JPH07265903A - Production of thin web h-beam - Google Patents

Abstract

PURPOSE:To provide the production method of a thin web H-beam capable of eliminating web wave prior to a finishing universal mill. CONSTITUTION:In producing an H-beam having a very thin web relative to flange by hot rolling through a rough universal mills 2, 4 and a finishing universal mill 5, a variable roll width/leg length edger mill 6 is placed at the upstream side of the finishing universal mill 5, by executing finish rolling after a web inner width of the H-beam is expanded by the edger mill 6, the H-beam having no defect of web wave is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a web thickness of, for example, 6
The present invention relates to a method for manufacturing a thin web H-section steel having a thickness of mm or less.

[0002]

2. Description of the Related Art Conventionally, a thin web H-section steel having a web thickness of, for example, 6 mm or less is liable to cause a poor balance between the reduction ratio of the web and the flange during rolling in a rough universal mill or a finish universal mill, resulting in a rolled web. There was a high probability that shape defects such as waves would occur.

When the ratio of flange thickness / web thickness increases, a cooling web wave is generated due to a difference in thermal stress after finish rolling. Therefore, a water cooling device is provided before and after the rough universal mill or between the rough universal mill and the finish universal mill. It is provided and water cooling is performed. In this case, when the web thickness becomes thin, the critical buckling stress is reduced, and the rapid cooling of the flange portion may cause a web wave due to compressive stress in the longitudinal direction of the web. Then, once a web wave is generated, it is difficult to perform shaping by rolling with a finish universal mill, which leads to a problem of product failure such as disqualification.

[0004]

According to the above-mentioned conventional method, in the rolling of thin-walled web H-section steel, a web wave is likely to be generated due to a rolling web wave or a flange quenching due to flange water cooling. There was no way to shape the wave, which caused product defects such as disqualification, which was a factor in the reduction of the acceptance rate.

The present invention has been made to solve the above-mentioned problems of the prior art, and is a thin-walled web H capable of eliminating web waves generated before a finishing universal mill.
An object is to provide a method for manufacturing a shaped steel.

[0006]

SUMMARY OF THE INVENTION The present invention provides a method for hot rolling an H-shaped steel product having an extremely thin web for a flange through a rough universal mill and a finish universal mill, and the upstream of the finish universal mill. A method for producing a thin web H-section steel is characterized in that a roll width variable / leg length variable edger mill is arranged on the side, and the web inner width of the H-section steel is enlarged by the edger mill and then finish rolling is performed.

[0007]

[Operation] According to a study by the present inventor, it was found that the above-mentioned problematic web wave is generated due to the difference in rolling length between the web and the flange. If the rolling length of the web is reduced by enlarging, the defective shape can be eliminated before the finishing universal mill.

That is, according to the present invention, an edger capable of varying the roll width and leg length is arranged on the upstream side of the finishing universal mill, and the inner width of the web is enlarged by the roll width / leg length variable edger mill. Web waves can be eliminated before being rolled in a universal mill. Since the roll width / leg length variable edger mill always enlarges the inner width of the web to a certain extent, the width W _R of the horizontal roll of the rough universal mill is larger than the width W _F of the horizontal roll of the finishing universal mill by a predetermined inner width expansion amount. It is necessary to reduce it by ΔW.

ΔW = W _F −W _R > a (1) Here, a is a positive numerical value, and is set to about 1% or more of the horizontal roll width W _F of the finishing universal mill. desirable. As described above, in the present invention, the inner width of the web is expanded by ΔW by using the roll width / leg length variable edger mill.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a mill arrangement to which the method of the present invention is applied. 1 is a breakdown mill, 2 is a first rough universal mill, 3 is an edger mill, and 4 is a second rough universal mill. 5 is a finishing universal mill,
Reference numeral 6 denotes a roll width / leg length variable edger mill of the present invention which is arranged on the upstream side of the finishing universal mill 5. 7 is a flange water cooling device, and 8 is a water cooling device between the roughing and finishing mills.

As shown in FIG. 2, the roll width / leg length variable edger mill 6 of the present invention is composed of a pair of upper and lower variable width rolls 9 and 9 for pressing down both ends of the web 11 of the H-shaped steel 10, Each side surface is tapered with an angle θ _E. The taper angle θ _E is set to be substantially equal to or less than the roll taper angle θ _{R of} the first and second coarse universal mills 2 and 4, and prevents the flange 12 part from being caught at the time of expansion. That is, θ _E ≦ θ _R (2) Further, the limit of biting of the flange 12 by the variable width rolls 9 and 9 should be equal to or less than the distance L between the tips of the flange 12 of the H-section steel 10. On the actual machine, the limit of ΔW is expressed by the following equation (3).

ΔW ≦ (1/2) · (L−W _F ) ... (3) Here, when the leg length of the H-section steel 10 is h, the distance L between the tips of the flange 12 is given by (4) ) Becomes an expression. L = W _F + 2h · tan θ _R (4) Therefore, the expansion amount ΔW in the edger mill 6 can be calculated by the following equation (5) using the equations (3) and (1) in which the equation (4) is substituted. It becomes the range of the formula.

A <ΔW <h · tan θ _R (5) For example, web height: 550 mm × flange height: 200 mm ×
When the web width of the H-section steel 10 having a web thickness of 6 mm and a flange thickness of 16 mm is increased to 1% or more of the horizontal roll width W _F of the finishing universal mill with the numerical value a of 5.2 mm or more, If the roll taper angle θ _R of the 2 coarse universal mills 2 and 4 is 5 °, the leg length h is 97 mm, so the expansion amount ΔW obtained by the equation (5) can be determined within the following range.

[0014] 5.2 mm <ΔW <8.5 mm It is noted that the horizontal roll width W _R of the first and second coarse universal mill 2,4 and (W _F -a), roll width W _E of the roll width and leg length variable Ejjamiru 6 Is to match the roll width W _F of the finishing universal mill 5. In this way, the H-shaped steel can be controlled by the roll width / leg length variable edger mill 6.
By expanding 10, the web wave generated in front of the finishing universal mill 5 can be eliminated, and about 80% of the generated web wave can be eliminated in the actual machine.

[0015]

As described above, according to the present invention,
The roll width / leg length variable edger mill expands the inner width of the web to eliminate the web wave before it is rolled by the finishing universal mill, which can contribute to the improvement of the product pass rate. Is large.

[Brief description of drawings]

FIG. 1 is a layout view showing a mill row to which the present invention is applied.

FIG. 2 is a front view showing a configuration of a roll width / leg length variable edger mill used in the present invention.

[Explanation of symbols]

 2 1st coarse universal mill 4 2nd coarse universal mill 5 Finishing universal mill 6 Roll width and leg length variable edger mill 9 Variable width roll 10 H-section steel 11 Web 12 Flange

Claims (1)

[Claims] 1. A method for producing an H-section steel product having a web extremely thin against a flange by hot rolling through a rough universal mill and a finishing universal mill, wherein a roll width / leg length variable edger mill is provided upstream of the finishing universal mill. Is arranged, the inner width of the web of the H-section steel is enlarged by the edger mill, and then finish rolling is performed, and a method for producing a thin-walled web H-section steel.