Method and computer program product for calculating a stable rolling schedule for a rolling process

Abstract

The invention relates to a method for calculating a stable rolling schedule for a rolling process in a rolling mill for rolling a metal strip and to a corresponding computer program product. Here, a biasing quantity is varied until a calculated target level force meets a preset limit criterion. Meeting the limit criterion means that the roll set and the rolling process are stable at this point. In the case that iterations of the biasing of the working rolls alone do not lead to compliance with the limit criterion, the invention proposes that subsequently the pulling force acting on the rolled material on the entry side and / or on the exit side of the rolling stand is varied iteratively while keeping the biasing constant until the calculated target level force meets the limit criterion.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for calculating a pass schedule for a stable rolling process when rolling a metal strip in a rolling mill and to a corresponding computer program product. BACKGROUND

[0002] When flat rolling a rolling stock, in particular a metal strip, it is known that for achieving small final thicknesses (or for reasons of energy efficiency) small work roll diameters have to be provided. However, small work roll diameters limit the possible geometry of the drive shaft necks and thus the possible drive torque, which appears relatively large in case of an increase of material strength / an increase of the re-forming resistance.

[0003] A disadvantage of using small work roll diameters is that due to the horizontal forces acting in large length-to-width ratios (ratio of bearing center distance to roll diameter) the rolls are horizontally deflected; see Figure 6 The horizontal out-of-roundness not only leads to an instability of the whole roll set, it can even lead to a longitudinal bending of the rolls. In case of very small work rolls the deflection will not only have a horizontal component, but additionally a vertical component in the direction of the roll supporting it. The desired vertical bending of the work rolls for setting the rolling gap profile is independent of this situation.

[0004] Various measures are known in the prior art to protect and stabilize thin rolls against horizontal out-of-roundness during the rolling process.

[0005] One of the measures is the so-called horizontal offset. Here, the axial extension of the work roll pair is offset from the roll pair on which the work roll pair is biasedly supported. A (zero) offset leads to an instability of the roll set and should in principle be avoided, because upon a change of the rolling gap the rolls will "drift" due to the bearing play and will form strip defects and strip tears.

[0006] The fixed offset is suitable for hot rolling mills, where the strip tension shows hardly any key role for the roll gap conditions and the stability of the roll set. In case of cold rolling mills, in particular with a large product range and in case of a reversible operation and / or in case of non-driven work rolls, the fixed offset is not sufficient.

[0007] An improved method for fixed offset is the so-called (horizontally stable) HS offset, which is set by HS displacement (device). Here, HS displacement means that the work roll pair, together with its inserts, moves along the + / - belt running direction. Essentially, it is a variable setting of the offset. The absolute value and direction of the HS offset are set such that the vertical adjustment force FA and the force components appearing in the offset (horizontal force), as well as the tension difference generated from the entry and exit tensions Ze, Za, compensate as much as possible, preferably almost completely, throughout all rolling stages, and the rolls remain stably against one side of the rolls supporting them. The side to be set can be either on the entry side (-) or the exit side (+), depending on parameters such as the rolling forces, torques, roll diameters, and belt tensions on the entry and exit sides. The horizontal force minimized by setting the HS offset thus causes only minimal horizontal deflection when the roll position is absolutely stable.

[0008] The adjusting force FA and tension on the entry side Ze and exit side Za of the rolling mill stand are the main forces responsible for the re-forming work to be completed at the metal strip. The force component in the offset, i.e., the horizontal force Haw of the work roll, is the resultant force generated by the vector addition of the other force components mentioned, where all force components must have a common vector sum of 0, as in... Figure 7 As shown. The horizontal force Haw and the bias are proportionally related as follows:

[0009] Haw=f(FA,-saw,MA,Ze-Za,μ,r)

[0010] in

[0011] MA driving torque

[0012] μ is the coefficient of friction; and

[0013] r is the radius of the working roll.

[0014] saw bias

[0015] The detailed known calculations vary depending on the type of roll set and its driver.

[0016] Because work rolls with small diameters react particularly severely to excessive horizontal forces in the following way: that is, the work rolls, for example, Figure 6 As shown, there is a tendency towards undesirable horizontal deflection. Importantly, the horizontal force is not excessive when using work rolls with high slender lengths. Therefore, it is known and common in the prior art that the target horizontal force acting on the work rolls is calculated by means of a pass planning computer, which runs a process model of the rolling process. The pass planning computer calculates the horizontal force while taking into account a large amount of input data.

[0017] In Figure 8 the intuitive view shows which input data the pass schedule computer is based on for calculating the setup data, i.e. the pre-setting for the rolling stand before the rolling process starts. It can be identified that the input data are equipment data, data about technical limits, material data, data about rolling strategy, coil data, product data and / or optionally also production plan data.

[0018] Traditionally, the input data also include a pre-set, initial, manually determined, stored in a database or table, offset of the work roll relative to the other roll in the rolling stand, which the work roll is supported relative to.

[0019] In the prior art, the target level force calculated taking into account the input data is then checked in such a way that it meets a pre-set limit criterion when rolling under constant conditions. If yes, the initial offset on which the target level force calculation is based is set at the work roll and the rolling is rolled. Then, due to the set offset, the previously calculated target level force, which meets the limit criterion, can act at the offset work roll. Compliance with the limit criterion represents a stable roll set and rolling process.

[0020] If the initially calculated target level force does not meet the pre-set limit criterion, the target level force is then recalculated in the prior art with a respectively varying offset of the work roll out of a set of N available different offsets, but otherwise with unchanged input data, until it is determined that the last calculated target level force, taking into account the last changed (optimum) offset, first optimally meets the limit criterion.

[0021] The known method forms the closest prior art. Therefore, claim 1 delimits it. The known method serves to determine the optimum offset of the work roll in which the calculated target level force is within the limit criterion, thus ensuring stable rolling conditions.

[0022] It has been shown in practice that it is not always satisfactory to calculate the target level force only by iterating the offset with otherwise constant input data, in particular with constant tension on the entry side and / or on the exit side of the rolling stand. That is, it is not always achieved with a separately varying or iterating offset that the calculated target level force meets the limit criterion. This leads to problems in particular in the case of work rolls with a high length of the strip, in particular in combination with a high strip tension, since the work roll reacts particularly severely to an excessive level force, for example with a bending of the undesired level. SUMMARY

[0023] The object underlying the present application is to improve the known method and the known computer program product for calculating a stable rolling schedule for a rolling process, in particular for flat rolling of a thin metal strip as a high-strength rolled material, in such a way that the stability of the roll set in the rolling stand and thus of the rolling process is further improved, in particular when flat rolling a thin metal strip as a high-strength rolled material by means of thin work rolls.

[0024] With regard to the method, the object is achieved by the method as claimed in claim 1.

[0025] The term "set data" relates to initialization or pre-setting data; the data is set (in advance) at the rolling stand before starting the rolling process. The data can be changed partially later during the rolling process.

[0026] The "target level force" calculated according to the application is a pure calculation variable which cannot be set directly at the rolling stand before starting the rolling process. As described, it is a resultant force which results from the vector addition of the entry tension, the exit tension and the adjustment force of the work rolls in the rolling stand, in particular. However, the "target level force" serves as a representative variable according to which it can be predicted or derived whether the rolling process is stable or not, in particular in the case of the use of high slenderness of the work rolls, according to whether the pre-set limit criteria representing the stability of the rolling process are met or not. However, the resulting level force can be derived directly during the rolling process via load cells at the bending blocks (additional structural outlay) or indirectly via load cells, pressure measuring devices in the stand or reversing rolls and torque measurements at the work spindles for the drive side and the operating side of the stand (software sensors).

[0027] The slenderness defined by the ratio of the bearing center distance to the work roll diameter is a characteristic variable which, as described above, has an effect on the stability of the rolling process. From a slenderness of 5 or more, the risk of instability increases significantly.

[0028] Deriving the optimum tension acting on the rolled material on the entry side and / or on the exit side of the rolling stand in the manner claimed according to the application offers the advantage that the target level force itself can also remain within the limit criteria if this is not possible by a separate iterative offset change.

[0029] A further advantage of taking the target level force into overall consideration is the minimization of the bearing load of the entire roll set, which significantly improves the service life of the roll chocks.

[0030] According to a first embodiment of the application, the target level force is calculated individually or separately for different sections k of the metal strip to be rolled, since the metal strip has different speeds and is subjected to different strip tensions in its different sections.

[0031] According to a second embodiment of the application, the limit criterion for the horizontal stability of the rolling process, in particular of the work roll, is defined as a limit criterion according to which

[0032] 1. the calculated at least two target horizontal forces of different sections of the metal strip must have the same sign; and / or

[0033] 2. the calculated target horizontal forces do not exceed the respectively preset material-dependent load limit of the work roll.

[0034] According to a third embodiment, the calculated target horizontal force can be kept within the limit criterion itself, if this is not possible by changing the bias and the pulling force on the entry side and / or on the exit side of the rolling stand only. To this end, the third embodiment proposes that the adjustment force of the work roll is additionally varied also with the optimum bias remaining constant and the optimum pulling force remaining constant respectively and also with the input data remaining constant otherwise, until it is determined that the last calculated target horizontal force meets the limit criterion.

[0035] According to a further embodiment, the input data of the pass schedule computer are in particular also data for the technical limits. According to the application, this includes in particular the material-dependent load limit for the horizontal stability of the roll set of the rolling stand, the limit value for the horizontal force including the sign, the limit value for the force and the work requirement, the limit value for the position of the critical interface, the limit value for the overhang and the limit value for the torque of the rolls of the rolling stand. According to the application, the material-dependent load limit for the horizontal stability of the roll set and in particular of the work roll is taken into account in particular when calculating the target horizontal force acting on the work roll, the target position of the level of the work roll, the target pulling force of the rolled piece at the entry opening and / or at the exit opening of the rolling stand and when calculating the target reduction of at least one pass of the rolling stand.

[0036] The taking into account of the material-dependent load limit claimed when calculating the target setting data provides the advantage that the stability of any intermediate rolls and roll sets of the support rolls of the rolling stand in addition to the work roll and thus also the stability of the rolling process as a whole is improved. This is to say that an undesired course of the strip to the left or to the right at the exit opening of the rolling stand, strip tearing, roll engagement and roll bending or curving are avoided or at least minimised. By taking into account the material-dependent load limit it is also achieved that thin rolled piece thicknesses desired by the rolling customer, which are very high in strength values, are achieved on conventional 4-high, 6-high rolling stands, multi-rolling stands or also on rolling stands with an odd number of rolls, even with an asymmetric arrangement of the rolls, without the need to provide additional mechanical or fluid components for supporting the rolls at the rolling stand.

[0037] The stable boundary conditions achieved by the method according to the application can advantageously be predetermined for the rolling process and can already be ensured by pre-setting the (target) setting data at the rolling stand before the rolling process is started. In this way, the automatic threading of the rolling stock into and out of the rolling stand can also be ensured stably without additional devices. During the running of the rolling process, the method according to the application achieves that the target setting data and possibly its profile are permanently monitored in order to ensure the stability of the rolling process also during continuous operation. By the method according to the application, the production range of an existing rolling facility can be extended independently of the number and configuration of its rolling stands, for example to thinner final thicknesses. Furthermore, smaller work rolls can be used for the rolling stand in order to roll the thinner final thicknesses and in order to save energy at the same time.

[0038] According to a further embodiment, the method according to the application is not only used in a single rolling stand, but also in a rolling mill in which a plurality of rolling stands are arranged one after the other in the form of a rolling line. According to the application, the target setting data can be calculated and set not only for a single rolling stand, but also for the entire pass schedule of the rolling line, i.e. preferably for all its rolling stands, taking into account the material-related load limits.

[0039] According to a further embodiment of the application, the actual horizontal forces acting on the work rolls during the rolling process are permanently monitored and adjusted to the target horizontal forces currently calculated by the pass schedule computer, respectively. The adjustment of the horizontal forces takes place by appropriate changes of the adjusting elements provided at the rolling stand, i.e. for example the horizontal bias of the work rolls, the pulling forces of the rolling stock on the entry side and / or on the exit side of the rolling stand and / or the thickness reduction carried out by the rolling stand at the rolling stock (adjusting forces).

[0040] A further improvement of the stability of the rolling process can be achieved in that production planning data, i.e. for example data relating to rolling program optimization, data from production planning, plant planning and facility utilization, are additionally taken into account together when calculating the target setting data.

[0041] The measurement data obtained when monitoring the running rolling process, i.e. for example the actual horizontal forces, the actual horizontal position of the work rolls, the actual pulling forces acting on the rolling stand at the entry and / or exit of the rolling stand and / or the actual thickness reduction of the rolling stock through the rolling stand, are preferably compared with the respective associated current target setting data. Deviations between the target and actual values that can be identified in this way can be used for the continuous adaptation of the process model.

[0042] Further advantages of the design variants of the method according to the application are the subject matter of the dependent claims.

[0043] The above objects are also achieved by a computer program product. The advantages of the computer program product correspond to the above-mentioned advantages with reference to the claimed method. BRIEF DESCRIPTION OF DRAWINGS

[0044] The invention is in total accompanied by 8 drawings, wherein

[0045] Figure 1 A general system showing a pass schedule computer and its input data and output data, wherein the important input data and output data of the invention are underlined;

[0046] Figure 2 A flow chart showing the method according to the invention for calculating the target horizontal force according to a first embodiment;

[0047] Figure 3 A technical correlation and distinction (prior art) is shown when the metal strip to be rolled enters and leaves the rolling stand;

[0048] Figure 4a , 4b A flow chart showing the method according to the invention for calculating the target horizontal force according to a second embodiment of the invention;

[0049] Figure 5 A flow chart showing the method according to the invention with additional adaptation of the process model;

[0050] Figure 6 An undesired horizontal bending of the work roll with high length of the work roll (prior art) is shown;

[0051] Figure 7 A misalignment of the work roll relative to the intermediate roll or support roll supporting the work roll in the rolling stand and the associated force parallelogram (prior art) is shown; and

[0052] Figure 8 A general system showing a pass schedule computer and its input data and output data according to prior art. DETAILED DESCRIPTION

[0053] The invention is described in detail below with particular reference to Figures 1 to 5 The invention is described in detail below with particular reference to

[0054] Figure 1This paper illustrates a process for performing complex calculations on the pass planning of at least one rolling mill stand according to the method of the present invention. A core component for controlling the rolling process of a rolled product via at least one rolling mill stand is a so-called pass planning computer, on which a process model of the rolling process is run. The process model describes the complex re-forming process in the rolling gap using known fundamental formulas of re-forming technology and the state of the roll group. The roll group may include, in addition to the work rolls that open the rolling gap of the rolled product, intermediate rolls and / or support rolls of the rolling mill stand. By running the process model on the pass planning computer, pre-calculations for the next rolled product to be rolled after the current rolled product, recalculations involving the current rolled product, or superimposed product optimizations can be performed. In order for the pass planning to be calculated, input data is fed to the pass planning computer, which must be stored in a suitable manner, for example, in a database or parameter file, so that the pass planning computer can access the input data. For example, a rolling mill stand or multi-stand mill must be described via equipment data as input data. Furthermore, mandatory technical limitations apply to the rolling process. Furthermore, the behavior of the re-forming technology for the rolled material must be described mathematically using its material data.

[0055] Furthermore, the rolled material must be defined using product data. Additionally, coil data and rolling strategies must be preset using strategy data as input data. Furthermore, production planning data can also be considered for higher-level objectives, such as facility utilization or rolling process optimization. All terms mentioned for the input data are... Figure 1 The collective term for the different individual data shown in the text.

[0056] Based on the input data and the boundary conditions, the track planning computer then calculates so-called setup data, hereinafter referred to as target or initialization data, for the rolling process to be executed next, and sends the setup data to at least one rolling stand in advance.

[0057] The course schedule calculated according to the prior art is shown. Figure 8 Different, according to Figure 1 The data for technical constraints according to the invention include load limits related to the roll material for the horizontal stability of the roll set, as well as data for process technical constraints, such as the permissible sign switching of the horizontal force during different rolling stages in the pass plan. Another difference from the prior art is that the horizontal stability HS position, i.e., the offset of the work roll relative to another roll supporting it in the rolling mill, and / or the HS force, i.e., the horizontal force during the running rolling process, is determined and preferably measured, and is used in particular for adapting process models.

[0058] The most important difference from existing technologies is that at least some setting data ( Figure 1 The "Set Data" block (underlined) not only presets the data once for the entire rolling process, but also iteratively calculates it to achieve the highest possible stability of the rolling process. Specifically, the calculation of the horizontal stability of the roll set, particularly the horizontal force acting on the work rolls, is integrated into the pass planning calculation.

[0059] The use of the data, which differs from that in the prior art, within the scope of this invention is described in more detail below.

[0060] Figure 2 The flowchart of the method according to the invention, as particularly claimed in claim 1, is illustrated schematically. Within the scope of the method according to the invention, in the first iteration, in the first method step i), input data is provided to the track planning computer, as referenced above. Figure 1 As described. According to the invention, the input data further includes an initial bias saw of the work roll relative to another roll in the rolling mill that supports the work roll. The initial bias can be obtained from a table or database, but is preferably obtained from... Figure 7 The target horizontal force is calculated from known formulas, where the tensions Ze and Za are set to zero for this purpose. Before and / or during the rolling process, the method according to the invention then provides: in the second step ii), the target horizontal force acting on the work roll is calculated using a pass planning computer. For this purpose, a process model of the rolling process is run on the pass planning computer, and the pass planning computer calculates the target horizontal force taking into account the input data.

[0061] In the subsequent third method step iii), the target horizontal force previously calculated by the pass planning computer using the initial bias is checked as follows: whether it meets a preset limit criterion. The limit criterion represents the horizontal stability of the rolling process, particularly the horizontal stability of the work rolls. According to the invention, the limit criterion is defined such that…

[0062] 1. At least two calculated horizontal forces from different sections of the metal strip must have the same sign; and / or

[0063] 2. The calculated target horizontal forces shall not exceed the preset material-related load limits of the working rolls.

[0064] For cases where the calculated target horizontal force satisfies the limit criterion, the method according to the present invention proposes: setting the (optimal) offset saw at the rolling mill stand on which the calculation of the target horizontal force is based. opt That is, the initial offset is given here, and the rolled material or strip is then rolled with the initial optimal offset. Since the optimal offset can be based on: then rolling is also performed using a target horizontal force calculated to satisfy the limit criterion.

[0065] Otherwise, i.e. if the target level force calculated by means of the initial bias cannot satisfy the limit criterion, the method according to the application proposes that steps i), ii) and iii) are repeated with a corrected / changed bias of the work roll out of a set of N available different offsets, but otherwise with changed input data, in a further maximum of N iteration steps, until finally in step iii) it is determined that the finally calculated target level force satisfies the limit criterion, taking into account the finally changed or set optimum bias.

[0066] For the case that the calculated target level force cannot satisfy the limit criterion for all N biases available, the method according to the application proposes that steps i), ii) and iii) are repeated with a respectively changed strip tension Ze on the entry side of the rolling stand acting on the strip out of a set of L (L e N) available different strip tensions on the entry side of the rolling stand and / or with a respectively changed strip tension Za on the exit side of the rolling stand acting on the strip out of a set of M (M e N) available different strip tensions on the exit side of the rolling stand and with the respectively constant optimum bias saw opt and otherwise unchanged input data, in a further maximum of L and / or M iteration steps, until finally in step iii) it is determined that the finally calculated target level force satisfies the limit criterion, taking into account the finally changed optimum strip tension. The optimum bias is the bias for which the target level force calculated in the preceding performed bias iteration is closest to satisfy the limit criterion.

[0067] In Figure 2 the method according to the application is shown, wherein the abbreviation "saw" stands for the bias of the work roll, the abbreviation "Ze" stands for the strip tension on the entry side of the rolling stand and the abbreviation "Za" stands for the strip tension on the exit side of the rolling stand.

[0068] According to the application, the calculation of the target level force is not uniformly calculated for the entire metal strip, but is individually calculated for different sections of the metal strip. This is meaningful, because the speed of the metal strip to be rolled through the rolling stand and the acceleration and friction conditions applied to the metal strip in the entry section of the metal strip are different from the speed, acceleration and friction conditions of the metal strip during rolling of the middle section (body) of the metal strip when the metal strip is braked and during rolling of the exit section, wherein the metal strip enters into the rolling stand or its rolling gap with the entry section. In addition to the speed, acceleration and friction conditions, the strip tension applied to the metal strip is different for the sections of the metal strip.

[0069] Figure 3 The technical associations generally known in the prior art are explained.

[0070] The problem is solved by the present application by calculating the target horizontal force for each section k e N of the metal strip as described. In the metal strip, a distinction is made between the entry section for k = 1, the middle section (body) for k = 4 and the exit section for k = 7. According to the present application, for at least two of the sections, the target horizontal force is calculated individually in the form of the horizontal force Haweinl acting on the work roll when the rolled object is threaded into the rolling gap of the rolling stand with its entry section for k = 1, in the form of the horizontal force Hawfilet acting on the work roll when the rolled object is rolled in the body for k = 4 and / or in the form of the horizontal force Hawausl when the rolled object is threaded out of the rolling stand with its exit section for k = 7 by means of the following: Figure 2 The individual traversal of steps i), ii) and iii) is carried out to calculate each target horizontal force in the respective section of the metal strip.

[0071] Figure 4a A further embodiment of the method according to the present application is shown for the case in which the calculated target horizontal force neither in the case of individual iterative changes of the bias nor in the case of individual iterative changes of the strip tension Ze on the entry side of the rolling stand nor in the case of individual changes of the strip tension Za on the exit side of the metal strip leads to the respective calculated target horizontal force meeting the limit criterion. For this case, the method according to the present application proposes that first the optimum bias out of a set of L available different tensions on the entry side of the rolling stand and / or the optimum bias out of a set of M available different tensions on the exit side and / or the optimum bias out of a set of H available adjustment forces, where h = 1... H, is selected, by means of which the target horizontal force calculated with the optimum bias remaining constant and otherwise the input data remaining constant meets the limit criterion optimally. Then, with the optimum bias thus selected and the optimum tension thus selected, the method steps i), ii) and iii) according to the present application are repeated with the respectively iteratively changed adjustment force FAh out of the set of H available adjustment forces until it is determined in step iii) that the last calculated target horizontal force meets the limit criterion. The optimum values thus found for the bias, the strip tension on the entry side and on the exit side of the rolling stand and the adjustment force are set at the rolling stand before and during the rolling process. Since the calculation of the optimum values for the respective section of the metal strip is carried out individually, the calculated optimum parameters are also set anew individually during the rolling process depending on which section of the metal strip is just being rolled.

[0072] The calculated target level force cannot be directly preset at the rolling stand, unlike the optimum parameters iteratively determined according to the method according to the application. Rather, the target level force is a resultant force which is automatically set and derived when the parameters are set at the rolling stand. If the optimum values for the parameters are set, it should be ensured that the target level force will meet the limit criteria and the process will run stably.

[0073] If the metal strip to be rolled does not only pass through one rolling stand, but a rolling mill having a plurality of rolling stands arranged in succession in the rolling direction, the target level force for the work rolls is determined separately in each stand in the scope of the pass schedule calculation and the associated iteratively determined optimum parameters of the pass sequence are preset or set separately at the work rolls of the rolling stands.

[0074] It has already been mentioned above with reference to Figure 1 and 8 that technical limits are also delivered as input to the pass schedule computer. According to the application, these are, inter alia, the material-dependent load limits for the horizontal stability of the roll necks of the rolling stands, the limit values including the sign of the level force and the limit values of the force requirements and work requirements, the limit values of the critical plane positions, the limit values of the overhangs and the limit values of the torques of the drives, for example the limit values of the torques of the drives for the rolls of the rolling stands.

[0075] The calculation of the HS offset to be set in consideration of the permissible level force can be carried out exemplarily as follows, see Figure 4b ):

[0076] For the set rolling passes from an entry thickness of 2.0 to 0.793 mm at a strip width of 1162 mm and a work roll diameter of 330 mm, the strip tension Ze, Za specific to the pass schedule is first determined. In addition, the resulting adjustment force FA, but especially the level force Hawin, Hawmain, Hawout is calculated for the infeed and outfeed phases for k = 1, k = 7 and for the strip main pass for k = 4, more precisely in consideration of the different possible settable offset positions saw. The facility-specific and re-forming-technical parameters are taken into account for setting the optimum offset position.

[0077] The calculations show that the horizontal force Haw changes in the case of a constant adjustment force (FA), a constant tensile force (Ze / Za) and a different bias position saw. However, it needs to be determined what the horizontal force Haw or the total resultant horizontal force Fres is in the different rolling stages k. If the horizontal force Haw or Fres in the rolling stages k = 1, k = 4, k = 7 exceeds the permissible limit value which is preset by the second limit criterion according to the application, this leads to damage to the rolls or to an unstable process (non-flat, undesired hysteresis) which in turn leads to production failure. The permissible value is calculated as shown in Figure 4a ).

[0078] If the bias position causes a sign change between the sections of the metal strip (first limit criterion), this thus causes an undefined unstable rolling situation which not only leads to poor flatness values, but also to the free movement of the rolls which can lead to damage to the rolls and their bearings and to the adjacent rolls. In addition, the crossing of the work roll or the adjacent roll is a serious problem with regard to the strip run. The strip is pushed laterally out of the rolling gap. The result is diagonal waviness or even tearing of the strip. If the horizontal force is too small, the tendency of the stand to vibrate increases and the quality tolerances cannot be adhered to. If the horizontal force is too great, the dynamics of the adjustment of the hydraulic adjustment are negatively affected by the increased hysteresis.

[0079] It becomes apparent in the calculation example according to Figure 4b that for the two bias positions saw = -8 and -6, no sign change occurs in the respective calculated horizontal force Haw in the 3 strip sections k = 1, k = 4, k = 7, but for the bias position saw = -8, the respective horizontal force acting on the work roll Haw is higher than the permissible limit value of the material-dependent load limit of here, for example, 80 kN in size, by the value of the minimum Fbaw of 84.3 kN.

[0080] In order to find the load and its limits, both the resulting horizontal force Haw / 2 and the maximum bending force FaBW are taken into account and compared to the permissible limit criterion as the total resultant force Fres.

[0081] Since all the conditions are advantageously met with a bias saw of -6, in the example according to Figure 4b -6 mm is set as the optimum bias for the rolling pass.

[0082] If the calculation of the horizontal load and the possible bias position from the set N does not achieve the permissible setting, then, as above with reference to Figure 2 and 4aAs described, the pass schedule needs to be adapted automatically. The strip tension, the pass drop, the rolling force or the adjusting force and, if necessary, even the work roll diameter (for example with new work rolls or ground work rolls) can be adapted. The values resulting from the pass schedule calculation are automatically compared with the values of the calculated horizontal load until a stable condition is obtained.

[0083] Figure 5 Another aspect of the method according to the application is shown. As Figure 1 As already shown in the introduction, the aspect proposes to permanently monitor the running rolling process by means of different measurement data, in particular at least one actual horizontal force and / or actual horizontal position (= offset) from at least one of the work rolls, preferably periodically, and to compare the actual horizontal force thus determined with the respective current target horizontal force and / or to compare the actual horizontal position with the respective current target horizontal position of the work rolls. The comparison consists in particular in forming a difference. Then, according to the application, the deviation (Delta) between the target value and the actual value, which can be identified in this way, is checked in such a way that it is asked whether the deviation lies within a preset permissible range. If this is the case, the deviation is used for a preferably continuous adaptation of the process model running on the pass schedule computer. The process is thus self-learning. If the deviation (Delta) between the target value and the actual value is not permissible, the strip tension is adapted during the ongoing pass in such a way that the deviation determined becomes permissible again as far as possible.

[0084] The measurement data can be, for example, the rolling force applied by the at least one rolling stand to the rolled material, the thickness of the rolled material, the temperature of the rolled material, the rolling speed, the offset of the work rolls, the tensile load acting on the rolled material, the motor torque of the drive associated with the rolling stand, for example for adjusting or rotating the rolls, and / or cooling data, for example representing the cooling of the rolled material.

[0085] The at least one, preferably both, work rolls of the rolled material of the rolling stand are driven.

[0086] The rolling stand can be designed as a reversing stand, in which the rolled material is then rolled in the reverse direction by means of the rolling stand.

[0087] Additional measures to improve the application:

[0088] The application can likewise be used for single stands and tandem rolling lines, as well as for single-direction and reversing operation. It is suitable for 4Hi and 6Hi as well as j-Hi (j = 2 to 6) rolling stands.

[0089] - A known HS displacement system is used to set the bias position saw. The HS displacement system is structurally in the area of the roll insert and is fixed at the roll stand. Thus, no additional mechanical equipment is provided at all along the roll barrel. The area can be used for effective roll cooling / lubrication, inductors, brushes and strip guiding elements.

[0090] - The depletion of the allowable and possible drive torques of the small work rolls can be carried out by using high-torque HT spindles with torque or temperature monitoring.

[0091] - The double drive of the work rolls reduces the possible torque fault between two work rolls, which in turn can also be used as an additional measure to reduce the resulting horizontal forces or to further reduce the roll diameter.

[0092] - The integration of the automatic pass schedule calculation / generation with the calculation of the horizontal forces and the different level of automation.

[0093] - The basic automation (level 0, level 1) ensures that the calculated target values are set compulsorily. If the target values are not set (comparison of the target values with the actual measured values), it is indicated that a barrier is entered.

[0094] - The calculation of the integral of the horizontal forces and the pass schedule calculation are components of a physical process model (level 2) or a subset (submodel level 2).

[0095] - The model and / or the pass schedule calculation with the associated calculation of the horizontal forces can have a superimposed optimization algorithm. The optimization can take place in a self-learning manner or via adaptation and, if necessary, taking into account the current measured values.

[0096] - A connection to a production planning tool (level 2 1 / 2 or level 3) can be provided. Thus, a technically not stably established pass sequence can be established by other production routes without problems at the rolling facility itself. Alternatively, an adaptation can take place by association with the production planning tool of the product to be manufactured in order to avoid standstills at the facility.

[0097] - A joint with an automatic maintenance plan (level 2 1 / 2 or level 3) can be provided in order to achieve a fine adjustment by means of the work roll diameter used.

[0098] - A comparison of the pre-calculated resulting horizontal forces with the measured horizontal forces takes place. For the measurement, force measuring devices (e.g. piezo elements, pressure measuring devices, strain gauges or load cells) can be provided in the area of the bending device. Alternatively, the measurement can be indirectly calculated via the participating measurable parameters via digital soft sensors.

[0099] The comparison of the calculated and measured values of the horizontal force can be implemented by a learning algorithm as a component of the process model or submodel, so that a model-based calculation can be adapted (long / short-time adaptation).

Claims

1. A method for calculating a pass schedule for a stable rolling process when rolling at least one segment of a metal strip in a rolling mill stand, the method comprising the steps of: i) Provide input data for the track planning computer, wherein the input data also includes a preset initial offset of the work roll relative to the other rolls in the rolling stand; and Before and / or during the rolling process ii) Taking into account the input data, the target horizontal force acting on the work roll is calculated by means of the pass planning computer, and the rolling process model is run on the pass planning computer. and iii) Check whether the target horizontal force calculated by the track planning computer meets the preset limit standard; If so: set the bias on which the calculation of the target horizontal force is based at the working roll, and roll the workpiece with the obtained target horizontal force; or If not: Repeat steps i), ii), and iii) using each changed bias from the set of N different available biases of the work roll and using input data that is otherwise unchanged, until it is determined in step iii) that the final calculated target horizontal force satisfies the limit criterion, taking into account the last changed bias. Its features are, If iteratively repeating steps i), ii), and iii) using individual variations of the bias does not result in the target horizontal force satisfying the limit criterion in step iii), then the method proposes the following first modification in step iii) in the "If No" option: From a set of N biases, the optimal bias is selected such that the calculated target horizontal force optimally satisfies the limiting criterion with the optimal bias. Using varying tensions acting on the rolled material on the entry side of the rolling mill from a set of L available different tensions and / or using varying tensions acting on the rolled material on the exit side of the rolling mill from a set of M available different tensions, and using optimal biases that remain constant and otherwise unchanged input data, repeat steps i), ii), and iii) until it is determined in step iii) that the final calculated target horizontal force satisfies the limit criterion, taking into account the final changed tensions.

2. The method according to claim 1, Its features are, The metal strip to be rolled has one or more sections; when the metal strip to be rolled has one section, it has only one entry section; when the metal strip to be rolled has two sections, it has an intermediate section as the main body; and when the metal strip to be rolled has three sections, it has an exit section. and The target horizontal force is calculated individually for at least one of the segments by traversing steps i), ii), and iii) separately to calculate each of the target horizontal forces in the various segments of the metal strip, in the form of a horizontal force acting on the work roll when the rolled product is inserted into the rolling gap of the rolling mill stand with its entry segment, in the form of a horizontal force acting on the work roll when the body of the rolled product is rolled, and / or in the form of a horizontal force when the rolled product is exited from the rolling mill stand with its exit segment.

3. The method according to claim 1 or 2, Its features are, The limiting criterion for the horizontal stability of the rolling process is defined as the limiting criterion, and according to the limiting criterion:

1. At least two calculated target horizontal forces applied to different sections of the metal strip must have the same sign; and / or 2. The calculated target horizontal forces do not exceed the preset material-related load limits of the working rolls.

4. The method according to claim 3, characterized in that, The limiting standard for the horizontal stability of the rolling process is the limiting standard for the horizontal stability of the work rolls.

5. The method according to claim 1 or 2, Its features are, If iteratively repeating steps i), ii), and iii) with varying tension while maintaining the optimal bias does not result in at least one calculated target horizontal force satisfying the limiting criterion in step iii), then the method is modified in the "If No" option as follows: Select the optimal tension from the set of L different available tensions on the entry side and / or from the set of M different available tensions on the exit side, and calculate the target horizontal force such that the optimal tension satisfies the limit criterion while keeping the optimal offset constant and otherwise keeping the input data constant. Steps i), ii), and iii) are repeated with the adjusting force of the work rolls being iteratively changed, while keeping the optimal bias and the optimal tension constant, and in addition to keeping the input data constant, until it is determined in step iii) that the final calculated target horizontal force satisfies the limit criterion.

6. The method according to claim 1 or 2, Its features are, Multiple rolling stands are sequentially arranged along the rolling direction in the rolling mill; For each of the multiple work rolls in a rolling mill stand arranged sequentially, at least one target horizontal force is determined individually; and The optimal parameters associated with or iteratively determined for the pass sequence at the work rolls of the rolling mill stand are preset or set.

7. The method according to claim 1 or 2, Its features are, The input data includes equipment data, technical limitation data, material data, rolling strategy data, coil data, product data, and / or production plan data.

8. The method according to claim 7, Its features are, The data subject to the technical limitations must have a limit value for at least one of the following parameters: Material-related load limits for the horizontal stability of the roll set of the rolling mill stand, limit values ​​including signs for horizontal forces, limit values ​​for force and working requirements, limit values ​​for the position of the critical surface, limit values ​​for lead and limit values ​​for the torque of the drive.

9. The method according to claim 8, Its features are, The driver is a driver for the rolls of the rolling mill stand.

10. The method according to claim 3, Its features are, Measurement data is detected during the ongoing rolling process.

11. The method according to claim 10, Its features are, Measurement data is cyclically monitored during the ongoing rolling process.

12. The method according to claim 10, Its features are, During the ongoing rolling process, detect at least one actual horizontal force and / or actual horizontal position of at least one work roll; and The actual horizontal force is compared with each current target horizontal force and / or the actual horizontal position is compared with each current target horizontal position of the work roll.

13. The method according to claim 12, Its features are, The deviation between the target value and the actual value that may be identified in this way is checked: whether the deviation is within a preset allowable range; and If permitted: The deviation is then used to adapt the process model running on the track planning computer.

14. The method according to claim 13, Its features are, The deviation is used for continuous adaptation of the process model running on the track planning computer.

15. The method according to claim 13, Its features are, The measurement data are: the rolling force applied to the rolled material by at least one rolling mill stand, the thickness of the rolled material, the temperature of the rolled material, the rolling speed, the bias of the work rolls, the tensile load acting on the rolled material, the motor torque of the drive associated with the rolling mill stand, and / or cooling data.

16. The method according to claim 15, Its features are, The measured data is the motor torque of the driver used to adjust or rotate the rolls.

17. The method according to claim 15, Its features are, The cooling data represents the cooling of the rolled product.

18. The method according to claim 1 or 2, Its features are, At least one roll of the rolling mill stand is driven.

19. The method according to claim 18, Its features are, The two rolls that drive the rolling mill stand.

20. The method according to claim 1 or 2, Its features are, The rolling mill is structured as a reversible frame; and The rolled material is rolled in reverse operation using the rolling mill stand.

21. A computer program product capable of being directly loaded into the internal memory of a digital computer, and comprising a software code segment that, when the product is run on a computer, performs the steps of the method according to any one of the preceding claims by means of the software code segment.

22. The computer program product according to claim 21, characterized in that, The computer program product can be directly loaded into the memory of the rolling mill stand or rolling line pass planning computer.

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