Control device for a hot rolling line

Abstract

Provided is a control device for a hot rolling line that can suppress destabilization of cooling in a transition boiling region while maintaining the response performance of feedback control of coiling temperature. The control device controls cooling of a rolled material by an upstream-side bank after correcting a reference value of a target temperature of the rolled material in feedforward control of the upstream-side bank by a correction value. The control device controls cooling of the rolled material based on feedback control of a downstream-side bank after correcting a reference value of a cooling water amount for the rolled material in feedback control of the downstream-side bank by a correction value calculated by a feedback correction value calculation section.

Description

Technical Field

[0001] This invention relates to a control device for a hot rolling production line. Background Technology

[0002] Patent Document 1 discloses a control device for a hot rolling production line. According to this control device, it is possible to suppress the instability of cooling in the transition boiling region.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 4894686 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, the control device described in Patent Document 1 omits the feedback bank near the winding temperature gauge. As a result, the response performance of the feedback control for the winding temperature decreases.

[0008] This invention addresses the aforementioned problems. The objective of this invention is to provide a control device for a hot rolling production line capable of suppressing cooling instability in the transition boiling region while maintaining the responsiveness of feedback control for coiling temperature.

[0009] Methods used to solve problems

[0010] The control device for the hot rolling production line of the present invention includes: a feedforward correction value calculation unit, which calculates a correction value based on the deviation between the target value and the measured value of the coiling temperature of the rolled material in the feedforward control of the upstream silo at the ROT cooling device, for a hot rolling production line where the rolled material is cooled by water injection in the ROT cooling device and then coiled by a coiler; a feedback correction value calculation unit, which calculates a correction value corresponding to the correction value calculated by the feedforward correction value calculation unit, for a reference value of the cooling water volume of the rolled material in the feedback control of the downstream silo at the ROT cooling device; and a control unit, which controls the cooling of the rolled material performed by the upstream silo after correcting the reference value of the target temperature of the rolled material in the feedforward control of the upstream silo by the correction value calculated by the feedforward correction value calculation unit, and controls the cooling of the rolled material based on the feedback control of the downstream silo after correcting the reference value of the cooling water volume of the rolled material in the feedback control of the downstream silo by the correction value calculated by the feedback correction value calculation unit.

[0011] Invention Effects

[0012] According to the present invention, the control device controls the cooling of the rolled material by the upstream silo after correcting the reference value of the target temperature of the rolled material in the feedforward control of the upstream silo with a correction value. The control device also controls the cooling of the rolled material based on the feedback control of the downstream silo after correcting the reference value of the cooling water volume for the rolled material in the feedback control of the downstream silo with a correction value calculated by the aforementioned feedback correction value calculation unit. Therefore, it is possible to suppress the instability of cooling in the transition boiling region while maintaining the responsiveness of the feedback control of the coiling temperature. Attached Figure Description

[0013] Figure 1 This is a structural diagram of the main parts of the hot rolling production line, which is the control device of the hot rolling production line in Implementation Method 1.

[0014] Figure 2 This is a diagram showing the history of temperature drop of the rolled material in the hot rolling production line using the control device of the hot rolling production line in Implementation Method 1.

[0015] Figure 3 This is a diagram illustrating the heat flow of the hot rolling production line brought about by water cooling in the control device of the hot rolling production line in Implementation Method 1.

[0016] Figure 4 This is a perspective view of the cutting plate of the control device of the hot rolling production line using Implementation Method 1.

[0017] Figure 5 This is a block diagram of the main parts of the control device for the hot rolling production line in Implementation Method 1.

[0018] Figure 6 This is a graph showing the predicted temperature of the cut plate calculated by the control device of the hot rolling production line in Embodiment 1.

[0019] Figure 7 This is a diagram used to illustrate the non-interference of two feedback controls performed by the control device of the hot rolling production line in Embodiment 1.

[0020] Figure 8 This diagram illustrates a method by which a large portion of the cooling water from the downstream tank is added to other tank groups, as performed by the control device of the hot rolling production line of Embodiment 1.

[0021] Figure 9 Explain the operation of the control device of the hot rolling production line in Implementation Method 1.

[0022] Figure 10 This is a hardware structure diagram of the control device for the hot rolling production line in Implementation Method 1.

[0023] Figure 11 This is a block diagram of the main parts of the control device for the hot rolling production line in Embodiment 2. Detailed Implementation

[0024] The embodiments will be described with reference to the accompanying drawings. Furthermore, in each drawing, the same or corresponding parts are assigned the same reference numerals. Repeated descriptions of these parts will be appropriately simplified or omitted.

[0025] Implementation method 1.

[0026] Figure 1 This is a structural diagram of the main parts of the hot rolling production line, which is the control device of the hot rolling production line in Implementation Method 1.

[0027] exist Figure 1 The hot rolling production line has a finishing mill 1 located downstream of a roughing mill (not shown). A ROT cooling device 2 is located downstream of the finishing mill 1. Pinch rolls 3 are located downstream of the ROT cooling device 2. A coiler 4 is located downstream of the pinch rolls 3.

[0028] ROT cooling unit 2 includes a water injection system. In ROT cooling unit 2, the water injection system is divided into multiple reservoirs by a cooling water supply system. These reservoirs are arranged along the length of the hot rolling production line. Each reservoir has multiple water injection valves. These valves are arranged along the length of the hot rolling production line. Each water injection valve is equipped with multiple nozzles. These nozzles are arranged along the width of the hot rolling production line.

[0029] The finishing mill exit temperature gauge 5 is installed between the finishing mill 1 and the ROT cooling device 2. The coiling temperature gauge 6 is installed between the ROT cooling device 2 and the pinch roll 3.

[0030] The finishing mill 1 finishes the rolled material. Then, the finishing mill exit thermometer 5 measures the initial temperature of the rolled material along its entire length before cooling, as the actual FDT value. Next, the ROT cooling device 2 cools the rolled material by injecting water at a certain pressure. Then, the coiling thermometer 6 measures the initial temperature of the rolled material along its entire length, as the actual CT value. Finally, the coiler 4 coils the rolled material. The position of the rolled material is based on the circumferential speed v of the final stand of the finishing mill 1, which determines the production line speed. FM7 and the circumferential speed v of the winding machine 4 pc track.

[0031] The control device 7 includes a storage unit 7a, a feedforward correction value calculation unit 7b, a feedback correction value calculation unit 7c, and a control unit 7d.

[0032] Control device 7, via control unit 7d, uses a temperature model to calculate the predicted temperatures of the inlet and outlet sides of each chamber of the ROT cooling device 2 for each cut plate, starting from the actual FDT value of the cut plate k, in a manner that ensures the final predicted CT value reaches the target value. At this time, half of the water injection valves are pre-opened at the downstream chamber.

[0033] If the final CT prediction value is inconsistent with the target value, the control device 7 updates the set value of the cooling water volume at each tank on the upstream side other than the downstream tank, and then calculates the predicted value of the inlet and outlet temperature of each tank of the ROT cooling device 2 for each cutting plate.

[0034] If the final CT prediction value matches the target value, the control device 7 sets the setpoint of the cooling water volume at each reservoir on the upstream side, excluding the downstream reservoir, to the reference value V. k FF_ref .

[0035] On the upstream side, excluding the downstreammost reservoir, each reservoir ensures that the cooling water volume meets the reference value V. k FF_ref The method determines the number of water injection valves to be opened, thereby cooling each cutting plate.

[0036] exist Figure 1 In this process, for the cutting plate k, the first to fifth cartridges from the upstream side are used. In this case, the control device 7, through the feedforward correction value calculation unit 7b, calculates the target value CT based on the winding temperature, using the reference value of the target temperature of the cutting plate k in the feedforward control of the upstream cartridges. cmd and measured CT values k－a act The correction value ΔCT for the deviation k aim The control device 7 uses the following equation (1) to calculate the target value CT of the temperature model. k aim .

[0037] [Formula 1]

[0038] CT k aim =CT cmd +ΔCT k aim (1)

[0039] For the cutting plate k-b, the control device 7, through the feedback correction value calculation unit 7c, calculates the reference value V for the cooling water volume of the rolled material in the feedback control of the downstream warehouse. k－b 2nd_ref The correction value ΔCT is calculated and compared with the correction value calculated by the feedforward correction value calculation unit 7b. k aim The corresponding correction value ΔV k－b 2nd_ref .

[0040] The correction value ΔCT is applied whenever the temperature changes through the cutting plate directly below the winding thermometer 6. k aim and correction value ΔV k－b2nd_ref CT based on measured values ​​of winding temperature k－a act And change.

[0041] Control device 7 stores, via storage unit 7a, the actual value V of the cooling water volume of the downstream reservoir (excluding the downstream reservoir) in use. k 1st_act Information.

[0042] Control device 7 uses the reference value of the target temperature in the feedforward control of the upstream reservoir via control unit 7d and the correction value ΔCT calculated by feedforward correction value calculation unit 7b. k aim After correction, the cooling of each cutting plate is controlled by the upstream warehouse.

[0043] When each cutting plate reaches the downstream storage area, the control device 7, via the control unit 7d, sets a reference value V. k－b 2nd_ref_mod Cooling of each cutting plate is controlled based on feedback control from the downstream hopper, with a reference value V. k－b 2nd_ref_mod It is the reference value V for the cooling water volume of the cutting plate in the feedback control of the downstream tank. k－b 2nd_ref The correction value ΔV calculated by the feedback correction value calculation unit 7c k－b 2nd_ref The result is obtained by making corresponding corrections. At this point, the correction value ΔV k－b 2nd_ref Sometimes, the actual value of the cooling water volume V is used for each cutting plate. k 1st_act .

[0044] Next, use Figure 2 This describes the history of temperature drop in the rolled material.

[0045] Figure 2 This is a diagram showing the history of temperature drop of the rolled material in the hot rolling production line using the control device of the hot rolling production line in Implementation Method 1.

[0046] like Figure 2 As shown, each warehouse takes into account the material of the rolled material and adjusts the interval of opening the water injection valve in a way that meets the preset cooling rate setting.

[0047] Next, use Figure 3 This indicates the heat flow brought about by water cooling.

[0048] Figure 3 This is a diagram illustrating the heat flow of the hot rolling production line brought about by water cooling in the control device of the hot rolling production line in Implementation Method 1.

[0049] like Figure 3 As shown, when the surface of the rolled material is in a film boiling state, water vapor exists between the surface of the rolled material and the cooling water. If the surface temperature of the rolled material decreases, the surface of the rolled material transitions from a film boiling state to a transitional boiling state. If the surface temperature of the rolled material decreases further, the surface of the rolled material transitions from a transitional boiling state to a nucleation boiling state. In the nucleation boiling state, the upper surface of the rolled material is in overall contact with the cooling water. As a result, steam bubbles are locally generated.

[0050] When the surface of the rolled material is in a state of transitional boiling, the heat flux is smaller in the high-temperature region compared to the low-temperature region at the beginning of cooling. Therefore, cooling is slow. In contrast, the heat flux is larger in the low-temperature region, thus accelerating cooling. As a result, the temperature difference between the high-temperature and low-temperature regions widens at the beginning of cooling.

[0051] If cooling is carried out while the surface of the rolled material is in a state of transitional boiling, local temperature unevenness will accumulate and expand. As a result, in the cooled steel plate, in addition to poor flatness and residual stress, uneven material distribution such as hardness and strength may also occur.

[0052] Next, use Figure 4 Explain the considerations for the temperature model.

[0053] Figure 4 This is a perspective view of the cutting plate of the control device of the hot rolling production line using Implementation Method 1.

[0054] like Figure 4 As shown, when the rolled material is conveyed directly below the ROT cooling device 2, the heat input and output are calculated based on the assumption that the rolled material is divided into slabs of a certain length. For example, the certain length is set between 3m and 5m.

[0055] As factors in the movement of heat, one can think of water-cooled heat conduction, radiation, and heat generation due to phase changes. For example, if only water-cooled heat conduction is a factor, the heat dissipation Q from water cooling... water (W) is represented by the following equation (2).

[0056] [Formula 2]

[0057] Q water =h w A W (T surf -T w (2)

[0058] In equation (2), h w It is the water-cooled thermal conductivity coefficient (W / mm) 2 / ℃). A wIt is the area (mm²) of the upper and lower surfaces of the cutting plate that are in contact with the cooling water. 2 A w The amount varies depending on the number of water injection valves opened in each reservoir. surf This is the surface temperature (°C) of the cutting plate. w It is the temperature of the cooling water (°C).

[0059] At this time, the temperature change of each cutting plate is represented by the following equation (3).

[0060] [Formula 3]

[0061]

[0062] In equation (3), ΔT i Δt is the temperature drop (°C) of the cutting plate k at location i. i is the location number of the storage unit. Δt is the time (s) for the cutting plate k to pass through location i. k H is the length (mm) of the cutting plate k in the direction of travel. k This refers to the thickness (mm) of the cut plate k. B k ρ is the width (mm) of the cutting plate k. ρ is the density (kg / mm³) of the cutting plate k. 3 C P It is the specific heat of the cutting plate k (J / kg / ℃).

[0063] Next, use Figure 5 This indicates the correction value ΔCT k aim and the corrected baseline value V k－b 2nd_ref_mod The calculation method.

[0064] Figure 5 This is a block diagram of the main parts of the control device for the hot rolling production line in Implementation Method 1.

[0065] exist Figure 5 On the left, the PID gain of the first PID controller is set considering the inactive transfer time up to the winding temperature gauge 6. The first PID controller accepts the target value CT of the winding temperature. cmd CT values ​​compared with actual values k－a act The first PID controller receives information about the deviation from the target value CT of the winding temperature. cmd CT values ​​compared with actual values k－a act The correction value ΔCT is calculated by multiplying the deviation by the PID gain. k aim .

[0066] exist Figure 5On the right side, the PID gain of the second PID controller is set considering the inactive transfer time up to the winding temperature gauge 6. The second PID controller is responsible for setting the target value CT of the winding temperature. cmd CT values ​​compared with actual values k－a act The input is the information obtained by reversing the sign of the deviation. The second PID controller uses the target value CT of the winding temperature to achieve the desired winding temperature. cmd CT values ​​compared with actual values k－a act The baseline value V for cooling water volume is calculated by multiplying the value obtained by reversing the sign of the deviation by the PID gain. k－b 2nd_ref The corrected baseline value V k－b 2nd_ref_mod By V k－b 2nd_ref_mod Subtract the actual value V k 1st_act To calculate.

[0067] Next, use Figure 6 This indicates the predicted temperature of the cutting plate at ROT cooling device 2.

[0068] Figure 6 This is a graph showing the predicted temperature of the cut plate calculated by the control device of the hot rolling production line in Embodiment 1.

[0069] Figure 6 This represents the predicted temperature of the cutting plate assuming a fixed throughput speed at a storage bin. Before the cutting plate cools, the control device 7 uses equations (2) and (3) to calculate the predicted temperature of each cutting plate on the inlet and outlet sides of each storage bin.

[0070] If the actual FDT value changes, then for each cutter, the number of libraries used for libraries other than the last one changes. As a result, the number of libraries that become the last one among those used for libraries other than the last one also changes.

[0071] like Figure 6 As shown, at the correction value ΔCT aim When the temperature is less than 0, the target temperature setpoint CT of the temperature model is... aim The target value of CT becomes higher than the winding temperature. cmd Small. In this case, among the warehouses that are used, the warehouse that is the most downstream becomes the warehouse that is further downstream.

[0072] For example, if the downstream reservoir is the fourth reservoir from the upstream side at the current moment, the water injection valve of the fifth reservoir from the upstream side is opened, thereby increasing the cooling water volume for the reservoirs other than the downstream reservoir.

[0073] Next, use Figure 7 This demonstrates the non-interference mechanism of the two feedback controls.

[0074] Figure 7 This is a diagram used to illustrate the non-interference of two feedback controls performed by the control device of the hot rolling production line in Embodiment 1.

[0075] When the cutting plate k reaches the inlet side of the downstream tank, the control device 7 determines the reference value V of the cooling water volume at the downstream tank. k 2nd_ref Subtract the actual value V k 1st_act .

[0076] Next, use Figure 8 This describes a method of adding most of the cooling water from the downstream reservoir to other reservoir groups.

[0077] Figure 8 This diagram illustrates a method by which a large portion of the cooling water from the downstream tank is added to other tank groups, as performed by the control device of the hot rolling production line of Embodiment 1.

[0078] After a certain period of time has elapsed since the cooling process began, at the downstream end of the storage area, the cutting plate k is being processed. －b The baseline value of cooling water volume V k－b 2nd_ref_mod If the value is not lower than the preset threshold, the control device 7 will adjust the cooling water volume reference value V. k－b 2nd_ref_mod A certain percentage (e.g., 80%) is converted into a correction value ΔCT for the target temperature through a temperature model. k－b 2nd At this point, the correction value ΔCT for the target temperature... k－b 2nd Less than 0.

[0079] Control device 7 uses equation (4) to correct the target value CT of the temperature model for the cutting plate k. k aim .

[0080] [Formula 4]

[0081] CT k aim =CT cmd +ΔCT k aim +ΔCT k-b 2nd (4)

[0082] As a result, the cooling water volume of the cutting plate k at the downstream end of the tank increases.

[0083] Next, use Figure 9 Explain the operation of control device 7.

[0084] Figure 9 Explain the operation of the control device of the hot rolling production line in Implementation Method 1.

[0085] In step S1, the control device 7 calculates the target value CT of the winding temperature based on the cutting plate k. cmd CT values ​​compared with actual values k－a act The correction value ΔCT for the deviation k aim Then, control device 7 performs step S2. In step S2, the control device determines the correction value ΔCT. k aim Is it less than 0?

[0086] If the correction value is less than 0 in step S2, the control device proceeds to step S3. In step S3, the control device determines the correction value ΔCT. k aim .

[0087] If the correction value in step S2 is not less than 0, the control device proceeds to step S4. In step S4, the control device determines the reference value V of the cooling water volume. k－b 2nd_ref Is it 0?

[0088] If the reference value of the cooling water volume is not 0 in step S4, the control device proceeds to step S5. In step S5, the control device adjusts the correction value ΔCT. k aim Set it to 0. Then, the control device determines the correction value in step S3.

[0089] If the reference value of the cooling water volume is 0 in step S4, the control device determines the correction value in step S3.

[0090] According to Embodiment 1 described above, after correcting the reference value of the target temperature of the rolled material in the feedforward control of the upstream silo using a correction value, the control device 7 controls the cooling of the rolled material performed by the upstream silo. After correcting the reference value of the cooling water volume for the rolled material in the feedback control of the downstream silo using a correction value calculated by the feedback correction value calculation unit, the control device 7 controls the cooling of the rolled material performed by the feedback control of the downstream silo. Therefore, it is possible to suppress the instability of cooling in the transition boiling region while maintaining the responsiveness of the feedback control for coiling temperature.

[0091] Furthermore, the control device 7 performs the aforementioned control on each of the multiple cutting plates. Therefore, it is possible to more reliably suppress cooling instability in the transition boiling region.

[0092] Furthermore, the control device 7 performs feedback control on the downstream silo to obtain the cooling water volume obtained by subtracting the correction value corresponding to the reference value of the target temperature of the rolled material in the feedforward control for the upstream silo from the reference value of the cooling water volume in the feedback control of the downstream silo. Therefore, non-interference of the two feedback controls can be achieved.

[0093] Furthermore, when the correction value for the reference value of the target temperature of the rolled material in the feedforward control of the upstream silo is 0 or higher, and when the deviation between the target value and the measured value of the coiling temperature of the rolled material is 0 or lower, the control device 7 does not perform corrections for each reference value. Therefore, it is possible to preferentially reduce the cooling water volume of the downstream silo used in the feedback control.

[0094] Furthermore, after a certain period of time has elapsed since the start of cooling, if the reference value of the cooling water volume is not less than a preset threshold, the control device 7 converts a certain percentage of the reference value into a correction value for the target temperature using a temperature model. Therefore, it is possible to reduce the cooling water volume in the downstream reservoir used in feedback control.

[0095] Next, use Figure 10 An example illustrating control device 7.

[0096] Figure 10 This is a hardware structure diagram of the control device for the hot rolling production line in Implementation Method 1.

[0097] The functions of the control device 7 can be implemented by a processing circuit. For example, the processing circuit has at least one processor 100a and at least one memory 100b. For example, the processing circuit has at least one dedicated hardware 200.

[0098] When the processing circuit has at least one processor 100a and at least one memory 100b, the functions of the control device 7 are implemented by software, firmware, or a combination of software and firmware. At least one of the software and firmware is described as a program. At least one of the software and firmware is stored in at least one memory 100b. The at least one processor 100a reads and executes the program stored in the at least one memory 100b to implement the functions of the control device 7. The at least one processor 100a is also referred to as a central processing unit, processing device, arithmetic unit, microprocessor, microcomputer, or DSP. For example, the at least one memory 100b is a non-volatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, EEPROM, disk, floppy disk, optical disk, CD, MD, DVD, etc.

[0099] When the processing circuit has at least one dedicated hardware 200, the processing circuit is implemented, for example, by a single circuit, a composite circuit, a programmable processor, a parallel programmable processor, an ASIC, an FPGA, or a combination thereof. For example, each function of the control device 7 is implemented by a processing circuit. For example, the combined functions of the control device 7 are implemented by a processing circuit.

[0100] Regarding the various functions of the control device 7, some can be implemented using dedicated hardware 200, while others can be implemented using software or firmware. For example, the functions of the control unit 7d can be implemented using a processing circuit as dedicated hardware 200, while functions other than those of the control unit 7d can be implemented by at least one processor 100a reading and executing a program stored in at least one memory 100b.

[0101] In this way, the processing circuit implements the functions of the control device 7 through hardware 200, software, firmware, or a combination thereof.

[0102] Implementation method 2.

[0103] Figure 11 This is a block diagram of the main parts of the control device for the hot rolling production line in Embodiment 2. Furthermore, parts that are the same as or correspond to those in Embodiment 1 are given the same reference numerals. Descriptions of these parts are omitted.

[0104] In implementation method 2, the Smith method is applied.

[0105] exist Figure 11 In China, CT scans k pre_1st This is the predicted coiling temperature of the cutting plate k, located directly below the exit-side thermometer 5 of the finishing mill. CT k pre_1st This is the predicted coiling temperature calculated when the cutting plate k-a is directly below the finishing mill exit thermometer 5. CT k－b pre_2nd This is the predicted winding temperature of cutter k-b at the moment it reaches the inlet side of the downstream chamber. CT k－a pre_2nd The winding temperature of the cutting plate k-a is a predicted value calculated when the cutting plate k-a reaches the inlet side of the downstream chamber. This predicted value information is stored in the storage unit 7a of the control device 7.

[0106] like Figure 11 As shown on the left, in the inner feedback loop, the input does not include invalid time CT. k pre_1st In the outer feedback loop, the CT... k－a act and CTk－a pre_1st The deviation is used as the model prediction error input. Correction value ΔCT k aim The calculation is based on these inputs.

[0107] like Figure 11 As shown on the right, in the inner feedback loop, the input does not include invalid time CT. k－b pre_2nd In the outer feedback loop, the input CT... k－a act and CT k－a pre_2nd The deviation is taken as the model prediction error. (Base value V) k－b 2nd_ref The calculation is based on these inputs.

[0108] According to Implementation Method 2 described above, the Smith method is applied. Therefore, the control gain can be increased.

[0109] Industrial availability

[0110] As described above, the control device for the hot rolling production line of the present invention can be used in a hot rolling production line.

[0111] Label Explanation

[0112] 1 Finishing mill; 2 ROT cooling device; 3 Pinch rolls; 4 Coiler; 5 Finishing mill exit side thermometer; 6 Coiler thermometer; 7 Control device; 7a Storage unit; 7b Feedforward correction value calculation unit; 7c Feedback correction value calculation unit; 7d Control unit; 100a Processor; 100b Memory; 200 Hardware.

Claims

1. A control device of a hot rolling line, comprising: a feedforward correction value calculation section that, for a hot rolling line in which a rolled material rolled by a finishing mill is cooled by water injection by a ROT cooling device and then coiled by a coiler, calculates a correction value based on a deviation of a target value from an actual value of a coiling temperature of the rolled material, for a reference value of a target temperature of the rolled material in feedforward control of a bank on an upstream side of the ROT cooling device; a feedback correction value calculation section that, for a reference value of a cooling water amount for the rolled material in feedback control of a bank on a downstream side of the ROT cooling device, calculates a correction value corresponding to the correction value calculated by the feedforward correction value calculation section; and a control section that, after the reference value of the target temperature of the rolled material in the feedforward control of the bank on the upstream side is corrected by the correction value calculated by the feedforward correction value calculation section, controls cooling of the rolled material by the bank on the upstream side, and after the reference value of the cooling water amount for the rolled material in the feedback control of the bank on the downstream side is corrected by the correction value calculated by the feedback correction value calculation section, controls cooling of the rolled material based on the feedback control of the bank on the downstream side.

2. The control device of a hot rolling line according to claim 1, wherein: the feedforward correction value calculation section calculates a correction value based on a deviation of a target value from an actual value of a coiling temperature, for a reference value of a target temperature of each of a plurality of slabs into which the rolled material is hypothetically divided; the feedback correction value calculation section calculates a correction value corresponding to the correction value calculated by the feedforward correction value calculation section, for a reference value of a cooling water amount for each of the plurality of slabs; and the control section, for each of the plurality of slabs, after the reference value of the target temperature in the feedforward control of the bank on the upstream side is corrected by the correction value calculated by the feedforward correction value calculation section, controls cooling by the bank on the upstream side, and after the reference value of the cooling water amount in the feedback control of the bank on the downstream side is corrected in correspondence with the correction value calculated by the feedback correction value calculation section, controls cooling based on the feedback control of the bank on the downstream side.

3. The control device of a hot rolling line according to claim 1 or 2, wherein: the control section performs the feedback control of the bank on the downstream side so as to be a cooling water amount obtained by subtracting a correction value of the cooling water amount corresponding to the correction value calculated by the feedforward correction value calculation section from the reference value of the cooling water amount in the feedback control of the bank on the downstream side.

4. The control device of a hot rolling line according to claim 1 or 2, wherein: the control section, in a case where the correction value calculated by the feedforward correction value calculation section is 0 or more and a case where a deviation of a target value from an actual value of a coiling temperature of the rolled material is 0 or less, does not correct the reference value of the target temperature of the rolled material in the feedforward control of the bank on the upstream side by the correction value calculated by the feedforward correction value calculation section to control cooling by the bank on the upstream side, and does not correct the reference value of the cooling water amount for the rolled material in the feedback control of the bank on the downstream side in correspondence with the correction value calculated by the feedback correction value calculation section to control cooling based on the feedback control of the bank on the downstream side. ​ ​ ​ ​ ​ ​ ​ ​ 5. The control device of a hot rolling line according to claim 1 or 2, wherein after a certain time elapses from the start of the cooling, in a case where the reference value of the amount of cooling water does not become smaller than a threshold value set in advance, the control section converts a certain proportion of the reference value to a correction value of the target temperature by a temperature model, and controls the cooling of the rolled material by the upstream-side battery after correcting the reference value of the target temperature of the rolled material in the feedforward control of the upstream-side battery by the correction value.

6. The control device of a hot rolling line according to claim 1 or 2, wherein the feedforward correction value calculation section receives an input of a predicted value of the coiling temperature not including an invalid time in the inner feedback loop, receives an input of a deviation between an actual value and the predicted value of the coiling temperature in the outer feedback loop, and calculates a correction value of the reference value of the target temperature of the rolled material in the feedforward control of the upstream-side battery based on these inputs; the feedback correction value calculation section receives an input of a predicted value of the coiling temperature not including an invalid time in the inner feedback loop, receives an input of a deviation between an actual value and the predicted value of the coiling temperature in the outer feedback loop, and calculates a reference value of the amount of cooling water for the rolled material in the feedback control of the downstream-side battery based on these inputs.

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