JP2002045909A - Method for controlling interstand tension and looper angle in continuous hot rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method by which the offset in interstand tension and looper angle is not generated as the stability of control is held even at accelerated rolling. SOLUTION: The speed V of the main motor which is multiplied by a gain as the basic manipulated variable of a fluctuation compensator is feedforwardwise outputted as Δv3, added to Δv1 and Δv2 and it is used for correcting the rolling speed as Δv. In the form of this practice, the gain at this time is determined in accordance with the deviation from the target value σof the interstand tension σ. The inputted interstand tension σis subtracted from the target value (σ ref) and proportional-plus-integral operation is performed to the difference by the operation of (k1+k2/s) (The 1/s is a sign showing integration.). The speed v of the main motor is multiplied by the result as the gain and it is outputted as the Δv3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the tension between the stands and the looper angle of a hot continuous rolling mill comprising a plurality of stands. The present invention relates to a control method for completely eliminating the control method.

[0002]

2. Description of the Related Art In a continuous hot rolling mill, maintaining a constant tension between stands of a material to be rolled (sometimes simply referred to as "tension between stands" and a looper angle in the present specification) requires a stable flow. This is a very important issue in securing boards and ensuring high quality products. In particular, if the tension between stands is too large, a "width shrinkage" phenomenon occurs in which the plate width becomes narrow, and if the tension between stands is too small, the sheet passing property is deteriorated. Therefore,
Matching the stand-to-stand tension with the target value is also important from the viewpoint of yield.

In order to solve such a problem, there are the following control means conventionally employed. (1) Looper constant height control (looper angle control) The looper height is kept constant and the tension is indirectly controlled, which is a classic method. The amount of observation is the looper angle, and the amount of operation is the peripheral speed of the work roll on the stand opposite to the pivot stand (the peripheral speed of the work roll is sometimes referred to as “main machine speed” in this specification). Will be At this time, a predetermined torque for supporting the torque applied to the looper shaft by the looper's own weight, the plate weight on the looper, and the target plate tension when the looper height is at the target position is given as the looper torque. This can be realized by supplying a predetermined current to the looper motor. Thereby, the tension between stands is also indirectly controlled.

(2) Simultaneous control of stand-to-stand tension and looper angle The interference between the looper angle and the stand-to-stand tension is a well-known phenomenon. There is a method of controlling the tension control between the looper and the stand independently, or a method of applying the optimal control theory by treating the interference system between the looper and the stand as a multivariable control system.
Each is applied to the actual machine.

An example of such control will be described with reference to FIGS. FIG. 4 shows the i-th stand and the (i + 1) -th stand. 1 is a work roll, 2 is a backup roll, 3 is a rolled material, 4 is a looper, 5 is a main motor (main machine), 6 is a looper motor, 7 is a control device.

In this control system, a pivot stand is provided at a rear stage, and an operation amount of the main machine speed is added to an i-th stand which is a front stage. A load meter is attached to the looper 4 and detects a load received from the material 3 to be rolled. If the value of the load meter, the looper angle θ, and the thickness and width of the material 3 to be rolled are known, the inter-stand tension σ can be detected based on these values. It is input to the control device 7. The illustration of the stand-to-stand tension calculating mechanism is omitted in FIG.

At the same time, a looper angle θ and a looper angular velocity θ dot are detected from a goniometer coupled to the looper motor 6 and input to the control device 7. Also,
The main engine speed v is input to the control device 7 from the main motor 5. The control device 7 receives these values as inputs,
The main engine speed change amount Δv and the looper motor torque change amount Δτ are output. The main engine speed control device and the looper motor control device respectively control the main engine speed and the looper torque by adding these change amounts to the reference speed v and the reference torque τ to obtain command values.

FIG. 5 is a control block diagram showing this control system and process. The detected looper angle θ and the stand-to-stand tension σ are their target values θref,
The difference Δθ, Δσ is input to the first computing unit. The first computing unit calculates the value

[0009]

(Equation 1)

Then, the first change amount Δτ _{1 of} the looper torque and the first change amount Δv _{1 of} the main engine speed are calculated. Here, 1 / s indicates integration, and F ₂ is a matrix.

On the other hand, the looper angle θ, the stand-to-stand tension σ, the looper angular velocity θ dots, and the main engine speed v are input to the second computing unit. The second computing unit converts these values into:

[0012]

(Equation 2)

Then, the looper torque second change amount Δτ ₂ and the main engine speed second change amount Δv ₂ are calculated. Here, F ₁ is a matrix.

The first change amount Δτ ₁ of the looper torque, the second change amount Δτ ₂ of the looper torque, the first change amount Δv ₁ of the main engine speed, and the second change amount Δv _{2 of} the main engine speed are respectively added by an adder, and the above-described looper motor torque change is performed. Amount Δτ, main engine speed change amount Δ
output as v.

[0015]

Incidentally, in a continuous hot rolling mill, accelerated rolling is performed in order to compensate for a decrease in the temperature of a non-rolled material with the passage of time during rolling and to secure a finish rolling temperature. It is usually done. At the time of accelerated rolling, the main machine control device generally includes a mechanism for performing acceleration while maintaining the main machine speed ratio of each stand constant. This is to keep the mass flow (volume velocity) between the stands constant.

However, at the time of accelerated rolling, the outlet plate thickness at each stand cannot be kept constant. This is because the deformation resistance of the material to be rolled changes with the accelerated rolling, or the thickness of the oil film of the rolling mill roll bearing changes, and the roll gap changes accordingly. Control devices for compensating for roll gap variations are typically incorporated into rolling mill controls, but their functions are not perfect.

Further, even when the deformation resistance of the material to be rolled changes, the plate thickness of each stand is kept to some extent by the automatic plate thickness control device, but this is not perfect.
In addition, with the accelerated rolling, the advance rate of each stand also changes, which causes the mass flow to be disturbed. For this reason, it is usual that the mass flow cannot be kept constant even if acceleration is performed while keeping the main engine speed ratio of each stand constant.

When the mass flows between the stands do not match, the height control of the looper functions, and the mismatch of the mass flows is removed by changing the main machine speed. However, when the rolling speed is accelerated with a constant acceleration, the imbalance of the mass flow generated between the stands changes in a ramp shape. In this case, in any of the conventional control methods as described above, the target value tracking performance of the looper is a mere regulator or a type 1 servo system. It is impossible to remove the offset of the looper height due to the ramp-shaped mass flow difference that occurs.
Along with this, occurrence of an offset in tension control between stands is inevitable.

As a method of reducing this offset,
Generally, a method of increasing the gain of integral compensation is employed. However, in the case of a material having a large control model error such as a thin material or a hard material, if the integral gain is increased, the control tends to be unstable, so that the gain cannot be increased.
After all, the problem that a large offset remained was inevitable.

FIG. 6 shows this state. The horizontal axis is rolled.
Elapsed time, looper angle and stand length for it
It shows the fluctuation of the force. Looper angle set value is 15 °
Has an offset of about 1 °,
The set value of tension between arms is 1.5kg / mm ^TwoAbout 0.1
5kg / mm^TwoOffset.

The present invention has been made in order to solve such a problem. Even during accelerated rolling, the stand-to-stand tension and the offset of the looper angle are removed while maintaining control stability. It is an object of the present invention to provide a simple control method capable of causing the control value to match a predetermined target value.

[0022]

A first means for solving the above-mentioned problem is a method for controlling the tension between the stands and the looper angle of a hot continuous rolling mill comprising a plurality of stands, wherein at least the tension between the stands and the looper are controlled. In the main machine speed and looper torque operated by feedback control and detecting the looper angle, an operation amount that cancels at least one of the stand-to-stand tension caused by the accelerated rolling and the offset from the target value of the looper angle is specified by the main machine speed command. A method for controlling the tension between stands and the looper angle of a continuous hot rolling mill characterized by being added to (1).

In the present means, in addition to the control means conventionally used, an operation amount for canceling at least one of the stand-to-stand tension caused by the accelerated rolling and the offset of the looper angle from the target value is controlled by the main machine speed command. , The main engine speed is changed so that if there is an offset, it is canceled so that the offset is eliminated.

A second means for solving the above-mentioned problem is as follows.
The first means is characterized in that an operation amount for canceling the offset is calculated based on a main machine speed and a stand-to-stand tension signal (claim 2).

In the first means, the presence or absence and the amount of the offset must be detected. In this means, the presence or absence of the offset is detected based on the tension signal between stands. Since the resolution of the tension between stands can be compared to the looper angle, the presence of a small offset can be reliably detected. Further, since the change amount of the main engine speed required to eliminate the offset having the same magnitude has a relationship with the main engine speed at that time, the operation amount is determined in this means in consideration of this as well. . Therefore, in this means, the offset of the tension between stands can be eliminated reliably and without disturbing the stability of control. Accordingly, the offset of the looper height is eliminated by the conventional control.

A third means for solving the above-mentioned problem is:
The second means, wherein an operation amount for canceling the offset is obtained by multiplying a main machine speed by a gain proportional to a deviation signal between a tension signal between stands and a target value thereof. (Claim 3).

In this means, the offset generated due to the response delay is eliminated by adding the main engine speed itself as a basic operation amount in a feed-forward manner. That is, since the main engine speed changes in the form of a ramp, by feeding it forward, it is possible to eliminate the offset generated due to the delay in response to the change in the ramp. It is preferable that the feedforward gain at that time be proportional to the offset amount. In this means, since the main engine speed multiplied by a gain proportional to the deviation signal between the stand-to-stand tension signal and its target value is used as the feedforward operation amount, the offset can be effectively removed.

A fourth means for solving the above-mentioned problem is:
The second means, wherein a manipulated variable for canceling the offset is multiplied by a gain obtained by performing a PI operation calculation on a deviation signal between the stand-to-stand tension signal and a target value thereof, as a gain. It is characterized in that it is calculated (claim 4).

Most offsets are eliminated by the third means. However, the causes of the offset include changes in rolling phenomena due to acceleration (for example, advanced ratio,
The change in reverse speed causes a speed difference disturbance, which is also a function of the speed. Since these are multiplied, not added, to form a total disturbance, there is a case where the offset cannot be completely removed only by the third means. Therefore, in the present means, not only the amount of offset but also its integral value is considered when determining the feedforward gain based on the main engine speed. Therefore, the offset can be removed more reliably.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, the configuration of the rolling mill and the configuration of the control system as a whole are assumed to be the same as the conventional one shown in FIG. 4, and a control block diagram corresponding to FIG. 5 will be described. FIG. 1 is a control block diagram showing a control system and a process for realizing a control method according to an embodiment of the present invention. The detected looper angle θ and the stand-to-stand tension σ are compared with their target values θref and σref, respectively, and the differences Δθ and Δ
σ is input to the first computing unit. The first computing unit calculates the value

[0031]

(Equation 3)

The following calculation is performed to calculate the first change amount Δτ _{1 of} the looper torque and the first change amount Δv _{1 of} the main engine speed. Here, 1 / s indicates integration, and F ₂ is a matrix.

On the other hand, the looper angle θ, the stand-to-stand tension σ, the looper angular velocity θ dots, and the main machine speed v are input to the second computing unit. The second computing unit converts these values into:

[0034]

(Equation 4)

The following calculations are performed to calculate the looper torque second change amount Δτ ₂ and the main engine speed second change amount Δv ₂ . Here, F ₁ is a matrix.

The first change amount Δτ ₁ of the looper torque, the second change amount Δτ ₂ of the looper torque, the first change amount Δv ₁ of the main engine speed, and the second change amount Δv _{2 of} the main engine speed are respectively added by an adder, and the above-described looper motor torque change is performed. Amount Δτ, main engine speed change amount Δ
output as v.

The above operation is the same as that of the conventional control system shown in FIG. The present embodiment differs from the conventional control system in that a fluctuation compensator is added to this.
FIG. 2 shows details of an example of the fluctuation compensator. What is obtained by multiplying the main engine speed V by the gain as the basic operation amount of the fluctuation compensator
It is output in a feedforward manner as Δv ₃ in FIG. 1, and is added to Δv ₁ and Δv ₂ in FIG.
It is used for correcting the rolling speed.

In this embodiment, the gain at this time is determined according to the deviation of the inter-stand tension σ from the target value. The input stand-to-stand tension σ is subtracted from the target value σref, and a proportional integral calculation is performed on the difference by (k ₁ + k ₂ / s) calculation (1 / s is a symbol indicating integration). Done. The result is the main engine speed v as a gain.
And output as Δv ₃ .

In some cases, the proportional-integral calculation is not performed on the stand-to-stand tension deviation, and the main machine speed may be multiplied by the amount proportional to the stand-to-stand tension as a gain.
When the integration operation is performed as in this means, the offset accompanying the change in the advance rate, the reverse rate, and the like can be removed at the same time. In this manner, when the offset of the tension between stands is eliminated, the offset of the looper angle is also eliminated by the control operation of the conventional control system.

FIG. 3 shows the variation of the looper angle and the stand-to-stand tension with respect to the elapsed rolling time on the horizontal axis when the present invention is carried out. The setting value of the looper angle is
The setting value of the tension between the stand and the stand is 1.5 kg / mm ² . As can be seen by comparing FIGS. 3 and 6, in FIG. 3, which is a result of implementing the present invention, the offset of the looper angle and the stand-to-stand tension, which has not been conventionally solved, has been solved.

In the above-described embodiment, the control is performed so as to detect the offset amount of the tension between stands and eliminate the offset amount. However, the offset of the looper height is detected and eliminated. The same control can be obtained even by applying various controls. The basic control method is shown in FIG.
However, if there is no special situation, it can be used in addition to all of the control methods generally used conventionally.

[0042]

As described above, in the present invention, it is possible to prevent the occurrence of offsets in the looper angle and the stand-to-stand tension without impairing the stability of the control system even when performing accelerated rolling. it can.

[Brief description of the drawings]

FIG. 1 is a control block diagram showing a control system and a process for realizing a control method which is an example of an embodiment of the present invention.

FIG. 2 is a diagram illustrating details of an example of a fluctuation compensator.

FIG. 3 is a diagram showing a change in a looper angle and a tension between stands when the present invention is implemented.

FIG. 4 is a diagram showing an outline of a conventional inter-stand tension / looper height control system.

FIG. 5 is a control block diagram showing a conventional inter-stand tension / looper height control system and process.

FIG. 6 is a diagram showing a change in a looper angle and a tension between stands during accelerated rolling in the conventional control.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 work roll 2 backup roll 3 rolled material 4 looper 5 main motor (main machine) 6 looper motor 7 control device

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Sekine 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) in Nihon Kokan Co., Ltd. 4E024 AA08 BB04 CC03 DD10 EE01 GG01

Claims (4)

[Claims] 1. A method for controlling inter-stand tension and looper angle of a hot continuous rolling mill comprising a plurality of stands, wherein at least the inter-stand tension and looper angle are detected, and the main machine speed and looper torque are operated by feedback control. Wherein an operation amount for canceling at least one of a tension between stands caused by accelerated rolling and an offset from a target value of a looper angle is added to a main machine speed / speed command, and a tension between stands of a hot continuous rolling mill, And control method of looper angle. 2. The control method of a stand-to-stand tension and a looper angle of a hot continuous rolling mill according to claim 1, wherein an operation amount for canceling the offset is determined based on a main machine speed and a stand-to-stand tension signal. A method for controlling the tension between the stands and the looper angle of a hot continuous rolling mill, wherein the method is calculated. 3. The method for controlling a tension between stands and a looper angle of a hot continuous rolling mill according to claim 2, wherein the operation amount for canceling the offset is set to a main machine speed, a tension between stand signals, and A method for controlling the tension between stands and a looper angle of a hot continuous rolling mill, wherein a gain proportional to a deviation signal from a target value is multiplied. 4. The method of controlling a tension between stands and a looper angle of a continuous hot rolling mill according to claim 2, wherein an operation amount for canceling the offset is set to a main machine speed, a tension between stands signal, and a control signal. A method for controlling stand-to-stand tension and looper angle of a hot continuous rolling mill, wherein a value obtained by performing a PI operation calculation on a deviation signal from a target value is multiplied and calculated.