JP3946733B2 - Shape control method and shape control apparatus in rolling mill - Google Patents

Description

  The present invention relates to a shape control method and a shape control device in a rolling mill, and in particular, controls the spraying of a cooling medium to the work roll and adjusts the thermal crown of the work roll to control the plate shape in the obtained rolled material. The present invention relates to a cooling control technology.

  When rolling aluminum and the like, in order to stably obtain the target plate shape, the plate shape of the rolled material is measured by measuring the distribution of the rolled material in the width direction and the stretched state of the rolled material. The shape control is performed so that the actually measured plate shape approaches the target plate shape. As such shape control, in general, mechanical control such as a work roll bender, an intermediate roll bender, and a reduction level is performed, and simple and large shape correction such as ear elongation, middle elongation, and half elongation of a rolled material is performed. In addition, in order to correct local elongation or complex elongation, which is difficult to be corrected by such mechanical control, the cooling medium spraying on the work roll is controlled to change the thermal crown of the work roll (the amount of change in the roll radial direction). Cooling control (also referred to as coolant control) for adjusting the axial distribution) is performed.

  By the way, various methods have been proposed and implemented for cooling control for the purpose of shape control. Among them, as one of typical cooling control methods, there is a method for determining ON or OFF of cooling medium spraying based on the deviation between the actual shape and the target shape at the present time. In Kaihei 9-99307), a plate for controlling the thermal expansion of the rolling roll by turning on and off a plurality of coolants that zone-cool the rolling roll along the sheet width direction, thereby controlling the plate shape of the rolled material. In the roll coolant control method of the rolling mill, find the deviation between the actual rolling material shape data and the target shape, and if the deviation can be ignored, keep the coolant on, and if the deviation cannot be ignored The deviation of the deviation is selected from a plurality of on / off patterns set in a stepwise manner by combining an off time of a maximum of 2.5 seconds and an on time of a maximum of 10 seconds. Roll coolant control method of a plate rolling mill, characterized by on-off controlling each coolant accordance off pattern selected depending on the case have been proposed.

  However, as proposed in Patent Document 1, the method for ON / OFF control of the cooling medium spraying based on the deviation between the actual shape and the target shape at the present time is simple feedback control. , Because it is not possible to cope with the deviation between the predicted shape and the target shape in the future in advance, the problem is that the response is delayed and overshoot is likely to occur, and it is difficult to sufficiently improve and stabilize the control accuracy was there. In addition, depending on the deviation obtained from the shape data of the actual rolled material and the target shape, the number of times of switching on / off the cooling medium spraying increases more than necessary, and in some cases, an unnecessary switching operation may occur. there were. Such frequent switching of the ON / OFF operation is a factor that shortens the life of a switching valve or the like in the cooling medium spraying device, and there is a problem that the equipment maintenance cost increases.

  On the other hand, the present inventors, in Patent Document 2 (Japanese Patent Laid-Open No. 8-90033), predict the shape of the rolled material in the future from the rolling situation and the like as a new method to replace the conventional cooling control described above, and take A method of controlling the cooling medium spraying based on the deviation between the predicted shape and the target shape is proposed. That is, in Patent Document 2, the plate shape of the rolled material after a unit time has been predicted and obtained based on the actual measured value of the plate shape of the rolled material at the current time and the spraying state of the cooling medium on the work roll. Further, there is disclosed a shape control method in a rolling mill characterized by controlling a spraying state of a cooling medium based on a deviation (predicted shape deviation) between a predicted plate shape and a target plate shape. Thus, in the cooling control previously proposed by the present inventors, predict the shape of the rolled material after a unit time has elapsed, so that the deviation between the predicted shape and the target shape is minimized, Since it controls the spraying of the cooling medium, the control performance is effectively improved compared with the conventional method of controlling the spraying of the cooling medium based only on the current shape deviation. Yes.

  However, the control method previously proposed by the present inventors as described above obtains the predicted shape deviation when the cooling medium spraying is turned on and the predicted shape deviation when the cooling medium spraying is turned off. Based on only the magnitude relationship between the two types of predicted shape deviations obtained, the cooling medium spraying is determined to be ON or OFF, and the predicted shape deviation is a value that does not cause any practical problems. Even if it is, the spraying of the cooling medium can be switched depending on the magnitude of the value. Even in the control method proposed by the present inventors, the spraying of the cooling medium is controlled based on the actual result shape etc. As in the conventional method, there is a risk of causing an unnecessary switching operation in the cooling medium spraying device.

JP-A-9-99307 JP-A-8-90033

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is that, in the obtained rolled material, the deviation from the target shape does not become a practical problem. The present invention relates to a shape control method and a shape control apparatus in a rolling mill that can advantageously suppress the occurrence of unnecessary ON / OFF operations in a cooling medium spraying apparatus while controlling to a degree.

  And in order to solve this subject, this invention performs ON / OFF control at the time of each control set at the time of rolling start and every unit time passage after that, for blowing of the cooling medium with respect to the work roll of a rolling mill. When controlling the plate shape of the obtained rolled material, the plate shape of the rolled material is predicted at the time of the next control after elapse of unit time in one control, and the predicted plate shape and the target plate shape Is a shape control method in a rolling mill that determines whether or not cooling medium spraying is turned on or off at the time of the one control based on a deviation from the above, and when cooling medium spraying is turned on at the time of the one control While predicting the plate shape of the rolled material at the time of the next control, and obtaining the predicted shape deviation 1 from the predicted plate shape and the target plate shape, Predicting the plate shape of the rolled material at the time of the next control when the soldering state is OFF, obtaining a predicted shape deviation 2 from the predicted plate shape and the target plate shape, the predicted shape deviation 1 and the When each absolute value of the predicted shape deviation 2 is compared with a predetermined threshold, and the absolute values of the predicted shape deviation 1 and the predicted shape deviation 2 are equal to or less than the threshold, the one control time In the present invention, the gist of the shape control method in the rolling mill is characterized in that the cooling medium spray ON or OFF determined in the immediately preceding control is maintained as it is.

  Further, the present invention provides a sheet of rolled material obtained by ON / OFF control of cooling medium spraying on a work roll of a rolling mill at each control set at the start of rolling and every subsequent unit time. When controlling the shape, in one control, predict the plate shape of the rolled material at the next control after elapse of unit time, based on the deviation between the predicted plate shape and the target plate shape, A shape control device in a rolling mill that determines whether or not cooling medium spraying is ON or OFF at the time of one control, (a) at the time of the next control when the cooling medium spraying is ON at the time of the one control. Predicting the plate shape of the rolled material in step 1, and calculating the predicted shape deviation 1 from the predicted plate shape and the target plate shape, and (b) at the time of the one control And calculating the predicted shape deviation 2 from the predicted plate shape and the target plate shape by predicting the plate shape of the rolled material in the next control when the cooling medium spraying is turned off. (C) a comparison between the absolute value of the predicted shape deviation 1 obtained by the first computing means and a predetermined threshold value, and the predicted shape deviation 2 obtained by the second computing means A comparison means for comparing the absolute value with the threshold value; and (d) based on the comparison result of the comparison means, the absolute value of the predicted shape deviation 1 and / or the absolute value of the predicted shape deviation 2 is the threshold value. In the case of exceeding one, the ON / OFF of the cooling medium spraying is determined so that the predicted shape deviation becomes smaller during the one control, while the absolute value of the predicted shape deviation 1 and the predicted shape deviation 2 are determined. When the absolute values are both within the threshold value, there is provided a determining unit that maintains ON or OFF of the cooling medium spraying determined in the immediately preceding control in the one control. The shape control apparatus in the rolling mill characterized by this is also the gist thereof.

  As described above, in the shape control method in the rolling mill according to the present invention, the predicted shape deviation (predicted shape) at the next control time when the cooling medium spraying is turned ON and when the cooling medium spraying is turned OFF in one control. When the absolute values of the predicted shape deviations 1 and 2 are within a predetermined threshold, the cooling medium spraying determined during the immediately preceding control is performed during the one control. Since the deviation between the shape of the obtained rolled material and the target shape is kept within the threshold value, unnecessary ON / OFF operation occurs in the cooling medium spraying device. Can be advantageously suppressed, so that the durability of the spraying device is advantageously improved.

  Further, according to the shape control device having the structure according to the present invention, the cooling control according to the above-described method of the present invention can be advantageously performed.

  Hereinafter, in order to clarify the present invention more specifically, a shape control method and a shape control apparatus according to the present invention will be described in detail with reference to the drawings as appropriate.

  First, in FIG. 1, a shape control system provided with a shape control device according to the present invention is schematically shown by a partial block diagram. The shape control system shown therein is a case where the present invention is applied as shape control in a cold rolling mill, but the present invention is similarly applied to shape control in a hot rolling mill. It goes without saying that it can be applied.

  In FIG. 1, a rolling mill 10 is a general single-stand type four-high rolling mill, and a pair of work rolls 12a and 12b and a pair of backup rolls 14a and 14b positioned between them from above and below. And is composed of. Although not shown in FIG. 1, the purpose is to impart bending action to each roll at both ends in the axial direction of the work rolls 12a and 12b and the backup rolls 14a and 14b and to provide appropriate crowns during rolling. Each of the roll bending apparatuses is installed.

  Further, on the entry side (lower right side in FIG. 1) of the rolled material 16, coolant devices 18 a and 18 b that spray a cooling medium against the work rolls 12 a and 12 b are disposed opposite to each other above and below the rolled material 16. . The coolant devices 18a and 18b have a plurality of sprays at predetermined intervals corresponding to a unit width (zone) of the shape detector 20 to be described later over the longitudinal direction (the axial direction of the work rolls 12a and 12b). A nozzle (not shown) is disposed at a fixed position, and a cooling medium is sprayed from each spray nozzle to a portion corresponding to the spray nozzle in the work rolls 12a and 12b.

  Further, on the exit side of the rolled material 16 (upper left side in FIG. 1), a shape detector 20 capable of directly measuring the plate shape (tension) of the rolled material 16 with a predetermined unit width in the plate width direction. The shape detector 20 detects each plate shape in a plurality of portions (zones) of the rolled material 16 divided by unit widths in the plate width direction, and the detection result (detection) The shape value) is input to the control device 22.

  And under the state where spraying of the cooling medium by the coolant devices 18a, 18b to the work rolls 12a, 12b is controlled by the control device 22, the work roll 12b located on the lower side of the pair of work rolls 12a, 12b is The work roll 12a and the pair of backup rolls 14a and 14b are rotationally driven by a drive motor (not shown), and accordingly, the rolled material 16 becomes the entry side. It is rolled between the pair of work rolls 12a and 12b while being gradually fed from the side toward the exit side.

  That is, on the work rolls 12a and 12b, the control medium 22 performs ON / OFF control of spraying of the cooling medium to each part corresponding to each zone of the rolled material 16, so that the work roll 12a is cooled. The cooling state (temperature distribution) in 12b is changed, the thermal crown is adjusted there, and the plate shape of the obtained rolled material 16 is controlled for each unit width (zone). .

  In this case, the control device 22 that performs ON / OFF control of the coolant blowing by the coolant devices 18a and 18b has a configuration as shown in FIG. Specifically, 1) predicting the plate shape of the rolled material 16 at the next control (after the unit time has elapsed) when the cooling medium spraying is turned ON, and predicting from the predicted plate shape and the target plate shape First calculation means (calculation means for predicted shape deviation 1) 24 for obtaining the shape deviation 1 and 2) predicting the plate shape of the rolled material 16 at the next control when the cooling medium spraying is turned off, and such prediction The second computing means (calculating means for predicted shape deviation 2) 26 for obtaining the predicted shape deviation 2 from the plate shape and the target plate shape, and 3) the absolute value of the predicted shape deviation 1 obtained by the first computing means Third calculation means for obtaining a value (absolute value calculation means for predicted shape deviation 1) 28 and 4) Fourth calculation means for obtaining an absolute value of predicted shape deviation 2 obtained by the second calculation means (predicted shape) Absolute value calculation means for deviation 2) 3 5) Comparing means 32 for comparing the absolute value of the predicted shape deviation 1 and the absolute value of the predicted shape deviation 2 with a predetermined threshold value, and 6) based on the comparison result in the comparing means 32, respectively. , And a determination means 34 for determining ON or OFF of the cooling medium spraying by the coolant devices 18a, 18b. In the present embodiment, as described above, the plate shape of the rolled material 16 is controlled for each predetermined unit width (zone), and the controller 22 finally cools each zone. ON / OFF of the spraying of the medium is determined.

  And with respect to the control apparatus 22 which has such a structure, it was detected by the shape detector 20 at the time of one control (at the time of the start of rolling or any one of the control time set every unit time thereafter). Tension in each zone (detected shape value): y, ON / OFF state of cooling medium for each zone by coolant devices 18a, 18b (control signal, ON time: +1, OFF time: -1): u, and rolled material The target shape value of each zone in 16 is input, and first, the predicted shape deviation 1 is calculated by the first calculation means, and the predicted shape deviation 2 is calculated by the second calculation means for each zone. In the present embodiment, the target shape value is input by an external input unit (not shown). However, the target shape value is input to the first calculation unit 24 and the second calculation unit 26 in advance. It is also possible to set it.

  Here, when calculating the predicted shape deviation 1 by the first calculation means 24 and the predicted shape deviation 2 by the second calculation means 26, various conventionally known methods can be employed. Especially, in predicting the plate shape at the time of next control (after the unit time elapses), the plate shape control system by the coolant devices 18a and 18b is modeled as a dynamic system, and is based on a mathematical expression using state variables. Thus, a method for obtaining the amount of change in the plate shape is advantageously employed. Specifically, the plate-shaped control system using the coolant devices 18a and 18b is represented, for example, as shown in FIG. 2 of Patent Document 2 (Japanese Patent Laid-Open No. 8-90033) as a model. When a time interval (discrete time) for conversion is expressed as Δ in a discrete value system, the following formula 1 is obtained.

ｘ_i ：冷却媒体による第ｉゾーンの形状変化量［I-unit］
ｕ_i ：第ｉゾーンにおける冷却媒体の操作状態を基準化した入力
（ＯＮ時：＋１、ＯＦＦ時：−１）
ｙ_i ：第ｉゾーンにおける（検出）形状値
ｄ_i ：第ｉゾーンにおける外乱による形状変化量［I-unit］
Ｔ_i ：クーラント系時定数［ｓ］
Ｋ_ij：クーラント系ゲイン［I-unit］
Δ ：離散時間［ｓ］
ｔ ：離散化モデルにおける演算時点での時刻［ｓ］

x _i : Shape change amount of i-th zone by cooling medium [I-unit]
u _i : Input based on the operating state of the cooling medium in the i-th zone (ON: +1, OFF: −1)
y _i : (detected) shape value in the i-th zone d _i : shape change amount due to disturbance in the i-th zone [I-unit]
T _i : Coolant system time constant [s]
K _ij : Coolant gain [I-unit]
Δ: discrete time [s]
t: Time [s] at the time of calculation in the discretized model

  Specifically, based on the above formula, in the first computing means 24, the plate shape (detected shape value) of the rolled material 16 detected by the shape detector 20: y (t) and u (t) = + 1 (when the input control signal is +1, the control signal is used as it is, and when the input control signal is −1, it is converted to +1 and used). The predicted plate shape 1: y (t + 1) at the next control (after the unit time elapses) when the cooling medium spraying is turned ON in one control is calculated for each zone in the rolled material 16. Similarly, in the second calculation means 26, such y (t) and u (t) = − 1 (when the input control signal is −1, such control signal is used as it is, When the input control signal is +1, it is converted into -1 and used.) From the above, the predicted plate shape 2 at the next control when the cooling medium spraying is turned off at the time of one control: y ′ (t + 1) is calculated for each zone in the rolled material 16. When calculating the predicted plate shapes 1 and 2, if there is no significant change in the disturbance: d (t), it is not necessary to consider the disturbance: d (t), but the amount of change can be predicted. In the case where it is not negligible, the amount of change of disturbance: d (t) can also be considered. Incidentally, as this disturbance: d (t), a thermal crown or the like due to processing heat generation or the influence of cooling on other zones can be considered.

Note that [I-unit], which is a unit indicating the amount of shape change in the above formula 1, has the following physical meaning. That is, referring to the literature ("Theory and practice of sheet rolling", edited by Japan Iron and Steel Institute, published in 1984, page 96), as shown in Fig. 3, the elongation difference rate of the sheet after rolling is expressed as Δε, steepness Λ, plate wave height δ, and plate wave pitch l, λ = δ / l and Δε = (π / 2) ² · (δ / l) ² Rate: By multiplying Δε by 10 ⁵ , it is possible to obtain the elongation difference rate whose unit is converted to [I-unit].

  Then, from the predicted plate shapes 1 and 2 for each zone obtained in this way and the target shape value in each zone, the first computing means 24 calculates the predicted shape deviation 1 at the next control, In the second calculation means 26, the predicted shape deviation 2 at the next control time is calculated.

  Next, using the predicted shape deviations 1 and 2 for each zone calculated as described above, the third calculation means 28 obtains the absolute value of the predicted shape deviation 1 while the fourth calculation means 30. In, the absolute value of the predicted shape deviation 2 is obtained. Note that the control device 22 of the present embodiment obtains the absolute value of the predicted shape deviation 1 (2) separately from the first (2) computing means 24 (26) that calculates the predicted shape deviation 1 (2). Although (4) calculation means 28 (30) is provided, in the present invention, even calculation means that can obtain both the predicted shape deviation 1 (2) and its absolute value are used. It goes without saying that you get.

  Further, the obtained absolute values of the predicted shape deviations 1 and 2 in each zone are input to the comparison unit 32 where they are compared with a predetermined threshold value. Here, as the threshold value in the comparison means 32, a value that does not interfere with practical use as the plate shape deviation is set in advance according to the quality of the target rolled material 16 or the like. The obtained comparison result is output to the determination means 34.

  Then, in the determining unit 34, ON / OFF of the cooling medium spraying is determined based on the comparison result in the comparing unit 32 described above.

  That is, in the determination means 34, based on the comparison result in the comparison means 32 described above, for each zone, 1) either one of the absolute value of the predicted shape deviation 1 and the absolute value of the predicted shape deviation 2; Alternatively, when both are larger than the threshold value, the cooling medium spraying state (ON or OFF) is determined so that the predicted shape deviation becomes smaller as in the conventional case, while 2) the absolute value of the predicted shape deviation 1 When both the value and the absolute value of the predicted shape deviation 2 are within the threshold value, the cooling medium spray ON or OFF determined in the immediately preceding control, that is, the first calculating means 24 and the first calculating means 24 described above are used. It is determined that the ON / OFF state of the cooling medium input to the second calculating means 26 is maintained as it is, and the ON / OFF signal of the cooling medium based on the determination result is the coolant device 18a, 1 And is output with respect to b. Based on the ON / OFF signal from the determining means 34, the coolant devices 18a and 18b are controlled to turn on or off the cooling medium sprayed by the spray nozzles corresponding to the zones of the rolled material 16. is there.

  As described above, according to the shape control according to the present invention, the predicted shape deviation at the next control time when the spraying of the cooling medium is turned ON and when it is turned OFF is obtained, and the absolute values thereof are both predetermined. If it is within the threshold value, it will be maintained as it is without switching ON / OFF of spraying of the cooling medium, so that it is unnecessary in practice while sufficiently securing the shape accuracy of the obtained rolled material. The occurrence of switching of coolant operation (ON / OFF switching of cooling medium spraying) is effectively suppressed, and the durability of the coolant device can be advantageously improved, thereby reducing the equipment maintenance cost. Can be planned.

Here, during cold rolling of an aluminum alloy, a simulation is performed when the shape control according to the present invention is adopted, and a change in the shape deviation (absolute value) in one zone of the rolled material obtained by the simulation is shown in FIG. 4 and FIG. 5 shows changes in the cooling medium spraying state (changes in the ON / OFF state). Similarly, in the cold rolling of an aluminum alloy, the method as disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 8-90033) previously proposed by the present inventors, specifically, a predicted shape after elapse of unit time. A simulation is also performed when a method of controlling the spraying of the cooling medium to the work roll is adopted so that the predicted shape deviation is reduced, and the shape in one zone of the rolled material obtained by the simulation is obtained. A change in deviation (absolute value) is shown in FIG. 6, and a change in the cooling medium spraying state (change in the ON / OFF state) is shown in FIG. In these shape controls, the plate shape prediction calculation after unit time elapses is performed based on the above (Equation 1), and the time interval (discrete time) for discretization in (Equation 1): Δ 0.5 [s], disturbance in the target zone: d _i +5.0 [I-unit], coolant system time constant: T _i 10.0 [s], coolant system gain: K _ij 10.0 [I-unit]. Further, the target shape value in the target zone was set to 0.0 [I-unit], and the threshold value was set to 0.8 [I-unit]. Such a threshold is indicated by a dotted line in the graphs of FIGS.

  As is apparent from the results of the examination by the simulation, in the shape control by the conventional method in 30 seconds from the start of the control, the cooling medium is turned on / off 24 times (see FIG. 7), but according to the present invention. In shape control, it was recognized that the ON / OFF switching of the cooling medium was 12 times half of the conventional method while keeping the shape deviation of the obtained rolled material within the threshold (see FIG. 4) (see FIG. 4). 5).

  The specific configuration of the present invention has been described in detail above. However, this is merely an example, and the present invention is not limited by the above description.

  For example, in the above-described embodiment, the coolant devices 18a and 18b for spraying the cooling medium to the work rolls 12a and 12b are sprays whose positions are fixed so as to correspond to the zones of the work rolls 12a and 12b on a one-to-one basis. Although the nozzle has a structure, in the present invention, a spray device for a work roll is provided by a coolant device capable of simultaneously spraying a cooling medium to a plurality of zones from a single spray nozzle, or by a signal from a control device. It is also possible to use a coolant device or the like that can change the relative position.

  In addition, although not enumerated one by one, the present invention can be carried out in a mode to which various changes, modifications, improvements, etc. are added based on the knowledge of those skilled in the art. It goes without saying that all are included in the scope of the present invention without departing from the spirit of the present invention.

It is a partial block explanatory drawing which shows roughly an example of the shape control system provided with the shape control apparatus according to this invention. It is block explanatory drawing which shows an example of the shape control apparatus according to this invention. It is a schematic diagram for demonstrating the steepness and elongation difference rate in the plate shape of a rolling material. It is a graph which shows the result at the time of simulating according to shape control of the present invention (change of shape deviation). It is a graph which shows the result (change of the ON / OFF state of a cooling medium) at the time of simulating according to shape control of the present invention. It is a graph which shows the result at the time of simulating according to the conventional shape control (change of shape deviation). It is a graph which shows the result (change of the ON / OFF state of a cooling medium) when simulating according to the conventional shape control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rolling machine 12a, 12b Work roll 14a, 14b Backup roll 16 Rolled material 18a, 18b Coolant apparatus 20 Shape detector 22 Control apparatus 24 1st calculating means 26 2nd calculating means 28 3rd calculating means 30 4th calculating means 30 4th Calculation means 32 Comparison means 34 Determination means

Claims (2)

When controlling the plate shape of the obtained rolled material by controlling the ON / OFF control of the cooling medium spraying on the work roll of the rolling mill at each control time set at the start of rolling and every subsequent unit time, At the time of one control, the plate shape of the rolled material is predicted at the next control after the elapse of unit time, and the cooling at the time of the one control is based on the deviation between the predicted plate shape and the target plate shape. A shape control method in a rolling mill for determining ON or OFF of spraying of a medium,
At the time of the one control, the plate shape of the rolled material at the time of the next control when the cooling medium spraying is turned on is predicted, and the predicted shape deviation 1 is obtained from the predicted plate shape and the target plate shape. On the other hand, the plate shape of the rolled material at the time of the next control when the spraying state of the cooling medium is turned off is predicted, the predicted shape deviation 2 is obtained from the predicted plate shape and the target plate shape, and the predicted shape When the absolute value of each of the deviation 1 and the predicted shape deviation 2 is compared with a predetermined threshold and the absolute values of the predicted shape deviation 1 and the predicted shape deviation 2 are equal to or less than the threshold, A shape control method in a rolling mill, wherein the ON or OFF of the cooling medium spraying determined in the immediately preceding control is maintained as it is at the time of one control. When controlling the plate shape of the obtained rolled material by controlling the ON / OFF control of the cooling medium spraying on the work roll of the rolling mill at each control time set at the start of rolling and every subsequent unit time, At the time of one control, the plate shape of the rolled material is predicted at the next control after the elapse of unit time, and the cooling at the time of the one control is based on the deviation between the predicted plate shape and the target plate shape. A shape control device in a rolling mill that determines ON or OFF of spraying of a medium,
At the time of the one control, the plate shape of the rolled material at the time of the next control when the cooling medium spraying is turned on is predicted, and the predicted shape deviation 1 is obtained from the predicted plate shape and the target plate shape. A first computing means;
At the time of the one control, the plate shape of the rolled material at the time of the next control when the cooling medium spraying is turned off is predicted, and the predicted shape deviation 2 is obtained from the predicted plate shape and the target plate shape. A second computing means;
A comparison between the absolute value of the predicted shape deviation 1 obtained by the first computing means and a predetermined threshold value; and the absolute value of the predicted shape deviation 2 obtained by the second computing means; A comparison means for comparing with a threshold;
When the absolute value of the predicted shape deviation 1 and / or the absolute value of the predicted shape deviation 2 exceeds the threshold value based on the comparison result in the comparison means, the predicted shape deviation is greater in the one control. On the other hand, when the cooling medium spray ON or OFF is determined to be small, the absolute value of the predicted shape deviation 1 and the absolute value of the predicted shape deviation 2 are both within the threshold value. At the time of control, determining means for maintaining ON or OFF of the cooling medium spraying determined at the time of the immediately preceding control,
A shape control apparatus for a rolling mill, comprising:

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