Improved tape path control for a metal strip

Abstract

A control device (12) for a rolling stand (1) for rolling a strip (4) of metal receives characteristic information (I) from a detection device (10) regarding the shape of a strip foot (11). Depending on the shape of the strip foot (11), the control device (12) determines control variables (C1 to C3) for the rolling gap of the rolling stand (1) and controls the actuators (5 to 7) of the rolling stand (1) according to the determined control variables (C1 to C3).

Description

field of technology

[0001] The present invention relates to an operating method for a rolling stand for rolling a strip of metal, wherein a control device for the rolling stand receives characteristic information from a detection device for the shape of a strip foot.

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

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

[0004] The present invention further assumes a rolling device, wherein the rolling mill comprises a rolling stand for rolling a strip of metal, wherein the rolling stand comprises actuators influencing a rolling gap of the rolling stand, wherein the rolling mill comprises a detection device for detecting information characteristic of the shape of the strip foot, wherein the rolling mill comprises a control device which is connected to the detection device and the actuators in terms of control technology, wherein the control device is designed as such a control device which controls the rolling mill according to such an operating procedure. State of the art

[0005] The article "Towards Lights-Out Factory: Improved Finishing Mill Operation by Centerline Control, Reduced Strip Steering" by Klaus Pronold et al., published in Proceedings of the Iron & Steel Technology Conference, May 8-11, 2023, Detroit, Michigan, USA, pages 1438-1444, describes how to capture images from the area between the rolling stands of a multi-stand rolling mill. The captured images are then analyzed with regard to strip position, strip width, angle to the center position, and the shape of the strip head and strip foot.

[0006] The article "Development of Tandem Steering Control in Hot Strip Mill" by Sanga Takagi et al., published in Proceedings of the Iron & Steel Technology Conference, May 8-11, 2023, Detroit, Michigan, USA, pages 1419-1427, describes the process of capturing images from the area between the rolling stands of a multi-stand rolling mill. These images are then analyzed to determine the strip position.

[0007] The article "Strip Steering Control - A Cutting-Edge Technology for Hot Strip Mills" by Olaf Jepsen et al., published in Proceedings of the Iron & Steel Technology Conference, May 16-18, 2022, Pittsburgh, Pennsylvania, USA, pages 1753-1760, describes the process of capturing images from the area between the rolling stands of a multi-stand rolling mill. These images are then analyzed to determine the strip position.

[0008] From the technical article "Reduction of off-centering at tail end caused by unstable work roll position with mill stabilizing device in hot rolling" by Hideaki Furumoto et al., published in ScienceDirect, Procedia Engineering 207 (2017), pages 1373 to 1378, it is known that in particular the weaving out of the strip, i.e. the exit of the strip foot from a rolling stand, is problematic and that a thickness difference in the strip width direction (i.e. a strip wedge) should be avoided if possible. Summary of the invention

[0009] The process of strip unwinding from a rolling stand is one of the most critical steps in the strip rolling process. On the one hand, the strip foot can move freely laterally before reaching the roll gap of the rolling stand. Furthermore, the strip foot can exit the rolling stand unevenly. In particular, if the strip foot is longer on one side than the other, a strip break can occur, which not only renders the rolled strip usable only as scrap, but also leads to a plant shutdown.

[0010] The object of the present invention is to create possibilities by means of which operational safety can be increased when operating a rolling mill.

[0011] The problem is solved by an operating method with the features of claim 1. Advantageous embodiments of the operating method are the subject of dependent claims 2 to 6.

[0012] According to the invention, an operating method of the type mentioned at the outset is designed in such a way that the control device determines, depending on the shape of the strip foot, actuating elements of the rolling stand that influence a roll gap of the rolling stand and controls the actuating elements of the rolling stand according to the determined actuating elements.

[0013] The information about the base of the currently rolled strip, which is recorded and received by the control unit, is therefore used to determine the control parameters for the final section of the strip that has just been rolled (which also includes the base of the strip itself).

[0014] Typically, the control unit receives the information while the strip head (i.e., the beginning) of the strip currently being rolled has already entered the rolling stand, so that the strip foot is moving towards the stand during this process. However, in the case of reversing rolling, it is also possible to detect the shape of the strip head exiting the rolling stand during a rolling pass and to transmit this information to the control unit immediately or at a later time. After the direction of travel is reversed, the strip head of the previous rolling pass corresponds to the strip foot of the current rolling pass. Therefore, the shape of the strip head detected at the exit of the rolling stand during the previous rolling pass can be used as the shape of the strip foot for the current pass.

[0015] Typically, a device is positioned upstream of the rolling stand to hold the strip until the strip foot exits the device. In this case, the control device receives information characteristic of the strip foot's shape after the foot has exited the upstream device. The upstream device could be, for example, a reel or an S-roll set. Often, however, it is another rolling stand positioned upstream of the rolling stand.

[0016] The actuators for which the control unit determines the control variables within the framework of the inventive procedure are generally contour-influencing actuators, for example, an actuator for wedge adjustment or an actuator for work or intermediate roll bending. However, other actuators are also possible, for example, roll cooling or so-called pair crossing.

[0017] Preferably, the control device determines the control variables such that the shape of the strip foot assumes a target shape or at least approximates it after passing through the rolling stand. This avoids or at least reduces problems when the strip foot exits the rolling stand.

[0018] The desired shape can be achieved, for example, by ensuring that the ligament base runs as straight as possible and perpendicular to a ligament midline. Alternatively, the desired shape can be achieved, for example, by ensuring that the ligament base is slightly longer in the midline region than at the edges, thus forming a tongue in the midline region.

[0019] If the strip foot has a longitudinal wedge, meaning it is shorter on one side than the other, the rolling stand angle is preferably adjusted asymmetrically so that the shorter part of the strip foot is rolled more heavily than the longer part. If the strip foot is shaped like a dovetail or a fishtail, meaning it is shorter in the middle than at the sides, the roll deflection is adjusted to reduce or even completely compensate for the extent of the tail. In both cases, this compensates for the length differences.

[0020] In some cases, the strip foot can be so severely deformed longitudinally that the deformation can no longer be corrected, or not to a sufficient extent. In this case, the rolling stand should be raised as a temporary measure. This means that the remaining section of the strip will no longer be rolled properly and can only be used as scrap. However, this is acceptable because the section is relatively short.

[0021] To implement this approach, it is preferably intended that that the control device determines a measure of the deviation of the shape of the strip foot from the target shape based on the shape of the strip foot, that in the case that the determined measure does not exceed a threshold value, the control device determines the control variables in such a way that the shape of the strip foot assumes the target shape or at least approximates the target shape after passing through the rolling stand, and that in the case that the determined measure exceeds the threshold value, the control device raises the rolling stand.

[0022] As a result, the control unit checks whether the strip foot is so severely deformed that correction of the shape is no longer possible. In this case, the rolling stand is raised as an emergency measure.

[0023] The rolling stand is often part of a multi-stand rolling mill. If the rolling stand is different from the last rolling stand in the mill, it will often suffice for the control unit to determine the control parameters only for the rolling stand itself, as far as determining the control parameters based on the shape of the strip foot is concerned. However, it is also possible for the control unit to additionally determine control parameters for actuators of at least one further rolling stand downstream of the rolling stand, depending on the shape of the strip foot, and to control the actuators of the further rolling stand accordingly.

[0024] Normally, when the shape of the strip foot at least approximates the target shape, a further approximation of the strip foot shape can be achieved by means of the next rolling stand. In the exceptional case where the control unit raises the rolling stand, the control unit can also raise the next rolling stand or at least adjust its position. Particularly when raising the rolling stand, the same measure is often taken for all subsequent rolling stands in the rolling mill.

[0025] The control unit receives information characteristic of the strip foot's shape from the detection device for the first time at an early point in time and for the last time at a late point in time. For example, a camera detects a specific area on the entry side of the rolling stand. In this case, the early point in time is determined by the strip foot entering this area. Similarly, the late point in time is determined by the strip foot exiting this area. It is therefore possible that the control unit receives information from the detection device or another detection device, at least until a changeover point, that is characteristic of the strip's lateral position and / or curvature on the entry side of the rolling stand. The changeover point lies between the early and late points in time.Until the changeover point, the control unit determines the control parameters for the actuators of the rolling stand as a function of the lateral position of the strip and / or its curvature. Only after this point, i.e., from the changeover point onward, does the control unit determine the control parameters for the actuators of the rolling stand as a function of the shape of the strip foot. Thus, a prior art method precedes the actual method according to the invention, with the system switching from the prior art method to the method according to the invention at the changeover point.

[0026] In the case of application of the present invention to a reversing rolling stand, as already mentioned, the shape of the strip head exiting the rolling stand can be captured during the previous rolling pass and used as the shape of the strip foot for the current rolling pass. In this case, the earliest possible point in time can be considered to be the point in the previous rolling pass at which the shape of the strip head exiting the rolling stand is captured. However, the changeover point in this case can only occur at the earliest at the point in time at which the current rolling pass begins.

[0027] The information received by the control unit, characteristic of the strip foot's shape, can be an optical image or a thermal image, as required. Alternatively, a single line or a few lines can be scanned (repeatedly) along the strip's width, or a two-dimensional image can be acquired. The acquisition device is designed accordingly. If the acquisition of information regarding the strip's lateral position and / or curvature at the entry end of the rolling stand is performed by a separate acquisition device, the same principles apply to this additional device.

[0028] The problem is further solved by a control program with the features of claim 7. According to the invention, the execution of the control program causes the control device to control the rolling mill according to an operating method according to the invention.

[0029] The problem is further solved by a control device with the features of claim 8. According to the invention, the control device is programmed with a control program according to the invention, such that the control device controls the rolling mill according to an operating method according to the invention.

[0030] The problem is further solved by a rolling mill with the features of claim 9. According to the invention, the control device of the rolling mill is designed as a control device according to the invention, which controls the rolling stand according to an operating method according to the invention. Brief description of the drawings

[0031] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of an exemplary embodiment, which is explained in more detail in conjunction with the drawings. These drawings show: FIG 1 a multi-stand rolling mill, FIG 2 a single rolling stand, FIG 3 a captured image, FIG 4 a flowchart, FIG 5 a flowchart, FIG 6 a captured image, FIG 7 a flowchart and FIG 8 to 11 images of a strip. Description of the embodiments

[0032] According to FIG 1 A rolling mill has several rolling stands 1. These are shown in FIG 1 There are a total of four rolling stands 1. However, the number of rolling stands 1 could also be larger or smaller. The rolling stands 1 are in FIG 1 (and also in FIG 2 , in which a single rolling stand 1 is shown) is depicted as a quarto stand, i.e., as rolling stands that, in addition to their two work rolls 2, have two backup rolls 3, but no other rolls. The work rolls 2 and the backup rolls 3 are in FIG 1 Only the third rolling stand 1 of the rolling mill is marked with its reference symbol. However, the rolling stands 1 do not have to be configured as quarto stands. They can also be configured as duo stands, sexto stands, or in other ways. In a duo stand, the corresponding rolling stand 1 has only the two work rolls 2; in a sexto stand, in addition to the two work rolls 2 and the two backup rolls 3, it has two intermediate rolls arranged between the work rolls 2 and the backup rolls 3.

[0033] The rolling stands 1 are arranged sequentially one after the other and are traversed sequentially by a strip 4 with a uniform transport direction x. In other cases, however, there could also be only a single rolling stand 1 or a pair of rolling stands 1, which the strip 4 traverses in reverse. The strip 4 consists of metal. The metal is often steel. However, it can also be another metal, for example, aluminum or copper.

[0034] The following is related to FIG 2 One of the rolling stands 1 is explained in more detail. The corresponding explanations apply to all rolling stands 1.

[0035] According to FIG 2 The rolling stand 1 has actuators 5 to 7 by means of which the roll gap of the rolling stand 1 can be influenced. The actuators 5 to 7 are generally known to those skilled in the art and are therefore only briefly outlined below.

[0036] For example, the rolling stand 1 has an adjusting device 5 as one of the actuating elements 5 to 7. The adjusting device 5 is generally designed as a hydraulic adjusting device. It acts via the corresponding mounting elements (not shown) on the bearing journals 8 of the upper or lower backup roll 3. The other backup roll 3 is usually statically mounted. The adjusting device 5 has a separate sub-device 5a, 5b for each of the two bearing journals 8 of the corresponding backup roll 3. By means of the adjusting device 5, the roll gap can be influenced symmetrically with symmetrical control of the two sub-devices 5a, 5b, and asymmetrically with asymmetrical control. The direction of the force exerted by the sub-devices 5a, 5b corresponds to the arrows from the sub-devices 5a, 5b to the bearing journals 8 of the upper backup roll 3.

[0037] Furthermore, a sliding device 6 for the work rolls 2 may be provided. The sliding device 6 allows the work rolls 2 to be moved axially. The movement of the work rolls 2 is in opposite directions. Thus, if one work roll 2 is moved from left to right, the other work roll 2 is moved from right to left. The same applies to a movement in the reverse direction. In conjunction with a suitable grinding pattern – which is generally known to experts – the contour of the roll gap (i.e., the area between the two work rolls 2) can be influenced. The influence on the contour is usually symmetrical. The sliding device 6 has a separate sub-device 6a, 6b for each of the two work rolls 2.

[0038] Furthermore, a bending device 7 is often provided for the work rolls 2. The bending device 7 allows the work rolls 2 to be bent. The bending device 7 is generally designed as a hydraulic bending device. The bending device 7 acts on the bearing journals 9 of the work rolls 2 via the corresponding mounting elements (not shown). The bending device 7 has a separate sub-unit 7a, 7b for each of the two bearing journals 9 on the operator and drive sides of the respective work rolls 2. With symmetrical control of the two sub-units 7a, 7b, the roll gap can be influenced symmetrically by means of the bending device 7; with asymmetrical control, it can be influenced asymmetrically. The directions of the forces exerted by the sub-units 7a, 7b correspond to the arrows pointing from the sub-units 7a, 7b to the bearing journals 9 of the work rolls 2.

[0039] Alternatively or additionally, further actuators may be present by means of which the roll gap of the rolling stand 1 can be influenced.

[0040] The present invention is in principle applicable to each of the rolling stands 1 of the rolling mill of FIG 1 applicable. However, it is referred to below in conjunction with the one in FIG 1 The second rolling stand 1 is explained below. Whenever "rolling stand 1" is mentioned below without further specification, this rolling stand 1 is always meant. If a different rolling stand 1 is meant, this other rolling stand 1 will be explicitly specified.

[0041] According to FIG 1 A recording device 10 is present. Information I can be recorded by means of the recording device 10, which is relevant for the shape of the tape foot 11 of the tape 4 (see FIG 3 ) are characteristic. For example, the detection device 10 can be designed as an optical camera or as a thermal imaging camera, so that the information I is an optical image or a thermal image. FIG 3 Figure 1 shows an example image captured by the capture device 10. Alternatively, the capture device 10 can be configured as a line scanner. In this case, an image is captured as shown in Figure 1. FIG 3 generated gradually by repeated scanning during the transport of tape 4.

[0042] The rolling mill 1 is constructed according to FIG 1 Controlled by a control unit 12. The control unit 12 is connected to the acquisition unit 10 for receiving information I. It is also connected to the rolling stand 1 and, in particular, to its actuators 5 to 7 for controlling the actuators 5 to 7. The control unit 12 controls the rolling stand 1, and usually all rolling stands 1 of the rolling mill.

[0043] The control unit 12, as indicated by the abbreviation "µP" within the control unit 12, is software-programmable. The control unit 12 is programmed with a control program 13. The control program 13 comprises machine code 14, which can be executed directly by the control unit 12. The programming of the control unit 12 with the control program 13, or equivalently, the execution of the machine code 14 by the control unit 12, causes the control unit 12 to control the rolling mill 1 according to an operating procedure, which is described below, initially in conjunction with FIG 4 and will be explained in more detail later in the other FIG.

[0044] According to FIG 4 In step S1, the control unit 12 receives information I from the detection unit 10. In step S2, the control unit 12 determines the longitudinal contour of the belt foot 11. The longitudinal contour, as a function of its position in the width direction y of the belt 4, indicates how far the belt foot 11 extends from a reference line 15 (see FIG 3 The distance a of the tape foot 11 from the respective location in the lattice y of the tape 4, i.e., from the reference line 15, is determined. The reference line 15 can, in principle, be chosen arbitrarily, as long as it is orthogonal to the tape centerline. This is because the absolute distance a of the tape foot 11 from the reference line 15 as a function of the location in the lattice y of the tape 4 is not important, but rather the variations in the distance a. The distance a, viewed in the lattice y of the tape 4, is usually determined for a number of support points. The number of support points can be as required, but is usually 5 or more, for example, between 10 and 20. However, larger numbers are also possible.

[0045] In step S3, the control unit 12 determines the manipulated variables C1 to C3 for the actuators 5 to 7. The control unit 12 determines the manipulated variables C1 to C3 depending on the shape of the tape foot 11. For example, the control unit 12 can perform a best-fit of a predetermined polynomial and determine the manipulated variables C1 to C3 based on the coefficients of the polynomial thus determined. This is shown in the schematic diagram in FIG 3 The control unit 12 determines the manipulated variables C1 to C3, generally such that the shape of the strip foot 11 assumes a target shape 16 after passing through the rolling stand 1, or at least approximates the target shape 16. In step S4, the control unit 12 controls the actuators 5 to 7 according to the determined manipulated variables C1 to C3.

[0046] According to FIG 4 Steps S5 and S6 are still present. Steps S5 and S6 are only optional and therefore in FIG 4 Only shown with dashed lines. In step S5, the control unit 12 determines further control variables C1' to C3' for (generally identical) actuators 5 to 7 of at least one further rolling stand 1 downstream of the rolling stand 1, depending on the shape of the strip foot 11. The determination of the further control variables C1' to C3' is carried out in addition to the determination of the control variables C1 to C3 for the actuators 5 to 7 of the rolling stand 1. If the control unit 12 determines the further control variables C1' to C3' depending on the shape of the strip foot 11, the control unit 12 controls the actuators 5 to 7 of the further rolling stand 1 in step S6 according to the determined further control variables C1' to C3'. For example, the control unit 12 can also additionally determine control variables for the in FIG 1 third and / or that in FIG 1 Determine fourth rolling mill 1.

[0047] After step S4 or step S6 has been executed, the control unit 12 typically returns to step S1. Steps S1 to S4 and S1 to S6 are therefore executed cyclically. The information I received during the subsequent execution of step S1 can either replace or be added to the information I received during the previous execution of step S1, for example, by averaging the values.

[0048] FIG 5 demonstrates a supplement and extension of the approach of FIG 3 .

[0049] According to FIG 5 In step S11, the control unit 12 receives information I from the detection unit 10. In step S12, the control unit 12 determines the longitudinal contour of the belt foot 11. Steps S11 and S12 correspond 1:1 to steps S1 and S2 of FIG 3 .

[0050] In step S13, the control unit 12 determines a dimension M for the deviation of the shape of the tape foot 11 from the target shape 16, based on the shape of the tape foot 11. The dimension M is larger the greater the deviation of the shape of the tape foot 11 from the target shape 16. For example, FIG 3 a situation in which the measure M has a relatively low value. FIG 6 In contrast, this shows a case in which the measure M has a relatively large value.

[0051] In step S14, the control unit 12 checks whether the determined dimension M exceeds a threshold value M0.

[0052] If the determined dimension M does not exceed the threshold value M0, the control unit 12 determines the manipulated variables C1 to C3 for the actuators 5 to 7 in step S15 and controls the actuators 5 to 7 according to the determined manipulated variables C1 to C3 in step S16. Furthermore, steps S17 and S18 may also be present, in which the control unit 12, depending on the shape of the strip foot 11, additionally determines the further manipulated variables C1' to C3' for actuators 5 to 7 of at least one further rolling stand 1 downstream of the rolling stand 1 and controls the actuators 5 to 7 of the further rolling stand 1 according to the determined further manipulated variables C1' to C3'. Steps S15 to S18 correspond 1:1 to steps S3 to S6 of FIG 3 .

[0053] If, however, the determined dimension M exceeds the threshold value M0, the control unit 12 raises the rolling stand 1 in step S19. Accordingly, the control unit 12 determines the manipulated variables C1 to C3 in this case.

[0054] If necessary, the control unit 12 can also, in an optional step S20, raise at least one further rolling stand 1 downstream of the rolling stand 1, for example the one in FIG 1 third and / or that in FIG 1 fourth rolling stand 1. Accordingly, the control unit 12 determines the further control variables C1' to C3' for the further rolling stand 1 or the further rolling stands 1 in this case.

[0055] FIG 7 shows one way to integrate the operating method according to the invention into the general operation when unthreading the band 4.

[0056] According to FIG 7 In step S31, the control unit receives the information I, for example, an image captured by the detection device 10. The information I is not (yet) characteristic of the shape of the strip foot 11 – possibly from the point at which the strip foot 11 exits an upstream device. However, it is characteristic of the lateral position of the strip 4 and / or the curvature of the strip 4 on the entry side of the rolling stand 1. The upstream device can, for example, control the first rolling stand 1 of the rolling mill. FIG 1 be. FIG 8 The figure shows an example of a corresponding image in which the belt foot 11 has already exited the upstream device, but is not yet in the detection range of the detection device 10.

[0057] As the strip 4 is transported through the rolling mill and thus also through the rolling stand 1, the strip foot 11 approaches a detection area of ​​the detection device 10 and finally enters the detection area of ​​the detection device 10. FIG 9 The figure shows an image captured at an earlier time t1. The early time t1 corresponds to the time at which the information I characteristic of the shape of the tape foot 11 is first captured by the detection device 10 and consequently the control device 12 also first receives this information I.

[0058] As the strip 4 is transported further through the rolling mill and thus also through the rolling stand 1, the strip foot 11 passes through the detection area of ​​the detection device 10. FIG 10 This shows an image captured during this period. At this time, the tape foot 11 (add: somewhere) is located within the detection range of the detection device 10. FIG 11 Figure 1 shows an image captured at time t2. At this time, the tape foot 11 is just within the detection range of the detection device 10. Time t2 corresponds to the time at which the information I characteristic of the shape of the tape foot 11 is last captured by the detection device 10, and consequently, the control unit 12 also last receives this information I.

[0059] According to FIG 7 In step S32, the control unit 12 checks whether a changeover time t0 has occurred. The changeover time t0 lies (add: somewhere) between the early time t1 and the late time t2. It can, for example, correspond to the state that is in FIG 10 is shown.

[0060] If the changeover time t0 has not yet occurred, the control unit 12 proceeds to step S33. In step S33, the control unit 12 determines the manipulated variables C1 to C3 for the actuators 5 to 7 of the rolling stand 1 (and, if applicable, also the manipulated variables C1' to C3' for further rolling stands 1) depending on the lateral position of the strip 4 and / or the curvature of the strip 4. The procedure of step S33 is known and familiar to those skilled in the art.

[0061] If, however, the changeover time t0 has occurred, the control unit 12 proceeds to step S34. In step S34, the control unit 12 determines the manipulated variables C1 to C3 for the actuators 5 to 7 of the rolling stand 1 (and, if applicable, also the manipulated variables C1' to C3' for further rolling stands 1) depending on the shape of the strip foot 11. Step S34 corresponds to steps S2, S3 and, if applicable, also step S5 of FIG 4 or steps S12, S15, S19 and possibly also steps S17 and S20 of FIG 5 .

[0062] In step S35, the control unit 12 controls the actuators 5 to 7 of the rolling stand 1 (and, if applicable, also the actuators 5 to 7 of the other rolling stands 1) according to the determined control variables C1 to C3, C1' to C3'. The control unit 12 then returns to step S31.

[0063] The approach of FIG 7This was explained above in connection with a uniform acquisition device 10, in which the same information I (for example, a captured image) can be used both for determining the lateral position of the belt 4 and / or the curvature of the belt 4, as well as for determining the shape of the belt foot 11. Alternatively, it is essentially equivalent to use separate acquisition devices 10 for acquiring the respective information I. Furthermore, the switching at the changeover time t0 can alternatively be an abrupt switchover or a ramp-like transition. The latter is particularly suitable if the time interval between the early and late times t1, t2 is sufficiently large.

[0064] The present invention has many advantages. In particular, problems with the unthreading of the strip 4 from the rolling stand 1 can be significantly reduced. This is especially true because the shape of the strip foot 11 can be reliably detected for a longer period than the lateral position of the strip 4 and / or the curvature of the strip 4 on the entry side of the rolling stand 1.

[0065] Although the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by the person skilled in the art without leaving the scope of protection of the invention. Reference symbol list

[0066] 1 Roll stands 2 Work rolls 3 Support rolls 4 Belt 5 Adjusting device 6 Pushing device 7 Bending device 5a, 5b, 6a, 6b, 7a, 7b Sub-devices 8, 9 Bearing journals 10 Detection device 11 Belt foot 12 Control device 13 Control program 14 Machine code 15 Reference line 16 Target shape aDistance C1 to C3, C1' to C3' Control variables IInformation MMameter M0Threshold S1 to S35Steps t0Change time t1, t2Time points yLocation in the latitude direction of the band

Claims

1. Operating method for a rolling stand (1) for rolling a strip (4) of metal, - wherein a control device (12) for the rolling stand (1) receives characteristic information (I) for the shape of a strip foot (11) from a detection device (10), - wherein the control device (12) determines, depending on the shape of the strip foot (11), control variables (C1 to C3) for a roll gap of the rolling stand (1) and controls the control variables (5 to 7) of the rolling stand (1) according to the determined control variables (C1 to C3).

2. Operating method according to claim 1, characterized by that the control device (12) determines the actuating variables (C1 to C3) such that the shape of the strip foot (11) after passing through the rolling stand (1) assumes a target shape (16) or at least approximates the target shape (16).

3. Operating method according to claim 1, characterized by - thatThe control device (12) determines a dimension (M) for the deviation of the shape of the tape foot (11) from the target shape (16) based on the shape of the tape foot (11), - that the control device (12) in the case that the determined dimension (M) does not exceed a threshold value (M0), determines the control variables (C1 to C3) such that the shape of the strip foot (11) after passing through the rolling stand (1) assumes the target shape (16) or at least approximates the target shape (16), and - that The control device (12) raises the rolling stand (1) if the determined dimension (M) exceeds the threshold value (M0).

4. Operating method according to claim 1, 2 or 3, characterized by thatThe control device (12) determines additional control variables (C1' to C3') for actuators (5 to 7) of at least one further rolling stand (1) downstream of the rolling stand (1) depending on the shape of the strip foot (11) and controls the actuators (5 to 7) of the further rolling stand (1) according to the determined additional control variables (C1' to C3').

5. Operating method according to one of the above claims, characterized by- the control device (12) receives the information (I) characteristic of the shape of the strip foot (11) from the detection device (10) for the first time at an early time (t1) and for the last time at a late time (t2), - that the control device (12) receives information (I) from the detection device (10) or another detection device at least until a changeover time (t0) which lies between the early and the late time (t1, t2), which is characteristic of the lateral position of the strip (4) and / or the curvature of the strip (4) on the entry side of the rolling stand (1),- that the control device (12) determines the control variables (C1 to C3) for the actuators (5 to 7) of the rolling stand (1) up to the changeover time (t0) depending on the lateral position of the strip (4) and / or the curvature of the strip (4), and - that the control device (12) determines the control variables (C1 to C3) for the actuators (5 to 7) of the rolling stand (1) only from the changeover time (t0) depending on the shape of the strip foot (11).

6. Operating method according to one of the above claims, characterized by that the information (I) received by the control device (12) that is characteristic of the shape of the tape foot (11) is an optical image or a thermal image.

7. Control program for a software-programmable control device (12) for controlling a rolling stand (1) for rolling a strip (4) of metal, wherein the control program comprises machine code (14) that can be directly executed by the control device (12), wherein the execution of the machine code (14) by the control device (12) causes the control device (12) to control the rolling stand (1) according to an operating method according to one of the above claims.

8. Control device for a rolling stand (1) for rolling a strip (4) of metal, wherein the control device is programmed with a control program (13) according to claim 7, such that the control device controls the rolling stand (1) according to an operating method according to one of claims 1 to 6.

9. Rolling device, - wherein the rolling device comprises a rolling stand (1) for rolling a strip (4) of metal, - wherein the rolling stand (1) comprises actuators (5 to 7) influencing a roll gap of the rolling stand (1), - wherein the rolling device comprises a detection device (10) for detecting information (I) characteristic of the shape of the strip foot (11), - wherein the rolling stand (1) comprises a control device (12) which is connected to the detection device (10) and the actuators (5 to 7) for control purposes, - wherein the control device (12) is configured as a control device (12) according to claim 8, which controls the rolling stand (1) according to an operating method according to one of claims 1 to 6.

Images