JP3503449B2 - H-beam rolling method - Google Patents

Description

Detailed Description of the Invention

[Definition of Terms] In the present invention, "first material" and "next material" refer to a single or a plurality of rolled materials, respectively, which have a rolling order in a rolling order. In addition, "increase / decrease ... in large / small ..." means "increase / decrease in large ...
It means "increasing, decreasing ... to small ...".

Thickness reduction of flange = (thickness of flange before rolling−thickness of flange after rolling) / flange thickness before rolling web thickness reduction of web = (thickness of web before rolling−thickness of web after rolling) ) / Web thickness before rolling

[0003]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rolling H-section steel, and more particularly to a method for rolling H-section steel that improves the accuracy of flange width in the length direction of H-section steel.

[0004]

2. Description of the Related Art A rolling mill for H-section steel is composed of a combination of a breakdown rolling mill 5, a rough universal rolling mill 1, an edging rolling mill 2 and a finishing universal rolling mill 4 as shown in FIG. , Bloom, beam blank, or other material steel slab is passed through these rolling mills one after another and rolled to obtain a predetermined cross-sectional dimension H
Shaped steel is produced.

The breakdown rolling mill is a double rolling mill in which a plurality of perforated rolls having a plurality of perforated or closed perforations are arranged along the roll cylinder. It is rolled and formed into H shape (breakdown rolling). As shown in FIG. 3 (a), the rough universal rolling mill includes a rough horizontal roll 7 and a rough vertical roll 8, and the web thickness of the material (rolled material) 6 subjected to breakdown rolling is the rough horizontal roll 7.
And the flange thickness is rough horizontal roll 7 and rough vertical roll 8
Each is rolled down (coarse universal rolling).

The flange width is reduced (edging rolling) by the edging roll 9 of the edging rolling machine as shown in FIG. 3 (b). The rolled material 6 is rolled by rough universal rolling and edging rolling until it has a predetermined cross-sectional dimension, which is called rough rolling. Up to this stage, the flange is tilted at an obtuse angle to the web.

Next, the rolled material 6 after the rough rolling is shown in FIG.
As shown in (c), by the finishing horizontal roll 10 and the finishing vertical roll 11 of the finishing universal rolling machine, the angle of the flange is raised (the flange is raised at right angles to the web).
Also, the flange thickness and web thickness are reduced (finish universal rolling) to finish the final product dimensions. In such rough rolling and finish universal rolling, it is usual to set a target thickness and a reference roll gap for each pass, and set the roll position of each rolling mill to match them.

By the way, in the rough universal rolling and the finish universal rolling, the flange width end face is not restricted by the roll as shown in FIGS. 3 (a) and 3 (c). Therefore, this portion is freely deformed, and a phenomenon called so-called flange width expansion occurs. This flange width expansion is affected by the rolling conditions of the material, temperature distribution, pre-rolling shape, etc., so the amount of flange width expansion varies depending on the length position of the rolled material, and the flange width distribution in the product length direction becomes uneven. Not a few things. At this time, for the length part where the flange width is insufficient to the dimensional tolerance, it is forced to cut off and the yield deteriorates, and for the length part that exceeds the dimensional tolerance,
There was a problem that it takes time and care for maintenance.

As a means for solving this problem, the edging roll opening is continuously increased or decreased with respect to both end portions of the rolled material on the basis of the set value for the steady portion, and the edging rolling is carried out. A method for obtaining a uniform flange width in the longitudinal direction later is disclosed in Japanese Patent Laid-Open No. 8-
It is disclosed in Japanese Patent No. 252615.

[0010]

However, according to this method, if the opening degree of the edging roll is made too small, the web is excessively reduced and the web thickness becomes non-uniform in the lengthwise direction, which becomes a restriction and the flange There is a problem that the adjustable range of the width is narrowly lost. An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a rolling method of H-section steel capable of stably producing H-section steel with good flange width accuracy in the product length direction.

[0011]

As a result of intensive studies, the inventors of the present invention have found that the thickness reduction amount of the flange and the web in the rough universal rolling is equal to the flange width distribution in the longitudinal direction after the finish universal rolling or the rough universal rolling. It was found that there is a strong correlation, and the knowledge that the above object can be achieved by effectively utilizing such a correlation was obtained, and the present invention was made based on this knowledge.

The present invention relates to an H-section steel rolling method for sequentially subjecting a raw steel slab to breakdown rolling, rough universal rolling, rough rolling for performing edging rolling, and finish universal rolling. A method for rolling H-section steel, characterized in that either one or both of a flange thickness reduction rate and a web thickness reduction rate are changed in the longitudinal direction.

Further, the present invention provides a method for rolling an H-section steel in which a material billet is sequentially subjected to breakdown rolling, rough universal rolling, rough rolling for performing edging rolling, and finish universal rolling. Alternatively, the flange width distribution in the length direction after rough universal rolling is determined, and either or both of the flange thickness reduction rate of rough universal rolling and the web thickness reduction rate of the next material based on the flange width distribution during rolling. This is a rolling method for H-section steel, which is characterized in that it is changed in the longitudinal direction.

The above-mentioned change is caused by the thickness reduction rate of the flange in the first half pass of the rough universal rolling in the rolled portion of the next material corresponding to the large / small flange width after finishing universal rolling or rough universal rolling of the leading material. It is preferable to increase / decrease the difference between the thickness reduction ratio of the web and the thickness reduction ratio of the web.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, a raw steel billet is
In the rolling method of H-section steel in which breakdown rolling, rough universal rolling, rough rolling for edging rolling, and finish universal rolling are sequentially performed, during rough universal rolling,
Since either or both of the flange thickness reduction rate and the web thickness reduction rate are changed in the longitudinal direction of the material to be rolled, the flange width in the length direction can be adjusted, and
Obtain the flange width distribution in the length direction after finishing universal rolling or rough universal rolling of the leading material, and based on the flange width distribution, either the flange thickness reduction rate of the rough universal rolling to the next material or the web thickness reduction rate Alternatively, both of them are changed in the longitudinal direction during rolling, so that the flange width variation range in the length direction in the rough universal rolling of the next material can be made smaller than that of the preceding material, and eventually the product length. The flange width accuracy in the depth direction can be improved.

FIG. 1 is a schematic view showing an example of rolling equipment suitable for carrying out the present invention. In FIG. 1, 3 is a dimension measuring device, and the same or corresponding parts as in FIG. The raw steel billet is rolled to a predetermined size by the breakdown rolling mill 5, then rough rolling is performed by alternately repeating the rough universal rolling mill 1 and the edging rolling mill 2 for a plurality of passes, and finally the finish universal rolling mill 4 is rolled. Finished to the final dimensions of the product. In addition,
Rough rolling may be performed in a single pass using a plurality of rough universal rolling mills and an edging rolling mill. The dimension measuring device 3 is installed on the exit side of the finish universal rolling mill 4, and
The flange width distribution in the length direction after finish universal rolling can be measured. In addition, instead of installing a dimension measuring device,
You may take a sample from the unsteady part and the steady part of a product, and measure the dimension manually.

Further, the flange width distribution in the length direction after the rough universal rolling may be measured by the dimension measuring device 3 on the delivery side of the rough universal rolling mill, or may be obtained as follows. For example, the relationship between the flange width difference ΔB between the unsteady part and the steady part after the rough universal rolling (before the edging rolling) and the edging rolling load difference ΔE during the edging rolling is represented by the formula (1).

ΔB = α × ΔE (1) α in the formula (1) is a constant determined by the rigidity of the edging rolling mill and the flange thickness of the material, and can be determined in advance by experiments or theoretical analysis. Therefore, if ΔE is obtained in the final pass of rough rolling and ΔB is calculated from the equation (1), the calculated value represents the flange width distribution in the length direction after rough universal rolling.

Next, based on the method of adjusting the flange width in the longitudinal direction of the rolled material and the measurement result of the flange width distribution in the longitudinal direction after finishing universal rolling or rough universal rolling of the preceding material, A method of changing either or both of the flange thickness reduction rate and the web thickness reduction rate of rough universal rolling in the longitudinal direction will be described.

The inventors conducted experimental rolling and actual machine performance survey on the flange width expansion during rough universal rolling,
The following findings were obtained. FIG. 4 is a graph schematically showing the relationship between the flange thickness and the web thickness for each rough universal rolling pass. The thickness dimension before rough universal rolling is indicated by Δ, the thickness dimension after each pass of rough universal rolling is indicated by ◯, and the thickness dimension after the final pass of rough rolling is indicated by ●. The thickness before rough universal rolling is determined by the shape of the roll caliber (open hole type or closed hole type) of the breakdown rolling mill, and there is little room for change. The thickness dimension after the final pass of rough rolling is also determined by the product target dimension, etc., and there is little room for change. However,
There are innumerable routes from △ to ●.

For example, the pattern a in FIG. 4 is a path in which the web thickness decreases in the rough universal rolling while maintaining a substantially linear relationship with the flange thickness, and the pattern b is a pattern in which the flange thickness reduction ratio is greatly increased in the first half pass in the latter half pass. The path is small, the web thickness reduction ratio is small in the first half pass and large in the second half pass, that is, the path in which the difference between the flange thickness reduction ratio and the web thickness reduction ratio is large in the first half pass and small in the second half pass, pattern c is the opposite. The difference in the thickness reduction ratio with respect to the pattern a corresponds to a route in which the first half pass is small and the second half pass is large, and any route can be selected.

FIG. 5 shows the difference between the flange thickness reduction rate and the web thickness reduction rate (flange thickness reduction rate-web thickness reduction rate) in one pass of (a) first half pass and (b) second half pass of rough universal rolling. Is a graph schematically showing the relationship between the () and the flange width expansion amount. In addition, FIG.
The scale of (b) is the same. As shown in the figure, the flange width spread in the rough universal rolling is almost proportional to the difference in the thickness reduction ratio between the flange and the web, but the influence is large at the steady portion and small at the front and rear end portions. Further, the difference in flange width expansion between the steady portion and the front and rear end portions is large in the first half pass of rough rolling and small in the second half pass.

The inventors, paying attention to this point, use the rolling equipment shown in FIG. 1 to obtain a web height of 900 mm, a flange width of 300 mm, a web thickness of 16 mm, and a flange thickness of 28 mm by the nominal dimensions.
A rolling experiment was performed on the shaped steel while changing the rolling pattern at each part in the longitudinal direction, and the flange width distribution in the longitudinal direction at each stage of rolling was investigated. The rolling pattern of the rough universal rolling is, as shown in Table 1, the thickness reduction rate pattern a1 selected as a reference and the web thickness reduction rate (r _Wi : i is a pass number) are matched with the pattern a1 to reduce the flange thickness reduction rate of the first half pass. (R
_Fi ) is larger than the pattern a1 to increase the difference (r _Fi −r _Wi ) in the thickness reduction ratio between the flange and the web, and the patterns b1 and r _Wi are matched to the pattern a1 so that the r _Fi of the first half pass is smaller than the pattern a1. Then, the three patterns of the pattern c1 in which r _Fi -r _Wi were reduced were formed and rolled under the following three conditions.

Condition 1: The leading end is pattern a1, the stationary part is pattern a1, and the trailing end is pattern a1 Condition 2: The leading end is pattern b1 and the stationary part is pattern a
1, the rear end part is the pattern b1 Condition 3: The front end part is the pattern c1, and the stationary part is the pattern a
1, pattern c1 at the rear end

[0025]

[Table 1]

FIG. 6 is a graph showing the variation of the flange width in the length direction of the rolled material at (a) the stage before rough rolling and (b) the stage after finish universal rolling. In the stage before rough rolling, the flange width in the longitudinal direction is almost constant, but in the stage after finish universal rolling, the flange width is larger than the nominal value in the vicinity of the tip under Condition 1 and almost the nominal value in the vicinity of the steady part. Although it becomes larger than the nominal value in the vicinity of the rear end portion, in Condition 2, almost any portion in the longitudinal direction becomes the nominal value, and in Condition 3, the width of the front and rear end portions becomes larger than that of Condition 1.

That is, by setting the optimum rolling pattern for each portion, it is possible to reduce the fluctuation of the flange width in the longitudinal direction.

[0028]

[Example] Using the rough rolling equipment shown in FIG. 1 (hydraulic rolling of the rough universal rolling mill), the web height is designated by the nominal dimension.
H-section steel with a thickness of 762 mm, a flange width of 267 mm, a web thickness of 13.2 mm and a flange thickness of 17 mm was rolled. Coarse universal rolling was performed in 15 passes. First, three rollings were performed according to the normal schedule shown in Table 2 (conventional rolled material; conventional example), and the flange width in the longitudinal direction was measured by a dimension measuring device.
For the shaped steel, the flange width at the front and rear ends was 2.5 mm smaller than the flange width at the steady part on average.

[0029]

[Table 2]

Next, based on this information, the target web thickness of each pass of the rough universal rolling and the target flange thickness of the steady part are unchanged without change in order to make the flange widths of the front and rear end parts and the steady part uniform. Then, only the target flange thickness at the front and rear ends was changed as shown in Table 3 and rolling was performed (rolled material according to the present invention; Example).

[0031]

[Table 3]

That is, in the embodiment, the leading and trailing end portions are made smaller than the thickness reduction ratio of the flange of the front material (conventional rolled material) in the first half pass of rough rolling (the second to fourth passes), and in the fifth to sixth passes. After that, the thickness reduction rate was changed to the same value after that. The rolling conditions of the edger at this time were the same as the conventional conditions. FIG. 7 shows the actual results of the flange width from the tip portion to the steady portion of the example and the conventional example. The same tendency is observed at the rear end. In the figure, A (example) is the actual flange width of the rolled material according to the present invention, and B (conventional example) is the average value of the flange widths of three conventional rolled materials for comparison. From the figure, in the conventional example, the difference in flange width between the tip part and the steady part is large at about 2.5 mm, but in the example, this difference is 40% of the conventional example.
It decreased to about 1.0 mm below, and a uniform flange width was obtained from the tip to the steady part.

In the above embodiment, a method of changing the target thickness in rough rolling and correcting the thickness reduction pattern of the flange and the web with respect to the subsequent material is described with reference to the first three rolling records. However, it is obvious that the same effect can be obtained by actually measuring the flange width in the longitudinal direction for each one and sequentially correcting the thickness reduction pattern of the flange and the web for each one. In addition, even if either of the flange width of the front end or the rear end cannot be measured,
Since the tendency of the flange width deviation at the leading edge and the trailing edge relative to the steady part is usually the same, the reduction amount of each pass of the rough rolling is changed according to the difference between the measured flange width and the flange width of the steady part. The same effect can be expected when the thickness reduction pattern of the flange, the web is modified.

In the embodiment, when the flange widths at the front end and the rear end are smaller than the steady portion, only the thickness reduction rate of the flange at the front end and the rear end is changed with respect to the set value of the leading material. , An example of changing the difference between the flange thickness reduction rate and the web thickness reduction rate was shown, but only the web thickness reduction rate at the front end portion and the rear end portion is changed with respect to the set value of the leading material, or Both the flange thickness reduction rate and the web thickness reduction rate may be changed with respect to the set value of the leading material to change the difference between the flange thickness reduction rate and the web thickness reduction rate. Further, when the flange widths of the leading end portion and the trailing end portion are larger than the steady portion, rolling may be performed under conditions opposite to the above conditions.

[0035]

As described above, according to the present invention, the flange width in the product length direction can be adjusted, and the H-section steel having good flange width accuracy can be stably manufactured.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of rolling equipment suitable for implementing the present invention.

FIG. 2 is a schematic diagram of a normal H-section steel rolling facility.

FIG. 3A is an explanatory diagram of rough universal rolling, FIG. 3B is an edging rolling, and FIG.

FIG. 4 is a graph schematically showing the relationship between the flange thickness and the web thickness for each rough universal rolling pass.

FIG. 5 (a) first half pass of rough universal rolling, (b)
It is a graph which shows typically the relationship between the difference of the flange thickness reduction rate and web thickness reduction rate in one pass of the latter half pass, and the flange width expansion amount.

FIG. 6 is a graph showing variations in flange width in the length direction of the rolled material in (a) the stage before rough rolling and (b) the stage after rough universal rolling.

FIG. 7 is a graph showing the actual results of the flange width from the tip portion to the steady portion of the example and the conventional example.

[Explanation of symbols]

1 Coarse universal rolling mill 2 Edging rolling mill 3 Dimension measuring device 4 Finishing universal rolling mill 5 Breakdown rolling mill 6 Material (rolled material) 7 coarse horizontal roll 8 coarse vertical roll 9 Edging roll 10 Finishing horizontal roll 11 Finishing vertical roll

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tomoya Komaki 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Works Ltd. Technical Research Institute (72) Inventor Hiroyasu Shigemori 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama ( No address) Kawasaki Steel Co., Ltd. Inside Mizushima Works (56) References JP-A-9-19701 (JP, A) JP-A-8-252615 (JP, A) JP-A-11-151512 (JP, A) Kai 59-16611 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B21B 37/00-37/78 B21B 1/00-1/46

Claims (3)

(57) [Claims] 1. A method for rolling an H-section steel in which a raw steel billet is sequentially subjected to breakdown rolling, rough universal rolling, rough rolling and edging rolling, and finish universal rolling. A method for rolling H-section steel, characterized in that either one or both of the flange thickness reduction rate and the web thickness reduction rate is changed. 2. A method for rolling an H-section steel in which a raw steel billet is sequentially subjected to breakdown rolling, rough universal rolling, rough rolling for performing edging rolling, and finish universal rolling in a rolling method for finishing steel after finish universal rolling or rough universal rolling of a leading material. The flange width distribution in the subsequent length direction is obtained, and either or both of the flange thickness reduction rate and the web thickness reduction rate of rough universal rolling for the next material are changed in the longitudinal direction during rolling based on the flange width distribution. A method for rolling an H-section steel, which comprises: 3. The change is such that the flange width after finishing universal rolling or rough universal rolling of the leading material is large /
The difference between the thickness reduction rate of the flange and the web thickness reduction rate in the first half pass of the rough universal rolling is increased / decreased with respect to the set value of the first material on the rolled part of the next material corresponding to the small area. The method of claim 2.