Cooling device control device

Abstract

Performs precalculation, cooling history management, feedforward calculation, and feedback calculation. In precalculation, multiple cooling beds are set as feedforward beds or feedback beds. Precalculation also calculates the water injection rates for each of these beds. In cooling history management, a recalculation position is set for re-implementing the feedback calculation. In feedback calculation, when a segment reaches the recalculation position, a temperature correction value is calculated to compensate for the delay in the transport time from the feedback bed to the outlet thermometer and the response delay of the feedback bed. In feedback calculation, the water injection rates for each feedback bed calculated in precalculation are also modified for each segment based on the outlet temperature target value, the actual outlet temperature value calculated for each segment, the recalculated outlet temperature prediction value, and the temperature correction value.

Description

Technical Field

[0001] The present invention relates to an apparatus for controlling a cooling device for cooling a rolled material in a rolling line. Background Art

[0002] Hot rolling quality control involves both product dimensional control and rolled material temperature control. Examples of dimensional control include plate thickness control, plate width control, and flatness control. Examples of temperature control include finishing mill outlet temperature control and coiling temperature control. Finishing mill outlet temperature control controls the temperature of the rolled material at the outlet of the finishing mill. Coiling temperature control controls the temperature of the rolled material at the entry of the coiler.

[0003] Coil temperature control is typically performed using multiple cooling beds installed in the rolling line. These cooling beds collectively constitute a cooling system. Coil temperature control involves, for example, precalculation, feedforward control, and feedback control. For convenience, feedforward will be referred to as "FF" and feedback as "FB."

[0004] A precalculation is performed before cooling begins. In the precalculation, for example, a control target (target temperature) is assigned, and the amount of water injected into each of the plurality of cooling beds is determined so that the temperature of the rolled material after being cooled by the cooling equipment becomes the target temperature. FF control is performed by measuring the temperature of the rolled material (hereinafter also referred to as "strip") to be cooled after the cooling action of the cooling equipment begins. In FF control, for example, the amount of water injected during the precalculation is changed based on the measured actual value. FB control is performed by measuring the temperature of the strip at the outlet side of the cooling equipment. In FB control, for example, the amount of water injected during the precalculation is changed based on the measured actual temperature value.

[0005] Patent Document 1 discloses a first embodiment in which multiple cooling beds are divided into water-cooled beds with water injection and air-cooled beds without water injection. The "cooling length," representing the total length of the water-cooled beds in the conveying direction of the strip, is varied for each section. In this first embodiment, the "cooling length" is varied to compensate for temperature fluctuations caused by the discrepancy between the strip speed predicted during precalculation and the actual speed. A section is defined as a section where the strip is divided into virtual lengths in the conveying direction.

[0006] In the first embodiment, FB control is also performed in some water cooling beds. This FB control varies the water injection rate in the water cooling beds performing FB control based on the temperature difference between the actual temperature of the rolled material after cooling by the cooling equipment and the target temperature. The first embodiment also includes a function to compensate for the time lost in transporting the strip from the water cooling bed performing FB control to the outlet of the cooling equipment.

[0007] Patent document 1 also discloses the following second embodiment: a portion of the water-cooled bed is allocated as a "cooling bed for FF control" (hereinafter also referred to as "FF bed"), and FF control is performed on the water injection amount in the FF bed according to each section. In this second embodiment, the above-mentioned temperature difference is calculated at a distance upstream from a position equivalent to the wasted time of the response delay of the FF bed. In FF control, the water injection amount in the FF bed is changed based on the temperature difference. In addition, in the second embodiment, the description of the configuration common to the configuration of the first embodiment is omitted. Therefore, in the second embodiment, it is also possible to consider performing FB control in a portion of the water-cooled bed. In the second embodiment, the water-cooled bed that performs FB control can be said to correspond to the "cooling bed for FB control" (hereinafter also referred to as "FB bed").

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-34122 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] In the second embodiment of patent document 1, the position of the FF bed is uncertain. In addition, in this second embodiment, it is unclear whether all the water-cooling beds other than the FB bed are FF beds, or whether part of the water-cooling beds other than the FB bed are FF beds. Therefore, first, the case where all the water-cooling beds other than the FB bed are FF beds is studied. Consider the case where the FF bed is located on the upstream side of the rolling line. In this case, it can be expected that the temperature difference is small. Therefore, the advantage of deliberately changing the water injection amount during the pre-calculation at this position is small. Therefore, the case where the FF bed is located on the downstream side of the rolling line is considered next. However, in this case, from the perspective of maintaining the cooling pattern (cooling rule) in the cooling equipment, there are the following problems.

[0013] The cooling mode has a significant impact on the material of the strip after being cooled by the cooling equipment, and is therefore an important factor in the cooling of the strip. Examples of cooling modes include front-stage cooling and back-stage cooling. In front-stage cooling, the amount of water injected into the cooling bed on the upstream side of the rolling line is relatively large, and the amount of water injected into the cooling bed decreases as the strip moves toward the downstream side of the rolling line. On the contrary, in back-stage cooling, the amount of water injected into the cooling bed on the downstream side of the rolling line is relatively large, and the amount of water injected into the cooling bed decreases as the strip moves toward the upstream side of the rolling line. In front-stage cooling, the high-temperature strip is rapidly cooled. Therefore, although it also depends on the chemical composition of the rolled material, front-stage cooling may sometimes result in a material with higher strength but difficult to process. In back-stage cooling, the strip is water-cooled after its temperature drops. Therefore, back-stage cooling results in a material with toughness that is not too high in strength but easy to process.

[0014] In the second embodiment of patent document 1, there is a description of performing front-stage cooling. However, in the case of performing front-stage cooling, when FF control is performed on the FF bed located on the downstream side of the rolling line, the cooling mode will collapse due to the increase in the amount of water injected into the FF bed. This problem exists not only in the case where all water-cooling beds other than the FB bed are FF beds, but also in the case where part of the water-cooling beds other than the FB bed are FF beds. In the latter case, the problem becomes significant. The reason is that, in the latter case, water is injected separately from the FF bed, the FB bed and other water-cooling beds. In this way, in order to make the material of the plate and strip after being cooled by the cooling equipment become the desired material, the cooling mode is required not to collapse. Therefore, it can be said that the change of the amount of water injected into the FF bed is limited. Therefore, it is desired to have an improvement for controlling the actual temperature of the plate and strip at the outlet side of the cooling equipment to the target temperature while maintaining the cooling mode in the FF bed.

[0015] An object of the present invention is to provide a technique capable of controlling the actual temperature of the strip at the outlet side of the cooling device to a target temperature while maintaining the cooling mode in the FF bed.

[0016] Means for solving problems

[0017] The present invention is a control device for a cooling device installed in a rolling line and cooling a rolled material using a plurality of cooling beds. The control device has the following features.

[0018] The control device is configured to control the water injection amounts in the plurality of cooling beds so that an outlet temperature target value indicating the target temperature of the rolled material at the position of an outlet thermometer provided on the outlet side of the cooling device is consistent with an outlet temperature actual value indicating the actual temperature of the rolled material measured by the outlet thermometer.

[0019] The control device performs precalculation, cooling history management, feedforward calculation, and feedback calculation in controlling the water injection amounts in the plurality of cooling beds.

[0020] In the above-mentioned pre-calculation, the above-mentioned control device

[0021] The plurality of cooling beds are configured as feedforward beds for performing feedforward control of the water injection amount or feedback beds for performing feedback control of the water injection amount. The feedback bed is at least one cooling bed sequentially allocated from the downstream side of the rolling line according to the rolled material, and the feedforward beds are the remaining cooling beds.

[0022] The control device further performs the above-mentioned pre-calculation,

[0023] calculating an outlet temperature prediction value indicating the predicted temperature of the rolled material at the position of the outlet thermometer,

[0024] The water injection amounts in the plurality of cooling beds are calculated so that the outlet temperature prediction value is consistent with the outlet temperature target value.

[0025] In the cooling history management, the control device

[0026] The position of the rolled material is grasped by a section, which represents an interval when the rolled material is divided into an imaginary length in the conveying direction.

[0027] Cooling histories are stored for each section, the cooling histories including actual speeds of the rolled material at respective positions of the plurality of cooling beds and histories of respective water injection amounts in the plurality of cooling beds.

[0028] In the above feedforward calculation, the above control device

[0029] The predicted exit temperature value is calculated for each section based on an actual entry temperature value indicating the actual temperature of the rolled material at the position of an entry thermometer installed on the entry side of the cooling device and the speed of the rolled material at the position of the entry thermometer.

[0030] Based on the difference between the outlet temperature target value and the outlet temperature prediction value calculated for each section, each water injection amount in the feedforward bed calculated in the precalculation is changed.

[0031] The control device calculates, in the feedback calculation, a difference between an actual outlet temperature value indicating an actual temperature of the rolled material at a position of the outlet thermometer and the target outlet temperature value for each section.

[0032] The control device further sets a recalculation position for re-implementing the feedback calculation in the cooling history management. The recalculation position is located upstream of the feedback bed on the pass line by a distance corresponding to a response delay of the feedback bed.

[0033] Furthermore, when the segment reaches the recalculation position, the control device recalculates the predicted exit temperature value for the segment that has reached the recalculation position based on the cooling history.

[0034] The control device further performs the feedback calculation.

[0035] When the segment reaches the recalculated position, a temperature correction value is calculated to compensate for a delay in the transport time from the position of the feedback bed to the position of the outlet thermometer and a response delay of the feedback bed.

[0036] Based on the outlet temperature target value, the outlet temperature actual value calculated for each section, the recalculated outlet temperature prediction value, and the temperature correction value, the water injection amounts in the feedback bed calculated in the precalculation are changed for each section.

[0037] The above-mentioned control device may further have the following features.

[0038] The control device further calculates the predicted speed of the rolled material.

[0039] The control device mentioned above, in the above recalculation,

[0040] Based on the cooling history from the position of the entry thermometer to the recalculated position, an actual temperature drop value of the rolled material conveyed from the position of the entry thermometer to the recalculated position is calculated for each section;

[0041] Based on the predicted speed and the water injection amounts in the plurality of cooling beds obtained by the pre-calculation, a predicted temperature drop value of the rolled material from the recalculated position to the position of the outlet thermometer is calculated for each section.

[0042] The outlet temperature prediction value is calculated based on the actual temperature drop value and the predicted temperature drop value.

[0043] The above-mentioned control device may further have the following features.

[0044] A prescribed cooling pattern is applied to each water injection rate in the feedforward bed.

[0045] The control device changes each water injection amount in the feedforward bed within the range of the predetermined cooling pattern during the feedforward calculation.

[0046] The above-mentioned control device may further have the following features.

[0047] A prescribed cooling pattern is applied to each water injection rate in the feedforward bed.

[0048] The control device further comprises:

[0049] According to the feedback bed, it is determined whether the water injection amount in the feedback bed is close to the maximum water injection amount or the minimum water injection amount.

[0050] When it is determined that the water injection rate in the feedback bed has approached the maximum water injection rate or the minimum water injection rate, the water injection or stop of the water injection in the feedback bed is switched to the feedforward bed within the range of the predetermined cooling mode.

[0051] Effects of the Invention

[0052] According to the present invention, in the cooling history management, a recalculation position for re-implementing the feedback calculation is set. The recalculation position is located at a position on the upstream side of the rolling line relative to the position of the feedback bed at a distance equivalent to the response delay of the feedback bed. In addition, according to the present invention, the next feedback calculation using the recalculation position is performed. That is, when the section reaches the recalculation position, a temperature correction value is calculated to compensate for the delay in the conveying time from the position of the feedback bed to the position of the outlet thermometer and the response delay of the feedback bed. Then, based on the outlet temperature target value, the outlet temperature actual value calculated according to the section, the recalculated outlet temperature prediction value, and the temperature correction value, each water injection amount in the feedback bed calculated in the pre-calculation is changed according to the section.

[0053] By incorporating the recalculated predicted outlet temperature value into each change in water injection rate, stable temperature control can be achieved for various rolling speeds. Furthermore, by incorporating a temperature correction value into each change in water injection rate, delays in conveying time and feedback bed response can be compensated for. This also improves the stability of temperature control for various rolling speeds. Consequently, the actual temperature of the cooling equipment's outlet section can be controlled to the target temperature.

[0054] Furthermore, according to the present invention, the feedforward beds are allocated sequentially from the outlet side of the cooling device. This allows the cooling pattern in the feedforward beds to be maintained. Consequently, the actual temperature of the cooling device outlet zone can be controlled to the target temperature while maintaining the cooling pattern in the feedforward beds. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a diagram showing a configuration example of a rolling line to which the control device according to the first embodiment of the present invention is applied.

[0056] Figure 2 It is a diagram showing an example of the functional configuration of the control device according to the first embodiment.

[0057] Figure 3 is a diagram illustrating recalculation of positions.

[0058] Figure 4 This is a control block diagram related to FB control performed by the control device.

[0059] Figure 5 This is a diagram showing an example of control timing of temperature control performed by the control device.

[0060] Figure 6 This is a flowchart showing an example of temperature control processing performed by the control device.

[0061] Figure 7 It is a diagram showing the functional configuration of a comparative example of the control device of the first embodiment.

[0062] Figure 8 This is a control block diagram related to FB control performed by a control device in a comparative example.

[0063] Figure 9 This is a diagram explaining the outline of control when the water injection rate in the FB bed is close to the maximum water injection rate.

[0064] Figure 10 This is a diagram explaining the outline of control when the water injection rate in the FB bed is close to the minimum water injection rate.

[0065] Figure 11 This is a flowchart showing an example of temperature control processing performed by the control device in the second embodiment.

[0066] Figure 12 This is a flowchart showing an example of temperature control processing performed by the control device in the second embodiment.

[0067] Figure 13 This is a flowchart showing an example of temperature control processing performed by the control device in the second embodiment. DETAILED DESCRIPTION

[0068] The following describes in detail a control device for a cooling device according to an embodiment of the present invention with reference to the accompanying drawings. Common elements are denoted by the same reference numerals in the various figures, and duplicate descriptions are omitted. The present invention is not limited to the following embodiments and can be implemented with various modifications without departing from the spirit of the present invention.

[0069] 1. First Implementation

[0070] First, refer to Figures 1 to 8A control device according to a first embodiment of the present invention will be described.

[0071] 1-1. Example of rolling line configuration

[0072] Figure 1 It is a diagram showing a configuration example of a rolling line to which the control device of the first embodiment is applied. Figure 1 The figure shows an example of the configuration of a rolling line around a run-out roller table (hereinafter also referred to as "ROT") 10. The ROT 10 is a device for conveying the rolled material (i.e., the strip M) after being rolled by the finishing mill 11 to a coiler 15. A cooling device 12 is provided in the ROT 10. The cooling device 12 includes N cooling beds arranged along the conveying direction of the strip M. Figure 1 The numbers #01 to #N shown are for distinguishing these cooling beds, and are assigned in order from the upstream side in the ROT 10. In addition, "upstream" and "downstream" in this application are based on the conveying direction of the strip M.

[0073] Each cooling bed is equipped with a plurality of valves for supplying cooling water from at least one of the upper and lower surfaces of the strip M. By changing the number of open valves in a cooling bed, the amount of water injected into the cooling bed is changed. The amount of water injected into each valve 1 of the subsequent cooling bed (e.g., cooling bed #02) can also be set to be less than the amount of water injected into each valve 1 of the preceding cooling bed (e.g., cooling bed #01). In this case, even if the number of open valves in the preceding and subsequent cooling beds is the same, the degree of cooling can be differentiated between the cooling beds. In addition, the valves of the cooling bed can be configured to change the amount of water injected by switching between an open state and a closed state, or to continuously change the amount of water injected by changing the opening degree.

[0074] Strip M on ROT10 Figure 1 The strip M is conveyed from the left side to the right side of the cooling device 12. While passing through the cooling device 12, the strip M is cooled to the desired temperature by cooling water supplied from at least one cooling bed. The actual temperature of the strip M is constantly measured by at least an inlet thermometer 13 and an outlet thermometer 14. The inlet thermometer 13 is located on the inlet side of the cooling device 12. The outlet thermometer 14 is located on the outlet side of the cooling device 12. After passing through the cooling device 12, the strip M is coiled by a coiler 15.

[0075] The entry-side thermometer 13 is located on the exit side of the finishing mill 11 and is also referred to as the finishing mill exit-side thermometer. The exit-side thermometer 14 is located on the entry side of the coiler 15 and is also referred to as the coiling thermometer. For convenience, the position of the entry-side thermometer 13 will be referred to as the "FDT (Finisher Delivery Thermometer) position." The position of the exit-side thermometer 14 will be referred to as the "CT (Coiling Thermometer) position."

[0076] 1-2. Example of control device configuration

[0077] The control device of the first embodiment typically comprises a computer having at least one processor, at least one memory, and an input / output interface. The control device is connected to a host computer that determines various rolling-related factors, such as product thickness. Some of the functions of the host computer may also be incorporated into the control device.

[0078] Figure 2 FIG. 1 is a diagram showing an example of the functional configuration of the control device according to the first embodiment. Figure 2 As shown, the control device 20 includes a pre-calculation unit 21, a cooling history management unit 22 (cooling history, i.e., cooling history), a feedforward calculation unit (FF calculation unit) 23, a recalculation unit 24, and a feedback calculation unit (FB calculation unit) 25. These functions are implemented by the processor of the control device 20 executing a predetermined program stored in a memory.

[0079] Before starting the cooling of the strip M, the pre-calculation unit 21 determines the initial water injection amount of the cooling bed based on the operation instruction received from the host computer. The operation instruction includes the outlet temperature target value T of the strip M. CT AIM , cooling mode, etc. Outlet temperature target value T CT AIM is the target temperature of the strip M at the CT position. Examples of cooling modes include front-stage cooling and rear-stage cooling. These examples have already been described.

[0080] Because cooling begins at the leading end of the strip M, the pre-calculation unit 21 determines the initial settings for the cooling bed and the initial water injection rates before the strip M reaches the inlet-side thermometer 13. The timing for determining the initial water injection rates is determined by fully considering the "valve response delay," the time from valve opening until cooling water reaches the strip. This "valve response delay" is synonymous with the "cooling bed response delay" in this specification.

[0081] In the initial setting of the cooling bed, the cooling bed is set to an FF bed or an FB bed. In the first embodiment, the FF bed is set sequentially from the upstream side in ROT10 (upstream side of the rolling line), and the FB bed is set sequentially from the downstream side in ROT10 (downstream side of the rolling line). The cooling mode is applied to the FF bed. In order to prevent the cooling mode from collapsing, the total number of FB beds is set to about 1 to 2 according to each element of the product. Figure 2 In the example shown, cooling beds #N-1 and #N correspond to FB beds, and the remaining cooling beds (ie, cooling beds #01 to #N-2) correspond to FF beds.

[0082] In determining the initial water injection amount, first, the predicted temperature drop value dT of the strip M when it is transported from the FDT position to the CT position is calculated. The predicted temperature drop value dT is used to calculate the predicted temperature drop value T, which represents the predicted temperature of the strip M at the FDT position. FDT CAL In addition, based on the result of this calculation, the outlet temperature prediction value T representing the predicted temperature of the strip M at the CT position is calculated. CT CAL Then, the predicted value of the outlet temperature T CT CAL and the outlet temperature target value T CT AIM The initial water injection amount is determined in a consistent manner. When determining the initial water injection amount, a value that takes into account future changes (increases and decreases) in the water injection amount in the cooling bed is used.

[0083] Outlet temperature prediction value T CT CAL The calculation of is performed using, for example, equations (1) and (2).

[0084]

[0085]

[0086] The variables in equations (1) and (2) are as follows.

[0087] t(FDT): time of passing the FDT position [s]

[0088] t(CT): time of passing the CT position [s]

[0089] h: thickness of the strip M [m]

[0090] γ(T(t)): specific heat at temperature T [J / (kg·degC)]

[0091] T(t): Temperature of the strip M at time t [degC]

[0092] ρ: density [kg / m3]

[0093] q(v pre (t),T(t),δ pre (t),……): heat flux [W / m 2 ]

[0094] v pre (t): predicted speed of strip M [m / s]

[0095] δ pre(t): The type of cooling determined (water cooling by water injection or air cooling) [-]

[0096] The predicted speed of the strip M is calculated based on the actual speed value of the strip M on the upstream side of the cooling equipment 12, the operating conditions of the hot rolling line, and the like, and is repeatedly corrected as necessary.

[0097] The cooling history management unit 22 manages the position and cooling history of the strip M based on the segments S. A segment S represents an interval when the strip M is divided into imaginary lengths in the conveying direction. The position of each segment S passing through the cooling equipment 12 is managed (mastered) based on the speed of the strip M at the exit of the rolling mill (e.g., the finishing mill 11). This speed can be calculated using the roller rotation speed of the rolling mill or directly measured. The cooling history of each segment S passing through the cooling equipment 12 includes the actual speed of the segment S at each position on the cooling bed and the history of each water injection amount in the cooling bed.

[0098] The cooling history management unit 22 also determines the recalculation position for the feedback calculation (FB calculation) for each segment S. The recalculation position is the position where each water injection amount in the FB bed is recalculated (i.e., the position where the FB calculation is re-implemented). Re-implementation of the FF calculation will be described later. Here, the recalculation position will be explained first.

[0099] Figure 3 is a diagram illustrating recalculation of positions. Figure 3 The recalculated position SP of the #N-1 cooling bed is shown. The recalculated position SP is located upstream of the #N-1 cooling bed in ROT10 (upstream of the rolling line) by a distance D2 corresponding to the wasted time. The wasted time corresponds to the valve response delay of the #N-1 cooling bed. Figure 3 1 and 2 show distance D1 next to distance D2. Distance D1 is the distance from the position of the #N-1 cooling bed to the CT position.

[0100] The FF calculation unit 23 calculates the outlet temperature prediction value T which indicates the predicted temperature at the CT position of the i-th (i is a natural number) segment Si when the segment Si passes through the FDT position. CT CAL (i) Outlet temperature prediction value T CT CAL The calculation of (i) is performed using, for example, equations (3) and (4).

[0101]

[0102]

[0103] The variables shown in formulas (3) and (4) are as follows.

[0104] T FDT ACT (i): Actual temperature of segment Si at FDT position [degC]

[0105] t(FDT)(i): time for segment Si to pass through the FDT position [s]

[0106] t(CT): time for segment Si to pass through the CT position [s]

[0107] T(t)(i): Temperature of segment Si at time t [degC]

[0108] The other variables are basically the same as those in equations (1) and (2).

[0109] The FF calculation unit 23 also uses the outlet temperature prediction value T CT CAL (i) and the outlet temperature target value T CT AIM The water injection rates in the FF beds are changed so that the difference between (i) and (f) decreases. During the change, the water injection rates are determined within the cooling mode range to maintain the cooling mode. FF control is performed after the water injection rates are determined. Valve response delay is taken into account in FF control. Specifically, before the segment Si reaches the cooling bed whose water injection rate has been changed, the valve opening and closing operation of the cooling bed is started so that cooling can be carried out in a timely manner based on the changed water injection rate.

[0110] When the segment Si reaches the recalculated position SP, the recalculating unit 24 reduces the actual value dT based on the temperature from the FDT position to the recalculated position SP. actcal , and the temperature reduction prediction value dT from the recalculated position SP to the CT position, the outlet temperature prediction value T of the segment Si at the CT position CT CAL (i) Recalculate the actual temperature drop dT actcal Calculated based on the cooling history. The temperature drop prediction value dT is calculated based on the predicted speed of the strip M and the amount of water injected into the FB bed. The outlet temperature prediction value T CT CAL The recalculation of (i) is performed using, for example, equations (5) to (7).

[0111]

[0112]

[0113]

[0114] The variables shown in formulas (5) to (7) are as follows.

[0115] t(SP): time for segment Si to pass through the recalculated position SP [s]

[0116] v act (t): Actual speed of section Si [m / s]

[0117] δ act (t): type of cooling obtained as actual value for the segment Si (water cooling by water injection or air cooling) [-]

[0118] The other variables are basically the same as those in equations (1) to (4).

[0119] The FB calculation unit 25 performs FB calculation. In the FB calculation, the outlet temperature actual value T representing the actual temperature of the segment Si at the CT position is calculated. CT ACT and the outlet temperature target value T CT AIM In the FB calculation, the Smith method is also used to compensate for the temperature change of the segment Si associated with the delay in the transport time from each position of the FB bed to the CT position and the response delay of the FB bed. Figure 4 This FB calculation will be described.

[0120] Figure 4 This is a control block diagram related to FB control performed by the control device 20 . Figure 4 The feedback controller 26 and the controlled object 27 are depicted in FIG. The feedback controller 26 includes a PID controller G C and a Smith compensator 28 .

[0121] The control object 27 includes the target device G P , delivery delay e -D1s , and valve response delay e -D2s (“s” is the Laplace operator). Transmission delay e -D1s The delay e represents the time it takes to deliver the segment Si at the distance D1 from each position of the FB bed to the CT position. -D2s It means that the response delay of FB bed wastes time.

[0122] The Smith compensator 28 includes the object device model G PM , transport delay model -D1Ms , and valve response delay model e -D2Ms Delivery Delay Model -D1Ms This is a model for calculating the temperature correction value of the segment Si associated with the delay in the transport time from each position of the FB bed to the CT position. Valve response delay model e -D2MS This is a model for calculating the temperature correction value of the segment Si associated with the response delay of the FB bed.

[0123] The temperature difference ΔT shown in equation (8) is input to the PID controller 26a. E .

[0124] ΔT E =r-(y+y M1 -y M22 )…(8)

[0125] The variables shown in formula (8) are as follows.

[0126] r: The predicted temperature of the strip M at the CT position obtained in the precalculation

[0127] y: actual temperature of the strip M at the CT position

[0128] y M1 : The predicted temperature of the segment Si at the CT position calculated when the segment Si reaches the recalculated position SP

[0129] y M22 : y calculated when segment Si reaches the recalculated position SP M1 , and is recorded in the memory after the calculation and read from the memory when the segment Si reaches the CT position M1

[0130] 1-3. Temperature control process of the control device

[0131] Reference Figure 5 6. The control flow from the start to the end of cooling of the strip M by the cooling device 12 will be described. Figure 5 1 is a diagram showing an example of control timing of temperature control performed by the control device 20 . Figure 6 1 is a flowchart showing a processing example of temperature control performed by the control device 20 .

[0132] The strip M is continuously rolled in a rolling mill located upstream of the ROT 10. Therefore, for example, after the leading section S1 of the strip M passes the entry-side thermometer 13, it takes several minutes for the trailing section Sm (m is a natural number) of the strip M to pass the exit-side thermometer 14. Figure 5 (i) of FIG. 1 depicts the status of ROT10 before the start of FB control. Figure 5 As shown in (i), the segment S1 after passing the FDT position advances in ROT10 and reaches the recalculated position SP. Figure 5 The recalculated position SP shown in (i) is based on the position of the #N-1 cooling bed.

[0133] Whenever a segment Si (1≤i≤m) reaches the recalculated position SP, it is executed Figure 6 The procedure shown. Figure 6 In the shown procedure, first, the counter Itr is set to zero (step S10). The counter Itr is used for convergence calculations performed in the processes after step S14.

[0134] Following the process of step S10, the outlet temperature prediction value T is calculated (recalculated) CT CAL (i) (Step S11) Outlet temperature prediction value T CT CAL The calculation (recalculation) of (i) is performed using, for example, equations (5) to (7). The outlet temperature prediction value T calculated by the process of step S11 is CT CAL (i) is used as the predicted temperature y M1 (i) and stored in the memory.

[0135] Following the processing of step S11, it is determined whether a section Si exists at the CT position (step S12). The processing of step S12 is performed to determine whether to start control FB. Whether a section Si exists at the CT position is determined based on, for example, the actual temperature of the strip M measured by the outlet temperature meter 14.

[0136] If it is determined in the process of step S12 that the segment Si exists at the CT position, FB control is executed (step S13). Figure 5 (ii) of FIG. 1 depicts the status of ROT10 during the execution of FB control. Figure 5 (ii) shows a segment Sj (1≤j≤m) existing at the CT position and a segment Sk (1≤k≤m) existing at the recalculated position SP.

[0137] However, the actual temperature measurement of the front end of the segment Sk is unstable. Therefore, the FB control of the segment Sk when the front end reaches the CT position is started after a predetermined time delay (for example, several seconds) from the arrival. In the FB control, the temperature difference ΔT is calculated using the above formula (8). E , and based on the temperature difference ΔT E To change the water injection rate in the FB bed #N-1.

[0138] For example, the temperature difference ΔT when the segment Sk reaches the recalculated position SP E , by using (9) and (10) to calculate the predicted temperature y M1 and y M22 Substitute into the above formula (8) to calculate.

[0139] y w22 =y M1 [J]...(9)

[0140] y M1 =y M1 [k]…(10)

[0141] Here, in equation (9), for the predicted temperature y M22 Use y M1 The reason for [j] is as follows. That is, as described in the explanation of formula (8), the predicted temperature y shown in formula (8) is M22 The predicted temperature y is calculated when the segment Si reaches the recalculated position SP, taking into account the delivery delay and valve response delay. However, this predicted temperature is equal to the predicted temperature y at the CT position of the segment Sj calculated when the segment Sj reaches the recalculated position SP. Therefore, in formula (9), for the predicted temperature y M22 Use y M1 [j].

[0142] The predicted temperature y shown in formula (10) M1 The calculation of [k] is performed based on the above-mentioned formula (5) (however, "i" in the formula (5) is replaced by "k").

[0143] The process of step S13 is repeatedly executed while it is determined that the segment Si exists at the recalculated position SP. Figure 5 (iii) of FIG. 1 shows the situation when the segment Sm (the last segment Si) reaches the recalculated position SP. After the segment Sm passes the recalculated position SP, Figure 6 The processing of the shown program ends.

[0144] If it is determined in step S12 that there is no segment Si at the CT position, the process after step S14 is executed. The process after step S14 is the temperature control before the start of FB control. In step S14, it is determined whether the outlet temperature prediction value T calculated in step S11 is CT CAL (i) and the outlet temperature target value T CT AIM Is the absolute value of the difference less than the threshold ΔT tol Threshold ΔT tol This is the temperature difference at which the amount of water injected into the FB bed needs to be changed, and is set in advance.

[0145] In the process of step S14, if it is determined that the absolute value is the threshold value ΔT tol In the above case, the output temperature prediction value T CT CAL (i) and the outlet temperature target value T CT AIMIs the sign of the difference between the two values negative (step S15)? The negative sign means that the predicted value of the outlet temperature T CT CAL (i) Lower than the outlet temperature target value T CT AIM On the contrary, the positive sign means that the predicted value of the outlet temperature T CT CAL (i) Higher than the outlet temperature target value T CT AIM .

[0146] Therefore, if the sign is determined to be negative, the water injection rate in the FB bed is reduced (step S16). Specifically, the water injection rate is reduced by closing one of the valves in the FB bed. On the other hand, if the sign is determined to be positive, the water injection rate in the FB bed is increased (step S17). Specifically, the water injection rate is increased by opening one of the valves in the FB bed.

[0147] Following the process of step S16 or S17, the outlet temperature prediction value T is calculated (recalculated again). CT CAL (i) (Step S18) The content of the process of step S18 is basically the same as that of step S12. The outlet temperature prediction value T calculated by the process of step S18 is CT CAL (i) is used as the predicted temperature y M1 (i) and stored in the memory.

[0148] Following the process of step S18, it is determined whether the counter Itr is lower than the threshold Itr max (Step S19) Threshold Itr max It is the upper limit of the number of repetitions of the processing of steps S14 to S18 and is set in advance. max It is set in a manner that does not hinder the execution of temperature control of segment S(i+1) that reaches the recalculated position SP after segment S(i) by taking into account the length of segment S(i), the actual speed value of segment S(i), the calculation processing speed of the processor, etc.

[0149] In the process of step S19, if it is determined that the counter Itr exceeds the threshold Itr max In the case of Figure 6 The processing of the shown routine ends. If it is determined that this is not the case, the process returns to step S14.

[0150] 1-4. Effect

[0151] Reference Figure 7 8. The effects of the first embodiment will be described. Figure 7It is a diagram showing the configuration of a comparative example of the control system of the first embodiment. Figure 8 This is a control block diagram related to FB control performed by the control device in this comparative example. Figure 7 Corresponding to Figure 2 , Figure 8 Corresponding to Figure 4 .

[0152] If Figure 2 and Figure 7 As can be seen from the comparison, Figure 7 In the comparative example shown, the functional configuration of the control device 30 is the same as that of Figure 2 The functional configuration of the control device 20 shown is different. Specifically, the control device 30 is different from the control device 20 in that it does not include the recalculation unit 24.

[0153] As already described, the recalculation unit 24 reduces the actual value dT based on the temperature from the FDT position to the recalculation position SP. actcal , and the temperature drop prediction value dT from the recalculated position SP to the CT position, and the recalculated side temperature prediction value T CT CAL (i) In contrast, the control device 30 does not include the recalculation unit 24. Therefore, in the control device 30, in the FB control of each water injection amount in the FB bed, only the outlet temperature actual value T representing the actual temperature of the segment Si at the CT position can be used. CT ACT and the outlet temperature target value T CT AIM FB calculation of the difference.

[0154] In this regard, according to the first embodiment, the outlet temperature prediction value T is recalculated at the recalculation position SP. CT CAL (i) Then, for the temperature difference ΔT input to the PID controller 26a, E Considering the recalculated outlet temperature prediction value T CT CAL (i) Therefore, it is possible to achieve stable temperature control for various rolling speeds.

[0155] Here, as in the first embodiment of Patent Document 1, it is possible to consider compensating for the wasted time caused by the conveyance of the strip in the FB control. Figure 7 The control device 30 of the embodiment performs the compensation of the wasted time. In this case, the diagram showing the control block diagram associated with the FB control of each water injection amount in the FB bed by the control device 30 corresponds to Figure 8 . Figure 4 and Figure 8 As can be seen from the comparison, Figure 8 In the comparative example shown, the control object 27 does not include the valve response delay e -D2S In addition, the Smith compensator 28 does not have a valve response delay model e -D2MS Therefore, in Figure 8 In the comparative example shown, the temperature difference ΔT input to the PID controller 26a is E Valve response delays are not taken into account.

[0156] In this regard, according to the first embodiment, since the temperature difference ΔT E By taking both the delivery delay and the valve response delay into account, the stability of the temperature control for various rolling speeds can be improved. Figure 2 The distance from the recalculated position SP to the CT position shown is 20 m, and the conveying speed of the strip M is 10 or 20 m / s. In this case, the conveying time is 2.0 or 1.0 s. Valve response delay is generally around 2 to 2.5 s, so it cannot be ignored. In addition, the conveying speed of the strip M tends to increase as the thickness decreases. For a 20 mm thickness, the conveying speed is 2.0 m / s, and for a 1.2 mm thickness, it increases to 20 m / s. Therefore, the impact of valve response delay is particularly significant when rolling thinner products.

[0157] Thus, according to the first embodiment, the recalculated outlet temperature predicted value T is considered. CT CAL (i) FB control for conveying delays and valve response delays. Therefore, the actual temperature of section Si can be controlled to the target temperature. Furthermore, according to the first embodiment, approximately one to two FB beds are installed on the downstream side of the ROT 10 (downstream of the pass line). Therefore, the actual temperature of section Si can be controlled to the target temperature while adhering to the cooling pattern of the FF bed installed upstream of the ROT 10 (upstream of the pass line).

[0158] 2. Second Implementation

[0159] Next, refer to Figures 9-13 A temperature control system according to a second embodiment of the present invention will be described. Explanations overlapping with those of the first embodiment will be omitted as appropriate.

[0160] 2-1. Overview of Second Embodiment

[0161] The FB control of the first embodiment allows the actual temperature of section Si to be controlled to the target temperature even when the rolling stock speed varies. However, the FB bed has a limited number of valves, so the amount of water injection can be increased or decreased. Therefore, in the second embodiment, before the water injection rate in the FB bed reaches the maximum or minimum water injection rate, water injection in the FB bed is switched to water injection in the FF bed.

[0162] Figure 9 This is a diagram explaining the outline of the control when the water injection rate in the FB bed is close to the maximum water injection rate (MAX). Figure 9 In this paper, we focus on the #N-1 cooling bed which is the FB bed. Figure 9 As shown in (i), in the #N-1 cooling bed, cooling water is supplied from a total of 6 valves. Figure 9 (i) shows the situation where the total number of valves of the #N-1 cooling bed is open, and the upper and lower valves on the upstream side of the rolling line are further opened. Here, if the total number of valves of the #N-1 cooling bed is 8, Figure 9 The situation shown in (i) can be said to be that the water injection amount in the FB bed is close to the maximum water injection amount. On the other hand, in the #h (1≤h≤N-2) cooling bed which is the FF bed, cooling water is not supplied (ie, air cooling).

[0163] In the second embodiment, Figure 9 As shown in (ii), the water injection from the total of 4 valves of the #N-1 cooling bed is switched to the water injection from the total of 2 valves of the #h cooling bed. If the switch cannot be satisfied by injecting water from the #h cooling bed alone, the water injection into the #N-1 cooling bed can be shared by the #h cooling bed and other cooling beds while complying with the cooling pattern. For example, when the cooling pattern is front-stage cooling, the water injection into the #N-1 cooling bed can be shared by the #h and #h+1 cooling beds to comply with the cooling pattern. The water injection into the #h cooling bed accompanying the switch begins before the segment Si (hereinafter also referred to as the "target segment TSi") to be injected after the switch reaches the position of the #h cooling bed. In addition, the water injection into the #h cooling bed is started by taking into account the valve response delay.

[0164] like Figure 9 As shown in (iii), the water injection from the four valves of cooling bed #N-1 accompanying the switching is stopped before the target zone TSi reaches the position of cooling bed #N-1. The water injection is stopped by the time delay of the valve response to prevent cooling water from reaching the target zone TSi.

[0165] Figure 10 This is a diagram explaining the outline of the control when the water injection rate in the FB bed is close to the minimum water injection rate (MIN). Figure 9 Likewise, in Figure 10 We also focus on the #N-1 cooling bed as the FB bed. Figure 10 As shown in (i), in the #N-1 cooling bed, cooling water is supplied from a total of two valves. Figure 10 (i) shows the situation where the total of 4 valves of the #N-1 cooling bed are open, and the upper and lower valves on the upstream side of the rolling line are closed. Figure 10 The situation shown in (i) can be said to be that the water injection amount in the FB bed has approached the minimum water injection amount. On the other hand, in the cooling bed #h which is the FF bed, cooling water is supplied from a total of four valves.

[0166] In the second embodiment, Figure 10 As shown in (ii), the cessation of water injection from the total two valves of the #N-1 cooling bed is switched to the cessation of water injection from the total two valves of the #h cooling bed. If this switching cannot be achieved by simply stopping water injection in the #h cooling bed, the water injection in the #N-1 cooling bed can be shared by the #h cooling bed and other cooling beds while complying with the cooling pattern. For example, if the cooling pattern is front-stage cooling, the cessation of water injection in the #N-1 cooling bed can be shared by the #h-1 and #h cooling beds to comply with this cooling pattern. The cessation of water injection in the #h cooling bed accompanying the switching is performed before the target segment TSi reaches the position of the #h cooling bed. The cessation of water injection in the #h cooling bed is also performed taking into account valve response delay.

[0167] like Figure 10 As shown in (iii), water injection from the two valves of cooling bed #N-1 accompanying the switch is performed before the target segment TSi reaches the position of cooling bed #N-1. Water injection is advanced by the time delay of the valve response to prevent cooling water from falling into the target segment TSi.

[0168] Whether to switch the water injection is determined based on, for example, the following conditions (11) and (12) related to an upper threshold value corresponding to the maximum water injection amount or a lower threshold value corresponding to the minimum water injection amount. If conditions (11) or (12) are met, the water injection is switched.

[0169]

[0170]

[0171] The meanings of the values on both sides of conditions (11) and (12) are as follows.

[0172] α FB UP : Adjustment coefficient of the upper threshold

[0173] α FB LW: Adjustment coefficient of the lower threshold

[0174] N FB AVA : Total number of valves that can be used

[0175] N FB ON: Total number of valves currently open

[0176] 2-2. Processing example of control device

[0177] Figures 11-13 This is a flowchart showing an example of temperature control processing performed by the control device 20 in the second embodiment. Figures 11-13 The flowchart shown is for example Figure 6 It is executed as part of the processing of step S13 shown in FIG.

[0178] exist Figure 11 In the procedure shown, first, it is determined whether condition (11) is satisfied (step S20). Satisfaction of condition (11) means that the water injection amount in the FB bed is close to the maximum water injection amount. In this case, execution Figure 12 On the other hand, if it is determined that condition (11) is not satisfied, it is determined whether condition (12) is satisfied (step S21). The meaning of satisfying condition (12) is that the water injection amount in the FB bed is close to the minimum water injection amount. In this case, execute Figure 13 Processing of the program shown.

[0179] 2-2-1. When the water injection volume is close to the maximum injection volume

[0180] exist Figure 12 In the procedure shown, the case number Nmm is first set (step S30). The case number Nmm is a consecutive number used to store the processing results of steps S31 to S33 in the memory (the initial value of Nmm is 1). In the process of step S30, the number of changes Nmm of the FF bed valve is also set. CH＿FF The initial value N CH＿FF INI And the number of changes N of the valve of the FB bed CH＿FB The initial value N CH＿FB INI .

[0181] Initial value N CH＿FF INI and N CH＿FB INI It is expressed by equations (13) and (14).

[0182]

[0183]

[0184] In addition, the number of changes N CH＿FB and N CH＿FF It can be changed as an adjustment item as appropriate.

[0185] Change number N when reducing the number of valves of the FB bed CH＿FB The upper limit N CH＿FB MAX＿Dec For example, it is assumed that a maximum of 4 valves can be closed by one change (i.e., N CH＿FB MAX＿Dec =4) On the other hand, when the number of valves of the FF bed is increased, the change number N CH＿FF The upper limit N CH＿FF MAX＿Inc The number of valves in the currently usable closed state (ie, valves that can be changed to the open state by switching) is set according to the cooling mode.

[0186] In the process of step S30, the valve of the FF bed to be switched (hereinafter also referred to as "switching valve") is also determined according to the cooling mode. Consider the case where the cooling mode is front-stage cooling. In this case, the switching valve is the valve located most upstream in the ROT 10 (i.e., the valve of the FF bed closest to the inlet side of the cooling device 12) among the valves in the currently usable closed state of the FF bed. CH＿FB When the number is 2 or more, two or more valves included in the FF bed to be switched (hereinafter also referred to as “switch bed”) correspond to the switching valves.

[0187] Following step S30, the target segment TSi is determined (step S31). When a valve on an FF bed is opened, there is a delay in the valve's response until the water injection rate actually changes. Therefore, in step S31, to ensure rapid switching, the segment Si that will first pass through the position of the switching valve when the water injection rate changes due to the opening of the switching valve is predicted. This segment Si is set as the target segment TSi.

[0188] Furthermore, in recent computer control systems, the calculation and transport times are approximately several milliseconds. Therefore, the time required for the prediction calculation of the target segment TSi has little effect on the temperature change of the target segment TSi. Furthermore, in this prediction calculation, the time required for transporting the target segment TSi is calculated based on the predicted speed of the strip M. This predicted speed is calculated based on the actual speed of the strip M and the operating conditions of the hot rolling line, and is repeatedly revised as needed.

[0189] Following the process of step S31, the outlet temperature prediction value T representing the predicted temperature of the target segment TSi at the CT position is calculated. CT CAL(Nmm) (Step S32) Outlet temperature prediction value T CT CAL The calculation of (Nmm) is performed using, for example, equations (5) to (7) (however, "segment Si" in equations (5) to (7) is replaced with "target segment TSi").

[0190] Following the process of step S32, the predicted outlet temperature value T calculated in the process of step S32 is determined. CT CAL (Nmm) and outlet temperature target value T CT AIM Is the absolute value of the difference less than the threshold ΔT tol (Step S33). The processing of step S33 is the same as Figure 6 The processing of step S14 shown is basically the same.

[0191] In the process of step S33, it is determined that the absolute value is the threshold value ΔT tol In the above case, the processing results of steps S31 to S33 are saved (step S34). Next, the output side temperature prediction value T is determined. CT CAL (Nmm) and outlet temperature target value T CT AIM Is the sign of the difference between the two negative (step S35). The processing of step S35 is the same as Figure 6 The processing of step S15 shown is the same.

[0192] The negative sign of the difference means that the predicted value of the outlet temperature T CT CAL (Nmm) lower than the outlet temperature target value T CT AIM Therefore, when it is determined that the sign is negative, the number of valves in the open state of the FB bed is reduced by one (the change number N CH＿FB →Number of changes N CH＿FB -1)(Step S36). As a result, the amount of water injected into the FB bed is reduced, so the outlet temperature prediction value T CT CAL (Nmm) rise.

[0193] The positive sign of the difference means that the predicted value of the outlet temperature T CT CAL (Nmm) higher than the outlet temperature target value T CT AIM Therefore, it is possible to increase the number of open valves in the FB bed, but the water injection amount in the FB bed is close to the maximum water injection amount. Therefore, if the sign is positive, the number of switching valves (valves that switch from closed state to open state) in the switching bed is increased by 1 (the change number N is 0).CH＿FF →Number of changes N CH＿FF +1) (step S37). As a result, the water injection amount in the conversion bed increases, so the outlet temperature prediction value T CT CAL (Nmm) reduced.

[0194] Following the process of step S36 or S37, the change number N is determined. CH＿FB or N CH＿FF Whether the upper limit has been reached (step S38). The processing of step S38 is performed based on whether the condition (15) or (16) is satisfied.

[0195]

[0196]

[0197] The abs(N CH＿FB ) is the number of changes N CH＿FB The absolute value of abs(N CH＿FF ) is the number of changes N CH＿FF The absolute value of .

[0198] In the process of step S38, it is determined that the number of changes N CH＿FB or N CH＿FF If the upper limit has not been reached, the case number Nmm is incremented by 1 and the process returns to step S31 (Nmm→Nmm+1). That is, the process of steps S31 to S38 is repeatedly executed while the case number Nmm is incremented until a positive result is obtained in the process of step S33.

[0199] In the process of step S38, it is determined that the number of changes N CH＿FB or N CH＿FF When the upper limit is reached, the optimal combination of the case number Nmm and the target segment TSi is selected (step S39). The outlet temperature prediction value T is selected from the case number Nmm stored in the memory by the process of step S34. CT CAL (Nmm) and outlet temperature target value T CT AIM The case number Nmm with the smallest absolute value of the difference is selected as the best combination.

[0200] 2-2-2. When the water injection volume is close to the minimum water injection volume

[0201] exist Figure 13 In the procedure shown, the case number Nmm is first set (step S40). The processing content of step S40 is the same as Figure 12 The processing contents of step S30 shown are basically the same. However, the initial value NCH＿FF INI and N CH＿FB INI It is expressed by equations (17) and (18).

[0202]

[0203]

[0204] Change number N when increasing the number of valves of the FB bed CH＿FB The upper limit N CH＿FB MAX＿Inc For example, it is assumed that a maximum of 4 valves can be opened by a single change (i.e., N CH＿FB MAX＿Inc =4) On the other hand, the change number N when the number of valves of the FF bed is reduced CH＿FF The upper limit N CH＿FF MAX＿Dec The number of valves in the currently usable open state (ie, valves that can be changed to the closed state by switching) is set according to the cooling mode.

[0205] In the process of step S40, the switching valve is further determined according to the cooling mode. Consider the case where the cooling mode is front-stage cooling. In this case, the switching valve is the valve located most downstream among the valves in the currently usable open state of the FF bed (i.e., the valve closest to the FF bed on the outlet side of the cooling device 12). CH＿FB When the number is 2 or more, the two or more valves included in the conversion bed correspond to the conversion valves.

[0206] Following step S40, the target segment TSi is determined (step S41). When a valve on an FF bed is closed, there is a delay in the valve's response until the water injection rate actually changes. Therefore, in step S41, to ensure rapid switching, the segment Si that will first pass through the position of the switching valve when the water injection rate changes due to the closing of the switching valve. This segment Si is set as the target segment TSi.

[0207] Following the processing of step S41, the processing of steps S42 to S45 is performed. The processing contents of steps S42 and S43 are the same as those of Figure 12 The processing contents of steps S32 to S35 shown are the same.

[0208] In the process of step S45, the negative sign of the difference means that the predicted outlet temperature value T CT CAL (Nmm) lower than the outlet temperature target value T CT AIMTherefore, it is possible to increase the number of closed valves in the FB bed, but the water injection amount in the FB bed is close to the minimum water injection amount. Therefore, if the sign of the difference is determined to be negative, the number of switching valves (valves that switch from open to closed state) in the FF bed is increased by 1 (the change number N is 0. CH＿FF →Number of changes N CH＿FF +1) (step S46). As a result, the amount of water injected into the conversion bed is reduced, so the outlet temperature prediction value T CT CAL (Nmm) rise.

[0209] On the other hand, the positive sign of the difference means that the predicted outlet temperature value T CT CAL (Nmm) higher than the outlet temperature target value T CT AIM Therefore, when it is determined that the sign of the difference is positive, the number of valves in the open state of the FB bed is increased by one (the change number N is CH＿FB →Number of changes N CH＿FB +1) (step S47). As a result, the water injection amount in the FB bed increases, so the outlet temperature prediction value T CT CAL (Nmm) reduced.

[0210] Following the process of step S46 or S47, the number of changes N is determined. CH＿FB or N CH＿FF Whether the upper limit has been reached (step S48). The processing of step S48 is performed based on whether the condition (19) or (20) is satisfied.

[0211]

[0212]

[0213] In the process of step S48, if it is determined that the number N is changed CH＿FB or N CH＿FF If the upper limit has not been reached, the case number Nmm is incremented by 1 and the process returns to step S41 (Nmm→Nmm+1). That is, the processes of steps S41 to S48 are repeatedly executed while the case number Nmm is incremented until a positive determination result is obtained in step S43.

[0214] In the process of step S48, it is determined that the number of changes N CH＿FB or N CH＿FF When the upper limit is reached, the best combination of case number Nmm and target segment TSi is selected (step S49). Figure 12 The processing contents of step S39 shown are the same.

[0215] 2-3. Effect

[0216] According to the second embodiment, the actual temperature of the sector Si including the target sector TSi can be controlled to the target temperature while preventing the water injection amount in the FB bed from becoming the maximum water injection amount or the minimum water injection amount.

[0217] Explanation of symbols

[0218] 10 Roller table (ROT)

[0219] 12 Cooling equipment

[0220] 13 Inlet side thermometer

[0221] 14 Outlet side thermometer

[0222] 20, 30 control devices

[0223] 21 Pre-computing unit

[0224] 22 Cooling History Management Department

[0225] 23 Feedforward calculation unit

[0226] 24 Recalculation Department

[0227] 25 Feedback calculation unit

[0228] 26 Feedback Controller

[0229] 27 Control Object

[0230] 28 Smith compensator

[0231] M Plate and strip (rolled material)

[0232] S, Si, Sj, Sk, Sm segments

[0233] SP recalculates position

[0234] T CT ACT Actual value of outlet temperature

[0235] T CT AIM Outlet temperature target value

[0236] T CT CAL Outlet temperature prediction value

[0237] T FDT CAL Inlet temperature prediction value

[0238] dT Temperature drop prediction value

[0239] dT actcal Actual value of temperature reduction

Claims

1. A control device for a cooling device, which is provided in a rolling line and cools a rolled material through a plurality of cooling beds, characterized in that: The control device is configured to control the water injection amount of each of the plurality of cooling beds so that an outlet temperature target value indicating the target temperature of the rolled material at the position of an outlet temperature meter provided on the outlet side of the cooling device is consistent with an outlet temperature actual value indicating the actual temperature of the rolled material measured by the outlet temperature meter. The control device performs pre-calculation, cooling history management, feed-forward calculation and feedback calculation in controlling the water injection amount of each of the plurality of cooling beds. In the above-mentioned pre-calculation, the above-mentioned control device The plurality of cooling beds are set as feedforward beds for performing feedforward control of the water injection amount, or as feedback beds for performing feedback control of the water injection amount, The feedback bed is at least one cooling bed sequentially allocated from the downstream side of the rolling line according to the rolled material, and the feedforward bed is the remaining cooling bed. calculating an outlet temperature prediction value indicating the predicted temperature of the rolled material at the position of the outlet thermometer, The water injection amount of each of the plurality of cooling beds is calculated in such a way that the outlet temperature prediction value is consistent with the outlet temperature target value. In the cooling history management, the control device The position of the rolled material is grasped by a section, which represents an interval when the rolled material is divided into an imaginary length in the conveying direction. The cooling history is stored in sections, the cooling history including the actual speed of the rolled material at each position of the plurality of cooling beds and the history of each water injection amount in the plurality of cooling beds. In the above feedforward calculation, the above control device The predicted exit temperature value is calculated for each section based on an actual entry temperature value indicating the actual temperature of the rolled material at the position of an entry thermometer installed on the entry side of the cooling device and the speed of the rolled material at the position of the entry thermometer. Based on the difference between the outlet temperature target value and the outlet temperature prediction value calculated for each section, the water injection amount in the feedforward bed calculated in the pre-calculation is changed. In the feedback calculation, the control device calculates the difference between the actual outlet temperature value and the target outlet temperature value according to the segment. The control device further sets a recalculation position for re-implementing the feedback calculation in the cooling history management. The recalculated position is located upstream of the rolling line relative to the position of the feedback bed by a distance corresponding to the response delay of the feedback bed. When the segment reaches the recalculated position, the control device recalculates the predicted outlet temperature value for the segment reaching the recalculated position based on the cooling history. The control device further performs the feedback calculation. When the segment reaches the recalculated position, a temperature correction value is calculated to compensate for a delay in the transport time from the position of the feedback bed to the position of the outlet thermometer and a response delay of the feedback bed. Based on the outlet temperature target value, the outlet temperature actual value calculated for each section, the recalculated outlet temperature prediction value, and the temperature correction value, the water injection amounts in the feedback bed calculated in the precalculation are changed for each section.

2. The control device for the cooling device according to claim 1, wherein: The control device further calculates the predicted speed of the rolled material. The control device mentioned above, in the above recalculation, Based on the cooling history from the position of the entry thermometer to the recalculated position, an actual temperature drop value of the rolled material conveyed from the position of the entry thermometer to the recalculated position is calculated for each section; Based on the predicted speed and the water injection amounts in the plurality of cooling beds obtained by the pre-calculation, a predicted temperature drop value of the rolled material from the recalculated position to the position of the outlet thermometer is calculated for each section. The outlet temperature prediction value is calculated based on the actual temperature drop value and the predicted temperature drop value.

3. The control device for a cooling device according to claim 1 or 2, wherein: Apply the specified cooling pattern to each water injection rate in the above feedforward bed, The control device changes each water injection amount in the feedforward bed within the range of the predetermined cooling pattern during the feedforward calculation.

4. The control device for a cooling device according to claim 1 or 2, wherein: Apply the specified cooling pattern to each water injection rate in the above feedforward bed, The control device further comprises: According to the feedback bed, it is determined whether the water injection amount in the feedback bed is close to the maximum water injection amount or the minimum water injection amount. When it is determined that the water injection rate in the feedback bed has approached the maximum water injection rate or the minimum water injection rate, the water injection or stop of the water injection in the feedback bed is switched to the feedforward bed within the range of the predetermined cooling mode.

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