JPH084826B2 - 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. Especially when the tail end of the rolled material slips out of the rolling mill and loses the tension, it is easy to meander, and a large meander at the tail end causes so-called tail drawing.

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.

The meandering phenomenon at the tail end of a rolled material is a very unstable system, and once the meandering is started, it is difficult to completely correct it. For this reason, if the start of control is delayed, meandering greatly progresses during that time, and eventually the meandering cannot be suppressed and the tail restriction may occur.

As described above, in the meandering control, the delay in the timing of starting the control greatly affects the meandering suppressing ability of the meandering control. On the other hand, if the control start timing is too early, excessive control operation may be performed due to the noise of the rolling load signal or the like while the rolled material is caught in the upstream rolling mill.

When the rolled material is subjected to backward tension and restrained by the upstream rolling mill, the restraining force suppresses the meandering of the rolled material, but the extra leveling operation performed during this period is It becomes a cause of meandering of the tail end of the rolled material when the restraint to the rear is lost.

For this reason, it is desirable that the timing of starting the control coincides with the timing at which the tension at the tail end of the rolled material is lost and starts to meander, and a high meandering suppression capability is provided in the meandering control of the tail end of the rolled material. In order to obtain it, it is necessary to make the timing of starting the meandering control close to the timing at which the meandering at the tail end of the rolled material is likely to occur.

[0009]

The control start timing in the conventional meandering control of the tail end portion of the rolled material uses the trailing edge signal from the upstream rolling mill load relay. However, the timing at which the load relay turns off is after the rolled material has completely slipped out of the rolling mill, and this timing is later than the timing at which the meandering phenomenon begins,
Before the control was started, the meandering progressed and it was not possible to obtain a sufficient meandering suppressing effect.

In view of the above situation, the present invention provides a meandering control method capable of accurately determining the timing of starting the meandering control of a rolled material.

[0011]

According to the present invention, in the meandering control of the tail end portion of a rolled material in a continuous hot rolling mill, the reduction amount of the rolling load in the upstream rolling mill of the meandering control rolling mill is equal to or more than a preset value. The meandering control method is characterized in that the control is started from the time point when the value becomes, or the time point when the decrease amount of the upstream looper tension becomes equal to or more than a preset value.

[0012]

When the meandering at the tail end of the rolled material is considered, the meandering is suppressed by the backward tension while there is restraint in the upstream rolling mill, and the meandering starts when this restraint disappears.

The timing at which the constraint of the upstream rolling mill disappears can be detected from the timing at which the rolling load at the upstream rolling mill decreases or the timing at which the tension in the upstream looper decreases. Therefore, by determining the control start timing from these signals, it becomes possible to start the meandering control from the time when the meandering starts, and it is possible to improve the meandering suppressing ability.

A method of determining the control start timing according to the rolling load in the upstream rolling mill will be described with reference to FIG.

The rolling load of the upstream rolling mill is locked on (a) at an arbitrary timing. This is to memorize the rolling load when the rolled material is stably passed.

When the rolling load of the upstream rolling mill decreases from the lock-on value by a preset value (b), the meandering control of the controlled rolling mill is started. As shown in FIG. 2, the control start timing determined by the reduction of the rolling load is closer to the timing at which the meandering starts (c) and (d) as compared with the timing (e) of the conventional load relay, and the rolling is performed accordingly. The meandering of the material can be made smaller (h), (i).

In the present invention, however, the meandering control start timing can be optimized by presetting the set value (b) for judging the rolling load reduction.

The method of detecting tension in the upstream looper is the same as the method of rolling load. A method of determining the control start timing by detecting the tension in the upstream looper will be described with reference to FIG.

The tension of the upstream looper is locked on (j) at an arbitrary timing. When the looper tension of the upstream looper decreases from the lock-on value by a preset value (k), the meandering control of the controlled rolling mill is started.

As shown in FIG. 3, the control start timing determined by the reduction of the tension in the upstream looper is closer to the start timing of the meandering (l), (m) compared to the timing (n) of the load relay. Therefore, the meandering of the rolled material can be further reduced (q) and (r).

In the present invention, however, the meandering control start timing can be optimized by presetting the set value (k) for the looper tension decrease determination.

[0022]

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 the figure, 1 is a meandering control rolling mill, 2 is an upstream rolling mill, 3 is an upstream looper, and 4a and 4b are meandering control. Rolling load detector for detecting rolling load of rolling mill 1, 5
Reference numerals a and 5b are rolling load detectors for detecting the rolling load of the upstream rolling mill 2, and 6a and 6b are load detectors for detecting the looper load in the upstream looper 3.

The meandering control system includes a rolling load detector 4
Rolling load difference ratio ΔP ₁ / P _1t = (P _1W −P _1D ) / (P _1W + P from the rolling loads P _1W and P _1D on the working side and the driving side detected by a and 4 b by the rolling load calculator 7. _1D ) is calculated, and based on this rolling load difference rate ΔP ₁ / P _1t ,
A control output amount is calculated in the meandering controller 8 set to a predetermined control gain, and a reduction command is sent to the left and right reduction cylinders 9a and 9b based on the control output amount to control the gap between the work rolls. Is configured to suppress meandering.

In the method of determining the control start timing based on the rolling load of the upstream rolling mill, the rolling loads P _2W and P on the working side and the driving side detected by the rolling load detectors 5a and 5b of the upstream rolling mill 2 are used. Based on _2D , rolling load P _2t =
P _2W + P _2D is obtained by the rolling load calculator 10 of the upstream rolling mill, and the logical judgment circuit 11 decreases the rolling load from the locked rolling-up upstream rolling mill load P _2to and the current upstream rolling mill rolling load P _2t. When the amount (P _2to −P _2t ) ≧ set value, the control start timing switch 13 is switched, and the meandering control of the meandering control rolling mill 1 is started.

The same applies to the method of determining the control start timing by the upstream looper tension.
The looper tension calculator 12 obtains the looper tension T based on the work side and drive side looper loads P _3W and P _3D detected by the looper load detectors 6a and 6b installed in the 11, when the looper tension decrease amount (T ₀ −T) ≧ the set value from the locked-up upstream looper tension T ₀ and the current upstream looper tension T, the control start timing switch 13 is switched to perform the meandering control. The meandering control of the rolling mill 1 is started.

The mode changeover switch 14 determines which of the start timing determination based on the rolling load of the upstream rolling mill and the start timing determination based on the upstream looper tension is used.
Can be selected by.

In the case of this example, an example in which control circuits for both rolling load and looper tension are incorporated and selected is shown.
Obviously, it is possible to control only one of them.

[0029]

According to the meandering control method of the present invention, it is possible to accurately determine the timing to start the meandering control of the tail end of the rolled material by using a simple and inexpensive system, and control the meandering of the rolled material. In the above, the excellent effect that the meandering suppressing ability can be enhanced can be obtained.

[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 start timing based on an upstream looper tension.

FIG. 3 is a diagram illustrating determination of a meandering control start timing depending on a rolling load of an upstream rolling mill.

[Explanation of symbols]

 1 Meandering control rolling mill 2 Upstream rolling mill 3 Upstream looper 4a, 4b Rolling load detector 5a, 5b Meandering control rolling mill rolling load detector 6a, 6b Upstream looper load detector 7 Rolling load calculator 8 Meandering controller 9a, 9b Rolling down cylinder 10 Rolling load calculator for upstream rolling mill 11 Logic judgment circuit 12 Looper tension calculator 13 Control start timing switch 14 Mode switching

Claims (1)

[Claims] 1. In meandering control of the tail end of a rolled material in a continuous hot rolling mill, when the reduction amount of rolling load in an upstream rolling mill of the meandering control rolling mill reaches a preset value or more, or an upstream looper. A meandering control method, characterized in that the control is started from the time when the amount of decrease in tension exceeds a preset value.