Method for ascertaining control variable of rolling stand, corresponding control program, control device having such control program, and rolling stand having such control device

Abstract

The invention relates to a method for ascertaining a control variable of a rolling stand. The invention relates to a rolling stand (1) for rolling flat rolled stock (2) made of metal, comprising a working roll (3), a supporting roll (4) and an intermediate roll (5). A control device (11) for a rolling stand (1) receives an actual variable (I) and a target variable (Z). The actual variable (I) describes a flat rolled stock (2) before rolling in the rolling stand (1), and the target variable (Z) describes a target profile and / or a target straightness of the flat rolled stock (2) after rolling in the rolling stand (1). The control device (11) ascertains, before rolling the flat rolled stock (2), an intermediate roll control value for an axial movement of the intermediate roll (5) and an initial control value for the bending device (9, 10) for bending the working roll (3) and the intermediate roll, taking into account an actual variable (I), for these values, an expected contour and / or an expected straightness of the flat rolled stock (2) is made as close as possible to a target contour and / or a target straightness described by a target variable (Z). The control device (11) adjusts the axial movement of the intermediate roll as a function of the determined intermediate roll adjustment value (UC delta) before rolling the flat rolled stock (2) in the rolling stand (1), and adjusts the bending device (9, 10) as a function of the determined initial control value at least at the beginning of rolling of the flat rolled stock (2). The control device (11) ascertains an intermediate roll control value (UC delta) and an initial control value in such a way that the initial working roll control value and / or the initial intermediate roll control value have a respective predetermined minimum distance from the minimum value and the maximum value thereof.

Description

Technical Field

[0001] The invention relates to an operating method for a rolling stand for rolling flat rolling stock made of metal, wherein the rolling stand has working rolls, support rolls and intermediate rolls arranged between the working rolls and the support rolls.

[0002] - wherein a control device for the rolling stand receives actual variables and target variables,

[0003] - the actual variables describe the flat rolled product before rolling in the rolling stand, and the target variables describe the desired contour and / or desired flatness of the flat rolled product after rolling in the rolling stand,

[0004] - wherein before the flat rolled product is rolled in the rolling stand, the control device determines, taking into account actual variables, intermediate roll adjustment values ​​for the axial displacement of the intermediate rolls, initial working roll control values ​​for a working roll bending device for bending the working rolls, and initial intermediate roll control values ​​for an intermediate roll bending device for bending the intermediate rolls, for which values ​​an expected contour and / or an expected flatness of the flat rolled product comes as close as possible to the setpoint contour and / or setpoint flatness described by the target variables,

[0005] - the control device regulates the axial displacement of the intermediate rollers as a function of the determined intermediate roller adjustment values ​​before the flat rolling stock is rolled in the rolling stand,

[0006] - wherein the control device regulates the working roll bending device according to the determined initial working roll control values ​​and regulates the intermediate roll bending device according to the determined initial intermediate roll control values ​​at least at the beginning of rolling of the flat rolling stock in the rolling stand.

[0007] The present invention also relates to a control program, which includes a machine code, which can be executed by a control device for a rolling stand having working rolls, backup rolls and intermediate rolls arranged between the working rolls and the backup rolls, the rolling stand being used for rolling a flat rolled product made of metal, wherein the execution of the machine code by the control device causes the control device to

[0008] - receiving actual variables and target variables for a rolling stand, wherein the actual variables describe the flat rolled product before rolling in the rolling stand and the target variables describe a desired contour and / or a desired flatness of the flat rolled product after rolling in the rolling stand,

[0009] - before rolling the flat rolled product in the rolling stand, determining, taking into account actual variables, intermediate roll adjustment values ​​for the axial displacement of the intermediate rolls, initial working roll control values ​​for a working roll bending device for bending the working rolls, and initial intermediate roll control values ​​for an intermediate roll bending device for bending the intermediate rolls, for which values ​​an expected contour and / or an expected flatness of the flat rolled product is as close as possible to a setpoint contour and / or a setpoint flatness described by the target variables,

[0010] - before the flat rolling stock is rolled in the rolling stand, the axial displacement of the intermediate roll is adjusted by means of a displacement device (8) according to the determined intermediate roll adjustment value,

[0011] At least at the beginning of rolling of the flat rolling stock in the rolling stand, the working roll bending device is adjusted as a function of the determined initial working roll control values ​​and the intermediate roll bending device is adjusted as a function of the determined initial intermediate roll control values.

[0012] The rolling stand has, like every other rolling stand, two working rolls which act directly and diametrically (i.e. without further rolls arranged between them) on the flat rolled stock. The rolling stand also has two support rolls which counteract the bending of the working rolls. If no further rolls are present, the rolling stand is a so-called four-roll stand. In addition to the working rolls and the support rolls, there are two intermediate rolls which are arranged between the two working rolls and the two support rolls. The rolling stand is thus a so-called six-roll stand.

[0013] Actual variables describing the flat rolling stock before rolling in the rolling stand may be, for example, width, thickness, cross-section, contour, straightness, temperature, chemical composition, origin or the like.

[0014] Flat rolled products often consist of steel, sometimes of aluminum. In rare cases, they can also consist of other metals, such as copper. Flat rolled products are mostly strips, in rare cases thick plates. The rolling is usually cold rolling. However, in special cases, it can also be hot rolling.

[0015] The invention further relates to a control device for a rolling stand for rolling flat rolled products made of metal, wherein the rolling stand has working rolls, backup rolls and intermediate rolls arranged between the working rolls and the backup rolls, wherein the control device is programmed with such a control program that the control device operates the rolling stand according to such an operating method when executing a machine code of the control program.

[0016] The invention also relates to a rolling stand for rolling flat rolled stock made of metal.

[0017] - wherein the rolling stand comprises working rolls, support rolls and intermediate rolls arranged between the working rolls and the support rolls, 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),

[0018] - The displacement device (8) is designed in such a way as to carry out an axial displacement of the intermediate roller (5).

[0019] The rolling stand has a control device by which the rolling stand is operated during operation according to such an operating method. Background Art

[0020] The above-mentioned subject matter is well known to those skilled in the art.

[0021] In the professional paper "Numerical Analysis of Intermediate Roll Shifting-Induced Rigidity Characteristics of UCM Cold Rolling Mill" by Qing-Long Wang et al., published in Steelresearchinternational in 2018 with paper number 1700454, a numerical analysis was performed on the effect of the movement of the intermediate rolls on the rigidity of such a rolling stand.

[0022] In the professional 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 Process 34 (2018), pages 637 to 649, a numerical and experimental analysis was also carried out for the flatness prediction of such a rolling stand.

[0023] In JPS6046804 A, in order to improve the accuracy of the plate thickness along the longitudinal direction of the plate to be rolled, an application of a rolling mill is shown, which is equipped with a bending roll device between the working roll and the intermediate roll. The rolling of the plate is carried out by controlling the bending force during the rolling process. Summary of the invention

[0024] When rolling flat rolled stock made of metal, the resulting profile of the rolled stock and the resulting flatness of the rolled stock are important quality features. The influence on the profile and the flatness are inseparably coupled to one another, at least when the rolled stock is relatively thin. The flatness and / or the profile can be influenced in different ways and methods. For example, in the case of a six-high mill (i.e. a rolling mill in which, in addition to the working rolls and the support rolls, there are also intermediate rolls arranged between the working rolls and the support rolls, usually referred to in English as a "6-high-Gerüst"), the profile and / or the flatness can be influenced by bending the working rolls and by bending the intermediate rolls. Furthermore, the profile and / or the flatness can also be influenced by the reverse displacement of the intermediate rolls. This applies in particular to the so-called UCM (universal crown mill).

[0025] With the aid of such rolling stands, good results can be achieved for many materials. However, for high-strength wide materials and when a section that is as box-shaped as possible is required, such rolling stands in the prior art also reach their limits.

[0026] The object of the present invention is to provide a possibility by means of which the range within which flat rolling stock can be rolled with high quality can be expanded.

[0027] This 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 matter of dependent claims 2 to 5.

[0028] According to the invention, an operating method of the type mentioned at the outset is designed in such a way that the control device determines the intermediate roll adjustment value, the initial working roll control value and the initial intermediate roll control value in such a way that the initial working roll control value and / or the initial intermediate roll control value have respective predetermined minimum distances from their minimum and maximum values.

[0029] This makes it possible to provide a sufficiently large control reserve when rolling the flat product in the event of subsequent disturbances in the rolling process that are unavoidable in practice, such as changes in the temperature of the flat product and, associated therewith, changes in the material strength of the flat product. These disturbances can thus be compensated for by adapting the working roll control values ​​and / or the intermediate roll control values.

[0030] The minimum spacing can be determined as required. If the possible adjustment range, i.e. the range from the corresponding minimum value to the corresponding maximum value, is standardized to 100% and the value 0% is assigned to the corresponding minimum value, the minimum spacing can be, for example, 20%, 25%, 30%, 35% and can also be higher than this, for example, 40% or 45% or even 50%. Of course, other values ​​are also possible. It is even possible to select a value different from the value selected for the minimum spacing with the corresponding maximum value for the minimum spacing with the corresponding minimum value. For example, it can be stipulated that the initial working roll-control value must be at least 30% away from its minimum value and at least 40% away from its maximum value. Of course, the sum of these two minimum spacings is allowed to be a maximum of 100%. In addition, it is possible to predetermine the minimum spacing for the initial working roll-control value differently from the initial intermediate roll-control value. For example, it can be required that the initial working roll-control value is 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 at least 20% away from its minimum value and at least 50% away from its maximum value. The numerical values ​​mentioned are purely exemplary only in order to explain the principle.

[0031] In practice, it can be advantageous to prescribe the minimum distance in such a way that at least one of the two initial actuation values ​​is not located between the limits of its respective adjustment range, but is closer to its minimum or maximum value. In particular, it can be considered that the thermal crown of the working rolls changes during the rolling of the flat rolled product and that this change must be prevented by corresponding actuation of the working roll bending device and / or the intermediate roll bending device. If the actuation value is moved more toward its maximum value by such a prevention, the associated initial actuation value should be prescribed more toward 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 can be required.

[0032] The intermediate rollers are usually designed identically and are installed in the rolling stand opposite one another. In the case of UCM, the intermediate rollers also have a cone on one side within their working surface. For such rolling stands, the control device determines the intermediate roller control value, preferably as the signed distance of the cone from the side of the flat rolling stock. This procedure can be implemented particularly easily.

[0033] The target variable can be a set profile and / or a set straightness and can include, for example, the C2 value and the C4 value of the Chebyshev polynomial. The description of the set profile or the set straightness in this way is particularly simple. Usually, it is also completely sufficient if the target variable only includes these two values.

[0034] The operating method is preferably designed such that

[0035] the control device implements a model, by means of which the rolling of the flat rolling stock in the rolling stand is modeled on the basis of mathematical-physical equations,

[0036] - not only the actual variables and the target variables, but also the intermediate roll adjustment values, the initial working roll control values ​​and the initial intermediate roll control values ​​enter into the mathematical-physical equations, and

[0037] The control device determines the intermediate roll adjustment values, the initial working roll control values ​​and the initial intermediate roll control values ​​by solving an optimization problem entered into for the model.

[0038] This type of processing is real-time and reliably provides good results. The equations can be algebraic equations and differential equations in particular.

[0039] In some cases, the rolling stand, in order to influence the contour and / or the straightness of the flat rolled product, additionally has a cooling device by means of which sections of the working rolls can be cooled individually, viewed within the scope of the barrel width of the working rolls. In this case, the control device preferably also takes into account the individual cooling of the sections of the working rolls when determining the intermediate roll adjustment values, the initial working roll control values ​​and the initial intermediate roll control values.

[0040] Furthermore, this object is achieved by a control program having the features of claim 6. Advantageous embodiments of the control program are the subject matter of dependent claims 7 to 10.

[0041] According to the present invention, the execution of the control program causes the control device to design an operating method of the type mentioned at the outset in the following manner, namely: the control device determines the intermediate roll adjustment value, the initial working roll control value and the initial intermediate roll control value in such a way that the initial working roll control value and / or the initial intermediate roll control value have respective predetermined minimum distances from their minimum value and maximum value.

[0042] The advantages achieved thereby correspond to the advantages of the operating method according to the invention.

[0043] The control program can also be designed in an advantageous manner. The advantageous designs of the control program and the advantages resulting therefrom correspond to the advantageous designs and advantages of the operating method according to the invention.

[0044] Furthermore, this object is 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 when executing the machine code of the control program, the control device operates the rolling stand according to the operating method according to the invention.

[0045] The object is also achieved by a rolling stand for rolling flat rolled stock made of metal 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The above-described characteristics, features and advantages of the present invention and the manner and method of achieving these characteristics, features and advantages will become more clearly understood in conjunction with the following description of an embodiment, which will be explained in more detail in conjunction with the accompanying drawings. Here:

[0047] Figure 1 The rolling stand is shown from the side.

[0048] Figure 2 The rolling stand is shown from above.

[0049] Figure 3 A portion of a rolling stand is shown along the rolling direction.

[0050] Figure 4 shows a flow chart,

[0051] Figure 5 shows that the 2nd order Chebyshev polynomial,

[0052] Figure 6 shows that for the 4th order Chebyshev polynomial,

[0053] Figure 7 shows the effectiveness of the bending device,

[0054] Figure 8 Another flow chart is shown, and

[0055] Fig. 9 The model is shown. DETAILED DESCRIPTION

[0056] according to Figure 1 and 2 , a rolling stock 2 is to be rolled in a rolling stand 1. The rolling stock 2 consists of metal, for example steel or aluminum. The rolling stock 2 is a flat rolling stock, i.e. a strip (usually) or a thick plate (exceptions). The rolling in the rolling stand 1 is usually cold rolling. However, it can also be hot rolling as an exception. The rolling stand 1 has working rolls 3, which form a roll gap between them, in which the rolling stock 2 is rolled.

[0057] exist Figure 1 and 2 Only the working rolls 3 of the rolling stand 1 are shown, i.e. Figure 1The upper and lower working rolls 3 are shown in FIG. Figure 2 In FIG. 3 , only the upper working roll 3 is shown (the lower working roll 3 is covered by the upper working roll 3 ). Figure 3 The rolling stock 2 and the rolls 3 to 5 of the rolling stand 1 are shown, which are arranged above the rolling stock 2. The same sequence of rolls 3 to 5 is present below the rolling stock 2, although this is not the case at this point. Figure 3 in (and also in Figure 1 ) is not shown.

[0058] according to Figure 3 , the rolling stand 1 has support rolls 4, namely, upper support rolls and lower support rolls 4, in addition to the working rolls 3. In addition, the rolling stand 1 has intermediate rolls 5. The intermediate rolls 5 are arranged between the working rolls 3 and the support rolls 4. Specifically, the upper intermediate roll 5 is arranged between the upper working roll 3 and the upper support roll 4, thereby producing a sequence of three rolls 3 to 5 stacked one above the other above the rolled product 2. In a similar manner, the lower intermediate roll 5 is arranged between the lower working roll 3 and the lower support roll 4, thereby also producing a sequence of three rolls 3 to 5 stacked one above the other below the rolled product 2.

[0059] Working roll 3 and backup roll 4 are as in Figure 3 As can be seen in the figure, the intermediate rollers 5 are usually designed symmetrically and identically to each other. The intermediate rollers 5 are usually also designed identically to each other. However, they are usually asymmetrical themselves. The intermediate rollers 5 can, for example, have a cone 7 on one side within their working surface 6. Such grinding of the intermediate rollers 5 is often referred to as one-sided intermediate roller grinding.

[0060] In the case of an asymmetrical design of the intermediate rolls 5, the intermediate rolls 5 are usually installed opposite to one another in the rolling stand 1. Figure 3 As shown in FIG. 1 , the cone 7 of the upper intermediate roll 4 is located at the flat rolled product 2. Figure 3 In the region of the right side of the middle, the cone 7 of the lower intermediate roller 4 is therefore located in the middle of the flat rolled product 2. Figure 3 In the area on the left side.

[0061] In order to roll the flat rolled product 2 in the rolling stand 1 in a desired manner, in particular to adjust the profile, the contour and the straightness, the rolling mill 1 is provided with a plurality of rollers, each of which ... Figure 1 The rolling stand 1 has various adjusting elements 8 to 10 , namely a displacement device 8 , a working roll bending device 9 and an intermediate roll bending device 10 .

[0062] Within the scope of the present invention, the terms section, profile and straightness are used in their usual sense. Specifically, the term "section" is used as a purely scalar measure for the deviation of the thickness of the flat rolled stock 2 at a predetermined distance from the side of the flat rolled stock 2. For the section, the designation Cxx is commonly used in the prior art, where xx (in "mm") represents the predetermined distance from the side of the flat rolled stock 2. The term "profile" is used for the curve of the thickness of the rolled stock 2 over 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 "straightness" literally includes only visible distortions of the flat rolled stock 2. However, it is used as a synonym for the internal stresses present in the flat rolled stock 2 and is more precisely independent of whether these internal stresses lead to visible distortions of the flat rolled stock 2.

[0063] The axial movement of the intermediate rollers 5 can be adjusted by means of the displacement device 8. The axial movements of the intermediate rollers 5 are usually opposite to each other. Thus, when the upper intermediate roller 5 is moved to the left by a certain degree, the lower intermediate roller 5 is moved to the right by the same degree. Figure 3 The extent of the axial displacement is determined by the intermediate roller adjustment value UCΔ. The intermediate roller adjustment value UCΔ can be adjusted according to Figure 3 The illustration in is determined in particular as a signed distance of the cone 7 from the side of the flat rolled product 2 .

[0064] By means of the working roll bending device 9, a bending force for bending the working roll 3 can be applied to the working roll 3. The bending of the working roll 3 Figure 3 The upper working roll 3 is indicated by a double arrow in the figure. The associated working roll control value for the working roll bending device 9 is denoted by the reference symbol B1. In a similar manner, a bending force for bending the intermediate roll 5 can be applied to the intermediate roll 5 by means of the intermediate roll bending device 10. The bending of the intermediate roll 5 is Figure 3 This is indicated by a double arrow next to the upper intermediate roller 5. The associated intermediate roller control value for the intermediate roller bending device 10 is denoted by the reference symbol B2.

[0065] The rolling of the rolling stock 2 in the rolling stand 1 is controlled by a control device 11 of the rolling stand 1. As indicated by the designation “μP” for “microprocessor” within the control device 11, the control device 11 can usually be programmed with software. The control device 11 is therefore programmed with a control program 12. The control program 12 includes a machine code 13, which can be executed by the control device 11. The execution 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 will be explained in detail below.

[0066] according to Figure 4 , the control device 11 first receives the actual variable I and the target variable Z in step S1.

[0067] The actual variable I describes the flat rolled stock 2 before rolling in the rolling stand 1. The actual variable I can include, for example, the geometrical dimensions of the flat rolled stock 2, in particular its width and its thickness. The actual variable I can also include other geometrical characteristic variables of the flat rolled stock 2, such as its cross section, its contour and its straightness. Furthermore, the actual variable I can also include other properties of the flat rolled stock 2, such as its temperature, its chemical composition and possibly also its origin.

[0068] The target variable Z can include the following variables, which describe the desired profile K* of the flat rolled stock 2 after rolling in the rolling stand 1. For example, the target variable Z for the desired profile K* can include the C2 value k2 and the C4 value k4 of the Chebyshev polynomial, that is, the coefficients for the 2nd and 4th order Chebyshev function 2. As an alternative or in addition to the description of the desired profile K*, the desired flatness can also be described. The desired flatness can optionally be described similarly to the desired profile K* by corresponding C2 values ​​and corresponding C4 values.

[0069] Chebyshev polynomials and Chebyshev functions are well known to those skilled in the art. Specifically, the 2nd and 4th order Chebyshev functions have a functional relationship:

[0070]

[0071] Therein, x is the normalized position in the width direction of the flat rolled product 2 . The value x=0 therefore represents the center of the flat rolled product 2 , and the values ​​−1 and +1 represent the left and right sides of the flat rolled product 2 . Figure 5 and 6 The corresponding function is shown. The C2 value k2 and the C4 value k4 are the following coefficients: The function uses these coefficients, for example, to enter into the description of the setpoint profile K*:

[0072] K*=k2·C2+k4·C4

[0073] In step S2, the control device 11 determines the intermediate roll adjustment value UCΔ, the initial working roll control value B10 and the initial intermediate roll control value B20. The determination is performed taking into account the actual variable I. The determination is performed in such a way that the expected contour KE of the flat rolled product 2 is as close as possible to the setpoint contour K* as described by the target variable Z. As an alternative or in addition, the determination can also be performed in such a way that the expected flatness of the flat rolled product 2 is as close as possible to the setpoint flatness described by the target variable Z.

[0074] The determination of step S2 is not yet unambiguous within the scope defined so far. That is, a plurality of combinations of intermediate roll control values ​​UCΔ, initial working roll control values ​​B10 and initial intermediate roll control values ​​B20 are possible, wherein the desired profile KE and / or the desired flatness of the flat rolled product 2 is achieved with each such combination to be as close as possible to the desired profile K* and / or the desired flatness described by the target variable Z. In order to unambiguously determine the intermediate roll control values ​​UCΔ, the initial working roll control values ​​B10 and the initial intermediate roll control values ​​B20, the control device 11 also takes into account the following condition when determining the aforementioned values ​​UCΔ, B10, B20, namely that the initial working roll control values ​​B10 and / or the initial intermediate roll control values ​​B20 are at a respective predetermined minimum distance from their minimum values ​​B1min, B2min and maximum values ​​B1max, B2max. Therefore, at least one of the two initial control values ​​B10, B20 meets the condition specified for it. In the simplest case, the specification is carried out in such a way that the initial working roll control value B10 and / or the initial intermediate roll control value B20 are spaced as far as possible from their minimum values ​​B1min, B2min and maximum values ​​B1ax, B1max.

[0075] In step S3, the control device 11 adjusts the axial displacement of the intermediate roll 5 as a function of the determined intermediate roll adjustment value UCΔ. That is, the intermediate roll adjustment value UCΔ is predefined for the shifting device 8. The axial displacement of the intermediate roll 5 is no longer changed while the flat rolled product 2 is being rolled in the rolling stand 1. Furthermore, in step S4, the control device 11 sets the working roll control value B1 to the initial working roll control value B10 and the intermediate roll control value B2 to the initial intermediate roll control value B20.

[0076] Steps S1 to S4 are carried out by the control device 11 before the flat rolled product 2 is rolled in the rolling stand 1. Starting from step S5, the rolled product 2 is rolled in the rolling stand 1.

[0077] In step S5, the rolling stand 1 is controlled in continuous operation, i.e., while the rolling stock 2 is being rolled in the rolling stand 1. In step S5, the control device 11 controls the two bending devices 9, 10 according to their respective control values ​​B1, B2. It thus adjusts the bending devices according to their respective control values ​​B1, B2. Due to step S4, the control values ​​B1, B2 have initial control values ​​B10, B20 at least at the beginning of rolling of the flat rolling stock 2 in the rolling stand 1, so that the control device 11 adjusts the two bending devices according to their respective initial control values ​​B10, B20 at least at the beginning of rolling of the flat rolling stock 2 in the rolling stand 1.

[0078] Initially, the initial control values ​​B10, B20 are retained until actual values ​​for the profile K can be acquired with the aid of the measuring device 14 arranged on the outlet side of the rolling stand 1. The control device 11 therefore checks in step S6 whether such actual values ​​are available to it. 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 retains unchanged the control of the bending devices 9, 10, in particular according to their initial control values ​​B10, B20. However, as soon as actual values ​​for the profile K are available to the control device 11, the control device 11 proceeds to step S7. In step S7, the control device 11 changes the control values ​​B1, B2 in order to bring the actual profile K given by the actual values ​​closer to the setpoint profile K*. The control device 11 then returns to step S5. When step S5 is now repeated, the bending devices 9, 10 are again controlled using the correspondingly changed control values ​​B1, B2.

[0079] The repetition of steps S5 , S6 and S7 is continued until the flat rolling stock 2 has been completely rolled in the rolling stand 1 .

[0080] As an alternative or in addition to the acquisition of the actual value for the contour K, an actual value for the flatness can also be acquired. In this case, when determining the control values ​​B1 , B2 in step S7 , the goal of bringing the actual flatness given by the actual value close to the setpoint flatness is taken into account as an alternative or in addition.

[0081] Combine the following Figure 7 To explain why the following condition must be taken into account when determining the intermediate roll adjustment value UCΔ, the initial working roll control value B10 and the initial intermediate roll control value B20, namely that the initial working roll control value B10 and / or the initial intermediate roll control value B20 have respective predetermined minimum distances from their minimum values ​​B1min, B2min and maximum values ​​B1max, B2max.

[0082] Figure 7 For a plurality of intermediate roll control values ​​UCΔ it is shown which C2 values ​​k2 and C4 values ​​k4 can be set in each case by setting the working roll control value B1 and the intermediate roll control value B2. Figure 7 , for each intermediate roller adjustment value UCΔ, a trapezoid 15 is generated (exactly or at least approximately) in the space k2-k4. This trapezoid 15 is Figure 7In each case, the intermediate roller adjustment values ​​UCΔ are supplemented by lowercase letters (a to e). The supplementation by the corresponding lowercase letters serves only to distinguish the trapezoids 15 from one another linguistically. In the following, lowercase letters are used only when a very specific reference is to be made to a completely specific trapezoid of the trapezoids 15. As long as a general reference is made to the trapezoids 15, the lowercase letters are omitted. With regard to the corresponding intermediate roller adjustment values ​​UCΔ, the process proceeds in a completely analogous manner.

[0083] The sides of the trapezoid 15 correspond to the fact that one of the two manipulated values ​​B1, B2 is the smallest or the largest and the respective other of the two manipulated values ​​B1, B2 passes through its possible value range. The angles of the respective trapezoid 15 correspond to the fact that the two manipulated values ​​B1, B2 are the smallest or the largest. By changing the intermediate roller control value UCΔ, the position of the associated trapezoid 15 in the k2-k4 space can obviously be adjusted.

[0084] If, for example, the set profile K* corresponds to the point 16 in the k2-k4 space, then in the case of the intermediate roller control value UCΔc, the set profile K* can be adjusted. However, only a small control reserve is available not only for a reduction in the intermediate roller control value B2, but also for an increase in the C2 value k2 and for a reduction in the C4 value k4. In a similar manner, in the case of the intermediate roller control value UCΔe, the set profile K* can also be adjusted. However, only a small control reserve is available not only for an increase in the intermediate roller control value B2, but also for a decrease in the C2 value k2 and for an increase in the C4 value k4. In contrast, if the intermediate roller control value UCΔd is selected, not only the set profile K* can be adjusted. More precisely, a large control reserve is available not only for a reduction in the intermediate roller control value B2 (and the working roller control value B1), but also for an increase thereof. Correspondingly, a large control reserve is available both for a reduction and for an increase in the C2 value k2 and likewise both for a reduction and for an increase in the C4 value k4.

[0085] As far as has been explained so far, it is optimal to determine the initial working roll control value B10 and / or the initial intermediate roll control value B20 in such a way that at least one of the two values ​​B10, B20 is as far away as possible from its minimum value B1min, B2min and maximum value B1max, B2max. However, deviations from this rule can be evidenced by the subsequent heating of the working rolls 3 that occurs during the rolling of the rolled stock 2 in the rolling stand 1 and a corresponding change in the contour of the working rolls 3.

[0086] For the case where at least one of the two values ​​B10, B20 should be as far apart as possible from its minimum value B1min, B2min and maximum value B1max, B2max, the specific determination of the intermediate roller adjustment value UCΔ can be carried out, for example, in such a way that a symmetrical convex geometry is defined in the k2-k4 space. A suitable symmetrical convex geometry is, for example, a rectangle (special case: a square), whose edges are oriented parallel to the k2- or k4-axis and have a predetermined ratio relative to each other. Another suitable symmetrical convex geometry is, for example, an ellipse (special case: a circle), whose main axis is oriented parallel to the k2- or k4-axis and has a predetermined ratio relative to each other. The intermediate roller adjustment value UCΔ sought is then usually determined explicitly by the condition that the area covered by the symmetrical convex geometry is maximized when the symmetrical convex geometry is centered relative to the point 16. Exceptions only occur in the very unlikely case that the setpoint contour K* is so unfavorably predetermined that it can "only just be reached". An example of such a situation is that the setpoint profile K* in the k2-k4 space can be described by the point 16'. If the initial working roll control value B10 and / or the initial intermediate roll control value B20 should not be in the middle between their minimum values ​​B1min, B2min and maximum values ​​B1max, B2max, this procedure can be modified by using a distorted graph.

[0087] Figure 8 A possible procedure for determining the center roller adjustment value UCΔ is schematically shown. Figure 8 In the results, it corresponds to Figure 4 Implementation of step S2.

[0088] according to Figure 8 , the control device 11 first determines a value B1M for the average of the working roll control values ​​B1 in step S11. In the simplest case, the control device 11 forms an unweighted arithmetic mean of the minimum and maximum working roll control values ​​B1min, B1max in step S11. In a similar manner, the control device 11 determines a value B2M for the average of the intermediate roll control values ​​B2 in step S12.

[0089] In step S13, the control device 11 sets the intermediate roller adjustment value UCΔ to an initial value. In step S14, the control device 11 determines the associated initial control values ​​B10, B20 for which the expected profile KE corresponds as closely as possible to the setpoint profile K* (as an alternative or in addition, the expected flatness corresponds as closely as possible to the setpoint flatness).

[0090] In step S15, the control device 11 checks whether the determined initial working 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 step S16. If this is not the case, the control device 11 checks in 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 changes the intermediate roll adjustment value UCΔ in step S18 and returns from there to step S14.

[0091] In step S16, the control device 11 checks whether the change of the intermediate roller adjustment value UCΔ should be ended. The check in step S16 can, for example, include an evaluation of the symmetrical convex geometry explained above. If the change of the intermediate roller adjustment value UCΔ should not be ended, the control device 11 proceeds to step S18. Otherwise, Figure 8 The processing method ends. Then, Figure 4 The last determined values ​​UCΔ, B10, B20 are used in steps S3 and S4.

[0092] To execute Figure 4 Step S2 or Figure 8 In step S14, the control device 11 can Fig. 9 The diagram in embodies a model 17. With the aid of the model 17, the rolling of the flat rolled stock 2 in the rolling stand 1 is modeled. The model 17 is based on mathematical-physical equations. The model can in particular include a set of differential equations that are locally resolved two-dimensionally or three-dimensionally and coupled to each other. The actual variable I and the target variable Z enter into the mathematical-physical equations. In addition, the intermediate roll adjustment value UCΔ, the initial working roll control value B10 and the initial intermediate roll control value B20 also enter into the mathematical-physical equations. The model 17 provides the expected profile KE (as an alternative or supplementary solution, the expected flatness) as an output variable. Such a corresponding model 17 is known to those skilled in the art.

[0093] In the case of such modeling, the control device 11 can determine the intermediate roll adjustment value UCΔ, the initial working roll control value B10 and the initial intermediate roll control value B20, for example, within the scope of step S2 or step S14 by solving an optimization problem entered into by the model 17 .

[0094] In some cases, the actuators 8 to 10 mentioned, i.e. the displacement device 8, the working 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 straightness of the flat rolled product 2 can be influenced. In other cases, the rolling stand 1 is used in order to influence the contour K and / or the straightness of the flat rolled product 2. Figure 2 The illustration in FIG. 1 additionally has a cooling device 18. In this case, the cooling device 18 can be used to individually cool the sections of the working roll 3 within the scope of the roll width of the working roll 3. If such a design is given, the control device 11 also takes into account the individual cooling B3 of the sections of the working roll 3 when determining the intermediate roll adjustment value UCΔ, the initial working roll control value B10 and the initial intermediate roll control value B20. For example, the individual cooling B3 of the sections of the working roll 3 can be Figure 4 Either it is taken into account by the control device 11 within the scope of the execution of step S2 or S14 of 8 , or the individual cooling B3 of the sections of the working roll 3 can be an additional input variable of the model 17 and can be taken into account accordingly in the model 17 .

[0095] The invention has many advantages. Thus, the influence of the specific intermediate roll adjustment value UCΔ remains essentially unaffected by the adjustment range of the two bending devices 9, 10. However, it influences the associated control values ​​B1, B2 to a large extent, the resulting effect on the roll gap and thus on the profile K and the straightness of the rolled product 2. As a result, a very wide range of different flat products 2 can be rolled in a rolling stand 1 in accordance with the specifications by the process according to the invention. This applies not only to the strength of the flat product 2 but also to its size and to the requirements for the section, profile K and straightness. In many cases, it is not necessary to replace the working rolls 3 with other working rolls 3 with adapted crowns in a costly and time-consuming manner. Although it is possible to use the individual cooling B3 of the working rolls 3. However, this is usually not necessary. This is particularly advantageous because the individual cooling B3 of the working rolls 3 is very slow on the one hand and has only a small adjustment range on the other hand.

[0096] Although the invention has been illustrated and described in detail by means of preferred embodiments, the invention is not restricted to the disclosed examples and other variants can be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention.

[0097] Reference numerals list

[0098] 1 Rolling stand

[0099] 2 Rolling

[0100] 3 Working rolls

[0101] 4 Support rollers

[0102] 5 Middle roller

[0103] 6 Working surface

[0104] 7 Cone

[0105] 8 Mobile Devices

[0106] 9, 10 Bending device

[0107] 11 Control Device

[0108] 12 Control procedures

[0109] 13 Machine Code

[0110] 14. Measuring device

[0111] 15 Trapezoid

[0112] 16, 16' point

[0113] 17 Model

[0114] 18 Cooling device

[0115] B1, B10 working roll-control value

[0116] Minimum values ​​of B1min and B2min

[0117] Maximum values ​​of B1max and B2max

[0118] B2, B20 intermediate roller - control value

[0119] B3 Individual cooling

[0120] Average value of B1M and B2M

[0121] I Actual parameter

[0122] K, KE, K* profiles

[0123] k2 C2 value

[0124] k4 C4 value

[0125] Steps S1 to S18

[0126] UCΔ Intermediate roller-adjustment value

[0127] Z target parameter

Claims

1. A method for operating a rolling stand (1) for rolling a flat rolling stock (2) made of metal, wherein the rolling stand (1) has working rolls (3), backup rolls (4) and intermediate rolls (5) arranged between the working rolls (3) and the backup rolls (4), - wherein a control device (11) for the rolling stand (1) receives actual variables (I) and target variables (Z), - the actual variable (I) describes the flat rolled product (2) before rolling in the rolling stand (1), and the target variable (Z) describes the desired profile (K*) and / or the desired flatness of the flat rolled product (2) after rolling in the rolling stand (1), - wherein the control device (11) determines, before rolling the flat rolled product (2) in the rolling stand (1), taking into account the actual variable (I), intermediate roll adjustment values ​​(UCΔ) for the axial displacement of the intermediate rolls (5), initial working roll control values ​​(B10) for a working roll bending device (9) for bending the working rolls (3), and initial intermediate roll control values ​​(B20) for an intermediate roll bending device (10) for bending the intermediate rolls (5), for which an expected profile (KE) and / or an expected flatness of the flat rolled product (2) are brought as close as possible to a set profile (K*) and / or a set flatness described by the target variable (Z), - the control device (11) regulates the axial displacement of the intermediate roller (5) according to the determined intermediate roller adjustment value (UCΔ) before rolling the flat rolled product (2) in the rolling stand (1), - wherein the control device (11) regulates the working roll bending device (9) in the rolling stand (1) at least at the beginning of rolling of the flat rolled stock (2) according to the determined initial working roll control value (B10) and regulates the intermediate roll bending device (10) according to the determined initial intermediate roll control value (B20), It is characterized in that The control device (11) determines the intermediate roll adjustment value (UCΔ), the initial working roll control value (B10) and the initial intermediate roll control value (B20) in such a way that the initial working roll control value (B10) and / or the initial intermediate roll control value (B20) are separated from their minimum and maximum values ​​(B1min, B2min, B1max, B2max) by a respective predetermined minimum distance.

2. The operating method according to claim 1, It is characterized in that The intermediate rollers (5) are designed identically and are installed in opposite directions in the rolling stand (1), the intermediate rollers (5) having a cone (7) on one side within their working surface, and the control device (11) ascertains the intermediate roller adjustment value (UCΔ) as the signed distance between the cone (7) and the side edge of the flat rolled product (2).

3. The operating method according to claim 1 or 2, It is characterized in that The target variable (Z) for the desired contour (K*) and / or for the desired straightness comprises the C2 value (k2) and the C4 value (k4) of the Chebyshev polynomial.

4. The operating method according to claim 1, 2 or 3, It is characterized in 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 modeled based on mathematical-physical equations, - not only the actual variable (I) and the target variable (Z), but also the intermediate roll control value (UCΔ), the initial working roll control value (B10) and the initial intermediate roll control value (B20) enter into the mathematical-physical equation, and The control device (11) determines the intermediate roll adjustment value (UCΔ), the initial working roll control value (B10) and the initial intermediate roll control value (B20) by solving an optimization problem entered into the model (17).

5. The operating method according to any one of the preceding claims, It is characterized in that In order to influence the profile (K) and / or the straightness of the flat rolled product (2), the rolling stand (1) additionally has a cooling device (18), by means of which sections of the working rolls (3) can be cooled individually within the scope of the roll barrel width of the working rolls (3), and the control device (11) also takes into account the individual cooling of the sections of the working rolls (3) when determining the intermediate roll adjustment value (UCΔ), the initial working roll control value (B10) and the initial intermediate roll control value (B20).

6. A control program comprising a machine code (13), the machine code being executable by a control device (11) for a rolling stand (1) having working rolls (3), support rolls (4) and intermediate rolls (5) arranged between the working rolls (3) and the support rolls (4), the rolling stand being used for rolling a flat rolled product (2) made of metal, wherein the execution of the machine code (13) by the control device (11) causes the control device (11) to - receiving actual variables (I) and target variables (Z) for the rolling stand (1), wherein the actual variables (I) describe the flat rolled product (2) before rolling in the rolling stand (1) and the target variables (Z) describe a desired profile (K*) and / or a desired flatness of the flat rolled product (2) after rolling in the rolling stand (1), - before rolling the flat rolled product (2) in the rolling stand (1), determining, taking into account actual variables (I), intermediate roll adjustment values ​​(UCΔ) for the axial displacement of the intermediate rolls (5), initial working roll control values ​​(B10) for a working roll bending device (9) for bending the working rolls (3), and initial intermediate roll control values ​​(B20) for an intermediate roll bending device (10) for bending the intermediate rolls (5), for which values ​​an expected profile (KE) and / or an expected flatness of the flat rolled product (2) is as close as possible to a set profile (K*) and / or a set flatness described by target variables (Z), - before rolling the flat rolling stock (2) in the rolling stand (1), adjusting the axial displacement of the intermediate roller (5) by means of a displacement device (8) as a function of the determined intermediate roller adjustment value (UCΔ), - at least at the beginning of rolling of the flat rolled stock (2) in the rolling stand (1), adjusting the working roll bending device (9) according to the determined initial working roll control value (B10) and adjusting the intermediate roll bending device (10) according to the determined initial intermediate roll control value (B20), and - The intermediate roll adjustment value (UCΔ), the initial working roll control value (B10) and the initial intermediate roll control value (B20) are determined in such a way that the initial working roll control value (B10) and / or the initial intermediate roll control value (B20) are at a respectively predetermined minimum distance from their minimum and maximum values ​​(B1min, B2min, B1max, B2max).

7. A control program according to claim 6, It is characterized in that Execution of a machine code (13) by the control device (11) causes the control device (11) in a rolling stand (1) whose intermediate rolls (5) are identically designed, are inserted into the rolling stand (1) in opposite directions and have a cone (7) on one side within their working surface to determine the intermediate roll adjustment value (UCΔ) as a signed distance between the cone (7) and a side edge of the flat rolled product (2).

8. The control program according to claim 6 or 7, It is characterized in that The target variable (Z) for the desired contour (K*) and / or for the desired straightness comprises the C2 value (k2) and the C4 value (k4) of the Chebyshev polynomial.

9. A control program according to claim 6, 7 or 8, It is characterized in that The execution of the machine code (13) by the control device (11) causes the control device (11) to - implementing a model (17) by means of which the rolling of a flat rolling stock (2) in a rolling stand (1) is modeled based on mathematical-physical equations, wherein not only the actual variables (I) and the target variables (Z) but also the intermediate roll adjustment values ​​(UCΔ), the initial working roll control values ​​(B10) and the initial intermediate roll control values ​​(B20) are entered into the mathematical-physical equations, and - determining the intermediate roll control value (UCΔ), the initial working roll control value (B10) and the initial intermediate roll control value (B20) by solving the optimization problem entered into the model (17).

10. The control program according to any one of claims 6 to 9, It is characterized in that The execution of a machine code (13) by the control device (11) causes the control device (11) to also take into account the individual cooling of sections of the working rolls (3) when determining intermediate roll adjustment values ​​(UCΔ), initial working roll control values ​​(B10) and initial intermediate roll control values ​​(B20) in a rolling stand (1), wherein the rolling stand additionally has a cooling device (18) for influencing the profile (K) and / or the straightness of the flat rolled product (2), by means of which sections of the working rolls (3) can be individually cooled as viewed within the barrel width of the working rolls (3).

11. A control device for a rolling stand (1) for rolling flat rolled products (2) made of metal, wherein the rolling stand (1) has working rolls (3), support rolls (4) and intermediate rolls (5) arranged between the working rolls (3) and the support rolls (4), wherein the control device is programmed with a control program (12) according to any one of claims 6 to 10 so that when executing a machine code (13) of the control program (12), it operates the rolling stand (1) according to an operating method according to any one of claims 1 to 5.

12. A rolling stand for rolling flat rolled products (2) made of metal, - wherein the rolling stand comprises working rolls (3), support rolls (4), intermediate rolls (5) arranged between the working rolls (3) and the support rolls (4), intermediate roll bending devices (10) for bending the intermediate rolls (5) and working roll bending devices (9) for bending the working rolls (3), - wherein the displacement device (8) is designed so as to carry out an axial displacement of the intermediate roller (5), - wherein the rolling stand has a control device (11) according to claim 11, by which the rolling stand is operated during operation according to an operating method according to any one of claims 1 to 5.

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