JPH10328706A - Method for hot rolling of metallic plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the reduction of a cutting-away quantity for moving linear flaws occurring at the side tip part of a product plate by bringing a plate width after width rolling down by the vertical rolling mill of a hot rolling mill group composed of the vertical rolling mill and a horizontal rolling mill to a specific dimension range with respect to a slab for hot rolling, which has been subjected to the width rolling down to the specific dimension range by a horizontal opposite system press. SOLUTION: For the width rolling down of the slab for the hot rolling, when the plate width of the product plate is expressed by W, it must be (W-5) to (W+5) mm, and for the plate width after the width rolling down by the vertical rolling mill, it must be (W-15) to (W-5) mm. When the width of the hot rolling slab is larger than (W+5) mm, the cutting-away quantity to obtain a desired plate width is increased and a yield is lowered. On the other hand, when it is smaller than (W-5) mm, since the width rolling down by the vertical rolling mill is suppressed small, width fluctuation in the longitudinal direction is not dissolved. When the width rolling down by the vertical rolling mill is smaller than (W-15) mm, the width at the time of rolling is widened, and the cutting-away quantity is increased. When it exceeds (W-5) mm, since the width rolling down by the vertical rolling mill is suppressed small, the width fluctuation in the longitudinal direction is not dissolved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot rolling method for a metal plate, and more particularly, to a hot rolling slab reduced in width by a horizontally opposed press using a vertical rolling mill and a horizontal rolling mill. The present invention relates to a method of hot rolling by a group of rolling mills.

[0002]

2. Description of the Related Art When a metal plate such as a stainless steel plate or a titanium plate is manufactured from a slab by hot rolling, a defect such as a linear flaw is present at a side end (end in a width direction of the metal plate) of the metal plate. Easy to occur. When good surface accuracy is required for the performance of a rolled product sheet (hereinafter, also simply referred to as a product sheet), when the above-mentioned linear flaw occurs, it is necessary to cut off the linear flaw portion. The reduction in the yield of the product plate due to the removal of such linear flaws is several percent, which is the main cause of the reduction in the yield.

Further, even in the case of a product plate which does not require the removal of linear flaws, it is necessary to grind the linear flaws by polishing or the like, which requires a great number of man-hours.

As a technique for increasing the yield by reducing the cut-off amount for removing the linear flaw, Japanese Patent Laid-Open No.
No. 62807 and Japanese Unexamined Patent Publication No. Hei 5-146807 disclose that a slab side surface is concave-shaped by hot-rolling by using a horizontally opposed press (hereinafter also simply referred to as a press) before hot rolling, and the width is widened by hot rolling. There has been proposed a method for suppressing the above. However, in the width reduction method using a press, the slab width tends to fluctuate along the longitudinal direction of the slab. For this reason, there is a problem that the width accuracy of the product plate is reduced. In addition, the width reduction of the slab refers to the reduction of the slab width.

[0005] In order to suppress a reduction in width accuracy of a product plate when the slab width is reduced by a press, conventionally, the thickness of a material to be rolled (metal plate) is reduced by a horizontal rolling mill, and thereafter, a vertical rolling mill is used. The hot rolling technique of applying the width reduction by the above has been adopted.
In this rolling technique, particularly, the width reduction by a vertical rolling mill is increased to suppress a decrease in width accuracy of a product sheet due to a width reduction press.

However, in the technique of reducing the thickness of a material to be rolled (metal sheet) by a conventional horizontal rolling mill and then performing width reduction by a vertical rolling mill, the vertical rolling in the early stage of rolling has a large width adjusting effect. A large amount of width reduction takes place in the die rolling mill, ie the vertical mill at the top of the rolling line. For this reason, the concave molding provided on the slab side surface by the width reduction press is flattened under a large width pressure in the vertical rolling mill in the initial stage of rolling, and the effect of suppressing the width expansion by hot rolling is lost. . Therefore, if the decrease in the width accuracy of the product plate is suppressed, there is a problem that the cut-off amount for removing the linear flaw increases.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in consideration of the above circumstances, and has been made in consideration of the wire generated at a side end of a product sheet when a metal sheet is manufactured by hot rolling a slab width reduced by a press. An object of the present invention is to provide a hot rolling method for a metal plate, which can reduce the amount of cut-off for removing a state flaw and can suppress a decrease in width accuracy of a product plate.

[0008]

The gist of the present invention resides in a method for hot rolling a metal plate described below.

[0009] A horizontal facing press (W-5) to (W
When a hot rolling slab reduced in width to +5) mm is hot-rolled by a rolling mill group composed of a vertical rolling mill and a horizontal rolling mill, the sheet width after width reduction by the vertical rolling mill is set to ( W-15) to (W-5) mm, and a method of hot rolling a metal plate, characterized in that rolling is performed. Here, W indicates the width of the rolled product plate in mm. Note that the vertical rolling mill refers to a rolling mill provided with a vertical roll, and the horizontal rolling mill refers to a rolling mill provided with a horizontal roll. A hot rolling slab whose width has been reduced by a press is rolled into a product metal plate by a rolling mill group including one or more vertical rolling mills and one or more horizontal rolling mills.

The width W of a rolled product sheet means the width W of a metal sheet after hot rolling by a horizontal rolling mill as a final rolling mill in the above-mentioned rolling mill group.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In order to solve the above-mentioned problems, the present inventors have set the width reduction by pressing and the width reduction by vertical rolling mill at the time of forming a concave shape on the side surface of a slab. Various effects on the linear scratches and width accuracy were examined.

As a result, simply reducing the width reduction amount in the vertical rolling mill in the initial stage of rolling in order to prevent the flattening of the slab side concave formation provided by the width reduction press reduces the total amount of width reduction. The width of the product plate greatly exceeds the predetermined width W of the product plate, and the yield is greatly reduced. However, if the width reduction in the press is increased to compensate for the decrease in the total width reduction, the side edge of the product plate is reduced. It has been clarified that it is possible to reduce the cut-off amount for removing the linear defects and to suppress the decrease in the width accuracy of the product plate.

Next, SUS43 is used as a product metal plate.
0 stainless steel sheet (hereinafter simply referred to as steel sheet), and by the usual rigid-plastic finite element analysis, the side of the product steel sheet when the slab with the concave shape formed on the side surface by width reduction with the width reduction press is hot rolled The width of the linear flaws generated at the end and the change in the depth of the concave molding and the change in the plate width were investigated in detail.

That is, as shown in FIG.
The width of the slab 1 is reduced by a width reduction press (not shown) equipped with a mold 2 having an arc-shaped projection having a height h of 30 mm and a height h of 30 mm to form a concave shape on the side surface of the slab. The width of the linear flaw, the depth of the concave forming, and the width of the steel sheet for each rolling pass when the rolling is completed by a rolling mill group composed of a rolling mill and a horizontal rolling mill and finished to a thickness of 35.0 mm are made normal. The method was studied by rigid plastic finite element analysis. FIG. 2 shows a 35.0 m thick rolled by the conventional rolling pass schedule shown in Table 1.
The linear flaw width, the concave depth (concave molding depth), and the sheet width of the steel sheet when finished to a width of 1,050 mm in m are shown.

The width of the sheet shown in parentheses in Table 1 is an analysis value of the sheet width after reducing the thickness by a horizontal rolling mill. Further, the linear flaw width, the concave depth, and the sheet width in FIG. 2 each show a state after a width reduction or a thickness reduction is performed by a press or a rolling mill.

In the present specification, the plate width in the case of having a concave shape refers to the width of the most bulged portion in the width direction at both ends.

[0017]

[Table 1]

In the conventional rolling pass schedule of Table 1,
The width of the plate after the width reduction press is 1100 mm, which is 50 mm wider than the product width (finished width) of 1050 mm. The reduction amount is as large as 20 mm, 53 mm and 69 mm, respectively. For this reason, the concave molding with a depth of 30 mm on each side of the slab side surface provided by the width reduction press almost disappears at the stage after the width reduction by the vertical rolling mill E2. That is, after the width is reduced by the vertical rolling mill E2, the slab side surface is flattened. Therefore, as shown in FIG. 2, the vertical mill E
After width reduction in 2, the linear flaw width sharply increases,
In a 50 mm product steel plate, a linear flaw of 17.0 mm is generated on one side.

Next, in the rolling pass schedule shown in Table 1, when the width was reduced by the vertical rolling mills E1 to E4 and the sheet was rolled to a sheet thickness of 35.0 mm, that is, as shown in Table 2, After reducing the width by a press equipped with a mold having an arc-shaped projection, the linear flaw width, the concave depth and the thickness of the steel sheet when rolled only by the horizontal rolling mills R1 to R6 and finished to a sheet thickness of 35.0 mm. The plate width was investigated by rigid plastic finite element analysis in the usual way. In addition, the sheet width shown in parentheses in Table 2 is an analysis value of the sheet width after thickness reduction by a horizontal rolling mill.

[0020]

[Table 2]

FIG. 3 shows a comparison of the side end shape after rolling by the horizontal rolling mill R6, that is, the side end shape of the product steel plate when rolling is performed according to the pass schedules in Tables 1 and 2. (A) shows the side end shape of the product steel sheet after rolling by the horizontal rolling mill R6 in the pass schedule of Table 1 in which the width reduction was also performed by the vertical rolling mills E1 to E4, and FIG. It is a figure which shows the side end part shape of the product steel plate after rolling by the horizontal rolling mill R6 in the pass schedule of Table 2 which did not perform width reduction by the mold rolling mills E1-E4. When the width reduction was performed by the vertical rolling mills E1 to E4 (FIG. 3A), no concave shape was left at the end of the steel plate side, but the vertical rolling mills E1 to E4 did not.
It can be seen that when the width reduction due to the above is omitted (FIG. 3 (b)), a concave shape remains at the width end of the steel sheet.

FIG. 4 shows the linear flaw width, the concave depth and the sheet width of the steel sheet when the sheet was rolled according to the pass schedule shown in Table 2 and finished to a sheet thickness of 35.0 mm. The linear flaw width, concave depth, and plate width in FIG. 4 also show the state after the width reduction or the thickness reduction is performed by a press or a rolling mill.

When the width reduction by the vertical rolling mills E1 to E4 is omitted, the width of the linear flaw is reduced because the concave shape remains at the end of the steel sheet side, and after the rolling by the final horizontal rolling mill R6. In the product steel sheet of (1), a linear flaw of 2.7 mm is formed on one side, and it can be seen that the cut-off amount for removing the linear flaw can be reduced.

However, on the other hand, vertical rolling mills E1 to E4
Without the width reduction according to the following, for a product width of 1050 mm rolled by the conventional pass schedule shown in Table 1,
Since the plate width after rolling by the final horizontal rolling mill R6, that is, the plate width of the rolled product plate becomes as large as 1130 mm, in order to adjust to the desired plate width of 1050 mm,
It is necessary to increase the cut-off amount with the increase in the plate width, and therefore, the yield is reduced.

Next, as shown in Table 3, the width reduction by the press and the vertical rolling mill E1 provided with the above-mentioned mold having the arc-shaped projections is made the same as that of the conventional method shown in Table 1. When the sheet width after the width reduction in the vertical rolling mills E2 to E6 is almost equal to the sheet width after the width reduction in the vertical rolling mill E1, the sheet width is 35.0 mm and the sheet width is finished to 1090 mm. In other words, the plate widths after the width reduction in the vertical rolling mills E2 to E6 are almost the same, but the desired plate width is 1078 to 1082 mm larger than 1050 mm, and the vertical rolling mill and the horizontal rolling mill are used. Rolled by rolling mills, thickness 3
The width of the linear flaw, the depth of the concave shape, and the width of the steel sheet when the sheet width was finished at 5.0 mm to a sheet width of 1090 mm were investigated by rigid-plastic finite element analysis by a usual method. In addition, the sheet width shown in parentheses in Table 3 is an analysis value of the sheet width after thickness reduction by a horizontal rolling mill.

[0026]

[Table 3]

FIG. 5 shows the linear flaw width, the concave depth and the sheet width of the steel sheet when the sheet was rolled according to the pass schedule shown in Table 3 and finished to a sheet thickness of 35.0 mm and a sheet width of 1090 mm. The linear flaw width, the concave depth, and the sheet width in FIG. 5 also show the state after the width reduction or the thickness reduction is performed by a press or a rolling mill.

FIG. 5 shows that the concave molding provided by the width reduction press remains before the width reduction by the vertical rolling mill E3, that is, after the rolling by the horizontal rolling mill R3. Therefore, even when rolling is performed according to the pass schedule shown in Table 3, the linear flaw width is reduced as compared with the case of the conventional rolling pass schedule shown in Table 1, and the product steel sheet after rolling in the final horizontal rolling mill R6 is used. Has a linear flaw of 14.1 mm on one side,
The cut-off amount for removing the linear flaw can be reduced.
However, the sheet width after the width reduction in the vertical rolling mills E1 to E6 is set to 1078 to 1010 which is larger than the desired sheet width of 1050 mm.
Since it was 82 mm, as in the case of rolling with the pass schedule shown in Table 2 above, for a product width of 1050 mm rolled with the conventional pass schedule shown in Table 1,
Since the strip width after being rolled by the final horizontal rolling mill R6, that is, the strip width of the rolled product sheet becomes as large as 1090 mm, the cut-off amount accompanying the increase in the strip width in order to adjust to the desired strip width of 1050 mm. Needs to be increased, and as a result, the yield decreases.

Therefore, various studies were conducted by increasing the width reduction amount of the width reduction press. As a result, 1045
When the width is reduced to 1055 mm, the width of the sheet after the width reduction by the vertical rolling mill is set to 1035 to 1045 mm, and hot rolling is performed by a rolling mill group including a vertical rolling mill and a horizontal rolling mill, a linear defect is obtained. It has been found that the width is reduced and that the yield can be increased because it can be adjusted to the desired plate width of 1050 mm.

Table 4 and FIG. 6 show an example of the examination results. Table 4 shows that the width of the product was reduced to 1050 mm, which is the width of the product steel plate, by the width reduction press provided with the mold having the above-described arc-shaped projections, and further, the plate after the width reduction by the vertical rolling mills E1 to E6. The width is set to 1038 to 1042 mm and rolled by a rolling mill group including a vertical rolling mill and a horizontal rolling mill to obtain a thickness of 3 mm.
This is a pass schedule in the case of finishing to a plate width of 1050 mm with 5.0 mm. In addition, the sheet width shown in parentheses in Table 4 is an analysis value of the sheet width after thickness reduction by a horizontal rolling mill.

[0031]

[Table 4]

FIG. 6 shows the linear flaw width, the concave depth and the sheet width of the steel sheet when the sheet was rolled according to the pass schedule shown in Table 4 and finished to a sheet thickness of 35.0 mm and a sheet width of 1050 mm. The linear flaw width, concave depth, and sheet width in FIG. 6 also show the state after the width reduction or the thickness reduction is performed by a press or a rolling mill.

From the comparison between FIG. 6 and FIG. 5, the linear flaw width and the concave shape for each rolling when rolling was performed according to the pass schedule shown in Table 4 (FIG. 6) and when rolling was performed according to the pass schedule shown in Table 3 (FIG. 5). It is clear that the change in depth is about the same. That is, by increasing the width reduction amount of the width reduction press,
It can be seen that there is almost no effect by setting the plate width after pressing down to 1050 mm, which is the same size as the plate width of the product steel plate.

When rolling is performed according to the pass schedule shown in Table 4, the linear flaw width is reduced as compared with the case of the conventional rolling pass schedule shown in Table 1, and in the case of a product steel plate having a width of 1050 mm, 14.5 mm on one side. It becomes a linear flaw, and the cut-off amount for removing the linear flaw can be reduced. Moreover, since the width of the strip after the width reduction in the vertical rolling mills E1 to E6 was set to 1038 to 1042 mm smaller than the desired strip width of 1050 mm, the product width of 1050 mm rolled by the conventional pass schedule shown in Table 1 was used. A product with the same plate width is obtained. Therefore, 1 in the path schedule of Table 3 described above.
1 which is the desired sheet width as in the case of rolling to 090 mm
It is not necessary to increase the cut-off amount for adjusting to 050 mm. Therefore, the yield is improved as compared with the conventional rolling pass schedule.

If the width of the hot-rolled slab whose width has been reduced by the press is larger than (W + 5) mm, the width of the rolled product sheet greatly exceeds the desired sheet width W. In this case, the amount of cut-off increases, and the yield decreases. On the other hand, when the width of the hot-rolled slab reduced in width by the press is smaller than (W-5) mm, the width reduction amount in the vertical rolling mill is set in order to set the width of the rolled product plate to a desired width. Since it is necessary to keep the width small, it is difficult to eliminate the width fluctuation in the longitudinal direction of the slab caused by the width pressure by the press, and therefore, a reduction in the width accuracy of the rolled product sheet is inevitable. For this reason, the width of the hot-rolled slab when the width is reduced by a press is set to (W-5) to (W + 5) mm.

Further, even when the width of the hot-rolled slab is reduced to (W-5) to (W + 5) mm when the width is reduced by a press, removal of the linear flaws generated at the side end of the product plate. In order to achieve both reduction in the amount of cut-off and suppression of a decrease in width accuracy of the product plate, the slab is hot-rolled by a rolling mill group including a vertical rolling mill and a horizontal rolling mill. At the time, the width of the plate after the width reduction by the vertical rolling mill was changed to (W-
15) It is necessary to roll to (W-5) mm. When the width of the sheet after the width reduction by the vertical rolling mill is less than (W-15) mm, the concave shape provided at the slab side end is flattened by the press, so that the width at the time of hot rolling is increased. This is because the amount of cut-off for removing linear flaws increases and the yield decreases. Further, when the above-mentioned strip width exceeds (W-5) mm, it is necessary to reduce the width reduction in the vertical rolling mill in order to set the strip width of the rolled product sheet to a desired W, This is because it is difficult to eliminate the width variation in the longitudinal direction of the slab caused by the pressing under the width pressure, and the width accuracy of the rolled product sheet is reduced.

In order to set the sheet width to (W-15) to (W-5) mm after the width reduction by the vertical mill, the roll interval of the vertical mill is set to (W-15) to (W-15). -5) It may be adjusted to mm and rolled.

[0038]

In the following, a slab having SUS430 as a base material is reduced in width by a press and then hot-rolled by a group of rolling mills composed of a vertical rolling mill and a horizontal rolling mill to obtain a sheet thickness of 35 m.
An example in which a sheet width of 1050 mm is finished with m will be described.

First, a slab having a thickness of 206 mm and a width of 1280 mm and made of SUS430 as a base material was continuously cast. Next, after heating this slab to 1210 ° C., JIS SKD
Using a press having a die 61 as a base material and a die having an arc-shaped projection shown in FIG.
The width was reduced to 00 mm. After this width reduction, hot rolling was performed by a rolling mill group including a vertical rolling mill and a horizontal rolling mill according to a normal pass schedule shown in Table 5 to obtain a sheet thickness of 35 m.
m, board width 1050m.

[0040]

[Table 5]

The thus obtained linear flaw at the end of the 35 mm thick steel plate side was 17.3 mm on one side.

Next, the continuous casting thickness of 206 m
After heating a slab having a base material of SUS430 having a width of 1280 mm and a width of 1280 mm to 1210 ° C., using a press provided with a mold having JIS SKD61 as a base material and having a circular projection shown in FIG. The width was reduced to 1,050 mm in width by an ordinary method. After this width reduction, hot rolling was performed by a rolling mill group composed of a vertical rolling mill and a horizontal rolling mill according to the pass schedule shown in Table 6 to obtain the same sheet thickness of 35 mm and sheet width of 1 as described above.
Finished to 050 mm.

[0043]

[Table 6]

The thus obtained linear flaw at the end of the 35 mm thick steel plate side was 14.6 mm on one side. Therefore, the cut-off amount for removing linear flaws could be reduced by 2.7 mm on one side as compared with the case of rolling according to the normal pass schedule shown in Table 5 above.

In addition, as a result of automatically measuring the variation of the sheet width at the exit side of the horizontal rolling mill R6 when rolling was performed according to the pass schedules shown in Tables 5 and 6, the results were obtained according to the pass schedule of Table 6 according to the method of the present invention. In the case of rolling, it was confirmed that the sheet width variation was the same as that in the case of rolling by the conventional pass schedule shown in Table 5, although the linear flaw width was reduced.

[0046]

According to the method for hot rolling a metal sheet of the present invention, the amount of cut-off for removing linear flaws generated at the side end of the product sheet can be reduced, and the width accuracy of the product sheet can be reduced. It is possible to suppress.

[Brief description of the drawings]

FIG. 1 is a view for explaining width reduction of a slab by a width reduction press provided with a mold having an arc-shaped projection.

FIG. 2 shows a conventional rolling pass schedule for rolling to a thickness of 3
It is a figure which shows the linear flaw width | variety, concave depth (concave molding depth), and the board width of a steel plate at the time of finishing to 1050 mm in width by 5.0 mm.

FIG. 3 is a view showing the shape of a product side end depending on the presence or absence of width reduction by a vertical rolling mill. FIG. 3 (a) shows a horizontal rolling mill R in a pass schedule in which width reduction is also performed by vertical rolling mills E1 to E4.
6 shows the side end shape of the product steel sheet after rolling by the vertical rolling mills E1 to E4, and (b) shows the side end of the product steel sheet after rolling by the horizontal rolling mill R6 in the pass schedule in which the width reduction was not performed by the vertical rolling mills E1 to E4. It shows the shape.

FIG. 4 shows a thickness of 35 mm without width reduction by a vertical rolling mill.
It is a figure which shows the linear flaw width | variety at the time of finishing to 0 mm, concave depth, and the board width of a steel plate.

FIG. 5: Limiting the width reduction amount by a vertical rolling mill to a thickness of 3
It is a figure which shows the linear flaw width | variety, concave depth, and the board width of a steel plate at the time of finishing to 1090 mm in width by 5.0 mm.

[FIG. 6] The width reduction by the vertical rolling mill is limited, and the width reduction of the width reduction press is increased to increase the width by 105 mm in the width of 35.0 mm.
It is a figure which shows the linear flaw width | variety at the time of finishing to 0 mm, concave depth, and the board width of a steel plate.

[Explanation of symbols]

 1: Slab 2: Die R: Die projection radius h: Die projection height

Claims (1)

[Claims] (1) A horizontal facing press (W-5) to (W +
5) When the hot rolling slab reduced in width to mm is hot rolled by a rolling mill group composed of a vertical rolling mill and a horizontal rolling mill, the sheet width after the width reduction by the vertical rolling mill is set to ( W
(15) A method for hot rolling a metal plate, wherein the method is performed by rolling to (W-5) mm. Here, W indicates the width of the rolled product plate in mm.