JPH07314002A - Method for edging slab by press working - Google Patents

Abstract

PURPOSE:To obtain a method for edging a slab by which uniform width is attained over the entire length of a rolled steel sheet. CONSTITUTION:In this edging method of the slab by press working, in a stage where a prescribed width is attained by applying press working to the slab 1 in the width direction at the time of manufacturing the steel sheet by hot- rolling the slab, the front end part 111 and the rearmost end part 112 in the longitudinal direction of the slab 1 are formed narrower than the middle stationary part 13 and the front and rear end parts 11, 12 over a prescribed length toward the intermediate stationary part from both end parts are formed wider than the intermediate stationary part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of hot-rolling a slab to produce a steel sheet, and pressing the slab in the width direction to reduce the width of the slab.

[0002]

2. Description of the Related Art A typical example of a conventional slab width reduction method by press working will be described with reference to FIGS.

First, as shown in FIG. 2 (A), there is a method of using a press machine to reduce the slab 1 to a predetermined width W over its entire length. However, according to this method, as shown in FIG. 2 (B), due to the difference in metal flow between the tip portion of the slab and the intermediate steady portion, the most distal end portion M of the rolled steel sheet
1 and the rear end portion M2 have wide portions, and the front end portion N1 and the rear end portion N that have entered the stationary portion side somewhat from that portion.
2 has a narrow portion, resulting in a decrease in plate width accuracy and a decrease in product yield.

The conventional method shown in FIG.
140701), the front and rear end parts 11 of the slab 1,
The fixed lengths LT and LB of 12 are pressed wider than the intermediate stationary portion 13. However, in this method, as shown in FIG. 3B, a wide portion is formed at the most distal end portion M1 and the rearmost end portion M2 of the rolled steel sheet, and the slab end portions 1
Depending on the length of 1 and 12, the connecting part M between both ends and the steady part
3 produces a wide part. As a result, the plate width accuracy is lowered and the product yield is lowered.

The conventional method shown in FIG.
No. 0041), the front and rear end portions 11, 12 of the slab 1 are disclosed.
Are formed to be wider than the intermediate stationary part, and their connecting parts 11
1,112 is formed in a stepped shape. According to this method, the wide part as described above does not occur in the part of the rolled steel plate that is slightly inside the steady part with respect to the front and rear ends, but the wide parts M1 and M2 still occur at both ends. This method has not achieved the improvement of the plate width accuracy and the yield although the pressing process takes time.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a method for pressing a slab that does not form a wide portion at the front and rear ends of a rolled steel sheet.

[0007]

According to the method for reducing the width of a slab by pressing according to the present invention, when a steel sheet is manufactured by hot rolling the slab, the slab is pressed in the width direction to obtain a predetermined sheet width. In the process, the slab's longitudinal most distal end and its rearmost end are formed to be narrower than the intermediate steady part,
The front and rear end portions extending from the both end portions toward the intermediate stationary portion for a predetermined length are formed wider than the intermediate stationary portion.

[0008]

According to the method of the present invention, the front and rear end portions of the slab and the steady portion are narrowed, so that the metal flow at the front and rear end portions and the metal flow at the intermediate steady portion during hot rolling of the slab are reduced. It is possible to compensate the plate width variation due to the difference of
As a result, the strip width of the rolled steel sheet becomes uniform over the entire length.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for reducing the width of a slab by press working according to the present invention will be described with reference to FIGS.

As shown in FIG. 1, in the width reduction method of the present invention, in producing a steel sheet by hot rolling the slab, the slab is pressed in the width direction to obtain a predetermined sheet width. Predetermined lengths LT1 and LB1 of the most distal end portion 111 and the rearmost end portion 112 in the longitudinal direction of No. 1 are formed into widths WT1 and WB1 narrower than the width WM of the intermediate stationary portion 13, and the ends are directed toward the intermediate stationary portion. Predetermined length LT2, LB
The front and rear end portions 11 and 12 extending over 2 are formed to have wider widths WT2 and WB2 than the intermediate stationary portion 13.

The lengths LT1, LT2, LB1,
With respect to the respective values of LB2 and the widths WT1, WT2, WB1, WB2, optimum values should exist for the slab width W as the base material, the slab width reduction ΔW during rolling, and the like. For example, items such as those shown in Table 1 below are obtained in advance by a test or the like. After that, it updates to the latest optimum value based on the actual value.

[0012]

[Table 1] Next, specific steps of the slab width reduction method of the present invention will be described with reference to FIGS.

First, the press working of the tip portion 11 of the slab 1 will be described. As shown in FIG. 5, when the slab 1 is transported toward the mold 2, the transport distance is measured by the measuring roll 3 and the hot material detector 4. When the tip of the slab 1 has passed the detector 4 and has traveled a distance L between the molds 2, the slab conveyance is stopped, the interval between the molds 2 is narrowed, and the tip end portion 111 of the tip end portion 11 has a width WT1. (A).

Next, the mold opening is changed from WT1 to WT2 (WT
1 <WT2), the opening is maintained and the slab 1 is advanced by a predetermined distance (LD + LT) (B). During this time, the slab 1 is pressed down to the width WT2.

When the slab 1 advances by a distance (LD + LT), the slab 1 is stopped and the mold opening is changed from WT2 to WM.
Change to (WT2> WM) (C).

While maintaining the mold opening WM, the intermediate stationary portion 13 of the slab 1 is pressed down to the width WM (D).

Next, the press working of the rear end portion 12 of the slab 1 will be described with reference to FIG. In the press working of the rear end portion 12, a forward mold 2a, a reverse mold 2b, and a mold switching device (not shown) are used.

After advancing the reduction (D) of the intermediate stationary portion 13 by a predetermined distance, the slab 1 is stopped and the die 2a is stopped.
Open wider than the base material width (A).

Next, while the slab transportation distance is measured by another measuring roll 3a and another hot material detector 4a, the slab 1 is transported to the vicinity of the corner portion of the die 2a ( B).

At this point, the mold 2a is switched to the reverse mold 2b, and the steps (A)-(D) of FIG. 5 described above are performed with the slab conveyance direction reversed. After the rear end 12 of the slab 1 is pressed, it is pressed down to the unpressed lower part of the stationary part 13 with a width WM (C).

Specific examples of the present invention are shown in Table 2 below in comparison with the conventional method. In addition, the conventional method No.
6, 7, and 8 correspond to the conventional method described with reference to FIGS. In addition, the method of the present invention No. The plate width variation of No. 1-5 is shown in (A)-(E) of FIG. 6
The plate width variation of -8 is shown in (A)-(C) of FIG. 9, respectively.

[0022]

[Table 2] The result of comparison between the method of the present invention and the conventional method for a wide material (1400 mm or more) is shown in FIG. The definition of the plate width fluctuations ΔW and ΔW1 in the diagram (A) is shown in the diagram (B).

According to the method of the present invention, the width variation within the plate (ΔW)
Is reduced by about 6 mm, and plate width fluctuation on the narrow side (ΔW1)
Is reduced by about 3 mm. By reducing ΔW1 by about 3 mm, the yield can be improved by 3/1400 = 0.2%.

[0024]

EFFECTS OF THE INVENTION According to the present invention, it is possible to eliminate the forefront / rear end width expansion peculiar to hot rolling and the width shrinkage or width expansion that occur at both ends near the steady part, which have occurred in the conventional method, and to eliminate the entire width of the steel sheet It is possible to obtain a substantially uniform plate width. As a result, the plate width accuracy and the yield can be improved.

[Brief description of drawings]

FIG. 1 is a plan view of a slab after pressing by the method of the present invention.

FIG. 2 is an explanatory view of a conventional method, which is a plan view of a slab after pressing (A) and a graph (B) showing a change in plate width after rolling.
Represents and.

FIG. 3 is an explanatory view of another conventional method, showing a plan view (A) of a slab after pressing and a graph (B) showing a change in plate width after rolling.

FIG. 4 is an explanatory view of still another conventional method, and shows a plan view (A) of a slab after pressing and a graph (B) showing a change in plate width after rolling.

FIG. 5 is an explanatory view of the method of the present invention, showing a pressing process of a slab tip and an intermediate part.

FIG. 6 is an explanatory view of the method of the present invention, showing a pressing step of the middle portion and the rear end portion of the slab.

FIG. 7 is an explanatory view showing the effect comparison between the method of the present invention and the conventional method, showing a strip width variation comparison graph (A) and its explanatory graph (B).

FIG. 8 is a graph showing plate width fluctuation after rolling of a slab based on the method of the present invention.

FIG. 9 is a graph showing plate width variation after rolling of a slab based on a conventional method.

[Explanation of symbols]

 1: Slab 2, 2a, 2b: Mold 3, 3a: Measuring roll 4: Hot material detector 11, 12: Front / rear end part 13: Intermediate steady part 111, 112: First / rear end part

Claims (1)

[Claims] 1. When manufacturing a steel sheet by hot rolling a slab, in the step of press-working the slab in the width direction to obtain a predetermined plate width, the most distal end and the rearmost end in the longitudinal direction of the slab are intermediate. A slab by press working characterized in that it is formed to be narrower than the stationary portion, and the front and rear end portions extending from the both end portions toward the intermediate stationary portion for a predetermined length are formed to be wider than the intermediate stationary portion. Width reduction method.