JPS6056401A - Manufacture of h-beam of large sheet-thickness ratio and its simulant - Google Patents

Abstract

PURPOSE:To obtain a titled H-beam having the large thickness ratio between flange and web without causing its buckling by forming the web thickness of the shape of a blank material before a universal mill into the larger one, and reducing the temperature difference between those of a flange part and web one. CONSTITUTION:A pass schedule is set so that the ratio TF2/TW2, between the flange thickness TF2 and the web one TW2 of a rough shaped billet before a universal mill, is equal to or lower than the same thickness ratio tF/tW of a product. The product is obtained by spreading heavily the internal dimension of the web of this billet by a skew-roll type sizing mill constituted of skew rolls 12, 12' and 13, 13'.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to rolling of H-section steel having a large flange-to-web thickness ratio, or similar section steel.

(Prior Art) Generally, in H-beam steel manufactured by the universal rolling method, a temperature difference occurs between the flange portion and the web portion due to a difference in cooling rate due to the difference in wall thickness between the flange portion and the web portion. In addition, the web portion where roll cooling water accumulates during rolling tends to have a slower cooling rate than the flange portion, which also causes a temperature difference.

This temperature difference between the flange portion and the web portion results in a difference in the amount of shrinkage during the cooling process, and remains as residual stress.

If this residual stress exceeds the web's buckling limit stress, buckling will occur in the web during the cooling process. This buckling is usually called a web wave. This web wave is
The wall thickness ratio between the flange and the web tends to increase, and in conventional H-section steel, the wall thickness ratio between the flange and the web is
The limit is 1.4 to 1.7. In addition, as the wall thickness ratio between the flange and the web increases, the temperature difference during rolling also increases, and the balance of the rolling reduction ratio between the flange and the web tends to fluctuate (
This results in web waves during rolling.

Therefore, regarding the rolling reduction ratio between the flange and web of H-section steel, the flange rolling reduction ratio is usually 2 to 8
There was a constraint that it had to be rolled while maintaining the relationship of setting.

In this way, in manufacturing H-shaped copper 1 with a high plate thickness ratio, two problems must be solved: web buckling during cooling due to the temperature difference between the flange and the web, and web wave generation during rolling. Must be.

By the way, the cross-sectional performance of the H-beam steel web is 1.
- In recent years, efforts have been made to reduce the weight of section steel by making the web thinner, and the ratio of flange thickness to web thickness, which has more efficient cross-sectional performance, has been reduced to 20 to 30.
In history, the need for H-beam steel with a corner plate thickness ratio higher than that is becoming apparent.

(Object of the Invention) The present invention provides an H-beam steel with a large corner plate thickness ratio between the flange thickness and the web thickness, without the above-mentioned web buckling.

(Structure and operation of the invention) In the present invention, the web thickness of the universal pre-material shape is
By increasing the heat capacity of the web and reducing the temperature difference between the flange and web parts,
The purpose is to select the thickness ratio between the flange and the web of the pre-universal material to a value that provides a finishing temperature condition that will not cause web buckling during cooling.

Therefore, it is possible to manufacture an H-section steel with excellent cross-sectional performance compared to a conventional H-section steel in which the flange-to-web wall thickness ratio is thicker than 2, which was considered difficult in the prior art.

The present invention will be described in detail below with reference to the drawings. In the illustrated embodiment, a case will be described in which an H-beam steel having a high plate thickness ratio is manufactured.

FIG. 1(a) is a schematic process diagram of an H-section steel manufacturing line that implements the method of the present invention. Referring to FIG. 1(a),
Blooms or slabs sent from the steelmaking process undergo a heating process and are rolled into a beam blank 21 having a predetermined size and shape as shown in FIG. The pre-universal rough-shaped steel billet rolled at .3゛・ and made vertically symmetrical is sent to the next process, the universal mill.

Next, the rough universal rolling mill 4(a) in FIG. 1(a)
, 4(b), 4(c) and shaping pressure Hg 5 (a),
One pass rolling is performed in the rough universal rolling mill group 9 including 5(b), followed by the intermediate universal rolling mills 6ta), 6(b), 6(c) and the flat rolling mill in FIG. 1(a). 7
(a), 7(b), then web widening rolling mill 8
After passing the
- Apply pressure from the top, bottom, left and right using the rolling mill 6 (d),
With the flange section almost vertical, shape the desired high plate thickness.
Roll to

As shown in FIG. 1-(b), the rough universal mill 2 and shaping mill 3 following the breakdown mill 1 are used for continuous reciprocating rolling, and the subsequent web widening mill 4 and finishing mill 5 are rolled in one pass. It is also possible to use a tandem-type mill arrangement in which the roughing universal rolling mill and the shaping mill are used for rolling. A combination arrangement may also be used.

FIG. 2 shows an example of the groove diagram of the breakdown rolling mill shown in FIG. The steel piece 21 ejected from the top has a symmetrical shape, and the first
In Fig. 1(a), it is sent to the rough rolling mill 2, and in Fig. 1(b), it is directly sent to the rough universal rolling mill (Table 2.
The steel billet leaving the rough rolling mill 3 in Figure (a) also has a vertically symmetrical shape and is sent to the rough universal rolling mill 4.

The flange and web thicknesses of these pre-universal rough shaped steel billets are determined from the individual rolling reduction rates of each pass of the universal rolling mill and the flange and web thicknesses of the finished product. The flange rolling reduction rate at this time is usually set to be 2 to 8% thicker than the web rolling reduction rate.

Next, the inner dimension of the web of the pre-universal rough-shaped steel piece is made narrower by the narrowing amount ΔS than the inner dimension of the universal horizontal roll, in order to prevent occurrence of slipping, etc. when it is caught in the subsequent universal stand. That is, if n is the number of universal stands, the inner web dimension becomes narrower by n×ΔS. Here, a value of 10 to several mm is generally used for the narrowing amount ΔS.

FIG. 3 shows the relationship between the pre-universal rough-shaped steel piece prepared in this way and the finished product shape. The flange thickness TF of the universal front rectangular steel piece and the web thickness Tw1
The ratio TF+/Tw is the thickness ratio tp/1w of the product.
This is the cause of the increase in the finishing temperature difference between the flange and the web.

FIG. 4 shows the relationship between the universal pre-phase steel piece used to carry out the present invention and the shape of the finished product. The ratio TF2/TW2 of the flange thickness TF2 and web thickness Tw2 of the universal pre-rough shaped steel billet is the thickness tp of the product.
/1w, and the finishing temperature difference between the flange and the web is improved.

Figure 4 shows a pre-universal rough-shaped steel piece used to manufacture H-beams of the same size as Figure 3, but compared to Figure 3, the web thickness is thicker (the inner web dimension is smaller (Wl ＞W
2). That is, the third
Cross-sectional area S+ of the web part in the figure, cross-sectional area S of the web part in Figure 4
2, St = Wj X Tw.

St = wz '
w, , Wl > W2 Donal. The inner web dimension w2 of the universal pre-rough shaped steel piece according to the present invention is as follows:
It is extremely smaller than the internal web dimension U of the product. Therefore, in order to manufacture an H-section steel having the inner web dimension U shown in Fig. 4, a rolling method for widening the web is required. Rolling machine 8
An overview is shown below.

This has the function of a diagonal roll type sizing mill that can significantly expand the internal web dimension, as shown in Figure 5 (a).
As shown in the front view of , and as shown in FIG.
．． It consists of 13'.

As shown in FIG. 5(a), when the diagonal roll contacts and rolls down the web portion of the input side rolled material 14 having an H-shaped cross section and rolls it down, the web is widened due to the diagonal force generated. In addition to this function, the inner surface of the flange of the H-section steel is pushed and expanded by the outer surface of the diagonal roll, thereby providing a web-like widening effect.

These two web widening functions can perform their functions depending on the amount of web widening, either individually or by the synergistic effect of the two functions. In other words, as shown by θH1θV in the figure, the direction of the axis of the roll can be freely changed three-dimensionally, so the material being rolled is not affected by oblique force. Tozu (a rational and efficient widening rolling method that applies widening force.

Since the diagonal roll type sizing mill has the function of increasing the web thickness while keeping the flange thickness unchanged according to the web width expansion, the rolling pass schedule setting sea fence shown in Fig. 6 allows the flange and web thickness to be increased. The rolling schedule can be set so that the temperature difference falls within an appropriate tolerance.

Embodiment Table 1 shows an example of the pass schedule of H-shaped steel with a peak plate thickness ratio calculated by the conventional method and Table 2 shows the rolling pass schedule setting sea fence of the present invention.

Table 1: Material cross section (plume thickness): 300 Product cross section (mu)
Web thickness: 4.5 Bloom width: 500 Flange J:
9.0 Web height: 250 Flange width: 125 Second surface material cross section (-Bloom thickness: 300 Product cross section (mm) Web thickness: 4.5 Bloom width: 500 Flange thickness: 9.
.

Web height = 250 Flange width: 125 The universal rolling pass Pw in Table 2 is web widening rolling using diagonal rolls, and the internal web dimension after 6 passes is approximately 6
The web width has been widened by 0 mm, and the web rolling reduction ratio ηtw
It is possible to make the value much larger than the flange reduction rate ηtf.

Therefore, the flange reduction rate ηtf and the web reduction rate ηtw
With the exception of the last universal rolling mill, it is possible to roll the web in a thicker state than in the conventional rolling method, which maintains a uniform balance over all passes.

In this example, a web widening rolling method is adopted by introducing a diagonal roll type sizing mill, but it is also possible to introduce other methods, such as the web local reduction method shown in Fig. 7, in the finishing row. . In the figure, (a) is the pre-universal rough shaped steel billet, (b) is the rough universal rolling, and (c) is the finished product.
Local pressure reduction P is shown.

In addition, in this example, the valley rolling reduction ratio in the uni-meal rolling section is kept at the conventional level, but in the rough and intermediate universal rolling sections, the web reduction ratio is increased to the fullest extent that web waves during rolling can be tolerated. ηtw is the flange reduction rate ηtF
Making it relatively larger than this makes the method of the present invention even more effective.

As a universal rolling mill, if an eccentric vertical roll mechanism is used in which the vertical roll axis is located closer to the rolling exit side than the horizontal roll axis, web wave generation during rolling can be reduced. Therefore, it is possible to increase the web thickness of the universal pre-rough copper piece.

(Effect of the invention) FIG. 8 shows the rolling pass schedule setting dialog according to the present invention.
The results of temperature calculation based on the fence are compared with the conventional method. The cross section of the finished product h250x125x4.5/9 is shown. In the conventional method, the temperature difference between the flange and the web is 230℃.
On the other hand, in the method of the present invention, the temperature is significantly improved to 72°C.

Figure 9 shows the relationship between the finishing temperature difference and the web cooling wave generation limit (product cross section H250X125X4.5/
9), as shown in the figure, is well within the allowable temperature difference in the present invention.

In the conventional pass schedule setting method, in order to improve this excessive temperature difference, a forced water cooling device for the flange section, a heat insulation device for the web section, and a forced temperature raising device are required, so a high plate thickness ratio is required. The manufacturing of shaped steel requires extra equipment investment and is a manufacturing method with poor thermal efficiency.

As mentioned above, the present invention combines the optimum value of the flange thickness and web thickness ratio of the pre-universal rough-shaped steel billet, and the rolling pass schedule setting'/l:r-7 square 4-work widening rolling method. Accordingly, it is possible to economically and efficiently produce H-shaped steel, channel steel, and other shaped steel having extremely good cross-sectional properties that meet market needs.

[Brief explanation of drawings]

Figures 1 (a) and (b) are explanatory diagrams of the rolling mill arrangement used for rolling H-section steel with a tube-to-thickness ratio, and Figure 2 is an illustration of the roll hole type of the breakdown mill used in the present invention. Outline - 1 side view, Figure 3 is a schematic diagram of the relationship between the conventional universal pre-rough shaped steel billet and the product, Figure 4 is a schematic diagram of the relationship between the universal pre-rough shaped steel billet used in the present invention and the product, FIG. 5(a) is a front view of a diagonal roll type sizing mill, FIG. 5(b) is a side view thereof, FIG. 6 is a bus schedule setting seekex chart used in the present invention, and FIG. 7 is a web A process diagram of the local reduction method used in widening rolling. Figure 8 is a diagram of the valley-nos rolling temperature and rolling time. Figure 9 is a diagram of the relationship between the finishing temperature difference between the flange and the web and the increase in web cooling wave generation limit. It is. 12.13: Oblique roll 14 Two-man side rolling material 21: Beam blank 22.23: Upper and lower rolls Figure 1 (a) Figure 1 (b) Figure 3 Figure 4 Figure 5 (α) (b) Figure 7 Figure 9

Claims (1)

[Claims] 1. The ratio 'f'r/Tw of the flange thickness TF of the pre-universal rough shaped steel billet to the web thickness Tw so that the finish rolling temperature difference between the flange and the web is within a predetermined tolerance.
A method for manufacturing commercially available thickness ratio fI section steel and similar section steel, characterized in that a pass schedule is set such that the same thickness ratio tp/1w of the product is equal to or less than. 2. Manufacture of heavy plate thickness ratio H-shaped steel and ZoA similar shaped steel according to claim 1, wherein the web circular dimension of the universal pre-rough shaped steel is shorter than the internal dimension of the product by at least 5 degrees. Method.