JPS61123401A - Hot rolling method of h-beam - Google Patents

Abstract

PURPOSE:To prevent the buckling of a web and the idle passing of the web end and to improve rolling efficiency in the stage of hot rolling an H-beam at the specific width ratio of the web by specifying the respective metal flow rates of primary and secondary rough univeral rolling. CONSTITUTION:The primary rough universal rolling to roll down the end 42 of the web is executed in a -1-7% range of the metal flow rate expressed by the equation in the stage of assembling position-variable horizontal split rolls to a rolling mill and executing partial hot rolling of the H-beam with the inside width of the web ranging >=20 times the thickness of the web. The secondary rough universal rolling to roll down the central part 40 of the web is executed in a 1-4% range of the metal flow rate expressed by the equation. In the equation, DELTAM is the metal quantity moving from the flange to the web in the stage of rolling, DELTAS is the total reduction of area of the flange and web in the stage of rolling. The number of roll exchange is thus decreased and the dimensional accuracy 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 in particular to a method for hot rolling H-section steel that can reduce the number of roll changes. Used in the field of hot rolling.

[Conventional technology]

In general, hot rolling of H-section steel is performed by a combination of a breakdown rolling mill 12, a roughing universal rolling mill 14, an edge rolling mill 16, and a finishing universal rolling mill 18, as shown in FIG. 1 (2), [F]). Manufactured by. That is, a slab 2 and a rectangular steel piece 4 as shown in Fig. 2
, a material such as a steel billet 6 for H-beam steel is cut into upper and lower rolls ti with an open hole shape 8 or a closed hole shape 10 shown in FIG.
After rough shaping into a predetermined shape using a double type breakdown rolling mill 12, one or more rough universal rolling mills 14 having roll shapes as shown in FIG. 1 by one or more edger rolling mills 16 in the shape
After intermediate rolling in a bus or multiple buses, the product is rolled into an H-shaped steel product in one bus in a finishing universal rolling mill 18 in the form of a roll as shown in FIG. 4 (0).

The roll dimensions of the finishing universal rolling mill 18 and the roll dimensions before it are determined by the product dimensions, and the dimensions shown in Figure 3 (A), Figure 4 (B), Figure 4 (0), etc. are designed to be approximately equal.

Therefore, in the past, breakdown rolls were used for each product size.
We had a rough uniform roll, an edger roll, and a finishing universal roll, and it was necessary to replace the horizontal rolls every time the product dimensions changed.

Furthermore, since H-section steel is usually rolled in small quantities in multiple sizes, the number of rolls inevitably increases, and the number of roll replacements increases, resulting in a reduction in the operating rate of the rolling mill. Furthermore, when a request is made to roll an H-shaped steel product with non-standard dimensions, the existing rolls are no longer applicable, and various difficulties arise in manufacturing.

The problem with the conventional method is that the dimensions of (A) in Figure 3 (2), (B) in Figure 4 ■, G/'1 in Figure 4 G, and (B) in Figure 4 0 are This happens because it is fixed. Therefore, the present inventors made the above dimensions (a), (b), (c), and (c) variable within the rolling line, and varied the dimensions (a), (b), (c), and (c) according to the product dimensions. It was discovered that all of the above problems could be solved by changing the dimensions of (2) and rolling, and based on this knowledge, the entire technique was developed in Japanese Patent Application No. 58-2426. That is, Figure 5 Prisoner, 03. (0,
As shown in FIG.
The first coarse universal rolling mill, the second rolling mill,
A secondary roughing universal rolling mill (0) and a finishing universal rolling mill (2) were used for rolling, thereby making it possible to roll H-section steel having different web heights and 7 lange widths with the same roll.

In addition, Fig. 6 (2), CBI, (as shown in Q, divided rolls 26, 32.34'i primary rough universal rolling mill, secondary rough universal rolling mill) whose axial position can be completely changed, and finishing universal It also includes a rolling method that is arranged in the rolling mill 0 and allows rolling of different t-web height sizes with the same roll.

Furthermore, the present inventors have discovered that H
In partial rolling of section steel, the universal rolling mill's hard rolls reduce the web inner width and the split rolls widen the web inner width, resulting in an H-shaped cross section of the same material with a different narrow web height after breakdown. Considering rolling the entire steel product, if the amount of reduction in the inner width of the web is within 70% of the web thickness, the division of the primary roughing universal rolling mill shown in Figures 5 (2) and 6 (2) will be applied. It is possible to roll even if the width of the roll (e) is narrower than the inner width of the material and the inner width of the material web is reduced with a hard roll, and the amount of increase in the inner width of the web is equal to the amount of web area reduction/web thickness. If the amount is within 90% of
It has been confirmed that it is possible to expand the width of the web by making the width of the split rolls of the secondary rough universal rolling mill shown in FIG. We have also discovered that by reducing and expanding the inner width of the web, it is possible to roll H-beam steels with different web height sizes from the same cross-sectional material after breakdown rolling using the same rolls after universal rolling.

These prior art technologies had many effects compared to conventional rolling methods, such as reducing the frequency of roll replacement, but in these rolling methods, the secondary coarse universal When the rolling mill partially rolls the central part of the web, buckling of the web occurs, and in order to prevent this web buckling, increasing the reduction amount of the 7-lunge in the rolling mill causes the web to buckle locally. Alternatively, there is a problem that the product does not come into contact with the entire roll, that is, so-called "through-through" occurs, and the product tends to lack the width of the 7 lunges.

[Problems to be Solved by the Invention] The purpose of the present invention is to eliminate the drawbacks of the above-mentioned conventional techniques in hot rolling of H-section steel, and to provide a stable method that can reduce the frequency of roll replacement and reduce the number of rolls owned. A complete method for hot rolling H-section steel is provided.

[Means and effects for solving the problem] As a result of extensive studies on partial rolling of H-beam steel, the present inventors have found that the area reduction from the flange to the web is carried out at a certain range of area reduction per bath. A friend of mine discovered that all of the above problems could be solved by rolling such that a metal film o -f was formed.

The gist of the present invention is as follows.

In other words, there is a primary roughing universal rolling mill that uses slabs, rectangular billets, steel billets for H-section steel, etc. as raw materials and incorporates horizontally split rolls whose axial positions are variable for each bus;
Next, in a hot rolling method for H-section steel in which partial rolling is carried out using an entire row of rolling mills consisting of a rough universal rolling mill, the inner width of the web is within a range of 20 times or more the web thickness, and the rolling mill of each bus is In the primary rough universal rolling where the edges are rolled down, the metal flow rate is expressed by the following equation (1)! --Thermal heating of H-beam steel characterized by rolling in the range of 1 to 7 inches, and in the secondary rough universal rolling in which the center part of the web is completely rolled down, the metal is rolled in the range of 7O-IK'tl to 4%. This is an intermediate rolling method.

Metal flow i = △M / △s i%) −・
-(1) However, △M: Amount of metal transferred from the flange to the web during the rolling process △S: Total area reduction of the flange and web during the rolling process In rolling an H-section steel using horizontally split rolls, the amount of metal transferred from the flange to the web during the rolling process is as follows: It is characterized by repeated partial reductions. That is, as shown in FIG. 7(2), the flat material of the web is first rolled down at the end portion 42 of the web using a primary rough universal rolling mill. At this time, the center portion 40 of the web is in an unrolled state, and as a result, the rolled material has a swollen shape at the center portion 40A as shown in FIG. Next, the central part of the web was rolled down by 40Ai using a secondary rough universal rolling mill, and the center part of the web was rolled down by 40Ai as shown in Fig. 7 (0
The web is rolled into a flat shape as shown in FIG. By repeating this process, the product is rolled. Focusing here on the deformation behavior of the web in the secondary rough universal rolling, in this rolling the end 42A of the web is in an unrolled state, and the 40 people in the center of the web are restrained from elongating in the rolling direction.
The area-reduced metal in the central portion 42A flows not only in the rolling direction but also in the width direction. The thickness of the end portion 42A of the web is reduced due to the elongation of the entire material, while the thickness is increased due to the metal flowing in the width direction, and these two factors cancel each other out, resulting in no flattening of the web. However, the metal flow in the width direction is limited by contact with the rolls, and if the reduction rate in the center of the web is large, the reduced area metal is forcibly pushed out in the rolling direction, so there is a critical seat in the rolling direction. Web buckling occurs when the bending stress is exceeded. In order to prevent web buckling, it is effective to reduce the compressive stress in the rolling direction of the web by applying 7-lunge rolling in the secondary rough universal rolling mill.

Further, when the area reduction rate of the flange is larger than the area reduction rate of the entire web, metal flow from the flange to the web occurs, which also contributes to preventing thickness reduction at the web end. However, in the case of flange rolling, if the rolling is excessive, the area-reduced metal at the center of the web will mostly flow in the rolling direction, so no flow in the width direction will occur, and the thickness of the web end 42A after rolling will be the same as that of the web center 40A. The web becomes thinner than the thickness after rolling, a so-called web passing phenomenon occurs, and the web cannot be flattened.

Therefore, in order to completely prevent web buckling and through-through of the web end, the difference in thickness between the web center 4OA and the web end 42A after the first rough universal rolling is reduced, and the web center at the second rough universal is rolled. While reducing the amount of reduction in the part 4OA, buckling of the web center part is prevented to the extent that the flow of the metal in the width direction of the web center part and the metal flow from the 7 lunges to the web can compensate for the area reduction due to the stretching of the web end part 42A. It is necessary to reduce the flange as much as possible.

As a result of various studies on rolling methods that can satisfy the above requirements, the inventors of the present invention determined that the amount of metal transferred from the flange to the web should be kept within certain conditions with respect to the total area reduction in primary and secondary rough universal rolling. This can be achieved by finding scales and friends.

In other words, the amount of metal transferred from the flange to the web △M
is expressed by the following formula.

However, So and Sl are the cross-sectional areas of the rolled material before and after rolling, S, 0. S, , are the lunge cross-sectional areas (before and after rolling, respectively). Further, the area reduction amount S is expressed by the following formula.

ΔS=So−Sl The ratio of the amount of metal transferred from the 7th lunge to the web with respect to the total area reduction, that is, the metal flow rate is determined by the following equation (1).

Metal flow IK=△M/△st%) ・・・・・・
(1) Figure 8 shows the metal flow rate △M/△S in secondary rough universal rolling with respect to the occurrence of web buckling and web through-through phenomena that occur in secondary rough universal rolling. and the ratio of the average thickness Tw of the web to the inner web width Bw at that time (web plate width ratio By / T
V]. However, at this time, the metal flow rate in the first rough universal rolling is 3.
I'm on the move.

In FIG. 8, the Δ mark indicates a material in which web buckling occurred, the mark indicates a material in which the web passed through, and the ○ mark indicates a material in which the web could be rolled well. As shown in FIG. 8, it has been found that when the web plate width ratio is in the range of 20 or more, rolling can be performed without problems if the metal flow rate is in the range of 1 to 4 inches.

Figure 9 shows the metal flow rate △M/△S in primary rough universal rolling with respect to the occurrence of web buckling and web through-through phenomena that occur in secondary rough universal rolling, which were obtained through various experiments. It shows the relationship with the web plate width ratio Bw/Tw at that time. However, the metal flow rate in the secondary rough universal rolling is 15%. The symbols in FIG. 9 are the same as in FIG. 8. As shown in FIG. 9, it has been found that when the web plate width ratio is in the range of 20 or more, rolling can be performed without problems if the metal flow rate is in the range of 11 to 7%.

Furthermore, Fig. 10 shows the relationship between the metal flow rate in the primary rough universal rolling and the monometal flow rate in the subsequent secondary set universal rolling with respect to the occurrence of web buckling and web through-through phenomena occurring in the secondary rough universal rolling. There are nine things that show relationships.

The web plate width ratio is the average value of the primary and secondary rough universals, and is shown for the case of 40. The ☆ mark in the figure indicates that web buckling and web end passing phenomena occur simultaneously, and the other details are the same as in FIG. 8. In this way, after rolling with a metal 70-rate in the range of 11% to 7% in the primary rough universal rolling mill, rolling with a metal flow rate in the range of 1 to 4 inches in the secondary rough universal rolling mill. It turns out that if you do it, you can roll it without any problems.

Therefore, in the rolling method of the prior art, by rolling under the nine conditions shown above, it is possible to stably roll without causing problems such as web buckling and web through-through phenomena. It is nine.

〔Example〕

The present invention was carried out using the split rolls shown in Figure 6 and (B) and (C).The arrangement of the rolling mill is shown in Figure 11.

First, the ends and flanges of the web are rolled down in the primary rough universal rolling mill 14-1, and then the central portion of the web, the flanges, and the ends of the flange are rolled down in the secondary rough universal rolling mill 14-2. After this process is rolled in multiple buses using reversible rolling, one of the finishing universal rolling mills 18
The flange is tilted on the bus and finished into an H-shaped steel product. Using a roll with the dimensions shown in Table 1, H800X30
From a steel billet for H-shape rolled with a breakdown roll for zero rolling, the nominal size is 700X30 within the rolling condition range according to the present invention.
0,800X300 and 900X300 H-beams were manufactured. Table 2 shows the cross-sectional dimensions of the product after breakdown rolling and in each case.

Table 1 In the case of 700 x 300, rolling is performed to reduce the inner width of the web by making the divided roll width of the primary rough universal rolling mill narrower than the inner width of the web of all materials, and at the same time narrowing the gap between hard rolls by the same amount. The next rough universal rolling mill 14-2 rolls with the same divided roll width as the first rough universal rolling mill 14-1 so that the inner web width of the material becomes 700 x 300, and then The finishing universal rolling mill 18 was set to have a web inner width of 1,700 x 30'o split roll width, and 7 lunges were raised to 700 x 30.
I finished it at 0.

In the case of 800X300, primary rough universal rolling mill 14
-1 and the finishing universal rolling mill 18's split roll width t-800 x 300, set to the web inner width dimension, and rolled.

For 900x300, use secondary rough universal rolling mill 1
4-2 The width of the divided roll is wider than the inner width of the web of material,
At the same time, the inner width of the web is expanded by widening the hard 6-ru spacing by the same amount.The primary rough universal rolling mill 1
In 4-1, the material is rolled with the same dividing roll width as in the secondary rough universal rolling mill 14-2, so that the inner width of the material becomes 900 x 300 mm.
Finishing universal rolling mill 18 with web inner width set to 90QX30Q
Finished to 90 In either case, the cross section after breakdown is the product cross section,
It is determined from the amount of metal transferred from the flange to the web in the casing that is rolled into the product, but in this example, only 800 x 300 rolls are used for breakdown rolling, so the web height and flange thickness are constant. , the web thickness and 7 lunge width are adjusted by changing the roll spacing at the end of breakdown rolling.

For such a cross-section after breakdown, in the range where the web width ratio is 20 or more, the metal flow rate is 3% in the primary rough universal rolling and λ5 in the secondary rough universal rolling.
It was rolled to give a square shape.

When the width ratio of the web was less than 20, rolling was performed under the above conditions.

As a result of rolling in this way, 700×300°800
No web buckling or web passing occurs even in the rolling of X300 and 900X300 chairs, and the dimensional accuracy of the product 1. The surface condition is also good and the yield is excellent. It goes without saying that it can be applied to the production of H-beam steel of any size with a web height of 700 to 900 from H-beam billets using rolls, and 700X
700X300 from a steel billet after breakdown rolling for 300
It can also be applied to the case of manufacturing 90ox300t from a 900x300 breakdown rolled steel billet.

〔Effect of the invention〕

As is clear from the above embodiments, the present invention incorporates variable-position horizontal split rolls into the primary rough universal rolling mill and the secondary rough universal rolling mill, and when performing partial rolling,
By limiting the metal flow rate in each bath, problems that adversely affect the rolling process and product value, such as web buckling and web throughput during rolling of H-section steel, can be resolved, and the optimum Since the cross-sectional dimensions can be determined in advance, there is no longer a shortage of the 7-lunge width, improving rolling efficiency.

Improved dimensional accuracy can bring many benefits.

[Brief explanation of the drawing]

Figures 1 and 2 are process diagrams of H-section steel hot rolling.
Figure 3, @, and D are cross-sectional views showing the shape of the hot-rolled H-section steel material; ), (Q are cross-sectional views showing the process of hot rolling of H-section steel, Figure 5 (2), (Bl
, (0, ([) are the same as those of the prior art primary rough universal rolling mill (to) and Edger rolling mill ■.Secondary rough universal rolling mill 0. Finishing universal rolling mill ■ Each roll shape and material Figure 6 is a cross-sectional view showing the rolls of the primary rough universal rolling mill, the secondary rough universal rolling mill ■, and the finishing 1 two-versal rolling mill (0) of the prior art. Cross-sectional view showing the shape and material, Fig. 7 (A). ■, (0 are the materials before the first universal rolling, respectively. After the first rough universal rolling (B), the materials after the second universal rolling (-0 after the monkey rolling) Figure 8 is a diagram showing the relationship between the web plate width ratio and the metal flow rate in secondary rough universal rolling with respect to the occurrence of defects during secondary rough universal rolling, and Figure 9 is a diagram showing the relationship between the metal flow rate in secondary rough universal rolling. A diagram showing the relationship between the web plate width ratio and the metal 70-ratio in the first rough universal rolling with respect to the occurrence of defective phenomena during universal rolling. Figure 10 shows the relationship between the occurrence of defective phenomena during the secondary rough universal rolling. FIG. 11 is a diagram showing the relationship between the metal flow rate in the first rough universal rolling and the metal flow rate in the second rough universal rolling, and FIG. 11 is a process diagram showing the hot rolling of nine H-shaped steel by carrying out the present invention. 2...Slab 4...Rectangular steel piece 6...
H-beam steel billets 12...Double breakdown rolling mill 14...Rough universal rolling mill 14-1...Primary rough universal rolling mill 14-2...
・Secondary roughing universal rolling mill 16... Edger rolling mill 18... Finishing universal rolling mill 26.28, 32.34... Horizontal split roll agent
Patent Attorney Takeo Nakaji Figure 1 (A) Figure 3 (A) (B) Figure 4 Figure 51XI Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 2≦HIMUshi9-Blue Positive 1st wear χri'a4 〒pu≦
Police (2≦) Figure 1I

Claims (1)

[Claims] (1) A primary rough universal rolling mill and a secondary rough universal rolling mill that are made of slabs, rectangular billets, steel billets for H-beam steel, etc., and incorporate horizontally split rolls whose axial positions can be varied for each bus. A hot rolling method for H-beam steel in which the inner width of the web is at least 20 times the web thickness, and the rolling of each bath is performed by rolling down the end of the web. In the primary rough universal rolling, the metal flow rate shown by the following formula (1) is set in the range of -1 to 7%, and in the secondary rough universal rolling in which the central part of the web is rolled down, the metal flow rate is set in the range of 1 to 4. A method for hot rolling H-beam steel, characterized by rolling within a range of 1. Metal flow rate = △M/△S (%) (1)
However, ΔM: Amount of metal transferred from the flange to the web during the rolling process ΔS: Total area reduction of the flange and web during the rolling process