Roller cooling control device

Abstract

The invention provides a roll cooling control device. The rolling / idling prediction unit predicts the time at which the next rolled material reaches the roll at the transition time from the rolling to the idling state. The cooling water amount monitoring unit acquires the amount of cooling water supplied to the nozzle at the transition point in time. The roll thermal expansion amount prediction unit predicts the amount of thermal expansion of the roll at the prediction target period and the transition point in time using the time predicted by the rolling / idling prediction unit as the prediction target period. The cooling water amount reduction calculation unit and the roll thermal expansion amount prediction unit cooperate with each other to calculate the cooling water amount to be reduced in the prediction target period so that the difference between the thermal expansion amount at the transition time point and the thermal expansion amount in the prediction target period falls within a predetermined range. The variable flow valve adjustment unit adjusts the opening degree of the variable flow valve so as to reduce the amount of cooling water calculated by the cooling water amount reduction calculation unit.

Description

Technical Field

[0001] The present disclosure relates to a roll cooling control device for cooling a roll of a rolling mill, and particularly to a roll cooling control device for a hot rolling mill preferably suitable for rolling a rolling material such as a metal material. Background Art

[0002] As rolling equipment installed in a rolling line, there is a hot rolling mill (hereinafter referred to as a "rolling mill") that rolls a rolling material heated by a heating furnace. The rolling mill has one or more stands. The stand has a pair of upper and lower working rolls (hereinafter referred to as rolls), and the plate thickness at the exit of the rolling mill is controlled to a target plate thickness by appropriately calculating and controlling the roll gap and roll rotation speed.

[0003] Furthermore, the rollers will thermally expand due to the heat input from the rolling material to the rollers and the heat generated by the friction between the rolling material and the rollers. In order to prevent excessive thermal expansion, cooling water is sprayed on the rollers to cool the rollers, thereby suppressing the temperature of the rollers within a specified range. When cooling the rollers, cooling water is sprayed at a certain pressure to improve the cooling effect. Therefore, generally, multiple pumps are driven to supply water with a higher pressure than other water supply systems, and the load on the pumps and the motors driving the pumps becomes larger.

[0004] Patent Document 1 discloses a thermal shock control method for suppressing thermal shock (roll profile change) caused by thermal expansion of a roll. In this control method, energy-saving operation during idling (non-rolling) is achieved by performing VVVF (Variable Voltage Variable Frequency) control on a pump.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-272354 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] The method disclosed in Patent Document 1 aims to suppress the thermal shock (thermal expansion) of the roll, but does not consider controlling the thermal expansion of the roll in the increasing or growing direction. From the perspective of the plate thickness controllability of the rolling mill, it is not necessarily ideal to reduce the thermal expansion of the roll, but it is ideal not to reduce the thermal expansion of the roll excessively. In other words, if the thermal expansion of the roll is reduced excessively, it will interfere with the calculation and control of the roll gap and the roll rotation speed, and it may have an adverse effect on the plate thickness controllability.

[0010] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a roll cooling control device capable of cooling a roll without adversely affecting the plate thickness controllability.

[0011] Means used to solve problems

[0012] The first viewpoint of the present disclosure is about a roll cooling control device for cooling the rolls of a rolling mill. The rolling mill is provided with: a nozzle for spraying cooling water on the rolls; one or more pumps for supplying cooling water to the nozzles; and a variable flow valve capable of changing the flow rate of cooling water supplied from the pump to the nozzles. The roll cooling control device is provided with a rolling / idling prediction unit, a cooling water quantity monitoring unit, a roll thermal expansion prediction unit, a cooling water quantity reduction calculation unit, and a variable flow valve adjustment unit. The rolling / idling prediction unit takes the time point when the rolling state changes to the idling state as the transition time point, and predicts the time when the next rolled material arrives at the roll at the transition time point. The cooling water quantity monitoring unit obtains the amount of cooling water supplied to the nozzle at the transition time point. The roll thermal expansion prediction unit takes the time predicted by the rolling / idling prediction unit as the prediction object period, and predicts the thermal expansion of the roll during the prediction object period and at the transition time point, respectively. The cooling water quantity reduction calculation unit calculates the cooling water quantity to be reduced during the prediction target period in cooperation with the roll thermal expansion amount prediction unit so that the difference between the thermal expansion amount at the transition time point and the thermal expansion amount during the prediction target period falls within a predetermined range. The variable flow valve adjustment unit adjusts the opening of the variable flow valve so as to reduce the cooling water quantity calculated by the cooling water quantity reduction calculation unit.

[0013] The second viewpoint of the present disclosure is about a roll cooling control device for cooling the rolls of a rolling mill. The rolling mill is provided with: a nozzle for spraying cooling water on the rolls; one or more pumps for supplying cooling water to the nozzles; and a variable flow valve capable of changing the flow rate of cooling water supplied from the pump to the nozzles. The roll cooling control device is provided with a rolling / idling prediction unit, a roll thermal expansion prediction unit, a cooling water amount reduction calculation unit, and a variable flow valve adjustment unit. The rolling / idling prediction unit uses rolling information to predict the rolling period and the idling period in a prescribed prediction target period. The roll thermal expansion prediction unit predicts the thermal expansion amount of the rolls in the prediction target period. The cooling water amount reduction calculation unit cooperates with the roll thermal expansion prediction unit, and takes the maximum thermal expansion amount of the rolls maintained when the maximum amount of cooling water is supplied to the nozzles as the thermal expansion amount target value, and calculates the cooling water amount to be reduced in the prediction target period in such a way that the difference between the thermal expansion amount target value and the thermal expansion amount in the prediction target period falls within a prescribed range. The variable flow valve adjustment unit adjusts the opening of the variable flow valve so as to reduce the cooling water amount calculated by the cooling water amount reduction calculation unit.

[0014] In addition to the first viewpoint or the second viewpoint, the third viewpoint has the following features. The pump includes a variable speed pump. The roll cooling control device also includes a variable speed pump adjustment unit. The variable speed pump adjustment unit adjusts the speed of the variable speed pump according to the opening of the variable flow valve adjusted by the variable flow valve adjustment unit.

[0015] In addition to the first viewpoint or the second viewpoint, the fourth viewpoint has the following features. A drain valve is provided between the pump and the variable flow valve. The roll cooling control device further includes a drain valve adjustment unit. The drain valve adjustment unit adjusts the opening of the drain valve in a manner that reduces the amount of cooling water calculated by the cooling water amount reduction calculation unit when the opening of the variable flow valve is adjusted by the variable flow valve adjustment unit.

[0016] In addition to the first aspect, the fifth aspect has the following features: the variable flow valve adjustment unit is configured to adjust the opening of the variable flow valve to a minimum opening when the difference between the thermal expansion amount at the transition time point and the thermal expansion amount during the prediction target period exceeds a predetermined range.

[0017] In addition to the first viewpoint, the sixth viewpoint has the following features. The rolling mill continuously performs rolling in an idling state that is shorter than a specified time. The rolling / idling prediction unit is configured to predict rolling and idling in a second prediction object period that is longer than the prediction object period. The cooling water amount reduction calculation unit is configured to use the maximum thermal expansion amount of the rolling roll maintained when the maximum amount of cooling water is supplied to the nozzle as the thermal expansion amount target value during continuous rolling, and calculate the cooling water amount to be reduced in the second prediction object period in a manner such that the difference between the thermal expansion amount target value and the thermal expansion amount in the prediction object period falls within a specified range.

[0018] Effects of the Invention

[0019] According to the first viewpoint of the present disclosure, the opening of the variable flow valve is adjusted in such a way that the difference between the thermal expansion of the roll at the time of transition from rolling to the idling state and the thermal expansion of the roll during the predicted period until the next rolled material reaches the roll falls within a specified range. As a result, the amount of cooling water supplied to the roll is appropriately controlled to prevent the thermal expansion of the roll from excessively decreasing in the idling state. Therefore, the roll can be cooled without adversely affecting the plate thickness controllability.

[0020] According to the second viewpoint of the present disclosure, the thermal expansion amount of the roll during the prediction object period including multiple rolling and idling state is predicted, and the opening of the variable flow valve is adjusted in such a way that the difference between the predicted thermal expansion amount and the thermal expansion amount target value falls within a specified range. As a result, the amount of cooling water supplied to the roll is appropriately controlled, and the thermal expansion amount can reach the thermal expansion amount target value as quickly as possible. Therefore, the roll can be cooled without adversely affecting the plate thickness controllability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram schematically showing the configuration of a rolling line to which the roll cooling control device according to the embodiment is applied.

[0022] Figure 2 This is a schematic diagram schematically showing the configuration of a process control computer of a roll cooling control device according to an embodiment.

[0023] Figure 3 This is a diagram showing the concept of calculation of the thermal expansion amount of a roll.

[0024] Figure 4 This is a diagram showing an example of growth of the thermal expansion amount of a roll during hot rolling.

[0025] Figure 5 This is a diagram showing an example of an opening command value sequence of a variable flow valve.

[0026] Figure 6 This is a diagram showing an example of controlling the thermal expansion amount of the roll according to the first embodiment.

[0027] Figure 7 It is a flowchart for explaining the procedure of the roll cooling control according to the first embodiment.

[0028] Figure 8 This is a diagram showing an example of controlling the thermal expansion amount of the roll according to the second embodiment.

[0029] Fig. 9 This is a diagram showing an example of preliminary calculation of the average temperature rise of the roll.

[0030] Fig.10 To express the cooling water volume of the roll Fig. 9 The figure shows an example of the influence of the increase in the average temperature of the roll.

[0031] Fig.11 This is a diagram showing an example of the hardware configuration of a process control computer. DETAILED DESCRIPTION

[0032] Hereinafter, referring to the drawings, an embodiment of the present disclosure will be described by taking a case where the present invention is applied to a hot rolling mill as an example. In addition, the same reference numerals are given to common elements in each figure, and repeated descriptions are omitted.

[0033] Figure 1 FIG. 2 is a schematic diagram schematically showing the structure of a rolling production line to which the roll cooling control device according to the embodiment is applied. Figure 1As shown, the rolling line RL includes a rolling mill 1. A heating furnace (not shown) is provided upstream in the conveying direction of the rolling mill 1. The rolling mill 1 uses steel or other metal materials as a rolling material M, and rolls the rolling material M heated to a predetermined temperature by the heating furnace into a predetermined target product thickness.

[0034] The rolling mill 1 has one or more ( Figure 1 The example shown is a stand, which includes a pair of upper and lower working rolls 11, a pair of upper and lower support rolls 12, and a motor for rotating the rolls (not shown). Although not shown, a press-down device is provided on the support rolls 12, and the roll gap between the upper and lower working rolls 11 is controlled by adjusting the press-down opening of the press-down device. In this embodiment, the working roll 11 is a roll to be cooled. Hereinafter, the working roll 11 is also referred to as simply the roll 11.

[0035] The rolling mill 1 includes: a plurality of ( Figure 1 In the example shown, there are four nozzles 13 for spraying cooling water to the roll 11; a plurality of pumps 14 (14a to 14n) for supplying cooling water to the nozzles 13; and a variable flow valve 15 capable of changing the flow rate of cooling water supplied from the pump 14 to the nozzles 13. A motor 141 for driving the pump 14 is electrically coupled to each pump 14. A variable speed driver 142n is electrically coupled to the motor 141n of at least one pump 14n, whereby the pump 14n is configured as a variable speed pump capable of changing the rotation speed. The number of pumps 14 including the variable speed pump 14n can be appropriately set according to the nozzle 13 and further according to the water supply capacity to the roll 11. In addition, a check valve 16 is preferably provided on the nozzle 13 side (discharge side) of each pump 14. In addition, a drain valve 17 is interposed in a branch path 172 branched from a cooling water supply path 171 between the pump 14 and the variable flow valve 15. The drain valve 17 constitutes a part of the drain mechanism, and includes, for example, a bypass valve and a relief valve. Although not shown in the figure, another drain valve may be provided in the branch passage branching from the cooling water supply passage between the pump 14 and the check valve 16. The other drain valve also constitutes a part of the drain mechanism.

[0036] The rolling line RL is operated by a control system using a computer. The computer includes a host computer 2 and a process control computer 3 connected to each other via a network. The process control computer 3, which is a lower computer, is connected to an interface screen 4 as an operation screen operated by an operator via a network. The operator can perform input operations of control conditions on the interface screen 4, etc.

[0037] The process control computer 3 performs a series of setting calculations and controls of the control objects in the rolling process based on the rolling information (including the operation plan and the rolling process) received from the host computer 2. The target product thickness of the rolled material M is input from the host computer 2 to the process control computer 3. The process control computer 3 appropriately controls each device based on the target product thickness, the control conditions provided from the interface screen 4, etc. The process control computer 3 calculates the settings of each device that can achieve the target product thickness, and operates the actuators of each device based on these setting values. During the operation of each device, the process control computer 3 corrects the action of the actuator according to the values ​​obtained from various measuring instruments (not shown). The process control computer 3 operates the press-down device of the stand to adjust the roll gap in such a way that the actual thickness of the rolled material M becomes the target product thickness (i.e., offsets the thickness deviation).

[0038] Figure 2 The figure schematically shows the structure of the process control computer 3 of the roll cooling control device as an embodiment. The roll cooling control device 3 includes a roll thermal expansion prediction unit 31, a rolling / idling prediction unit 32, a cooling water quantity monitoring unit 33, a cooling water quantity reduction calculation unit 34, a variable flow valve adjustment unit 35, and a variable speed pump adjustment unit 36.

[0039] The roll thermal expansion amount prediction unit 31 calculates the thermal expansion amount of the roll 11 (hereinafter also referred to as "roll thermal expansion amount") using the thermal expansion model of the roll 11 and the heat input and output of the roll 11. Figure 1 As shown in the enlarged figure, the heat input and output relative to the working roll 11 includes the heat input from the rolled material M (material heat, friction heat, processing heat), the heat dissipation generated by the cooling water sprayed from the nozzle 13 (refer to the dotted line in the figure), the heat dissipation to the supporting roll 12, and the heat dissipation generated by air cooling. Figure 3 1 is a diagram showing the concept of calculating the thermal expansion amount of the roll 11. In the roll thermal expansion model, the difference method is used to calculate the thermal expansion amount of the roll 11. Figure 3 The temperature of each node (Node) 110 indicated by the black circle is calculated. The heat input from the rolled material M and the amount of heat dissipated to other parts are calculated, and the heat conduction to the inside of the roll 11 is expressed by a physical model. The temperature of each node 110 inside the roll 11 is calculated, and the thermal expansion of each node 110 generated by the temperature is calculated. The thermal expansion of each node 110 is integrated to calculate the thermal expansion based on the roll radius or diameter. In addition, the temperature of each node 110 inside the roll 11 is sometimes calculated, and the average temperature of the roll 11 is calculated based on the temperature of each node 110. The thermal expansion is calculated based on the relationship between the average temperature and the thermal expansion. In addition, based on Figure 3The calculation of the differential method shown sometimes takes time depending on the number of nodes 110. In the case of repeatedly performing real-time calculations and interacting with the cooling water reduction calculation unit 34 described later many times, the computer load may become high. Therefore, conditions can be determined in advance for calculation, the calculation results can be stored, and the calculation results can be extracted as needed. The conditions determined in advance include, for example, the plate thickness / plate width, hardness, temperature, etc. of the rolled material M, and the thermal expansion amount that will be generated when the roll 11 is rolled for several seconds under these conditions can be calculated in advance. In the case where the conditions do not match at all, linear interpolation or the like can be used for the extraction of the calculation results. In addition, the average temperature in the diameter direction, which is the reference for the thermal expansion amount calculation, can be calculated in advance. Figure 4 A diagram showing an example of the growth (increase) of the thermal expansion amount of the roll 11 during hot rolling. Since the heat input to the roll 11 during rolling is large due to heat dissipation, the thermal expansion amount increases. Since the heat dissipation from the roll 11 during non-rolling (idling) is larger than the heat input, the thermal expansion amount decreases. If rolling and non-rolling are repeated, the thermal expansion amount gradually saturates and stabilizes at a certain value, as shown by the approximate curve Ac in the figure as a dotted line. When calculating the thermal expansion amount of the roll in advance, the approximate curve Ac in Figure 4 can be calculated in advance.

[0040] The rolling / idling prediction unit 32 predicts the timing of rolling the rolled material M by the roll 11 (including the rolling start time t0), the rolling period (the time during rolling), the timing when the rolled material M exits the roll 11 and transitions (Japanese original text: migrates) to the idling state (non-rolling state), the idling period (the time in the idling state), the timing when the next rolled material (also called "the next material") M arrives at the roll 11 (future time), and the rolling period of the next material, etc., based on the above-mentioned rolling information received from the host computer 2. Since the heat balance of the roll 11 changes greatly depending on rolling and non-rolling, it is important for the rolling / idling prediction unit 32 to accurately predict the rolling / rolled timing, the rolling period / idling period.

[0041] The cooling water amount monitoring unit 33 obtains the flow rate of the cooling water supplied to the nozzle 13 and then to the roll 11 (hereinafter also referred to as "roll cooling water amount", "cooling water amount"). The cooling water amount monitoring unit 33 obtains the opening degrees and opening / closing (open / closed) information of various valves 15, 16, 17 provided in the rolling mill 1, and obtains information related to whether the cooling water is effectively used for cooling the roll 11 and / or information related to whether the cooling water is drained by the above-mentioned drainage mechanism.

[0042] The cooling water quantity reduction calculation unit 34 changes the roller cooling water quantity virtually, and obtains the roller thermal expansion quantity while cooperating with the roller thermal expansion quantity prediction unit 31 (while exchanging information), and calculates the roller cooling water quantity in such a way that the roller thermal expansion quantity is kept as constant as possible. The reason why the roller thermal expansion quantity is kept as constant as possible is that if the roller thermal expansion quantity changes excessively, the state of the roller 11 will change, which will adversely affect the rolling control and reset (reset) for ensuring product quality, such as plate thickness control, plate crown control, and flatness control. In addition to exchanging information with the roller thermal expansion quantity prediction unit 31, the cooling water quantity reduction calculation unit 34 also determines at which future timing the opening of the variable flow valve 15 and the rotation speed of the pump (including the variable speed pump 14n) 14 are set to what according to the information from the rolling / idling prediction unit 32, and obtains the roller cooling water quantity or the state of the drainage valve (bypass valve, overflow valve) 17 of the drainage mechanism according to the information from the cooling water quantity monitoring unit 33. Based on this information, a variable flow valve opening command value sequence for saving pump power is provided to the variable flow valve adjustment unit 35, or a pump output command value sequence is provided to the variable speed pump adjustment unit 36. Here, the command value sequence is set as command values ​​arranged in time series. Figure 5 FIG. 1 is a diagram showing an example of a command value sequence for a variable flow valve opening. The format of the command value sequence is not limited to Figure 5 The format shown may be any information as long as it specifies which command value is to be output at which time.

[0043] The variable flow valve adjustment unit 35 receives the variable flow valve opening command value sequence sent from the cooling water amount reduction calculation unit 34, and sends the determined command value to the variable flow valve 15 at a determined time. The command value sequence is in the form of a vector or matrix, and the command value is a scalar (single value). Here, in the case where the command value to the variable flow valve 15 changes sharply, a filter may be applied to the variable flow valve adjustment unit 35 to slow down the change of the command value, or as described later, Figure 6 The command value is made ramp-shaped as shown.

[0044] The variable speed pump adjustment unit 36 ​​also receives the pump output command value column sent from the cooling water volume reduction operation unit 34, and sends the determined command value to the variable speed driver 142n at a determined time. Here, in the case where the command value to the variable speed driver 142n changes sharply, a filter can also be applied to the variable speed pump adjustment unit 36 ​​to slow down the change of the command value, or to make the command value ramp-shaped. In addition, during the operation of the pump 14, if the pump 14 and the water flow resonate, the pump 14 may be damaged. Therefore, in the cooling water volume reduction operation unit 34 or the variable speed pump adjustment unit 36, it is sufficient to avoid operation near the resonance frequency.

[0045] Next, roll cooling control according to the first aspect of the present embodiment will be described. Figure 6 This is a diagram for explaining the control of the roll cooling water amount based on the first scheme. In the first scheme, the change in the roll thermal expansion amount is predicted by a model, and the roll cooling water amount is set to appropriately maintain the roll thermal expansion amount during the non-rolling (idling) between rolling, that is, the transition from rolling to idling state (time t1) until time t2 when the next rolling material M to be rolled arrives at the roll 11.

[0046] When the rolling operation is relatively smooth, and the interval between rolling is not too long, and the idling period is shorter than the prescribed period, the heat input from the rolling material M to the roll 11 and the heat dissipation to the cooling water sprayed to the roll 11 are in a roughly balanced state, and the roll thermal expansion amount will not increase or decrease significantly. Therefore, the roll diameter including thermal expansion and wear changes roughly fixedly, and will not have a big impact on the reset and control of rolling. Here, the wear of the roll 11 does not change sharply but gradually, so it is easier to deal with than the change of thermal expansion.

[0047] If the idling period (the period from time t1 to time t2) becomes longer due to some reason, the heat input from the rolled material M to the roll 11 will disappear. In this case, if the roll cooling water volume W during rolling is reduced to 0.01% at the time point (time t1) when the rolling state is changed to the idling state, RC0 If the heat dissipation to the cooling water remains unchanged, then Figure 6 The thermal expansion of the roll shown by the middle dotted line gradually decreases. At time t2 when the next rolling material M reaches the roll 11, the roll 11 contracts excessively, which sometimes interferes with the resetting and control of the next rolling material M. In addition, if the roll 11 is excessively cooled by the roll cooling water, the heat input of the next rolling material M causes the thermal expansion of the next rolling material M to increase sharply during rolling, which also interferes with the control. Therefore, when the interval between rolling is predicted to be longer, that is, when the idling period is predicted to be longer, the roll cooling water volume W is set to RC0 Reduce ΔW RC Let W RC0，new , so that the thermal expansion of the roller is not reduced excessively.

[0048] Figure 7 FIG. 1 is a flowchart for explaining the procedure of the roll cooling control based on the first embodiment. Figure 7 In the routine shown, first, it is determined whether the rolling state has shifted to the idling state (non-rolling) (step S1). If the rolling state has not shifted to the idling state, that is, if the rolling state is in progress, the routine is temporarily terminated.

[0049] When the rolling state is changed to the idling state, the rolling / idling prediction unit 32 uses the rolling information to calculate the time T until the next rolling material M reaches the position of the roll (roll to be cooled) 11 (step S2). The time T calculated in step S2 is also called the "prediction object period". The rolling information includes the position and length of the rolling material M on the rolling production line RL, the conveying speed of the rolling material M, the steel type and size (thickness, width, etc.) of the rolling material M, the temperature of the rolling material M, etc. As the temperature of the rolling material M, the measured value of a temperature sensor not shown in the figure can be used. In addition, for example, in the case where a plurality of stands with rolls 11 are arranged in parallel, that is, in the case where there are a plurality of rolls 11 to be cooled, the time (prediction object period) T should be set to the time until the next rolling material M reaches the roll 11 on the most upstream side (the front position close to the subsequent rolling material M).

[0050] Next, it is determined whether the time T calculated in step S2 is a threshold value T TH Above (step S3). If the time T is greater than the threshold T TH On the other hand, if the time T is the threshold value T TH If above, proceed to step S4.

[0051] In step S4, the cooling water amount monitoring unit 33 monitors the roll cooling water amount W at the time when the rolling state is changed to the idling state (non-rolling state). RC0 Make a record.

[0052] Next, the cooling water amount reduction calculation unit 34 calculates the cooling water amount that can be reduced within the prediction target period T while cooperating with the roll thermal expansion amount prediction unit 31 (while exchanging information). Specifically, first, the cooling water amount W recorded in the above step S4 is reduced. RC0 The reduction of roller thermal expansion ΔR for the duration T TH (Refer to Figure 6 ) is calculated (step S5). Next, the reduction amount ΔR of the thermal expansion of the roll calculated in step S5 is determined. TH Is it the threshold ΔR? TH，MIN (ΔR TH，MIN ≤0) or more (step S6). TH Ratio threshold ΔR TH，MIN If the amount of cooling water W is small, it is determined that the amount of cooling water W is small during the time T. RC0 That is, it is judged that even if the roller cooling water volume W RC0The duration T is such that the roll 11 will not be excessively cooled before the next rolling (the amount of thermal expansion of the roll will not change excessively). In this case, the amount of cooling water W for the roll is calculated. RC0 The opening command value sequence of the variable flow valve 15 in the case of continuous operation (see Figure 5 )(step S7), and proceed to step S11.

[0053] The reduction amount ΔR of the thermal expansion of the roll calculated in step S5 is TH is the threshold ΔR TH，MIN In the above case, if the roller cooling water volume W RC0 If the duration T is less than 100, it is determined that the roll 11 will be excessively cooled (the roll thermal expansion amount will change excessively) before the next rolling (time t2). In this case, the process proceeds to step S8. In step S8, the roll cooling water volume W is set to RC0 Reduce ΔW RC The obtained quantity is W RC0，new Calculation is performed, and similarly to the above step S5, the cooling water volume W to be reduced RC0，new The reduction of roller thermal expansion ΔR for the duration T TH Next, the reduction amount ΔR of the thermal expansion amount of the roll calculated in step S8 is determined. TH Is it greater than the above threshold ΔR TH，MIN The reduction in the thermal expansion of the roller is ΔR (step S9). TH Ratio threshold ΔR TH，MIN If the cooling water volume W is small, the process returns to step S8. RC0，new Further reduction to calculate the appropriate reduction in roll thermal expansion ΔR TH .

[0054] The ΔR calculated in step S8 TH than the above threshold ΔR TH，MIN If the amount of cooling water W is small, it is determined that during the time T, the amount of cooling water W of the roll is reduced. RC，new In this case, the amount of cooling water W to be reduced is calculated. RC，new The opening command value sequence of the variable flow valve 15 for the duration T (see Figure 5 )(step S10), and proceed to step S11.

[0055] In step S11, the opening command value sequence of the variable flow valve 15 calculated in step S10 or step S7 is set. Figure 5 At each time specified in the opening command value sequence shown, the opening command value specified in accordance with each time is output to the variable flow valve 15, thereby controlling the opening of the variable flow valve 15.

[0056] In step S12, the output command value sequence of the variable speed pump 14n during the time T is calculated corresponding to the opening command value sequence of the variable flow valve 15. RC0 If the condition continues, the speed of the variable speed pump 14n is set to maintain the current speed. RC0 Reduce to W RC0，new In this case, the reduction will be ΔW RC is converted into the rotation speed of the variable speed pump 14n. That is, the reduction amount ΔW is calculated. RC The output command value sequence of the variable speed pump 14n calculated in this way is set to the variable speed driver 142n of the variable speed pump 14n. Although not shown in the figure, at each time point determined in the output command value sequence, the variable speed driver 142n of the variable speed pump 14n outputs the pump command value determined corresponding to each time point, thereby controlling the speed of the variable speed pump 14n. During the time T, the speed of the variable speed pump 14n can be reduced by the reduction amount ΔW. RC , so energy saving can be achieved.

[0057] In addition, sometimes the prediction target period T is long, even if the roll cooling water volume W RC0 Even if the roller thermal expansion is reduced to the lower limit (e.g. 0%), the roller thermal expansion cannot be reduced by ΔR. TH Maintain at a certain threshold ΔR TH，MIN In this case, the opening of the variable flow valve 15 is adjusted to the minimum opening so that the roll cooling water volume W RC0 The configuration may be performed so as to reduce it to the lower limit value.

[0058] According to the above configuration, the difference ΔR between the thermal expansion of the roll at the transition time from rolling to the idling state (non-rolling) and the thermal expansion of the roll during the prediction target period T until the next rolling material M reaches the roll 11 is calculated. TH Falling into the specified range (compared to the threshold ΔR TH，MIN The opening of the variable flow valve 15 is adjusted in a manner such that the ...

[0059] Next, roll cooling control according to the second aspect of the present embodiment will be described. Figure 8 : is a diagram showing an example of controlling the thermal expansion of the roll based on the second scheme. In the second scheme, Figure 8The prediction target period T2 shown includes a plurality of rolling periods and idling periods (non-rolling periods), and is longer than the prediction target period T of the first embodiment. The second embodiment is preferably applicable to continuous rolling in which rolling is continuously performed with idling states shorter than a predetermined time.

[0060] In the second scheme, the thermal expansion of the roll within the prediction object period T from the current time (for example, the rolling start time) t0 to the future (to) is predicted at fixed time intervals, and the amount of cooling water for the roll that reduces the change in the predicted thermal expansion of the roll is calculated. The prediction object period T2 of the second scheme also corresponds to the "second prediction object period" in the claims. Figure 8 The dotted approximate curve Ac1 shows the change of the roll thermal expansion when the roll cooling water flow is fixed at 100% (maximum flow rate). The solid approximate curve Ac2 shows the change of the roll thermal expansion to the target value R shown by the dotted line as soon as possible. TG The example of the change of the roll thermal expansion when the roll cooling water volume is set in the manner of . During continuous rolling, the thermal expansion target value R TG The maximum thermal expansion amount of the roll 11 that is maintained when the maximum amount of cooling water is supplied to the nozzle 13 via the variable flow valve 15 can be set.

[0061] In order to realize the above-mentioned approximate curve Ac, the rolling / idling prediction unit 32 uses the rolling information to calculate the time from the current time (for example, the rolling start time t0) to a certain time t in the future. END The time until then is defined as a prediction target period T2, and a time schedule of rolling and non-rolling of the roll 11 in the prediction target period T2 is prepared.

[0062] The roll thermal expansion amount prediction unit 31 calculates the roll thermal expansion amount when the cooling water is sprayed to the roll 11 at a fixed flow rate for each rolling period and non-rolling period. The cooling water amount reduction calculation unit 34 cooperates with the roll thermal expansion amount prediction unit 31 to make the calculated thermal expansion amount close to the thermal expansion amount target value R TG The amount of cooling water for the rolls is determined in a manner to prevent the rolling material M from burning with the roll 11. At this time, if the minimum flow rate during rolling is predetermined, the lower limit of the amount of cooling water for the rolls during rolling is set according to the minimum flow rate. Similarly, if the minimum flow rate during non-rolling is predetermined, the lower limit of the amount of cooling water for the rolls during non-rolling is set according to the minimum flow rate.

[0063] Based on the roll cooling water volume thus determined, the opening command value sequence of the variable flow valve 15 is calculated in the same manner as in the first embodiment (see Figure 5), and the calculated opening command value sequence is set to the variable flow valve 15. Next, in order to save energy, the reduction amount ΔW of the roll cooling water volume is set to RC is converted into the rotation speed of the variable speed pump 14n. That is, the reduction amount ΔW is calculated. RC The output command value sequence of the variable speed pump 14n calculated in this way is set to the variable speed driver 142n of the variable speed pump 14n.

[0064] According to the second scheme, the thermal expansion amount of the roll 11 during the prediction target period T2 including multiple rolling periods and idling periods is predicted, and the predicted thermal expansion amount and the thermal expansion amount target value R are calculated. TG The opening of the variable flow valve 15 is adjusted so that the difference falls within a predetermined range. As a result, the amount of cooling water supplied to the roll 11 is appropriately controlled, and the thermal expansion amount can be made to reach the thermal expansion amount target value R in a timely and rapid manner. TG Therefore, the roll 11 can be cooled without adversely affecting the plate thickness controllability.

[0065] Furthermore, when the prediction object period T2 is long, the prediction accuracy of the roller thermal expansion amount becomes lower as the distance from the current time t0 increases. Therefore, the above series of processes can be performed at fixed intervals (for example, 10 seconds). The temporarily determined opening command value sequence of the variable flow valve 15 and the pump output command value sequence are updated at fixed intervals, thereby overwriting the new command value on the command value at the same time.

[0066] Here, refer to Figure 3 The calculation based on the difference method described above sometimes takes time, and the result calculated by using predetermined conditions can also be used. The conditions refer to, for example, the thickness / width, hardness, temperature, etc. of the rolled material M. Based on such conditions, if the rolling is performed for a few seconds by the roller 11, the amount of thermal expansion that will be generated is determined in advance by experiments or simulations. For the extraction of the thermal expansion determined in advance, linear interpolation can be performed when the conditions are completely inconsistent.

[0067] In addition, the radial direction (see Figure 3 )’s average temperature. Fig. 9 This is a diagram showing an example of the pre-calculation of the average roll temperature rise. Under the premise that the roll cooling water volume is set to 100% (maximum flow), the average roll temperature rise is calculated based on the average roll temperature at the start of rolling and the rolling time. Such calculations are performed separately according to the necessary divisions such as steel type division and plate thickness division included in the rolling information. In the case where the roll cooling water volume is not 100%, it is necessary to supplement it with cooling water. Fig.10 To express the cooling water volume of the roll Fig. 9The figure shows an example of the effect of the average roll temperature rise. The amount of cooling water and the average roll temperature rise are not necessarily linearly related. In addition, the degree of average temperature rise varies depending on the roll diameter. The maximum roll diameter refers to the roll diameter when the roll to be cooled is a new roll, and the minimum roll diameter refers to the roll diameter when the roll to be cooled is continuously used until just before it is discarded. Fig. 9 as well as Fig.10 It is difficult to calculate in a way that covers all conditions, so discrete values ​​of representative conditions are calculated in advance. The calculation results under discrete values ​​are stored in advance, and linear interpolation is performed between calculated points and lines in the area where calculation is not performed to extract various values. In this way, the time taken for calculating the average temperature of the roll and even the thermal expansion amount by the roll thermal expansion amount prediction unit 31 can be shortened.

[0068] If the calculation time of the roller thermal expansion amount prediction unit 31 is shortened, the prediction accuracy of the thermal expansion amount may be reduced. In addition, the prediction accuracy of the thermal expansion amount by the roller thermal expansion amount prediction unit 31 may be reduced due to interference. RC0，new If the accuracy of the variable flow valve 17 is reduced, the amount of cooling water supplied to the nozzle 13 may become excessive even if the opening of the variable flow valve 17 is changed. In this case, if the roller thermal expansion amount, cooling water amount, and opening instruction value sequence are calculated again, the calculation load will increase. Figure 1 The drain valve adjustment unit 37 shown in the figure opens the drain valve 17 and adjusts its opening degree, thereby being able to correct the cooling water amount supplied to the nozzle 13. The opening degree of the drain valve 17 may be set to reduce the cooling water amount calculated by the cooling water amount reduction calculation unit 34. This advantageously allows the drain valve 17 of the existing equipment to be used without increasing the calculation load.

[0069] The specific structure of the process control computer 3 is not limited, but as an example, it may be the following structure. Fig.11 The figure shows an example of the hardware configuration of the process control computer 3. The functions of the process control computer 3 can be Fig.11 The processing circuit shown in the figure can be implemented. The processing circuit can be dedicated hardware 30a. The processing circuit can include a processor 30b and a memory 30c. Alternatively, a part of the processing circuit can be formed as dedicated hardware 30a, and further include a processor 30b and a memory 30c. Fig.11 In the example, a part of the processing circuit is formed as dedicated hardware 30a, and the processing circuit also includes a processor 30b and a memory 30c.

[0070] At least a part of the processing circuit may be at least one dedicated hardware 30a. In this case, the processing circuit may be, for example, a single circuit, a complex circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

[0071] The processing circuit may include at least one processor 30b and at least one memory 30c. In this case, each function of the process control computer 3 is implemented by software, firmware, or a combination of software and firmware. The software and firmware are described as programs and stored in the memory 30c. The processor 30b reads out the program stored in the memory 30c and executes it, thereby realizing the functions of each part of the roll cooling control device 3.

[0072] The processor 30b is also called a CPU (Central Processing Unit), a central processing device, a processing device, an arithmetic device, a microprocessor, a microcomputer, or a DSP. As the memory 30c, non-volatile or volatile semiconductor memories such as RAM, ROM, flash memory, EPROM, and EEPROM are suitable.

[0073] In this way, the processing circuit can implement the functions of the process control computer 3 through hardware, software, firmware or a combination thereof.

[0074] The embodiments of the present disclosure are described above, but the present disclosure is not limited to the above embodiments, and various modifications can be made to implement without departing from the scope of the main purpose of the present disclosure. In the above embodiments, when the number, quantity, amount, range, etc. of each element is mentioned, the present invention is not limited to the mentioned number except for the case where it is particularly clearly indicated and the case where the number is clearly determined in principle. In addition, the structures described in the above embodiments are not necessary for the present invention except for the case where it is particularly clearly indicated and the case where it is clearly determined in principle.

[0075] In the above embodiment, the case of cooling the work roll 11 is described as an example, but the present disclosure can also be applied to the case of cooling the backup roll 12. In addition, in the above embodiment, the hot rolling mill is described as an example, but it is not limited to this. For example, since the rolls need to be cooled in cold rolling mills, plate rolling mills, rod and wire rolling mills, etc., the present disclosure can also be applied to these rolling mills.

[0076] In addition, the first and second embodiments of the above-mentioned embodiments may be combined and implemented. According to this, the thermal expansion amount of the roll 11 during the prediction target period T including multiple rolling periods and idling periods is predicted, and the predicted thermal expansion amount and the thermal expansion amount target value R are compared.TG The opening of the variable flow valve 15 is adjusted so that the difference falls within a predetermined range. As a result, the amount of cooling water supplied to the roll 11 is appropriately controlled, and the thermal expansion amount can be made to reach the thermal expansion amount target value R in a timely and rapid manner. TG . Achieve the target value of thermal expansion R TG After that, the thermal expansion amount of the roll 11 in the idling state is prevented from being excessively reduced. Therefore, the roll 11 can be cooled without adversely affecting the plate thickness controllability.

[0077] Explanation of symbols

[0078] 1 ... rolling mill, 11 ... working roll (roll), 12 ... support roll, 13 ... nozzle, 14 ... pump, 14n ... variable speed pump, 142n ... variable speed driver, 15 ... variable flow valve, 17 ... drain valve, 3 ... roll cooling control device, process control computer, 31 ... roll thermal expansion prediction unit, 32 ... rolling / idling prediction unit, 33 ... cooling water monitoring unit, 34 ... cooling water reduction calculation unit, 35 ... variable flow valve adjustment unit, 36 ... variable speed pump adjustment unit, 37 ... drain valve adjustment unit, M ... rolling material, RL ... rolling production line

Claims

1. A roller cooling control device for cooling the rollers of a rolling mill. The rolling mill comprises: a nozzle for spraying cooling water to the roll; one or more pumps for supplying cooling water to the nozzle; and a variable flow valve capable of changing the flow rate of cooling water supplied from the pump to the nozzle. The roll cooling control device comprises: A rolling / idling prediction unit, using rolling information, predicts a time when the next rolling material reaches the roll at a transition time point from the rolling state to the idling state; a cooling water quantity monitoring unit, for acquiring the cooling water quantity supplied to the nozzle at the transition time point; a roll thermal expansion amount prediction unit, which uses the time predicted by the rolling / idling prediction unit as a prediction target period, and predicts the thermal expansion amount of the roll during the prediction target period and at the transition time point, respectively; a cooling water quantity reduction calculation unit, which calculates the cooling water quantity to be reduced during the prediction target period in such a manner that the difference between the thermal expansion quantity at the transition time point and the thermal expansion quantity during the prediction target period falls within a prescribed range while cooperating with the roll thermal expansion quantity prediction unit; as well as The variable flow valve adjustment unit adjusts the opening of the variable flow valve so as to reduce the cooling water amount calculated by the cooling water amount reduction calculation unit.

2. A roller cooling control device for cooling the rollers of a rolling mill. The rolling mill comprises: a nozzle for spraying cooling water to the roll; one or more pumps for supplying cooling water to the nozzle; and a variable flow valve capable of changing the flow rate of cooling water supplied from the pump to the nozzle. The roll cooling control device comprises: A rolling / idling prediction unit predicts a rolling period and an idling period in a predetermined prediction target period using the rolling information; a roller thermal expansion amount prediction unit for predicting the thermal expansion amount of the roller during the prediction target period; a cooling water amount reduction calculation unit, which cooperates with the roll thermal expansion amount prediction unit, and calculates the cooling water amount to be reduced during the prediction target period in such a manner that the difference between the thermal expansion amount target value and the thermal expansion amount during the prediction target period falls within a prescribed range, taking the maximum thermal expansion amount of the roll maintained when the maximum cooling water amount is supplied to the nozzle as a thermal expansion amount target value; as well as The variable flow valve adjustment unit adjusts the opening of the variable flow valve so as to reduce the cooling water amount calculated by the cooling water amount reduction calculation unit.

3. The roller cooling control device according to claim 1 or claim 2, wherein: The pump comprises a variable speed pump, The roll cooling control device further includes a variable speed pump adjustment unit that adjusts the rotation speed of the variable speed pump according to the opening degree of the variable flow valve adjusted by the variable flow valve adjustment unit.

4. The roller cooling control device according to claim 1 or claim 2, wherein: A drain valve is provided between the pump and the variable flow valve. The rolling roller cooling control device also includes a drain valve adjustment unit, which adjusts the opening of the drain valve in a manner that reduces the amount of cooling water calculated by the cooling water amount reduction calculation unit when the opening of the variable flow valve is adjusted by the variable flow valve adjustment unit.

5. The roller cooling control device according to claim 1, wherein: The variable flow rate valve adjustment unit is configured to adjust the opening of the variable flow rate valve to a minimum opening when a difference between the thermal expansion amount at the transition time point and the thermal expansion amount during the prediction target period exceeds a predetermined range.

6. The roller cooling control device according to claim 1, wherein: The rolling mill continuously performs rolling with the idling state being shorter than a predetermined time interval. The rolling / idling prediction unit is configured to predict rolling and idling in a second prediction target period which is longer than the prediction target period. During continuous rolling, the cooling water amount reduction calculation unit takes the maximum thermal expansion of the rolling roller maintained when the maximum cooling water amount is supplied to the nozzle as the thermal expansion target value, and calculates the cooling water amount to be reduced during the second prediction object period in such a way that the difference between the thermal expansion target value and the thermal expansion during the prediction object period falls within a specified range.

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