JP2970484B2 - Rolling method of thick steel plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of rolling a thick steel plate to be rolled by using a horizontal rolling mill and an edger, and more particularly to a method of rolling a thick steel plate so that the planar shape of a rolled steel plate becomes almost rectangular.

[0002]

2. Description of the Related Art Generally, when rolling a thick steel plate, a rectangular slab having a flat shape is first rolled in the width direction, and then rotated in a horizontal plane by 90 degrees to perform rolling in the longitudinal direction. Rolling of this thick steel plate is performed using a horizontal rolling mill, but when rolling is performed only with a horizontal rolling mill, the planar shape of the rolled steel plate is determined by the tentering ratio (width of rolled steel plate / rolled slab). When the width) is small and the stretch length ratio (the length of the steel sheet after rolling / the length of the slab before rolling) is large, it becomes a drum shape as shown in FIG. When the stretch length ratio is small, a drum shape as shown in FIG. 7B is obtained.

[0003] In order to obtain a rectangular product steel plate having a predetermined width and length from a rolled steel plate having a flat drum shape or a drum shape, the rolled steel plate must be prepared in advance with respect to FIG.
In (A) and FIG. 7 (B), a surplus width and surplus length indicated by hatching are given, and the surplus width and surplus length portion have to be truncated.

[0004] In order to reduce the truncation loss and make the planar shape of the rolled steel sheet closer to a rectangular shape, a so-called edger method of using a horizontal rolling mill and an edger together to make the planar shape closer to a rectangular shape has been widely adopted. ing.

To explain the edger method, in order to improve the planar shape of the hourglass, as shown in FIG. 8A, a steel sheet 1 having the hourglass shape is horizontally rolled in the longitudinal direction (hereinafter referred to as “finishing rolling”). Before or after)
Edger rolls 2A, 2A
Edging using B (hereinafter “finishing edging”)
).

[0008] In the case of a drum-shaped steel sheet 1, as shown in FIG. 8 (B), before, during or after horizontal rolling in the width direction of the steel sheet (hereinafter referred to as “width rolling”).
Edging of the fish tail portion corresponding to the front and rear ends of the steel sheet (hereinafter referred to as “width edging”) is performed.

[0007] By improving the shape of the tongue portion or the fish tail portion in this manner, the shape of the steel plate after rolling can be made closer to a rectangle.

As a specific method of rolling a thick steel plate using the edger method, a conventional method has been known, for example, from Japanese Patent Publication No. 61-500
No. 43, the product of the fishtail length (one side) before and after the rolling direction generated when a dog bone generated by edging rolling is immediately horizontally rolled in the same direction as edging rolling, and the remaining tentering ratio after edging rolling are calculated. A rolling method is disclosed in which rolling is performed so that the reduction amount of the edging rolling is equal to の of the width (both sides) of the drum shape after finishing rolling caused by tentering rolling.

In Japanese Patent Application Laid-Open No. Sho 62-192201, the flat shape of the material to be rolled is made rectangular after each rolling pass of the adjusting rolling pass, the tentering rolling pass, and the finishing rolling pass. A rolling method is disclosed in which vertical roll rolling is performed while adjusting the roll opening so as to cancel out the expected crop and Tyco shapes in each rolling pass before starting horizontal rolling in each rolling pass.

[0010]

However, these proposals propose an optimum necessary edging amount and its timing. When edging is performed over a plurality of passes, the necessary edging amount is reduced by a plurality of passes. Does not suggest how to allocate them. In fact, as shown in the embodiment in JP-B-61-50043, it is shown that the distribution is performed in the same manner.

However, in the rolling of this type of thick steel plate, horizontal rolling is performed by reverse rolling. Therefore, edging performed in the middle of the pass is generally performed in two reciprocating passes in reverse.

In this reverse rolling, it has been found that the plane shape of the rolled steel sheet greatly changes depending on the amount of edging necessary for distributing the necessary edging amount to a plurality of passes, as will be described later.

[0013] Accordingly, the present invention provides a method for edging the steel sheet after rolling in which one or more reciprocating passes or a plurality of reciprocating passes are continuously performed in the rolling of a thick steel sheet. It is an object of the present invention to make the planar shape of the shape closer to a rectangle so as to minimize the truncation loss at the time of commercialization.

[0014]

Means for Solving the Problems] The present invention which has solved the above-mentioned problems, according edger, BEFORE or during tentering rolling
Edging or before or during finish rolling
Finish edging in one round trip or multiple passes
Continuously performed over the return pass , and thereafter, a method of rolling a thick steel plate that is subjected to horizontal rolling, based on a necessary edging amount, dimensions of the steel sheet at the time of edging, and horizontal rolling conditions of the first pass after edging, After edging
The required edging amount is distributed to each pass so that the fishtail length of the thick steel plate after the horizontal rolling in the first pass is the same at the front and rear ends and both sides in the rolling direction. is there.

In the present invention, one round-trip path or a plurality of
In performing the edging of the reciprocating pass or more , so as to make the plane shape of the thick steel plate rectangular after the completion of the entire rolling process,
In order to make the size of the fish tail the same, determine the distribution ratio that distributes the necessary edging amount to each path,
Perform edging . Therefore, the planar shape after the subsequent horizontal rolling can be made closer to a rectangle, and thus, the cut-off loss at the time of commercialization can be reduced.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reason why the planar shape of a steel sheet is not made rectangular is that a fish tail is generated at the time of edging and the fish tail grows at the time of horizontal rolling in the first pass after the edging. That's why.

However, with respect to the fish tail generated during the edging and the fish tail grown during the horizontal rolling in the first pass after the edging, the biting side tends to be larger than the biting side.

That is, in the case where edging in only one direction and horizontal rolling are considered, the fishtail length generated by performing edging in the direction shown in FIG. 3A is as shown in FIG. 3B. , towards the biting side fish tail length ΔL ₁ bite missing side fish tail length ΔL ₂ than increases. Further, after the edging is performed, as shown in FIG.
In the stage where the horizontal rolling of the first pass is performed, the growing fish tail as shown in FIG.
The higher the bite missing side growth rate r ₂ than the biting side growth rate r _1.

However, in the case where edging is performed in a reciprocating pass, as shown by an arrow in FIG. 4A, when edging is performed in the first pass on the outward path side, the fishtail length ΔL _B1 on the biting side is The length of the fishtail on the biting side is longer than ΔL _T1 . Subsequently, when the second pass on the return path is performed, if the edging amounts of the first pass and the second pass are the same, as shown in FIG. 4B, the front-rear end asymmetry of the fish tail shape is canceled out, ΔL _B2 and Δ
L _T2 will be equal. However, the bite-side fishtail growth rate r _B during the subsequent finish rolling by the horizontal rolling mill is larger than the bite-side fishtail growth rate r _T , so that the finish rolling was performed by the horizontal rolling mill. After that, as shown in FIG. 4C, the fishtail length r _B × ΔL _B2 on the biting side becomes larger than the fish tail length r _T × ΔL _T2 on the biting side.

FIG. 5 shows an example of the planar shape of the rolled steel sheet when the lengths of the front and rear end fish tails after rolling are not equal. Here, FIG. 5 (A) shows the plan shape of the thick steel plate after the tentering edging, and FIG. 5 (B) shows the plan shape of the thick steel plate after the finish edging.

Therefore, in the present invention, the edging by the edger is performed continuously over one or more reciprocating passes or a plurality of reciprocating passes. , The fishtail length of the thick steel plate after the first pass horizontal rolling after the edging is the same at the front and rear ends and both sides in the rolling direction, based on the horizontal rolling conditions of the first pass after the edging. Thus, the necessary edging amount is allocated to each pass.

Hereinafter, embodiments of the present invention and the principle of the present invention will be specifically described with reference to the drawings. FIG. 1 is a flowchart of a rolling method according to the present invention,
The subject of the slab, if necessary, established a slab thickness by first forming path, after rolling tentering, or in the course of direct finish rolling, before or during tentering rolling, performing tentering edge in g, Or finishing pressure
In extended before or during, performs finishing edge in g.

[0023] In these tentering edge in g and or finishing edges in g, the edging by edger
It is performed continuously over one or more reciprocating passes or multiple reciprocating passes .

Each path (1) in the edging process
A method for calculating the distribution rate of the edging amount for a reciprocating pass or a plurality of reciprocating passes) will be described by taking finishing edging as an example.

As shown in FIG. 2, when the rolled steel plate 1 is edging Ejjaroru 2A, by 2B, the ratio of the fishtail length after edging, a fishtail length of biting side [Delta] L _1, chewing release side Is expressed as ΔL ₂ , the following equation (1) is obtained.

[0026]

(Equation 1)

The expression (1) expressed in the function form can be specifically expressed as, for example, the expression (2).

[0028]

(Equation 2)

In the equation (2), the constants a and b are numerical values obtained empirically, and these numerical values include the influence of the edger roll diameter R _V.

The ratio of the growth rate of the fish tail at the front and rear ends in the first pass of the horizontal rolling after the edging is represented by r ₁ as the growth rate of the fish tail on the biting side and as the growth rate of the fish tail on the non-biting side. r ₂ is represented by the following equation (3).

[0031]

(Equation 3)

The expression (3) expressed in the form of a function can be specifically expressed as, for example, the expression (4).

[0033]

(Equation 4)

In the equation (4), the constants c, d, and e are values empirically obtained, and these values include the effects of the edger roll diameter R _V and the horizontal rolling mill roll diameter R _H. .

Based on these relationships, a more detailed example of how to obtain the distribution ratio of the edging amount in the first pass and the second pass for equalizing the length of the front and rear end fish tails will be specifically described with reference to FIG. Will be described.

First, in the reciprocating path of the edging, as shown in FIG. 6A, the fishtail length of the portion on the biting side in the first pass is ΔL _B1 , and the fishtail length of the portion on the biting side in the first pass is ΔL _B1 . ΔL _T1 , the ratio of the front and rear end fishtail lengths after the first pass can be expressed by the following equation (5).

[0037]

(Equation 5)

Subsequently, as shown in FIG. 6 (B), the fish tail on the biting side in the second pass is ΔL
_T2 , the fish tail on the side of the biting side is ΔL _B2
Then, the ratio of the front and rear end fishtail lengths after the second pass can be expressed by the following equation (6).

[0039]

(Equation 6)

Further, as shown in FIG. 6C, assuming that the biting side of the second pass of the edging is equal to the biting side of the horizontal rolling after the edging, the fishtail growth rate of the biting side is r _T. the fishtail growth chewing release side When r _B, the ratio of r _T and r _B can be expressed by the following equation (7).

[0041]

(Equation 7)

On the other hand, the condition that the final front and rear end fishtail lengths are equal can be expressed by the following equation (8).

[0043]

(Equation 8)

Therefore, the equation (8) is replaced by the equation (6).
By substituting the equation (7), the following equation (9) can be obtained.

[0045]

(Equation 9)

By solving the distribution ratio α in the equation (9), the distribution ratio of the required edging amount in each path can be obtained.

It is clear that such a concept can be applied to both edging and finishing edging as it is. It is also apparent that the present invention can be similarly applied to two or more round trip paths in addition to one round trip path.

[0048]

EXAMPLES The rolling method according to the present invention and the conventional rolling method were performed, and the occurrence rates of truncation loss in each case were compared.

Table 1 shows the roll diameters of the edger roll and the horizontal rolling mill used in this embodiment, and Table 2 shows the rolling conditions of the present invention and the conventional example. As this conventional example, as in the embodiment of Japanese Patent Publication No. Sho 61-50043, the required edger amount is equally divided by one reciprocating pass.

[0050]

[Table 1]

[0051]

[Table 2]

Table 3 shows the distribution ratio of the edging amount of each edging and the cut-off ratio of the rolled steel sheet in the conventional example, and Table 4 shows the distribution ratio of the edging amount of each edging and the cut-off ratio of the rolled steel plate in the example of the present invention. Show.

[0053]

[Table 3]

[0054]

[Table 4]

In this embodiment, case 1 is an example in which only finishing edging is performed without performing tentative edging , and cases 2 to 4 are examples in which tentative edging and finish edging are performed. As can be seen from Table 3 and Table 4, in each of Cases 1 to 4, the cut-off rate of the steel sheet of the present invention was much lower than that of the conventional case due to poor planar shape of the rolled steel sheet. .

Specifically, comparing the average values of the truncation rates in Cases 1 to 4, the average value of the truncation rates in the conventional example was 4.6%, whereas in the case of the present invention example The average value of the truncation rate was 2.7%. As can be seen from the result, the cut-off rate of the shape defect could be reduced by 41%.

[0057]

As is apparent from the above description, according to the present invention, edging is performed one round trip in rolling of a thick steel plate.
When performing continuously in a pass or a plurality of reciprocating passes or more , the distribution of the edging amount at that time can be optimized, and the planar shape of the steel plate after rolling can be made closer to a rectangle, so that the cut-off loss at the time of commercialization can be minimized.

[Brief description of the drawings]

FIG. 1 is a flowchart of a steel plate rolling process according to the present invention.

FIG. 2 is an explanatory diagram of a fish tail generated by edging.

FIG. 3 is an explanatory diagram of a fish tail generated by edging in only one direction and horizontal rolling.

FIG. 4 is an explanatory diagram of a fish tail generated by edging and horizontal rolling in one reciprocating pass.

FIG. 5 is an explanatory view showing a planar shape of a steel plate in a case where fishtail lengths at front and rear ends are different after edging.

FIG. 6 is a process chart showing a process of adjusting a fish tail amount according to the present invention.

FIG. 7 is a cross-sectional view illustrating an example of a shape of a steel sheet after rolling by rolling by a horizontal rolling mill.

FIG. 8 is an explanatory diagram showing edging by an edger.

[Explanation of symbols]

1 ... thick steel plate, 2 ... edger roll, 3 ... horizontal rolling mill roll.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B21B 1/38 B21B 37/16 B21B 37/28

Claims (1)

(57) [Claims] 1. Before or during tent rolling by an edger
Edging in or before finish rolling or
Means finishing edging on the way
A method of rolling a thick steel sheet that is continuously performed over a plurality of reciprocating passes and then horizontally rolled, based on a necessary edging amount, dimensions of the steel sheet at the time of edging, and horizontal rolling conditions in the first pass after the edging. And distributing the necessary edging amount to each pass so that the fishtail length of the thick steel plate after horizontal rolling in the first pass after edging is the same at the front and rear ends and both sides in the rolling direction. Rolling method of thick steel plate.