JPH0587336B2 - - Google Patents

Description

[Detailed description of the invention] a. Industrial application field The present invention relates to an automatic plate thickness control method for a rolling mill.
In particular, it relates to new improvements for detecting the angle of the looper and controlling the relock-on timing in hot tandem mills to improve sheet threadability and highly accurate sheet thickness control.

b. Prior Art Conventionally, in the automatic plate thickness control method in hot rolling that has been generally used, the roll gap is controlled so that the plate exit side thickness calculated from the rolling pressure and the roll gap matches the target plate thickness. Storing this target plate thickness in the memory of the plate thickness control section is generally called lock-on.

As for the conventional automatic plate thickness control method, although the literature name etc. are not listed, in any method, lock-on occurs at the timing when the head of the product is bit into each stand, and the rotation of each stand, Due to an error in the initial setting of the rolling reduction, the mass balance between the stands could not be achieved, and the plate thickness was controlled by locking on with excessive tension between the stands.

c Problems to be Solved by the Invention Since the conventional automatic plate thickness control method for rolling mills was performed as described above, when locking on with excessive tension applied between each stand, this excessive tension As a result, the thickness at the exit side becomes extremely thin, the rolling pressure is low, and the mass balance is not yet achieved. This is stored as the target thickness, and then the loop control action of the looper is used to adjust the thickness to the appropriate thickness. In the loop state, that is, in the process of the tension reaching an appropriate value, steep tension fluctuations and rolling pressure fluctuations occur.

Therefore, when the automatic plate thickness control operates the reduction steeply toward an abnormal target value in a state where the mass balance is disrupted and the plate thickness is thin, the looper between each stand will hunt, causing hot rolling problems. This was the cause of deterioration in the passage of the plate.

In addition, in automatic plate thickness control, the initial abnormal value that appeared thin was fixed as the target plate thickness, so control was to be performed toward a plate thickness value that was different from the original target value. It was extremely difficult to obtain good accuracy.

Furthermore, recently, the thickness of steel plates used in products such as automobiles has increased, for example, to 0.7 mm.
As the thickness becomes thinner, extremely high accuracy is required to control the plate thickness, and making the plate thinner than the target thickness has become a serious problem.

The present invention promptly solves the above-mentioned problems, and even when rolling is performed with the product head in an excessive tension state, the product can be passed through the plate without making a steep roll gap operation after returning to the proper tension.
Another object of the present invention is to obtain an automatic plate thickness control method for a rolling mill that enables highly accurate plate thickness control.

d Means for Solving the Problems The automatic plate thickness control method for a rolling mill according to the present invention includes a tandem mill for rolling hot strip steel, and an automatic plate thickness control method for controlling the rolled plate thickness of the tandem mill. In a hot band steel tandem rolling mill having a control unit, a looper and a loop control unit for controlling the tension between each stand of the tandem mill, an angle signal detected by a pulse generator provided in the looper is used. Therefore, the first step is to detect the tension state of the hot strip steel between each stand, and the second step is to re-lock on the automatic plate thickness control section in the steady tension region of the tension state obtained in the first step. It consists of two steps.

e Effect In the automatic plate thickness control method for a rolling mill according to the present invention, when the pulse generator detects that the looper has returned to the steady angle (steady tension return), the automatic plate thickness control section is relocked. By doing this, lock-on is performed in the steady tension region, canceling the abnormal target plate thickness and mass balance, and thereby returning the stand exit side plate thickness to the original target value.

Therefore, it is possible to update the plate thickness to the originally targeted thickness, which prevents sudden movements in rolling reduction, and as a result, improves the threadability in hot tandem rolling and improves the accuracy of automatic plate thickness control. can.

f Example Hereinafter, a preferred example of the automatic plate thickness control method for a rolling mill according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a rolling mill and an automatic plate thickness control system for applying the automatic plate thickness control method according to the present invention. n-1st stand 3
This is a hot rolling tandem mill consisting of a hot rolling tandem mill, and each of these stands 2 and 3 is provided with a first rolling roll 4 and a second rolling roll 5.

Each of the rolling rolls 4 and 5 in each of the stands 2 and 3 is provided with a first rolling device 6 and a second rolling device 7 consisting of a rolling screw and a position control device (not shown), as well as first and second rolling devices.
Load cells 8 and 9 are each provided.

A looper 11 is rotatably provided between each of the stands 2 and 3 for bending a part of the hot steel strip (hereinafter referred to as a strip) 10 being rolled and conveyed. A rotating shaft 12a of a looper motor 12 is connected to the looper motor 12, and the rotation of the looper motor 12 lifts the looper 11 to a required angle, thereby making it possible to bend the strip 10.

Next, what is indicated by the reference numeral 13 is an automatic plate thickness control section 13, which includes a first calculation section 14, a second calculation section 15, an adder 16, a subtracter 16a, a lock It is composed of an on-memory X, a pulse generation circuit 17, and an OR circuit 18.

The output signal F of the first load cell 8 is input to the second calculation section 15, and the output signal F of the first calculation section 14 is input to the second calculation section 15.
S is inputted to the first rolling down device 6, and the feedback signal S of the first rolling down device 6 is inputted to the adder 16.

Furthermore, the rotation shaft 12a of the looper motor 12
is connected to a pulse generator 19 for detecting the angle of the looper 11, and the output signal P of this pulse generator 19 is sent to the angle detector 2.
0, and the output signal θ of this angle detector 20
is applied to the roll motor 23 as a speed correction signal via the loop controller 21 and mill speed control system 22. Therefore, by correcting the rotation of the roll motor 23, the rotation of the second rolling roll 5 of the n-1st stand 3 is corrected, and the loop amount between the n-th and n-1st stands is corrected.

The output signal θ of the angle detector 20 is input to a relock-on timing determination logic unit 24,
This relock-on timing determination logic section 24
A relock-on signal RO, which is an output signal from the OR circuit 18, is input to one input terminal 18a, and a lock-on timing signal RT is input to the other input terminal 18b.

Next, a case will be described in which automatic plate thickness control is actually performed using the rolling mill and automatic plate thickness control system configured as described above.

First, the output of the n stand 2 is calculated based on the output signal F, which is the rolling pressure detected by the first load cell 8, and the output signal S, which is the screw position measured by the rolling down device 6. Side plate thickness h
is given by the following equation.

h=α/MF+S...1 formula, where M is Mill's constant α is a scale factor Using the exit side plate thickness of the n-th stand 2 in the above-mentioned 1 formula, after a certain period of time has elapsed after the n-th stand 2 is engaged, (lock-on timing RT signal ON), close the switch L, store the value of the exit side plate thickness h at that time as the lock-on value h ₀ in the lock-on memory Using the deviation Δh of h ₀ as a control factor, it is converted into the rolling screw movement amount ΔS by the plate thickness influence coefficient M+Q/M (∵Q is the plasticity coefficient), and the rolling device 2 is controlled.

Furthermore, to explain the operation of the inter-stand loop control system for controlling the strip 10 between each stand 2 and 3, this inter-stand loop control system includes a looper 11, a looper motor 1
2, pulse generator 19, angle detector 20,
It is composed of a loop controller 21 and a mill speed control system 22.

Here, the relock-on timing determination logic 24 which inputs the output θ of the angle detector 20 calculates
The tension state between each stand 2 and 3 is determined, and automatic board thickness control is relocked in the steady tension region.

Figure 2 shows the above-mentioned relock-on determination logic 2.
In addition to showing the operation timing of step 4, FIG. 3 also shows the control flow of the relock-on determination logic.

First, in Fig. 2, the horizontal axis is time, the vertical axis is the engagement of the n-th stand 2, and the looper angle (θp is the looper angle at the pass line, _θ1 is the setting angle for relock-on timing detection, and _θ0 is (control target angle of the loop controller), relock-on signal RO, and the on state of AGC.

In FIG. 2, after TD ₁ has elapsed from the n-th stand engagement timing, the AGC locks on to start control, and the looper 11 rises at the same timing.

At this time, the n-th stand 2 and the n-1 stand 3
In between, the head of the strip 10 is under strong tension, and the looper 11 contacts the strip 10, but is pressed down to the pass line angle θp.

On the other hand, in the above-mentioned state, the loop controller 21 operates and gives a rotation increase correction signal to the n-1st stand 3 and the stands upstream from it, and loops the strip 10 between each stand 2 and 3. relax.

After the aforementioned AGC is turned on and T ₁ has elapsed,
When the loop becomes slack and reaches the relock-on set angle θ ₁ for relock-on, a pulse-like relock-on signal is applied to the automatic plate thickness control device 13.

Thereafter, the looper 11 is loop-controlled toward the target angle θ ₀ , and is controlled so that the angle θ ₀ is maintained, although there is some vertical fluctuation due to some rolling disturbance.

In the subsequent rolling process, even if the relock-on setting angle θ ₁ is passed again, from the second time onwards,
The relock-on timing determination logic 24 cancels the lock-on and is configured not to perform lock-on again.

Next, the control flow of the relock-on determination logic will be shown using FIG.

First, it is determined whether or not the strip 10 is caught in the n-th stand 2 (step 1), and only when it changes from off to on, the memory K is cleared to zero (step 2). Then TD ₂ with AGC on
The timing after the elapse is determined (step 3), and if the timing is the same, it is determined whether K=0 (step 4).

In each of the above-mentioned judgments, if the result is NO, the process returns to the start.

After that, the angle θ of the looper 11 becomes θ<θ ₁ (θ ₁
is the re-lock-on setting angle) is satisfied (step 5), and if NO,
Put K+1 into memory K and return to the start (step 6).

The above state indicates that the looper 11 rose above the relock-on setting angle θ ₁ during the margin time TD ₂ after the looper 11 rose until it came into contact with the strip 10, and the head of the strip 10 shows that it is not in tension. In this case, K+1 is stored in memory K so that the same function is not used.

If the above judgment is YES, it waits until the angle of the looper 11 becomes θ> _θ1 (step 7), outputs one pulse of the relock-on signal RO (step 8), and then stores K+1 in the memory K. (Step 9), the relock-on function is not used until the next strip is caught in the n-stand 2.

g Effects of the Invention Since the automatic plate thickness control method for a rolling mill according to the present invention has the above-described configuration and operation, it can obtain the following various effects.

(1) When the looper returns to the steady angle, that is, when the steady tension returns from the excessive tension state, by relocking the looper,
The target value for automatic plate thickness control can be updated to an appropriate value, and as a result, the plate thickness value, which is the original target value, can be maintained with high accuracy.

(2) Due to the above-mentioned effects, steep movements of the rolling device can be prevented, and as a result, sheet threadability can be improved in hot tandem rolling.

[Brief explanation of the drawing]

The drawings are for illustrating the automatic plate thickness control method for a rolling mill according to the present invention. FIG. 1 is a block diagram showing the overall configuration, FIG. 2 is a time chart showing the operation timing of the relock-on determination logic, and FIG. 3
The figure is a flowchart showing the operation of the relock-on determination logic. 1 is a hot rolling tandem mill, 2 is an n-th stand, 3 is an n-1-th stand, 4 is a first rolling roll, 5 is a second rolling roll, 6 is a first rolling device, 7
is the second reduction device, 8 is the first load cell, 9 is the second
Load cell, 10 is a strip, 11 is a looper, 12 is a looper motor, 13 is an automatic plate thickness control section, 16 is an adder, 19 is a pulse generator,
20 is an angle detector, 21 is a loop controller,
22 is a mill speed control system, and 24 is a relock-on timing determination logic.

Claims (1)

[Claims] 1. A tandem mill for rolling hot strip steel,
A hot band steel tandem rolling mill having an automatic plate thickness control unit for controlling the rolled plate thickness of the tandem mill, and a looper and a loop control unit for controlling the tension between each stand of the tandem mill,
A first step of detecting the tension state of the hot strip between each stand by an angle signal detected by a pulse generator provided in the looper; and a tension state obtained in the first step. . A method for automatically controlling plate thickness in a rolling mill, comprising: a second step of relocking the automatic plate thickness control section in a steady tension region.