Rolling with minimal bending force reduction upon entry.

Abstract

In the rolling mill stand (1), a flat workpiece (8) made of metal is rolled. The work roll inserts (5) are squeezed apart by the bending system (10). A basic setpoint (FBB*) is provided to the bending feedback controller (14), and the bending feedback controller (14) determines a composite setpoint (FB*) taking into account the basic setpoint. The actual value of the bending force (FB) is also provided to the bending feedback controller (14). The bending feedback controller (14) thereby determines the basic manipulated variable (SB) of the bending system (10) such that when the bending system (10) is driven with the basic manipulated variable (SB), the actual value (FB) is as close as possible to the basic setpoint (FBB*). From the stabilization time point (t3) after the entry time point (t2), the bending feedback controller (14) determines the composite setpoint (FB*) with additional consideration of the actual rolling force (F). During the entry period, which begins before the actual entry time (t2) and ends no later than the stabilization time, an additional setpoint (FBZ*) is provided to the bending feedback controller (14), which takes this into account when determining the composite setpoint (FB*). Thus, the actual value of the bending force (FB) is greater than the basic setpoint (FBB*). Alternatively or additionally, an additional manipulated variable (SZ) is added to the basic manipulated variable (SB), or the adjustment variable (SR) provided to the bending system (10) is downwardly limited by the minimum manipulated variable (SM).

Description

Technical Field

[0001] This invention is based on a method for operating a rolling mill stand for rolling flat workpieces made of metal, the workpiece having a head.

[0002] -Among them, the rolling mill stand has at least work rolls and support rolls.

[0003] - In this system, a bending system that presses open the work roll embedding part, while the work roll is installed in the work roll embedding part, acts on the work roll embedding part.

[0004] -Among them, the head of the rolled piece arrives at the rolling mill stand at the actual entry time.

[0005] - Here, the basic setpoint is provided to the bending feedback controller, and the bending feedback controller determines the composite setpoint by taking the basic setpoint into account.

[0006] -In this process, the actual value of the bending force is further provided to the bending feedback controller.

[0007] The bending feedback controller determines the basic manipulated variables of the bending system based on the synthesized setpoint and the actual values, so that when controlling the bending system using the basic manipulated variables, the actual values ​​are as close as possible to the synthesized setpoint.

[0008] -In this context, the bending feedback controller determines the composite setpoint starting from the stable time point after the entry time point, taking into account the actual rolling force that occurs when rolling a flat piece.

[0009] The present invention is also based on a rolling unit for rolling flat workpieces made of metal, the rolling unit having a workpiece head.

[0010] -The rolling unit includes a rolling mill stand and a bending feedback controller.

[0011] -The rolling mill stand has at least a work roll and a support roll installed in the work roll embedding section.

[0012] -Among them, the rolling mill stand has a bending system that presses open the embedded part of the work roll.

[0013] -Among them, the bending feedback controller drives the bending system.

[0014] -In this process, the rolling mill stand and the full controller interact with each other during the operation of the rolling unit.

[0015] This enables them to execute such a method. Background Technology

[0016] Rolling stands used for rolling flat products are typically designed as four-high stands (i.e., rolling stands with work rolls and support rolls) or six-high stands (i.e., rolling stands with work rolls, support rolls, and intermediate rolls arranged between the work rolls and support rolls). They are usually rolled with metal strips, and sometimes with thick plates.

[0017] A rolling schedule calculation is performed before rolling the corresponding workpiece. Within the scope of the rolling schedule calculation, the setpoints for each actuator of the rolling mill stand are determined, and these actuators will operate according to these setpoints when rolling the corresponding workpiece. The setpoints include at least an adjustment amount or rolling force. They typically also include a setpoint for bending force (hereinafter referred to as the basic setpoint), by which the work roll insert should be pressed down and, consequently, the work roll should be pressed open. Bending force can be used to affect the shape, profile, and flatness of the workpiece.

[0018] Other actuators can also exist to influence shape, profile, and flatness, such as work roll displacement or localized cooling. For stainless steel rolling mill stands, lubrication of the strip edges can also affect the profile. However, other actuators are not relevant within the scope of this invention.

[0019] The pass roll schedule calculation is performed by a higher-level control device, commonly referred to in the industry as an L2 system. The setpoints determined as part of the pass roll schedule calculation are forwarded by the control device to the lower-level controller, which performs real-time control during the rolling process. This entire controller is typically referred to in the industry as an L1 system. The setpoints are specified before the workpiece reaches the roll gap between the work rolls of the rolling mill stand (i.e., before entry).

[0020] For example, the setpoint for the bending force (i.e., the basic setpoint) is assigned to the bending feedback controller. This setpoint is modified during the rolling process of the flat roll using various correction variables. One of these correction variables is an additional setpoint, which is determined as a function of the rolling force and, similar to the AGC, is designed to compensate for changes in rolling deformation caused by variations in the rolling force. However, this additional setpoint is only applied after the L1 system controller has readjusted to address any instabilities that occurred upon re-entry.

[0021] Therefore, the bending feedback controller determines the basic manipulated variables for the bending system during the entry time period based solely on the basic setpoint and the actual value of the bending force, and controls the bending system during this entry time period, which begins before the entry point and ends after the entry point. This determination is thus achieved so that the actual value of the bending force is always as close as possible to the basic setpoint.

[0022] Upon entry, the bending force (i.e., its actual value) decreases. The bending feedback controller attempts to correct this decrease as quickly as possible. However, it takes hundreds of milliseconds (sometimes as long as 500 milliseconds) before the system is fully corrected.

[0023] On the one hand, a decrease in bending force negatively impacts the final shape and related profile, as well as the flatness of the rolled piece. However, this is generally acceptable. On the other hand, a decrease in bending force can lead to short-term instability, the effects of which on strip operation are not always predictable. In particular, hooks may form in the rolled piece on the exit side of the rolling mill. In some cases, the hooks become so large that they impact the side rails downstream of the rolling mill. This can cause damage to the side rails, and in some cases, even cause the head of the rolled piece to become stuck. In this situation, the head of the rolled piece is no longer fed further, while the rolling mill continues to push the rolled piece. As a result, the rolled piece lifts up (so-called bulging). This at least leads to unplanned, prolonged interruptions in the operation of the rolling mill, and sometimes even serious damage to the rolling mill or downstream equipment.

[0024] DE 102006059 709A1 discloses a method for operating a rolling mill stand for rolling flat workpieces made of metal, wherein the work rolls of the rolling mill stand are subjected to a bending force before the head of the workpiece arrives. The rolling mill stand has a balancing force at least as large as that of the upper work roll and the upper support roll (and other rolls possibly disposed between the upper work roll and the upper support roll). The bending force is determined according to the process requirements of the rolling process from the point where the head of the workpiece arrives at the rolling mill stand. The resulting bending force can be greater than or less than the minimum force, and can also be greater than or less than the balancing force.

[0025] A method for operating a rolling mill stand for rolling flat workpieces made of metal is known from JP S57050207A, wherein the time point at which the head of the workpiece arrives at the rolling mill stand is calculated in advance. From this point onward, the work rolls of the rolling mill stand are subjected to bending forces through a bending system.

[0026] JP S59061512A discloses a method for operating a rolling mill stand for rolling flat sections made of metal, wherein a ring lifter arranged upstream of the rolling mill stand detects whether the section is under tension at the entrance side of the rolling mill stand. This is used to detect entry and exit. Upon entry, the bending force acting on the work rolls of the rolling mill stand is adjusted so that the thickness of the section decreases towards its side edges. During entry, once a decrease in load on the ring lifter is detected, and thus the flat section is detected exiting the upstream rolling mill stand, the bending force is adjusted in a similar manner.

[0027] DE 4331261 A1 discloses a method for operating a rolling mill stand for rolling flat rolled products, wherein the work rolls can withstand positive and negative bending forces of different magnitudes through a bending system. Summary of the Invention

[0028] The purpose of this invention is to provide a feasible method that can avoid unstable states as much as possible.

[0029] This objective is achieved by an operating method having the features of claim 1. Advantageous designs are those described in dependent claims 2 to 7.

[0030] According to the present invention, the operating method of the aforementioned type is designed to, during an entry time period that begins before the actual entry time and ends after the actual entry time,

[0031] - In addition to the basic setpoint, additional setpoints are provided to the bending feedback controller so that the bending feedback controller can determine the composite setpoint and actual value during entry, taking into account not only the basic setpoint but also the additional setpoint. Therefore, the bending force is greater than the basic setpoint before the actual entry time point, and / or

[0032] - By applying additional manipulated variables to the basic manipulated variables, a synthetic manipulated variable is determined, which is then provided to the bending system, and the bending system is thereby controlled such that the synthetic manipulated variable is greater than the basic manipulated variable, and / or

[0033] - The basic and minimum manipulated variables are fed to the selection element, and the selection element feeds the maximum value of the basic and minimum manipulated variables to the bending system.

[0034] If the actual value of the bending force before the entry point is greater than the basic set value, the bending force begins to decrease at a higher level. This reduces the feasibility and extent of potential hook formation. If the composite manipulated variable is greater than 0, the hydraulic valve is at least partially open upon entry, through which hydraulic fluid is supplied to the bending system. Therefore, it is not necessary to open it at the entry point. Consequently, the entry of the rolled piece results in a smaller decrease in bending force. This also reduces the feasibility and extent of potential hook formation. By appropriately specifying the additional manipulated variable, it is possible to ensure that the resulting controlled variable is greater than 0. For example, the additional manipulated variable can be set to 110% of the maximum possible value. Even if the bending feedback controller determines the minimum possible value as the basic manipulated variable, the hydraulic valve will be open at least -100% + 110% = 10%.

[0035] As an alternative to specifying additional manipulated variables, a minimum manipulated variable can also be provided directly. In this case, if the hydraulic valve is already open by the basic manipulated variable and the minimum manipulated variable is less than the basic manipulated variable, the hydraulic valve remains open without changing its open position. However, regardless of the value of the basic manipulated variable, the hydraulic valve is always open at least to the extent specified by the minimum manipulated variable. By appropriately selecting the minimum manipulated variable (i.e., greater than 0), it is also possible to ensure that the hydraulic valve is at least partially open at the entry time.

[0036] The additional setpoint and / or additional adjustment and / or minimum adjustment can abruptly switch to their maximum values ​​at the start of the entry period. The additional setpoint and / or additional manipulated variable and / or minimum manipulated variable can also abruptly decrease to zero at the end of the entry period. However, preferably, the additional setpoint and / or additional manipulated variable and / or minimum manipulated variable increase strictly monotonically from 0 to their maximum values ​​with a finite gradient from the start of the tapping cycle and / or from their maximum values ​​to zero with a finite gradient at the end of the entry period. This results in a smoother transition, which places less stress, particularly on the bending feedback controller, hydraulic valve, and bending system, and also results in a more stable transition, especially when the additional setpoint and / or additional manipulated variable decreases to 0.

[0037] The feasibility of ascending and descending with finite slopes is well known and familiar to those skilled in the art. For example, ramps can occur or binary switching processes can be smoothed through appropriate filtering.

[0038] Typically, the expected entry time is determined by tracking the path of the rolled piece. In this case, the start of the entry time period is preferably a predetermined lead time earlier than the expected entry time.

[0039] The predetermined lead time is determined, for example, in such a way that the additional setpoint and / or the additional manipulated variable and / or the minimum manipulated variable reaches its maximum value at a point in time, the distance from which the expected entry time is at least as large as the error tolerance between the actual and expected entry times. Those skilled in the art can readily estimate the error tolerance based on the inaccuracy of the roll head path, as is known to them. The predetermined lead time is typically in the range of 0.5 s to 2.0 s, particularly between 0.8 s and 1.5 s, for example, approximately 1.0 s.

[0040] The end of the entry time period can be a predetermined delay after the expected entry time point. However, preferably, the end of the entry time period is a predetermined lag time after the actual entry time point. For example, the actual entry time point can be easily detected due to a sudden increase in the actual rolling force or the rolling torque actually applied by the drive device of the work rolls.

[0041] In both cases, the predetermined late period is defined as the time point at which the additional setpoint and / or additional manipulated variable and / or minimum manipulated variable maintain their maximum values ​​until the distance from the expected or actual tap point reaches a predetermined value. From this time point, the additional setpoint and / or additional manipulated variable and / or minimum manipulated variable can be reduced to 0. The specified value—that is, the period during which the additional setpoint and / or additional manipulated variable and / or minimum manipulated variable remain at their maximum values—is determined by the design and dimensions of the bending system. This value is typically in the range of 0.1s to 1.0s, particularly between 0.2s and 0.6s, for example, 0.3s or 0.4s.

[0042] Preferably, prior to rolling the flat workpiece, additional setpoints and / or additional manipulated variables and / or the maximum values ​​of minimum manipulated variables are determined based on the workpiece characteristics and / or the expected rolling force. Thus, the corresponding maximum values ​​can be optimally matched to the specific rolling pass to be performed. Alternatively or additionally, the maximum values ​​of the additional setpoints and / or additional manipulated variables and / or minimum manipulated variables can be determined in such a way that the composite manipulated variable immediately presents its maximum possible value before the actual entry point. This measure is particularly useful in the case of the front stand of a multi-stand finishing mill or in the case of a rolling stand used for rolling thick plates (plate mill).

[0043] The additional setpoint and / or additional manipulator and / or minimum manipulator are preferably determined such that the decrease in the actual value of the bending force is compensated by at least 50% at the actual entry point, which would be set without the additional setpoint and / or additional manipulator and / or minimum manipulator. Therefore, if the basic setpoint has a value X and no additional setpoint and / or additional manipulator and / or minimum manipulator achieves a decrease to a value Y upon entry, the additional setpoint and / or additional manipulator and / or minimum manipulator are preferably determined such that the bending force decreases to a maximum value (X+Y) / 2, preferably even only to a value greater than (X+Y) / 2. Particularly preferred is that the bending force decreases to the maximum value of the basic setpoint, i.e., value X.

[0044] This objective is further achieved by a rolling unit having the features of claim 8. According to the invention, in a rolling unit of the type mentioned at the beginning, the rolling mill stand and the bending feedback controller interact with each other during the operation of the rolling unit, causing them to perform the operating method according to the invention. Attached Figure Description

[0045] The above-described properties, features, and advantages of the invention, as well as the ways in which they are realized, will become clearer and more apparent in conjunction with the following description of embodiments explained in more detail with reference to the accompanying drawings. This is illustrated in the schematic diagrams:

[0046] Figure 1 The rolling stand before the rolled piece is shown from the side.

[0047] Figure 2 This is shown from the side when entering. Figure 1 The rolled piece, that is, at the starting point of the rolling process,

[0048] Figure 3 The rolling process of the workpiece is shown from the side. Figure 1 The rolling mill stand in the middle,

[0049] Figure 4 As shown above Figures 1 to 3 Part of the rolling mill stand,

[0050] Figure 5 It shows Figures 1 to 4 Part of the control structure of the rolling mill stand,

[0051] Figure 6 It shows the prior art Figures 1 to 4 The timing diagram of the operation method of the rolling mill stand.

[0052] Figure 7 The first embodiment of the present invention is shown. Figures 1 to 4 Part of the control structure of the rolling mill stand,

[0053] Figure 8 The first embodiment of the present invention is shown. Figures 1 to 4 The timing diagram of the operation method of the rolling mill stand.

[0054] Figure 9 A second embodiment of the present invention is shown. Figures 1 to 4 Part of the control structure of the rolling mill stand,

[0055] Figure 10 A second embodiment of the present invention is shown. Figures 1 to 4 A timing diagram of the operation method of the rolling mill stand; Detailed Implementation

[0056] according to Figures 1 to 4 The rolling mill stand 1 has work rolls 2 and support rolls 3. Within the scope of this invention, this represents the minimum configuration of the rolling mill stand 1. Furthermore, the rolling mill stand 1 can also have intermediate rolls. In this case, the intermediate rolls would be arranged between the work rolls 2 and the support rolls 3. Figure 4 As shown, the working roll 2 has a bearing journal 4, and the working roll 2 is mounted in the working roll insert 5 via the bearing journal. In a similar manner, the support roll 3 has a bearing journal 6, and the support roll 3 is mounted in the support roll insert 7 via the bearing journal.

[0057] During the rolling of the workpiece 8, a rolling force F is applied to the support roll insert 7 and thus also to the support roll 3. The rolling force F is transmitted to the work roll 2 via the support roll 3. This is well known to those skilled in the art. The workpiece 8 itself is made of metal, such as steel or aluminum. It is a flat workpiece, such as strip or plate. The workpiece 8 has a workpiece head 9. The workpiece head 9 is the area where the workpiece 8 is first rolled in the rolling mill stand 1. Accordingly, the transport direction of the workpiece 8 is... Figures 1 to 3 In this context, x represents the value.

[0058] The rolling mill stand 1 also has a bending system 10. The bending system 10 typically includes at least two hydraulic cylinder units 11, 12, which act on the drive side and operator side of the work roll insert 5 to press the work roll insert 5 open. The bending system 10 is used to adjust the shape, profile, and flatness of the rolled piece 8. In some cases, multiple hydraulic cylinder units 11, 12 act on the work roll insert 5. In this case, there are correspondingly more hydraulic cylinder units 11, 12.

[0059] according to Figure 5 The rolling mill stand 1 is controlled by a control structure. The control structure typically includes a control device 13 and a bending feedback controller 14 in any case.

[0060] Control device 13 is a higher-level control device acting as the L2 system, that is, it determines the setpoints within the range calculated by the lower-level feedback controller's rolling table. Figure 5 Only a single feedback controller, namely the bending feedback controller 14, is shown in this paper. Of course, other feedback controllers are possible in practical applications. However, only the bending feedback controller 14 is important within the scope of this invention. Therefore, only the bending feedback controller 14 is shown and will be described below.

[0061] Even before rolling the workpiece 8 in rolling stand 1, the rolling table calculation is performed on the workpiece 8 (see...). Figure 1 Within the scope of the rolling schedule calculation, the control device 13 determines the setpoint for adjusting the rolling mill stand 1, which can be the roll offset, etc. Specifically, within the scope of the rolling schedule calculation for rolling the workpiece 8 in the rolling mill stand 1, the control device 13 determines the basic setpoint FBB* for the bending force. The basic setpoint FBB* can be a single odd value that is constant over time. Alternatively, separate basic setpoint FBB* can be determined for different portions of the strip to be rolled. In this case, the basic setpoint FBB* varies over time.

[0062] The basic setting value FBB* is provided to the bending feedback controller 14 from time point t1 (see Figure 6Hereinafter, time point t1 will be referred to as the default time point t1. At the default time t1, the head 9 of the rolled piece has not yet reached the rolling mill stand 1 (see...). Figure 1 The basic setpoint FBB* is typically provided by the control unit 13. However, in principle, the basic setpoint FBB* can also be provided to the bending feedback controller 14 in some other way.

[0063] The actual value of the bending force FB is also provided to the bending feedback controller 14. The feasibility of detecting or determining the actual value FB is generally known to those skilled in the art. For example, in order to determine the bending force FB, the working pressures pP and pT in the working spaces of the hydraulic cylinder units 11 and 12 can be mathematically linked to each other in a manner that relates to the effective working area.

[0064] The bending feedback controller 14 controls the bending system 10. Specifically, the bending feedback controller 14 uses the obtained setpoint FB* and the actual value FB to determine the basic manipulated variable SB of the bending system 10. The basic manipulated variable SB is determined such that if the bending system 10 is controlled by the basic manipulated variable SB, the actual value FB is as close as possible to the synthetic setpoint FB*. The synthetic setpoint FB* is determined by the bending feedback controller 14 using at least the basic setpoint FB*. The synthetic setpoint FB* can be temporarily the same as the basic setpoint FB*. However, at least temporarily, other variables are also included in the synthetic setpoint FB*. This will become apparent. The bending feedback controller 14 uses the basic manipulated variable SB to determine the synthetic manipulated variable SR. The synthetic manipulated variable SR can be temporarily the same as the basic manipulated variable SB. During normal operation, i.e., during the stable rolling of the flat roll 8, the bending feedback controller 14 outputs the synthetic manipulated variable SR to the bending system 10, thereby controlling the bending system 10.

[0065] The opening states of hydraulic valves 15 and 16 are determined by the bending feedback controller 14 as the basic manipulated variable SB and the synthetic manipulated variable SR. The working spaces of hydraulic cylinder units 11 and 12 are subjected to high working pressure pP (pump pressure) and low working pressure pT (tank pressure). Hydraulic valves 15 and 16 are typically continuously adjustable valves, i.e., proportional valves or servo valves.

[0066] Due to the specification of the basic setpoint FBB*, the bending feedback controller 14 first determines a relatively large basic manipulated variable SB from the default time t1, which can even be the maximum feasible value MAX of the basic manipulated variable SB (and the synthetic manipulated variable SR). However, once the actual value FB of the bending force is as close as possible to the basic setpoint FBB*, it reduces the basic manipulated variable SB back to 0 or almost zero. Furthermore, it should be noted in this regard that, within the scope of this invention, a positive value of the basic manipulated variable SB corresponds to an increase in the bending force (reaching the technically maximum feasible value), and a negative value corresponds to a decrease in the bending force.

[0067] At time t2, the head 9 of the rolled piece reaches the rolling mill stand 1 (see...). Figure 2 The time point t2 will be referred to below as the actual entry time point t2. For example, the actual entry time period t2 can be easily detected by identifying a significant increase in the rolling force F or rolling torque driving the work roll 2. Upon entry, the bending force FB decreases significantly. A decrease of 50% or more is quite possible. Within a relatively short time, the bending feedback controller 14 opens the hydraulic valves 15 and 16 by specifying the corresponding basic manipulated variable SB, thereby setting the bending force back to its composite setpoint FB*. The time required to recover the bending force is typically much less than 1 second, for example, about 500 ms.

[0068] Rolling of workpiece 8 is carried out after the actual entry time point t2 (see...). Figure 3 However, immediately following the entry time point t2, the rolling mill stand 1 enters a relatively unstable state, which is then corrected by various feedback controllers (including the bending feedback controller 14) assigned to the rolling mill stand 1. A stable state is reached again at the stabilization time point t3. The time interval between the stabilization time point t3 and the entry time point t2 is determined by the design and dimensions of the rolling mill stand. Typically, this time interval is in the range of 1 second or less, for example, 500 ms or less.

[0069] Starting from the stabilization time point t3, the correction value δFB* is determined by evaluation unit 17. The correction value δFB* is applied to the basic setpoint FBB*. Starting from the stabilization time point t3, the composite setpoint FB* is the sum of the basic setpoint FBB* and the correction value δFB*. The correction value δFB* is determined in evaluation unit 17 based on the (actual) rolling force F. Evaluation unit 17 thus achieves the so-called DPC (=“bending AGC”).

[0070] If needed, additional correction variables can be provided to the bending feedback controller 14 from the steady-state time point t3, for example, from flatness feedback control or profile feedback control. Correction based on thermal influencing factors is also feasible. However, at least compensation for the effects caused by rolling force is provided.

[0071] At time t4, the rolling foot 18 of rolling piece 8 (see...) Figures 1 to 3 The actual entry time t4 is similar to the actual entry time t2, and the actual exit time t4 can also be easily detected, particularly by identifying a significant decrease in the rolling force F or rolling torque driving the work roll 2. Time t4 is hereinafter referred to as the exit time point. Typically, shortly before the exit time point t4, the application of the correction value δFB* to the basic setpoint FBB* is frozen, i.e., the last determined correction value δFB* is retained. However, this is secondary within the scope of this invention.

[0072] The core of the aforementioned prior art process is retained, but modifications and additions have been made according to the present invention. The following is in conjunction with... Figure 7 and Figure 8 A more detailed explanation of feasible modifications and additions, combined with Figure 9 and Figure 10 A more detailed explanation of the possible modifications and additions.

[0073] As a basis Figure 7 and Figure 8 As part of the embodiment, in addition to the basic setting value FBB*, an additional setting value FBZ* is provided to the bending feedback controller 14 during the entry time period. The additional setting value FBZ* can be fed to the bending feedback controller 14 by the control device 13. However, this additional setting value can also be specified in some other way, for example by an operator (not shown).

[0074] The entry time period begins at start time t5 and ends at end time t6. Start time t5 is earlier than the actual entry time t2. End time t6 is later than the actual entry time t2. This end time is usually before the stabilization time t3. This end time can also coincide with the stabilization time t3. However, end time t6 should generally not be after the stabilization time t3. This is because from the stabilization time t3 onwards, the significance and purpose of feedback control of rolling mill stand 1 is no longer to ensure a stable start-up of the rolling process. Instead, the significance and purpose of feedback control of rolling mill stand 1 is now to roll the workpiece 8 to its target characteristics, particularly its target thickness and its target shape or its target profile. The provision for additional setpoints FBZ* beyond the stabilization time t3 is disadvantageous in this regard.

[0075] An additional setting value FBZ* is applied to the basic setting value FBB*. The additional setting value FBZ* is provided to the bending feedback controller 14, causing the bending feedback controller 14 to determine the sum of the basic setting value FBB* and the additional setting value FBZ* as the composite setting value FB*. Therefore, the basic manipulated variable SB is determined such that the actual value of the bending force FB is as close as possible to this sum. Due to the modified setting value (FBB* + FBZ* instead of FBB*), the actual value of the bending force FB immediately preceding the entry time point t2 is greater than the basic setting value FBB*.

[0076] According to Figure 9 and Figure 10Within the scope of the design scheme, an additional manipulated variable SZ is applied to the basic manipulated variable SB during the entry time period. Thus, the sum of the basic manipulated variable SB and the additional manipulated variable SZ is provided to hydraulic valves 15 and 16 as a composite manipulated variable SR. Therefore, the composite manipulated variable SR is greater than the basic manipulated variable SB immediately preceding the actual entry time point t2. The additional manipulated variable SZ can be provided to the bending feedback controller 14 by the control device 13. However, it can also be specified in some other way, for example, by an operator (not shown).

[0077] According to Figure 9 In the design scheme, the basic manipulated variable SB and the additional manipulated variable SZ are added on the output side of the bending feedback controller 14.

[0078] Typically, it is adopted according to Figure 7 and Figure 8 The process or based on Figure 9 and Figure 10 The process described above is sufficient. However, in principle, these two processes can also be combined. For example, the additional manipulated variable SZ can be primarily applied to increase the actual value of the bending force FB. In this case, the additional setpoint FBZ* can be updated accordingly simultaneously so that the bending feedback controller 14 does not counteract the increase in bending force caused by the deviation between the actual value of the bending force FB and the basic setpoint FBB*. However, even without updating the additional setpoint FBZ*, the synthesized manipulated variable SR can be guaranteed to be positive. All that is needed for this is to select a sufficiently large additional manipulated variable SZ.

[0079] Various advantageous designs of the present invention can also be particularly derived from Figure 8 and Figure 10 It can be seen, and in some cases, it can also be seen from Figure 7 and Figure 9 As can be seen, these design solutions are not essential for realizing the basic principles of this invention, but they provide additional advantages. These design solutions will be explained individually in more detail below. They can be implemented independently of each other, but can also be combined as needed. Furthermore, they are all combined below without exception. Figure 8 and some Figure 7 This explains the design scheme, specifically the case where an additional setting value FBZ* is specified. However, if an additional manipulation variable SZ or a minimum manipulation variable SM is specified, a favorable design scheme can be achieved in a completely similar manner.

[0080] A feasible design involves specifying an additional setpoint FBZ* starting from a start time point t5. Specifically, the additional setpoint FBZ* preferably increases strictly monotonically from the start time point t5 with a finite slope from 0 to a maximum value FBZ0*. This increase can occur within a period of, particularly, a few hundred milliseconds. The increase should be completed before the actual start time point t2. Appropriate steps for this gradual increase are well known to those skilled in the art.

[0081] Another feasible design involves reducing the additional setpoint FBZ* after the actual entry time point t2. Specifically, the additional setpoint FBZ* decreases from its maximum value FBZ0* to 0, preferably in a strictly monotonic manner and with a finite slope. In particular, the time period during which this reduction occurs can also be in the range of several hundred milliseconds. The corresponding steps of gradual reduction are well known to those skilled in the art. However, the value must reach 0 no later than the steady-state time point t3.

[0082] Another feasible design involves defining the starting time point t5. Specifically, the expected entry time point t7 can be determined as part of the path tracking of the roll head 9 (the implementation of path tracking is generally known to those skilled in the art). Therefore, the starting time point t5 can be easily determined such that it is preceded by a predetermined time period T1 by the expected entry time point t7.

[0083] The actual entry time t2 can be before or after the expected entry time t7. However, the time deviation is at most as large as the previously known error tolerance δt. Therefore, the actual entry time t2 lies within the interval [t7-δt; t7+δt].

[0084] The predetermined advance time period T1 can be measured in such a way that the additional setpoint FBZ* has clearly reached its maximum value FBZ0* at the actual entry time t2. Specifically, this design ensures that the actual value of the bending force FB has been adjusted as close as possible to the sum of the basic setpoint FBB* and the additional setpoint FBZ*. Alternatively, the predetermined advance time period t1 can also be measured in such a way that the additional setpoint FBZ* has certainly not yet reached its maximum value FBZ0* at the actual entry time t2. This design particularly ensures that the synthetic manipulated variable SR has a positive value at the actual entry time t2. The predetermined time period T1 is typically in the range of 0.5s to 2.0s, particularly between 0.8s and 1.5s, for example, approximately 1.0s.

[0085] The specific method for determining the advance time period T1 can also be combined with a specific method for determining the additional setpoint FBZ* (or its maximum value FBZ0*). Specifically, the advance time period T1 can be determined in such a way that at the actual entry time t2, "the bending force FB has been adjusted as close as possible to the sum of the basic setpoint FBB* and the additional setpoint FBZ*." Simultaneously, the additional setpoint FBZ* (or its maximum value FBZ0*) can be determined such that the actual value of the bending force FB does not reach the sum of the basic setpoint FBB* and the additional setpoint FBZ* at all. (Therefore, the above wording is in quotation marks). The result of this step is that the synthetic manipulated variable SR is forced to become positive (usually even reaching its maximum value MAX) and remain at that value because the actual desired result (FB = FBB* + FBZ*) cannot be achieved.

[0086] Another feasible design involves defining the end time t6 while ensuring that the end time t6 is no later than the stabilization time t3. This is because, as already mentioned, the actual entry time t2 can be recorded effortlessly, or it can be determined based on the recorded measurement variables. Therefore, the end time t6 can be determined without problems, such that it is later than the actual entry time t2 by a predetermined lag time T2.

[0087] Preferably, the predetermined lag time period T2 is determined in such a manner that the additional setting value FBZ* remains at its maximum value FBZ0* until a time point at which the distance from the actual entry time point t2 has a predetermined value. Specifically, this value can be in the range of 0.1s and 1.0s. For example, it can be between 0.2s and 0.6s. A value between 0.3s and 0.4s is particularly preferred. After the latter time point, the additional setting value FBZ* may suddenly, preferably gradually, decrease from its maximum value FBZ0* to 0. Reaching the value 0 corresponds to the end time point t6. Since the time period during which the additional setting value FBZ* decreases is also known, the end time point t6 can be determined effortlessly based on the actual entry time point t2.

[0088] Alternatively, the predetermined lag time period T2 can be determined based on the expected entry time t7. In this case, the determination is based on the expected entry time t7, not the actual entry time t2.

[0089] Another feasible design involves determining, for example, an additional setpoint FBZ* (or its maximum value FBZ0*) via control device 13. Specifically, the characteristics of the workpiece 8 can be utilized. These characteristics are, on the one hand, actual or expected variables of the workpiece 8 that it possesses or is assumed to possess before rolling in the rolling mill 1. Examples of these variables are width, thickness, temperature, and chemical composition, and can also be the pretreatment of the workpiece 8. On the other hand, these characteristics are target variables that the workpiece 8 should possess after rolling in the rolling mill 1. Examples of these variables are the width and thickness of the workpiece 8. Furthermore, the mechanical properties of the rolling mill 1 are known, such as the elastic modulus of the mill, the diameter of the work roll 2, the diameter of the support roll 3, etc. Finally, the expected values ​​of the operating variables of the rolling mill 1 used for rolling the workpiece 8, particularly the expected value FE of the rolling force F, are determined, for example, via control device 13, as part of the rolling schedule calculation. The additional setting value FBZ* or its maximum value FBZ0* is preferably determined based on the characteristics of the workpiece 8 and / or the expected value FE of the rolling force F. If necessary, the mechanical characteristics of the rolling mill stand 1 can also be taken into account. Specific determinations can be made, for example, using formulas or tables. These formulas or tables can be stored, for example, in the control device 13.

[0090] Another feasible design involves determining the additional setpoint FBZ* or its maximum value FBZ0*. Specifically, the additional setpoint FBZ* can be determined such that the synthesized manipulated variable SR exhibits its maximum feasible value immediately preceding the actual entry time t2. The determination of the additional setpoint FBZ* causes hydraulic valves 15 and 16 to fully open at the actual entry time t2, and thus the entire operating pressure pP of the hydraulic system (including the accumulator) is stably introduced. This step is particularly applicable to the front stands of plate mills and multi-stand finishing mills (in the case of metal strip). However, in principle, this step can also be applied to the rear stands of multi-stand finishing mills.

[0091] The final feasible design also involves determining the additional setpoint FBZ* or its maximum value FBZ0*. In particular, the additional setpoint FBZ* can be determined in such a way that the actual value of the bending force FB at the actual entry time t2 decreases, which will compensate for at least 50% if the additional setpoint FBZ* is not provided to the bending feedback controller 14.

[0092] In many cases, it is sufficient if hydraulic valves 15 and 16 are not fully opened but only slightly opened. This design approach is particularly useful in such situations, where a minimum manipulated variable SM is specified, and the minimum manipulated variable SM has a relatively low value, such as between 8% and 20% of the maximum feasible modulation of hydraulic valves 15 and 16. However, specifying a larger minimum manipulated variable SM should not be excluded in other cases.

[0093] This invention offers numerous advantages. In particular, the entry process is significantly stabilized. Furthermore, the time elapsed from entry time t2 to the actual value of the bending force FB reaching the basic set value FBB* again is shortened. Finally, threading and roll forming are also stabilized.

[0094] Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the disclosed examples, and those skilled in the art can derive other variations therefrom without departing from the scope of protection of the present invention.

[0095] Reference number list

[0096] 1 Rolling mill stand

[0097] 2. Working rolls

[0098] 3. Support rolls

[0099] 4, 6 bearing journals

[0100] 5. Working roll embedding section

[0101] 7. Support roll embedding part

[0102] 8 Rolled parts

[0103] 9. Head of rolled piece

[0104] 10 Bending System

[0105] Hydraulic cylinder units 11 and 12

[0106] 13 Control device

[0107] 14 Bending Feedback Controller

[0108] Hydraulic valves 15 and 16

[0109] 17 Evaluation Units

[0110] 18 Rolled part foot

[0111] 19 Select Components

[0112] F Rolling force

[0113] FE Expected Value

[0114] FB* Synthesis Settings

[0115] FBB* Basic Settings

[0116] FBZ* Additional Settings

[0117] FBZ0* Maximum value

[0118] Actual value of FB bending force

[0119] MAX (Maximum Feasible Value)

[0120] pP, pT working pressure

[0121] SB Basic Manipulated Variables

[0122] Minimal Manipulation Variable in SM

[0123] SR synthetic manipulation variable

[0124] SZ Additional Manipulated Variables

[0125] Time points from t1 to t7

[0126] Time periods T1 and T2

[0127] X transmission direction

[0128] δFB* correction value

[0129] δt is the error tolerance.

Claims

1. A method of operating a rolling mill stand (1) for rolling a flat workpiece (8) made of metal, the workpiece having a head (9), -in, The rolling mill stand (1) has at least a work roll (2) and a support roll (3). -The working roll (2) is installed in the working roll embedding part (5), and the bending system (10) that presses open the working roll embedding part (5) acts on the working roll embedding part (5). - Wherein, the head of the rolled piece (9) arrives at the rolling mill stand (1) at the actual entry time (t2), - In this process, a basic setpoint (FBB*) is provided to a bending feedback controller (14), and the bending feedback controller (14) determines a synthetic setpoint (FB*) taking into account the basic setpoint (FBB*). -In this context, the bending feedback controller (14) is also provided with the actual value of the bending force (FB). - Wherein, the bending feedback controller (14) determines the basic manipulated variable (SB) of the bending system (10) based on the synthesized setpoint (FB*) and the actual value (FB), such that when the bending system (10) is controlled using the basic manipulated variable (SB), the actual value (FB) is as close as possible to the synthesized setpoint (FB*). - Wherein, the bending feedback controller (14) determines the composite setpoint (FB*) from the stabilization time point (t3) after the entry time point (t2), taking into account the actual rolling force (F) that occurs during the rolling of the flattened workpiece (8). Its features are, During the entry period that begins before the actual entry time (t2) and ends after the actual entry time (t2), - In addition to the basic setpoint (FBB*), an additional setpoint (FBZ*) is provided to the bending feedback controller (14) such that the bending feedback controller (14) determines the composite setpoint (FB*) during the entry time period, taking into account not only the basic setpoint (FBB*) but also the additional setpoint (FBZ*), and thereby immediately prior to the actual entry time point (t2), the actual value of the bending force (FB) is greater than the basic setpoint (FBB*), and / or - A synthetic manipulated variable (SR) is determined by applying an additional manipulated variable (SZ) to the basic manipulated variable (SB), the synthetic manipulated variable being provided to the bending system (10), and the bending system (10) being controlled such that the synthetic manipulated variable (SR) is greater than the basic manipulated variable (SB) and / or - The basic manipulation variable (SB) and the minimum manipulation variable (SM) are provided to the selection element (19), and the selection element (19) provides the bending system (10) with the maximum value of the basic manipulation variable (SB) and the minimum manipulation variable (SM).

2. The operating method according to claim 1, characterized in that, The additional setpoint (FBZ*) and / or the additional manipulated variable (SZ) and / or the minimum manipulated variable (SM) increase strictly monotonically from 0 to the maximum value (FBZ0*) with a finite slope starting from the beginning of the entry time period (t5) and / or decrease strictly monotonically from the maximum value (FBZ0*) to zero with a finite slope at the end of the entry time period (t6).

3. The operating method according to claim 1 or 2, characterized in that, The expected entry time (t7) is determined by path tracking of the rolled piece (8), and the start point (t5) of the entry time period is a predetermined advance time period (T1) earlier than the expected entry time (t7).

4. The operating method according to claim 1 or 2, characterized in that, The end of the entry time period (t6) is later than the actual entry time (t2) by a predetermined lag time period (T2).

5. The operating method according to claim 1 or 2, characterized in that, Before rolling the workpiece (8) in the rolling mill (1), the maximum value of the additional setpoint (FBZ*), the additional manipulation variable (SZ), and the minimum manipulation variable (SM) are determined based on the characteristics of the workpiece (8) and / or based on the expected rolling force (FE).

6. The operating method according to claim 1 or 2, characterized in that, The maximum values ​​of the additional setpoint (FBZ*), and / or the additional manipulated variable (SZ), and / or the minimum manipulated variable (SM) are determined such that the synthetic manipulated variable (SR) presents the maximum feasible value (MAX) of the synthetic manipulated variable at the actual entry time point (t2).

7. The operating method according to claim 1 or 2, characterized in that, The additional setpoint (FBZ*) and / or the additional manipulated variable (SZ) and / or the minimum manipulated variable (SM) are determined such that the decrease in the actual value (FB) of the bending force at the actual entry time point (t2) is compensated by at least 50%, wherein the actual entry time point is adjusted without the additional setpoint (FBZ*) and / or the additional manipulated variable (SZ) and / or the minimum manipulated variable (SM).

8. A rolling unit for rolling a flat workpiece (8) made of metal, said workpiece having a head (9), -in, The rolling unit has a rolling mill stand (1) and a bending feedback controller (14). -The rolling mill stand (1) has at least a work roll (2) and a support roll (3) installed in the work roll embedding part (5). -The rolling mill stand (1) has a bending system (10) that presses open the work roll insert (5). - wherein the bending feedback controller (14) actuates the bending system (10), characterized in that, The rolling mill stand (1) and the bending feedback controller (14) interact with each other during the operation of the rolling unit, such that the rolling mill stand and the bending feedback controller perform the operating method according to any one of the preceding claims.

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