JPH0472608B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a continuous rolling mill, and particularly to a continuous rolling mill with improved tension control of a rolled material.

[Technical background of the invention and its problems]

In a continuous rolling mill that continuously rolls steel plates, etc., it is necessary to precisely control the tension of the rolled material to a target value in order to improve the quality accuracy of product thickness and width and to stabilize operability. be done. There are various methods for controlling the tension of the rolled material, but generally a method is used in which the tension of the rolled material is controlled to a predetermined value by adjusting the circumferential speed of the rolling rolls.

FIG. 6 shows a tension control device for rolled material in a conventional continuous rolling mill. Rolled material 3 rolled by upstream roll 1 and downstream roll 2
The tension is detected by a tension detector 4 disposed between the upstream roll 1 and the downstream roll 2. In the tension control calculator 6, the detected value of the tension detector 4 and the tension reference setting value of the tension reference setting device 5 are compared, and the deviation is proportionally integrated and outputted to the speed control device 7 as a speed reference compensation amount. Ru. This speed control device 7 controls the circumferential speed of the upstream rolling roll 1 connected to the main motor 8, and by controlling the circumferential speed of the upstream rolling roll 1, the tension of the rolled material 3 becomes equal to the reference setting value. controlled. At this time, since the amount of change in the tension of the rolled material 3 with respect to the amount of change in the circumferential speed of the upstream rolling roll 1 depends on the type of the rolled material 3 and the rolling conditions, conventional methods such as plate thickness and plate width Data of the material to be rolled 3 such as deformation resistance and rolling conditions such as circumferential speed and rolling reduction of the rolling rolls are input to the tension control calculator 6.
The gain and compensation time constant of the tension control calculator 7 were adjusted, thereby improving control performance.

However, in the above-mentioned rolled material tension control device, tension disturbance occurs due to the rolling rolls being moved at a fast cycle by changing the gain of the plate thickness control device, which closely interferes with the tension of the rolled material. However, when such a tension disturbance occurs, there is a problem that the tension control of the rolled material becomes oscillatory.

[Purpose of the invention]

The present invention was made in consideration of the above circumstances, and
It is an object of the present invention to provide a continuous rolling mill equipped with a rolled material control device that has stable tension control performance with respect to gain changes of the thickness control device for the rolled material.

[Summary of the invention]

In order to achieve the above object, a continuous rolling mill according to the present invention includes a rolling roll that rolls a material to be rolled such as metal, a main motor that drives the rolling roll, a speed control device that controls the speed of the main motor.
a tension detector that detects the tension of the rolled material; and a tension control device that outputs a speed reference compensation amount to the speed control device based on a deviation between a detected value of the tension detector and a predetermined tension reference value. and a plate thickness control device that controls the thickness of the rolled material, and a gain adjuster that compensates the gain of the tension control device according to the gain of the plate thickness control device.

This allows the gain adjuster to variably set the gain of the tension control device in response to a change in the gain of the plate thickness control device, thereby achieving stable tension control.

[Embodiments of the invention]

FIG. 1 shows a continuous rolling mill according to an embodiment of the present invention. Upstream rolling roll 1 that rolls the material to be rolled 3
A tension detector 4 is installed between the rolling roll 2 and the downstream rolling roll 2 . The tension detector 4 and tension reference setting device 5 are connected to a tension control calculator 6.
An automatic plate thickness control device 12 using a hydraulic rolling device is installed coupled to the upstream rolling roll 1. The tension control calculator 6 and the automatic plate thickness control device 12 are connected to a gain adjuster 11.
1 is connected to a speed control device 7, and this speed control device 7 is connected to the upstream rolling roll 1 via a main motor 8.
It is connected to the. Further, the speed control device 9 is connected to the downstream rolling roll 2 via a main motor 10.

Next, the operation will be explained. The tension detector 4 detects the tension of the rolled material 3 that is rolled by the adjacent upstream roll roll 1 and downstream roll roll 2 . In the tension control calculator 6, the detected value of the tension detector 4 and the tension reference setting value of the tension reference setting device 5 are compared, and the deviation is proportionally integrated to determine the speed reference compensation amount. In the gain adjuster 11, the speed reference compensation amount by the tension control calculator 6 is serially compensated by the scale factor C of the mill constant control system taken in by the automatic plate thickness control device 12. The speed reference compensation amount compensated by the scale factor C by the automatic plate thickness control device 12 is output to the speed control device 7, and the speed control device 7 By controlling the circumferential speed of the upstream rolling roll 1, the tension of the rolled material 3 is controlled to be equal to the tension reference setting value. Here, the mill constant control is a minor loop of automatic plate thickness control, and is to control the mechanical mill constant M [TON/mm] to a predetermined equivalent mill constant Me [TON/mm].
The relationship between the mechanical mill constant M and the equivalent mill constant Me is as follows: Δh=ΔP/M−CΔP/M=ΔP/M _e (1) M _e =M/1−C (2). However, Δh [mm] is the exit side plate thickness deviation from the lock-on value, ΔP [TON] is the rolling load variation, and C
is a scale factor, and C<1...(3). From formula (1), the larger the equivalent Mill constant M _e is,
It is shown that the accuracy of plate thickness control becomes higher.

Next, the gain adjuster 11 shown in FIG. 1 will be explained in detail. FIG. 2 shows the tension control system and plate thickness control system of the continuous rolling mill according to this embodiment.

First, in the tension control system, the tension feedback coefficient _K10 of the feedback 20 of the tension of the rolled material to the speed of the rolled material is a value that changes depending on the material to be rolled and the rolling schedule, and the smaller this value is, the greater the tension fluctuation is. . This will be explained below.

The time rate of change dt/dτ of the tension t of the rolled material 3 between the upstream roll 1 and the downstream roll 2 is expressed by the following equation based on Hook's law.

dt/dτ=E/L(V-v) [Kg/mm ² /sec]...(
4) However, E: Young's modulus of rolled material 3 [Kg/mm ² ] L: Distance between rolling rolls 1 and 2 [mm] V: Speed of rolled material at the entrance of rolling roll 2 [mm/sec] v: Rolling roll 1 The speed of the rolled material on the exit side is [mm/sec].

The following equation is obtained by Laplace transform of this equation (4).

s〓[t] _−t0 =E/L{〓[V]−〓[v]}……(5
) From this equation (5), the speed of the rolled material on the exit side of rolling roll 1 v
The minute change Δt in the tension of the rolled material 3 when is slightly changed by Δv is expressed by the following equation.

s〓[Δt]=-E/L〓[Δv]...(6) On the other hand, the rolling material speed v on the exit side of the rolling roll 1 is expressed by the following formula.

v=(1+f)V _R ...(7) where f: Advancement rate at rolling roll 1 [-] _VR : Roll circumferential speed of rolling roll 1 [mm/sec].

Therefore, the minute change Δv in the speed v of the rolled material on the outlet side of the rolling roll 1 is expressed by the following equation.

Δv=(1+f)ΔV _R +V _R Δf = (1+f)ΔV _R +V _R・(∂f/∂t)Δt=(1+f)ΔV _R +K ₁₀・Δt ……(8) K ₁₀ =V _R・(∂ f/∂t) ...(9) Here, (∂f/∂t): is the influence coefficient of the tension t on the advance rate f.

The following equation is obtained from equations (6) and (8) above.

〓[Δt]=-E/L・S{〓[(1+f)ΔV _R ]+〓[ _K10・Δt]}...(10) When expressed in a block diagram, it becomes as shown in FIG. 7.

Hereinafter, the following equation can be obtained from FIG. 7 by omitting the Laplace operator 〓 [ ].

Δt/(1+f)ΔV _R =-E/Ls/1-(-E/Ls)・K
₁₀ = -1/K ₁₀ 1/1 + (L/EK ₁₀ ) s (11) According to the above equation (9), K ₁₀ changes depending on the material to be rolled and the rolling schedule. Also, from equation (11), Δt/
The gain of (1+f)ΔV _R is -1/K ₁₀ , and K ₁₀
The smaller the value, the greater the tension fluctuation Δt with respect to the manipulated variable ΔV _R for tension control.

Furthermore, if the delay time constant of the speed control device 7 is T _M , the tension feedback coefficient K ₁₀ is 1/T ₁ = −K ₁₀ /3T with respect to the settings of the control constants T ₁ and T ₂ of the tension control calculator 6. It is reflected by _M ……(12) T ₂ =T _M ……(13).

The basis for this will be explained below.

A conventional tension control system is shown in the block diagram of FIG. Here, T ₂ is set to T ₂ = T _M in order to cancel 1/(1+T _M s) and improve the response, and T ₁ is the following open-loop transfer function G(s) = 1 + T ₂ s/T ₁ s・1/1+T _M s・(1+f)・
-1/K ₁₀・1/1+(L/E・K10)s=
−(1+f)/T ₁ s・K ₁₀・{1+(L/E・K10)s}
...(14) If the angular cutoff frequency of the closed loop is ω _c [rad/sec], −(1+f)/ω _c T ₁ K ₁₀ =1 holds true.
When this equation is transformed by setting f≈0, it becomes 1/T ₁ =−ω _c K ₁₀ (15), and if ω _c =1/3T _M is set considering the stability of the closed loop, the following equation holds true.

1/T ₁ =-K ₁₀ /3T _M (16) Therefore, the tension control calculator 6 includes information on the tension feedback coefficient K ₁₀ .

Taking into consideration the series compensation element K _t of the gain adjuster 11, the total gain of the tension control system is K _t /T ₁ =−K _t K ₁₀ /3T _M (17). In the plate thickness control system, the plate thickness control device 12
is the load cell 21 with load cell time constant T _L [s],
Mill constant control 22 and hydraulic pressure reduction device time constant T _v corresponding to mill constant control amount −C/M shown in equation (1)
It has a hydraulic lowering device 23 of [s]. From FIG. 2, the amount of change in speed of the rolled material Δv [mm/sec] with respect to the change in tension Δt [Kg/mm ² ] is expressed by the following equation.

The above formula can be simplified as follows.

Δv/Δt=K ₁₀ +−C/M+m−mC−∂P/∂t・∂f/∂
h・V _R ...(19) However, m [TON/mm] is the plastic deformation rate, P
[TON] is the rolling load, t [Kg/mm ² ] is the tension, b is the backward movement rate, h [mm] is the plate thickness, and v [mm/s] is the speed of the rolled material.

In this equation (19), when the tension t is increased, the rolling load P becomes smaller, so ∂P/∂t<0, and when the plate thickness h is increased, the advance rate f becomes smaller, so ∂f/∂h<0 Therefore, the plate thickness control system is based on the tension feedback coefficient.
It has the effect of reducing _K10 .

As shown in FIG. 2, the plate thickness control device 12 stands in parallel with the field back 20 of the tension of the rolled material to the speed of the rolled material, so that the thickness control system is the tension feedback coefficient
There is an effect of reducing K ₁₀ , and the degree of this decrease is greater as the scale factor C of the Mill constant control 22 is larger.

That is, the above equation (18) can be transformed as shown in the following equation.

ΔV/Δt=K ₁₀ −C/M+m(1−C)・∂P/∂t・∂f
/∂h・V _R ...(20) K ₁₀ =V _R ∂f/∂t =V _R ∂f/∂h・∂h/∂P・∂p/∂t =V _R /M ∂f/∂t h・∂P/∂t =K ₁₀・(1-C)(M+m)/M+m(1-C)...
...(21) This relationship is expressed as shown in Figure 3.

Thus, the plate thickness control system has the effect of reducing the tension feedback coefficient _K10 , and the degree of this decrease increases as the scale factor C of the mill constant control 22 increases.

FIG. 4 shows a Bode diagram of the closed loop of the tension control system including the plate thickness control system of the continuous rolling mill according to this embodiment. In Fig. 4, if the scale factor C of the plate thickness control system is changed to C=0.9 while maintaining the tension control gain adjusted with C=0, the tension control system changes to the attenuation rate (ζ ) can be seen to form a small oscillating system. FIG. 3 shows the relationship between the scale factor C of the plate thickness control system of the continuous rolling mill according to this embodiment and the series compensation element K _t of the gain adjuster 11. The oscillatory properties of the tension control due to changes in the scale factor C of the plate thickness control system described above are as shown in FIG. This problem can be solved by variably setting the series compensation element _Kt of the gain adjuster 11 according to the scale factor C.

This will be explained in more detail.

K _x =C/M+m(1-C)・∂P/∂t・∂f/∂h・V _R …
…(22).

The tension feedback coefficient _K10 can be transformed as follows.

K ₁₀ = V _R・∂f/∂t = V _R・∂f/∂h・∂h/∂P・∂P/∂t = V _R /M・∂f/∂h・∂P/∂t... ...(23) ∵Δh=ΔP/M ...(24) Therefore, K _x = MC/M+m(1-C)・K ₁₀ ...(25)

The round transfer function H(s) of the tension control system including the plate thickness control device 12 and the gain adjuster 11 is 1+f≒1
is expressed by the following formula.

Here, the angular cutoff frequency of the closed loop ω _c [rad/sec]
Then, −K _t /ω _c T ₁ (K ₁₀ −K _x )=1 (27) holds true.

From this equation (27), K _t = −ω _c T ₁ (K ₁₀ −K _x ) ...(28), and ω _c = 1/3T _M T ₁ = −3T _M /K ₁₀ ...(29) Substituting, K _t = K ₁₀ −K _x /K ₁₀ = 1-K _x /K ₁₀ = 1-1/K ₁₀・K ₁₀・MC/M+m(1-C) =(M+m)(1-C) /M+m(1-C)……(30
) becomes. This function is shown in FIG.

Therefore, the tension control device includes a gain adjuster 11.
and for the value of scale factor C, K _t
By variably setting the value calculated by the above formula (the value shown in FIG. 3), the vibration of the plate thickness control system can be eliminated.

A continuous rolling mill according to another embodiment of the invention is shown in FIG. A looper 13 and a tension detector 4 are installed between an upstream roll 1 and a downstream roll 2 that roll a material 3 to be rolled. The looper 13 includes a looper drive motor 14 and a looper position detector 1
9 is connected. The looper position detector 19 and the looper position setter 18 are connected to the looper position control device 1.
7 is connected. This looper position control device 1
7 is output to a speed control device 16, which controls the looper drive motor 1.
It is connected to a current control device 15 that controls the current of 4. The tension detector 4 and the tension reference setting device 5 are connected to a tension control calculator 6. An automatic plate thickness control device 12 using a hydraulic rolling down device is installed on the upstream rolling roll 1. The gain adjuster 11 is
It is connected to the tension device 6 and the automatic plate thickness control device 12, and compensates the gain of the tension control device 6 according to the gain of the automatic plate thickness control device 12. The compensation control signal from the gain adjuster 11 is output to the speed control device 7, and the speed control device 7 controls the speed of the main motor 8 that drives the upstream roll 1 using this compensation control signal.

The operation of the looper control system of the continuous rolling mill according to this embodiment will be explained. The position of the looper 13 is detected by a looper position detector 19. In the looper position control device 17, the detected value of the looper position detector 19 and the set value of the looper position setter 18 are compared,
Based on the deviation, the looper position control signal is controlled via the speed control device 16, current control device 15, and looper drive motor 14 so that the position of the looper 13 matches the set value. The operations of the tension control system and plate thickness control system of the continuous rolling mill according to this embodiment are similar to those of the previous embodiment, and the gain of the tension control system is adjusted according to the scale factor C of the plate thickness control system. The configuration and operation of regulator 11 are also similar to those in the previous embodiment.

[Effects of the Invention] As described above, according to the present invention, it is possible to eliminate the oscillation of the tension control of the rolled material due to the gain change of the plate thickness control device for the rolled material, realize stable tension control, and improve the rolling material. The dimensional accuracy of the board thickness and board width can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a continuous rolling mill according to an embodiment of the present invention, FIG. 2 is a block diagram showing a tension control system and plate thickness control system of a continuous rolling mill according to an embodiment of the present invention, and FIG. 3 is a block diagram showing a continuous rolling mill according to an embodiment of the present invention. is the scale factor C of the plate thickness control system of a continuous rolling mill according to an embodiment of the present invention.
Fig. 4 is a Bode diagram showing that the tension control system forms a vibration system by changing the _gain of the plate thickness control system, Fig. 5 6 is a block diagram showing a continuous rolling mill according to another embodiment of the present invention, FIG. 6 is a block diagram showing a conventional continuous rolling mill, and FIGS. 7 and 8 show detailed operations of an embodiment of the present invention. FIG. 2 is a block diagram for explanation. 1, 2... Rolling roll, 3... Rolled material, 4...
...Tension detector, 5...Tension reference setting device, 6...Tension control calculator, 7, 9...Speed control device, 8, 1
0...Main motor, 11...Gain adjuster, 12
...Automatic plate thickness control device, 13...Looper, 14...
...Looper drive motor, 15...Current control device, 1
6... Speed control device, 17... Looper position control device, 18... Looper position setting device, 19... Looper position detector, 20... Feedback of rolled material tension to rolled material speed, 21... ...Load cell,
22... Mill constant control, 23... Hydraulic lowering device.

Claims (1)

[Claims] 1. A rolling roll that rolls the rolled material, a main motor that drives the rolling roll, a speed control device that controls the speed of the main motor, a tension detector that detects the tension of the rolled material, and the tension a tension control device that outputs a speed reference compensation amount to the speed control device based on a deviation between a detected value of the detector and a predetermined tension reference value; and a plate thickness control device that controls the thickness of the rolled material. and a gain adjuster that compensates the gain of the tension control device according to the gain of the plate thickness control device.