JPS6250001A - Rough rolling method for thin-walled web wide flange beam - Google Patents

Abstract

PURPOSE:To permit the formation of a thin-walled web wide flange beam with single of heat hot rolling by forming two kinds of calibers having approximately the same caliber width and different web shapes of the calibers to the caliber rolls of a breakdown mill and passing a rolling material alternately plural times through two kinds of the calibers. CONSTITUTION:The rolling material is rolled with the irregularly shaped caliber KI and the ordinary caliber KII and after the rolling material is rotated 90 deg., the rolling material is subjected to edging rolling with the box caliber B. The material is again returned to the molding caliber KI and the same rolling pattern is repeated. The number of passes of the molding rolling and edging rolling as well as the number of 90 deg. rotations of the rolling material are decreased and the molding rolling is executed in the continuous passes of the calibers KI, KII and B. The wide flange beam for SRC, etc. is thus formed by single heat of hot rolling.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for rough rolling a thin web H-section steel having a 7 lange thickness to web thickness ratio of about 3 to 4.

(b) Conventional technology SRC (5teel Re1nforced Conc)
Compared to H-section steel used for steel structures, the H-section steel used for steel structures has a much thinner web thickness, and the flange-to-web thickness ratio is 3 to 4. Compared to the wall thickness ratio of normal rolled H-section steel of 1.0 to 20, it is 5RCJl.
The fiH type has a relatively thin web.

When manufacturing this 5T (C H-beam steel), it is hot rolled in one heat from a slab or plume.

The reduction in the weight of the flange is significantly larger than that of the flange.
Even in the rough rolling process in a breakdown mill, which rolls a rough piece (beam blank) with unbalanced rolling, web waving occurs. For this reason, it is manufactured using the built-up method by welding three steel plates.

If a beam blank is used as a raw material and hot rolled for one time, web waving during rolling can be prevented, but two heat rolling is usually required, which is not cost-effective. The material is a beam blank continuous slab. If you need to hold molds of multiple sizes.

This has not been realized because it takes time to change molds at steel factories.

Conventionally, when H-beam steel is manufactured by hot rolling, the rough rolling method using a breakdown mill is to first roll a web into the forming hole in multiple passes in 1, as shown in Figures 3 and 4. decrease. In the case of an open type hole with vertical symmetry as shown in Figure 1, if the web is continuously rolled down, the roll
Because bulging occurs in a part of the collar, the material is generally turned 90 degrees after one pass of rolling in the shaped hole type KI, as shown in Figure 5.

Flatten the outer surface of the flange with box hole die B, turn the material 90° again, return to the same forming hole die KI, and repeat this pattern. The same applies to the forming hole mold KII.

In this way, the disadvantage of performing multiple passes with the same hole.

■ The thickness of the 7-lunge decreases due to material stretching associated with web reduction (Figure 7).

■ When the web reduction becomes large, the flange part cannot follow the stretching of the web, resulting in web buckling and the web becoming wavy.

■ The web temperature at the end of rolling decreases due to the increased number of material etching passes and material turns.

(c) Problems to be solved by the invention Problems to be solved by the invention are 2. Using an ordinary slab or plume as a raw material, hot rolling in one heat,
The objective is to obtain a rolling method that can produce H-beam steel for SRC.

(b) Means to solve problems The method for rough rolling thin web H-section steel of the present invention is as follows.

In a method in which rolled material is heated to a predetermined temperature in a heating furnace and then roughly rolled in a breakdown mill.

Forming two types of forming holes having substantially the same width and different hole shapes on the groove roll of the breakdown mill, and passing the rolled material alternately through the two types of forming holes. rolling.

The above-mentioned problem is solved by repeating the rolling process a plurality of times to reduce one rolled material to a predetermined web thickness.

(E) Example 9 The rough rolling method of the present invention will be described with reference to FIGS. 1, 2, and 6.

First, as shown in FIG. 1, there are two types of forming holes KI and KII of a breakdown mill having substantially the same hole width but different shapes of hole webs.

The molding hole type KH may be a hole with a normal shape, but the molding hole type K
I is in an unusual form for reasons that will be explained later.

In addition to the shape shown in Fig. 1, the shape of the hole type KI is as shown in Fig. 10 (
The shapes shown in A), CB), and (C) may also be used.

After one pass of rolling is performed in the shaping hole Kn, the material is turned 90 degrees, and edging rolling is performed in the box hole WB, the material is returned to the shaping hole KI again and the same pattern is repeated.

The characteristics of continuous passes of the molding hole types KI and KII are as follows.

Instead of rolling down the entire surface of the web, in the forming hole type KI,
After reducing the area of the web by half, in the forming hole mold KII,
The remaining half is reduced and at the same time flattened. An example of the combination of web shapes at this time is shown in FIG. In the forming hole type KI, the part 11 of the web of the rolled material 10 is strongly rolled down, so the area of the unrolled part 120 is large (7 lung width W
does not decrease; on the contrary, it increases. Rolled material 10 with forming hole type KI
If the entire material is rolled down, the rolled material 10 will be elongated in the longitudinal direction. On the other hand, if a portion is rolled, the flange width increases because it is restrained by the unrolled portion and does not stretch in the longitudinal direction.

Therefore, the inner web dimension d of the hole type KI is set larger than the d of the hole type KTI, and in the hole type KT, the tip of the flange is also rolled down at the same time as the remaining part of the web is rolled down.

In this way, the amount of stretching in one bus is significantly reduced. The decrease in wall thickness of the 7-lunge due to web reduction in hole types KI and KII is significantly improved.

Furthermore, whereas in the conventional method, etching was performed after each printing pass,9 the method of the present invention only requires etching to be performed every two printing passes, making it possible to halve the number of etching passes and the number of material turns. Therefore, the rolling time in the breakdown mill is 50~
It is possible to shorten the time by 60 seconds.

Breakdown mill-exposed beam blanks of I-I section steel for SRC have a web thickness of 3/3 of the flange thickness, similar to the product.
You need to make it three times thinner. In the rough rolling method of the present invention, since the web rolling area in each shaping pass is smaller than the non-rolling area, the elongation in the rolling direction is extremely small, and therefore the occurrence of web buckling is extremely small.

(F) Specific Examples H750X 200 The method of the present invention
The test will be carried out in a section steel factory with the mill layout shown in the figure.

The mill is a double reversible breakdown mill 21. Universal roughing mill 22, double-layer Etsuya mill 23. A Unino finishing mill 24 is installed.

In this case, the beam blank formed by the breakdown mill 21 also needs to have a thickness ratio of 7 lunges/web close to that of the product. In the case of the size of this example, the mil-
From balance, the web thickness of the beam blank is 4ofl
j The average flange thickness was 110mm. Table 1 shows a comparison of pass schedules when this was rolled from a continuous cast slab of 250 m x 1300 m. The breaktown roll hole type and layout N at this time are shown in Figures 1 and 3.
As shown in the figure.

Table 1 A comparison of the degree of pore filling at a web thickness of 50 m is shown in FIGS. 7 and 8. In the conventional method, as shown in Fig. 7, the thickness of the flange is significantly reduced, and the central flange thickness kX
It is 70y+m. In the method of the present invention.

As shown in FIG. 8, the number of pilgrims was 105, which is a significant improvement. The number of turns of the material is also reduced from 14 times in the conventional method to 8 times, which is a decrease of 6 times to 1. Assuming that each turn of the material requires 10 seconds, the rolling time can be reduced by about 1 minute, and the temperature drop of the web can also be improved.

In the conventional method, there was almost no rolling down of the flange portion in the second half pass, so there was only web rolling down, and web waving occurred in the 18th pass. On the other hand, in the method of the present invention,
No web ripples occurred at all until the final 17 passes.

(g) Effects According to the method of the present invention, it is possible to hot roll a thin web H-section steel having a wall thickness ratio of 7 flanges to a web of 3 to 4. In addition, according to the 9-roll rolling method, the decrease in flange width and flange thickness due to web rolling is extremely small.
Even when applied to ordinary rolled H-section steel, rolling efficiency can be improved by reducing the cross-section of the slab used and reducing the number of passes and turns.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing the method of the present invention. Figure 2 is the first
-"f" explanatory diagram showing the forming process of the rolled material related to the figure. Fig. 3 is a schematic explanatory diagram showing the conventional method.
Explanatory diagram showing the forming process of the rolling phase related to the figure. FIG. 5 is a live diagram summarizing the molding process shown in FIG. 4. FIG. 6 is an explanatory diagram summarizing the molding process shown in FIG. 2. Figure 7 is a theory showing the tendency of 7-lunge wall thickness reduction by the conventional method, quadruple. FIG. 8 is a theory #J diagram showing normalization of flange wall thickness by the method of the present invention. FIG. 9 is a diagram showing the layout of a section steel factory to which the method of the present invention is applied. FIG. 10 is an explanatory diagram showing another shape of the billboard mold according to the method of the present invention. 10: Rolled material 11: Strongly rolled lower part 12: Unrolled part 20: Heating furnace 21 Ni-breakdown mill 22: Universal roughing mill 23: Edger mill 24: Universal finishing mill KI, KIT: Forming hole type B: Box hole Type patent dispatcher Sumitomo Metal Industries, Ltd. Figure 2 Figure 5 ■■ ■■ O◎ Figure 6■

Claims (1)

[Claims] In a method in which a rolled material is heated to a predetermined temperature in a heating furnace and then roughly rolled in a breakdown mill, the groove rolls of the breakdown mill have approximately the same groove width and different groove web shapes. Forming two types of forming holes, Rolling by passing the rolled material alternately through the two types of forming holes, Repeating the rolling multiple times to reduce the rolled material to a predetermined web thickness. A method for rough rolling thin web H-beam steel.