JP3095896B2 - Method and apparatus for producing H-section steel rich in toughness and strength - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing an H-section steel, and more particularly to a method and an apparatus for improving the material of a fillet portion of a section steel to provide an H-section steel having high toughness and strength. It is.

[0002]

2. Description of the Related Art The toughness / strength of an H-section steel is most inferior at a fillet portion (hereinafter referred to as an R-section) at each position of a cross section. Improvement of properties ”has been published (Kawasaki Steel Technical Report, VOL.11,
(1979), No. 4, 515-524). According to this report, the inferior strength and toughness of the R-section of the H-section steel is due to the fact that the rolling temperature at that portion is the highest among the various cross-sectional positions, and the cooling rate after rolling is slow and the ferrite grain size increases. For this reason, one rough universal mill rolling is used to form a convex part on the outside of the R part, and the finished universal mill is subjected to low-temperature concentrated strong pressure, or two or more continuous rough universal mills are used to form the R part inside and outside. It has been shown that the material structure of the R portion is remarkably improved by alternately forming a convex shape and reciprocating rolling at a low temperature.

As a method for improving the toughness and strength of a section steel having a complicated cross-sectional shape such as an H-section steel, forcibly cooling the material to be rolled after finish rolling is disclosed in, for example, Japanese Patent Application Laid-Open No.
253721 and JP-A-2-22414. The former is intended to increase strength while preventing distortion (web wave) from occurring in a web when a thin H-section steel having a large flange thickness / web thickness ratio and a small web thickness is manufactured by rolling. The aim was to achieve a uniform rolling finish temperature of the thick flange by setting the finishing temperature of the steel above the transformation point of the steel, that of the thin web below the transformation point, and forcibly cooling only the flange at a predetermined cooling rate after rolling. It is intended to produce an H-beam with high toughness and strength.

[0004] In the latter case, for example, in an H-section steel having different thicknesses of the web and the flange, if the thickness of the thin portion is smaller than 15 mm, the thin portion is air-cooled after low-temperature rolling, and the thick portion is forcibly cooled after final finishing rolling. When the thickness of the thin portion is 15 mm or more, high-strength products are manufactured by forcibly cooling after the final finish rolling under different conditions for the thin portion and the thick portion.

On the other hand, Japanese Patent Laid-Open Publication No. Sho 50-112260 (Japanese Patent Publication No. 53-16789) discloses a method of correcting the squareness between a flange and a web by forcibly water-cooling an R portion before finish rolling of a shaped steel. Is stated.

[0006]

However, as disclosed in the above-mentioned technical report, there is a method for repeatedly subjecting an H-shaped steel R portion to strong pressure reduction at a low temperature in order to improve the mechanical properties of the H-shaped steel R portion. The problem is that the stand-by rolling is a condition in which the material to be rolled is made to stand by in the middle of rolling to a predetermined low temperature, and the temperature of the web having a higher cooling rate than the R portion is excessively lowered during the stand-by. And for those with a large flange thickness, R
Due to the large size of the part, it is necessary to increase the rolling reduction when forming into a convex shape, and the rolling load, rolling torque, and roll surface pressure increase, resulting in reduced workability, roll wear, and roll flatness. There has been a problem of affecting the dimensional accuracy of the product.

[0007] Further, as disclosed in JP-A-62-253721 and JP-A-2-22414, by forcibly cooling a predetermined portion to a predetermined temperature after rolling, toughness,
In the prior art for manufacturing a high strength H-section steel, the cooling portion is limited to one-side cooling, such as the outer surfaces of the left and right flanges of the H-section steel and the lower surface of the web. The temperature difference between the inner and outer surfaces of the flange increases, which tends to cause shape defects such as warpage of the flange and improper squareness due to thermal stress.In particular, when the thickness of the flange is increased, the material properties on the inner and outer surfaces of the flange become more uneven. The problem is that the uniformity of the product cannot be guaranteed for all the cross sections.

[0008] Further, R before the finish rolling disclosed in Japanese Patent Application Laid-Open No. Sho 50-112260 (Japanese Patent Publication No. 53-16789).
The purpose of forced water cooling of the part is to correct the perpendicularity between the flange and the web, and is to cool the R part in one pass before finish rolling, and the difference between the upper and lower parts of the deformation resistance of the material to be rolled is reduced. Even if it is sufficient for control, it cannot be applied to the increase in the amount of strain intended for improving the material intended by the present invention. Moreover, if the inner surface of the upper R portion is water-cooled when the web thickness of the final pass is thin,
Since the water temperature occurs on the web due to the water riding, the inner surface of the upper R portion is not actually cooled, and only the water cooling of the inner surface of the lower R portion is practically used.

Therefore, the present invention has been made in view of the above-mentioned conventional problems. By combining the strong water cooling and the strong rolling of the R portion of the H-section steel, the synergistic effect of the rolled material can be obtained. It is an object of the present invention to provide a method and an apparatus for manufacturing an H-section steel, which promotes the refinement of the structure, and in particular, can improve the toughness and strength of the R portion even when the thickness is large and the R portion is large.

[0010]

According to the present invention, there is provided a method for producing an H-section steel, which comprises the steps of hot rolling a material to be rolled with two coarse universal mills. At the same time, a concave hole die is provided at a corner of a horizontal roll of one mill and a central portion of a vertical roll of the other mill for strongly reducing a fillet portion of a material to be rolled. Water cooling means and material to be rolled
The inner surface of the fillet on the web guide that guides the web surface
A cooling nozzle is provided , and immediately before rolling, at least the fillet portion of the material to be rolled and the inner and outer surfaces of the flange in the vicinity thereof are strongly cooled and reciprocally rolled by the coarse universal mill, and the inside and outside of the fillet portion are alternately cooled at a low temperature. Is repeated a plurality of times, followed by rolling with a finish universal mill.

Further, the apparatus for producing an H-section steel according to the present invention comprises a coarse universal mill having concave grooves on both sides of a horizontal roll, a coarse universal mill having concave grooves at the center of a vertical roll, and both mills. A coarse universal mill group consisting of an edging mill disposed in the middle, a cooling device disposed on the front and rear surfaces of the coarse universal mill group and cooling the vicinity of the fillet portion of the material to be rolled with water from inside and outside the flange, A web guide for guiding a web surface is provided with a rolled material guide device having a fillet portion inner surface cooling nozzle for the material to be rolled and disposed before and after the coarse universal mill.

In the above manufacturing apparatus, the curved surface shape of the horizontal roll of the first-stage coarse universal mill and the curved surface shape of the horizontal roll of the second-stage coarse universal mill are used. It can be selected from any of the intermediate curved surface shapes.

[0013]

As described in the above-mentioned technical report, the present inventors have been preparing H-section steel by standby rolling.
The longer the waiting time for lowering the material to a predetermined temperature (ie, the greater the degree of temperature decrease), the greater the amount of distortion in the R portion, the finer the structure, and the more significant the material improvement effect becomes. By paying attention, it was thought that the water cooling technology cultivated by the present applicant could be used to obtain the same effect. By combining strong water cooling and high pressure reduction of the R part of the H-section steel, the synergistic effect has been used to promote the refinement of the microstructure of the material to be rolled and to improve the material quality. The present inventors have found that the most remarkable effect can be obtained by lowering the temperature to below the Ar ₃ transformation point to carry out high-pressure rolling, thereby achieving the present invention.

In the method for producing an H-section steel according to the present invention, R
A mill layout for strongly reducing the portion and a cooling means capable of immediately performing the strong reduction by strongly cooling the R portion with water are required.
For the mill layout, for example, in the case of mill array with rough universal mill of the two groups, the concave grooved on both sides of the horizontal roll HU ₁ of the first stage crude Universal mill (U ₁₎ as shown in FIG. 1 1 provided with a, it is concave grooved 2 provided at the center of the vertical roll VU ₂ of the second stage coarse universal mill (U _2). By reverse rolled by the rough universal mill, strong pressure of a vicinity of the R portion of the flange outer surface of the rolled material in U _1, the U ₂ flange inner surface R
The overpressure of the part is repeated. The above-described roll shape is preferable from the viewpoint of the first pass of the coarse universal mill.
However, considering that the vertical roll is undriven, because reversed and feed material to be rolled from U ₂ to U ₁ in reverse path, if rolling reduction bite be no problem in the first pass , 2 pass a concave grooved 1 on both sides of the horizontal roll HU ₂ of U ₂ which is a first stage in (reverse path) is provided, U _1
1 may be arranged in a mill shape opposite to that of FIG.

When the edging mill E ₁ is arranged between the first-stage coarse universal mill (U ₁ ) and the second-stage coarse universal mill (U ₂ ), the horizontal roll HE ₁ of the E ₁ mill is removed. Either a solid body roll (calibur edger) or an edger roll with variable width and variable leg length may be used. Further, the curved shape of the sides of the horizontal roll HE ₁ edging mill E _1, curved surface having a concave grooved first horizontal roll HU ₁ of the first stage crude universal mill (or second stage rough universal mill HU ₂ formed on the same curved surface) of the horizontal roll, when rolling the vicinity R portion of the web surface of the rolled material in its horizontal roll HE _1, in the non-reduction horizontal roll HU ₁ of the first stage crude universal mill U ₁ The portions of the concave mold 1 on both sides (ie, the convex portions of the material R to be rolled) may be rolled. However, in the case of insufficient Mirupawa edging mill E _1, the horizontal roll HU ₁ non pressure portion of U ₁ is preferably towards the method of rolling in the subsequent second stage rough universal mill U _2.

Alternatively, the first-stage coarse universal mill U
₁ and in aim to increase the rolling pass of the R portion of the second stage rough universal mill in consideration of the reduction balance between U ₂ the material to be rolled, the curved shape of the roll both sides of the horizontal roll HE ₁ edging mill E ₁ , formed in the middle of the curved surface shape of the curved shape of the horizontal roll HU ₁ of the first stage crude Universal mill and the curved shape of the horizontal roll U ₂ of the second stage coarse universal mill, the convex of the rolled material R unit by it It is also effective to use the training effect on the shaped part.

Finish universal mill U _F for finish rolling
The vertical also its horizontal roll HU _F roll VU _F
May have a normal roll profile as shown in FIG. For the forced cooling of the R portion, it is necessary to arrange a cold water nozzle so that the outer surface and the inner surface on one side of the flange of the material to be rolled can be simultaneously cooled, in order to equalize the temperature difference inside and outside the flange, In order to more strongly cool the vicinity of the R portion where the heat capacity is particularly large than that of the other portions, it is desirable that the nozzle aimed at the vicinity of the R portion should have a larger cooling water injection amount than the other nozzles. Such a water cooling system 10
It includes a front face of the first stage crude universal mill U ₁ shown in FIG. 1, on the rear surface of the second stage coarse universal mill U _2, symmetrically arranged on both sides respectively across the pass line.

Furthermore in order to perform strongly cooling the upper and lower R portion surface of the material to be rolled, entry side generally each coarse universal mill U _1, U ₂ to perform the appropriate guidance of the rolled H-shaped steel as well as/
Alternatively, it is preferable to provide a water cooling facility (a cooling nozzle hole or the like) 40 capable of directly injecting the cooling water into the web guide portion by using a guide device arranged on the outlet side and directly aiming at the R portion. . In this case, as the guide device, a variable width guide (chance-free guide) that can guide the inner surface of the flange of the material to be rolled and the flange end and can change the distance (leg length) between the web and the flange end is preferable. R targeted
This is because the portion can be reliably cooled.

The present invention uses the cooling means and the rolling means as described above to rapidly and forcibly cool the material to be rolled, particularly the fillet portion and the inner and outer surfaces of the flange in the vicinity thereof, to the Ar ₃ transformation point or less. The structure in the vicinity of the R portion is refined by repeating the intense reduction, and then rolled by a finish universal mill, thereby producing an H-section steel having high toughness and strength.

[0020]

Embodiments of the present invention will be described below. An actual machine experiment of a mill layout having two coarse universal mills shown in FIG. 1 was carried out as follows. The test material has a product size of 294 x 200 x 8 x 12 (web height x flange width x
Web thickness x flange thickness mm), and the composition of the components is as shown in Table 1.

[0021]

[Table 1]

The rolling conditions were set as follows. In the case of the present invention, a heating temperature of 1250 ° C. and a breakdown mill (B
D mill) is subjected to reverse rolling by a rough universal mill group U _R (U _1, U ₂ ) provided with a concave hole shape in a horizontal roll or a vertical roll.
Formed alternately convex protrusions on the outside or inside of the part to produce a H-shaped steel products with lower concentration strongly pressed by the universal mill U _F finishing it.

Table 2 shows details of the experimental conditions in comparison with the case of the conventional production method.

[0024]

[Table 2]

In the case of the conventional production method indicated by No. 1 in the table, rolling was performed in the same manner as described above using a horizontal roll or a vertical roll of a coarse universal mill having no concave hole. Also,
In the case of the conventional controlled rolling method indicated by No. 2 and No. 3, the material was made to stand by to a predetermined temperature after two passes of the rough rolling, and then the control rolling (CR) was performed. For cooling,
In the case of the present invention, forced water cooling was performed on the outer surface of the flange and the R portion using an apparatus described later.

In the conventional method, no forced water cooling was performed. FIG. 2 to FIG. 5 show the hole shape (roll profile) of the roll of the coarse universal mill U _R used for manufacturing the H-section steel of the present invention. Figure 2 is intended horizontal roll HU ₁ of the first stage crude universal mill, FIG. 3 is an enlarged view thereof. Further, FIG. 4 is intended vertical roll VU ₂ of the second stage coarse universal mill, FIG. 5 is an enlarged view thereof.

FIG. 6 is a schematic diagram of the water cooling device 10 disposed on the front and rear surfaces of the coarse universal mill U _R. In addition, this figure shows only one side which is arranged on both sides of the rolling line. Reference numeral 11 denotes an H-shaped steel as a material to be rolled, which is mounted on a table roller (not shown) of a rolling line.
The nozzle guide wheel 12 placed on the side of the H-section steel 11 is provided with a plurality of flange outer surface cooling nozzles 13 facing the outer surface of the flange 11F, and cooling supplied from an outer surface cooling nozzle header 14 is provided. Water is sprayed onto the outer surface of the flange 11F to be cooled with water. The nozzle position is adjusted by moving the flange outer surface cooling nozzle 13 up and down by the elevating motor 16 of the nozzle mounting support 15 in accordance with the flange width that changes depending on the size of the H-section steel 11. The nozzle guide wheel 12 is connected to a flange inner surface upper cooling nozzle carriage 20A on which a connection block 19 on which an output screw shaft 18a of a flange inner / outer surface nozzle guide interval adjusting motor 18 is screwed is mounted.
A bogie 20B for the cooling nozzle at the lower portion of the inner surface of the flange is connected to the bogie 20A via a bogie connecting screw shaft 22. Both carriages 20A, 20B are mounted on a nozzle elevating beam 23 so as to be able to travel freely, and the nozzle elevating beam 23 is supported by a lift lever 25 driven by a beam elevating motor 24 so as to be able to elevate and lower. The cart 20B
The flange inner surface lower cooling nozzle 26A _1, 26A ₂ and water supply header 27A ₁ Part, 27A ₂ are mounted.

Further, the flange inner surface upper cooling nozzle carriage 20A, further through the support 10S, flange inner surface upper cooling nozzle 26B _1, 26B ₂ and the water supply header 28B _1, 28B ₂ and their elevation motor 29 or the like Is installed. Since the nozzles of the outer cooling surface 13 of the water cooling device, the lower cooling nozzle 26A of the inner flange surface, and the upper cooling nozzle 26B of the inner flange surface can all be moved up and down and horizontally in a direction perpendicular to the rolling line, the H-shape is used. The position is appropriately set according to the size of the steel 11, that is, the change in the web height, the flange width, and the flange thickness, and the injection area of the cooling water is kept optimal. In addition, it has a function of independently controlling the on / off of each nozzle to arbitrarily adjust the timing of cooling water injection. In addition, among the nozzles of the cooling device 10, the flange inner surface lower cooling nozzle 26 A ₁ and the flange inner surface upper cooling nozzle 26
With respect to B _1, is more effective when the cooling water injection quantity to more than others nozzle.

FIG. 7 shows a chance-free (variable width) guide device 3 disposed on the entrance side and the exit side of the first-stage coarse universal mill U ₁ and the second-stage coarse universal mill U ₂ , respectively.
0 shows a schematic diagram. This figure shows only the lower one of the ones arranged above and below the rolling line. The guide device 30 basically includes a pair of left and right flange width restraining rollers 31 that abut against and constrain the end surface of the flange 11F of the material 11 to be rolled, and a pair of right and left webs that guide the web 11W of the material 11 to be rolled. And a guide 32. A plurality of flange width restraining rollers 31 are rotatably supported by a bearing box 33 and are arranged in the longitudinal direction of the material 11 to be rolled. On the other hand, the web guide 32 is also extended along the longitudinal direction of the material 11 to be rolled, and is supported by the guide frame 34 integrally with the flange width restraining roller 31. A guide width varying device 36 provided with a drive motor 35 is attached to each of the left and right sides of the guide frame 34, whereby the pair of left and right flange width restraining rollers 31 and the web guide 32 are independently moved left and right. The guide width can be adjusted according to the size of the material 11 to be rolled.

The guide frame 34 can be moved in the vertical direction by a jack type lifting device 37 installed below. The elevating devices 37 are installed in a pair on the left and right, and are driven by a single driving source (not shown) via a driving shaft 38 in order to minimize the level difference between the left and right. Further, the guide frame 34 is provided with a pair of left and right roller lifting devices 39 for vertically moving the respective flange width restraining rollers 31 individually. The roller lifting / lowering device 39 rotates the lift rod 39A connected to the lower end of the bearing box 33 of the flange width restraining roller 31 by the roller height setting motor 39D via the worm speed reduction mechanism 39B and the transmission 39C. Then, the flange width restraining roller 31 is moved up and down relatively to the web guide 32. Thereby, the vertical interval from the roller surface of the flange width restraining roller 31 to the guide surface 32a of the web guide 32 can be freely adjusted, and the material 11 to be rolled can be adjusted.
Even if there is a change in the size of the flange leg length, etc., or the wear of the flange width restraining roller 31 or the web guide 32, the distance between the web 11W and the web guide 32 is always properly maintained while restraining the end surface of the flange 11. .

The web guide 32 of the present invention has not only the above-described position correcting function but also a forced cooling function of the R portion of the material 11 to be rolled. That is, FIG.
As shown in the figure, the guide surface 32 on the upper part of the web guide 32
The cooling water from a cooling water supply source (not shown) can be directly injected into the R portion of the material 11 to be rolled by providing an R portion inner surface cooling nozzle 40 opened at a.

Table 2 shows the conditions and measurement results (reduction data, processing temperature, etc.) of this experiment in comparison with those of the conventional case. Also,
9 shows, the finishing universal mill U _F by the rolled material 1
The relationship between the finish rolling temperature (scale on the horizontal axis) of the R portion of No. 1 and the lower yield point (LYP) and brittle ductile fracture transition temperature (Trs) of the product of the present invention obtained in the above-described production experiment was obtained. The results are shown in comparison with the results of the conventional product.

From the above test results, the following became clear. The yield point and the transition temperature of the product obtained by the method of the present invention are greatly improved as compared with the conventional method and the controlled rolling method. From these results, according to the method of the present invention in which the structure of the fillet portion was densified by a combination of forced cooling and high pressure reduction and the rolling temperature of finish rolling was conventionally reduced, the material of the fillet portion (R portion) of the product was It is clear that the improvement effect is remarkable.

[0034]

As described above, according to the present invention,
Since rolling was performed by repeatedly applying high pressure and forced water cooling around the R-section of the H-section steel, the size of the R-section where the flange and the web were joined was large in the case of the H-section steel. Toughness) can be improved compared to other cross-sections, dimensional accuracy is good, product uniformity can be guaranteed for all cross-sections, especially large H-section steel with large thickness and large R section Also, the effect of improving toughness and strength can be achieved without relying on complicated rolling methods such as controlled rolling.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a mill layout in a manufacturing process of the present invention.

FIG. 2 is a diagram showing a rough-rolled horizontal roll profile of one embodiment of the present invention.

FIG. 3 is an enlarged view of a part III in FIG. 2;

FIG. 4 is a diagram showing a rough-rolled vertical roll profile according to an embodiment of the present invention.

FIG. 5 is an enlarged view of a portion V in FIG. 4;

FIG. 6 is a schematic view of a water cooling device according to an embodiment of the present invention.

FIG. 7 is a front view showing a cross section of a part of the guide device according to the embodiment of the present invention.

8 is a cross-sectional view of the water cooling means, showing an enlarged portion VIII of the web guide of FIG. 7;

FIG. 9 is a graph showing the relationship between the temperature of the R-roll finish rolling of the material to be rolled, the yield point, and the transition temperature in comparison with the conventional case and the present invention.

[Explanation of symbols]

U ₁ first stage coarse universal mill HU ₁ horizontal roll VU ₁ vertical rolls U ₂ second stage rough universal mill HU ₂ horizontal roll VU ₂ vertical roll 10 cooling device 11 the rolled material 11W web 11F flange 30 guide apparatus 32 web guide 40 R part inner surface cooling nozzle

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-55-40057 (JP, A) JP-A-62-54519 (JP, A) JP-A-50-112260 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B21B 1/08 B21B 27/02 B21B 45/02 320

Claims (3)

(57) [Claims] 1. A method for producing an H-section steel including a step of hot-rolling a material to be rolled by two coarse universal mills, wherein a corner portion of a horizontal roll of one of the mills is strongly reduced in a fillet portion of the material to be rolled. And the center of the vertical roll of the other mill are provided with concave holes, respectively, and water cooling means for the material to be rolled is provided on the front and rear surfaces of the mill stand, and the web surface of the material to be rolled is also provided.
A fillet part inner surface cooling nozzle is arranged in the guiding web guide, and immediately before rolling, reciprocating rolling is performed by the coarse universal mill while strongly cooling at least the fillet part of the material to be rolled and the inner and outer surfaces of the flange in the vicinity thereof. A method for producing an H-section steel having high toughness and strength, characterized in that the inside and the outside of the fillet portion are alternately formed into a convex shape at a low temperature a plurality of times, and then rolled by a finish universal mill. 2. A coarse universal mill having a concave hole shape on both sides of a horizontal roll, a coarse universal mill having a concave hole shape at the center of a vertical roll, and an edging mill disposed between the two mills. Universal mills,
A cooling device disposed on the front and rear surfaces of the rough universal mill group to cool the vicinity of the fillet portion of the material to be rolled with water from inside and outside of the flange, and a web guide for guiding the web surface of the material to be rolled. An apparatus for manufacturing an H-shaped steel, comprising: a rolled material guide device provided before and after a coarse universal mill with an inner surface cooling nozzle. 3. The curved surface shape of the horizontal roll of the first-stage coarse universal mill, the curved surface shape of the horizontal roll of the second-stage coarse universal mill, and the curved surface shape of both sides of the horizontal roll of the edging mill. An apparatus for manufacturing an H-section steel, wherein the apparatus is selected from any of the following intermediate curved surface shapes.