JPS6024722B2 - Reduction correction rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reduction correction rolling method, particularly when a locally treated slab or a continuously cast slab having width taper, width shrinkage, etc. is used as a material to be rolled. A preferable method is to change the roll rolling calendar during rolling to give a thickness change in the rolling direction of the rolled material (hereinafter referred to as reduction correction rolling), and then turn this rolled material 90 degrees and roll it to improve the flatness of the rolled material after rolling. This invention relates to an improvement in a rolling method for correcting the reduction of thick plates so that the shape approaches a rectangle.

Generally, slabs manufactured in continuous casting equipment etc. are cut into products after undergoing forming rolling, tentering rolling, and finishing rolling in a plate rolling mill. Depending on the difference, the shape will be as shown in FIG. IA or FIG. IB.

That is, the edge portions 10A and 12A of the rolled materials 10 and 12 are as follows.
The center portion is narrower or wider than both end portions, and the cropped portions 10B and 12B have many cropped portions to protrude or recess outward in the longitudinal direction to obtain the product size 14. If these defective portions exist, it is necessary to shear the defective portions using a shearing machine or the like after rolling, resulting in a reduction in rolling yield. Conventionally, methods for improving the planar shape after rolling have included modifying the cross-sectional shape of the slab, modifying the rolling roll shape, using a rolling method to correct rolling by changing the roll gap during rolling, or optimizing the rolling schedule. Various methods have been proposed.

Among these, in the plate rolling method including reduction correction rolling,
Conventionally, after correcting the cross-sectional shape in the rolling direction by reduction correction rolling, normal reverse rolling was performed during the rolling process in which the material to be rolled was rotated 900 times. Here, normal reverse rolling refers to a case in which the number of passes is minimized in order to improve rolling efficiency, and rolling is carried out with the maximum rolling reduction within the range permitted by the equipment.
That is, for the pincushion-shaped edge portion 10A, a rolled material 16A with a thick longitudinal cross section as shown in FIG. 2A is used, and on the contrary, for the drum-shaped edge portion 12A, a thin rolled material 16A is used as shown in FIG. 2B. The rolled material 16B is formed by changing the roll gap in the final pass of forming rolling (in the direction of arrow A), and then in the subsequent tentering rolling (in the direction of arrow B) which is perpendicular to this forming pass.
direction), the edge portions are made to approach a straight line. Similarly, for the protruding crop part 1OB, by changing the roll gap, the central part of the longitudinal cross section is thinner as shown in Fig. 2C, and for the depressed crop part 12B, it is thicker as shown in Fig. 2D. Rolled material 16C, 16D
are formed in the final pass of tentering rolling, and the subsequent finish rolling in a direction perpendicular to this makes the cropped portion close to a straight line, so that a planar shape close to a rectangle is obtained after rolling. This reduction correction rolling method is very effective when the slab shape is good, but for example,
Slabs that have undergone local maintenance, slabs that have tapered joints when the width is changed due to continuous casting materials, or
Similarly, when correction rolling is performed on a slab with a poor shape, such as a slab whose width is contracted at the leading and trailing ends of a continuous cast material, the planar shape of the rolled material after rolling is not necessarily good. There was a problem that the shape could not be obtained.

That is, for example, as shown in FIG. 3, when conventional reduction correction rolling is performed on a width nervous slab 20 having a tapered planar shape, the planar shape of the finally obtained rolled material 22 is the 4th A. The result will be as shown in the figure. Although this is a better planar shape than the planar shape obtained by normal rolling as shown in Figure 4B, the influence of the width taper of the slab 20 remains, and the shape is completely rectangular. I couldn't get the shape. In addition, in the case of a slab whose width is contracted at the leading edge or the trailing edge, for example, when correction rolling is performed to improve the drum shape, the planar shape of the rolled material 24 finally obtained is as follows. It becomes as shown by line A in Fig. 5. Although this is a better shape than the case where reduction correction rolling is not performed (solid line B), the influence of width shrinkage remains at the tip C, and a perfect rectangle (solid line D) is still obtained. I couldn't do that. This is the 6th
As shown in Figure A, because the local treatment was performed on a part of the surface, the cross-sectional shape of the local treatment area E is smaller than the cross-sectional shape of the normal area (Figure 6C), as shown in Figure 6B. The same applies to the local maintenance slab 26. The present invention has been made to solve the above-mentioned conventional drawbacks, and includes slabs with locally treated areas, slabs with a width boupa shape,
Alternatively, it is an object of the present invention to provide a method for rolling a thick plate that can obtain a good planar shape of the rolled material close to an accurate rectangle even when using a rolled material with a defective shape such as a slab that has undergone width contraction. purpose.

The present invention changes the roll rolling calendar during rolling in the final pass of forming rolling in which forming rolling is followed by tentering rolling and then finishing rolling, thereby changing the thickness of the rolled material. In the reduction correction rolling method, which improves the width shape of the rolled material after rolling by performing tentering rolling with 900 turns, the strip width or equivalent strip width distribution in the longitudinal direction of the rolled material is determined in advance, and the longitudinal distribution of the equivalent strip width is determined in advance. The above object is achieved by modifying the lower layer of roll rolling in the final pass of forming rolling so as to obtain a longitudinal distribution of the cross-sectional area of the rolled material corresponding to the targeted width shape of the rolled material after completion of rolling. This is how it was done.

Further, the plate width or equivalent plate width of the rolled material is determined by substituting the measured value of the rolling load into the rolling load formula.

The present invention will be described in detail below with reference to the drawings.

Now, assuming that the target intermediate shape of the rolled material 28 after reduction correction rolling and before final rolling is as shown in FIG. 7A, the longitudinal distribution of the cross-sectional area Sx of the corresponding rolled material 28 is , as shown in FIG. 7B. Therefore, in order to obtain such a longitudinal distribution of the rolled cross-sectional area, the lower pupil of the roll during reduction correction rolling is corrected based on the longitudinal distribution of the plate width or equivalent plate width of the rolled material determined in advance. Bye. For example, when a slab with a tapered slab width is subjected to normal reduction correction rolling, the longitudinal distribution of the cross-sectional area Sx of the intermediate rolled material becomes as shown in Fig. 8, and as shown in Fig. 4A. As a result, the final planar shape of the rolled material 22 also becomes tapered. Therefore, the required correction thickness during reduction correction rolling is calculated according to the plate width of the material to be rolled (equivalent plate width in the case of locally treated slabs) that has been measured or calculated in advance, and the lower layer of the roll is adjusted accordingly. Just modify it to 0. Examples of the present invention will be described in detail below. Now, when performing reduction correction rolling on a slab with a normal plate width (180 mm) and a good shape, the cross-sectional area Sx of the intermediate rolling village after forming rolling corresponding to the target planar shape of the rolled material When the longitudinal distribution of is as shown in FIG.
As shown in the figure, the width of the slab plate varies from 170 mm to 180 mm (slab size 22 mm).
0 x (1700-1800) x 300 enemies),
Let us consider the case where the reduction correction rolling according to the present invention is performed. First, the distribution of the target plate thickness Hx during the secondary reduction correction rolling is as shown in FIG. 11, since the plate width of the slab is considered to be uniform. However, in the case of the present invention, since the slab has a width taper, the distribution of the target plate thickness Hx during reduction correction rolling is based on the law of constant volume.
As shown in the figure, for the tip with normal plate width,
It is possible to obtain the same plate thickness as in conventional reduction correction rolling, and to obtain a larger plate thickness than in normal reduction correction rolling at the rear end portion, which is narrower than the normal width of the plate. Thereby, as shown in FIG. 13, a final rolled material 22 having a planar shape close to a normal rectangle can be obtained. Specifically, it is performed as follows.

m Actual measurement or online calculation of the slab width WX (actual measurement of the equivalent slab width in the case of locally treated slabs) ■ Longitudinal distribution of the cross-sectional shape Sx of the intermediate rolled material corresponding to the target final planar shape of the rolled material (3) Calculation of the longitudinal distribution of the plate thickness Hx necessary to obtain the longitudinal distribution of the cross-sectional area Sx of the rolled material. (4) Calculation of the longitudinal distribution of the plate thickness H. The rolling screw position corresponding to (roll rolling lower layer) S.

Calculation Next, each of the items (1) to '4} above will be explained in detail.

(1- slab width (equivalent slab width in case of local care)
For example, the width of the slab after the first pass of forming and rolling can be measured using a plate width meter using a photoelectric element.

In this case, the thickness of the plate becomes equal in the longitudinal direction due to the first forming pass of forming and rolling, so even in the case of a locally treated slab, the equivalent slab width was determined by actually measuring the plate width. Note that the equivalent slab width is as follows.

That is, if we consider a slab 26 whose surface has undergone local treatment E as shown in FIG. It shows the behavior of That is, the cross-section of the normal part of this local care slab 26 has a normal cross-sectional shape with the plate width W and the plate thickness t as shown in FIG. 6C, but the cross-section of the local care part E is as shown in FIG. 6B. As shown, the cross-sectional area of the slab 26 is reduced by the removed area s corresponding to the local care portion E. Therefore, the area E where such local care has been applied
The equivalent slab width W in this case is calculated, for example, by the following equation. W'=(txw-0.2xs)/t...
...{1-Here, the coefficient of 0.2 for the removed area s is based on the knowledge that the effect of the removed area in the width direction is about 20% as a result of an experiment. Therefore, in the case of a locally treated slab, the distribution of this equivalent slab Nakatomi W' in the longitudinal direction of the slab is determined. Further, when calculating the slab width W on-line, it is determined as follows.

That is, the rolling load formula is generally expressed by the following formula. P:KO
‐Km‐Qp‐sod‐W ・・・‐・
-・[2] Here, P is rolling load, Km is average deformation resistance, Qp is rolling force, Kd is projected contact length, W is slab width,
Ko is a coefficient.

Therefore, the slab width W can be determined from the following equation by actually measuring the rolling load P.

W=KO. Km bow Qp. Sod・・・・・・【3
}That is, find the measured load distribution corresponding to the slab length x,
From this, it is also possible to determine the distribution of slab widths. ■ Next, the intermediate cross-sectional area Sx of the rolled material corresponding to the target final planar shape of the rolled material is determined by correcting the equivalent slab width to the rolled material cross-sectional area for which a prediction formula is created from the actual width shape. ,demand.

[3} The intermediate rolled material obtained in this way
．． From the longitudinal distribution of the cross-sectional area Sx, the required plate thickness H. The longitudinal distribution of is determined using the following equation. Criticism = Lecture ・
‐・‐‐‐[4)'4) Reduction screw position S corresponding to the required plate thickness Hx' calculated in this way.

is obtained as follows. That is, from the gauge meter type, the required plate thickness Hx' and screw position S. The following equation holds between . Criticism = S.

Toshima Tok ・--. ...[5} Here, F is the rolling load, M is the mill constant, and K is the constant. Therefore, the Shoshita screw position S. is determined by the following equation. S. =Critique-(White JyuK) -------■As explained above, according to the present invention, the local care slab, width taper slab,
Even when a slab with a defective shape, such as a width-shrinking slab, is used as a rolling material, Shoshita corrective rolling can finally obtain an accurate rectangle, which is an advantage in that it can significantly improve rolling performance. It has a great effect.

[Brief explanation of drawings]

Figures IA and IB are plan views showing a rolled material after general rolling, Figures 2A to 2D are perspective views showing a rolled material subjected to reduction correction rolling, and Figure 3 is a plan view of a rolled material after reduction correction rolling. 4A is a plan view showing the final product shape when the width taper slab shown in FIG. 3 is subjected to conventional reduction correction rolling, and FIG. 4B is a plan view showing the final product shape when the width taper slab shown in FIG. Fig. 5 is a plan view showing a comparison of the final product shape when a width shrink slab is subjected to conventional reduction correction rolling or normal rolling.
Figure A is a perspective view showing an example of a local care slab, Figure 6B
The figure is a sectional view taken along the line BB in Fig. 6A, and Fig. 6C is a sectional view taken along line BB in Fig. 6A.
Similarly, the sectional view taken along the line C-C in FIG. 6A and FIG. 7A are as follows.
FIG. 7B is a perspective view showing the shape of an intermediate rolled material after targeted reduction correction rolling, FIG. 7B is a diagram showing the longitudinal distribution of the cross-sectional area of the intermediate rolled material, and FIG. 8 is a width taper slab Figure 9 is a diagram showing the longitudinal distribution of the cross-sectional area of the intermediate rolled material after reduction correction rolling when conventional reduction correction rolling is performed on the slab. On the other hand, a diagram showing the longitudinal distribution of the cross-sectional area of the rolled material corresponding to the target intermediate shape of the rolled material after reduction correction rolling.
Fig. 0 is a diagram showing the longitudinal distribution of the plate width of the width taper slab used in the above example, and Fig. 11 is a diagram showing the intermediate rolled material after reduction correction rolling when conventional reduction correction rolling is performed. A diagram showing the target value of the longitudinal distribution of the plate thickness, FIG. 12 is a diagram showing the target value of the longitudinal distribution of the plate thickness of the intermediate rolled material after reduction correction rolling in the example according to the present invention. ,
FIG. 13 is a plan view showing the shape of a rolled material finally obtained in an example of the present invention. 20, 26... Slab, 22, 24, 28... Rolled material. Figure AFigure IBFigure 2AFigure 2BFigure 2CFigure 20Figure 3Figure 4AFigure 4BFigure 5Figure 6AFigure 6BFigure 6CFigure 7AFigure 7BFigure 8Figure 9 Figure 10 Figure 11 Figure 12 Figure 13

Claims (1)

[Scope of Claims] 1. In the final pass of forming rolling of thick plate rolling in which forming rolling is followed by tentering rolling and then finishing rolling, the roll rolling position is changed during rolling to change the thickness of the rolled material, and then this rolling is performed. In the reduction correction rolling method that improves the width shape of the rolled material after rolling by turning the material 90 degrees and performing tentering rolling, the longitudinal distribution of the plate width or equivalent plate width of the rolled material is determined in advance. In accordance with this, the roll rolling position in the final pass of forming rolling is modified so as to obtain a longitudinal distribution of the cross-sectional area of the rolled material corresponding to the targeted width shape of the rolled material after completion of rolling. A method of rolling with reduction correction. 2. The reduction correction rolling method according to claim 1, wherein the plate width or equivalent plate width of the rolled material is determined by substituting the measured value of the rolling load into the rolling load formula.