JPH0815612B2 - Meandering control method - 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 method for a tail end portion of a rolled material in hot rolling.

[0002]

2. Description of the Related Art Meandering is a phenomenon in which a rolled material moves from a roll center to a working side or a driving side during rolling work.

When the degree of meandering increases, the side surface of the rolled material comes into strong contact with the side guides, which may cause breakage or buckling of the rolled material. In particular, when the tail end of the rolled material slips out of the rolling mill and the tension is lost, it tends to meander.

Therefore, as one of the conventional means for suppressing the meandering, the meandering is detected from the difference between the rolling loads on the left and right sides, and the leveling adjustment is performed so as to narrow the roll gap on the side where the rolling load is increased. A differential load type meandering control to be suppressed is implemented.

However, in the above-mentioned meandering control method, it is impossible to separate the lateral difference of rolling load due to the meandering amount of the rolled material tail end from the lateral difference of rolling load due to the planar shape of the rolled material tail end. In the meandering control described above, leveling control is performed so that the center line of the rolled material comes to the center of the roll.

For this reason, when there is a planar shape defect such as one-sided elongation at the tail end of the rolled material, as shown in FIG. 2, if the cut-off timing is delayed, a direction opposite to the original meandering direction of the rolled material is obtained. There is a risk that the control (g) will be performed to promote meandering. Therefore, it is necessary to terminate the meandering control before a control abnormality such as reverse operation occurs.

[0007]

In the conventional meandering control,
The control was terminated when the load relay of the controlled rolling mill was turned off. But the load relay is O
The timing to become FF is after the rolled material has completely slipped out of the rolling mill, and control at the tail end of the rolled material at the defective planar shape cannot be terminated.

In order to solve such a problem, in order to eliminate the unstable control operation at the tail end of the rolled material, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Unexamined Patent Publication No. 3-20110, a method of stopping the control of the trailing edge of the rolled material by using a rolled material velocity detector and a timer, and as disclosed in Japanese Patent Laid-Open No. 63-183713. In, the method of measuring the flat shape of the rolled material tail end, the method of terminating the control in the flat shape defective portion is proposed, but a special device such as a rolled material speed detector or a flat shape detector is required, The system is complicated and expensive.

Under a very severe environment such as continuous hot rolling equipment due to dust, water, vibration, temperature, etc., special detectors have problems in terms of reliability and maintainability. It's a reality.

In view of the above situation, the present invention provides a meandering control method capable of accurately determining the timing at which the meandering control of a rolled material is terminated by using a simple system.

[0011]

Means for Solving the Problems In the meandering control of the tail end portion of a rolled material in a continuous hot rolling mill, the present invention performs a control calculation when the rolling load in the meandering control rolling mill reaches a preset set value. And the meandering control output amount is held at the control amount at the time of the termination after the control calculation is terminated.

[0012]

When the tail end portion of the rolled material has a defective planar shape such as one-sided elongation, the strip width of the rolled material decreases in accordance with the size of the defective planar shape. Since the rolling load changes depending on the strip width, when the flat shape defective portion at the tail end of the rolled material leaves the rolling mill, the rolling load also decreases as the strip width decreases. Therefore, by measuring the reduction amount of the rolling load or the reduction rate of the rolling load, it becomes possible to detect the planar shape defect of the tail end portion of the rolled material.

A method of determining the cut-off timing of the meandering control from the reduction amount of the rolling load will be described with reference to FIG.

The rolling load of the controlled rolling mill is locked on (b) at an arbitrary timing. This means that the rolling load is memorized when the rolled material is stably passed, and the lock-on timing may be any time during the period when the rolled material is stably passed. It seems that the rolling load should be locked on (b) at the timing (a) when the meandering control is started.

When the rolling load of the rolling mill decreases from the lock-on value by a preset ratio (d), the control calculation is terminated (e), and the control amount is kept until the rolled material completely slips out of the rolling mill. For a certain period of time, the control amount at the time of the termination (e) is maintained (f).

However, in the present invention, the meandering control cutoff timing can be optimized by adjusting the set value (d) for determining the rolling load reduction.

Further, the rolling load reduction amount is detected by the reduction amount from the lock-on value, but the rolling load maximum value is stored and the meandering is performed by the rolling load reduction amount from this rolling load maximum value. A method of determining the control termination timing can also be used.

The same applies to the case where the meandering control termination timing is determined by using the reduction rate of the rolling load. However, in the case of the reduction rate, there is no lock-on, and the control is terminated when the reduction rate of the rolling load reaches or exceeds the preset value.

Due to the determination of the meandering control cutoff timing due to the reduction of the rolling load as described above, a planar shape defect such as single elongation occurs at the tail end of the rolled material and the direction of the rolling load difference is reversed at the tail end. Also in this case, the control operation can be bypassed without becoming unstable.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a control system for carrying out the control method of the present invention. In this embodiment, the timing of stopping the meandering control is determined by the reduction amount of the rolling load.

The meandering control system uses the rolling load calculator 6 from the rolling loads P _W and P _D on the working and driving sides detected by the rolling load detectors 5a and 5b of the controlled rolling mill 1.
Rolling load difference rate ΔP / P _t = (P _W −P _D ) /
(P _W + P _D ) is calculated, and this rolling load difference rate ΔP / P
Based on _t , the control output amount is calculated in the meandering adjuster 7 set to a predetermined control gain, and a reduction command is sent to the left and right reduction cylinders 8a and 8b based on this control output amount, and the work roll interval It is configured to suppress the meandering by controlling the gap.

In the rolling mill 1 having such a structure, assuming that the tail end of the rolled material 2 is asymmetrical in plan view and reaches the rolling mill trailing edge position, in the conventional meandering control, the rolled material 2 is
Although the rolling load is not meandering, the rolling load on the working side becomes larger than the rolling load on the driving side, and the meandering adjuster 7 calculates the control output in the direction of promoting the meandering.

On the other hand, the configuration of the control cutoff timing according to the present invention is performed by the rolling load calculator 6 from the rolling loads P _W and P _D on the working side and the driving side detected by the rolling load detectors 5a and 5b. Rolling load P _t = P _W + P
_D is obtained, and in the logic judgment circuit 9, the rolling load P _to locked on at the start of control and the rolling load P _t at the present time.
Therefore, when the rolling load reduction amount (P _to −P _t ) ≧ the set value, the changeover switch 10 is switched, and the leveling control output at the time of control termination until the rolled material slips through the rolling mill 1. It is designed to be held at a controlled amount.

After the rolled material 2 slips through the rolling mill 1, the control output is cleared. In this embodiment, the rolling load P _to of the control rolling mill is locked on when the load relay of the upstream rolling mill is turned off.

[0026]

According to the meandering control method of the present invention, it is possible to accurately determine the timing at which the meandering control of the rolled material is terminated by using a simple and inexpensive system, and to determine the planar shape of the tail end of the rolled material. It is possible to obtain an excellent effect that it is possible to avoid the abnormal operation of the control that is caused.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a control system for carrying out a control method of the present invention.

FIG. 2 is a diagram illustrating determination of a meandering control cutoff timing according to a rolling load.

[Explanation of symbols]

 1 Controlled rolling mill 2 Rolled material 3 Work roll 4 Backup roll 5a, 5b Rolling load detector 6 Rolling load calculator 7 Meander controller 8a, 8b Rolling down cylinder 9 Logic judgment circuit 10 Changeover switch

Claims (1)

[Claims] 1. In the meandering control of the tail end of a rolled material in a continuous hot rolling mill, the control calculation is terminated when the rolling load in the meandering control rolling mill reaches a preset set value, and after this control calculation is terminated. Is a meandering control method in which the meandering control output amount is held at the control amount at the time of the termination.