JP2001340909A - Controlling equipment and controlling method for tandem rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controlling equipment and controlling method for a tandem rolling mill having good maintenance property at a low cost and also obtaining a high quality strip. SOLUTION: A first model 11 is expressed by the equation dΔPB/dt=(-1/ TB)ΔPB+KB/TB.ΔUB. ΔCM=KC.ΔPB, in which a control amount of rolling stands 1 to 4 and an actual adjusting amount are ΔUB and ΔPB respectively, and a calculated fluctuating value of a crown profile of a plate is ΔCM. However, KB and TB are a gain and time constant when the adjusting amount ΔPB is approximated by a primary delay corollary. KC is an influence coefficient of which the crown profile of a plate is influenced by the adjusting amount. A second model 12 is expressed by ΔCS=ΔCM.e-LS, in which the calculated fluctuating value of the crown profile of the plate directly under a crown meter 5 is ΔCS and detection idling time of the crown meter 5 is L. More precise control of the crown profile of the plate can be performed upon use of these models 11 and 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control of a tandem rolling mill for controlling a tandem rolling mill having a plurality of rolling stands, each of which has an adjusting means for adjusting a strip crown of a strip. The present invention relates to an apparatus and a control method.

[0002]

2. Description of the Related Art In a tandem rolling mill that rolls a strip with a plurality of rolling stands, a plate shape (a shape in a plate longitudinal direction generated by a difference in length between a plate width center portion and a plate end portion).
In addition, controlling the sheet crown (shape in the sheet width direction caused by the sheet thickness difference between the sheet width center part and the sheet edge part) is an important issue for ensuring product quality, and various methods have been conventionally proposed. Have been. For example, Japanese Patent Publication No. Hei 8-15610 discloses that, based on a static model representing a change in plate shape and plate crown at each rolling stand, a plate crown detected further downstream of the most downstream rolling stand is corresponded. A technique for calculating an adjustment amount of each rolling stand is disclosed.

Further, Japanese Patent Publication No. 4-72603 discloses that
Based on the plate crown ratio detected further downstream of the most downstream rolling stand, the adjustment amount of each rolling stand is calculated so that the correction amount of the plate crown ratio is equal in all the rolling stands, and the adjustment amount and the plate shape are calculated. A technique of adjusting each rolling stand based on the sum of the amount of adjustment and the amount of adjustment of each rolling stand is disclosed.

[0004]

[Problems to be solved by the invention]
In the method described in Japanese Patent No. 15610, although the control effect in the steady state is taken into consideration, the influence in the so-called transient state in which the strip moves between the rolling stands at the time of adjustment in which the sheet crown target value or the like is changed is taken into consideration. It has not been. For this reason, the change in the plate shape during the movement of the strip at the time of the adjustment is unexpected, and there is a possibility that a defect such as distortion is generated particularly in a thin plate material and the quality is reduced.

[0005] Further, when the sheet crown is detected further downstream of the most downstream rolling stand, there is a dead time before the adjustment result of each rolling stand is reflected on the detected value of the sheet crown. If this detection dead time is not taken into account, over-control will be performed by controlling the next cycle before the control effect is detected, or conversely, the control cycle will be slowed down to prevent over-control or unnecessarily. There is a problem that the control performance is deteriorated as a result of lowering the control gain or the like.

Japanese Patent Publication No. 8-15610 does not consider the effect of the detection dead time at all, and
JP-A No. 2603 describes that it is desirable to consider the detection dead time, but does not disclose any specific method. In addition, if a crown meter is individually provided immediately downstream of each rolling stand, the above detection dead time can be shortened and control accuracy can be improved, but the crown meter is extremely expensive and maintenance problems are taken into consideration. It is desirable to control the plate crown and plate shape with less crown meter.

Therefore, the present invention can control the strip crown and strip shape of the strip with high accuracy even by providing only one strip crown detecting means such as a crown meter, and, consequently, low cost and maintainability. An object of the present invention is to provide a control device and a control method for a tandem rolling mill capable of obtaining a good and high-quality strip.

[0008]

In order to achieve the above object, the invention according to claim 1 comprises a plurality of rolling stands, each of which adjusts a strip crown of a strip. A tandem rolling mill control device having an adjusting means for controlling the tandem rolling mill, at least further downstream of the most downstream rolling stand, a sheet crown detecting means for detecting a sheet crown of the strip, The rate of change and the delay time when the strip crown of the strip actually changes after controlling each of the adjusting means, and the delay required for movement of the strip from the most upstream rolling stand to the strip crown detecting means. A model defining the correspondence between the control amount of each of the adjusting means and the change amount of the plate crown based on time; Control amount calculating means for calculating a control amount of each of the adjusting means based on the correspondence defined by the above and the sheet crown detected by the sheet crown detecting means, and a time required for moving the strip between the rolling stands. And delay input means for individually delaying and inputting the control amounts calculated by the control amount calculating means to the respective adjusting means.

In the present invention thus constructed, the strip crown detecting means detects the strip crown of the strip further downstream of the most downstream rolling stand. Further, the model defines the correspondence between the control amount of the adjusting means provided in each rolling stand and the change amount of the sheet crown as follows. That is, the rate of change and the delay time when the strip crown of the strip actually changes after controlling each of the adjusting means, and the delay time required for the movement of the strip from the most upstream rolling stand to the strip crown detection means. Based on this, the correspondence between the control amount of each adjusting means and the change amount of the plate crown is defined.

The control amount calculating means calculates the control amounts of the respective adjusting means based on the correspondence defined by the model and the sheet crown detected by the sheet crown detecting means. For this reason, the control amount calculated by the control amount calculating means includes a rate of change (a so-called delay system gain) and a delay time (a so-called delay system) when the strip crown of the strip actually changes after controlling each adjusting means. ) And the delay time required to move the strip from the most upstream rolling stand to the strip crown detecting means (so-called detection dead time). Very good feedback control can be performed. In addition, by controlling the plate crown with an appropriate change amount, the plate shape can be well controlled.

In the present invention, the control amount calculated in this manner is input to the respective adjusting means with a delay individually by the delay input means based on the time required for moving the strip between the rolling stands. . Therefore, according to the present invention, the strip crown and the strip shape of the strip can be controlled with high accuracy, and a high-quality strip can be obtained. In addition, since at least one sheet crown detecting means may be provided, the rolling of the strip can be reduced in cost and the maintenance property can be improved.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the model comprises a control amount Δu of each of the adjusting means.
It is characterized in that the change amount ΔC _S of the plate crown corresponding to _B is associated with the following equation.

[0013]

(Equation 3)

[0014] _{ΔC M = K C ΔP B ΔC} S = ΔC M · e -LS However, variable representing [Delta] P _B is the amount of adjustment by the adjusting means of the rolling stand time t as a parameter, K _B and T _B are the A gain and a time constant when the adjustment amount is approximated by a first-order lag system, K _C is an influence coefficient of the adjustment amount on the sheet crown, and L is a dead time detected in the sheet crown detection.

The applicant of the present invention has controlled each of the above adjusting means.
Later, when the strip crown of the strip actually changes,
When the ratio is approximated by a first-order lag system,
K _B And the influence coefficient K of the above adjustment amount on the sheet crown
_C And the delay time of the change is
Time constant T_B At the top of the rolling stand,
Detects delay time required to move strip to delivery means
When each is associated with the dead time L,
Control amount Δu_B And the change amount ΔC of the above-mentioned sheet crown_SCorrespondence with
The relationship states that it is very well defined by:
I saw.

[0016]

(Equation 4)

ΔC _M = K _C ΔP _B (2) ΔC _S = ΔC _M · e- ^LS (3) where ΔP _B is the amount of adjustment by the adjusting means of the rolling stand with time t as a parameter. Is the variable to represent.

In the present invention, since the model that defines the above-mentioned correspondence by the equations (1) to (3) is used,
In addition to the effects of the invention described in claim 1, the strip crown and the strip shape of the strip can be controlled with higher accuracy,
There is an effect that a higher quality strip can be obtained.

The third aspect of the present invention is the first or second aspect.
In addition to the configuration described above, the rate of change and the delay time when the strip crown of the strip actually changes after controlling each of the adjusting means, and the distance from the most upstream rolling stand to the strip crown detecting means, An input unit for inputting at least one of the delay time required for the movement of the strip to the model is further provided.

In the present invention, the input means, K in the ratio (aspect 2 of the change when the strip crown actually said strip after controlling the respective adjustment means varies _B, K
_C ) and the delay time (T _B in claim 2), and
At least one of a delay time (L in claim 2) required for moving the strip from the most upstream rolling stand to the strip crown detecting means can be input to the model. For this reason, even if the above parameters change due to the material of the strip or the aging or improvement of the rolling stand, it is possible to satisfactorily respond by inputting appropriate values of the parameters from the input means. Therefore, according to the present invention, in addition to the effects of the first and second aspects of the present invention, there is an effect that the material of the strip and the rolling stand can be flexibly changed over time and improved.

According to a fourth aspect of the present invention, there is provided a tandem rolling mill for controlling a tandem rolling mill having a plurality of rolling stands and each of the rolling stands having adjusting means for adjusting a strip crown of a strip. A method for detecting a strip crown of the strip at least further downstream of the most downstream rolling stand, and controlling a rate of change when the strip crown of the strip actually changes after controlling the adjusting means. And a delay time, and a correspondence relationship between the control amount of each of the adjusting means and the amount of change in the sheet crown based on the delay time required for movement of the strip from the most upstream rolling stand to the sheet crown detection position. Using a specified model, control of each of the adjusting means based on the correspondence defined by the model and the detected plate crown. Calculating the amount, based on the time required for movement of the strip between the respective rolling stand, the control amount of the calculated is characterized by inputting individually delayed to the respective adjusting means.

In the method of the present invention, the strip crown of the strip is detected further downstream of the most downstream rolling stand.
Further, the model used in the present invention defines the correspondence between the control amount of the adjusting means provided in each rolling stand and the change amount of the sheet crown as follows. That is, the rate of change and the delay time when the strip crown of the strip actually changes after controlling each of the adjusting means, and the delay time required for the movement of the strip from the most upstream rolling stand to the detection position of the strip crown. The correspondence between the control amount of each adjusting means and the amount of change of the plate crown is defined based on

In the present invention, the control amount of each of the adjusting means is calculated based on the correspondence defined by the model and the detected plate crown. The control amount calculated in this manner includes the rate of change (so-called delay-based gain) and the delay time (so-called delay-based time constant) when the strip crown of the strip actually changes after controlling each adjusting means. In addition, the delay time required to move the strip from the most upstream rolling stand to the detection position of the strip crown (so-called detection dead time) is reflected. Feedback control can be performed. In addition, by controlling the plate crown with an appropriate change amount, the plate shape can be well controlled.

In the present invention, the control amount calculated in this manner is input to each adjusting means with a delay individually based on the time required for the strip to move between the rolling stands. Therefore, according to the present invention, the strip crown and the strip shape of the strip can be controlled with high accuracy, and a high-quality strip can be obtained. Moreover, since the detection of the strip crown only needs to be performed at at least one location, the rolling of the strip can be reduced in cost and the maintainability can be improved.

According to a fifth aspect of the present invention, in addition to the configuration of the fourth aspect, the model comprises a control amount Δu of each of the adjusting means.
It is characterized in that the change amount ΔC _S of the plate crown corresponding to _B is associated with the following equation.

[0026]

(Equation 5)

The _{ΔC M = K C ΔP B ΔC} S = ΔC M · e -LS However, variable representing [Delta] P _B is the amount of adjustment by the adjusting means of the rolling stand time t as a parameter, K _B and T _B are the A gain and a time constant when the adjustment amount is approximated by a first-order lag system, K _C is an influence coefficient of the adjustment amount on the sheet crown, and L is a dead time detected in the sheet crown detection.

[0028] As described with respect to claim 2, the present applicant, the correspondence relation between the change amount [Delta] C _S of the controlled variable Delta] u _B and the strip crown for each adjusting means, the above-mentioned formula (1) - (3 )
Has been found to be very well defined by: In the present invention, since the model that defines the above-mentioned correspondence by the above-mentioned equations (1) to (3) is used, in addition to the effect of the invention described in claim 4, the strip crown and the strip shape of the strip are further increased. The effect is obtained that the control can be performed with high precision and a strip of higher quality can be obtained.

[0029]

Next, an embodiment of the present invention will be described with reference to the drawings. Although the following embodiments will be described by taking hot rolling as an example, the present invention is also applicable to cold rolling. FIG. 1 is an explanatory diagram illustrating a configuration of a tandem rolling mill to which the present invention is applied and a control system thereof. As shown in FIG. 1 to N
o. 4 is provided with rolling stands 1 to 4, and further downstream of the most downstream rolling stand 4, a crown meter 5 for measuring the strip crown of the strip S, and winding up of the strip S after the strip crown measurement. Machine 7.

Each of the rolling stands 1 to 4 has a quadruple roll 1
, 4a to 4d, and various vendors as adjusting means, such as an increment vendor (not shown) for adjusting the end bearing interval of the middle two work rolls 1a to 4a, 1b to 4b. ing. In the following description, a case will be mainly described in which a vendor is used as the adjusting means. However, the same control can be performed when another actuator such as a VC roll is used as the adjusting means. These actuators change the bending force and the like in accordance with a control command from the control device 10 described below, and adjust the strip crown of the strip S.

The control device 10 includes a first model 11 representing the rate of change of the sheet shape and the sheet crown after controlling the bender and a time delay, and a crown meter from the outlet side of the most upstream rolling stand 1. Second model 1 representing delay time up to 5
2, control commands for the above-described actuators of the respective rolling stands 1 to 4 are calculated as follows.

That is, the control device 10 includes the model 11,
12 and the second from the plate crown detected by the crown
A subtracter 13 for subtracting the output of the model 12, a subtractor 14 for subtracting the output of the subtractor 13 from the crown target input from the outside, and a first model 1 from the output of the subtractor 14.
And a compensator 1 for outputting a control command for controlling the plate crown to the crown target for each actuator based on the output of the subtractor 15.
6 and the rolling stands 2, 3 output from the compensator 16
4 is transmitted to each rolling stand 1-2, 2-3,
And a delay processing block 17 for inputting with a delay based on the time required to move the strip S between 3 and 4.

Next, the operation, operation, and effect of each of the above blocks constituting the control device 10 will be described. Note that each of the blocks constituting the control device 10 may be individually configured as hardware.
It may be realized by software by configuring as a computer having OM and RAM.

First, the first model 11 sets the control amount of the actuator output from the compensator 16 to Δu _B , and the adjustment amount by which the rolling stands 1-4 are actually (mechanically) adjusted according to the control amount. ΔP a variable representing the time t as a parameter _B, and when the variation calculated value of strip crown corresponding to the adjustment amount [Delta] C _M, a, [Delta] C _M a second model 12 and the subtracter calculated by the following formula 15 is output.

[0035]

(Equation 6)

ΔC_M = K_C ΔP_B Where K_B And T_B Is the adjustment amount ΔP_BIn a first-order lag system
Gain and time constant for approximation, K_C Is the above adjustment amount
Coefficient of influence on the sheet crown. In compensator 16
Is ΔC calculated in this way._MReflect the above acti
Control amount Δu_BIs calculated.
After controlling the eta, the strip crown of the strip S is actually
Rate of change when changing (K_B, K_C) And delay time
(T _B) Is sufficiently reflected in the control amount Δu_BRolling stan
Can be output as a control command to the nodes 1 to 4. What
The compensator 16 is a proportional system that performs an output proportional to the input value.
Control (P control), integration system that outputs according to the integration of input values
Control (I control), PI control combining them, etc.
Control amount Δu_BIs calculated.

These calculation methods and necessary control coefficients in the compensator 16 are input from the process computer 20 based on rolling conditions and the like. Further, the gain K _B , the time constant T _{B, and the} like are also input from the process computer 20 to the first model 11 as needed, whereby the material of the strip S, the aging of the rolling stands 1 to 4, It is possible to cope well with improvements and the like.

The second model 12 calculates a plate crown variation calculation value ΔC _S immediately below the crown meter 5 by the following equation:
Output to the subtractor 13. ΔC _S = ΔC _M · e ^-LS where L represents a dead time detected by the crown meter 5.

By subtracting the output of the second model 12 from the current measured value of the crown meter 5 (subtractor 13), the strip S of the portion currently rolled by the rolling stand 1 is moved directly below the crown meter 5. The processing of the subsequent blocks can be executed by predicting the plate crown at the time of the execution.

As described above, in the control device 10, by using the first model 11 and the second model 12, the rate of change (KB _B) when the strip crown of the strip actually changes after controlling the actuator is controlled. , K _C ) and the delay time (T _B ), and the control amount Δu _B sufficiently reflecting the delay time (L) required for moving the strip S from the uppermost rolling stand 1 to the crown meter 5. And the sheet crown can be feedback controlled very well. In addition, by controlling the plate crown with an appropriate change amount, the plate shape can be well controlled.

Further, the control amount Δu _B is individually delayed for each actuator by the delay processing block 17 based on the time required for moving the strip S between the rolling stands 1-2, 2-3, and 3-4. Is entered. That is, the delay processing block 17 calculates the time required for the strip S to move to each of the stands 1-4 based on the rolling speed and the distance between each of the rolling stands 1-2, 2-3, and 3-4, and passes through the rolling stand 1. The control amount Δu _B is appropriately distributed and output to each of the rolling stands 1 to 4 in synchronization with the time when the portion of the strip S reaches each of the rolling stands 2 to 4. Therefore, in the present tandem rolling mill, the strip crown and the strip shape of the strip S can be controlled with high accuracy, and a high-quality strip can be obtained. In addition, since only one crown meter 5 needs to be provided in the present tandem rolling mill, the cost of rolling the strip S can be reduced, and the maintainability can be improved.

Next, the tandem rolling mill is controlled by using the control device 10 of the present embodiment and the conventional control device having no first model 11, second model 12, and delay processing block 17, respectively. Then, the difference of the effect was verified.
An actuator for changing the bending force was used as the actuator. Further, the control was started with the amount of change in the target value of the sheet crown set to -0.2%, and the steady state 1
At the time point of 80 s, a further disturbance of -0.2% (step change of the sheet crown of the supplied strip S) was given. Further, the characteristics of each of the rolling stands 1 to 4 were as shown in Table 1.

[0043]

[Table 1]

FIG. 2 shows a change in the measured value of the sheet crown measured by the crown meter 5 and a change in the sheet shape downstream of the rolling stand 4. FIG. 2A shows the result obtained by the above-described conventional control device, and FIG. 2B shows the result obtained by the control device 10. As shown in FIG. 2A, when the conventional control device is used, the plate crown is controlled to the target value and the plate shape change is constant in the steady state, but the plate shape change is greatly deteriorated in the transient state. It can be seen that it is lost (see the circle in the figure). Also, the time required for the crown to reach the target value was as long as 150 s. In contrast, FIG.
In the present embodiment shown in (B), the plate crown was able to quickly reach the target value while constantly suppressing the change in the plate shape from the transient state (75s). Therefore, excellent effects such as improvement of product quality of the strip S and securing of operation stability are expected.

In the above-described embodiment, the first model 11 and the second model 12 are used as models, the compensator 16 is used as control amount calculating means, the delay processing block 17 is used as delay input means, and the process computer 20 is used as input means. Respectively. Further, the present invention is not limited to the above-described embodiment at all, and can be implemented in various forms without departing from the gist of the present invention. For example, in the above-described embodiment, the control is performed so that the sheet crown itself matches the target value. However, in the present invention, in addition to the control of the sheet crown itself, the control of the amount equivalent to the sheet crown such as the crown ratio is performed. Can also be applied.

In the present invention, a plurality of sheet crown detecting means such as a crown meter may be provided in a tandem rolling mill. In this case, the detection dead time can be reduced, the time until the sheet crown reaches the target value can be further reduced, and the quality of the obtained strip can be further improved. In this case, it is disadvantageous in terms of cost and maintainability, but such an embodiment can be considered when giving priority to yield and product quality.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a tandem rolling mill to which the present invention is applied and a control system thereof.

FIG. 2 is an explanatory diagram showing effects of the tandem rolling mill and a control system in comparison with a conventional example.

[Explanation of symbols]

1, 2, 3, 4 ... rolling stand 5 ... crown meter 10 ... control device 11 ... first model 12 ... second model
16 Compensator 17 Delay processing block 20 Process computer S Strip

Continued on the front page (72) Inventor Nagataka 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries Co., Ltd. (72) Inventor Meiji Sugie 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries Co., Ltd. F-term (reference) 4E024 AA03 EE01 GG01 GG05

Claims (5)

[Claims] 1. A control device for a tandem rolling mill, comprising: a plurality of rolling stands, each of which controls a tandem rolling mill having an adjusting means for adjusting a strip crown of a strip; , Further downstream of the most downstream rolling stand,
Strip crown detecting means for detecting the strip crown of the strip, and the rate of change and delay time when the strip crown of the strip actually changes after controlling each of the adjusting means, and from the most upstream rolling stand A model defining a correspondence relationship between a control amount of each of the adjusting means and a variation amount of the plate crown based on a delay time required for movement of the strip to the plate crown detection means; and a correspondence relationship defined by the model. Control amount calculating means for calculating a control amount of each of the adjusting means based on the sheet crown detected by the sheet crown detecting means; and calculating the control amount based on a time required for moving the strip between the rolling stands. Delay input means for individually delaying and inputting the control amount calculated by the means to each of the adjusting means, and tandem pressure. Control equipment for rolling mills. 2. The tandem rolling mill according to claim 1, wherein the model associates the change amount ΔC _S of the sheet crown corresponding to the control amount Δu _B of each of the adjusting means by the following equation. Control device. (Equation 1) _{ΔC M = K C ΔP B ΔC} S = ΔC M · e -LS However, [Delta] P _B is a variable representing the adjustment amount time t as a parameter by the adjusting means of the rolling stands, K _B and T _B is the adjustment amount A gain and a time constant when approximated by a first-order lag system, K _C represents an influence coefficient of the adjustment amount on the sheet crown, and L represents a detection dead time in the sheet crown detection. 3. The rate of change and delay time when the strip crown of the strip actually changes after controlling each of the adjusting means, and the strip from the most upstream rolling stand to the strip crown detecting means. 2. An input means for inputting at least one of a delay time required for movement of the model to the model.
Or the control device of the tandem rolling mill according to 2. 4. A method for controlling a tandem rolling mill, comprising: a plurality of rolling stands, each of which includes an adjusting means for adjusting a strip crown of a strip, the method comprising: , Further downstream of the most downstream rolling stand,
After detecting the strip crown of the strip, and after controlling each of the adjusting means, the rate of change and the delay time when the strip crown of the strip actually changes, and the detection of the strip crown from the most upstream rolling stand Based on a delay time required for the movement of the strip to the position, using a model that defines the correspondence between the control amount of each of the adjusting means and the amount of change of the strip crown, the correspondence defined by the model is detected and detected. The control amount of each of the adjusting means is calculated based on the obtained sheet crown and, based on the time required for moving the strip between the rolling stands, the calculated control amount is individually delayed by the adjusting means. A method for controlling a tandem rolling mill, characterized by inputting. 5. The tandem rolling mill according to claim 4, wherein the model associates the change amount ΔC _S of the sheet crown corresponding to the control amount Δu _B of each of the adjusting means by the following equation. Control method. (Equation 2) _{ΔC M = K C ΔP B ΔC} S = ΔC M · e -LS However, [Delta] P _B is a variable representing the adjustment amount time t as a parameter by the adjusting means of the rolling stands, K _B and T _B is the adjustment amount A gain and a time constant when approximated by a first-order lag system, K _C represents an influence coefficient of the adjustment amount on the sheet crown, and L represents a detection dead time in the sheet crown detection.