JP3473558B2 - Rolling method for H-section steel - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a hot rolling method for large H-section steel used in the field of civil engineering and construction.

[0002]

2. Description of the Related Art Large H-section steel is produced from continuously cast slabs by using a hole rolling mill (breakdown mill) and a universal rolling mill.

FIG. 1 is a diagram schematically showing a rolling line for producing H-section steel. (A) is an example in which an intermediate rolling mill group and a finishing rolling mill group are arranged separately from each other, and (b) is It is a figure which shows the example which has arrange | positioned the rough rolling mill, the edger rolling mill, and the finishing rolling mill, respectively.

A general rolling line for H-section steel is, as shown in FIG. 1 (a), a heating furnace H for heating continuously cast slabs,
Double roll type breakdown mill BD with hole type (hereinafter referred to as "BD mill"), followed by 4 rolls of universal rough rolling mill UR (hereinafter referred to as "UR mill"), 2 rolls Edger rolling machine E (hereinafter referred to as "E
"Mill") and a UR mill arranged in a reversible mill group M1
And the subsequent forming and rolling mill F and the four-roll universal finishing mill UF (hereinafter referred to as "UF mill")
And the finishing mill group MF in which are arranged in tandem.

Recently, in order to improve the manufacturing efficiency of large H-section steel, as a group of mills following the BD mill, as shown in FIG. 1 (b), U
A rolling line has been proposed which is composed of a mill group M2 in which an R mill, an E mill and a UF mill are arranged in close proximity to each other. Here, the “proximity arrangement” means an arrangement in which one rolled material is rolled without slipping through two rolling mills. That is, in the closely arranged mill group, one rolled material is rolled by two rolling mills at least temporarily.

FIG. 2 is a view showing a cross-sectional shape of a roll hole type of a rolling mill and a rolled material formed by the hole type.
(a) is a UR mill, (b) is an E mill, and (c) is a UF mill.

As shown in FIG. 2 (a), the roll of the UR mill has a horizontal roll (1,1) with a side portion (1 -1,1-2)
The vertical roll (2,2) has an inclination angle (α)
Is provided with an inclination angle (α) on the circumferential portion of the roll cross section so that the central portions of the circumferential portions (2-1, 2-2) become thicker. A hole formed by such a roll is called an X-shaped hole, and can reduce the web thickness and flange thickness of the rolled material efficiently. Further, even if the shape of the roll becomes small due to wear due to the inclination of the side surface of the horizontal roll, it can be reused by correcting this and adjusting the axial distance between the two rolls. Normally, this inclination angle (α) is 3 ° to 5 °
Is.

As shown in FIG. 2 (b), the roll (3, 3) of the E mill has a step (3) at which the side surface (3-1, 3-2) has a tilt angle (β) and the width of the flange is reduced. Parts (3-3, 3-4) are provided. This is to perform the reduction in the width direction of the flange while maintaining the X-shaped hole shape. Usually, this inclination angle (β) is
It is 3 ° to 5 °.

As shown in FIG. 2 (c), the rolls of the UF mill have side portions (4-side) on the horizontal rolls (4, 4) as in the UR mill.
1,4-2) has an inclination angle (γ), and the vertical rolls (5,5) have an inclination angle (γ) on the body (5-1,5-2). A hole formed by such a roll is called an H-shaped hole, and a rolled material can be lightly reduced in the final finishing rolling pass to finish it into a predetermined cross-sectional dimension.
Usually, this inclination angle (γ) is 0.3 ° to 0.5 °.

The H-section steel is usually produced by shaping a continuously cast slab heated in the line shown in FIG. 1 (a) into a rough shape material (beam blank) by multipass reversible rolling in a BD mill, After being sent to the reversible mill group M1 and subjected to intermediate rolling by a plurality of passes of reversible rolling, it is sent to the finishing mill group MF and finished into a predetermined shape by one-pass finish rolling.

FIG. 3 is a schematic view showing the cross-sectional shapes of the roll-hole type and the rolled material of the BD mill for forming a rough material. Figure 3
(A) shows a hole type formed by upper and lower double rolls, (b)
FIGS. 3 (e) to 3 (e) are diagrams showing a situation in which a cross-section of a rectangular slab is pressed down in the long side direction by these hole dies to form a crude material.

The slabs having a rectangular cross section (rolled materials Q1 to Q4) are
As shown in FIGS. 3 (b) to (e), after centering rolling with the hole die K1 of the BD mill (see FIG. 3 (b)), the flange widening rolling with the hole die K2 (FIG. 3 (c), After performing groove elimination rolling (see FIG. 3 (d)) with the hole die K3, shaping rolling is performed with the hole die K4 to form a rough material Q4 (see FIG. 3 (e)). .

The rough material Q4 is a reversible mill group M1 shown in FIG. 1 (a).
The two UR mills as shown in Fig. 2 (a) in the thickness direction of the flange and the web thickness direction, and the E mill as shown in Fig. 2 (b) in the width direction of the flange. The rolling is performed in multiple passes to form the intermediate rolled material Q5. The reversible mill group M1 includes a UR mill, an E mill, and an E mill as shown in FIG.
Although the UR mill is arranged in tandem, the UR mill and the E mill may be arranged in tandem.

The intermediate rolled material Q5 is sent to the finishing mill group MF, the flange width of the rolled material is set to a target value by the forming and rolling mill F, and then the UF mill is used to set a predetermined dimension as shown in FIG. 2 (c). H-section steel
Finished rolled to Q6.

In order to improve the production efficiency of H-section steel, the above-mentioned FIG.
As shown in (b), the method of using a rolling line composed of a mill group M2 in which a UR mill, an E mill, and a UF mill are closely arranged,
In each pass except the finishing pass, reciprocal rolling is performed using two units, a UR mill and an E mill, and in the finishing pass, finish rolling is performed using a UF mill. Japanese Examined Patent Publication No. 6-83845 discloses a so-called "X-H rolling method" in which reciprocal rolling is performed by a UR mill, an E mill and a UF mill arranged in close proximity, and the UF mill also reduces the web thickness and the flange thickness. Proposed.

[0016]

Conventionally, in the UF mill, in order to roll the final product, a slight inclination (γ = 0.3 ° to 0.5 °) is attached to the side surface of the horizontal roll (the surface in contact with the flange of the product). ing. For this reason, the UF mill is only used for the final finishing pass when rolling one strip. However, in the above X-H rolling method, a UF mill is used for all passes to reduce the web thickness and flange thickness. For this reason, the side surface of the horizontal roll is worn, and the amount of rolling in one rolling chance (period until roll change) is significantly reduced. Further, in the pass from the UF mill to the UR mill, the angle of the flange portion of the rolled material is widened from 0.3 ° to 5 °, and this is repeated, which may cause seizure flaws on the inner surface of the flange portion.

The objects of the present invention are UR mills, E mills and UF mills.
To provide an X-H rolling method using a rolling line in which mills are closely arranged, which does not reduce the rolling amount in one rolling opportunity and realizes high efficiency without causing a flaw in a rolled material. It is in.

[0018]

[Means for Solving the Problems] The present inventor has conducted research on a method for achieving high efficiency without reducing the rolling amount by an X-H rolling method and without causing a flaw in a rolled material.
The present invention was completed by finding out the following points. (1) UR mill, E mill and UF mill are placed in series and X-H
When rolling, if only the web thickness is reduced with a UF mill,
No bending occurs at the base of the web and the flange, (2) If you reduce the web thickness only with a UF mill, you can reduce the number of passes compared to reducing the web thickness with a BD mill, (3) Above In order to realize (1) and (2), the ratio (BFt / BWt) of the thickness of the flange portion (BFt) to the thickness of the web portion (BWt) is set to 0.8 to 1.2. Desirable.

The gist of the present invention based on these findings lies in the rolling method of H-section steel shown below.

Break-down rolling mill Universal rough rolling mill of four rolls from a beam blank shaped by BD (U
R) A method for rolling H-section steel using a group of mills (M2) in which a two-roll edger rolling mill (E) and a four-roll universal finishing mill (UF) are arranged close to each other. For all rolling passes in group (M2), the first half pass group that uses all rolling mills in each pass, the second half pass group that does not use finishing mill (UF) in each pass, and the finishing pass that uses all rolling mills A method for rolling H-section steel, characterized by being divided into three parts (see Fig. 1 (b)).

The cross-sectional shape of the beam blank is preferably formed such that the ratio (BFt / BWt) of the thickness of the flange portion (BFt) to the thickness of the web portion (BWt) is 0.8 to 1.2.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION 1. Regarding the rolling method in the mill group of the present invention: The rolling line used in the rolling method of the H-section steel of the present invention has a BD mill arranged downstream of the heating furnace H as shown in FIG. UR mill, E mill and UF downstream
A mill group M2 in which mills are installed close to each other is arranged and configured.

The characteristic feature of the rolling method for H-section steel of the present invention is that FIG.
All the number of rolling passes in the mill group M2 shown in (b) is divided into three passes, namely, a first pass, a second pass and a finishing pass.

FIGS. 4A and 4B are views showing the cross-sectional shapes of a roll hole die and a rolled material for explaining the H-section steel rolling method of the present invention. FIG. 4A is a UR mill, FIG. (c) is a UF mill.

The side angle of the horizontal roll (1,1) of the UR mill and the side angle of the roll (3,3) of the E mill are both 5 ° and U
The side angle of the horizontal rolls (4, 4) of the F mill is 0.3 °,
It is the same as the roll shape of the rolling line conventionally used.

In each pass of the first half of rolling, a UR mill, an E mill and a UF mill are used.

In the UR mill, as shown in FIG. 4 (a), the thickness direction of the web portion and the thickness direction of the flange portion of the rolled material are reduced in the same manner as in the conventional case (from the broken line to the solid line in the figure). Is reduced to).

In the E mill, the width direction of the flange portion of the rolled material is reduced as in the conventional case, but as shown in FIG. 4 (b),
You may perform the reduction of the width direction of the flange part of a rolled material, and the thickness direction of the web part.

In the UF mill, as shown in FIG. 4 (c), the vertical rolls (5, 5) are brought into contact with the tip of the outer surface of the flange of the rolled material, and the horizontal rolls (4, 4) are used to adjust the thickness of the web portion. Only rolling down is done. The cross-sectional shape of the rolled material in the UF mill is X
Shape, that is, the web can be rolled down in the thickness direction by the horizontal rolls (4, 4) with the flange having an inclination of 5 °. This means that the web thickness of the beam blank can be made larger than before, and the side surface (4-1) of the horizontal roll of the UF mill does not come into contact with the rolled material, so it does not cause wear. is there.

In each pass of the latter half of rolling, the UF mill is not used as in the conventional method, but the UR mill and the E mill are used to measure the thickness direction of the flange portion, the thickness direction of the web portion and the flange portion. Perform width reduction. In the finishing pass, the UR mill, E mill and UF mill are used for finish rolling as in the conventional method.

As described above, rolling in the intermediate mill of the present invention is
Since the UF mill in each pass of the first half only reduces the web thickness, when the rolled material is sent from the UF mill to the UR mill, bending deformation does not occur at the intersection of the flange and the web. As a result, the quality of the H-section steel can be improved and the productivity can be improved.

2. Regarding the cross-sectional shape of the rough material:
In the intermediate rolling of H-section steel, the reduction in the thickness direction of the web is performed by the UR mill and the UF mill in each pass of the first half. On the other hand, the reduction in the thickness direction of the flange is performed only by the UR mill.
Therefore, in the cross-sectional shape of the rough material sent from the BD mill, the thickness of the web portion and the thickness of the flange portion can be made smaller than the cross-section of the conventionally used rough material.

FIG. 6 is a conceptual view showing a cross section of a beam blank, (a) is a beam blank for carrying out the method of the present invention, and (b) is a beam blank used conventionally.

The cross section of the beam blank for carrying out the method of the present invention has a thickness (B) as shown in FIG. 6 (a).
The ratio (BFt / BWt) between the Ft) and the thickness of the web (BWt) is 0.8.
It is desirable that it is formed to ~ 1.2. Ratio (BFt / BW
When t) is less than 0.8, the web thickness becomes much larger than the flange thickness, and the effect of the method of the present invention that the web thickness is reduced more by the UF mill cannot be sufficiently exhibited. Further, if the ratio (BFt / BWt) exceeds 1.2, the web thickness becomes much smaller than the flange thickness, and the number of passes in the DB mill increases, so that the effect of the present invention cannot be exhibited.

Beam blanks for carrying out the method of the present invention can be manufactured from continuously cast slabs by a BD mill.

FIG. 5 is a schematic diagram showing a roll hole die and a rolled material cross-sectional shape of a BD mill for producing a beam blank used in the method of the present invention. (A) shows two rolls and a roll formed by the roll. And (b) to (f) are diagrams showing a hole shape and a rolled material cross-sectional shape from the centering rolling of the slab to the rough shape material.

The roll of the BD mill shown in FIG. 5 is provided with two insertion hole types (K2-1, K2-2) which are only one in the roll hole type of the conventional BD mill shown in FIG. There is. This is because if the flange thickness of the beam blank is reduced as shown in FIG. 6 (a), the filling property of the material into the hole die is deteriorated.
This is because it is necessary to make the flange width of the rolled material (Q3-1) before biting into the shaping hole die (K4-1) larger than before as shown in.

[0038]

EXAMPLES (Invention Example) BD mill, UR as shown in FIG. 1 (b)
Using the H-shaped steel rolling equipment in which the mill, E mill and UF mill are arranged in series, the side length B shown in Fig. 7 is 300 mm, the height (H) is 800 mm, and the web thickness (t ₁ ) is An H-section steel with a thickness of 19 mm and a flange thickness t ₂ of 32 mm was produced. This H-section steel is an H-section steel with a fixed external method and has the largest flange thickness.

The material was a continuously cast slab having a thickness of 250 mm and a width of 1400 mm, which was heated to 1280 ° C. and then subjected to rolling.

The BD mill has the hole type shown in FIG. 5, and according to the pass schedule shown in Table 1, the web thickness (BWt) shown in FIG. 6 (a) is 100 mm, the web height (BWh) is 1050 mm, and the flange thickness is A beam blank with a (BFt) of 120 mm and a flange width (BFb) of 380 mm was formed. That is, (BFt / BWt) is 1.2
Is.

[0041]

[Table 1]

The number of rolling passes in the BD mill for obtaining the above beam blank from the above continuously cast slab was 15 as shown in Table 1.

The obtained beam blanks are shown in Table 2 using a group of mills (M2, see FIG. 1 (b)) in which a UR mill, an E mill and a UF mill having the hole type shown in FIG. The above H-section steel was rolled according to the pass schedule shown.

[0044]

[Table 2]

As shown in Table 2, from the 1st pass to the 8th pass in the first half, the reduction in the web thickness direction and the flange thickness direction in the UR mill, the reduction in the flange width direction in the E mill, and the UF
The mill was rolled through the web in the thickness direction. From the 9th pass to the 14th pass in the latter half, the UF mill and the UF mill were not used.
The E mill performed the same rolling as the conventional one, and the finishing pass (pass number 15) performed continuous rolling using the UR mill, E mill and UF mill. The number of passes at this time was 15 passes in the BD mill as is clear from Table 1, 14 passes in the intermediate rolling in the mill group (M2) and 1 pass in finish rolling as is clear from Table 2. It was possible to produce H-section steel from continuously cast slabs with a total of 30 passes of rolling.

(Comparative Example 1) As a comparative example, a method of using the same H-shaped steel rolling equipment as in the above-mentioned invention example, using the same continuous casting slab as in the above-mentioned invention example, and using the UF mill only for the finishing rolling pass (conventional method) Method) to produce an H-section steel having the same shape as the above-mentioned invention example.

The BD mill used is a conventional roll having four holes as shown in FIG. Rolling was performed according to the pass schedule shown in Table 3 to obtain a beam blank as shown in FIG. 6 (b). The beam blank has a web thickness (BWt) of 70 mm and a web height (BWh) of 1050.
mm, the flange thickness (BFt) was 140 mm, and the flange side length (BFb) was 350 mm. The ratio (BFt / BWt) of the flange thickness (BFt) to the web thickness (BWt) of the beam blank is 2.0, which is larger than the range defined by the invention.

[0048]

[Table 3]

The above beam blank has an intermediate mill group (M
The intermediate rolling carried to 2) was carried out according to the pass schedule shown in Table 4 without using the UF mill.

[0050]

[Table 4]

For the evaluation of rolling efficiency, the number of rolling passes required to reduce the thickness of the web portion of the rolled material from 100 mm to 70 mm was compared with the above-mentioned invention examples.

In Comparative Example 1, as is clear from Table 3,
The number of rolling passes required to reduce the thickness of the web portion of the rolled material from 100 mm to 70 mm was required from the 15th pass to the 21st pass in the BD mill. This is done by rolling (K4) in the hole form to reduce the web thickness (pass numbers 17, 19 in Table 3 and
21) 3 passes, and 3 passes of break-in rolling (same pass numbers 16, 18 and 20) in the hole type (K3) to remove the bite part that has occurred in the rolled material in these rolling passes, in total This is to do 6 passes. On the other hand, in the above-described method of the present invention, as is clear from Table 2, reduction of the thickness of the web portion from 100 mm to 70 mm is performed by the intermediate mill group, and from the first pass to the third pass. Rolling (UF mill gives a web thickness of 70 mm) is acceptable. As shown in FIG. 4 (c), when the horizontal roll of the UF mill reduces the web thickness of the rolled material, if the vertical roll contacts a part of the flange of the rolled material, Because it does not occur, break-in rolling is not required unlike rolling in a BD mill.

In the conventional method, the number of rolling passes for producing the H-section steel from the cast slab is 21 passes in the BD mill as shown in Table 3, and in the mill group (M2) of the UR mill and the E mill. 18 passes for intermediate rolling as shown in Table 4, and 1 pass for finish rolling using all mills (pass number 1
9), for a total of 40 passes.

(Comparative Example 2) As Comparative Example 2, the same H-section steel rolling equipment and the same continuous casting slab as in Invention Example 1 were used.
A conventional beam blank, that is, a beam blank (Q4) shown in FIG. 6 (b) is formed, and the method of the present invention is applied to a mill group (M2).
Then, a test for producing an H-section steel having the same shape as that of Inventive Example 1 was conducted. The results are shown in Table 5.

[0055]

[Table 5]

As is clear from Table 5, in the intermediate rolling in the mill group (M2), the UR mill, E mill and
Rolling was performed using all mills of the UF mill. this is,
The shape of the beam blank is such that the thickness of the web (70 mm) is smaller than the thickness of the flange (140 mm) (BFt / BWt is 140 mm).
/ 70 = 2.0), which means that the number of passes for rolling down the web in the UF mill in the thickness direction is reduced. That is, in this example, since the beam blank has an inappropriate cross-sectional shape, the number of rolling passes required for producing the H-shaped steel from the slab is the same as that of Comparative Example 1 in the BD mill, 21 passes, and the mill group (M2 ) In Table 5
As can be seen from the above, 16 passes of intermediate rolling, and 1 pass of finish rolling using all mills, that is, 38 passes in total.

(Comparative Example 3) As Comparative Example 3, the same H-section steel rolling equipment and the same continuous casting slab as in Invention Example 1 were used.
A conventional beam blank, that is, a beam blank (Q4) shown in FIG. 6 (b) is formed, and a mill group (M2) is used to form a beam blank (Q4) having the same shape as the example of the present invention by the method described in Japanese Patent Publication No. 6-83845. A test was conducted to produce H-section steel. The results are shown in Table 6.

[0058]

[Table 6]

As is clear from Table 6, in rolling in the mill group (M2), the UR mill, the E mill and the UF mill were used from the first pass to the eighth pass, and the UR mill and the UF mill used the web thickness direction. And, rolling was performed to perform reduction in the flange thickness direction.
Then, in the 9th and 10th passes, the UR mill and E mill are used to perform reduction in the web thickness direction, the flange thickness direction, and the flange width direction, and in the final 11th pass, the UR mill is again used.
Finish rolling was performed using an E mill and a UF mill.

In this case, the number of rolling passes is 21 in the BD mill, 10 in the intermediate rolling in the mill group (M2), and in the finish rolling.
It was one pass, for a total of 32 passes. However, in 1 to 8 passes, the UF mill performs reduction in the web thickness direction and the flange thickness direction, so there were some cases where minute rolling flaws were observed at the joint between the flange of H-section steel and the web. .

As is clear from the above examples, the total number of rolling passes of the present invention example is 30, the comparative example 1 has 40 passes, the comparative example 2 has 38 passes, and the comparative example 3 has 32 passes. It can be seen that the method of the present invention is excellent also in.

[0062]

INDUSTRIAL APPLICABILITY In the rolling method for H-section steel of the present invention, a mill group in which a UR mill, an E mill and a UF mill are closely arranged is used, and all rolling passes are used in all rolling passes in the mill group. Rolling is performed in three divisions into a first-half pass group, a second-half pass group that does not use a finishing rolling mill in each pass, and a finishing pass that uses all rolling mills. As a result, the number of rolling passes can be reduced, rolling flaws do not occur at the joint between the flange of the H-section steel and the web, and an H-section steel of excellent quality can be manufactured. Further, if the sectional shape of the beam blank is such that the ratio (BFt / BWt) of the thickness of the flange portion (BFt) to the thickness of the web portion (BWt) is 0.8 to 1.2, the above rolling method is preferably carried out. be able to.

[Brief description of drawings]

FIG. 1 is a view schematically showing a rolling line for H-section steel,
(a) is a rolling line in which an intermediate rolling mill group and a finishing rolling mill group are arranged apart from each other, and (b) is a diagram showing a rolling line in which a rough rolling mill, an edger rolling mill, and a finishing rolling mill are arranged in proximity to each other. .

FIG. 2 is a view showing a cross-sectional shape of a roll hole type of a rolling mill and a rolled material formed by the hole type, where (a) is a UR mill and (b) is
Is E mill and (c) is UF mill.

FIG. 3 is a diagram showing a cross-sectional shape of a roll hole die and a rolled material of a BD mill for forming a rough material. FIG. 3 (a) shows a hole die formed by upper and lower two-stage rolls, and (b) to (e) show a situation in which a rectangular slab is pressed down in the long side direction to form a rough material. It is a figure.

FIG. 4 is a view showing a cross-sectional shape of a roll hole die and a rolled material for explaining the H-section steel rolling method of the present invention, and (a) is a UR
Mill, (b) E mill and (c) UF mill.

FIG. 5 is a schematic view showing a roll hole shape and a rolled material cross-sectional shape of a BD mill used in the method of the present invention, (a) showing two rolls and a hole shape formed thereby, (b) )-(F) are diagrams showing the cross-sectional shape and the hole shape from the centering rolling of the slab to the rough shaped material.

FIG. 6 is a view showing a sectional shape of a beam blank,
(a) is the beam blank used in the example of the present invention, and (b) is the beam blank used in the comparative example.

FIG. 7 is a view showing a cross-sectional shape and dimension symbols of H-section steel.

[Explanation of symbols]

H. Heating furnace BD. Double roll type breakdown mill UR. 4-roll universal rough rolling machine E. 2-roll edger rolling machine UF. 4-roll universal finishing mill F. Forming and rolling mills K1 to K4, K2-1, K2-2, K4-1. Hole type 1. UR mill horizontal roll 2. UR mill vertical roll 3. E-mill horizontal roll 4. UF Mill Horizontal Roll 5. UF Mill Vertical Roll

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B21B 1/08

Claims (2)

(57) [Claims] 1. A method for rolling an H-section steel from a beam blank using a group of mills in which a four-roll universal rough rolling mill, a two-roll edger rolling mill, and a four-roll universal finish rolling mill are arranged close to each other. All the rolling passes in the mill group are divided into a first half pass group that uses all rolling mills in each pass, a second half pass group that does not use a finishing mill in each pass, and a finishing pass that uses all rolling mills. A method for rolling H-section steel, characterized by being divided into three parts. 2. The cross-sectional shape of the beam blank is such that the ratio (BFt / BWt) of the thickness (BFt) of the flange portion to the thickness (BWt) of the web portion from the surface of the flange is 0.8 to 1.2. The method for rolling H-section steel according to claim 1, wherein