JP3347572B2 - Meandering control method for tandem rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a meandering control technique for securing a stable threading property of a rolled material during rolling in a tandem rolling operation of a metal plate.

[0002]

2. Description of the Related Art In plate rolling, a control technique for passing a rolled material straight through a rolling line is one of the most important operation techniques from the viewpoint of avoiding a rolling trouble. Such a technique is generally referred to as a meandering control technique. The most effective actuators for meandering control are the working side (work side: WS) and the drive side (drive side: DS) of a horizontal roll rolling mill. This is a rolling leveling operation for adjusting the rolling position difference. In the following description, in many cases, the working side (WS) and the driving side (DS) are simply represented by “left, right”,
Passing a rolled material in a widthwise direction from a mill center is referred to as "meandering".

As a conventional technique relating to meandering control, for example, as disclosed in Japanese Patent Publication No. 58-51771, left and right rolling load detectors are provided, rolling loads on both sides are separately detected, and the sum of the load differences is calculated. Ratio (hereinafter referred to as the load difference ratio)
Is calculated, and the rolling leveling control is performed based on the load difference ratio. Also, as in JP-A-59-191510, the meandering detector of the rolling mill is used to detect the meandering amount of the rolled material. There is a method of performing a reduction leveling control, and a method of providing a load detector between rolling mills and performing a reduction leveling control based on a load difference between the rolling mills, as disclosed in Japanese Patent Publication No. 57-209708.

[0004]

However, in the conventional control method described above, in a single-stand rolling mill or in tandem rolling having a plurality of rolling mills, the control method is performed after the rear end of the rolled material leaves the immediately preceding rolling mill. However, in the steady rolling state at the time of tandem rolling, in the case of the above-described conventional method, it is not possible to perform appropriate control on all rolling mills.

[0005] That is, from the experimental studies of the inventors, the meandering phenomenon during steady tandem rolling is that the optimum value of the rolling leveling is deviated (hereinafter this is referred to as poor rolling leveling).
It has been clarified that the meandering caused by the above is transmitted from the upstream side to the downstream side, and that the meandering also occurs in the normal rolling mill on the downstream side where there is essentially no rolling leveling failure.

Therefore, for example, when the meandering is caused to the downstream side due to the poor draft leveling on the upstream side, if the meandering is corrected by operating the downstream rolling mill according to the above control method, This is an erroneous operation, and if the rolling level of the upstream rolling mill is set to an appropriate state,
On the downstream side, meandering occurs again due to the above-described rolling leveling operation. That is, in the meandering control at the time of steady tandem rolling, it is necessary to control the entire tandem rolling mill in consideration of the influence on the downstream side, instead of controlling each rolling mill separately.

In view of the above, according to the present invention, when meandering occurs in a plurality of rolling mills during steady tandem rolling, one of the plurality of rolling mills in which the meandering has been detected always performs rolling leveling control of one rolling mill on the most upstream side. By repeating the above control at all times until the entire tandem rolling mill has no meandering,
A meandering control method capable of precisely adjusting only a rolling mill having poor leveling reduction is presented.

[0008]

This onset bright [Means for solving problems] In the meander control method for correcting meandering of the tandem rolling at the steady rolling by reduction leveling control for adjusting the left-right difference of rolling set value of the rolling machine, the reduction leveling operation The time from when the rolling operation is performed until the next rolling leveling operation is performed in the same rolling mill or another rolling mill is defined as the passing time of the material from the rolling mill in which the rolling leveling operation is performed to the final rolling mill, and the time between the first rolling mill and the final rolling mill. A meandering control method for a tandem rolling mill, wherein a passing time of a material to a rolling mill is equal to or longer than an added time. Hereinafter, the operation of the present invention will be described in detail.

[0009]

FIG. 2 is a schematic diagram of a continuous rolling mill in which three rolling mills are arranged in tandem. In FIG. 2, 1
Is a rolling mill, 2 is a rolling leveling device provided in the rolling mill, 3 is a rolling load detector, 4 is a meandering detector, 6 is a looper roll, 7 is a rolled material, and 9 is a coiler. . Rolled material 7
The rolling mills 1a, 1b, and 1c are arranged in tandem in the order of the rolling direction 8 to form a tandem continuous rolling mill. Each rolling mill has a reduction leveling device 2a, 2b,
2c and rolling load detectors 3a, 3b, 3c are provided respectively. In addition, meandering detectors 4a, 4b, and 4c are provided on the exit side of each rolling mill, respectively. Further, coilers 9a and 9b are provided on the entrance side and the exit side of the continuous rolling mill, respectively, and a looper roll 6a is provided between the coiler 9 and the rolling mill and between the rolling mills. , 6b, 6c, 6d
Is provided.

[0010] Rolled material 7 sent out from coiler 9a
Enters the rolling mill via the looper roll 6 and the rolling mill 1
Rolled by a, 1b, 1c and wound up on a coiler 9b. The meandering amount of the rolled material is detected by meandering detectors 4a, 4b, and 4c on the exit side of each rolling mill, and the rolling leveling amount is determined based on the meandering amount, and the meandering is controlled by controlling the rolling leveling device. is there.

First, an experiment was conducted to observe the meandering behavior during steady tandem rolling using a continuous rolling mill of three rolling mills as shown in FIG. In the experiment, under the conditions as shown in Table 1, the rolling leveling operation was performed twice for each of the first to third rolling mills on the time schedule of the experiment as shown in FIG. Was observed.

[0012]

[Table 1]

FIG. 4, FIG. 5 and FIG.
It is a measurement result of the meandering amount by the meandering detectors installed on the left and right sides of each rolling mill when the rolling leveling operation is performed in the second and third rolling mills. From these, meandering occurs in the rolling mill that has performed the rolling leveling operation, and the upstream rolling mill is hardly affected by the meandering, but the downstream rolling mill has a time lag, but in the same direction as the upstream side. It can be seen that meandering occurs and each rolling mill reaches a steady state when it reaches a certain meandering amount. Also, by returning the rolling leveling amount to an appropriate state when this meandering has reached a steady state,
It can be seen that each rolling mill returns to the initial state before the rolling leveling operation is performed.

As described above, the meandering phenomenon at the time of steady tandem rolling is such that the meandering is transmitted from the upstream side to the downstream side, and the meandering occurs even in a normal rolling mill having no downstream rolling reduction defect. Therefore, when the control is performed separately in each rolling mill as in the conventional meandering control method, it is necessary to operate up to a normal rolling mill having no rolling leveling failure, and it is not possible to perform appropriate control. That is, in order to control the meandering during the steady tandem rolling, it is necessary to correctly detect a position where the rolling leveling is defective and perform an appropriate rolling leveling operation for the rolling mill.

[0015] where, steady tandem when rolling the rolling reduction leveling defects mill only as a way of adjusting accurately, reduction leveling always one rolling mill on the most upstream side among the plurality of rolling mill detected meandering Control. By repeating this control, the meandering of the entire tandem rolling mill is corrected and eliminated. In other words, as can be seen from the characteristic that the meandering is mainly transmitted from the upstream side to the downstream side, when the meandering occurs on a plurality of rolling mills due to a plurality of rolling leveling defects, the meandering occurring on the downstream side It will include many causes on the upstream side, and conversely, it will decrease as it goes upstream. Accordingly, by controlling the rolling leveling first from the upstream rolling mill and sequentially eliminating the cause of the meandering on the downstream side, it is possible to accurately adjust only the rolling mill having poor rolling leveling.

[0016] in Figure 1 flow - Cha - according DOO, will be described an algorithm based rather meandering control method of the above concept. During steady-state tandem rolling, the meandering amount on the entrance side and / or the exit side is measured by a meandering detector installed on one or both of the entrance side and the exit side of each rolling mill. Based on these meandering amounts, a rolling mill (hereinafter referred to as a meandering rolling mill) having a meandering rolling target to be subjected to the rolling leveling operation is detected among all the rolling mills of the tandem rolling mill. In this case, for example, the above-described meandering amount on the incoming side or the meandering amount on the outgoing side, or the meandering amount immediately below the roll estimated from the meandering amounts on the incoming and outgoing sides is determined in advance by the allowable meandering amount. In comparison, the rolling mill exceeding the allowable amount is detected as a meandering rolling mill. Here, the meandering detector is a measuring device capable of detecting the position of the sheet passing in the width direction. The meandering detector is mainly an optical, monitor-type, or contact-type meandering detector. A vertical roll rolling mill or a width gauge equipped with a roll and a vertical roll width detector can also be used as a meandering detector.

Next, among the detected meandering rolling mills, the rolling mill on the most upstream side is selected, and the meandering amount on the inlet side or the meandering side on the rolling side of the rolling mill or the estimated meandering amount immediately below the roll is determined. Then, an optimal rolling leveling operation amount is calculated, and the rolling leveling operation is executed based on this operation amount. Leveling operation amount Δg at this time, when the meandering amount and x _c, for example, calculated from the following equation.

[0018]

(Equation 1)

Here, K _p is a proportional gain, T _I is an integral gain, and T _d is a differential gain. This rolling leveling control is repeatedly performed until the meandering amount becomes equal to or less than the allowable amount. The control cycle at this time is preferably performed at a cycle equal to or longer than the time when the meandering of the rolling mill becomes steady. When the control of the meandering rolling mill on the most upstream side is completed, the same operation as described above is performed in the rolling mill on the downstream side, and the meandering rolling mill in the tandem rolling mill is detected again. The rolling leveling control is executed for the most upstream rolling mill. When moving the control target to the downstream rolling mill in this way, it is desirable to wait for a time until the meandering of the final rolling mill becomes a steady state.

Here, as shown in FIG. 8, the time from when the rolling leveling operation is performed until the meandering of the final n-th rolling mill reaches a steady state is defined as t _sn, and the leveling operation is performed under the conditions shown in Table 1. With respect to the above-described experimental results, the time required for the meandering of the final rolling mill to reach a steady state was arranged. FIG. 9 shows the i-th rolling mill (i = m) in which the rolling leveling operation was performed from the time t _sn until the meandering of the final n-th rolling mill became steady when the rolling leveling operation was performed in the i-th rolling mill. 1 to n) to subtract the passing time t _i−n of the material from the first rolling mill to the last n rolling mill, and normalize by the passing time t _1−n of the material from the first rolling mill to the last n rolling mill, ie, (t _sn -T
_i−n ) / t _1−n , where n = 3. From this, it can be seen that the value of ( _{tsn -} ti _-n ) / t1 _-n is close to 1 under any condition.

Therefore, it has been clarified that t _sn can be expressed by the following equation (2).

T _sn ≒ t _i−n + t _1−n (2) Therefore, if t _i−n and t _1−n are measured _respectively , the meandering of the final n-th rolling mill becomes steady. The following time t _sn can be obtained, and the next control may be performed after waiting for this time or more.

As described above, when moving the object to be controlled by the rolling mill, the passage time t _i-n of the material from the i-th rolling mill to the final n-th rolling mill that has performed the rolling leveling operation and the first rolling mill Time t _1-n of the material from the rolling mill to the last n-th rolling mill
_Is obtained from the equation (2), and after waiting for the time or more, the next rolling-down leveling operation is executed, whereby it is possible to accurately detect the meandering amount and specify the control rolling mill.

As described above, in the present invention, taking into account the meandering phenomenon at the time of steady tandem rolling in which meandering is transmitted from the upstream side to the downstream side, the most upstream side of the rolling mill in which meandering always occurs is taken into consideration. By operating the rolling leveling of the rolling mill and sequentially eliminating the cause of the meandering from the upstream side, only the rolling mill having poor rolling leveling can be accurately adjusted.

[0025]

EXAMPLE With seven tandem rolling mills as shown in FIG.
All rolling mills have rolling leveling devices 2a to 2g, and meandering detection devices 4a to 4g that can measure the width direction passing position of the rolled material are provided between the rolling mills on the rear side of all rolling mills. The meandering control method of the present invention was implemented using a tandem rolling mill.

At the time of steady tandem rolling, the meandering detectors 4a to 4g installed on the exit side of each rolling mill detect the meandering amount. The meandering rolling mill to be subjected to the leveling operation is the third
It turned out that there were five rolling mills of 4, 5, 6, and 7.
A third rolling mill on the most upstream side is selected from the meandering rolling mills, and an optimal rolling leveling operation amount is calculated based on the amount of meandering on the outlet side of the third rolling mill, and the rolling leveling is performed based on the operating amount. The device 2c was operated. 3rd with one leveling operation
Since the meandering amount of the rolling mill was within the allowable range, the leveling control of the third rolling mill was completed. At that time, in addition to the passing time of the material from the first rolling mill to the final seventh rolling mill, wait for the passing time of the material from the third rolling mill to the final seventh rolling mill or more, and again, all the rolling mills of the tandem rolling mill As a result of measuring the meandering amount, the meandering rolling mill was the sixth and seventh two rolling mills among the seven rolling mills.

In the same manner as described above, the sixth rolling mill on the most upstream side is selected from the meandering rolling mills, and based on the meandering amount on the exit side of the sixth rolling mill, an optimum rolling leveling operation amount is calculated. The rolling leveling device 2f was operated based on the operation amount. 1
The leveling control of the sixth rolling mill was completed because the meandering amount of the sixth rolling mill was within the allowable range by the number of leveling operations.
After that, in addition to the passage time of the material from the first rolling mill to the final seventh rolling mill, the passage time of the material from the sixth rolling mill to the final seventh rolling mill is waited for more than the passing time. As a result of measuring the amount of meandering on the exit side, there was no meandering rolling mill. Thereafter, during the steady rolling, the rolled material was allowed to pass straight through the rolling line, and the trailing end portion of the rolled material was able to be stably passed.

In the above control, the meandering amount obtained from the meandering detector is used as a method for detecting the meandering rolling mill. However, in the case of a facility that does not have a meandering detector in all rolling mills or a facility that does not have a meandering detector at all. Is the load difference obtained from the left and right rolling load detectors of each rolling mill, or, in a rolling facility having a looper load detector between rolling mills, In a rolling facility having both a load detector and a meandering detector, similar control can be performed by using a difference in tension acting on a rolled material.

[0029]

As described above, according to the present invention, an appropriate rolling leveling operation can be performed during the tandem steady rolling, and as a result, there is almost no accident at the time of threading including the rear end rolling of the rolled material. It is possible to improve the operation efficiency and the yield of the operation.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an algorithm of a meandering control method according to the present invention.

FIG. 2 is a side view showing an outline of a continuous rolling mill used for observing meandering behavior during tandem steady rolling.

FIG. 3 is a time chart showing an experimental time schedule in an experiment for observing meandering behavior during tandem steady rolling.

FIG. 4 is a graph showing outputs (meaning amount) of meandering detectors on the left and right sides of each rolling mill when a rolling level defect is given to a first rolling mill.

FIG. 5 is a graph showing the output (meaning amount) of the meandering detectors on the left and right sides of each rolling mill when a rolling level defect is given to a second rolling mill.

FIG. 6 is a graph showing outputs (meaning amounts) of meandering detectors on the left and right sides of each rolling mill when a rolling level defect is given to a third rolling mill.

FIG. 7 is a side view showing an outline of a continuous rolling mill embodying the present invention.

FIG. 8 is a graph showing a change in meandering amount from a rolling leveling start point, and shows a time t _sn until the final rolling mill reaches a steady meandering amount.

FIG. 9 shows a value obtained by subtracting the passage time of the material from the rolling mill on which the rolling leveling was performed to the third rolling mill from the time required for the final rolling mill to reach the steady meandering amount. It is a graph which shows the value normalized by the passage time of the material between.

[Explanation of symbols]

1a to 1g: rolling mill 2a to 2g: reduction leveling device 3a to 3g: load detector 4a to 4d: meandering detector 5a to 5g: looper load detector 6a to 6f: looper 7: rolled material 8: rolling direction 9a to 9b: coiler

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-20608 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 37/00-37/78

Claims (1)

(57) [Claims] 1. A meandering control method for correcting meandering in tandem rolling at the time of steady rolling by means of a rolling leveling control for adjusting a left-right difference of a rolling set value of a rolling mill. The time until the next rolling leveling operation in the mill, the passing time of the material from the rolling mill that performed the rolling leveling operation to the final rolling mill, and the passing time of the material from the first rolling mill to the final rolling mill, A meandering control method for a tandem rolling mill, wherein the time is equal to or longer than the added time.