JPH0716632A - Controller for continuous hot rolling mill - Google Patents

Abstract

PURPOSE:To improve the response for controlling the height of a looper by calculating with integrating a deviation part between a target value and a detected value of the height of looper and correcting the speed correcting value of a main mill controlling system. CONSTITUTION:A main mill speed controller 13 controls the current of a 1st stand main mill 11. Looper motor current controlling means control the current of a looper motor 6. Looper tension controlling means 10 calculate the current commanding value so that the tension of a rolling material is followed to the target value. The looper tension controlling means 10 calculate the current commanding value of the looper motor 6 based on the tension target value of the rolling material 1 and the detected value of the looper height. An integral controlling unit 16 calculates a main mill speed changing amount command value against the deviation of the target value of looper height and the detected value of looper height, and adds it to the main mill speed command value. A state feed-back controlling unit 15 improves the response of height controlling system, calculating the main mill speed changing amount command value and adds it into the main mill speed command value based on the rotational speed of the looper motor 6, the detected value of the looper height and the detected value of the tension of rolling material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a looper between a plurality of stands arranged continuously, and the height of the looper and
The present invention relates to a controller for a continuous hot rolling mill that controls the tension of rolled material.

[0002]

2. Description of the Related Art Thickness and width are part of the evaluation criteria for final products in hot rolling and cold rolling, and the tension applied to the rolled material during rolling affects these thickness and width. Control is performed to keep the tension at a certain value.

In particular, the rolled material in the hot rolling is heated to a high temperature to reduce the deformation resistance of the rolled material, and if the tension is large, it tends to break. If the tension is set low to prevent this breakage, a tensionless state may occur due to disturbance or erroneous setting, and if this state continues, a large loop may occur between the rolling mill stands, causing an accident. Therefore, especially in hot rolling, a looper is provided, and tension control is performed by this looper.
Further, the height of the looper is controlled from the viewpoint of improving the sheet passing property of the material.

In the control of the tension of the rolled material and the height of the looper, there is an interference from the tension of the rolled material to the height of the looper and an interference from the rotational speed of the looper drive motor to the tension of the rolled material. Conventionally, there has been a device that executes a PID calculation for a deviation between a target value and a detected value without suppressing these interferences and individually controls the rolled material tension and the looper height based on the calculation result.

[0005]

Generally, a control system of tension and looper height is expressed by a transfer function, which includes a secondary resonance system. The characteristic of the secondary resonance system is the resonance frequency ω
It is represented by _n and a damping constant ζ, and when the crossing angular frequency of the looper height control response approaches the resonance frequency ω _n , resonance occurs near this frequency, and when the damping constant ζ is small, it becomes oscillatory. Therefore, the response of the looper height control is the resonance frequency ω
_It is limited to about 1/4 or less of _n , and must be suppressed to a lower value depending on the value of the damping constant ζ. Therefore, the conventional control device has a problem that the control response cannot be sufficiently improved.

There is a conventional method of multiplying the rotation speed of the looper motor by a constant to convert it into a changed value of the current reference and adding it to the current reference of the looper drive motor to equivalently increase the damping of the looper. However, this method slows down the response of the looper motor, which may adversely affect the tension of the rolled material.

The present invention has been made to solve the above problems, and substantially eliminates the resonance frequency of the rolling material tension and looper height control system to improve the looper height control response. At the same time, it is an object to obtain a controller for a continuous hot rolling mill that enables highly accurate and stable control of the looper height.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a looper is provided between a plurality of stands arranged continuously, and a main motor for driving a rolling mill of each stand and a looper motor for driving a looper are controlled at a speed. A main machine control system that controls the speed of the main machine motor according to the command value, and a controller for a continuous hot rolling mill that has a looper motor control system that controls the current of the looper motor according to the current command value, and a target value for the tension of the rolled material. Based on the detected value of the looper height, the looper tension control means that calculates the current command value of the looper motor that causes the tension of the rolled material to follow the tension target value, and the deviation between the looper height target value and the detected value On the other hand, at least an integral calculation is executed, and the integral control means for correcting the speed command value of the main machine control system according to the calculation result, the tension detection value of the rolled material,
The detected value of the rotation speed of the looper motor and the detected value of the looper height are multiplied by the feedback gains that are set so as to substantially eliminate the resonance points of the control response of the looper height, and the results are added. And a state feedback control means for correcting the speed command value of the control system.

[0009]

According to the present invention, at least an integral calculation is executed for the deviation between the target value and the detected value of the looper height, and the speed correction value of the main machine control system is corrected based on the result, and the rolling material The detected values of the tension, the rotation speed of the looper motor, and the looper height are multiplied by the feedback gains that are set so as to substantially eliminate the resonance point of the control response of the looper height, and the results are added. Since the speed correction value of the system is corrected, the control response of the looper height can be increased, which enables highly accurate and stable looper height control.

[0010]

The present invention will be described in detail below with reference to the illustrated embodiments. FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention together with a rolling system. In the figure, the rolled material 1 is the i-th stand 2 and the i + 1-th stand 3
Are rolled in this order. Here, when the total number of stands of the tandem rolling mill is n, n = 5 to 7 is general. Devices such as the looper shown below are installed between the stands.
It is possible to easily extend to other stands by considering the state between the two stands i to i + 1. Therefore, only the two stands will be considered here. Note that i is in the range of 1 ≦ i ≦ n−1.

When the looper 4 is provided between the i stand and the i + 1 stand, the height of the looper converted into the angle of the looper arm is detected by the looper height detector 5. A looper motor current control means 8 is provided to control the current of the looper motor 6. The looper motor current control means 8 controls the current so that the current command value and the current detection value by the looper motor current detector 9 match. Further, there is provided a looper tension control means 10 for obtaining a current command value for the looper electric motor current control means 8. The looper tension control means 10 calculates a current command value based on the target value of the looper height and the value detected by the looper height detector 5.

On the other hand, the speed of the i-th stand main machine 11 for driving the rolling machine of the i-th stand is detected by the main machine speed detection device 12, and the main machine speed control device 13 makes the main machine speed command value and the main machine speed detection value equal. Thus, the current of the main unit 11 of the i-th stand is controlled.

A rotation speed detector 7 for detecting the speed of the looper motor 6 and a tension detector 14 for detecting the rolling material tension between the stands are provided, and the detected values are added to the state feedback controller 15. It has become. The state feedback controller 15 takes in the detection values of the looper height detector 5 in addition to the detection values of the rotation speed detector 7 and the tension detection device 14, and calculates the speed correction value for the i-th stand main unit 11. The speed reference is corrected by this speed correction value. Further, the reference value of the looper height and the detected value of the looper height by the looper height detector 5 are fetched, PI calculation is executed for the difference, and the speed reference for the i-th stand main unit 11 is determined by the calculation result. An integral controller 16 for correction is provided.

The operation of this embodiment configured as described above will be described below. When the rolled material 1 is rolled in the order of the i-th stand 2 and the (i + 1) th stand 3, the main machine speed control device 13 determines the speed reference V _MREF and the main machine speed detection device 12
The electric current of the i-th stand main engine 11 is controlled so that the detected value V _M of the main engine rotation speed according to Further, the looper motor current control means 8 causes the current command value I _LREF output from the looper tension control means 10 and the current detection value I _L of the looper motor 6 detected by the looper motor current detector 9 to coincide with each other. Control the current of.

The looper tension control means 10 calculates a current command value I _LREF that causes the tension of the rolled material 1 to follow the tension target value t _fREF (kg / mm ² ) by the following method.

[0016]

[Equation 1] I _LREF = F ₀ ^* (θ, t _fREF ) (2) where θ: looper height converted to an angle g: gravitational acceleration R ₁ : distance from looper rotation center to looper roll center R ₂ : Looper roll radius R ₃ : Distance from the center of rotation of the looper to the center of gravity of the looper (mm) g _L : Gear ratio between the looper machine and the looper electric motor A: Cross sectional area of the rolled material α: Angle between the pass line and the rolled material β: Path angle between the line and the rolled material W _s: mass of the strip between stands W _L: a looper mass.

Therefore, the looper tension control means 10 causes the current command value I of the looper motor to make the tension of the rolled material follow the tension target value based on the tension target value t _{fREF of} the rolled material and the detected value θ of the looper height. _LREF can be calculated.

On the other hand, the integral controller 16 controls the looper height target value θ
_The PI calculation is executed for the deviation between the _REF and the looper height detection value θ detected by the looper height detector 5 to calculate the main machine speed change amount command value ΔV _R2, which is added to the main machine speed command value V _MREF .
Further, the state feedback controller 15 detects the rotation speed ω _L of the looper motor 6 by the rotation speed detector 7, the looper height detection value θ by the looper height detector 5, and the rolling material tension detection value by the tension detection device 14. As will be described in detail later, based on t _f , a main engine speed change amount command value ΔV _R1 that improves the response of the height control system and brings the response close to a desired value is calculated, and the main engine speed command value V is calculated. _Add to _MREF .

The state feedback controller 15 intended to eliminate the resonance point of the looper control system by changing the ζ resonance frequency omega _n and damping factor of the looper height control system previously described, then, the resonance frequency omega _n and attenuation The change of the constant ζ will be described.

Of the conventional rolled material tension and looper height control by PID control, the looper control system is shown in a block diagram in FIG. In the figure, a series of blocks 100 surrounded by a broken line represents a process to be controlled, a block 101 is a conversion element from a looper angle reference θ _REF to a height reference l _REF, and a block 102 is a looper angle θ to a looper height. It is a conversion element to Sa. A block 103 corresponds to the height control controller of the looper, and is an element for executing a PI calculation on the deviation between the height reference l _REF and the looper height l to output a main engine speed change amount command value Δ _VRREF , A block 104 is an element showing a speed control system including an i-th stand main engine 11, a main engine speed detection device 12, and a main engine speed control device 13. Further, the block 105 is an element corresponding to the looper tension control means 10,
Flock 106 is an element corresponding to the looper motor current control means 8.

When the transfer function from the main engine speed change amount command value Δ _VRREF to the change amount Δθ of the looper angle is expressed by a transfer function, the transfer function G (S) of the secondary resonance system shown in the following equation is included.

[0022]

[Equation 2] Of these, the resonance frequency ω _n and the damping constant ζ are given by the following equations.

[0023]

[Equation 3] However, E: Young's modulus of rolled material L: Distance between rolling stands J _L : Moment of inertia of looper F ₂ (θ): Looper angle-loop amount conversion derivative coefficient F ₃ (θ): Tension-torque conversion derivative coefficient K ₁₀ : Tension Feedback coefficient Z: Looper damping coefficient.

On the other hand, the looper system shown in FIG.
That is, it can be expressed by the following equation when expressed by the state equation.

[0025]

[Equation 4] The matrices A, B, and C are as shown below.

[0026]

[Equation 5] Here, two of the eigenvalues of the A matrix are resonance frequencies ω _n
And the damping constant ζ are used to express the following equation.

Λ = −ζ · ω _n ± jω _n · ζ ² −1 (8) It is known that this eigenvalue can be arbitrarily changed by applying state feedback. In this embodiment, the resonance frequency ω _n and the damping constant ζ are indirectly changed by appropriately selecting the gain of the state feedback controller 15. By selecting the gain so that this eigenvalue becomes λ _f = −ω _f (9), the response of the control system can be set to ω _f (rad / s). However, it is assumed the other eigenvalues is greater than omega _f, it is possible to improve the response than conventional control system by taking the omega _f increases.

FIG. 3 is a block diagram of a looper control system corresponding to the present embodiment. The same elements as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. This eliminates the block 103 in FIG. 2 corresponding to the conventional looper height control controller, and replaces it with the block 107 corresponding to the integral controller 16 and the block 107 corresponding to the state feedback controller 15. Has been added.

Block 108 is a feedback gain K _F01 for the rolled material tension t _f , and a rotation speed ω of the looper motor.
Feedback gain K _F02 for _L , looper height θ
Has a feedback gain K _F04 for the feedback gain K _F03, velocity V _R of the i stand main engine 11 against. Therefore, feedback gains K _F01 , K _F02 , K _F03 , K _F04 for eliminating the resonance point of the looper control system are provided.
And the integration constant K _IO of the block 107 by using the parameter expressing the process to be controlled, for example,
It can be determined as follows.

[0030]

[Equation 6] However, T _v : Time constant of main machine speed control system L: Distance between stands α: Influence coefficient from main machine speed to rolling material speed E: Young's modulus of rolled material K _IO : Integral constant Z: Looper damping coefficient J _L : Looper motor inertia Efficiency g _L : Gear ratio between looper and looper electric motor F ₂ : Effect coefficient from looper height to rolled material tension F ₃ : Effect coefficient from rolled material tension to looper electric motor torque.

The cutoff frequency of the closed loop response from the looper height reference θ _REF to the looper height θ is ω _HC, and S
_{When 1} = S ₂ = S ₃ = S ₄ = −ω _HC , the adjustment coefficient for the main engine control system becomes large, and as shown in the following equation, it is possible to approach a fourth-order delay system without a resonance point.

[0032]

[Equation 7] Thus, according to this embodiment, the resonance point of the looper height control system can be substantially eliminated.

[0033]

As is apparent from the above description, according to the present invention, the speed correction value of the main machine control system is corrected according to the deviation between the target value and the detected value of the looper height, and the rolling material The detected values of the tension, the rotation speed of the looper motor, and the looper height are multiplied by the feedback gains that are set so as to substantially eliminate the resonance point of the control response of the looper height, and the results are added. Since the speed correction value of the system is corrected, the control response of the looper height can be increased, which enables highly accurate and stable looper height control.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention together with a rolling system.

FIG. 2 is a diagram showing a configuration of a control system of a conventional continuous hot rolling mill by a transfer function.

FIG. 3 is a diagram showing a configuration of an embodiment of the present invention by a transfer function.

[Explanation of symbols]

 2 i-th stand 3 i-th stand 3 4 looper 5 looper height detector 6 looper electric motor 7 rotation speed detector 8 looper electric motor current control means 9 looper electric motor current detector 10 looper tension control means 11 i-stand main engine 12 main engine speed Detector 13 Main engine speed controller 14 Tension detector 15 State feedback controller 16 Integral controller

Claims (1)

[Claims] 1. A looper is provided between each of a plurality of stands arranged continuously, and the speed of the main motor is controlled according to a speed command value when controlling the main motor and the looper motor for driving the rolling mill of each stand. In a controller for a continuous hot rolling mill, which has a main machine control system to control and a looper motor control system to control the current of the looper motor according to a current command value, the target value of the tension of the rolled material and the detected value of the looper height are set. Based on the looper tension control means that calculates the current command value of the looper motor that causes the tension of the rolled material to follow the tension target value, and at least an integral calculation is performed for the deviation between the looper height target value and the detected value. Then, the integral control means for correcting the speed command value of the main machine control system based on the calculation result, the detected tension value of the rolled material, the detected value of the rotation speed of the looper motor, and the loop The detected value of the height of the looper is multiplied by a feedback gain determined so as to substantially eliminate the resonance point of the control response of the looper height and added, and the speed command value of the main engine control system is corrected by the addition result. A control device for a continuous hot rolling mill, comprising: