Reduction of tension-induced changes in thickness during rolling

Abstract

The flat metal material (2) to be rolled is rolled in a roll stand (1). A position controller (6) for controlling the positioning of an actuator (5) for setting the roll gap of the roll stand (1) determines an actuation variable (q) for the actuator (5) as a function of the obtained position target value (s*) and the position actual value (s) of the actuator (5) and drives the actuator (5) accordingly. The obtained position target value (s*) is determined by using the obtained reference target value (s1*). The obtained reference target value (s1*) is determined as the sum of an initial reference target value (s0*) and an additional target value (δs1*). The additional target value (δs1*) is determined by a determining element (13) by using the inlet actual tension (ZE) and the inlet reference tension (ZER) and / or by using the outlet actual tension (ZA) and the outlet reference tension (ZAR). Instead of the actual tensions (ZE, ZA), the corresponding target tensions (ZE*, ZA*) of the corresponding tension control operation can also be used, but in either case the reference tensions (ZER, ZAR) are variables different from the target tensions (ZE*, ZA*).

Description

[Technical Field]

[0001] The invention is based on a method for operating a roll stand for rolling flat metal stock, in which a position regulator for adjusting the positioning of an actuator for setting the roll gap of the roll stand determines an actuation variable for the actuator as a function of an obtained position target value and an actual position value of the actuator and actuates the actuator accordingly, the obtained position target value being determined by use of an obtained reference target value, the obtained reference target value being determined as the sum of an initial reference target value and an additional target value.

[0002] In the simplest case, the resulting position target is the same as the resulting reference target, which is generally independent of the inlet and outlet tensions.

[0003] The invention is further based on a control system for a roll stand for rolling flat metal stock, the control system being formed by hardware blocks and / or software programs so as to implement such an operating method during operation.

[0004] The invention is further based on a rolling unit for rolling flat metal stock, the rolling unit having a roll stand for rolling the flat metal stock and such a control system. [Background technology]

[0005] When rolling flat metal stock, one of the basic requirements of the rolling process is to produce a flat stock with a thickness that corresponds as closely as possible to the predetermined target thickness. The thickness of the stock leaving the roll stand is set, among other things, via the roll gap. The size of the roll gap is then set by the corresponding setting of the actuator to a specific position.

[0006] The size of the roll gap, and therefore the thickness of the existing rolled material, is not, however, fixed solely by the position of the actuator. Instead, the deflection of the roll stand must be considered in addition to wear, thermal crowning, roll displacement, and possibly other influences. The deflection is the result of the rolling force and other forces, such as bending forces, acting on the roll stand.

[0007] In many cases, roll stands are manipulated by adjusting the roll gap. In such cases, the exit thickness to which the rolled material will be rolled in the roll stand is initially determined in a pass schedule. The associated predicted rolling force is further determined taking into account the parameters of the rolled material (e.g., its width, its entry thickness, its temperature, and other variables). The associated deflection of the roll stand is determined through the use of a spring model of the roll stand. Position targets for the actuators are then determined taking into account the deflection of the roll stand and other variables, such as wear-induced and / or temperature-induced crowning.

[0008] When rolling a rolled material, the actual rolling force is measured directly or determined based on measured variables. Correction values ​​are determined by the AGC (Automatic Gauge Control). The correction values ​​are determined within the AGC via a spring model of the roll stand.

[0009] Flat metal stock is often rolled such that, while being rolled in a roll stand, the stock is tensioned in an upstream device upstream from the roll stand and / or in a downstream device downstream from the roll stand. Consequently, entry tension can be applied to the stock upstream from the roll stand, and exit tension can be applied to the stock downstream from the roll stand. To better maintain entry and exit tensions, respective loop lifters can be located upstream and / or downstream from the roll stand. If the roll stand is part of a multi-stand rolling line but is not the first roll stand in the rolling line, the upstream device can also be another roll stand in the multi-stand rolling line. Similarly, if the roll stand is part of a multi-stand rolling line but is not the last roll stand in the rolling line, the downstream device can also be another roll stand in the multi-stand rolling line. In other designs, the upstream and / or downstream device can also be a coiler, for example, in the case of a Steckel mill. Other embodiments are possible.

[0010] The exit tension, and to an even greater extent the entry tension, have an influence on the rolling force. In particular, the higher the tension, the lower the required rolling force. The roll stand deflects less at lower rolling forces. If the reduced deflection is not taken into account, the tension therefore influences the thickness to which the rolled material is rolled in the roll stand.

[0011] In principle, this does not present a problem, since changes in the rolling force are measured and the deflection changes affected by the force changes are corrected via the AGC described above. However, the AGC requires a considerable period of time to correct the deflection of the roll stand. The correction value is therefore applied only with a delay. Furthermore, compensation by the AGC is often only considered in a damped manner, since otherwise there is a risk of simultaneously correcting the positioning by the AGC and updating the tension by the tensioning system, which could cause vibrations and instability. Finally, the correction value determined by the AGC is often subject to errors, for example, due to frictional hardening in the roll stand or due to dead zones.

[0012] Furthermore, it is common practice to switch on the AGC only after the initial pass, i.e., with a delay. During the initial pass, the exit tension is zero because the leading edge of the rolled material has not yet reached the downstream device that, in conjunction with the roll stand, can apply exit tension to the rolled material. However, it is entirely possible for the entry tension to have a value other than zero. If the entry tension changes in such a case, this will affect the rolling force and therefore the deflection of the roll stand. However, because the AGC is switched on only after the initial pass, changes in the thickness of the rolled material in the roll stand, caused by the changed deflection of the roll stand, are not corrected during the initial pass.

[0013] Similarly, it is common practice to freeze the AGC (i.e., the correction value determined at the time of freezing is no longer updated) before the initial pass or to limit the time during which the correction value changes. During the final pass, the entry tension is zero because the tail of the rolled material has already left the upstream device that, together with the roll stand, can apply entry tension to the rolled material. However, there is a general possibility that the exit tension will have a value other than zero. If the exit tension changes in such a case, this will affect the rolling force and therefore the deflection of the roll stand. However, since the AGC is frozen before the final pass and the time during which the correction value determined by the AGC can change is limited, the change in thickness of the rolled material in the roll stand, caused by the changed deflection of the roll stand, is not corrected, or only insufficiently corrected, during the final pass.

[0014] Patent Document 1 discloses an operating method of the type mentioned at the beginning. In this operating method, an additional target positioning value added to an actual target positioning value is determined by a tension regulator that adjusts the actual input tension to the target input tension. The actual target positioning value is the target roll gap value.

[0015] Patent Document 2 also discloses an operating method of the type mentioned at the beginning, in which an additional target positioning value added to an actual target positioning value is determined by a tension regulator that adjusts the actual output tension to the target output tension, and the actual target positioning value is the target roll gap value.

[0016] Patent Document 3 also discloses a method for operating a roll stand for rolling flat metal stock. This method includes, as part of the method, mass flow control that acts on the roll stand positioning system. The thickness of the rolled stock exiting the roll stand is set as a result. In this method, a tension regulator that adjusts the input-side actual tension to the input-side target value acts on the roll stand positioning system. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] EP3231522A1 [Patent Document 2] Patent Publication No. 2003-164906 [Patent Document 3] EP2620233A1 [Non-patent literature]

[0018] [Non-Patent Document 1] "On the theory of rolling" by J.M. Alexander, published in the Proceedings of the Royal Society of London, Vol. 326, pp. 535-563 (1972) Summary of the Invention [Problem to be solved by the invention]

[0019] The object of the invention consists in providing an option that makes it possible to ensure a better maintenance of the thickness of the rolled material at the exit side of the roll stand. [Means for solving the problem]

[0020] This object is achieved by a method for operating having the characteristics of claim 1. Advantageous embodiments of the method for operating are the subject matter of dependent claims 2 to 12.

[0021] According to the present invention, an operating method of the type described at the beginning is configured such that the additional target value is determined by the determining element by using the inlet-side actual tension or a corresponding target tension and the inlet-side reference tension of the inlet-side tensioning system and / or by using the outlet-side actual tension or a corresponding target tension and the outlet-side reference tension of the outlet-side tensioning system, the inlet-side reference tension being a variable different from the inlet-side target tension and / or the outlet-side reference tension being a variable different from the outlet-side target tension.

[0022] The actual inlet tension and / or the actual outlet tension may be actual values ​​measured using measurement techniques or may be values ​​determined based on values ​​measured using measurement techniques. Tensioning systems are generally sufficiently powerful and high quality that the actual and target values ​​coincide to a sufficient extent to allow the use of either the actual or target values.

[0023] The roll stand is generally operated by adjusting the roll gap. Furthermore, the inlet tensioning system generally acts on the roll peripheral speed at which the flat rolled material is rolled in the roll stand and / or on the feed speed at which the flat rolled material leaves a device located upstream from the roll stand. Similarly, the outlet tensioning system generally acts on the roll peripheral speed and / or on the discharge speed at which the flat rolled material enters a device located downstream from the roll stand. The tensioning systems generally act on only one device in each case, i.e., either the upstream device or the roll stand, or either the roll stand or the downstream device.

[0024] If there is a dependence of the additional target value on the inlet-side tension state (target or actual), the additional target value is preferably determined by a determination element based on the product of the inlet-side sensitivity and the difference between the inlet-side actual tension or the corresponding target tension and the inlet-side reference tension. Similarly, if there is a dependence of the additional target value on the outlet-side tension state, the additional target value is preferably determined by a determination element based on the product of the outlet-side sensitivity and the difference between the outlet-side actual tension or the corresponding target tension and the outlet-side reference tension. The determination of the additional target value, and thus the resulting basic target value, is therefore particularly simply configured.

[0025] The additional setpoint value is preferably determined by the determining element based on the product of the inlet sensitivity and the difference between the inlet actual tension or the corresponding setpoint tension and the inlet reference tension and / or based on the product of the outlet sensitivity and the difference between the outlet actual tension or the corresponding setpoint tension and the outlet reference tension. In this way, the additional setpoint value can be determined particularly simply and reliably.

[0026] Preferably, the inlet and / or outlet sensitivities are specified for the determinants by a higher level control device.

[0027] The corresponding sensitivities can be stored in the high-level control device, for example in the form of a table. The corresponding sensitivities can be stored in the table depending on the geometry and other properties of the rolled material (for example, its chemical composition and its temperature). However, it is preferred if the entry and / or exit sensitivities are determined by the high-level control device as part of the pass schedule calculation by analysis of a rolling model. The rolling model is based on mathematical physical equations that describe the rolling procedure in a roll stand. Therefore, a very accurate determination of the entry and / or exit sensitivities is possible. The rolling model can be iteratively adapted as needed.

[0028] The mathematical physical equations of the rolling model are generally differential and / or algebraic equations. Such models are widely known to those skilled in the art. By way of example only, reference may be made to "Rolling Models: A New Approach to Rolling Models," IEEE Transactions on Mechanical Engineering, Vol. 1, No. 1, pp. 111-114, 2002.

[0029] Similarly, the inlet reference tension and / or the outlet reference tension may also be specified for the determining element by a higher level control device, and the corresponding reference tension may be determined or set by the higher level control device as part of the pass schedule calculation.

[0030] The operating method is preferably configured such that the high-level control device determines, for example as part of a pass schedule calculation, an initial reference target value and an inlet-side target tension and / or an outlet-side target tension based on the target thickness at which the flat rolled material will exit the roll stand and the inlet-side reference tension and / or the outlet-side reference tension, specifies the initial reference target value for the adjustment unit having a position regulator and a determination element, specifies the inlet-side target tension for a pre-tension regulator that adjusts the inlet-side actual tension to the inlet-side target tension, and / or specifies the outlet-side target tension for a post-tension regulator that adjusts the outlet-side actual tension to the outlet-side target tension.

[0031] The resulting position target value is preferably determined at least during rolling of the center of the rolled material by using a correction value determined by using the actual rolling force, so that AGC is implemented. Therefore, it is possible to combine the operating method according to the invention with AGC.

[0032] The resulting reference target value is preferably taken into account as part of the determination of the correction value in addition to the actual rolling force, which may be improved as a result when determining the correction value.

[0033] The resulting position target value is preferably determined during rolling at least the head of the rolled material and / or the tail of the rolled material without using the actual rolling force, in which case the invention also compensates for tension and rolling force changes that occur when the AGC is not activated.

[0034] The latter procedure can also be combined with a procedure in which the AGC is active during rolling, especially in the center of the rolled stock. In this case, the AGC can be switched on at the transition from rolling the head of the rolled stock to rolling the center. Similarly, the AGC can be switched off (frozen or limited in its changes) at the transition from rolling the center to rolling the tail of the rolled stock.

[0035] The resulting position target value is preferably determined by using the deviation of the thickness of the rolled material measured at the exit side of the roll stand from the target thickness, and any remaining errors can be corrected as a result.

[0036] The object is further achieved by a control system having the characteristics of claim 13. According to the invention, the control system implements the operating method according to the invention during operation using hardware blocks and / or software programs.

[0037] The object is further achieved by a rolling unit having the characteristics of claim 14. According to the invention, a control system is designed as a control system according to the invention for a rolling unit of the type mentioned at the beginning.

[0038] The above-mentioned features, characteristics and advantages of the present invention, and the manner in which they are achieved, will become more apparent and more readily understandable in conjunction with the following description of exemplary embodiments, which are set forth in detail in connection with the diagrammatically illustrated drawings. [Brief explanation of the drawings]

[0039] [Figure 1] FIG. 1 shows a roll stand and its control system. [Figure 2] FIG. 2 illustrates a roll assembly in a first operational state. [Figure 3] FIG. 3 shows the roll assembly from FIG. 2 in a second operational state. [Figure 4] FIG. 3 shows the roll assembly from FIG. 2 in a third operational state. [Figure 5] FIG. 2 is a diagram showing the structure of an adjustment unit. [Figure 6] FIG. 1 illustrates decision elements. [Figure 7] FIG. 6 shows additions to the adjustment unit from FIG. 5. [Figure 8] FIG. 8 shows a modification to the addition from FIG. 7. [Figure 9] FIG. [Figure 10] FIG. 6 shows an embodiment of the adjustment unit from FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0040] In FIG. 1, the rolled material 2 is rolled in a roll stand 1. Only the working rollers of the roll stand 1 are shown in FIG. 1 (and may also be shown in other figures). However, the roll stand 1 generally has at least a backup roller in addition to the working rollers (4 high stand), possibly intermediate rollers arranged between the working rollers, and a backup roller in addition to the backup rollers (6 high stand). The rolled material 2 is often made of metal, often steel, often aluminum, but rarely another metal, for example copper. The rolled material 2 may also be flat rolled material, i.e., strip (standard) or plate (exception).

[0041] The roll stand 1 is generally operated by adjusting the roll gap. Furthermore, the rolled material 2 is rolled in the roll stand 1 at a rolling surface speed vU. The associated drives and their operation are not shown.

[0042] According to the illustrations in FIGS. 2 and 3, the rolled material 2 can be held in a device 3 upstream from the roll stand 1 while being rolled in the roll stand 1. In this case, the rolled material 2 leaves the upstream device 3 with a feed speed vZ. Furthermore, an inlet effective tension ZE is applied to the rolled material 2 at the inlet side of the roll stand 1. A loop lifter can be arranged between the upstream device 3 and the roll stand 1. The loop lifter is not shown. The upstream device 3 can be designed according to the illustrations in FIGS. 2 and 3, in particular as a separate roll stand. However, it can have a different design, for example as a coiler or as a set of drive rollers. The feed speed vZ is shown in FIG. 2 as a peripheral speed. If the upstream device 3 is a roll stand, a forward slip must additionally be taken into account.

[0043] The inlet actual tension ZE is generally adjusted to a corresponding target tension ZE* by a corresponding tension adjustment system. In this case, the inlet actual tension ZE and the inlet target tension ZE* are supplied to the pre-tension regulator 24. Using the inlet actual tension ZE and the inlet target tension ZE*, and usually using the distance between the two tensions ZE, ZE*, the pre-tension regulator 24 determines a pre-actuation variable δvE applied to the actuator so that the inlet actual tension ZE is the same as or at least approximates the inlet target tension ZE*. The pre-actuation variable δvE can in particular be a speed additive target value acting on the roll peripheral speed vU or, in the reverse representation, on the feed speed vZ.

[0044] Similarly, the rolled material 2 can be held in a device 4 downstream from the roll stand 1 while being rolled in the roll stand 1, as shown in Figures 3 and 4. In this case, the rolled material 2 enters the downstream device 4 with a discharge speed vA. Furthermore, an exit-side actual tension ZA is applied to the rolled material 2 at the exit side of the roll stand 1. A loop lifter can also be arranged between the roll stand 1 and the downstream device 4. This loop lifter is also not shown. The downstream device 4 can be designed specifically as a separate roll stand according to the diagrams in Figures 3 to 5. However, it can have a different design, for example as a coiler or as a set of drive rollers. The discharge speed vA is shown as a peripheral speed in Figures 3 and 4. If the downstream device 4 is a roll stand, a rear slip must additionally be taken into account.

[0045] The actual outlet tension ZA is generally adjusted to a corresponding target tension ZA* by a corresponding tension adjustment system. In this case, the actual outlet tension ZA and the target outlet tension ZA* are supplied to the post-tension regulator 25. Using the actual outlet tension ZA and the target outlet tension ZA*, and usually the distance between the two tensions ZA, ZA*, the post-tension regulator 25 determines a post-actuating variable δvA applied to the actuator so that the actual outlet tension ZA is the same as or at least approximates the target outlet tension ZA*. The post-actuating variable δvA can in particular be a speed additive target value acting on the roll peripheral speed vU or, in the reverse representation, on the discharge speed vA.

[0046] The roll stand 1 generally has a number of actuators that influence the rolling process. Examples of such actuators are bending systems that can set the roll bending, displacement devices that can axially displace a pair of rolls in opposite directions, roll cooling systems, roll gap lubrication systems, and many others. Within the scope of the present invention, this is essentially the actuator 5 (see FIG. 5) that sets the roll gap of the roll stand 1. Therefore, more details are given below only regarding this actuator 5 and its operation.

[0047] To regulate the positioning of the actuator 5, a position setpoint s* is specified to a position regulator 6 of a regulating unit 7. An actual value s of the actuator 5 is further supplied to the position regulator 6. As a function of these two variables s*, s, the position regulator 6 determines an actuation variable q for the actuator 5 and controls the actuator 5 accordingly. The regulating unit 7 is an essential component of the control system according to the invention.

[0048] The actuator 5 is generally designed as a hydraulic cylinder unit according to the diagram in FIG. 5. In this case, the actuation variable q acts on a hydraulic system 8, which applies a high actuation pressure pP (= pump pressure) or a low actuation pressure pT (= tank pressure) to the actuation chambers 9, 10 of the hydraulic cylinder unit as required. The actuation variable q can in this case be the conveyed hydraulic flow. In particular in this embodiment, the position regulator 6 can be designed as a proportional regulator (P regulator) according to the diagram in FIG. 5. In rare cases, it is also possible to adjust the roll gap by means of an electric drive acting on the screw instead or in addition. In such cases, the position regulator 6 is often designed as a proportional-integral regulator (PI regulator).

[0049] The resulting position target value s* is determined by use of the resulting reference target value s1*. In the embodiment according to Fig. 5, the resulting position target value s* is identical to the resulting reference target value s1*. However, other variables can also be included in the resulting position target value s*. This will become more clear from further explanations. The resulting reference target value s1* is determined by use of the inlet actual tension ZE and / or the outer actual tension ZA.

[0050] According to the diagram of Fig. 5, the resulting reference target value s1* is determined in the nodal point 11 as the sum of the initial reference target value s0* and the additional target value δs1*. The initial reference target value s0* is, at least generally, independent of the actual inlet-side tension ZE and the actual outlet-side tension ZA. In contrast, the additional target value δs1* depends on the actual inlet-side tension ZE and the actual outlet-side tension ZA. In particular, the additional target value δs1* is determined by the determining element 13 using the actual inlet-side tension ZE and the inlet-side reference tension ZER. Alternatively or additionally, the additional target value δs1* can be determined by the determining element 13 using the actual outlet-side tension ZA and the outlet-side reference tension ZAR.

[0051] To determine the additional setpoint value δs1*, the inlet actual tension ZE can be supplied, for example, to a decision block 12 of the decision element 13, according to the diagram of Fig. 6. In this case, the inlet component δs1E* of the additional setpoint value δs1* is determined in the decision block 12 by use of the inlet actual tension ZE and the inlet reference tension ZER. For example, the inlet component δs1E* can be determined according to the diagram of Fig. 6 by the following formula: δs1E*=SE·(ZE-ZER) (1) where SE is the input sensitivity. The input reference tension ZER can optionally have a value of 0. In certain cases, it may be more variable over time. In this case, it is generally also necessary to change the initial reference target value to the corresponding range.

[0052] The input sensitivity SE and the input reference tension ZER can be specified to the decision element 13 by a higher-level control device 14, for example according to the diagram in Figure 1. The control device 14, if present, is another basic component of the control system.

[0053] Similarly, in order to determine the additional setpoint value δs1*, the outlet-side actual tension ZA is supplied, for example, to a decision block 15 of the decision element 13, according to the diagram of Fig. 6. In this case, the outlet-side component δs1A* of the additional setpoint value δs1* is determined in the decision block 15 by use of the outlet-side actual tension ZA and the outlet-side reference tension ZAR. For example, the outlet-side component δs1A* can be determined according to the diagram of Fig. 6 by the following formula: δs1A*=SA·(ZA-ZAR) (2) where SA is the output-side sensitivity. The outlet-side sensitivity SA and the outlet-side reference tension ZAR can likewise be specified to the decision element 13 by the higher-level control device 14 according to the diagram of FIG. 1. The input-side reference tension ZAR can optionally have the value 0. In certain cases, it may be more variable over time. A similar method of changing the input-side reference tension ZER may require changing the initial reference target value s0* at one end of the outlet-side reference tension ZAR in a corresponding range.

[0054] It is also possible to use only one of the two tensions ZE, ZA. In this case, the additional setpoint value δs1* is identical to the corresponding components δs1E*, δs1A*. However, generally both tensions ZE, ZA are used. In the case of linearized determination, the determination element 13 has a nodal point 16 at which the additional setpoint value δs1* is determined as the sum of the two components δs1E*, δs1A*. Furthermore, instead of the actual values ​​ZE, ZA, it is possible to use the associated setpoint values ​​ZE*, ZA*.

[0055] The target tensions ZE*, ZA*, i.e., the target values ​​ZE*, ZA*, supplied to the associated tension regulators 24, 25 and thus effective for the tensioning system, are variables different from the reference tensions ZER, ZAR. While this approach allows for the target tensions ZE*, ZA* to be derived from the reference tensions ZER, ZAR, there is no identity between them. While certain values ​​may be the same temporarily, this is not systematically or consistently the case.

[0056] Thus, for example, the target tensions ZE*, ZA* can be specified by an operator (not shown) or can be changed by the operator during rolling of the flat rolled material 2. In contrast, the reference tensions ZER, ZAR cannot be changed by the operator. Furthermore, while maintaining the reference tensions ZER, ZAR, the target tensions ZE*, ZA* can be changed over time by the higher-level control device 14 for technical reasons. This will be explained in more detail below with the help of an example. In this example, the upstream device 3 and the downstream device 4 are roll stands, which are also arranged upstream from the upstream device 3 and downstream from the downstream device 4.

[0057] The leading edge 20 of the rolled material 2 (see FIG. 2) reaches the roll stand 1 at time t1, the downstream device 4 at time t2, and a roll stand disposed downstream from the downstream device 4 at time t3. Similarly, for example, the tail 21 of the rolled material 2 (see FIG. 4) reaches the roll stand disposed upstream from the upstream device 3 at time t4, the upstream device 3 at time t5, and a roll stand at time t6. Time t4 is generally after time t3.

[0058] 2 shows the rolling process at time t1 when the rolled stock 2 is being rolled. The inlet actual tension ZE can be applied after time t1, whereas this is not possible before time t1. The inlet actual tension ZE is therefore always zero before time t1. The outlet actual tension ZA is also zero, since the rolled stock 2 is not yet located at the outlet of the roll stand 1, in particular, the rolled stock 2 has not yet reached the downstream device 4.

[0059] Similarly, Figure 4 shows the rolling process at time t6 when the rolled stock 2 is being rolled. Up to time t6, the exit actual tension ZA can be further applied, but after time t6 this is no longer possible. The actual tension ZA is therefore always zero after time t6. Since the rolled stock 2 at the entrance of the roll stand 1 is gone, in particular having left the upstream device 3 a long time ago, the entrance actual tension ZE is also zero.

[0060] 3 shows a rolling process in which the rolled material 2 is rolled between times t1 and t6, more precisely between times t2 and t5. Respective actual tensions ZE, ZA are applied to the rolled material 2 on at least one side (i.e., on the inlet or outlet side) during this period, and also on both sides (i.e., on the inlet and outlet sides) during part of this period.

[0061] In a static state in which the rolled material 2 is being rolled in all of the roll stands in the above example, the target tensions ZE*, ZA* can correspond to the reference tensions ZER, ZAR, i.e., have the same value. This static state for the specification of the target values ​​ZE*, ZA* for the tension regulators 24, 25 exists between times t3 and t4.

[0062] On the other hand, the post-tension regulator 25 may, for example, essentially not be operating during the period between times t1 and t2, since the actual outlet tension ZA cannot be applied to the rolled material 2 at the outlet side of the roll stand 1. On the other hand, it is absolutely possible to determine the outlet component δs1A* of the additional setpoint value δs1* during this period as well. Furthermore, although the pre-tension regulator 24 may be operating during this period, the corresponding setpoint value ZE* = ZER is not immediately supplied to the pre-tension regulator 24 at time t1 (or shortly thereafter); instead, the setpoint value ZE* may be ramped up from 0 to the value of the corresponding reference tension ZER.

[0063] Similarly, although the post-tension regulator 25 operates during the period between time t2 and time t3, the corresponding target value ZA*=ZAR is not immediately supplied to the post-tension regulator 25 at time t2 (or shortly thereafter); instead, the target value ZA* may be ramped up from 0 to the value of the corresponding reference tension ZAR.

[0064] Similarly, while the pre-tension regulator 24 operates during the period between time t4 and time t5, the target value ZE* supplied to the pre-tension regulator 24 may be ramped down from a value ZE*=ZER present at the beginning of the period to a value of 0 during the period.

[0065] Furthermore, the pre-tension regulator 24 may essentially not operate during the period between times t5 and t6, since the inlet-side actual tension ZE cannot be applied to the rolled material 2 at the inlet side of the roll stand 1. However, it is absolutely possible to determine the inlet-side component δs1E* of the additional setpoint value δs1* during this period. Furthermore, the post-tension regulator 25 may operate during this period, but the setpoint value ZA* supplied to the post-tension regulator 25 may be ramped down during this period from the value ZA*=ZAR present at the beginning of the period to the value 0.

[0066] Further values ​​such as the inlet sensitivity SE and / or outlet sensitivity SA, and possibly the reference tensions ZER and / or ZAR and / or initial reference target value s0* may also be provided by the higher level control device 14.

[0067] The regulator makes real-time adjustments during the rolling of the rolled material. The regulator as a whole is usually referred to by experts as an L1 system. The high-level control device 14 therefore acts as a unit which is usually referred to by experts as an L2 system. According to the diagram of FIG. 1, the high-level control device 14 comprises, inter alia, a rolling model 17 in which the rolling procedure in the roll stand 1 is modeled. The rolling model 17 is based on mathematical physical equations which describe the rolling procedure. By analyzing the rolling model 17, the high-level control device 14 determines said variables SE and / or SA and / or ZER and / or ZAR and / or s0*, and possibly also further variables.

[0068] For example, the high-level control device 14 performs a pass schedule calculation in which these and other values, if necessary, are determined before the rolled stock 2 is rolled in the roll stand 1. The determined values ​​are made available by the high-level control device 14 to a lower-level regulator (e.g., to the position regulator 6 of the regulating unit 7). In particular, as part of the pass schedule calculation, the high-level control device 14 determines an initial reference target value s0* and an entry target tension ZE* and / or an exit target tension ZA* based on a target thickness d* (see FIG. 1 ) at which the flat rolled stock 2 will exit the roll stand 1, as well as an entry reference tension ZER and / or an exit reference tension ZAR. The target thickness d* can alternatively be specified for the high-level control device 14 or can be determined independently by the high-level control device 14. The reference tensions ZER and ZAR are generally set by the high-level control device 14. Based on these values ​​d*, ZER, and ZAR, the high-level control device 14 determines the required rolling force and the required positioning. The required rolling force corresponds to a reference rolling force FR, and the required positioning corresponds to an initial reference target value s0*. The initial reference target value s0* is specified by a high-level control device 14 of the adjustment unit 7. The high-level control device 14 also specifies an inlet-side target tension ZE* for the front tension regulator 24 and an outlet-side target tension ZA* for the rear tension regulator 25.

[0069] The high-level control device 14 can determine the entry sensitivity SE, for example, by determining the effect of a change in the entry tension ZE on the intended operating point of the roll stand 1, the actual rolling force F, and further the effect of a change in the rolling force F on the deflection of the roll stand 1. The product of these two effects gives the entry sensitivity SE. Similarly, the high-level control device 14 can determine the exit sensitivity SA by determining the effect of a change in the exit tension ZA on the intended operating point of the roll stand 1, the rolling force F, and further the effect of a change in the rolling force F on the deflection of the roll stand 1. The product of these two effects gives the exit sensitivity SA. In a completely equivalent manner, it is also possible to specify basic variables for the sensitivities SE and SA for the determiner 13, namely, the effect of a change in the entry tension ZE on the actual rolling force F, the effect of a change in the exit tension ZA on the rolling force F, and the effect of a change in the rolling force F on the deflection of the roll stand 1. In this case, the determiner 13 can determine the sensitivities SE and SA itself. Furthermore, the determining element 13 can in this case in particular also determine the change δF in the predicted rolling force corresponding to the change in the tensions ZE, ZA.

[0070] The resulting position target value s* is generally not identical to the resulting reference target value s1*, but instead is determined by the use of another correcting variable.

[0071] Thus, according to the diagram of FIG. 7, for example, the resulting position target value s* can be determined by using a correction value δs2* determined by using the rolling force F. For example, the resulting position target value s* can be determined at node point 18 as the sum of the resulting reference target value s1* and the correction value δs2*. The correction value δs2* is then determined in decision block 19 by using the actual rolling force F. Decision block 19 therefore implements an AGC in which additional deflections of the roll stand 1 are (at least largely) compensated for. The additional deflections of the roll stand 1 result from the deviation of the actual rolling force F from the reference rolling force FR. It should be noted that for clarity, only additional parts of the regulating unit 7 are illustrated in FIG. 7. FIGS. 5 and 6 should be used as reference for the basic design of the regulating unit 7.

[0072] In the simplest case, only the actual rolling force F and the reference rolling force FR are supplied as input variables to the decision block 19. According to the diagram of FIG. 1, the reference rolling force FR is provided by the high-level control device 14. However, in many cases, in addition to the actual rolling force F, a value is also supplied to the decision block 19 that already corresponds to the obtained position target value s*, apart from the correction value δs2* determined by the decision block 19. For example, the obtained reference target value s1* can be supplied to the decision block 19. In this case, as part of the determination of the correction value δs2*, the decision block 19 also takes into account the obtained reference target value s1*. Furthermore, in this case, the decision element 13 also determines an associated predicted change δF in the reference rolling force FR in addition to the additional target value δs1*. The predicted change δF in the reference rolling force FR is taken into account by the decision block 19 when the correction value δs2* is determined. In addition, the position actual value s may also be supplied to the decision block 19.

[0073] The procedure described in connection with Figure 7 is carried out continuously in the roll stand 1 while the stock 2 is being rolled. As part of this, the correction value δs2* is determined and updated independently of whether this portion of the stock 2 is being rolled. However, in many cases, the correction value δs2* is determined and applied while the center portion of the stock 2 is being rolled. In contrast, during the rolling of the head 20 and / or tail 21 of the stock, the resulting position target value s* is often determined by use of the actual rolling force F. This is described in more detail below in connection with Figures 8 and 9, with additional reference to Figures 2 to 4.

[0074] 8 is based on the regulating unit 7 from FIG. 7. In FIG. 8, an actuation signal A and a reset signal R can be supplied to a decision block 19. The actuation signal A has the value 0 or the value 1 in FIG. 9. A value of 1 for the actuation signal A results in the actuation of the decision block 19. In this case, the decision block 19 determines the respective effective correction value δs2* by using the rolling force F. As a result, the resulting position setpoint value s* is therefore determined by using the rolling force F. A value of 0 for the actuation signal A results in the actuation of the decision block 19. In this case, the decision block 19 outputs the last determined correction value δs2* but does not further update the correction value δs2*. As a result, the resulting position setpoint value s* is therefore determined without using the rolling force F. The reset signal R is supplied to the decision block 19 only if no rolled material is being rolled in the roll stand 1. Supplying the reset signal R resets the last determined correction value δs2* to 0.

[0075] The actuation signal A varies as a function of time t. Up to time t1, the actuation signal A has a zero value 0. It then rises, generally abruptly, to the value 1. At time t6, the actuation signal A falls again, generally abruptly, to the value 0. At time t7, after time t6 in FIG. 9, the reset signal R is asserted (for a short period of time).

[0076] FIG. 10 shows another embodiment of the adjusting unit 7 from FIG. 5. However, the embodiment from FIG. 10 can also be based directly on the embodiment of the adjusting unit 7 from FIGS. 7 and 8. In FIG. 10, the thickness d of the rolled material 2, i.e., its actual value, is measured at the exit side of the roll stand 1 by a corresponding measuring device 22. The thickness d is compared with the target thickness d* in a decision block 23. A correction variable δs3* is determined in the decision block 23 based on the deviation of the thickness d of the rolled material 2 from the target thickness d*. The correction variable δs3* is supplied to the nodal point 18. The resulting position target value s* is therefore also determined using the correction variable δs3*. Residual errors of all types can be compensated for by this procedure.

[0077] The present invention has many advantages. When and as long as the AGC is active, i.e., especially when rolling the center of the rolled material 2, the AGC, and thus any thickness adjustment system based on measuring the thickness d, does not have to compensate for all errors in the positioning of the roll stand 1 resulting from changes in the rolling force F, since partial compensation is somehow achieved by the tension-dependent determination of the resulting position target value s*, i.e., by correction by the tensions ZE and ZA. When and as long as the AGC is not active, i.e., especially during the initial and final pass phases, correction of thickness errors can be achieved at least partially by the tension-dependent determination of the resulting position target value s*, which would otherwise not be correctable at all. As a result, thicknesses d in the initial and / or final sections of the rolled material 2 that deviate more than the permitted tolerance from the target thickness d* can subsequently be significantly shortened, often by about half. Furthermore, there is good reason to believe that the design of the loop adjustment system immediately after the initial pass could also be improved.

[0078] Although the present invention has been shown and described in detail by means of preferred exemplary embodiments, the invention is not limited to the disclosed examples, and other modifications can be derived by those skilled in the art without going beyond the scope of protection of the invention. [Explanation of symbols]

[0079] 1 roll stand 2. Rolled materials 3, 4 Upstream / downstream devices 5 Actuators 6-position regulator 7 Adjustment Unit 8 Hydraulic System 9, 10 Working chamber 11, 16, 18 node points 12, 15, 19, 23 decision blocks 13 Decision Factors 14 Control Devices 17 Rolling Model 20. Top of rolled material 21 Tail of rolled material 22 Measuring Devices 24, 25 Tension regulator A operating signal d, d* thickness (actual and target) F actual rolling force FR Reference Rolling Force pP, pT working pressure q actuation variable R Reset signal s Actual position value s* Obtained position target value s0*, s1* standard target values t time Time points t1 to t7 vA, vU, vZ speed ZA, ZE, ZA*, ZE* Tension (actual and target) ZAR, ZER standard tension δs1* Additional target value δs1A* and δs1E* components δs2* correction value δs3* correction variable δvA, δvE operating variables

Claims

1. A method of operating a roll stand (1) for rolling a flat metal strip (2), comprising the steps of: a position regulator (6) for adjusting the positioning of an actuator (5) for setting the roll gap of the roll stand (1) determines an actuation variable (q) for the actuator (5) as a function of the resulting position target value (s*) and position actual value (s) of the actuator (5) and actuates the actuator (5) accordingly; the obtained position target value (s*) is determined using the obtained reference target value (s1*); said resulting reference target value (s1*) being determined as the sum of an initial reference target value (s0*) and an additional target value (δs1*) determined by a higher level control device (14); the additional target value (δs1*) is determined by a determining element (13) using the actual inlet tension (ZE) or the inlet target tension (ZE*) of an inlet tensioning system, which is a tension that can be set during operation of the roll stand (1), and the inlet reference tension (ZER), which is a tension that is set before operation of the roll stand (1), and / or using the actual outlet tension (ZA) or the outlet target tension (ZA*) of an outlet tensioning system, which is a tension that can be set during operation of the roll stand (1), and the outlet reference tension (ZAR), which is a tension that is set before operation of the roll stand (1), An operating method in which the inlet-side reference tension (ZER) is a variable different from the inlet-side target tension (ZE*), and the outlet-side reference tension (ZAR) is a variable different from the outlet-side target tension (ZA*).

2. 2. A method according to claim 1, characterized in that the roll stand (1) is operated by adjusting the roll gap.

3. 3. The method according to claim 1 or 2, characterized in that the inlet tensioning system acts on the roll peripheral speed (vU) at which the flat rolled stock (2) is rolled in the roll stand (1) and / or on the feed speed (vZ) at which the flat rolled stock (2) leaves a device (3) arranged upstream from the roll stand (1), and / or the outlet tensioning system acts on the roll peripheral speed (vU) and / or on the discharge speed (vA) at which the flat rolled stock (2) enters a device (4) arranged downstream from the roll stand (1).

4. 4. The method according to claim 1, 2 or 3, characterized in that the additional setpoint value (δs1*) is determined by the determining element (13) based on the product of an inlet sensitivity (SE) and a difference between the inlet actual tension (ZE) or the inlet target tension (ZE*) and the inlet reference tension (ZER) and / or based on the product of an outlet sensitivity (SA) and a difference between the outlet actual tension (ZA) or the outlet target tension (ZA*) and the outlet reference tension (ZAR).

5. An operating method as described in claim 4, characterized in that the high-level control device (14) determines the inlet side sensitivity (SE) and / or the outlet side sensitivity (SA).

6. 6. The method according to claim 5, characterized in that the entry sensitivity (SE) and / or the exit sensitivity (SA) are determined by the high-level control device (14) as part of a pass schedule calculation by analysis of a rolling model (22) which describes the rolling procedure in the roll stand (1) based on mathematical physical equations.

7. An operating method as described in any one of claims 1 to 6, characterized in that a high-level control device (14) determines the inlet side reference tension (ZER) and / or the outlet side reference tension (ZAR).

8. The high-level control device (14) determining the initial reference target value (s0*) and the entrance-side target tension (ZE*) and / or the exit-side target tension (ZA*) based on a target thickness (d*) of the flat rolled material (2) exiting the roll stand (1) and the entrance-side reference tension (ZER) and / or the exit-side reference tension (ZAR); specifying the initial reference target value (s0*) of the regulating unit (7) comprising the position regulator (6) and the determining element (13); 8. The operating method according to claim 7, wherein the inlet-side target tension (ZE*) is designated for a front tension regulator (24) that adjusts the inlet-side actual tension (ZE), and / or the outlet-side target tension (ZA*) is designated for a rear tension regulator (25) that adjusts the outlet-side actual tension (ZA), to the outlet-side target tension (ZA*).

9. 9. The method according to claim 1, wherein the obtained position target value (s*) is determined during rolling of at least the central portion of the rolled material (2) by using a correction value (δs2*) determined on the basis of the actual rolling force (F) and used to take into account the influence of changes in the rolling force (F) on the deflection of the roll stand (1).

10. An operating method as described in Claim 9, characterized in that the correction value (δs2*) is determined based on the obtained reference target value (s1*) and the actual rolling force (F).

11. 9. The method according to claim 1, wherein the obtained position target value (s*) is determined during rolling of at least the head (20) of the rolled material and / or the tail (21) of the rolled material without using an actual rolling force (F).

12. 9. The method according to claim 1, wherein the resulting position target value (s*) is determined by using the deviation of the thickness (d) of the rolled material (2) measured at the exit side of the roll stand (1) from the target thickness (d*).

13. 13. A control system for a roll stand (1) for rolling flat rolled stock (2), formed by hardware blocks and / or software programs so as to implement, during operation, the operating method according to any one of claims 1 to 12.

14. A rolling unit for rolling a flat metal stock (2), comprising a roll stand (1) for rolling said flat metal stock (2) and a control system according to claim 13.

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