JPS5870903A - Rolling method for thick plate - Google Patents

Abstract

PURPOSE:To decrease the broadside shape defects of products after the end of rolling by performing edging at the broadside rolling reduction calculated by the length of the fish tails produced from dogbones, the remaining broadside rolling ratio after edging and the broadside shape produced by broadside rolling. CONSTITUTION:A broadside rolling ratio alpha is calculated from rolling width/slab width and a broadside shape margin Smm. is calcualted by the equationI. Thereafter a fishing length FTmm. is calculated by the equation II from the remaining broadside ratio alpha' after broadside edging and the margin Smm.. From the fishing length FTmm. obtained by the calculation, broadside rolling reduction DELTAW is calculated by the equation III. Slabs are subjected to broaside rolling by using the broadside rolling reduction DELTAW, whereby the fluctuations in the width of the products after the end of the rolling are decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thick plate rolling method, in particular, performs at least one pass or more of edging rolling during tenter rolling, thereby reducing the need for the width shape of the finished product after rolling. The present invention relates to a modification of the thick plate rolling method that has been improved.

In general, in thick plate rolling, a slab manufactured by an X-ray shunt rolling mill in continuous casting equipment is first subjected to 1 to 8 passes of forming rolling to adjust the scoop thickness, and then rolled by 90°. Then, after carrying out width ratio rolling for the required number of passes to obtain a predetermined plate width, the plate is further turned 900 times to return to the original direction, and finishing rolling is performed for the required number of passes to obtain the desired plate thickness. Based on the differences in rolling conditions between the thick steel edges and the center of the target plate thickness, plate width, and plate length, the planar shape line of the finished product (steel plate after rolling) is determined as shown in Figures 1 and 2. The width of the finished product is as shown in FIG. As shown in Figure 2, it has a nine-drum shape with wider front and rear ends. This is particularly caused by tentering rolling, and the sill shape differs depending on the relationship between the slab dimensions and the finished dimensions. Figure 3 shows that it is known that if the value is less than about 1.5, the drum shape will be as shown in Figure 2, and if it is more than 1.5, it will be the drum shape as shown in Figure 1. The amount is also known quantitatively, as shown in FIG. In Figure 3, the width shape formula S on the vertical axis
1 or 2, the plate width M at the center in the longitudinal direction of the product 10 and -1-B-1→.

In preparation for such shape defects, especially @shape &, conventionally, as shown in Fig. 1 or 2, the target product 16
The finished product 10 was finished to the dimensions plus an allowance, and then cut to the required width using a shear or gas to form the product 16. Therefore, the current situation is that the margin is quite large, and the yield rate is decreasing.

Conventionally, methods such as rounding, improving the pass schedule, diagonal rolling, or correction rolling have already been proposed to reduce the cutting allowance and improve the yield of rolled products. However, even in reduction correction rolling, which is the most advanced technology among these, the planar shape after reduction correction rolling is as shown in FIG. 4, and the width varying portion 18 at the leading and trailing ends has not been completely controlled. is the current situation.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and by performing edge rolling with an appropriate width reduction amount, it is possible to reduce the width fluctuation of the finished product after rolling, and therefore, the yield can be improved. Furthermore, it is an object of the present invention to provide a thick plate rolling method that can produce a copper plate that does not require edge cutting.

The present invention provides a thick plate rolling method in which edge rolling is performed for at least 41 passes or more during tentering rolling to reduce defects in the width shape of the finished product after rolling. , the product of the fishtail length (on one side) that occurs when the dog bone produced in edge rolling is horizontally rolled, the tenting ratio of the residue after edge rolling, and the drum-shaped width shape equation (both sides) that occurs in tenter rolling.
The above objective can be achieved by rolling the material in such a manner that the amounts match.

Generally, when a rolled material is subjected to edge rolling and then subjected to normal horizontal rolling, a fishtail occurs at the rear end of the rolling tip. The present invention actively utilizes this fishtail to make the width rectangular. The present invention will be described in detail below. As mentioned above, the width fluctuation of the finished product is largely caused by the tentering rolling, and the change in planar shape due to the tentering rolling will be examined in detail. As is already known, as shown in FIG. 5, as horizontal rolling continues, the rear end of the rolling tip becomes convex. Among these, the unsteady deformation region is almost constant in normal rolling, and is about 400 to 60 ow from the edge.The convex portion at the front and rear ends after tentering rolling is rotated 90 degrees and finished rolling. The width of the final product is equivalent to the width of the final product, making it drum-shaped. Therefore, in order to eliminate defects in the width shape of the product, it is important to first aim to make the width rectangular at the time of completion of tentering rolling.

By the way, edgers are widely used in hot rolling to improve the width accuracy of finished products, and edgers are sometimes used for rounding for this purpose even in thick plate rolling. When using Eziya, the 6th
As shown in the figure, there is a raised part 22 called a dog bone near the edge rolled down by the vertical roll 2o of the edger.
When normal horizontal rolling is performed after this ninth step, as shown in Fig.
is stretched in the rolling direction, a fishtail 24 occurs at the rear end of the rolling tip, and width fluctuations also increase. Therefore, in general, this edging rolling has a negative effect on the planar shape.
However, in the present invention, on the contrary, the dog bones produced in the edge rolling are actively used to reduce the drum shape caused by the tentering rolling. It was a harmonious experience. That is, the amount corresponding to the width shape equation of the drum shape produced in tentering rolling is offset by the fishtail produced when the dogbone produced in edge rolling during tentering is horizontally rolled.

FIG. 8 shows the width reduction amount ΔW (匈) (both II) when horizontal rolling is further performed after the edging rolling.
The relationship between fishtail length FT (pith) (one side) is shown.

The relationship between the two is expressed, for example, by the following equation.

FT=-8+〇, 92ΔW ・−・・・・・・・(11
On the other hand, the width ratio α and the width shape formula 8 (s
m) (both sides) relationship line, for example, expressed by the following equation.

5=-170+114α (2) Therefore, the width reduction amount ΔW of the above equation (13) may be determined so as to satisfy the relationship of the following equation.

Here, α' is the tentering ratio of the remaining material after death which is subjected to tentering edge rolling.

Examples of the present invention will be described in detail below.

Table 1 below shows the pass schedules in the conventional example and the embodiment of the present invention. In Table 10, the reason why a horizontal rolling pass was taken as the first tentering pass was due to a problem with the pass schedule. Furthermore, the purpose of using an even number of etching passes is to prevent asymmetry. In the above pass schedule, the overall tenting ratio α is 240. ．． 4, the width shape S (on both sides) is 104 m according to the above-mentioned equation (2).

On the other hand, since the tenting ratio α' of 20 mm after the edge rolling in the example of the present invention is '100=2'', the fishtail length FT (one side ) is 23.6 m from the above equation (3). Therefore, from the above equation (1), the necessary width reduction amount ΔW of the etching rolling is 34.4 m. In this example, , since the etching rolling is performed in two passes, rolling is carried out with a pass schedule that exceeds the width pressure in each pass, and the width shape formula (drum type) S of the final product is 113 m11 in the conventional example. In contrast to the case of 9, it was confirmed that in this example, the reduction was reduced to a negative degree of 112W.

By reducing the need for width shapes, the steel plate and therefore the yield rate can be improved, and this has the excellent effect of making it possible to manufacture steel plates that do not require edge cutting.

[Brief explanation of the drawing]

1 and 2, a plan view showing an example of the planar shape of the final product in conventional thick plate rolling; FIG. 3 is an lfM diagram showing the relationship between the export ratio and the width shape formula in thick plate rolling; FIG. 4 is a plan view showing an example of the planar shape after conventional rolling correction rolling, and FIG. 5 is a plan view showing a change in the planar shape after horizontal rolling. Figure 6 is a cross-sectional view showing the state in which dog bones occur during edge rolling, and Figure 7 is
Fig. 8 is a plan view showing the fishtail occurrence after horizontal rolling of the edge-rolled material. 01O... finished product, 22... is a diagram showing the relationship between lengths.
・Dotsugubone, 24...Fishtail. Agent Takaya Ron (and 1 other person) Figure 1 Figure 2 Figure 3 Comparison of width widths (rolled width/slave width 7)

Claims (1)

[Claims] (1) In a thick plate rolling method in which at least one pass or more of edge rolling is performed during tentering rolling to reduce the need for a width shape of the finished product after rolling, the amount of width reduction in the edge rolling is The product of the fishtail length (on one side) produced when horizontally rolling the dogbone produced during rolling and the tenting ratio of the remaining after edge rolling, and the drum-shaped width shape formula (on both sides) produced by tentering rolling.
A method for rolling a thick plate, characterized in that rolling is carried out on the surface so that the .