JP3389903B2 - Metal strip rolling control method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling control technique for rolling a metal strip, and in particular, it makes full use of control response of a roll reduction device and / or a mill motor to improve plate thickness accuracy and metal The present invention relates to a control method that enables stable manufacturing of a strip.

[0002]

2. Description of the Related Art As a method for controlling the plate thickness of a metal strip during rolling to a desired thickness, the following methods have been conventionally known.

(1) In accordance with the measured value of the incoming plate thickness of the rolled material measured by the plate thickness gauge provided on the incoming side of the rolling mill or the estimated value of the incoming plate thickness estimated by the plate thickness estimating means, A feedforward plate thickness control method for controlling a roll reduction position and / or a roll speed so that the influence of thickness variation does not appear on the outlet plate thickness.

(2) According to the measured value of the outgoing strip thickness of the rolled material measured by the strip thickness gauge provided on the outgoing side of the rolling mill or the estimated value of the outgoing strip thickness estimated by the strip thickness estimating means, the roll reduction is performed. Feedback thickness control method for manipulating position and / or roll speed.

As the plate thickness estimating means, a method of calculating a so-called gauge meter thickness by substituting the roll rolling position and the rolling load into a gauge meter formula, a moving speed of the rolled material at the plate thickness estimating position, and an estimation A method is known in which the so-called mass flow thickness is calculated by substituting the moving speed and plate thickness of the rolled material at a position different from the position into the constant law of mass flow, and in particular, the gauge meter thickness is used in the feedback plate thickness control method. The conventional control method is called a gauge meter AGC, and the control method using the mass flow thickness in the feedback plate thickness control method is called a mass flow AGC.

(3) According to the rolling load measured by the load cell,
A plate thickness control method called Visla AGC or mill rigidity variable control, which is a method of operating the roll reduction position so as to correct the roll gap change due to the elongation of the rolling mill.

Further, if the tension of the rolled material fluctuates, not only the passing of the rolled material becomes unstable, but also the elastic deformation amount of the rolling mill is changed through the change of the rolling load to promote the variation of the sheet thickness. It is also important to control the tension of the rolled material. The following methods are known as tension control methods for rolled materials.

(4) A feedback tension control method in which the roll reduction position and / or the roll speed is operated according to the tension measurement value of the rolled material measured by a tensiometer.

(5) In a rolling facility equipped with a looper, a supporting force of the looper is given so as to balance with a target tension of a rolled material, and a loop amount variation (measured by a looper angle) varied by a tension variation, Indirect tension control method by feedback looper angle (height) control that controls roll speed.

The above control methods (1) to (5) can be used in combination, and the operation amount determined by each control is the rolling position of the same roll rolling device and the roll speed of the same rolling roll. The final manipulated variable is added for each value.

In these rolling control methods, it is general to use digital control, which is superior in control accuracy to an analog control circuit, due to the recent development of system technology and digital technology.

FIG. 2 is a block diagram showing a general digital control system.

As shown in the figure, the digital compensator 10 samples the rolling data necessary for controlling the plate thickness, tension, etc. through the sampler 20 at every predetermined control cycle, and determines the roll rolling position or the roll speed. Is calculated, and the hold circuit 30 converts the operation amount, which is a discrete signal for each control cycle, into a continuous signal, and the operation end 40 such as the roll reduction device or the mill motor is instructed to change the roll reduction position or the roll speed. And so on.

In the same figure, the input of rolling data or the output of the manipulated variable is shown by one system line, but in reality, there are various inputs for rolling data, and there are various outputs, so the above-mentioned one The system line of means a bundle of many data (signals). Further, the sampler 20 also means a large number of samplers (not necessarily synchronized sampling).

In the above control method, the control response of the roll reduction device or the mill motor at the operating end is, of course,
The faster the speed, the higher the control accuracy.

For example, Japanese Unexamined Patent Publication No. 4-237506 discloses a method of controlling the tension and looper angle of a rolled material by using an AC motor having a crossing frequency of 40 rad / s or more, and a high response AC motor. It is stated that the use of (1) stabilizes the tension of the rolled material and improves the plate thickness accuracy.

Further, in Japanese Patent Laid-Open No. 7-16607,
A method of performing mill rigidity variable control with a tuning rate of 0.8 to 1.0 under a control cycle of 1/100 or less of the temperature disturbance cycle of the rolled material is disclosed.

[0018]

However, there is no knowledge about the relationship between the control response of the roll reduction device or the mill motor, which is the operation end of rolling control, and the control period of the digital compensator, and the above-mentioned Japanese Patent Laid-Open No. 4-237506. Even if an operating end having a high control response as disclosed in the publication is used, a sufficient control effect may not be obtained due to the long control cycle. Also, in an attempt to unnecessarily shorten the control cycle, the amount of calculation to be performed within one control cycle is limited, and advanced calculations cannot be performed, and the digital compensator has only a simple control logic such as a few arithmetic operations. It could not be implemented.

In order to avoid this, it is necessary to divide the arithmetic processing contents into a plurality of digital compensators or to use a CPU (central processing unit) having a high arithmetic speed for the digital compensators, which increases equipment costs. There is a problem. For example, in the technique disclosed in Japanese Patent Application Laid-Open No. 7-16607, when the control cycle becomes too short as compared with the control response of the operating end, the operating end controls the operating amount even if the control device outputs an operating command. Cannot be changed, and only the above-mentioned disadvantage of shortening the control cycle appears.

The object of the present invention is to solve the above problems.
By setting the control cycle of the digital compensator to a value that is necessary and sufficient to exert the control response of the roll reduction device or the mill motor, it is possible to control the strip rolling at a low cost with high accuracy and stability. To provide a method.

[0021]

The present inventor has obtained the following knowledge by observing the behavior of the sheet thickness in an actual rolling mill and performing simulation by a computer model. Hereinafter, the grounds for setting the control cycle of the digital compensator will be described in detail.

Generally, the responsiveness of the operating end of a roll reduction device, a mill motor, etc. is such that the gain of the frequency response at the operating end is -3.
The maximum value of the frequency at which the phase is at least dB (0.71) and at least -π / 4 [rad] (hereinafter referred to as the control response frequency).
It is represented by. That is, the control response frequency is the maximum frequency of the input sine wave in which the amplitude of the output sine wave is 0.71 or more and the phase delay is π / 4 [rad] or less when the sine wave of the unit amplitude is input to the operation end. is there.

For example, the transfer function at the operating end is

[0024]

[Equation 5]

However, when T is a time constant [s] and s is a first-order lag such as Laplacian, the gain and phase of the transfer function of equation (1) are given, where f'is the frequency of the input sine wave. Is
It is expressed by equations (2) and (3).

[0026]

[Equation 6]

The control response frequency is expressed by equation (4).

[0028]

[Equation 7]

In the case of digital control, the output of the digital compensator 10 is input to the operating end 40 through the hold circuit 30 as shown in FIG. 2, so the control response frequency of the operating end including the hold circuit must be taken into consideration. . This includes
It suffices to check the gain and phase of the response at the operating end when the digital compensator 30 outputs a discrete-time sine wave signal. The output of the digital compensator 10 can be expressed by the following equation (5).

U _i = sin (2πf′iΔ) (i = 0,1,2 ...) (5) where f ′ is frequency [Hz] and Δ is control cycle [s].

The output of the hold circuit 30 at time t is
It can be expressed by equation (6), and this output is given to the operating end.

X (t) = sin (2πf′t) (iΔ ≦ t <(i + 1) Δ) (6) The output of the operating end 40 does not become a sine wave, but (7)
By approximating with a sine wave as in the equation and obtaining the gain k and the phase α, the control response frequency of the operating end including the hold circuit can be obtained.

Y (t) = k sin (2πf′t + α) (7) FIG. 3 shows the frequency characteristics of the system including the hold circuit when the operating end is a first-order lag system and its control response frequency is 25 Hz. Is a graph obtained by the calculation method of Eq. (7), in which Fig. (A) shows the gain characteristic and Fig. (B) shows the phase characteristic. In both (a) and (b), the control cycle is 0.00
Both the case of 5 s and the case of 0.01 s are shown. Same figure
As shown in (a), the gain characteristics are not so different even if the hold circuit is included, but as shown in (b) of the figure, the phase characteristics are delayed as the control cycle becomes longer.

Further, the allowable range of the phase delay is -π / 4 [r
ad], the control response frequency of the operating end including the hold circuit is 15 Hz when the control cycle is 0.005 s,
When the control cycle is 0.01 s, it is 9.4 Hz, which is lower than the control response frequency of 25 Hz at the operating end not including the hold circuit.

FIG. 4 is a graph showing the relationship between the control cycle and the control response frequency of the operating end including the hold circuit when the control response frequency is the operating end of a first-order lag system of 25 Hz.
As can be seen from the figure, the control response frequency of the operating end including the hold circuit increases as the control cycle decreases,
It approaches the control response frequency of the operating end.

Generally, when designing a control system having an operating end whose control response frequency is f [Hz], the control response frequency f
It is known to provide a margin called a stability margin or a phase margin, instead of a control system based on the assumption that the operating end is operated at [Hz]. In the case of a process control system in which the controlled variable is settled to a constant target value such as plate thickness control or tension control, it is desirable that the phase margin be π / 9 [rad] or more. In particular, when the measured or estimated data input to the digital compensator has a time delay corresponding to π / 9 [rad] or more at the control response frequency f, the phase margin must be π / 9 rad or more. The control system becomes unstable.

When the control response frequency is the first-order lag system operating end of f, the phase at the frequency f (that is, -π / 4 [ra
The control response frequency g [Hz] of the first-order lag system in which the phase is further delayed by π / 9 [rad] than that of [d]) can be derived from the relationship of the following expression (8) as in expression (9).

[0038]

[Equation 8]

[0039]

[Equation 9]

Therefore, if the control cycle of the digital compensator is set so that the control response frequency including the hold circuit at the operating end is 0.47 times or more the control response frequency at the operating end, the response at the operating end is almost the same. Control can be realized without impairing the property.

On the other hand, if the control cycle is shortened, there are problems that the complicated control logic cannot be mounted on the digital compensator and that a plurality of digital compensators are required, resulting in an increase in equipment cost, as described above. , Should be an appropriate value. In this case, it is sufficient that the control response frequency of the operating end including the hold circuit is 0.9 times the control response frequency of the operating end. In order to raise the control response frequency of the operating end including the hold circuit to a value higher than this, and to make it equal to the control response frequency of the operating end, the sample-hold control cycle must be shortened so that it becomes equal to the continuous time. Inevitably, the equipment cost increases, but the effect is poor.

In summary, the control response frequency f [Hz] of the operating end is controlled so that the control response frequency g [Hz] of the operating end including the hold circuit has the following expression (10). If the cycle is determined, the control ability of the operating end of the roll reduction device, the mill motor, etc. can be utilized in a necessary and sufficient manner.

0.47f ≦ g ≦ 0.9f (10) Control response frequency g [H at the operating end including the hold circuit
z] depends not only on the control cycle Δ but also on the control response frequency f of the operating end. In designing the control cycle Δ, it is preferable to express the control cycle Δ satisfying the expression (10) by an explicit function of the control response frequency f at the operating end.

FIG. 1 is a graph showing the relationship between the control response frequency f at the operating end and the control cycle Δ of the digital compensator.

For example, the control response frequency f at the operating end is 25
In the case of Hz, it is understood from FIG. 4 that the control cycle satisfying the expression (10) is 0.0008s or more and 0.008s or less. Similarly, by changing the control response frequency f of the operating end, (10)
A plot of the control period Δ satisfying the formula is the range shown by the hatched portion in FIG. 1. As a result of examining the relational expression that fits the boundary curve in the shaded area in the figure, the following expression (11) was obtained. That is, within the range of the formula (11), the formula (10) is generally established, and the control ability of the operating end of the roll reduction device, the mill motor, etc. can be used necessary and sufficient.

[0046]

[Equation 10]

Further, in the control method for operating both the roll rolling position and the roll speed, the operating frequency at which they can respond, that is, the digital compensator outputs the manipulated variable only up to the frequency with the smaller control response frequency. Therefore, the control cycle is set so that the frequency f having the smaller control response frequency satisfies the expression (11).

The present invention was made based on the above findings, and the gist thereof is as follows (1) to (4).

(1) Sheet thickness measurement value of rolled material, estimated sheet thickness value of rolled material estimated by gauge meter method or mass flow constant law, measured rolling load value, measured tension value of rolled material and loop amount of looper device Based on at least one of the values, the digital compensator calculates the operation amount of the roll reduction position and / or the roll speed for each constant control cycle, and the roll reduction position and / or the roll reduction position so as to follow the operation amount. What is claimed is: 1. A method for controlling the rolling of a metal strip, which operates a roll speed, wherein the control period of the digital compensator is set within the range of the following equation.

[0050]

[Equation 11]

Here, Δ is the control cycle [s] of the digital compensator, f is the control response frequency of the roll reduction position when only the roll reduction position is operated, and the roll speed control response frequency when only the roll speed is operated. When operating both the roll reduction position and the roll speed, the frequency of the smaller control response frequency of the roll reduction position and the roll speed [H
z].

(2) Measured value of rolled material, estimated value of rolled material estimated by gauge meter method or constant law of mass flow, measured value of rolling load, measured value of rolled material tension and measurement of loop amount of looper device At least one of the values is measured or estimated by a measuring instrument or an estimator with a time delay corresponding to a phase delay of π / 9 [rad] or more at the frequency f, and based on the measured or estimated data. Rolling control method for a metal strip, in which an operation amount of a roll reduction position and / or a roll speed is calculated by a digital compensator for each constant control cycle, and the roll reduction position and / or roll speed is operated so as to follow the operation amount. A method for controlling rolling of a metal strip, wherein the control period of the digital compensator is set within the range of the following equation.

[0053]

[Equation 12]

Here, Δ is the control cycle [s] of the digital compensator, f is the control response frequency of the roll reduction position when only the roll reduction position is operated, and the control response frequency of the roll speed when only the roll velocity is operated. When operating both the roll reduction position and the roll speed, the frequency of the smaller control response frequency of the roll reduction position and the roll speed [H
z].

(3) Measured value of rolled material, estimated value of rolled material estimated by gauge meter type or constant mass flow law, measured rolling load, measured tension of rolled material and constant loop amount of looper device Among them, at least two data are classified into a plurality of data groups, each data group is input to different digital compensators, and the roll compensating position common to the data groups is set in the digital compensator at every constant control cycle. And / or the control amount of the roll speed common to the data group is calculated, and the roll reduction position and / or the operation amount of the roll speed calculated by the different digital compensator are added for each roll reduction position and roll speed, and added. A method for controlling the rolling of a metal strip, in which the roll reduction position and / or the roll speed is operated so as to follow the operation amount, which is controlled by the digital compensator. Set the control cycle to be longer as the frequency of the control band controlled by each digital compensator is lower, and set the control cycle of the digital compensator with the highest control band frequency within the range of the following formula. A characteristic method for controlling the rolling of a metal strip.

[0056]

[Equation 13]

Here, Δ is the control cycle [s] of the digital compensator having the highest frequency in the control band, and f is the control response frequency of the roll reduction position and the roll speed when only the roll reduction position is operated. Is the control frequency of the roll speed, and when operating both the roll reduction position and the roll speed, is the smaller frequency [Hz] of the control response frequencies of the roll reduction position and the roll speed.

(4) The rolling load measurement value is input to the first digital compensator, the strip thickness measurement value on the delivery side of the rolling mill is input to the second digital compensator, and the first digital compensator has a constant control cycle. The first roll reduction position operation amount is calculated for each time, the second roll reduction position operation amount is calculated for each constant control cycle by the second digital compensator, and the first roll reduction position operation amount and the second roll reduction position operation are performed. A method for controlling the rolling of a metal strip, in which the amount is added and the roll reduction position is operated so as to follow the added operation amount, wherein the control cycle of the second digital compensator is greater than the control cycle of the first digital compensator. A rolling control method for a metal strip, which is set to be long and the control cycle of the first digital compensator is set within the range of the following equation.

[0059]

[Equation 14]

Here, Δ is the control cycle [s] of the first digital compensator, and f is the control response frequency [H] of the roll rolling position.
z].

In the present invention, the controlled object controlled by the digital compensator may include not only the roll reduction position and / or roll speed but also other control such as change of loop amount (looper angle) setting.

[0062]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a feedforward plate thickness control using a plate thickness gauge on the inlet side of a rolling mill, a gauge meter AG.
It can be applied to known rolling control methods such as C, mass flow AGC, feedback tension control using a tensiometer, and loop amount (looper angle) feedback control. This is because the present invention relates to a digital compensator used for these controls and does not depend on the type of the detecting end or the operating end. Therefore, the case where the embodiment of the present invention is applied to the rolling control in which the mill rigidity variable control and the feedback sheet thickness control using the sheet thickness gauge on the delivery side of the rolling mill are used together will be described as an example.

FIG. 5 is a block diagram showing an example of rolling equipment and a control system used for implementing the present invention. The rolled material 1 is supplied in the direction of the white arrow. A pair of top and bottom work rolls 2,
In No. 3, the gap is adjusted by the roll reduction device 50,
The rolled material 1 is rolled by passing through the gap.
The rolling load can be measured by the load meter 6 during rolling, and the rolled plate thickness of the rolled material 1 can be measured by the plate thickness meter 5 installed on the delivery side of the rolling mill. . The rolling load measured by the load meter 6 is given to the first digital compensator 11 via the sampler 20-1 every control cycle Δ ₁ second, and the first roll rolling position change command is calculated.

On the other hand, the plate thickness of the rolled material 1 measured by the plate thickness gauge 5 is given to the second digital compensator 12 via the sampler 20-2 every control cycle Δ ₂ seconds, and the second roll roll position is changed. The command is calculated. The first roll reduction position change command, which is a discrete time signal, is converted into a continuous time signal by being held by the first hold circuit 31 until the next control cycle of the first digital compensator 11, and the roll reduction device 5
0, and the second roll reduction position change command, which is a discrete time signal, is converted into a continuous time signal by being held by the second hold circuit 32 until the next control cycle of the second digital compensator 12. It is given to the roll reduction device 50. The roll reduction device 50 adds the first roll reduction position change command converted to the continuous time signal and the second roll reduction position change command, and controls the roll reduction position so as to match the added value. Roll two,
The plate thickness of the rolled material 1 is controlled by adjusting the gap of No. 3.

Although FIG. 5 shows an example in which the first roll reduction position change command and the second roll reduction position change command are added by the roll reduction device 50, an adder is separately installed and the first roll is installed. The rolling position changing command and the second roll rolling position changing command may be given to the adder, and the addition result may be given to the roll rolling device 50.

The first roll roll-down position change command ΔS ₁ obtained in the first digital compensator 11 is calculated by the following equation by a known method of mill rigidity variable control.

[0067]

[Equation 15]

Here, P is the rolling load given from the load meter 6, P ₀ is the stored value of the rolling load at the start of control, ka is the tuning rate, M is the mill rigidity coefficient, and ka and M are the rolled material 1 It is decided before starting rolling.

The second roll roll-down position change command ΔS ₂ obtained by the second digital compensator 12 is calculated by the following equation by a known method of proportional-plus-integral control.

[0070]

[Equation 16]

Here, h is a plate thickness given from the plate thickness gauge 5, h _ref is a plate thickness target value, k _PS is a proportional gain, k _IS is an integral gain, and z is a digitally controlled shift operator.
h _ref , k _PS and k _IS are determined before the rolling of the rolled material 1 is started.

Using the rolling equipment configured as described above,
Control cycle delta ₁ of the first digital compensator 11 in practicing the present invention, a method of determining the control cycle delta ₂ of the second digital compensator 12 will be described.

Control cycle Δ _{1 of} the first digital compensator 11
Is set according to the control response frequency f _s [Hz] of the roll reduction device 50, which is the operation end, as shown in the following equation (14).

[0074]

[Equation 17]

The control cycle Δ ₂ of the second digital compensator 12 is set according to the following expression (15) according to the control response frequency f _s [Hz] of the roll reduction device 50 which is the operating end. deep.

[0076]

[Equation 18]

In the above description, the present invention is applied to each of the methods of setting Δ ₁ and Δ ₂ , but it may be applied to only one for the following reason.

That is, since the mill rigidity variable control is so small that the dead time for detecting the rolling load can be ignored, the control band can be increased to near the control response frequency of the roll reduction device, and the effect of improving the plate thickness accuracy is great. . On the other hand, in the feedback plate thickness control, the control band must be made considerably lower than the control response frequency of the roll reduction device. This is the thickness gauge 5 from the position of the work rolls 2 and 3.
This is because there is a dead time for detecting the plate thickness only during the time when the rolled material 1 is transferred to the position. Therefore, the control cycle Δ ₁ of the first digital compensator is set so as to satisfy the equation (14), and the control cycle Δ ₂ of the second digital compensator is set smaller than Δ ₁ to save the equipment cost. This is an effective method.

FIG. 6 is a block diagram showing another example of the rolling equipment and the control system used for implementing the present invention. This figure is a diagram when the present invention is applied to a control device for controlling the plate thickness by the roll speed. In the figure, the same elements as those in FIG. 5 are designated by the same reference numerals.

In the feedback plate thickness control, a method of operating the roll speed as shown in FIG. 6 is also possible in addition to the roll roll-down position control as shown in FIG. The calculated value of the second digital compensator 12 becomes a roll speed change command, and the roll speed change command is given to the second hold circuit 32. The second hold circuit 32 holds the roll speed change command, which is a discrete time signal, until the next control cycle of the second digital compensator 12 and converts it into a continuous time signal, which is given to the mill motor 60, and the mill motor 60 causes the second hold circuit. The rolled material 1 is rolled while adjusting the rotation speeds of the work rolls 2 and 3 according to a roll speed change command given from 32.

The roll speed change command ΔV obtained by the second digital compensator 12 is calculated by the following equation by a known method of proportional-plus-integral control.

[0082]

[Formula 19]

Here, k _PV is a proportional gain and k _IV is an integral gain, and these values are determined before the rolling of the rolled material 1 is started.

When the present invention is carried out using the rolling equipment configured as described above, the control cycle Δ ₁ of the first digital compensator 11 is set within the range satisfying the expression (14) as described above. Every other time, the control cycle Δ ₂ of the second digital compensator 12 is equal to the control response frequency f _V [H of the mill motor 60 that is the operating end.
z], and set within the range of the following formula (17).

[0085]

[Equation 20]

As in the case of FIG. 5, the present invention may be applied to only _one of Δ ₁ and Δ ₂ .

In the feedback plate thickness control, there is also known a method of simultaneously operating the roll reduction position and the roll speed.

FIG. 7 is a block diagram showing another example of the rolling equipment and the control system used for implementing the present invention. The figure shows a case where the present invention is applied to a rolling apparatus that simultaneously operates the roll reduction position and the roll speed. In the figure, the same elements as those in FIGS.

In the case of the same drawing, the second digital compensator calculates a second roll reduction position change command and a roll speed change command, which are operation amounts commands for feedback plate thickness control, and supplies them to the second hold circuit 32. To be Second hold circuit 3
Reference numeral 2 is a discrete time signal that holds the second roll reduction position change command and the roll speed change command until the next control cycle of the second digital compensator 12 and converts them into a continuous time signal, and outputs the second roll reduction position change command. A roll speed change command is given to the roll reduction device 50 to the mill motor 60. Roll reduction device 5
0 adds the first roll reduction position change command and the second roll reduction position change command converted into the continuous time signal, and controls so that the roll reduction position coincides with the added value. Adjust the gap. On the other hand, the mill motor 60 is configured to roll the rolled material 1 while adjusting the rotation speeds of the work rolls 2 and 3 according to a roll speed change command given from the second hold circuit 32.

The second roll reduction position change command ΔS ₂ and the roll speed change command ΔV obtained in the second digital compensator 12 are calculated by the following equations by a known method of proportional-plus-integral control.

[0091]

[Equation 21]

[0092]

[Equation 22]

Where k _PSV1 and k _PSV2 are proportional gains, k
_ISV1 and k _ISV2 are integral gains, which are determined before the rolling of the rolled material 1 is started.

When the present invention is carried out using the rolling equipment configured as described above, the control cycle Δ ₁ of the first digital compensator 11 is set within the range satisfying the expression (14) as described above. Every other time, the control cycle Δ ₂ of the second digital compensator 12 is the control response frequencies f _S [Hz] and f _V [Hz] of the roll reduction device 50 and the mill motor 60, which are the operation ends.
Depending on the value, set within the range of the following formula (20).

[0095]

[Equation 23]

As in the above, the present invention may be applied to only _one of Δ ₁ and Δ ₂ .

In the above description, the calculation of the manipulated variable of the mill rigidity variable control and the feedback plate thickness control based on the plate thickness measured by the plate thickness meter is performed by separate digital compensation of the first digital compensator and the second digital compensator. However, it is also possible to use one digital compensator to calculate the manipulated variables of the variable mill stiffness control and the feedback plate thickness control under the same control cycle. Hereinafter, a method for carrying out the present invention in such a case will be described.

FIG. 8 is a block diagram showing an example of rolling equipment and a control system used for implementing the present invention. This figure shows a case where the calculation of the variable mill rigidity control and the feedback plate thickness control shown in FIG. 5 is performed by one digital compensator 10. In the figure, the same elements as those in FIGS.

The digital compensator 10 receives the measured values of the plate thickness of the rolled material 1 from the plate thickness meter 5 and the rolling load from the load meter 6 as discrete time signals. Inside the digital compensator 10, there are provided a first arithmetic circuit 21 for calculating the first roll pressure reduction position change command by the mill rigidity variable control by the formula (12) and a second roll pressure reduction position change command by the feedback plate thickness control.
The second calculation circuit 22 for calculating by the equation (13) is provided, and the first roll reduction position change command and the second roll reduction position change command are added and given to the first hold circuit 31 as a roll reduction position change command. To be The first hold circuit 31 holds the roll reduction position change command, which is a discrete time signal, until the next control cycle of the digital compensator 10, converts it into a continuous time signal, and gives it to the roll reduction device 50. The rolled material 1 is rolled while adjusting the gap between the work rolls 2 and 3 according to a roll rolling position change command given from the hold circuit 31.

When the present invention is carried out by using the rolling equipment configured as described above, the control cycle Δ of the digital compensator 10 is determined by the control response frequency f _S [H of the roll reduction device 50.
z]

[0101]

[Equation 24]

It is set within the range of. FIG. 9 is a configuration diagram showing an example of rolling equipment and a control system used for implementing the present invention. This figure shows a case where the calculation of the mill rigidity variable control and the feedback plate thickness control shown in FIG. 6 is performed by one digital compensator 10. In the figure, the same elements as those in FIGS.

In the figure, the digital compensator 10 is supplied with the measured values of the plate thickness of the rolled material 1 from the plate thickness meter 5 and the rolling load from the load meter 6 as discrete time signals. Inside the digital compensator 10, there is provided a first arithmetic circuit 2 for arithmetically operating a roll rolling position change command by the mill rigidity variable control by the formula (12).
1. The second calculation circuit 22 for calculating the roll speed change command by the feedback plate thickness control by the formula (16) is provided, and the roll pressure reduction position change command is issued by the first hold circuit 3
First, the roll speed change command is given to the second hold circuit 32. The first hold circuit 31 holds the roll reduction position change command, which is a discrete time signal, until the next control cycle of the digital compensator 10, converts it into a continuous time signal, and gives it to the roll reduction device 50. The roll speed change command, which is a discrete time signal, is held until the next control cycle of the digital compensator 10, converted into a continuous time signal, and given to the mill motor 60. The roll reduction device 50 adjusts the gap between the work rolls 2 and 3 according to the roll reduction position change command given from the first hold circuit 31, while the mill motor 60 responds to the roll speed change command given from the second hold circuit 32. The rolling material 1 is rolled while adjusting the rotation speeds of the work rolls 2 and 3.

When the present invention is carried out by using the rolling equipment configured as described above, the control cycle of the digital compensator 10 is such that the control response frequencies f _S [Hz] of the roll reduction device 50 and the mill motor 60, respectively. , F _V [Hz]
Set within the range of formula (22) below.

[0105]

[Equation 25]

FIG. 10 is a block diagram showing an example of rolling equipment and a control system used for implementing the present invention. This drawing shows a case where the calculation of the mill rigidity variable control and the feedback plate thickness control shown in FIG. 7 is performed by one digital compensator 10.
In the figure, the same elements as those in FIGS.

In the figure, inside the digital compensator 10, there is provided a first calculation circuit 21 for calculating a first roll pressure-reduction position change command by the mill rigidity variable control by the formula (12), and a second roll by feedback plate thickness control. The second calculation circuit 22 for calculating the rolling position changing command and the roll speed changing command by the formulas (18) and (19) is provided, and the first roll rolling position changing command and the second roll rolling position changing command are added. Is applied to the first hold circuit 31, and the roll speed change command is applied to the second hold circuit 32. The first hold circuit 31 holds the roll reduction position change command, which is a discrete time signal, until the next control cycle of the digital compensator 10, converts it into a continuous time signal, and gives it to the roll reduction device 50. The roll speed change command, which is a time signal, is held until the next control cycle of the digital compensator 10, converted into a continuous time signal, and given to the mill motor 60. The roll reduction device 50 adjusts the gap between the work rolls 2 and 3 according to the roll reduction position change command given from the first hold circuit 31, while the mill motor 60 responds to the roll speed change command given from the second hold circuit 32. The rolling material 1 is rolled while adjusting the rotation speeds of the work rolls 2 and 3.

When the present invention is carried out by using the rolling equipment configured as described above, the control cycle Δ of the digital compensator 10 is determined by the control response frequency f _S [Hz of each of the roll reduction device 50 and the mill motor 60. ], F _V [Hz] according to the following formula (23).

[0109]

[Equation 26]

[0110]

EXAMPLE A roll reduction device having a control response frequency f _S of 15 Hz was applied to the rolling equipment shown in FIG. 8 and the control cycle of the digital compensator 10 was changed to hot-roll low carbon steel.
In this case, the desirable control period of the digital compensator 10 calculated from the equation (21) was 1.3 ms to 12.7 ms. The control result was evaluated based on the magnitude of variation (maximum-minimum) in the thickness deviation with respect to the target thickness value.

FIG. 11 is a graph showing the relationship between the control cycle of the digital compensator and the variation of the plate thickness deviation in this embodiment.

As shown in the figure, when the control period of the digital compensator is larger than the desired range (more than 12.7 ms), the plate thickness deviation is large, and the desired range (1.3 ms or more,
(12.7 ms or less), the plate thickness deviations were almost the same.

On the other hand, even if the control cycle was made smaller than the desired range (less than 1.3 ms), the plate thickness deviation was not improved. From the above, the effectiveness of the control method of the present invention was confirmed.

[0114]

According to the control method of the present invention, it becomes possible to fully utilize the control response of the operation end of the roll reduction device, the mill motor, etc. in the rolling control of the metal strip, and unnecessarily increase the equipment cost. Without increasing the plate thickness accuracy and rolling stability.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a control response frequency of an operating end and a control cycle Δ of a digital compensator.

FIG. 2 is a block diagram showing a general digital control system.

3A and 3B are graphs showing frequency characteristics of a system including a hold circuit at an operating end of a first-order lag system, in which FIG. 3A shows a gain characteristic and FIG. 3B shows a phase characteristic.

FIG. 4 is a graph showing the relationship between the control cycle of the operating end of the first-order lag system and the control response frequency of the system including the hold circuit.

FIG. 5 is a configuration diagram showing an example of rolling equipment and a control system used for implementing the present invention.

FIG. 6 is a configuration diagram showing an example of rolling equipment and a control system used for implementing the present invention.

FIG. 7 is a configuration diagram showing an example of rolling equipment and a control system used for implementing the present invention.

FIG. 8 is a configuration diagram showing an example of rolling equipment and a control system used for implementing the present invention.

FIG. 9 is a configuration diagram showing an example of rolling equipment and a control system used for implementing the present invention.

FIG. 10 is a configuration diagram showing an example of rolling equipment and a control system used for implementing the present invention.

FIG. 11 is a graph showing the relationship between the control cycle of the digital compensator and the variation in plate thickness deviation in the example of the present invention.

[Explanation of symbols]

1: Rolled material 2, 3: Work roll 5: Thickness gauge 6: Load cell 10: Digital compensator 11: First digital compensator 12: Second digital compensator 20, 20-1, 20-2: Sampler 21: First arithmetic circuit 22: Second arithmetic circuit 30: Hold circuit 31: First hold circuit 32: Second hold circuit 40: Operating end 50: Roll reduction device 60: Mill motor

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B21B 37/00-37/78

Claims (4)

(57) [Claims] 1. A measured value of rolled material, an estimated value of rolled material estimated by a gauge meter method or a constant law of mass flow, a measured value of rolling load, a measured value of rolled material tension and a measured value of loop amount of a looper device. Among them, a digital compensator calculates a roll reduction position and / or an operation amount of a roll speed for each constant control cycle based on at least one data, and the roll reduction position and / or the roll is adjusted so as to follow the operation amount. A method for controlling the rolling of a metal strip, wherein the control period of the digital compensator is set within the range of the following equation, which is a method for controlling the rolling of a metal strip. [Equation 1] Where Δ is the control cycle [s] of the digital compensator, f is the control response frequency of the roll reduction position when only the roll reduction position is operated, and the roll speed control response frequency and roll reduction when only the roll speed is operated. When both the position and the roll speed are operated, the frequency [Hz] is the smaller one of the control response frequencies of the roll reduction position and the roll speed. 2. A strip thickness measurement value of a strip, a strip thickness estimation value estimated by a gauge meter type or a constant mass flow law, a rolling load measurement value, a strip tension measurement value, and a loop amount measurement value of a looper device. At least one of the data is measured or estimated by a measuring device or an estimator with a time delay corresponding to a phase delay of π / 9 [rad] or more at the frequency f, and digital data is obtained based on the measured or estimated data. A metal strip rolling control method in which a compensator calculates an operation amount of a roll reduction position and / or a roll speed for each constant control cycle and operates the roll reduction position and / or the roll speed so as to follow the operation amount. A rolling control method for a metal strip, wherein the control cycle of the digital compensator is set within the range of the following equation. [Equation 2] Where Δ is the control cycle [s] of the digital compensator, f is the control response frequency of the roll reduction position when only the roll reduction position is operated, and the roll speed control response frequency and roll reduction when only the roll speed is operated. When both the position and the roll speed are operated, the frequency [Hz] is the smaller one of the control response frequencies of the roll reduction position and the roll speed. 3. A strip thickness measurement value of a strip, a strip thickness estimation value estimated by a gauge meter method or a constant mass flow law, a rolling load measurement value, a strip tension measurement value, and a loop amount constant loop value. Among them, at least two data are classified into a plurality of data groups, the respective data groups are input to different digital compensators, and the roll compensating position common to the data groups is set by the digital compensator at every constant control cycle. And / or the control amount of the roll speed common to the data group is calculated, and the roll reduction position and / or the operation amount of the roll speed calculated by the different digital compensator are added for each roll reduction position and roll speed, and added. What is claimed is: 1. A method for controlling rolling of a metal strip, wherein a roll reduction position and / or a roll speed is controlled so as to follow an operation amount, the control of the digital compensator. The period is set to be longer as the frequency of the control band controlled by each digital compensator is lower, and the control period of the digital compensator with the highest frequency of the control band is set within the range of the following formula. A method for controlling rolling of a metal strip. [Equation 3] Where Δ is the control cycle [s] of the digital compensator with the highest frequency in the control band, f is the control response frequency of the roll reduction position when operating only the roll reduction position, and roll speed when operating only the roll speed. In the case of operating both the roll reduction position and the roll speed, the control response frequency is the smaller frequency [Hz] of the roll reduction position and the roll speed. 4. The rolling load measurement value is input to a first digital compensator, the strip thickness measurement value on the delivery side of the rolling mill is input to a second digital compensator, and the first digital compensator is used for every constant control cycle. The first roll roll position operation amount is calculated, and the second digital roll compensator calculates the second roll roll position operation amount at a constant control cycle. The first roll roll position manipulation amount and the second roll roll position manipulation amount are calculated. A method of controlling the rolling of a metal strip in which the roll reduction position is operated so as to follow the added operation amount,
The control cycle of the second digital compensator is set to be longer than the control cycle of the first digital compensator, and the control cycle of the first digital compensator is set within the range of the following equation. Rolling control method. [Equation 4] However, Δ is the control cycle [s] of the first digital compensator, f
Is the control response frequency [Hz] at the roll reduction position.