JPH07214127A - Method for controlling strip width in finishing roll - Google Patents

Abstract

PURPOSE:To keep a strip width at the outlet side of a rolling mill to a target value in high accuracy by calculating the tension for making the deviation of a strip width meter the target value at each stand just before setting the strip width meter, giving it as the tension at the rear part just under roll bite to control the strip width. CONSTITUTION:The strip width between F2-F4 stands positioned at the intermediate part in a finish rolling mill group F1-F7 with the strip width meter 4 and the tension just before the inlet of the roll bite in the F3 stand and the tension just before each roll bite of the F4, F5 and F6 stands with a tension detecting instrument 3 between the stands, are measured and transmitted to an arithmetic unit 5. Tension correcting quantity calculation is predictively calculated as the steel strip based on between the stands with the setting reference tension to the steel strip 1 reaching the F3 stand based on the measured strip width and tension by executing the feedback of the tension values at the F4, F5 and F6 to the strip width deviation from the target value at the finish rolling mill side. The tension for making the measured width deviation with the strip width meter 4 between the stands used at this time the target value, is calculated at the stand just under the F3 roll bite to control the strip width as the tension at the rear part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strip width control method in finish rolling for controlling strip width by controlling tension between stands.

[0002]

2. Description of the Related Art In general hot rolling, a heated slab is rolled by rough rolling and finish rolling, and is operated so as to have a predetermined plate thickness on the exit side of the finish rolling mill. However, regarding the strip width, the strip width in the longitudinal direction of the material on the exit side of the finish rolling mill is not necessarily constant due to temperature variations such as skid marks generated during the heating process in the heating furnace and width variations on the exit side of the rough rolling mill. However, there was a deviation of the plate width from the target value. Due to such plate width deviation, in actual operation, a margin is provided so that the width on the delivery side of the finishing mill does not fall below the target value over the entire length in the longitudinal direction of the material. In this case, if the plate width deviation is large, a large margin width must be taken, which also causes a decrease in yield.

By the way, it is desirable to reduce the margin width as much as possible from the standpoint of improving the product yield. It is only necessary to reduce the width variation in the coil of the finished product.Therefore, in order to eliminate the width variation on the output side of the rough rolling mill and to suppress the width variation occurring in the finishing rolling mill, a finish composed of multiple stands There has been proposed a method of performing strip width control by utilizing tension between stands of a rolling mill. For example, on the entry side of the finishing rolling mill, the required tension corresponding to the sheet width deviation is calculated according to a predetermined relational expression for the sheet width, sheet thickness, steel type, temperature, etc. of the material to be rolled, and the calculated value is used to stand. The inter-tension is controlled predictively.

On the other hand, as in Japanese Patent Laid-Open No. 63-76709, on the rolling mill exit side when rolling is performed on the basis of the strip width and temperature of the material on the rolling mill entrance side, based on the tension between stands. Predicting the plate width fluctuation of this, and removing this plate width deviation between the stands selected in consideration of the height difference of the temperature distribution between the stands, calculate the necessary tension correction amount for each part in the longitudinal direction of the rolled material, When the corrected tension exceeds the tension limit, the tension set value between the stands is set as the tension limit value, and the plate width deviation that could not be removed is removed between adjacent upstream stands, and the same tension correction amount is calculated. Then, repeat the same calculation until the plate width deviation that could not be completely removed by the tension limit can be sequentially removed between the stands on the upstream side.Tension control is performed according to the inter-stand tension correction amount obtained by these calculations. Is that.

[0005]

In the conventional method of controlling the strip width using the tension between the stands of the finish rolling mill in the hot tandem rolling according to the above-mentioned proposal, the strip width gauge deviation is set as the target value. No means for controlling the rear tension immediately below the roll bite is disclosed as a calculation of the tension in the stand immediately before the installation of the plate width gauge, and the method is disclosed in JP-A-63-7.
The same applies to the 6709 publication. Therefore, in the conventional strip width control method, simply predicting the inter-stand tension and performing the inter-stand tension control based on the prediction means that the strip width of the target value predicted at the rolling mill exit side is This means that the deviation is removed, and the change in the finishing exit side width does not necessarily correspond well to the change in tension between stands, and there is a problem that accurate plate width control is not performed. . As described above, in the prior art, it was not clear which stand should be used for the strip width deviation on the delivery side of the rolling mill.

The present invention has been made in order to solve such a problem, and is effective by means for controlling the plate width deviation from the predicted target width on the delivery side of the rolling mill and controlling the rear tension immediately below the roll bite. It is an object of the present invention to provide a strip width control method in a finish rolling mill which can be controlled to a desired value.

[0007]

The object of the present invention is to achieve the above-mentioned object, and the gist of the invention is to provide a method for controlling the plate width by controlling the tension between stands. A plate width meter is installed, and the tension for setting the deviation of the plate width meter to the target value is calculated for each stand immediately before the installation of the plate width meter, and it is given as rear tension just below the roll bite to control the plate width. A strip width control method in finish rolling.

[0008]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram of an apparatus for carrying out the present invention. Figure 1
In the rolling mill groups F _{1 to} F ₇ of the finishing rolling mill 2 for finishing rolling the material 1 to be rolled, the inter-stand tension detecting device 3 for detecting the tension value of each stand is provided just below the roll bite. A looper, which is an inter-stand tension control device (not shown), is provided between the stands of the finishing rolling mill groups F _{1 to} F ₇ . On the other hand, a plate width gauge 4 is installed between the stands, and tension for setting a plate width deviation from the plate width gauge 4 to a target value and tension from each inter-stand tension detection device 3 provided immediately below the roll bite are provided. An arithmetic unit 5 is provided for calculating the rear tension values of the respective stands which are used as the target plate width deviations, and the arithmetic unit 5 calculates and gives the rear tension immediately below the roll bite. The arithmetic unit 5 is configured to control as feedback in the rolling mill F ₃ , and to control the rolling mills F ₄ , F ₅ , and F ₆ as feedforward, as shown in the figure, for example.

FIG. 2 is a view showing the tension state of the rolling mill.
As shown in FIG. 2, the material 1 to be rolled is directly below the roll bite 6
In, the forward tension and the backward tension are acting as shown by the arrow. Further, FIG. 3 shows the situation in detail.
FIG. 3 is a diagram showing a change in plate width between roll stands. As shown in the figure, plate width reduction such as plate width reduction 7 between stands is performed, and the roll stands near the roll bite entrance 8 of the next stand.
The width of the roll bit has been reduced,
There is a width change behavior that the width spreads at. That, F ₃ and F ₄ between width measurement value does not throat no changes殆against the tension change between the rolling mill F ₃ and F ₄ in FIG. 1. On the other hand, it was found that the change in tension between F ₃ and F ₄ , and between F ₄ and F ₅ and the change in the finish exit side width correspond well. From this, it is clear that the change in plate width is due to the rear tension near the roll bite Was confirmed to have a large effect.

FIG. 4 is a diagram showing the relationship between the tension difference for each looper and the plate width strain. As shown in FIG. 4, in the No. 3 looper, the plate width distortion changes according to a certain curve with respect to the tension change in the A coil and the B coil. Further, FIG. 5 is a view showing the relationship between the tension difference for each looper and the plate width strain, similarly to FIG. 4, and shows the plate width strain with respect to the tension change of the C coil and the D coil in the No4 looper, and shows a constant straight line. You can see that it is changing according to.
In this way, it is shown that the tension and the plate width deviation at each stand have a correlation. The plate width strain is expressed as (width change amount) / (width before width change) × 100% as the width change rate, and tension change (kg / mm ² ) is the tension / (plate thickness + plate width) unit tension. Is displayed as. The means for controlling the rearward tension according to the present invention can be controlled by the current of the looper between the stands and the speed of the rolling mill, and also by the roll gap.

[0011]

EXAMPLES finishing mill group F ₁ tension value of the roll bite immediately before the sheet width meter and F ₃ stands between F ₃ to F ₄ stands located in the middle portion of the to F ₇ and F _4, F ₅ and The tension immediately before each roll bite of F ₆ is measured and sent to a computing device, and the tension correction amount calculation is based on the measured strip width and tension, and for the steel plate reaching F ₃ , the set reference tension is applied. The sheet width deviation from the target on the exit side of the finishing rolling mill is fed back by the tension values at F ₄ , F ₅ and F ₆ as if it passed between the stands, and a prediction calculation is performed. The tension for setting the measurement width deviation of the stand width meter used at this time to the target value is F
₃ Calculated on the stand just below the roll bite, and given as a rear tension just below this roll bite, the plate width is controlled.
By repeating these operations in sequence, the tension to be set between the stands is calculated, and then the difference from the reference tension is controlled as the tension to be corrected.

[0012]

As described above, according to the present invention, the inter-stand tension of the finish rolling mill is calculated for each stand immediately before the installation of the strip width gauge, and the rear tension immediately below the roll bite is controlled to control the tension. By controlling the strip width of the rolled material, it becomes possible to maintain the strip width on the delivery side of the rolling mill with a high precision of the target value.
This has an extremely excellent effect of improving the product yield by reducing the margin as much as possible.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for carrying out the present invention,

FIG. 2 is a diagram showing a tension state of a rolling mill,

FIG. 3 is a view showing a change in plate width between roll stands,

FIG. 4 is a diagram showing a relationship between a tension difference for each looper and a plate width strain;

FIG. 5 is a diagram showing a relationship between a tension difference for each looper and a plate width strain.

[Explanation of symbols]

 1 rolled material 2 finishing rolling mill 3 tension detection device between stands 4 strip width gauge 5 computing device 6 just under the roll bit 7 strip width shrinking 8 roll bit near the entrance 9 roll bit

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[Procedure amendment]

[Submission date] April 28, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

FIG. 2 is a view showing the tension state of the rolling mill.
As shown in FIG. 2, the material 1 to be rolled is directly below the roll bite 6
In, the forward tension and the backward tension are acting as shown by the arrow. Further, FIG. 3 shows the situation in detail.
FIG. 3 is a diagram showing a change in plate width between roll stands. As shown in the figure, plate width reduction such as plate width reduction 7 between stands is performed, and the roll stands near the roll bite entrance 8 of the next stand.
The width of the roll bit has been reduced,
There is a width change behavior that the width spreads at. That is, the tension change between the rolling mills F _{3 to} F ₄ shown in FIG.
However, the width change is detected by the stand width meter between F _{3 and} F _4.
I couldn't, and I could detect it with the width meter on the exit side. this child
To the stand just before the stand width meter.
This is to control the tension by pulling back.

Claims (1)

[Claims] 1. A method for controlling a strip width by controlling a tension between stands, wherein a strip width meter is installed between stands, and a strip width gauge is installed to set a tension for setting a deviation of the strip width meter to a target value. A method for controlling the strip width in finish rolling, which is calculated for each stand immediately before and is applied as a rear tension just below the roll bite to control the strip width.