JPH03268803A - Rolling method of h-shape steel - Google Patents

Abstract

PURPOSE:To prevent the shape of web from deterioration by finely adjusting the inside width of web of roughly rolled billet according to a specified condition with a universal mill with a divided roll of which the roll width is variable for rolling down web thickness before finish universal rolling. CONSTITUTION:The roughly formed billet which is passed through a break down mill 5 is repeatingly rolled until the web thickness Tw, flange thickness Tf and flange width L of the roughly formed billet become the target dimension with a group of roughing universal mills which are constituted of a roughing universal mill 1 and edger mill 2. On the next stage, the billet is reducing adjusted at least once so as to become a prescribed inside width Bw of web (the dimension that the thickness of flange on both sides is subtracted from the web height of the roughly formed billet) and then performed with finish rolling that is combined with raising-up of flange with a universal mill 4. In the fine adjustment of the inside width of web before finish universal rolling, each draft is controlled so as to satisfy the formula.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for rolling H-section steel, which improves dimensional accuracy by avoiding shape defects during the 3g H-section adjustment rolling process, especially changes in the thickness of the web in the width direction. This is an attempt to make further improvements.

(Prior art) In general, H-beam steel is made of
In a rolling line that combines a breakdown rolling mill 6, a roughing universal rolling mill 7, an edger rolling mill 8, and a finishing universal rolling mill 9, FIGS.
and each material as shown in (C), that is, slab 10
．． The rectangular copper piece IL was produced by stepwise hot rolling a mackerel piece 12 for H-section steel.

Here, each material having a cross section as shown in FIGS. 7(a), 7(b), and 7(c) above is roughly shaped in a breakdown rolling mill 6, and such a rolling mill is, for example, Open hole shape 13 as shown in FIGS. 8(a) and (b). Alternatively, a double breakdown rolling mill having upper and lower rolls with closed hole shapes 14 carved therein was used.

As for the specific rolling procedure, the rolled material is first processed into a shape suitable for intermediate rolling in a breakdown rolling mill 6 using a plurality of hole shapes, and then as shown in Fig. 9 (a). ) and at least one edger rolling mill 8 equipped with rolls having the shape as shown in FIGS. - A pass or multiple passes of intermediate rolling are carried out, and the finished universal rolling mill 9, which is equipped with rolls as shown in FIG. Ta. In this way, in the conventional rolling procedure, the product dimensions are determined in advance, and the finishing universal rolling mill 9
The dimensions of the rolls in Figure 8(a) and the dimensions of the rolls in Figure 9(a) were determined in a normal rolling line. (B), the dimension (C) in FIG. 9(B), and the dimension (d) in FIG. 9(C) were designed to be approximately equal.

In rolling H-section steel, as mentioned above, the change in shape of the material after breakdown rolling is limited, and in rolling a specific series (for example, H600X300),
Horizontal rolls were used that had a specific width to match.

By the way, in rolling H-section steel using horizontal rolls of a specific width, although the inner width of the web can be kept constant,
When the flange thickness needs to be changed, the web height may have to be changed accordingly.

That is, even within one series of H-beams, there are several types of products with different flange thicknesses and web thicknesses to suit different applications. This is manufactured by appropriately changing the distance between the horizontal rolls and vertical rolls of a rolling mill, but since the difference between the maximum and minimum flange thickness of the product is usually around 16 mm, there is Therefore, there were cases where the web height changed by about twice that, that is, about 32a+m.

If the web heights of H-section steels in the same series differ greatly, problems may occur when the steels are used, for example, as construction members. In other words, in order to reduce the amount of rope used as much as possible, when manufacturing a beam by joining several sizes of HY3 steel in the same series, if the web heights of the H-beams differ, when the outer surfaces of one flange are matched, the other This causes a large misalignment (twice the difference in flange thickness), which poses a problem during construction. In addition, in the structural design of buildings, dimensions are usually determined sequentially from the outside to the inside, but if the web height of the H-shaped steel used differs, it may be difficult to match with other dimensions at the construction site. This can become a serious problem when strictness is required.

In addition, the following problems were unavoidable when manufacturing H-section steel by rolling.

That is, in the rolling of H-section steel, as shown in FIG. 10, the side surface portion 16 of the horizontal roll 15 of the rough universal rolling mill 7 wears out and the roll width decreases as the number of rolled materials increases. In this case, the vertical roll 17 wears out along with the horizontal roll 15, but this can be dealt with by adjusting the roll opening degree corresponding to the amount of wear for the vertical roll 17, but for the horizontal roll, as shown in FIG. In addition, the web thickness (E) is determined within the range allowed by the product's dimensional tolerance.
The only option is to thicken the roll width to ensure the web height, and if rolling continues with the roll width outside this tolerance, product dimensions will vary.
To avoid this, complicated work such as replacing the rolls is required, and if you want to stably obtain H-shaped steel of good quality over a long period of time, the frequency of replacing the rolling rolls will increase significantly. There was a disadvantage in doing so.

Here, the web height tolerance of H-beam steel products is 400. ±3.0 wll for less than inn, ±4.0 wll for 400 dishes or more and less than 600 dishes, 6
For items over 00, ±5.0III11 standard (JI
(see SG3192). In rolling H-beam steel,
As mentioned above, the web height of the product (to) is horizontal roll 1
The web height is affected by the roll width in step 5.
The effective width of the hole to be used was determined so that the dimensional tolerance of () was within the above range.

Due to the above-mentioned problems in rolling H-section steel, in H-section steel for construction, which requires high dimensional accuracy, the web height is constant even if the flange thickness is different. In this way, plates made by welding together have been used. However, in this case, there is a disadvantage that the manufacturing cost is naturally higher than that of rolled H-beam steel, and therefore there has been a desire to establish a manufacturing method that can be manufactured by rolling with high dimensional accuracy.

In an attempt to solve the above-mentioned problems, for example,
Publication No. 9-133902 discloses a variable width split roll having a structure in which the axial position can be changed, as shown in FIG. 9, this allows partial rolling of the web of the section and rolling of the flange end, making it possible to roll H-beams of different sizes (web heights) using the same roll. A rolling method is disclosed.

In addition, in Japanese Patent Application Laid-open No. 60-82201, Fig. 6 (Work)
As shown in FIG. A rolling method is disclosed in which split rolls whose axial positions can be changed are incorporated into a universal rolling mill 9, and the web height and flange width of an H-section steel are finished to a desired size using the same roll.

(Problems to be Solved by the Invention) In all of the above prior art techniques, the web height can be changed over a large range, and several series of H-beams can be continuously rolled, so compared to conventional rolling, roll exchange is possible. It has the advantage of being able to reduce the frequency. However, when rolling with a constant web height for all sizes in the same series, the amount of adjustment of the roll spacing of the splitting hole/roll is 30
Despite the fact that it is only required to be about III+, it is necessary to use a two-part roll that can move in the axial direction as a horizontal roll in all of the rough universal mill, enjar mill, and finishing universal mill, so the equipment cost is very high. was there.

Furthermore, in JP-A No. 61-262404, there is an attempt to apply a horizontal roll equipped with at least two split rolls whose axial position can be adjusted during finish rolling of a profile, but such a rolling method There was a problem in that when applying local rolling to a thin and cooled profile, the roll surface pressure of the rolling rolls increased and an excessive load was applied to the split rolls.

In addition to the above-mentioned problems that occur when rolling H-section steel, prior to finish universal rolling, universal rolling is equipped with a split call for web thickness reduction that allows the roll width to be changed. A rolling method (see Japanese Patent Application No. 63-233393) has been proposed in which rolling is performed to reduce the inner width of the web of a rough shaped steel piece at least once.

In the case of this rolling method, it is possible to suppress the increase in load on the rolling rolls when adjusting the width of the web, and the advantage is that the width dimension of the web can be adjusted over a wide range. As a result, a thickness deviation occurs in the width direction of the web, and if this deviation becomes excessive, it cannot be corrected even by final finishing universal rolling, resulting in dimensional defects. there were.

This invention suppresses as much as possible the plate thickness deviation in the width direction of the web, which is feared to occur in a rolling method in which the inner width of a rough-shaped steel slab for H-section steel is adjusted to reduce the width at least once. The purpose is to propose a method that can stably manufacture products with high dimensional accuracy.

(Means for Solving the Problems) The present invention provides the above-mentioned finishing method when rolling an H-section steel by performing rough universal rolling and then finishing universal rolling on a rough shaped steel piece having a web and a flange that has been subjected to breakdown rolling. Prior to universal rolling, use a universal rolling mill equipped with split rolls for web thickness reduction that can change the roll width to perform at least one reduction of the web inner width of the rough shaped steel billet in accordance with the following conditions. This is a method for rolling Hi steel characterized by the following.

Note=5≦ (r f r w r bw) ≦
15 Here, r: Reduction rate (%) of flange thickness r,
,: Rolling ratio of web thickness (%) R: Rolling ratio of web inner width (%) (Function) Figure 1 shows a schematic diagram of a rolling mill row suitable for use in rolling H-section steel. In the figure, number 1 is a roughing universal rolling mill, 2 is an edge rolling mill, 3 is a universal rolling mill having a web thickness reduction roll 3a with variable roll width, 4 is a finishing universal rolling mill, and 5 is a breakdown rolling mill. It is a machine. When applying the above rolling mill row to roll H-section steel, the rough-shaped strip that has passed through the breakdown rolling mill 5 is rolled by the rough universal rolling mill 1 and the Edger rolling mill 2.
As shown in FIG. 2(a), the rough-shaped steel piece is repeatedly rolled using a rough universal rolling mill group consisting of the following until the web thickness T, 1, flange thickness Tf, and flange width of the rough-shaped steel piece reach the target dimensions. Then, in the next step, for example, as shown in Figure 2(b)
As shown in FIG. 2, the inner web width B is adjusted at least once by the universal rolling mill 3 (the dimension obtained by subtracting the thickness of the flanges on both sides from the web height of the rough-shaped rope piece), and then the second As shown in Figure (C), finishing rolling which also serves as flange raising is performed by a universal rolling mill 4. In such a rolling method, by appropriately adjusting the roll width of the rolls 3a in the universal rolling mill 3, H-section steel with a constant web height h can be rolled without requiring frequent replacement of the rolling rolls. Moreover, by actively changing the roll width of the rolling roll 3a, there is an advantage that several types of H-section steel having different web heights can be rolled on the same line. However, in such a rolling method that adjusts the inner width of the web to reduce it, if the rolling conditions of the universal rolling mill 3 are not appropriate, the thickness of the web will be stepped in the width direction as shown in Figure 3, and this will be large. In such cases, the problem cannot be solved by the final finish rolling alone, and it is necessary to add an extra rolling process to eliminate it, which may lead to an increase in equipment costs or a decrease in productivity. be.

FIG. 4 shows a schematic diagram of one of the rolls, which is an example of a two-part type that is suitable for use when performing rolling to reduce the inner width of the web. , web thickness reduction ratio,
The flange thickness reduction ratio and web inner width reduction ratio are expressed as follows: -5≦(rrrwrbw)≦15 rf: Flange thickness reduction ratio (%) rw: Web thickness reduction ratio (%) rbw: Web inner width reduction ratio (%), no extreme thickness difference occurs in the width direction of the web, and even if a thickness difference occurs, it can be easily eliminated in the finish rolling stage.

In addition, the roll width of the horizontal roll of the rough universal rolling mill is Bull, the web height of the H-section steel that will become the final product is H8, and the minimum value of the flange thickness of the H-section steel to be manufactured within the same roll chance is T. If f+%, 7, then H--2・T, ,, +B,.

Therefore, the web height is constant and the flange thickness T,
When rolling H-section steel, the flange thickness T
What is necessary is to reduce twice the difference between fmi and . In other words, when adjusting the reduction of the inner web width, among the reduction ratios of the web thickness, flange thickness, and web inner width, the reduction ratio of the web inner width is the one within the same roll chance. It is determined from the manufacturing range of the flange thickness and the number of reduction adjustment passes for the inner web width. Therefore, it is only necessary to adjust the rolling reduction ratio of the remaining web thickness and the rolling reduction ratio of the flange thickness in accordance with the rolling reduction ratio of the web inner width.

FIG. 5 shows the thickness T of the unrolled part of the web of the H-section steel after finish rolling. .

2 is a graph investigating the relationship between the ratio of the web thickness and the value obtained by subtracting the web thickness rolling rate r8 and the web internal width rolling rate rbw from the flange thickness rolling rate rt when adjusting the reduction of the web internal width.

Normally, when manufacturing Him by rolling, dimensional accuracy comparable to that of H-section steel manufactured by welding is required. In particular, for H-shaped steel used for construction, the maximum web thickness is about 14 rm, so if the web thickness variation tolerance is about ±5% (±0.7 on), the web thickness is calculated from the rolling reduction rate r of the flange thickness. The value obtained by subtracting the sum of the rolling reduction ratio r of the thickness and the rolling reduction ratio rbw of the inner web width must be regulated within the range of 5 to 5 obtained from Figure 5 above, and the inner width of the web must be within this range. By adjusting the reduction, even if a step exists in the width direction of the web at this stage, the step will be very small and can be reliably eliminated in the subsequent finish rolling.

(Example) By applying the rolling mill row shown in Fig. 1 above, we tested the web thickness and flange of a typical H-beam steel with a web height of 500 mm and a flange width of 200 mm. The thickness is 9mm, 12nan, 12m, 16mm, respectively.
Rolling was carried out to 12 m+a and 25 mm, and the deformation status of the obtained H-section steel web was investigated. The results are shown in Table 1 along with the rolling conditions. In addition, the reduction adjustment of the web inner width is performed before the finishing universal rolling, and the web thickness is reduced to 9.
Rolling was performed using an H-beam steel with a flange thickness of 12 mm and a standard dimension of 12 mm.

Table 1 From Table 1, it was confirmed that the step ratio of the web thickness was very small when rolling was performed that met the conditions specified in the present invention.

(Effect of the invention) Thus, according to this invention, the web height is constant.
This method is advantageous when rolling a section steel or when rolling several types of H section steel on the same rolling line using the same rolling roll.
It is possible to effectively avoid deterioration in the shape of the web, which is a concern when applying a rolling method that adjusts the reduction of the inner width of the web.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a rolling mill row suitable for carrying out the present invention. FIGS. Figure 4 shows the deformation of the web caused by adjusting the inner width of the web. Figure 4 shows one of the split rolls for reducing the web thickness. Figure 5 shows the deformation of the web caused by adjusting the inner width of the web. Figure 6 (a) (b) is an explanatory diagram of the rolling procedure for H-section steel according to the conventional method. Figure 7 (a) (b) (C) is a cross-section of the material for H-section steel at each rolling stage. Figure 8 (a) (b) is a diagram showing the shape of the caliber of the breakdown rolling mill Figure 9 (a) (b) (C) is an explanatory diagram of the rolling procedure according to the conventional method Figure 1θ FIG. 11 is a diagram showing the main dimensions of H# steel. 1... Roughing universal rolling mill 2... Edger rolling mill 1... Universal rolling mill 3a... Variable width roll 4... Finishing universal rolling mill 5... Breakdown rolling machine Fig. 1 Fig. 2 Figure 5 Figure 6 (Ct> (b) Figure 7 Figure 8 Figure 9 Figure 11

Claims (1)

[Claims] 1. When rolling an H-section steel by subjecting a rough shaped steel piece having a web and a flange that has undergone breakdown rolling to rough universal rolling and then finish universal rolling, prior to the finishing universal rolling, A universal rolling mill equipped with split rolls for web thickness reduction whose roll width can be changed is used to reduce the inner width of the web of the rough shaped steel billet at least once in accordance with the following conditions. Method of rolling section steel. Note-5≦(r_f-r_w-r_b_w)≦15r_f:
Reduction rate of flange thickness (%) r_w: Reduction rate of web thickness (%) r_b_w: Reduction rate of web inner width (%)