JPH0358803B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling a loop of rolled material formed between two adjacent stands in a multi-high rolling mill consisting of a plurality of stands each driven by a separate electric motor. , a motor speed control device that controls the motor speed detection value of the motor in one stand to the speed setting value set by the speed setting device, and a loop setting value set by the loop setting device and detected by the loop detector. and a loop adjuster that outputs a speed correction amount according to a loop control deviation from the loop detection value, and by adding the speed correction amount to the speed setting value and providing it to the motor speed control device, the loop detection value can be adjusted. The present invention relates to a loop control method for a multi-high rolling mill, in which is controlled so that is equal to a loop set value.

When rolling is performed while forming a loop in the rolled material between two adjacent rolling stands, it is required to maintain the loop amount 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 motor speed command value of one stand is corrected according to the loop control deviation obtained as a result. There is. The adjustment parameters in the loop controller that constitutes such a loop control system are determined by disturbances caused by dimensional fluctuations in the rolled material or temperature changes, and by preset errors in the speed command values given to the motor speed control systems of both applicable stands. The adjustment should be made optimally so that the resulting loop fluctuations are sufficiently suppressed. However, since control stability must be ensured, there is a limit to increasing the response speed of the loop feedback control system. Therefore, the loop control system absorbs disturbances with a period slower than the response speed field and forms a stable loop, but cannot absorb disturbances with a faster period. This causes loop fluctuations. In particular, loop fluctuations caused by errors in speed preset values are large, and in some cases there are problems such as dimensional fluctuations due to material tension or misrolls due to excessive loops.

An object of the present invention is to provide a loop control method capable of suppressing loop fluctuations in an inexpensive manner by eliminating the above-described determination.

The key point of the present invention that achieves this objective is to use the motor speed detector and loop detector, which are also provided in conventional devices, without directly detecting the material velocity on the exit side of the front stage stand and the material speed on the input side of the rear stage stand. A feedback system that indirectly determines the deviation between the speeds of both materials from the output signal of the control object through a state observation device that includes an equivalent model of the controlled object, and then variably sets the speed command value to cancel this deviation. It is possible to quickly absorb disturbances through control and suppress loop fluctuations.

That is, the present invention provides a loop control method for a multi-high rolling mill of the type described at the beginning, in which the loop detection value and the motor speed detection value are expressed as a constant and an advance rate by the gear ratio and roll diameter in the front stage stand. The difference between the material speed on the roll exit side of the front stand and the material speed on the roll input side of the rear stand, which is expressed by a constant based on the gear ratio and roll diameter and the backward movement rate, on the rear stand is based on the detected value of the motor speed of one stand. A state observation device is provided to calculate the estimated amount as , and the deviation between the output signal of this state observation device and the speed command value is added to the sum of the speed setting value and speed correction given to the motor speed control device. It is characterized by

By doing so, according to the present invention,
Loop fluctuations caused by fast-cycle disturbances can be suppressed.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows two mutually adjacent stands 1, 2 of a multi-high rolling mill. The rolled material 3 is formed into a loop between the two stands. Each stand is driven by a separate electric motor,
Here, illustration of the electric motor of the rear stage stand 2 and its control system is omitted. The electric motor 41 that drives the front stand 1 is shown as a DC motor supplied with power via a thyristor converter 42 . The speed control system of this electric motor 41 is controlled by a thyristor converter 4.
2, a speed control device 5, a speed setting device 6, and a speed detection generator 7. As usual, the speed control device 5 includes, in addition to a speed regulator constituting a speed control loop, a current regulator constituting a minor loop for current control inside the speed control loop.

Furthermore, a loop control system is provided outside this speed control loop. This loop control system is composed of a loop adjuster 8 that operates in accordance with the deviation l*-l between the ^output signal l ^* of the loop setter 9 and the output signal l of the loop detector 10. As loop regulator 8, a P or PI operating regulator is used.

Furthermore, a state observation device (observer) 12 is provided, and this includes the motor speed n of the front stage stand 1 detected by the speed detector 7 and the loop amount l detected by the loop detector 10. is entered. A difference △n^ is formed between the output signal n^ of the state observer and the output signal n ₀ ^* of the speed setting device 6, and this difference is the output signal Δn of the loop regulator 8 at the setting input of the speed control device 5. with speed setpoint n ₀ ^*
has been added to. Note that the two switch elements 11 shown are interlocked with each other and are turned on during loop control. When a loop of rolled material 3 is not formed between both stands, both switches 1
1 is in the off state and therefore the speed control device 5
The setting side input n ^* is a preset value n ^* ₀ by the speed setter 6, and the rotational speed n of the electric motor 41 is controlled to this preset value n ^* ₀ . Similarly, the rotational speed of an electric motor (not shown) on the rear stage stand 2 side is also controlled to a preset value in consideration of the desired loop amount. The tip of the rolled material 3 is the rear stand 2
When the stand is engaged and a loop is formed between the stands, both switches 11 are turned on and loop control is performed. During loop control, the signal n ^* on the setting input side of the speed control device 5 is n ^* = n ^* ₀ + △n + △n^ = n ^* ₀ + △n + (n^-n ^* ₀ ) = n^ + n ...(1) becomes. That is, the output signal of the state observation device 12 becomes the speed command value, and the correction amount Δn of the loop regulator 8 is added to this. Therefore, the illustrated embodiment can also be modified into a circuit scheme with a switching circuit for switching n ^* from n ^* ₀ to n^+Δn.

By the way, the stands 1 and 2 shown in FIG.
Rolled material 3, electric motor 41, thyristor converter 4
2. The system consisting of speed controller 5, speed detector 7, loop regulator 8 and loop detector 10 can be represented by the block diagram of FIG. In FIG. 2, ALR represents a loop control system comprising a loop regulator 8, and ASR represents a speed control system comprising an electric motor 41, a thyristor converter 42, and a speed control device 5. As will be described later, a ₁ and a ₂ are constants depending on the gear ratio and roll diameter in stands 1 and 2, f is a forward rate, and φ is a reverse rate. Similarly, as will be described later, v ₁ and v ₂ are values obtained by dividing the roll exit side material speed V ₁ of the front stage stand 1 and the roll input side material speed V ₂ of the rear stage stand 2, respectively, by the reference material speed V ₀ . Therefore, in the front stage stand 1, the output signals n ₁ and a ₁ (1+
f) is performed and is equal to the multiplied value v ₁
is obtained. Further, in the rear stage stand 2, n ₂ given by the speed control system of the rear stage stand 2 (not shown) is multiplied by a ₂ (1-φ),
We get v ₂ which is equal to the multiplied value. The loop time constant T _L representing the rolled material 3 is the value obtained by dividing the reference loop amount L ₀ by the reference material speed V ₀ . The loop amount l is
As described later, it is the value obtained by dividing the loop amount L between the stands by the reference loop amount _L0 , and the loop detector 1
As an output signal of 0, it is given to the state observer 12 as shown in FIG.
The speed detection signal n is similarly given to the state observer 12.

By the way, as can be seen from the above 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 observer 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^. That is, the integral element 122 is constituted by an element having an integral time corresponding to the loop time constant T _L in order to estimate the loop amount l of the rolled material 3 shown in FIG. The model 121 has an integration time n^ _L , the output signal n of the speed detector 7 and the output signal of the integration element 122.
Integrate the difference with n^. The deviation between the output signal l of the loop detector 10 and the output signal of the model 121 is input to the integral element 122 via an amplifier 123 having a gain _g2 . Therefore, the integral element 122 operates to change the output signal n' until the deviation l-l' becomes zero. Amplifier 124 has a gain g ₁ and a deviation l
-l^ is fed back to the input of the model 121, thereby helping to stabilize the two integral elements 121 and 122 connected in a loop by suppressing automatic vibration. Gain g ₁ ,
By selecting an appropriate value for g ₂ , the response of the state observer can be optimized.

By the way, the loop amount L between the stands is expressed by the integral value of the speed difference between the roll exit side material speed of the front stage stand 1 and the roll entry side material speed of the rear stage stand, and the roll exit side material speed of the front stage stand 1
V ₁ and the roll entry side material speed V ₂ of the rear stage stand 2 have the following relationship: L=∫ ^t _p (V ₁ −V ₂ ) dt (2). Here, the reference material velocity is V ₀
Assuming that the reference loop amount is L ₀ , V ₁ , V ₂ , and L are unitized as V ₁ /V ₀ =v ₁ , V ₂ /V ₀ =v ₂ , and L/L ₀ =l, respectively. After replacing the above equation (2) with these unit quantities and performing Laplace transform, it becomes l=1/ _TLS (v ₁ −v ₂ ) (3). However, T _L =L ₀ /V ₀ (=constant),
Further, S is a Laplace operator. These v ₁ and v ₂ and the motor speed n ₁ and n ₂ of each stand 1, 2
As is well known, v ₁ = a ₁・(1+f)・n ₁ ………(4) v ₂ = a ₂・(1−φ)・n ₂ ………( 5) There is a relationship. However, a ₁ and a ₂ are constants depending on the gear ratio and roll diameter in stands 1 and 2, respectively, f is the forward rate, and φ is the reverse rate.

In addition, the constants a ₁ and a ₂ depending on the gear ratio and roll diameter in the stand, the forward rate f and the reverse rate φ are as follows:
It fluctuates due to loop fluctuation factors (for example, material dimensional changes, material temperature changes, roll gap changes, speed preset value errors between stands, impact drop when material is bitten, etc.).

By the way, according to the state observer 12, model 1
Since the output signal l^ of the model 12 is controlled to match the output signal l of the loop detector 10, it is a simulation value of the loop amount.
The operation of 1 can be expressed by the Laplace calculation formula: l^=1/ _TLS (n-n^) (6). Due to the function of the integral element 122 in the state observer 12,
Considering that the control such that l=l^ is performed and the selection that T^ _L ≒T _L is performed, v ₁ −v ₂ = n−n^ from (3) and (6). In other words, the output signal n^ of the state observer 12
can be expressed as n^=n−(v ₁ −v ₂ ) (7). The two expressions preceding this expression
Applying (4) and (5), n^=n−{a ₁・(1+f)・n ₁ −a ₂ (1−φ)・n ₂ }
As can be seen from this formula, state observer 1
The output signal No. 2 includes all loop fluctuation factors based on the motor speed detection signal n of one stand. In the present invention, the output signal n^ of the state observer 12
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, when formula (7) is taken into consideration, v ₁ - _{v 2} = 0 Control will be implemented. That is, v ₁ −
If v ₂ ≠ 0, the loop amount l changes, but according to the present invention, since the speed command value n^ directly includes a component that cancels (v ₁ − v ₂ ), the loop adjustment The speed is changed in response to the loop fluctuations without waiting for a slow response due to the speed correction amount Δn of the speed controller 8. 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 monitor 12, and prevents sudden changes. The compensation effect for the disturbance is the state observer 1.
This is performed by the feedforward control as described above in accordance with No. 2.

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 the material is bitten, etc. can be suppressed with responsiveness. Since it can be well suppressed, the amount of loop between the stands can be kept 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 on the front stage side is operated to maintain the loop formed between two adjacent stands at a desired value. Needless to say, this method can also be applied to a motor speed control system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is a block diagram showing the speed control system and loop control system in FIG. 1. DESCRIPTION OF SYMBOLS 1, 2...Stand, 3...Rolling material, 41...Electric motor, 42...Thyristor converter, 5...Speed control device, 6...Speed setter, 7...Speed detector, 8...Loop regulator, 9...Loop setter , 10... Loop detector, 12... State observer, 121... Controlled object model (integral element), 122... Integral element, 123, 124
…amplifier.

Claims (1)

[Scope of Claims] 1. 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 a separate electric motor, one stand The motor speed detection value n of the motor at is the speed setting value set by the speed setting device 6.
The motor speed control device 5 controls n ₀ ^* and the loop setting value l ^* set by the loop setting device 9.
and a loop controller 8 that outputs a speed correction amount Δn according to a loop control deviation l ^* −l between the loop detection value l detected by the loop detector 10, and Said speed setting value
In a loop control method for a multi-high rolling mill, the loop detection value l and motor speed detection are controlled so that the loop detection value is equal to a loop setting value by adding the value to n ₀ ^* and giving it to the motor speed control device. value n
From, the material velocity v ₁ on the roll exit side of the front stand expressed by the constant a ₁ due to the gear ratio and roll diameter in the front stand and the advance rate f, and the constant ₂ due to the gear ratio and roll diameter at the rear stand.
Calculate an estimated amount n^ for estimating the difference v ₁ - v ₂ between the roll entry side material speed v ₂ of the rear stand and the reverse movement rate φ, expressed by the reverse movement rate φ, based on the motor speed detection value n of the one stand. A state observation device 12 is provided, and the output signal n^ of this state observation device and the speed setting value are
The deviation △n^ from n ₀ ^* is calculated as the speed setting value n ₀ ^* given to the motor speed control device and the speed correction △
A loop control method for a multi-high rolling mill, characterized in that the loop control method is added to an additional value of n.