JPH0857513A - Controller for rolling mill - Google Patents

Abstract

PURPOSE: To stably controll a looper and tension before and after changing travel by setting and calculating the index of robust stability so that looper control is most suitable for each rolling condition before, during and after changing travel. CONSTITUTION: A rolled stock 1 is rolled with stand rolling mills 2. The opening degree of screw-down is calculated with an automatic gage controller 3 and screw-down devices 4 are set. The speeds of main machines 5 are controlled with main machine speed controllers 6. The main machine speed command value and looper motor speed command value are calculated by looper controllers 12 so that looper angles become the target values and outputted to ASRs 6 for main machines and ASRs 9 for loopers. A control parameter setting means 13 has a A schedule 15 that is a rolling pass schedule before changing travel and B schedule 17 after changing travel. Both A- and B- schedules 15, 17 are covered with the index 16 of robust stability. Control parameters are calculated and the rolling mill is controlled by changing over the A- and B-schedules 15, 17 and index 16 of robust stability by the timing for changing travel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling mill controller for controlling the angle of loopers arranged between stands of a tandem rolling mill and the tension between stands of rolled material.

[0002]

2. Description of the Related Art Sheet thickness and sheet width are part of the evaluation criteria for final products in hot rolling and cold rolling. Of these, the automatic thickness control for the thickness (hereinafter AGC: Automatic Gauge Co
(abbreviated as ntrol) is performed, and automatic strip width control is performed for the strip width. On the other hand, the tension applied to the material being rolled affects the strip thickness and strip width, so tension control is also performed.

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

In such a rolled material tension and looper angle control device, there are interference from the rolled material tension to the looper angle and interference from the rotational speed of the looper to the tension. In the conventional tension control, a method of controlling the rolling material tension and looper angle by PID control without suppressing the interference and a rolling material tension by adding a decoupling compensator for suppressing these interferences The non-interference control method that controls the looper angle independently, and the interference system between the looper and the rolling material tension as a multivariable system, the optimal control theory (Linear Quadratic), H∞ control,
There is a method of applying the ILQ control, which is applied to each of the actual machines. Furthermore, the interference system between the stand outlet side plate thickness and the inter-stand tension is regarded as a multivariable system, and multivariable control of the plate thickness / tension to make it non-interfering (for example, Japanese Patent Laid-Open No. 6-526).
"Control device for continuous hot rolling mill" described in Japanese Patent Publication) is also applied.

Among the control theories applied to the control of the looper, the tension, and the plate thickness as described above, the H∞ control theory is a general one having the indexes of robust stability and disturbance suppression. Robust stability refers to the degree to which the entire control system including the controller is stable even when the controlled process changes for some reason or when there is a difference between the controlled process and its model. Generally, a control system with high robust stability is desirable. The H∞ control has an index of this robust stability and is characterized in that the controller can be designed in consideration of the robust stability. At the same time, it has an index of disturbance suppression, and the performance of the control system can be designed by the trade-off between robust stability and disturbance suppression.

On the other hand, the optimal control theory is a method of finding a control gain that minimizes the evaluation function J shown in the following equation (1).

[0007]

[Equation 1] u = −Kx (2) where x is the state quantity of the control target process, u is the operation quantity given to the control target process by the controller, x ^T is the transposition of x, and u ^T is the transposition of u. K is a control gain.

A specific design method is to determine the weighting matrices Q and R in the equation (1), but Q and R are numerical matrices, and it is difficult to find an index of robust stability in them. However, the disturbance suppression performance is generally obtained by setting Q and R in the direction in which the control gain increases. However, it is necessary to repeat many trials and errors to find Q and R.

The ILQ control theory is a control theory in which a direct response can be specified and the trial and error can be reduced by solving an inverse problem of the optimal control theory. Further, it is a feature that the Riccati equation does not have to be numerically solved and the control gain is represented by a mathematical expression including the specified response and the parameter of the process to be controlled. However, similar to the optimal control theory, there is no robust stability index, and the disturbance suppression index is obtained by increasing the control gain.

In addition, due to the necessity of coping with high-mix low-volume production, so-called running plate thickness change, running plate width change, running plate thickness, which changes plate thickness or plate width during rolling of one rolled material. -The board width will be changed (collectively these will be referred to as running distance changes). Further, there is so-called endless rolling in which a plurality of rolled materials are joined into one rolled material in order to prevent deterioration of the quality at the leading end of the rolled material and to enable the rolling of an extremely thin material. Even in endless rolling, the running distance may be changed before and after the joint.

[0011]

In the above-described running distance change, since the material thickness / width of the material before changing the running distance is different from the material thickness / width of the material after changing the running distance, before and after changing the running distance. It is necessary to change the control parameters for looper, tension, and plate thickness control. In this case, conventionally, the control parameter change timing must be changed in advance to the control parameter after the running time change during rolling of the material before the running time change, or the running time change can be done by changing the control parameter before the running time change. It was used and changed to the control parameters after the change of running distance after the change of running distance was completed. For this reason, when the plate thickness and plate width differ greatly before and after the change in running distance, and when different steel types are joined, the deformation resistance etc. before and after the welded part vary greatly, so a stable looper before and after changing the running distance,
It is not always possible to control the tension and the plate thickness.

Further, the technique of endless rolling in hot rolling is not an established technique yet, and there are various joining methods. A method in which the tail end of the material that has been rolled in advance (leading material) and the tip of the material to be rolled next (subsequent material) are butted against each other and heated, and are pressed against each other by an external force to join them. There is. In this case, the temperature of the bonded portion may become high, or the material temperature of the pressed portion may drop because a mechanism for pressing the material is required to apply an external force for pressing. If the strength of the joining part is insufficient, due to these temperature changes and the difference in deformation resistance before and after the joining part, excessive tension will be applied to the rolled material in the tandem rolling mill, leading to fracture of the joining part. There is also. Therefore, it is necessary to avoid applying excessive tension to the joint.

The present invention has been made in order to solve the above-mentioned problems, and when the looper / tension control of the tandem rolling mill is carried out before and after the change of running distance, or
An object of the present invention is to provide a rolling mill control device that enables optimum control in consideration of robust stability and disturbance suppression performance of a control system before and after running distance change when performing multi-variable tension control.

[0014]

A rolling mill control apparatus according to a first aspect of the present invention provides an angle of a looper arranged between stands of a tandem rolling mill and a rolling material tension between stands where the looper is arranged. When having a looper controller to control,
Before changing the running distance between the stands, set the control parameter of the looper control device that matches the rolling pass schedule before changing the running distance when changing the running distance when changing the strip thickness and / or the strip width during rolling. In addition, the robust stability index is set and calculated so as to be optimal for each rolling condition before, during, and after the change in running distance, and is specified. It is characterized in that it is provided with control parameter setting means for designating a control parameter of the looper control device that conforms to the schedule.

A rolling mill controller according to a second aspect of the present invention is a looper controller for controlling an angle of a looper arranged between stands of a tandem rolling mill and a rolled material tension between stands on which the looper is arranged. When rolling, when rolling a rolled material in which the trailing edge of the preceding material and the leading edge of the following material are rolled, according to the joining strength of the joining part, the joining part is not broken by the tension fluctuation caused by the disturbance before and after the joining part. A control parameter that decides whether to set the disturbance suppression index large or to set the robust stability index larger than the disturbance suppression index, and calculates the control parameter with the determined index to be the control parameter of the looper controller. It is characterized by having setting means.

A rolling mill controller according to a third aspect of the present invention includes a strip thickness tension control device for performing multi-variable control of rolling material tension between stands of a tandem rolling mill and stand stand-side strip thickness, and When changing the strip thickness and / or strip width during rolling, start the strip change between the stands with the control parameter of the strip thickness tension controller that matches the rolling pass schedule before the strip change. Before, the robust stability index is set and calculated so as to be optimal for each rolling condition before, during, and after the change in running distance, and the calculation is made. It is characterized in that it is provided with a control parameter setting means for designating a control parameter of the plate thickness tension control device suitable for the pass schedule.

A rolling mill controller according to a fourth aspect of the present invention is provided with a strip thickness tension control device for performing multi-variable control of a rolling material tension between stands of a tandem rolling mill and a stand outlet side strip thickness. When rolling a rolled material that joins the tail end and the trailing end of the trailing material, according to the joining strength of the joining part, a disturbance suppression index is set so that the joining part does not break due to tension fluctuations caused by disturbances before and after the joining part. Set it larger, or
Alternatively, it is provided with control parameter setting means for determining whether to set the robust stability index larger than the disturbance suppression index, and calculating the control parameter with the determined index to be the control parameter of the plate thickness tension control device. It has a feature.

According to a fifth aspect of the present invention, there is provided a rolling mill controller including a tension feedback controller for feedback-controlling the rolling material tension between the stands of the tandem rolling mill. When rolling the rolled material, the disturbance prediction means for estimating the change of rolling material speed based on the temperature change of the joint part and the change of the deformation resistance before and after the joint part, and the tension fluctuation by using the output of this disturbance prediction means And a tension feedforward controller that calculates an operation amount that suppresses the operation amount. The output of the tension feedforward controller is added to the output of the tension feedback controller to be the operation amount.

[0019]

In the rolling mill control device according to claim 1,
In the control parameter setting means, before the running distance change point enters between the stands, the rolling pass schedule before the running distance change, the rolling state when transitioning from before the running distance change to after the running distance change, and the after running distance change The control parameters are calculated by setting an index of robust stability that is optimal for the rolling pass schedule of the above, the control parameters of the looper control device are specified, and the running distance change points pass between the stands. After that, the control parameters of the looper control device that match the rolling pass schedule after the change in running time are designated.

In the rolling mill control apparatus according to the second aspect, when the rolled material in which the trailing end of the preceding material and the leading end of the following material are joined is rolled by the control parameter setting means, the joining strength of the joining portion is weak. In this case, the control parameter with the disturbance suppression index set to a large value is calculated, and the control parameter of the looper control device is specified, with the highest priority being that the joint portion is not broken due to the change in tension. When the joining strength of the joining part is strong, the robust stability index is set to be larger than the disturbance suppression index so that it is optimal for the rolling conditions before and after the joining part, and the control parameter is calculated to calculate the control parameter of the looper controller. Specify control parameters.

In the rolling mill control apparatus according to the present invention, the control parameter setting means sets the rolling pass schedule before the running distance change and the rolling distance schedule before the running distance change before the running distance change point enters between the stands. The control parameters are calculated by setting the index of robust stability that is optimal for the rolling state when transitioning after the change in running length and the rolling pass schedule after changing the running length, and Specify control parameters. After the running distance change point has passed between the stands, the control parameter of the plate thickness tension control device that matches the rolling pass schedule after the running distance change is specified.

In the rolling mill control apparatus according to the present invention, when the rolled material in which the trailing end of the preceding material and the leading end of the following material are joined is rolled by the control parameter setting means, the joining strength of the joining portion is weak. In this case, it is given top priority that the joint portion does not break due to tension fluctuations, and the control parameter with the disturbance suppression index set to a large value is calculated to specify the control parameter of the plate thickness tension control device. When the joint strength at the joint is strong, the robust stability index is set to be larger than the disturbance suppression index so that it is optimal for the rolling conditions before and after the joint, and the control parameters are calculated to control the plate thickness tension. Specify the control parameters of the device.

In the rolling mill control apparatus according to the fifth aspect, when joining the tail end of the preceding material and the tip of the following material, the disturbance predicting means joins the temperature change around the joint and the different steel type. In order to suppress the tension fluctuation caused by the change of deformation resistance before and after the joining part, the change of rolling material speed is estimated from the change of temperature and the change of deformation resistance. The tension feedforward controller uses the disturbance predicted by the disturbance predicting means to calculate a manipulated variable that suppresses tension fluctuation, and adds the calculated value to the output of the tension feedback controller as the manipulated variable.

[0024]

The present invention will be described in detail below with reference to the illustrated embodiments. FIG. 1 is a block diagram showing the configuration of an embodiment corresponding to the rolling mill control device according to the first aspect. In FIG. 1, the rolled material 1 is rolled in the order of the first stand rolling mill 2a to the seventh stand rolling mill 2g. Here, the total number of stands of the tandem rolling mill is 7, but 4 to 7 stands are general. Further, in the following description, since each stand or each stand has the same configuration, for example, reference numerals 2a, 2b, ..., 2g added to the rolling mill are used.
Is simply referred to as 2, and reference numerals na, nb, ..., ng added to elements other than the rolling mill are simply referred to as n.

The plate thickness is calculated by the automatic plate thickness controller (AGC) 3 and the reduction opening is calculated and set in the reduction device 4. The rolling rolls are driven by a rolling mill driving electric motor (hereinafter referred to as a main machine) 5, and the speed control of the main machine 5 is performed by a main machine speed control device 6 (main machine ASR). A looper 7 is provided between the rolling mill stands, the tension of the rolled material received by the looper roll is detected by a tensiometer 11, and the angle of the looper arm (referred to as a looper angle) is detected by a looper goniometer 10. The speed of the looper electric motor 8 that drives this looper is
It is controlled by a looper electric motor speed control device 9 (referred to as a looper ASR). The main motor, the speed detector of the looper motor, and the current control system are omitted.

In the looper controller 12, the deviation between the detected value by the tension meter 11 and the given tension target value is made small, and the deviation between the looper goniometer 10 and the given looper angle target value is made small. As described above, the main engine speed command value and the looper motor speed command value are calculated, and the main engine ASR is calculated respectively.
6 and the looper ASR9.

The control parameter setting means 13 includes a control parameter designating section 14, a rolling pass schedule before changing the running distance (referred to as A schedule) 15, and a rolling pass schedule after changing running distance (referred to as B schedule) 17. have. Schedules A and B shall be given in advance. Furthermore, it has a robust stability index 16 that covers both A and B schedules, and depending on the timing of the change in running time, A schedule 15, robust stability index 16,
The control parameters are calculated by switching the B schedule 17, and the respective control parameters are used.

A concrete method of realizing the looper control device 12 and the control parameter setting means 13 will be described below. First, the control method used for the looper control device 12 is the conventional P
I control, non-interference control, optimum control, H∞ control, ILQ control, etc. are applied. The H∞ control has a clear index of robust stability and disturbance suppression, but the other controls do not have a clear index of robust stability. However, the index of disturbance suppression and the index of robust stability are almost determined by the trade-off (when one is increased, the other is decreased), and H∞
It is possible to have a rough index by a method other than control. However, for convenience of explanation, the H ∞ control is used here for the looper control device 1.
Consider as applied to 2.

FIG. 2 is a block diagram of a process model and a controller to be controlled of the looper angle and tension between any two consecutive stands. Note that in FIG. 2, a symbol is added before each symbol, and since the linear model is shown in FIG. 2, the variable is displayed by the change amount of the symbol. Target tension value Δ
The H∞ controller 18 controls the roll peripheral speed change amount command value ΔV so as to reduce the deviation e _t between the t _fref and the detected tension value Δt _f.
By operating _RREF , the H ∞ controller 19 operates the looper motor speed command value ω _LREF . Looper angle target value [Delta] [theta] _{re f} and looper angle detection value H to the deviation e _h to reduce the [Delta] [theta]
The ∞ controller 20 operates the roll peripheral speed change amount command value ΔV _RREF , and the H∞ controller 21 controls the looper motor speed command value ω.
_{Operate LREF} .

In FIG. 2, 22 to 34 are controlled processes, which correspond to the elements denoted by reference numerals 1, 2, 5 and 9 in FIG. Of these, 22 is a main engine speed control system, and represents the speed control system composed of the main engine 5 and the main engine ASR 6 in FIG. 1 as one block. Two
3 is an influence coefficient block (f is an advanced rate) from the main machine speed to the rolling material speed, 24 is a tension generation gain and an integrator in the tension generation process, 25 is a feedback gain of the tension generation process, and the tension is calculated in blocks 24 and 25. The generation mechanism is modeled.

Reference numeral 26 is an influence coefficient from the looper electric motor speed to the rolled material speed, and 27 is an influence coefficient from tension to the looper electric motor torque. 28 is the gain from the looper angle to the looper motor torque, 31 is the looper motor torque constant,
Reference numeral 32 is a transfer function from torque to rotation speed in the looper motor, 33 is a transfer function from rotation speed of the looper motor to looper angle, and 34 is a looper damping coefficient. Two
Reference numeral 9 denotes a looper speed controller, which is the looper ASR9 in FIG.
Equivalent to. Further, reference numeral 30 is a block showing a looper current control system, but since the response is generally very fast as compared with the speed control, the block 30 has a gain of 1 and does not need to consider the dynamic characteristics. Blocks 28-3 of FIG.
Reference numeral 4 corresponds to the looper electric motor 8 and the looper ASR in FIG.

The meanings of the variables in FIG. 2 are summarized below. t _f: forward tension theta: looper angle g _L: gear ratio between the looper and the looper motor J: looper motor inertia efficiency K _10: tension feedback coefficient E: Young's modulus of the strip L: Stand distance V _R: main engine Speed Z: Looper damping coefficient f: Advanced rate φ: Looper motor torque constant ω _L : Looper rotation speed T _v : Main machine speed control system time constant F ₁ : Gain from looper angle to looper torque (load by material weight / looper's own weight) Torque) F ₂ : coefficient of influence from looper rotation speed to rolling material speed F ₃ : coefficient of influence from tension to looper motor torque Subscript REF: command value of the symbol.

The blocks 35 to 38 in FIG.
This is a weighting function used in control design, and the H ∞ control will be briefly described below. In the H∞ control, a weighting function W for defining a transfer function from the target tension value Δt _fref to the control deviation e _t (this is called a tension system sensitivity function).
₁₁ (35), control deviation e from the looper angle target value Δθ _ref
A weighting function W ₁₂ (36) for defining the transfer function up to _h (this is called the sensitivity function of the looper angle system), the transfer function from the desired tension value Δt _fref to the tension Δt _f (this is the complementary sensitivity of the tension system). Function W) for defining
₂₁ (37), Design a weighting function W ₂₂ (38) for defining the transfer function from the looper angle target value Δθ _ref to the looper angle Δθ (this is called the complementary sensitivity function of the looper angle system). In the design by the H ∞ control, the weighting function is designed so that the responses of the respective sensitivity functions and the complementary sensitivity function become desired responses, and the controller G _c11 that satisfies the weight function is designed.
The purpose is to find G _c21 , G _c12 , G _c22 (blocks 18-21).

The form of the H∞ controller can be realized by two configuration methods, that is, a configuration by output feedback as shown in FIG. 2 and a configuration by state feedback for detecting and feeding back the state of the process to be controlled. Here, the configuration based on state feedback is omitted.

FIG. 3 shows an example of how to determine the weighting function in the looper multivariable system in FIG. FIG. 3A shows the inverse function W of the weighting function W ₁₁ for defining the sensitivity function of the tension system.
₁₁ ⁻¹ and the inverse function W ₂₁ ⁻¹ of the weighting function W ₂₁ for defining the complementary sensitivity function of the tension system, and the closed loop transfer function including the H ∞ controller designed by them are shown. The closed loop transfer function indicates a transfer function G _T1 from the target tension value to the tension and a transfer function G _H2 from the target tension value to the looper angle. FIG.
Inverse function of the weighting function W ₂₂ to the (b) is to define the complementary sensitivity function of inverse function W ₁₂ ^-1 and looper angle based weighting function W ₁₂ to define the sensitivity function of the looper angle system W ₂₂ ^{- 1} and the closed loop transfer function including the H∞ controller designed by them are shown. The closed loop transfer function indicates a transfer function G _H1 from the looper angle target value to the looper angle and a transfer function G _T2 from the looper angle target value to the tension.

As shown in FIG. 3, generally, the sensitivity function sets each gain function so that the gain is small in the low frequency region, and the complementary sensitivity function sets each weight function so that the gain is small in the high frequency region. The reason for this is as described below. A. There is a constraint that (sensitivity function) + (complementary sensitivity function) = 1, and it cannot be reduced based on the sensitivity function and the complementary sensitivity function over all frequency regions. B. In general, the sensitivity function mainly relates to the quick response of the control system. C. The complementary sensitivity function is mainly related to the robust stability of the control system.

In order to achieve the purpose of B, the gain of the sensitivity function should be made small over the entire frequency band, and in order to achieve the purpose of C, the gain of the complementary sensitivity function should be made small over the entire frequency band. Obviously, that's fine. However, since A is a constraint condition, this 2
It is impossible to fill one over the entire frequency band at the same time. Therefore, the control amount is made to follow the target value only in the low frequency region, and therefore the gain of the sensitivity function is made small in the low frequency region. Further, from the viewpoint of noise resistance and the like, the gain from the target value to the control amount is reduced in the high frequency region, and the gain of the complementary sensitivity function is reduced in the high frequency region in order to improve robust stability.

As described above, the sensitivity function and the complementary sensitivity function are the responses of the closed loop system after setting the weighting function and designing the controller, and the sensitivity function and the complementary sensitivity function related to the tension control are the weighting function W ₁₁ , W ₂₁ , and the sensitivity function and complementary sensitivity function related to looper angle control are determined by the weighting functions W ₁₂ , W ₂₂ .

Further, the index of the quick response is the frequency at which the sensitivity function is in the vicinity of -3db, and in FIG. 3, the response of the tension control is approximately 5 rad / s in terms of the crossing angular frequency. The robust stability index is the gain difference between the complementary sensitivity function and the reciprocal of the weighting function, and the robust stability index of the tension control system in FIG. 3 is the difference between W ₂₁ ⁻¹ and GT _{1 of} about 20 to 40 d.
b. This means that the stability is maintained even if there is an error between the actual process and the model of about 20 to 40 db (= 10 to 20 times).

A large design of robust stability is
This means that the control system is stable even if the process to be controlled changes over a wide range, and one controller gain can handle a wide range of rolling conditions. Therefore, A schedule 15 and B schedule 1 in FIG.
By setting the robust stability index 16 that covers 7 and 7, it is possible to stably control before, during, and after running distance change with one control parameter.

FIG. 4 is a block diagram showing the configuration of a conventional device corresponding to FIG. 1 shown for reference. The control parameter setting means 13a switches and uses only the control parameters for the A schedule before the change of the running time and the control parameters for the B schedule after the change.

FIG. 5 shows selection of control parameters for the A and B schedules and the robust stability index. FIG. 5 (a)
Is a control parameter switching method according to the present embodiment. The horizontal axis shows the movement of the position of the running distance change point, and
In terms of points, the control parameter for A schedule is not used, the control parameter based on the robust stability index is used, and B is used.
The control parameter for schedule represents that it is not used. In FIG. 5A, the control parameter for the A schedule is changed to the control parameter based on the robust stability index before the running distance change point enters the i stand, and the running distance change point is i +.
After passing through one stand, the control parameters are changed to the B schedule. By doing so, stable control becomes possible before and after the running distance change point passes between the i to i + 1 stands.

FIGS. 5 (b) and 5 (c) show a conventional switching method. In FIG. 5 (b), the control parameter for A schedule is changed to the control parameter for B schedule before the change point during running enters the i stand. FIG. 5C is a method of changing the control parameter for A schedule to the control parameter for B schedule after the running distance change point passes through the i + 1 stand. In the method of FIG. 5A, a part of the material before the running time change and the rolling during the running time change are schedules after the running time change B
The control is performed according to the schedule, and the control precision during the control becomes poor and the stability is not guaranteed. Further, in the method of FIG. 5C, a part of the material after the running distance change and the rolling during the running distance change are controlled by the A schedule which is the schedule before the running distance change, resulting in deterioration of control accuracy and stability. Sex is not guaranteed.

As is clear from the above description, according to the rolling mill control apparatus shown in FIG. 1, it is possible to set the control parameters of the looper control apparatus which are not affected by the change in the rolling pass schedule before and after the change in running distance. Stable control is possible before and after changing the running distance.

FIG. 6 is a block diagram showing the configuration of an embodiment corresponding to the rolling mill control device according to the second aspect. Elements denoted by reference numerals 1 to 11 in FIG. 6 are the same elements as those shown in FIG. Further, although the control parameter setting means 39 (including 14, 40, 41) is shown to be provided only between the third stand and the fourth stand, similar means may be provided between the other stands. However, their description is omitted for simplification of the drawings.

When rolling a rolled material having a joined portion with a tandem rolling mill, the most important issue is to roll the joined portion without breaking it. A major cause of the fracture of the joined portion is that the joined portion is weaker in tensile force than other portions and excessive tension is applied during rolling. Rolling without applying an excessive tension is easy because the applied disturbance is relatively small in the steady portion other than the joined portion. However, the joining portion includes a rolled material portion heated for joining and a rolled material portion where the temperature is lowered by pressing the leading material and the trailing material with external force for joining. In addition, when different steel types are joined, the rolling resistance changes drastically at the joint because the deformation resistance is different. Further, when the target plate thickness and the plate width of the preceding material and the following material are different, the running distance is changed around the joining portion or before and after the joining portion, and the roll gap opening degree is rapidly changed. Therefore, the disturbance applied to the tension control system is very large.

Further, in the former stand of tandem rolling, since the time elapsed after joining is small and the effect of water cooling between stands is less likely to appear, the joining portion may be easily broken. On the other hand, in many cases, the temperature gradient in the temperature changing portion between the rear stands is gentle.
When joining the same steel type, there is less disturbance than when joining different steel types. Therefore, whether to give priority to suppressing the disturbance and not breaking the joint or to give priority to the stability of control depends on the rolling conditions, the joining conditions, and the stands.

As shown in FIG. 6, the control parameter setting means 39 determines which one of the disturbance suppression and the robust stability should be prioritized, depending on the rolling condition, the joining condition, and the distance between the stands, and one of the indexes is designated as the control parameter. The control parameter designation unit 14 supplies the control parameter to the looper control device 12.

Since the method of giving the robust stability index has already been described, the method of giving the disturbance suppression index will be described here.
The disturbance suppression index is clearly given by H ∞ control, and PI
Control, non-interference control, optimum control, ILQ control, etc. can also be achieved by designing with high speed response. Here, the H ∞ control will be described.

In FIG. 3, in order to increase the disturbance suppression characteristic, the weighting functions W ₁₁ ^-1 and W ₁₂ ^-1 are set so as to reduce the sensitivity function. As described above, the sensitivity function is a transfer function from the target value to the control deviation, and if the gain of this sensitivity function is made smaller, the control deviation becomes smaller, that is, the tension or looper angle, which is the control amount, does not easily deviate from the target value. Is meant to be. The weighting function W ₁₁ ^-1 to reduce the sensitivity function, W ₁₂ ^-1 may or transferred point to separate the weighting function and 0db lines to high-frequency range can be achieved by a steep slope the weight function in the low frequency range .

Thus, according to the embodiment shown in FIG.
The control parameters of the looper control device can be set according to the rolling conditions, joining conditions, and stand conditions, and stable and highly accurate control of the looper height and tension before and after the joining portion can be performed.

FIG. 7 is a block diagram showing the configuration of an embodiment corresponding to the rolling mill control apparatus according to the third aspect. Elements denoted by reference numerals 1, 2 and 4 to 11 in FIG. 7 are the same as elements denoted by the same reference numerals in FIG.

In this embodiment, in order to control the plate thickness and the tension, the process of the plate thickness and the tension with mutual interference is regarded as a multivariable system, and the multivariable control is applied. Multi-variable control of plate thickness and tension is performed. In this case, the position of the looper is controlled by the looper position control device 42 in order to use the tensiometer 11 attached to the looper. A load cell is generally used as the rolling load detector 44. By taking in the roll gap opening setting value (S) in addition to the rolling load (P), the plate thickness of each stand can be obtained from the gauge meter formula (3). h = S + P / M (3) where, h: delivery side plate thickness, M: mill constant

FIG. 8 is different from FIG. 7 in the method of detecting the stand-out side plate thickness. In FIG. 8, the measurement value by the plate thickness gauge 50 installed between the stands is delayed by the delay means 51 until it reaches the nearest stand on the downstream side,
Stand stand-out plate thickness h according to the mass flow constant of equation (4)
Is to detect. H · V · B = h · v · b (4) where, H: incoming plate thickness, V: incoming material speed, B: incoming width, v: outgoing material speed, b: outgoing width

The method shown in FIGS. 7 and 8 is used separately for each stand. For example, the method shown in FIG. 8 can be used for a stand with a plate thickness gauge, and the method shown in FIG. 7 can be used for a stand without a sheet gauge. .

FIG. 9 shows a block diagram of multi-variable control of plate thickness and tension. Blocks 52 to 55 are integral controllers, 5
Reference numerals 6 to 59 are state feedback controllers. Blocks 60 to 63 and 22 to 25 indicate control target processes. Block 60 represents the response of the reduction device,
Block 61 is an influence coefficient from the roll gap opening to the delivery side plate thickness, 62 is an influence coefficient from the roll gap opening to the material speed, and 63 is an influence coefficient from the tension to the delivery side plate thickness. Blocks 22-25 are the same as in FIG.

The controllers 52 to 59 shown in FIG.
It can be designed using a multivariable control theory such as optimal control, H ∞ control, ILQ control and the like. Further, although the configuration of the state feedback is shown in FIG. 9, the configuration of the output feedback as shown in FIG. 2 is also possible. When changing the running distance, the plate thickness may be changed significantly, which causes disturbance to the tension. However, by treating the plate thickness and the tension as a multivariable system, there is an advantage that the plate thickness and the tension can be well controlled. .

Here, a control parameter setting means 45 having the same configuration as that of FIG. 1 is provided. That is, by designing the robust stability in the plate thickness tension control device 43 to be large, if the robust stability index 48 that covers the A schedule 47 and the B schedule 49 in FIG. , It is possible to stably control after the change with one control parameter.

The conventional apparatus has a configuration without the block 48 in FIG. 7, and uses only the control parameters for the A schedule before the change of the running time and the control parameters for the B schedule after the change by switching.

However, in the embodiment shown in FIGS. 7 and 8, the control parameters for the A and B schedules and the robust stability index are selected as described with reference to FIG. That is, in FIG. 5A, the control parameter for the A schedule is changed to the control parameter based on the robust stability index before the change point for running time enters the i stand, and the control for B schedule is performed after the change point for running time passes the i + 1 stand. Change to parameter. By doing this, i ~ i + 1
Stable control is possible before and after the running point changes between the stands.

FIG. 10 is a block diagram showing the configuration of an embodiment corresponding to the rolling mill control device according to the fourth aspect. FIG.
Elements denoted by reference numerals 1, 2, 4 to 11, 42, 43 at 0 are the same as those denoted by the same reference numerals in FIG. In FIG. 10, the gauge thickness method is used to detect the plate thickness. FIG. 11 shows a method of detecting the plate thickness using a plate thickness gauge. Reference numbers 1, 2, 4 to 1 in FIG.
Elements denoted by 1, 42, 43, 50 and 51 are the same as the elements denoted by the same reference numerals in FIG.

When a rolled material having a joined portion is rolled by a tandem rolling mill, it is a problem to roll the joined portion without breaking it. However, the temperature change of the joined portion and the joining of different steel types also cause the variation of the sheet thickness. This will lead to tension fluctuations. Therefore, by controlling the plate thickness and the tension in multiple variables and designing the disturbance suppression performance to be large, it is possible to prevent the overtension from being applied to the joint portion and prevent the breakage.

Similar to the embodiment shown in FIG. 7 or FIG. 8, whether the robust stability or the disturbance suppression performance is prioritized depends on the rolling condition, the joining condition and the stand. Shall be selected according to.

FIG. 12 is a block diagram showing the configuration of an embodiment corresponding to the rolling mill control apparatus according to the fifth aspect, and blocks 22 to 25 are the same as those shown in FIG.
The other block 68 is a tension feedback type controller, and the PID control, the tension control part of the non-interference control, the optimum control, the ILQ control, the H ∞ control and the like can be applied.

The block 69 is based on the temperature disturbance ΔT at the joint, the deformation resistance difference Δk due to the joining of different steel types, and the material speed change Δ.
It is a disturbance process that represents the effect on V _d . The disturbance predicting means 70 calculates the predicted value ΔV _d ^* of the material velocity change ΔV _d by using the predicted value ΔT ^* of the temperature disturbance ΔT and the predicted value Δk ^* of the difference Δk of the deformation resistance due to the joining of different steel types. The concrete calculation of ΔV _d ^* is based on the following formula.

[0066]

[Equation 2] ΔT ^* : Change in temperature of joint Δk ^* : Change in deformation resistance of joint (using set calculation value) The amount of temperature change in the joint can be estimated to some extent by the heating time for joining. However, in reality, the details of the temperature change are unknown, so assuming the conditions at the joint, predicting the temperature change, and considering that the temperature gradient changes over time, a function in the longitudinal direction of the material is considered. The function type, function parameters, etc. are stored in a table, etc., and the table is picked up from the table when used.

The coefficient of influence from the change of the deformation resistance to the material speed is related to the plate thickness control, and it is difficult to obtain a clear value, but a gain table is created under various conditions and the gain is calculated by analyzing the actual machine data. decide.

The tension feedforward controller 71 calculates an operation amount of the main machine speed that compensates the material speed change ΔV _d ^* predicted by the disturbance predicting means 70. The tension feedforward controller 71 is a controller having a dynamic characteristic that compensates for a simple control gain or a response delay of the main machine speed control system.

Therefore, according to the embodiment shown in FIG. 12, it is possible to control the tension variation before and after the joining portion due to the temperature variation of the joining portion and the variation of the deformation resistance due to the joining of different steel types. , It becomes possible to control the plate thickness and tension with high accuracy before and after the joint.

In each of the above embodiments, the double rolling mill is the rolling mill to be controlled, but this rolling mill is a quadruple rolling mill,
The present invention can be similarly applied to other rolling mills such as a six-fold rolling mill.

Although the looper drive system has been described using the electric motor, it can be applied to other drive systems such as a hydraulic drive system.

[0072]

According to the rolling mill control apparatus of the first aspect, it becomes possible to set the control parameters of the looper control apparatus which are not affected by the change in the rolling pass schedule before and after the change of the running distance, and before and after the change of the running distance. It enables stable looper and tension control.

According to the rolling mill controller of the second aspect, control of the looper controller according to the rolling condition, the joining condition, and the stand condition before and after the joining portion (the running distance changing portion may be included). Parameters can be set,
It is possible to control the looper and tension with stability and high accuracy before and after the joint.

According to the rolling mill control apparatus of the third aspect, it becomes possible to set the control parameters of the multi-variable control apparatus for strip thickness and tension which is not affected by the change in the rolling pass schedule before and after the change of the running distance. It enables stable control of plate thickness and tension before and after change.

According to the control device for a rolling mill described in claim 4, the plate thickness and the tension depending on the rolling condition, the joining condition and the stand condition are provided before and after the joining part (the running distance change part may be included). It becomes possible to set the control parameters of the multivariable control device, and it becomes possible to control the plate thickness and tension in a stable and highly accurate manner before and after the joining portion.

According to the rolling mill control device of the fifth aspect, it is possible to perform the tension control before and after the joining portion, which can suppress the tension variation due to the temperature change of the joining portion and the deformation resistance change due to the joining of different steel types. Therefore, stable and highly accurate tension control can be performed before and after the joint.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment corresponding to a rolling mill control device according to claim 1.

FIG. 2 is a block diagram showing a detailed configuration of the embodiment shown in FIG.

FIG. 3 is a Bode diagram for explaining the method of determining the weighting function of the embodiment shown in FIG.

FIG. 4 is a block diagram showing a configuration of a conventional rolling mill control device shown for reference, for comparison with the embodiment shown in FIG. 1.

5 is a time chart showing the operation of the embodiment shown in FIG. 1 together with the operation of the conventional apparatus shown in FIG.

FIG. 6 is a block diagram showing a schematic configuration of an embodiment corresponding to the rolling mill control device according to claim 2;

FIG. 7 is a block diagram showing a schematic configuration of an embodiment corresponding to the rolling mill control device according to claim 3;

FIG. 8 is a block diagram showing a schematic configuration of another embodiment corresponding to the rolling mill control device according to claim 3;

9 is a block diagram showing a detailed configuration of the embodiment shown in FIG. 7 or FIG.

FIG. 10 is a block diagram showing a schematic configuration of an embodiment corresponding to the rolling mill control device according to claim 4;

FIG. 11 is a block diagram showing a schematic configuration of another embodiment corresponding to the rolling mill control device according to claim 4;

FIG. 12 is a block diagram showing a schematic configuration of an embodiment corresponding to the rolling mill control device according to claim 5;

[Explanation of symbols]

 2 Rolling mill 3 Automatic plate thickness control device 4 Rolling down device 5 Rolling mill driving electric motor 6 Main machine speed control device 7 Looper 8 Looper electric motor 9 Looper electric motor speed control device 10 Looper angle meter 11 Tension meter 12 Looper control device 13, 39, 45 , 64 control parameter setting means 14, 46, 65 control parameter designation section 15, 47 A schedule 16, 40, 48, 66 robust stability index 17, 49 B schedule 41, 67 disturbance suppression index 68 tension feedback controller 69 disturbance process 70 Disturbance predicting means 71 Tension feedforward controller

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B21B 37/50 G05B 13/02 T 7531-3H B21B 37/00 BBP 8315-4E 130

Claims (5)

[Claims] 1. A rolling mill controller having a looper controller for controlling an angle of a looper arranged between stands of a tandem rolling mill and a rolled material tension between stands on which the looper is arranged. At the time of changing the running distance for changing the rolled material plate thickness and / or the plate width, the control parameter of the looper control device that matches the rolling pass schedule before the changing of the running time is set before starting the running time change between the stands, Robust stability index is set and calculated so as to be optimal for each rolling condition before, during, and after the running change, and after the running change, the rolling pass schedule after the running change is specified. A rolling mill control device comprising control parameter setting means for designating a control parameter of the suitable looper control device. 2. A rolling mill controller having a looper controller for controlling an angle of a looper arranged between stands of a tandem rolling mill and a tension of a rolled material between stands on which the looper is arranged. When rolling a rolled material in which the end and the trailing edge of the trailing material are joined, a large disturbance suppression index is set according to the joining strength of the joining portion so that the joining portion does not break due to tension fluctuations caused by disturbances before and after the joining portion. Control parameter setting means for determining whether to set the robust stability index larger than the disturbance suppression index and calculating the control parameter with the determined index to be the control parameter of the looper control device. A rolling mill control device characterized by the above. 3. A rolling mill controller having a strip tension controller for performing multi-variable control of rolled strip tension between stands of each tandem rolling mill and strip stand-out strip thickness in a rolling mill controller during rolling. And / or when changing the running width to change the board width,
The control parameters of the plate thickness tension control device conforming to the rolling pass schedule before changing the running distance, before starting the changing of the running distance between the stands, each rolling condition before changing the running distance, during the changing, and after the changing A control that sets and calculates an index of robust stability so that it becomes optimal for the specified value, and specifies the control parameter of the strip tension controller that conforms to the rolling pass schedule after the change in running distance after the change in running distance. A rolling mill control device comprising a parameter setting means. 4. A rolling mill controller having a strip tension controller for performing multi-variable control of rolled strip tension between stands of each tandem rolling mill and strip stand side strip thickness, in a rolling mill controller, a trailing edge of a preceding strip and a trailing strip of strip. When rolling a rolled material that is joined to the material tip, depending on the joining strength of the joining portion, set a large disturbance suppression index so that the joining portion does not break due to tension fluctuations caused by disturbances before and after the joining portion, or It is provided with a control parameter setting means for determining whether to set the robust stability index larger than the disturbance suppression index, and calculating the control parameter with the determined index to be the control parameter of the plate thickness tension control device. Characteristic rolling mill control device. 5. A rolling mill control device having a tension feedback controller for feedback-controlling the rolling material tension between each stand of a tandem rolling mill, in which a rolling material in which a leading end of a preceding material and a leading end of a following material are joined is rolled. In this case, the disturbance predicting means for estimating the change of the rolling material speed based on the temperature change of the joint part and the change of the deformation resistance before and after the joint part, and the operation amount for suppressing the tension fluctuation by using the output of the disturbance predicting means. And a tension feedforward controller for calculating, and the output of the tension feedforward controller is added to the output of the tension feedback controller to be a manipulated variable.