JPH05123718A - Vertical roll for hot rolling and edging method by using this roll - Google Patents

Abstract

PURPOSE:To improve the yield of a product by providing grooves in the peripheral direction of a roll at a position corresponding to the side face end parts of a slab subjected to edging. CONSTITUTION:This vertical roll 1 is used for edging in hot rolling. Grooves 2, 3 are provided in the peripheral direction of the roll 1 at least at the position corresponding to one of the upper and lower ends of the side face of the slab subjected to edging. Each of the grooves 2, 3 has a depth (b) of >=3% of the thickness of the slab 10 and an opening width (d) of >4 times the depth (b) of this groove. When the slab is subjected to edging the amt. of edging in the center part of the slab 10 is made >1 time and <=5 times the groove depth (b) of the roll. In this way, the cutoff of the end part of a product coil can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical roll which contributes to the suppression of linear defects generated in a steel sheet after hot rolling, and a width rolling method using the vertical roll.

[0002]

2. Description of the Related Art Hot rolling of steel sheets is carried out as shown in FIG.
The slab 10 produced in the continuous casting factory, when the slab temperature is low, after charging the heating furnace 11 and heating to a predetermined temperature,
200 to 30 by rolling multiple times with a rough rolling mill in which one or more vertical roll rolling mills 12 and one horizontal roll rolling mill 13 are arranged.
A slab having a thickness of about 0 mm is reduced to a sheet bar having a thickness of about 20 to 40 mm, and then finish rolling is performed by a finish rolling machine 14 including a group of horizontal roll rolling machines to obtain a product coil 15.

In the rolling by the above-mentioned horizontal roll rolling machine, the side surface of the slab is deformed without being constrained, so that wrinkles and cracks are generated in this side surface portion, and while these defects are rolled up to the product coil, the The linear flaw 16 extends around the upper and lower surfaces of the product coil and extends parallel to the rolling direction, as shown in FIG. Since the portion where the linear flaw 16 occurs is not a product, it is necessary to shear and remove the coil width end portion. Therefore, in order to reduce the removed portion, there has been proposed a method of reducing the maximum wraparound amount e of the linear flaw 16 from the coil width edge shown in FIG.

For example, in Japanese Patent Publication No. 50-14632, as shown in FIG. 3, the slab 1 may be width-rolled by a caliber edger 17 having a convex shape in the bottom to make the side surface of the slab concave in the plate width direction. Japanese Patent Laid-Open No. 52-41151 discloses a method in which the convex portion of the bottom-convex convex caliber edger is 5% or more of the rolled material thickness. Further, Japanese Patent Laid-Open No. 58-138502 discloses that the side surface shape of the slab described in the above publication is manufactured by continuous casting.

[0005]

Generally, when the thickness of the hot rolled slab is reduced to the thickness of the sheet bar, width rolling may be repeated a plurality of times with the same vertical roll. Since the thickness of the slab often differs depending on the steel type, the slabs having different thicknesses are width-rolled by the same vertical roll. If the caliber edger described in the above-mentioned publication is used for this width rolling, a slab having a thickness larger than the caliber bottom width is disadvantageously difficult to be width-rolled at the caliber portion. Therefore, it is necessary to replace the vertical roll depending on the slab thickness, which impairs the productivity in hot rolling. On the other hand, the method of denting the central portion in the thickness direction of the side surface of the slab described in the above publication by continuous casting requires more facilities, steps, etc., and is not necessarily a good measure from the viewpoint of manufacturing cost. Therefore, an object of the present invention is to propose a vertical roll for hot rolling which can advantageously solve the above problems, and a width rolling method using this roll.

[0006]

SUMMARY OF THE INVENTION The inventors have found that linear flaws generated at the plate edge of a stainless steel hot-rolled sheet lower the product yield, so that the linear flaws shown in FIG. When a width rolling method capable of suppressing the amount e was examined, it was confirmed that it was effective to make the side surface of the slab concave.
The slab side surface is dented by a hot rolling process, and further, the upper end and / or the lower end of the slab side surface is width-reduced by the groove part provided on the peripheral surface of the vertical roll, and the upper end part of the slab side surface and / or The present invention has been completed based on the finding that it is advantageous to make the width reduction amount at the lower end portion smaller than the width reduction amount at the widthwise central portion of the slab side surface (hereinafter referred to as "slab side surface central portion"). ..

That is, the present invention relates to a vertical roll used for width rolling in hot rolling, in which a groove is formed in the roll circumferential direction at a position corresponding to at least one of the upper end and the lower end of the side surface of the slab subjected to the width rolling. It is a vertical roll for hot rolling provided. In this case, it is advantageous in practice that the groove has a depth of 3% or more of the slab thickness and the opening width of the groove exceeds four times the groove depth.

Further, according to the present invention, when the slab is width-rolled by using the above-mentioned vertical roll for hot rolling, the width reduction amount in the central portion of the thickness of the slab is set to 5 times or less than 1 times the groove depth of the roll. The width rolling method is characterized in that

FIGS. 4 and 5 show the cross section of the vertical roller 1 for hot rolling according to the present invention only on one side of the center of rotation thereof. As shown in FIG. 4 (b), the vertical roll 1 shown in FIG. 4 has grooves 2 and 3 provided in the roll circumferential direction at positions corresponding to the upper end and the lower end of the slab 10 width-reduced by the roll. It will be done. In addition, the vertical roll 1a shown in FIG.
Is an example in which the groove 2a is similarly formed at a position corresponding to the upper end of the slab. Although not shown, it goes without saying that the groove may be formed only at the position corresponding to the lower end of the slab.

[0010]

With a vertical roll having grooves formed according to the present invention,
The fact that the slab side surface can be recessed in the width rolling step of hot rolling can be realized from the view shown in FIG. 4 (b). By denting the side surface of the slab, it is possible to reliably avoid the wraparound on the upper and lower surfaces of the linear flaw generated on the side surface of the slab.

That is, when the vertical roll shown in FIG. 4 is used for the first pass of rough rolling in the hot rolling line of FIG.
Fig. 6 shows the relationship between (the amount of width reduction in the central part of the side surface of the slab / the groove depth b) and the maximum wraparound amount e of the linear flaw in the product coil.
Shown in. In the vertical roll, as shown in FIG. 4 (a), the center distance a between the grooves 2 and 3 was 200 mm, and the groove depth b was 200 mm.
The width was 12 mm, the groove bottom width c was 20 mm, the groove opening width d was 80 mm, and the roll diameter was 800 mm. The rolling conditions are as shown in Table 1.

[0012]

From the figure, the maximum wraparound amount e of the linear flaw is 15 mm when the width reduction amount is more than 5 times less than 1 times the groove depth.
From the following, it can be seen that a significant reduction can be achieved compared to the conventional level. Here, in consideration of the width variation amount of the product coil, the amount of meandering or the edge cutting margin resulting from these, the maximum wraparound amount e of the linear flaw is suppressed to 15 mm or less in order to improve the product yield. It is advantageous.

Next, the results of experiments conducted on the shape of the groove formed on the vertical roll will be described in detail. First, FIG. 7 shows the relationship between (groove depth b / slab thickness) and the maximum wraparound amount e of the linear flaw in the product coil. The experimental conditions were the same as the experiment shown in FIG. 6 except that the groove opening width d was 84 mm and the width reduction amount at the center of the side surface of the slab was 36 mm. As shown in the figure, when the groove depth b is 3% or more of the slab thickness, the maximum wraparound amount e of the linear flaw is reduced to 15 mm or less.

Further, the relationship between the groove opening width d / the groove depth b and the maximum wraparound amount e of the linear flaw in the product coil is shown in FIG.
Shown in. The experimental condition is that the groove depth b is 6% of the slab thickness.
The experiment is the same as the experiment shown in FIG. 7 except that it is 12 mm. As shown in the figure, by setting the groove opening width d in a range exceeding four times the groove depth b, the maximum wraparound amount e of the linear flaw is
It can be reduced to 15 mm or less. In addition, it is preferable that the upper end portion and the lower end portion of the slab are pressed down at a half of the groove opening width d.

[0016]

EXAMPLE The vertical roll of FIG. 4 was applied to the first pass of rough rolling of the hot rolling line shown in FIG. 1, and 10 slabs were hot rolled under the conditions shown in Table 1. The vertical roll is
As shown in FIG. 4 (a), the center distance between the grooves 2 and 3 is 200 mm, the groove depth is 12 mm, and the width of the groove bottom is 20 m.
m, the groove opening width d: 80 mm, the roll diameter: 800 mm, and the width reduction amount at the center of the slab side surface was 36 mm. For comparison, the same hot rolling was performed using a conventional vertical roll whose sectional shape is shown in FIG. Table 2 shows the results obtained by examining the maximum wraparound amount e of the linear flaws in the product coil thus obtained.

[0017]

As shown in the table, in the product obtained by using the vertical roll according to the present invention, the maximum wraparound amount of the linear flaw was small. This tendency is the thickness of the same vertical roll
The same applies to the rolling of an austenitic stainless steel slab having a width of 200 mm and a width of 1200 mm, and similar effects can be expected even when the product width and the slab thickness are different in addition to this steel type. Even when a 260 mm thick plain steel slab is rolled using a vertical roll with a groove distance of 200 mm, the product surface edge is free from defects such as folds and ear scratches due to the effect of grooves. It turned out that it can be rolled in the same way as a normal vertical roll. Note that the vertical roll according to the present invention may be applied at any path and stand.

Next, in the hot rolling mill in which the above-mentioned embodiment was carried out, since the amount of linear flaws wrapping around the product surface was large, a vertical groove provided only at the position where the upper end of the side surface of the slab was width-rolled. The SUS430 steel slab was hot rolled using a roll. The rolling conditions at this time are the same as in Table 1. Further, the shape of the grooved vertical roll is as shown in FIG.
The groove 2 has the same shape. The results of examining the maximum wraparound amount of the linear flaws in the product coil thus obtained are shown in Table 3. When such a vertical roll is used, the wraparound amount on the product surface, which conventionally has a large wraparound amount, is reduced, As a result, the maximum wraparound amount could be reduced from 19 mm to 15 mm. In this way, it is also effective to provide a groove only on the side where the linear flaw wraparound amount is large, and in a hot rolling plant where the linear flaw wraparound amount is large on the back surface of the product, the slab side surface lower end is width-rolled. The same effect can be expected by providing the groove on the vertical roll only at the position.

[0020]

[0021]

As described above, according to the present invention, it is possible to reduce the wraparound amount of the linear flaw generated in the hot rolled coil. Therefore, the cut-off amount of the product coil end can be reduced, and the product yield can be remarkably improved.

[Brief description of drawings]

FIG. 1 is a schematic view showing a hot rolling line.

FIG. 2 is a schematic view showing a linear flaw in a product coil.

FIG. 3 is a cross-sectional view showing a caliber edger.

FIG. 4 is a cross-sectional view showing a vertical roll according to the present invention.

FIG. 5 is a sectional view showing another vertical roll according to the present invention.

FIG. 6 is a graph showing a relationship between (amount of reduction in width at the central part of the side surface of the slab / groove depth b) and a maximum wraparound amount e of the linear flaw in the product coil.

FIG. 7 shows the relationship between (groove depth b / slab thickness) and the maximum wraparound amount e of linear flaws in the product coil and the maximum wraparound amount of flaws other than linear flaws (folding flaws, ear crack flaws, etc.). It is a graph shown.

FIG. 8 is a graph showing the relationship between (groove opening width d / groove depth b) and the maximum wraparound amount e of the linear flaw in the product coil.

FIG. 9 is a cross-sectional view showing a conventional vertical roll.

[Explanation of symbols]

 1 Vertical roll 1a Vertical roll 2 Groove 3 Groove 10 Slab 11 Heating furnace 12 Vertical roll rolling machine 13 Horizontal roll rolling machine 14 Finish rolling machine 15 Product coil 16 Linear flaw 17 Caliber edger

Front page continuation (72) Inventor Masao Akita, 1 Kawasaki-cho, Chiba-shi, Chiba, Kawasaki Steel Co., Ltd. Technical Research Headquarters (72) Inventor Akio Adachi 1, Kawasaki-cho, Chiba-shi, Chiba Steel Works ( 72) Inventor Yoji Utashiro 1 Kawasaki-cho, Chiba, Chiba Prefecture Inside the Kawasaki Steel Co., Ltd. Chiba Works (72) Inventor Akira Kawarada 1 Kawasaki-cho, Chiba City Chiba Works Chiba Steel Co., Ltd.

Claims (3)

[Claims] 1. A vertical roll used for width rolling in hot rolling, wherein grooves are provided in the roll circumferential direction at positions corresponding to at least one of the upper end and the lower end of the side surface of the slab to be subjected to such width rolling. Vertical roll for hot rolling. 2. The vertical roll for hot rolling according to claim 1, wherein the groove has a depth of 3% or more of the slab thickness and an opening width exceeding 4 times the groove depth. 3. When the slab is width-rolled by using the vertical roll for hot rolling according to claim 1, the width reduction amount in the thickness central portion of the slab is more than 1 time and not more than 5 times the groove depth of the roll. And a width rolling method.