JP2007190597A - Method and device for controlling cooling and device for calculating quantity of cooling water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the deterioration in the shape of a steel sheet which is generated by the difference between cooling rates on upper and back surfaces with high accuracy by rapidly controlling the quantity of the cooling water which is jetted from the upside and underside of the cooling device when the steel sheet is cooled down to the cooling finishing temperature which is predetermined. <P>SOLUTION: By setting a predetermined cooling schedule by calculating temperatures when the steel sheet is passed through the inside of the cooling device on the basis of the measured value with a thermometer on the inlet side of cooling and calculating a necessary cooling condition until the steel sheet is cooled down to a prescribed temperature, a heat transfer coefficient is calculated from a preset temperature and the flow rate of water per unit area in the lower part of cooling. The flow rate of water per unit area in the upper part of cooling is calculated from the calculated heat transfer coefficient, and the quantity of the cooling water of the cooling device is controlled on the basis of a ratio of the flow rate of the water per unit area in the lower part of cooling to the flow rate of the water per unit area in the upper part of cooling. Consequently, the amount of calculation which is necessary to control the quantity of the cooling water which is jetted from the upper and lower surfaces of the cooling device to cool the steel sheet down to the predetermined cooling finishing temperature is simplified. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling control method, a cooling control device, a cooling water amount calculation device, a computer program, and a recording medium in a steel plate manufacturing process, and more particularly to a technique suitable for use in cooling a steel plate immediately after rolling.

  Conventionally, the temperature of the steel plate in the cooling plate is measured, and the amount of cooling water sprayed on the upper and lower surfaces of the steel plate is changed so that the cooling end temperature becomes a desired temperature, so that the difference between the upper surface temperature and the lower surface temperature of the steel plate is changed. There has been proposed a cooling control which is modified so as to prevent the deterioration of the shape of the steel sheet caused by the difference between the upper surface temperature and the lower surface temperature of the steel sheet (see, for example, Patent Document 1).

  Further, in the cooling method described in Patent Document 2, the vertical ratio of the cooling water amount is determined by a coefficient determined from the size of the material to be cooled. By the way, the steel plate temperature during cooling largely depends on the cooling water amount and the heat transfer coefficient. That is, the heat transfer coefficient is a function of the steel sheet surface temperature.

  Therefore, it is not possible to accurately reflect the change in the heat transfer coefficient due to the steel plate temperature state at the start of cooling, which is different for each cooling target, and the change in the steel plate surface temperature during cooling, which changes from moment to moment, in the cooling water amount. For this reason, it was not possible to prevent the deterioration of the shape of the steel sheet with high accuracy only by determining the ratio of the amount of water.

  In order to solve the above problems, in the cooling method described in Patent Document 3, the temperature at the start of cooling is predicted and calculated at the end of rolling, and the heat transfer equation with the calculation result as the initial state is used. Thus, by calculating the surface temperature state and the heat transfer coefficient that change from moment to moment, the water volume ratio that suppresses the deterioration of the shape of the steel plate during cooling is determined with high accuracy.

  However, as described above, the heat transfer coefficient greatly affects the steel sheet temperature at the start of cooling. Therefore, in the cooling method described in Patent Document 3 on the assumption that the cooling start temperature is predicted at the end of rolling, the end of rolling is performed. In the section from the time to the start of cooling, it is affected by various disturbances. For this reason, the amount ratio of water determined at the end of rolling also includes a lot of errors, so that the cooling method described in Patent Document 3 has a problem in that there is a limit in suppressing deterioration of the shape of the steel sheet.

  Therefore, as a technique for simultaneously solving the problems of the cooling methods described in Patent Documents 2 and 3, for example, in the cooling method described in Patent Document 4, the cooling water supply / water ratio is a thermometer installed at the cooling start position. Using the heat transfer equation that takes into account the surface temperature state and the heat transfer coefficient that change from time to time, the water volume ratio that makes the vertical temperature distribution constant is searched and calculated.

Japanese Patent Publication No. 7-41303 JP-A-60-210313 Japanese Patent Publication No. 7-29139 Japanese Patent Laid-Open No. 2-70018

  In the case of the cooling method described in Patent Document 4 described above, it is considered that the water volume ratio can be obtained with high accuracy. However, in the case of this cooling method, since the search by the iterative calculation using the heat transfer equation is performed to obtain the upper / lower ratio of the cooling water amount, the calculation amount becomes enormous. Therefore, there is a problem that it takes a lot of time to obtain a calculation result. As a result, inconvenience that water injection starts after the steel sheet enters the cooling device, or inconvenience that the steel plate must be stopped and waited in front of the cooling device until water injection is started. Since there is a large possibility, the realization was difficult.

  In view of the above-described problems, the present invention quickly controls the amount of cooling water sprayed from the upper and lower surfaces of the cooling device when cooling the steel sheet to a predetermined cooling end temperature, and thus the difference in cooling rate between the upper surface and the lower surface. It aims at preventing the deterioration of the shape of the steel plate generated by the above with high accuracy.

  The cooling control method of the present invention is a cooling control method for cooling a steel plate immediately after rolling with a cooling device, and the temperature when the steel plate passes through the inside of the cooling device is set to the inlet side of the cooling device. A scheduled cooling schedule for setting a scheduled cooling schedule by calculating the cooling conditions necessary for cooling the steel sheet to a predetermined temperature for a plurality of positions inside the cooling device based on the measured value of an installed thermometer A heat transfer coefficient indicating heat transferability from the setting step, the temperature in the planned cooling schedule set by the planned cooling schedule setting step, and the first cooling water density in the cooling water for cooling one side of the steel plate A heat transfer coefficient calculation step for calculating the heat transfer coefficient and a heat transfer coefficient calculated by the heat transfer coefficient calculation step. Based on the up / down ratio calculation step of calculating the cooling water amount density and calculating the up / down ratio of the first cooling water amount density and the second cooling water amount density, and the up / down ratio calculated by the up / down ratio calculation step, A cooling water amount control step for controlling a cooling water amount for cooling the steel sheet passing through the inside of the cooling device.

  The cooling control device of the present invention is a cooling control device for cooling a steel plate immediately after rolling with a cooling device, and the temperature when the steel plate passes through the inside of the cooling device is set to the inlet side of the cooling device. A scheduled cooling schedule for setting a scheduled cooling schedule by calculating the cooling conditions necessary for cooling the steel sheet to a predetermined temperature for a plurality of positions inside the cooling device based on the measured value of an installed thermometer The heat transfer coefficient indicating the heat transferability from the setting means, the temperature in the scheduled cooling schedule set by the scheduled cooling schedule setting means, and the first cooling water amount density in the cooling water for cooling one side of the steel plate A heat transfer coefficient calculation means for calculating the heat transfer coefficient calculated from the heat transfer coefficient calculated by the heat transfer coefficient calculation means. Based on the up / down ratio calculating means for calculating the cooling water amount density and calculating the up / down ratio of the first cooling water amount density and the second cooling water amount density, and the up / down ratio calculated by the up / down ratio calculating means, And cooling water amount control means for controlling the amount of cooling water for cooling the steel sheet passing through the inside of the cooling device.

  The cooling water amount calculation device of the present invention is a cooling water amount calculation device that calculates a cooling water amount necessary for cooling a steel plate immediately after rolling with a cooling device, and the temperature at which the steel plate passes through the inside of the cooling device. Based on the measured value of a thermometer installed on the inlet side of the cooling device, the cooling conditions necessary to cool the steel plate to a predetermined temperature are calculated for a plurality of positions inside the cooling device. From the planned cooling schedule setting means for setting the planned cooling schedule, the temperature in the planned cooling schedule set by the planned cooling schedule setting means, and the first cooling water amount density in the cooling water for cooling one side of the steel sheet, heat A heat transfer coefficient calculating means for calculating a heat transfer coefficient indicating the ease of transmission of the heat transfer coefficient, and the heat transfer coefficient calculated by the heat transfer coefficient calculating means And an up / down ratio calculating means for calculating a second cooling water amount density in the cooling water for cooling the first cooling water and calculating an up / down ratio between the first cooling water amount density and the second cooling water amount density. .

  A computer program according to the present invention causes a computer to execute the cooling control method described above.

  The recording medium of the present invention records the computer program described above.

  According to the present invention, the temperature when the steel sheet passes through the inside of the cooling device is cooled to the predetermined temperature based on the measured value of the thermometer installed on the entry side of the cooling device. The cooling condition necessary for the calculation is calculated for a plurality of positions inside the cooling device to set a scheduled cooling schedule, and the temperature in the set scheduled cooling schedule and the first cooling water amount in the cooling water for cooling one side of the steel plate A heat transfer coefficient indicating the ease of heat transfer is calculated from the density, and from the calculated heat transfer coefficient, a second cooling water amount density in the cooling water for cooling the opposite surface of the steel sheet is calculated, and the first Since the amount of cooling water for cooling the steel sheet passing through the inside of the cooling device is controlled based on the vertical ratio of the cooling water amount density and the second cooling water amount density, the steel is heated to a predetermined cooling end temperature. To cool the can simplify the calculation amount required for controlling the amount of cooling water injected from the upper and lower surfaces of the cooling device. As a result, the time required to obtain the required calculation result can be greatly shortened, so that the period from when the temperature of the steel sheet is measured until when the cooling is actually started can be greatly shortened. Therefore, it becomes possible to install the inlet-side thermometer immediately before the cooling device, to realize cooling with a small error in the water volume ratio, and to suppress deterioration of the steel plate shape.

(First embodiment)
Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows an example of a steel sheet production line to which the present invention is applied.
As shown in FIG. 1, a finishing mill 2 that rolls a steel plate 1 that is roughly formed through a heating furnace or a roughing mill (not shown) to a target plate thickness, and a straightening machine that corrects the shape of the steel plate 1 after finish rolling. 3 and a cooling device 4 for accelerating and cooling the straightened steel plate 1 are sequentially disposed, and the steel plate 1 after the accelerated cooling becomes a product having a desired shape and material.

  A finishing front surface thermometer 5 is disposed on the entry side of the finishing mill 2, and a finishing delivery thermometer 6 is disposed on the exit side. A cooling inlet thermometer 7 is disposed on the inlet side of the cooling device 4. In the present embodiment, each thermometer can measure the temperature of the upper surface and the lower surface of the steel plate 1.

  FIG. 2 is a diagram illustrating an internal configuration example of the cooling device 4. A large number of roller groups 41 for conveying the steel plate 1 are arranged inside the cooling device 4, and nozzle groups (not shown) for injecting cooling water onto the upper and lower surfaces of the steel plate 1 in each of the cooling zones 1Z to 19Z. Many are arranged. The cooling water sprayed from these nozzle groups is configured so that the flow rate is controlled by a flow control valve, and the number of zones used and the spray amount from each nozzle are determined according to various conditions such as the thickness and length of the steel plate. Can be adjusted. In the present embodiment, a cooling inlet thermometer 7 is disposed on the inlet side of the cooling device 4.

  FIG. 3 is a block diagram showing a schematic configuration of a control system including the cooling water amount calculation apparatus 100 of the present embodiment. The cooling water amount calculation device 100 outputs the rolling control device 200 that performs overall control of each rolling mill including the finish rolling mill 2, the production management device 300 that mainly performs production management, and the cooling water amount calculation device 100. A data input / output device 400 for displaying various data and outputting an input from an operator to the cooling water amount calculation device 100 and the cooling inlet side thermometer 7 are connected.

  Further, the cooling water amount calculation device 100 is connected to a cooling water amount control device 500 that controls the flow rate control valve 501 in each of the cooling zones 1Z to 19Z of the cooling device 4 to control the cooling water amount.

  That is, the cooling water amount calculation device 100 controls the cooling water amount control device 500 based on data input from the cooling inlet side thermometer 7, the rolling control device 200, the production management device 300, the data input / output device 400, and the like. Calculate the amount of cooling water.

  In particular, the cooling water amount calculation apparatus 100 according to the present embodiment determines the water injection amount of the cooling device 4 by transmitting data related to the required cooling water amount to the cooling water amount control device 500 while conveying the steel sheet 1 after finish rolling. To do.

  More specifically, the cooling water amount calculation device 100 of the present embodiment includes a scheduled cooling schedule setting unit 101 that sets a scheduled cooling schedule of the steel sheet 1 by the cooling device 4 according to the target cooling end temperature information, and the cooling device 4. The heat transfer coefficient calculation unit 102 that acquires the heat transfer coefficient at a predetermined part of the steel sheet 1 on the entry side, and the planned cooling schedule and the heat transfer coefficient reach calculation unit 102 set by the planned cooling schedule setting unit 101 are acquired. Based on the heat transfer coefficient, an upper / lower ratio calculation unit 103 that calculates a water density density ratio between the upper surface and the lower surface to be reflected in the cooling water amount control device 500 is provided.

FIG. 4 is a flowchart illustrating an example of a procedure for determining the cooling water amount by the cooling water amount calculation apparatus 100 in the present embodiment.
In step S <b> 401, the scheduled cooling schedule setting unit 101 sets a scheduled cooling schedule for the steel sheet 1 by the cooling device 4. Specifically, the surface temperature of the steel plate 1 measured by the cooling inlet side thermometer 7 is measured, and a process for obtaining the temperature distribution in the plate thickness direction at each segment immediately before cooling is performed.

It is known that the temperature distribution in the plate thickness direction has a parabolic shape in which the temperature is highest at an intermediate position in the plate thickness direction. Further, as a method for obtaining the temperature distribution in the plate thickness direction from the surface temperature, for example, the temperature distribution at 11 points in the plate thickness direction can be determined using the method disclosed in Patent Document 1 (see FIG. 7). In brief, the upper surface temperature _TF is a measured temperature. The temperature difference ΔT between the upper surface and the plate temperature maximum is expressed by the following equation (1)
ΔT = 33.8−3.63h (−0.0371 + 0.00528h) · T _F (1)
Where ΔT: temperature difference between the upper surface and the plate temperature maximum point, and h: plate thickness.
The lower surface temperature T _L is expressed by the following formula (2)
T _L = T _F + K ₁ ξ (ΔT _S con + ΔT _S class) + K ₂ (2)
Where ξ: temperature conversion coefficient obtained by learning, ΔT _S : entrance side temperature upper / lower surface temperature difference obtained by learning, K ₁ , K ₂ : determined by adjustment factors. A radial temperature distribution satisfying the above conditions is determined, and a temperature distribution in the thickness direction is determined.

Then, the temperature distribution in the plate thickness direction in each segment immediately before cooling is set as an initial value, and the plate thickness direction described above is divided into appropriate lengths based on desired control accuracy (for example, 11 points). The temperature transition up to the cooling start position of the cooling device 4 is solved as a point, and the heat conduction difference equation is solved to obtain the plate thickness direction average temperature Tsk * (hereinafter referred to as “cooling start temperature” at each segment at the cooling start position of the cooling device 4. It is referred to as “Tsk *.” K is a thickness direction index) and is calculated as cooling start temperature information. As for the technique for analyzing the temperature transition by solving the differential equation of heat conduction, for example, as disclosed in Patent Document 1, the outline will be described based on the initial temperature distribution state in the thickness direction. Using 11 points in the representative points as calculation target points, the one-dimensional heat conduction difference equation Q (j) _t + Δ _t shown in the following equation (3)
= Q (j) _t + Δt · (λ _{j + 1} −2λ _j + λ _j−1 ) / ρ · Δx ² (j = 1 to 11),
ΔQ _s
= 4.88 [[(Tg + 273) / 100] ⁴ -[(T (j) +273) / 100] ⁴ ]
(J = 1, 11)
= 0 (j = 2 to 10) (3)
Where Q (j) _t : heat content of element j at time t, T (j): same temperature display, Δt: difference calculation step time (= const, 150 msec), ρ: density, λ: element j Thermal conductivity, Tg: temperature, ΔQ _s : boundary condition, Δx: plate thickness division thickness is solved. In this case, the conversion from the plate temperature T to the heat content Q is
If T> 880, Q = 3.333 + 0.16T,
If T ≦ 880, Q = −149.05 + 0.481 · T−1.68 × 10 ⁻⁴ · T ² , conversion from heat content Q to temperature T (heat content: specific heat from 0 ° C. to T Integrated value)
If Q> 144.13, T = −20.8 + 6.25 × Q,
If 0 <Q ≦ 144.13, T = 1431.5−√ (1.162 × 10 ₆ −5.95 × 10 ³ × Q).

  And the scheduled cooling schedule setting part 101 calculates and sets the passage time (TMz) and the estimated cooling temperature (Tsk) of each zone based on the cooling plate speed in each zone (1Z-19Z). Here, the predicted cooling temperature (Tsk) indicates the incoming temperature in one area divided into several in each zone, as shown in FIG.

  The cooling plate speed is given as a set of data on the position of the front end of the plate and the conveyance speed by the method described in Patent Document 1. As shown in FIG. 8, if the position of the front end of the plate is x and the conveying speed at this time is V (x), k point at the inlet of the cooling device at that time on the plate, in other words, x rearward from the front end of the plate. The water cooling time at

Given in.
Next, the water cooling times t _t , t _m , and t _b of the tip, center, and end are obtained by the following equations.

L: plate length, V (x) = 1 / (ax ² + bx + c), and a, b, c are obtained by substituting into the above three equations.

The acceleration range (defined region of x) is determined as follows.
0 ≦ x ≦ L + lzone + Δlc ₂ ,
L: Plate length, lzone: Effective cooling zone length, Δlc ₂ : Coexistence (= const).

  As described above, x is appropriately determined within the determined acceleration range and substituted into the equation of V (x) to create the position of the front end of the plate and the conveyance set (speed pattern) at that time. Then, the calculation result is output to a sheet feeding speed control device (not shown).

  The acceleration rate is obtained in this manner because the steel plate 1 is cooled while being transported, so that the time at which the cooling device 4 is entered differs between the steel plate front end portion and the end portion. That is, since the cooling start temperature differs along the longitudinal direction of the steel sheet, the temperature after cooling differs between the front end and the end, and the plate passing speed is set to the end in order to make the product material uniform over the entire length. This is because correction is made by increasing the speed toward the part. As described above, the cooling schedule up to the cooling end target temperature is acquired.

  Next, in step S402, the heat transfer coefficient calculation unit 102 selects a reference water amount density corresponding to the calculation target zone Z from each zone reference water amount density, and substitutes it into the cooling lower water amount density (WDLi). Here, as a method of determining the reference water amount density of each zone, for example, a method of determining by a value transmitted from a business computer as shown in Patent Document 1 can be used.

  Next, in step S403, the heat transfer coefficient calculation unit 102 calculates the heat transfer difference using the predicted cooling temperature (Tsk) as an initial value to calculate the steel plate back surface temperature (TLi). Here, the value of Tsk in the first iteration calculation in the zone 1Z is “cooling start temperature Tsk *”, and otherwise, the result of the iteration calculation is Tsk. And lower heat transfer coefficient ((alpha) Li) is calculated | required from the calculated cooling lower water volume density (WDLi) and steel plate back surface temperature (TLi). The steel plate back surface temperature (TLi) can be calculated as j = 11 when Patent Document 1 described above is taken as an example.

FIG. 10 is a characteristic diagram showing the cooling temperature transition in the present embodiment.
As shown in FIG. 10, the steel plate back surface temperature (TLi) indicates, for example, the entry-side back surface temperature in one iteration in the zone 1Z. When calculating the steel plate back surface temperature (TLi), the heat conduction difference calculation is performed with the cooling predicted temperature (Tsk) as an initial value, and the steel plate back surface temperature (TLi) is calculated by each iteration.
A method of calculating the lower heat transfer coefficient (αLi) will be described later in detail with reference to FIG.

The heat transfer coefficient (α) is generally a nonlinear function determined from the water density WD (m ³ / (m ² · min)) and the surface temperature Ts, and various formulas have been proposed. For example, the following formula has been proposed.
Log (α) = A + B * Log (WD) + C * Ts + D (4)
Since the heat transfer coefficient (α) varies depending on the difference in the boiling form of water, the coefficients A, B, C, and D in the expression (4) are divided into the coefficients according to the surface temperature as follows. It is common to do.
Ts ≧ K1 → A1, B1, C1, D1,
Ts <K1 → A2, B2, C2, D2,
Moreover, since it is common for the upper surface and the lower surface to have a difference in the retention state of the cooling water, it is common to divide the coefficients. Therefore, in the example employing the basic formula (4), the heat transfer coefficient is calculated by properly using the following coefficient sets. For example, for the coefficient for calculating the upper heat transfer coefficient:
Ts _U ≧ K1 _U → A1 _U , B1 _U , C1 _U , D1 _U ,
Ts _U <K1 _U → A2 _U , B2 _U , C2 _U , D2 _U ,
And For the coefficient for calculating the lower heat transfer coefficient,
Ts _L ≧ K1 _L → A1 _L , B1 _L , C1 _L , D1 _L ,
Ts _L <K1 _L → A2 _L , B2 _L , C2 _L , D2 _L ,
And Based on the above-described concept, FIG. 5 will be described.

FIG. 5 is a characteristic diagram showing the relationship between the steel plate back surface temperature and the lower heat transfer coefficient in the present embodiment.
FIG. 5 shows a curve indicating the relationship between the steel plate back surface temperature and the heat transfer coefficient when WDLi = 0.3, 0.8, and 2.0.

  For example, in the case of WDLi = 0.8, when the value of the steel plate back surface temperature (TLi) is calculated, the Y component (αLi) at the coordinates 501 on the curve corresponding to WDLi = 0.8 can be obtained. A plurality of curve patterns that differ depending on the numerical value of the cooling lower water density (WDLi) are stored in advance, and when the calculated cooling lower water density (WDLi) curve pattern is not stored, the curve having the closest numerical value is stored. Calculate using patterns. Therefore, it is desirable to store a large number of curve patterns in order to increase calculation accuracy.

  Next, in step S404, the top / bottom ratio calculation unit 103 calculates the cooling upper water density (WDUi) using the lower heat transfer coefficient (αLi) calculated in step S403, and the appropriate top / bottom ratio in the iteration. (Ηi) is calculated.

Next, a method for calculating the cooling water density (WDUi) will be described with reference to FIG.
FIG. 6 is a diagram showing the relationship between the steel sheet surface temperature (TUi) and the upper heat transfer coefficient (αUi) in the present embodiment.
In this embodiment, a curve passing through coordinates 601 such that the steel sheet surface temperature (TUi) = steel sheet back surface temperature (TLi) and the upper heat transfer coefficient (αUi) = lower heat transfer coefficient (αLi) is searched, The cooling water density (WDUi) is obtained. A plurality of cooling upper water density (WDUi) curve patterns are stored in the same manner as the cooling lower water density (WDLi) curve pattern. If the corresponding curve pattern is not stored, the cooling upper water density (WDUi) is stored. ) Directly.

Next, a method for calculating the cooling upper water density (WDUi) will be described with reference to FIGS. 9 and 11.
FIG. 9 is a diagram illustrating a method for searching for the cooling upper water density (WDUi) in the present embodiment.
As shown in FIG. 9, the cooling upper water density (WDUi) in which the upper heat transfer coefficient (αUi) is the same as the lower heat transfer coefficient (αLi) is searched and calculated while changing the cooling water quantity density WDU.

FIG. 11 is a flowchart illustrating a procedure in which the top / bottom ratio calculation unit 103 calculates the cooling upper water density (WDUi) in the present embodiment.
In step S1101, it is determined whether or not the upper standard heat transfer coefficient (α ₀ ) matches the lower heat transfer coefficient (αLi). Here, the upper standard heat transfer coefficient (α ₀ ) is a non-reference surface heat transfer coefficient corresponding to the standard water density (WDU ^* ), and is calculated by the above-described equation (4). The standard water density (WDU ^* ) is stored as data in advance.

As a result of this determination, if they match, WDUi = WDU ^* and the calculation ends. On the other hand, if they do not match as a result of the determination in step S1101, it is determined in step S1102 whether the upper standard heat transfer coefficient (α ₀ ) is larger than the lower heat transfer coefficient (αLi). As a result of the determination, if the upper standard heat transfer coefficient (α ₀ ) is larger than the lower heat transfer coefficient (αLi), the process jumps to step S1106. On the other hand, if the result of determination in step S1102 is that the upper standard heat transfer coefficient (α ₀ ) is smaller than the lower heat transfer coefficient (αLi), the process proceeds to step S1103.

Next, in step S1103, 1 is added to k (when proceeding from step S1102, k = 0 is set) to calculate WDU _{k + 1} = WDU _k + ΔW _k (k ≧ 0). Where WDU _k and ΔW _k are
ΔW _k = | WDU _k −WDU _k−1 | / 2 (k ≧ 1),
WDU ₀ = WDU ^* , ΔW ₀ = S (S: constant),
And

Next, in step S1104, it is determined whether or not the heat transfer coefficient (α _{k + 1} ) corresponding to WDU _{k + 1} calculated in step S1103 matches the lower heat transfer coefficient (αLi). As a result of this determination, if they match, WDUi = WDU _{k + 1} and the calculation ends. On the other hand, if they do not match as a result of the determination in step S1104, it is determined in step S1105 whether the calculated heat transfer coefficient (α _{k + 1} ) is larger than the lower heat transfer coefficient (αLi).

As a result of the determination, if the calculated heat transfer coefficient (α _{k + 1} ) is smaller than the lower heat transfer coefficient (αLi), the process returns to step S1103, 1 is added to k, and the same calculation is performed again. On the other hand, if the result of determination in step S1105 is that (α _{k + 1} ) is greater than (αLi), the process proceeds to step S1106.

Next, in step S1106, 1 is added to k (when proceeding from step S1102, k = 0 is set), and WDU _{k + 1} = WDU _k −ΔW _k (k ≧ 0) is calculated. In step S1107, it is determined whether or not the heat transfer coefficient (α _{k + 1} ) corresponding to WDU _{k + 1} calculated in step S1106 matches αLi. As a result of this determination, if they match, WDUi = WDU _{k + 1} and the calculation ends. On the other hand, as a result of the determination in step S1107, if they do not match, it is determined in step S1108 whether α _{k + 1} is smaller than αLi.

As a result of the determination, if the calculated heat transfer coefficient (α _{k + 1} ) is larger than the lower heat transfer coefficient (αLi), the process returns to step S1106, 1 is added to the value k, and the same calculation is performed again. Do. On the other hand, if the result of determination in step S1108 is that (α _{k + 1} ) is smaller than (αLi), the process proceeds to step S1103, 1 is added to the value k, and the calculation is performed again in the same manner. As described above, the calculation is repeated until the calculated heat transfer coefficient (α _{k + 1} ) matches the lower heat transfer coefficient (αLi).

  In the present embodiment, when cooling is started in the cooling device 4, the steel plate surface temperature (TUi) = the steel plate back surface temperature (assuming that the steel plate surface temperature and the steel plate back surface temperature are substantially the same. Calculation is performed as TLi). However, for example, in the stage before cooling by the cooling device 4, an error may occur between the steel plate surface temperature and the steel plate back surface temperature by calculating the above-described heat conduction difference equation. In this case, for zone 1Z, the heat conduction difference equation may be calculated as j = 1, and this calculated numerical value may be taken into consideration for fine adjustment.

  Then, by calculating the cooling upper water density (WDUi), the appropriate upper / lower ratio of the iteration is calculated. The proper top / bottom ratio (ηi) is ηi = WDUi / WDLi.

  Next, in step S405, the top / bottom ratio calculation unit 103 determines whether or not the iteration has been completed for one zone. If the result of this determination is not complete, processing returns to step S403 and the calculation is repeated again. On the other hand, if the result of determination in step S <b> 405 is ended, the process proceeds to next step S <b> 406.

  The number of iterations can be arbitrarily set. However, when the elapsed time (ETM) is calculated by multiplying the number of iterations (I) by one iteration time (TM *), ETM => The number of iterations is determined so as to be TMz.

  Next, in step S406, the up / down ratio calculation unit 103 calculates an average value (AVE (ηi)) of the appropriate up / down ratio (ηi) of each iteration, and finally calculates the average value as the zone appropriate up / down ratio (ηz). ).

  Next, in step S407, the heat transfer coefficient calculation unit 102 determines whether or not there is a next zone that has not been calculated. If the result of this determination is that there is a next zone, processing returns to step S402, and calculation is performed again to calculate the zone appropriate up / down ratio (ηi) for the next zone. On the other hand, if the result of determination in step S407 is that there is no next zone, processing proceeds to next step S408.

  When calculation of all zone appropriate up / down ratios is completed, the cooling water amount calculation device 100 transmits data of all zone appropriate up / down ratios (ηz) to the cooling water amount control device 500, and the cooling water amount control device 500 transmits the data to the data. Based on this, the flow control valve 501 of the cooling device 4 is adjusted so that the cooling water flows to each nozzle. Thereby, in this embodiment, before the front-end | tip part of the steel plate 1 enters into the cooling device 4, it can be made to flow the cooling water in all the zones.

  In step S <b> 408, the scheduled cooling schedule setting unit 101 determines whether or not the portion whose temperature has been measured by the cooling entry-side thermometer 7 is the end portion of the steel plate 1. If the result of this determination is the end portion of the steel plate 1, all processing is terminated. On the other hand, as a result of the determination in step S408, if it is not the end portion of the steel plate 1, the process returns to step S401, and a new cooling schedule is acquired for the next portion in the steel plate 1.

  As described above, in order to make the product material of the steel plate 1 uniform over the entire length, the plate passing speed is increased toward the end portion. For this reason, the cooling schedule of the steel plate 1 differs depending on the position of the steel plate 1. Therefore, in this embodiment, the steel sheet 1 is divided into a plurality of parts, and a cooling schedule is acquired for each part.

  In the present embodiment, as described above, since the cooling upper water density (WDUi) and the cooling lower water density (WDLi) are determined, in order to cool the steel sheet 1 to a predetermined cooling end temperature, The amount of calculation required to control the amount of cooling water sprayed from the upper and lower surfaces of the cooling device 4 can be simplified. Thereby, before the front-end | tip part of the steel plate 1 enters into the cooling device 4, a cooling water can be made to flow in all the zones 1Z-19Z, and the deterioration of a steel plate shape can be suppressed to the minimum.

(Other embodiments according to the present invention)
Specifically, the cooling water amount calculation device 100 of the above-described embodiment is configured by a computer device or a computer system including a CPU, a RAM, a ROM, and the like. Accordingly, the present invention includes a computer program itself installed in a computer in order to realize each function processing of the present invention.

  Moreover, the said embodiment is only what showed the specific example in implementing this invention, and the technical scope of this invention should not be limitedly interpreted by these. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

It is a figure which shows an example of the steel plate manufacturing line in the 1st Embodiment of this invention. In the 1st Embodiment of this invention, it is a figure which shows the internal structural example of a cooling device. In the 1st Embodiment of this invention, it is a block diagram which shows the schematic structural example of the control system containing a cooling water amount calculation apparatus. It is a flowchart which shows an example of the procedure which determines a cooling water amount by the cooling water amount calculation apparatus of the 1st Embodiment of this invention. In the 1st Embodiment of this invention, it is a figure which shows the relationship between steel plate back surface temperature and a lower heat transfer coefficient. In the 1st Embodiment of this invention, it is a figure which shows the relationship between a steel plate surface temperature and an upper heat transfer coefficient. It is a figure which shows the temperature distribution of 11 thickness direction. It is a figure which shows the position of the steel plate which has passed the cooling device. In the 1st Embodiment of this invention, it is a figure which shows the method of searching a cooling water quantity density. In the 1st Embodiment of this invention, it is a characteristic view which shows an example of cooling temperature transition. It is a flowchart which shows an example of the procedure in which the up-down ratio calculation part of the 1st Embodiment of this invention calculates cooling upper water density.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Finishing mill 3 Straightening machine 4 Cooling device 5 Finishing side thermometer 6 Finishing side thermometer 7 Cooling inlet side thermometer 41 Roller group 100 Cooling water amount calculation apparatus 101 Schedule cooling schedule setting part 102 Heat transfer coefficient calculation part 103 top / bottom ratio calculation unit 200 rolling control device 300 production management device 400 data input / output device 500 cooling water amount control device 501 flow control valve

Claims (11)

A cooling control method for cooling a steel plate immediately after rolling with a cooling device,
Cooling required to cool the steel plate to a predetermined temperature based on the measured value of a thermometer installed on the inlet side of the cooling device, when the steel plate passes through the inside of the cooling device. A planned cooling schedule setting step for calculating a condition for a plurality of positions inside the cooling device and setting a planned cooling schedule;
Heat for calculating a heat transfer coefficient indicating ease of heat transfer from the temperature in the scheduled cooling schedule set by the scheduled cooling schedule setting step and the first cooling water density in the cooling water for cooling one side of the steel sheet. A transfer coefficient calculation process;
From the heat transfer coefficient calculated by the heat transfer coefficient calculation step, a second cooling water amount density in the cooling water for cooling the opposite surface of the steel sheet is calculated, and the first cooling water amount density and the second cooling water amount are calculated. An up / down ratio calculating step for calculating an up / down ratio with density;
A cooling control method comprising: a cooling water amount control step for controlling a cooling water amount for cooling the steel sheet passing through the inside of the cooling device based on the top / bottom ratio calculated by the top / bottom ratio calculation step. The first cooling water amount density is a cooling water amount density of cooling water for cooling the lower side of the steel plate,
2. The cooling control method according to claim 1, wherein the second cooling water amount density is a cooling water amount density of cooling water for cooling the upper side of the steel plate.   The top / bottom ratio calculating step calculates the top / bottom ratio of the cooling water amount density at a plurality of positions inside the cooling device based on the cooling schedule set by the scheduled cooling schedule setting step. The cooling control method according to 2.   The cooling control method according to any one of claims 1 to 3, wherein the first cooling water amount density is determined based on a cooling schedule set by the scheduled cooling schedule setting step. A cooling control device for cooling a steel plate immediately after rolling with a cooling device,
Cooling required to cool the steel plate to a predetermined temperature based on the measured value of a thermometer installed on the inlet side of the cooling device, when the steel plate passes through the inside of the cooling device. A planned cooling schedule setting means for calculating a condition for a plurality of positions inside the cooling device and setting a planned cooling schedule;
Heat for calculating a heat transfer coefficient indicating ease of heat transfer from the temperature in the scheduled cooling schedule set by the scheduled cooling schedule setting means and the first cooling water amount density in the cooling water for cooling one side of the steel plate. A transmission coefficient calculation means;
From the heat transfer coefficient calculated by the heat transfer coefficient calculating means, a second cooling water amount density in the cooling water for cooling the opposite surface of the steel sheet is calculated, and the first cooling water amount density and the second cooling water amount are calculated. An up / down ratio calculating means for calculating an up / down ratio with density;
A cooling control device comprising cooling water amount control means for controlling an amount of cooling water for cooling the steel sheet passing through the inside of the cooling device based on the upper / lower ratio calculated by the upper / lower ratio calculating means. The first cooling water amount density is a cooling water amount density of cooling water for cooling the lower side of the steel plate,
The cooling control device according to claim 5, wherein the second cooling water amount density is a cooling water amount density for cooling the upper side of the steel plate.   The said down / up ratio calculation means calculates the up / down ratio at a plurality of positions inside the cooling device based on the cooling schedule set by the scheduled cooling schedule setting means. Cooling control device.   The cooling control apparatus according to any one of claims 5 to 7, wherein the first cooling water amount density is determined based on a cooling schedule set by the scheduled cooling schedule setting means. A cooling water amount calculation device for calculating a cooling water amount necessary for cooling a steel plate immediately after rolling with a cooling device,
Cooling required to cool the steel plate to a predetermined temperature based on the measured value of a thermometer installed on the inlet side of the cooling device, when the steel plate passes through the inside of the cooling device. A planned cooling schedule setting means for calculating a condition for a plurality of positions inside the cooling device and setting a planned cooling schedule;
Heat for calculating a heat transfer coefficient indicating ease of heat transfer from the temperature in the scheduled cooling schedule set by the scheduled cooling schedule setting means and the first cooling water amount density in the cooling water for cooling one side of the steel plate. A transmission coefficient calculation means;
From the heat transfer coefficient calculated by the heat transfer coefficient calculating means, a second cooling water amount density in the cooling water for cooling the opposite surface of the steel sheet is calculated, and the first cooling water amount density and the second cooling water amount are calculated. A cooling water amount calculation device comprising an upper / lower ratio calculating means for calculating an upper / lower ratio with respect to the density.   A computer program for causing a computer to execute the cooling control method according to any one of claims 1 to 4.   A computer-readable recording medium on which the computer program according to claim 10 is recorded.

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