JP2518746B2 - Hot 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 method of controlling tension in hot rolling by changing roll peripheral speed and looper motor torque.

[0002]

2. Description of the Related Art In a hot rolling control device, an automatic internal plate thickness deviation control system (AG
C) is adopted (The Iron and Steel Institute of Japan "Theory and Practice of Sheet Rolling" p.223 to p.256).

The automatic plate thickness deviation control system will be described in detail with reference to FIG.

In FIG. 8, M: rolling mill rigidity coefficient (KgW / mm) Q: rolling material plasticity coefficient (KgW / mm) Δu: reduction system mechanism operation command amount (mm) ΔS: reduction mechanism operation amount (mm) ΔP : Rolling load fluctuation amount (KgW) Δh: Outlet plate thickness deviation (mm) ΔH: Inlet plate thickness deviation (mm) ΔR _r : Reduction reference (mm) α: Tuning factor (---) (0 ≦ α ≦
1) s: plus operator (1 / sec) G: integration constant (1 / sec) T ₁ : time constant (sec), where T ₁ << 1.0.

In this case, the transfer function G ₁ from the inlet side plate thickness deviation (ΔH) to the outlet side plate thickness deviation (Δh) is expressed by Formula 2 using W expressed by Formula 1.

[0006]

[Equation 1]

[0007]

[Equation 2]

Considering the characteristics in the steady state (s = 0.0), G ₁ is expressed by the equation 3.

[0009]

(Equation 3)

Therefore, in order to completely remove the entrance side plate thickness deviation (ΔH), the tuning factor needs to be α = 1.0.

Further, when the automatic plate thickness deviation control system is used, the tension of the rolled material, the thickness of the rolled material, the speed of the rolled material on the outgoing side and the incoming side of the rolling mill, and the roll of the stand upstream from the looper angle. A method of changing the peripheral speed has been adopted. For example, JP-A-59-110410 and JP-A-62-7241 are used.
No. 1 and Japanese Patent Application Laid-Open No. 61-249617, etc.
A DC mill motor with a crossover frequency of 25 rad / sec is used.

[0012]

However, the conventional method has the following problems, which will be described in detail with reference to FIG.

FIG. 9 is a view showing a conventional hot rolling control device. In FIG. 9, 1 is a rolled material, 2 is an i-1 rolling mill (hereinafter referred to as an upstream rolling mill), 3 is an i-th rolling mill (hereinafter referred to as a downstream rolling mill), and 4 is a looper. Roll, 5 is a looper arm, 6 is a motor for driving the looper,
7 is a CPU, 10 is an upstream mill motor system, and 11 is a downstream mill motor system, and the rolled material flows from the upstream rolling mill to the downstream rolling mill.

In FIG. 9, H _i : i-th rolling mill entrance side plate thickness (mm) V _i : i-th rolling mill entrance side speed (mm / sec) h _i : i-th rolling mill exit side plate thickness (mm) v _i : No. i rolling mill exit side speed (mm / sec) H _i-1 : i-1 No. rolling mill entrance side plate thickness (mm) Vi _-1 : i-1 No. rolling mill entrance side speed (mm / sec) h _{i-1: i-1} th thickness at delivery side of the rolling mill _{(mm) v i-1:} i-1 th delivery side of the rolling mill speed _{(mm / sec) ΔVR i-} 1: i-1 th mill peripheral velocity change Amount (mm / se
c).

In the steady state, the i-th stand and i +
Between the first stand, V _i-1 is expressed by the equation 4.

[0016]

(4) v _i-1 = V _i

In the i-th stand, the relationship of equation 5 is established.

[0018]

[Equation 5] H _i · V _i = h _i · v _i

Now, for example, when the deformation resistance of the rolled material fluctuates and the strip thickness on the delivery side of the rolling mill fluctuates as h _i → h _i + Δh _i , V _i fluctuates as shown in Eq. .

[0020]

(Equation 6)

Further, as shown in the equation (7), the speed balance is broken.

[0022]

(7) v _i ≠ V _{i + 1}

If left as it is, the rolled material may form a loop and may be folded into the rolling mill to break the rolled material. However, by changing the roll peripheral speed of the upstream stand on which the looper moves up and down, Regain the equilibrium of Equation 7 above.

As described above, the change in tension caused by the change in plate speed is suppressed by controlling the torque of the looper motor and the roll peripheral speed of the upstream or downstream stand. In other words, it is a redundant control system that tries to control one controlled variable by two manipulated variables.

As described above, the conventional control includes non-interference control and LQ.
There is control, and in non-interference control, the looper height is controlled by the looper motor torque, and the tension is controlled by the roll peripheral speed. In tension control, only the operation amount called roll peripheral speed was used. Therefore, the disturbance suppression in the non-interference control is as shown in FIG.

FIG. 6 shows how the steel plate tension changes when the entrance-side plate speed V _i changes due to changes in deformation resistance and the effects of AGC. The vertical axis of this figure is the steel plate tension (Kg
f), the horizontal axis represents time (seconds).

Reference numeral 1 in the figure corresponds to tension component 1 in the looper control block diagram shown in FIG.
Corresponds to the tension component 2, and the code T corresponds to the tension which is the sum thereof. It should be noted that the tension component 1 represents the influence of tension by operating the roll peripheral speed, and the tension component 2 represents the influence of tension by operating the looper angle.

Further, as shown in FIG. 6, in the non-interference control, the tension component 1 due to the operation of the roll peripheral speed is equal to the total tension fluctuation, that is, the tension component 2 depends on the tension effect due to the change of the looper angle. Since the suppression is not performed, when the advanced ratio fluctuates by about 10% due to the hydraulic pressure reduction of the AGC, the fluctuation of the plate speed is greatly affected, and the fluctuation of tension of about 700 Kgf is generated. The cycle corresponds to the response 120 rad under the hydraulic pressure.

FIG. 7 shows the case where the LQ control is performed. In this case, the tension components 1 and 2 which are the influences of the tension due to the two operation amounts cancel each other to some extent, and the total tension fluctuation is suppressed to a fluctuation of about 100 kgf.

However, since the tension component 2 is used too much,
Looper angle fluctuation [Tension component 2 x (L / EhB) K _LS ]
Results in large and unstable operations. Therefore, it is necessary to design the two operation amounts so that they cooperate quantitatively and in cooperation with each other.

That is, it is necessary to appropriately separate and coordinate the sharing of the two tension components on the frequency. In particular,
Large and slow movements are dealt with by the roll peripheral speed, that is, the tension component 1. If the looper is moved too much, stable operation will be hindered. It is considered necessary to respond.

The present invention provides a hot rolling control method which advantageously solves the above problems.

[0033]

DISCLOSURE OF THE INVENTION The present invention provides a tensiometer for measuring the tension of a rolled material, a looper angle meter for moving the rolled material up and down, and a rolled material tension and a looper angle detected by an angular velocity meter during rolling of a steel sheet. When calculating the rotation speed correction amount of the mill motor and the looper torque or the looper motor rotation speed correction amount from the looper angular velocity by the central processing unit, the tension control amount by changing the roll peripheral speed and the tension control amount by changing the looper angle are calculated. A hot rolling control method characterized in that a frequency weighting filter for dividing in an appropriate frequency range is used to determine a state feedback gain by H∞ control theory to change a roll peripheral speed and a looper motor torque.

[0034]

The present invention will be described in detail below together with its operation.

FIG. 1 shows an example of a hot rolling control device suitable for implementing the present invention and a hot rolling control method using the same.

In FIG. 1, 1 is rolled material, 2 is i-1
No. rolling mill (hereinafter referred to as upstream rolling mill), 3 i-th rolling mill (hereinafter referred to as downstream rolling mill), 4 looper rolls, 5 looper arms, 6 looper drive motor, 7 Is a CPU, 8 is an upstream mill motor system, and 9 is a downstream mill motor system, and the rolled material 1 flows from an upstream rolling mill to a downstream rolling mill.

In FIGS. 1 and 2, H _i : i-th rolling mill entry side plate thickness (mm) V _i : i-th rolling mill entry side speed (mm / sec) h _i : i-th rolling mill exit side plate thickness (mm ) V _i : No. i rolling mill exit side speed (mm / sec) H _i-1 : i-1 No. rolling mill entrance side plate thickness (mm) Vi _-1 : i-1 No. rolling mill entrance side speed (mm / sec) h _i-1 : i-1 rolling mill delivery side plate thickness (mm) v _i-1 : i-1 rolling mill delivery side speed (mm / sec) ΔVR _i-1 : i-1 rolling mill circumference Speed change amount (mm / se
c).

In FIG. 2, W ₁ , W ₂ , W ₃ : frequency weighting filters ‖ marks: changeover switch (soft switch), ON is LQ (ILQ) control mode, OF
F is a robust control mode. K _{I ·} : Integral gain K _{P ·} : State feedback gain K _{S ·} : Gain adjustment parameter

The CPU 7 and the upstream mill motor system 8 are equipped with an AC mill motor system having an intersection frequency of 40 rad / sec or more according to the present invention. In hot rolling, the tuning factor must be 0.85-1.0 in order to achieve a highly accurate strip thickness, and the deflection angle of the looper and the tension fluctuation of the steel sheet become large, but the operation is stabilized. Therefore, it is necessary to keep the deflection angle of the looper and the amount of tension fluctuation of the steel plate below a certain level.

FIG. 2 is a block diagram of a looper multivariable optimum control system for carrying out the present invention.

First, a tension target and an angle target are set from the outside and compared with the tension actual results (c) and the angular actual results (d), respectively, and the difference between them is input to the integrators 10 and 11. Then, the integration gains 12, 13, 1 are added to the outputs of the integrators 10, 11, respectively.
4,15 can be applied. The state feedback signal components (a) and (b) described below are added to this, and finally the adjustment gains 16 and 17 are applied to the mill peripheral speed and the command value to the looper.

The calculation of the state feedback signals (a) and (b) is a process state quantity. Steel plate tension (c), looper angle (d), looper angular velocity (e), state feedback gains 18, 19, 20 and 22, respectively.
Apply 23, 24.

[0043] is a further feature of the following present invention, the signal through the frequency weighting filter W ₁ 26 to the tension deviation signal (f), and angle deviation signal (G) in the frequency weighting filter W
₂ 27, and the signal passing through the frequency weighting filter W ₃ 28 for the steel plate tension (c) and looper angle (d) signals as new state variables, and the state feedback gain for each newly added state variable. 29, 30, 21,
And 31, 32, 25 are added to the conventional state feedback signal.

Frequency weighting filters W ₁ 26, W ₂ 27,
W ₃ 28 is the point of the present invention, and FIG. 4 described below, and FIG.
It will be explained in.

FIG. 2B is a block diagram of the process operation end 33 of the looper optimum control system for carrying out the present invention.

Reference numeral 100 represents the response of the rolling roll speed control system approximated by a secondary system. The output of the rolling roll speed control system 100 corresponds to the speed difference of the roll peripheral speed between the stands and the plate speed disturbance. The signal obtained by subtracting Vd and the feedback term (a) to the plate speed due to the change in tension is integrated by (b) 10
The value obtained by setting 1 is the amount of deflection (c) between the loops, multiplied by the Young's modulus, and divided by the length 104 between stands to obtain the tension component 1 (d).

From the looper torque, the tension component 1 (d)
Signal _{obtained by} multiplying the influence coefficient K _gT 105 from tension to torque, the signal _{obtained by multiplying the} looper angular velocity (f) by the damping constant 107 of the looper, and the looper angle signal (g)
Influence factor from looper angle to looper torque K _gS 1
The signal obtained by subtracting the signal multiplied by 08 is divided by the moment of inertia of the looper, and the integrated signal 106 is the looper angular velocity (f), and the integrated signal 109 is the looper angle signal (g).

The respective coefficients are as follows.

E: Young's modulus of steel plate, I: Moment of inertia of looper system, L: Distance between stands, f: Damping constant of looper, K _VT : Effect term of tension on plate speed, K
_gT : Influence term from tension to torque (torque applied from steel plate to looper), K _LS : Influence term from looper angle to _strip elongation, K _gS : Influence term from looper angle to looper load torque,

K _VT : i to (i + 1) The change in tension between stands corresponds to the change in the front tension of the i stand and the change in the rear tension of the i + 1 stand.
The reverse rate b _{i + 1 of the i} , i + 1 stand changes. Therefore, even if the i, i + 1 stand roll peripheral speed is constant, the plate speed on the i stand stand-out side and the i + 1 stand stand-in side changes.

The advanced _{rate: f = (V O -V r} ) / V r reverse _{rate: b = (V r -V i} ) / V r steel plate at the exit side entry side of the roll roll circumferential speed since the slip and the steel plate The speeds do not match. When Vo is the outgoing plate speed, V _{i is the} incoming plate speed, V _{r is the} roll peripheral speed, and Vo> V _r > V _i , K _VT is as shown in Eq.

[0052]

K _VT = (df _i / dT) · V _{r, i} + (db _{i + 1} / dT) · V _{r, i + 1}

K _gT : Torque G _t (kg · m) exerted on the looper by the steel plate tension T (kg) is expressed by the following equation 9.

[0054]

G _t = R ₁ · T · (sin (θ + β) -sin
(Θ-α)) (kg · m), so K _gT is several 10
, And K _gS becomes as in _Eq .

[0055]

[ _Formula 10] K _gT (θ) = R ₁ · (sin (θ + β) −sin (θ−α)) (kg · m)

[0056]

[Expression 11] K _LS : Strip elongation 1 = 1 ₁ +1 ₂ −L = (L ₁ +
R ₁ · cos θ) / cos α + (L-L ₁ -R ₁ · co
sθ) / cos β-L

Here, α = tan ⁻¹ {(R ₁ · sin θ + R ₂ −H ₁ ) / (L ₁ + R ₁ · cos θ)}, β = tan ⁻¹ {(R ₁ · sin θ + R ₂ −H ₁ ) /
(L−L ₁ −R ₁ · cos θ)}.

[0058]

(12) Therefore, K _LS = dl / dθ

K _gS : By changing the looper angle,
The changing load torque is the torque due to the weight of the steel plate, the torque due to the weight of the looper, the torque due to the bending of the steel plate, such as the restoring force of the elastic body.

Torque due to steel plate weight G _M = W _L · co
sθ · R ₁ , W _L : Torque due to the weight of the looper weight of the steel sheet existing between the stands G _S = W _S · cos θ · R ₁ /
2, W _S: looper weight, looper bent by the torque G _E
= _{K (Lsin} θ-H ₁ ) cos θ Therefore, K _gS becomes as shown in _Eq .

[0061]

[ _Formula 13] K _gS = d (G _M + G _S + G _E ) / dθ

L, R ₁ , R ₂ , H ₁ , L ₁ , E,
I and θ are as follows. L: interstand distance 5.486m R _1: looper arm length 0.612m R _2: looper roll radius 0.092 M H _1: looper shaft-pass line distance 0.184m L _1: Stand-looper shaft 2.345m E: Young's modulus of steel plate 1.8 × 10 ¹⁰ kg / m ² I: Total moment of inertia of looper 0.74 kg · m · s ² θ: Looper angle

FIG. 4 is an explanation of the frequency weighting filters W ₁ 111, W ₂ 112, W ₃ 113 which is the point of the present invention, and corresponds to 26, 27 and 28 in FIG.

W ₁ 111 indicates a tension control sharing range by the tension component 1, and is increased in the low frequency range so that the low frequency range can be mainly shared. W ₂ 112 is a frequency weighting filter showing the tension components 1 and 2, that is, how much the total tension control is performed up to the frequency region, and increases the gain up to the response range to be controlled. W ₃ 113 is a filter showing a frequency range not controlled by the tension component 2.

That is, the tension component 2 corresponds to the looper angle signal (g), and if it fluctuates too much, the operation becomes unstable. Therefore, the movement amount should be limited as much as possible. Therefore, the tension control sharing by the looper should work finely at high frequency, and W ₃ represents the frequency range where the looper is not moved.

The input to W ₁ is the difference between the tension component 1 and the target tension, the input to W ₂ is the tension deviation itself, and the input to W ₃ is the tension component 2. These inputs are W ₁ , W
_2, W ₃ so as not to exceed the frequency weights set in, using the known H∞ design theory, the state feedback gain in FIG. 2 (18,19,20,21,22,23,
24, 25, 29, 30, 31, 32) are determined.

[0067]

EXAMPLES L: interstand distance 5.486m R _1: looper arm length 0.612m R _2: looper roll radius 0.092 M H _1: between looper shaft-pass line length 0.184m L _1: Stand-looper Shaft 2.345 m E: Young's modulus of steel plate 1.8 × 10 ¹⁰ kg / m ² I: Total moment of inertia of looper 0.74 kg · m · s ² θ: In case of looper angle, plate velocity disturbance Vd (hydraulic pressure in FIG. 3) Reduction: 120
FIG. 5 shows the tension component 1, the tension component 2, and the total tension when the tension fluctuation for the case where the advanced rate changes by 10% on the sine wave by rad) is suppressed by the control of the present invention.

[0068]

As described above, as shown in FIG.
Compared to the non-interference control and the LQ control shown in FIG.
It can be seen from Fig. 5 that the tension fluctuation amplitude is greatly suppressed (about 15 kgf). Further, it can be seen that the amplitude of the tension component 2 is smaller than that of the LQ control, and the fluctuation of the looper angle is also small. This is because the role of the two tension components in the frequency range can be sufficiently separated by the frequency weighting filter, and thus the cooperation is well achieved. For example, the looper angle variation as set by W ₃ 113 in FIG. Is also kept small.

[Brief description of drawings]

FIG. 1 is a drawing showing an example of a hot rolling control device suitable for carrying out the present invention.

FIG. 2 is a block diagram showing a looper multivariable optimum control system for carrying out the present invention.

3 is a block diagram of a process operating end 33 of a looper optimum control system for carrying out the present invention, and is a drawing obtained by equivalently converting FIG.

FIG. 4 is a frequency weighting filter W ₁ 11 embodying the present invention.
_{1, W 2 112, W 3} 113 is a block diagram for explaining.

FIG. 5 is a waveform diagram showing the suppression characteristic against disturbance when controlled by the method of the present invention.

FIG. 6 is a waveform diagram showing a state of disturbance control in non-interference control.

FIG. 7 is a waveform diagram showing a state of disturbance control in LQ control.

FIG. 8 is a block diagram showing an automatic plate thickness deviation control system in the hot rolling control device.

FIG. 9 is a diagram showing an example of a conventional hot rolling control device.

[Explanation of symbols]

 1 rolled material 2 upstream rolling mill 3 downstream rolling mill 4 looper roll 5 looper arm 6 looper drive motor 7 CPU 8 upstream mill motor system 9 downstream mill motor system

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Yoneyama 1-1-1 Emitsu, Hachimanto-ku, Kitakyushu City Nippon Steel Corp., Facility Engineering Headquarters (72) Inventor Koichi Nishiyama Emitsu, Hachimanto-ku, Kitakyushu 1-1-1 Nippon Steel Corp., Facility Engineering Division (56) References Japanese Patent Laid-Open No. 59-110410 (JP, A)

Claims (1)

(57) [Claims] 1. Central processing based on a tension meter for measuring the tension of the rolled material, an angle meter of a looper for moving the rolled material up and down, and an angle meter of the rolled material, the looper angle and the looper angular velocity detected at the time of rolling the steel sheet. When calculating the mill motor rotation speed correction amount and looper torque or looper motor rotation speed correction amount with the device, in order to divide the tension control amount by changing the roll peripheral speed and the tension control amount by changing the looper angle into appropriate frequency ranges Hot rolling control method, characterized in that the roll feedback speed and the looper motor torque are changed by determining the state feedback gain by the H ∞ control theory by using the frequency weighting filter of 1 above.