JPH06297017A - Controller for meander of rolled stock in continuous mill - Google Patents

Abstract

PURPOSE:To obtain a meander controller to adjust meander controlling response and meander controlling capacity in consideration of parameter fluctuation of a meander process under rolling. CONSTITUTION:This is a controller for meander of a rolled stock in a continuous mill provided with plural rolling stands containing rolling rolls 3, 3' and rolling-down devices 5, 7 for the rolling roll having a leveling means. It is furnished with a detecting device 21 for the meander of the rolled stock, an automatic identifying device 23 to identify on-line a process model of ever-changing meander detected by the detecting device 21 and an arithmetic unit 25 for leveling quantity to calculate the leveling quantity for controlling the meander in accordance with the process model identified by the identifying device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a meandering control device for rolled material in a continuous strip rolling mill for metal strips represented by a hot strip rolling mill, a cold strip rolling mill, and the like.

[0002]

2. Description of the Related Art In a rolling operation, depending on the conditions during rolling, the rolled material cannot stay in the center of the roll and moves toward the end of the roll as the rolling progresses as shown in FIG. The phenomenon is well known and this phenomenon is called meandering.

Here, the meandering of the rolled material will be briefly described. FIG. 5 shows a state in which the rolled material 32 deviates from the center of the work roll 34 to the right side for some reason. The rolling force is unbalanced left and right,
The roll gap is wider on the right side than on the left side. By the way, although the peripheral speed of the work roll 34 is uniform on the left and right, the gap on the right side is wider, so that the volume flow rate of the rolled material 32 per unit time is larger on the right side. Further, if the thickness of the rolled material 32 on the inlet side is symmetrical, the rolled material 32 will be drawn in earlier on the side of the larger volume flow rate. As a result, the rolled material 32 moves toward the right side, the left and right difference of the roll gap is promoted, and the rolling material 32 approaches the right end more rapidly, causing a phenomenon of meandering.

This meandering phenomenon is likely to occur when the tail end of the steel strip passes through the rolling mill (when the tail end slips out), and causes operational troubles called "plate drawing" and "raising." When such a trouble occurs, the rolls may be damaged, peripheral equipment may be damaged, or the yield of the rolled material may be reduced. In order to prevent these adverse effects and perform a stable rolling operation, meandering control of the rolled material is essential.

Generally, a method of controlling meandering is to reduce the rolling reduction of the side of the rolled material that is meandered (the center of the rolled material moves in the longitudinal direction) and
This is a method of increasing (rolling) the roll pressure on the opposite side. By doing so, the volume of the rolled material drawn into the rolling roll is balanced left and right, and it is possible to prevent a harmful moment from being applied to the tail end of the pressure material.

As a typical example of conventional meandering control by the leveling method, the meandering detection amount of a plate meandering detector arranged between rolling stands is compared with the rolling position difference of the downstream stand (leveling amount: working side rolling position and driving side pressure). 3-60564, 3-7524
There was a device disclosed in 2. This device is equipped with a meandering detector on the entrance side of the rolling stand to suppress and control the meandering between the rolling stands and the stands. The meandering is prevented by operating the leveling amount of the downstream stand. The invention of these devices is
The feature is that the meandering detection amount is directly fed back to be input to a controller mainly composed of a differential amplifier, and the leveling operation amount is output.

As another method, the meandering amount and the wedge amount (difference in thickness in the width direction of the rolled material) are obtained from the rolling load signal, and a certain theoretical model is set to optimize the leveling amount of the rolling mill. Has also been proposed (Japanese Patent Laid-Open No. 3-57507). According to this method, a certain control accuracy can be obtained within the range of the accuracy of assembling the model formula and the coefficient (a value theoretically multiplying the numerical value related to measurement as a constant) used therein. However, if the effects that are not expressed in the model formula itself are highly effective, if there is a change in the constant and the coefficient, or if there is an increase in the error in the intermediate measurement value (wedge amount), the accuracy of the model collapses, There is a drawback that accurate control cannot be performed.

[0008]

In the conventional meandering control device, no consideration is given to environmental fluctuations during rolling, that is, fluctuations in the meandering process caused by changes in rolling load / temperature, changes in rolling speed, etc. The gain of the controller for meandering control must be set lower than the maximum gain that can stably correct the meandering. for that reason,
The correction response of the conventional meandering control is not only affected by changes in the rolling environment, but also has a problem that sufficient quick response cannot be obtained.

The present invention has been made to solve the above problems, and takes into consideration the parameter fluctuation of the meandering process during rolling, and takes into consideration the meandering control response and the meandering control capability of the prior art. Aim to get.

[0010]

Means for Solving the Problems The problems described above include a rolling roll and a rolling roll reduction device having leveling means,
A rolling material meandering control device in a continuous rolling mill consisting of a plurality of rolling stands, comprising a rolling material meandering detection device provided between rolling stands, and a process of meandering that changes momentarily detected by the detection device. A rolling material meandering controller for a continuous rolling mill equipped with an automatic identification device for online identification of a model and a leveling amount calculation device for calculating a leveling amount for meandering control based on the process model identified by the identification device. Can be resolved.

[0011]

[Operation] The control effect of meandering appears immediately on the mill entry side. While controlling the leveling amount, the meandering amount (positional difference between the center of the mill and the width center of the material to be rolled) is measured by a meandering detection device on the mill entrance side. Many parameters are present between the leveling amount and the meandering amount, but the current values of these parameters can be optimized by analyzing the actual values of the past several times according to the degrees of freedom of the operation amount and control amount. To estimate, ie, meandering process models can be identified online. Based on the current model obtained by this estimation parameter,
The leveling amount for the next time (for example, after 10 ms) is controlled. This control result is used again as the data for performance analysis.
This effect is that the turning of the car when the steering wheel is turned is normally a constant gear ratio, but when this gear ratio changes momentarily due to parameter fluctuations, it is the most appropriate from the past several trial results. It is likened to repeating the process of estimating the possible gear ratio and turning the steering wheel to get the target line.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below with reference to the drawings and mathematical formulas. FIG. 1 is a diagram showing an outline of a meandering control device according to an embodiment of the present invention. The rolled material 1 is running in the direction of the arrow, and the rolling roll (work roll) 3,
It is drawn into the roll gap 3'and rolled. The roll gap between the rolling rolls 3 and 3 ′ is adjusted by adjusting the position of the lower backup roll 4 ′ with the rolling down devices 5 and 7. The reduction device has a function of directly moving up and down bearing boxes (not shown) on both sides of the lower backup roll 4 '. The roll-driving-side reduction device is called a driving-side reduction device 7, and the working-side, ie, non-driving-side reduction device is called a driving-side reduction device 5.

The pressure reducing devices 5 and 7 use hydraulic cylinders in this embodiment. The pressure reducing devices 5 and 7 are independently controlled in their pressure reducing positions by the servo valves 9 and 11. The actual value of the rolling-down position is detected by the rolling-down position detectors 13 and 15 (Magnet scale etc.) attached to the rolling-down devices 5 and 7, respectively. The leveling operation is an operation of raising the reduction device on one side by a certain size and lowering the reduction device on the other side by the same size.

The meandering detection device 21 includes rolling rolls 3 and 3 '.
It is installed on the entrance side of the (rolling stand) and has a function of measuring the deviation between the center of the rolling mill and the center of the rolled material in the width direction, that is, the amount of meandering. The meandering detection device may use, for example, the left and right end detection signals of an optical rolling material width gauge. It is necessary to have a sufficient measurement span so that the position in the width direction of the rolled material can be measured with respect to the center of the rolling mill.

The meandering control device 22 is mainly composed of a meandering identification device 23 and a leveling amount calculation device 25. The meandering identification device 23 is a digital identification device that identifies the parameters of the meandering process model discretized online during rolling. The leveling amount calculation device 25 is a calculation device that calculates an optimum leveling amount for meandering control based on the identified parameters. The meandering control device according to the present invention is preferably realized by a programmable controller, a sequencer, a computer or the like that enables high-speed sampling (sampling period of 10 ms or less).

Next, an example of the control procedure in the meandering control device 22 will be described with reference to the flowchart of FIG. The meandering is a problem mainly in the final part (tail end) of the rolled material. The time when the control of the present invention starts is when the tail end approaches the controlled rolling stand. The meandering amount detected by the meandering detection device arranged on the rolling mill entrance side and the leveling amount of the rolling stand are input, and each data is stored in a tracking file in time series.
At this time, the sampling time (Δτ) is kept constant (see FIG. 2). If the amount of meandering is constant, meandering does not become a special problem.
Near the tail end, if the amount of meandering suddenly increases to either side of the mill, problems such as side guide damage and plate drawing will occur. The meandering amount at the start of control is taken in as the current value (normal value), and is held until the control is completed, and is set as the target value for meandering control.
Leveling takes in the current values of the rolling positions on both sides of the roll and calculates the difference from that.

The mathematical description of the meandering model is set with generality like the equation (1). In the equation, L is the model order of the meandering process, M is the model order of the leveling amount, and i
And j are suffixes, T is an unknown vector Φ to be identified
Of these parameters, E is a parameter related to the meandering process, and E is a parameter related to the leveling amount. Also, y _i is i
The second observation value of meandering amount, ΔS _j is the observation value of j-th leveling amount, and Y _i is the estimation value of meandering considering the fluctuation of rolling environment.

[0018]

[Equation 1]

The meandering process is described by the equation (1),
By online identifying T _i and E _j in time series,
The meandering estimation amount Y _i in which the fluctuation of the rolling environment (load, speed) is reflected in T _i and E _j is obtained. At the same time, by using T _i ⁰ and T _j ⁰ calculated in advance as initial values, the estimation speed to the true parameter of online identification is improved, and the convergence time can be shortened.

The means for online identification must be based on general model identification theory. Here, the description is made using the least squares estimation, but even if the maximum method is used,
Other identification methods may be used. <Meandering Model Identification by Kalman Filter Theory with Forgetting Factor (Exponential Weighting Type)> The general formula of the meandering model is shown in Equation (1). Based on this,
Each vector is defined as follows.

[0021]

[Equation 2]

[0022]

[Equation 3]

[0023]

[Equation 4]

According to this procedure, the parameter of the meandering model is calculated in the Φ vector, which reflects the fluctuation of the rolling environment. However, this procedure must be performed within Δτ time, and must be performed every sampling period. Accordingly, the meandering estimation amount Y _i can be described by the equation (8). Y _i = φ ₁ · y ₁ + φ ₂ · y ₂ + …… ＋ φ _L · y _L + φ _{L +1} · △ S ₁ + ……… ＋ φ _{L + M} · △ S _M …………… (8)

Compare Φ with upper and lower limits. If the calculation becomes abnormal, do not use this calculation. <Leveling amount calculation device> In the online identification device, the leveling amount ΔS is calculated by the identified parameter vector Φ and the known vector Z.
Calculate _ref . _{△ S ref = - (1 /} φ L + 1) · (φ 1 y 1 + φ 2 y 2 + ...... + φ L y L + φ L + 2 · △ S 2 + ...... + φ L + M · △ s M) ………………… (9) However, φ _{1 to} φ _{L + M} ≠ 0.

It is also important to set an output limit on _{ΔS ref} so that an excessive leveling command will not be issued. Further, as the plate target position, the meandering amount at that time is locked on and stored at the start of the meandering control. The calculated leveling amount is output to the reduction control device.
At this time, for example, with respect to the repetition cycle of 10 ms, the rolling position control is settled in about 8 ms. (10) When the tail end of the rolled material is completely slipped off, the control of the present invention ends.

Next, the case of applying the present invention to the final stage of a hot rolling finishing mill (eg, 6th and 7th stages of a 7-stage continuous mill) will be described as a specific example and an example of specific effects. According to the analysis of the conventional method theoretical model from the leveling difference to the amount of meandering,
It has been found that L = 2 and M = 2 are sufficient for the order of the identification model in this mill. In the example implemented, L
= 2, M = 2, and the dynamic characteristics of the reduction device were ignored. Therefore, the frame of the meandering model is as shown in equation (10), and the initial values of Φ vector T ₁ , T ₂ , E ₁ , and E ₂ are calculated as follows.

Y = φ ₁ · y ₁ + φ ₂ · y ₂ + …… + φ ₃ · ΔS ₁ + φ ₄ · ΔS ₂ …………… (10) T ₁ = 2τ / (τ + Δτ ² _{) ..................... (11) T 2 =} -τ / (τ + △ τ 2) ..................... (12) E 1 = ε · (T D + △ τ) / (τ + △ τ _{^{2) ........................ (13) E 2}} = -ε · (T D · △ τ / (τ + △ τ 2)) ..................... (14) τ: serpentine time constant, △ τ: Sampling time ε: Leveling / meandering gain, T _D : Meandering sensor phase lead time In an actual system, a logic sequence such as start and end of meandering control is required, but is not related to the gist of the present invention. Since it does not exist, the explanation is omitted. In addition, the sampling cycle was set to 10 ms.

Prior art (PID control) and the present invention (Self T
The control characteristics of the uning controller are compared by the simulation method. First, when a certain amount of plate width center deviation (off-center) disturbance occurs at a certain time t = 0, PID and ST
Adjustment was made so that C showed the same control characteristics (A in FIG. 3). Since the aim is not to return the amount of meandering to the value before the occurrence of off-center, the PID is adjusted to stabilize the value as quickly as possible and to a small value. Next, under the same conditions, in addition to the off-center disturbance at t = 0, the disturbance of the rolling load increase corresponding to the increase of the deformation resistance or the plate thickness is added around t = 0.2 seconds, and the control states of both control methods are compared. did. In the conventional method, A of 1.5
While the meandering amount is doubled (100%), the present invention is stable at about 1/2 (52.6%) of meandering.

This feature is that when controlling the meandering that occurs at the trailing edge of each stand of a continuous rolling mill, it is against fluctuations in parameters such as fluctuations in rolling roll speed, changes in temperature of the rolled material, and changes in rolling load due to changes in strip thickness. It means that the meandering can be corrected stably and at high speed.
It is possible to control the meandering amount of / 2 (see FIG. 3). For this reason, there are economical effects such as reduction of plate drawing and lifting of the blade when the tail end slips out, and improvement of yield, reduction of roll change, and extension of roll life.

[0031]

As described above, according to the present invention, since the meandering control device is constituted by the meandering model online identification device and the leveling amount calculation device, the conventional method is resistant to the parameter fluctuation during rolling (compared with the conventional method). 50%) A meandering control result was obtained, strip drawing and shaving increase at the trailing edge of the continuous rolling mill were reduced, yield was improved, and reshuffling due to roll defects was reduced.
It has the effect of extending the roll life. In addition, since the meandering model can be analyzed by online identification, there is an effect that the meandering model can be highly accurate.

The online identification device according to the present invention is
It is possible to quantitatively understand how the parameters of the meandering model are affected by environmental changes (parameter fluctuations) during rolling, and as a result, the leveling amount command value is calculated from the model parameter Φ vector and known vector Z. Therefore, it is possible to provide a meandering control characteristic that is robust (robust) to fluctuations in parameters during rolling.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a meandering control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a tracking method with a constant sampling time in the apparatus of FIG.

FIG. 3 is a diagram showing simulation results comparing the meandering control performances of a conventional control device and a control device according to an embodiment of the present invention.

FIG. 4 is a flowchart showing an example of a control procedure in the meandering control device of FIG.

FIG. 5 is a diagram for explaining a mechanism of meandering of a rolled material.

[Explanation of symbols]

 1: Rolling material 3: Rolling roll 4: Backup roll 5: Working side (FS) reduction device 7: Driving side (FS) reduction device 9, 11: Servo valve 13, 15: Reduction position detector 21: Meandering detection device 22 : Meandering control device 23: Identification device 25: Leveling amount calculation device

Claims (1)

[Claims] 1. A rolled material meandering control device in a continuous rolling mill comprising a plurality of rolling stands including rolling rolls and a rolling roll reduction device having leveling means; rolling material provided between rolling stands. A meandering detection device, an automatic identification device that online-identifies the process model of the meandering detected by the detection device, and a leveling amount for meandering control based on the meandering process model identified by the identification device. And a leveling amount calculation device for calculating the rolling amount.