JPS58154406A - Control system of loop of multi-stages rolling mill - Google Patents

Abstract

PURPOSE:To suppress the fluctuations in loops by inexpensive methods by determining the deviation between the speeds of both materials with a state observing device including the equivalent models of control systems from the output signals of speed detectors for motors and loop detectors and setting the speed command value variably so as to eliminate the deviation. CONSTITUTION:A loop controller 8 which superposes the deviation of loop control on the speed command value of a speed control device 5 for motors of the stand 1 of stands 1, 2 are provided. Further, a state observing device 12 which simulates the difference between the material speed on the roll outlet side of the stand 1 and the speed on the roll inlet side of the stand 2 from the loop detection signal and the speed detection signal for motors of the stand 1 on the basis of the motor speed of the stand 1 is provided. The speed command value is set variable in accordance with the output signal of the device 12, whereby the fluctuations in the loop are suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control method for controlling the loop of rolled material between the stands in a multi-high rolling mill consisting of a plurality of stands each driven by an individual electric motor.

When rolling is performed while forming a loop in the rolled material between two rolling stands adjacent to each other, it is required to maintain the loop size at a desired value. For this reason, a loop detector is provided, the output signal of this loop detector is compared with the loop setting signal, and the rotation speed command value of one of the stands is corrected according to the loop control deviation obtained as a result. ing. The control parameters of the lube controller, which constitutes the loop control system, are controlled by disturbances caused by dimensional fluctuations or temperature changes in the rolled material, and by the motor speed control system of both applicable stands. The IAI should be adjusted optimally so that loop fluctuations caused by presettling differences in the given speed command values are sufficiently suppressed.However, in order to ensure control stability, the tension feedback control system There is a limit to increasing the response speed of the loop control system. Therefore, the loop control system absorbs disturbances with a period slower than the response speed limit and forms a stable loop, but It is not possible to absorb this disturbance and loop fluctuations occur. In particular, the loop fluctuations caused by errors in speed preset/soto values are large, and in some cases, dimensional fluctuations due to material tension or misrolls due to excessive loops occur. There was a problem.

An object of the present invention is to provide a loop control method that eliminates the above-mentioned drawbacks and suppresses loop fluctuations using an inexpensive method.

The key point of the present invention to achieve this objective is to use a motor speed detector and a loop detection system, which are also provided in conventional devices, without directly detecting the material speed at the outlet side of the front stand and the material speed at the inlet side of the rear stand. From the output signal of the
The deviation between the above-mentioned art material stabbing speeds is indirectly determined through a state observation device that includes an equivalent model to be controlled, and the speed command value is variably set to cancel out this deviation. Absorbs disturbances and changes the loop
-This is because it is possible to suppress the movement.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The figure shows two stands 1 adjacent to each other of a multi-high rolling mill.
2 is shown. The rolled material 2 is formed into a loop between the two stands. Each stand has an individual '1
The electric motor of the rear stage stand 2 and its control system are not shown here, although they are driven by a motor. The electric motor 41 driving the front stand l is shown as a direct current motor fed via a thyristor converter 42. The speed control system of this electric motor 41 has an iris ristor converter 42. speed 1
lilJ control device f5. It is composed of a speed setting device 6 and a speed detection generator 7. The speed control device 5 includes, as usual, a speed regulator that constitutes a speed control loop.
U) includes a current regulator constituting a minor loop for current control inside its speed control wholesale loop. Furthermore, a loop control 1liI system is provided outside this speed control loop. This loop control system is a loop setter 9
The loop regulator 8 operates according to the deviation between the output signal of the loop detector and the output signal of the loop detector. As loop regulator 8, a P or PI operating regulator is used.

Furthermore, a state observation device (observer) 12 is provided, to which the motor speed n of the front stage l detected by the speed detector 7 and the loop 1it1 detected by the loop detector 10 are manually input. . A difference △z is formed between the output signal of the state observer and the output signal nt of the speed setting device 6, and this difference is used together with the output signal Δn of the loop regulator 8 on the setting input side of the speed control device [5 to determine the speed setting. It is superimposed with vessel n:. 2. The two illustrated switch elements 115- are interlocked with each other and are turned on during loop control.

In a state where a loop of the rolled material 3 is not formed between both stands, both switches 11 are in the OFF state, and therefore, the manual power on the setting side of the speed control device 5 is controlled by the speed setting device 6.
The preset value range is based on the rotational speed n of the electric motor 41.
is controlled by this preset Sengo. Similarly, the rotational speed of an electric motor (not shown) on the rear stage stand 2 side is also controlled to a preset value that takes into account the desired loop speed.

When the tip of the rolled material 3 is caught in the rear stage stand 2 and a loop is formed between the stands, both switches 11 are turned on and loop control is performed. During loop control, the signal d on the setting input side of the speed control device 5 is ♂=n:+△n+△n =n:+△n−1−(n−nλ) Second order+△n...・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・(1) That is, the output signal of the state observation device 12 becomes the speed command value, and the correction 1Δn of the loop regulator 8 is superimposed on this. Therefore, the embodiment shown in Fig. 6 can also be modified to a circuit system including a switching circuit for switching ♂ from n to △n.

By the way, as can be seen from the above-mentioned equation (1), it is important to understand what quantity the output signal n of the state observation device 12 represents in order to understand the effects of the present invention. Therefore, a specific internal configuration example of the state observation device 12 and its operation will be explained.

The state observation device 12 includes an integral element 121 as an equivalent model of the controlled object, and an integral element 122 for holding the aforementioned output signal n. Model 121 is the integration time rPL
, the output signal n of the speed detector 7 and the integral element 122
The difference between the output signal n and the output signal n is integrated. The deviation between the output signal t of the loop detector 10 and the output signal of the model 121 is input to the Jt* component 122 via an amplifier 123 having a gain g. Therefore, the integral element 122 has a deviation of 1−
The output signal n is changed until 1 becomes zero. The amplifier 124 has a gain gl:.

The deviation 1-1 is fed back to the input of the model 121, and thereby the self-excited vibration of the two integral elements 121 and 124 connected in a loop is suppressed and stabilized. Helpful. Gain gr, Ih
By selecting an appropriate value for , the response of the state observer can be optimized.

By the way, the loop between the stands is the front stand l.
For the roll source material speed v1 of and the roll entry side material speed ■ of the rear stage stand 2, L-■: (v, -v2) dt
(2) have a relationship of Here, the reference material speed is V. bird,
, the reference loop amount. Then, after unitizing V,,V,,L, and substituting the above equation (2) with these multiple positions, when Laplace transform is performed, t = −(V,
-v2)・・・・・・・・・・・・・・・・・・
・・・・・・・・・ (3)+11. l, I Kinaru. However, TL"'1-Lo/'Vo (=constant), and 11λ or S is the Laplace operator. These V, and v
2 and the electric and motor speeds n1 and n2 of each stand 1.2, as is well known, v has a1・(1+
f)・n,・・・・・・・・・・・・・・・・・・
・・・・・・・・・(41v2= a2・(1−ψ)・n
2・・・・・・・・・・・・・・・・・・・・・・・・
・(5) There is a relationship. However, al + "2 is a constant depending on the gear ratio and roll diameter in the tilt stands 1 and 2, f is the forward rate, and ψ is the reverse rate.

By the way, according to the state observation device 12, the output signal t of the model 121 is controlled to match the output signal t of the loop detector 10, so it is a simulated value of the loop amount, and the output signal t of the model 121 is The operation can be expressed by the Laplace arithmetic equation. Considering that the integral element 122 in the state observer 12 controls 1=1 and selects TL#TL, (3) From +61, v, -v
, = n - n. That is, the output signal n of the state observer 12 is n
= n −(v, −vt)・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・(It can be expressed as 71. The previous two equations (4) are added to this equation.

9- Applying (5), 'E= 111a, 11 (1+f)-nt a2
(1−ψ) ・n21, and as you can see from this formula,
The output signal of the state monitor 12Q is based on the motor speed detection (HIn) of one stand and includes all loop fluctuation factors.
Since the actual speed value n detected by the speed detector 10 is controlled so that n = n using the speed command value as the speed command value, considering equation (7), the control becomes v, -v, 20. It will be done. That is, V+-v
If t''=0, the loop l1llt changes, but according to the present invention, since the speed command value n does not directly include a component that cancels (v, -vρ), the loop a14 node 8
The speed correction amount n l (the speed is changed in response to the loop fluctuation suppression without waiting for a slower response).

Therefore, as can be seen from the above equation (1), the loop regulator 8 cancels the steady loop control deviation caused by the simulation error of the condition observer 12, and prevents sudden changes by 10- Compensation for this disturbance is performed by the above-mentioned foot power control by the condition observer 12.

As described above, according to the present invention, loop fluctuations caused by material dimensional changes, material temperature changes, roll gap changes, speed preset value errors between stands, impact drops when biting the material, etc. can be suppressed in a responsive manner. Since it can be suppressed, it is possible to keep loops between stands stable. This makes it possible to suppress dimensional variations in the rolled material and prevent misrolls from occurring. Furthermore, being able to maintain a stable loop means that the loop forming space can be reduced on the machine side.

In the illustrated embodiment, the motor speed control system 1 on the front stand side is operated to maintain the loop formed between two adjacent stands at a desired value. Needless to say, the present invention can also be applied to a motor speed control system at a later stage.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. 1.2...Stand, 3...Rolled material, 41...
Electric motor, 42... Thyristor converter, 5... Speed control device, 6... Speed setter, 7... Speed detector, 8
...l rape adjuster, 9... loop setting device, 10.
...Loop detector, 12...State observation device, 121...
- Controlled object model (integral element), 122... Integral element, 123, 124... Amplifier.

Claims (1)

[Claims] l) In order to control the loop of rolled material formed between two adjacent stands in a multi-high rolling mill consisting of a plurality of stands each driven by an individual electric motor, one It is equipped with a loop controller that superimposes a speed correction valve according to the loop control deviation on the speed command value of the stand's motor speed control system, and also uses the loop detection signal and the motor speed detection signal of one stand to determine the roll output of the previous stand. 11111 Equipped with a condition observation device that calculates a quantity that simulates the difference between the material speed and the roll entry speed of the subsequent stand, using the motor speed of one stand as a reference, and adjusts the speed command value according to the output signal of this condition observation device. 09 is a loop control method for a multi-high rolling mill in which loop fluctuations are suppressed by variably setting . 2. In the control method according to claim 1, the state observer includes a first integral element that simulates a controlled object;
a second integral element for extracting the output signal of the state observer; the deviation between the motor speed detection signal and the 113 force signal of the second integral element is input to the first integral element;
The second integral side lc is a loop control system for a multi-high rolling mill in which the deviation between the loop detection signal and the output signal phase of the first integral element is input.