EP4353375A1 - Method for determining actuated variables of a roll stand, corresponding control program, control device with such control program, and rolling stand with such control device - Google Patents

Abstract

A rolling stand (1) for rolling a flat rolled stock (2) made of metal has working rolls (3), backup rolls (4) and intermediate rolls (5). A control device (11) for the rolling stand (1) receives actual values (I) and target values (Z). The actual values (I) describe the flat rolled stock (2) before rolling in the rolling stand (1), the target values (Z) describe a target contour and/or a target flatness of the flat rolled stock (2) after rolling in the rolling stand (1). Before rolling the flat rolling stock (2), the control device (11) determines an intermediate roll setting value (UCΔ) for an axial displacement of the intermediate rolls (5) and initial control values for a bending device (9, 10) for bending the work rolls (3) and the intermediate rolls (5), taking into account the actual variables (I), for which an expected contour and/or an expected flatness of the flat rolling stock (2) are approximated as closely as possible to the target contour and/or target flatness described by the target variables (Z). Before rolling the flat rolling stock (2) in the rolling stand (1), the control device (11) sets the axial displacement of the intermediate rolls (5) in accordance with the determined intermediate roll setting value (UCΔ) and sets the bending devices (9, 10) in accordance with the determined initial control values, at least at the start of rolling the flat rolling stock (2). The control device (11) determines the intermediate roll setting value (UCΔ) and the initial control values such that the initial work roll control value and/or the initial intermediate roll control value have a respective predetermined minimum distance from their minimum and maximum values.

Description

Field of technology

• wobei eine Steuereinrichtung für das Walzgerüst Istgrößen und Zielgrößen entgegennimmt,
• wobei die Istgrößen das flache Walzgut vor dem Walzen in dem Walzgerüst beschreiben und die Zielgrößen eine Sollkontur und/oder eine Sollplanheit des flachen Walzguts nach dem Walzen in dem Walzgerüst beschreiben,
• wobei die Steuereinrichtung vor dem Walzen des flachen Walzguts in dem Walzgerüst unter Berücksichtigung der Istgrößen einen Zwischenwalzen-Einstellwert für eine axiale Verschiebung der Zwischenwalzen, einen anfänglichen Arbeitswalzen-Ansteuerwert für eine Arbeitswalzen-Biegeeinrichtung zum Biegen der Arbeitswalzen und einen anfänglichen Zwischenwalzen-Ansteuerwert für eine Zwischenwalzen-Biegeeinrichtung zum Biegen der Zwischenwalzen ermittelt, für die eine erwartete Kontur und/oder eine erwartete Planheit des flachen Walzguts der durch die Zielgrößen beschriebenen Sollkontur und/oder Sollplanheit so weit wie möglich angenähert werden,
• wobei die Steuereinrichtung vor dem Walzen des flachen Walzguts in dem Walzgerüst die axiale Verschiebung der Zwischenwalzen entsprechend dem ermittelten Zwischenwalzen-Einstellwert einstellt,
• wobei die Steuereinrichtung zumindest zu Beginn des Walzens des flachen Walzguts in dem Walzgerüst die Arbeitswalzen-Biegeeinrichtung entsprechend dem ermittelten anfänglichen Arbeitswalzen-Ansteuerwert und die Zwischenwalzen-Biegeeinrichtung entsprechend dem ermittelten anfänglichen Zwischenwalzen-Ansteuerwert einstellt.

The present invention is based on an operating method for a rolling stand for rolling a flat rolled metal product, wherein the rolling stand has work rolls, backup rolls and intermediate rolls arranged between the work rolls and the backup rolls,

• whereby a control device for the rolling stand receives actual and target values,
• wherein the actual values describe the flat rolling stock before rolling in the rolling stand and the target values describe a target contour and/or a target flatness of the flat rolling stock after rolling in the rolling stand,
• wherein the control device determines, prior to rolling the flat rolling stock in the rolling stand, taking into account the actual variables, an intermediate roll setting value for an axial displacement of the intermediate rolls, an initial work roll control value for a work roll bending device for bending the work rolls and an initial intermediate roll control value for an intermediate roll bending device for bending the intermediate rolls, for which an expected contour and/or an expected flatness of the flat rolling stock are approximated as closely as possible to the target contour and/or target flatness described by the target variables,
• wherein the control device adjusts the axial displacement of the intermediate rolls in accordance with the determined intermediate roll setting value before rolling the flat rolling stock in the rolling stand,
• wherein the control device adjusts the work roll bending device according to the determined initial work roll control value and the intermediate roll bending device according to the determined initial intermediate roll control value, at least at the beginning of the rolling of the flat rolling stock in the rolling stand.

• für das Walzgerüst Istgrößen und Zielgrößen entgegennimmt, wobei die Istgrößen das flache Walzgut vor dem Walzen in dem Walzgerüst beschreiben und die Zielgrößen eine Sollkontur und/oder eine Sollplanheit des flachen Walzguts nach dem Walzen in dem Walzgerüst beschreiben,
• vor dem Walzen des flachen Walzguts in dem Walzgerüst unter Berücksichtigung der Istgrößen einen Zwischenwalzen-Einstellwert für eine axiale Verschiebung der Zwischenwalzen, einen anfänglichen Arbeitswalzen-Ansteuerwert für eine Arbeitswalzen-Biegeeinrichtung zum Biegen der Arbeitswalzen und einen anfänglichen Zwischenwalzen-Ansteuerwert für eine Zwischenwalzen-Biegeeinrichtung zum Biegen der Zwischenwalzen ermittelt, für die eine erwartete Kontur und/oder eine erwartete Planheit des flachen Walzguts der durch die Zielgrößen beschriebenen Sollkontur und/oder Sollplanheit so weit wie möglich angenähert werden,
• vor dem Walzen des flachen Walzguts in dem Walzgerüst die axiale Verschiebung der Zwischenwalzen entsprechend dem ermittelten Zwischenwalzen-Einstellwert einstellt,
• zumindest zu Beginn des Walzens des flachen Walzguts in dem Walzgerüst die Arbeitswalzen-Biegeeinrichtung entsprechend dem ermittelten anfänglichen Arbeitswalzen-Ansteuerwert und die Zwischenwalzen-Biegeeinrichtung entsprechend dem ermittelten anfänglichen Zwischenwalzen-Ansteuerwert einstellt.

The present invention is further based on a control program comprising machine code which can be processed by a control device for a rolling stand for rolling a flat metal rolling stock, said rolling stand comprising work rolls, backup rolls and intermediate rolls arranged between the work rolls and the backup rolls, wherein the processing of the machine code by the control device causes the control device

• receives actual and target values for the rolling stand, whereby the actual values describe the flat rolling stock before rolling in the rolling stand and the target values describe a target contour and/or a target flatness of the flat rolling stock after rolling in the rolling stand,
• before rolling the flat rolling stock in the rolling stand, taking into account the actual values, an intermediate roll setting value for an axial displacement of the intermediate rolls, an initial work roll control value for a work roll bending device for bending the work rolls and an initial intermediate roll control value for an intermediate roll bending device for bending the intermediate rolls are determined, for which an expected contour and/or an expected flatness of the flat rolling stock are approximated as closely as possible to the target contour and/or target flatness described by the target values,
• before rolling the flat rolling stock in the rolling stand, the axial displacement of the intermediate rolls is adjusted according to the determined intermediate roll setting value,
• at least at the beginning of rolling the flat rolling stock in the rolling stand, the work roll bending device is adjusted according to the determined initial work roll control value and the intermediate roll bending device is adjusted according to the determined initial intermediate roll control value.

The rolling stand has - like every rolling stand - two work rolls, which act directly and immediately (i.e. without other rolls arranged in between) on the flat rolled material. The rolling stand also has two backup rolls, which counteract the deflection of the work rolls. If there were no other rolls, the rolling stand would be a so-called four-high stand. In this case, in addition to the work rolls and the backup rolls, there are two intermediate rolls, which are arranged between the two work rolls and the two backup rolls. The rolling stand is therefore a so-called six-high stand.

The actual values that describe the flat rolled stock before rolling in the rolling mill can be, for example, the width, thickness, profile, contour, flatness, temperature, chemical composition, history and others.

The flat rolled stock is often made of steel, sometimes of aluminum. In rare cases it can also be another metal, such as copper. The flat rolled stock is usually a strip, in rare cases a heavy plate. The rolling is usually cold rolling. In exceptional cases, however, it can also be hot rolling.

The present invention is further based on a control device for a rolling stand for rolling a flat rolled metal stock, wherein the rolling stand has work rolls, backup rolls and intermediate rolls arranged between the work rolls and the backup rolls, wherein the control device is programmed with such a control program so that when the machine code of the control program is processed, it operates the rolling stand according to such an operating method.

• wobei das Walzgerüst Arbeitswalzen, Stützwalzen und zwischen den Arbeitswalzen und den Stützwalzen angeordnete Zwischenwalzen aufweist,
• wobei das Walzgerüst eine derartige Steuereinrichtung aufweist, von der das Walzgerüst im Betrieb gemäß einem derartigen Betriebsverfahren betrieben wird.

The present invention further relates to a rolling stand for rolling a flat rolled metal product,

• wherein the rolling stand comprises work rolls, backup rolls and intermediate rolls arranged between the work rolls and the backup rolls,
• wherein the rolling stand has such a control device, by which the rolling stand is operated in operation according to such an operating method.

State of the art

The items mentioned are generally known to experts.

In the paper " Numerical Analysis of Intermediate Roll Shifting-Induced Rigidity Characteristics of UCM Cold Rolling Mill" by Qing-Long Wang et al., published in steel research international 2018, article number 1700454 , a numerical analysis of the influence of the displacement of the intermediate rolls on the stiffness of such a rolling mill is carried out.

In the paper " Numerical and experimental analysis of strip cross-directional control and flatness prediction for UCM Cold Rolling Mill" by Qing-Long Wang et al., published in Journal of Manufacturing Processes 34 (2018), pages 637 to 649 , a numerical and experimental analysis is carried out, including the flatness prediction for such a rolling mill.

Summary of the invention

When rolling flat metal rolled stock, the resulting contour of the rolled stock and the resulting flatness of the rolled stock are important quality characteristics. Influencing the contour and flatness are - at least with relatively thin rolled stock - inseparably linked. Influencing the flatness and/or the contour is possible in various ways. For example, the contour and/or flatness of a six-high stand (i.e. a rolling stand in which, in addition to the work rolls and the backup rolls, there are also intermediate rolls arranged between the work rolls and the backup rolls, usually referred to as a 6-high stand) can be influenced by bending the work rolls and by bending the intermediate rolls. Furthermore, the contour and/or flatness can also be influenced by moving the intermediate rolls in opposite directions. This is particularly true for a so-called UCM (universal crown mill).

Good results can be achieved for many materials using a rolling mill of this type. However, with high-strength, wide materials and when a profile that is as box-shaped as possible is required, even such a rolling mill reaches its limits in the current state of the art.

The object of the present invention is to provide possibilities by means of which the range within which high-quality rolling of a flat rolled product is possible can be increased.

The object is achieved by an operating method for a rolling stand with the features of claim 1. Advantageous embodiments of the operating method are the subject of the dependent claims 2 to 5.

According to the invention, an operating method of the type mentioned at the outset is designed in that the control device determines the intermediate roll setting value, the initial work roll control value and the initial intermediate roll control value in such a way that the initial work roll control value and/or the initial intermediate roll control value have a respective predetermined minimum distance from their minimum and maximum values.

This ensures that a sufficiently large control reserve is available in the event of subsequent, in practice unavoidable disruptions to the rolling process when rolling the flat rolled stock (for example, if the temperature of the flat rolled stock changes and the material strength of the flat rolled stock changes as a result). This means that the disruptions can be compensated for by adjusting the work roll control value and/or the intermediate roll control value.

The minimum distance can be determined as required. If the possible setting range, i.e. the range from the respective minimum value to the respective maximum value, is standardized to 100% and the respective minimum value is assigned the value 0%, the minimum distance can be, for example, 20%, 25%, 30%, 35% and even higher, for example 40% or 45% or even 50%. Of course, other values are also possible. It is even possible to choose a different value for the minimum distance from the respective minimum value than for the minimum distance from the respective maximum value. For example, it can be specified that the initial work roll control value must be at least 30% away from its minimum value and at least 40% away from its maximum value. The sum of the two minimum distances can of course not exceed 100%. It is also possible to specify the minimum distances for the initial work roll control value differently than for the initial intermediate roll control value. For example, it may be required that the initial work roll control value is spaced from its minimum value by at least 30% and from its maximum value by at least 40%, the initial intermediate roll control value is at least 20% away from its minimum value and at least 50% away from its maximum value. The numerical values given are purely exemplary to illustrate the principle.

In practice, it may be advantageous to set the minimum distances in such a way that at least one of the two initial control values is not halfway between the limits of its respective setting range, but closer to its minimum or maximum value. This makes it possible to take into account in particular that the thermal crowning of the work rolls changes when the flat rolling stock is rolled and that this change must be counteracted by appropriate control of the work roll bending device and/or the intermediate roll bending device. If this counteraction causes the control value to shift more towards its maximum value, the associated initial control value should be set more towards its minimum value. In this case, for example, a minimum distance from the minimum value of 30% and a minimum distance from the maximum value of 50% may be required.

The intermediate rolls are usually designed the same and installed in the rolling stand inversely to one another. In a UCM, the intermediate rolls also have a cone on one side within their running surface. In such a rolling stand, the control device determines the intermediate roll control value preferably as the signed distance of the cone from the side edge of the flat rolled stock. This procedure is particularly easy to implement.

The target values for the target contour and/or the target flatness can include, for example, a C2 value and a C4 value of a Chebyshev polynomial. Describing the target contour or the target flatness in this way is particularly simple. It is often completely sufficient if the target values only include these two values.

• dass die Steuereinrichtung ein Modell implementiert, mittels dessen das Walzen des flachen Walzguts in dem Walzgerüst basierend auf mathematisch-physikalischen Gleichungen modelliert wird,
• dass in die mathematisch-physikalischen Gleichungen sowohl die Istgrößen und die Zielgrößen als auch der Zwischenwalzen-Einstellwert, der anfängliche Arbeitswalzen-Ansteuerwert und der anfängliche Zwischenwalzen-Ansteuerwert eingehen und
• dass die Steuereinrichtung den Zwischenwalzen-Einstellwert, den anfänglichen Arbeitswalzen-Ansteuerwert und den anfänglichen Zwischenwalzen-Ansteuerwert durch Lösen eines Optimierungsproblems ermittelt, in das das Modell eingeht.

The operating method is preferably designed in such a way

• that the control device implements a model by means of which the rolling of the flat rolling stock in the rolling stand is modelled based on mathematical-physical equations,
• that the mathematical-physical equations include both the actual and target values as well as the intermediate roll setting value, the initial work roll control value and the initial intermediate roll control value and
• that the control device determines the intermediate roll setting value, the initial work roll control value and the initial intermediate roll control value by solving an optimization problem into which the model is incorporated.

This approach is real-time capable and reliably delivers good results. The equations can be algebraic equations and differential equations.

In some cases, the rolling stand also has a cooling device to influence the contour and/or flatness of the flat rolled stock, by means of which sections of the work rolls can be individually cooled across the barrel width of the work rolls. In this case, the control device preferably also takes into account the individual cooling of the sections of the work rolls when determining the intermediate roll setting value, the initial work roll control value and the initial intermediate roll control value.

The object is further achieved by a control program with the features of claim 6. Advantageous embodiments of the control program are the subject of dependent claims 7 to 10.

According to the invention, the execution of the control program causes the control device to design an operating method of the type mentioned at the outset in that the control device determines the intermediate roll setting value, the initial work roll control value and the initial intermediate roll control value in such a way that the initial work roll control value and/or the initial intermediate roll control value have a respective predetermined minimum distance from their minimum and maximum values.

The advantages achieved thereby correspond to those of the operating method according to the invention.

The control program can also be designed in an advantageous manner. The advantageous designs of the control program and the advantages achieved thereby correspond to those of the operating method according to the invention.

The object is further achieved by a control device with the features of claim 11. According to the invention, the control device is programmed with a control program according to the invention, so that the control device operates the rolling stand according to an operating method according to the invention when executing the machine code of the control program.

The object is further achieved by a rolling stand for rolling a flat rolled metal product with the features of claim 12. According to the invention, in a rolling stand of the type mentioned at the outset, the control device of the rolling stand is designed as a control device according to the invention.

Short description of the drawings

FIG 1

ein Walzgerüst von der Seite,

FIG 2

ein Walzgerüst von oben,

FIG 3

einen Teil eines Walzgerüsts in Walzrichtung gesehen,

FIG 4

ein Ablaufdiagramm,

FIG 5

ein Tschebyscheff-Polynom 2. Grades,

FIG 6

ein Tschebyscheff-Polynom 4. Grades,

FIG 7

Wirksamkeiten von Biegeeinrichtungen,

FIG 8

ein weiteres Ablaufdiagramm und

FIG 9

ein Modell.

The above-described properties, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of an embodiment, which is explained in more detail in connection with the drawings, in which:

FIG 1

a rolling mill from the side,

FIG 2

a rolling mill from above,

FIG 3

a part of a rolling mill viewed in the rolling direction,

FIG 4

a flow chart,

FIG 5

a Chebyshev polynomial of degree 2,

FIG 6

a Chebyshev polynomial of degree 4,

FIG 7

Effectiveness of bending devices,

FIG 8

another flow chart and

FIG 9

a model.

Description of the embodiments

According to the FIGS 1 and 2 A rolling stock 2 is to be rolled in a rolling stand 1. The rolling stock 2 consists of metal, for example steel or aluminum. The rolling stock 2 is a flat rolling stock, i.e. a strip (normal case) or a heavy plate (exception). Rolling in the rolling stand 1 is usually cold rolling. In exceptional cases, however, it can also be hot rolling. The rolling stand 1 has working rolls 3, which form a roll gap between them in which the rolling stock 2 is rolled.

In the FIGS 1 and 2 only the working rolls 3 of the rolling stand 1 are shown, i.e. in FIG 1 the upper and lower working roll 3 and in FIG 2 only the upper working roll 3 (the lower working roll 3 is covered by the upper working roll 3). FIG 3 shows the rolling stock 2 and the rolls 3 to 5 of the rolling stand 1 arranged above the rolling stock 2. Below the rolling stock 2 there is the same sequence of rolls 3 to 5, even if this is in FIG 3 (and also in FIG 1 ) is not shown.

According to the presentation in FIG 3 In addition to the work rolls 3, the rolling stand 1 has backup rolls 4, i.e. an upper and a lower backup roll 4. The rolling stand 1 also has intermediate rolls 5. The intermediate rolls 5 are arranged between the work rolls 3 and the backup rolls 4. In concrete terms, the upper intermediate roll 5 is arranged between the upper work roll 3 and the upper backup roll 4, so that a sequence of three rolls 3 to 5 arranged one above the other results above the rolling stock 2. In an analogous manner, the lower intermediate roll 5 is arranged between the lower work roll 3 and the lower Support roller 4 is arranged so that a sequence of three rollers 3 to 5 arranged one above the other is also produced below the rolling stock 2.

The working rolls 3 and the support rolls 4 are, as in FIG 3 As can be seen, they are generally symmetrical and identical to one another. The intermediate rollers 5 are also generally identical to one another. However, they are often not symmetrical. For example, the intermediate rollers 5 can have a cone 7 on one side within their running surface 6. Such a grinding of the intermediate rollers 5 is often referred to as a one-sided intermediate roller grinding.

In the case of the asymmetrical design of the intermediate rolls 5, the intermediate rolls 5 are usually installed inversely to each other in the rolling stand 1. If, as in FIG 3 shown, the cone 7 of the upper intermediate roller 4 in the area of FIG 3 right side edge of the flat rolling stock 2, the cone 7 of the lower intermediate roll 4 is located in the area of FIG 3 left side edge of the flat rolled stock 2.

For the proper rolling of the flat rolling stock 2 in the rolling stand 1, in particular for the adjustment of profile, contour and flatness, the rolling stand 1 has according to FIG 1 various actuators 8 to 10, namely a sliding device 8, a work roll bending device 9 and an intermediate roll bending device 10.

The terms profile, contour and flatness are used in their usual meanings within the scope of the present invention. Specifically, the term "profile" is used as a purely scalar measure for the deviation of the thickness of the flat rolled stock 2 at a predetermined distance from the side edges of the flat rolled stock 2. In the prior art, the designation Cxx is common for the profile, where xx (in the unit "mm") stands for the predetermined distance from the side edges of the flat rolled stock 2. The term "contour" is used for the course of the thickness of the rolled stock 2 across the width of the rolled stock 2 minus the thickness of the rolled stock 2 in the middle of the rolled stock 2. The term flatness, in its literal sense, initially only includes visible distortions of the flat rolled stock 2. However, it is used as a synonym for the internal stresses prevailing in the flat rolled stock 2, regardless of whether these internal stresses lead to visible distortions of the flat rolled stock 2 or not.

By means of the sliding device 8, an axial displacement of the intermediate rollers 5 can be set. The axial displacement of the intermediate rollers 5 is generally in opposite directions to each other. If the upper intermediate roller 5 is thus displaced to the left by a certain amount, the lower intermediate roller 5 is displaced to the right by the same amount. The displacement of the intermediate rollers 5 is in FIG 3 by a double arrow within the upper Intermediate roll 5 is indicated. The extent of the axial displacement is determined by an intermediate roll setting value UCΔ. The intermediate roll setting value UCΔ can be set as shown in FIG 3 in particular as the signed distance of the cone 7 from the side edge of the flat rolling stock 2.

By means of the work roll bending device 9, a bending force can be exerted on the work rolls 3 to bend the work rolls 3. The bending of the work rolls 3 is in FIG 3 indicated by double arrows next to the upper work roll 3. The associated work roll control value for the work roll bending device 9 is designated with the reference symbol B1. In an analogous manner, a bending force for bending the intermediate rolls 5 can be exerted on the intermediate rolls 5 by means of the intermediate roll bending device 10. The bending of the intermediate rolls 5 is in FIG 3 indicated by double arrows next to the upper intermediate roll 5. The corresponding intermediate roll control value for the intermediate roll bending device 10 is designated by the reference symbol B2.

The rolling of the rolling stock 2 in the rolling stand 1 is controlled by a control device 11 of the rolling stand 1. The control device 11 is usually software-programmable, as indicated within the control device 11 by the designation "µP" for "microprocessor". The control device 11 is therefore programmed with a control program 12. The control program 12 includes machine code 13 that can be processed by the control device 11. The processing of the machine code 13 by the control device 11 causes the control device 11 to operate the rolling stand 1 according to an operating method that is explained in more detail below.

According to FIG 4 The control device 11 first receives actual variables I and target variables Z in a step S1.

The actual variables I describe the flat rolling stock 2 before rolling in the rolling stand 1. The actual variables I can include, for example, the geometric dimensions of the flat rolling stock 2, in particular its width and its thickness. The actual variables I can also include other geometric parameters of the flat rolling stock 2, for example its profile, its contour and its flatness. Furthermore, the actual variables I can also include other properties of the flat rolling stock 2, for example its temperature, its chemical composition and possibly also its history.

The target values Z can include values that describe a target contour K* of the flat rolling stock 2 after rolling in the rolling stand 1. For example, the target values Z for the target contour K* can include a C2 value k2 and a C4 value k4 of a Chebyshev polynomial, i.e. the coefficients for the Chebyshev functions of the 2nd and 4th degree. Alternatively or in addition to the description of the target contour K*, a description of the target flatness is also required. possible. The target flatness can, if necessary, be described analogously to the target contour K* by a corresponding C2 value and a corresponding C4 value.

auf, wobei x der normierte Ort in Breitenrichtung des flachen Walzguts 2 ist. Der Wert x = 0 steht also für die Mitte des flachen Walzguts 2, die Werte -1 und +1 für die linke und die rechte Seitenkante des flachen Walzguts 2. Die FIG 5 und 6 zeigen die entsprechenden Funktionen. Der C2-Wert k2 und der C4-Wert k4 sind die Koeffizienten, mit denen die Funktionen beispielsweise in die Beschreibung der Sollkontur K* eingehen: $$K*=k2\cdot C2+k4\cdot C4$$

Chebyshev polynomials and Chebyshev functions are well known to experts. Specifically, Chebyshev functions of degree 2 and 4 have the functional relationships $$C2\left(x\right)=\frac{1}{2}-x^2\mathrm{and}C4\left(x\right)=-\frac{1}{2}+4x^2-4x^4$$

where x is the standardized location in the width direction of the flat rolled stock 2. The value x = 0 stands for the center of the flat rolled stock 2, the values -1 and +1 for the left and right side edges of the flat rolled stock 2. The FIGS 5 and 6 show the corresponding functions. The C2 value k2 and the C4 value k4 are the coefficients with which the functions are included, for example, in the description of the target contour K*: $$K*=\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">k</figure-callout>}2\cdot \mathrm{<figure-callout\; id="2"\; label="C"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">C</figure-callout>}2+\mathrm{<figure-callout\; id="4"\; label="k"\; filenames="imgf0002.png,imgf0004.png"\; state="\{\{state\}\}">k</figure-callout>}4\cdot \mathrm{<figure-callout\; id="4"\; label="C"\; filenames="imgf0002.png,imgf0004.png"\; state="\{\{state\}\}">C</figure-callout>}4$$

In a step S2, the control device 11 determines the intermediate roll setting value UCΔ, an initial work roll control value B10 and an initial intermediate roll control value B20. The determination is carried out taking into account the actual variables I. It is carried out in such a way that an expected contour KE of the flat rolling stock 2 is approximated as closely as possible to the target contour K* - as described by the target variables Z. Alternatively or additionally, the determination can also be carried out in such a way that an expected flatness of the flat rolling stock 2 is approximated as closely as possible to the target flatness described by the target variables Z.

The determination of step S2 is, as far as defined so far, not yet unambiguous. Several combinations of the intermediate roll setting value UCΔ, the initial work roll control value B10 and the initial intermediate roll control value B20 are therefore possible, with each such combination achieving that the expected contour KE and/or the expected flatness of the flat rolling stock 2 is as close as possible to the target contour K* and/or target flatness described by the target variables Z. In order to clearly determine the intermediate roll setting value UCΔ, the initial work roll control value B10 and the initial intermediate roll control value B20, the control device 11 additionally takes into account the condition that the initial work roll control value B10 and/or the initial intermediate roll control value B20 have a respective predetermined minimum distance from their minimum values B1min, B2min and maximum values B1max, B2max when determining the values UCΔ, B10, B20. At least one of the two initial control values B10, B20 therefore meets the condition specified for it. In the simplest case, the determination is made in such a way that the initial work roll control value B10 and/or the initial intermediate roll control value B20 are as far away as possible from their minimum values B1min, B2min and maximum values B1ax, B1max.

In a step S3, the control device 11 sets the axial displacement of the intermediate rolls 5 according to the determined intermediate roll setting value UCΔ. The intermediate roll setting value UCΔ is thus specified to the shifting device 8. The axial displacement of the intermediate rolls 5 is no longer changed during the rolling of the flat rolling stock 2 in the rolling stand 1. Furthermore, in a step S4, the control device 11 sets the work roll control value B1 to the initial work roll control value B10 and the intermediate roll control value B2 to the initial intermediate roll control value B20.

The steps S1 to S4 are carried out by the control device 11 before the rolling of the flat rolling stock 2 in the rolling stand 1. From step S5 onwards, the rolling stock 2 is rolled in the rolling stand 1.

In step S5, the rolling stand 1 is controlled during operation, i.e. while the rolling stock 2 is being rolled in the rolling stand 1. In step S5, the control device 11 controls, among other things, the two bending devices 9, 10 according to their respective control values B1, B2. It therefore sets the bending devices 9, 10 according to their respective control values B1, B2. Due to step S4, the control values B1, B2 have the initial control values B10, B20 at least at the start of the rolling of the flat rolling stock 2 in the rolling stand 1, so that the control device 11 sets the bending devices 9, 10 according to their respective initial control values B10, B20 at least at the start of the rolling of the flat rolling stock 2 in the rolling stand 1.

The initial control values B10, B20 are initially retained until an actual value for the contour K can be recorded by means of a measuring device 14 arranged on the outlet side of the rolling stand 1. The control device 11 therefore checks in a step S6 whether such an actual value is available to it. If and as long as this is not the case, the control device 11 goes directly back to step S5. In this case, the control device 11 in particular keeps the control of the bending devices 9, 10 unchanged according to their initial control values B10, B20. However, as soon as an actual value for the contour K is available to the control device 11, the control device 11 goes to a step S7. In step S7, the control device 11 changes the control values B1, B2 with the aim of bringing the actual contour K given by the actual value closer to the target contour K*. The control device 11 then goes back to step S5. The renewed control of the bending devices 9, 10 during the renewed execution of step S5 is now carried out with the correspondingly changed control values B1, B2.

The repeated execution of steps S5, S6 and S7 is maintained until the flat rolling stock 2 has been completely rolled in the rolling stand 1.

Alternatively or in addition to recording the actual value for the contour K, it would also be possible to record an actual value for the flatness. In this case, when determining the control values B1, B2 in step S7, the aim of approximating the actual flatness given by the actual value to the target flatness would be taken into account alternatively or additionally.

The following is in connection with FIG 7 explains why, when determining the intermediate roll setting value UCΔ, the initial work roll control value B10 and the initial intermediate roll control value B20, the condition is taken into account that the initial work roll control value B10 and/or the initial intermediate roll control value B20 have a respective predetermined minimum distance from their minimum values B1min, B2min and maximum values B1max, B2max.

FIG 7 shows for several intermediate roll setting values UCΔ which C2 values k2 and C4 values k4 can be set by setting the work roll control value B1 and the intermediate roll control value B2. According to FIG 7 For each intermediate roll setting value UCΔ, a trapezoid 15 in the k2-k4 space results (exactly or at least approximately). The trapezoids 15 are in FIG 7 each supplemented by a small letter (a to e). The addition of the respective small letter serves only to linguistically distinguish the trapezoids 15 from one another. The small letters are only used below when reference is to be made very specifically to a very specific one of the trapezoids 15. If reference is made to the trapezoids 15 in general, the small letter is omitted. The procedure for the respective intermediate roll setting value UCΔ is completely analogous.

The edges of the trapezoids 15 correspond to the fact that one of the two control values B1, B2 is minimal or maximal and the other of the two control values B1, B2 runs through its possible value range. The corners of the respective trapezoid 15 correspond to the fact that both control values B1, B2 are minimal or maximal. It is clear that the position of the corresponding trapezoid 15 in the k2-k4 space can be adjusted by varying the intermediate roll setting value UCΔ.

If - for example - the target contour K* corresponds to a point 16 in the k2-k4 space, the target contour K* can be set with the intermediate roll setting value UCΔc. However, only a small control reserve is available for a reduction in the intermediate roll control value B2 as well as for an increase in the C2 value k2 as well as for a reduction in the C4 value k4. In an analogous manner, the target contour K* can also be set with the intermediate roll setting value UCΔe. Both for a However, only a small control reserve is available for increasing the intermediate roll control value B2 and for reducing the C2 value k2 and for increasing the C4 value k4. If, on the other hand, the intermediate roll setting value UCΔd is selected, not only the target contour K* can be set. Rather, a large control reserve is available for both reducing and increasing the intermediate roll control value B2 (and also the work roll control value B1). Correspondingly, a large control reserve is also available for both reducing and increasing the C2 value k2 and also for both reducing and increasing the C4 value k4.

As explained so far, it would be optimal to determine the initial work roll control value B10 and/or the initial intermediate roll control value B20 in such a way that at least one of the two values B10, B20 is as far away as possible from its minimum value B1min, B2min and maximum value B1max, B2max. However, a deviation from this rule can be justified by the fact that a later heating of the work rolls 3 occurs during the rolling of the rolling stock 2 in the rolling stand 1 and, correspondingly, a change in the contour of the work rolls 3 occurs.

In the event that at least one of the two values B10, B20 is to be as far away as possible from its minimum value B1min, B2min and maximum value B1max, B2max, a concrete determination of the intermediate roll setting value UCΔ can be made, for example, in such a way that a symmetrical convex geometric figure is defined in the k2-k4 space. A suitable symmetrical convex geometric figure is, for example, a rectangle (special case: square) whose edges are oriented parallel to the k2 or k4 axis and have a predetermined relationship to one another. Another suitable symmetrical convex geometric figure is, for example, an ellipse (special case: circle) whose main axes are oriented parallel to the k2 or k4 axis and have a predetermined relationship to one another. Then, as a rule, the desired intermediate roll setting value UCΔ is clearly determined by the condition that when the symmetrical convex geometric figure is centered relative to point 16, the area covered by the symmetrical convex geometric figure is maximized. An exception only arises in the very unlikely case that the target contour K* is specified so unfavorably that it can "just barely" be achieved. An example of such a case would be if the target contour K* could be described in k2-k4 space by point 16'. If the initial work roll control value B10 and/or the initial intermediate roll control value B20 should not be in the middle between their minimum values B1min, B2min and maximum values B1max, B2max, this procedure can be modified by using distorted figures.

FIG 8 shows schematically a possible procedure for determining the intermediate roll setting value UCΔ. FIG 8 corresponds to the result of an implementation of step S2 of FIG 4 .

According to FIG 8 In a step S11, the control device 11 first determines an average value B1M for the work roll control value B1. In the simplest case, the control device 11 forms the unweighted arithmetic mean of the minimum and maximum work roll control values B1min, B1max in step S11. In an analogous manner, the control device 11 determines an average value B2M for the intermediate roll control value B2 in a step S12.

In a step S13, the control device 11 sets the intermediate roll setting value UCΔ to an initial value. In a step S14, the control device 11 determines the associated initial control values B10, B20 for which the expected contour KE corresponds to the target contour K* as much as possible (alternatively or additionally: the expected flatness corresponds to the target flatness as much as possible).

In a step S15, the control device 11 checks whether the determined initial work roll control value B10 corresponds exactly or at least approximately to the associated average value B1M. If this is the case, the control device 11 proceeds to a step S16. If this is not the case, the control device 11 checks in a step S17 whether the determined initial intermediate roll control value B20 corresponds exactly or at least approximately to the associated average value B2M. If this is the case, the control device 11 also proceeds to step S16. If this is not the case, the control device 11 varies the intermediate roll setting value UCΔ in a step S18 and from there returns to step S14.

In step S16, the control device 11 checks whether the variation of the intermediate roll setting value UCΔ should be terminated. The check in step S16 can, for example, consist of an evaluation of the symmetrical convex geometric figure explained above. If the variation of the intermediate roll setting value UCΔ should not be terminated, the control device 11 goes to step S18. Otherwise, the procedure of FIG 8 The last determined values UCΔ, B10, B20 are then calculated in steps S3 and S4 of FIG 4 used.

To execute step S2 of FIG 4 or step S14 of FIG 8 the control device 11 can be operated as shown in FIG 9 implement a model 17. The rolling of the flat rolling stock 2 in the rolling stand 1 is modelled by means of the model 17. The model 17 is based on mathematical-physical equations. In particular, it can locally resolve two- or three-dimensionally, coupled differential equation systems The actual variables I and the target variables Z are included in the mathematical-physical equations. The intermediate roll setting value UCΔ, the initial work roll control value B10 and the initial intermediate roll control value B20 are also included in the mathematical-physical equations. Model 17 supplies the expected contour KE (alternatively or additionally the expected flatness) as an output variable. A corresponding model 17 as such is known to experts.

In the case of such a modeling, the control device 11 can, for example, determine the intermediate roll setting value UCΔ, the initial work roll control value B10 and the initial intermediate roll control value B20 in the context of step S2 or step S14 by solving an optimization problem in which the model 17 is included.

In some cases, the actuators 8 to 10 mentioned, i.e. the sliding device 8, the work roll bending device 9 and the intermediate roll bending device 10, are the only actuators by means of which the contour K and/or the flatness of the flat rolling stock 2 can be influenced. In other cases, the rolling stand 1 has actuators for influencing the contour K and/or the flatness of the flat rolling stock 2 as shown in FIG 2 additionally has a cooling device 18. In this case, sections of the work rolls 3 can be individually cooled by means of the cooling device 18 across a barrel width of the work rolls 3. If such a configuration is present, the control device 11 also takes into account an individual cooling B3 of the sections of the work rolls 3 when determining the intermediate roll setting value UCΔ, the initial work roll control value B10 and the initial intermediate roll control value B20. For example, the individual cooling B3 of the sections of the work rolls 3 can be carried out by the control device 11 as part of the execution of steps S2 or S14 of the FIG 4 or 8 be taken into account or can the individual cooling B3 of the sections of the work rolls 3 be an additional input variable of model 17 and be taken into account accordingly in model 17.

The present invention has many advantages. The influence of the specific intermediate roll setting value UCΔ has essentially no influence on the setting range of the two bending devices 9, 10. However, it has a significant influence on the resulting effect of the associated control values B1, B2 on the roll gap and thus on the contour K and the flatness of the rolled rolling stock 2. As a result, a very wide range of different flat rolling stock 2 can be rolled properly in the rolling stand 1 using the procedure according to the invention. This applies both to the strength of the flat rolling stock 2 and to its dimensions as well as to the requirements for profile, contour K and flatness. A costly and time-intensive exchange of the work rolls 3 for other work rolls 3 with an adapted crowning is not necessary in many cases. The individual cooling B3 of the work rolls 3 can be used. However, this is not usually necessary. This is an advantage in particular because the individual Cooling B3 of the work rolls 3 is, on the one hand, very slow and, on the other hand, has only a small adjustment range.

Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited to the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

List of reference symbols

1

Rolling mill

2

Rolled goods

3

Work rolls

4

Support rollers

5

Intermediate rolls

6

Tread

7

cone

8th

Sliding device

9, 10

Bending equipment

11

Control device

12

Tax program

13

Machine code

14

Measuring device

15

Trapeze

16, 16'

Points

17

Model

18

Cooling device

B1, B10

Work roll control values

B1min, B2min

Minimum values

B1max, B2max

Maximum values

B2, B20

Intermediate roller control values

B3

individual cooling

B1M, B2M

mean values

I

Actual sizes

K, KE, K*

Contours

k2

C2 value

k4

C4 value

S1 to S18

steps

UCΔ

Intermediate roll setting value

Z

Target values

Claims (12)

Operating method for a rolling stand (1) for rolling a flat rolled product (2) made of metal, wherein the rolling stand (1) has work rolls (3), backup rolls (4) and intermediate rolls (5) arranged between the work rolls (3) and the backup rolls (4), - wherein a control device (11) for the rolling stand (1) receives actual values (I) and target values (Z), - wherein the actual values (I) describe the flat rolling stock (2) before rolling in the rolling stand (1) and the target values (Z) describe a target contour (K*) and/or a target flatness of the flat rolling stock (2) after rolling in the rolling stand (1), - wherein the control device (11) determines, prior to rolling the flat rolling stock (2) in the rolling stand (1), taking into account the actual variables (I), an intermediate roll setting value (UCΔ) for an axial displacement of the intermediate rolls (5), an initial work roll control value (B10) for a work roll bending device (9) for bending the work rolls (3) and an initial intermediate roll control value (B20) for an intermediate roll bending device (10) for bending the intermediate rolls (5), for which an expected contour (KE) and/or an expected flatness of the flat rolling stock (2) are approximated as closely as possible to the target contour (K*) and/or target flatness described by the target variables (Z), - wherein the control device (11) adjusts the axial displacement of the intermediate rolls (5) in accordance with the determined intermediate roll setting value (UCΔ) before rolling the flat rolling stock (2) in the rolling stand (1), - wherein the control device (11) adjusts the work roll bending device (9) according to the determined initial work roll control value (B10) and the intermediate roll bending device (10) according to the determined initial intermediate roll control value (B20), at least at the beginning of the rolling of the flat rolling stock (2) in the rolling stand (1), characterized,
that the control device (11) determines the intermediate roll setting value (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20) such that the initial work roll control value (B10) and/or the initial intermediate roll control value (B20) have a respective predetermined minimum distance from their minimum and maximum values (B1min, B2min, B1max, B2max). Operating method according to claim 1,
characterized,
that the intermediate rolls (5) are of the same design and are installed inversely to one another in the rolling stand (1), that the intermediate rolls (5) have a cone (7) on one side within their running surface and that the control device (11) adjusts the intermediate roll setting value (UCΔ) is determined as the signed distance of the cone (7) from the side edge of the flat rolling stock (2). Operating method according to claim 1 or 2,
characterized,
that the target values (Z) for the target contour (K*) and/or for the target flatness include a C2 value (k2) and a C4 value (k4) of a Chebyshev polynomial. Operating method according to claim 1, 2 or 3,
characterized, - that the control device (11) implements a model (17) by means of which the rolling of the flat rolling stock (2) in the rolling stand (1) is modelled based on mathematical-physical equations, - that the mathematical-physical equations include both the actual variables (I) and the target variables (Z) as well as the intermediate roll setting value (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20) and - that the control device (11) determines the intermediate roll setting value (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20) by solving an optimization problem into which the model (17) is included. Operating method according to one of the above claims,
characterized,
that the rolling stand (1) additionally has a cooling device (18) for influencing the contour (K) and/or flatness of the flat rolling stock (2), by means of which sections of the work rolls (3) can be individually cooled across a barrel width of the work rolls (3), and that the control device (11) also takes into account the individual cooling of the sections of the work rolls (3) when determining the intermediate roll setting value (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20). Control program comprising machine code (13) which can be processed by a control device (11) for a rolling stand (1) having work rolls (3), backup rolls (4) and intermediate rolls (5) arranged between the work rolls (3) and the backup rolls (4) for rolling a flat rolled stock (2) made of metal, wherein the processing of the machine code (13) by the control device (11) causes the control device (11) - receives actual values (I) and target values (Z) for the rolling stand (1), whereby the actual values (I) describe the flat rolling stock (2) before rolling in the rolling stand (1) and the target values (Z) describe a target contour (K*) and/or a target flatness of the flat rolling stock (2) after rolling in the rolling stand (1), - before rolling the flat rolling stock (2) in the rolling stand (1), taking into account the actual variables (I), an intermediate roll setting value (UCΔ) for an axial displacement of the intermediate rolls (5), an initial work roll control value (B10) for a work roll bending device (9) for bending the work rolls (3) and an initial intermediate roll control value (B20) for an intermediate roll bending device (10) for bending the intermediate rolls (5) are determined, for which an expected contour (KE) and/or an expected flatness of the flat rolling stock (2) are approximated as closely as possible to the target contour (K*) and/or target flatness described by the target variables (Z), - before rolling the flat rolling stock (2) in the rolling stand (1), the axial displacement of the intermediate rolls (5) is adjusted in accordance with the determined intermediate roll setting value (UCΔ), - at least at the beginning of rolling the flat rolling stock (2) in the rolling stand (1), the work roll bending device (9) is adjusted in accordance with the determined initial work roll control value (B10) and the intermediate roll bending device (10) is adjusted in accordance with the determined initial intermediate roll control value (B20) and - the intermediate roll setting value (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20) are determined such that the initial work roll control value (B10) and/or the initial intermediate roll control value (B20) have a respective predetermined minimum distance from their minimum and maximum values (B1min, B2min, B1max, B2max). Control program according to claim 6,
characterized,
that the processing of the machine code (13) by the control device (11) causes the control device (11) in a rolling stand (1) whose intermediate rolls (5) are of identical design, are installed in the rolling stand (1) inversely to one another and have a cone (7) on one side within their running surface, to determine the intermediate roll setting value (UCΔ) as the signed distance of the cone (7) from the side edge of the flat rolling stock (2). Control program according to claim 6 or 7,
characterized,
that the target values (Z) for the target contour (K*) and/or for the target flatness include a C2 value (k2) and a C4 value (k4) of a Chebyshev polynomial. Control program according to claim 6, 7 or 8,
characterized,
that the processing of the machine code (13) by the control device (11) causes the control device (11) - a model (17) is implemented, by means of which the rolling of the flat rolling stock (2) in the rolling stand (1) is modelled based on mathematical-physical equations, wherein the mathematical-physical equations include both the actual variables (I) and the target variables (Z) as well as the intermediate roll setting value (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20), and - the intermediate roll setting value (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20) are determined by solving an optimization problem in which the model (17) is included. Control program according to one of claims 6 to 9,
characterized,
that the processing of the machine code (13) by the control device (11) causes the control device (11) in a rolling stand (1) which additionally has a cooling device (18) for influencing the contour (K) and/or flatness of the flat rolling stock (2), by means of which sections of the work rolls (3) can be individually cooled across a barrel width of the work rolls (3), also to take into account the individual cooling of the sections of the work rolls (3) when determining the intermediate roll setting value (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20). Control device for a rolling stand (1) for rolling a flat rolled stock (2) made of metal, wherein the rolling stand (1) has work rolls (3), backup rolls (4) and intermediate rolls (5) arranged between the work rolls (3) and the backup rolls (4), wherein the control device is programmed with a control program (12) according to one of claims 6 to 10, so that when the machine code (13) of the control program (12) is processed, it operates the rolling stand (1) according to an operating method according to one of claims 1 to 5. Rolling stand for rolling a flat rolled product (2) made of metal, - wherein the rolling stand comprises working rolls (3), support rolls (4) and intermediate rolls (5) arranged between the working rolls (3) and the support rolls (4), - wherein the rolling stand comprises a control device (11) according to claim 11, by which the rolling stand is operated in operation according to an operating method according to one of claims 1 to 5.

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