Reducing thickness variations due to tension in rolling

Abstract

A flat metal material (2) to be rolled is rolled in a roll stand (1). A position controller (6) for controlling the placement of an actuator (5) by means of which a roll gap of the roll stand (1) is set determines an actuating variable (q) for the actuator (5) as a function of a resulting position target value (s*) and a position actual value (s) of the actuator (5) and drives the actuator (5) accordingly. The resulting position target value (s*) is determined with utilization of a resulting base target value (s1*). The resulting base target value (s1*) is determined as the sum of an initial base target value (s0*) and an additional target value (δs1*). The additional target value (δs1*) is determined by a determination element (13) with utilization of an inlet-end actual tension (ZE) and an inlet-end reference tension (ZER) and / or with utilization of an outlet-end actual tension (ZA) and an outlet-end reference tension (ZAR). Instead of the actual tensions (ZE, ZA), the corresponding target tensions (ZE*, ZA*) of corresponding tension control operations can also be used. However, in both cases, the reference tensions (ZER, ZAR) are variables that differ from the target tensions (ZE*, ZA*).

Description

Title of the invention

[0001] Reduction of tension-induced thickness changes during rolling field of technology

[0002] The present invention is based on an operating method for a rolling stand for rolling a flat rolled metal product, wherein a position controller for controlling the adjustment of an actuator, by means of which a roll gap of the roll stand is adjusted, determines a manipulated variable for the actuator as a function of a resulting position setpoint and an actual position value of the actuator and controls the actuator accordingly, wherein the resulting position setpoint is determined using a resulting base setpoint, wherein the resulting base setpoint is determined as the sum of an initial base setpoint and an additional setpoint.

[0003] In the simplest case, the resulting position setpoint is identical to the resulting base setpoint. The initial base setpoint is generally independent of the inlet and outlet tension.

[0004] The present invention further relates to a control system for a rolling stand for rolling a flat rolled metal product, wherein the control system is designed by hardware blocks and / or software programming in such a way that it implements such an operating method during operation.

[0005] The present invention further relates to a rolling unit for rolling a flat rolled metal stock, wherein the rolling unit comprises a rolling stand for rolling the flat rolled stock and such a control system. State of the art

[0006] When rolling flat metal stock, one of the fundamental requirements of the rolling process is to produce a flat rolled stock whose thickness matches a predetermined target thickness as closely as possible. The thickness of the rolled stock leaving the rolling stand is primarily controlled by the roll gap. The size of the roll gap, in turn, is adjusted by adjusting the actuator to a specific position.

[0007] However, the size of the roll gap and thus the thickness of the outgoing rolled stock is not determined solely by the position of the actuator. Rather, in addition to wear, thermal crowning, roll displacement, and possibly other influences, the springback of the roll stand must also be taken into account. Springback results from the rolling force and other forces acting on the roll stand, such as the bending force.

[0008] In most cases, rolling stands are operated with roll gap control. In such cases, the exit-side thickness to which the rolled stock is to be rolled in the rolling stand is first determined in a pass schedule. Furthermore, an associated expected rolling force is determined, taking into account characteristics of the rolled stock (e.g., its width, its entry-side thickness, its temperature, and other variables). Using a spring model of the rolling stand, the associated springback of the rolling stand is determined. Taking into account the springback of the rolling stand and other variables such as wear-related and / or temperature-related crowning, a position setpoint for the actuator is then determined.

[0009] During rolling of the rolled stock, the actual rolling force is recorded directly or determined based on recorded values. The correction value is determined using an AGC (automatic gauge control). The correction value is determined within the AGC using a spring model of the rolling stand.

[0010] The rolling of flat metal stock is often carried out in such a way that the stock is clamped in an upstream device in front of the roll stand and / or in a downstream device behind the roll stand while it is being rolled in the roll stand. This allows the stock to be subjected to an inlet-side tension in front of the roll stand or an outlet-side tension behind the roll stand. To better maintain the inlet-side or outlet-side tension, a respective looper can be arranged in front of and / or behind the roll stand. If the roll stand is part of a multi-stand rolling mill, but is not the frontmost roll stand in the roll stand, the upstream device can still be another roll stand in the multi-stand rolling mill.Similarly, if the rolling stand is part of a multi-stand rolling mill but is not the last rolling stand in the mill, the downstream equipment can also be another rolling stand in the multi-stand rolling mill. In other designs, the upstream and / or downstream equipment can also be a coiler, for example, in a Steckel mill. Other designs are also possible.

[0011] The exit tension, and to an even greater extent the entry tension, influence the rolling force. In particular, the greater the tension, the lower the required rolling force. At a lower rolling force, the rolling stand springs less. Therefore, unless the reduced spring is taken into account, the tension influences the thickness to which the rolled stock is rolled in the rolling stand.

[0012] In principle, this does not pose a problem because the change in rolling force is recorded, and the change in springback caused by the change in rolling force is corrected via the AGC mentioned above. However, the AGC requires a significant amount of time to correct the springback of the rolling stand. The correction value is therefore only applied with a delay. Furthermore, the compensation by the AGC is often only taken into account in a dampened manner, as otherwise there is a risk that the simultaneous correction of the adjustment by the AGC and the tracking of the tensions by tension controls could lead to oscillations and instabilities. Finally, the correction value determined by the AGC is often subject to errors, for example due to friction effects in the rolling stand or due to dead bands.

[0013] Furthermore, it is common practice to only activate the AGC after the first pass – i.e. with a delay. During the first pass, the exit-side tension is 0 because the rolling stock head has not yet reached a downstream device which, in conjunction with the rolling stand, could apply the exit-side tension to the rolling stock. However, the entry-side tension can certainly have values ​​other than 0. If the entry-side tension changes in such a case, this affects the rolling force and thus the springback of the rolling stand. However, since the AGC is only activated after the first pass, the change in the thickness to which the rolling stock is rolled in the rolling stand caused by the changed springback of the rolling stand is not corrected during the first pass.

[0014] Similarly, it is common practice to freeze the AGC before tapping - i.e. in advance - (i.e. no longer adjust a correction value determined at the time of freezing) or to limit any temporal change in the correction value. During tapping, the in-feed tension is 0 because the rolling stock root has already run out from an upstream device which, in conjunction with the rolling stand, could apply the in-feed tension to the rolling stock. However, the out-feed tension can certainly have values ​​other than 0. If in such a case the out-feed tension changes, this has an impact on the rolling force and thus on the spring back of the rolling stand. However, since the AGC is frozen orthe temporal change of the correction value determined by the AGC is limited, the change in the thickness to which the rolling stock is rolled in the rolling stand caused by the changed springback of the rolling stand is not corrected or only insufficiently corrected during the tapping phase.

[0015] An operating method of the type mentioned above is known from EP 3 231 522 A1. In this operating method, a tension controller, which regulates the actual tension at the input side to a desired tension at the input side, determines an additional adjustment setpoint, which is then added to the actual adjustment setpoint. The actual adjustment setpoint is a roll gap setpoint. The preamble of claim 1 is based on EP 3 231 522 A1.

[0016] An operating method of the type mentioned above is also known from JP 2003-164 906 A. In this operating method, a tension controller, which regulates the actual tension at the output side to a target tension at the output side, determines an additional adjustment setpoint, which is then added to the actual adjustment setpoint. The actual adjustment setpoint is a roll gap setpoint.

[0017] EP 2 620 233 A1 also discloses an operating method for a rolling stand for rolling flat metal stock. This operating method implements a mass flow control system, which in turn affects the adjustment system of the rolling stand. This adjusts the thickness of the rolled stock leaving the rolling stand. In this operating method, a tension controller, which regulates the actual tension at the input side to a desired tension at the input side, acts on the adjustment system of the rolling stand. Summary of the invention

[0018] The object of the present invention is to create possibilities by means of which a better adherence to the thickness of the rolling stock on the outlet side of the rolling stand can be ensured.

[0019] The object is achieved by an operating method having the features of claim 1. Advantageous embodiments of the operating method are the subject of dependent claims 2 to 12.

[0020] According to the invention, an operating method of the type mentioned at the outset is designed in that that the additional setpoint is determined by a determination element using an inlet-side actual tension or a corresponding setpoint tension of an inlet-side tension control and an inlet-side reference tension and / or using an outlet-side actual tension or a corresponding setpoint tension of an outlet-side tension control and an outlet-side reference tension, wherein the inlet-side reference tension is a different value from the inlet-side setpoint tension and / or the outlet-side reference tension is a different value from an outlet-side setpoint tension.

[0021] The actual tension on the inlet side and / or the actual tension on the outlet side can be measured actual values ​​or values ​​determined based on measured values. The use of either the actual values ​​or the setpoint values ​​is possible because tension controls generally have sufficiently high dynamic range and quality, and therefore the actual values ​​and setpoints correspond sufficiently.

[0022] As a rule, the rolling stand is operated with roll gap control. Furthermore, the inlet-side tension control usually affects a roll circumferential speed at which the flat rolled stock is rolled in the rolling stand and / or a feed speed at which the flat rolled stock runs out of a device upstream of the rolling stand. In a similar way, the outlet-side tension control usually affects the roll circumferential speed and / or a discharge speed at which the flat rolled stock runs into a device downstream of the rolling stand. As a rule, the tension controls only affect one device at a time, i.e. either the upstream device or the rolling stand, or either the rolling stand or the downstream device.

[0023] If the additional setpoint is dependent on the inlet-side tension condition (target or actual), the additional setpoint is preferably determined by the determination element based on the product of an inlet-side sensitivity multiplied by the difference between the inlet-side actual tension or the corresponding target tension and the inlet-side reference tension. Similarly, the additional setpoint is preferably determined by the determination element based on the product of the outlet-side sensitivity multiplied by the difference between the outlet-side actual tension or the corresponding target tension and the outlet-side reference tension, provided the additional setpoint is dependent on the outlet-side tension condition. This makes the determination of the additional setpoint and thus the resulting base setpoint particularly simple.

[0024] Preferably, the additional setpoint is determined by the determination element based on the product of an inlet-side sensitivity with the difference between the inlet-side actual tension or the corresponding setpoint tension and the inlet-side reference tension and / or based on the product of the outlet-side sensitivity with the difference between the outlet-side actual tension or the corresponding setpoint tension and the outlet-side reference tension. In this way, the additional setpoint can be determined particularly easily and reliably.

[0025] Preferably, the inlet-side sensitivity and / or the outlet-side sensitivity are specified to the detection element by a higher-level control device.

[0026] For example, the corresponding sensitivities can be stored within the higher-level control system in the form of tables or similar. The tables can contain the corresponding sensitivities depending on the geometry and other properties of the rolling stock (e.g., its chemical composition and temperature). However, it is preferred if the inlet-side sensitivity and / or the outlet-side sensitivity are determined by the higher-level control system as part of a pass schedule calculation by evaluating a rolling model. The rolling model is based on mathematical-physical equations that describe the rolling process in the rolling stand. This enables a "pinpoint" determination of the inlet-side sensitivity and / or the outlet-side sensitivity. The rolling model can be adapted repeatedly as needed.

[0027] The mathematical-physical equations of the rolling model are usually differential equations and / or algebraic equations. Such models are well known to experts. For example, see the paper "On the theory of rolling" by J.M. Alexander, published in the Proceedings of the Royal Society London, Vol. 326, pages 553 to 563, 1972.

[0028] In a similar way, the inlet-side reference train and / or the outlet-side reference train can also be specified to the determination element by a higher-level control device. The corresponding reference trains can be determined or applied by the higher-level control device as part of a pass schedule calculation.

[0029] Preferably, the operating method is designed in such a way that the higher-level control device - for example in the context of the pass plan calculation - based on a target thickness with which the flat rolled stock is to leave the roll stand and the inlet-side reference tension and / or the outlet-side reference tension, the initial base target value and the inlet-side target tension and / or the outlet-side target tension are determined, the initial base target value is specified by a control unit comprising the position controller and the determination element, and the inlet-side target tension is specified by a front tension controller, which regulates the inlet-side actual tension to the inlet-side target tension, and / or the outlet-side target tension is specified by a rear tension controller, which regulates the outlet-side actual tension to the outlet-side target tension.

[0030] Preferably, the resulting position setpoint is determined at least during the rolling of a center section of the rolling stock using a correction value determined using an actual rolling force. Thus, an AGC is implemented. It is therefore possible to combine the operating method according to the invention with the AGC.

[0031] When determining the correction value, the resulting base setpoint is preferably taken into account in addition to the actual rolling force. This can improve the dynamics of determining the correction value.

[0032] Preferably, the resulting position setpoint is determined at least during the rolling of a rolling stock head and / or a rolling stock root without using an actual rolling force. In this case, the present invention compensates for tension changes and the resulting rolling force changes even when the AGC is not active.

[0033] The latter approach can also be combined with the approach in which the AGC is active during the rolling of a middle section of the rolling stock. In this case, the AGC can alternatively be switched on during the transition from rolling the rolling head to rolling the middle section. Similarly, the AGC can be switched off (freezing or limiting changes) during the transition from rolling the middle section to rolling the rolling foot.

[0034] Preferably, the resulting position setpoint is determined by utilizing the deviation of a rolling stock thickness measured at the exit side of the rolling stand from a target thickness. This allows any residual errors to be corrected.

[0035] The object is further achieved by a control system having the features of claim 13. According to the invention, the control system implements an operating method according to the invention through the hardware blocks and / or software programming during operation.

[0036] The object is further achieved by a rolling unit having the features of claim 14. According to the invention, in a rolling unit of the type mentioned at the outset, the control system is designed as a control system according to the invention. Short description of the drawings

[0037] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of the embodiments, which are explained in more detail in conjunction with the drawings. Herein, in schematic representation: FIG 1 a rolling stand and its control, FIG 2 a rolling arrangement in a first operating state, FIG 3 the rolling arrangement of FIG 2 in a second operating state, FIG 4 the rolling arrangement of FIG 2 in a third operating state, FIG 5 the structure of a control unit, FIG 6 a determination element, FIG 7 an addition to the control unit of FIG 5 , FIG 8a modification of the addition of FIG 7 , FIG 9 a time diagram and FIG 10 an embodiment of the control unit of FIG 5 . Description of the embodiments

[0038] According to FIG 1 A rolling stock 2 is to be rolled in a rolling stand 1. From the rolling stand 1, FIG 1 (and, where shown, also the other FIGS) only the work rolls are shown. As a rule, however, the rolling stand 1 has at least backup rolls in addition to the work rolls (four-high stand), and if necessary also intermediate rolls in addition to the backup rolls, which are arranged between the work rolls and the backup rolls (six-high stand). The rolled stock 2 consists of metal, often steel, in some cases aluminum, in rare cases another metal such as copper. The rolled stock 2 is also a flat rolled stock, i.e. a strip (usually) or a heavy plate (exception).

[0039] Roll stand 1 is generally operated with roll gap control. Furthermore, the rolling of the rolled stock 2 in roll stand 1 takes place at a roll circumferential speed vU. The associated drives and their control systems are not shown.

[0040] According to the presentation in the FIG 2 und 3 The rolling stock 2 can be held in a device 3 arranged upstream of the rolling stand 1 while it is being rolled in the rolling stand 1. In this case, the rolling stock 2 runs out of the upstream device 3 at a feed speed vZ. Furthermore, the rolling stock 2 is subjected to an inlet-side actual tension ZE on the inlet side of the rolling stand 1. A looper can be arranged between the upstream device 3 and the rolling stand 1. The looper is not shown. The upstream device 3 can be arranged according to the illustration in the FIG 2 und 3 It can be designed in particular as an additional rolling stand. However, it can also be designed differently, for example as a coiler or as a drive roller set. The feed speed vZ is specified in the FIG 2 und 3 represented as peripheral speed. If the upstream device 3 is a rolling stand, the overfeed must also be taken into account.

[0041] The actual tension ZE on the inlet side is generally controlled to a corresponding target tension ZE* by means of a corresponding tension control. In this case, the actual tension ZE on the inlet side and the target tension ZE* on the inlet side are fed to a front tension controller 24. The front tension controller 24 determines a front manipulated variable δvE by utilizing the actual tension ZE on the inlet side and the target tension ZE* on the inlet side - usually by utilizing the difference between the two aforementioned tensions ZE, ZE* - which is applied to an actuator so that the actual tension ZE on the inlet side is adjusted to, or at least approximated to, the target tension ZE* on the inlet side. The front manipulated variable δvE can in particular be an additional speed setpoint that acts on the roll peripheral speed vU or - with the opposite sign - on the feed speed vZ.

[0042] In an analogous manner, the rolling stock 2 can be rolled while it is being rolled in the rolling stand 1, as shown in the FIG 3 und 4 be held in a device 4 arranged downstream of the rolling stand 1. In this case, the rolling stock 2 runs into the downstream device 4 at a discharge speed vA. Furthermore, the rolling stock 2 is subjected to an actual tension ZA on the outlet side of the rolling stand 1. A looper can also be arranged between the rolling stand 1 and the downstream device 4. This looper is also not shown. The downstream device 4 can be arranged according to the illustration in the FIG 3 bis 5 It can be designed in particular as an additional rolling stand. However, it can also be designed differently, for example as a coiler or as a set of drive rollers. The discharge speed vA is specified in the FIG 3 und 4 represented as peripheral speed. If the downstream device 4 is a rolling stand, the lag must also be taken into account.

[0043] The actual tension ZA on the outlet side is generally controlled to a corresponding target tension ZA* by means of a corresponding tension control. In this case, the actual tension ZA on the outlet side and the target tension ZA* on the outlet side are fed to a rear tension controller 25. The rear tension controller 25 determines a rear manipulated variable δvA by utilizing the actual tension ZA on the outlet side and the target tension ZA* on the outlet side - usually by utilizing the difference between the two aforementioned tensions ZA, ZA* - which is applied to an actuator so that the actual tension ZA on the outlet side is adjusted to, or at least approximated to, the target tension ZA* on the outlet side. The rear manipulated variable δvA can in particular be an additional speed setpoint that acts on the roll peripheral speed vU or - with the opposite sign - on the discharge speed vA.

[0044] The rolling stand 1 generally has a plurality of actuators by means of which the rolling process is influenced. Examples of such actuators are a bending system by means of which a roll bend is adjusted, a sliding device by means of which a pair of rolls can be axially displaced in opposite directions, a roll cooling system, a roll gap lubrication system, and others. Within the scope of the present invention, an actuator 5 (see FIG 5 ), by means of which the roll gap of the rolling stand 1 is adjusted. Therefore, only this actuator 5 and its control will be discussed in more detail below.

[0045] To control the position of actuator 5, a resulting position setpoint s* is specified to a position controller 6 of a control unit 7. An actual value s of actuator 5 is also supplied to position controller 6. Depending on these two variables s*, s, position controller 6 determines a manipulated variable q for actuator 5 and controls actuator 5 accordingly. Control unit 7 is an essential component of a control system according to the invention.

[0046] As a rule, the actuator 5 is as shown in FIG 5 designed as a hydraulic cylinder unit. In this case, the manipulated variable q acts on a hydraulic system 8, by means of which the working chambers 9, 10 of the hydraulic cylinder unit are subjected to a high working pressure pP (= pump pressure) or a low working pressure pT (= tank pressure) as required. The manipulated variable q can in this case, for example, be a hydraulic flow to be pumped. In particular, in this embodiment, the position controller 6 can be configured as shown in FIG 5 be designed as a proportional controller (P controller). In rare cases, it is also possible—alternatively or additionally—to adjust the roll gap using electric drives acting on screws. In such cases, the position controller 6 is often designed as a proportional-integral controller (PI controller).

[0047] The resulting position setpoint s* is determined using a resulting base setpoint s1*. In the configuration according to FIG 5 The resulting position setpoint s* is identical to the resulting base setpoint s1*. However, other variables can also be included in the resulting position setpoint s*. This will become clearer in later explanations. The resulting base setpoint s1* is determined using the actual infeed tension ZE and / or the actual outfeed tension ZA.

[0048] According to the presentation in FIG 5 the resulting base setpoint s1* is determined at a node 11 as the sum of an initial base setpoint s0* and an additional setpoint δs1*. The initial base setpoint s0* is - at least as a rule - independent of the inlet-side actual tension ZE and the outlet-side actual tension ZA. The additional setpoint δs1*, on the other hand, depends on the inlet-side actual tension ZE and the outlet-side actual tension ZA. In particular, the additional setpoint δs1* is determined by the determination element 13 using an inlet-side actual tension ZE and an inlet-side reference tension ZER. Alternatively or additionally, the additional setpoint δs1* can be determined by the determination element 13 using the outlet-side actual tension ZA and an outlet-side reference tension ZAR.

[0049] To determine the additional setpoint δs1*, as shown in FIG 6 For example, the inlet-side actual tension ZE can be fed to a determination block 12 of the determination element 13. In this case, an inlet-side component δs1E* of the additional setpoint δs1* is determined in the determination block 12 using the inlet-side actual tension ZE and the inlet-side reference tension ZER. For example, the inlet-side component δs1E* can be determined as shown in FIG 6 according to the relationship δs 1 E * = SE ⋅ ZE − ZER Here, SE is an input-side sensitivity. The input-side reference tension ZER can, if necessary, have the value 0. In individual cases, it can even be time-variable. In this case, it is usually also necessary to change the initial base setpoint s0* by a corresponding amount.

[0050] The input-side sensitivity SE and the input-side reference train ZER can be assigned to the determination element 13, for example, as shown in FIG 1 be specified by a higher-level control device 14. The control device 14, if present, is another essential component of the control system.

[0051] In an analogous manner, the additional setpoint δs1* can be determined as shown in FIG 6 For example, the outgoing-side actual tension ZA can be fed to a determination block 15 of the determination element 13. In this case, an outgoing-side component δs1A* of the additional setpoint δs1* is determined in the determination block 15 using the outgoing-side actual tension ZA and the outgoing-side reference tension ZAR. For example, the outgoing-side component δs1A* can be calculated as shown in FIG 6 according to the relationship δs 1 A * = SA ⋅ ZA − ZAR Here, SA is an output-side sensitivity. The output-side sensitivity SA and the output-side reference tension ZAR can be assigned to the determination element 13 as shown in FIG 1 can also be specified by the higher-level control device 14. The input-side reference tension ZAR can, if necessary, have the value 0. In individual cases, it can even be variable over time. Analogous to a change in the input-side reference tension ZER, it may be necessary to change the initial base setpoint s0* to a corresponding extent when the output-side reference tension ZAR ends.

[0052] It is possible that only one of the two tensions ZE, ZA is used. In this case, the additional setpoint δs1* is identical to the corresponding component δs1E*, δs1A*. However, both tensions ZE, ZA are usually used. In the case of a linearized determination, the determination element 13 has a node 16 at which the additional setpoint δs1* is determined as the sum of the two components δs1E*, δs1A*. Furthermore, it is possible to use the corresponding setpoints ZE*, ZA* instead of the actual tensions ZE, ZA.

[0053] The target trains ZE*, ZA*, i.e., the target values ​​ZE*, ZA* supplied to the corresponding train controllers 24, 25 and thus valid for train control, are different values ​​from the reference trains ZER, ZAR. While it may be possible to derive the target trains ZE*, ZA* from the reference trains ZER, ZAR, there is no identity. The actual values ​​may be temporarily the same, but this is not systematically and consistently the case.

[0054] For example, it is possible for the target tensions ZE*, ZA* to be specified by an operator (not shown) or to be varied by the operator during the rolling of the flat rolled stock 2. The reference tensions ZER, ZAR, on the other hand, cannot be changed by the operator. Furthermore, it is possible for the target tensions ZE*, ZA* to be varied over time by the higher-level control device 14 for technological reasons, while the reference tensions ZER, ZAR are maintained. This is explained in more detail below using an example. For the purposes of this example, it is assumed that the upstream device 3 and the downstream device 4 are rolling stands and that a rolling stand is also arranged upstream of the upstream device 3 and a rolling stand is also arranged downstream of the downstream device 4.

[0055] A rolling stock head 20 of the rolling stock 2 (see FIG 2 ) reaches, for example, the rolling stand 1 at a time t1, the downstream device 4 at a time t2 and the rolling stand downstream of the downstream device 4 at a time t3. Similarly, for example, a rolling stock foot 21 of the rolling stock 2 (see FIG 4 ) at a time t4 the rolling stand upstream of the upstream device 3, at a time t5 the upstream device 3 and at a time t6 the rolling stand 1. The time t4 is usually after the time t3.

[0056] FIG 2 shows the rolling process during rolling of rolling stock 2 at time t1. Starting at time t1, the actual tension ZE on the inlet side can be applied. However, this is not possible before time t1. Therefore, before time t1, the actual tension ZE on the inlet side is necessarily 0. The actual tension ZA on the outlet side is also 0, because there is no rolling stock 2 on the outlet side of roll stand 1, and the rolling stock 2 has certainly not reached the downstream device 4.

[0057] In an analogous way, FIG 4 the rolling process during rolling of rolling stock 2 at time t6. Up to time t6, the actual tension ZA on the exit side can just be applied. After time t6, however, this is not possible. After time t6, the actual tension ZA on the exit side is therefore necessarily 0. The actual tension ZE on the entry side is also 0, because there is no longer any rolling stock 2 on the entry side of roll stand 1, and the rolling stock 2 has already exited the upstream device 3 long ago.

[0058] FIG 3 shows the rolling process during rolling of rolling stock 2 between times t1 and t6, more precisely between times t2 and t5. During this time period, rolling stock 2 is subjected to the respective actual tension ZE, ZA on at least one side (i.e., on the inlet side or the outlet side), and during part of this time period even on both sides (i.e., on the inlet side and the outlet side).

[0059] In the static state, when rolling stock 2 is rolled in all rolling stands of the example just explained, the target tensions ZE*, ZA* can correspond to the reference tensions ZER, ZAR, i.e., have the same values. This static state—relative to the specification of the target values ​​ZE*, ZA* for the tension controllers 24, 25—exists between times t3 and t4.

[0060] On the other hand, for example, in the period between time t1 and time t2, the rear tension controller 25 may, due to its design, not be active. This is because the rolling stock 2 on the exit side of the rolling stand 1 cannot be subjected to the exit-side actual tension ZA. However, the determination of the exit-side component δs1A* of the additional setpoint δs1* is entirely possible even during this period. Furthermore, the front tension controller 24 may indeed be active during this period. However, it is possible that the corresponding setpoint ZE* = ZER is not immediately supplied to the front tension controller 24 at time t1 (or shortly thereafter), but rather the setpoint ZE* is increased from 0 to the value of the corresponding reference tension ZER using a ramp.

[0061] Similarly, it is possible that in the period between time t2 and time t3 the rear tension controller 25 is active, but the corresponding setpoint ZA* = ZAR is not immediately supplied to the rear tension controller 25 at time t2 (or shortly thereafter), but the setpoint ZA* is increased by means of a ramp from 0 to the value of the corresponding reference tension ZAR.

[0062] Similarly, it is possible that in the period between time t4 and time t5 the front tension controller 24 is active, but the setpoint ZE* supplied to the front tension controller 24 is reduced during the said period from the value ZE* = ZER present at the beginning of the said period to the value 0 by means of a ramp.

[0063] Furthermore, the front tension controller 24 cannot be active during the period between time t5 and time t6, due to the nature of the method. This is because the rolling stock 2 cannot be subjected to the actual inlet tension ZE on the inlet side of the rolling stand 1. However, the determination of the inlet-side component δs1E* of the additional setpoint δs1* is entirely possible during this period. Furthermore, the rear tension controller 25 can indeed be active during this period. However, it is possible that the setpoint ZA* supplied to the rear tension controller 25 is reduced by means of a ramp from the value ZA* = ZAR present at the beginning of the period to the value 0 during this period.

[0064] The inlet-side sensitivity SE and / or the outlet-side sensitivity SA and, if necessary, also other values ​​such as the reference tensions ZER and / or ZAR and / or the initial base setpoint s0* can be provided by the higher-level control device 14.

[0065] The controllers implement real-time control during rolling of the rolled stock. The entire controller system is commonly referred to as an L1 system in technical circles. The higher-level control device 14 therefore functions as a unit commonly referred to as an L2 system in technical circles. The higher-level control device 14 comprises, as shown in FIG 1 Among other things, a rolling model 17, in which the rolling process in the rolling stand 1 is modeled. The rolling model 17 is based on mathematical-physical equations that describe the rolling process. The higher-level control device 14 determines the aforementioned variables SE and / or SA and / or ZER and / or ZAR and / or s0* and, if necessary, other variables by evaluating the rolling model 17.

[0066] For example, prior to rolling the rolling stock 2 in the rolling stand 1, the higher-level control device 14 performs a pass schedule calculation in which it determines these and, if necessary, other values. The higher-level control device 14 makes the determined values ​​available to subordinate controllers (for example, the position controller 6 of the control unit 7). In particular, the higher-level control device 14 determines, within the scope of the pass schedule calculation, based on a target thickness d* (see FIG 1 ) with which the flat rolled stock 2 is to leave the roll stand 1, and the inlet-side reference tension ZER and / or the outlet-side reference tension ZAR, the initial base setpoint s0* as well as the inlet-side setpoint tension ZE* and / or the outlet-side setpoint tension ZA*. The setpoint thickness d* can alternatively be specified to the higher-level control device 14 or determined independently by the higher-level control device 14. The reference tensions ZER, ZAR are generally set by the higher-level control device 14. Based on these values ​​d*, ZER, ZAR, the higher-level control device 14 determines the required rolling force and the required adjustment. The required rolling force corresponds to a reference rolling force FR, and the required adjustment corresponds to the initial base setpoint s0*. The higher-level control device 14 specifies the initial base setpoint s0* to the control unit 7.Likewise, the higher-level control device 14 specifies the inlet-side target tension ZE* to the front tension controller 24 and the outlet-side target tension ZA* to the rear tension controller 25.

[0067] The higher-level control device 14 can determine the inlet-side sensitivity SE, for example, by determining the effect of the change in the inlet-side tension ZE on an actual rolling force F for the intended operating point of the rolling stand 1 and also the effect of the change in the rolling force F on the springback of the rolling stand 1. The product of the two aforementioned effects results in the inlet-side sensitivity SE. In an analogous manner, the higher-level control device 14 can determine the outlet-side sensitivity SA by determining the effect of the change in the outlet-side tension ZA on the rolling force F for the intended operating point of the rolling stand 1 and also the effect of the change in the rolling force F on the springback of the rolling stand 1. The product of the two aforementioned effects results in the outlet-side sensitivity SA.In a completely equivalent manner, it is also possible to specify the base variables for the sensitivities SE, SA to the determination element 13, i.e., the effect of the change in the inlet-side tension ZE on the actual rolling force F, the effect of the change in the outlet-side tension ZA on the rolling force F, and the effect of the change in the rolling force F on the springback of the roll stand 1. In this case, the determination element 13 can determine the sensitivities SE, SA itself. Furthermore, in this case, the determination element 13 is also particularly capable of determining a change δF in the expected rolling force corresponding to changes in the tensions ZE, ZA.

[0068] As a rule, the resulting position setpoint s* is not identical to the resulting base setpoint s1*, but is determined using additional correction variables.

[0069] This is according to the presentation in FIG 7 For example, it is possible that the resulting position setpoint s* is determined using a correction value δs2* determined using the rolling force F. For example, the resulting position setpoint s* can be determined in a node 18 as the sum of the resulting base setpoint s1* and a correction value δs2*. In this case, the correction value δs2* is determined in a determination block 19 using the actual rolling force F. The determination block 19 thus implements an AGC in which an additional springback of the rolling stand 1 is (at least largely) compensated. The additional springback of the rolling stand 1 is caused by the deviation of the actual rolling force F from the reference rolling force FR. For the sake of clarity, it is pointed out that in FIG 7 only the additional parts of the control unit 7 are shown. For the basic design of the control unit 7, the FIG 5 und 6 to be taken into account.

[0070] In the simplest case, only the actual rolling force F and the reference rolling force FR are fed to the determination block 19 as input variables. The reference rolling force FR is fed to the determination block 19 as shown in FIG 1 provided by the higher-level control device 14. In many cases, however, in addition to the actual rolling force F, a value is also supplied to the determination block 19 which, with the exception of the correction value δs2* determined by the determination block 19, already corresponds to the resulting position setpoint s*. For example, the resulting base setpoint s1* can be supplied to the determination block 19. In this case, the determination block 19 also takes into account the resulting base setpoint s1* when determining the correction value δs2*. Furthermore, in this case, the determination element 13 also determines the associated expected change δF in the reference rolling force FR in addition to the additional setpoint δs1*. The expected change δF in the reference rolling force FR is taken into account by the determination block 19 when determining the correction value δs2*. If necessary, the actual position value s can also be supplied to the determination block 19.

[0071] It is possible that the information associated with FIG 7 explained procedure is always carried out during the rolling of the rolling stock 2 in the rolling stand 1. In this, the determination and activation of the correction value δs2* takes place regardless of which section of the rolling stock 2 is currently being rolled. In many cases, however, the correction value δs2* is only determined or activated while a middle section of the rolling stock 2 is being rolled. During the rolling of the rolling stock head 20 and / or the rolling stock foot 21, however, the resulting position setpoint s* is often determined without using the actual rolling force F. This is explained below in connection with the FIG 8 and 9 with additional reference to the FIG 2 bis 4 explained in more detail.

[0072] FIG 8 comes from the control unit 7 of FIG 7 . At FIG 8 An activation signal A and a reset signal R can be fed to the detection block 19. The activation signal A has, according to FIG 9 the value 0 or the value 1. A value of 1 for activation signal A activates determination block 19. In this case, determination block 19 determines the currently valid correction value δs2* using the rolling force F. As a result, the resulting position setpoint s* is determined using the rolling force F. A value of 0 for activation signal A deactivates determination block 19. In this case, determination block 19 outputs the last determined correction value δs2* but does not update the correction value δs2* any further. As a result, the resulting position setpoint s* is determined without using the rolling force F. The reset signal R is only fed to determination block 19 when no rolling stock is being rolled in roll stand 1. The feed of reset signal R causes the last determined correction value δs2* to be reset to 0.

[0073] The activation signal A varies as a function of time t. Up to time t1, the activation signal A has the value 0. After that, the activation signal A increases - usually abruptly - to the value 1. At time t6, the activation signal A decreases - usually again abruptly - to the value 0. At a time t7, which according to FIG 9 after time t6, the reset signal R is (briefly) specified.

[0074] FIG 10 shows a further embodiment of the control unit 7 of FIG 5 . The design of FIG 10 However, it could easily be based on the design of control unit 7 of the FIG 7 und 8 According to FIG 10At the exit side of the rolling stand 2, a thickness d of the rolling stock 2, i.e., its actual value, is measured using a corresponding measuring device 22. In a determination block 23, the thickness d is compared with a target thickness d*. Based on the deviation of the thickness d of the rolling stock 2 from the target thickness d*, a correction variable δs3* is determined in the determination block 23. The correction variable δs3* is fed to the node 18. This determines the resulting position target value s*, also taking into account the correction variable δs3*. This procedure allows any remaining errors to be compensated.

[0075] The present invention has many advantages. If and as long as the AGC is active—in particular during rolling of the center section of the rolled stock 2—the AGC and any thickness control based on the thickness measurement d no longer have to compensate for the entire error in the adjustment of the roll stand 1 caused by the change in the rolling force F, since partial compensation is already achieved by the tension-dependent determination of the resulting position setpoint s*, i.e., by the correction based on the tensions ZE, ZA. If and as long as the AGC is inactive—in particular during the tapping phase and the tapping phase—the tension-dependent determination of the resulting position setpoint s* can at least partially correct thickness errors that otherwise could not be corrected at all.As a result, the initial section and / or the final section of the rolled stock 2, whose thickness d deviates from the target thickness d* by more than the permissible tolerance, can be significantly shortened, often by approximately half. There is also reason to assume that the design of the loop control immediately after the initial pass will also be improved.

[0076] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variants can be derived therefrom by those skilled in the art without departing from the scope of the invention as defined in the claims. List of reference symbols

[0077] 1Roll stand 2Rolling stock 3, 4Upstream / downstream equipment 5Actuator 6Position controller 7Control unit 8Hydraulic system 9, 10Working spaces 11, 16, 18Nodes 12, 15, 19, 23Determination blocks 13Determination element 14Control device 17Rolling model 20Rolling stock head 21Rolling stock foot 22Measuring device 24, 25Tension controller AActivation signal d, d*Thicknesses (actual and target) FActual rolling force FRReference rolling force pP, pTWorking pressures qManipulated variable RReset signal sActual position value s*Resulting position setpoint s0*, s1*Basic setpoints tTime t1 to t7Time points vA, vU, vZSpeeds ZA, ZE, ZA*, ZE*Tensions (actual and target) ZAR, ZERReference tensions δs1*additional setpoint δs1A*, δs1E*components δs2*correction value δs3*correction variable δvA, δvEcontrol variables

Claims

1. Operating method for a roll stand (1) for rolling flat metal rolling stock (2), - wherein a position regulator (6) for regulating the positioning of an actuator (5) by means of which a roll gap of the roll stand (1) is set determines an actuating variable (q) for the actuator (5) as a function of a resulting position target value (s*) and a position actual value (s) of the actuator (5) and activates the actuator (5) accordingly, - wherein the resulting position target value (s*) is determined by use of a resulting base target value (s1*), characterized in that - the resulting base target value (s1*) is determined as the sum of an initial base target value (s0*) and an additional target value (δs1*), - wherein the additional target value (δs1*) is determined by a determination element (13) by the use of an inlet-side actual tension (ZE), or a corresponding target tension (ZE*) of an inlet-side tension regulating system, and an inlet-side reference tension (ZER) and / or by the use of an outlet-side actual tension (ZA), or a corresponding target tension (ZA*) of an outlet-side tension regulating system, and an outlet-side reference tension (ZAR), - wherein the inlet-side reference tension (ZER) is a different variable from the inlet-side target tension (ZE*) and / or the outlet-side reference tension (ZAR) is a different variable from an outlet-side target tension (ZA*).

2. Operating method according to Claim 1, characterized in that the roll stand (1) is operated by regulating the roll gap.

3. Operating method according to Claim 1 or 2, characterized in that the inlet-side tension regulating system acts on a roll circumferential speed (vU) at which the flat rolling stock (2) is rolled in the roll stand (1), and / or on a feed speed (vZ) at which the flat rolling stock (2) exits a device (3) arranged upstream from the roll stand (1), and / or in that the outlet-side tension regulating system acts on the roll circumferential speed (vU) and / or on a discharge speed (vA) at which the flat rolling stock (2) enters a device (4) arranged downstream from the roll stand (1).

4. Operating method according to Claim 1, 2 or 3, characterized in that the additional target value (δs1*) is determined by the determination element (13) on the basis of the product of an inlet-side sensitivity (SE) and the difference between the inlet-side actual tension (ZE) or the corresponding target tension (ZE*) and the inlet-side reference tension (ZER) and / or on the basis of the product of the outlet-side sensitivity (SA) and the difference between the outlet-side actual tension (ZA) or the corresponding target tension (ZA*) and the outlet-side reference tension (ZAR).

5. Operating method according to Claim 4, characterized in that the inlet-side sensitivity (SE) and / or the outlet-side sensitivity (SA) are specified for the determination element (13) by a higher-order control device (14).

6. Operating method according to Claim 5, characterized in that the inlet-side sensitivity (SE) and / or the outlet-side sensitivity (SA) are determined by the higher-order 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. Operating method according to one of the above claims, characterized in that the inlet-side reference tension (ZER) and / or the outlet-side reference tension (ZAR) are specified for the determination element (13) by a higher-order control device (14) .

8. Operating method according to Claim 7, characterized in that the higher-order control device (14) - determines the initial base target value (s0*) and the inlet-side target tension (ZE*) and / or the outlet-side target tension (ZA*) on the basis of a target thickness (d*) with which the flat rolling stock (2) is to exit the roll stand (1) and the inlet-side reference tension (ZER) and / or the outlet-side reference tension (ZAR), - specifies the initial base target value (s0*) of a regulating unit (7) comprising the position regulator (6) and the determination element (13), and - specifies the inlet-side target tension (ZE*) for a front tension regulator (24) which regulates the inlet-side actual tension (ZE) to the inlet-side target tension (ZE*) and / or the outlet-side target tension (ZA*) for a rear tension regulator (25) which regulates the outlet-side actual tension (ZA) to the outlet-side target tension (ZA*).

9. Operating method according to one of the above claims, characterized in that the resulting position target value (s*) is determined at least during the rolling of a central portion of the rolling stock (2) by the use of a correction value (δs2*) determined by the use of an actual rolling force (F).

10. Operating method according to Claim 9, characterized in that the resulting base target value (s1*) is taken into account as part of the determination of the correction value (δs2*) in addition to the actual rolling force (F).

11. Operating method according to one of the above claims, characterized in that the resulting position target value (s*) is determined at least during the rolling of a head (20) of the rolling stock and / or a tail (21) of the rolling stock without the use of an actual rolling force (F).

12. Operating method according to one of the above claims, characterized in that the resulting position target value (s*) is determined by the use of the deviation of a thickness (d) of the rolling stock (2), measured at the outlet side of the roll stand (1), from a target thickness (d*).

13. Control system for a roll stand (1) for rolling flat metal rolling stock (2), wherein the control system is formed by hardware blocks and / or software programs in such a way that during operation it implements an operating method according to one of the above claims.

14. Rolling unit for rolling flat metal rolling stock (2), wherein the rolling unit has a roll stand (1) for rolling the flat rolling stock (2) and a control system according to Claim 13.

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