JPH0141402B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for rolling an H-shaped rough-shaped steel billet, and in particular, to a method for rolling an H-shaped rough-shaped steel strip, which is suitable for hot rolling a beam blank with a substantially H-shaped cross section into a rough-shaped steel billet. Concerning a method of rolling a piece.

BACKGROUND ART Conventionally, in rolling large H-section steel, it has been desired to use continuous casting materials from the viewpoint of improving quality and yield. Here, when using blooms and slabs as continuous casting materials, since these materials have a rectangular cross section, when forming them into an H-shaped rough cross section for rolling H-shaped steel with a universal rolling mill. In addition, due to the difference in the rolling reduction ratio between the web part and the flange part, large cropped parts that do not form the product shape tend to occur at the front and rear ends of the rolled material. It is difficult to obtain a shaped flange, and furthermore, many rolling passes are required to form the H-shaped rough cross section. On the other hand, when a beam blank is used as a continuous casting material, since the beam blank has a substantially H-shaped cross section, the disadvantages encountered when using blooms and slabs are eliminated.

However, due to the simplification of continuous casting equipment, restrictions on mold changes, and efficient use of molten steel,
It is not appropriate to have a wide variety of approximately H-shaped cross-sectional shapes of the beam blank. Therefore, in order to make it possible to roll rough-shaped steel pieces with a wide range of cross-sectional shapes from a single beam blank, the rolling method shown in Fig. 1 has been used as a rolling method that increases the web height of intermediate rough-shaped steel pieces. Proposed. That is, in this rolling method, the rounded part of the hole 3A of the breakdown roll 2 is brought into contact with the inner surface of the flange of the intermediate rough-shaped steel billet 1, and the flange is pushed outward along the inclination angle θ of the inner surface of the flange. Furthermore, by expanding the flange outward by the holes 3B, the web height can be gradually increased. However, in the rolling method shown in FIG. 1 above, when the contact angle θ between the grooves 3A and 3B and the inner surface of the flange of the intermediate rough-shaped steel piece 1 is small, the inner wall of the flange is strongly rubbed down and folded into the flange. To avoid this, it is necessary to set a large contact angle θ, and it is difficult to increase the amount of increase in web height when the leg length h of the flange is short. That is, in the conventional rolling method described above, when rolling a beam blank into a rough shaped steel piece whose web height is significantly larger than the height of the beam blank, a large number of holes are required. .

The present invention provides an H-shaped rough shape that allows a beam blank to be rolled into a rough shape steel billet with a web height significantly larger than the height of the beam blank with good quality and high rolling efficiency. The object of the present invention is to provide a method for rolling steel billets.

In order to achieve the above object, the present invention provides a method for hot-rolling a beam blank with a substantially H-shaped cross section into a rough-shaped steel piece with a web height larger than the height of the beam blank using the hole shape of a rough rolling roll. A method of rolling an H-shaped rough-shaped steel billet to be rolled, in which the height of the web at the trailing end is reduced by rolling down only the web at the rear end in the rolling direction of the billet in the next rolling pass through the hole. By performing bit-back rolling to increase the thickness, and then, in the next rolling pass following the bit-back rolling, only the web extending over the entire length from the tip in the rolling direction of the steel billet is rolled down through the hole die. Rolling is performed to increase the web height of the entire piece, and both side surfaces of the steel piece on the exit side are guided by a billet exit guide device installed on the exit side of the rough rolling roll. so that both sides of the rear end portion of the steel billet in the rolling direction are guided by a billet entry side guide device which is disposed on the entry side of the steel billet and is set to have the same guide width as the billet exit guide device. This is what I did.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a front view showing each cross-sectional shape before and after rolling of an H-shaped rough section rolled according to the present invention,
FIG. 3 is a cross-sectional view of a main part showing a breakdown roll as a rough rolling roll used in an embodiment of the present invention, and FIGS. 4A to 4C show a rolling process in an embodiment of the present invention. FIGS. 5 and 6 are sectional views of essential parts showing rolling conditions according to the conventional rolling method, and FIG.
8 is a plan view showing a swimming state during rolling of an intermediate rough-shaped steel billet; FIG.
The figure is a plan view showing a rolling state in an embodiment of the present invention.

In the present invention, a beam blank 11 made of continuous casting and having _a substantially H-shaped cross section with _a height H ₀ and a width B ₀ as shown in FIG. 12, the web height H ₃ of the rough shaped steel piece 12 can be rolled to be larger than the height H ₀ of the beam blank 11. That is, after the beam blank 11 is heated and soaked in a heating furnace, it is rolled in a reversible double rolling mill in which the roll gap can be changed for each pass, and then the beam blank 11 is heated and soaked in a heating furnace. 14,15,1
6, the first to third steps detailed below.
Through the process, the area is reduced and formed and rolled into intermediate rough-shaped steel pieces 17, 18 and rough-shaped steel pieces 12 in sequence.

First, in the first step, the beam blank 11
is rolled into an intermediate rough shaped steel piece 17 by the groove 14 of the breakdown roll 13, as shown in FIG. 4A. In this first step, the main purpose is rolling to reduce the leg length h ₁ of the flange of the intermediate rough shaped steel slab 17, the web thickness t ₁ is not made too thin, and the web height H ₁ is the same as that of the beam blank 11. It is important not to make it too large compared to the height H ₀ .

The reason why the web thickness t ₁ is not made too thin in the first step is as follows.
Firstly, if the web thickness t ₁ is reduced in the first step, the web rolling reduction rate in the second step becomes small, making it impossible to significantly increase the web height H ₂ . Second, when the web thickness t ₁ becomes thinner from the first step of rolling, the temperature drop of the web and, by extension, the temperature drop of the intermediate rough shaped steel slab 17 becomes large, making it difficult to proceed smoothly with rolling. Not only that, but it also creates a large temperature difference between the web and the flange, which is unreasonable, creating residual stresses in the final H-beam product as it cools after leaving the finishing universal mill.

Further, the reason why the web height H ₁ is not made much larger than the height H ₀ of the beam blank 11 in the first step is as follows. That is, when reducing the leg length h ₁ of the flange of the intermediate rough-shaped steel piece 17 and simultaneously increasing its web height H ₁ , as shown in FIG.
Wrinkle flaws 19 are generated on the outer surface of the flange of No. 7, and the wrinkle flaws 19 tend to remain as linear flaws on the final product, which is not appropriate. Therefore, in the first step, both sides of the hole mold 14 are rather overfilled, and the intermediate rough shaped steel piece 17
It is necessary to set the web height H ₁ to a size that is not too large compared to the height H ₀ of the beam blank 11 to the extent that a protrusion 20 as shown in FIG. 6 is generated on the outer surface of the flange of the beam blank 11. . Note that the protrusion 20 formed on the outer surface of the flange of the intermediate rough shaped steel piece 17
Then, with the intermediate rough shaped steel piece 17 turned 90 degrees, the protruding portion 20 is placed in the center of the hole mold 16.
This can be corrected by performing an edging rolling process to the extent that the problem is suppressed and eliminated.

Next, the intermediate rough-shaped steel piece 17 rolled in the first step is rolled into an intermediate rough-shaped steel piece 18 by the groove 15 of the breakdown roll 13 in the second step, as shown in FIG. 4B. Ru. The main purpose of this second step is to increase the web height H ₂ and reduce the web thickness t ₂ by rolling down only the web. In other words, since only the web of the intermediate rough shaped steel piece 18 is rolled and the flange is not rolled at all, the metal flow of the entire rolled material is more likely to widen than when stretched in the longitudinal direction of rolling, and a large web is formed. An increase in height H ₂ is obtained. Therefore, the hole mold 15 used in this second step has a depth g that is deeper than the leg length h ₂ of the flange of the intermediate rough-shaped steel piece 18 so as not to compress the flange of the intermediate rough-shaped steel piece 18. It is necessary to have a groove. In addition,
In this second step, the web height H ₂ of the intermediate rough shaped steel piece 18 decreases as the web thickness t ₂ decreases.
Although it is possible to increase the web height H of the intermediate rough-shaped steel piece 17 in the previous step to the width f of the hole mold ₁₅ , the web height H of the rough-shaped steel piece 12 to be formed and rolled in the next third step. ₃ .

By the way, in the second step, the flange of the intermediate rough-shaped steel piece 18 is not restrained by the hole 15 and is freely movable in the direction perpendicular to rolling. As shown in FIG. 7, the rear end of the roll 18 tends to swim left and right during rolling. That is, the above-mentioned second method of the rolling method according to the present invention
In the process, since the web height of the intermediate rough shaped steel billet 18 changes with each pass, the guide width L of the exit manipulator 21 as the billet exit guide device is
and the guide width L of the entry side manipulator 22 as the steel billet entry side guide device, respectively, are determined by the intermediate rough shaped steel piece 1.
It is not easy to automatically set the respective guide widths L of both manipulators 21 and ₂₂ to be different from each other according to the exit side web height l ₂ and entry side web height l 1 of 8. The guide width L is
The width is set to the same width that can be adapted to the exit web height l ₂ of the intermediate rough shaped steel piece 18 in each pass. Therefore, in the second step, when the entrance web height l ₁ of the intermediate rough shaped steel piece 18 is much smaller than the exit web height l ₂ , the intermediate rough shaped steel piece 18 If a large gap is left between the rear end in the rolling direction and the entry manipulator 22, the rear end in the rolling direction of the intermediate rough shaped steel billet 18 will swing left and right, and its flange will be aligned with the hole shape 15. There is also a risk that the web will get caught in the rolling part, making rolling impossible.

Therefore, in the second step, the rear end portion of the intermediate rough shaped steel piece 18 in the rolling direction can be guided by the entry side manipulator 22 to prevent the occurrence of swimming as described below. That is, at the end of the preceding pass, as shown in FIG. 8, the guide width L ₀ of the exit manipulator 21 in the preceding pass moves the rear end side of the intermediate rough shaped steel billet 18 in the rolling direction in the next rolling pass. While positioning, the rear end N of the intermediate rough shaped steel piece 18 in the rolling direction is inserted into the hole 15 of the roll gap corresponding to the next pass. Intermediate rough shaped steel piece 1
When the rear end N in the rolling direction of No. 8 reaches the entrance manipulator 21, both manipulators 21,
The guide width of 22 is set as the exit web height in the next pass.
The guide width L should be compatible with l ₂ . Here, the intermediate rough-shaped steel piece 18 on the entry side manipulator 21 side is a long rolled material and stably moves straight due to its own weight. Under such conditions, the rear end N of the intermediate rough shaped steel piece 18 in the rolling direction becomes slightly longer (0.5 m or more) than the distance M from the roll axis to the tip of the exit manipulator 21. After rolling down only the web at the end N, the breakdown roll 13 is reversed, and the intermediate rough-shaped steel piece 18 is rolled into the groove 1.
5 Chew again. By this back-rolling, the web height of the rear end N of the intermediate rough shaped steel piece 18 in the rolling direction is increased to the same size as the exit web height l ₂ in the next pass. Therefore, when the intermediate rough-shaped steel piece 18 is bitten back from the hole mold 15, the roll gap is opened and the intermediate rough-shaped steel piece 18 is air-fed in the opposite direction of rolling, and then, as shown in FIG. In the next pass shown in FIG. 2, the roll gap is set to the rolling state, and the guide width of the outlet manipulator 21 is set to the guide width L that matches the outlet web height _l2 in the pass, and the intermediate roughening is performed. By rolling down only the web of the shaped steel piece 18 over its entire length from the tip in the rolling direction, rolling is performed to increase the web height of the entire intermediate rough shaped steel piece 18. In the path shown in FIG. 9, both side surfaces of the intermediate rough shaped steel piece 18 on the exit side are guided by the exit side manipulator 21, and the rear end N of the intermediate rough shaped steel piece 18 in the rolling direction is guided by the exit side manipulator 21.
Since both sides of the intermediate steel billet 18 are guided by the entrance manipulator 22, it is possible to complete rolling without the intermediate rough shaped steel billet 18 moving left and right during rolling.

Finally, the intermediate rough-shaped steel piece 18 rolled in the second step is rolled into a rough-shaped steel piece 12 by the groove 16 of the breakdown roll 13 in a third step, as shown in FIG. 4C. . In this third step, the intermediate rough-shaped steel piece 18 whose flange width was made small in the first step and whose web height was made large in the second step is turned into a desired H-beam steel by a universal rolling mill. The purpose is to obtain a rough-shaped steel piece 12 whose shape and dimensions are adjusted so that it can be rolled. That is,
In this third step, a light reduction is applied to the intermediate rough shaped steel piece 18 to the extent that the non-uniformity of the cross section that has occurred is made uniform.

According to the above embodiment, the beam blank 11 is
It becomes possible to roll the steel piece 12 into a rough shaped steel piece 12 having a cross-sectional shape significantly different from the cross-sectional shape of the beam blank 11. That is, the rolling range of the rough shaped steel piece 12 rolled from the single beam blank 11 is expanded. Therefore, without diversifying the cross-sectional shapes of the continuous casting beam blank 11, it is possible to obtain H-shaped rough shaped steel pieces with various cross-sectional shapes from the beam blank 11 with a single cross-sectional shape, and as a result, it is possible to obtain H-shaped rough shaped steel pieces with various cross-sectional shapes. It becomes possible to obtain H-beam steel.

Further, according to the above embodiment, the main purpose is to reduce the leg length h ₁ of the flange of the intermediate rough shaped steel piece 17 in the first step, and the web thickness t ₁ is not made too thin in the first step. , the temperature drop of the web itself and, by extension, of the entire intermediate rough shaped steel piece 17 is small, so that the smooth progress of rolling is not hindered by the temperature drop of the rolled material, and the temperature difference between the web and the flange is reduced. is not large, and therefore no residual stress is generated in the final H-section steel product. Note that, contrary to the present invention, if the web height is mainly increased in the first step and then the flange width is decreased in the second step, the web height will be increased in the first step and the web thickness will be decreased. Because it is thinner, it is difficult to edging-roll the protrusion formed on the outer surface of the flange in the first step with a 90 degree turn, and the groove of the breakdown roll becomes deep, which is not appropriate.

In addition, according to the above embodiment, since the main purpose of the second step is to increase the web height H ₂ by rolling down only the web of the intermediate rough-shaped steel piece 18, the one-hole type web height
It becomes possible to increase the amount of _H2 , and it becomes possible to save the number of holes and the length of the breakdown roll 13. That is, according to the above-mentioned embodiment, the single hole die 16 gives the intermediate rough shaped steel piece 18 the deformation equivalent to the two hole shapes 3A and 3B of FIG. 1 according to the conventional example. becomes possible.

Further, according to the above embodiment, in the second step, the intermediate rough-shaped steel billet 18 is subjected to back-rolling to increase the web height of the rear end portion N in the rolling direction in the next rolling pass, and then In the next rolling pass following the bit-back rolling, rolling is performed to increase the web height over the entire length from the tip end in the rolling direction of the intermediate rough-shaped steel slab 18, and both sides of the exit side of the intermediate rough-shaped steel slab 18 and Since both entrance side surfaces can be guided by the exit side manipulator 21 and the entrance side manipulator 22, which are set to the same guide width,
It becomes possible to proceed with rolling to increase the web height under stable conditions without causing any swimming in the rear end portion of the intermediate rough shaped steel piece 18 in the rolling direction.

In addition, although the above embodiment described the case where the present invention is applied to a continuous casting beam blank,
The present invention is also applicable to beam blanks that are roughly rolled from agglomerated materials using blooming rolls. In that case, the content of the equipment for the blooming roll can be simplified, and even if the cross-sectional shapes of the beam blanks obtained by the blooming roll are small, each beam blank can be made into a web whose height is significantly different from that of the beam blank. This makes it possible to roll H-shaped steel slabs with different cross-sectional shapes from a beam blank with a single cross-sectional shape, which in turn makes it possible to obtain H-shaped steel slabs with various dimensions. becomes possible.

As described above, the present invention provides an H-shaped beam blank in which a beam blank having a substantially H-shaped cross section is hot-rolled into a rough-shaped steel piece with a web height larger than the height of the beam blank using the hole shape of the rough rolling roll. A method for rolling a roughly shaped steel billet, in which only the web at the rear end in the rolling direction of the steel billet is rolled down through the hole in advance in the next rolling pass, thereby increasing the height of the web at the rear end. Then, in the next rolling pass following the back-rolling, only the web extending over the entire length from the tip in the rolling direction of the billet is rolled down through the hole, thereby reducing the entire length of the billet. In addition to rolling to increase the web height, the billet exit side guide device installed on the exit side of the rough rolling rolls guides both sides of the billet on the exit side, and The steel billet entry side guide device, which is disposed at It has the advantage that the blank can be rolled into a rough shaped steel billet with a significantly larger web height compared to the height of the beam blank, with good quality and high rolling efficiency.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the main part showing the rolling situation by the conventional rolling method, Fig. 2 is a front view showing the cross-sectional shape of the rough-shaped steel piece before and after rolling, which is rolled by the present invention, and Fig. 3 is the present invention. FIG. 4A, FIG. 4B, and FIG. 4C are main part sectional views showing different rolling processes in one embodiment of the present invention. , FIG. 5 and FIG. 6 are sectional views of main parts showing the rolling situation according to the conventional rolling method, FIG. 7 is a plan view showing the swimming state of the intermediate rough-shaped steel billet during rolling, and FIG. 8 is the present invention. FIG. 9 is a plan view showing the back-rolling state in one embodiment of the present invention. FIG. 9 is a plan view showing the rolling state in one embodiment of the present invention. 11... Beam blank, 12... Rough shaped steel piece,
13...Breakdown roll, 14,15,1
6... Hole shape, 17, 18... Intermediate rough shaped steel piece, 21
...Exit side manipulator, 22...Input side manipulator.

Claims (1)

[Claims] 1. A method for rolling an H-shaped rough-shaped steel billet in which a beam blank with a roughly H-shaped cross section is hot-rolled into a rough-shaped steel billet whose web height is larger than the height of the beam blank using the hole shape of a rough rolling roll. In advance, only the web at the rear end in the rolling direction of the steel billet in the next rolling pass is rolled down by the hole mold, thereby performing back-rolling to increase the height of the web at the rear end,
Next, in the next rolling pass following the back-rolling, rolling is performed to increase the web height of the entire steel billet by rolling down only the web extending over the entire length from the tip of the steel billet in the rolling direction through the hole. At the same time, the billet exit side guide device installed on the exit side of the rough rolling roll guides both sides of the exit side of the steel billet, and Rolling of an H-shaped rough shaped steel billet, characterized in that both sides of the rear end of the billet in the rolling direction are guided by a billet entry guide device which is set to have the same guide width as that of the exit guide device. Method.