JPH11342411A - Plate width control for thick steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a side edge cutting off volume at a refining process and improve a product yield by measuring a plate width at plural points during rolling for controlling a rolling roll gap of the following pass in a manner to eliminate the width variation based on the measured width. SOLUTION: A steel plate is rolled with a rolling mill and a width of a steel plate 2 is measured by a width meter 3 in the midst of the rolling in the steel plate length direction at n numbers in a given pitch (for example, 10 mm). Based on the measured data, an operation device 4 adjusts a rolling roll gap of the following pass using a hydraulic pressure device 5. A width variation can thus be eliminated. Then, a gauge meter plate thickness correction volume required for compensating a measured width variation is calculated by the operation device 4. The correction volume is added to a target gauge meter thickness of each steel plate part at the following pass rolling. Also, a roll gap correction volume required for compensating the plate width variation is calculated, so as to add the correction volume to the target roll gap value of each steel plate part at the following pass rolling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the width of a thick steel plate manufactured through the steps of adjusting rolling, width rolling, and finishing rolling. The present invention relates to a sheet width control method for eliminating a change in a sheet width caused by a defective shape or the like.

[0002]

2. Description of the Related Art When a steel plate is manufactured by a reversible rolling mill using a slab manufactured by continuous casting or slab rolling as a material, first, the slab is rolled to a predetermined thickness by adjusting rolling to flatten the surface. After rolling, the slab is rotated 90 degrees and tentative rolling is performed.When the length of the rolled slab reaches the target width, the slab is rotated again 90 degrees, and then a steel plate having the target thickness is obtained. In general, finish rolling is performed until finished.

[0003] In these rolling processes, the thickness, width, and length of the rolled steel plate are finished to target values to reduce the amount of edge truncation in the next refining process (shearing process). It is extremely important in improving the retention.
Of these, various studies have been made on the method of matching the sheet thickness to the target value, and sufficient control accuracy has been obtained, but the development of a method of matching the sheet width to the target value is not yet sufficient. .

As a technique for controlling the width of a thick steel plate, for example, there is a technique described in Japanese Patent Application Laid-Open No. 62-137114. This is done by measuring the length of the rolled material with a width / length meter in the final immediate pass of the tent rolling, and correcting the thickness after tent rolling based on the measured length. The subsequent plate length (product width) is to be kept at a target value.

[0005]

However, in the technique described in Japanese Patent Application Laid-Open No. Sho 62-137114, it is possible to make the plate width at a desired position in the longitudinal direction of the product coincide with the target value. However, fluctuations in the width of the steel sheet cannot be avoided.

[0006] The first factor among the typical causes of the width variation in the steel sheet is a skid mark. That is,
The slab, which is the raw material, is first heated in a heating furnace. At that time, as shown in FIG. 2 (a), the temperature of the part in contact with the skid in the heating furnace is lower than that of the other parts. At times, the deformation resistance of that part becomes larger than other parts. For this reason, the elongation of the skid mark portion in tent rolling becomes smaller than that of other portions, and the tent rolling is completed (90
At the end of the rotation), the width of the skid mark portion becomes narrow as shown in FIG.

[0007] In the subsequent finish rolling, the skid mark portion has a small spread, so that a steel plate having a narrow skid mark portion is obtained after the completion of the finish rolling, as shown in FIG. 2 (c).

A second factor that causes a width variation in the steel plate is a width variation in the plate due to local deformation of the rear end of the slab tip in a relatively thick region. This occurs because the material flows in the width direction of the plate due to the small restraining force of the material from the side at the front and rear ends of the plate. In the case of thick plate rolling, after the adjustment rolling, the slab is rotated 90 ° to perform tentative rolling, and then further rotated 90 ° for finish rolling. Therefore, the above deformation is combined, and the deformation is predicted (modeling). Makes it even more difficult.

[0009] A third factor that causes a variation in the width of the steel sheet is a defective shape of the slab material. In the case of manufacturing a product of a thin material (generally a thickness of 7 to 8 mm or less) in a thick plate, a slab manufactured by continuous casting is rolled to a certain thickness by a slab mill or a thick plate rolling mill (for example, Rolling to a thickness of 250 mm to 130 mm), may be rolled again after re-heating in a heating furnace. At that time, since the slab is three-dimensionally deformed as described above,
In many cases, the initial shape of the slab is not always rectangular.

FIG. 3 shows this state. In FIG.
Is a slab intermediate-rolled in this way, and has a non-rectangular shape. Further, as shown in FIG.
One slab may be cut into a plurality of small slabs, which may be heated and rolled. In this case, the shape of the small slab becomes complicated.

Further, in order to improve the surface properties of the slab, slab care for locally cutting the slab surface and the like are also performed, and this also complicates the initial shape of the slab and becomes a disturbance in controlling the width of the slab.

As described above, when the width of the steel sheet fluctuates at the time of completion of the finish rolling, it is necessary to previously set the average target width to be wider so that the narrowest portion becomes the product width. The amount of cut-off was increased, causing a decrease in yield.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a method for controlling the width of a thick steel plate, which can reduce the fluctuation of the width after finishing rolling.

[0014]

The first means for solving the above-mentioned problems is a method for controlling the width of a thick steel plate manufactured through each of the steps of adjusting rolling, width rolling and finish rolling. In the course of rolling, the sheet width is measured at a plurality of points, and based on the measured data, the gap between the rolling rolls in the next pass is adjusted so as to eliminate the sheet width fluctuation. This is a control method (claim 1).

In the present means, the gap between the rolling rolls is adjusted during the next pass rolling so as to eliminate the fluctuation in the sheet width based on the actually measured fluctuation in the sheet width. If the roll gap is narrowed, the plate thickness is reduced, and the width of the plate is increased by the transverse flow of the material. Conversely, when the roll gap is widened, the sheet width becomes narrow. Therefore, by adjusting the roll gap,
Plate width fluctuation can be eliminated.

A second means for solving the above-mentioned problem is as follows.
In the first means, the plate width of each part in the length direction is measured in the middle of rolling, and a correction amount of the gauge meter plate thickness necessary to compensate for the fluctuation of the measured plate width is calculated. In the pass rolling, the gap between the rolling rolls is adjusted by adding the correction amount to the target gauge meter plate thickness of each part of the steel plate (claim 2).

In this means, the correction amount of the gauge meter plate thickness required to compensate for the fluctuation of the measured plate width is calculated, and the gauge meter plate thickness is changed accordingly.
The gauge meter thickness control device is installed in the rolling mill as standard, so it is only necessary to add a correction input to this device, and it is necessary to control the width of the plate without newly installing a special control device. Can be.

A third means for solving the above-mentioned problem is as follows.
In the first means, during the rolling, measure the width of each part in the length direction, calculate the roll gap correction amount necessary to compensate for the fluctuation of the measured width, in the next pass rolling The gap of the rolling roll is adjusted by adding the correction amount to the target roll gap value in each part of the steel plate (claim 3).

In this means, the gap between the rolling rolls is directly changed without changing the gauge meter plate thickness as in the second means. Therefore, even in a rolling mill in which the gauge meter thickness control device is not installed (particularly, a rough rolling mill), the strip width control can be performed.

A fourth means for solving the above-mentioned problems is any one of the first means to the third means, wherein the adjustment of the gap of the rolling roll is performed in any pass during finish rolling. It is.

A fifth means for solving the above-mentioned problem is any one of the first means to the third means, wherein the adjustment of the gap between the rolling rolls is performed in the last pass of the tentative rolling. .

A sixth means for solving the above-mentioned problem is any one of the first means to the third means, wherein the adjustment of the gap between the rolling rolls is performed in the final pass of the adjustment rolling.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of equipment for implementing an embodiment of the present invention. In FIG. 1, 1 is a rolling mill, 2 is a steel plate being rolled, 3 is a width gauge, 4 is an arithmetic unit,
5 is a hydraulic pressure reduction device.

The width of the steel sheet 2 being rolled by the rolling mill 1 is
Then, n pieces are measured at a constant pitch (for example, 100 mm) in the length direction of the steel sheet, and the measured data is defined as W _i (n = 1,..., N). And that when the average value is W _ave, constant-width deviation [Delta] W _i is represented by _{ΔW i = W i -W ave ...} (1).

On the other hand, the arithmetic unit 4 detects the rolling load P and the roll gap S under no load in order to set the _delivery side thickness h during rolling to the target thickness h _aim, and then uses the gauge meter type to calculate the _delivery side thickness. Feedback control (AGC: automatic thickness control) for estimating the thickness h and correcting the roll gap so that the exit side thickness h becomes the target thickness h _aim even when the rolling load P fluctuates is performed.

That is, h = S + P / M (2) h _aim = S ₀ + P _L / M (3) Here, M: Mill constant S ₀ : Initial roll gap (roll gap at lock-on) P _L : Lock-on load

The exit thickness deviation Δh is given by: Δh = h−h _aim = (S−S ₀ ) + (P−P _L ) / M (4) Therefore, in order to make the exit thickness deviation Δh zero, ΔS = S−S ₀ = − (P−P _L ) / M The roll gap is changed by the hydraulic pressure reduction device 5 by ΔS determined by (5).

In the first embodiment of the present invention, the target plate thickness h _aim is changed according to the measured plate width. That is, _assuming that the width change amount corresponding to the unit plate thickness change amount is α, h _aim ′ _i = h _aim + k ₁ · ΔW _i / α (6) Change the thickness (target gauge meter thickness). h _aim ' _i indicates a target sheet thickness when the measurement point at which the sheet width measurement value is ΔW _i bites into the rolling mill. Here, α is determined in advance by experiments or the like. Also, k ₁ is a correction coefficient, suitably determined by experiments or the like. By changing the target sheet thickness by the equation (6), the gap of the rolling roll is changed via the equations (4) and (5), and as a result, the sheet width does not fluctuate.

In the second embodiment of the present invention, the arithmetic unit 4 directly changes the roll gap without changing the target gauge meter plate thickness of the next pass. _{That, ΔS i = - (P-} P L) / M + k 2 · β · ΔW i ... and so that (7), rolls when the measuring point plate width measurement is [Delta] W _i is bitten into the rolling mill Determine the gap ΔS _i ,
The roll gap is changed by the hydraulic pressure reduction device 5. Here, the coefficient β is determined in advance by experiments or the like.
Is expressed as β = (M + K) / (αM) (8), where K is the plasticity coefficient of the material. K ₂ is a control gain, which is determined by adjustment in actual rolling.

In the first and second embodiments, when the gauge meter thickness control device is installed, the input for the width control is simply added as a correction input to the gauge meter thickness control device. Since it is possible, it has the feature that the equipment cost can be reduced.

When the rolling mill is a rough rolling mill and a gauge meter thickness control device is not installed, the roll gap change amount is ΔS _i , and ΔS _i = k ₂ · β · ΔW _i (9) What should be determined. The meanings of coefficients and the like are the same as in equation (7).

As described above, the control of the sheet width by changing the roll gap may be performed in the final pass of the adjustment rolling, may be performed in the final pass of the tentative rolling, and may be performed in an appropriate pass during the finish rolling. May be performed.

[0033]

As described above, in the present invention, the sheet width is measured at a plurality of points in the middle of rolling, and based on the measured data, the gap of the rolling roll in the next pass is eliminated to eliminate the sheet width fluctuation. Since it is adjusted as described above, even in a plate rolling mill without an edger, the fluctuation of the plate width in the longitudinal direction of the thick steel plate is significantly suppressed, and as a result, in the refining process, the amount of side edge cut off is reduced, Product yield can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of equipment for implementing an embodiment of the present invention.

FIG. 2 is a diagram showing a cause of a width variation of a thick steel plate in the related art.

FIG. 3 is a diagram showing the shape of a slab that has been subjected to intermediate rolling and the shape of a divided slab.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Rolling machine 2 ... Steel plate 3 ... Width gauge 4 ... Calculation device 5 ... Hydraulic pressure reduction device 6 ... Intermediate-rolled slab

Claims (6)

[Claims] 1. A method for controlling the width of a thick steel plate manufactured through each of the steps of adjusting rolling, width rolling, and finish rolling. A method of controlling the width of a thick steel plate, wherein the gap between the rolling rolls in the next pass is adjusted based on the following formula so as to eliminate fluctuations in the width of the plate. 2. A method for controlling the width of a thick steel plate according to claim 1, wherein the width of each portion in the length direction is measured during rolling to compensate for the fluctuation of the measured width. Calculate the required gauge meter plate thickness correction amount, in the next pass rolling, by adding the correction amount to the target gauge meter plate thickness of each part of the steel plate, to adjust the gap of the rolling roll, Sheet width control method. 3. The method for controlling the width of a thick steel sheet according to claim 1, wherein the width of each part in the length direction is measured during rolling, and the fluctuation of the measured width is compensated. Calculating a necessary roll gap correction amount, and in the next pass rolling, by adding the correction amount to a target roll gap value in each part of the steel sheet, adjusting the gap of the rolling roll, wherein the width control method of a thick steel plate . 4. The method for controlling the width of a thick steel sheet according to claim 1, wherein the gap of the rolling roll is adjusted by any one of the passes during finish rolling. A thickness control method for a thick steel plate. 5. The method for controlling the width of a thick steel sheet according to any one of claims 1 to 3, wherein the adjustment of the gap between the rolling rolls is performed in the final pass of the tentative rolling. A method for controlling the width of a thick steel plate. 6. The method for controlling the width of a thick steel sheet according to any one of claims 1 to 3, wherein the adjustment of the gap between the rolling rolls is performed in a final adjustment rolling pass. Characteristic thickness control method for thick steel plate.