JPH0523847B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Field of Application) The present invention relates to a continuous rolling mill, and particularly to a looper control device for controlling the looper angle and tension between stands. (Conventional technology) 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. Due to the large influence on the elements,
It is desirable to keep this as constant as possible. For this reason, in continuous hot rolling mills, control is performed to absorb changes in the tension value 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. 3 shows the basic configuration of the looper and a conventional control device that controls it. The material to be rolled 101 passes through a rolling stand 102 having rolling rolls 102a and 102b, and then passes through a rolling stand 102 having rolling rolls 102a and 102b.
and 103b, between which it is in contact with a looper mechanism 104. A looper angle θ of the looper mechanism 104 is detected by a looper angle detector 105, and a calculation device 106 calculates a looper torque amount corresponding to the looper angle θ such that the target tension value is always maintained. The current target value of the looper drive motor necessary for generating the looper torque amount obtained in this way is applied from the calculation device 106 to the current control device 107 of the looper drive motor, and this current control device 10
7 drives a looper drive motor 108. On the other hand, the detection signal of the looper angle detector 105 is also applied to the arithmetic unit 109.
Now, in order to return the looper angle θ, which has gone up and down due to inter-stand tension control, to the target value, the rolling roll 102 is
Roll drive electric motor 120 that drives a, 102b
A speed target value is calculated for. This speed target value is sent from the calculation device 109 to the speed control device 11.
0, and the roll drive motor 120 is driven by the speed control device 110. As can be seen from FIG. 3, the conventional looper control device performs inter-stand tension control and looper 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 tension control by the looper drive motor 108 begins; Since the looper angle control is performed by the roll drive motor 120 in this manner, this looper angle control may have an adverse effect on the inter-stand tension control, causing large fluctuations or even instability. There were flaws. Furthermore, if the looper angle is controlled to suppress this tension fluctuation, the response of the control must be lowered, and there is a drawback that it is not possible to follow disturbances that change quickly over time. As a conventional technique for solving this problem, there is a looper control device shown in FIG. 4, for example. In this conventional technology, the looper control system is regarded as a multivariable control system with two inputs and two outputs, and by linearizing the nonlinear looper dynamic characteristic model near a certain steady rolling state, the integral gain of the looper control system and the proportional Gains are determined, and these gains are used to determine the main engine speed target value correction amount and the looper speed target value correction amount. FIG. 4 is a control block diagram showing the configuration of a conventional looper control device that controls the tension t _f and the looper angle θ to their respective target values t _f ^R and θ ^R. Note that FIG. 4 mainly shows the flow of control signals. In FIG. 4, a speed control device for a looper drive motor (hereinafter referred to as a "looper speed control device" (looper ASR)) 1A is a looper drive motor 2.
, _and drives the looper mechanical system 3.
On the other hand, the main machine speed control device (main machine ASR) 4 controls the speed of the main machine electric motor 5 that drives the rolling rolls to a predetermined value. The inter-stand tension generating mechanism 6 is a block representing a transfer function from the speed of the main motor 5 to the tension t _f , and is determined by the mechanical specifications of the rolling mill, the dimensions of the rolled material, etc. F _T in block 7 is a coefficient for converting tension t _f into looper motor load current, and is determined by the dimensions of the rolled material, the looper angle, etc. Further, F〓 in block 8 is a coefficient for converting the change in the looper angle into the main motor motor speed, and is determined by the rolling mill mechanical specifications, the looper angle, etc. Blocks 7 and 8 represent mutual interference between the looper angle θ and the tension t _f . The blocks 1A to 8 above represent the equipment conditions and the rolling process, and the structure and operation of the looper control device according to the prior art will be explained below. Blocks 9, 10, 11 and 12 represent the gains of the main controller, 13 and 14 are integrators, 15 and 16 are adders, and 17 to 22 are blocks representing feedback gains of state variables. The looper motor speed reference ΔN _L ^R given to the looper speed control device 1A is obtained by adding the output values of each means shown in (a) to (d) below. (a) Integral gain K ₂₁ (block 10) and integrator 1 regarding the deviation between the detected tension value t _f and the target tension value t _f ^R
(b) Means for performing an integral operation according to 4 and a proportional operation according to a proportional gain F ₄ (block 20) regarding the deviation between the detected tension value t _f and the target tension value t _f ^R ; (b) the detected looper angle value θ and the target value of the looper angle; Integral gain K ₂₂ for deviation from θ ^R (block 12)
(c) means for performing an integral operation by an integrator 14, a means for performing a proportional operation by a proportional gain F ₅ (block 21) regarding the deviation between the detected looper angle value θ and the target looper angle value θ ^R , and (c) a detected looper motor speed value N There are three types of means for performing proportional operation with respect to _L using a proportional gain F ₆ (block 22). On the other hand, the speed reference value input to the main engine speed control device 4 is synthesized by adding the speed setting value N ^R and the main engine speed correction amount ΔN ^R. Here, the main engine speed correction amount ΔN ^R is obtained by adding the output values of each means shown in the following (d) to (f). (d) Integral gain K ₁₁ (block 9) and integrator 13 regarding the deviation between the detected tension value t _f and the target tension value t _f ^R
Integral operation by , tension detection value t _f and tension target value
Proportional gain _F ¹ (block ₁
(e) Integral gain K ₁₂ for the deviation between the looper angle detection value θ and the looper angle target value θ ^R (block 11);
means for performing an integral operation by an integrator 13, and a proportional operation by a proportional gain F ₂ (block 18) for the deviation between the detected looper angle value θ and the target looper angle value θ ^R ; (f) a detected looper motor speed value N _L; There are three types of means for performing proportional operation using proportional gain F ₃ (block 19) for . Next, the operation of the conventional looper control device configured as described above will be explained. The looper 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 equation of state as shown in equations (1) and (2). X〓=A.
X, U, and Y are vectors expressed by equations (3), (4), and (5), respectively, and W is a three-dimensional disturbance vector. Also, A, B, and C are 3×3, 3×2, and 2×, respectively.
It is a constant matrix of 3. X = [Δt _f , Δ〓, N _L ] ^T (state vector) …(3) U = [ΔN ^R , ΔN ^R _L ] ^T (operation vector) …(4) Y = [Δt _f , Δθ] ^T (output vector)...(5) Here, the symbol T represents the transposition of the vector. 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 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, the operation vector U may be configured as shown in equation (6). U=-R ^-1 B ^T P ₂₁ ∫ ^t ₀ (Y-Y _R )dt-R ^-1 B ^T P ₂₂ (X
-X ₀ ) + U ₀ ...(6) Here, R is a 2x2 diagonal positive definite matrix, Y _R is the target value vector of the output vector Y, X ₀ is the initial value vector of the state vector X, and U ₀ is the operation This is the initial value vector of vector U. In addition, P ₂₁ and P ₂₂ are the quasi-definite solution 5×5 of the Riccati type equation shown by the following formula PA〓+A〓 ^T P−PB〓R ^-1 B〓 ^T P+Q=O ……(7)
It is a submatrix of matrix P, and the relationship between P and P ₂₁ and P ₂₂ is

[Table] 〓〓〓 〓〓〓
_P11

Claims (1)

[Claims] 1. A first control system that controls the speed of the main electric motor that drives the rolls of the rolling stand so that the material to be rolled has a predetermined tension value, and a first control system that is provided between the rolling stands that are arranged in tandem. and a second control system that controls a looper drive motor that drives the looper so that the looper is at a predetermined angle, and the first control system and the second control system each have a proportional operation element and an integral operation element. In a looper control device for a continuous rolling mill, the gain of the integral action element and the proportional action element at two or more rolling speeds are calculated and stored before the material to be rolled is rolled in the continuous rolling mill. and calculating means for setting gains linearly interpolated based on the stored gain using the speed reference or actual speed value of the main machine motor during rolling to the proportional action element and the integral action element. A looper control device for a continuous rolling mill.