AT519154A1 - Regulation of the narrow-side conicity of a continuous casting mold - Google Patents

Abstract

The invention relates to a method and a device for regulating the narrow-side conicity of a continuous casting mold based on the measurement of the forces applied to the narrow sides with the aid of actuators. In order to achieve the best possible narrow-side conicity, in which by the Anstel development of the narrow side plates on the cast metal strand whose temperature-induced shrinkage balanced as precisely as possible and as large as possible contact with the metal strand is produced, the invention proposes a control loop whose deviation on the measurement of is based on the actuators occurring during continuous casting forces. By means of suitable parameterization of the control variable, the regulation and filtering of the control loop, a very fast and reliable control behavior can be realized. For a device according to the invention double-acting hydraulic cylinders are proposed as actuators.

Description

Summary

Regulation of the narrow side cone of a continuous casting mold

The invention relates to a method and a device for regulating the narrow side taper of a continuous casting mold based on the measurement of the forces applied to the narrow sides with the aid of actuators. In order to achieve the best possible narrow side taper, in which the temperature-related shrinkage is compensated for as precisely as possible by placing the narrow side plates on the cast metal strand and thus making the largest possible contact with the metal strand, the invention proposes a control circuit, the control deviation of which is based on the measurement of forces acting on the actuators during continuous casting. Appropriate parameterization of the control variable, the control specification and filtering the control circuit can result in very fast and reliable control behavior. Double-acting hydraulic cylinders are proposed as actuators for a device according to the invention.

FIG 3/56

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description

Regulation of the narrow side taper of a continuous casting mold

The invention relates to a method for regulating the narrow side taper 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, the narrow side plates of which are set in accordance with the method according to the invention with the aid of actuators located at different distances from the casting side.

Continuous casting molds are used when casting 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 metal plates, the so-called mold plates, which are arranged so as to be displaceable relative to one another and are preferably made from a copper alloy and essentially have a cuboid shape.

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

The four mold plates of a continuous casting mold are arranged at the same height in relation to the casting direction, the two broad side plate plates and the two narrow side plates each lying opposite one another. This creates a mold open on both sides, the openings of which are referred to as the pour-side or outlet-side end and which have a rectangular cross section with respect to a cutting plane normal to the casting direction.

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The arrangement of the mold plates with respect to one another is such that each of the two broad side plates contacts the two narrow side plates with their inner surface during the casting process, and conversely each narrow side plate with two opposite outer surfaces contacts the two broad side plates. The distance between the outlet-side ends of the narrow side plates is referred to as the casting width, since this distance defines the dimension of the cast metal strand when it emerges from the mold.

On the one hand, this arrangement enables the narrow side plates to be displaced parallel to the inner surfaces of the broad side plates even during the casting process. On the other hand, a clamping force can be exerted on the narrow side plates by mechanically positioning the wide side plates against the narrow side plates.

The space enclosed by the mold plates in relation to the casting direction is referred to below as the interior of the mold, accordingly the surfaces of the mold plates facing the interior are referred to as their inner surfaces, analogously to this, the surfaces opposite the inner surfaces of the respective cuboid mold plates are also referred to as outer surfaces called the mold plates.

So-called back-up 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 metal melt released during continuous casting from the mold plates. Such devices, e.g. Milling on the outer surfaces of the mold plates, which together with the backing 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 is carried out by corresponding actuators, which make it possible to insert a / 56

2016P00270AT to position individual mold plates spatially and thereby to vary the cross-sectional area of the mold that is decisive for the dimension of the metal slab produced. Such actuators can e.g. be motor-driven spindles or hydraulic actuators, which are also known from the prior art.

During the casting process, a metal melt is introduced into the interior of the mold at the end on the pouring side, the metal melt starting to solidify in the contact area with the mold plates due to the heat being given off to the mold plates, and a so-called strand shell is formed in this area, the thickness of which is formed when the corresponding strand section passes through continuously increased by the mold. The metal strand which is partially solidified in this way is pulled out by appropriate pull-out devices, e.g. driven driver rollers in the roller table following the mold, pulled out of the mold at the outlet end thereof, this process being supported by mechanical oscillation movements of the mold itself.

The surface of the molten metal in the interior of the continuous casting mold is also referred to as a mold level. Accordingly, the so-called mold level height h is defined as the distance of the mold level from the exit end of the mold.

Furthermore, casting powder is applied to the molten metal at the pouring end of the mold, which is melted on the surface of the still molten metal melt by the heat given off and subsequently a sliding film between the strand shell that forms and the inner surfaces of the mold plates, which forms the mechanical Friction between the strand shell and the inside of the mold plates is reduced.

Despite the formation of a strand shell, the majority of the section of the metal strand located inside the mold remains in the liquid phase. A corresponding ferrostatic pressure therefore acts on the strand shell, / 56

2016P00270AT which must be compensated by a corresponding back pressure of the mold plates, since the strand shell itself cannot build up sufficient back pressure.

For this reason, during the casting process, a corresponding pressure force is applied to the narrow side plates in particular by means of their actuators, since the clamping effect which the broad side plates exert on the narrow side plates is generally 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 the narrow side plate is moved at this point by a spatial displacement of the point of application by the actuator. This point of attack can be designed to be articulated if, for example, the inclination of the narrow side plate changes during the displacement by the actuator. In this sense, the point of attack is assigned a position which is displaceable in space and which is referred to below as the actuator position. Furthermore, an actuator comprises a sensor with which the current value of the actuator position is recorded, which is also referred to as the actual position of the actuator and which is transmitted to a control unit.

In the case of position control of the actuator, the control unit specifies a specific position value, which is also referred to below as the target position of the actuator. The actual position of the actuator is compared with its target position and the actuator is controlled by the control unit such that the actual position and target position match. This actuation takes place by applying an appropriate mechanical force to the actuator, 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. A mechanical force is also applied to the actuator by the control unit and can take place, for example, by changing the hydraulic pressure if the actuator is designed in the form of a hydraulic cylinder.

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During the casting process, all actuators of the continuous casting mold are given individual target positions and the internal forces of the individual actuators are regulated in such a way that the interaction of all actuators during the casting process - with the exception of the process of adjusting the position of the narrow side plates - the outward forces of the Metal melt can be balanced exactly, otherwise the narrow side plates would move. There is therefore a balance of forces between the outward forces caused by the ferrostatic pressure of the molten metal and the inward forces of the actuators.

Since metal alloys experience a reduction in their spatial volume during their solidification and subsequent cooling, the cast metal strand shrinks accordingly as it passes through the mold. It is also known that in order to achieve the highest possible quality, the cast metal strand should have as large a mechanical contact as possible with the inner surfaces of the mold plates when it passes through the mold. However, if the strand shell lifts off from the inner surface of the mold due to thermal shrinkage, this significantly reduces the heat flow from the metal strand at the point in question, which results in a non-uniform quality of the strand surface and, in extreme cases, can lead to the strand shell being torn open.

One measure to ensure that the metal strand passing through the mold is as large and uniform as possible is to predefine a slight inclination between the opposing mold plates, so that the cross section of the mold from the pouring end to the outlet end corresponds to the shrinkage of the metal strand rejuvenated.

The inclination of the opposite broad side plates is usually determined by a trapezoidal shape of the narrow side plate / 56

2016P00270AT achieved: since the narrow side plates contact the two broad side plates along their vertical extension, there is a different distance between the upper, pour-side ends of the two broad side plates than between the lower, exit-side ends of the broad side plates. The quotient of the difference between the upper distances f and the lower distances d between the broad side plates and the mold height H accordingly

Kb = (f - d) / h is also called broadside taper.

Similarly, the taper of the narrow side plates - hereinafter also referred to as narrow side taper K _s - is usually referred to as the difference between the distance e between the ends of the narrow side plates on the pouring side and the distance b between the ends of the narrow side plates on the outlet side, which is identical to the casting width b, according to

K _s = (e - b) / b defined. However, other definitions of the narrow side taper are also 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. It is conceivable, for example, to refer to a definition for the narrow side taper only on a single narrow side plate

K _s , _l = (e _l - b _l ) / b _l with le {1, 2}, where the index l is the first and the second narrow side plate and e _{l is} the inlet-side and b _{l is} the outlet-side normal distance of the narrow side plate l from the geometric Mark the center line of the continuous casting mold. In the case of such a definition of the narrow side conicity, which relates only to a narrow side plate, the continuous casting mold is consequently assigned two values for the narrow side conicity.

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Since the broadside cone is determined solely by the geometrical shape of the narrow side plates, no influence can be exerted on it during the casting operation. In order to improve the contact of the inside of the mold with the strand shell during the casting process, solutions are known from the prior art which influence the shape of the narrow side plates of a mold.

The formation of the strand shell when the metal strand passes through the continuous casting mold depends on various factors, such as the casting speed, the composition of the molten metal itself, the properties of the casting powder or the cooling capacity of the cooling device of the mold, which also influence the heat transfer from the cast metal strand to the mold and thus the mechanical contact of the metal strand with the mold.

From JP 2010 253548 A a construction for continuous casting molds is known, which proposes to mechanically bend the narrow side plates during the casting depending on the casting speed, the carbon content of the molten metal or the heat flow passing from the metal strand to the mold, 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 both the solidification profile of the strand shell and the frictional forces that occur on the inner surfaces of the mold plates as constant as possible, even with changing casting conditions, by the targeted bending of the narrow side plates, and thus to avoid the formation of longitudinal cracks in the cast metal strand , A complex bending mechanism according to FIGS. 15 and 18 is used to apply the required bending forces.

JP H03 210953 A proposes a continuous casting mold, the narrow side plates of which each have a groove 15 running in the horizontal direction perpendicular to the casting direction, which is why a kink 56 at this point under the action of force

2016P00270AT in accordance with Fig. 1. This action of force is regulated as a function of temperature values measured by means of a thermocouple in the vicinity of the outlet end of the narrow side plates. The grooves of the narrow side plates represent a mechanical weak point.

JP H02 247059 A suggests bending the narrow side plates together with the backing plates mounted on them depending on the measured heat flow or the casting speed. The bending forces required for this are very high, the inner surfaces of the narrow side plates assume a curve along the casting direction.

A disadvantage of all the publications mentioned above is that high mechanical forces or correspondingly complex trades are required to bend the narrow side plates.

In addition, in the publications mentioned, a hypothetical solidification process of the strand shell is assumed, for which a physical modeling is necessary, which in turn depends on various influencing factors and is therefore subject to the corresponding uncertainties, since no direct measurement of the actual contact area between the strand shell and the inner surfaces of the mold plate takes place ,

Another disadvantage of the above-mentioned publications is that a control system which is based on a measured temperature value or a measured heat flow has a correspondingly inherent inertia and therefore cannot react quickly enough to rapidly changing production conditions.

In order to avoid disadvantageous mechanical loads on the narrow side plates, the present invention therefore proposes, instead of bending the narrow side plates, to change their spatial position during the casting operation by guiding them along the inner sides of the wide side plates. This happens because the Klemm / 56

2016P00270AT force that the broad side plates exert on the narrow side plates is reduced, then the narrow side plates are adjusted accordingly with the aid of corresponding position-controlled actuators and finally the contact pressure of the broad side plates is reset to the original value. Such an adjustment process takes place in a controlled manner and in such a way that, despite the outward forces of the molten metal melt, there is no sudden tearing of the strand shell.

In particular, the narrow side taper can be adapted to the shrinkage of the metal strand resulting from the formation of the strand shell, so that the contact area of the narrow side plates with the strand shell is as large as possible. No forces are applied for the bending of the narrow side plates themselves and the frictional forces between the strand shell and the inner surfaces of the mold plates are not unnecessarily increased.

If the narrow side taper is optimal in this sense, the setting 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 side taper are between 0.9% and 1.3% of the pouring width according to the above definition.

Excessive taper of the narrow side plates, which causes the strand to be squeezed by the mold, causes increased wear on the mold surface and increases the friction between the mold and the strand. Under certain circumstances, when the metal strand passes through the continuous casting mold in the edge area where the narrow side plates and the broad side plates meet, the strand shell can also bulge inwards, which in turn leads to longitudinal defects in the metal strand.

On the other hand, too little taper on the narrow side creates a gap between the strand shell and the narrow side plates of the mold, which leads to a reduced strand scha / 56

2016P00270AT oil growth due to insufficient heat dissipation via the mold walls. A resulting bulging of the strand in the mold can, in addition to an increased probability of breakdown, also lead to quality problems in the edge region of the metal strand.

The optimal narrow side taper depends on various production parameters, e.g. the shrinkage characteristic of the cast metal melt or also from the actual heat dissipation, which is determined, among other things, by the properties of the mold powder and the casting speed. It therefore makes sense to dynamically adapt the narrow side taper to the prevailing casting conditions during casting.

The setting of the narrow side taper of a continuous casting mold during the casting operation as a function of a production parameter is known from the prior art.

In order to ensure rapid adjustment of the narrow side, the wide side plates can be permanently clamped, for example, by a preset spring clamp, the clamping action of which is only briefly opened by a corresponding unclamping device during the adjustment of the narrow side taper by actuators of the unclamping device canceling the clamping force of the spring clamp.

For example, DE 10 2014 227 013 A1 describes the adjustment of the narrow side taper 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 to the inner surfaces of the mold plates. The temperature distribution is preferably determined with the aid of optical waveguide sensors, with conclusions being drawn about the mechanical contact or the formation of air gaps from the ratio of measured values between centrally located and near-edge temperature sensors.

On the one hand, the temperature-based control of the narrow side cone described in DE 10 2014 227 013 A1 is relative / 56

2016P00270AT slow - 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 from the cast metal strand to the mold plates and the associated temperature changes, but without taking into account frictional forces, and is therefore only an indirect method for determining the appropriate taper, which is subject to corresponding inaccuracies.

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

Although this invention allows a quick reaction to changing production conditions with regard to the contact of the narrow side plates with the metal strand due to the pressure-controlled activation of the lower actuators, the movements of the actuators simultaneously adjust the narrow side cone itself, so that the contact behavior of the narrow side plates on the one hand and on the other hand, the optimal value of the narrow side cone cannot be set independently of one another. In addition, a uniform pouring width cannot be maintained, since during a control process the narrow side plates are tilted at their lower end and, moreover, it cannot be guaranteed that the narrow side cone is identical on both sides, which can lead to non-uniform growth of the strand shell.

It is also common to use known production parameters / 56

2016P00270AT such as the composition of the molten metal, the casting width, the current casting speed or a heat flow calculated from measured temperature values, to calculate a value for the narrow side taper and to specify this value manually using the automation system of the relevant continuous casting plant. This procedure is based either on empirical values or a model assumption with regard to strand shell growth and is therefore subject to a corresponding number of uncertainties, and there is also no precise reproducibility due to the manual intervention.

It is therefore an object of the present invention to overcome the disadvantages of the abovementioned methods and to disclose a method for regulating the narrow side taper of a continuous casting mold which, depending on the current process conditions, allows the optimum value of the narrow side taper to be set as quickly and reproducibly as possible in the sense of the greatest possible Contact surface between the strand shell and the inside of the mold is allowed without unnecessarily increasing the frictional forces.

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

In the following, a continuous casting mold is assumed, the narrow side plates of which can be moved along the inner sides of the broad side plates via at least two mechanical actuators, and as a result of which an inward force is exerted on the strand shell of the cast metal strand in order to prevent the ferrostatic pressure acting on the outside from occurring counteract solidified metal melt, since the clamping effect of the narrow side plates by the broad side plates and the intrinsic cohesive force of the strand shell itself are not sufficient to prevent the strand from tearing open. These forces transmitted from the narrow side plates to the strand shell are referred to below as narrow side forces.

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It is assumed that the casting direction of the continuous casting mold 1 is oriented essentially in the direction of the acceleration due to gravity; Therefore, the ferrostatic pressure of the molten metal introduced into the mold 1 increases linearly in the casting direction in accordance with the behavior of a liquid with the distance to the surface of the molten metal which is located in the casting direction at a distance corresponding to the level of the mold level above the outlet ends of the mold plates.

The increase in pressure within the molten metal melt naturally also continues below the outlet end of the continuous casting mold. A good approximation of a deviation from the linear rise due to the temperature dependence of the density of the molten metal can be neglected, since the temperature of the melt introduced into the mold is only slightly above the solidification temperature.

The ferrostatic pressure of the molten metal causes outward forces that have to be compensated by corresponding inward counter forces to prevent the strand shell from tearing open.

When the molten metal passes through the continuous casting mold, the cooling effect leads to the formation of a continuous shell along the inner surfaces of the mold plates.

The strand shell has an inherent strength which depends locally on its thickness and which partially compensates for the ferrostatic pressure of the molten metal which acts on the outside.

The remaining part of the ferrostatic pressure inside the continuous casting mold must be compensated for by appropriate counterpressure of the mold plates in order to avoid tearing of the strand shell.

While the corresponding back pressure is automatically set due to the fixed clamping of the broad side plates, the back pressure along the narrow side plates / 56

2016P00270AT can be actively regulated, since there is no complete clamping effect of the narrow side plates through the wide side plates. The spatial position and orientation of the narrow side plates is therefore carried out by active position control of the mechanical actuators moving the narrow side plates.

After the metal strand emerges from the continuous casting mold, the strand shell has already grown to such an extent that the ferrostatic pressure exceeding the intrinsic strength of the strand shell can be easily compensated for by spatially fixed or position-controlled strand guide rollers, the strand guide rollers directly supporting the surface of the extended metal strand.

Tests show that the narrow side forces with decreasing casting speed (less than 0.6 meters per minute) always decrease due to the formation of the strand shell and the associated strand shrinkage, until the metal strand at very low casting speeds (0 to 0.2 meters per minute) comes into contact with almost completely loses the mold narrow sides and the narrow side forces tend towards zero.

Tests also show that adjusting the narrow side taper has a direct influence on the required narrow side forces.

There is therefore an empirical relationship between the narrow side forces and the casting speed. There is also a connection between the narrow side forces and the narrow side taper.

The present invention for setting a value of the narrow side taper that is as optimal as possible, in which the inclination of the narrow side plates against the strand shell that is being formed exactly compensates for the shrinkage of the metal strand, is based on the use of this connection and suggests / 56

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A method for setting a narrow side taper K _{s of} a continuous casting mold for the production of a metal strand using at least one control circuit, the continuous casting mold comprising a first and a second narrow side plate, on each of which at least two position-controlled actuators for positioning the respective narrow side plate at different distances from the end on the casting side the continuous casting mold are arranged and wherein corresponding forces occur in the effective direction of each actuator during operation of the continuous casting mold, characterized in that the at least one control loop

a reference pressure Pref as a reference variable,

an average surface pressure Pmed between the narrow side plates and the metal strand as a controlled variable, which is determined from the forces occurring in the direction of action of the actuators, and

- A controller, which as a function of a control deviation P _dif = P _ref - P _{med determines} the narrow side taper K _s as the manipulated variable of the control loop as an input variable, and uses the actuators to position at least one of the first or second narrow side plates according to the narrow side taper K _s established.

According to the invention, each of the two narrow side plates of the continuous casting mold can be positioned by a separate, independent control circuit which only controls the actuators of the respective narrow side plate. In this case, the manipulated variable of the control loop in question depends on the inclination of the respective narrow side plate with respect to the casting direction and the method according to the invention thus comprises two independent values for the narrow side conicity - in each case one value for the first and one value for the second narrow side plate - the continuous casting mold ,

Alternatively, however, a common control loop can be used for both narrow side plates, the corresponding / 56

2016P00270AT controls the actuators of both narrow side plates. In this case, the method according to the invention comprises a common value for the narrow side taper of the continuous casting mold, the definition of which depends equally on the inclinations of both narrow side plates with respect to the casting direction.

Furthermore, the controller of the control loop can also contain filterings that either process the input signal for a control regulation contained in the control loop or process the signal determined by the control regulation before it is fed to the controlled system.

The method according to the invention enables a quick reaction to changing process conditions, since the detection of the narrow side forces, which are influenced by the process conditions, takes place practically in real time, in contrast to methods which are based on temperature or heat flow measurements.

The method according to the invention is also based on an empirical relationship between the narrow side forces on the one hand and the current casting parameters, such as the casting speed, the behavior of the casting powder or the composition of the molten metal on the other hand, this empirical relationship being modeled by the behavior of the controller. The method according to the invention therefore does not require any physical modeling of the effects of the various influencing variables, but rather is based on the measurement of the direct 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 quickly.

For example, a lifting of the strand shell from the inside of the narrow side plates, caused, for example, by excessive cooling and accompanying strand shrinkage, can be detected immediately, because it is suitable for a load

2016P00270AT agreed control position correspondingly reduce the narrow side forces to be applied. Likewise, an increase in the narrow side forces, which would cause the strand to be crushed and is caused, for example, by the cooling capacity of the metal strand being too low, can be compensated for directly. In this way, an optimal force distribution of the actuators and, accordingly, the largest possible contact area between the strand shell and the inner surfaces of the narrow side plates is achieved without the frictional forces between the strand shell and the inner surfaces of the continuous casting mold being unnecessarily increased.

Furthermore, the method according to the invention ensures good reproducibility, since the adaptation of the narrow side taper to the current production conditions does not require any operator intervention but only depends on the preset parameters of the controller or on any filtering carried out in the controller.

In a further preferred embodiment of the method _according to the invention, the reference pressure Pref is a function of the density of the molten metal p _liq , a mold level h and a dimensionless correction factor S.

The density pliq of the molten metal is to be understood as the material density of the liquid melt, the physical unit of which is given, for example, in kg / m ³ . The reference pressure Pref depends on the density of the molten metal pliq and on the level of the mold level h, which is defined as the distance between the mold level and the end of the mold on the outlet side and also contains a further dimensionless correction factor S that can be specified.

The reference pressure P _ref is a parameter of the control process and, if necessary, can also be reset during the casting process, for example by an operator or by another control system, in order to change the characteristic of the control loop. This makes it possible to take account of a change in the mold level h during the casting process

2016P00270AT view or flexibly to changes in the casting parameters, e.g. to react to a change in the composition of the molten metal, the casting powder or in the heat dissipation of the mold.

An adaptation of the reference pressure can be based, for example, on empirical values based on the recorded casting parameters, as a result of which an advantageous driving style of the continuous casting mold, once determined under certain casting conditions, can be reproduced.

The reference pressure P _ref can, for example, by the expression

Pref = S · Pferd / 2 = S · _Pliq · g · h / 2 are determined, where g is the value of the acceleration due to gravity and Horse the ferrostatic pressure of the molten metal inside the cast metal strand at the outlet end of the continuous casting mold. Since, due to the laws of physics, the ferrostatic pressure horse rises linearly in the pouring direction, the ferrostatic pressure averaged over the mold level h, which is referred to as the mean surface pressure Pmed, corresponds to half the value of the local ferrostatic pressure horse at the foot of the liquid column of the height h at the outlet end the mold. A temperature-related change in the density Pliq 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 inherent load-bearing capacity of the strand shell that forms, which weakens the effect of the outward ferrostatic pressure horse of the molten metal, furthermore the effect of the frictional forces between the narrow side plates and the broad side plates that differ from those of the Actuators of the narrow side plates counteract the forces applied and reduce them accordingly, as well as the friction between the strand shell and the narrow side plates, which due to the narrow side taper an outward / 56

2016P00270AT has a force component directed in the width direction of the continuous casting mold and depends on the value of the narrow side taper. In addition, the correction factor S can depend on the chosen casting speed v, because in particular the friction between the strand shell and the narrow side plates represents sliding friction and therefore the friction forces that occur depend on the relative speed between the surfaces involved.

With values of S <1, the self-supporting capacity of the strand shell outweighs the frictional forces between the narrow sides and the broad side plates or between the narrow side plates and the strand shell and is used, for example, in an operating mode in which the broad side plates are only pressed against the narrow side plates with very little clamping action, which is also known as soft clamping.

In contrast, values of S> 1 mean that the frictional forces between the narrow-side and broad-side plates or between the narrow-side plates and the strand shell predominate and must be compensated accordingly by the actuators of the narrow-side plates.

The dependence of the correction factor S on the casting speed v can be described, for example, by a table model based on empirical values. S can also be influenced by other factors, e.g. depend on the composition of the molten metal or the casting powder, which can also be shown in an empirically recorded table model.

The above-mentioned definition of the reference pressure P _ref offers the advantage that it represents an easy-to-use empirical modeling of the control variable of the control loop according to the invention, which, in addition to the correction factor S, depends only on process parameters which are known in any case and which therefore uses the correction factor S, for example in relation to new compositions the molten metal or the casting powder in a / 56

2016P00270AT can be expanded in a number of ways and requires no complex physical simulations.

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

N1 N2

Pmed = [Σ (Ε1 _Λ ) + Σ (F2, j)] / (2 · h · d) i = 1 j = 1, where

F1 i the force detected by a measuring element of the control circuit and occurring at the actuator i of the first narrow side plate,

F2 j the force detected by a measuring element of the control circuit and occurring at the actuator j of the second narrow side plate,

N1 the number of actuators of the first narrow side plate,

N2 denotes the number of actuators on the second narrow side plate, h the height of the mold level and d the thickness of the mold.

The mean surface pressure Pmed represents an averaging over the forces of all actuators of the two narrow side plates, which the actuators exert on the narrow side plates. These forces can advantageously be measured very simply and quickly using methods known from the prior art, as a result of which the control loop can react very quickly to control deviations. In particular, it is possible to control control deviations much more quickly than would be the case with temperature or heat flow-based controls, because / 56

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Force measurements can be carried out within fractions of a second.

In a preferred embodiment of the method according to the invention, the setting of a common narrow side taper for both narrow side plates takes place symmetrically in relation to the casting direction of the continuous casting mold, with the spatial position of the center line of the metal strand being specified in relation to the wide side plates and a value for the casting width b.

For each of the two narrow side plates, by means of the actuators acting in the width direction of the continuous casting mold, whose spatial arrangement is known, the inclination of the narrow side plate with respect to the casting direction and an absolute spatial position can be specified, which - based on the entire continuous casting mold - has four mechanical ones Represents degrees of freedom.

If the position of the center line of the produced metal strand in relation to the broad 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 broad side plates, this reduces the number of degrees of freedom by one. An additional specification of a distance of the narrow side plates from one another - for example the distance between the ends of the narrow side plates at the casting outlet end, which by definition is identical to the casting width b of the continuous casting mold - reduces the degrees of freedom by a further. Furthermore, if the inclinations of the two narrow side plates are set symmetrically with respect to the casting direction, this represents a restriction to only a single degree of mechanical freedom of the narrow side plates, which is represented by a correspondingly unique value for the narrow side conicity. As a result, there is a clear relationship between a value for the narrow side taper Ks and the position values of the individual actuators of both the first and the second narrow side plates, so that a default value for the narrow / 56

2016P00270AT side taper K _s corresponding position values of the actuators of both narrow side plates can be determined in a clear manner. In this case, the two narrow side plates of the continuous casting mold are no longer positioned independently of one another, but instead are 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 process or to leave it constant and to specify a starting value for the target positions of the individual actuators when they first pass through the control circuit. A constant value of the casting width b during the casting process is particularly desirable with regard to the quality of the cast metal strand, since complex measures for adjusting the width of the metal strand, such as e.g. Flame cutting or side upsetting can be omitted.

In a preferred embodiment of the method according to the invention, the controller of the at least one control circuit comprises a control specification with an input variable derived from the control deviation and an output variable and the actual positions {X ^ _{1 (} X ₂ , j}) of the actuators in each cycle of the at least one control circuit at least one of the first or the second narrow side plate is detected and an actual value Is for the narrow side taper Ks is derived therefrom, and this by specifying corresponding target positions {Y _{1; i} , Y2 j} for the actuators of at least one of the first or the second narrow side plate in one effect of the narrow side taper on the control system of the at least one control circuit that maps the mean surface pressure only when there is a difference to the determined actual value.

The detected actual positions of the actuators of the narrow side plates thus represent input variables and the determined target positions for the actuators represent corresponding output variables of the at least one control loop, which are determined anew each time through the at least one control loop.

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If the actual value I _{s of} the narrow side taper and the manipulated variable determined in the current cycle of the at least one control loop, which is identical to the nominal value of the narrow side taper Ks, then there is no need to adjust the narrow side taper over the controlled system. This is particularly advantageous if, when adjusting the narrow side plates, the clamping mechanism for the wide side plates usually has to be actuated, which in this case can be omitted. Such a control cycle can therefore be carried out correspondingly quickly, ie within a few milliseconds or less.

In a further preferred embodiment of the method according to the invention, the regulator is given a rule

K _s '= I _s - k · Pdif' where

P _dif 'is a variable derived from a control deviation P _{dif of} the control loop,

K _s ' are a variable determined by the control specification of the control loop for determining the manipulated variable Ks and k are a proportionality factor with a value range from 0.001 to 0.1, preferably from 0.005 to 0.02.

The control specification describes the behavior of the control loop as a function of the control deviation and is used to determine the output variable; the meaning and role of the regulation are to be understood in the context of a classic control loop and are therefore well known to the person skilled in the art.

With this rule regulation deviations can be parameterized in a very simple way: if the proportional / 56

2016P00270AT factor k has a value less than 1, this means that the determined control deviation is weakened into the correction of the output variable of the control specification, while for values greater than 1 the control deviation is amplified.

In a further preferred embodiment of the method according to the invention, the control deviation P _{dif of} the control loop is first _filtered by means of a time-related filter O _T according to

Pdif '= OT (Pdif; {Pdif} ^), where {P _dif } x is a set of stored values of the control deviation Pdif from previous cycles of the control loop and going back over a time period τ

P _dif 'one determined by the time-related filter

Input variable for the regulation of the control loop are.

This filtering can consist, for example, of simply averaging all the values of the control deviation used. However, it is also conceivable to weight current values more strongly than values from earlier times. For example, the historical values of the control deviation are preferably taken into account over a period of time τ = 5-10 seconds.

This temporal filtering of the control deviation suppresses high-frequency fluctuations in the measurement signal, which can be caused, for example, by incorrect measurements. This prevents incorrect adjustment of the narrow side plates due to incorrect measured values or to / 56

2016P00270AT establishes high-frequency interference and contributes to the stabilization of the continuous casting process.

In the event that an adjustment of the narrow side taper is triggered, this can be carried out quickly since, because of the first filtering, which filters out large fluctuations in the control deviation, usually only small changes in the manipulated variable have to be carried out. For example, a change of 0.1% of the narrow side taper at a casting width of 2000mm with a conventional continuous casting mold, the level of which is typically less than 1000mm, only causes an adjustment of less than 2mm in the area of the cast-side actuators. The entire process of such an adjustment, including releasing the clamping of the wide-side plates, moving the narrow-side plates by means of the actuators and re-clamping the wide-side plates, can therefore usually be carried out within a second or even faster, so that a very fast control process is provided.

In a further preferred embodiment of the method according to the invention, the output variable K _s ' is filtered a second time by means of a saturation filter Os according to

K _s ''= Os (Ks', K _s , min, K _s , max), where

K _s '' a value derived by means of the saturation filter Os for determining the manipulated variable K _s ,

Ks min is a lower limit for the narrow side taper Ks and

K _{3jmax are} an upper limit for the narrow side _taper Ks.

The saturation filter Os ensures that the narrow side taper Ks regulated by the control loop is within / 56

2016P00270AT of the permitted range defined by the limit values K _s , _min and K _s , _max remains, for example within 1.1 to 1.2. The limit values K _3jmin and K _s , _{max are} parameters of the control _method , which are usually preset, but which can also be changed during the casting process. For example, the limit values K _smin and K _s , _{max can} be changed by an operator or by a control system when changing between two metal batches, if a changed composition of the metal melt requires this.

In a further preferred embodiment of the method the Schmalseitenkonizität Ks through a third filtering one of the output variable K _s' derived control law of the value K _s' 'according to means of a Hysteresefilters _Φ Η

Ks = Φ ^ Ι ^ '' - Isl; λ), where | | the formation of the numerical absolute value and λ denote the threshold value of the hysteresis filter and the derived value K _s ''corresponds to a signal-technical treatment of the output variable K _s ' preceding the third filtering of the regulation.

According to a two-point controller, the manipulated variable of the control loop is only changed if the value K _s determined in the current cycle of the control loop differs in amount by at least the value λ from the current actual value Is of the narrow side taper. This means that the actuators of the narrow side plates are only adjusted if the newly calculated default value for the narrow side taper differs from the existing value, for example by more than 0.05, so that, for example, only slight fluctuations in the production conditions affect the quality of the metal strand produced have no effect, the narrow side plates are not adjusted unnecessarily and in particular the clamping of the broad side plates does not have to be released, which leads to a constant stability of the / 56

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Continuous casting process and contributes to the speed of the control process.

The invention further relates to a

Device for setting a narrow side taper K _{s of} a continuous casting mold for the production of a metal strand, in particular for carrying out one of the methods described, the continuous casting mold comprising a first and a second narrow side plate, on each of which at least two position-controlled actuators for positioning the respective narrow side plate at different distances from the are arranged on the pouring end of the continuous casting mold and the device has a control unit and devices for detecting the forces occurring during the 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 circuit, the control circuit

a reference pressure P _ref as a reference variable,

an average surface pressure Pmed between the narrow side plates and the metal strand as a controlled variable, which is determined from the forces occurring in the direction of action of the actuators, and

- A controller that uses a narrow side taper Ks as the control variable of the control circuit as a function of a control deviation P _dif = P _ref - P _med , and uses the actuators to adjust the positions of at least one of the first or second narrow side plates according to the narrow side taper Ks is.

The advantageous refinements of the device according to the invention for setting a narrow side taper of a / 56

2016P00270AT

Continuous casting molds 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 moved actuator.

Such actuators can be moved very quickly since no gear is required and are sufficiently known from the prior art.

In a particularly preferred embodiment of the device according to the invention, at least one of the hydraulically moved actuators is a double-acting hydraulic cylinder.

Double-acting hydraulic cylinders offer the advantage that the force applied by the respective actuator 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 the double-acting hydraulic cylinder. It is therefore also possible to retrofit an existing continuous casting mold, which already has hydraulic cylinders of this type for adjusting the narrow side plates, to carry 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 have to 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 application of the actuator in question. The / 56

2016P00270AT occur at the points of attack of the actuators Forces can e.g. are measured using 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 need a gear and therefore have no mechanical play. They also offer the advantage that the force occurring can be determined directly from the force-speed characteristic or from the force-current characteristic without additional force sensors.

The above-described properties, features and advantages of this invention and the manner in which they are achieved can be more clearly understood in connection with the following description of exemplary embodiments which are explained in more detail in connection with the drawings. Show

1a shows a perspective view of a continuous casting mold,

1b shows a section through a continuous casting mold normal to the width direction,

1c shows a section through a continuous casting mold normal to the thickness direction,

2 shows schematically the forces occurring in the width direction of the mold,

3 shows the signal flow of a narrow side plate of a control circuit according to the invention and

4 shows the schematic structure of a control circuit according to the invention of a narrow side plate with two actuators.

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1 a shows an oblique view of the arrangement of the broad side plates 2, 2 'and the first and second narrow side plates 4 and 4' of a continuous casting mold 1, the two narrow side plates 4, 4 'being arranged to be displaceable along the inner surfaces of the broad side plates 2, 2'. The back-up plates of the individual mold plates and the actuators for adjusting the narrow side plates are not shown in this view.

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

At the end 3 on the pouring side, molten metal is added with the addition of casting powder into the interior of the continuous casting mold 1, where the molten metal is transported further in the casting direction G and is withdrawn from the mold 1 at the exit end 3 'in the form of a partially solidified metal strand 5. The metal strand 5 has a rectangular cross section with respect to the normal plane to the casting direction G, the short side of which is oriented in the thickness direction D and the long side in the width direction B.

1b shows a section through the continuous casting mold 1 from FIG. 1a normal to the width direction B, in which the broad side plates 2, 2 'inclined relative to the casting direction G with the backing plates 7, 7' attached to them and the trapezoidal shape of the second narrow side plate 4 'can be seen.

The distance f between the inner surfaces of the broad side plates 2, 2 'at the end 3 on the pouring side is greater than the corresponding distance d at the end 3' of the continuous casting mold 1, where d is also referred to as the casting thickness, since the cast metal strand 5 (not shown in FIG. 1b) ) with this thickness emerges from the interior enclosed by the continuous casting mold 1.

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1c shows a section through the continuous casting mold 1 from FIG. 1a normal to the thickness direction D. The narrow side plates 4, 4 ', which are inclined relative to the casting direction G, can be seen, with the backing plates 6, 6' attached to them, and the rectangular shape of the broad side plate 2, along the inside of which the narrow side plates 4, 4 'can be displaced, can be seen.

The distance e between the inner surfaces of the narrow side plates 4, 4 'at the end 3 on the pouring side is in turn greater than the corresponding distance b at the end 3' of the continuous casting mold 1 at the outlet side, b being referred to as the casting width.

On the outer sides of the narrow side plates 4, 4 ', an upper actuator A11 or A21 engages near the casting-side end 3 of the continuous casting mold 1 and a lower actuator A1 2 or A2 2 near the exit-side end 3' of the continuous casting mold 1. By means of the actuators A1 1 and A1 2 acting in the width direction B, the first narrow side plate 4 can be moved with respect to its inclination to the casting direction G and its position in the width direction B or can be held in a certain position, the force F1 1 on the upper actuator A1 2 and the force F1 2 occurs on the lower actuator A12 along the effective direction of the respective actuator. Accordingly, the inclination and the position of the second narrow side plate 4 ′ are set or maintained by means of the actuators A2 1 and A2 2, the force F2 1 occurring on the upper actuator A21 and the force F2 2 occurring on the lower actuator A22 in the effective direction of the respective actuator ,

With the above-mentioned definitions and the distances shown in FIG. 1b and FIG. 1c, the broad side taper Kb and the narrow side taper Ks are calculated as a dimensionless quantity, in each case in percent, in the present example

K _b = (f - d) x 100 / H

K _s = (e - b) x 100 / b / 56

2016P00270AT

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

2 shows a section normal to the direction of thickness D through a continuous casting mold 1, the first and second narrow side _plates 4 and 4 'of which two actuators (A _{1; 1} , A _1j2 ) and (A _2j1 , A _2j2 ) are moved, respectively, however the inclination of the narrow side plates 4 and 4 'is not shown. Along the inner surface of the first narrow side plate 4, the course of the ferrostatic pressure P _{fer of} the metal melt 10, which increases linearly in the casting direction G, is shown schematically, while along the inner surface of the second narrow side plate 4 'the strand shell 13 growing in the casting direction G can be seen. Furthermore, the center line M denotes the line of symmetry of the metal strand 5 with respect to the width direction B of the continuous casting mold 1.

Near the pouring-side end 3 of the continuous casting mold 1, the surface of the cast-in molten metal 10 is also referred to as a casting level 12, which is located at a distance h - the so-called casting level - above the exit-side end 3 'of the continuous casting mold 1. At the exit end 3 ', the partially solidified metal strand 5 is pulled out of the continuous casting mold 1, the strand shell 13 already formed being supported in the width direction B by lateral strand guide rollers 14 and 14'.

F _{1; 1} and F _2j1 , as in FIG. 1c, _denote the forces of the upper actuators A1 1 and A21 (not shown in FIG. 2), which are transmitted to the respective narrow side plates 4 and 4 'near the pour-side end 3. Correspondingly, F _{1 2} and F _{2 2} symbolize the forces of the exit-side actuators A1 2 and A2 2.

In FIG. 3, in a section normal to the direction of thickness D, one half of a continuous casting mold 1 according to the invention up to the center line M and the control connection to ei / 56

2016P00270AT ne control unit 8 shown, the first narrow side plate 4 can be moved with the help of two actuators A _{1; 1} and A _1j2 . The other half of the continuous casting mold 1, which comprises the second narrow side _plate 4 'and corresponding actuators A _2j1 and A22, is connected to the control unit 8 in a manner corresponding to the first half shown, but is not shown in FIG. 3. In addition, in the concrete example, the actuators A _{1; 1} and A _{1 (2 are designed} as double-acting hydraulic cylinders.

The liquid metal melt 10, which is introduced into the continuous casting mold 1 near the upper, casting-side end 3 during continuous casting, forms with its surface the casting level 12 at a distance corresponding to the level of the casting level h above the lower, exit-side end 3 'of the continuous casting mold 1. 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 A1 1 engages near the upper, casting-side end 3 of the continuous casting mold 1 on the first narrow side plate 4 and can move it at this point of attack in the width direction B; _Similarly , the first narrow side _plate 4 can also be moved in the width direction B by the actuator A _1j2 , which _engages the first narrow side _plate 4 in the vicinity of the lower, _outlet- side end 3 '.

In order to detect the instantaneous position of the first narrow side plate 4, the respective position _values X ₁ and X _{1 j 2} are transmitted from the actuators A _{1; 1} and A ^ 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. The forces F _{1; 1} and F _1j2 with which the actuators A _{1; 1} and A1 2 act on the first narrow side plate 4 can be determined from the difference between these pressures. Furthermore, the actuators A _{1; 1} and A _1j2 of hydraulic drive units 9 with corresponding amounts of hydraulic fluid / 56

2016P00270AT acted on so that the pistons of the actuators are moved according to the _target positions Y _{1; 1} and Y _1j2 determined by the control unit 8. The hydraulic drive units 9 can be, for example, hydraulic pumps or hydraulic valves which provide the volume of hydraulic fluid required in each case. For the second narrow side plate 4 '(not shown in FIG. 3), the explanations apply analogously with regard to the actual positions X21 and X2 2 and the forces F _2j1 and F _{2j2 of} the actuators A ₂ , ₁ and A _2j2 and for the desired positions specified by the control unit 8 Y _2j1 and Y ₂ , ₂

4 shows an exemplary embodiment of a control circuit 15 for setting the narrow side taper K _{s in} accordance with the method according to the invention, the control circuit 15, in addition to the actual control specification 25, a first, temporal filtering 22 of the control deviation P _dif , and a second filtering 23 with respect to the permissible maximum values and a third filtering 24 for a desired hysteresis behavior of Ks.

A cycle of the control circuit 15 runs as follows for a continuous casting mold 1, comprising a first and a second narrow side plate 4 and 4 ':

- The forces F _{1; i} transmitted from the actuators A _{1; i} to the first narrow side plate 4 and the forces F ₂ , j transmitted from the actuators A ₂ , j to the second narrow side plate 4 'are recorded in a measuring element 26, from which together the control variable of the control circuit 15 is determined in the form of an average surface pressure P _med (with pressure as the physical unit) using the values of the mold level h and the casting thickness d. The indices i and j comprise the value range {1, ... N1} and {1, ... N2}, where N1 and N2 the number of actuators on the first and second narrow side plates 4 and 4 '. describe.

- A reference _pressure P _ref from the density of the liquid molten metal p _liq , the _{height of} the casting level h and a dimensionless correction / 56 is used as the reference variable for the control circuit 15

2016P00270AT door factor S used. 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 mold level h can be measured and the instantaneous value obtained can be transmitted to the control circuit 15.

- The current value of the control deviation P _{dif of} the control circuit 15 is determined according to ^P dif = ^P ref - ^P med and stored in a control unit 8 (not shown in FIG. 4) and fed to the controller 21 of the control circuit 15, the controller 21 being next to the actual regulation 25 in the present example includes a first, second and third filtering 22, 23 and 24.

- In the next step, from the current value of Pdif together with stored values of the control deviation from previous runs through the control circuit 15 by means of a first filtering 22, which uses a time-related filter Φ-, which spans a past time period τ, a filtered value P _dif 'determined from the control deviation, the filter Φ- being used to filter out short-term deviations and high-frequency interference and thus to determine a time-smoothed value of the control deviation.

- In the regulation 25 of the control loop, the actual values of the positions X ^ i of the actuators A _{1 (i of} the first narrow side plate 4 and the actual values of the positions X2 j of the actuators A ₂ , j of the second narrow side plate 4 'with the help of position sensors 16 (in 4 (not shown in FIG. 4)) and an actual value Is for the narrow side taper of the continuous casting mold 1 is determined from this in accordance with the geometric relationships of the continuous casting mold 1. An output variable Ks 'of the rule 25 is determined from the actual value Is and the time-filtered value Pdif' in such a way that about the effect of actuators A1 i and A2 j in Regelstre / 56

2016P00270AT cke 20 of the control deviation P _{dif is} counteracted.

- Subsequently, in a second filtering 23 by a saturation filter Φ _3, the _smin the allowable lower limit K or ceiling K _{s, max} as a parameter for Schmalseitenkonizität K _s includes, from the output of K _s' of the control law 25 is a derived value K _s '' certainly. This prevents the narrow side taper Ks from exceeding or falling below the predefined limit values in the event of large or permanently persistent control deviation Pdif, which would result in particular in the case of proportional control in control specification 25.

- Then, in a third filtering 24, a hysteresis filter Φ _{κ is used to determine} the newly set value for the narrow side taper Ks from the derived value K _s ″, which at the same time represents the manipulated variable of the control circuit 15. The hysteresis filter Φ _{κ contains} a parameter λ that describes the threshold value of the hysteresis filter. This parameter specifies the minimum difference between the manipulated variable Ks and the associated actual value Is, from which an adjustment of the narrow side plates 4 or 4 'is actually carried out. Differences below the threshold value λ are suppressed by the hysteresis filter Φ _κ by setting the manipulated variable Ks to the actual value Is.

- In the controlled system 20 of the control circuit 15, the corresponding set positions Y _{1 (i} or Y ₂ , j of the actuators A _{1; i} or A ₂ , j of the first or The second narrow side plate 4 or 4 'is determined and the narrow side plates are adjusted by adjusting the actuators accordingly, the adjustment being carried out only if the manipulated variable Ks and the associated actual value Is differ.

Although the invention has been illustrated and described in detail by preferred exemplary embodiments, the / 56

2016P00270AT

The invention is not limited by the disclosed examples and other variations can be derived therefrom by a person skilled in the art without leaving the scope of the invention.

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LIST OF REFERENCE NUMBERS

1 continuous molding 2, 2 ' 3 Broad side plate, pour-side end 3 ' exit end 4 first narrow side plate 4 ' second narrow side plate 5 metal strand 6, 6 ' Back plate narrow side 7, 7 ' 8th Back plate broadside control unit 9 hydraulic drive unit 10 molten metal 11 Pressure sensor, device for force detection 12 meniscus 13 strand shell 14, 14 ' Strand guide rolls 15 loop 16 position sensor 20 controlled system 21 regulator 22 first filtering 23 second filtering 24 third filtering 25 control law 26 measuring element A1, i ^A 2, j A1.1 A1.2 Actuator i of the first narrow side plate Actuator j of the second narrow side plate, cast-side actuator of the first narrow side plate, outlet-side actuator of the first narrow side plate A2,1 pouring-side actuator of the second narrow side plate th A2,2 outlet-side actuator of the second narrow side plate b casting width B width direction d casting thickness

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D thickness direction e distance on the pouring side 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 F2, j Force on actuator j of the second narrow side plate Fi, i Force on the casting-side actuator of the first narrow side plate F1.2 Force on the outlet-side actuator of the first narrow side plate F2,1 Force on the casting-side actuator of the second narrow side plate F2.2 Force on the outlet-side actuator of the second narrow side plate Φη hysteresis filters o _p saturation filter Φτ time-related filter G casting H casting level H mold height i Index regarding the first narrow side plate is Actual value of the narrow side taper j Index regarding the second narrow side plate Ks Narrow side taper, manipulated variable Ks' Initial size of the rule Ks '' derived value Ks, min lower limit for narrow side taper ^K s, max λ upper limit for narrow side taper threshold M centerline N1 Number of actuators in the first narrow side plate N2 Number of actuators on the second narrow side plate pdif deviation pdif ' filtered value of the control deviation, input variable of the control regulation ^P med medium surface pressure, controlled variable Pref Reference pressure, reference variable pLIQ Density of the molten metal S dimensionless correction factor τ Period of time

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X1, i Actual position of the actuator i of the first narrow side plate X2, j Actual position of the actuator j of the second narrow side plate X1.1 Actual position of the first actuator on the casting side Narrow side plate X1,2 Actual position of the first actuator on the outlet side Narrow side plate X2,1 Actual position of the second actuator on the casting side Narrow side plate x2,2 Actual position of the second actuator on the outlet side Narrow side plate Y1, i Target position of the actuator i of the first narrow side plate ^Y 2, j Target position of the actuator j of the second narrow side plate Y1,1 Target position of the casting-side actuator of the first Narrow side plate y1,2 Target position of the outlet-side actuator of the first Narrow side plate Y2,1 Target position of the second actuator on the casting side Narrow side plate Y 2,2 Target position of the outlet-side actuator of the second narrow side plate

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2016P00270AT

Claims (14)

claims 1. Method for setting a narrow side taper (K _s ) of a continuous casting mold (1) for the production of a metal strand (5) with the aid of at least one control circuit (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 (N1) of position-controlled actuators (A _{1; i} ) with ie {1, ..., N1} for positioning the first narrow side plate (4) and on the second narrow side plate (4 ') a plurality (N2) of position-controlled actuators (A _2j j), each with {1, ..., N2} for positioning the second narrow side plate (4 '), each at a different distance from the casting-side end (3) of the continuous casting mold (1), and - In the effective direction of each actuator (A _{1; i} , A ₂ , j) during operation of the continuous casting mold (1) corresponding forces (F _{1 (} i, F ₂ , j) with ie {1, ..., N1} and occur each {1, ..., N2}, characterized in that the control loop (15) a reference pressure (P _ref ) as a reference variable, - An average surface pressure (P _med ) between the narrow side plates (4, 4 ') and the metal strand (5) as a controlled variable, which is determined from the forces (F _{1 (i} , F ₂ , j), and - A controller (21) which, depending on a control deviation P _dif = P _ref - P _{med, determines} the narrow side taper (Ks) as the control variable of the control circuit (15) as an input variable, and uses it by means of the actuators (A _{1 (i} , A ₂ , j) adjusts the positions of at least one of the first or the second narrow side plates (4, 4 ') in accordance with the narrow side taper (Ks). 2. The method of claim 1, _wherein the reference _pressure (Pref) is a function of the density (p _liq ) of the molten metal 42/56 2016P00270AT (10), a mold level (h) and a dimensionless correction factor (S). 3. The method according to any one of the preceding claims, wherein the mean surface pressure (P _med ) by the expression N1 N2 Pmed = [Σ (Ε1 _Λ ) + Σ (F2, j)] / (2 · h · d) i = 1 j = 1 with a casting level height (h) and a casting thickness (d) of the continuous casting mold (1). 4. The method according to any one of the preceding claims, wherein the setting of a common narrow side taper (Ks) for the first and the second narrow side plate (4, 4 ') symmetrically with respect to the pouring direction (G) of the continuous casting mold (1) with specification of the spatial Position of the center line (M) of the metal strand (5) in relation to the broad side plates (2, 2 ') and the casting width (b). 5. The method according to any one of the preceding claims, wherein the controller (21) comprises a control regulation (25) with an input variable (Pdif ') derived from the control deviation (Pdif') and an output variable (Ks') - in each cycle of the control circuit (15), the actual positions (X ^ i, X ₂ j of the actuators (A _{1; i} , A ₂ , j) of at least one of the first and second narrow side plates (4, 4 ') are recorded, - an actual value (Is) of the narrow side taper (Ks) is derived from this and - In a control system (20) of the control circuit (15), which maps the effect of the narrow side taper (Ks) on the mean surface pressure (Pmed), the narrow side taper (Ks) by specifying corresponding target positions (Y1 i, Y ₂ , j) for the actuators (A _{1; i} , A ₂ j at least one of the first or the second narrow side plates (4, 4 ') only then new 43/56 2016P00270AT is set if there is a difference to the determined actual value (I _s ). 6. The method according to claim 5, wherein the regulation (25) is K _s '= I _s - k · P _dif ', where k is a proportionality factor with a range of values from 0.001 to 0.1. 7. The method according to any one of claims 5 or 6, in which from the control deviation (P _dif ) by a first filtering (22) by means of a time-related filter (Φ _τ ) the input variable (P _dif ') of the regulation (25) according to ^P dif '= ^{Φ P} V ^{P dif ^} T), is determined, where {P _dif } _{T is} a set of stored values of the control deviation (P _dif ) from previous cycles of the control loop (15) which go back over a period of time τ. 8. The method according to any one of claims 5 to 7, in which from the output variable (K _s ') of the regulation (25) by a second filtering (23) by means of a saturation filter (Φε) a derived value (K _s '') according Ks '' = øs is determined ^(Ks, Ks max, min, K ₃₎ where K _{s smin, maximum,} an upper limit for the Schmalseitenkonizität (K _s), a lower limit value and K. 9. The method according to any one of claims 5 to 8, in which by a third filtering (24) a value (Ks ') derived from the output variable (Ks') of the regulation (25) by means of a hysteresis filter (Φ _η ) the narrow side taper ( K _s ) according to Ks = - Isl; λ), 44/56 2016P00270AT is determined, where | | the formation of the numerical absolute value and λ denote the threshold value of the hysteresis filter (Φ _Η ). 10. Device for setting at least one narrow side taper (K _s ) of a continuous casting mold (1) for the production of a metal strand (5), in particular for carrying out a method according to claims 1 to 9, wherein the continuous casting mold (1) has a first narrow side plate (4) and comprises a second narrow side plate (4 '), - wherein on the first narrow side plate (4) a plurality (N1) of position-controlled actuators (A _{1; i} ) with ie {1, ..., N1} for positioning the first narrow side plate (4) and on the second narrow side plate (4 ') a plurality (N2) of position-controlled actuators (A _2j j), each with {1, ..., N2} for positioning the second narrow side plate (4 '), each at a different distance from the pouring-side end (3) of the continuous casting mold (1), and - The device via a control unit (8) and devices ( 11) for detecting the forces (F ₁ , _i , F ₂ , j) occurring in the effective direction of the respective actuators (A ₁ , _i , A ₂ , j) during operation of the continuous casting mold (1) with ie {1, ... , N1} and each {1, ..., N2}, characterized in that the control unit (8) is set up for at least one control loop (15), the control loop (15) a reference pressure (P _ref ) as a reference variable, - An average surface pressure (Pmed) between the narrow side plates (4, 4 ') and the metal strand (5) as a controlled variable, which is determined from the forces (F _{1; i} , F _2r j), and - a controller (21) which, depending on a control deviation P _dif = P _ref - P _{med, determines} the narrow side taper (Ks) as the control variable of the control circuit (15) as an input variable, 45/56 2016P00270AT is used and the actuators (A _{1 (i} , A ₂ , j) can be used to adjust the positions of the first and second narrow side plates (4, 4 ') according to the narrow side taper (K _s ). 11. The device of claim 10, wherein at least one of the actuators (A _{1 (i} , A ₂ , j) is a hydraulically moved actuator. 12. The apparatus of claim 11, wherein at least one of the hydraulically moved actuators (A ^ _i , A ₂ j) is a double-acting 10 hydraulic cylinder is. 13. The apparatus of claim 11, wherein at least one of the actuators (A ^ _i , A _2j j) has an electrical rotary drive. 15 14. Device according to claim 11, in at least one of the electrically driven actuators (A ^ _i , A ₂ , j) is a linear motor. 46/56 201600270 1.4