JPS61135404A - Hot rolling method of h-beam - Google Patents

Abstract

PURPOSE:To reduce roll changing frequencies and to improve the rolling efficiency by adjusting the distance between sectional rolls so that the contracting and expanding amounts of the inside width of a web are equal to the prescribed amount corresponding to the thickness of web. CONSTITUTION:The distance B between the sectional rolls 26 of an universal mill is contracted within a range of 80% web thickness. Further, in case of expanding the distance C of the sectional rolls of a secondary roughing universal-mill or an edging mill larger than the inside width-dimension of the web of stock, the ratio of the reduction amount of area of web and the thickness of web is regulated within 90%. In this way, H-beams of different sizes can be obtained by rolling a stock having the same cross section without changing rolls till the finishing universal mill subsequent to a break down mill, Accordingly, the roll changing frequency is reduced, and the rolling efficiency is improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for hot rolling H-section steel, and particularly to a method for hot rolling H-section steel that has excellent dimensional accuracy and can reduce the number of roll changes. Used in the field of manufacturing H-beam steel.

[Conventional technology]

Hot rolling of general ICH section steel is carried out in the first stage, as shown in (2), using a combination of a breakdown rolling mill 12, a roughing mill 22 pernal rolling mill 14, an edge rolling mill 16, and a finishing everlasting rolling mill 18. Therefore, it is done. That is,
2nd placement, (2) (The materials such as the slab 2 shown in Q, the rectangular steel piece 4, the steel piece 6 for H-section steel, etc. are transferred to the third device, and the open hole type 8 or closed hole type 10 shown in @ is The material is roughly formed into a predetermined shape using a double-type breakdown rolling mill 12 having upper and lower rolls with carved holes.The breakdown mill 12 uses a plurality of hole shapes and sequentially rolls the material through several machine passes. Processed into a shape suitable for intermediate rolling.

The rough shaped material is passed through one or more rough machine presses 14 in the roll shape as shown in FIG. 4(A)tc and
3) One or more edgers in the form of a roll as shown in K.
After one pass or a plurality of intermediate rolling passes by the rolling mill 16, the product is rolled into an H-shaped steel product in one pass in a final rolling mill 18 having a roll shape as shown in FIG. 4 (Q).

Once the product dimensions are determined, the roll dimensions of the finishing universal rolling mill 18 and the roll dimensions of the previous rolling mills are determined. That is, the dimensions of the third device (a), (b) of FIG. 4(5), and (b) of FIG. 4(00) are designed to be approximately equal. Since the shape change after 5&C breakdown rolling is limited, horizontal rolls of a specific width are used, so conventionally it was necessary to replace the horizontal rolls every time the product dimensions changed. Ta.

Normally, H-beam steel is rolled in small quantities with multiple sizes.For example, the product size of H-beam steel is JIS standard 33 series, A8
There are 44 series according to the TM standard, and a total of 77 series.

Conventionally, it usually takes 25 to 30 minutes to change a roll from one size to another, so when rolling multiple sizes of H-beams, the time required to change rolls is proportional to the number of sizes. It is reducing the operating rate. Naturally, when the rolls are replaced, the material is heated and retained in the furnace, resulting in a large amount of energy loss.

Conventionally, in H-shaped steel rolling, as shown in FIG.
There is a tendency for the inner width dimension of 0 to decrease. The vertical rolls 24 also wear out, but in this case, the opening degree of the vertical rolls 24 can be adjusted by the amount of wear, and there is no problem. For this reason, as shown in FIG. 6, if the flange thickness (e) is kept constant, the web height will be reduced by the amount of wear on the side surface 22 of the horizontal roll 20. (e) is made thicker to ensure a higher web height.

i.e. the height of the web of material) is increased by horizontal rolls 200
It is affected by the size of the width, so usually increase the web height)
The effective roll width to be used is determined within the range of dimensional tolerance. For example, if the web height is less than 400 m,
, 400 m or more and less than 600 m, ±4.0 m, 6
000 or more, the tolerance of ±5.0■ is JI8G3192
stipulated in

Therefore, the seven flange thickness varies depending on the width of the horizontal roll 200 used, and especially when rolling is performed using a horizontal roll 20 whose width has been reduced due to wear, the flange thickness of the product increases and the yield decreases. Naturally, the width of the rolls used will change for each rolling chance, resulting in variations in product dimensions for each rolling chance, or even within the same rolling chance, changes in the thickness of the 7 langes due to wear on the horizontal roll side surface 22. Unfavorable in terms of accuracy.

In addition, since it is necessary to have size canning breakdown rolls, rough universal rolls, edger rolls, and finishing universal rolls, there is the problem that the number of rolls in stock will inevitably increase, and usually there are spare rolls for each size. 2
I own ~3 sets. For example, even if a product with a web height of between 700n and 800m is required, it is impossible to manufacture it because it is outside the range of the existing roll width.

If production is inevitable, it will be necessary to acquire new products ranging from breakdown rolls to universal rolls and edger rolls, and it is inevitable that the number of rolls in stock will further increase.

In response to this problem, conventionally,
As disclosed, there is a method in which a horizontal roll of a universal roll is divided into two parts in a direction perpendicular to the roll axis, and a spacer is inserted between them for rolling. However, although this method can be used for a certain range of web height sizes, a dedicated spacer is required for each rolling size, and the roll width cannot be adjusted according to the amount of wear on the horizontal roll side wall 22 at the start of rolling. , the variation in 7-range thickness of products within the same chance remains an unresolved problem.

Furthermore, since the roll width is set not within the rolling line but at a dedicated roll exchange location away from the line, there are numerous drawbacks such as the unavoidable loss of roll exchange time required for each size change. The problem with the conventional method is the reliability of the third device)
, Figure 4 (4) (b), Figure 4 (5) (c), 4th
This occurs because the dimensions (in FIG. 00) are fixed at least within the rolling line.

The present inventors therefore found the above 9) in rolling line whitening.
If it is possible to change the dimensions of , (B), e→, ni), change the dimensions of (a), (b), (c), ni) according to the product dimensions and roll. He discovered that the above problem could be solved, and based on this knowledge,
-7542 and Japanese Patent Application No. 58-189691. In other words, the former patent application No. 58-7542 was filed 7th, (
g), (as shown in QIC), split rolls 26, 32, and 34 whose axial positions can be changed are used in the rough universal rolling mill 14,
This is a rolling method that enables rolling of different web height sizes with the same roll by placing the web in an edger rolling mill 16 and a finishing universal rolling mill 18 to perform partial rolling of the web and rolling of the flange end. In this method, the web can be rolled to a target height while increasing the distance between rolls in accordance with the widening of the web that occurs during edger rolling. The latter patent application No. 189691/1989 was filed in the 8th session, (to), (
Q, As shown in
4A, Edger rolling mill 16, secondary roughing universal rolling mill 14B, finishing universal rolling mill 0 to roll different web height sizes and flange width sizes with the same roll (or Figure 9 section), (As shown in OK, the divided rolls 26, 32 and 34 whose axial positions can be changed are
The present invention relates to a rolling method in which the following universal rolling mill 14A, the secondary roughing universal rolling mill 14B, and the finishing universal rolling mill 18 are arranged to enable rolling of different web height sizes with the same roll.

However, although these prior art technologies have many effects such as a reduction in the frequency of roll replacement compared to the conventional rolling method, they are not suitable for rolling H-beams with different web heights using the universal rolling mill mentioned above. The material, ie, the cross section of the rough shaped steel slab after breakdown rolling, is different, and if the universal rolling mill or later cannot be rolled with the same roll, and the rolling size is changed using the same roll, it is necessary to replace the breakdown roll.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide a hot rolling method that allows rolling of various H-section steel products having different web heights using a material having the same cross section after breakdown rolling.

[Means and operations for solving the problems] The gist of the present invention is as follows.

That is, hot rolling of H-beam steel is made of slabs, rectangular steel slabs, steel slabs for H-beam steel, etc., and includes rolling steps using split rolls whose axial positions are variable for each pass. In this method, the reduction amount of the web inner width is 80% of the web thickness.
or the amount of increase in the inner width of the web is within 90% of (web area reduction/web thickness). This is a hot rolling method.

As a result of various studies on partial rolling of H-beam steel, the inventors of the present invention found that under certain conditions, it is possible to reduce the inner width of the material web using the vertical rolls of a universal rolling mill and to increase the inner width of the web using the split rolls. I found out. If the distance between the split rolls 26 of the universal rolling mill in the 9th rotation is made narrower than the inner web width of the material shown in Figure 6 (Y), and the inner web width of the material is reduced using the vertical rolls, the reduction will occur. If the amount is large, Figure 10 (A) 1. The overall shape is unsuitable for commercialization as shown in CB). In the 10th turn, when the inner width of the web was reduced, the area near the 8th part at the boundary between the web and the 7th lunge buckled in the width direction, and was then pressed down by the split rolls, resulting in a flaw. Fig. 53) shows a small degree of f810 image distortion, in which the 8 parts on the upper surface side of the web are deformed at an acute angle, and the lengths of the upper and lower 7 lunge legs (e) are uneven.

Next, the experiments that formed the basis of the present invention will be explained. In universal rolling, the web inner width was reduced under various conditions, and the web inner width reduction amount (ΔS) and the web thickness at that time (H6
) and the occurrence situation of the overall shape of the defect is shown in FIG. In FIG. 11, the X marks indicate cases in which an inconvenient phenomenon occurred, and the O marks indicate cases in which no problems occurred. Thus, it has been found that the inner side of the web can be reduced without any problem if the amount is within 80 inches of the web thickness. Therefore, in the present invention, the amount of reduction in the inner width of the web is limited to within 80 inches of the web thickness.

In addition, when expanding the inner width of the web by making the interval υ) between the split rolls of the secondary rough universal rolling mill or edger rolling mill shown in Figure 9 03) larger than the inner web width of the material, the split roll If the distance is too large, the inside of the 7-lunge of the material will be scraped by the roll, causing scratches and making it impossible to manufacture the product. FIG. 12 shows the relationship between the amount of increase in web inner width (ΔL) and the amount of web area reduction/web thickness Q with respect to the presence or absence of flaws, which was obtained through various experiments.

Here, the web area reduction is the area reduction of the web when the central part of the web, which was not rolled in the primary 22 parsal rolling, is rolled down in the secondary 22 parsal rolling or edger rolling, as shown in Figure 13. The amount corresponds to the shaded area in the figure. Web thickness is the web thickness after rolling.

In FIG. 12, marks x indicate those in which flaws occurred, and marks Q indicate those in which the inner width of the web could be expanded without any problems.

From this, it has been found that the inner width of the web can be expanded without any problem if the amount is within 901i of (web area reduction/web thickness), and in the present invention, (web area reduction/web thickness) is within 90 inches. limited to.

This will be explained in more detail next. FIG. 14 shows changes in the inner web width of the material when the material after breakdown rolling is partially rolled by universal rolling. The vertical axis on the left is the inner web width of the material after breakdown rolling, the vertical axis on the right is the inner web width of the product after universal rolling, and the horizontal axis is the universal rolling pass number. .

In the case of Japanese Patent Application No. 58-7542, which is the prior art, this corresponds to the straight line (a), and when the central part of the web of material is rolled down in the edger rolling shown in Fig. 7 β), the width of the web is widened. Rolling is performed while widening the interval between the divided rolls according to the spread, and the target inner web width dimension of 8 is obtained.

In the case of patent application 189691/1989, which is the prior art, a straight line (b
) K, and the web inner width dimensions of the material and product after breakdown rolling are rolled in a state where they are equal, and the target inner web width dimension of 8 is obtained.

On the other hand, the one according to the present invention has a straight line (c) and a curved line (d).
It is indicated by. Straight line (C) is a case where the inner web width is actively expanded by the split rolls, and the inner web width dimension of t is obtained. Curve (d) is the case where the web inner width is reduced by vertical rolls, and a web inner width dimension of U is obtained.

Therefore, according to the present invention, the inner width of the web is t from the same material.
It becomes possible to separately manufacture H-beam steel in the range from .

Conventionally, there were breakdown rolls for each size, and the rolls had to be replaced each time rolling, but with the present invention, it is now possible to use the same roll not only for universal rolling rolls but also for breakdown rolls of different sizes. It is possible to continuously roll different sizes without changing the entire line rolls.

〔Example〕

The present invention was carried out with the arrangement of the rolling mill shown in FIG. 15 using the ninth apparatus, and the split rolls shown in (1) and (Q).

First, in the primary rough universal rolling mill 14-1, the web and flange are rolled using horizontally divided rolls 26 and vertical rolls in which the flange surface of the material has a taper of about 5 degrees. In the rough universal rolling mill 14-21C, the flange end is rolled by a horizontally divided roll 32 having a taper of about 5 degrees at the flange end, and at the same time, the same horizontally divided roll 32 and a vertical roll are used to roll down the flange by 7 lunges, and the fixed roll 30 is used to roll the flange into a web. The lower part of the central part was rolled, and both were rolled repeatedly. After completing the intermediate rolling in the primary and secondary rough universal rolling mills 14-1 and 14-2, the finishing universal rolling mill 18, which is equipped with a split roll 34 without a taper and a vertical roll, is rolled 5 times as shown in FIG. A flange with a taper was raised and finished rolled into a product.

(using a roll with the dimensions shown in Table 1) lsoox300
Web thickness of 90mk with breakdown roll for EE
Nominal dimensions 700X300 and 9 from rolled steel slabs
A 00X300 H section steel was manufactured. The inner web width of each product is 656 ws (700 x 300
), 752 wx (800X300) and 850 soa (900X30G).

In the case of Table 1, that is, 700 x 300, as shown in Figure 14(d), if the dividing roll width of the primary universal rolling mill is made narrower than the inner web width of the material, and at the same time the vertical roll interval is also narrowed by the same amount, the web Rolling was performed to reduce the inner width. Naturally, in this case, the roll width was narrowed within 80% of the web thickness to avoid any problems. However, the width of the divided rolls of the secondary universal rolling mill 14-2 was made to be the same as the inner width of the web of the material after the primary universal rolling, and no forcible web height reduction was performed in the secondary universal rolling.

That is, the web inner width 7521 after breakdown rolling
111. Using an 800 x 300 rolling stock with a web thickness of 905 m, set the split rolls of the primary rough universal rolling mill so that the inner web width is 752 fi, start rolling, and create the pass schedule shown in Table 2. The inner width of the material is 700 x 300.
Rolling is performed using a secondary rough universal rolling mill, and the above-mentioned split roll interval is reduced for each pass, so that the total reduction amount for each pass is 96 rolls,
In other words, the distance was reduced by 96m from 752m to 656m. After that, 7 lunges were raised on a finishing universal rolling mill with the split roll width set to the inner web width of 700 x 300.
Finished the X30GI/c.

In the case of 900 x 300, the width of the divided rolls of the secondary universal rolling mill should be made wider than the inner width of the web of the material, and at the same time the vertical roll interval should be made wider by the same amount. Rolling was carried out to enlarge the roll width.Of course, in this case, problems occur.2 As I would like to express, the amount by which the roll width is widened is the amount of web area reduction/
The amount was within 90% of the web thickness. However, the divided roll width of the primary universal rolling mill was set to be the same as the web inner width of the material after secondary universal rolling, and the web internal width was not forcibly expanded during primary universal rolling.

That is, the inner width of the web is 752 cm, and the web thickness is 80 cm.
Using a 0x300 rolling material, set the split roll interval of the primary rough universal rolling mill so that the inner web width is 752mm, start rolling, and then roll the secondary rough universal rolling mill according to the pass schedule shown in Table 3. While increasing the split roll spacing of the rolling mill for each pass, the split roll spacing of the primary rough universal rolling mill after the secondary rough universal rolling mill is made to match the spacing of the secondary rough universal rolling mill that has already been rolled. ) The total amount of expansion for each path is 98 dragons, or 752
A total of 98 baskets were rolled to 850n. That is, the total amount of increase in the inner web width of the secondary unit Uniparser/L' rolling mill is 98. It is.

The inner width of the material is 900x300.
3 After rolling with the primary and secondary universal rolling mills until the width dimensions in the table are reached, the expansion of the split roll widths of the primary and secondary universal rolling machines is stopped, and the rolling is continued with the split roll width kept constant. The web was finished with 7 lunges using a finishing universal rolling mill with the split roll width set to an inner web width of 900 x 300.

As mentioned above, the 700X300 and 9QQX300 H-section steels rolled by the method of the present invention do not have any flaws on the inner surface of the 7 flange due to the expansion or contraction of the inner width of the web, or root flaws in the attachment of the flange to the web, and the surface condition is The dimensional accuracy was good and the yield was excellent due to fine adjustment of the position of the variable position split roll against wear. Naturally, by applying the present invention, 700X
800X300 between 300 and 900X300 can be easily manufactured, and H-beams with any web height dimension between 700 and 900 can also be easily manufactured.

In particular, it has become possible to manufacture H-beam steel in multiple sizes with different web heights from a single cross-section material after breakdown rolling, making it possible to roll the entire line from the breakdown rolling mill to the finishing universal rolling mill without changing rolls. This made it possible to continuously roll H-section steel of different sizes on the entire line.

〔Effect of the invention〕

As is clear from the above examples, when hot rolling an H-section steel using split rolls whose axial positions are variable, the present invention provides a method in which the reduction amount of the inner width of the web is within 80 rounds of the web thickness. Or, if the amount of increase in the inner width of the web is within 901 of (web area reduction amount / web -), -
From the cross-sectional material to the finishing universal rolling mill after the breakdown rolling mill, it is possible to roll different sizes of H shapes without changing the rolls, and the number of four-roll exchanges in the breakdown rolling mill is reduced to about 1/2 of the conventional number. 3, the number of Punta down rolls in stock was reduced, material heating time was shortened, rolling efficiency was improved, and many other effects were achieved.

[Brief explanation of drawings]

The first device, (Bl is a process diagram of H-shaped steel hot rolling,
2nd position, (to), (Q is a cross-sectional view showing the shape of H-beam hot-rolled material, WIJ3 figure, equipment) is a cross-sectional view of the roll showing the roll hole shape, 4th position, CB), (Q is a cross-sectional view showing the hot rolling process of H-shaped steel, Figure 5 is a cross-sectional view showing wear on the side surface of the horizontal roll of a conventional universal rolling mill, and Figure 6 is H-shaped steel. A cross-sectional view showing the dimensions of the steel, Figures 7 (8), (5), and (q are all cross-sectional views showing the roll shape of the prior art (Japanese Patent Application No. 58-7542), and each figure is a rough universal rolling. machine, CB) is an Edger rolling mill, (Q is a finishing universal rolling mill, Fig. 8 (5), (
g), (Q, and (g)) are all based on the prior art (patent application 1982-
189691) is a cross-sectional view showing the shape of the roll and material.
(B) and (Q are both prior art) (Japanese Patent Application No. 58-189691) is a tF1 diagram showing the shape of the roll material. In each figure, the column is the primary universal rolling mill, () is the secondary universal rolling mill, (Q is the finishing universal rolling mill, and the 10th device is ) are cross-sectional views of the material in which abnormal deformation occurred in the KR section when the web height was reduced, and Figure 11 shows the amount of web inner width reduction and whether or not a defective phenomenon occurred when the web inner width was reduced, and at that time. Figure 12 is a diagram showing the relationship between web thickness and the presence or absence of flaws during web height expansion, and the relationship between the amount of increase in web inner width and (web area reduction/web thickness). Fig. 13 is a cross-sectional view explaining the amount of web area reduction and web thickness, Fig. 14 is a line diagram showing changes in web inner width dimension in universal partial rolling according to the prior art and the present invention, and Fig. 15 is a cross-sectional view illustrating the web area reduction amount and web thickness. It is a process diagram showing the hot rolling of an H-beam steel in an example. 2...Slab, 4...Rectangular steel piece 6...H
Steel material for shaped steel, 12...Breakdown rolling machine, 14.
・・Rough universal rolling mill, 14-1 ・・1st set universal rolling mill, 14-2・
・Second-stage set of any rolling mill, 16...Edgeer
Rolling mill, 18... Finishing any rolling mill, 26. 28, 32, 34... Divided pool. Agent Patent Attorney Takeo Nakaji Figure 1 II 2 Figure 3 Kyou 4th Ward Figure 5 9M7 Figure 9 * to m (A) (B) No. 111! Nitsux7L Ho (mm) j112mm Fig. 13

Claims (1)

[Claims] (1) Hot rolling of H-beams made of slabs, rectangular billets, steel billets for H-beams, etc., which is rolled using split rolls whose axial positions are variable for each pass. In the rolling method, the reduction amount of the web inner width is within 80% of the web thickness, or the increase amount of the web inner width is (web area reduction amount/
A method for hot rolling H-beam steel, characterized in that rolling is performed by adjusting the interval between the split rolls so that the distance between the split rolls is within 90% of the web thickness.