JPS589701A - Production of rough shape ingot - Google Patents

Abstract

PURPOSE:To improve the yield, efficiency and quality of rolling in a method of forming triangular hollow slits on both sides edges of flat ingots with plural split calibers provided at the center in the bottom part, by specifying the shape of the split calibers. CONSTITUTION:In order to produce a rough shape ingot for H-steel, a flat ingot obtained by continuous casting or the like is heated, and triangular hollow slits are formed on both side edges thereof. In this formation, the ingot with the width direction thereof held top and bottom is roughly rolled with the split calibersI-III formed to the rolls of duplex type reversible rolling mills. The calibersI-III have crest parts 1 of a prescribe height (h) and a vertical angle theta, which vertical angle theta is made constant and which height (h) is so set as to increase gradually. The ingot having the slits is force expanded in the slit parts with the box calibers IV formed to said rolls and the slit parts are flattened by plural times of passes. The width direction of the ingot is positioned horizontally, and is rolled with the forming calibers V provided to said rolls in order to reduce the thickness in the web part and to trim the entire sectional shape.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a rough-shaped steel piece for H-section steel.

Conventionally, H-beam steel has been heated from a steel ingot into a slab-rolled rough section (beam blank)' and then rolled by 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 are thin, such as steel ingot #1, and it is not possible to form a rough shaped steel slab with a thick flange width using the conventional groove rolling method. Therefore, various new rolling methods have been proposed. Some representative examples will be explained below.

First, the first method is 1. In a rough rolling mill, using a number of box hole shapes whose groove bottom widths gradually increase, width reduction rolling is performed while sequentially changing the hole shapes with the width direction of the slab as the vertical direction. After eating, transform the material into a dog bone shape.
The purpose is to roll the steel piece into a predetermined rough shape using a finishing hole 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.

! Method 2 is to provide a convex protrusion at the center of the bottom of the box hole mold, thereby forming a concave groove in the center of the slab in the thickness direction, and preventing the material from falling over with a similar convex protrusion in the next hole mold. The material is rolled into a dog-horn shape while being held in the same position as shown in FIG. This is a method of forming pieces.

The sixth method is to directly feed the slab into a unimassal mill to form a predetermined rough shaped steel piece. Universal book mills usually have vertical rolls that are not driven, so it is not possible to take a large reduction in the width direction.

The fourth method, as shown in Figure 1, is to provide a bulge in the center of the bottom of the box hole, use multiple holes with different top angles of the bulge, and widen the flange-equivalent portion. It is. In this method, when the material is bitten into the next hole, the apex angle of the material and the apex of the hole are different, so as shown in FIG.
The material 10 gets caught from the tip of the flange-equivalent part and is difficult to push open evenly on the left and right sides, causing twisting of the material 10.

In both of the above-mentioned methods, a slab thinner than a conventional steel ingot is rolled down in the width direction, and the reduction does not penetrate into the center.
It utilizes a dog-bone deformation in which only the ends swell. In particular, in the case of wide H-beam steel, a width reduction of 500 dragons 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 rolling in the width direction requires a considerable number of passes, rolling efficiency is also significantly reduced. When a slab with a large aspect ratio is stood perpendicular to its width and rolled down from above and below, the material tends to shift in the box hole mold during rolling, causing rolling defects on the side walls of the hole. often remains 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 producing rough-shaped steel slabs for H-beam steel according to the present invention involves forming holes in a roll of a double-hole rolling mill such as a breakdown mill, and forming a plurality of split holes with a triangular chevron in the center of the bottom. Triangular concave slits are formed on both sides of the heated flat steel slab using a die, and the apex angle of the chevron portion is the same and the height is increased sequentially. After the slab (Y depth < Shit) is formed, holes are made in the roll using a slotted hole die. The slits are expanded and flattened by rolling a plurality of times using a flat-bottomed box hole die, and then shaped into a predetermined cross-sectional shape using a shaping hole provided in the roll.

Next, the method of the present invention will be specifically explained with reference to the drawings. First, a flat steel billet obtained by continuous casting etc. (hereinafter referred to as a steel billet, see Fig. 6 (A)) is placed in a heating furnace for 12 hours.
Heat to a temperature of 00C or higher. Next, triangular concave slits v are formed on both sides of the steel piece (see Fig. 1 (B) and (
Q).

As shown in Fig. 4, the slits are formed in the width direction of the steel billet using split hole types I, ■, and ■, which are made in the rolls of a double reversible rough rolling mill (hereinafter referred to as BD mill). Rough rolling is performed as upper and lower. Each split hole type I, ■, I has a chevron portion 1 of a predetermined height h and apex angle θ. Each split hole type I
, ■, ■ The apex angle θ of the chevron portion 10 is constant, but the height h is set to gradually increase.

Next, the steel billet having the slit is forced to spread out the slit part by the box hole type (■) provided in the roll.
Figure 1 (D)). Similarly to the above-described slit formation, the slit portion is rolled and rolled several times with the width direction of the steel piece being up and down until the slit portion becomes flat.

Next, in order to reduce the thickness of the web portion of the rolled material having a dog-bone cross section and to shape the overall cross-sectional shape, the rolled material is rolled using a forming hole (3) provided in the roll.

Above, we have described a method for manufacturing a rough steel billet with a dog φ bone cross-sectional shape from a flat steel billet using a BD mill. It is possible to increase the number of It, l, box hole type (2), and forming hole type (2), and it is also possible to vertically install a plurality of roll pairs having each hole type.

<Example> Example vH4oox4oo of the method of the present invention will be described. FIG. 5 shows a mill layout in which the method of the present invention was implemented. In Fig. 5, 2 is a heating furnace, 3 is a BD mill, 4 is a rough universal mill, 5 is an edger mill,
6 indicates a crop saw, and 9 indicates a finishing universal mill.

12. A continuous casting slab with material dimensions of 180w thickness x 1200u width is placed in the heating furnace 2. Heating to '50 c, three types of split hole molds as shown in Figure 4 1. Rough rolling was performed using a BD mill with It, I, box hole type (■), and shaped hole type (■). The bottom width 1 of the split hole type ■, ■, ■ is 220.6, respectively.
00.380 h, the height h of the chevron part is 40,120.20
0 and the apex angle θ was 60°. The bottom width 1' of the box hole type ■ is 500 mm, and the bottom width 11 of the forming hole type ■ is 72 mm.
I set it to 0.

In the rough rolling, first, the heated slab is placed with the width direction as the top and bottom,
By rolling with split hole type I, ■, ■, two passes per each hole type,
After rolling down by a total of 400 mm, the slit part was expanded by rolling 3 ξ holes with a box hole type ■, and the web height was 7.
It was formed into a rolled material with a dog-bone cross section having a 001n111 flange width of 520mm. Next, the rolled material was turned 90 degrees and rolled with a forming hole V of 2·ξ so that the web thickness was 70 mm.
It was formed into a rough shaped steel piece with a flange width of 450 nw and a web height of 720 urn.

This rough shaped steel piece is then finished into a product using a crop saw 6, a rough universal mill 4, an edger mill 5, and a finishing universal mill 9.
111158-9701 (3) According to the method of the present invention, large fish tails do not occur at the front and rear ends of the rough-shaped steel billet, so the yield is improved, and the flange width is more efficient, so the number of rolling passes can be reduced. Rolling efficiency is improved by reducing
Even when manufacturing a large-sized H-beam from a thin flat steel piece, it is possible to manufacture it by heating only once.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the hole shape of a horizontal roll used in the conventional method. 2 is a cross-sectional view showing the state of the material being rolled by the groove shown in FIG. 1; FIG. FIG. 6 is a schematic process diagram showing the method of the present invention, and FIG. 4 is a front view showing the hole shape of the horizontal roll when a BD mill is used in the method of the present invention. FIG. 5 is a plan view showing an example of a mill layout for implementing the method of the present invention. 1: Yamagata part 2: Heating furnace 3: BD mill
4: Coarse universal mill 5; Edger mill 6: Crop saw 9: Finishing universal mill 10: Rolling material hole Figure 1 Figure 4 also 5 times procedure amendment Written by the Patent Office on August 7, 1982 Director Kazuo Wakasugi 1. Indication of the case Patent Application No. 107940 of 1982 2. Name of the invention Method for manufacturing rough-shaped steel slabs 6. Relationship with the person making the amendment Patent applicant address Name (211) Sumitomo Metals Kogyo Co., Ltd. 4, Agent (1) The portion of water in the description is amended as follows. Correction location page Line Before correction After correction 5 9 1st
Figure 6: 5 11 ). ) of (2
) Figures 2, 3 and 4 are corrected as shown in the attached drawings. that's all

Claims (1)

[Claims] A triangular chevron is provided at the center of the bottom of the box hole mold, and slits are made on both sides of the flat steel piece using a plurality of split hole molds in which the apex angle of the chevron is the same and the height t is successively increased.
A method for manufacturing a rough-shaped steel billet, which comprises sequentially deepening the slits and then expanding the slits using a flat-bottomed box hole mold to flatten them.