of the various influencing variables, but rather is based on the measurement of the immediate reaction of the casting parameters in the form of the narrow side forces, so that the effects of all relevant casting parameters are taken into account equally and equally fast. Thus, a withdrawal of the strand shell from the inner sides of the narrow side plates, for example, caused by excessive cooling and concomitant strand shrinkage can be detected immediately because the applied for a certain control position narrow side forces reduce ent ^¬ speaking. Similarly, an increase in the narrow side forces, which would cause a pinch of the strand and is caused, for example, by a too low cooling capacity of the metal strand, are directly balanced. In this way, optimal Kraftvertei ^¬ ment of the actuators and, accordingly, the largest possible contact surface between the strand shell and the inner surfaces of the narrow side plates is achieved without the Rei ^¬ bungskräfte between the strand shell and the inner surfaces of the continuous casting mold are unnecessarily increased.

Furthermore, the inventive method ensures gu ^¬ te reproducibility, since the adjustment of the Schmalseitenkonizität to the instantaneous conditions of production does not require any operator intervention but depends only on the voreingestell ^¬ th parameters of the controller or of at most carried out in the controller filtering.

In a further preferred refinement of the method according to the invention, the reference pressure P _{ref is} a function of the density of the liquid molten metal pi _iq , a pouring mirror ^height h and a dimensionless correction factor S.

The density pi _{iq of} the molten metal is to be understood as meaning the material density of the molten metal whose physical density

Unit is given in kg / m ³ , for example. The reference pressure P _ref depends on the density of the molten metal pi _iq and on the molten metal level h, which is defined as the distance of the casting mirror from the outlet end of the mold, and also contains a further dimensionless correction factor S, which can be specified.

The reference pressure P _ref is a parameter of the control method and, if necessary, can also be used during the casting process. For example, by an operator or by another control system, be readjusted to change the characteristics of the control loop. As a result, it is possible to take into account a change in the casting-mirror height h during the casting process or to respond flexibly to changes in the casting parameters, such as a change in the composition of the molten metal, of the casting powder or in the heat removal of the mold. An adaptation of the reference pressure, for example, are based on empirical values from the acquired He ^¬ casting parameters, making a determined once under certain casting conditions, advantageous way in which the continuous molding can be reproduction ^¬ ed.

The reference pressure P _ref can be determined, for example, by the expression P _ref = S * P _fer / 2 = S * p _liq * g * h / 2, where g is the value of the gravitational acceleration and P _{fer is} the ferrostatic pressure of the molten metal inside the cast Metal strand designate at the outlet end of the continuous casting mold. As a result of the physical laws of the ferrostatic pressure P _fer linearly increases in the casting direction, of about the Gießspiegelhö ^¬ height h averaged ferrostatic pressure, referred to as the mean FLAE ^¬ chenpressung P _med, half the value of the local ferrostatic pressure P _fer corresponds to the foot of the Liquid column of height h at the outlet end of the mold. A temperature-related change in the density pi _iq can be disregarded if the pouring temperature of the molten metal is only a few degrees above its solidification temperature.

The correction factor S preferably has a value range of 0.7-3 and takes into account the self-supporting ability of the forming strand shell, which mitigates the effect of the outward ferrostatic pressure P _{fer of} the molten metal, further the effect of frictional forces between the narrow side plates and the wide side plates corresponding to those of counteract the forces applied to the actuators of the narrow side plates and reduce them accordingly and the friction between the strand shell and the Schmalseitenplat ^¬ th, which has an outwardly directed force component in the width direction of the continuous casting and due to the narrow side ^conicity depends on the value of the narrow side conicity. In addition, the correction factor S on the selected casting speed v depend, because in particular the friction between the strand shell and the narrow side plates is a sliding friction and therefore the friction forces occurring depends on the relative speed between the ^¬ divided surfaces.

For values of S <1, the self-sustainability of the strand shell outweighs the frictional forces between the narrow side and the wide side plates and between the narrow side plates and the strand shell and used for example in ei ^¬ nem mode for use, on the Breitseitenplat ^¬ th only with very low clamping action be used against the Schmalsei- tenplatten, which is also referred to as soft-clamping.

In contrast, mean values of S> 1, must be that the friction Strengthens ^¬ te between the narrow side and the wide side plates and narrow side plates and between the strand shell predominate and compensated for accordingly by the actuators of the narrow side plates.

The dependence of the correction factor S from the speed v Gießgeschwin- can be ^¬ be written, for example, by a table model based on empirical values. Also, S may depend on other factors, such as the composition of the molten metal or the casting powder, which can also be mapped in an empirically recorded table model.

The above definition of the reference pressure P _ref offers the advantage of an easy-to-use empirical Mo ^¬ model- ling the reference variable of the control loops invention ses represents that depends in addition to the correction factor S only by already known process parameters, and which may therefore be extended by means of the correction factor S for example, with respect to new together ^¬ mensetzungen of the molten metal or the mold powder in a ^¬ ways and requires no elaborate physical simulations.

In a further preferred embodiment of the method according to the invention, the mean surface pressure P _{med is expressed} by the expression

Nl N2

P _med = [E (F _{1; 1} ) + (F ₂ , _j )] / (2 * h * d)

determined, where

F i, i the force detected by a measuring element of the control loop, occurring at the actuator i of the first narrow side plate,

F ₂ , _{j is} the force detected by a measuring element of the control loop, occurring at the actuator j of the second narrow side plate,

 Nl the number of actuators of the first narrow side plate,

 N2 is the number of actuators of the second narrow side plate,

 h the Gießspiegelhöhe and

 d designate the casting thickness.

The average surface pressure P _med represents an average over the forces of all the actuators of the two narrow side plates, which exert the actuators on the narrow side plates.

These forces can advantageously be measured very simply and quickly by methods known from the prior art, as a result of which the control loop can be adjusted very quickly to control deviations. can react. In particular, a lot faster from ^¬ control of deviations is possible, than would be the case with unaffected by temperature or heat flow-based regulations as force measurements can be performed within a split second.

In a preferred embodiment of the method according to the invention, the setting of a common Schmalsei ^¬ tenkonizität for both narrow side plates is symmetrical with respect to the casting direction of the continuous casting mold under specification of the spatial position of the center line of the metal strand in Be ^¬ train on the wide side plates and a value for the casting width b. For each of the two narrow side plates, the inclination of the narrow side plate with respect to the casting direction and an absolute spatial position can be predetermined by means of the actuators acting in the width direction of the continuous casting mold whose spatial arrangement is known, which - based on the entire continuous casting mold - represents four mechanical degrees of freedom.

If the position of the center line of the produced metal strand with respect to the wide side plates is kept constant by appropriate positioning of the narrow side plates so that the metal strand does not drift in the width direction relative to the wide side plates, this reduces the number of degrees of freedom by one. An additional specification of a distance between the narrow side plates to each other - for example, the distance of the pouring outlet ends of the narrow side plates, which is by definition identical to the casting width b of the continuous casting mold - reduces the degrees of freedom by another. Further, if also the inclinations of the two narrow side plates are set symmetrically with respect to the casting direction, this represents a limitation to only a single mechanical degree of freedom of the narrow side plates, which is represented by a correspondingly unique value for the narrow side conicity. This ^{results in} a clear relationship between a value for the Schmalseitenkonizität K _s and the position values of a ^¬ individual actuators of both the first and the second narrow side plates, so that _s corresponding position values of the actuators of both narrow-side plates can be uniquely determined from a preset value for the narrow ^¬ seitenkonizität K. Thus, in this case, the two narrow side plates of the continuous casting mold are no longer independent vonei ^¬ nander, but positioned by a single control loop.

In this context, it is also possible to change the casting width b during the execution of the control method or to leave it constant and to specify a starting value for the Sollpo ^¬ positions of the individual actuators when first run through the control loop. A constant value of the casting width b is during the casting process, in particular towards ^¬ clearly the quality of the cast metal strand desirable because elaborate measures to below SET ^¬ development of the width of the metal strip, such as flame cutting or lateral compression can be omitted.

In a preferred embodiment of the method according to the invention, the controller of the at least one control loop comprises a control law with a abge ^¬ initiated by the control deviation input variable and an output variable and ^¬ to the actual ^¬ positions {Χι in each cycle of the at least one control loop, ι, X2 ,} the actuators at least one of the first or the second narrow side plate detected and derived therefrom an actual value I _s for the narrow-side conicity K _s and this by specifying appropriate target positions {Yi, ±, Y ₂ , ₃ } for the actuators at least one of the first or The second narrow side plate in a the effect of the narrow ^¬ lateral conicity on the average surface pressure imaging controlled system of at least one control loop only adjusted if a difference from the determined actual value exists.

The detected actual positions of the actuators of the narrow side plates thus represent input variables and the determined target positions for the actuators correspond to output variables of the actuator. at least one control loop, which are each newly determined in each pass through the at least one control loop.

Parts therefore the actual value of I _s of Schmalseitenkonizität and in the current cycle of the at least one control loop he ^¬ mittelte manipulated variable which _s is identical to the target value of the narrow ^¬ seitenkonizität K, match, then an adjustment of the Schmalseitenkonizität over the control path omitted. This is particularly advantageous if during the adjustment of the narrow side plates usually also an operation of the clamping mechanism for the wide side plates must be made, which can be omitted in this case. Such a control cycle can therefore be correspondingly fast, ie within a few milliseconds or less.

In a further preferred embodiment of the method according to the invention is a control rule of the controller

Pdif 'being a variable derived from a control deviation P _{dlf of} the control loop,

a determined by the control rule of the control variable size for determining the manipulated variable K _s and

 are a proportionality factor with a value range from 0.001 to 0.1, preferably from 0.005 to 0.02.

The control law here describes the behavior of the rule ^¬ circle depending on the deviation and is used to determine the output; while understanding the importance and role of Re ^¬ are gelvorschrift in the context of a classic rule ^¬ circle and thus the skilled person adequately be ^¬ known. By this control law control deviations can be programmed in a very simple way: when the Proportionali ^¬ tätsfaktor k has a value less than 1, so this causes the system deviation attenuated flows into the Cor ^¬ rection of the output of the control law, currency ^¬ rend at values greater 1 the deviation is amplified.

In a further preferred embodiment of the method erfindungsge- MAESSEN a first filtering of the Regelabwei ^¬ chung _dlf P of the control loop by means of a time-related Fil ^¬ ters Φ _τ takes place in accordance with

Pdif '= Φτ (Pdi _f ; {Pdif} _τ ), where

P _{d i _f} x is an amount of over a period τ back ^¬ reaching, stored values of the control deviation P _dlf from previous cycles of the

Control circuit and

P _d i _f 'a from the time-related filter Φ _Τ determined

Input variable for the control rule of the control loop ^¬ are.

This filtering can, for example, consist in a simple averaging of all the values of the control deviation used. However, it is also conceivable to weight more recent values more strongly than values that were older. Thus = 5-10 seconds into consideration the historical values of the control deviation with τ game as preferred in ^¬ a period of time.

By this temporal filtering high frequency fluctuations of the control deviation of the measurement signal, the example embodiment ^¬ caused by erroneous measurements are kön- NEN, suppressed. This prevents an erroneous adjustment of the narrow side plates due to false readings or due to high-frequency interference and contributes to the stabilization ^¬ tion of the continuous casting process.

In the event that an adjustment of the narrow side conicity is triggered, this can be carried out quickly, since we ^¬ gen of the first filtering that filters out large fluctuations in the control deviation, usually only small changes in the control are great to perform. Thus, for example, causes a change of 0.1% of the narrow side conicity at a Gieß ^¬ width of 2000mm in a conventional continuous casting mold whose Gießspiegelhöhe is typically less than 1000mm, single ^¬ lich an adjustment of less than 2mm in the region of the pouring-side actuators. The entire process of such an adjustment, comprising releasing the clamping of the wide side plates, the method of the narrow side plates by means of the actuators and re-clamping the wide side plates, therefore, can usually be performed within a second or even faster, so that a very fast control process is given.

In a further preferred embodiment of the method according to the invention, a second filtering of the output K _s ' of the control rule by means of a saturation filter

Os according to

S (K _s , K _Sfm i _n , K _Sfmax ), where

K '' _s a abgelei ^¬ Teter by means of the saturation value Os filter for determining the manipulated variable K _s, a lower limit value for K and Schmalseitenkonizität

K is an upper limit for the narrow-side conicity K _s . The saturation filter Os ensures that the narrow-side conicity K _s regulated by the control loop remains within the permissible range defined by the limit values K _s , _min and K _s , _max , eg within 1.1 to 1.2. The limit values K _s , _min and K _s , _{max are} parameters of the control ^method , which are usually preset, but which can also be changed during the casting process. Thus, the limits K _s , _min and K _s , _max, for example, when switching between two metal batches by an operator or by a control system can be changed if a changed composition of the molten metal requires it.

In a further preferred embodiment of the method according to the invention, the narrow-side conicity K _{s is} determined by a third filtering of a value K _s ''derived from the output K _s ' of the regulation ^¬ rule by means of a hysteresis ^filter Φ _Η

K _s = Φ _Η (| K _S "-I _s |; λ), where || denotes the formation of the numerical absolute value and λ denotes the threshold value of the hysteresis filter and the derived value K _s " of a signal processing prior to the third filtering the output size K _s ' corresponds to the regulation.

According to a two-point controller, the manipulated variable of the control loop when the detected in the current cycle of the control loop value K _{s s} Schmalseitenkonizität the magnitude order differs Minim ^¬ least the value of λ by the current actual value I is changed only. This causes an Ver ^¬ of the actuators of the narrow side plates is only carried out if the newly calculated set value for the Schmalseitenkonizität from the existing value, for example, by more than 0.05, is different so that for example, at only ge ^¬ ringfügigen fluctuations of the production conditions on Quality of the produced metal strand have no effect, the narrow side plates are not unnecessarily adjusted and in particular the clamping of the wide side plates not solved which contributes to a consistent stability of the continuous casting process and to the speed of the regulatory procedure. Furthermore, the invention relates to a

Apparatus for setting a narrow-side conicity K _{s of} a continuous casting mold for the production of a metal strand, in particular for carrying out one of the described methods, wherein the continuous casting mold comprises a first and a second narrow side plate, on each of which at least two position-controlled actuators for positioning the jewei ^{¬ age} narrow side plate in different Distance to the pouring end of the continuous casting mold are arranged and wherein the device has a control unit and Einrich ^¬ lines for detecting the forces occurring during operation of the continuous casting mold in the direction of action of each actuator, characterized in that the control unit is set up for a control loop, wherein the control loop a reference pressure P _ref as a reference variable,

a median surface pressure P _med between the narrow side plates and the metal strand as controlled variable, wherein the mean surface pressure P _med can be determined from the forces occurring in the effective direction of the actuators,

- a controller _dlf by the function of a control deviation P = P _ref - P _med Schmalsei ^¬ tenkonizität K _s can be determined as an input variable as the manipulated variable of the control loop, and

a controlled system, by means of which the position of the first and / or the second narrow side plate can be set in accordance with the narrow side conicity K _s by means of the actuators. The advantageous embodiments of the device according to the invention for adjusting a narrow-side conicity of a continuous casting mold essentially correspond to those of the method according to the invention.

In a preferred embodiment of the device according to the invention, at least one of the actuators is a hydraulically actuated actuator.

Such actuators can be moved very quickly because no transmission is needed and are well known from the prior art. In a particularly preferred embodiment of the device according to the invention, at least one of the hydraulically actuated actuators is a double-acting hydraulic cylinder.

Double acting hydraulic cylinders offer the advantage that the force applied by each actuator force can be determined very easily by two pressure sensors per actuator, since the force is determined by the differential pressure between the two chambers and the cross sectional area of the piston of doppeltwir ^¬ kenden hydraulic cylinder. Therefore, retrofitting an existing continuous casting mold, which already has such hydraulic cylinders for adjusting the narrow side plates, for carrying out the method according to the invention in a simple and cost-effective manner, since only sensors for detecting the corresponding pressures and the travel positions of the corresponding actuators must be installed.

In a further embodiment of the device according to the invention, at least one of the actuators has an electrical rotary drive.

Such actuators allow a simple determination of the actuator position based on the position of the drive axis of the electrically operated motor or an axis of the transmission, which is usually used between the motor and the linearly moving point of the actuator in question. The forces occurring at the points of action of the actuators can be detected, for example, via strain gauges.

In a further preferred embodiment of the device according to the invention, at least one of the electrically driven actuators is a linear motor.

Linear motors do not require a gear and therefore have no mechanical play. Furthermore, they offer the advantage of being out of the power-speed curve and out of the power-current characteristic occurring force can be determined without further Krafts ^¬ sors.

The above-described characteristics, features, and advantages of this invention, as well as the manner in which these are achieved, will become clearer and more clearly understood in the context of the following description of embodiments, taken in conjunction with the drawings. In this case, a perspective view of a continuous casting mold, a section through a continuous casting mold normal to the width direction, a section through a continuous casting mold normal to the thickness direction, schematically in the width direction of the mold on passing forces, the signal flow of a narrow side plate of he ^¬ inventive control circuit and

4 shows the schematic structure of an inventive

Control circuit of a narrow side plate with two acces- gates.

FIG la shows in perspective view the arrangement of the broad sides ^¬ plates 2, 2 'and the first and the second narrow side plate 4 and 4' of a continuous molding 1, wherein the two narrow-side plates 4, 4 'along the inner surfaces of the broad side plates 2, 2' slidably are arranged. The backup plates of the individual Kokillenplatten and the actuators for the adjustment of the narrow side plates are not shown in this on.

Furthermore, in FIG. 1 a, the directional vectors of the thickness direction D, the width direction B and the casting direction G are shown in their spatial position with respect to the continuous casting mold 1, wherein the vectors D, B and G form an orthogonal, right-handed coordinate system.

At the pouring end 3 liquid molten metal is introduced with the addition of casting powder in the interior of the continuous casting 1, where the molten metal in the casting direction G wei ^¬ tertransportiert and at the outlet end 3 'in the form ei ^¬ nes teilerstarrten metal strand 5 from the mold 1 is ^¬ attracted , The metal strand 5 has, with respect to the normal plane to the casting direction G, a rectangular cross section whose short side is oriented in the thickness direction D and whose long side is oriented in the width direction B.

FIG lb shows a section through the continuous casting mold 1 of FIG la normal to the width direction B, wherein the relative to the casting direction G inclined broadside plates 2, 2 'with the attached backup plates 7, 7' and the trapezoidal shape of the second narrow side plate 4 'can be seen.

The distance f of the inner surfaces of the wide side plates 2, 2 'at the inflow end 3 is greater than the corresponding distance d at the outlet end 3' of the continuous casting mold 1, where d is also referred to as Gießdicke, since the gegos ^¬ sene metal strand 5 (in FIG lb not shown) with this thickness from the enclosed by the continuous casting mold 1 In interior space.

FIG. 1 c shows a section through the continuous casting mold 1 from FIG. 1 a normal to the thickness direction D. Visible are the relative to the casting direction G inclined narrow side plates 4, 4 'with the attached backup plates 6, 6', also the rectangular shape of the wide side plate 2 he ^¬ recognizable, along the inside of the narrow side plates 4, 4 'are displaced.

The distance e of the inner surfaces of the narrow side plates 4, 4 'at the inflow end 3 is again greater than the corresponding distance b at the outlet end 3' of the continuous casting mold 1, wherein b is referred to as casting width.

On the outer sides of the narrow side plates 4, 4 'engages in each case an upper actuator Αι, ι or A ₂ , i near the feed end 3 of the continuous casting mold 1 and a respective lower actuator Ai, 2 or A ₂ , 2 near the outlet end. 3 'the continuous casting mold 1 on. By means of acting in the width direction B actuators Αι, ι or Ai, ₂ , the first narrow side plate 4 with respect to their inclination to the casting direction G and its position in the direction B or B held in a certain position, wherein the upper actuator Ai, ₂ the Force F i, i and the lower actuator Ai, _2, the force F i, _{2 occurs} along the effective direction of the respective actuator. Accordingly, by means of the actuators A ₂ , i and A _{2, 2,} the inclination and the position of the second narrow side plate 4 'set or maintained, wherein the upper actuator A ₂ , i, the force F ₂ , i and the lower actuator A _{second 2,} the force F _{2, 2 occurs} in the effective direction of the respective actuator.

With the above definitions and the distances illustrated in FIG lb, and lc, the FIG wide seitenkon- calculated izität K _b and K _s as dimensions Schmalseitenkonizität ^¬ loose size, in each case in percent, in the subject example to

K _b = (f - d) × 100 / H K _s = (e - b) x l00 / b

However, other calculation rules for the conicities are conceivable, for example, the narrow-side conicity K _{s can} also be related to the mold height H.

2 shows a section normal to the thickness direction D through a continuous casting mold 1, the first and second Schmalsei- tenplatte 4 and 4 'with two actuators (Αι, ι, Ai, ₂ ) and (A ₂ , i, A ₂ , ₂ ), but the inclination of the narrow side plates 4 and 4 'is not shown. Along the inner surface of the first narrow side plate 4 of the linearly increasing in the casting direction G course of the ferrostatic pressure P _{fer of} the molten metal 10 is shown schematically, while along the inner surface of the second Schmalseitenplat ^¬ te 4 'growing in the casting G strand shell 13 he ^¬ is recognizable. Furthermore, the center line M indicates the Symmet ^¬ rielinie of the metal strip 5 with respect to the Breitenrich- tung B of the continuous molding. 1

Near the pouring end 3 of the continuous casting mold 1, the surface of the cast-in molten metal 10 is also referred to as pouring mirror 12, which is at a distance h - the so-called Gießspiegelhöhe - above the outlet end 3 'of the continuous casting mold 1. At the outlet end 3 'of the solidified metal strand is 5 pulled out of the casting die 1, wherein the strand already formed ^¬ cup 13 approximately to roll in the width direction B by lateral Strangfüh- 14 and 14' is supported.

With Fi, i and F ₂ , i are the forces of the upper Ak ^¬ tors Αι, ι and A ₂ , i (not shown in Figure 2), as shown in Figure lc, near the pouring end 3 on the respective narrow side plate 4 and 4 'are transmitted. Accordingly symbo ^¬ taping Fi, ₂ or F _{2, 2,} the forces of the exit-side actuators Ai, 2, and A _{2; 2.}

In FIG. 3, in a section normal to the thickness direction D of FIG. ne half of a continuous casting _{mold according} to the invention 1 to the center line M and the control technology connection to ei ^¬ ne control unit 8 shown, wherein the first narrow side ^¬ plate 4 by means of two actuators Αι, ι and A _ir2 can be moved. The other half of the continuous casting mold 1, which comprises the second narrow side plate 4 'and corresponding actuators A ₂ , i and A ₂ , 2, is connected in accordance with the first half shown to the control unit 8, but not shown in FIG. In addition, in the specific example are the AK factors Αι, ι and A _ir2 out as a double-acting hydraulic cylinder ^¬.

The liquid molten metal 10, which is introduced into the continuous casting mold 1 during the continuous casting near the upper, feed-side end 3, forms the surface with its surface

Gießspiegel 12 at a distance corresponding to the Gießspiegel ^¬ height h above the lower, exit-side end 3 'of the continuous casting mold 1 from. In the casting direction G below the first narrow side plate 4, the solidified strand shell 13 is supported by lateral strand guide rollers 14.

The actuator Αι, ι engages near the upper, casting-side end 3 of the continuous casting mold 1 on the first narrow side plate 4 and can move them at this point in the direction of width B; Similarly, the first narrow side plate 4 of the actuator A \ _r 2, which acts in the vicinity of the lower, exit-side En ^¬ of 3 'on the first narrow side plate 4, are also moved in the width direction B. To detect the instantaneous position of the first narrow side _plate 4, the actuators Αι, ι and A _{ir2 transmit} the respective position values Χι, ι and Xi, 2 to the control unit 8, which are determined by corresponding position sensors 16 of the respective actuator. In addition, the pressures of the two chambers of each double-acting hydraulic cylinder are detected by means of corresponding pressure sensors 11 and transmitted to the control unit 8. From the difference of these pressures, the forces F i, i and Έ _ι2 , with which the actuators Αι, ι and Ai, 2 act on the first narrow side plate 4, determine. Furthermore, the actuators Αι, ι and Ai, _{2 are} acted upon by hydraulic drive units 9 with corresponding amounts of hydraulic fluid, so that the pistons of the actuators are moved in accordance with the setpoint positions Υχ, χ and Υχ, ₂ determined by the control unit 8. The hydraulic drive units 9 Kgs be ^¬ NEN example, hydraulic pumps or valves, which provide the required volume in each case of hydraulic liquid ^¬ ness available. For the second narrow side plate 4 'not shown in FIG. 3, the statements apply correspondingly with respect to the actual positions X ₂ , x and X ₂ , ₂ and the forces F ₂ , x and F ₂ , 2 of the actuators A ₂ , x and A _{2 2} and for the predetermined by the control unit 8 target positions Y _{2; 1} and Y ₂ , ₂ .

4 shows an embodiment of a control circuit 15 for adjusting the Schmalseitenkonizität K _s according to the he ^¬ inventive method in which the control circuit 15 in addition to the actual control law 25, a first temporal Filter ^¬ tion 22 of the control deviation P _d IF, and a second filtering 23 in With regard to the permissible maximum values and a third filtering 24 with respect to a desired hysteresis behavior of K _s .

A cycle of the control loop 15 runs for a Stranggussko ^¬ kille 1, comprising a first and a second narrow side plate 4 and 4 ', as follows:

The forces F i transmitted by the actuators A _{1, 1} to the first narrow side plate 4 _{; 1} and the 'transmitted by the actuators A _{2, j} to the second narrow side plate 4 forces F _{2, j} are captured in a measuring member 2 6, from which h together with the Who th ^¬ the casting level and the casting thickness d the Regelgrö ^¬ SSE of the control circuit 15 in the form of a median Flächenpres ^¬ solution P _med (with pressure as a physical unit) is determined. The indices i and j in this case comprise the value range {1,... N1} or {1,... N2}, where N1 or N2 the number of

Designate actuators on the first and second narrow side plate 4 and 4 '.

- The reference variable of the control loop 15 is a reference Pressure P _ref from the density of the liquid molten metal Pi _iq , the Gießspiegelhöhe h and a dimensionless Korrek ^¬ turfaktor S used. Here, the values of h, p _liq and S for each cast batch can either be fixed or changed during the casting process.

In particular, the current can be detected casting level h Messtech ^¬ cally and the instantaneous value obtained is transmitted to the control loop 15 °. - It is the current value of the deviation P _dlf of Re ^¬ gelkreises 15 according

Pdif Pref ^- Pmed determined and a control unit 8 (not Darge ^¬ represents in FIG 4) is stored and supplied to the controller 21 of the control circuit 15, the regulator 21 besides the actual Re ^¬ gelvorschrift 25 in the present example, a first, two ^¬ te and third filtering 22, 23 and 24 included.

- In the next step from the current value of P _dlf to ^¬ together with stored values of the control deviation from previous passes through the loop 15 by means of a first filter 22, the _τ a time-based filter Φ comparable turns that spans a past period of time τ, a filtered value P _d if 'determined from the control deviation, where ^¬ in the filter Φ _Τ serves to filter out short-term deviations and high-frequency interference and thus to determine a time ^smoothly smoothed value of the control deviation.

- In the control law 25 of the control circuit are the actual ^¬ values of the positions _Xi-1 of the actuators Ai, ± the first narrow ^¬ side plate 4 and the actual values of positions X _{2, j} of Ak ^¬ ports A _{2, j} of the second narrow side plate 4 ' detected by means of position sensors 16 (not shown in FIG 4) and determined therefrom according to the geometric conditions of the continuous casting mold 1, an actual value I _s for the Schmalseitenkon ^¬ icity of the continuous casting mold 1. From the actual value I _s and from the time-filtered value P _d if 'is an output gungsgröße K _s ' of the control rule 25 is determined such that on the effect of the actuators Ai _{; 1} and A ₂ , _j in the controlled system 20 of the control deviation P _{dlf is} counteracted.

Subsequently, in a second filtering 23 by ei ^¬ nes saturation filters Φ ₃ that the allowable lower limit K _{s, min} and the upper limit K _{s, max} as a parameter for Schmalsei ^¬ tenkonizität K _s includes, from the output of K _s' of the control law 25 a derived value K _s '' determined.

This prevents the narrow-side conicity K _s from ^exceeding or _falling below the preset limit values with a large or permanent control deviation P _dlf , which would be effected in particular in the case of a proportional control in the control regulation 25.

Thereafter, in a third filtering 24 by means of a hysteresis filter Φ _Η from the derived value K _s '' the value to be set for the narrow-side conicity K _s ^¬ be adjusted, which simultaneously represents the manipulated variable of the control loop 15. The hysteresis filter Φ _{Η contains} a parameter λ which writes the threshold value of the hysteresis ^filter . This parameter defines the minimum difference between the manipulated variable K _s and the associated actual value I _s , from which an adjustment of the narrow side plates 4 or 4 'is actually carried out. Differences below the threshold value λ are suppresses the hysteresis filters _Φ Η un ^¬ by the manipulated variable K _s the actual value of I _s is Equilibrium ^¬ sets.

In the controlled system 20 of the control loop 15 from the new default value for the narrow-side conicity K _s and from the casting width b, the corresponding desired positions Yi _{; 1} or Y ₂ , _{3 of} the actuators Ai _{; 1} and A ₂ , _{j of} the first and second

Narrow side plate 4 and 4 'determined and causes an adjustment of the narrow side plates by appropriate employment of the actuators, the adjustment is only Runaway ^¬ leads, if the manipulated variable K _s and the associated actual value I _s differ. Although the invention in detail by preferred execution ^¬ examples has been illustrated and described in detail, the invention is not limited by the disclosed examples and other variations can be derived therefrom by the skilled artisan without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

1 continuous casting mold

 2, 2 'wide side plate

3 pouring end

 3 'exit end

 4 first narrow side plate

4 'second narrow side plate

 5 metal strand

6, 6 'backup plate narrow side

 7, 7 'backup disk broadside

 8 control unit

 9 hydraulic drive unit

 10 molten metal

11 Pressure sensor, force sensing device

 12 pouring mirrors

 13 strand shell

 14, 14 'strand guide rollers

 15 control loop

16 position sensor

 20 controlled system

 21 controllers

 22 first filtering

 23 second filtering

24 third filtering

 25 regulation

 26 measuring element

 Αι, ι actuator i the first narrow side plate

A ₂ , _j Actuator j of the second narrow side plate

Αι, ι Eingießseitiger actuator of the first narrow side plate

Ai, 2 outlet side actuator of the first narrow side ^{plate ¬} te

A ₂ , i inflow-side actuator of the second narrow side plate

A ₂ , 2 outlet side actuator of the second narrow side plate

b casting width

 B width direction

d casting thickness D thickness direction

e inflow-side distance of the narrow side plates f pour-side distance of the broad side plates

Fi, i force on actuator i of the first narrow side plate F ₂ , _j force on actuator j of the second narrow side plate

Fi, i force on the pouring-side actuator of the first narrow ^¬ side plate

Fi, 2 force on the outlet side actuator of the first narrow ^¬ side plate

F ₂ , i force on the pouring-side actuator of the second narrow ^¬ side plate

F ₂ , 2 force on the outlet side actuator of the second narrow ^¬ side plate

Φ _Η hysteresis filter

Φ ₃ saturation filter

Φ _τ time-related filter

 G casting direction

h pouring height

 H mold height

i index regarding first narrow side plate

I _s actual value of narrow-side conicity

j index with respect to the second narrow side plate

K _s narrow-side conicity, manipulated variable

K _s ' output of the regulation

K _s '' derived value

K _s , _min lower limit for narrow-side conicity

K _s , _max upper limit for narrow-side conicity

λ threshold

 M center line

Nl number of actuators of the first narrow side plate

N2 Number of actuators of the second narrow side plate

P _d i _f control deviation

P _d i _f 'filtered value of the control deviation, input variable of the control specification

P _med mean surface pressure, controlled variable

P _ref reference _pressure, reference variable

Pii _q Density of liquid molten metal

 S dimensionless correction factor

τ time span Actual position of the actuator i of the first narrow side plate

 Actual position of the actuator j of the second narrow side plate

 Actual position of the pouring-side actuator of the first narrow side plate

> ^■ !, 2 actual position of the outlet side actuator of the first

 Narrow side plate

2, 1 actual position of the pouring-side actuator of the second

 Narrow side plate

 Actual position of the outlet side actuator of the second narrow side plate

 Target position of the actuator i of the first narrow side plate

 Target position of the actuator j of the second narrow side plate

 Target position of the pouring-side actuator of the first narrow side plate

 Target position of the outlet side actuator of the first narrow side plate

 Target position of the pouring-side actuator of the second narrow side plate

 Target position of the outlet side actuator of the second narrow side plate

Claims

claims

1. A method for adjusting a narrow side conicity (K _s ) of a continuous casting mold (1) for the production of a metal strand (5) by means of at least one control loop (15), the continuous casting mold (1) comprising a first narrow side plate (4) and a second Narrow side plate (4 ')

- Wherein on the first narrow side plate (4) a plurality (Nl) position-controlled actuators (Ai _{; 1} ) with ie {l, ..., Nl} to

Positioning the first narrow side plate (4) and on the second narrow side plate (4 ') a plurality (N2) positi ^¬ onsgeregelter actuators (A _{2, j)} each with {l, ..., N2} (for Positionin ^¬ ren the second narrow side plate 4 ') in each case at a different distance from the feed-side end (3) of

Continuous casting mold (1) are arranged, and

- In the effective direction of each actuator (Ai _{; 1} , A ₂ , _j ) during operation of the continuous casting mold (1) corresponding forces (Fi, i, F ₂ , _j ) with ie {1, Nl} and {1, .. ., N2} occur, characterized in that during a cycle through the at least one control loop (15)

- A reference pressure (P _ref ) as a reference variable and

- A mean surface pressure (P _med ) between the Schmalsei ^¬ tenplatten (4, 4 ') and the metal strand (5) as a controlled variable, wherein the average surface pressure (P _med ) from the forces (Fi, i, F ₂ , _j ) determined will be consulted and that

- A controller (21) in response to a control deviation (Pdif) = (Pref) ^~ (Pmed) as input the Schmalseitenko ^¬ nicity (K _s ) as the manipulated variable of the control loop (15) determined and that

- The position of the first and / or the second narrow side plate (4, 4 ') is adjusted according to the narrow side conicity (K _s ) via a controlled system (20) by means of the actuators (Ai _{; 1} , A _2;] ).

2. The method of claim 1, wherein the reference pressure (P _ref ) is a function of the density (pn _q ) of the liquid molten metal (10), a Gießspiegelhöhe (h) and a dimensionless correction factor (S).

3. The method according to any one of the preceding claims, wherein the average surface pressure (P _med ) by the expression

 Nl N2

P _med = [(Fi, i) + (F ₂ , j)] / (2 * h * d)

 = 1 j = l with a Gießspiegelhöhe (h) and a casting thickness (d) of the continuous casting mold (1) is determined.

4. The method according to any one of the preceding claims, wherein the setting of a common narrow side conicity (K _s ) for the first and the second narrow side plate (4, 4 ') sym ^¬ metric with respect to the casting direction (G) of the Stranggussko- kille (1 ) under specification of the spatial position of the center line (M) of the metal strand (5) with respect to the Breitseitenplat ^¬ th (2, 2 ^λ ) and the casting width (b) takes place.

5. The method according to any one of the preceding claims, wherein the controller (21) a regulation (25) with one of the

Control deviation (P _d i _f ) derived input variable (P _d i _f ') and an output variable (K _s ') comprises and wherein

- in each cycle of the control loop (15) the actual positions (Xi _rl, 2,) of the actuators (A _{i; 1,} A _{2, j)} at least one of ers ^¬ th or the second narrow side plate (4, 4 ') are detected,

- From an actual value (I _s ) of the narrow-side conicity (K _s ) is derived from ^¬ and

in a controlled system (20) of the control circuit (15), which images the effect of the narrow-side conicity (K _s ) on the average surface pressure (P _med ), the narrow-side conicity (K _s ) by specifying corresponding desired positions (Yi, ±, Y2,) for the actuators (Ai _{; 1} , A ₂ , _j ) at least one of the first or the second narrow side plate (4, 4 ') is only ^readjusted if there is a difference to the determined actual value (l _s ).

6. The method of claim 5, wherein the control rule (25) K _s '= I _s - k ^• P _d i _f ', where k is a Proportionsi ^¬ tätsfaktor with a range of values from 0.001 to 0.1.

7. The method according to any one of claims 5 or 6, wherein from the control deviation (P _d i _f ) by a first filtering (22) by means of a time-related filter (Φ _τ ), the input variable (P _d i _f ') of the control rule (25 ) according p _dif '= Φ _τ (Pdi _f; is {Pdif} _τ) determined, wherein {P _d i _f Jx a lot of (for a time ^¬ span τ reaching back, stored values of the Regelab ^¬ deviation P _d i _f ) from previous cycles of the control loop (15).

8. The method according to any one of claims 5 to 7, wherein from the output variable (K _s ') of the control rule (25) by a second filtering (23) by means of a saturation filter (CDs) a derived value (K _s '') according to

Ks CDs (K _s , K _s , min A K _s , max) r is determined, where K _s , _{m are} in a lower limit and K _s , _m ax is an upper limit for narrow-side conicity (K _s ).

9. The method according to any one of claims 5 to 8, wherein by a third filtering (24) derived from the output variable (K _s ') of the regulation (25) derived value (K _s '') by means of a hysteresis filter (Φ _Η ) the Narrow-side conicity (K _s ) according to

K _S = _Φ Η (IK _S "- I sl; λ), is determined, where | | characterized the formation of the absolute numerical value ^¬ λ and the threshold of the Hysteresefilters _(Φ Η) be ^¬.

10. An apparatus for adjusting at least one narrow side conicity (K _s ) of a continuous casting mold (1) for the production of a metal strand (5), in particular for performing a method according to claims 1 to 9, wherein the continuous casting mold (1) a first narrow side plate ( 4) and a second narrow side plate (4 '),

- wherein on the first narrow side plate (4) a plurality of (Nl) position-controlled actuators (Ai _{; 1} ) with ie {l, ..., Nl} for positioning the first narrow side plate (4) and on the second narrow side plate (4 ') a plurality (N2) positi ^¬ onsgeregelter actuators (A _{2, 3)} each with {l, ..., N2} for positioning the second narrow side plate (4 ') in each case under ^¬ schiedlichem distance to the pouring end (3) of the continuous molding (1 ) are arranged, and

- wherein the device via a control unit (8) and A ^¬ directions (11) for detecting the during operation of the continuous casting mold (1) in the effective direction of the respective actuators (Αι, ι, A ₂ , _j ) occurring forces (Fi, i, F ₂ , _j ) with

ie {1, nl} and the {1, ..., N2} features, characterized in that the control unit (8) is directed ^¬ for at least one control loop (15), wherein the control circuit (15)

a reference pressure (P _ref ) as a reference variable,

- A mean surface pressure (P _me d) between the Schmalsei ^¬ tenplatten (4, 4 ') and the metal strand (5) as a controlled variable, wherein the average surface pressure (P _med ) from the forces (Fi _fl , F ₂ , _j ) can be determined is

a regulator (21), by means of which the narrow-side conicity (K _s ) can be determined as the manipulated variable of the control circuit (15) as an input variable as a function of a control deviation (Pdif) = (Pref) ^~ (Pmed), and - a control system (20), via which by means of the actuators (A _{i; 1,} A _{2, j),} the position of the first and / or the second narrow ^¬ side plate (4, 4 ') corresponding to the Schmalseitenkonizität (K _s) is adjustable, having .

11. Device according to claim 10, wherein at least one of the actuators (Ai _{; 1} , A ₂ , _j ) is a hydraulically moved actuator.

12. The apparatus of claim 11, wherein at least one of the hydraulically actuated actuators (Ai _{; 1} , A ₂ , _j ) is a double-acting hydraulic cylinder.

13. The apparatus of claim 11, wherein at least one of the actuators (Ai, ±, A ₂ , j) has an electric rotary drive.

14. The apparatus of claim 11, wherein at least one of the electrically driven actuators (Ai _{; 1} , A _2;] ) is a linear motor.