JPH09141315A - Control of tension between stands and looper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably control tension between stands and a looper angle without depending on the variation of characteristics by the looper angle when tension between stands and the looper vary in the case of stock to be rolled with a continuous rolling mill consisting of two or more stands provided with the looper between stands. SOLUTION: In the case of controlling tension generating in stocks to be rolled between stands and the looper angle so as to be a target value by manipulating the roll rotating velocity of the rolling stand 2 and the torque of the looper 4, the looper angle is measured during rolling, the gain of a controller operating the roll rotating velocity command value of the roll stand 2 with a tension and looper angle controller 15 is controlled with a control gain changing device 14 so that smaller the looper angle is larger the gain becomes, and the gain of the controller operating the torque command value of the looper 4 is controlled so that larger the looper angle is, the larger the gain becomes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to continuous rolling suitable for application in controlling the tension and looper of a material to be rolled in a continuous rolling mill having a looper arranged between rolling stands such as a hot rolling finishing mill. The present invention relates to a method for controlling tension between stands and a looper in a machine.

[0002]

2. Description of the Related Art Fluctuations in tension between stands in a continuous rolling mill affect the dimensional accuracy of the material to be rolled and the stability of the strip. That is, if the inter-stand tension becomes excessive, the plate thickness and width of the material to be rolled are reduced, and if the inter-stand tension becomes zero, an excessive loop occurs between the stands or the The material meanders.

Therefore, for example, in a hot rolling finishing mill, a mechanism called a looper is installed in order to properly maintain the loop amount between stands and to keep the tension between stands stable.

The tension between the stands and the looper angle interfere with each other, the fluctuation of the tension induces the fluctuation of the looper angle, and the fluctuation of the looper angle causes the fluctuation of the tension. For example, if the tension between the stands increases, the looper descends, and if the looper descends, the tension between the stands decreases. Therefore, it is important to stably control the tension that directly affects the dimension and shape of the rolled material and to suppress the fluctuation of the looper angle from the viewpoint of stable operation.

In order to control the two amounts, tension and looper angle, two manipulated variables, the roll rotation speed of the rolling stand and the looper torque, have been conventionally used.

As the most general control method, the looper angle is fed back to the roll rotation speed of the upstream or downstream rolling stand, and the roll rotation speed is corrected to control the looper angle constant, and the looper torque is further adjusted. There is a method of indirectly controlling the tension to a target value by adjusting according to the looper angle variation.

The above method has a problem that the tension controllability is poor because the tension is open loop controlled. Therefore, as described in JP-A-59-110410, the tension is measured by a load cell or the like installed in the looper, the tension is controlled by using the roll rotation speed of the rolling stand as an operation amount, and the looper torque or the looper speed is operated. A method using two feedback loops for controlling the looper angle as a quantity has been put into practical use.

In this method, as described above, the tension and the looper angle interfere with each other, the tension fluctuation induces the looper angle fluctuation, and the looper angle fluctuation causes the tension fluctuation. Therefore, before canceling the influence of this interference. A controller called a local compensator is also used, which is called a non-interference control system.

[0009] In addition, JP-A-59-118213,
JP-A-59-118214 and JP-A-5-131207
The application of the integral type optimum regulator, the application of H ∞ control, etc. are also performed as described in (1).

In the application of the above-mentioned integral type optimum regulator, the amount to be controlled is the amount to be controlled by feeding back not only the tension between the stands and the looper angle but also the state quantities such as the roll rotation speed and the looper speed. The controller is designed to minimize the weighted squared error integral function of a certain stand-to-stand tension, looper angle and control input roll rotation speed command and looper speed command. According to this method,
Although the response of the control system changes depending on the selection of the weight in the weighted squared error integration function and trial and error are required to obtain the desired response, not only can a stable control system be constructed, but some model error of the controlled object Even if there is, a control system that can maintain stability can be configured. Further, the controller is easy in that the feedback amount is multiplied by a constant gain to be the control input.

Further, in the application of the H∞ control, the frequency characteristic of the control system can be designed so as to cope with the model error such as the expected Young's modulus and the disturbance such as the plate temperature fluctuation and the plate thickness fluctuation. In this method, there are cases where only the inter-stand tension and looper angle, which are the quantities to be controlled, are fed back, and there are cases where the state quantity is included in the feedback. According to this method, although the controller may be complicated in a high dimension depending on the frequency characteristic to be designed, a design method based on the frequency characteristic of the PI controller, which has been often used in a simpler system than the conventional method. A control system can be designed in the same way.

In the design of each of the conventional control methods described above, the control device for calculating the roll rotation speed command value and the looper torque command value is optimally designed at a certain appropriate stand tension and looper angle, and It is used as it is regardless of the change in tension between stands and the generated looper angle.

[0013]

However, the characteristics of the controlled object from the roll rotation speed command and the looper torque command to the inter-stand tension and the looper angle greatly change depending on the looper angle. FIG. 1 shows a physical model of a control target from the roll rotation speed command and the looper torque command to the inter-stand tension and the looper angle. In FIG. 1, tension between roll stands σ is _calculated from the roll rotation speed command V _Rref.
And the characteristics up to the looper angle θ are expressed by the following equations (1) and (2), respectively. However, here, s in the formula is a Laplace operator, and the meaning of each symbol is as follows.

[0014]

(Equation 1) σ: Tension between stands θ: Looper angle W _L : Looper speed V _R : Roll rotation speed V _Rref : Roll rotation speed command value K _Vt : Influence coefficient from stand tension to material speed e = E / L (E: Young rate, L: interstand distance) J: looper inertia K _VN: influence coefficient K _gt from the looper speed to the material speed: influence coefficient from interstand tension to Rupatoruku f: forward slip T _V: the roll rotation speed control device Time constant gref: Looper torque command value D: Looper damper coefficient

The stability of the above equation (1) depends on the stability of the quadratic term (a) in the equation (1) and the quadratic term (b) in the equation (2), which are surrounded by broken lines, and depends on the quadratic term. When the damping constant ζ which is an index of stability of (a) and (b) is obtained,
The damping constants ζ in (a) and (b) are as follows.

Ζ = (1/2) · (D + J · e · K _Vt ) ÷ {J · e (D · K _Vt + K _VN · K _gt )} ^1/2 (3)

In the above equation (3), the smaller the looper angle, the smaller K _VN and K _gt.
Is larger, and the stability of the controlled object is better.

In addition, 2 in the equation (1) regarding the tension between the stands
When the steady-state gain Gt (s) of the next item (a) is obtained, the following equation (4) is obtained.

Gt = 1 / (D · K _Vt + K _VN · K _gt ) (4)

In this equation (4), as in the previous case,
As the looper angle becomes smaller, K _VN and K _gt become smaller, so that the steady gain Gt becomes larger and the inter-stand tension greatly fluctuates.

That is, the smaller the looper angle, the more stable the looper operates, but the larger the tension fluctuation. Conversely, the larger the looper angle, the more unstable the looper becomes, but the smaller the tension fluctuation.

Therefore, in the above-mentioned prior art, the control device for calculating the roll rotation speed command value and the looper torque command value has a constant gain regardless of the change of the looper angle, so that the looper descends and the looper angle is decreased. In the case of a small value, there is a problem that the fluctuation of the tension between the stands becomes large, the tension increases, and the width of the rolled material shrinks. On the contrary, when the looper rises and the looper angle becomes large, the roll rotation speed command value and the looper torque command value are excessively output, and the looper vibrates or the looper suddenly descends. was there.

Among the conventional techniques, particularly, in the method of feeding back the looper angle to the roll rotation speed of the upstream or downstream rolling stand and correcting the roll rotation speed to control the looper angle constant,
Note that the steady-state term of the quadratic term (b) of the equation (2) related to the looper angle becomes larger as the looper angle becomes lower, and it is conceivable to reduce the gain of the control device so as to cancel it. However, such a gain change, on the contrary, results in an increase in the fluctuation of tension between stands.

The present invention has been made to solve the above-mentioned conventional problems. When rolling a material to be rolled by a continuous rolling mill having two or more stands equipped with loopers between the stands, the tension between the stands and the looper are increased. When fluctuates,
An object of the present invention is to stably control the inter-stand tension and the looper angle to a target value without depending on the change in the characteristics due to the looper angle.

[0025]

A first aspect of the present invention is to roll a rolling material of a rolling stand by rolling a material to be rolled by a continuous rolling mill having two or more stands equipped with a looper between the rolling stands. By controlling the torque of the looper and the tension of the material to be rolled between the stands and the angle of the looper to a target value, in the method for controlling the tension between the stands and the looper in the continuous rolling mill, the looper angle is The above problem is solved by increasing the gain of the control device that measures the roll rotation speed command value of the rolling stand during rolling, and increases the gain when the looper angle is smaller.

According to a second aspect of the present invention, in the same inter-stand tension and looper control method, the looper angle is measured during rolling, and the gain of the control device for calculating the torque command value of the looper is set when the looper angle is large. The problem is similarly solved by increasing the size.

According to a third aspect of the present invention, in the same inter-stand tension and looper control method, the looper angle is measured during rolling, and the gain of the control device for calculating the roll rotation speed command value of the rolling stand is set to the looper angle. The problem is similarly solved by increasing the gain when the looper angle is small and increasing the gain of the control device that calculates the torque command value of the looper when the looper angle is large.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

In the method of controlling the tension between the stands and the looper in the continuous rolling mill according to the embodiment of the present invention, the tension and the looper angle generated in the material to be rolled between the stands are controlled by operating the roll rotation speed and the torque of the looper. When controlling to a target value, calculated by the setting calculation result performed prior to rolling, based on the dimensions and tension target value of the material to be rolled between the stands, looper angle target value, etc., the roll rotation speed command value and Design a controller that calculates the looper torque command value.

In the past, the control device designed before rolling was operated under constant conditions during rolling, whereas in the present embodiment, the control target based on the change in looper angle is based on the measured looper angle. In consideration of the change in the characteristics, the operating condition of the control device that calculates the command value (operation amount) is changed.

That is, the amount of feedback such as the tension between the stands and the looper angle, or the amount based on the amount of feedback such as the amount obtained by integrating or differentiating the feedback amount or the amount obtained by proportionally integrating the product is multiplied, and the roll rotation is the operation amount. The smaller the looper angle, the larger the gain of the control device that calculates the speed command value.

Further, a feedback amount such as a tension between stands or a looper angle or an amount based on a feedback amount such as an amount obtained by integrating or differentiating the feedback amount or an amount obtained by proportionally integrating is multiplied to obtain a looper torque command as an operation amount. The larger the looper angle, the larger the gain of the control device that calculates the value.

In this embodiment, by changing the operation status of the control device in this way, when the inter-stand tension and the looper angle fluctuate from the target values, the inter-stand inter-stand does not change regardless of the change in the characteristics due to the looper angle. It is possible to stably recover the tension and the looper angle to the target values.

Next, referring to the drawings, as an example of a more specific embodiment, in controlling the inter-stand tension and the looper in a hot rolling mill, the looper angle is fed back to the roll rotation speed of the upstream rolling stand. An example of applying the control to make the looper angle constant will be described in detail.

FIG. 2 is an overall configuration diagram when the method of the present invention is applied to two adjacent stands in a hot rolling mill. 1 is a material to be rolled, 2 and 3 are two adjacent i-th stand and i + 1-th stand, and 2a, 2b, 3a, 3b
Represents a work roll. The work rolls 2a, 2b are driven by a motor 5, and the motor 5 is controlled by a speed controller 8 so that the work rolls 2a, 2b rotate at a target speed value.

Further, the looper 4 installed between the stands
Is a material 1 to be rolled while being transferred from left to right in the figure
Is supported from below and is equipped with a looper roll 4a at its tip, and a motor 6 for applying a driving torque to the looper 4 is installed at the base of the looper arm 4b. Is controlled to occur.

In the control gain changing device 14 applied to the present embodiment, for example, when the detected value of the looper angle is inputted from the angle detector 13, the tension and looper angle control device 15 is obtained.
Calculate the change amount of the control gain used in. The tension and looper angle control device 15 changes the control gain according to the amount of change in the control gain input from the control gain changing device 14, and calculates the command value for the looper torque control device 10 and the speed control device 8.

The calculation of the control gain change amount by the control gain change device 14 is performed as follows.

In the first embodiment according to the first aspect of the invention, for example, in order to control the looper angle to a target value, the roll rotation angle feedback is fed back to calculate a roll rotation speed command value for the speed control device 8. The speed command gain Gv is set, for example, as shown in FIG.
As shown in (3), the smaller the looper angle, the larger it becomes in proportion to the change in the equation (4) with respect to the looper angle.

Further, in the second embodiment according to the second aspect of the invention, the looper torque command gain Gg for calculating the looper torque command value for the looper torque control device 10 by feeding back the looper speed in order to suppress the looper fluctuation is the looper damper coefficient D. In order to ensure the stability of the control system, the correction amount of the looper damper coefficient D for compensating for the change of the damping constant ζ with respect to the change of the looper angle as shown in the equation (3), and To do. When the looper torque command gain Gg is determined in this manner, the gain Gg becomes larger as the looper angle is larger as shown in FIG. 4, for example, as is clear from the equation (4).

Further, in the third embodiment according to the third aspect of the invention, the gain change executed in the first embodiment and the second embodiment is simultaneously performed. However, when the gain is changed at the same time, the change in the gain for calculating the looper torque command to the looper torque control device has the effect of increasing the damper term D of the looper.
After that, the gain for calculating the roll rotation speed command value is changed. The broken lines in FIGS. 3 and 4 show the case of the prior art in which the gains Gv and Gg are constant even if the looper angle changes.

Next, FIGS. 5 and 6 show the control results according to the example when the third embodiment according to the present invention is applied to the simulator of the continuous hot rolling mill consisting of two stands.

In FIGS. 5 and 6, the first stand and the second stand are shown.
The material to be rolled between stands has a plate thickness of 6 mm and a plate width of 1500 m
The target tension between these stands is 10M
Pa and the target looper angle were set to 14 degrees, and the tension and looper angle of the material to be rolled when rolling the general steel are shown in comparison between the present example and the conventional method. FIG. 5 shows the control result of the tension between the stands, and FIG. 6 shows the control result of the looper angle.

As is clear from FIGS. 5 and 6, according to the present embodiment, both the inter-stand tension fluctuation and the looper angle fluctuation are suppressed as compared with the conventional method, and in particular, the inter-stand tension with respect to the target tension. Is greatly suppressed.

The present invention has been specifically described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

For example, in the present invention, the looper speed control system may be used in combination so that the tension and looper angle control value 15 gives the looper speed command value to the looper speed control system.

The looper angle may be fed back to the roll rotation speed of the rolling stand on the downstream side to control the looper angle constant, or may be used in combination with a strip thickness control system. Further, the control target is not limited to hot rolling.

Also in the non-interference control and the H∞ control described as the prior art, the tension and the looper system model used in the design process change according to the looper angle as already described, and therefore the gain is increased. If a constant value is maintained during rolling, the control performance will deteriorate due to changes in the looper angle. Therefore, if the present invention is applied to these control methods and the gain is changed during rolling, control performance can be maintained regardless of changes in the looper angle. As a concrete embodiment thereof, the same form as that shown in FIG. 2 may be used, but a tension and looper angle control value 1 is used by using a looper speed control system together.
5 may give a looper speed command to the looper speed control system.

[0049]

As described above, according to the present invention,
When rolling a material to be rolled by a continuous rolling mill with two or more stands equipped with loopers between the stands, the looper angle is measured during rolling, and control is performed in consideration of the characteristic change of the control target due to the change of the looper angle. Since the operating condition of the apparatus is changed, when the inter-stand tension and the looper angle fluctuate from the target values, the inter-stand tension and the looper angle can be controlled to be stably restored to the target values. Therefore, in plate materials such as steel plates, it is known that when the tension changes during rolling, the plate width changes, but the present invention improves the controllability of making the plate width constant and improves the product yield. Is possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a physical model showing characteristics from a roll rotation speed command and a looper torque command to a tension between stands and a looper angle.

FIG. 2 is a block diagram showing a control system used in an embodiment of the present invention applied to hot rolling.

FIG. 3 is a diagram showing a gain according to an embodiment of the present invention in comparison with a conventional method.

FIG. 4 is another diagram showing the gain according to the embodiment of the present invention in comparison with the conventional method.

FIG. 5 is a diagram showing an example of tension control response according to the present invention in comparison with a conventional method.

FIG. 6 is a diagram showing an example of a looper angle control response according to the present invention in comparison with a conventional method.

[Explanation of symbols]

 1 ... Rolled material 2 ... i-th stand 3 ... i + 1st stand 2a, 2b, 3a, 3b ... Work roll 4 ... Looper 4a ... Looper roll 4b ... Looper arm 5, 6, 7 ... Motor 8, 9 ... Speed control device 10 ... Looper torque control device 11, 12 ... Rolling position control device 13 ... Looper angle detector 14 ... Control gain changing device 15 ... Tension and looper angle control device 16 ... Host computer

Front Page Continuation (72) Inventor Akira Torao 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Inside the Kawasaki Steel Research Laboratory (72) Inventor Fumihiko Ichikawa 1 Kawasaki-cho, Chuo-ku, Chiba Chiba Kawasaki Steel Co., Ltd. Company Technology Research Institute (72) Inventor Kiyoshi Ueda, Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Works

Claims (2)

[Claims] 1. A stand for rolling a material to be rolled by a continuous rolling mill having two or more stands equipped with a looper between rolling stands, by operating a roll rotation speed of the rolling stand and a torque of the looper. Controlling the tension generated in the rolled material between and the angle of the looper to a target value,
In a method for controlling inter-stand tension and looper in a continuous rolling mill, the looper angle is measured during rolling, and the gain of a controller for calculating a roll rotation speed command value of the rolling stand is increased as the looper angle is smaller. And / or a control method for controlling the inter-stand tension and the looper in the continuous rolling mill, wherein the gain of the control device that calculates the torque command value of the looper is increased as the looper angle is larger. 2. The operation amount according to claim 1, wherein a gain of a control device for calculating an operation amount of a roll rotation speed of a rolling stand is multiplied by an amount based on a feedback amount such as a tension between stands and a looper angle. Is a coefficient for calculating the roll rotation speed command value, and the gain of the control device that calculates the operation amount of the looper torque is multiplied by the amount based on the feedback amount such as the tension between the stands and the looper angle, and the operation is performed. A method for controlling inter-stand tension and looper in a continuous rolling mill, which is a coefficient for calculating a looper speed command value or a looper torque command value, which is a quantity.