JPH10156408A - Die for edging press of slab for hot rolling and edging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die for edging press end edging method for suppressing variation in width due to width return at the time of manufacturing a metallic plate by hot-rolling an edged slab, controlling deffects in the side end parts of the metallic plate and preventing burning between the die and the slab at the time of edging the slab. SOLUTION: This method is a method for reducing the initial width W0mm of the slab having the initial thickness of T0mm by Dmm with a box-caliber- shaped die for edging press for the slab for hot-rolling the bottom width Bmm of the caliber, depth Hmm of the caliber and taper angle θ deg. of the side faces of the caliber of which satisfy (T0-20)<=B<=(T0+100), 0<H<=(W0-D)/3 and 0<θ<=10, and a horizontal opposed type press provided with the above-mentioned die. A circular-arcuate projection of <=20mm in height may be provided in the middle part of the bottom of the caliber. At least the tapered part to be the side faces of the caliber is formed by executing build-up using a material whose melting point is higher than that of the base material of the slab and, when the built-up part has hardness of >=80 by Shore hardness, the preventing effect of burning between the die and the slab is greater.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die and a method for reducing the width of a slab for hot rolling. More specifically, when manufacturing metal plates such as stainless steel plates, low alloy steel plates, carbon steel plates, and titanium plates by hot rolling from continuous casting slabs, they are used for pressing to pre-form continuous casting slabs before hot rolling. Mold and width reduction method.

[0002]

2. Description of the Related Art In the production of expensive metal sheets such as metal sheets, especially stainless steel, and pure titanium and titanium alloys (hereinafter, "pure titanium" and "titanium alloy" are simply referred to as "titanium"). Casting a continuous cast slab having a width corresponding to each of a wide variety of product widths causes a significant decrease in casting capacity and an increase in cost. Further, a process such as cutting a so-called "taper slab" generated when changing the slab width into a rectangular parallelepiped with a gas is required, and the cost increases.

[0003] For example, the product width of a hot-rolled steel sheet including a stainless steel sheet generally ranges from 0.8 m to 1.5 m. Therefore, in order to cope with a wide range of product width, for example, a continuous casting slab in which the thickness is constant and the width is changed at a pitch of 50 mm has been conventionally cast.

[0004] However, as described above, casting various types of slabs corresponding to the width of the product steel sheet requires a reduction in the operation rate due to the change of the mold of the continuous casting machine and an increase in the casting capacity due to the casting of the narrow width slab. There has been a problem that the cost is reduced and the cost is increased.

[0005] In contrast to the conventional relationship between the slab width and the product width, in the pre-rolling process of the hot slab, the slab width is greatly reduced (hereinafter, “slab width reduction” is replaced with “slab width reduction” or “slab width reduction”). Slab width reduction), the slab width can be centralized and the slab width can be increased, so that great advantages such as improvement in the capacity of a continuous casting machine can be obtained.

For example, in the production of the above-mentioned hot-rolled steel sheet, the width of the slab to be continuously cast is one type of 1500 mm, and the slab is hot-rolled after variously changing the slab width in the pre-process of the next hot rolling. If a product steel plate can be manufactured in this way, the efficiency and capacity of continuous casting will be greatly improved. For this reason, there is a strong demand for casting with a slab width corresponding to the maximum product width, and for example, reducing the slab width by up to about 600 mm before rough slab rolling in a rolling mill.

As a method of reducing the slab width, there are known a slab width reduction method using a vertical roll and a slab width reduction method using a horizontally opposed press.

However, when the slab width is reduced by using a vertical roll, the cross-sectional shape of the slab becomes a so-called "dog bone" in which only the thickness of the side end is increased. This dogbone-shaped slab has a problem that, when the thickness is reduced by a group of rolling mills provided downstream of the vertical roll, the width returns, so that a rolled plate having a desired product width cannot be obtained.

Japanese Patent Publication No. 50-14632 discloses a vertical roll (edger) with a caliber on the side surface of a slab in at least one pass for reducing the thickness of the slab.
A technique for reducing the pressure is disclosed. However, the technique proposed in this publication is intended only to prevent defects such as cracks occurring at or near the side end of the product plate, and therefore, even if the above technique is used, it is not always necessary to use a dog bone. Was not something that could be eliminated.

On the other hand, when the width of the slab is reduced by using a horizontally opposed press, the contact length between the slab and the tool (press die) during the reduction of the slab width can be increased, so that the slab reduction efficiency is high. For this reason, recently, a method of reducing the width of a slab by a horizontally opposed press has been widely adopted.

Conventionally, a die having a flat pressing surface (hereinafter, referred to as a "flat die") is used as a die for the slab width reduction press.
Has been used. However, the flat mold does not restrain the slab in the thickness direction when the slab is reduced. Therefore,
When a large width reduction of 300 mm or more is applied to a continuously cast slab using a flat mold, it is inevitable that dog bones are generated as in the case of the reduction of the slab width by the vertical roll described above. The occurrence of dog bones when the slab width is reduced by this flat mold is remarkable in the press rolling stationary section where the slab is tightly restrained in the length direction by the flat mold,
There is no constraint in the length direction by the flat mold, or even if it is present, it is not remarkable at the leading and trailing ends of the slab where the constraint is extremely loose. For this reason, when the thickness of the slab is reduced by a group of rolling mills provided at the subsequent stage of the horizontal facing press, the amount of width return at the leading end and the trailing end of the product plate is small. The width becomes significantly narrower than the plate width of the stationary portion where a noticeable dog bone has been generated. By rolling down the material to be rolled (slab) with an edger mill at the time of slab thickness reduction by a group of rolling mills provided at the subsequent stage of the horizontally opposed press, the width of the product plate steady portion and the width of the product plate front end and rear end are reduced. Although the difference from the plate width can be reduced, it is hardly sufficient.

Further, when the width of the slab, especially the width of a slab made of stainless steel or titanium, is greatly reduced by the horizontally opposed press, the shape of the slab corner is sharpened. In the hot rolling of the slab by the group of rolling mills provided in the above, the portion corresponding to the slab corner is supercooled, and the temperature drop becomes large. For this reason, a bar-shaped flaw (hereinafter, referred to as a linear surface flaw) occurs at the side end of the rolled plate. Furthermore, wrinkles on the side surfaces (short side surfaces) of the slab generated during hot rolling of the slab by the rolling mills wrap around flat upper and lower surfaces of the plate to be rolled with the progress of the rolling pass. "Will remain as wrinkle-shaped flaws.

As described above, in the present invention, "linear surface flaws" and "seam flaws" are separately described. FIG.
It is a figure which shows the linear surface flaw and the seam flaw which arise in the metal plate finished by hot rolling. As shown in this figure, if both occur, the positional relationship is such that the "seam flaw" is closer to the side end of the rolled sheet than the "linear surface flaw".

If linear surface flaws or seam flaws occur, especially in the case of products where surface accuracy is an important selling point, this part must be trimmed, and the linear surface flaws and seam flaws are removed. Increases in cost are inevitable due to the accompanying reduction in yield. Further, even in the case of a product whose surface accuracy is not so important, the surface must be cleaned with a grinder to remove linear surface flaws and seam flaws, which requires a great deal of man-hour and time.

For this reason, for example, Japanese Patent Application Laid-Open No. 6-304610
Japanese Patent Application Laid-Open Publication No. H11-163873 discloses a pressing die in which a trapezoidal groove having a specific shape is provided on a pressing surface and a slab corner is chamfered to prevent overcooling of a slab corner. The mold proposed in this publication has a prima facie effect on preventing linear surface flaws due to overcooling of the slab corner. However, it is difficult to obtain the effect of preventing the generation of seam flaws formed by wrinkles on the slab side surfaces (short side surfaces) generated during hot rolling of the slab and rolling over the flat upper and lower surfaces of the plate to be rolled with the progress of the rolling pass. Further, since the hole mold (trapezoidal groove) is not necessarily shaped to restrain the slab in the thickness direction when the slab is reduced, the width of the slab is reduced by using a press having a mold described in the above publication. Dog bones sometimes occurred. In addition, even if dog bone does not occur, seizure may occur between the mold and the slab, and this seizure may remain on the product plate.

Japanese Patent Application Laid-Open No. 146807/1993 discloses that a press working surface (pressing surface) is provided with two grooves having 8-45 ° side walls with respect to the groove bottom. Kinshiki "has been proposed. This is the above anvil (mold)
Press, for example, as shown in FIG.
Pressing using a die with two grooves (groove depth C1, groove inclination angle θ1 with respect to groove bottom, projection height C2), the bottom of the slab short side surface (side surface) A trapezoidal shape having a width L1 is inserted, and then rough rolling and finish rolling are performed.

However, the mold proposed in Japanese Patent Application Laid-Open No. 5-146807 is also disclosed in Japanese Patent Application Laid-Open No. 6-304610.
Hole mold (trapezoidal groove), similar to the mold proposed in
Is not necessarily shaped to restrain the slab in the thickness direction when the slab is reduced, so that even when the width of the slab is reduced by using the press having the mold described in the above publication, dog bones may be generated. In addition, even if dog bone does not occur, seizure may occur between the mold and the slab, and this seizure may remain on the product plate.

A technique of hot rolling a metal plate by forming a trapezoidal split into the entire length of the short side surface (side surface) of the slab is disclosed in Japanese Patent Laid-Open No. 4-2.
It is also disclosed in Japanese Patent No. 62807. Even if the technology proposed in this publication is used, if the division of the trapezoid into the entire length of the short side surface (side surface) of the slab is not an appropriate shape, a predetermined width is secured in the product metal plate. Therefore, it was necessary to reduce the width of the slab by the edger mill when the slab thickness was roughly reduced by a group of rolling mills in the subsequent process. On the other hand, when the width is reduced by an edger mill during rough rolling, the short side surface (side surface) of the slab
In some cases, the effect of dividing the trapezoid into the entire length of the substrate was lost, and linear surface flaws and seam flaws were sometimes generated.

The technology proposed in each of the above publications for rolling a slab with a trapezoidal slit on the short side surface (side surface) is described below.
As shown in FIG. 14 and FIG. 15, the position of the linear surface flaw is made closer to the side end of the rolled material by generating a shallow fold flaw in the center of the sheet thickness, and it is necessary to remove the linear surface flaw. Its main purpose is to reduce trim charges. In addition,
FIG. 14 shows a case where the depth of the fold flaw generated by rolling is larger than the distance between the linear surface flaw and the rolled material side end. FIG.
5 shows the case where the depth of the fold flaw generated by rolling is smaller than the distance between the linear surface flaw and the end of the rolled material.

According to the study of the present inventors, the width of the linear surface flaw becomes smaller as the depth of the trapezoidal shape to be inserted into the short side surface (side surface) of the slab increases. On the other hand, as the depth of the trapezoidal shape increases, the depth of the fold flaw tends to increase. Therefore, in order to reduce the trim allowance due to the linear surface flaw, if the trapezoidal shape is deeply inserted into the slab by preforming by pressing, the deepest part of the fold flaw will be located at the position of the linear surface flaw in the next rolling. It may be closer to the center of the width of the metal plate (see FIG. 14), and after the trimming, linear surface flaws may be eliminated but fold flaws may remain. Further, when the fold flaw is large, if the hot-rolled metal plate is cold-rolled without trimming, there is a concern that a crack may occur on the side end face. From such a viewpoint, it is necessary to optimize the hole shape of the die for the width reduction press of the slab for hot rolling.

[0021]

When a metal plate is manufactured from a continuously cast slab by hot rolling, a wide slab is cast, and a large width reduction is applied to the slab so that the width reduction is 300 mm or more. When performed, as described above, the width variation of the product plate based on the occurrence of dog bone, linear surface flaws,
Problems such as generation of seam flaws and breakage flaws and occurrence of seizure between the mold and the slab when the slab width is reduced are caused. Among the above problems, especially when the width variation of the product plate is large, even if the efficiency and performance of the continuous slab casting are improved, the product yield is greatly reduced and the cost is increased. Therefore, in order to improve both the efficiency and performance of continuous slab casting and the product yield, it is most important to suppress the occurrence of dog bones.

The present invention provides a press die for preforming a continuously cast slab before hot rolling, which can achieve the following when a metal plate is manufactured from a continuously cast slab by hot rolling. It is a first object to provide a width reduction method. A second object of the present invention is to provide a press die and a width reduction method for preforming a continuously cast slab before hot rolling, which can achieve the following.
The present invention provides the following, and combinations thereof, and the following to
It is a third object of the present invention to provide a pressing die and a width reduction method for preforming a continuously cast slab before hot rolling, which can achieve any of the combinations described above.

The generation of dog bones can be suppressed even when a large width reduction such as reducing the slab width by 300 mm or more is performed.

In a metal sheet whose slab thickness has been reduced by a rolling mill after the slab width has been reduced, the width fluctuation of the product sheet due to the difference in width return is extremely small.

[0025] The occurrence of linear surface flaws and seam flaws generated at the side edges of metal plates, especially stainless steel plates and titanium plates, can be suppressed.

The depth of the fold flaw can be reduced.

[0027] The amount of cut-off at the end of the product plate required for removing linear surface flaws, seam flaws, and fold flaws can be reduced.

[0028] Seizure between the mold and the slab when the slab width is reduced can be prevented.

[0029]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a method of (1) to (3) for pressing a slab for hot rolling and a method for pressing a slab for hot rolling (4). It is in.

(1) A box-hole-shaped die for a horizontally opposed press for reducing the width of a slab for hot rolling, the bottom width Bmm, the depth Hmm, and the side taper angle θ of the hole die. A die for a width reduction press of a slab for hot rolling, characterized by satisfying the following formulas.

(T0−20) ≦ B ≦ (T0 + 100)... 0 <H ≦ (W0−D) / 3... 0 ゜ <θ ≦ 10 ゜. Is the initial thickness (mm) of the slab for hot rolling,
W0 is the initial width (mm) of the slab, and D is the width reduction (mm) of the slab.

(2) An arc-shaped protrusion having a height of 20 mm or less is provided at the center of the bottom of the hole mold (1).
4. A die for press-pressing a slab for hot rolling according to 4.

(3) At least the tapered portion serving as the side surface of the hole is formed by building up with a material whose melting point is higher than the melting point of the base material of the slab for hot rolling, and the built-up portion is formed by shore. The die for hot rolling slab according to the above (1) or (2), which has a hardness of 80 or more in hardness.

(4) The width of the slab is reduced by using a horizontal facing press equipped with a die for pressing the width of the slab for hot rolling according to any one of the above (1) to (3). A width reduction method for a slab for hot rolling, characterized by comprising:

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have studied various techniques for performing hot rolling after reducing the width of a slab by 300 mm or more using a horizontally opposed press. As a result, the following findings (A) to (E) were obtained.

(A) When the width of the slab is reduced, the die for the horizontally opposed press is formed into a box-hole shape, and the hole-shaped shape is defined by the width B of the hole bottom in relation to the slab to be subjected to the width reduction. (Mm) is given by ｛initial slab thickness T0
(Mm) -20mm} to {First slab thickness T0 (m
m) +100 mm}, and the depth is equal to or less than 1/3 of the width of the slab after the predetermined width reduction, that is, {the initial slab width W0 (mm) -the slab width reduction amount D (mm)}. 1 /
When the thickness is set to 3 or less and the side surface taper angle θ (゜) is set to 10 ° or less, it is possible to suppress the occurrence of dog bone in which only the thickness of the slab side end increases when the slab width is reduced. That is,
When the slab is reduced in width by the above-described box-hole type mold, the slab is strongly constrained by the mold, and the reduced meat (material) moves to the center in the slab width direction. For this reason, the thickness of the slab is increased in the entire width direction, and the occurrence of dog bone in which only the thickness of the slab side end is increased is suppressed.

(B) The occurrence of dog bone is suppressed in the slab which has been reduced in width by the horizontal facing press having the mold described in (A). For this reason, the amount of width return when the thickness of the slab after the width reduction is reduced by the rolling mill group (tandem mill group) provided at the subsequent stage of the horizontal facing press becomes substantially equal over the entire length of the metal plate. Therefore, when the slab thickness is reduced by the rolling mill group, it is not necessary to greatly reduce the width by the edger mill.

(C) When the width is reduced by a horizontal facing press having the mold described in (A) above, the slab corners are chamfered simultaneously. The generation of linear surface flaws at the rolled metal plate side end can be prevented.

(D) When the width of the slab is reduced, the die for the horizontally opposed press is formed into a box-hole shape, and the hole-shaped shape is defined as the width B of the hole bottom in relation to the slab to be subjected to the width reduction. (Mm) is given by ｛initial slab thickness T0
(Mm) -20mm} to {First slab thickness T0 (m
m) +100 mm}, and the depth is equal to or less than 1/3 of the width of the slab after the predetermined width reduction, that is, {the initial slab width W0 (mm) -the slab width reduction amount D (mm)}. 1 /
3 or less, furthermore, if the side taper angle θ (゜) is 10 ° or less and an appropriate projection is provided at the center of the bottom of the hole mold, only the thickness of the slab side end increases when the slab width is reduced. It can suppress the occurrence of dog bones and prevent the occurrence of linear surface flaws, and also cuts off the end of the product metal plate side (trim allowance) to remove seam flaws and breakage flaws generated at the side end of the metal plate. Can be reduced.

(E) At least the tapered portion which becomes the side surface of the hole of the box-hole-shaped mold described in (A) and (D) above has a melting point higher than that of the base material of the slab for hot rolling. It is formed by building up with a high material, and if the building-up portion has a hardness of 80 or more in Shore hardness, the distance between the mold and the slab when the slab width is greatly reduced. Seizure can be prevented from occurring.

The present invention has been completed based on the above findings (A) to (E).

Hereinafter, the reasons for limiting the requirements of the present invention will be described.

(A) Hole-Shape Shape The hole-shape is a box hole for moving the meat (material) to the center in the width direction of the slab by strongly restraining the hot-rolling slab to be subjected to the width reduction with a mold. Must be a type. In order to increase the thickness of the slab whose width has been reduced in the entire width direction and prevent dog bone deformation in which only the thickness of the slab side end increases, the specific shapes of the hole types are as follows (a-1) to (a). a-3)
Needs to be determined.

FIG. 1 is a cross-sectional view showing one example of the shape of one side of a die for a width reduction press of a slab for hot rolling according to the present invention. Hereinafter, the specific shape of the hole type will be described with reference to FIG.

(A-1) Bottom width of hole type: B (mm) The bottom width (width of hole bottom) B (mm) of the hole type must satisfy the above expression. If the bottom width B (mm) of the hole mold is smaller than {the initial slab thickness T0 (mm) -20 mm}, the amount of reduction in the slab corner becomes large, and the gap between the mold and the slab corner is increased. Tends to cause seizure. Further, fold flaws are also likely to occur. On the other hand, if the bottom width of the hole mold is larger than {the initial slab thickness T0 (mm) +100 mm}, it becomes difficult to restrain the slab in the thickness direction (vertical direction). Therefore, the bottom width B of the hole type
(Mm) was defined to satisfy the above equation.

(A-2) Depth of the hole mold: H (mm) The depth of the hole mold (hole depth) H (mm) is 1/3 or less of the width of the slab after the predetermined width reduction. That is, 1/3 of {initial slab width W0 (mm) -slab width reduction D (mm)}.
The following values must be used. If the depth of the hole mold exceeds one third of the width of the slab after the predetermined width reduction, the strength of the mold, particularly the strength of the corner of the mold, decreases, and the mold is damaged from the corner. It will be easier. On the other hand, the depth H (m
If m) is 0, it becomes a flat mold. Therefore, the depth H (mm) of the hole mold is defined so as to satisfy the above equation.
Incidentally, the upper limit of the depth H (mm) of the hole mold is preferably about 150 mm from the viewpoint of securing the strength of the mold, and the lower limit is preferably about 50 mm from the viewpoint of preventing the slab from biting out.

Since the reduction of the width exceeding 600 mm requires an extremely large horizontal facing press machine, the width reduction D (mm) of the slab is preferably set to 600 mm or less.

(A-3) Side taper angle of hole type: θ
(゜) The side surface taper angle θ (゜) of the hole type refers to the angle θ shown in FIG. 1, and this value needs to be 10 ° or less. If the side surface taper angle of the hole mold exceeds 10 °, the slab cannot be restrained in the thickness direction. On the other hand, when the side surface taper angle θ (゜) of the hole type is 0 ° or less, the width reduction of the slab cannot be substantially performed by the horizontally opposed press, and even if the width reduction can be performed, the slab corner is reduced. Chamfering of the part cannot be performed. Therefore, the side surface taper angle θ (゜) of the hole type is defined so as to satisfy the above expression. The lower limit of the side surface taper angle θ (゜) of the hole mold is set to about 5 ° in order to prevent seizure between the mold side surface and the slab and further prevent the slab from biting out. Is preferred.

(B) Projection at the bottom of the hole mold: A projection is provided at the center of the bottom of the hole mold having the shape shown in (a), and the width of the slab is reduced by a horizontal facing press having the mold. In addition to preventing the occurrence of dog bone and the occurrence of linear surface flaws, which increase only the thickness of the slab side end when the slab width is reduced, the removal of seam flaws and breakage flaws generated at the side end of the metal plate. In this case, the cut-off amount (trim allowance) at the end of the product metal plate can be reduced. Therefore, a projection may be provided at the center of the bottom of the hole having the shape of (a). The shape of the projection is preferably an arc having a height of 20 mm or less.

(C) Overlay on the hole mold: At least the tapered portion on the side surface of the hole of the box-hole mold described in the above (a) and (b) is subjected to a melting point reduction in width. It is formed by building up with a material higher than the melting point of the base material of the slab for hot rolling, and if the building-up portion has a hardness of 80 or more in Shore hardness, the slab width is reduced. It is possible to prevent the occurrence of seizure between the mold and the slab when a large reduction is made. If the melting point of the material to be built is lower than the melting point of the base material of the slab, seizure between the mold and the slab is likely to occur. Further, when the Shore hardness is less than 80, the amount of wear of the mold increases. Therefore, when seizure between the mold and the slab and wear of the mold become a major problem, at least the tapered portion serving as the side surface of the hole has a melting point that is lower than the melting point of the base material of the target slab under the width pressure. Alternatively, the above-mentioned box-hole-shaped mold may be used, which is formed by building up with a high material, and the building-up portion has a hardness of 80 or more in Shore hardness.

The upper limit of the Shore hardness of the overlaid portion is about 100. For the material to be built up, for example, by weight%, Cr: 25 to 32%, W: 4 to 25%, C: 1 to
3%, balance: stellite-based alloy with chemical composition of Co and unavoidable impurities, W carbide, Nb carbide, Mo
Carbide may be used. The overlaying method may be performed by a normal method such as a plasma arc method. It is preferable that the thickness of the overlay be 2 to 5 mm.

The width reduction press die of the slab for hot rolling according to the present invention is similar to the die for width reduction press of the slab for hot rolling, for example, for a hot die such as JIS SKD61. Steel is used as the base material. After smelting such a base material by a normal method, the steel slab is hot forged, and further subjected to a heat treatment such as annealing and quenching and tempering, using a steel material adjusted to a desired hardness and toughness, and using a normal steel material. The dies for hot-rolling slabs according to the present invention can be obtained by working by a method and further building up a stellite-based alloy or the like by an ordinary method as necessary.

(D) Width reduction method: When the slab is reduced in width by the box-hole-shaped mold described above, the slab is strongly restrained by the mold. Move to the center in the slab width direction. For this reason, the thickness of the slab is increased in the entire width direction, and the occurrence of dog bone in which only the thickness of the slab side end is increased is suppressed. Therefore, the width reduction method of the slab for hot rolling according to the present invention is to reduce the width of the slab such as stainless steel, low alloy steel and titanium continuously cast by a usual method to the width reduction press metal described above. It is only necessary to use a horizontally opposed press equipped with a mold to reduce the pressure in a usual manner.

Hereinafter, almost 1/5 of the case where the actual equipment is used.
The present invention will be described more specifically based on the results of width reduction and hot rolling of stainless steel and carbon steel slabs under conditions equivalent to the reduction experiment.

First, the thickness T0 is 40 mm and the width W0 is 150
mm, length 300mm stainless steel (JIS SUS4
30) and a continuous casting slab having carbon steel (JIS SM490A) as a base material is heated to 1200 ° C., and then a horizontally opposed press having a box-hole type mold according to the present invention or a normal flat mold is provided. The width of the slab is reduced by D = 60 mm with a horizontally opposed press, and the thickness of the slab side end and the thickness of the slab in the center in the width direction in the same cross section in the length direction are appropriately measured to determine the slab length direction. The occurrence of dog bones was investigated. JIS SKD61 was used as the base material of the mold. The width reduction of D = 60 mm corresponds to the width reduction of D = 300 mm in the actual machine.

Next, D = 60 mm using a horizontally opposed press.
After the slab reduced in width was reheated to 1000 ° C., rolling was performed using a double-type reverse rolling mill under a thickness reduction equivalent to rough row tandem rolling of an actual machine including six stands. That is, after the thickness is 33 mm in the first pass,
Hot rolling was performed on a pass schedule of 22 mm → 15 mm → 10 mm → 7 mm → 5 mm. This rolling corresponds to actual rolling when rough rolling is performed without using an edger mill. After finishing the rolling, the width of the steel plate was measured in the length direction. The material of the roll used in the above-mentioned reverse rolling mill is S50C, and its diameter is 250 mm.

FIG. 1 shows a cross-sectional shape of a die for a width reduction press of a slab for hot rolling according to the present invention. Specifically, the bottom width (width of the bottom of the hole) B (mm) of the hole mold is 40 m, which is equal to the initial thickness T0 of the target slab under the width reduction.
m, the depth H (mm) of the hole mold is 50 mm, and the side surface taper angle θ (゜) of the hole mold is 5 °.

FIG. 2 shows the result of measuring the thickness of the slab side end in the slab length direction when the width of the slab having SUS430 as the base material was reduced by D = 60 mm. The thickness of the slab at the center in the width direction was all 40 mm in the length direction.

FIG. 2 shows that when the width of the slab is reduced by D = 60 mm by a horizontally opposed press having a flat mold, the thickness of the slab side end at the leading end and the rear end of the slab and the thickness of the slab in the width direction central portion are reduced. It can be seen that a difference of 8 mm occurs between the difference between the thickness of the slab at the center in the length direction and the thickness of the slab at the center in the width direction. On the other hand, when the width of the slab is reduced by D = 60 mm using a horizontally opposed press having the mold according to the present invention shown in FIG. The difference between the thickness in the width direction center portion and the difference between the thickness of the slab side end portion in the center portion in the length direction and the thickness in the width direction center portion of the slab is equal to 2 mm, and the flat mold is inserted. 1/4 of the case of using a horizontally opposed press.

From the above results, it is clear that the generation of dog bone can be suppressed by reducing the width with a press having the mold according to the present invention.

FIG. 3 shows the result of measuring the thickness of the slab side end in the length direction of the slab when the width of the slab using SM490A as a base material is reduced by D = 60 mm. The thickness of the slab at the center in the width direction was all 40 mm in the length direction.

From FIG. 3, when the width is reduced by D = 60 mm with a horizontally opposed press having a flat mold, the thickness of the slab side end at the front end and the rear end of the slab and the thickness of the slab in the width direction center are obtained. It can be seen that a difference of 6 mm occurs between the difference between the thickness of the slab at the center in the length direction and the thickness of the slab at the center in the width direction. On the other hand, when the width of the slab is reduced by D = 60 mm using a horizontally opposed press having the mold according to the present invention shown in FIG. The difference between the thickness in the width direction center portion and the difference between the thickness of the slab side end portion in the center portion in the length direction and the thickness in the width direction center portion of the slab is equal to 2 mm, and the flat mold is inserted. 1/3 of the case of using a horizontally opposed press.

From the above results, it is clear that the generation of dog bone can be suppressed if the width is reduced by the press having the mold according to the present invention.

FIG. 4 shows the results of measuring the width of a steel sheet whose thickness was reduced to 5 mm from a slab whose base material is SUS430 and whose width was reduced to 5 mm.

In a horizontally opposed press having a flat mold, D =
When the slab reduced by 60 mm was rolled to a thickness of 5 mm, the difference in the width of the steel sheet between the front and rear ends of the steel sheet and the center in the length direction was 10 mm. On the contrary,
When a slab reduced by D = 60 mm in width is rolled to a thickness of 5 mm by a horizontally opposed press having the mold according to the present invention in FIG. 1, the leading end and the trailing end of the steel sheet and the central part in the length direction are removed. Was only 3 mm in width.

From the above results, in the case of a slab in which the generation of dog bones was suppressed by reducing the width by the press having the mold according to the present invention, when the steel sheet was finished by reducing the thickness,
It was confirmed that the variation in the width of the sheet due to the difference in width return was extremely small.

FIG. 5 shows the result of measuring the width of a steel sheet whose thickness was reduced to 5 mm from a slab whose base material was SM490A and whose width was reduced in the longitudinal direction.

In a horizontally opposed press having a flat mold, D =
When the slab reduced by 60 mm in width was rolled to a thickness of 5 mm, the difference in the width of the steel sheet between the front and rear ends of the steel sheet and the center in the length direction was 9 mm. On the other hand, a horizontally opposed press having the mold according to the present invention shown in FIG.
= When the slab reduced by 60 mm width was rolled to a thickness of 5 mm, the difference in width of the steel sheet between the front and rear ends of the steel sheet and the center in the length direction was only 2 mm.

From the above results, it can be seen that in the case of a slab in which the generation of dog bone was suppressed by reducing the width by the press having the mold according to the present invention, when the steel sheet was finished by reducing the thickness, the width of the width returned was reduced. It was confirmed that the plate width fluctuation based on the difference was extremely small.

Next, using two types of molds having a base material of S50C and a box hole shape according to the present invention, a thickness T0
After heating a continuous cast slab having a base material of carbon steel (JIS SM490A) having a length of 40 mm, a width W0 of 150 mm and a length of 300 mm to 1000 ° C., the width of the slab is reduced by D = 60 mm by a horizontal facing press. The occurrence of seizure between the mold and the slab was investigated. One of the above two molds
One is a mold all formed by S50C. The hardness of the side surface of this mold was 60 in Shore hardness. Another mold is a stellite-based alloy in which a tapered portion serving as a side surface of a hole is built up by a normal plasma arc method (chemical composition is Cr: 28%, W: 11%, C: 1.
5%, balance: Co and inevitable impurities). The thickness of the build-up of the tapered portion on the side surface of the hole was 2 mm, and the hardness of the build-up portion was a mold having a Shore hardness of 85.

The width of the 50 slabs was continuously reduced by using a mold in which the tapered portions on the side surfaces of the holes were overlaid, but seizure occurred between the mold and the slab. I was not able to admit. On the other hand, in the case of using a mold entirely formed of S50C, seizure occurred between the tapered portion on the side surface of the mold and the slab in the third sheet. As a result,
When the seizure between the mold and the slab is a problem, at least the tapered portion serving as the side surface of the hole is overlaid with a material whose melting point is higher than the melting point of the base material of the target slab under the width reduction. It has been confirmed that it is preferable to use the box-hole-shaped mold having a build-up portion having a hardness of 80 or more in Shore hardness.

Hereinafter, the present invention will be described in more detail based on an example in which a steel sheet is manufactured by performing width reduction and hot rolling of a slab in an actual machine.

[0073]

【Example】

(Embodiment 1) FIG. 6 is a schematic explanatory view showing a part of a mill layout used in this embodiment. The continuous cast slab to be hot-rolled is heated in a heating furnace H1 and then pressed horizontally.
The width is reduced by SP, then the rough rolling mill of R1 ~ R6 and E1 ~
The coarse row tandem mill group consisting of the E5 edger mill reduces the thickness and the width. Next, after the rolled crop is cut by the shear S2, it is finish-rolled by a finishing mill group to obtain a steel sheet having a desired thickness. In the case of manufacturing a stainless steel sheet in which the occurrence of linear flaws and seam flaws is a problem, no width reduction is performed by an edger mill during rough rolling.

The thickness T0 (mm) is 250 mm and the width W0 (m
m) is 1500 mm and the length is 10 m.
490A) is heated to 1250 ° C., and then the horizontal facing press SP having a box-hole-shaped mold according to the present invention or the horizontal facing press SP having a normal flat mold is used. After reducing the width of the slab by D = 340 mm, and further reducing the thickness to 200 mm by R1 mill, 160
The hot rough rolling in the R1 to R6 mills was performed in a pass schedule of mm → 120 mm → 95 mm → 70 mm → 65 mm. In addition, width rolling was also performed with the edger mills E1 to E5. The pass schedule is 1160mm → 1162mm → 1
165 mm → 1165 mm → 1165 mm. Measure the thickness of the slab side end and the thickness of the slab at the center in the same cross section in the length direction while reducing the width with the horizontal facing press SP to generate dog bone in the slab length direction. We also investigated the situation. The base material of the mold provided in the horizontal facing press SP is JIS SKD.
61.

FIG. 1 shows a cross-sectional shape of a mold for width reduction press of a slab for hot rolling according to the present invention. Specifically, the bottom width (hole bottom width) B (mm) of the hole mold is 250 m, which is equal to the initial thickness T0 of the target slab under the width reduction.
m, the depth H (mm) of the hole mold is 300 mm, and the side surface taper angle θ (゜) of the hole mold is 5 °. In addition, the inner surface of the hole type is a stellite-based alloy which has been overlaid by a normal plasma arc method (chemical composition is weight%, Cr: 28%,
W: 9%, C: 1.4%, balance: Co and inevitable impurities). The thickness of the build-up is 3 mm at the bottom of the hole, and 5 mm at the taper on the side surface of the hole. The hardness of the overlaid portion was 82 in Shore hardness.

When the slab is reduced by D = 340 mm in width by a horizontally opposed press having a flat mold, the thickness of the slab side end at the leading end and the rear end of the slab is 250 mm, which is equal to the initial thickness T0 of the slab. As it was, the thickness of the slab-side end at the center in the length direction was 300 mm. The thickness of the slab at the center in the width direction was all 250 mm in the length direction.
Therefore, in a horizontally opposed press having a flat mold, D =
When the width of the slab is reduced by 340 mm, the difference between the thickness of the slab side end at the front end and the rear end of the slab and the thickness of the slab at the center in the width direction, and the thickness of the slab side end at the center in the length direction and the slab The difference between the width and the center thickness is 50
mm difference occurred.

On the other hand, the slab was D = 340 mm by a horizontally opposed press having the mold according to the present invention.
When the width is reduced, the meat (material) moves to the center of the slab width, so that the deformation mode is close to single bulging. For this reason, the thickness of the slab-side end at the center in the length direction where the thickness of the slab-side end is maximized is also 320 mm, while the thickness of the slab-side end at the leading end and the rear end of the slab is 310 mm. Met. The thickness of the slab at the center in the width direction was all 250 mm in the length direction. In other words, D is applied by a horizontally opposed press having the mold according to the present invention.
= 340 mm width reduced, the difference between the thickness of the slab side end at the leading end and the rear end of the slab and the thickness in the center in the width direction of the slab, and the thickness of the slab side end at the center in the length direction and the slab The difference from the thickness at the center in the width direction was reduced to 10 mm, and was 1/5 of that when a horizontally opposed press having the flat mold was used.

From the above results, it is clear that the generation of dog bone can be suppressed by reducing the width in the press having the mold according to the present invention.

After the slab whose width was reduced by a horizontally opposed press having a flat mold was roughly rolled under the above-described conditions, a crop of 500 mm at the front end and 500 mm at the rear end was sheared off, and a finishing mill group was cut by an ordinary method. The steel plate finished and rolled to a thickness of 3 mm at the front and rear ends has a length of 30 mm each.
The width of the steel plate was insufficient over m, and this portion had to be cut off. On the other hand, after the slab whose width has been reduced by the horizontally opposed press having the mold according to the present invention is roughly rolled under the above-described conditions, the leading end 100 mm, the trailing end 100 m
m in a steel sheet which has been shear-cut with a finishing mill group and finished rolled to a thickness of 3 mm in a usual manner, despite the short crop cutting length as described above, the steel sheet width is insufficient. The portion had a length of only 5 m at the front end and the rear end, respectively, and the cut-off amount of the steel plate could be reduced.

(Embodiment 2) FIG. 7 is a schematic explanatory view showing a part of a mill layout used in this embodiment. The continuous cast slab to be hot-rolled is cut to a predetermined length by a gas torch GT, reduced in width by a horizontally opposed press SP, then cut by a shear S1, and soaked in a heating furnace H1 of a rolling mill. After this, rough rolling by the usual method,
The steel plate having a desired thickness is obtained by subjecting the rolled crop to shear cutting and finish rolling. In the case of manufacturing a stainless steel sheet in which the generation of linear flaws and seam flaws is a problem, the width reduction by an edger mill is not performed during the above-described rough rolling.

The thickness T0 (mm) is 220 mm and the width W0 (m
m) A continuous cast slab whose base material is carbon steel (JISSM490A) having a length of 1400 mm
Cut to 0 m. Next, the width of the slab is set to D = 60 by a horizontally opposed press SP having a box-hole-shaped mold according to the present invention or a horizontally opposed press SP having a normal flat mold.
It was reduced by 0 mm. Thereafter, as shown in FIG. 8, the slab was divided into slabs having lengths of a, b, and c of about 10 m by the shear S1 from the front end. Next, the thickness of the slab side end and the thickness of the slab in the width direction central portion in the same cross section in the length direction of the slabs a and c were measured. The base material of the mold provided in the horizontal facing press SP is JIS SKD61.

The die for the width reduction press of the slab for hot rolling according to the present invention is the same as that used in the above-mentioned "(Example 1)", and the cross-sectional shape is shown in FIG. Specifically, the bottom width B (mm) of the die is 220 mm, and the depth H of the die is
(Mm) is 220 mm, hole type side taper angle θ
(゜) is a mold having a hole shape of 5 °. Also in the case of the present embodiment, the inner surface of the hole die of the width reduction press die of the slab for hot rolling according to the present invention has a stellite-based alloy (weight%
, Cr: 29%, W: 8%, C: 1.4%, balance: C
o and the chemical composition of unavoidable impurities). The thickness of the build-up is 3 mm at the bottom of the hole, and 5 mm at the taper on the side surface of the hole. The hardness of the overlay was 80 in Shore hardness.

When the slab is reduced by D = 600 mm in width by a horizontally opposed press having a flat mold, the thickness of the slab side end at the front end of the slab a and the slab side end at the rear end of the slab c. The thickness of each is 230mm,
On the other hand, the thickness of both ends of the slab a at the center in the length direction of the slabs a and c was 320 mm. The thickness of the slabs a and c at the center in the width direction was 220 mm in the length direction. Therefore, when the width of the slab a is reduced by D = 600 mm using a horizontally opposed press having a flat mold, the difference between the thickness of the slab side end portion at the tip end portion of the slab and the thickness of the slab in the width direction central portion is: There was a difference of 90 mm between the difference between the thickness of the slab side end at the center in the length direction and the thickness of the center in the width direction of the slab. Similarly, for the slab c, the difference between the thickness of the slab side end at the rear end of the slab and the thickness in the width direction center portion of the slab, and the thickness of the slab side end and the width of the slab at the center in the length direction. There was a difference of 90 mm between the difference from the thickness at the center in the direction.

On the other hand, the slab was D = 600 mm by a horizontally opposed press having the mold according to the present invention.
When the width is reduced, the thickness of the slab side end of the steady part where the thickness of the slab side end is maximized is 250 mm with respect to the slab a and the slab c as described above.
Both the slab a and the slab c selected the central part in the length direction). On the other hand, the thickness of the slab side end of the leading end of the slab a and the thickness of the slab side end of the rear end of the slab c are both the same. 2
It was 30 mm. The thickness of the slabs a and c at the center in the width direction was 220 mm in the length direction. In other words, when the width of the slab a is reduced by D = 600 mm with a horizontally opposed press having the mold according to the present invention, the thickness of the slab side end at the tip end of the slab and the thickness of the slab in the width direction center are measured. The difference between the thickness of the slab side end at the center in the length direction and the thickness of the center in the width direction of the slab was reduced to 20 mm. Similarly, for the slab c, the difference between the thickness of the slab side end at the rear end of the slab and the thickness in the width direction center portion of the slab, and the thickness of the slab side end and the width of the slab at the center in the length direction. The difference from the thickness at the center in the direction was reduced to 20 mm, and was 2/9 of the case where a horizontally opposed press having the flat mold was used.

From the above results, it is clear that the generation of dog bone can be suppressed by reducing the width with a press having the mold according to the present invention.

Next, the above-mentioned slabs a and c were charged into a heating furnace H1 of a rolling mill, soaked at 1250 ° C., further subjected to ordinary rough rolling, cutting of a rolled crop by a shear and ordinary finish rolling. Thus, a rolled steel sheet having a thickness of 5 mm was manufactured.

The slab a cut in width and sheared by a horizontal facing press having a flat mold is roughly rolled in a usual manner, and then a crop of 500 mm in the front end and 100 mm in the rear end is sheared off. In the steel sheet finished and rolled to a thickness of 5 mm by the finishing mill group, the steel sheet width was insufficient at the leading end and the trailing end over a length of 30 m and 5 mm, respectively, and this part had to be cut off.

Similarly, after the slab c cut in width and sheared by a horizontal facing press having a flat mold is roughly rolled by a usual method, a crop of 100 mm in the front end and 500 mm in the rear end is sheared. In the steel plate finished and rolled to a thickness of 5 mm by a finishing mill group in a usual manner, the leading end and the rear end have a shortage of the steel plate width of 5 m and 30 m, respectively, and this part must be cut off. Was.

On the other hand, after the slabs a and c, which have been reduced in width by a horizontal facing press having the mold according to the present invention and subjected to shear cutting, are roughly rolled by an ordinary method, the tip portion is 100 m long.
m, in a steel sheet which is cut by shearing a crop of 100 mm at the rear end and rolled to a thickness of 5 mm by a finishing mill group in a usual manner, despite the short crop cutting length as described above, the steel sheet width The portions lacking were only 5 m in length at the leading end and the trailing end, respectively, and the cut-off amount of the steel plate could be reduced.

(Embodiment 3) FIG. 9 is a schematic explanatory view showing a part of a mill layout used in this embodiment. The continuous cast slab to be hot-rolled is cut to a predetermined length by a gas torch GT, then reduced in width by a horizontally opposed press SP, and then by an HV (horizontal-vertical) type bulking mill BM. Both the width and the thickness are reduced to be processed into a rectangular cross section (that is, a shape without a dog bone), and further cut by the shear S1. After being sheared, the material to be treated (slab) is soaked in a heating furnace H1 on the line, and thereafter subjected to rough rolling, shear cutting of a rolled crop and finish rolling in a usual manner to obtain a desired thickness. Steel plate. In the case of manufacturing a stainless steel sheet in which the generation of linear flaws and seam flaws is a problem, the width reduction by an edger mill is not performed during the above-described rough rolling.

The thickness T0 (mm) is 250 mm and the width W0 (m
m) A continuous cast slab whose base material is carbon steel (JISSM490A) having a length of 1600 mm
Cut to 0 m. Next, the width of the slab is set to D = 60 by a horizontally opposed press SP having a box-hole-shaped mold according to the present invention or a horizontally opposed press SP having a normal flat mold.
It was reduced by 0 mm. Furthermore, reverse rolling was performed in an HV type lump mill BM in three passes, and the slab width was further reduced by 200 mm to 800 mm and the slab thickness was 220 m.
m, and then cut with a shear S1, then the cut slab is heated to 1200 ° C. in a heating furnace H1 provided on a production line, and further subjected to rough rolling by a normal method, cutting of a rolled crop with a shear, and Finish rolling was performed to produce a rolled steel sheet having a thickness of 5 mm. The base material of the mold provided in the horizontal facing press SP is JIS SKD61.

The die for the width reduction press of the slab for hot rolling according to the present invention is the same as that used in the above-mentioned "(Example 1)" and "(Example 2)". It is shown. Specifically, the bottom width B (mm) of the hole type is 25
The die has a hole shape of 0 mm, a depth H (mm) of the hole die of 150 mm, and a side surface taper angle of 5 °.
Also in the case of the present embodiment, the inner surface of the hole die of the width reduction press die of the hot rolling slab according to the present invention is a stellite-based alloy (by weight%) which is built up by a normal plasma arc method. , Cr: 29%, W: 8%, C: 1.4%,
(The remainder: chemical composition of Co and unavoidable impurities). The thickness of the build-up is 3 mm at the bottom of the hole, and 5 mm at the taper on the side surface of the hole. The hardness of the overlaid portion was 80 in Shore hardness.

When the slab is reduced by D = 600 mm in width by a horizontally opposed press having a flat mold, three passes of reverse rolling are performed by an HV type lumping mill BM to make the width 800 mm and the thickness 220 mm. In the slab obtained, it was necessary to cut off both the front end and the rear end by 500 mm in the next shear S1.

On the other hand, the slab was D = 600 mm by a horizontally opposed press having the above-described mold according to the present invention.
When the width is reduced, the generation of dog bones is suppressed when the width is reduced by the press.
In a slab having a width of 800 mm and a thickness of 220 mm by performing reverse rolling in 3 passes, it was sufficient to cut off both the leading end and the trailing end by 100 mm with the shear S1.

It should be noted that there was no difference in the amount of cut-off between the case where the slab was reduced in width by the flat mold and the case where the slab was reduced in width by the mold according to the present invention in the step after cutting with the shear S1.

(Embodiment 4) FIG. 10 is a schematic explanatory view showing a mill layout used in this embodiment. After the hot-rolled continuous cast slab is heated in the heating furnace H1, the width is reduced by the horizontally opposed press SP, and then the thickness is reduced by the reverse type rough rolling mill R, and then the F1-F6 Finish rolling is performed by a finishing mill group including a finish rolling mill and edger mills E1 to E5 to obtain a steel sheet having a desired thickness.

The thickness T0 (mm) is 200 mm and the width W0 (m
m) is 1200 mm stainless steel (JIS SUS43
The continuous casting slab having the base material 0) as a base material is 1200 in a heating furnace H1.
After heating to ° C., the width of the slab is reduced by D = 350 mm with a horizontally opposed press SP having a box-hole-shaped mold according to the present invention or a horizontally opposed press SP having a normal flat mold, and further, Seven passes of hot rolling were performed on a reverse type rough rolling mill R to a thickness of 30 mm. Horizontal facing press
Measure the thickness of the end of the slab side and the thickness of the central part in the width direction of the slab in the same cross section in the length direction while reducing the width by SP, and investigate the dog bone generation state in the slab length direction I also did things. The horizontal facing press
The base material of the mold provided on the SP is JIS SKD61.

FIG. 11 shows a cross-sectional shape of a die for a width reduction press of a slab for hot rolling according to the present invention used in the present embodiment. Specifically, the bottom width B (mm) of the hole mold is 195 mm,
The depth H (mm) of the die is 200 mm, the side taper angle of the die is 5 °, and the height is 1 at the center of the bottom of the die.
This mold has an arc-shaped projection having a width of 5 mm and a width of 90 mm, and the width of the hole at the tip of the projection is 200 mm. The inner surface of the hole is formed of Nb carbide which is built up by a normal plasma arc method. The thickness of the cladding is 2 mm at the bottom of the hole and 4 mm at the tapered portion on the side surface of the hole. The hardness of the overlaid portion was 83 in Shore hardness.

The projection at the center of the bottom of the hole mold is for forming the short side surface (side surface) of the slab into a concave shape. Accordingly, the position of the linear surface flaw is brought closer to the side end of the rolled material, and the trim margin required for removing the linear surface flaw is reduced.

When the slab thickness is reduced after forming the short side surface (side surface) of a slab made of stainless steel as a base material and then reduced by an edger for width adjustment at the time of rough rolling, the effect of the concave formed portion is obtained. Will be erased.

When the width of the slab is reduced by the horizontally opposed press provided with the mold according to the present invention, the slab is strongly restrained by the mold. While sufficient concave shaping is performed, the pressed down meat (material) moves to the center in the slab width direction. For this reason, the thickness of the slab is increased in the entire width direction, and the dog bone deformation in which only the thickness of the slab side end is increased is suppressed.
When the slab in which the occurrence of the dog bone is suppressed is reduced in the rolling mill group to reduce the thickness, the amount of width return caused by rolling becomes substantially equal over the entire length of the steel sheet.
In other words, when the width of the slab is reduced by the horizontally opposed press provided with the mold according to the present invention, it is not necessary to adjust the width by reducing the width of the slab with an edger mill when reducing the slab thickness. For this reason, the effect of the concave-shaped portion is not impaired, so that the problem of linear flaws and seam flaws can be solved.

When the slab is reduced by D = 350 mm in width by a horizontally opposed press having a flat mold, the thickness of the slab side end at the leading end and the rear end of the slab is 220 mm.
The thickness of the slab-side end at the center in the length direction was 310 mm. The thickness of the slab at the center in the width direction was all 200 mm in the length direction. Therefore, when the width of the slab is reduced by D = 350 mm with a horizontally opposed press having a flat mold, the difference between the thickness of the slab side end at the front end and the rear end of the slab and the thickness of the slab in the width direction center, and the length There was a difference of 90 mm between the difference between the thickness of the slab side end at the center in the width direction and the thickness of the center in the width direction of the slab.

On the other hand, the slab was D = 350 mm by a horizontally opposed press having the above-described mold according to the present invention.
When the width is reduced, the thickness of the slab side end at the center in the length direction where the thickness of the slab end is maximized is also 240 mm. The thickness was 220 mm. The thickness of the slab at the center in the width direction was all 200 mm in the length direction. That is, D = 350 m with a horizontally opposed press having a flat mold
When the width of the slab is reduced by m width, the difference between the thickness of the slab side end at the front end and the rear end of the slab and the thickness in the width direction central portion of the slab, and the thickness of the slab side end at the central portion in the length direction and the slab The difference with the width direction center part thickness is reduced to 20 mm,
The value was 2/9 when a horizontal facing press having the flat mold was used.

From the above results, it is clear that the generation of dog bone can be suppressed by reducing the width with a press having the mold according to the present invention.

After roughly rolling the slab whose width has been reduced by a horizontally opposed press having a flat mold under the above-described conditions, the steel sheet finished and rolled to a thickness of 5 mm by a finishing mill group in the usual manner has a tip portion and A shortage of the steel plate width occurred at the rear end over a length of 30 m, and this portion had to be cut off. On the other hand, after the slab of which width has been reduced by the horizontally opposed press having the mold according to the present invention is roughly rolled under the above-described conditions, and then finished and rolled to a thickness of 5 mm by a finishing mill group in a usual manner, The part where the width was insufficient had only a length of 5 m at the front end and the rear end, respectively, and the amount of steel plate cut off could be reduced.

Further, the state of occurrence of linear surface flaws, seam flaws and breakage flaws of a rolled steel sheet which was rolled to a thickness of 5 mm after rolling down the slab by the method of the present invention was investigated.
As a result, no linear surface flaw was observed at the end of the hot-rolled steel sheet having a thickness of 5 mm on the steel sheet side. The seam flaw width was 8 mm. Next, the seam flaw was trimmed, and the cross-sectional shape of the steel sheet was observed, but no fold flaw was recognized. Therefore, in the case of a 5 mm thick stainless steel plate manufactured by rolling after reducing the width of the slab according to the method of the present invention, a seam flaw of about 8 mm each side is required to make the product as hot rolled. It was confirmed that the yield was improved only by the amount of cut-off.

[0107]

According to the method of reducing the width of a slab for hot rolling of the present invention, the following effects can be obtained when a metal plate is manufactured from a continuously cast slab by hot rolling.

Since the occurrence of dog bones can be suppressed even when the slab width is greatly reduced, in a metal sheet whose slab thickness has been reduced by a rolling mill after the slab width has been reduced, the width variation due to the difference in width return is extremely small. it can.

It is possible to suppress the occurrence of linear surface flaws and seam flaws generated on the side edges of a metal plate, especially a stainless steel plate or a titanium plate, and it is possible to reduce the depth of the fold flaw. The amount of cut-off at the product plate side end required for removing seam flaws and fold flaws can be reduced.

When the slab width is reduced, seizure between the mold and the slab can be prevented.

Therefore, since the slab width can be consolidated and the slab casting width can be increased, the efficiency and capacity of continuous casting can be greatly improved, and the cost can be reduced.

The method for reducing the width of a slab for hot rolling of the present invention can be easily carried out by using a die for pressing a width of a slab for hot rolling according to the present invention.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a shape of a die for a width reduction press of a slab for hot rolling according to the present invention.

[Fig. 2] The width of a slab whose base material is JIS SUS430 is D
It is a figure which shows the result of having measured the thickness of the slab side edge part in the slab length direction at the time of = 60 mm reduction.

FIG. 3 shows the width of a slab made of JIS SM490A as a base material.
It is a figure which shows the result of having measured the thickness of the slab side edge part in the slab length direction at the time of = 60 mm reduction.

FIG. 4 shows a slab of FIG.
It is a figure which shows the result of having measured the width | variety of the steel plate which reduced thickness to m in the length direction.

FIG. 5 shows a slab of FIG. 3 having a base material of SM490A of 5 m.
It is a figure which shows the result of having measured the width | variety of the steel plate which reduced thickness to m in the length direction.

FIG. 6 is a schematic explanatory view showing a part of a mill layout used in (Example 1).

FIG. 7 is a schematic explanatory view showing a part of a mill layout used in (Example 2).

FIG. 8 is a view showing a state in which the width of the slab is reduced by a horizontally opposed press and then cut by a shear in (Example 2).

FIG. 9 is a schematic explanatory view showing a part of a mill layout used in (Example 3).

FIG. 10 is a schematic explanatory view of a mill layout used in (Example 4).

FIG. 11 is a cross-sectional view showing a shape of a die for a width reduction press of a slab for hot rolling according to the present invention used in (Example 4).

FIG. 12 is an explanatory diagram of linear surface flaws and seam flaws generated on a hot-rolled metal plate.

FIG. 13 is a cross-sectional view showing an example of a slab shape in which a trapezoidal split is formed on a side surface of the slab according to the related art.

FIG. 14 is a diagram showing an example of a state of occurrence of a flaw at a side end portion of a metal plate which is hot-rolled after a trapezoidal split is formed on a side surface of a slab according to a conventional technique and then reduced in width.

FIG. 15 is a view showing another example of the state of occurrence of flaws at the side end portions of a metal plate that has been subjected to a trapezoidal split on the side surface of a slab and then subjected to a width reduction and then hot-rolled according to a conventional technique.

[Explanation of symbols]

 T: slab thickness (mm), W: slab width (mm), D: width reduction of slab (mm), B: bottom width of hole mold (mm), H: depth of hole mold (mm), θ: Side taper angle of hole type (穴), SP: Horizontal facing press, H1: Heating furnace, S1, S2: Shear, GT: Gas torch BM: Blasting mill R1, R2, R3, R4, R5, R6, R: Rough rolling mill

Claims (4)

[Claims] 1. A box-hole-shaped die for a horizontally opposed press for reducing the width of a slab for hot rolling, wherein a bottom width Bmm, a depth Hmm and a side taper angle θ ゜ of the hole die are set. A die for a width reduction press of a slab for hot rolling, characterized by satisfying the following expressions. (T0-20) ≦ B ≦ (T0 + 100)... 0 <H ≦ (W0−D) / 3... 0 ゜ <θ ≦ 10 ゜... Where T0 is hot Initial thickness of rolling slab (mm),
W0 is the initial width (mm) of the slab, and D is the width reduction (mm) of the slab. 2. The die according to claim 1, further comprising an arc-shaped projection having a height of not more than 20 mm at the center of the bottom of the hole die. 3. A tapered portion which is at least a side surface of the hole,
The melting point is formed by building up with a material higher than the melting point of the base material of the hot-rolling slab, and the building-up portion has a Shore hardness of 80 or more. The die for width reduction press of a slab for hot rolling according to claim 1 or 2. 4. The width of a slab for hot rolling is reduced by using a horizontally opposed press equipped with a die for a width reduction press of a slab for hot rolling according to any one of claims 1 to 3. Width reduction method for hot rolling slabs.