JPH09136108A - Controller for hot tandem mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for hot tandem mills capable of highly accurately and stably controlling a looper when the height of the looper arranged between respective stands of a tandem mill and the interstand tension of a rolled stock are controlled. SOLUTION: This controller is provided with a main current reference generating means 13 for calculating main looper current reference Iref1 such as balances the sum of the torque which is received with the looper from the rolled stock torque received from the tension of the rolled stock and torque caused by the gravity of the looper with a looper current reference generator 12 for controlling the tension of the rolled stock by calculating command value Tref of a looper current based on the target value tfref of tension and a detected value θ of looper height and setting this command value Iref of the looper current to a looper current controller 9 of a looper motor 8, and an auxiliary current reference generating means 14 for calculating an auxiliary looper current reference ICOM such as to balances torque necessary to accelerate and decelerate the looper. By the auxiliary current reference generating means 14, the auxiliary looper current reference ICOM obtained by adding either one or plural necessary conditions among the changes of the cross-sectional area of the rolled stock, the ascending speed of the looper and command value of speed is calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for a tandem hot rolling mill, which controls the height of a looper disposed between stands of a tandem hot rolling mill and the tension between stands of a rolled material.

[0002]

2. Description of the Related Art Plate thickness and plate width are part of the evaluation criteria for final products in hot rolling and cold rolling, and the tension applied to the material during rolling affects the plate thickness and plate width. Control to keep a certain value is being performed. In particular, the rolled material in hot rolling is heated to a high temperature, its deformation resistance is small, and if the tension is large, it tends to break. If the tension is set low to prevent this breakage, the tension may become zero due to disturbance or erroneous setting, and if this state continues for a long time, a large loop may occur between the rolling mill stands to cause an accident. Therefore, in hot rolling, in particular, a looper device is installed to prevent loops from being generated between stands, and at the same time the tension of the rolled material between the stands is controlled, and the looper height is increased from the viewpoint of improving the material threadability. It also controls.

In such control of the rolled material tension and the looper height, there are interference from the rolled material tension to the looper height and interference from the rotational speed of the looper to the tension. In the conventional tension control, there is a method of controlling the looper height by PID control without suppressing their interference. In the PID control of the looper height, the looper calculates the torque that the looper receives from the weight of the looper itself, the weight of the rolled material, and the tension of the rolled material (tension command value), and the torque when the looper accelerates and decelerates. By setting the electric current command value in the electric motor, the looper generates a force to push up the rolled material, and applies tension to the rolled material. Therefore, it is an open loop only for setting, rather than feeding back the tension value.

On the other hand, the above-mentioned interference system is treated as a multivariable variable, and a decoupling compensator for suppressing the interference is added to the looper decoupling control for independently controlling the rolling material tension and the looper height. Optimal control theory (LQ: Linear Quadratic) so that the looper and rolled material tension are controlled in coordination
, The looper ILQ (Inv that can obtain the control gain by a mathematical expression by solving the inverse problem of LQ.
There are multivariable controls such as erse linear quadratic control and H∞ control that can take into account the robustness of the control system, and they are applied to actual machines. Here, the robustness is a property in which it is difficult for the control system to become unstable even if noise is added to the control system or the control target changes.

[0005]

The multivariable control is premised on detecting both the rolling material tension and the looper angle in order to make the most of their respective characteristics. For this reason, it was difficult to apply multivariable control to rolling mills without a tensiometer. The tension between the i-th stand and the (i + 1) th stand of the rolling mill is generated after the tip of the rolled material is caught in the (i + 1) th stand, that is, after the (i + 1) th stand has been threaded. During this passage, the disturbance is very large, and the tension detection value by the tension meter will not stabilize until a short time has passed after the (i + 1) th stand passage. During this period, the tension value required for multivariable control cannot be obtained. Looper height PID that does not require
Control is needed.

Further, depending on the rolled material, the tension control by the multivariable control may not be fully covered, and the PID control with a well-adjusted looper height may show better control performance, and the tension detection is good. If not performed, the multi-variable control may malfunction, so the looper height PID
Control is also necessary for good control of the looper.

However, the above-mentioned looper height PI
Since the feedback control is not performed in the D control, the tension value may not be controlled according to the target value. Further, when calculating the current reference value to be set in the looper electric motor, since the current value required for accelerating and decelerating the looper is not known exactly, a fixed current value is generally added until now. In this case, for a rolled material having a small cross-sectional area, the specific gravity of the torque due to the fixed current value becomes larger than the torque due to the weight of the rolled material and the torque due to the tension.
There has been a problem that the force of the looper for lifting the rolled material increases and the tension value of the rolled material tends to be larger than the target value.

Further, since the PID control of the looper height does not work to suppress the mutual interference between the rolled material tension and the looper, it may be inferior to the multivariable control in terms of responsiveness and stability. This is because the control response of the looper height control cannot be sufficiently increased for the reason. That is, when the tension and the looper system are expressed by a transfer function, they are expressed in a form including a secondary resonance system. The characteristic of the secondary resonance system becomes oscillatory when the damping constant ζ of the resonance frequency ω _n is small. For this reason, the response of the control of the looper height is limited to about 1/4 or less of the resonance frequency ω _n , and it must be further suppressed depending on the magnitude of the damping constant ζ.

The present invention has been made to solve the above-mentioned problems, and when controlling the height of the looper arranged between the stands of the tandem rolling mill and the tension between the stands of the rolled material, it can be performed with high accuracy. An object of the present invention is to provide a control device for a tandem hot rolling mill that enables stable control of the looper.

[0010]

According to the present invention, a looper current command value is calculated based on a tension target value and a looper height detection value, and this looper current command value is set in a looper current controller of a looper motor. As a looper current reference generator that controls the tension of the rolled material by using the main current reference that calculates the main looper current reference that balances the sum of the torque received by the looper from the rolled material, the torque received from the rolled material tension and the torque due to the looper's own weight. It comprises a generating means and an auxiliary current reference generating means for calculating an auxiliary looper current reference that balances the torque required to accelerate and decelerate the looper. A looper current reference is calculated so as to be proportional.

Another aspect of the present invention is that the auxiliary current reference generating means uses a fixed current reference or a looper current reference determined to be proportional to the cross-sectional area of the rolled material, and further, a current value proportional to the rising speed of the looper. Is added to calculate the auxiliary looper current reference.

In another invention, the auxiliary current reference generating means uses a fixed current reference or a looper current reference determined so as to be proportional to the cross-sectional area of the rolled material, and further, a looper height controller calculates The auxiliary looper current reference is calculated by adding a current value proportional to the change in the speed command value of the electric motor.

According to another aspect of the invention, a speed command value of the rolling mill main electric motor is calculated based on the looper height target value and the looper height detected value, and the calculated speed command value is used for the rolling mill main electric motor speed. A looper height controller that is set in the controller to control the looper height, calculates a looper current command value based on the target tension value and looper height detection value, and then calculates the calculated looper current command value. When equipped with a looper current reference generator that sets the looper current controller of the electric motor to control the rolled material tension, the tension of the rolled material is determined by the force received by the tension detector attached to the looper or the torque received by the looper motor. A tension calculation means for calculating and a tension component torque correction means for changing the resonance frequency and the damping constant of the looper height control system based on a value obtained by multiplying the calculated tension by a gain.

In order to change the resonance frequency and the damping constant of the looper height control system, a value obtained by multiplying the calculated tension by the gain is output from the looper current reference generator as a correction value for the looper current reference. At the same time as subtracting from the looper current reference, the gain of the looper height controller that changes due to this subtraction is corrected to an appropriate value.

Further, in order to change the resonance frequency and the damping constant of the looper height control system, the value obtained by multiplying the calculated tension by the gain is used as the change amount of the main machine speed command value from the looper height controller. At the same time as adding to the output speed command value, the gain of the looper height controller that changes due to this addition may be corrected to an appropriate value.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the drawings. FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention together with an applicable rolling mill. In the figure, the rolled material 1 is rolled in the order of the i-th stand rolling mill 2 and the (i + 1) th stand rolling mill 3. Here, when the total number of stands of the tandem rolling mill is n, n = 5 to 7 is general. Devices such as a looper shown below are installed between the stands, but it can be easily expanded to other stands by considering the state between the two stands of i to i + 1 stands, so only the two stands will be considered here. . Note that i is in the range of 1 ≦ i ≦ n−1.

When the looper 7 is provided between the i-th stand and the (i + 1) th stand, the height of the looper converted into the angle of the looper arm is detected by the looper height detector 10. The current detection value I of the looper electric motor 8 that drives the looper 7 is fed back to the looper current controller 9. The looper current controller 9 controls the current detection value I to follow the current command value I _ref set by the looper current reference generator 12. On the other hand, the i-th stand rolling mill 2 and the (i + 1) th stand rolling mill 3 are driven by rolling mill main electric motors (hereinafter, referred to as main machines) 4 and 5, respectively. The speed of the i-th stand main engine 4 is controlled by the main engine speed controller 6. The same applies to the i + 1-th stand main unit 5, but is omitted here.

The looper height controller 11 is a looper height detector.
The main machine speed command value is calculated so that the looper height (represented by the looper angle θ, hereinafter also referred to as the looper angle) detected in 10 follows the looper height target value θ _ref and added to the main machine speed set value. The main engine speed controller 6 of the i-th stand. The looper current reference generator 12 is the main current reference generator 13
And an auxiliary current reference generator 14. A geometric shape in the case where a looper driven by an electric motor is arranged between the i-th stand and the (i + 1) th stand and the rolled material is lifted by this looper is shown in FIG. The main current reference generator 13 calculates the main current command value I _ref1 by the following equation based on the geometrical shape of FIG.

[0019]

(Equation 1) However, g: acceleration of gravity (mm / s ² ) = 9800 R ₁ : distance from rotation center of looper to center of looper roll (mm) R ₃ : distance from rotation center of looper to center of gravity of looper (mm) g _L : Gear ratio between looper machine and looper electric motor A: Cross-sectional area of rolled material (product of plate thickness and plate width) (mm ² ) α: Angle between pass line on i stand side and rolled material (rad) β: i + 1 angle between the pass line on the stand side and the rolled material (rad) θ: looper angle (rad) W _s : mass of rolled material between stands (product length, cross-sectional area, specific gravity product) (kg) W _L : Looper weight (kg). If the looper angle θ and the target tension value t _fref are set by the equations (1) and (2),
The main current command value I _ref1 can be calculated.

Incidentally, FIG. 10 shows an example of the configuration of a control device for a tandem hot rolling mill which has been conventionally implemented. The main current reference generator 13 has a function of calculating the main current command value I _ref1 by using the above equations (1) and (2). However, fixed current reference generator 15 corresponding to the auxiliary current reference generator 14 of this embodiment shown in FIG. 1, the current reference I ₀ of the fixed
There was only a function to generate.

Next, the auxiliary current reference generator 14 of this embodiment will be described below. The auxiliary current reference generator 14 calculates the auxiliary current reference I _COM by any one of the following methods a, b, and c. a. The auxiliary current reference is stored in advance in a table divided by the cross-sectional area and taken out at the time of use. This auxiliary current reference may be determined using the arithmetic expression described in the following item b,
Further, it may be stored in the table while being adjusted. b. Calculate using the following formula.

[0022]

(Equation 2) However, I _COM : auxiliary current reference I _ST : standard current reference A _ST : standard cross-sectional area It is also possible to set an upper limit and a lower limit to the above-mentioned auxiliary current reference I _COM .

When a fixed current reference I ₀ is used as in the conventional apparatus shown in FIG. 10, a substantially constant tension value is added regardless of the cross-sectional area of the rolled material, resulting in a large cross-sectional area. Compared with the material, the tension value of the small area material was likely to be larger than the target value. However, as described in the above item a or b, when the auxiliary current reference I _COM proportional to the cross-sectional area is used, the phenomenon that the tension value becomes larger than the target value for a rolled material having a small cross-sectional area is mitigated. be able to. c. Calculate using the following formula. I _COM = K _COM × ω _L + I _BASE (4) where I _COM : auxiliary current reference K _COM : gain ω _L : looper angular velocity I _BASE : current reference value of item a or b, or fixed current reference It is a value. In this case, it is possible to set an upper limit and a lower limit to the auxiliary current reference I _COM given by the equation (4).

Using the above equation (4), the auxiliary current reference I _COM
By calculating, if there is a loop in the rolled material between the stands, the looper must rise rapidly to remove the loop in the rolled material in a short time. By outputting the current reference,
Loops can be removed faster.

FIG. 3 is a block diagram showing the configuration of the second embodiment of the present invention, and in particular, expresses the control system of the looper height and tension as a model. Here, in the looper height control, the looper angle to be controlled and the main machine speed, which is an operation amount, have a non-linear relationship, and are converted into a rolled material loop amount 1 between stands having a linear relationship with the main machine speed, A looper height control system is configured using the loop amount l. A non-linear function F ₂ (θ) for converting the looper angle θ into the loop amount 1 is expressed by the following equation (5).

[0026]

(Equation 3) The loop amount l is l = F ₂ (θ) (6) where, L: distance between stands (mm) L ₁ : distance from rotation center of looper to i-th stand (m
m).

In FIG. 3, a block 20 corresponds to the looper height controller 11 in FIG. 1 and sets the looper angle target value θ _ref to
Using the equation (5), the loop amount target value l _ref is converted, and the looper angle θ is converted into the loop amount l. The looper height controller 21 is composed of a PI control system, and is represented by a proportional control gain K _P , an integral control gain K _I , and a total gain K _T , which is a deviation between the looper angle target value θ _ref and the loop amount l ( K _P + K _I / s) _KT multiplied by main engine speed command value V _Rref
Is output.

The main machine speed control system 22 represents the speed response of the main machine using the first-order lag time constant T _v , and is the transmission of the combination of the main machine speed controller 6 and the i-th stand main machine 4 in FIG. It is expressed as a function. This main engine speed control system 22
The roll peripheral speed variation V _R obtained by multiplying the transfer function of
converted to _s . The material velocity V _s , the loop velocity change amount ω _L × dF ₂ (θ) / dθ of the rolled material due to the looper angular velocity ω _L represented by block 26, and the tension based on the tension feedback coefficient K ₁₀ represented by block 25 The sum of the changes to the material velocity given by ## EQU1 ## is the tension t _f through the block 24 containing the integrator. The E in the block 24 is the Young's modulus of the rolled material. The tension t _f appears as the tension component torque T _T applied to the looper motor. The block 27 expresses this, and F ₃ (θ) written inside is expressed by the following equation.

[0029]

(Equation 4) Block 28 is a transfer function from the torque applied to the looper motor to the rotational speed ω _L of the looper motor, and ω _L is integrated to form the looper angle θ, which is the block 29.
Is represented by The block 30 represents the looper damping Z, and the block 31 is a function F ₁ (θ) representing the relationship from the looper angle θ to the torque of the looper motor, which is expressed by the following equation.

[0030]

(Equation 5) Block 32 corresponds to looper current reference generator 12 in FIG. Block 33 is a representation of the looper current control system of the time constant T _cc at a primary delay, block 34 represents the influence coefficient (referred to as torque constant) [Phi when the looper current I becomes the torque T. Blocks 28, 33 and 34 in FIG. 3 correspond to the looper current controller 9 and the looper electric motor 8 in FIG. As described above, the reason why the auxiliary current reference is necessary is that it is necessary to compensate the torque when accelerating and decelerating the looper, but it is generally difficult to precalculate the torque required for accelerating and decelerating.

The acceleration / deceleration torque T _A is expressed by the following equation.

[0032]

(Equation 6) However, J: inertia of the looper (kgm ² ). The amount to follow the change of the rolled material speed V _s generated through blocks 22 and 23 in FIG. 3, the looper angular velocity omega _L
Equal to the rolling stock velocity varying from to through block 26, the tension will not change. The rolling material speed V _s that changes through the block 26 is represented by the following equation.

[0033]

(Equation 7) When the material speed changes, the tension changes and the force applied to the looper also changes, so the looper moves up or down. The torque required to raise and lower the looper is the acceleration / deceleration torque,
The equation (10) is solved for the looper angular velocity ω _L , both sides are differentiated with respect to time, and both sides are multiplied by J to obtain the following equation.

[0034]

(Equation 8) As a result, it can be seen that the acceleration / deceleration torque T _A is represented by the inertia J of the looper, the time variation of the material speed, and the angular differential value of the function F ₂ (θ). However, since it is difficult to measure the speed of the rolled material, the time change of the main machine speed command value V _Rref output by the looper height controller is used as an alternative. Thus, instead of the auxiliary current reference I _{CO M} auxiliary current reference generating means 14 shown in FIG. 1 has been described above, it can be seen that if the output of the auxiliary current reference I _COM shown in the following equation.

[0035]

(Equation 9) A block 35 in FIG. 3 generates a time change amount of the main engine speed command value V _Rref , and a block 36 represents a gain.

Thus, according to the second embodiment, the acceleration / deceleration torque of the looper in the conventional PID control of the looper height can be compensated, and the tension is set to the target value because the constant auxiliary current reference is set. It will never be bigger. As a result, it is possible to reduce adverse effects on plate thickness and plate width due to overtension.

By the way, in the second embodiment shown in FIG. 3, the transfer function G (s) from the main machine speed command value V _Rref to the looper angle θ is given by the following equation.

[0038]

(Equation 10) Here, ω _{n is the} resonance frequency ζ is the damping constant. The resonance frequency ω _n is expressed by the following equation.

[0039]

[Equation 11] The damping constant ζ is expressed by the following equation.

[0040]

(Equation 12) In the looper height control, in order to avoid resonance, the resonance frequency ω
_It is necessary to suppress the response to about 1/3 to 1/5 of _n .
Generally, the resonance frequency ω _n = 5 to 10 rad / s,
The control response of the looper height is about 2 to 4 rad / s.
In order to speed up the response of the looper height control system, it is preferable that the resonance frequency is in a high frequency region and that the damping constant is large, because it becomes difficult to vibrate.

The following methods A, B and C can be considered as methods for changing the resonance frequency and the damping constant. A. The influence coefficient F ₂ from the looper speed to the material speed is changed. B. Change the influence factor F ₃ from the tension to the looper torque. C. Change the tension feedback coefficient K ₁₀ .

Of these, the item A is described in JP-A-7-1.
As disclosed in Japanese Patent No. 6632 and known, B and C
The terms are explained.

The above-mentioned looper height PID control is often used together with the looper multivariable control, and a tension detector may be installed to monitor the tension of the rolled material. In many cases, the tension detection value can be used even in the PID control of the looper height.

FIG. 4 is a block diagram showing the configuration of the third embodiment of the present invention corresponding to the method of the above section B, together with the rolling mill to which it is applied. In the figure, the same elements as those of FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Here, the tension calculation means 17 calculates the tension of the rolled material based on the output signal of the tension detector 16 such as a load cell. The tension-based torque correction means 18 uses the calculated tension to correct the current reference I _ref set in the current controller 9 of the looper motor. This correction method will be described below with reference to FIGS. 5 and 6.

If the influence coefficient F ₃ can be changed from the equation (14), the resonance frequency can be changed.
Now, suppose that the gain K _F3 ^* is added to increase F ₃ as in the following equation. F ₃ → F ₃ + K _F3 ^* (16) The resonance frequency ω _{n in} this case becomes large as in the following equation.

[0046]

(Equation 13) This relationship is modeled and expressed as shown in FIG. That is, the block 37 is connected in parallel with the block 27. However, the product obtained by multiplying the rolled material tension t _f by the gain K _F3 ^* is directly applied to the load torque T of the looper motor.
Therefore, as shown in FIG. 6, the product obtained by multiplying the rolled material tension t _f by the gain K _{F3 of the} block 38 is _fed back to the current command value I _ref . However, if the influence coefficient F ₃ is changed, the gain of the transfer function G (s) also changes. The transfer function G (s) in this case is as follows.

[0047]

[Equation 14] Here, as in the case of Z, when F ₃ is changed by the equation (14), the gain of G (s) changes. Therefore, in order to obtain a flush control response as before the F _3, it is necessary to change the total gain K _T of the looper height control to the total gain K _T ^* follows the height control unit .

[0048]

(Equation 15) In FIG. 4, the broken line from the block 18 to the block 11 means that the total gain of the looper height control is corrected by the equation (19). Thus, according to the third embodiment, it is possible to improve the looper height control response by changing the resonance frequency and the damping constant in the looper height control, and it is possible to control the looper at high speed and stably. In the third embodiment, the tension of the rolled material is calculated based on the output of the tension detector 16,
Alternatively, it can be calculated from the torque received by the looper motor.

FIG. 7 is a block diagram showing the configuration of the fourth embodiment of the present invention corresponding to the method of the above item C, together with the rolling mill to which it is applied. In the figure, the same elements as those of FIG. 1 or 4 are designated by the same reference numerals, and the description thereof will be omitted. Here again, the tension calculation means 17 calculates the tension of the rolled material based on the output signal of the tension detector 16 such as a load cell. The tension generation gain correction means 19 calculates the amount of change of the main engine speed command value using this tension and adds it to the main engine speed command value. A method of calculating the change amount of the main machine speed command value of the tension generation gain correction means 19 will be described below with reference to FIGS. 8 and 9.

As is clear from the equation (14), if the tension feedback coefficient K ₁₀ can be changed, the resonance frequency can be changed. That is, as shown in FIG. 8 which models the control system of the tension and the looper height, it can be indirectly changed by connecting the block 39 to the block 25 of K ₁₀ in parallel. This means that K ₁₀ is increased as in the following equation. K ₁₀ → K ₁₀ + K _K ^* (20) If K ₁₀ is increased, the resonance frequency ω _n is increased as in the following equation.

[0051]

(Equation 16) Further, the damping constant ζ also becomes large as in the following equation.

[0052]

[Equation 17] However, it is not possible to directly return the tension multiplied by the gain K _K ^* to the material velocity. Therefore, as shown in FIG.
The block 40 returns to the main engine speed command value V _Rref .
Here, as in the third embodiment, when K ₁₀ is increased in the equation (18), the gain of the transfer function G (s) is reduced.
Therefore, if it is attempted to obtain a control response with the same looper height as before K ₁₀ is changed, the total gain K _T of the looper height controller is
Needs to be increased as K _T ^{* in} the following equation.

[0053]

(Equation 18) Here, K _T ^* is the total height control gain after the change. In FIG. 7, a broken line drawn from the block 19 to the block 11 indicates that the looper height control total gain is corrected by the equation (23). Thus, K ₁₀
By adding K _K ^* to, the following effects a and b can be obtained. I. As K ₁₀ increases, the gain from the material speed to the tension (1 / K ₁₀ ) decreases and the tension fluctuation decreases. B. If the tension is increased, the main machine speed is increased, which is effective as tension control as a means other than the tension control by the looper current.

Thus, according to the fourth embodiment, it is possible to increase the looper height control response by changing the resonance frequency and the damping constant in the looper height control, and it is possible to control the looper at high speed and stably. become.

Although the present invention has been described based on the specific embodiments, these embodiments are not limited to being applied individually, but a plurality of embodiments can be used in combination. Further, in each of the above-described embodiments, the one in which the looper is driven by the looper electric motor has been described, but the present invention is not limited to this application and can be applied to a drive system using a hydraulic device.

[0056]

As is apparent from the above description, according to the present invention, when the acceleration / deceleration torque of the looper is set,
Since the auxiliary current reference proportional to the cross-sectional area of the rolled material was used,
It is possible to prevent an increase in tension in a small cross-sectional area, which was conspicuous in conventional PID control, and to eliminate the adverse effect on the plate thickness and the plate width due to overtension in the small cross-sectional area material.

According to another aspect of the invention, since the auxiliary current reference proportional to the looper angular velocity is used, the loop generated in the rolled material between the stands can be quickly removed, and stable operation can be performed. You can

Further, according to another invention, the acceleration / deceleration torque of the looper in the conventional PID control of the looper height can be compensated, and a constant current reference is always set so that the tension becomes larger than the target value. Things will disappear. As a result, it is possible to reduce the influence of over tension on the plate thickness and the plate width.

According to another aspect of the invention, the resonance frequency and the damping constant in the looper height control can be changed to increase the looper height control response, which enables high-speed and stable control of the looper. Become.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention, together with a rolling mill to be applied.

FIG. 2 is a diagram showing a geometrical relationship between a looper angle and a strip passing shape of a rolled material in order to explain the operation of the first embodiment of the present invention.

FIG. 3 is a block diagram showing a detailed configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a third embodiment of the present invention together with an applicable rolling mill.

FIG. 5 is a block diagram for explaining the principle of the third embodiment of the present invention.

FIG. 6 is a block diagram showing a detailed configuration of a third exemplary embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a fourth embodiment of the present invention together with an applicable rolling mill.

FIG. 8 is a block diagram for explaining the principle of the fourth embodiment of the present invention.

FIG. 9 is a block diagram showing a detailed configuration of a fourth embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of a control device of a conventional tandem hot rolling mill together with an applicable rolling mill.

[Explanation of symbols]

 1 Rolled material 2 i-th stand rolling mill 3 i + 1-th stand rolling machine 4 i-th stand rolling machine Main motor 5 i + 1st stand rolling machine Main motor 6 Main machine speed controller 7 Looper 8 Looper electric motor 9 Looper current controller 10 Looper height Detector 11 Looper height controller 12 Looper current reference generator 13 Main current reference generator 14 Auxiliary current reference generator 15 Fixed current reference generator 16 Tension detector 17 Tension calculation means 18 Tension component torque correction means 19 Tension generation gain Correction means

Claims (9)

[Claims] 1. A controller of a tandem hot rolling mill for controlling the height of a looper arranged between each stand of a tandem hot rolling mill and the rolling material tension between the stands, which is a stand rolling according to a speed set value. The main motor speed controller that controls the speed of the main motor and the main motor speed command value that causes the looper height detection value to follow the looper height target value are calculated, and the main motor speed controller is calculated by this speed command value. A looper height controller that corrects the applied speed setting value, and a looper that calculates the looper current command value that causes the tension of the rolled material to follow the tension target value based on the tension target value of the rolled material and the looper height detection value. A current reference generator, and a looper current controller for controlling the current of the looper motor according to the looper current command value, wherein the looper current reference generator is a torque that the looper receives from the rolled material, The main looper current reference that balances the torque received from the tension of the rolled material and the sum of the torque due to the weight of the looper itself is either one of the cross-sectional area of the rolled material, the rising speed of the looper and the change in the speed command value. Alternatively, the control device for the tandem hot rolling mill is to correct the auxiliary looper current reference obtained by considering a plurality of requirements. 2. A main current reference for the looper current reference generator to calculate a main looper current reference that balances the sum of the torque received by the looper from the rolled material, the torque received from the rolled material tension and the torque due to the weight of the looper. A generating means and an auxiliary current reference generating means for calculating an auxiliary looper current reference determined so as to be proportional to the sectional area of the rolled material are provided, and the main looper current reference and the auxiliary looper current reference are added. The controller of the tandem hot rolling mill according to claim 1, wherein the value obtained by the above is output as a looper current command value. 3. A main current reference for the looper current reference generator to calculate a main looper current reference that balances the sum of the torque received by the looper from the rolled material, the torque received from the rolled material tension and the torque due to the looper's own weight. Auxiliary current reference generating means for calculating an auxiliary looper current reference by adding the generating means and a value determined to be proportional to the cross-sectional area of the rolled material and a value determined to be proportional to the rising speed of the looper. The control device for a tandem hot rolling mill according to claim 1, further comprising: and outputting a value obtained by adding the main looper current reference and the auxiliary current reference as a looper current command value. 4. A main current reference for calculating the main looper current reference by which the looper current reference generator balances the sum of the torque received by the looper from the rolled material, the torque received from the rolled material tension and the torque due to the looper's own weight. Producing means, a value determined to be proportional to the cross-sectional area of the rolled material, a value determined to be proportional to the rising speed of the looper, and a change in the speed command value calculated by the looper height controller. And an auxiliary current reference generating means for calculating an auxiliary looper current reference by adding the value and a value obtained by adding the main looper current reference and the auxiliary looper current reference. The control device for the tandem hot rolling mill according to claim 1, which outputs the value as a value. 5. A main current reference for the looper current reference generator to calculate a main looper current reference that balances the sum of the torque received by the looper from the rolled material, the torque received from the rolled material tension and the torque due to the weight of the looper. The main looper current reference is provided with a generating means and an auxiliary current reference generating means for calculating a supplementary looper current reference by adding a fixed value and a value determined so as to be proportional to a rising speed of the looper. The control device for a tandem hot rolling mill according to claim 1, wherein a value obtained by adding the above and an auxiliary looper current reference is output as a looper current command value. 6. A main current reference for calculating the main looper current reference by which the looper current reference generator balances the sum of the torque received by the looper from the rolled material, the torque received from the rolled material tension and the torque due to the looper's own weight. The generating means, a fixed value, a value determined so as to be proportional to the speed at which the looper rises, and a value proportional to the change in the speed command value calculated by the looper height controller are added, and an auxiliary looper is added. The tandem according to claim 1, further comprising: an auxiliary current reference generating unit that calculates a current reference, and outputs a value obtained by adding the main looper current reference and the auxiliary looper current reference as a looper current command value. Control device for hot rolling mill. 7. A controller for a tandem hot rolling mill, which controls the height of a looper arranged between each stand of a tandem hot rolling mill and the tension of a rolled material between the stands, wherein the stand rolling is performed according to a speed set value. The main motor speed controller that controls the speed of the main motor and the main motor speed command value that causes the looper height detection value to follow the looper height target value are calculated, and the main motor speed controller is calculated by this speed command value. A looper height controller that corrects the applied speed setting value, and a looper that calculates the looper current command value that causes the tension of the rolled material to follow the tension target value based on the tension target value of the rolled material and the looper height detection value. The current reference generator, the looper current controller that controls the looper motor current according to the looper current command value, and the force received by the tension detector attached to the looper or the looper motor. Tension calculation means for calculating the tension of the rolled material from the torque, and tension component torque correction means for changing the resonance frequency and damping constant of the looper height control system based on the value obtained by multiplying the calculated tension by the gain And a tandem hot rolling mill control device. 8. The tension component torque correcting means subtracts a value obtained by multiplying the calculated tension by a gain from a looper current reference output from the looper current reference generator as a correction value for the looper current reference. At the same time, the control device for the tandem hot rolling mill according to claim 7, wherein the gain of the looper height controller that changes due to this subtraction is corrected to an appropriate value. 9. The tension component torque correction means adds a value obtained by multiplying the calculated tension by a gain to a speed command value output from the looper height controller as a change amount of a main machine speed command value. At the same time, the gain of the looper height controller that changes due to this addition is corrected to an appropriate value, and the control device for the tandem hot rolling mill according to claim 7.