JP3521081B2 - Strip width control method in hot finishing mill - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip width control for a tandem rolling mill in which a plurality of stands are continuous, and more particularly, a target strip width can be obtained by changing a target value of a width gauge between stands online. The present invention relates to a method for performing plate width control.

[0002]

2. Description of the Related Art A conventional technique for width control in finish rolling will be described with reference to examples shown in FIGS. In FIG. 4, 21
Is a finish rolling mill consisting of 7 stands, 22 is a material to be rolled, 23 is an intermediate width gauge installed between F5 and F6 stands as an example, 24 is a final width gauge installed immediately before the winding device, and 25
Is a coiler.

As shown in FIG. 5, a target rolling width in a rolling mill is determined by adding a certain product width and a certain width (amount of target extra width). That is, the target width of the final width meter is set by product width + margin width. This extra width is determined by adding the cutting allowance, the thermal expansion allowance, etc. to the variation in the widthwise expansion caused by rolling, and it is finally discarded, so the extra width should be made as small as possible. It is important to control the plate width in order to improve the yield.

The target value of the intermediate width meter is set by adding the amount of width reduction between the intermediate width meter and the final width meter to the target set value of the final width meter. Accurately predicting this amount of width reduction is an important factor in setting the target width of the intermediate width meter, and eventually controlling the margin as desired.

In the conventional hot rolling, based on the variation of the rolling width caused by the variation of the slab width, the variation of the temperature unevenness due to the skid marks, and the amount of width deformation predicted from the rolling condition determined by the finish setup calculation,
The plate width was controlled by adjusting the opening of the vertical rolls (edgers) installed in the rough rolling mill group. For example, the technique described in Japanese Patent Laid-Open No. 5-285516 is a typical example.

Recently, a width control method in a finishing continuous rolling mill, particularly a plate width control method which positively utilizes tension between stands has been proposed for the purpose of further improving the yield. As shown in FIG. 4, tension feedback width control (FB-AWC) 26 and 27 for changing the tension between the upstream stands in order to eliminate the difference between the actual result of the intermediate width meter and the target set value is a generally known technique. Is.

For example, Japanese Unexamined Patent Publication No. 9-155422 discloses a hot continuous rolling mill that rolls a material to be rolled by a plurality of rolling stands while applying tension to the material, and is installed on the delivery side of the i-th rolling stand. In order to eliminate the plate width deviation between the measured plate width of the rolled material detected by the plate width meter and the target plate width set for the stand outlet side, the entrance side of the stand The change amount of tension is calculated by a function of the plate width deviation, the absolute value of the entrance side tension and the transfer time between stands, and the plate width is adjusted by feedback control to adjust the entrance side tension of the stand based on the tension change amount. A method of controlling is disclosed.

Further, Japanese Patent Laid-Open No. 5-285517 discloses a method for adjusting the strip width of a material to be rolled by changing the tension between two continuous rolling stands in a finish rolling mill. The difference between the measured value and the target value, the change in the strip crown ratio that is the difference in the strip crown ratio between the rolling stands before and after the rolling stand in each rolling stand, and the tension change amount is set based on the rolling conditions. On the other hand, the crown control in the rolling stand to calculate the fluctuation amount of the rolling load and the fluctuation amount of the plate crown ratio change expected in each rolling stand and to compensate the fluctuation amount of the plate crown ratio change based on both fluctuation amounts. A plate width control method is disclosed in which the operation amount of the means is set and the crown control means is operated together with the change of the tension.

[0009]

However, in the conventional width control method in the finish rolling mill, the following problems have not been solved.

First, as described above, the target set value of the intermediate width meter is set by adding the width shrinkage amount between the intermediate width meter and the final width meter to the target set value of the final width meter. This width shrinkage amount is the width shrinkage amount estimated using the width model from the rolling conditions determined by the setup calculation of the normal finish rolling, and the setup calculation error and the width model error are directly included in the intermediate width meter target value set value.

Therefore, by changing the tension as described in JP-A-5-285517 and JP-A-9-155422, it is possible to control the actual performance of the intermediate width meter as shown in FIG. However, since the width shrinkage amount during actual rolling is different from the estimated shrinkage amount, the actual result of the final width gauge may be wider than the target value by ΔW as shown in the figure.

Secondly, during actual rolling, the amount of width shrinkage between the intermediate width gauge and the final width gauge is not a constant value, but fluctuates according to changes in rolling conditions. For example, as shown in FIG. 5, the width reduction amount of the intermediate width gauge to the final width gauge gradually increases with the accelerated rolling. However, the target value of the conventional intermediate width gauge is set before rolling and does not change during rolling, so even if the actual results of the intermediate width gauge can be controlled as desired by changing the tension as described above,
There is a problem that the final width does not reach the target because the width deformation after the intermediate width meter gradually increases unlike the predicted value.

In order to solve such a problem, as shown in FIG. 4, the tension between a plurality of stands including the finishing final stand is corrected so as to eliminate the difference between the actual value of the final width meter and the target value. There is so-called monitor AWC control. However, in this control, the control gain cannot be increased largely because the distance from the tension operation position to the final width meter is long and the dead time is long. Therefore, there is still a problem that it takes time until the actual result of the final width meter can be controlled to the target value, and the surplus plate width during that time cannot be effectively reduced.

Thirdly, when the looper tension is operated on the basis of the signal of the intermediate width meter to control the width, the rolling load of the front and rear stands is changed by the change of the tension, so that the stand entrance / exit side plate crown ratio and the exit side plate. Thickness varies. For example, when the stand tension is increased to reduce the width, the rolling load is reduced in both the front and rear stands, the plate crown ratio fluctuates in the positive direction (medium elongation), and the delivery side plate thickness becomes thin. These effects must be compensated for while controlling the strip width.

In Japanese Patent Laid-Open No. 285517/1993, the compensation of the variation of the plate crown ratio by the tension operation is considered, but the influence of the tension operation on the plate thickness is not considered. Therefore, the plate thickness fluctuation due to the tension operation becomes a disturbance of the width control, which slows down the response of the width control and causes overshoot, so that the width control cannot be controlled as expected and there is a large margin. There are also problems such as having to take.

The present invention has been made in view of the above circumstances, and provides a hot finish rolling mill capable of accurately controlling the final strip width value to be close to the target value even if the rolling state changes during rolling. An object is to provide a plate width control method.

[0017]

A first means for solving the above-mentioned problems is a width gauge (intermediate width) installed between arbitrary stands of a hot finish rolling mill consisting of a plurality of stands or on the exit side of the finish rolling mill. In the width control using the width gauge (final width gauge) installed immediately before the winder (coiler), the actual width of the final width gauge is estimated from the measured width of the intermediate width gauge, and the estimated value and the final width are measured. A strip width control method for a finish rolling mill (claim 1), characterized in that the target value of the intermediate width gauge is changed based on a difference from the target set value of the width gauge.

In this means, the actual result of the final width meter is estimated in real time from the measured width value of the intermediate width meter, and the target setting of the intermediate width meter is set based on the difference between this estimated value and the target setting value of the final width meter. Since the value is changed, it is possible to accurately correct the width deformation amount of the intermediate width gauge to the final width gauge according to the change of the rolling condition and obtain a highly accurate finishing width.

A second means for solving the above problems is
In the first means, the width deformation model used when estimating the actual result of the final width meter from the intermediate width meter is the intermediate width meter actual result of the rolling tip (unsteady part), the final width meter actual result, and the intermediate width. Characterized by performing on-line identification using the tracking data of the rolling record of each stand on the total width meter to the final width gauge, and performing width control of the intermediate portion (steady portion) of rolling using the identified model (claim Item 2).

In the present means, the width deformation model used when estimating the actual result of the final width meter from the intermediate width meter is used as the intermediate width meter actual result of the rolling tip (unsteady part), the final width meter actual result, and the intermediate width meter. ~ Since it is identified online by using the tracking data of the rolling record of each stand in the final width meter, the target setting error of the intermediate width meter due to the width model error can be corrected. Further, since the width control is performed from the intermediate portion (steady portion) of rolling using the identified model, the width variation in the steady rolling portion is suppressed.

A third means for solving the above problems is
In the first means or the second means, by operating the tension of one or a plurality of loopers on the upstream side of the intermediate width meter, the difference between the actual result of the intermediate width meter and the target set value is reduced to 0. The roll bender pressure of the front and rear stands is corrected and compensated for the rolling load fluctuation of the front and rear stands and the crown ratio fluctuation of the entrance and exit sides caused by the looper tension operation. The variation in the outlet plate thickness of the front / rear stand caused by the above is compensated by the roll pressure reduction position adjustment of the corresponding stand (claim 3).

In this means, when the tension between the stands is controlled to control the difference between the actual result of the intermediate width meter and the target set value to be 0, the bender pressures of the front and rear stands and the roll reduction positions are simultaneously operated. Therefore, it compensates for the variation in plate thickness and plate crown ratio caused by the tension operation,
It is possible to realize highly precise plate width control without affecting the plate thickness and plate crown.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing an example of the configuration of a control device for carrying out the width control method of the present invention. FIG. 1 shows the part from the F5 stand to the coiler in the latter stage of the finishing continuous rolling mill consisting of seven stands. In this embodiment, an intermediate width meter is installed between the F6 and F7 stands, and width feedback control is performed by a tension operation between the F5 and F6 stands. In FIG. 1, 1 is an intermediate width gauge, 2 is a final width gauge installed immediately before the coiler, 3 is F5 and F6.
The fifth looper controller between the stands, 4 and 5 are the reduction controllers AGC, 6 and 7 of the F5 and F6 stands, respectively.
Are roll bender controllers for F5 and F6 stands, respectively.

Reference numeral 8 is a rolling information performance collecting and data tracking device, 9 is a width deformation model online identification device, and 10
Is a final width estimation device, 11 is an intermediate width meter target value changing device, 1
Reference numeral 2 is an automatic width control device (AWC), which are control devices for realizing the plate width control of the present invention. FIG. 2 shows an image of a control result using the control system shown in FIG. 1, and FIG. 3 shows a flow of control processing.

In carrying out the width control method of the present invention, during rolling, the rolling results (sheet thickness, reduction rate, tension, load, bender pressure, temperature ,
The intermediate width, the final width, etc.) are sampled and collected by the rolling information performance collection and data tracking device 8. The rolling information record collection and data tracking device 8 divides these data at equal intervals in the longitudinal direction of the material to be rolled and sequentially tracks the data up to the final width meter of each stand.

When the material to be rolled of a certain length passes through the final width meter, the data of that portion is transmitted to the width deformation model online identification device 9. The width deformation model online identification device 9 uses these data to identify the width deformation model prepared in advance. As shown in FIG. 2, this tip portion is called a model identification area. The width control is performed from the identification area and thereafter. However, the length of the identification area and the pitch length of the tracking data are not specified.

In the final width estimation device 10, the width result in the final width meter is predicted in real time from the measured value of the intermediate width meter and the rolling results after the F7 stand based on the identified model. In the intermediate width meter target value changing device 11 of FIG. 4, the target value of the intermediate width meter is changed based on the difference between the predicted value of the final width meter and the target set value. The width target value may be changed in batch or in real time.

The automatic width feedback control is implemented by an automatic width controller (AWC) 12. The automatic width controller (AWC) 12 calculates the difference between the measured value of the intermediate width meter and the changed target value, and outputs a target tension correction command to the looper controller 3 so as to eliminate this difference. In order to compensate the plate crown ratio variation and the outlet plate thickness variation caused by this tension correction, a bender pressure correction command and a pressure reduction correction command are output to the bender pressure control device and the pressure reduction control device AGC of the F5 and F6 stands, respectively. As a result of the series of operations, the target value of the intermediate width meter is changed and the automatic width control AWC for reducing the error of the intermediate width meter to 0 is performed as shown in FIG.
The final width will be controlled as desired.

As shown in FIG. 2, control is not performed in the model identification area, but when the model identification is completed, the target value of the intermediate width meter is corrected by the model error correction amount and the width control is started. Therefore, the actual value of the final width meter is kept close to the target value accordingly. After that, actual values are collected as the steel sheet passes, and based on the model identified by the final width estimation device 10, the width result in the final width meter is obtained from the measured value of the intermediate width meter and the rolling results after the F7 stand. Predict in real time. In the intermediate width meter target value changing device 11 of FIG. 4, the target value of the intermediate width meter is changed based on the difference between the predicted value of the final width meter and the target set value.
Therefore, even if the state of the rolling mill changes due to accelerated rolling, etc.,
As shown in FIG. 2, the target set value of the intermediate width meter is changed accordingly, and the final width meter measurement value is kept near the target value.

Next, a calculation algorithm relating to the width control method of the present invention will be described. In model identification, the width deformation model of the intermediate width meter to the final width meter is expressed by the following formula.

[0031]

[Equation 1]

Here, W _c and W _m : measured value of final width meter and measured value of intermediate width meter ΔW ₁ (7): Width spread by rolling at F7 stand ΔW ₂ (7): F7 stand entrance side rolling force Effect on width spread ΔW ₃ (7): Effect of crown ratio change on F7 stand entry / exit side ΔW ₄ (6): Creep deformation due to tension between F6 and F7 stands ΔW ₄ (7): F7 stand exit side ~ Creep deformation ΔW ₅ due to tension between coilers: width reduction due to temperature drop between F6 stand exit side and coiler.

There are some known methods for calculating the formulas and calculating methods for the above items, but the present invention is not particularly limited thereto. The reduced rolling length at each stand is calculated as follows.

[0034]

[Equation 2]

[0035] In this case, L _i is equivalent length of the side plate rolling length out Fi stand, h _i the side plate thickness out of Fi stand, v _i is the side plate speed out of the Fi stand, t is the elapsed time of Fi stand rolling.

The data are rearranged in the rolling longitudinal direction to calculate the respective influence terms of the width deformation, and the data are divided at equal intervals to create the following N sets of data. Explanatory variable data:

[0037]

[Equation 3]

Data of dependent variables: ΔW (1) ΔW (2) ... ΔW (j) ... ΔW (N) However, the identification method of the ΔW = ΔW _c −ΔW _m model is not particularly limited. Such a linear least squares method may be used. In this case, the following regression equation is set using the width deformation model as a linear function.

[0039]

[Equation 4]

However, ω (j) is a noise term. The following vectors are set for N sets of data.

[0041]

[Equation 5]

However, x ₀ is an offset amount, and ω
It represents the stationary component of (j). Then, equation (3) is expressed as follows.

[0043]

[Equation 6]

Evaluation function

[0045]

[Equation 7]

The estimation formula of the unknown parameter that minimizes is as follows.

[0047]

[Equation 8]

Estimated here

[0049]

[Equation 9]

Is a width influence coefficient in each stand.
That is, a: Width of F7 stand / influence coefficient of rolling reduction b: Width of F7 stand / influence of rear tension c: Width of F7 stand / influence coefficient of plate crown ratio d: Width between F6 and F7 stands / influence of front tension Coefficient e: F7, width between coilers / front tension influence coefficient f: width / temperature drop influence coefficient. In the final width estimation, the final width is estimated from the measured value of the intermediate width meter and the rolling record using the identified width model. That is, using the estimated x ₀ , a to f,

[0051]

[Equation 10]

Incidentally,

[0053]

[Equation 11]

[0054] is an estimate of the final _{width, ΔW 1 (7) = F} 1 (H, W, r 7) ΔW 2 (7) = F 2 (H, W, r 7, σ b7, k m) ΔW ₃ (7) = F ₃ (P ₇ , B ₇ , h ₇ ) ΔW ₄ (6) = F ₄ (T ₆ , σ _f6 , t ₆ ) ΔW ₄ (7) = F ₄ (T ₇ , σ _f7 , t ₇ ) ΔW ₅ = F ₅ (W, T ₆ , T _c ).

[0055] In these formulas, H is finished thickness at entrance side, W is finished target width, _{P 7} is F7 stand rolling load,
B ₇ is F7 stand roll bender pressure, _{r 7} is F7 stand reduction ratio, _{k m} is the deformation resistance of the material, _{h 7} is delivery side thickness F7 stand, sigma _b7 is F7 stand behind tension, sigma _f6 is F
6 stand front tension, σ _f7 is F7 stand front tension,
t ₆ is F6 stand ~F7 Sudando between transit time, _{t 7} the time passed between F7 stand-coiler, _{T 6} is, F6 stand delivery temperature, _{T 7} is the F7 stand delivery temperature, _{T c} is a coiler temperature before . Regarding the change of the target value of the width meter, the error between the estimated value of the final width meter and the target value is calculated by the following formula.

[0056]

[Equation 12]

In order to eliminate this error value, the target value of the intermediate width meter is changed as follows. _{W mref = W mset -ΔW c ...} (9) However, [Delta] W _c: estimate the final width meter and error _W of a target setpoint _cset: target setpoint final width meter _{W mset} intermediate width meter setpoint W _mref : Target value of intermediate width meter after change

In the automatic tension feedback width control (AWC) using the intermediate width meter, the deviation ΔW _m between the measured value W _m of the intermediate width meter and the target value W _mref is calculated by the following formula. ΔW _m = W _m −W _mref (10) For example, in order to manipulate the tension between the F5 and F6 stands to eliminate this deviation, the tension correction amount obtained by the following equation is required.

[0059]

[Equation 13]

However, ∂σ ₅ / ∂W is the tension of 5 loopers
/ Width influence coefficient. When the tension of 5 looper is changed by the correction amount of the above formula, the rolling load of F5 stand and F6 stand decreases and the plate crown ratio fluctuates. The variation is approximately as follows.

[0061]

[Equation 14]

However, in equations (12) and (13), ΔCi, Δ
Pi, ∂C _i / ∂P, ∂P _i / ∂σ _f , ∂P _i / ∂σ _b
Are the plate crown ratio variation of the i-stand, rolling load variation, crown ratio / load influence coefficient, load / front tension influence coefficient, and load / rear tension influence coefficient, respectively.

The above-mentioned fluctuations in the crown ratio may cause further width deformation and must be compensated. In order to compensate, any of the bender pressure of the rolling roll, the cross angle of the upper and lower rolls, the position shift of the upper and lower rolls, etc. may be operated, and the operating means is not particularly limited in the present invention. For example, when the bender pressure is operated to compensate the plate crown ratio variation, the bender pressure correction amount of the front and rear stands can be obtained as follows. However. Δ
B _iref and ∂B _i / ∂C are the bender pressure correction amount of the i stand and the roll bender pressure / plate crown influence coefficient, respectively.

[0064]

[Equation 15]

Further, when the tension correction amount of the equation (11) is applied with 5 loopers, the rolling loads of the F5 stand and the F6 stand change, and the delivery side plate thickness changes. The fluctuation amount can be approximately calculated by the following formula. F5 stand front tension tension variation on the outlet plate thickness:

[0066]

[Equation 16]

F6 stand rear side tension variation due to outlet tension:

[0068]

[Equation 17]

It is necessary to compensate for the above-mentioned variation in plate thickness by the rolling-down controller AGC provided in each stand, and the plate thickness correction command for the F5 and F6 stands is obtained as follows.

[0070]

[Equation 18]

However, in equations (16) to (19), Δh
_AGC5 and Δh _AGC6 are the AGC plate thickness modification command values ∂h ₅ / ∂σ _f of the F5 and F6 stands, respectively, and the outgoing plate thickness / front tension influence coefficient ∂h ₆ / ∂σ _b of the F5 stand are the F6 stand. Shown is the exit side plate thickness / rear tension effect coefficient.

[0072]

As described above, according to the present invention,
It is possible to provide a strip width control method for a hot finish rolling mill that can accurately control the final strip width value to be close to the target value even if the rolling state changes during rolling.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a configuration of a control device that implements a width control method of the present invention.

FIG. 2 is a diagram showing an image of a control result using the control system shown in FIG.

FIG. 3 is a diagram showing a flow of control processing in the control system shown in FIG.

FIG. 4 is a block diagram showing an example of a configuration of a control device that implements a conventional width control method.

5 is a diagram showing an image of a control result using the control system shown in FIG.

[Explanation of symbols]

1: Intermediate width meter 2: Final width meter 3: Fifth looper controller between F5 and F6 stands 4-5: Automatic plate thickness controller for F5 and F6 stands (AG
C) 6 to 7: V5 and F6 stand vendor control device 8: Rolling information performance collection and data tracking device 9: Width deformation model online identification device 10: Final width estimation device 11: Intermediate width gauge target value changing device 12: Automatic width controller AWC

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-10-263648 (JP, A) JP-A-63-199010 (JP, A) JP-A-57-139414 (JP, A) JP-A-5- 285517 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 37/00-37/78 G05B 13/02 G05B 13/04

Claims (3)

(57) [Claims] 1. A width gauge (intermediate width gauge) installed between arbitrary stands of a hot finish rolling mill consisting of a plurality of stands or on the exit side of the finish rolling mill, and a width gauge installed immediately before a winding device (coiler) ( In the width control using the final width meter, the actual width of the final width meter is estimated from the measured width value of the intermediate width meter, and the target of the intermediate width meter is based on the difference between this estimated value and the target setting value of the final width meter. A strip width control method for a finishing rolling mill, characterized by changing a value. 2. The strip width control method for a finish rolling mill according to claim 1, wherein the width deformation model used when estimating the actual performance of the final width gauge from the intermediate width gauge is used for the rolling tip portion (unsteady portion). The width of the middle part (steady part) of the rolling is identified online by using the tracking data of the results of the intermediate width gauge, the final width gauge, and the rolling results of each stand in the intermediate width gauge to the final width gauge. A strip width control method for a finish rolling mill, which comprises performing control. 3. The strip width control method for a finish rolling mill according to claim 1 or 2, wherein 1 is provided upstream of the intermediate width gauge.
By controlling the tension of one or more loopers, the difference between the actual result of the intermediate width meter and the target set value is controlled to be zero, and at that time, the rolling load fluctuation of the front and rear stands caused by the looper tension operation. , And the variation of the crown ratio of the inlet / outlet side by correcting the roll bender pressure of the front / rear stand respectively, and the variation of the outlet plate thickness of the front / rear stand caused by the looper tension operation is compensated by the roll pressure reduction position adjustment of the corresponding stand. A strip width control method for a finish rolling mill.