JP4193532B2 - Rolling method for bar steel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of hot rolling a rod-shaped steel material from a substantially circular cross-sectional shape to a substantially rectangular cross-sectional shape.
[0002]
[Prior art]
Conventionally, as a method of rolling a rod-shaped steel material from a substantially circular cross-sectional shape to a substantially rectangular cross-sectional shape, a method of hot rolling a bar-shaped steel material from a substantially circular cross-sectional shape to a substantially rectangular cross-sectional shape using a four-roll rolling mill (See Patent Document 1). This method is different from the method disclosed in Patent Document 2 in that the cross-sectional shape after rolling of the rod-shaped steel material is not limited by the shape of the caliber of the roll used for rolling. It can be rolled into
[0003]
[Patent Document 1]
JP 2000-233202 A [Patent Document 2]
Japanese Patent Laid-Open No. 55-165206
[Problems to be solved by the invention]
However, when a steel bar having a rectangular cross-sectional shape is rolled by the above-described method, the diagonal dimension in the cross-sectional shape after rolling (see FIG. 3) varies depending on the product, and this diagonal dimension is the target dimension with high accuracy. There was a problem that it could not be adjusted to.
This invention is made paying attention to such a problem, and provides the rolling method of the rod-shaped steel materials which can roll a rod-shaped steel materials to a desired shape accurately using a 4 roll rolling mill. It is intended.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the method for rolling a bar-shaped steel material according to the present invention uses a four-roll rolling machine to hot-roll a bar-shaped steel material from a substantially circular cross-sectional shape to a substantially rectangular cross-sectional shape. Rolling of a bar-shaped steel material, characterized in that the diameter of the bar-shaped steel material to be subjected to roll rolling is determined based on the correlation between the roll diameter ratio A of a four-roll rolling mill and the width spread rate γ determined for each steel type of the bar-shaped steel material Is the method.
However, the roll diameter ratio A = (D−d ₀ ) / d ₀
Spreading ratio γ = (B−d ₀ ) / d ₀
D: Roll diameter of a 4-roll rolling mill
d ₀ : Diameter of rod-shaped steel used for 4-roll rolling
B: Diagonal dimension in cross-sectional shape of rod-shaped steel material to be obtained by four-roll rolling According to such a method, the width spread rate of the rod-shaped steel material can be changed according to the steel type of the rod-shaped steel material and the roll diameter of the four-roll rolling mill. Therefore, the rod-shaped steel material can be accurately rolled into a desired shape using a four-roll rolling mill.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 to FIG. 4 are diagrams for explaining a method of rolling a bar-shaped steel material according to the present invention. FIG. 1 shows a rolling process used when hot-rolling a bar-shaped steel material from a substantially circular cross-sectional shape to a substantially rectangular cross-sectional shape. It is a schematic block diagram of an apparatus. In the figure, 11 is a bar-shaped steel material as a material to be rolled, 12 is a heating furnace for heating the bar-shaped steel material 11, and each bar-shaped steel material 11 coming out of the heating furnace 12 is composed of a plurality of two-roll rolling mills. Are supplied to a 4-roll rolling mill 16 through a rough rolling mill row 13, an intermediate rolling mill row 14 and a finishing rolling mill row 15.
[0007]
The four-roll rolling mill 16 includes four flat rolls 17a to 17d (see FIG. 2), and the bar-shaped steel material 11 supplied to the four-roll rolling mill 16 has a substantially circular cross-sectional shape as shown in FIG. To be rolled into a substantially rectangular cross-sectional shape. In FIG. 1, reference numeral 18 denotes an entrance-side dimension measuring device that measures the dimensions of the bar-shaped steel material 11 before entering the 4-roll rolling mill 16, and 19 denotes an output that measures the dimensions of the bar-shaped steel material 11 that has exited from the 4-roll rolling machine 16. The side dimension measuring device is shown, and the bar-shaped steel material 11 that has come out of the four-roll rolling mill 16 is sent to the next process by a pinch roll 20.
[0008]
When the present inventors finally roll the rod-shaped steel material 11 into a substantially rectangular cross-sectional shape 1 as shown in FIG. 3 using the rolling apparatus having such a configuration, the corners in the rectangular cross-section after rolling are shown. The value of the radius R of the portion 2 varies depending on the steel type of the rod-shaped steel material and the roll diameter D of the four-roll rolling mill. For this reason, the diameter d ₀ in the cross-sectional shape 3 of the rod-shaped steel material before the four-roll rolling (hereinafter referred to as the base material) The diameter D ₀ ) and the opposite dimension d in the cross-sectional shape 1 after the 4-roll rolling were found to vary in the diagonal dimension B after rolling even when the rolling was performed under the same conditions. It was. That is, the diagonal dimension B is obtained from the opposite side dimension d and the corner radius R,
B = d√2-2 (√2-1) R
Therefore, if the value of the radius R of the corner portion varies, the diagonal dimension varies.
[0009]
And if it sees about the rod-shaped steel materials of the same steel type, the breadth ratio γ represented by the following formula (1) is the roll diameter ratio A defined by (D−d ₀ ) / d ₀ in the following formula (2). We found that there is a good correlation.
γ = (B−d ₀ ) / d ₀ (1)
A = (D−d ₀ ) / d ₀ (2)
FIG. 4 shows the relationship between the roll diameter ratio represented by (D−d ₀ ) / d ₀ and the width spread rate γ. In the figure, ■ indicates the case where the steel type of the bar steel is MK19S or SGD, ◆ indicates the case where the steel type of the bar steel is SC, and ▲ indicates the case where the steel type of the bar steel is RCS15N. As can be seen, the width spread rate γ of the rod-shaped steel material 11 varies greatly depending on the steel type of the rod-shaped steel material 11 and the roll diameter ratio.
[0010]
Therefore, when rolling the rod-shaped steel material into four rolls, the target diagonal dimension B is obtained based on the width spread rate γ of the rod-shaped steel material 11 based on the steel type of the rod-shaped steel material 11 and the roll diameter D of the four-roll rolling mill 16. The outer diameter d ₀ of the rod-shaped steel material 11 before rolling may be determined.
That is, in order to obtain the diagonal dimension B of the bar-shaped steel material after the four-roll rolling, the diameter d ₀ of the bar-shaped steel material before the rolling is expressed by the following formula (3) by modifying the formula (1).
[0011]
d ₀ = B / (γ + 1) (3)
Here, if the width spread rate γ is obtained in advance with a correlation with the roll diameter ratio as shown in FIG.
γ = f (D, d ₀ ) (4)
Can be left as
Therefore, if the equation (4) is substituted into the equation (3), the base material diameter d ₀ for obtaining the diagonal dimension B can be expressed as a function of the roll diameter D and the diagonal dimension B. In this way, the target diagonal dimension B is obtained by determining d ₀ from the diagonal dimension B and the roll diameter D.
[0012]
As shown in FIG. 5, since the correlation between the roll diameter ratio and the width spread rate γ differs depending on the steel type, the correlation equation f (D, d ₀ ) in the equation (4) needs to be determined for each steel type. is there. Further, as shown in FIG. 5, since there is a linear correlation between the roll diameter ratio and the width spread rate γ, the correlation equation f is, for example,
f (D, d ₀ ) = αA + β
However, A is a roll diameter ratio (= (D−d ₀ ) / d ₀ ).
If α and β are coefficients determined from the correlation between the roll diameter ratio and the width spread rate γ, d ₀ can be easily determined.
[0013]
Here, in determining the value of d ₀ may be determined for d ₀ by performing the calculation of the the roll diameter and product dimensions d, for example, as shown in FIG. 5, the four-roll rolling mill For each roll diameter D and product dimension (opposite side dimension d after 4-roll rolling), a table in which the value of d ₀ obtained in consideration of the diagonal dimension B is set is prepared. before performing rolling by rolling mill train 14, the finish rolling mill train 15, reads this table may be determined d _0. It should be noted that after the value of d ₀ is determined, the rolling conditions of the rough rolling mill row 13, the intermediate rolling mill row 14, and the finishing rolling mill row 15 may be set so that the target d ₀ can be obtained. Needless to say.
[0014]
In the embodiment described above, it is preferable to use a pinch roll 20 having a box-shaped caliber 22 as shown in FIG. 6 as a pinch roll for conveying the rod-shaped steel material 11 output from the 4-roll rolling mill 16 to the next process. . This is because the pinch roll 20 does not crush the shape of the corner portion 2 adjusted with high accuracy by the 4-roll mill.
[0015]
【The invention's effect】
As explained above, according to the rolling method of the rod-shaped steel material according to the present invention, the width spread rate of the rod-shaped steel material can be changed according to the steel type of the rod-shaped steel material and the roll diameter of the four-roll rolling mill. It can be used to accurately roll a rod-shaped steel material into a desired shape.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a rolling apparatus used when hot rolling a rod-shaped steel material from a substantially circular cross-sectional shape to a substantially rectangular cross-sectional shape.
FIG. 2 is a diagram showing cross-sectional shapes before and after rolling a rod-shaped steel material by four rolls.
FIG. 3 is a diagram showing a cross-sectional shape of a rod-shaped steel material that has been rolled by four rolls.
FIG. 4 is a diagram showing the relationship between the width spread ratio of a rod-shaped steel material and the roll diameter ratio of a four-roll rolling mill.
FIG. 5 is a diagram showing an example of a table in which a base material diameter d ₀ is set for each roll diameter and product dimension.
FIG. 6 is a cross-sectional view of a pinch roll having a box-shaped caliber.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Bar-shaped steel material 12 Heating furnace 13 Coarse rolling mill row 14 Intermediate rolling mill row 15 Finish rolling mill row 16 Four roll rolling mill rows 17a-17d Roll 18 Entry side size measuring device 19 Outlet side dimension device 20 Pinch roll

Claims (1)

When hot rolling a rod-shaped steel material from a substantially circular cross-sectional shape to a substantially rectangular cross-sectional shape using a four-roll rolling mill, the diameter of the rod-shaped steel material subjected to four-roll rolling was determined for each steel type of the rod-shaped steel material, A method for rolling a bar-shaped steel material, which is determined based on a correlation between a roll diameter ratio A and a width spread rate γ of a 4-roll mill .
However, the roll diameter ratio A = (D−d ₀ ) / d ₀
Spreading ratio γ = (B−d ₀ ) / d ₀
D: Roll diameter of a 4-roll rolling mill
d ₀ : Diameter of rod-shaped steel used for 4-roll rolling
B: Diagonal dimension in the cross-sectional shape of a rod-shaped steel material to be obtained by 4-roll rolling

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