JP6438753B2 - Tandem rolling mill control device and tandem rolling mill control method - Google Patents

Description

  The present invention relates to a control device for a tandem rolling mill and a control method for a tandem rolling mill, and in particular, when calculating the rolling position of a work roll of each stand for rolling to a desired plate thickness prior to rolling the steel plate. The present invention relates to a control device for a tandem rolling mill and a control method for a tandem rolling mill that are suitable for stabilizing rolling and obtaining good steel sheet quality by optimizing the calculated value of the rolling position to a value that provides a target plate thickness.

  In tandem rolling, the rolling state of the steel sheet is predicted prior to rolling, the work roll reduction position (corresponding to the gap between the upper and lower work rolls) and the roll speed are determined, the steel sheet tip is controlled, and then the detector A method is used in which the rolling position and roll speed are gradually corrected to appropriate values using the plate thickness obtained from the plate and the steel plate tension between the stands. For this reason, it is necessary to determine the command values for the rolling position and roll speed of each rolling stand to appropriate values by predictive calculation. In particular, in hot rolling, where batch rolling of steel plates one by one, the thickness of the tip of the steel plate is accurately controlled to the target value, and the rolling is stabilized when the tip is caught in each rolling stand of the finishing mill. In addition, it is necessary to determine the rolling roll command and roll speed command values to appropriate values by predictive calculation. In order to obtain the target thickness on the final stand exit side, the most important is the reduction position, and it is necessary to determine the reduction position appropriately. Hereinafter, in the present invention, the reduction position refers to the reduction position of the work roll.

  As a conventional method for determining the reduction position to an appropriate value, there is the following. In JP 2013-198920 A, a tip thickness chart of rolling results is stored in layers by steel type and thickness, and the tip thickness chart for each layer corresponding to the steel sheet to be rolled next time and the plate of this steel sheet are recorded. A method is shown in which the reduction position is adjusted so that the thickness deviation from the tip is shortened from the thickness intersection.

  JP-A-2004-42058 also includes an intermediate plate thickness gauge between the stands, and corrects the reduction position of the downstream stand (stand after the intermediate plate thickness gauge) according to the deviation between the target intermediate plate thickness and the intermediate plate thickness gauge. The technique to do is shown.

JP 2013-198920 JP 2004-42058 JP

  However, these conventional techniques have the following problems.

  In the method of Patent Document 1, the thickness chart for each layer is not always similar every time, so that the plate thickness behavior at the tip of the steel plate to be rolled next time is stored as a result. When the chart was different from the thickness chart, there was a fear that the appropriate reduction position could not be adjusted. In addition, the amount of calculation increases due to the process of accumulating and collating chart data.

  In the method of Patent Document 2, an intermediate plate thickness gauge that is not provided in normal hot rolling is required to correct the reduction position, so that there is a problem that the system price becomes expensive and the maintenance work of the system increases. .

  Therefore, the problem to be solved by the present invention is to control a tandem rolling mill that can calculate an appropriate reduction position by a simple calculation without providing a special detector, and calculates a reduction position at which a target plate thickness can be obtained. It is to provide an apparatus and method.

  In order to solve this problem, the present application estimates the rolling load of each stand from information on the target plate thickness and chemical composition of the coil to be rolled next time received from the host computer, and calculates the control command for the rolling position and roll speed. In addition to the command set-up unit, an intermediate plate thickness calculation unit that estimates the plate thickness between the stands, and the rolling position of each stand is estimated using the rolling records taken from the controlled object, and the estimated rolling position and actual rolling position are Rolling position deviation calculation unit that calculates the deviation, plate thickness deviation calculation unit that calculates the deviation between the target thickness on the exit side of the finishing mill taken from the control command setup unit and the actual plate thickness obtained as rolling results, A reduction position correction amount calculation unit for calculating a reduction position correction amount from the thickness deviation is provided, and the control command setup unit calculates the reduction position using the calculated reduction position correction amount. It was.

  Specifically, the reduction position correction amount calculation unit calculates a deviation between the calculation result obtained by substituting the rolling performance into the reduction position calculation formula and the actual reduction position as a reduction position estimation error. By adding / subtracting the reduction position estimation error to the next reduction position calculation result, it is possible to calculate a reduction position with less error in the next coil. The plate thickness deviation calculating unit calculates an error from the target plate thickness of the finish mill final stand outlet side plate thickness obtained as a result of the plate thickness control. When the plate thickness error is large, the plate thickness error of the next coil can be reduced by correcting the reduction position in the direction to reduce this in the next rolling. In the reduction position correction amount calculation unit, by adding the reduction position deviation and the plate thickness deviation with appropriate weighting, errors in the reduction position calculation formula can be reduced while considering reduction of the plate thickness deviation. The control command setup unit calculates the final reduction position command by correcting the reduction position of each stand calculated based on the rolling theory with the reduction position correction amount obtained from the reduction position correction amount calculation unit. Thickness accuracy on the mill exit side can be improved.

  According to the present invention, it is possible to calculate an appropriate reduction position by a simple calculation without providing a special detector, and it is possible to increase the plate thickness accuracy.

It is explanatory drawing which showed the structure of the control apparatus of the tandem rolling mill of this invention. This is a process of the control command setup unit 101. This is a configuration of the draft schedule storage unit 102. This is a configuration of the speed pattern storage unit 103. This is the processing of the intermediate plate thickness estimation unit 111. This is a process of the reduction position deviation calculation unit 112. This is a process of the plate thickness deviation calculating unit 113. This is a process of the reduction position correction amount calculation unit 115. This is a configuration of the reduction position correction amount calculation gain storage unit 114. This is a configuration of the reduction position correction amount storage unit 116. It is explanatory drawing which showed the structure of the control apparatus of the tandem rolling mill of 2nd Example of this invention. This is the processing of the steel sheet similarity calculation unit 1102. This is the configuration of the steel sheet layer storage unit 1101.

  When calculating the reduction position of each stand for rolling to the desired thickness prior to rolling the steel plate with a finishing stand of a hot rolling mill or a cold tandem mill, a reduction that improves the thickness accuracy with a simple calculation. The position can be calculated. As a result, it is possible to obtain a steel plate with a high precision tip thickness and to stabilize tandem rolling. In addition, in the hot rolling mill finishing stand, the leading edge plate (steeling of each steel plate into each stand) becomes smooth, and quality defects can be reduced.

  FIG. 1 shows an embodiment of the present invention. In this embodiment, an example in which the control device for the tandem rolling mill is the control device for the hot tandem rolling mill will be described. Specifically, the operations shown in the calculation units or flowcharts of this embodiment can be executed by a computer. The control device 100 of the tandem rolling mill receives various signals from the controlled object 150 and outputs control signals to the controlled object 150. First, the configuration of the controlled object 150 will be described. In this embodiment, the control target 150 is a hot tandem rolling mill provided with a finishing mill 160. In the example shown in the figure, the finishing mill 160 is composed of a plurality of rolling stands. In this embodiment, seven rolling stands 161 are continuously connected. The arrangement is arranged. In FIG. 1, the steel plate 163 moves from left to right, and a thin steel plate 163 is produced by rolling a rough material 165 having a thickness of about 30 mm that has been rolled by a roughing mill, which is the previous process. The coarse material 165 may be called by a name such as a coarse bar, an incoming bar, or a transfer bar. In the finishing mill 160, the coarse material 165 is sequentially thinned by rolling at each rolling stand 161 and finally delivered as a steel plate 163 of about 1 mm to 15 mm on the exit side of the final rolling stand F7. The finish mill 160 directly rolls the rough material 165 and the steel plate 163 with the work roll 162 provided in each rolling stand 161. In the present invention, the roll speed means the peripheral speed of the work roll 162. In this embodiment, as a detector for grasping the state of the steel plate 163, a multi-gauge 164 for measuring the thickness, width, and temperature of the steel plate 163 is provided on the exit side of the final rolling stand (F7) of the finishing mill 160. ing. Although omitted in the present embodiment, actually, as a detector for grasping the state of the coarse material 165 and the steel plate 163, a thermometer, a shape meter for measuring the flatness of the plate, and the leading edge of the coarse material 165 are used. Various detectors such as a crop profile meter for measuring an edge shape image and a surface wrinkle meter for detecting a surface flaw of the steel plate 163 are provided in various places as necessary.

  Next, the configuration of the control device 100 of the tandem rolling mill will be described. The control device 100 of the tandem rolling mill receives information necessary for rolling, such as a steel type, a target plate thickness, a target plate width, and the like from the host computer 50 for each of the steel plates to be rolled, and the draft schedule storage unit 102 and the speed pattern With reference to the storage unit 103, the rolling command, the rolling position of the work roll 162, the rolling speed of the work roll 162, the roll speed of the work roll 162, etc. are calculated for each rolling stand 161. Using the data collected by the performance collection unit 110 and the performance collection unit 110 that collect the control command values that are actually output by the control device 100 of the mill, the plate thickness between the stands (hereinafter referred to as intermediate plate thickness) is estimated. Intermediate thickness calculation unit 111, estimation of the rolling position calculated using the inlet and outlet plate thicknesses estimated by the intermediate thickness calculation unit 111 and the rolling load of each rolling stand 161 taken from the performance collecting unit 110 Values and results The rolling position deviation calculation unit 112 that calculates the deviation from the actual rolling position value of each rolling stand 161 captured from the collecting unit 110, the target thickness on the F7 outlet side that is captured from the control command setup unit 101, and the actual value collecting unit 110 The thickness deviation calculating unit 113 for calculating the difference between the actual sheet thicknesses on the F7 delivery side, the deviation of the rolling position of each rolling stand 161 taken in from the rolling position deviation calculating unit 112, and the plate thickness taken in from the thickness deviation calculating unit 113 A reduction position correction amount calculation unit 115 that calculates a correction amount of the reduction position of each rolling stand 113 by calculation using the deviation and outputs the correction amount to the control command setup unit 101 is configured.

  Hereinafter, the operation of each part will be described in detail. FIG. 2 shows processing executed by the control command setup unit 101. The control command setup unit 101 receives information necessary for rolling such as the steel type, target plate thickness, target plate width and the like from the host computer 50, and then gives control commands such as the rolling position and roll speed for the steel plate 163 to be rolled. calculate. When the steel plate 163 is rolled by the finishing mill 160, the tip of the steel plate 163 is rolled according to the control command output by the control command setup unit 101. Therefore, in order to obtain a desired steel plate thickness from the tip, In order to stabilize the rolling load and the roll-down position of the work roll 162, and to stabilize the behavior of the steel plate when it bites into the downstream stand, the roll speed of each stand is set to the mass flow (thickness and thickness) of the steel plate 163. It is necessary to set a balanced command that does not disturb the product of the plate speed.

  First, in S2-1, a draft schedule which is information corresponding to how much the rough material 165 and the steel plate 163 are thinned in each of the rolling stands 161 is fetched from corresponding items in the draft schedule storage unit 102.

  FIG. 3 shows a configuration example of the draft schedule storage unit 102. In the example shown in the figure, the draft schedule stores the rolling at each rolling stand 161 and stores the difference between the thickness of the inlet side and the outlet side with respect to the inlet side thickness as a percentage. Each draft schedule indicates the steel type and thickness of the steel sheet to be rolled. , Stratified by plate width. The difference in plate thickness between the inlet side and the outlet side with respect to the inlet side plate thickness is called the rolling reduction. For example, consider a 35 mm rough 165 with a steel grade of SS400, a target plate thickness of 2.5 mm, and a target plate width of 900 mm. The target thickness is 2.0 to 3.0mm, and the target width is 1000mm or less. FIG. 3 shows that 35 mm of the rough material 165 is rolled by 14 mm corresponding to 40% on the F1 inlet side to obtain an F1 outlet thickness of 21 mm. In F2, it is shown that a 21mm inlet side plate thickness is rolled 35% to obtain an F2 outlet side plate thickness of 13.65mm. The deviation that occurs between the F7 outlet thickness obtained in this way and the target thickness of 2.5 mm is eliminated by correcting the reduction rate of each stand according to the reduction rate. In this way, in S2-1, the control command setup unit 101 searches the draft schedule storage unit 102 for the relevant stratification from the steel type, thickness, and width of the steel sheet to be rolled next time received from the host computer 50. In order to obtain the target final stand thickness (F7 in this embodiment), the rolling reduction of each stand is calculated. Next, in S2-2, the speed pattern is fetched from the speed pattern storage unit 103, and the roll speed of each rolling stand is calculated.

FIG. 4 shows the configuration of the speed pattern storage unit 103. The steel plate speed (initial speed) when the tip of the steel plate 163 is discharged from F7 (final rolling stand) with respect to the steel type, target plate thickness, and target plate width of the steel plate 163, and then the first acceleration, the second acceleration, and the steady state The speed, the deceleration when decelerating from the steady speed to the final speed when rolling the tail end of the steel plate 163, and the final speed are accumulated for each layer. The control command setup unit 101 determines the steel type, plate thickness, and plate width of the steel plate 163, and extracts the corresponding speed pattern from the speed pattern storage unit 103. For example, when steel grade is SS400, plate thickness is 1.2-1.4mm, and plate width is less than 1000mm, initial speed 650mpm, first acceleration 2mpm / s, second acceleration 12mpm / s, steady speed 1100mpm, deceleration 6mpm / s, final speed This indicates that 700 mpm is set. The initial speed is the speed of the steel plate 163 when the tip of the steel plate 163 is paid out from the final rolling stand 161 (F7), the first acceleration is the acceleration rate when the steel plate 163 subsequently increases the speed, the first acceleration The two accelerations are the acceleration rate and deceleration after the steel plate 163 is bitten by the downcoiler, which is the latter stage equipment, until the steady speed is reached. The steel plate 163 stably deviates from each stand and decelerates to the final speed. Is the deceleration rate. Next, the rolling temperature of each stand is calculated in S2-3. The temperatures of the rough material 165 and the steel plate 163 are the values detected by thermometers installed at various locations of the control target 150, heat radiation, heat transfer, heat generation due to deformation of the steel plate due to rolling, and the roll surface during rolling. It is estimated by combining temperature prediction calculation considering roll contact heat transfer etc. Many temperature estimation methods have been introduced in thermodynamic literature, etc. Further, temperature changes in rolling are described in detail in Chapter 6 (Temperature changes in rolling) of “Theory and practice of plate rolling (Japan Iron and Steel Institute)”, for example. Detailed explanation is omitted. In S2-4, the deformation resistance, which is a value corresponding to the hardness of the steel sheet rolled at each rolling stand, is calculated. The method for obtaining the deformation resistance is described in various documents, for example, in Chapter 7 (Deformation Resistance) of "Theory and Practice of Sheet Rolling (Japan Iron and Steel Institute)". As a typical calculation formula for deformation resistance, using the estimated steel plate temperature T during rolling,

[Equation 1]
kf ＝ Kε ⁿ (dε / dt) ^m exp (A / T)

Where ε: Strain, (dε / dt): Strain rate
K, n, m, A: Constants determined for each steel type

Is given as follows. ("Plate Rolling Theory and Practice" Formula 7.54)
Next, the roll speed of each rolling stand is calculated in S2-5. Since the speed pattern captured in S2-2 is the F7 delivery plate speed, the delivery plate speed of each rolling stand is calculated as follows based on this.
First, the exit side plate speed of each rolling stand is calculated by [Equation 2].

[Equation 2]
Vs _i = Vs ₇ × h ₇ / h _i

Vs _i : Outboard plate speed of i-th stand
h _i : Outboard thickness of the i-th stand
h ₇ : Outboard thickness of the 7th stand (final rolling stand)

Next, using the advanced rate, the roll speed of each rolling stand is calculated from the exit side plate speed of each rolling stand. Here, the advanced rate is a value corresponding to the ratio between the peripheral speed of the work roll and the exit speed of the sheet rolled by the work roll.

[Equation 3]
f = F (H, h, R ', Kp, tb, tf)

Where H: inlet side plate thickness, h: outlet side plate thickness, R ′: flat roll diameter,
Kp: deformation resistance, tb: incoming tension, tf: outgoing tension

It is known that Details are given in “Theory and Practice of Sheet Rolling” (edited by the Japan Iron and Steel Institute). Using the advanced rate, there is a relationship of [Equation 4] between the roll speed and the exit side plate speed.

[Equation 4]
Vr _i = Vs _i / (1+ f _i )

Vr _i: roll speed of the i-th stand
f _i : Advanced rate of i-th stand

The advance rate is calculated for each rolling stand, and the roll speed of each rolling stand is obtained. Furthermore, the rolling load is calculated in S2-6. The details of the rolling load prediction formula are shown in “Theory and Practice of Sheet Rolling” (edited by the Japan Iron and Steel Institute) and the like, for example, expressed by [Equation 5].

[Equation 5]
P = G (w, Kp, Qp, tf, tb, R ', H, h, μ)

Where w: plate width, Kp: deformation resistance, Qp: rolling force function, μ: friction coefficient

In general, there is a discrepancy between the rolling load prediction formula and the load obtained by actual rolling, so in order to reduce this discrepancy and increase the accuracy of rolling load prediction, the rolling load is actually multiplied by an appropriate correction factor. Predict. Details of the correction coefficient will be described in the explanation of the reduction position correction amount calculation unit 115 . Finally, the reduction position (roll gap) of the work roll 162 is calculated in S2-7. The basic part of the calculation of the reduction position is expressed by the relational expression [Equation 6]. In practice, however, various correction terms such as a bender pressure for controlling the deflection of the roll are added to increase the calculation accuracy. .

[Equation 6]
S = h−P / K

S: Rolling position, P: Rolling load, K: Mill spring constant

The control command setup unit 101 outputs the reduction position and roll speed calculated as described above corresponding to the steel sheet to be rolled next time as a control command. The reduction position control unit 130 controls the reduction position so that the reduction position of the work roll 162 becomes a value according to the control command in response to the control command of the reduction position output from the control command setup unit 101. Similarly, the speed control unit 140 performs speed control with respect to the speed control command output from the control command setup unit 101 so that the speed of the work roll 162 becomes a value as in the control command.

The control command setup unit 101 calculates a control command for a coil to be rolled next time before rolling, whereas an intermediate plate thickness calculation unit 111, a rolling position deviation calculation unit 112 , and a plate thickness deviation calculation unit 113 are shown below. The series of calculations executed by the reduction position correction amount calculation unit 115 is performed using the rolling record of the rolled steel sheet 163 at the timing when the rolling is finished. The rolling subject to calculation is called the rolling, and the steel plate 163 produced by the rolling is called the steel plate.

FIG. 5 shows processing executed by the intermediate plate thickness calculation unit 111. The intermediate plate thickness calculation unit 111 estimates the outgoing side plate thicknesses t _{1 to} t ₇ of F _{1 to} F ₇ when the steel plate 163 is rolled for the steel plate 163 based on the rolling results. These plate thicknesses are hereinafter referred to as intermediate plate thicknesses. When a detector for measuring the thickness of the rough material 165 is not provided, the thickness t ₀ of the rough material 165 is also estimated. Take in the final stand (F7) out of the plate thickness was measured in a multi-gauge 164 of the side value t ₇ at S5-1. The so-called mass flow constant law is established, where the product of the plate thickness and plate speed is constant on the entry and exit sides of F7. In S5-2, F7 inlet side plate thickness (= F6 outlet side plate thickness) is estimated according to the constant mass flow rule. That is, t ₆ is calculated according to [Equation 7].

[Equation 7]
t ₆ = t ₇ × V ₇ × (1 + f ₇ ) / {V ₆ × (1 + f ₆ )}

Where t _{7 is the} measured F7 outlet thickness, V _{7 is} the peripheral speed of the F7 work roll,
f _7: F7 of advanced rate, V _6: F6 circumferential speed of the work rolls, f _6: F6 advanced rate of

As the advance rates f ₆ and f ₇ , the values calculated by the control command setup unit 101 using [Formula 3] prior to rolling of the steel sheet are used. Since the advance rate is calculated by estimation using mathematical formulas, it is a value including a certain error, and the error is also superimposed on the estimated intermediate plate thickness. In S5-3 to S5-8, by repeating the process similar to [Equation 7], the entry side plate thickness is estimated in the order of F6, F5, F4, F3, F2, and F1. In other words, from the downstream rolling stand, the calculation for obtaining the thickness at the entrance side of the stand is performed in order from each advanced rate and the thickness at the exit side of the rolling stand. In this example, the outlet side thickness of each stand was calculated in order from the downstream stand, but it was calculated simultaneously from the measured F7 outlet thickness, F7 advanced rate, and the relationship between the advanced rate and roll speed of each stand. You can also.

FIG. 6 shows the processing of the reduction position deviation calculation unit 112. In S6-1, the exit side plate thickness of the stand in the rolling is fetched from the intermediate plate thickness calculation unit 111. Next, in S6-2, the rolling load and the actual value of the rolling position related to the stand of the steel sheet are fetched from the actual collecting unit 110, and the rolling position of the stand is calculated by [Equation 6] using the actual value of the rolling load. Is estimated. The rolling load and the actual value of the rolling position are usually taken at the same position at the tip of the steel plate. For example, the value after the steel plate is caught in each stand and about 2 to 3 m is collected as the actual result. Just do it. In S6-3, the rolling position deviation (Ds0_c) i, which is the difference between the actual value of the rolling position captured in S6-2 and the estimated value of the rolling position calculated in S6-2, is calculated according to [Equation 8]. .

[Equation 8]
(Ds0_c) i = (Dsa) i− (Dse) i

Where (Dsa) i: actual rolling position of the i-stand of the rolling,
(Dse) i: Estimated reduction position of the i-stand of the rolling,

In S6-4, it is determined whether or not the processing for calculating the rolling position deviation has been completed for all the stands, and if not completed, S6-1 to S6-3 are repeated. If the processing for calculating the rolling position deviation is completed for all the stands, the processing of the rolling position deviation calculating unit 112 for the steel plate is finished.

FIG. 7 shows the processing of the plate thickness deviation calculating unit 113. In S7-1, the target plate thickness is fetched from the control command setup unit 101. In S7-2, the actual sheet thickness measured by the multi-gauge 164 on the F7 exit side is fetched from the actual result collection unit 110. In S7-3, the thickness deviation (hd) 7 is calculated according to [Equation 9].

[Equation 9]
(hd) 7 = htarget−ha7

Where (hd) 7: F7 outlet thickness deviation, (ha) 7: F7 outlet thickness
htarget: Target plate thickness


As shown in [Equation 9], the plate thickness deviation is calculated by the difference (hd) 7 between the F7 outlet side plate thickness detected from the multigauge 164 and the target plate thickness.

  FIG. 8 shows the processing of the reduction position correction amount calculation unit 115. In S8-1, the plate thickness deviation is fetched from the plate thickness deviation calculating unit 113. In step S8-2, the reduction position deviation of the stand is acquired from the reduction position deviation calculation unit 112. In step S8-3, the reduction position correction amount calculation gain is acquired from the reduction position correction amount calculation gain storage unit 114.

  FIG. 9 shows the configuration of the reduction position correction amount calculation gain storage unit 114. The reduction position correction amount calculation gain is composed of reduction position deviation gain and sheet thickness deviation gain. In the example of Fig. 9, these are stratified by steel type, plate thickness, and plate width. For example, steel type is SS400, plate thickness When 2.0 is 3.0-3.0mm and the sheet width is 1000mm or less, 0.5 is stored as the rolling position deviation gain and 0.45 is stored as the sheet thickness deviation gain. In addition, when the steel grade is SS400, the plate thickness is 12.0 mm or more, and the plate width is 1400 mm or more, 0.5 is stored as the rolling position deviation gain and 0.55 is stored as the plate thickness deviation gain.

In S8-4, the value (Ds0_c) i of the rolling position correction amount stored as the result of the latest rolling is fetched from the rolling position correction amount storage unit 116. FIG. 10 shows a configuration of the reduction position correction amount storage unit 116. In this embodiment, the reduction position correction amount stored in the reduction position correction amount storage unit 116 is stratified by steel type and sheet thickness, and the reduction position correction amount is calculated corresponding to the past rolling for each layer. The reduction position correction amount of each stand output from the unit 115 is stored. The rolling position correction value (Ds0_c) i is stored for each stand (F1 to F7) for each stratum. In Fig. 10, when the steel grade is SS400 and the plate thickness is 1.6mm or less, the rolling position correction is corrected. In this example, 0.21, -0.03, 0.14, 0.03, -0.1, 0.18, and 0.31 are stored in order from F1. In S8-5, using the values and gains acquired in S8-1 to S8-4, calculate the reduction position correction amount (Ds0) i of the stand according to [Equation 10] and output it to the control command setup unit 101 To do.

[Equation 10]
(Ds0) i = α ・ (Ds0_c) i + (1−α) ・ (Ds0_p) i + β ・ (hd) i

Where α: Rolling position deviation gain, β: Plate thickness deviation gain
(Ds0_c) i: taken out from the reduction position correction amount storage unit 116
Reduction position correction amount for i-th stand

In calculating the reduction position correction amount (Ds0) i of the stand, α is the reduction position correction amount based on the past rolling record stored in the reduction position correction amount storage unit 116, and the rolling of the most recently rolled steel sheet 163. A coefficient that determines the distribution ratio of the reduction position correction amount calculated based on actual results and takes a value of 0 to 1. When α is 0, the reduction position correction amount calculated based on the rolling performance of the steel sheet 163 is ignored, and the calculation using the reduction position correction amount based on the past rolling performance stored in the reduction position correction amount storage unit 116 is performed. Thus, the reduction position correction amount (Ds0) i of the stand is determined. On the other hand, when α is 1, the reduction position correction amount (Ds0) i of the stand is calculated using the rolling record of the most recently rolled steel sheet 163, and the past stored in the reduction position correction amount storage unit 115 is calculated. The reduction position correction amount based on the rolling performance is ignored. When 0 <α <1.0, these are apportioned at a ratio according to α. For example, when α is 0.5, it is calculated by the reduction position correction amount stored in the reduction position correction amount storage unit 116 and the latest rolling record. The reduced position correction amount is apportioned at the same rate. On the other hand, β is a coefficient corresponding to how much the thickness deviation on the F7 outlet side is considered, and normally takes a value of 0 to 1. When β is 0, the reduction position correction amount (Ds0) i is calculated without considering the thickness deviation. Conversely, when β is 1, it indicates that the value corresponding to the plate thickness deviation is added to the reduction position correction amount (Ds0) i of each stand as it is. When 0 <β <1.0, the plate thickness deviation is taken into consideration at a ratio according to β, and the reduction position of each stand is corrected in the direction in which the plate thickness deviation decreases. The third term on the right side is a small value when the thickness deviation is small. Therefore, when the thickness deviation is small, the third term does not affect the calculation result of (Ds0) i, so that a good state with a small thickness deviation can be maintained. In S8-6, the reduction position correction amount (Ds0) i of the stand calculated in [Equation 10] is stored in the reduction position correction amount storage unit 116. In S8-7, it is confirmed whether the processing has been completed for all the stands, and if not completed, the processing of S8-2 to S8-6 is repeated. When the processing is completed for all the stands, the processing of the reduction position correction amount calculation unit 115 in the rolling is finished.

The calculated reduction position correction amount (Ds0) i is used by the control command setup unit 101 as follows. In S2-7 of FIG. 2, the reduction position is calculated according to the equation of [Equation 6], but after receiving the reduction position correction amount from the reduction position correction amount calculation unit 115, the reduction position is calculated according to the following. Do. That is, in order to set the reduction position at which the target plate thickness is obtained on the F7 outlet side, the reduction position setting value (Ds0) of the reduction position setting value (S) i of each stand is set as shown in [Equation 11] Calculate by adding i.

[Equation 11]
(S) i = (h) i- (P) i / (K) i + (Ds0) i

(S) i: Rolling position, (h) i: Target strip thickness, (P) i: Rolling load,
(K) i: Mill spring constant, where i: Value corresponding to the i-th stand

Actually, in order to calculate the reduction position with high accuracy, the bender pressure of each stand that controls the deflection of the roll, the correction term when the rolling load is low, the term corresponding to the zero point of the reduction position, the oil film thickness Various correction terms such as terms are added.

In this embodiment, an example of a hot tandem rolling finish mill is shown as the control object 150, and an example of a control apparatus of the hot tandem rolling mill is shown as the control device 100 of the tandem rolling mill. Even in a rolling mill, the present invention can be applied as it is. In the present embodiment, the finishing mill 160 is composed of seven rolling stands 161. However, the tandem mill may be composed of four to six stands. Even in this case, the present invention can be applied as it is. Alternatively, the finishing mill 160 may be composed of one stand or two stands, and the steel plate 163 may be produced by reciprocating rolling. Even in this case, the present invention can be applied as it is by detecting or estimating the plate thicknesses on the entry side and the exit side.
As a second embodiment of the present invention, FIG. 11 shows a case where a function for changing the distribution coefficient α used in [Equation 11] according to the similarity of the steel sheet 163 rolled back and forth is added. The steel type similarity calculation unit 1102 takes the similarity numbers of the steel types of the most recently rolled steel plate and the steel plate of the next rolled steel plate from the steel plate layer storage unit 1101 and outputs them to the distribution coefficient calculation unit 1103. The distribution coefficient calculation unit 1103 calculates an appropriate value of the distribution coefficient α based on the similarity between the steel sheets before and after received from the steel type similarity calculation unit 1102, and outputs the calculated value to the reduction position correction amount calculation unit 115. The reduction position correction amount calculation unit 115 calculates [Equation 10] using α received from the distribution coefficient calculation unit 1103 in S8-5 processing.

  FIG. 12 shows the processing of the steel type similarity calculation unit 1102. For the steel type of the steel plate rolled most recently in S12-1 and the steel type of the steel plate to be rolled next time, the respective similarity numbers are taken from the steel plate layer storage unit 1101.

FIG. 13 shows the configuration of the steel sheet layer storage unit 1101. A similarity number is defined in association with each steel type. The closer the similarity number is, the more similar the characteristics (deformation resistance, etc.) of those steel types are. Means different. For example, from the steel plate layer storage unit 1101, the similarity number of SS400 is 4 and the similarity number of SS490 is 5, indicating that these are different steel types but have a high similarity. On the other hand, the similarity number of SPHC is 2, indicating that the similarity between SS400 and SPHC is not as great as the relationship between SS400 and SS490. Furthermore, the similarity numbers of SS400 and DP are greatly different, indicating that these are different types of steel. Next, in S12-2, from the difference between the similarity numbers Vni and Vnj of the two steel plates, the similarity V of these steel plates is calculated according to [Equation 12].

[Equation 12]
V = | Vni−Vnj |

From [Equation 12], the smaller the V, the larger the similarity, and the larger V, the smaller the similarity. Finally, in S12-3, the similarity V is output to the distribution coefficient calculation unit 1103. The distribution coefficient calculation unit 1103 calculates the distribution coefficient α by, for example, [Equation 13].

[Equation 13]
α = 1− (V / Vc)

However, when Vc <V, the similarity corresponding to V = Vc, Vc: α = 0

According to [Equation 13], α is close to 1 when the similarity is large (when V is small), and α is close to 0 when the similarity is small (when V is large). When V is larger than Vc, α is 0. The reduction position correction amount calculation unit 115 calculates [Equation 10] using this α.

  As explained above, it can be effectively applied to the setup control of a tandem rolling mill.

100 Control Device for Tandem Rolling Mill 101 Control Command Setup Unit 102 Draft Schedule Storage Unit 103 Speed Pattern Storage Unit 110 Performance Collection Unit 111 Intermediate Plate Thickness Calculation Unit 112 Rolling Position Deviation Calculation Unit 113 Plate Thickness Deviation Calculation Unit 114 Rolling Position Correction Amount Calculation Gain storage unit 115 Roll-down position correction amount calculation unit 116 Roll-down position correction amount storage unit 1101 Steel plate layer storage unit 1102 Steel plate similarity calculation unit 1103 Distribution coefficient calculation unit

Claims (8)

A control apparatus for a tandem rolling mill, which controls a tandem rolling mill having a plurality of rolling stands and controls the thickness of a steel sheet continuously rolled by a work roll provided to the rolling stand to a desired value. And
When the steel sheet is rolled, the rolling position value of the work roll provided in each rolling stand is estimated using the rolling record value acquired in each of the plurality of rolling stands, and the estimated rolling position, A rolling position deviation calculating unit that calculates a rolling position deviation of the work roll at each rolling stand based on the actual rolling roll position value at each rolling stand obtained by the rolling;
A plate thickness deviation calculating unit that calculates a deviation between the target plate thickness of the steel plate and the plate thickness of the steel plate detected by a plate thickness measuring unit provided on the exit side of the rolling stand at the final stage of the tandem rolling mill;
A reduction position correction amount calculation gain storage unit for storing a reduction position deviation gain and a plate thickness deviation gain;
The reduction position deviation gain and the plate thickness deviation gain are acquired from the reduction position correction amount calculation gain storage unit, and the value obtained by multiplying the reduction position deviation and the reduction position deviation gain by the plate thickness deviation and the plate A rolling position correction amount calculating unit that calculates a rolling position correction amount at each rolling stand by adding a value multiplied by a thickness deviation gain;
Next, control is performed to calculate the reduction position of the work roll at each rolling stand for the steel sheet to be rolled, and to correct the calculated reduction position with the reduction position correction amount to calculate the reduction position set in each rolling stand. A command setup section;
A control apparatus for a tandem rolling mill. The reduction position correction amount calculation gain storage unit stores the reduction position deviation gain and the plate thickness deviation gain in association with at least one of a steel type, a target plate thickness, and a target plate width of the steel plate. The control apparatus of the tandem rolling mill according to claim 1. The reduction position deviation gain is a constant not less than 0 and not more than 1 that represents the importance of the reduction position deviation.
The tandem rolling mill control device according to claim 1 or 2, wherein the plate thickness deviation gain is a constant not less than 0 and not more than 1 representing importance of the plate thickness deviation of the steel plate. A rolling position correction amount storage unit that stores the rolling position correction amount calculated in the past rolling record in association with the steel type, target plate thickness, and target plate width of the steel plate for each stand;
The reduction position correction amount calculation unit includes a reduction position deviation calculated by the reduction position deviation calculation unit, a plate thickness deviation calculated by the plate thickness deviation calculation unit, and a past acquired from the reduction position correction amount storage unit. The rolling position correction amount output to the control command set-up unit is calculated from the rolling position correction amount calculated in the rolling of the tandem rolling mill according to any one of claims 1 to 3. Control device. The plate thickness of the steel plate detected by the plate thickness measuring unit provided on the exit side of the final rolling stand of the tandem rolling mill, and the roll speed that is the peripheral speed of the work rolls of the plurality of rolling stands. An intermediate plate thickness calculating unit that sequentially calculates an intermediate plate thickness, which is an entry side plate thickness of each of the plurality of rolling stands, from the final rolling stand to the upstream side;
When the rolling position deviation calculating unit calculates the rolling position of the work roll in the rolling based on the rolling performance of the rolled steel sheet, the rolling position deviation calculating unit uses the intermediate plate thickness calculated by the intermediate plate thickness calculating unit, The tandem rolling mill control device according to any one of claims 1 to 4, wherein a rolling position of the work roll in each of the rolling stands is estimated. A similarity number storage unit that stores a similarity number corresponding to a steel type of the steel sheet, as the similarity of the characteristics of the steel sheet increases,
A steel sheet similarity calculating unit that acquires the similarity number of each of the rolled steel sheet and the next rolled steel sheet from the similarity number storage unit, and calculates a difference between the two acquired similarity numbers as a similarity degree; ,
A distribution coefficient calculation unit that calculates a distribution coefficient that is a constant between 0 and 1 based on the calculated similarity;
The reduction position correction amount calculation unit adds the calculated reduction position correction amount and the reduction position correction amount calculated in the past rolling obtained from the reduction position correction amount storage unit by dividing the calculated distribution coefficient. The tandem rolling mill control device according to claim 4, wherein the rolling position correction amount is calculated from the calculated value and the plate thickness deviation calculated by the plate thickness deviation calculating unit. The distribution coefficient calculation unit calculates the distribution coefficient such that the smaller the similarity is, the larger the distribution coefficient is, and the larger the similarity is, the smaller the distribution coefficient is. The rolling mill control device described. A computer that controls a tandem rolling mill that continuously rolls steel plates with a plurality of rolling stands, when the steel plates are rolled, using the rolling record values obtained at each rolling stand of the plurality of rolling stands, In addition to estimating the rolling position of the work roll at each rolling stand, each rolling stand is based on the estimated rolling position at each rolling stand and the actual rolling position value at each rolling stand obtained by the rolling. A rolling position deviation calculating step for calculating a rolling position deviation at
A plate thickness deviation calculating step for calculating a deviation between the target plate thickness of the steel plate and the plate thickness of the steel plate measured on the exit side of the final rolling stand of the tandem rolling mill;
A value obtained by multiplying each rolling position deviation at each rolling stand calculated by the rolling position deviation calculating step by a rolling position deviation gain, and a sheet thickness deviation gain calculated by the plate thickness deviation calculating step. A reduction position correction amount calculating step for calculating a reduction position correction amount at each rolling stand by adding the multiplied values;
Next, for the steel sheet to be rolled, the work roll reduction position at each rolling stand is calculated, and the calculated work roll reduction position at each rolling stand is calculated by the reduction position correction amount calculation unit. A control command setup step for correcting with a rolling position correction amount at the rolling stand and calculating a rolling position to be set for each rolling stand using the corrected rolling position;
Run the tandem rolling mill control method.