JPH09201609A - Method for controlling thickness at the time of acceleration and deceleration in rolling and controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfactorily secure the accuracy of thickness at the time of acceleration and deceleration of rolling speed even when rolling in which strain rate is greatly varied is executed and even when a rolled stock whose deformation resistance is greatly varied to the variation of strain rate is rolled. SOLUTION: At the time of cold-rolling a metallic sheet, the variation ΔP of rolling load at the time of the acceleration and deceleration in rolling is estimated using a rolling-load variation estimating equation in which the coefficient μ of friction and deformation resistance Km are respectively taken as influence coefficients and, based on these estimated variation of rolling load, the correction of screw-down location in a rolling mill 1 is executed. And, by using the command value of rolling speed used for controlling rolling-speed as the parameter of the rolling speed in the rolling-load variation estimating equation, screw-down control without delay of control is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate thickness control method and a control device capable of effectively suppressing the plate thickness variation during the cold rolling of a metal plate during acceleration and deceleration of the rolling speed.

[0002]

[Related Background Art] When the rolling speed is accelerated or decelerated in cold rolling of a metal sheet, the coefficient of friction between the work roll and the rolled material changes with the change of the oil film thickness between the work roll and the rolled material. It is known that as a result, the rolling load fluctuates and a large plate thickness fluctuation occurs as compared with the steady rolling speed.

Conventionally, therefore, as disclosed in Japanese Patent Laid-Open No. 4-367309, a rolling load fluctuation predicting equation having a change coefficient of the friction coefficient as an influence coefficient is used for a rolling load fluctuation amount when the rolling speed is accelerated or decelerated. A technique has been proposed in which the fluctuation of the sheet thickness is predicted by predicting and correcting the rolling position by the roll with respect to the predicted fluctuation of the rolling load.

[0004]

However, in the case of the rolling load prediction method, since only the change of the friction coefficient is added to the prediction formula as the influence coefficient, for example, in the case of rolling in which the strain rate changes greatly, In the case of a rolled material whose deformation resistance is greatly affected by a change in strain rate, for example, a metallic material such as aluminum or copper, the rolling load prediction accuracy becomes very poor. As a result, there is a problem in that the plate thickness accuracy is deteriorated in the portion where the rolled material is accelerated and decelerated, and the so-called off-gauge region at the leading end portion and the tail end portion of the rolled material is increased accordingly.

Further, in the prior art, since the rolling load fluctuation amount which seems to have already changed is predicted and the strip thickness control is performed, it cannot be denied that a control delay of a predetermined control cycle occurs. That is, even if the rolling load prediction accuracy is improved, there is a problem that the plate thickness variation occurs due to the control delay and the tip off-gauge length of the rolled material increases. In this respect, JP-A-8-4
Japanese Patent No. 7708 discloses a method of compensating for a control response delay of a hydraulic pressure reduction system to improve the precision of reduction. However, even if this method is adopted, there is a problem in that the control delay of a predetermined control cycle, for example, one control cycle cannot be corrected.

The present invention has been made in consideration of such circumstances, and an object thereof is to carry out rolling such that the strain rate greatly changes, and to improve the plate thickness accuracy when the rolling speed is accelerated or decelerated. It is an object of the present invention to provide a strip thickness control method and control device in rolling that can sufficiently secure the number of off-cage portions.

[0007]

According to the sheet thickness control method of the present invention as set forth in claim 1, in cold rolling a metal sheet, fluctuations in rolling load at the time of accelerating and decelerating the rolling speed, the friction coefficient and the deformation. It is characterized in that the rolling load fluctuation prediction formulas in which the respective resistances are influence coefficients are used for prediction, and the rolling position in the rolling mill is corrected based on the predicted rolling load fluctuation amount.

In other words, not only the friction coefficient that has been conventionally used, but also the rolling load fluctuation prediction formula in which the fluctuation of the deformation resistance with respect to the speed change (strain speed change) is newly added as the influence coefficient is used to calculate the rolling load during acceleration / deceleration. Predict the amount of fluctuation,
By correcting the reduction position in the reduction device according to this prediction result, the effect of strain rate change is removed to suppress fluctuations in the delivery side plate thickness, and rolling is performed so that the rake plate thickness accuracy is sufficiently high during acceleration / deceleration. It is what

According to a second aspect of the present invention, there is provided a plate thickness control device for predicting a rolling load fluctuation, wherein a rolling load fluctuation amount ΔP at the time of accelerating and decelerating a rolling speed has a friction coefficient and a deformation resistance as influence coefficients. To convert the load change prediction amount calculated based on the rolling load fluctuation prediction formula into a roll gap correction amount ΔSk, and plate thickness compensation control according to the converted roll gap correction amount. And means for performing.

That is, the rolling load fluctuation amount ΔP is calculated by using the rolling load fluctuation prediction equations in which the coefficient of friction and the deformation resistance are influence coefficients, and the plate thickness control is performed according to the roll gap correction amount ΔSk obtained from the rolling load fluctuation amount ΔP. It is characterized in that the plate thickness accuracy is effectively increased with a simple control system by compensating the amount. Further, in the strip thickness control method according to the invention of claim 3, the rolling load fluctuation at the time of accelerating and decelerating the rolling speed is the rolling load fluctuation with the rolling speed after a predetermined control cycle indicated by the rolling speed command value as a parameter. This is characterized in that prediction is performed using a prediction formula, and the rolling position in the rolling mill is corrected based on the predicted rolling load fluctuation amount.

That is, as the rolling speed parameter in the rolling load fluctuation prediction formula, instead of the feedback signal of the rolling speed which is generally used in the past, the speed command value used for controlling the rolling speed of the rolling mill, that is, the predetermined value. By using the rolling speed that should be reached after the control cycle, the rolling load fluctuation that may occur after the predetermined control cycle is predicted with high accuracy and the rolling reduction control is performed.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of a plate thickness control method and control device according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing a schematic configuration of a rolling mill and its plate thickness control device. Rolling mill 1
A rolled material 3 mainly composed of a pair of work rolls 2 arranged to face each other vertically and guided between the work rolls 2.
Is rolled at a predetermined pressure. The rolling force applied between the work rolls 2 is applied by the rolling down device 5 under the control of the rolling down control device 4.

In the figure, 6 is a load cell for detecting the rolling load P between the work rolls 2, 7 is a pulse generator for detecting the rolling speed V (rotation speed) by the work rolls 2, and 8 is a deviation ΔH of the inlet side plate thickness. Is an X-ray thickness meter, and 9 is an X-ray thickness meter that measures the exit side plate thickness deviation Δh. The strip thickness control device for controlling the operation of the rolling mill 1 is an AGC.
A plate thickness control system 12 mainly including a calculation unit 11, a load change prediction calculation unit 14, and a roll gap correction calculation unit 1
5 and a calculator 16 as a main component. The AGC calculation unit 11 in the strip thickness control system 12 calculates the roll gap operation amount ΔSa so as to control the rolling mill 1 according to each data of the rolling load P, the entrance side strip thickness deviation ΔH, and the exit side strip thickness deviation Δh in the rolling mill 1. It is what you want. In addition, the rolling speed control unit 18 is a rolling speed command value at the time of accelerating and decelerating the rolling speed with respect to the work roll 2, that is,
The rolling speed Vs is set to be achieved after a predetermined control cycle (after one scan) from the present time.

On the other hand, the load change prediction calculation unit 14 in the calculation unit 16 uses the rolling speed V measured by the pulse generator 7 or the rolling speed command value Vs set by the rolling speed control unit 18, and the upper process. Predicting (calculating) the rolling load fluctuation amount ΔP in the rolling mill 1 based on a plate thickness value (target plate thickness) given from the computer 13 and other information about the material to be rolled based on a rolling / rolling load fluctuation prediction formula described later. Play a role. The roll gap correction calculation unit 15 obtains the roll gap amount ΔS to be set between the work rolls 2 based on the rolling load fluctuation amount ΔP predicted by the load change prediction calculation unit 14.

The plate thickness control system 12 basically outputs the roll gap operation amount ΔSa obtained by the AGC calculator 11 to the reduction control device 4 as the operation amount ΔS. The roll gap amount ΔS obtained by the arithmetic unit 16 is input as the plate thickness control compensation amount ΔSk, and the plate thickness control compensation amount ΔSk is added to the roll gap operation amount ΔSa by the adder 17 to perform the rolling reduction control. The operation amount ΔS for the device 4 is obtained.

Here, the calculation processing in the load change prediction calculation unit 14 and the roll gap correction calculation unit 15 will be described. In the load change prediction calculation unit 14, basically, a minute rolling speed in a certain speed range V is set. A minute rolling load change due to a change is predicted as follows.

[0017]

[Equation 1]

Here, P is the rolling load, ΔP is the minute rolling load change amount, V is the rolling speed measured by the pulse generator 7, and ΔV is the minute speed change amount. In the first embodiment of the present invention, two factors, a friction coefficient and a deformation resistance, are taken into consideration as a factor of the rolling load variation with respect to the velocity change, and the friction coefficient variation with respect to the velocity change and the deformation resistance variation with respect to the strain velocity variation. The following equations, where and are the influence coefficients, are derived from equation (1).

[0019]

[Equation 2]

Incidentally, the change of the friction coefficient with respect to the change of the rolling speed has the relationship as shown in FIG. 2 (a), and the change of the deformation resistance with respect to the change of the strain speed has the relationship as shown in FIG. 2 (b). , And the relationship between them is expressed by the following equation, for example.

[0021]

(Equation 3)

However, H is the entrance side plate thickness, h is the exit side plate thickness, R'is the flat roll diameter, and Km 'is the deformation resistance at zero speed [0], a, b, c, d. and e are constants. Therefore, by substituting the friction coefficient and the deformation resistance thus obtained into the above-described prediction formula, the model formula of the rolling load change with respect to the speed change can be obtained as follows.

[0023]

(Equation 4)

The load change prediction calculation unit 14 described above calculates (predicts) the minute rolling load change prediction amount ΔP when the rolling speed is V according to the load change prediction formula (5) obtained as described above. Then, the roll gap correction calculation unit 1
In 5, the minute rolling load change prediction amount ΔP calculated as described above is input, and the roll gap correction amount ΔSk is calculated as ΔS k = ΔP / K (6) with the mill constant of the rolling mill 1 as K. This roll gap correction amount ΔSk
Is added to the roll gap operation amount ΔSa obtained by the AGC calculation unit 11 of the plate thickness control system 12, and the operation amount for the reduction control device 4 is obtained as ΔS = ΔSa + ΔSk. The reduction device 5 is driven according to the operation amount ΔS, the gap between the work rolls 2 is adjusted, and the plate thickness is controlled.

As described above, according to the rolling control method and control apparatus of the present invention, not only the friction coefficient conventionally used but also the deformation resistance are taken into consideration as the factor of the rolling load fluctuation with respect to the speed change. , A rolling load fluctuation prediction formula is established with the coefficient of friction as a change in speed and the change in deformation resistance as a result of change in strain rate as influence coefficients. Then, based on this rolling load change prediction formula, the rolling load change amount with respect to a minute speed change when the rolling speed changes is predicted, and the rolling amount between the work rolls 2 in the rolling mill 1 is predicted according to this predicted rolling load change amount. Is to be corrected.

Therefore, in the case of rolling in which the strain rate changes greatly, or in the case of rolling a rolled material such as aluminum or copper whose deformation resistance is greatly affected by the change in strain rate. Also, it is possible to predict the rolling load variation when the rolling speed changes with high accuracy and control the plate thickness, and it is possible to improve the plate thickness accuracy. As a result, it is possible to shorten the off-gauge length at the leading end and the tail end of the rolled material 3.

FIG. 3 shows the variation in plate thickness during acceleration by comparing the conventional control method with the control method according to the present invention. As shown in this figure, according to the method of the present invention, the width (amplitude) of the plate thickness variation at the time of acceleration can be significantly reduced, and the length of the off-cage can be significantly reduced, as compared with the conventional method. You can Therefore, when the rolling speed changes at the time of starting or ending the rolling, that is, it is possible to effectively suppress the plate thickness variation at the time of accelerating and decelerating, and shorten the off-gauge length at the leading end and the tail end of the rolled material 3. As a result, the overall plate thickness accuracy can be improved and the yield can be improved. Moreover, according to the control method of the present invention, since the plate thickness control amount can be corrected without causing interference with the conventional general plate thickness control by the plate thickness control system 12 alone, it is added to the conventional system. It can also be incorporated into the system itself, and can also be incorporated into the conventional system itself.

By the way, in the above-described first embodiment, the rolling speed V determined by the pulse generator 7 is set.
The rolling load fluctuation amount was predicted based on the rolling load fluctuation prediction formula with the rolling speed parameter. However, the above rolling speed V
Instead of the work roll 2 in the rolling speed control unit 18,
The rolling load fluctuation amount may be predicted by using a rolling load fluctuation prediction formula having the rolling speed command value Vs used for controlling the peripheral speed as the rolling speed parameter.

Explaining the second embodiment,
Instead of the rolling speed V obtained by the pulse generator 7 as a feedback signal indicating the current rolling state,
Rolling mill 1 executed by the rolling speed control unit 18 shown in FIG.
The rolling speed control unit 1 controls the rolling speed that will change after the control cycle (after one scan) by
8 is obtained as the speed command value Vs. Then, based on the rolling load fluctuation prediction formula having the rolling speed (speed command value Vs) predicted to be reached one scan from the present time as a rolling speed parameter, the rolling load at the time when the rolling speed fluctuates by ΔV after one scan. The feature is that the fluctuation amount is predicted and the rolling reduction control is executed according to the predicted value.

More specifically, in the above-described first embodiment, the rolling speed Vo at the present time [To] and its 1
From the rolling speed V-1 measured before the control cycle [T-1] and the variation ΔV of the rolling speed in one control cycle, (Vo
-V-1), and the rolling load change amount ΔP, which may have fluctuated during this period, is predicted and the rolling reduction control is executed. However, in the second embodiment, the rolling speed V + 1 which will reach [T + 1] after one control cycle under the rolling speed control is set to the speed from the rolling speed control unit 18. Calculated as the command value Vs, and from the difference with the rolling speed Vo at the present time [To], the variation ΔV of the rolling speed during the next one control cycle is calculated as (V + 1−Vo), and it may fluctuate during this period. The rolling load change amount ΔP is predicted according to the above-described prediction formula. The rolling amount between the work rolls 2 in the rolling mill 1 is corrected according to the predicted rolling load change amount ΔP.

Thus, according to such predictive control, a change in the rolling speed at the time when the effect of correcting the reduction amount appears, the load change amount ΔP at that time is predicted and the reduction amount correction is performed. As shown in FIG. 4 (a), which shows the change in the rolling position over time, it is possible to bring the actual rolling movement closer to the ideal rolling control amount. In this respect, according to the predictive control according to the first embodiment described above, the load change amount ΔP at the present time is predicted based on the actual value of the rolling speed detected by the pulse generator 7, that is, the change amount ΔV of the rolling speed. Since the amount of reduction is corrected, it cannot be denied that the control delay of the reduction position occurs by the control period as shown in FIG. 4 (b).

Therefore, as shown in the second embodiment, if the rolling load fluctuation is predicted by using the speed command value Vs from the rolling control unit 18 as the rolling speed parameter, the control is performed in addition to the first embodiment. It is possible to suppress the response delay and perform highly accurate thickness control. Moreover, a feedback signal indicating the rolling speed (signal from the pulse generator 7)
Instead of, the speed command value V obtained from the rolling control unit 18
Only by using s as the rolling speed parameter, the strip thickness controllability can be dramatically improved. In addition, it is possible to effectively improve this, including the control delay of the hydraulic pressure reduction system.

The present invention is not limited to the above embodiment. For example, the relationship between the rolling speed and the friction coefficient and the relationship between the strain rate and the deformation resistance are expressed by using a relational expression other than the expressions (3) and (4) described above, and a rolling load fluctuation prediction expression is set up. good. As the rolling speed parameter used for predicting the load change, the rolling speed obtained from the pulse generator 7 is adopted, or the rolling speed control unit 18 is used.
It is also possible to adaptively select whether to adopt the speed command value obtained from In short, various modifications can be made without departing from the scope of the invention.

[0034]

As described above, according to the present invention, when the rolling speed changes, the compensation control for the plate thickness fluctuation is performed based on the rolling load fluctuation predicting equation having the friction coefficient and the deformation resistance as the influence coefficients. In the case of rolling such that the strain rate changes significantly, or even when rolling a rolled material whose deformation resistance is greatly affected by the change of strain rate,
It is possible to predict the rolling load fluctuation when the rolling speed changes with high accuracy and control the plate thickness, shorten the off-cage portion at the leading end and the tail end of the rolled material to improve the overall plate thickness accuracy, The effect that the yield can be improved is exhibited.

According to the invention of claim 3, in particular,
The rolling load fluctuation during acceleration / deceleration of the rolling speed is predicted by using the rolling load fluctuation prediction formula with the rolling speed after the predetermined control cycle indicated as the rolling speed command value as a parameter, so the control delay that anticipates the change It is possible to control the plate thickness with high accuracy. Therefore, it is possible to further improve the plate thickness accuracy and dramatically improve the production yield.

[Brief description of drawings]

FIG. 1 is a schematic block configuration diagram showing an embodiment of a plate thickness control device in a rolling mill according to the present invention.

FIG. 2 is a diagram showing a relationship between a rolling speed and a friction coefficient, and a relationship between a strain rate and a deformation resistance.

FIG. 3 is a view showing a deviation in plate thickness during acceleration by comparing the method of the present invention and the conventional method.

FIG. 4 is a diagram showing changes in the rolling position over time in comparison between a case where a rolling speed command value is used as a parameter in a rolling load fluctuation prediction formula and a case where a feedback signal is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolling mill 4 Rolling down control device 11 AGC calculation unit 12 Plate thickness control system 14 Load change prediction calculation unit 15 Roll gap correction calculation unit 18 Rolling speed control unit

Claims (3)

[Claims] 1. When cold rolling a metal sheet, rolling load fluctuations during acceleration and deceleration of rolling speed are predicted by using rolling load fluctuation prediction formulas having friction coefficient and deformation resistance as influence coefficients. A strip thickness control method at the time of acceleration / deceleration in rolling, characterized in that the rolling position is corrected based on the rolling load fluctuation amount. 2. A means for predicting a rolling load fluctuation amount ΔP at the time of accelerating and decelerating a rolling speed by using a rolling load fluctuation prediction formula having an influence coefficient of a friction coefficient and a deformation resistance, respectively.
A means for converting the load change prediction amount calculated based on the rolling load fluctuation prediction formula into a roll gap correction amount ΔSk, and a means for performing plate thickness compensation control according to the converted roll gap correction amount are provided. A characteristic plate thickness control device during acceleration / deceleration in rolling. 3. A rolling load fluctuation predicting formula, wherein the rolling load fluctuation during acceleration / deceleration of the rolling speed during cold rolling of a metal sheet is a parameter of the rolling speed after a predetermined control cycle indicated by a rolling speed command value. A method for controlling the plate thickness during acceleration / deceleration in rolling, characterized in that the rolling position is corrected based on the predicted rolling load fluctuation amount.