JPH0261325B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a continuous rolling mill, and more particularly to a looper control device for controlling the looper operating angle and tension between stands.

[Technical background of the invention]

When rolling a plate using a continuous rolling mill, important factors for evaluating product quality include plate thickness, plate width, plate crown amount, and plate flatness, and the influence of inter-stand tension value on these factors. is large, so it is desirable to keep it as constant as possible. For this reason, in continuous hot rolling mills, control is performed to absorb changes in tension values using a looper mechanism provided between each rolling stand. Furthermore, since it is required for rolling operations to keep the fluctuation of the looper operating angle small, the roll speed of the stand adjacent to the looper is also corrected.

FIG. 1 shows the basic configuration of a looper and a block diagram of a conventional control device that controls the looper.

After the material to be rolled 101 passes through the rolling stand 2 equipped with rolling rolls 102a and 102b,
It advances to a rolling stand 103 comprising rolling rolls 103a and 103b, between which it is in contact with a looper mechanism 104.

The looper operating angle θ of the looper mechanism 104 is detected by a looper operating angle detector 105, and a calculation device 106 calculates the amount of looper torque so as to always maintain the target tension value in accordance with the looper operating angle θ. It will be done.

Therefore, the current target value of the looper drive motor necessary to generate the above-mentioned looper torque amount is determined by the calculation device 106.
The current is applied to the current control device 107 of the looper drive motor, and the looper drive motor 108 is driven by the current control device 107.

On the other hand, the detection signal of the looper operating angle detector 105 is also applied to the arithmetic device 109.
At 09, a speed target value of the roll drive motor 120 is calculated in order to return the looper operating angle θ, which has been raised or lowered due to the inter-stand tension control, to the target value. This speed target is applied from the calculation device 109 to the speed control device 110 of the roll drive motor 120, and the roll drive motor 120 is driven by the speed control device 110.

[Problems with background technology]

As described above, the conventional looper control device performs inter-stand tension control and looper operating angle control independently, and does not take into account interference between them. Therefore, in such a looper control device, the material length between the stands changes by modifying the speed of the roll drive motor 120, and the looper drive motor 1
08 starts, but on the other hand, the roll drive motor 120 performs looper operation angle control to follow this, so this looper operation angle control has an adverse effect on the inter-stand tension control, causing fluctuations. It has the disadvantage that it may become large or even unstable.

Furthermore, if the looper operating angle is controlled in order to suppress this tension fluctuation, the response of the control must be lowered, resulting in the disadvantage that it is not possible to follow disturbances that change quickly over time.

[Purpose of the invention]

The present invention has been made in order to overcome the difficulties of conventional devices, and provides a looper control device for a continuous rolling mill that can sufficiently suppress inter-stand tension fluctuations of rolled material and has excellent responsiveness. Its purpose is to provide.

[Summary of the invention]

In the present invention, the looper control system is a two-input, two-output multivariable control system, and its control objective is to minimize the amount of variation in the looper angle and the amount of variation in tension. One of the manipulated variables for this purpose is the looper drive motor speed, and the other is the main engine motor speed. Required calculations are performed from these two inputs to derive two outputs: looper angle and tension. Additionally, looper control is also performed based on the actual tension by detecting the tension between the stands. The control system is configured in this way, taking into account mutual interference between variables.

[Embodiments of the invention]

An embodiment of the present invention shown in FIG. 2 will be described below.

FIG. 2 is a control block diagram showing the configuration of the looper control device according to the present invention. Note that FIG. 2 mainly shows the flow of control signals.

In Fig. 2, a looper drive motor speed control device (hereinafter referred to as a looper speed control device) 1A
The speed target value _REF input to is the speed set value ^* _R
It is synthesized by adding _EF and the speed target value correction amount _ΔREF . The speed target value correction amount Δ _REF is
Each means indicated by A○ to C○ below A○ Integral operation by integral gain k ₂₁ and integrator 10A and tension detection regarding the deviation between the detected tension value T _f of the rolled material between stands and the tension target value T _fR value
Deviation ΔT _f between T _f and tension detection value T ^* _f at the start of control
A means of performing proportional action with a proportional gain f ₂₁ .

I○ Regarding the deviation between _the looper operating angle detection _value θ and the looper operating angle target value θ ^*
A means for performing proportional operation using a proportional gain _f22 for the deviation Δθ.

○ Integral operation output Z ₃ of the PI controller for speed control in the looper speed control device, Integral operation output Z ₄ of the PI controller for minor current control in the looper speed control device, Looper drive motor armature current I, Looper drive motor rotation speed Detection value N, Main engine motor rotational speed detection value N _R , Integral operation output Z ₁ of the PI controller for speed control in the main engine motor speed control device (hereinafter referred to as the main engine speed control device), Minor current in the main engine speed control device The integral operation output Z ₂ of the control PI controller and the main motor armature current I _a , and the respective control start values Z ₃ ^* , Z ₄ ^* ,
The deviations from I ^* , N〓, N _R ^* , Z ₁ ^* , Z ₂ ^* and I _a ^* are proportional to ΔZ ₃ , ΔZ ₄ , ΔI, ΔN, ΔN _R , ΔZ ₁ , ΔZ ₂ and ΔI _a , respectively. Gain f ₂₃ , f ₂₄ , f ₂₅ ,
Means for performing proportional action consisting of f ₂₆ , f ₂₇ , f ₂₈ , f ₂₉ , and f ₃₀ .

It is synthesized by adding .

On the other hand, the speed target value N _REF input to the main engine speed control device 4A is synthesized by adding the speed set value N ^* _REF and the speed target value correction amount ΔN _REF .

The speed target value correction amount ΔN _REF is determined by each means shown in the following circles, that is, the integral gain for the deviation between the detected tension value T _f of the rolled material between the stands and the tension target value T _fR . Integral operation by k ₁₁ and integrator 9A, and tension detection value T _f
Means for performing proportional operation using a proportional gain _f11 for the deviation ΔT _f between the detected tension value T _f ^* at the start of control.

○ Regarding the deviation between the looper operating angle detection value θ and the looper operating angle target value θ _R , the integral operation by the integral gain k ₁₂ and the integrator 9A, the looper operating angle detection value θ and the looper operating angle detection value θ at the start of control. Means to perform proportional operation with proportional gain f ₁₂ for deviation Δθ from ^* .

○ Integral operation output Z ₃ of the PI controller for speed control in the looper speed control device, integral operation output Z ₄ of the PI controller for minor current control in the looper speed control device, detected value N of looper drive motor rotation speed, main engine speed control device The integral operation output Z ₁ of the PI controller for internal speed control, the integral operation output Z ₂ of the PI controller of the minor current control device in the main engine speed control device, and the main engine motor armature current I _a ,
Values at the start of each control Z ₃ ^* , Z ₄ ^* , I ^* , N ^* , N _R
^* , Z ₁ ^* , Z ₂ ^* and deviation from I _a ^* ΔZ ₃ , ΔZ ₄ , ΔI,
Proportional gains f ₁₃ , f ₁₄ , f ₁₅ , f ₁₆ , f ₁₇ , f _{18 ,} f ₁₉ for ΔN, ΔN _R , ΔZ ₁ , ΔZ 2 and ΔI _a , respectively
and means for performing proportional action consisting of f ₂₀ .

It is synthesized by adding .

Next, the operation of the continuous rolling mill looper control device of the present invention constructed as described above will be explained.

The looper dynamic characteristic model of a continuous rolling mill is a nonlinear model, but by Taylor expansion near a certain steady state, it can be expressed in the form of a linear state equation as shown in (Equation 1) and (Equation 2). .

x〓=A・x+B・u+w...(Formula 1) y=C・x...(Formula 2) However, x means the time differential dx/dt. x,
u and y are vectors represented by (Equation 3), (Equation 4), and (Equation 5), respectively, and w is a 10-dimensional disturbance vector. Also, A, B, and C are 10×10 and 10×, respectively.
It is a 2,2×10 constant matrix.

x = [ΔT _f , Δθ, ΔZ ₃ , ΔZ ₄ , ΔI, ΔN, ΔN _R , ΔZ ₁ , ΔZ ₂ , ΔI _a ] ^T (state vector) ... (3 formula) u = [ΔN _REF , ΔN _REF ] ^T (operation vector)
...(Formula 4) y=[ΔT _f , Δθ] ^T (output vector)
...(Formula 5) Here, the symbol T represents transposition.

The purpose of the looper control is to suppress the deviation ΔT _f of the inter-stand tension from the target value and the deviation Δθ of the looper operating angle from the target value as small as possible.
To achieve this purpose, an integral type optimal regulator is effective in the sense of minimizing a certain quadratic evaluation function. Therefore, (6
The operation vector u may be configured as shown in formula).

u=-R ^-1 B ^T P ₂₁ ∫ ^t ₀ (y-y _R ) dt -R ^-1 B ^T P ₂₂ (x-x ₀ )+u ₀ ... (Formula 6) Here, R is 2×2 Diagonal positive definite matrix, y _R is the target value vector of the output vector y, x ₀ is the state vector x
The initial value vector of u ₀ is the initial value vector of the operation vector u.

In addition, P ₂₁ and P ₂₂ are expressed as follows: P+ ^T P-PR ^{-1 T} P+Q=0
...(Equation 7) is a submatrix of the semi-definite 12×12 matrix P of the Riccati equation, and the relationship between P and P ₂₁ and P ₂₂ is It is. In addition, in (7), are (9), respectively,
It is a 12×12, 12×2 constant matrix given by (Equation 10), and Q is a 12-dimensional diagonal quasi-definite matrix.

From the above, the operation vector u = [ΔN _REF , Δ _REF ] ^T , which is composed of the speed target value correction amount ΔN _REF for the main engine speed control device 4A and the speed target value correction amount Δ _REF for the looper speed control device 1A, is determined by (Equation 6 )
You can decide accordingly.

Replace with (formula 6) R ^-1 B ^T P ₂₁ ≡k ₁₁ , k ₁₂ k ₂₁ , k ₂₂ ... (formula 11) −R ^-1 B ^T P ₂₂ = f ₁₁ , f ₁₂ , f ₁₃ , f ₁₄ , f ₁₅ , f ₁₆ ,
f ₁₇ , f ₁₈ , f ₁₉ , f ₂₀ −R ^-1 B ^T P ₂₂ = f ₁₁ , f ₁₂ , f ₁₃ , f ₁₄ , f ₁₅ , f ₁₆ ,
f ₁₇ , f ₁₈ , f ₁₉ , f ₂₀ f ₂₁ , f ₂₂ , f ₂₃ , f ₂₄ , f 25 , f ₂₆ , f ₂₇ , f ₂₈ , f _{29 ,} f ₃₀ …
...(Equation 12) and write down (Equation 6) specifically, (Equation 13)
get.

However, ΔN _REF ⁰ and Δ _REF ⁰ represent the initial values of ΔN _REF and Δ _REF , respectively.

Figure 2 is a block diagram of the above equation (13), and its explanation is as described above.

Main engine speed target value correction amount ΔN _REF according to (formula 13)
and the looper speed target value correction amount Δ _REF are determined, and the detected rotational speed value N _R of the main engine motor 5A and the detected rotational speed N of the looper drive motor 2A are corrected to follow them, and the detected tension value T _f and the detected rotational speed value N of the looper drive motor 2A are corrected to follow them. The operating angle detection value θ is controlled to be close to the target value.

In addition, in the above configuration, _the control system was constructed in such a way that _all the elements of _the state _vector You can omit it.

This is why the present invention is provided with means for performing a proportional operation based on the deviation between the detected value during control and the value detected at the start of control.

In looper control, multivariable control is not always performed.

Another control is in operation until the approximately 10 m long rolled material is passed through the continuous rolling mill, and at a certain timing it switches to multivariable control. Therefore, the initial state in multivariable control is the value of each signal "at the start of control".

Since the control system is configured based on the deviation from this initial state, the proportional operation that forms the state feedback of the optimal regulator applied in the present invention requires the detection value at the time of control and the detection value at the start of control. The deviation from ΔTf, Δθ, ... in equation (13) is used.

That is, regarding these proportional operations, true optimal control cannot be performed unless the "deviation between the detected value at the time of control and the detected value at the start of control" is used.

True optimal control improves tension and looper angle stability.

Further, these points are related to the fact that the present invention uses a multivariable control system as a looper control system.

Rather than considering the looper control system as a simple multi-loop system and performing only integral control, for example, in the looper operating angle control system of the present invention, the looper operating angle target value θref is given, and the Find the deviation from the looper operating angle detection value θ (negative feedback), integrate this, and then
The control performance can be improved by configuring the output stage to have a configuration in which the proportional operation that forms the state feedback of the optimum regulator described above is fed back from the looper process, and in addition to the integral operation value, the feedback given to the looper process is included. This is because mutual interference of the looper process can be absorbed and stability can be improved.

Therefore, this proportional action is essential.

Exactly the same thing can be said about the tension target value TfR of the rolled material between the stands.

〔Effect of the invention〕

Thus, according to the present invention, the following effects are recognized.

○Sa Conventional looper control systems do not take into account mutual interference between inter-stand tension control and looper operating angle control, and therefore have problems with stability. In the present invention, we have created a model faithful to physical phenomena and configured the control system by considering the looper control system as a multivariable control system with two inputs and two outputs, so mutual interference between each variable is taken into account and stability is improved. An excellent looper control device is obtained.

○C In the conventional looper control system, the control response had to be lowered in order to suppress the influence of the above-mentioned mutual interference, leading to deterioration in tracking of high-frequency disturbances. In the present invention, since the configuration is such that mutual interference between variables is taken into account, there is no need to reduce the control response, and therefore, it has excellent followability to high-frequency disturbances.

○S In the conventional looper control system, the tension between the stands was not detected, so looper control was not performed based on the actual tension, resulting in deterioration of product quality. However, in the present invention, the tension detector By installing a looper, it becomes possible to control the looper based on the actual tension, leading to improved quality.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of a conventional device.
FIG. 2 is a block diagram showing the configuration of one embodiment of the present invention. 1A...Looper motor speed control device, 2A...
Looper drive motor, 3A...Looper mechanical system, 4A
...Main engine motor speed control device, 5A...Main engine motor, 6A...Inter-stand tension generation mechanism, 9A, 1
0A...Integrator, 11-30...Proportional gain, 3
1 to 33...adder, 34 to 37...integral gain.

Claims (1)

[Claims] 1. A main motor speed control device that controls the rotational speed of the main motor that drives the rolls of the rolling stand, and an armature current that flows through the looper drive motor that drives the looper between the continuous rolling stands. In a continuous rolling mill having a looper drive motor speed control device that controls speed in a cascade manner, a first integral operation is performed on a deviation between a detected tension value of a material to be rolled between stands and a tension target value.
an integral action device, a first proportional action device that performs a first proportional action regarding the deviation between the detected tension value and the detected tension value at the time of control start; The second integral operation device performs the integral operation of 2, and the second integral operation device performs the second integral operation with respect to the deviation between the detected value of the looper operating angle and the detected value of the looper operating angle at the start of control.
a second proportional operation device that performs a proportional operation; and a third proportional operation that performs a third proportional operation regarding a deviation between a detected value of the armature current flowing through the looper drive motor and a detected value of the armature current at the start of control. a fourth proportional operation device that performs a fourth proportional operation with respect to a deviation between a rotational speed detection value of the looper drive motor and a rotational speed detection value at the time of control start; 1, 2nd, 3rd,
a first output device that combines the outputs from the fourth proportional operation device and outputs the result to the main motor speed control device as a speed target value correction amount for the main motor motor; the detected tension of the material to be rolled between the stands; A third integral operation is performed for the deviation between the tension target value and the tension target value.
an integral action device, a fifth proportional action device that performs a fifth proportional action regarding the deviation between the detected tension value and the detected tension value at the start of control; 6. Regarding the deviation between the detected value of the looper operating angle and the detected value of the looper operating angle at the start of control.
a sixth proportional operation device that performs a proportional operation; and a seventh proportional operation that performs a seventh proportional operation regarding a deviation between a detected value of the armature current flowing through the looper drive motor and a detected value of the armature current at the time of starting control. an eighth proportional operation device that performs an eighth proportional operation with respect to a deviation between a rotational speed detection value of the looper drive motor and a rotational speed detection value at the time of control start; 5, 6th, 7th,
Continuous rolling characterized by comprising a second output device that adds and synthesizes the outputs from the eighth proportional operation device and outputs the result to the looper drive motor speed control device as a speed target value correction amount of the looper drive motor speed control device. The machine's looper control device. 2. A ninth proportional operation device that performs a ninth proportional operation regarding the deviation between the rotation speed detection value of the main machine motor and the rotation speed detection value at the time of starting control; A 10th proportional operation device that performs a 10th proportional operation regarding the deviation from the speed detection value, and a first proportional operation device that adds the outputs of the 9th proportional operation device and the 10th proportional operation device to the speed target value correction amount of the main motor motor an summing device; an eleventh proportional operation device that performs an eleventh proportional operation regarding a deviation between a rotational speed detection value of the main machine motor and a rotation speed detection value at the start of control; and a detected value of an armature current flowing through the main machine motor. and a twelfth proportional operation device that performs a twelfth proportional operation regarding the deviation between the detected value of the armature current at the start of control, and the outputs of the eleventh proportional operation device and the twelfth proportional operation device are used to control the speed of the looper drive motor. The looper control device for a continuous rolling mill according to claim 1, further comprising a second addition device that adds to the speed target value correction amount of the device. 3. A 13th proportional operation device that performs a 13th proportional operation regarding the deviation from the value at the start of control of the integral operation output of the speed control PI controller in the looper drive motor speed control device; a 14th proportional operation device that performs a 14th proportional operation regarding the deviation of the integral operation output of the PI controller for minor current control from the value at the start of control; and a 14th proportional operation device for minor current control in the main engine speed control device.
The 15th proportional action is performed on the deviation of the integral action output of the PI controller from the value at the start of control.
A 16th proportional operation is performed on the deviation between the proportional operation device and the value at the start of control of the integral operation output of the PI controller for minor current control in the main machine motor speed control device.
16 proportional operation devices, further adding the outputs of the 13th, 14th, 15th, and 16th proportional operation devices to the speed target value correction amount of the main engine motor, and providing a third addition device, and controlling the speed of the looper drive motor. The 17th proportional operation is performed on the deviation of the integral operation output of the PI controller for speed control in the device from the value at the start of control.
17 proportional operation device; an 18th proportional operation device that performs an 18th proportional operation regarding the deviation between the integral operation output of the PI controller for minor current control in the looper drive motor speed control device and the value at the start of control; PI for speed control in motor speed control device
A 19th proportional operation device that performs a 19th proportional operation regarding the deviation of the integral operation output of the controller from the value at the start of control, and the integral operation output of the PI controller for minor current control in the main motor speed control device and the time at the start of control. The 20th proportional action is performed on the deviation from the value of
20 proportional operation devices, and a fourth addition device that further adds the outputs of the 17th, 18th, 19th, and 20th proportional operation devices to the speed target value correction amount of the looper drive motor speed control device. A looper control device for a continuous rolling mill according to scope 2.