Method for determining manipulated variables of a roll stand, corresponding control programme, control device comprising such a control programme, and roll stand comprising such a control device

Abstract

The invention relates to a method for determining manipulated variables of a roll stand, and to a roll stand (1) for rolling a flat metal rolling stock (2), said roll stand comprising working rolls (3), back-up rolls, and intermediate rolls. A control device (11) for the roll stand (1) receives actual variables (I) and target variables (Z). The actual variables (I) describe the flat rolling stock (2) before being rolled in the roll stand (1), and the target variables (Z) describe a target contour and / or a target flatness of the flat rolling stock (2) after being rolled in the roll stand (1). Before the flat rolling stock (2) is rolled, and taking into account the actual variables (I), the control device (11) determines an intermediate roll setting value for an axial displacement of the intermediate rolls and initial control values for a bending device (9, 10) for bending the working rolls (3) and the intermediate rolls, for which an expected contour and / or an expected flatness of the flat rolling stock (2) is brought as close as possible to the target contour and / or target flatness described by the target variables (Z). The control device (11) sets the axial displacement of the intermediate rolls in accordance with the determined intermediate roll setting value (UCΔ) before the flat rolling stock (2) is rolled in the roll stand (1) and, at least when the rolling of the flat rolling stock (2) begins, sets the bending devices (9, 10) in accordance with the determined initial control values. The control device (11) determines the intermediate roll setting value (UCΔ) and the initial control values in such a way that the initial work roll control value and / or the initial intermediate roll control value have a predefined minimum difference from their minimum and maximum values.

Description

[0001] Description

[0002] Title of the invention

[0003] METHOD FOR DETERMINING CONTROLLED VARIABLES OF A ROLLING STAND, CORRESPONDING CONTROL PROGRAM, CONTROL DEVICE WITH SUCH A CONTROL PROGRAM AND ROLLING STAND WITH SUCH A

[0004] CONTROL DEVICE

[0005] field of technology

[0006] 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,

[0007] - whereby a control device for the rolling stand receives actual values ​​and target values,

[0008] - where the actual values ​​describe the flat rolling stock before rolling in the rolling stand and the target values ​​describe a desired contour and / or a desired flatness of the flat rolling stock after rolling in the rolling stand,

[0009] - wherein, prior to rolling the flat rolled stock in the rolling stand, the control device determines, 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 rolled stock are approximated as closely as possible to the target contour and / or target flatness described by the target variables,

[0010] - 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,

[0011] - 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 rolled stock in the rolling stand.

[0012] The present invention further relates to a control program comprising machine code which can be executed 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 execution of the machine code by the control device causes the control device

[0013] - receives actual values ​​and target values ​​for the rolling stand, whereby the actual values ​​describe the flat rolled stock before rolling in the rolling stand and the target values ​​describe a target contour and / or a target flatness of the flat rolled stock after rolling in the rolling stand, - before rolling the flat rolled stock in the rolling stand, taking the actual values ​​into account, determines 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 rolled stock are approximated as closely as possible to the target contour and / or target flatness described by the target values,

[0014] - 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 by means of a displacement device (8),

[0015] - at least at the start of rolling the flat rolled 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.

[0016] The rolling stand, like every rolling stand, has two work rolls that act directly and immediately (i.e., without any other rolls in between) on the flat rolled stock. The rolling stand also has two backup rolls that counteract the deflection of the work rolls. If there were no additional rolls, the rolling stand would be a so-called four-high stand. In this case, in addition to the work rolls and backup rolls, there are two intermediate rolls located between the two work rolls and the two backup rolls. The rolling stand is therefore a so-called six-high stand.

[0017] The actual values ​​that describe the flat rolled stock before rolling in the rolling stand can be, for example, the width, thickness, profile, contour, flatness, temperature, chemical composition, history and others.

[0018] The flat rolled stock is often made of steel, sometimes aluminum. In rare cases, it can also be another metal, such as copper. The flat rolled stock is usually strip, in rare cases heavy plate. Rolling is usually cold rolling. In exceptional cases, however, it can also be hot rolling.

[0019] The present invention further relates to a control device for a rolling stand for rolling a flat metal rolling stock, wherein the rolling stand comprises 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, upon execution of the machine code of the control program, it operates the rolling stand according to such an operating method. The present invention further relates to a rolling stand for rolling a flat metal rolling stock,

[0020] - wherein the rolling stand comprises work rolls, backup rolls and intermediate rolls arranged between the work rolls and the backup rolls, an intermediate roll bending device (10) for bending the intermediate rolls (5) and a work roll bending device (9) for bending the work rolls (3),

[0021] - wherein a sliding device (8) is arranged to carry out an axial displacement of the intermediate rollers (5),

[0022] - wherein the rolling stand has such a control device by which the rolling stand is operated in operation according to such an operating method.

[0023] State of the art

[0024] The items mentioned are generally known to experts.

[0025] 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 shifting of the intermediate rolls on the stiffness of such a rolling mill is carried out.

[0026] 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 of, among other things, the flatness prediction for such a rolling mill is carried out.

[0027] To improve the accuracy of the sheet thickness in the longitudinal direction of a sheet to be rolled, JPS6046804 A describes the use of a rolling mill equipped with a roll bending device between a work roll and an intermediate roll. The sheet is rolled by controlling a bending force during rolling.

[0028] Summary of the invention

[0029] When rolling flat metal 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 inextricably linked - at least with relatively thin rolled stock. Flatness and / or contour can be influenced in various ways. For example, the contour and / or flatness in a six-high stand (i.e., a rolling stand in which, in addition to the work rolls and backup rolls, there are also intermediate rolls arranged between the work rolls and backup rolls, commonly 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 counter-directional displacement of the intermediate rolls.This is especially true for a so-called UCM (universal crown mill).

[0030] Such a rolling stand can achieve good results for many materials. However, for high-strength, wide materials and where a profile as close to box-shaped as possible is required, even such a rolling stand reaches its limits in the current state of the art.

[0031] 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.

[0032] The object is achieved by an operating method for a rolling stand having the features of claim 1. Advantageous embodiments of the operating method are the subject of dependent claims 2 to 5.

[0033] 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.

[0034] This ensures that a sufficiently large control reserve is available for subsequent, in practice unavoidable, disruptions to the rolling process during the rolling of the flat rolled stock (for example, a change in the temperature of the flat rolled stock and the associated change in the material strength of the flat rolled stock). This allows the disruptions to be compensated for by adjusting the work roll control value and / or the intermediate roll control value.

[0035] 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% or even higher, such as 40% or 45% or even 50%. Other values ​​are of course 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 must of course not exceed 100%.Furthermore, it is possible to specify different minimum distances for the initial work roll control value than for the initial intermediate roll control value. For example, it can be required that the initial work roll control value be at least 30% apart from its minimum value and at least 40% apart from its maximum value, while the initial intermediate roll control value be at least 20% apart from its minimum value and at least 50% apart from its maximum value. The numerical values ​​mentioned are purely exemplary to illustrate the principle.

[0036] In practice, it may be advantageous to set the minimum distances such 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 during rolling of the flat rolled stock 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 corresponding initial control value should be set more towards its minimum value. In this case, for example, a minimum distance of 30% from the minimum value and a minimum distance of 50% from the maximum value may be required.

[0037] The intermediate rolls are typically identical in design and installed in the rolling stand at an inverse angle to each other. In a UCM, the intermediate rolls also have a cone on one side within their running surface. In such a rolling stand, the control system preferably determines the intermediate roll control value as the signed distance of the cone from the side edge of the flat rolled stock. This approach is particularly easy to implement.

[0038] The target variables for the desired contour and / or the desired flatness can, for example, include a C2 value and a C4 value of a Chebyshev polynomial. Describing the desired contour or the desired flatness in this way is particularly simple. Often, it is entirely sufficient for the target variables to include only these two values.

[0039] 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,

[0040] - that the mathematical-physical equations include both the actual variables and the target variables as well as the intermediate roll setting value, the initial work roll control value and the initial intermediate roll control value, and

[0041] - 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.

[0042] This approach is real-time capable and reliably delivers good results. The equations can be algebraic and differential equations, in particular.

[0043] In some cases, the rolling stand additionally has a cooling device to influence the contour and / or flatness of the flat rolled stock. This device allows individual cooling of sections of the work rolls across the barrel width of the work rolls. In this case, the control device preferably also takes into account the individual cooling of the work roll sections when determining the intermediate roll setting value, the initial work roll control value, and the initial intermediate roll control value.

[0044] The problem is further solved by a control program having the features of claim 6. Advantageous embodiments of the control program are the subject of dependent claims 7 to 10.

[0045] 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.

[0046] The advantages achieved thereby correspond to those of the operating method according to the invention.

[0047] The control program can also be advantageously configured. The advantageous configurations 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 having 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.

[0048] The object is further achieved by a rolling stand for rolling a flat rolled metal stock having 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.

[0049] Short description of the drawings

[0050] 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 conjunction with the drawings.

[0051] FIG 1 a rolling stand from the side,

[0052] FIG 2 a rolling stand from above,

[0053] FIG 3 shows part of a rolling stand viewed in the rolling direction,

[0054] FIG 4 a flow chart,

[0055] FIG 5 a Chebyshev polynomial of degree 2,

[0056] FIG 6 a Chebyshev polynomial of degree 4,

[0057] FIG 7 Effectiveness of bending devices,

[0058] FIG 8 another flow chart and

[0059] FIG 9 a model.

[0060] Description of the embodiments

[0061] According to 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 rolled stock, i.e., a strip (usually) or a heavy plate (exceptionally). Rolling in the rolling stand 1 is usually cold rolling. However, in exceptional cases, it can also be hot rolling. The rolling stand 1 has work rolls 3, which form a roll gap between them, in which the rolling stock 2 is rolled.

[0062] In FIGS. 1 and 2, only the work rolls 3 of the rolling stand 1 are shown, i.e., in FIG. 1, the upper and lower work rolls 3, and in FIG. 2, only the upper work roll 3 (the lower work roll 3 is obscured by the upper work 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, the same sequence of rolls 3 to 5 exists, even if this is not shown in FIG. 3 (or in FIG. 1).

[0063] According to the illustration in FIG 3, the rolling stand 1 has, in addition to the work rolls 3, 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. Specifically, the upper intermediate roll 5 is arranged between the upper work roll 3 and the upper backup roll 4, so that above the rolling stock 2 there is a sequence of three rolls 3 to 5 arranged one above the other. In a similar way, the lower intermediate roll 5 is arranged between the lower work roll 3 and the lower backup roll 4, so that below the rolling stock 2 there is also a sequence of three rolls 3 to 5 arranged one above the other.

[0064] The work rolls 3 and the backup rolls 4 are, as can be seen in FIG. 3, generally symmetrical and identical to one another. The intermediate rolls 5 are generally also identical to one another. However, they are often not symmetrical. For example, the intermediate rolls 5 may have a cone 7 on one side within their running surface 6. Such a grinding of the intermediate rolls 5 is often referred to as a one-sided intermediate roll grinding.

[0065] In the case of the asymmetrical design of the intermediate rolls 5, the intermediate rolls 5 are generally installed inversely to one another in the rolling stand 1. If, as shown in FIG. 3, the cone 7 of the upper intermediate roll 4 is located in the region of the right-hand side edge of the flat rolling stock 2 in FIG. 3, the cone 7 of the lower intermediate roll 4 is located in the region of the left-hand side edge of the flat rolling stock 2 in FIG. 3.

[0066] For the proper rolling of the flat rolling stock 2 in the rolling stand 1, in particular for adjusting profile, contour and flatness, the rolling stand 1 according to FIG. 1 has various actuators 8 to 10, namely a sliding device 8, a work roll bending device 9 and an intermediate roll bending device 10.

[0067] 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 in 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 customary 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 thickness of the rolled stock 2 across the width of the rolled stock 2, minus the thickness of the rolled stock 2 in the center of the rolled stock 2. The term "flatness," by its literal meaning, initially encompasses only 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.

[0068] By means of the sliding device 8, an axial displacement of the intermediate rolls 5 can be adjusted. The axial displacement of the intermediate rolls 5 is generally opposite to one another. Thus, if the upper intermediate roll 5 is shifted to the left by a certain amount, the lower intermediate roll 5 is shifted to the right by the same amount. The displacement of the intermediate rolls 5 is indicated in FIG. 3 by a double arrow within the upper intermediate roll 5. The extent of the axial displacement is determined by an intermediate roll setting value UCA. The intermediate roll setting value UCA can be determined, as shown in FIG. 3, in particular as the signed distance of the cone 7 from the side edge of the flat rolled stock 2.

[0069] 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 indicated in FIG. 3 by double arrows next to the upper work roll 3. The corresponding work roll control value for the work roll bending device 9 is designated by the reference symbol B1. In an analogous manner, a bending force can be exerted on the intermediate rolls 5 to bend the intermediate rolls 5 by means of the intermediate roll bending device 10. The bending of the intermediate rolls 5 is indicated in FIG. 3 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.

[0070] 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 typically software-programmable, as indicated within the control device 11 by the designation "pP" for "microprocessor." The control device 11 is therefore programmed with a control program 12. The control program 12 includes machine code 13, which 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, which is explained in more detail below.

[0071] According to FIG 4, the control device 11 first receives actual variables I and target variables Z in a step S1.

[0072] The actual variables I describe the flat rolled stock 2 prior to rolling in the rolling stand 1. The actual variables I can include, for example, the geometric dimensions of the flat rolled stock 2, in particular its width and thickness. The actual variables I can also include other geometric parameters of the flat rolled stock 2, for example, its profile, its contour, and its flatness. Furthermore, the actual variables I can also include other properties of the flat rolled stock 2, for example, its temperature, its chemical composition, and possibly also its history.

[0073] The target variables Z can include variables that describe a target contour K* of the flat rolled stock 2 after rolling in the rolling stand 1. For example, the target variables 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 degrees. Alternatively or in addition to describing the target contour K*, a description of the target flatness is also 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.

[0074] Chebyshev polynomials and Chebyshev functions are well known to experts. Specifically, the second and fourth degree Chebyshev functions have the functional relationships

[0075] C2(x) = ^- - x 2 and C4(x) = -^- + 4x 2 - 4x 4, where x is the standardized location in the width direction of the flat rolled stock 2. The value x = 0 thus represents the center of the flat rolled stock 2, and the values ​​-1 and +1 represent the left and right side edges of the flat rolled stock 2. Figures 5 and 6 show the corresponding functions. The C2 value k2 and the C4 value k4 are the coefficients with which the functions are incorporated, for example, into the description of the target contour K*:

[0076] K* = k2-C2 + k4-C4

[0077] In a step S2, the control device 11 determines the intermediate roll setting value UCA, 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 rolled 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 rolled stock 2 is approximated as closely as possible to the target flatness described by the target variables Z.

[0078] The determination of step S2, as defined so far, is not yet unambiguous. Therefore, several combinations of the intermediate roll setting value UCA, the initial work roll control value B10, and the initial intermediate roll control value B20 are possible, with each such combination achieving the expected contour KE and / or the expected flatness of the flat rolled stock 2 being approximated as closely as possible to the target contour K* and / or target flatness described by the target variables Z.In order to unambiguously determine the intermediate roll setting value UCA, the initial work roll control value B10, and the initial intermediate roll control value B20, the control device 11, when determining the aforementioned values ​​UCA, B10, B20, 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. At least one of the two initial control values ​​B10, B20 therefore fulfills the condition specified for it. In the simplest case, the determination is made such that the initial work roll control value B10 and / or the initial intermediate roll control value B20 are as far apart as possible from their minimum values ​​B1min, B2min and maximum values ​​B1ax, B1max.

[0079] In a step S3, the control device 11 adjusts the axial displacement of the intermediate rolls 5 according to the determined intermediate roll adjustment value UCA. The intermediate roll adjustment value UCA 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 rolled 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.

[0080] Steps S1 to S4 are executed 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.

[0081] In step S5, the rolling stand 1 is controlled during ongoing operation, i.e., while the rolled 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 rolled 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 rolled stock 2 in the rolling stand 1.

[0082] 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. If and as long as this is not the case, the control device 11 returns directly to step S5. In this case, the control device 11, in particular, maintains 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 proceeds 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 returns to step S5.The renewed control of the bending devices 9, 10 during the renewed execution of step S5 now takes place with the correspondingly changed control values ​​B1, B2.

[0083] 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.

[0084] Alternatively or in addition to recording the actual value for 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 goal of approximating the actual flatness, determined by the actual value, to the target flatness would be considered alternatively or additionally.

[0085] In the following, it is explained in connection with FIG 7 why, when determining the intermediate roll setting value UCA, 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.

[0086] FIG. 7 shows, for several intermediate roll setting values ​​UCA, 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 UCA, a trapezoid 15 results (exactly or at least approximately) in the k2-k4 space. The trapezoids 15 are each supplemented in FIG. 7 by a lowercase letter (a to e). The supplement by the respective lowercase letter serves merely to linguistically distinguish the trapezoids 15 from one another. The lowercase letters are used below only when a very specific reference is to be made to a particular trapezoid 15. Where reference is made to the trapezoids 15 in general, the lowercase letter is omitted. The procedure for the respective intermediate roll setting value UCA is completely analogous.

[0087] The edges of the trapezoids 15 correspond to the fact that one of the two control values

[0088] B1, B2 is at a minimum or maximum, 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 at a minimum or maximum. Obviously, by varying the intermediate roll setting value UCA, the position of the corresponding trapezoid 15 in the k2-k4 space can be adjusted.

[0089] If, for example, the target contour K* corresponds to a point 16 in the k2-k4 space, the target contour K* can indeed be set using the intermediate roll setting value UCAc. However, only a small control reserve is available for a reduction in the intermediate roll control value B2, an increase in the C2 value k2, or a reduction in the C4 value k4. In a similar way, the target contour K* can also be set using the intermediate roll setting value UCAe. However, only a small control reserve is available for an increase in the intermediate roll control value B2, a reduction in the C2 value k2, or an increase in the C4 value k4. If, on the other hand, the intermediate roll setting value UCAd is selected, not only the target contour K* can be set.Rather, a large control reserve is available for both a decrease and an increase in the intermediate roll control value B2 (and also the work roll control value B1). Correspondingly, a large control reserve is also available for both a decrease and an increase in the C2 value k2, as well as for both a decrease and an increase in the C4 value k4.

[0090] 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 such 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 may be justified by the subsequent heating of the work rolls 3 during the rolling of the rolled stock 2 in the rolling stand 1, and a corresponding change in the contour of the work rolls 3.

[0091] If at least one of the two values ​​B10, B20 is to be as far away as possible from its minimum value B1 min, B2min and maximum value B1max, B2max, the intermediate roll setting value UCA can be specifically determined, for example, by defining a symmetrical, convex geometric figure 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 major 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 UCA is uniquely 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 arises only in the very unlikely case that the target contour K* is specified so unfavorably that it can "only just" be achieved. An example of such a case would be if the target contour K* could be described in the k2-k4 space by point 16'. If the initial work roll control value B10 and / or the initial intermediate roll control value B20 are not intended to be halfway between their minimum values ​​B1 min, B2 min and maximum values ​​B1max, B2max, this procedure can be modified by using distorted figures.

[0092] FIG. 8 schematically shows a possible procedure for determining the intermediate roll setting value UCA. FIG. 8 corresponds to the result of an implementation of step S2 of FIG. 4.

[0093] 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, in step S11, the control device 11 calculates the unweighted arithmetic mean of the minimum and maximum work roll control values ​​B1min, B1max. In a similar manner, the control device 11 determines an average value B2M for the intermediate roll control value B2 in a step S12.

[0094] In a step S13, the control device 11 sets the intermediate roll adjustment value UCA 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 as closely as possible to the target contour K* (alternatively or additionally: the expected flatness corresponds as closely as possible to the target flatness).

[0095] 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 UCA in a step S18 and from there returns to step S14.

[0096] In step S16, the control device 11 checks whether the variation of the intermediate roll setting value UCA 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 UCA should not be terminated, the control device 11 proceeds to step S18. Otherwise, the procedure of FIG. 8 is completed. The most recently determined values ​​UCA, B10, B20 are then used in steps S3 and S4 of FIG. 4.

[0097] To execute step S2 of FIG. 4 or step S14 of FIG. 8, the control device 11 can implement a model 17 as shown in FIG. 9. The rolling of the flat rolling stock 2 in the rolling stand 1 is modeled using the model 17. The model 17 is based on mathematical-physical equations. In particular, it can comprise spatially two- or three-dimensionally resolved, interconnected differential equation systems. The actual variables I and the target variables Z are included in the mathematical-physical equations. The intermediate roll setting value UCA, the initial work roll control value B10, and the initial intermediate roll control value B20 are also included in the mathematical-physical equations. The 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 those skilled in the art.

[0098] In the case of such modeling, the control device 11 can, for example, determine the intermediate roll setting value UCA, the initial work roll control value B10 and the initial intermediate roll control value B20 in step S2 and step S14, respectively, by solving an optimization problem in which the model 17 is incorporated.

[0099] In some cases, the aforementioned actuators 8 to 10, i.e., the shifting 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 rolled stock 2 can be influenced. In other cases, the rolling stand 1 additionally has a cooling device 18 for influencing the contour K and / or the flatness of the flat rolled stock 2, as shown in FIG. 2. In this case, sections of the work rolls 3 can be individually cooled by means of the cooling device 18, viewed across the barrel width of the work rolls 3. If such a configuration is present, the control device 11 also takes into account individual cooling B3 of the sections of the work rolls 3 when determining the intermediate roll setting value UCA, 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 taken into account by the control device 11 as part of the execution of steps S2 or S14 of FIGS. 4 and 8, respectively, or the individual cooling B3 of the sections of the work rolls 3 can be an additional input variable of the model 17 and can be taken into account accordingly in the model 17.

[0100] The present invention has many advantages. For example, the influence of the specific intermediate roll setting value UCA remains essentially unaffected by the adjustment range of the two bending devices 9, 10. However, it does significantly influence 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 stock 2. As a result, the procedure according to the invention enables a very broad spectrum of very different flat rolled stock 2 to be properly rolled in the roll stand 1. This applies both to the strength of the flat rolled stock 2 and to its dimensions, as well as to the requirements regarding profile, contour K, and flatness. A cost- and time-intensive replacement of the work rolls 3 with other work rolls 3 with an adapted crown is not necessary in many cases. The individual cooling B3 of the work rolls 3 can, however, be used.However, this is generally not necessary. This is particularly advantageous because the individual cooling system B3 of the work rolls 3 is very slow and has a limited adjustment range.

[0101] Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

[0102] List of reference symbols

[0103] 1 rolling stand

[0104] 2 Rolled goods

[0105] 3 work rolls

[0106] 4 support rollers

[0107] 5 intermediate rollers

[0108] 6 Tread

[0109] 7 cone

[0110] 8 Sliding device

[0111] 9, 10 Bending devices

[0112] 11 Control device

[0113] 12 Control program

[0114] 13 Machine code

[0115] 14 Measuring device

[0116] 15 T rapeze

[0117] 16, 16' points

[0118] 17 Model

[0119] Cooling device

[0120] B1, B10 work roll control values

[0121] B1min, B2min minimum values

[0122] B1max, B2max maximum values

[0123] B2, B20 Intermediate roller control values

[0124] B3 individual cooling

[0125] B1M, B2M mean values

[0126] I Actual values

[0127] K, KE, K* Contours k2 C2 value k4 C4 value

[0128] S1 to S18 steps

[0129] UCA intermediate roll setting value

[0130] Z Target variables

Claims

Claims 1. 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 desired contour (K*) and / or a desired 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), an intermediate roll setting value (UCA) 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), taking into account the actual variables (I), 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 (UCA) before rolling the flat rolling stock (2) in the rolling stand (1), - wherein the control device (11), at least at the beginning of the rolling of the flat rolled stock (2) in the rolling stand (1), sets 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), characterized in that the control device (11) determines the intermediate roll setting value (UCA), 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).

2. Operating method according to claim 1, characterized in 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 (UCA) is determined as the signed distance of the cone (7) from the side edge of the flat rolling stock (2).

3. Operating method according to claim 1 or 2, characterized in that the target variables (Z) for the desired contour (K*) and / or for the desired flatness comprise a C2 value (k2) and a C4 value (k4) of a Chebyshev polynomial.

4. Operating method according to claim 1, 2 or 3, characterized in that - 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 values ​​(I) and the target values ​​(Z) as well as the intermediate roll setting value (UCA), 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 (UCA), 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.

5. Operating method according to one of the above claims, characterized in 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 cooling device, sections of the work rolls (3) can be individually cooled across a barrel width of the work rolls (3), and in 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 (UCA), the initial work roll control value (B10) and the initial intermediate roll control value (B20).

6. Control program comprising machine code (13) which can be processed by a control device (11) for a rolling stand (1) comprising 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), 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), - before rolling the flat rolling stock (2) in the rolling stand (1), taking into account the actual variables (I), an intermediate roll setting value (UCA) 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 according to the determined intermediate roll setting value (UCA) by means of a displacement device (8), - 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 (UCA), 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).

7. Control program according to claim 6, characterized in 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 the same design, are installed inversely to one another in the rolling stand (1) and have a cone (7) on one side within their running surface, to determine the intermediate roll setting value (UCA) as the signed distance of the cone (7) from the side edge of the flat rolling stock (2).

8. Control program according to claim 6 or 7, characterized in that the target variables (Z) for the desired contour (K*) and / or for the desired flatness comprise a C2 value (k2) and a C4 value (k4) of a Chebyshev polynomial.

9. 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 (UCA), the initial work roll control value (B10) and the initial intermediate roll control value (B20), and - the intermediate roll setting value (UCA), 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.

10. Control program according to one of claims 6 to 9, characterized in that the processing of the machine code (13) by the control device (11) causes the control device (11) in a rolling stand (1) which, for influencing the contour (K) and / or flatness of the flat rolling stock (2), additionally has a cooling device (18) 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 (UCA), the initial work roll control value (B10) and the initial intermediate roll control value (B20).

11. 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.

12. Rolling stand for rolling a flat rolled product (2) made of metal, - wherein the rolling stand comprises working rolls (3), backup rolls (4), intermediate rolls (5) arranged between the working rolls (3) and the backup rolls (4), an intermediate roll bending device (10) for bending the intermediate rolls (5) and a working roll bending device (9) for bending the working rolls (3), - wherein a sliding device (8) is arranged to carry out an axial displacement of the intermediate rolls (5), 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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