Improved contour and / or flatness control of a rolling stand

Abstract

Before the material enters the rolling stand, a control system for a rolling mill for flat metal stock receives initial data (A) and target data (Z*) of the material and stand data (G) of the rolling mill. The initial data (A) describes the material at the entry end of the rolling mill. The target data (Z*) are the data the material should have at the exit end of the rolling mill. The stand data (G) describes the rolling mill. Before the material enters the rolling mill, the control system uses the initial data (A) and the target data (Z*), taking into account the stand data (G), to determine symmetrical and asymmetrical control variables (sym, asym) for the rolling mill actuators and controls these actuators, at least at the beginning of the rolling process, according to the determined symmetrical and asymmetrical control variables (sym, asym).To determine the asymmetric control variables (asym), the control system first determines the symmetric control variables (sym) and then determines the asymmetric control variables (asym) taking into account not only the initial data (A), the target data (Z*) and the framework data (G), but also the previously determined symmetric control variables (sym).

Description

field of technology

[0001] The present invention relates to an operating method for a rolling mill for rolling a flat rolled metal stock, wherein a control system for the rolling mill is informed of initial and target data of the rolled material and mill stand data before the rolled material enters the mill stand, wherein the initial data describe the rolled material on the entry side of the mill stand, the target data are data that the rolled material should have on the exit side of the mill stand, and the mill stand data describe the mill stand, wherein the control system determines symmetrical and asymmetrical control variables for actuators of the mill stand on the basis of the initial data and the target data, taking into account the mill stand data, and wherein the control system controls the actuators at least at the beginning of the rolling of the rolled material in the mill stand according to the determined symmetrical and asymmetrical control variables.

[0002] The present invention further relates to a control program for a software-programmable control system, wherein the control program comprises machine code that can be directly executed by the control system, wherein the execution of the machine code by the control system causes the control system to control a rolling mill for rolling a flat rolled metal product according to such an operating method.

[0003] The present invention further relates to a control system for a rolling stand for rolling a flat rolled metal stock, wherein the control system is programmed with such a control program, so that the control system controls the rolling stand according to such an operating procedure.

[0004] The present invention further assumes a rolling device, wherein the rolling apparatus comprises a rolling stand for rolling a flat rolled material made of metal, wherein the rolling stand comprises actuators for adjusting a rolling gap of the rolling stand according to symmetrical and asymmetrical control variables, wherein the rolling stand comprises a control system, wherein the control system is designed as such a control system that controls the rolling stand according to such an operating procedure. State of the art

[0005] Such an operating procedure is known, for example, from the technical article "Decoupling Adaptive Smith Prediction Model of Flatness Closed-Loop Control and Its Application" by Mingming Song et al., Processes 2020, 8(8), 895, https: / / doi.org / 10.3390 / pr8080895. Summary of the invention

[0006] When rolling a flat workpiece, maintaining target contour and flatness values ​​is of paramount importance, in addition to achieving the target thickness. Appropriate actuators are used to ensure these target values ​​are met. For example, the rolls can be pivoted and, in the case of work or intermediate rolls, bent. In conjunction with appropriate roll grinding, axial sliding movements of the work or intermediate rolls can also be achieved, usually in opposite directions. Particularly in cases where the shapes of the upper and lower roll sets are neither point-symmetrical nor axially symmetrical, either inherently or under load, even a purely symmetrical change in the rolling force will result in a change in the asymmetry of the roll gap. This leads to asymmetrical flatness and contour deviations in the rolled product.

[0007] The reason for the upper and lower roll sets not being symmetrical either point- or axis-symmetrical can be, for example, the use of identical rolls with different diameters. Two rolls are considered identical if they perform the same function and one is positioned above and the other below the workpiece, for example, in a four-stand or a six-stand, the two backup rolls and the two work rolls; in the case of a six-stand, this also includes the two intermediate rolls. The effect is more pronounced the smaller the diameters of the rolls in the corresponding roll pair and / or the greater the difference in diameter between the rolls.

[0008] To ensure compliance with target values, the prior art incorporates a sensor device at the outlet of the rolling stand, which detects the contour and / or flatness of the rolled material. The corresponding measured values ​​are fed to the control system. The control system then adjusts the symmetrical and asymmetrical control variables by comparing the detected contour or flatness with the corresponding setpoint values.

[0009] The state of the art represents a typical control system. The actual value (the resulting contour or flatness) is measured, and the manipulated variables, specifically the symmetrical and asymmetrical manipulated variables, are adjusted based on the deviation of the actual value from the corresponding target value. In the state of the art, correction only occurs once a measurement result is available. This results in a significant dead time. Consequently, a considerable amount of rolled material is processed before corrective action can be taken. Therefore, in the state of the art, a large quantity of rolled material often fails to meet the required specifications and must be scrapped. Furthermore, the actual value can only be measured after the rolled material has exited the rolling stand. As a result, the control loop exhibits relatively low dynamics.

[0010] The object of the present invention is to create possibilities by means of which a high-quality adjustment of the rolling stand is possible already at the beginning of the rolling process, i.e. when the rolled material has not yet reached the point where the actual value of the rolled material is recorded.

[0011] The problem is solved by an operating method with the features of claim 1. Advantageous embodiments of the operating method are the subject of dependent claims 2 to 10.

[0012] According to the invention, an operating method of the type mentioned at the outset is designed in such a way that the control system, in order to determine the asymmetric control variables, first determines the symmetric control variables and then determines the asymmetric control variables taking into account not only the initial data, the target data and the framework data, but also the previously determined symmetric control variables.

[0013] According to the invention, a staged approach is used. First, the symmetrical control variables are determined. Only when the symmetrical control variables are known are the asymmetrical control variables determined based on the initial data, the target data, the stand data, and the symmetrical control variables. The extent to which the symmetrical control variables cause an asymmetry in the roll gap can be determined, for example, by means of experiments or by means of a sufficiently accurate model of the rolling process.

[0014] The initial and target data primarily consist of geometric data of the rolled material, such as thickness, profile, contour, and flatness. Where necessary, the initial data, and potentially also the target data, can include further data such as temperature, chemical composition, phase fractions, and material strength or hardness. The stand data includes, for example, the topological structure of the rolling stand (e.g., whether it is a four-story or six-story stand), information about the rolls (diameter, barrel length, grind, etc.), the stand stiffness, and other details.

[0015] The rolling mill stand can be a quarto stand, meaning a rolling mill stand with only two backup rolls in addition to the work rolls. Alternatively, the rolling mill stand can be a sexto stand, meaning a rolling mill stand with two intermediate rolls in addition to the work rolls and backup rolls. In the case of a sexto stand, the rolling mill stand can be, in particular, a so-called UCM (universal crown mill).

[0016] In some configurations of a sexto frame, the intermediate rollers may also have a ramp, a step or a conical section at opposite ends of the respective roller bundle.

[0017] The rolling stand's actuators include at least one adjusting device. This adjusting device acts on the backup rolls of the rolling stand. It sets the thickness of the roll gap between the work rolls of the rolling stand and applies the rolling force. The adjusting device is typically designed as a hydraulic cylinder unit.

[0018] In addition, the rolling stand's actuators can also include at least one bending device. The bending device bends the work rolls. If the rolling stand has intermediate rolls in addition to work rolls and backup rolls, the bending device can act on either the work rolls or the intermediate rolls as needed. Optionally, two bending devices may be present, one acting on the work rolls and the other on the intermediate rolls. The bending devices are also typically designed as hydraulic cylinder units.

[0019] The aforementioned actuators – this applies equally to the adjusting device and the bending devices – each have a separate sub-unit for the operating side and the drive side of the rolling stand. For application of a symmetrical control variable, the two sub-units of the respective actuator are controlled with the same magnitude and the same sign. For application of an asymmetrical control variable, the two sub-units of the respective actuator are controlled with the same magnitude but opposite signs.

[0020] Furthermore, the actuators of the rolling stand can include at least one sliding device for counter-rotating the rolls of the rolling stand. In the case of a four-roll stand, the sliding device acts on the work rolls of the rolling stand. In the case of a six-roll stand, the sliding device can act on the work rolls or the intermediate rolls as needed. Optionally, two sliding devices may be present, one acting on the work rolls and the other on the intermediate rolls. The sliding devices are also generally designed as hydraulic cylinder units.

[0021] Furthermore, the rolling stand's actuators can include independently controllable bending force actuators for an upper and a lower set of rolls. In this case, the bending force actuators are supported directly by the stand's upright. This allows for the bending of rolls in the upper set independently of the bending of rolls in the lower set.

[0022] In addition to the actuators mentioned so far, a roller cooling system may also be present, which can be controlled with spatial resolution along the length of the bale. If present, a roller cooling system allows a liquid coolant – usually water – to be applied to the work rollers. The roller cooling system reacts relatively slowly.

[0023] The problem addressed by the present invention becomes more pronounced the smaller the diameters of the work rolls are and the greater the difference between their diameters. The operating method is therefore particularly preferred for a rolling mill stand where the diameter of the upper work roll and / or the lower work roll is less than 350 mm, especially between 250 mm and 300 mm. Alternatively or additionally, it is advantageous to use the operating method for a rolling mill stand where the diameter of the upper work roll differs from the diameter of the lower work roll, especially by more than 15 mm, 20 mm, or 30 mm.

[0024] In some cases, the initial and / or target data change during the rolling process. In such cases, the control system determines changes to the symmetrical and asymmetrical control variables based on these changes. The control system then adjusts the actuators of the rolling stand according to these changes. The system determines the changes to the symmetrical control variables based on the changes to the initial and / or target data, taking the stand data into account. The system determines the changes to the asymmetrical control variables based on the changes to the initial and / or target data, taking the stand data into account and additionally considering the changes to the symmetrical control variables. This allows for improved accuracy in setting the roll gap.

[0025] This approach is feasible regardless of whether the control system receives a measurement of the actual value of the rolled material directly at the exit of the rolling stand during the rolling process. If received, the actual value describes the contour and / or flatness of the rolled material. Therefore, the actual value is not a scalar, but spatially resolved in the width direction of the rolled material. The phrase "directly at the exit of the rolling stand" means that no other rolling stand is located between the rolling stand and the point where the actual value is measured.

[0026] In particular, the rolling stand is often part of a multi-stand rolling mill. In a multi-stand rolling mill, a contour and / or flatness detection device is not usually located directly downstream of every rolling stand. For example, in a rolling mill with a total of five rolling stands, such a device is often located either only downstream of the last rolling stand or downstream of both the third and the last rolling stand. It is therefore possible that another rolling stand is located downstream of the rolling mill, and that no such device is located between the rolling stand under consideration and the other rolling stand. Even in this case, the configuration described above can be used and leads to excellent results.

[0027] Provided the control system receives the aforementioned actual value, it is still possible to that the control system receives the corresponding actual value of the rolled material during the rolling process, that the control system determines a symmetric and an asymmetric component of the actual value, that the control system determines changes in the symmetric and asymmetric control variables and controls the actuators of the rolling stand according to the changed control variables, that the control system determines the changes in the symmetric control variables based on the symmetric component of the actual value, and that the control system determines the changes in the asymmetric control variables based on the asymmetric component of the actual value and the changes in the symmetric control variables.

[0028] This significantly improves the quality of the control system. This approach can be implemented, for example, in a multi-stand rolling mill, according to the configuration described above, for the third and last stands. Furthermore, this approach can be combined with the determination of changes resulting from altered initial and / or target data.

[0029] To determine changes in asymmetric control variables, the control system preferably identifies a change in the asymmetry of the roll gap in the rolling stand caused by changes in the symmetric control variables and then determines the changes in the asymmetric control variables based on the change in the asymmetry of the roll gap in the rolling stand. The influence of a change in a specific symmetric control variable on the asymmetry of the roll gap in the rolling stand can be determined, for example, through experiments or using a sufficiently accurate model of the rolling process.

[0030] In many cases, the control system comprises a higher-level and a lower-level control unit. The higher-level control unit can be, in particular, a so-called L2 system, and the lower-level control unit a so-called L1 system. When the control system is divided into higher-level and lower-level control units, the higher-level control unit preferably determines the symmetrical and asymmetrical control variables before the material enters the rolling stand and transmits these variables to the lower-level control unit. The lower-level control unit then controls the actuators of the rolling stand according to these determined symmetrical and asymmetrical control variables. Furthermore, the lower-level control unit determines changes in these symmetrical and asymmetrical control variables and controls the actuators of the rolling stand accordingly.

[0031] Where necessary, the subordinate control unit also receives the sensitivities from the superior control unit. Furthermore, the subordinate control unit may also receive the actual value and determine the symmetric and asymmetric components of the actual value.

[0032] The problem is further solved by a control program with the features of claim 11. According to the invention, the execution of the control program causes the control system to control a rolling mill for rolling a flat rolled metal stock according to an operating method according to the invention.

[0033] The problem is further solved by a control system with the features of claim 12. According to the invention, the control system is programmed with a control program according to the invention, such that the control system controls the rolling mill according to an operating method according to the invention.

[0034] The problem is further solved by a rolling mill with the features of claim 13. According to the invention, the control system is designed as a control system according to the invention, which controls the rolling mill according to an operating method according to the invention. Brief description of the drawings

[0035] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of an exemplary embodiment, which is explained in more detail in conjunction with the drawings. These drawings show: FIG 1 a multi-stand rolling mill, FIG 2 a rolling stand, FIG 3 another rolling stand, FIG 4 a flow diagram, FIG 5 a flow diagram, FIG 6 a flow diagram and FIG 7 a structural design of a control system. Description of the embodiments

[0036] According to FIG 1 A multi-stand rolling mill has several rolling stands 1. The rolling stands 1 are in FIG 1 The diagram is only schematic. In particular, only the work rolls of the rolling stands 1 are shown. Furthermore, the number (5) of rolling stands 1 shown is purely exemplary. The rolling mill could also have fewer rolling stands 1 (for example, two, three, or four rolling stands 1) or more rolling stands 1 (for example, six or seven rolling stands 1).

[0037] In the rolling stands 1, a rolled material 2 is rolled. The rolled material 2 consists of metal, often steel, in some cases aluminum, and in rare cases another metal such as copper. The rolled material 2 is a flat rolled material, i.e., a strip (typical case) or a heavy plate (exception). The rolled material 2 passes through the rolling stands 1 sequentially. It therefore has a uniform transport direction x.

[0038] A detection device 3 can be arranged behind some of the rolling stands 1. Using the respective detection device 3, a specific actual value y of the rolled material 2 can be measured, which the rolled material 2 exhibits after rolling in the immediately preceding rolling stand 1. The respective actual value y describes the contour and / or the flatness of the rolled material 2. In this case, a detection device 3 is arranged only behind the last rolling stand 1 of the rolling mill. However, it is possible that detection devices 3 are also arranged behind at least one other rolling stand 1 of the rolling mill, for example, additionally behind the third rolling stand 1 of the rolling mill.

[0039] At least one of the rolling stands 1 is controlled by a control system 4. In this case, all rolling stands 1 are controlled by the control system 4. The control system 4 is software-programmable. It is programmed with a control program 5. The control program 5 comprises machine code 6, which can be executed directly by the control system 4. Due to the programming of the control system 4 with the control program 5, the control system 4 executes the machine code 6. The execution of the machine code 6 by the control system 4 causes the control system 4 to control the rolling stands 1 according to an operating procedure that will be explained in more detail later.

[0040] Before the operating procedure is explained in more detail, the following is described in connection with the FIG 2 and 3 The structural design of one of the rolling stands 1 is explained. The structural design applies equally to all rolling stands 1.

[0041] According to FIG 2 The rolling stand 1 has 7 work rolls. The work rolls 7 are supported by intermediate rolls 8, which in turn are supported by backup rolls 9. The rolling stand 1 is therefore designed as a sexto stand. In particular, the rolling stand 1 can be designed as a so-called UCM.

[0042] The rolling stand 1 can have various actuators 10 to 14 and 18, 19. Actuators 10 to 14 and 18, 19 are generally known to those skilled in the art and are therefore only briefly outlined below.

[0043] In every case, an adjusting device 10 is present. The adjusting device 10 is generally designed as a hydraulic adjusting device. It acts via the corresponding mounting components (not shown) on the bearing journals 15 of the upper or the lower support roller 9. The other support roller 9 is usually statically mounted. The adjusting device 10 has a separate sub-device 10a, 10b for each of the two bearing journals 15 of the corresponding support roller 9.

[0044] A sliding device 11 for the intermediate rolls 8 is often also provided. The sliding device 11 allows the intermediate rolls 8 to be moved axially. The movement of the intermediate rolls 8 is generally in opposite directions. Thus, if one intermediate roll 8 is moved from left to right, the other intermediate roll 8 is moved from right to left. The same applies to a movement in the reverse direction. In conjunction with a suitable grinding pattern, generally known to those skilled in the art, the contour of the roll gap can be influenced. The sliding device 11 has a separate sub-device 11a, 11b for each of the two intermediate rolls 8.

[0045] Alternatively or in addition to the sliding device 11 for the intermediate rolls 8, a sliding device 12 for the work rolls 7 may also be provided. The sliding device 12 allows the work rolls 7 to be moved axially. The preceding descriptions regarding the movement of the intermediate rolls 8 also apply analogously to the movement of the work rolls 7. The sliding device 12 also has a separate sub-device 12a, 12b for each of the two work rolls 7.

[0046] Furthermore, a bending device 13 is often provided for the work rolls 7. The bending device 13 allows the work rolls 7 to be bent. The bending device 13 is generally designed as a hydraulic bending device. The bending device 13 acts on the bearing journals 16 of the work rolls 7 via the corresponding mounting elements (not shown). The bending device 13 has a separate sub-unit 13a, 13b for each of the two bearing journals 16 on the operator side and the drive side of the respective work rolls 7.

[0047] Alternatively or in addition to the bending device 13 for the work rolls 7, a bending device 14 for the intermediate rolls 8 may also be provided. The intermediate rolls 8 can be bent by means of the bending device 14. The bending device 14 is generally designed as a hydraulic bending device. The preceding descriptions regarding the bending of the work rolls 7 also apply analogously to the bending of the intermediate rolls 8. The bending device 14 also has separate sub-units 14a and 14b for each of the bearing journals 17 on the operator and drive sides of the two intermediate rolls 8.

[0048] The construction of the rolling mill stand 1 of FIG 3 largely corresponds to that of the rolling mill stand 1 of FIG 2 . In particular, this also applies to rolling mill stand 1 of FIG 3 The adjusting device 10 is present. Likewise, the sliding devices 11 and 12 may be present. The sliding devices 11 and 12 are in FIG 3 Not shown for clarity. Unlike rolling mill stand 1 of FIG 2 The actuators 10 to 14, 18 and 19 of the rolling stand 1, however, comprise bending force actuators 18 for an upper roll set of the rolling stand 1 and bending force actuators 19 for a lower roll set of the rolling stand 1, instead of bending devices 13, 14. The bending force actuators 18 and 19 can be controlled independently of each other. The mode of operation of the bending force actuators 18, 19 is the same as explained above for the bending devices 13, 14. However, the bending force actuators 18, 19 are supported on a fixed component 20 of the respective stand upright. The stand uprights themselves are in FIG 3 Not shown. The bending force actuators 18 allow bending of the upper work roll 7 or the upper intermediate roll 8 independently of bending of the lower work roll 7 or the lower intermediate roll 8. The bending force actuators 19 allow bending of the lower work roll 7 or the lower intermediate roll 8 independently of bending of the upper work roll 7 or the upper intermediate roll 8. The bending force actuators 17 and 18 each have a separate indexing device 18a, 18b, 19a, 19b for each of the two bearing journals 16, 17 of the corresponding work roll 7 or the corresponding intermediate roll 8.

[0049] Alternatively to the above in conjunction with the FIG 2 and 3In addition to the possible configurations of the rolling stand 1 described above, the rolling stand 1 could also be designed as a quarto stand. In this case, the rolling stand 1 has only the backup rolls 9 in addition to the work rolls 7, so that the work rolls 7 are directly supported by the backup rolls 9. In this case, the above explanations remain valid in principle. However, all aspects relating to the intermediate rolls 8 are no longer applicable.

[0050] The sliding devices 11 and 12 are generally always controlled symmetrically. The other actuators 10, 13, 14, 18, and 19 can be controlled both symmetrically and asymmetrically as required, with the control signals being additively superimposed. This is explained below for the adjusting device 10. Analogous explanations apply to the other actuators 13, 14, 18, and 19, which can be controlled both symmetrically and asymmetrically.

[0051] Assume that the adjusting device 10 is to be subjected to both a total rolling force FW and a differential rolling force δFW. The total rolling force FW is a symmetric control variable. The differential rolling force δFW is an asymmetric control variable. The total rolling force FW is distributed between the sub-devices 10a and 10b with the same sign, while the differential rolling force is distributed with opposite signs. In this case, sub-device 10a applies the partial rolling force FWa = (FW+δFW) / 2, and sub-device 10b applies the partial rolling force FWb = (FW-δFW) / 2. An analogous procedure is also possible, for example, with regard to the adjustment (i.e., position instead of force).

[0052] Under certain conditions, symmetrical controls always result in a symmetrical adjustment of the roll gap, and only asymmetrical controls result in an asymmetrical adjustment of the roll gap. Under other conditions, even a purely symmetrical control of the actuators 10 to 14, 18, 19 can result in an asymmetrical adjustment of the roll gap. Furthermore, for the bending force actuators 18, 19, a symmetrical control of an upper bending force actuator 18, for example, the upper bending force actuator 18 for the upper work roll 7, in conjunction with a similarly symmetrical control of a lower bending force actuator 19, can result in an asymmetrical effect. This is particularly true if the work rolls 7 of the upper and lower roll sets have different diameters and the intermediate rolls 8 have a ramp, a step, or a conical section at opposite ends of the respective roll barrel.This is known to experts.

[0053] At the rolling mills of the FIG 2 and 3 The upper work roll 7 has an upper diameter do, and the lower work roll 7 has a lower diameter du. The diameters do and du can, in principle, be of any value. However, the present invention demonstrates its full advantages when the diameter do of the upper work roll 7 and / or the diameter du of the lower work roll is below 350 mm, particularly between 250 mm and 300 mm. Another situation in which the present invention demonstrates its full advantages is when the diameter do of the upper work roll 7 differs from the diameter du of the lower work roll 7, particularly by more than 15 mm, 20 mm, or 30 mm. The in FIG 2 However, the values ​​shown of 295 mm for the diameter do of the upper work roll 7 and 255 mm for the diameter do of the lower work roll 7 are only purely exemplary values.

[0054] As part of the operating procedure, the control system 4 is updated according to FIG 4 First, in step S1, the stand data G of the rolling mill stand 1 is known. The stand data G describes the rolling mill stand 1 and its structure.

[0055] In step S2, the control system receives initial data A and target data Z* of the rolled material 2. The initial data A describes the rolled material 2 on the entry side of the rolling stand 1, i.e., before the rolled material 2 enters the rolling stand 1. The target data Z* are the data that the rolled material 2 should have on the exit side of the rolling stand 1, i.e., after the rolled material 2 has been rolled in the rolling stand 1. Both the initial data A and the target data Z* include at least the geometric data of the rolled material 2, i.e., its thickness, its width, its contour, and possibly also its flatness.

[0056] In step S3, the control system 4 determines symmetrical control variables sym based on the initial data A and the target data Z*, taking into account the stand data G. The symmetrical control variables sym include at least the total rolling force FW, i.e., the symmetrical control variable for the adjusting device 10 of the rolling stand 1. Furthermore, the symmetrical control variables sym include the symmetrical control variables for the other actuators 11 to 14, 18, and 19 of the rolling stand 1, provided these actuators 11 to 14, 18, and 19 are present. As a rule, in addition to the adjusting device 10, at least one bending device 13, 14, and / or at least one bending force actuator 18, 19 is present as an actuator for which a symmetrical control variable sym is determined.

[0057] In step S4, the control system determines 4 asymmetric control variables (asym). When determining these asymmetric control variables, the control system considers not only the initial data A, the target data Z*, and the framework data G, but also the symmetric control variables (sym) determined in step S3.

[0058] The control system 4 executes steps S1 to S4 before the workpiece 2 enters the rolling stand 1. The control system 4 then executes a subsequent step S5 at least at the beginning of the rolling process of the workpiece 2 in the rolling stand 1. In step S5, the control system 4 controls the actuators 10 to 14, 18, and 19 according to the determined symmetrical and asymmetrical control variables sym and asym.

[0059] In step S6, the control system 4 checks whether the rolling of the material 2 in the rolling stand 1 is complete. If not, the control system 4 returns to step S5 or step S2. If the control system 4 returns to step S5, the actuators 10 to 14, 18, 19 continue to be controlled according to the previously determined symmetric and asymmetric control variables sym, asym. If the control system 4 returns to step S2, the initial data A and the target data Z* are received again for new sections of the material 2, along with the corresponding determination of the symmetric and asymmetric control variables sym, asym. If, however, the rolling of the material 2 in the rolling stand 1 is complete, the control system 4 terminates the execution of the operating procedure in step S7.

[0060] FIG 5 shows a design of the procedure of FIG 4 . According to FIG 5 In step S11, the control system 4 is first informed of the stand data G of the rolling stand 1. In step S12, the control system 4 is informed of the initial data A and the target data Z* of the rolled material 2. In step S13, the control system 4 determines the symmetrical control variables sym. In step S14, the control system 4 determines the asymmetrical control variables asym. In step S15, the control system 4 controls the actuators 10 to 14, 18, and 19. In step S16, the control system 4 checks whether the rolling of the rolled material 2 in the rolling stand 1 is complete. If the rolling of the rolled material 2 in the rolling stand 1 is complete, the control system 4 terminates the execution of the operating procedure in step S17. Steps S11 to S17 correspond one-to-one with steps S1 to S7 of [previous step / section]. FIG 4 .

[0061] If the check in step S16 shows that the rolling of the workpiece 2 in the rolling stand 1 is not yet complete, the control system 4 proceeds to step S18. In step S18, the control system 4 checks whether it receives new values ​​for the initial data A and / or the target data Z*. If not, the control system 4 returns to step S15. Otherwise, the control system 4 proceeds to step S19.

[0062] In step S19, control system 4 determines changes δA in the initial data A and changes δZ* in the target data Z*. Control system 4 thus calculates the difference to the original values ​​that became known to control system 4 in step S2 or that are currently valid.

[0063] In step S20, the control system determines 4 changes δsym of the symmetrical manipulated variables sym. Within step S20, the control system 4 uses the framework data G as well as the changes δA of the initial data A and changes δZ* of the target data Z*.

[0064] In step S21, control system 4 determines changes δasym of the asymmetric manipulated variables asym. Within step S21, control system 4 processes the stand data G, the changes δA of the initial data A, the changes δZ* of the target data Z*, and the changes δsym of the symmetric manipulated variables sym. For example, control system 4 can first determine a change in the asymmetry of the roll gap of rolling stand 1 caused by the changes δsym of the symmetric manipulated variables sym, and then, based on the change in the asymmetry of the roll gap of rolling stand 1, determine the changes δasym of the asymmetric manipulated variables sym.

[0065] In step S22, control system 4 determines new symmetrical control variables sym by adding the changes δsym to the symmetrical control variables sym. Similarly, in step S23, control system 4 determines new asymmetrical control variables asym by adding the changes δasym to the asymmetrical control variables asym. Control system 4 then returns to step S15.

[0066] Because steps S18 to S23 are only executed after the first execution of step S15, steps S18 to S23 are performed during the rolling of the workpiece 2 in the rolling stand 1. Furthermore, the actuators 10 to 14, 18, 19 of the rolling stand 1 are controlled according to the changed symmetrical and asymmetrical control variables sym, asym.

[0067] FIG 6 shows a further development of the procedure of FIG 4 The design of FIG 6 This is feasible if a detection device 3 is located downstream of the rolling stand 1. In the example rolling mill of FIG 1 is the procedure of FIG 6 Therefore, it is only applicable to the last rolling stand 1 of the rolling mill.

[0068] According to FIG 6 In step S31, the control system 4 is first informed of the stand data G of the rolling stand 1. In step S32, the control system 4 is informed of the initial data A and the target data Z* of the rolled material 2. In step S33, the control system 4 determines the symmetrical control variables sym. In step S34, the control system 4 determines the asymmetrical control variables asym. In step S35, the control system 4 controls the actuators 10 to 14, 18, and 19. In step S36, the control system 4 checks whether the rolling of the rolled material 2 in the rolling stand 1 is complete. If the rolling of the rolled material 2 in the rolling stand 1 is complete, the control system 4 terminates the execution of the operating procedure in step S37. Steps S31 to S37 correspond one-to-one with steps S1 to S7 of FIG 4 .

[0069] If the check in step S36 shows that the rolling of the stock 2 in the rolling stand 1 is not yet complete, the control system 4 proceeds to step S38. In step S38, the control system 4 checks whether the detection device 3 has recorded a valid actual value y. If this is not the case, the strip head of the stock 2 has not yet reached the detection device 3. In this case, the control system 4 returns to step S35. Otherwise, the control system 4 proceeds to step S39.

[0070] In step S39, the control system 4 receives the actual value y. Based on this, in step S40, the control system 4 determines a symmetric component ysym and an asymmetric component yasym of the actual value y. This is possible because the actual value y is not a simple scalar, but has multiple values ​​when viewed in the width direction of the rolled material 2, i.e., it is spatially resolved.

[0071] In step S41, the control system determines 4 changes δsym of the symmetrical manipulated variables sym. Within step S41, the control system 4 uses at least the framework data G and the symmetrical component ysym of the actual value y.

[0072] In step S42, control system 4 determines changes δasym of the asymmetric control variables asym. Within step S42, control system 4 utilizes at least the stand data G, the asymmetric component yasym, and additionally the changes δsym of the symmetric control variables sym. For example, control system 4 can first determine a change in the asymmetry of the roll gap of rolling stand 1 caused by the changes δsym of the symmetric control variables sym, and then, based on the change in the asymmetry of the roll gap of rolling stand 1 plus the asymmetric component yasym, determine the changes δasym of the asymmetric control variables asym.

[0073] In step S43, the control system 4 determines new symmetrical control variables sym by adding the changes δsym to the symmetrical control variables sym. Similarly, in step S44, the control system 4 determines new asymmetrical control variables asym by adding the changes δasym to the asymmetrical control variables asym. The control system 4 then returns to step S35.

[0074] Because steps S38 to S44 are only executed after the first execution of step S35, steps S38 to S44 are performed during the rolling of the workpiece 2 in the rolling stand 1. Furthermore, the actuators 10 to 14, 18, 19 of the rolling stand 1 are controlled according to the changed symmetrical and asymmetrical control variables sym, asym.

[0075] The design of FIG 6 is considered as such, as they are in FIG 6 is shown as an alternative to the design of FIG 5 realized. However, it can also be used in addition to the design of FIG 5 This can be implemented. In this case, either a further step can precede step S38 or a further step can follow step S44. In the subsequent step, the measures described above in conjunction with FIG 5 and the steps S18 to S23 there were explained.

[0076] In many cases, the control system comprises 4 according to FIG 7A higher-level control unit 21 and a lower-level control unit 22. The higher-level control unit 21 – for example, a so-called L2 system – determines the symmetrical and asymmetrical control variables sym, asym before the rolled material 2 enters the respective rolling stand 1 and specifies these symmetrical and asymmetrical control variables sym, asym to the lower-level control unit 22. The lower-level control unit 22 – for example, a so-called L1 system – controls the actuators 10 to 14, 18 and 19 of the respective rolling stand 1 according to the determined symmetrical and asymmetrical control variables sym, asym. If necessary, the subordinate control unit 22 also determines the changes δsym, δasym of the symmetric and asymmetric control variables sym, asym and controls the actuators 10 to 14, 18 and 19 of the respective rolling stand 1 according to the changed control variables sym, asym.

[0077] The present invention has many advantages. In particular, it makes it possible to use work rolls 7 with relatively small diameters do, du, and also work rolls 7 with different diameters do, du. This also increases the service life of work rolls 7 because different diameters do, du become uncritical for the contour and flatness behavior of the rolling stands 1. For the same reason, the costs and time required for grinding the rolls 7 to 9, especially the work rolls 7, can also be reduced. Compared to a conventional control system, significantly greater dynamics can be achieved. Furthermore, the present invention can also be applied with good results even if the actual value y is not measured at the exit side of the respective rolling stand 1. The risk of strip breaks is also reduced. This is particularly important when rolling electrical steel sheets. The required dimensional length can be reduced.

[0078] Although the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by the person skilled in the art without leaving the scope of protection of the invention. Reference symbol list

[0079] 1 Rolling stands 2 Material to be rolled 3 Detection device 4 Control system 5 Control program 6 Machine code 7 Work rolls 8 Intermediate rolls 9 Backup rolls 10 Adjustment device 10a to 14a, 18a, 19a, 10b to 14b, 18b, 19b Dividing devices 11, 12 Sliding devices 13, 14 Bending devices 15 to 17 Bearing journals 18, 19 Bending force actuators 20 Fixed components 21, 22 Control devices Initial data, asymmetric control variables do, du, diameter FW, rolling force FWa, FWb, partial rolling forces G, stand data S1 to S4, 4 steps, symmetric control variables x, transport direction y, actual value yasym, ysym, components Z*, target data δA changes in initial data δasym changes in asymmetric control variables δFW difference rolling force δsym changes in symmetric control variables δZ* changes in target variables

Claims

1. Operating method for a rolling mill (1) for rolling a flat rolled stock (2) made of metal, - wherein a control system (4) for the rolling mill (1) is informed of initial data (A) and target data (Z*) of the rolled stock (2) and of the mill data (G) of the rolling mill (1) before the rolled stock (2) enters the rolling mill (1), - wherein the initial data (A) describe the rolled stock (2) on the entry side of the rolling mill (1), the target data (Z*) are data that the rolled stock (2) should have on the exit side of the rolling mill (1), and the mill data (G) describe the rolling mill (1), - wherein the control system (4) uses the initial data (A) and the target data (Z*) and takes into account the mill data (G) to determine the position of actuators (10 to 14, 18, 19) of the rolling mill before the rolled stock (2) enters the rolling mill (1). (1) determines symmetric and asymmetric control variables (sym, asym), - where the control system (4) determines the actuators (10 to 14, 18,19) at least at the beginning of the rolling of the material (2) in the rolling stand (1) according to the determined symmetric and asymmetric control variables (sym, asym), , characterized by that The control system (4) to determine the asymmetric control variables (asym) first determines the symmetric control variables (sym) and then determines the asymmetric control variables (asym) taking into account not only the initial data (A), the target data (Z*) and the framework data (G), but also the previously determined symmetric control variables (sym).

2. Operating method according to claim 1, characterized by that the actuating elements (10 to 14, 18, 19) of the rolling stand (1) comprise an adjusting device (10) and / or at least one bending device (13, 14).

3. Operating method according to claim 1, or 2, characterized by thatthe actuating elements (10 to 14, 18, 19) of the rolling stand (1) comprise at least one sliding device (11, 12) for moving rolls (7, 8) of the rolling stand (1) in opposite directions.

4. Operating method according to claim 1, 2 or 3, characterized by that the actuating elements (10 to 14, 18, 19) of the rolling stand (1) comprise independently controllable bending force actuators (18, 19) for an upper and a lower set of rolls of the rolling stand (1).

5. Operating method according to one of the above claims, characterized by that the rolling stand (1) has an upper and a lower work roll (7) and that the diameter of the upper work roll (7) and / or the lower work roll (7) is below 350 mm, in particular between 250 mm and 300 mm.

6. Operating method according to one of the above claims, characterized by thatthe rolling stand (1) has an upper and a lower work roll (7) and that the diameter (do) of the upper work roll (7) differs from the diameter (du) of the lower work roll (7), in particular by more than 15 mm, 20 mm or 30 mm.

7. Operating method according to one of the above claims, characterized by - that the control system (4) during the rolling of the rolled material (2) determines changes (δsym, δasym) of the symmetric and asymmetric control variables (sym, asym) due to a change (δA, δZ*) of the initial data (A) and / or the target data (Z*), - that the control system (4) controls the actuators (10 to 14, 18, 19) of the rolling stand (1) according to the changed control variables (sym, asym), - that the control system (4) determines the changes (δsym) of the symmetrical manipulated variables (sym) based on the changes (δA, δZ*) of the initial data (A) and / or the target data (Z*) taking into account the framework data (G) and - that the control system (4) determines the changes (δasym) of the asymmetric control variables (asym) based on the changes (δA, δZ*) of the initial data (A) and / or the target data (Z*) taking into account the framework data (G) and additionally taking into account the changes (δsym) of the symmetric control variables (sym).

8. Operating method according to one of the above claims, characterized by - that the control system (4) receives a measured actual value (y) of the rolled material (2) directly at the exit side of the rolling stand (1) during the rolling of the rolled material (2), wherein the actual value (y) describes the contour and / or the flatness of the rolled material (2), - that the control system (4) determines a symmetric and an asymmetric component (ysym, yasym) of the actual value (y), - thatthe control system (4) determines changes (δsym, δasym) of the symmetric and asymmetric control variables (sym, asym) and controls the actuators (10 to 14, 18, 19) of the rolling stand (1) according to the changed control variables (sym, asym), - that the control system (4) determines the changes (δsym) of the symmetrical manipulated variables (sym) based on the symmetrical component (ysym) of the actual value (y) and - that the control system (4) determines the changes (δasym) of the asymmetric control variables (asym) based on the asymmetric component (yasym) of the actual value (y) and the changes (δsym) of the symmetric control variables (sym).

9. Operating method according to claim 7 or 8, characterized by thatthe control system (4) for determining the changes (δasym) of the asymmetric control variables (asym) determines a change in an asymmetry of a roll gap of the rolling stand (1) caused by the changes (δsym) of the symmetric control variables (sym) and determines the changes (δasym) of the asymmetric control variables (asym) based on the change in the asymmetry of the roll gap of the rolling stand (1).

10. Operating method according to claim 7, 8 or 9, characterized by - that the control system (4) comprises a superior and a subordinate control unit (21, 22), - that The higher-level control unit (21) determines the symmetrical and asymmetrical control variables (sym, asym) before the rolled material (2) enters the rolling stand (1) and specifies the determined symmetrical and asymmetrical control variables (sym, asym) to the lower-level control unit (22) and - thatthe subordinate control device (22) controls the actuators (10 to 14, 18, 19) of the rolling stand (1) according to the determined symmetric and asymmetric control variables (sym, asym), determines the changes (δsym, δasym) of the symmetric and asymmetric control variables (sym, asym) and controls the actuators (10 to 14, 18, 19) of the rolling stand (1) according to the changed control variables (sym, asym).

11. Control program for a software-programmable control system (4), wherein the control program comprises machine code (6) that can be directly executed by the control system (4), wherein the execution of the machine code (6) by the control system (4) causes the control system (4) to control a rolling stand (1) for rolling a flat rolled stock (2) made of metal according to an operating method according to one of the above claims.

12. Control system for a rolling stand (1) for rolling a flat rolled material (2) made of metal, wherein the control system is programmed with a control program (5) according to claim 11, such that the control system controls the rolling stand (1) according to an operating method according to one of claims 1 to 10.

13. Rolling device, - wherein the rolling device comprises a rolling stand (1) for rolling a flat rolled stock (2) made of metal, - wherein the rolling stand (1) comprises actuators (10 to 14, 18, 19) for adjusting a roll gap of the rolling stand (1) according to symmetrical and asymmetrical control variables (sym, asym), - wherein the rolling device comprises a control system (4), - wherein the control system (4) is configured as a control system (4) according to claim 12, which controls the rolling stand (1) according to an operating method according to any one of claims 1 to 10.

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