JPS5919766B2 - Manufacturing method of H-beam steel - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing H-beam steel.

Conventionally, H-section steel has been produced by heating a roughly shaped steel piece (beam blank) that is bloom-rolled from a steel ingot and then rolling it into a product using a universal mill.

In recent years, from the viewpoint of energy saving and yield, a method of directly rolling a continuously cast slab has been implemented.

In general, continuous casting slabs have no thickness in the steel ingot, so
With the conventional groove rolling method, it is not possible to form a rough-shaped steel piece with a large edge width.

Therefore, various new rolling methods have been proposed.

Some representative examples will be explained below.

First, the first method is to perform width reduction rolling in a rough rolling mill by using a number of box hole types in which the groove bottom width gradually increases, and sequentially changing the hole types with the width direction of the slab as the vertical direction. After deforming the steel into a dog-bone shape, the steel is rolled into a predetermined rough shape using a finishing die.

This method requires a large number of boxhole molds.

Normally, with only one rough rolling mill, it is difficult to form large-sized rough slabs for H-beam steel due to restrictions on roll body length.

The second method is to provide a convex projection in the center of the first box hole mold, thereby forming a concave groove in the center of the thickness direction of the slab. Width rolling is carried out while holding the material so that it does not fall over, forming the material into a dog-bone shape.Then, the recesses in the material are erased using a normal box hole die with a flat groove bottom, and the material is rolled into a predetermined rough shape using a finishing hole die. This is a method of forming pieces.

The third method is to directly machine the slab with a universal mill to form a predetermined rough shaped steel piece.

Universal mills usually do not have a vertical roll drive, so it is not possible to obtain a large reduction in the width direction in the initial pass.

All of the above-mentioned methods utilize a dog-horn deformation in which a slab, which is thinner than a conventional steel ingot, is reduced to a greater extent in the width direction, and the reduction does not penetrate into the center and only the edges swell.

In particular, in the case of wide H-beam steel, a width reduction of 500 wl1 or more is required.

In these conventional technologies, the reduction in the width direction is very large, so
A very large fish tail occurs at the leading and trailing ends of the rough-shaped steel piece, and the cropping amount after rough rolling is large, leading to a decrease in rolling yield.

Furthermore, since a considerable number of passes are required for rolling in the width direction, rolling efficiency is also significantly reduced.

When a slab with a large aspect ratio is stood perpendicular to its width direction and rolled down from above and below, the material tends to collapse during rolling, causing rolling flaws due to the side walls of the groove, and these flaws often remain in the product.

Therefore, an object of the present invention is to provide a rolling method that improves rolling yield, rolling efficiency, and quality using flat steel pieces such as continuously cast slabs.

The method for manufacturing H-beam steel of the present invention involves heating a flat steel slab, and rolling the flat steel slab in the width direction using a rough rolling mill having a plurality of box hole shapes provided with chevrons of a predetermined height and apex angle. The web part of the rough-shaped steel piece is rolled by a horizontal roll in a universal mill, and at the same time the web part of the rough-shaped steel piece is rolled by a vertical roll in a universal mill. It is characterized in that the flange portion is formed by gradually pushing open the slits in the pieces.

Next, the method of the present invention will be specifically explained with reference to the drawings.

First, a flat steel billet (hereinafter referred to as a steel billet) obtained by continuous casting etc.

See Figure 1A. ) is heated to a temperature of 1200° C. or higher in a heating furnace.

Next, slits of a predetermined shape are formed on both side edges of the steel piece (FIGS. 1B and C).

The slits are formed using a double reversible rough rolling mill (hereinafter referred to as BD mill), as shown in FIG.

) with a plurality of box holes having a predetermined shape 1. II.

■ Rough rolling is performed with the width direction of the steel billet being the top and bottom.

Each box hole type I, It, III, . . . has a chevron portion 1 of a predetermined height h and apex angle θ.

Each box hole type 1. The apex angle θ of the chevron portions 1 of II, III, . . . is approximately constant (60 to 80°), but the height h is set to gradually increase.

As shown in Figure 3A, the depth S of the slit formed in the steel piece is approximately half (S) of the flange width H of the product (Figure 3B).
Key H/2).

The rough shaped steel pieces obtained in this way are manufactured using a universal mill (hereinafter referred to as UR mill).

) and a double-hole shaping mill (hereinafter referred to as E-mill).

), and multiple passes of reciprocating rolling are performed.

In the UR mill, the horizontal and vertical rolls have a taper angle ψ of 5° or more, as shown in the first diagram.

At the same time as rolling down the web part of the rough shaped steel billet with horizontal rolls,
The vertical rolls gradually push open the slits on both sides of the steel slab, and after the inside of the flange of the steel slab touches the side of the horizontal roll (
D) in Fig. 1, the tip of the flange portion is shaped using an E mill, and then finished with a universal mill (hereinafter referred to as UF mill).

) to form a product in one pass (Fig. 1E).

<Example> An example of the method of the present invention will be described for H400X400.

FIG. 4 shows a mill layout in which the method of the present invention was implemented.

In Fig. 4, 2 is a heating furnace, 3 is a BD mill, and 4 is a first
UR mill, 5 indicates the first E mill, 6 indicates the crop saw, 7 indicates the second UR mill, 8 indicates the second E mill, and 9 indicates the UF mill.

A continuous casting slab with a material size of 18011 g, a thickness of 100 m, and a width of 100 m is heated to 1250°C in a heating furnace 2.
As shown in the figure, there are 8 box holes 1. II.

Rough rolling was carried out using a BD mill 3 with the widthwise direction of the slab as the upper and lower sides.

Each box hole type I, II, If of the roll of BD mill 3,
・・・・・・The height h of the chevron part of ■ is 40 and 8, respectively.
0,120,160°180.200,215,230
M, and the apex angle θ was 60°.

The hole type used depends on the flange width of the product.

In the case of H400x400, since this is the maximum flange width according to JIS, the hole types used are t, n, and m.

There are seven: IV, V, Vl, and ■.

Each hole type is treated as 1 pass, and only hole type ■ is treated as 3 passes, totaling 9
A slit with a depth of 230 m was formed on both side edges of the material by the pass.

The average reduction amount per pass at this time is 50111IIl
It is.

The rough shaped steel billet is then guided to a first intermediate universal mill group consisting of a first UR mill 4 and a first E mill 5.

As shown in FIG. 5, each roll hole type in the first UR mill 4 and the first E mill 5 has a taper angle ψ=30°, and the apex angle θ of the vertical roll in the UR mill 4 is 120°.

Here, 7 passes of reverse rolling are performed.

In the first four passes, the E mill 5 is not used, and the web part of the steel billet is rolled down with the horizontal rolls of the UR mill 4, and at the same time, the vertical rolls are gradually closed to push the slit open from 60° to 120°. Ensure flange width.

The open dimensions of this intermediate universal mill group are a web thickness of 451 NIl and a flange thickness of 70 m.

Next, a crop saw 6 is used to cut a crop of the web portion at the leading and trailing ends of the rolled material.

Next, a second UR mill 7 and a second E mill 8 are installed.
The material is guided to the intermediate universal mill group.

Taper angle ψ of each roll of UR mill 7 and E mill 8 =
5°, and the apex angle θ of the vertical roll of UR = 170
(Figure 6).

Here, by 5 passes of reverse rolling, the web thickness was 13.5
11g1, flange thickness 21.911J flange width 403
Each was rolled to M.

Finally, in UF Mill 9, H400 x 40 with ■ pass
Rolled to 0.

According to the method of the present invention, the yield is improved because large fish tails do not occur at the front and rear ends of the rough-shaped steel billet, and the flange width width is improved, so the rolling efficiency is improved by reducing the number of rolling passes. Since the thickness of the flat steel slab can be reduced, large-sized products can be manufactured with just one heating process.

[Brief explanation of the drawing]

FIG. 1 is a schematic process diagram showing the method of the present invention. Figure 2 is a front view showing the box hole type of the roll of the rough rolling mill used in the method of the present invention, and Figure 3 is a diagram showing the relationship between the depth of the slits provided on both sides of the steel billet and the flange width of the product. Partial cross-sectional view. FIG. 4 is a plan view of a mill layout implementing the method of the invention. FIG. 5 is a partial front view showing the shape of each roll of the first intermediate universal mill group. FIG. 6 is a partial front view showing the shape of each roll of the second intermediate universal mill group. 1: Yamagata section, 2: Heating furnace, 3: BD mill, 4: 1st UR
Mill, 5: 1st E mill, 6: Crop saw, T: 2nd
UR mill, 8: 2nd E mill, 9: UF mill.

Claims (1)

[Claims] 1 A flat steel slab is heated and gradually rolled in the width direction by a rough rolling mill having a plurality of box holes with chevrons of a predetermined height and apex angle, so that a predetermined shape is formed on both side edges. A flange is formed by forming a rough-shaped steel piece having a deep slit, and rolling the web part of the rough-shaped steel piece with a horizontal roll in a universal mill, and at the same time gradually pushing open the slit of the rough-shaped steel piece with a vertical roll. A method for manufacturing an H-beam steel, characterized by forming a section.