Method for determining control variables of a rolling mill stand, corresponding control program, control device with said control program, and rolling mill stand with said control device

Abstract

A method for determining control variables of a rolling mill stand. A rolling mill stand (1) for rolling a metallic flat stock (2) has work rolls (3), backup rolls, and intermediate rolls. A control device (11) of the rolling mill stand (1) receives actual variables (I) and target variables (Z). The actual variables (I) describe the flat stock (2) before rolling in the rolling mill stand (1), and the target variables (Z) describe a target profile and / or target flatness of the flat stock (2) after rolling in the rolling mill stand (1). The control device (11) determines, before rolling the flat rolled stock (2), intermediate roll setpoints (UCΔ) for the axial displacement of the intermediate rolls and initial control values ​​for the bending devices (9, 10) for bending the intermediate rolls, taking into account the actual variable (I), so that the predicted contour and / or predicted flatness of the work rolls (3) and the flat rolled stock (2) are as close as possible to the target contour and / or target flatness described by the target variable (Z). The control device (11) sets the axial displacement of the intermediate rolls according to the determined intermediate roll setpoints (UCΔ) before rolling the flat rolled stock (2) in the rolling mill stand (1), and sets the bending devices (9, 10) according to the determined initial control values ​​when starting to roll at least the flat rolled stock (2). The control device (11) determines the intermediate roll setpoints (UCΔ) and the initial control values ​​so that the initial work roll control value and / or the initial intermediate roll control value have a predetermined minimum distance from their minimum and maximum values, respectively.

Description

[Technical Field]

[0001] The present invention is based on a method of operating a rolling mill stand for rolling a metallic flat stock, the rolling mill stand having work rolls, backup rolls, and intermediate rolls arranged between the work rolls and the backup rolls, a control device of the rolling mill stand receiving the actual variables and the target variables; the actual variables describe the flat rolled material before rolling in the rolling mill stands and the target variables describe the target contour and / or target flatness of the flat rolled material after rolling in the rolling mill stands, - the control device determines, before rolling the flat rolled stock in the rolling mill stand, intermediate roll setting values ​​for the axial displacement of the intermediate rolls, initial work roll control values ​​for the work roll bending device for bending the work rolls, and initial intermediate roll control values ​​for the intermediate roll bending device for bending the intermediate rolls, taking into account the actual variables, so that the predicted contour and / or predicted flatness of the flat rolled stock comes as close as possible to the target contour and / or target flatness described by the target variables; The control device sets the axial displacement of the intermediate roll according to the determined intermediate roll setting value before rolling the flat rolled material in the rolling mill stand; The control device sets the work roll bending device according to the determined initial work roll control value and sets the intermediate roll bending device according to the determined initial intermediate roll control value at least when starting rolling of the flat rolled material in the rolling mill stand. [Background technology]

[0002] The present invention further provides a control program including machine code processable by a control device of a rolling mill stand for rolling a metallic flat rolled material, the rolling mill stand having work rolls, backup rolls, and intermediate rolls disposed between the work rolls and the backup rolls, wherein the processing of the machine code by the control device causes the control device to: receiving actual variables and target variables for a rolling mill stand, the actual variables describing a flat rolled stock before rolling in the rolling mill stand and the target variables describing a target contour and / or target flatness of the flat rolled stock after rolling in the rolling mill stand; - before rolling the flat rolled stock in the rolling mill stand, determining intermediate roll setting values ​​for the axial displacement of the intermediate rolls, initial work roll control values ​​for the work roll bending device for bending the work rolls, and initial intermediate roll control values ​​for the intermediate roll bending device for bending the intermediate rolls, taking into account the actual variables, so that the predicted contour and / or predicted flatness of the flat rolled stock comes as close as possible to the target contour and / or target flatness described by the target variables; - before rolling the flat rolled material in the rolling mill stand, the axial displacement of the intermediate roll is set by means of the slide device (8) in accordance with the determined intermediate roll setting value; - When starting rolling of flat rolled material at least in the rolling mill stand, setting the work roll bending device in accordance with the determined initial work roll control value and setting the intermediate roll bending device in accordance with the determined initial intermediate roll control value.

[0003] This rolling mill stand, like other rolling mill stands, has two work rolls that act directly and immediately on the flat rolled material (i.e., without any other rolls interposed between them). The rolling mill stand also has two backup rolls that counteract the deflection of the work rolls. If there are no further rolls, the rolling mill stand is a so-called four-high rolling mill. Here, in addition to the work rolls and backup rolls, there are two intermediate rolls arranged between the two work rolls and the two backup rolls. The rolling mill stand is therefore a so-called six-high rolling mill.

[0004] The real variables describing the flat rolled material before rolling in the rolling mill stands may be, for example, width, thickness, profile, contour, flatness, temperature, chemical composition, history, etc.

[0005] Flat-rolled stock is often made of steel, sometimes aluminum, and sometimes other metals such as copper. Flat-rolled stock is usually strip, but rarely plate. Rolling is usually cold-rolled, but can also be hot-rolled in exceptional cases.

[0006] The present invention further resides in a control system for a rolling mill stand for rolling metallic flat stock, the rolling mill stand having work rolls, backup rolls, and intermediate rolls disposed between the work rolls and the backup rolls, the control system being programmed with a control program such that, when machine code of the control program is processed, the control system operates the rolling mill stand in accordance with such an operating method.

[0007] The invention is further based on a rolling mill stand for rolling metallic flat stock, comprising: the rolling mill stand has work rolls, backup rolls, 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); the slide device (8) is configured to effect an axial displacement of the intermediate roll (5), The rolling mill stand has a control device for operating the rolling mill stand in accordance with such an operating method.

[0008] The above-mentioned subject matter is well known to those skilled in the art.

[0009] In Non-Patent Document 1, a numerical analysis is carried out on the influence of the displacement of the intermediate roll on the rigidity of such a rolling mill stand.

[0010] In Non-Patent Document 2, in particular, numerical analysis and experimental analysis are carried out regarding prediction of flatness of such rolling mill stands.

[0011] Patent Document 1 discloses the use of a rolling mill equipped with a roll bending device between work rolls and intermediate rolls in order to improve the thickness accuracy in the longitudinal direction of a metal plate to be rolled. The metal plate is rolled by controlling the bending force during rolling.

[0012] When rolling flat metallic stock, the resulting profile and flatness of the rolled stock are important quality characteristics. Influencing profile and flatness are inextricably linked, at least for relatively thin rolled stock. Flatness and / or profile can be influenced in various ways. For example, profile and / or flatness can be influenced by bending the work rolls and bending the intermediate rolls in a six-high rolling mill (i.e., a rolling mill stand that has work rolls and backup rolls as well as intermediate rolls positioned between the work rolls and backup rolls, commonly referred to as a six-high stand). Furthermore, profile and / or flatness can also be influenced by the opposite displacement of the intermediate rolls. This is particularly true for so-called universal crown mills (UCMs).

[0013] Although good results can be obtained with such rolling mill stands for many materials, they also reach their technical limits in the prior art for high-strength, wide materials and when a box-like profile is required as much as possible. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Japanese Patent Application Publication No. 6046804 [Non-patent literature]

[0015] [Non-Patent Document 1] Qing-Long Wang et al., “Numerical Analysis of Intermediate Roll Shifting-Induced Rigidity Characteristics of UCM Cold Rolling Mill”, steel research international 2018, article number 1700454 [Non-patent document 2] Qing-Long Wang et al., “Numerical and experimental analysis of strip cross-directional control and flatness prediction for UCM Cold Rolling Mill”, Journal of Manufacturing Processes 34 (2018), pp.637-649 Summary of the Invention [Problem to be solved by the invention]

[0016] The object of the present invention is to provide the possibility of expanding the range in which qualitatively high-quality rolling of flat rolled stock is possible. [Means for solving the problem]

[0017] This problem is solved by a method for operating a rolling mill stand having the features of claim 1. Advantageous embodiments of the method are the subject of dependent claims 2 to 5.

[0018] According to the invention, an operating method of the type mentioned at the outset is configured in that the control device determines intermediate roll setpoints, initial work roll control values ​​and initial intermediate roll control values ​​such that the initial work roll control values ​​and / or the initial intermediate roll control values ​​have a predetermined minimum distance from their minimum and maximum values, respectively.

[0019] This ensures that if disturbances in the rolling process, which are unavoidable in practice, occur later when rolling the flat stock (for example, if the temperature of the flat stock changes and, as a result, the material strength of the flat stock changes), a sufficiently large control reserve is available, which allows the work roll control values ​​and / or the intermediate roll control values ​​to be adjusted to correct the disturbances.

[0020] The minimum distance can be determined as needed. If the possible control range, i.e., the range from each minimum value to each maximum value, is normalized to 100% and each minimum value is assigned a value of 0%, the minimum distance can be, for example, 20%, 25%, 30%, 35%, or even higher, such as 40%, 45%, or even 50%. Obviously, other values ​​are also possible. It is also possible to select a minimum distance from each minimum value that differs from the minimum distance from each 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. Obviously, the sum of both minimum distances can be up to 100%. Furthermore, it is also possible to specify a minimum distance for the initial work roll control value that differs from that of the initial intermediate roll control value. For example, the initial work roll control value is required to be at least 30% away from its minimum value and at least 40% away from its maximum value, while the initial intermediate roll control value is required to be at least 20% away from its minimum value and at least 50% away from its maximum value. The numbers given are purely exemplary to illustrate the principles.

[0021] In practice, it may be advantageous to set the minimum distance so that at least one of the two initial control values ​​is closer to its minimum or maximum value, rather than to the center between the limits of the respective control range. This takes into account, in particular, that when rolling flat stock, the thermal crown of the work rolls changes, which must be countered by corresponding control of the work roll bending device and / or intermediate roll bending device. If this countermeasure results in a control value displacing more toward its maximum value, the associated initial control value should be set more toward its minimum value. In this case, for example, it may be necessary to set the minimum distance from the minimum value to 30% and the minimum distance from the maximum value to 50%.

[0022] The intermediate rolls generally have the same configuration and are mounted in the rolling mill stand in opposite directions. In the case of UCM, the intermediate rolls also have a cone on one side in their running plane. In this type of rolling mill stand, the control device preferably determines the intermediate roll control value as the signed distance of the cone from the side edge of the flat rolled material. This procedure is particularly easy to implement.

[0023] The target variables can include, for example, the C2 and C4 values ​​of the Chebyshev polynomial for the target contour and / or target flatness. It is particularly easy to describe the target contour or target flatness in this way. It is often entirely sufficient if the target variables include only these two values.

[0024] The method of operation preferably comprises: the control device implements a model used to model the rolling of flat rolled material in a rolling mill stand on the basis of mathematical-physical equations, the mathematical-physical equations include actual and target variables, intermediate roll setpoints, initial work roll control values, and initial intermediate roll control values; the controller is configured to determine the intermediate roll setpoints, the initial work roll control values, and the initial intermediate roll control values ​​by solving an optimization problem in which the model is included.

[0025] This procedure can be carried out in real time and reliably produces good results.The equations may in particular be algebraic and differential equations.

[0026] The rolling mill stand may additionally have cooling devices to affect the profile and / or flatness of the flat rolled stock, which may be used to individually cool sections of the work roll across the bale width of the work roll, in which case the controller preferably also takes the individual cooling of the work roll sections into account when determining the intermediate roll settings, initial work roll control values, and initial intermediate roll control values.

[0027] 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.

[0028] According to the invention, the processing of the control program results in the control device implementing an operating method of the type mentioned at the outset by determining intermediate roll setpoints, initial work roll control values ​​and initial intermediate roll control values ​​such that the initial work roll control values ​​and / or the initial intermediate roll control values ​​have a predetermined minimum distance from their minimum and maximum values, respectively.

[0029] The advantages obtained thereby correspond to the advantages of the operating method according to the invention.

[0030] The control program can also be designed in an advantageous manner.The advantageous embodiments of the control program and the advantages achieved thereby correspond to the advantages of the operating method according to the invention.

[0031] The problem is further solved 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, whereby the control device operates the rolling mill stand according to the operating method according to the invention when the machine code of the control program is processed.

[0032] The problem is further solved by a rolling mill stand for rolling metallic flat stock with the features of claim 12. According to the invention, in a rolling mill stand of the type mentioned at the beginning, the control device of the rolling mill stand is configured as a control device according to the invention.

[0033] The characteristics, features and advantages of the invention mentioned above, and how they are obtained, will become clearer and easier to understand in connection with the following description of an embodiment which is set out in more detail in conjunction with the drawings, in which: [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 is a side view of a rolling mill stand. [Figure 2] FIG. 1 is a top view of a rolling mill stand. [Figure 3] FIG. 2 is a view of a part of a rolling mill stand in the rolling direction. [Figure 4] FIG. [Figure 5] FIG. 1 is a diagram illustrating a second-order Chebyshev polynomial. [Figure 6] FIG. 1 is a diagram illustrating a fourth-order Chebyshev polynomial. [Figure 7] FIG. 10 illustrates the effectiveness of the bending device. [Figure 8] FIG. [Figure 9] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0035] According to Figures 1 and 2, the rolled material 2 is rolled in a rolling mill stand 1. The rolled material 2 consists of a metal, for example steel or aluminum. The rolled material 2 is a flat rolled material, i.e. strip (usually) or plate (exceptionally). Rolling in the rolling mill stand 1 is generally cold rolling; however, hot rolling is also possible exceptionally. The rolling mill stand 1 has work rolls 3, between which a roll gap is formed, in which the rolled material 2 is rolled.

[0036] 1 and 2 show only the work rolls 3 of the rolling mill stand 1; that is, the upper and lower work rolls 3 are shown in FIG. 1, and only the upper work roll 3 is shown in FIG. 2 (the lower work roll 3 is hidden by the upper work roll 3). FIG. 3 shows the rolled material 2 and rolls 3 to 5 of the rolling mill stand 1 arranged above the rolled material 2. Although not shown in FIG. 3 (and FIG. 1), rolls 3 to 5 are also present below the rolled material 2 in the same order.

[0037] As shown in FIG. 3, the rolling mill stand 1 has backup rolls 4, i.e., upper backup rolls 4 and lower backup rolls 4, in addition to work rolls 3. The rolling mill 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 a row of three rolls 3 to 5 lined up one above the other is formed above the rolled material 2. Similarly, the lower intermediate roll 5 is arranged between the lower work roll 3 and the lower backup roll 4, so that a row of three rolls 3 to 5 lined up one above the other is also formed below the rolled material 2.

[0038] As can be seen from FIG. 3, the work rolls 3 and backup rolls 4 are generally symmetrical and have the same configuration. Similarly, the intermediate rolls 5 are generally similar to one another. However, the intermediate rolls 5 themselves are often not symmetrical. For example, the intermediate roll 5 may have a cone 7 on one side of its running surface 6. Such grinding of the intermediate roll 5 is often referred to as one-sided intermediate roll grinding.

[0039] In the case of an asymmetrical construction of the intermediate rolls 5, the intermediate rolls 5 are generally mounted in opposite orientation relative to one another in the rolling mill stand 1. If, as shown in Figure 3, the conical section 7 of the upper intermediate roll 5 is located in the region of the right side edge of the flat rolled material 2 in Figure 3, the conical section 7 of the lower intermediate roll 5 is therefore located in the region of the left side edge of the flat rolled material 2 in Figure 3.

[0040] For proper rolling of the flat rolled material 2 in the rolling mill stand 1, in particular for setting the profile, contour and flatness, the rolling mill stand 1 according to FIG. 1 has various actuators 8-10, namely a slide device 8, a work roll bending device 9 and an intermediate roll bending device 10.

[0041] Within the scope of the present invention, the terms profile, contour and flatness are used in their usual sense. Specifically, the term "profile" is used as a purely scalar measure of the deviation in thickness of the flat rolled material 2 at a given distance from the side edge of the flat rolled material 2. In the prior art, the notation Cxx is generally used for the profile, where xx (unit: mm) represents a given distance from the side edge of the flat rolled material 2. The term "contour" is used for the progression of the thickness of the rolled material 2 across the width of the rolled material 2, minus the thickness of the rolled material 2 at the center of the rolled material 2. In its literal sense, the term flatness primarily includes only the visible distortion of the flat rolled material 2. However, it is used as a synonym for the internal stresses present in the flat rolled material 2, regardless of whether these internal stresses lead to visible distortion of the flat rolled material 2.

[0042] The axial displacement of the intermediate rolls 5 can be set by the slide device 8. The axial displacements of the intermediate rolls 5 are generally opposite to each other. That is, if the upper intermediate roll 5 is displaced to the left to a certain extent, the lower intermediate roll 5 is displaced to the right to the same extent. The displacement of the intermediate rolls 5 is indicated in FIG. 3 by a double arrow in the upper intermediate roll 5. The degree of axial displacement is determined by the intermediate roll setting value UCΔ. As shown in FIG. 3, the intermediate roll setting value UCΔ may be determined, in particular, as the signed distance of the cone section 7 from the side edge of the flat rolled material 2.

[0043] A bending force can be applied to the work rolls 3 by the work roll bending device 9 in order to bend the work rolls 3. The bending of the work rolls 3 is indicated by a double arrow next to the upper work roll 3 in FIG. 3. The associated work roll control value for the work roll bending device 9 is labeled with the reference character B1. Similarly, a bending force can be applied to the intermediate rolls 5 by the intermediate roll bending device 10 in order to bend the intermediate rolls 5. The bending of the intermediate rolls 5 is indicated by a double arrow next to the upper intermediate roll 5 in FIG. 3. The associated intermediate roll control value for the intermediate roll bending device 10 is labeled with the reference character B2.

[0044] The rolling of stock 2 in rolling mill stand 1 is controlled by a controller 11 of rolling mill stand 1. Controller 11 is typically software programmable, as indicated by "μP" within controller 11, which stands for "microprocessor." Controller 11 is therefore programmed with a control program 12. Control program 12 includes machine code 13 processable by controller 11. Processing of machine code 13 by controller 11 causes controller 11 to operate rolling mill stand 1 in accordance with an operating method that will be described in more detail below.

[0045] 4, the control device 11 first receives an actual variable I and a target variable Z in step S1.

[0046] The real variables I describe the flat rolled stock 2 before rolling in the rolling mill stand 1. The real variables I may, for example, include the geometric dimensions of the flat rolled stock 2, in particular its width and thickness. The real variables I may also include other geometric properties of the flat rolled stock 2, such as its profile, contour and flatness. Furthermore, the real variables I may also include other properties of the flat rolled stock 2, such as its temperature, its chemical composition and possibly its history.

[0047] The target variable Z is the target contour K of the flat rolled material 2 after rolling in the rolling mill stand 1. * For example, the target contour K * The target variables Z of the target contour K may include the C2 values ​​k2 and C4 values ​​k4 of the Chebyshev polynomials, i.e., the coefficients of the second and fourth order Chebyshev functions. * Alternatively or additionally to the description of the target flatness, a description of the target flatness is also possible. * Similarly, it can be described by the corresponding C2 value and the corresponding C4 value.

[0048] Chebyshev polynomials and Chebyshev functions are well known to those skilled in the art. Specifically, second and fourth order Chebyshev functions are expressed by the functional relationship

number

number

[0049] In step S2, the control device 11 determines the intermediate roll setpoint UCΔ, the initial work roll control value B10, and the initial intermediate roll control value B20. This determination is made taking into account the actual variable I. The determination is made by taking into account the actual variable I, the expected contour KE of the flat rolled material 2 into the target contour K, which is described by the target variable Z. * Alternatively or additionally, the determination can be made so that the expected flatness of the flat rolled stock 2 is as close as possible to the target flatness described by the target variable Z.

[0050] The determination of step S2 is not yet clear as defined so far. That is, a plurality of combinations of the intermediate roll setting value UCΔ, the initial work roll control value B10, and the initial intermediate roll control value B20 are possible, and each of these combinations determines the predicted contour KE and / or predicted flatness of the flat rolled material 2 according to the target contour K described by the target variable Z. * and / or the target flatness is brought as close as possible to the target flatness. In order to clearly determine the intermediate roll setpoint UCΔ, the initial work roll control value B10, and the initial intermediate roll control value B20, when determining the above-mentioned values ​​UCΔ, B10, and 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 predetermined minimum distance from their minimum values ​​B1min, B2min and maximum values ​​B1max, B2max, respectively. In other words, at least one of the two initial control values ​​B10, B20 satisfies the condition specified for that initial control value. In the simplest case, the initial work roll control value B10 and / or the initial intermediate roll control value B20 are specified so as to be as far as possible from their minimum values ​​B1min, B2min and maximum values ​​B1max, B2max.

[0051] In step S3, the control device 11 sets the axial displacement of the intermediate rolls 5 in accordance with the determined intermediate roll set value UCΔ. That is, the intermediate roll set value UCΔ is set for the slide device 8. The axial displacement of the intermediate rolls 5 is no longer changed during rolling of the flat rolled material 2 in the rolling mill stand 1. Furthermore, in step S4, the control device 11 sets the work roll control value B1 to an initial work roll control value B10, and sets the intermediate roll control value B2 to an initial intermediate roll control value B20.

[0052] Steps S1 to S4 are executed by the control device 11 before the flat rolled material 2 is rolled in the rolling mill stand 1. From step S5 onwards, the rolled material 2 is rolled in the rolling mill stand 1.

[0053] In step S5, control of the rolling mill stand 1 is performed during operation, i.e., while the rolled material 2 is being rolled in the rolling mill stand 1. In step S5, the control device 11 controls, in particular, the two bending devices 9, 10 according to their respective control values ​​B1, B2. That is, the control device 11 sets the bending devices 9, 10 according to their respective control values ​​B1, B2. Based on step S4, the control values ​​B1, B2 have initial control values ​​B10, B20 at least at the start of rolling the flat rolled material 2 in the rolling mill stand 1, so 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 rolling the flat rolled material 2 in the rolling mill stand 1.

[0054] The initial control values ​​B10, B20 are initially maintained until actual measurements of the contour K are detected by the measuring device 14 arranged on the outlet side of the rolling mill stand 1. The control device 11 therefore checks in step S6 whether such actual measurements are available to the control device 11. If and as long as they are not available, the control device 11 returns directly to step S5. In this case, the control device 11 keeps the control of the bending devices 9, 10, in particular, unchanged according to their initial control values ​​B10, B20. However, once actual measurements of the contour K become available to the control device 11, the control device 11 proceeds to step S7. In step S7, the control device 11 converts the actual contour K given by the actual measurements into the target contour K. * The control values ​​B1, B2 are changed with the goal of approaching the value B1, B2. The control device 11 then returns to step S5. The re-control of the bending devices 9, 10 when step S5 is executed again is now performed using the correspondingly changed control values ​​B1, B2.

[0055] The repeated execution of steps S5, S6 and S7 is maintained until the flat rolled stock 2 is completely rolled in the rolling mill stand 1.

[0056] Alternatively or additionally to detecting the actual measured value of the contour K, it is also possible to detect the actual measured value of the flatness. In this case, when determining the control values ​​B1 and B2 in step S7, alternatively or additionally, the goal of bringing the actual flatness given by the actual measured value closer to the target flatness is taken into account.

[0057] The reason why the condition that the initial work roll control value B10 and / or the initial intermediate roll control value B20 have a predetermined minimum distance from their minimum values ​​B1min, B2min and maximum values ​​B1max, B2max, respectively, is taken into consideration when determining the intermediate roll setpoint UCΔ, the initial work roll control value B10, and the initial intermediate roll control value B20 will be explained below with reference to FIG. 7.

[0058] FIG. 7 shows which C2 value k2 and which C4 value k4 can be set by setting the work roll control value B1 and the intermediate roll control value B2 for multiple intermediate roll setpoints UCΔ. According to FIG. 7, for each intermediate roll setpoint UCΔ, a respective (exact or at least approximate) trapezoid 15 is generated in the k2-k4 space. The trapezoids 15 are each supplemented with lowercase letters (a-e) in FIG. 7. The addition of each lowercase letter is merely used to linguistically distinguish the trapezoids 15 from one another. In the following, lowercase letters are used only when referring to very specific trapezoids 15. When referring to trapezoids 15 in general, the lowercase letters are omitted. The procedure is completely similar for each intermediate roll setpoint UCΔ.

[0059] The edges of the trapezoids 15 correspond to where one of the two control values ​​B1, B2 is a minimum or a maximum, and where the other of the two control values ​​B1, B2 passes through its possible value range. The corners of each trapezoid 15 correspond to where both control values ​​B1, B2 are a minimum or a maximum. Obviously, the position of the associated trapezoid 15 in k2-k4 space can be adjusted by changing the middle roll setting UCΔ.

[0060] For example, target contour K * corresponds to point 16 in the k2-k4 space, the target contour K * However, only a small control reserve is available for decreasing the intermediate roll control value B2, increasing the C2 value k2, and decreasing the C4 value k4. Similarly, when the intermediate roll setting value UCΔe is used, the target contour K * However, only a small control reserve is available for increasing the intermediate roll control value B2, decreasing the C2 value k2, and increasing the C4 value k4. In contrast, when the intermediate roll setpoint UCΔd is selected, the target contour K *Rather, a large control reserve is available for both decreasing and increasing the intermediate roll control value B2 (and the work roll control value B1). Correspondingly, a large control reserve is available for both decreasing and increasing the C2 value k2, as well as for both decreasing and increasing the C4 value k4.

[0061] As explained above, it is optimal to determine the initial work roll control value B10 and / or the initial intermediate roll control value B20 so that at least one of the two values ​​B10, B20 is as far away as possible from its minimum value B1min, B2min and its maximum value B1max, B2max. However, deviations from this rule may be justified by the fact that heating of the work rolls 3 occurs later during rolling of the strip 2 in the rolling mill stand 1, and the contours of the work rolls 3 change accordingly.

[0062] If at least one of the two values ​​B10, B20 is as far as possible from its minimum value B1min, B2min and maximum value B1max, B2max, the specific determination of the intermediate roll setting value UCΔ can be performed, for example, so that a symmetric convex geometric figure is defined in the k2-k4 space. A suitable symmetric convex geometric figure is, for example, a rectangle (special case: square) whose sides are oriented parallel to the k2 axis or the k4 axis and have a predetermined relationship to one another. A further suitable symmetric convex geometric figure is, for example, an ellipse (special case: circle) whose major axes are oriented parallel to the k2 axis or the k4 axis and have a predetermined relationship to one another. In the usual case, the desired intermediate roll setting value UCΔ is clearly determined by the condition that the area covered by the symmetric convex geometric figure is maximized when the symmetric convex geometric figure is centered on point 16. An exception occurs when the target contour K * is so poorly specified that it can be "barely" achieved. An example of such a case is the target contour K in k2-k4 space. *is described by point 16'. This procedure can be modified by using a modified diagram if the initial work roll control value B10 and / or the initial intermediate roll control value B20 must not be midway between their minimum values ​​B1min, B2min and their maximum values ​​B1max, B2max.

[0063] 8 shows a schematic diagram of a possible procedure for determining the intermediate roll setpoint UCΔ, the result of which corresponds to the implementation of step S2 of FIG.

[0064] 8, in step S11, the control device 11 first determines the average value B1M of the work roll control values ​​B1. In the simplest case, the control device 11 forms an unweighted arithmetic mean of the minimum and maximum work roll control values ​​B1min, B1max in step S11. Similarly, the control device 11 determines the average value B2M of the intermediate roll control values ​​B2 in step S12.

[0065] In step S13, the control device 11 sets the intermediate roll setting value UCΔ to an initial value. In step S14, the control device 11 adjusts the predicted contour KE to be as close as possible to the target contour K * (alternatively or additionally: the expected flatness corresponds as closely as possible to the target flatness)

[0066] In step S15, the control device 11 checks whether the determined initial work roll control value B10 exactly or at least approximately corresponds to the associated average value B1M. If so, the control device 11 proceeds to step S16. If not, the control device 11 checks in step S17 whether the determined initial intermediate roll control value B20 exactly or at least approximately corresponds to the associated average value B2M. If so, the control device 11 also proceeds to step S16. If not, the control device 11 changes the intermediate roll setpoint UCΔ in step S18 and returns to step S14.

[0067] In step S16, the control device 11 checks whether the change in the intermediate roll setpoint UCΔ should be terminated. The check in step S16 can be performed, for example, by evaluation of the symmetric convex geometric figure described above. If the change in the intermediate roll setpoint UCΔ should not be terminated, the control device 11 proceeds to step S18. Otherwise, the procedure of FIG. 8 ends. The last determined values ​​UCΔ, B10, B20 are used in steps S3 and S4 of FIG. 4.

[0068] To perform 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 model 17 is used to model the rolling of the flat strip 2 in the rolling mill stand 1. The model 17 is based on mathematical-physical equations. In particular, it can include a system of simultaneous differential equations locally decomposed into two or three dimensions. The mathematical-physical equations include an actual variable I and a target variable Z. The mathematical-physical equations further include an intermediate roll setting value UCΔ, an initial work roll control value B10, and an initial intermediate roll control value B20. The model 17 provides an expected contour KE (alternatively or additionally, an expected flatness) as an output variable. Such corresponding models 17 are known to those skilled in the art.

[0069] In the case of such modeling, the control device 11 can determine, for example, the intermediate roll setpoint UCΔ, the initial work roll control value B10, and the initial intermediate roll control value B20 by solving an optimization problem incorporating the model 17 within step S2 or step S14.

[0070] In many cases, the above-mentioned actuators 8-10, i.e., the slide device 8, the work roll bending device 9, and the intermediate roll bending device 10, are the only actuators capable of influencing the contour K and / or flatness of the flat rolled material 2. In other cases, the rolling mill stand 1 additionally includes a cooling device 18, as shown in FIG. 2, to influence the contour K and / or flatness of the flat rolled material 2. The cooling device 18 can be used to individually cool sections of the work roll 3, in this case across the bale width of the work roll 3. Given such a configuration, the control device 11 also takes into account the individual cooling B3 of the sections of the work roll 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 roll 3 can be considered by the control device 11 within the execution of step S2 or S14 of FIG. 4 or FIG. 8, or the individual cooling B3 of the sections of the work roll 3 can be an additional input variable of the model 17 and can be taken into account in the model 17 accordingly.

[0071] The present invention has many advantages. For example, the specific intermediate roll setting UCΔ has almost no effect on the control range of the two bending devices 9, 10, while the associated control values ​​B1, B2 have a significant effect on the resulting roll gap and, therefore, on the contour K and flatness of the rolled strip 2. As a result, the procedure according to the present invention allows a very wide range of different flat strips 2 to be properly rolled in the rolling mill stand 1. This applies to both the strength of the flat strip 2 and its dimensions, as well as the profile, contour K, and flatness requirements. The costly and time-consuming exchange of work rolls 3 with other work rolls 3 having matching projections is often unnecessary. Separate cooling B3 of the work rolls 3 can be utilized. However, this is usually unnecessary. This is particularly advantageous because separate cooling B3 of the work rolls 3 is very slow and, on the other hand, has only a small control range.

[0072] Although the present invention has been shown and described in more detail by means of preferred embodiments, the invention is not limited to the disclosed embodiments, and those skilled in the art can derive other variants therefrom without departing from the scope of protection of the present invention. [Explanation of symbols]

[0073] 1 rolling mill stand 2. Rolled materials 3 Work rolls 4. Backup Role 5. Intermediate roll 6 Running surface 7 Cone section 8 Slide device 9, 10 Bending device 11 Control device 12 Control Program 13 Machine Code 14 Measuring equipment 15 Trapezoid 16, 16' point 17 models 18 Cooling device B1, B10 Work roll control values B1min, B2min minimum value B1max, B2max maximum value B2, B20 Intermediate roll control value B3 Individual cooling B1M, B2M average value I Real variable K.E., K. * Contour k2 C2 value k4 C4 value S1~S18 steps UCΔ Intermediate roll setting value Z goal variable

Claims

1. A method of operating a rolling mill stand (1) for rolling a metallic flat stock (2), the rolling mill stand (1) having work rolls (3), backup rolls (4), and intermediate rolls (5) disposed between the work rolls (3) and the backup rolls (4), the control device (11) of said rolling mill stand (1) receives the actual variables (I) and the target variables (Z), The actual variables (I) describe the flat rolled material (2) before rolling in the rolling mill stand (1), and the target variables (Z) describe the target contour (K) of the flat rolled material (2) after rolling in the rolling mill stand (1). ＊ ) and / or describe the target flatness, - before rolling the flat rolled material (2) in the rolling mill stand (1), the control device (11) takes into account the actual variables (I) and determines intermediate roll setting values ​​(UCΔ) for the axial displacement of the intermediate rolls (5), initial work roll control values ​​(B10) for the work roll bending device (9) for bending the work rolls (3), and initial intermediate roll control values ​​(B20) for the intermediate roll bending device (10) for bending the intermediate rolls (5), so that the expected profile (KE) and / or expected flatness of the flat rolled material (2) is determined according to the target profile (K) described by the target variables (Z); ＊ ) and / or as close as possible to the target flatness, - the control device (11) sets the axial displacement of the intermediate rolls (5) according to the determined intermediate roll setting value (UCΔ) before rolling the flat rolled material (2) in the rolling mill stand (1); - an operating method in which the control device (11) sets the work roll bending device (9) according to the determined initial work roll control value (B10) and sets the intermediate roll bending device (10) according to the determined initial intermediate roll control value (B20) at least when starting rolling of the flat rolled material (2) in the rolling mill stand (1), an operating method characterized in that the control device (11) determines the intermediate roll set value (UCΔ), the initial work roll control value (B10), and the initial intermediate roll control value (B20) so that the initial work roll control value (B10) and / or the initial intermediate roll control value (B20) have predetermined minimum distances from minimum and maximum values ​​(B1min, B2min, B1max, B2max) of the initial work roll control value (B10) and / or the initial intermediate roll control value (B20), respectively.

2. 2. The method according to claim 1, characterized in that the intermediate rolls (5) have the same configuration and are mounted in the rolling mill stand (1) in opposite directions relative to one another, the intermediate rolls (5) have a conical section (7) on one side in the running surface of the intermediate roll, and the control device (11) determines the intermediate roll setting value (UCΔ) as the signed distance of the conical section from the side edge of the flat rolled material (2).

3. The target variable (Z) is ＊ 3. The method according to claim 1, further comprising: determining a C2 value (k2) and a C4 value (k4) of a Chebyshev polynomial for the target flatness.

4. the control device (11) implements a model (17) used to model the rolling of the flat rolled material (2) in the rolling mill stand (1) based on mathematical-physical equations; the mathematical-physical equation includes the actual variable (I) and the target variable (Z), the intermediate roll setpoint (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20); and 4. A method according to claim 1, wherein the control device (11) is configured to determine the intermediate roll setpoint (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20) by solving an optimization problem involving the model (17).

5. 5. The method according to claim 1, wherein the rolling mill stand (1) additionally comprises cooling devices (18) for influencing the profile (K) and / or flatness of the flat rolled material (2), the cooling devices being capable of cooling sections of the work rolls (3) individually across a bale width of the work rolls (3), and the control device (11) also takes the individual cooling of the sections of the work rolls (3) into account when determining the intermediate roll setting value (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20).

6. 1. A control program including machine code (13) processable by a control device (11) of a rolling mill stand (1) for rolling a metallic flat rolled stock (2), the rolling mill stand having work rolls (3), backup rolls (4), and intermediate rolls (5) disposed between the work rolls (3) and the backup rolls (4), wherein the control device (11) performs the following by processing the machine code (13): - receiving actual variables (I) and target variables (Z) for said rolling mill stand (1), said actual variables (I) describing the flat rolled material (2) before rolling in said rolling mill stand (1) and said target variables (Z) describing the target contour (K) of the flat rolled material (2) after rolling in said rolling mill stand (1); ＊ ) and / or describe the target flatness, Before rolling the flat rolled material (2) in the rolling mill stand (1), intermediate roll setting values ​​(UCΔ) for the axial displacement of the intermediate rolls (5), initial work roll control values ​​(B10) for the work roll bending device (9) for bending the work rolls (3), and initial intermediate roll control values ​​(B20) for the intermediate roll bending device (10) for bending the intermediate rolls (5) are determined taking into account the actual variables (I), and the expected profile (KE) and / or expected flatness of the flat rolled material (2) is determined by the target profile (K) described by the target variables (Z). ＊ ) and / or the target flatness is approached as closely as possible, - before rolling the flat rolled material (2) in the rolling mill stand (1), setting the axial displacement of the intermediate rolls (5) by means of a slide device (8) according to the determined intermediate roll setting value (UCΔ); - setting the work roll bending device (9) according to the determined initial work roll control values ​​(B10) and the intermediate roll bending device (10) according to the determined initial intermediate roll control values ​​(B20) at least when starting rolling of the flat rolled material (2) in the rolling mill stand (1); a control program for determining the intermediate roll set value (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20) so that the initial work roll control value (B10) and / or the initial intermediate roll control value (B20) have a predetermined minimum distance from the minimum and maximum values ​​(B1min, B2min, B1max, B2max) of the initial work roll control value (B10) and / or the initial intermediate roll control value (B20), respectively.

7. 7. The control program according to claim 6, characterized in that, by processing the machine code (13) by the control device (11), the control device (11) determines the intermediate roll setting value (UCΔ) as the signed distance of the conical portion (7) from the side edge of the flat rolled material (2) in the rolling mill stand (1) in which the intermediate rolls (5) have the same configuration, are mounted opposite to each other in the rolling mill stand (1), and have a conical portion (7) on one side in the running surface of the intermediate rolls.

8. The target variable (Z) is ＊ 8. The control program according to claim 6, further comprising: a C2 value (k2) and a C4 value (k4) of a Chebyshev polynomial for the target flatness.

9. Processing of the machine code (13) by the control device (11) causes the control device (11) to: - implementing a model (17) used to model the rolling of the flat rolled stock (2) in the rolling mill stand (1) on the basis of mathematical-physical equations, the mathematical-physical equations including the actual variables (I) and the target variables (Z), the intermediate roll settings (UCΔ), the initial work roll control values ​​(B10) and the initial intermediate roll control values ​​(B20); A control program according to any one of claims 6 to 8, characterized in that it is configured to determine the intermediate roll setpoint (UCΔ), the initial work roll control value (B10) and the initial intermediate roll control value (B20) by solving an optimization problem involving the model (17).

10. 10. The control program according to claim 6, wherein the processing of the machine code by the control device (11) causes the control device (11) 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) in the rolling mill stand (1), which additionally comprises cooling devices (18) for influencing the contour (K) and / or flatness of the flat rolled material (2) and which are capable of cooling sections of the work rolls (3) individually across a bale width of the work rolls (3).

11. 11. A control device for a rolling mill stand (1) for rolling a flat metal rolled stock (2), the rolling mill stand (1) having work rolls (3), backup rolls (4), and intermediate rolls (5) arranged between the work rolls (3) and the backup rolls (4), the control device being programmed with a control program (12) according to any one of claims 6 to 10, and the control device, when processing a machine code (13) of the control program (12), causing the rolling mill stand (1) to operate in accordance with the operating method according to any one of claims 1 to 5.

12. A rolling mill stand for rolling a flat metal stock (2), comprising: the rolling mill stand comprises work rolls (3), backup rolls (4), intermediate rolls (5) arranged between the work rolls (3) and the backup rolls (4), an intermediate roll bending device (10) for bending the intermediate rolls (5), and a work roll bending device (9) for bending the work rolls; - a sliding device (8) configured to effect an axial displacement of said intermediate roll (5); The rolling mill stand has a control device (11) according to claim 11, by means of which the rolling mill stand is operated according to the operating method according to any one of claims 1 to 5.

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