JP2000000640A - Twin-roll continuous casting equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent penetration of molten metal by forming a pair of side gates of a self sliding material splitting, the side gates to right and left ones at the casting line, providing a pressing means to independently press aside a bottom part of the split side gates and a roll to reduce a gap between the side gates and the roll. SOLUTION: A continuous casting equipment directly manufactures a metallic sheet by passing a molten metal in a gap between rolls. Split side gates are split into two or more parts in a direction orthogonal to the casting direction, and each part is independently and movably mounted in the axial direction of the rolls. A self sliding material is preferably graphite. After bottom part of the side gates 10 is machined to the same curvature as that of a circumferential surface of rolls 1a, 1b, and split in right and left parts relative to the casting line, and further split into two. Split side gates 10a, 10b, 10c, 10d are mounted on a side gate support body 7, and a roll circumferential surface is independently pressed by springs 8a, 8b, 8c, 8d and holding plates 9a, 9b, 9c and 9d. The side gates are prevented from being broken, and the wear is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twin-roll continuous casting apparatus for producing a thin metal sheet directly from molten metal, and more particularly to a side weir of a twin-roll continuous casting apparatus.

[0002]

2. Description of the Related Art Thin metal sheets have been conventionally produced by subjecting a cast metal slab to a process such as hot rolling or cold rolling. However, according to this normal method, a number of processes such as a hot rolling process, a cold rolling process, and a heat treatment process performed between those processes are required, and accordingly, it is required to prepare various types of equipment. .

Therefore, recently, as a technique for easily producing a metal sheet without requiring many steps and various kinds of facilities, a method of directly cooling and solidifying a molten metal into a sheet-like slab is known. was suggested. As one of the methods, there is a method using a twin-roll continuous casting apparatus using a pair of water-cooled rolls. In this apparatus, a molten metal pool is formed between a pair of water-cooled rolls disposed in parallel to each other and supplied with molten metal, and the molten metal is contacted with the water-cooled rolls to cool and solidify. This is an apparatus for continuously casting a metal sheet while rolling the shell by a pair of water-cooled rolls.

In such a twin-roll continuous casting apparatus, in order to prevent the molten metal from leaking in the axial direction of the water-cooled roll,
Usually, a member called a side weir is used. The side weir is of a type that is pressed against the end surface of a rotating water-cooled roll (see FIG. 3) and a type that is installed on the roll peripheral surface (see FIG.
See). The side weir that presses against the end surface of a rotating water-cooled roll is a type of side weir that is installed on the roll peripheral surface where the width of the sheet is easy to change because the width of the cast metal sheet is determined by the width of the roll. Weirs are considered more advantageous in terms of productivity.

[0005] A problem in using the side weir of the type installed on the roll peripheral surface is the insertion (melting) of molten metal into a gap formed between the bottom of the side weir and the roll. is there. When the molten metal inserted into the gap between the side weir and the roll is solidified in place and the solidified metal bites between the roll and the bottom of the side weir, a surface crack occurs at the end of the sheet metal. The occurrence of surface cracks at the ends of the thin metal sheet is caused by the fact that the moving speed of the end of the thin metal sheet below the roll at the biting portion of the solidified metal is reduced by friction with the side weirs at other portions (for example, the metal being cast). (Central portion of the thin plate), and is caused by the generation of tensile stress at the end of the thin metal plate at the biting portion of the solidified metal. The surface cracks at the ends of the sheet metal not only remarkably reduce the quality of the sheet metal, but also, in extreme cases, cause the sheet metal to break and the operation must be stopped. In addition, since the jug damages the side weirs and rolls, there is a problem that the frequency of replacement of the side weirs and rolls is increased and the productivity is reduced.

[0006] As described above, the sprinkling of the gap formed between the bottom of the side weir and the roll not only significantly lowers the quality of the slab, but also causes a reduction in productivity. In order to prevent such a jug, it is important that there is no gap formed between the roll and the bottom of the side weir. For this reason, the processing accuracy of the bottom of the side weir has been improved. However, the peripheral surface of the roll and the bottom of the side weir may not be in close contact with each other due to abrasion of the side weir during operation or thermal expansion of the roll.

[0007] To improve this problem, proposals have been made regarding improvement of a side weir used in a twin-roll continuous casting apparatus. For example, JP-A-5-69096 discloses that
It is described that a gas or cooling liquid is injected into a gap between the side weir and the roll to prevent molten metal from leaking from the gap between the side weir and the roll. A side weir is a type of a side weir that is pressed against an end face of a rotating water-cooled roll. It is described that when the water-cooled roll is energized, the molten metal is energized and electromagnetic force prevents leakage of the molten metal from the roll end face.

[0008]

However, these methods require new devices, and furthermore, the side weir incorporating these devices has a complicated structure, and the workability and maintainability of the twin-roll continuous casting device are increased. Is reduced. Further, there is a case where it is not possible to prevent a hot water from flowing into a gap formed between the bottom of the side weir and the roll. For example, if the magnitude of thermal expansion of the rolls differs between the two rolls, the side roll is lifted by the roll with the larger thermal expansion, and a gap is formed between the roll and the other roll with the lower thermal expansion. For this reason, there arises a problem that it is not possible to prevent hot water from entering a gap formed between the bottom of the side weir and the roll.

In addition, in the conventional side weir, when the solidified shell formed on each roll peripheral surface is pressed in the vicinity of the roll kiss point (the portion where the distance between the pair of rolls is the minimum) is pressed. The unsolidified molten metal extruded in the axial direction solidifies at the widthwise end of the sheet metal, casting occurs, and this casting wears the side dam and further damages the side dam. There is a problem to do. And
Damage to the side weirs can cause serious disasters such as molten metal leaks and resulting steam explosions.

According to the present invention, in a twin-roll continuous casting apparatus, a simple device is provided on a side weir to prevent a hot run between the bottom of the side weir and the peripheral surface of the roll, thereby improving the quality and quality of the metal sheet. It is an object of the present invention to provide a twin-roll continuous casting apparatus capable of improving productivity and preventing breakage of a side weir due to casting at an end of a thin metal plate.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a method for melting a molten metal pool formed by a pair of rolls and a pair of side weirs provided between the pair of rolls. In a twin-roll continuous casting apparatus for supplying a metal and passing the molten metal through a gap between the pair of rolls to directly manufacture a thin metal sheet from the molten metal, the pair of side weirs is made of a self-sliding material. And these side weirs are divided right and left (in the direction perpendicular to the casting direction) in the casting line, and furthermore, a pressing means for independently pressing the bottom of these divided side weirs and the roll is provided. It is characterized by having. The self-slidable material is a material that self-corrects to a shape along the shape of a mating material that slides due to wear or the like during sliding, and the mating material on which the wear powder or the material itself slides. Is a material having a lubricating action between That is, the self-sliding material is a material that is softer than the sliding partner and has a lubricating action. The self-sliding material needs to have heat resistance because it handles molten metal. As the self-slidable material that can be used in the present invention, graphite, boron nitride, or the like can be used, and graphite is particularly preferable. This is because graphite is a self-slidable material that is excellent in heat resistance and workability, has high strength at high temperatures, and is relatively inexpensive.

A pair of side weirs is made of a self-sliding material and is divided into right and left (in a direction perpendicular to the casting direction) in a casting line, and is independently pressed against a roll by a pressing means. As the roll rotates, the bottom of the weir is polished by friction with the roll peripheral surface, and has the same curvature as the roll curved surface. Therefore, each part of the divided side weir and the roll peripheral surface are always in close contact with each other, and it is possible to prevent the occurrence of a gap between the side weir and the roll, which may cause hot water.

Further, the side weir is divided into right and left parts in the casting line, and is independently pressed against the rolls by a pressing means. Even if the curvature of the peripheral surface of the roll is shifted, the bottom of the side weir is polished in a shorter time than the side weir formed of an integral body, and the adhesion to the roll can be restored. At this time, it is preferable that the divided side weir is further divided into two or more in a direction perpendicular to the casting direction and pressed against the roll by a pressing means. The deviation between the curvature of the roll peripheral surface due to the thermal expansion of the roll and the bottom of each of the divided side weirs can be restored in a shorter time to the close contact with the roll. At this time, an appropriate number of divisions of two or more can be selected in consideration of the roll diameter, the material and thickness of the side weir, and the like.

In addition, it is preferable that each of the divided side weirs of the twin-roll continuous casting apparatus of the present invention is independently movably mounted in the roll axis direction. Since each part of each divided side weir is independently movably mounted in the axial direction of the roll, for example, the unsolidified layer is squeezed out in the direction of the metal sheet and solidifies (casting) at the end of the sheet. Even before the side weir breaks, the side weir moves in the roll axis width direction, so that damage to the side weir can be prevented. Further, since the side weir is movable in the roll axis width direction, the stress on the side weir due to the occurrence of casting is reduced, and the wear amount of the side weir can be reduced.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a mechanism for pressing a side weir onto a roll peripheral surface. FIG. 2 shows a mechanism for attaching the side weir in the roll axis direction (the structure of the side weir shown in FIG. 1). FIG. 4 is a schematic diagram showing a twin-roll continuous casting apparatus of a type in which a side weir is pressed onto a roll peripheral surface.

First, a twin-roll continuous casting apparatus of the present invention will be described. The twin-roll continuous casting apparatus of the present invention is a twin-roll continuous casting apparatus using a side weir installed on the roll peripheral surface shown in FIG. 4, and has a structure in which two internal water-cooled rolls are horizontally arranged. is there. As shown in FIG. 1, the side weir used in the twin-roll type continuous casting apparatus of the present invention is formed by processing the bottom of the side weir 10 to have the same curvature as the peripheral surfaces of the rolls 1a and 1b, and then forming the right and left ( (In the direction perpendicular to the casting direction), and each of the divided side weirs is further divided into two in the direction perpendicular to the casting direction. Each part 10a of these divided side weirs,
10b, 10c, and 10d are side weir supports 7 attached to a frame of a twin-roll continuous casting apparatus (not shown).
Attached to. At this time, each part 10a, 10b, 10c, 10d of the divided side weir is provided with a spring 8a, 8b,
8c, 8d and side dam retaining plates 9a, 9b, 9c, 9d attached below these springs are configured to independently press the peripheral surfaces of the rolls 1a, 1b.

Next, the mounting mechanism of the side weir 10 in the roll axis direction according to the embodiment of the present invention will be described with reference to FIG. The divided side weir 10 b is pressed against the side weir support 18 by a spring stand to which a pressing force is applied by a spring 12. The pressing force of the spring 12 is adjusted by tightening the bolt 11. This bolt 11 is used for the washer 1
4, through the spring 12, and the spring base 13,
The structure is connected to the nut 14 of the side weir support 18 through the through hole 16 of the divided side weir 10 b and the through hole 17 of the side weir support 18. The other divided side weirs 10 a, 10 c, and 10 d are similarly configured to be pressed against the side weir support 7.

An embodiment in which a stainless steel thin plate is manufactured directly from molten stainless steel using the twin-roll continuous casting apparatus of the present invention will be described. The side weir of the twin roll continuous casting apparatus used in this embodiment is made of graphite, and is the side weir 10 divided into four parts as described above.
As a comparative example, a stainless steel thin plate was manufactured in the same manner as in the example of the present invention, using a side weir 6 (made of graphite), which is a conventional integrated member, installed on the roll peripheral surface shown in FIG.
At this time, the pair of side weirs 6 is structured to be pressed against the peripheral surfaces of the rolls 1a and 1b by a side weir support (not shown).

The casting conditions for stainless steel sheets in Examples and Comparative Examples are shown below. -Type of roll: Internal water-cooled copper alloy roll with a diameter of 400 mm and length of 600 mm-Dimension of thin plate: 300 mm in width and 2 mm in thickness-Type of molten steel: JIS SUS304-Casting temperature: 1505 ° C-Casting speed: 20 m / min and When graphite was used for the side weir, BN (boron nitride) was spray-coated beforehand on the contact surface of the side weir with the molten steel before casting in order to prevent reaction with molten steel.

A stainless steel thin plate was manufactured directly from molten stainless steel using a twin-roll continuous casting apparatus using the divided graphite side weir of the present invention and a conventional side weir. The results are described below. The surface of the stainless steel sheet when the split graphite side weir of the present invention was used was free from cracks caused by a jug, but the conventional stainless steel side weir when using the side weir was used. Surface cracks were observed on the steel sheet. As described above, by using the divided graphite side weirs of the present invention, by preventing the occurrence of hot water, it is possible to prevent the surface cracks of the stainless steel sheet and prevent the stainless steel sheet from being broken due to the surface cracks. It was confirmed that it was possible.

Further, the interface between the side weir and the peripheral surface of the roll after use has been investigated and will be described below. In the divided graphite side weir of the present invention, each part of the divided side weir and the roll peripheral surface were in close contact with each other, no hot water was found, and no damage was found on the side weir and the roll. On the other hand, in the side weir, which is a conventional one-piece, it was recognized that a gap was formed at the interface between the side weir and the roll peripheral surface, and that the side weir and the roll were damaged. .

Further, when the wear situation near the roll kiss point of both side weirs was observed, no wear phenomenon was observed with the divided graphite side weir of the present invention, but the conventional side weir, which is an integral body, was not observed. In, many linear wear marks due to casting were observed. As described above, in the conventional side weir which is an integral member, since the side weir is not mounted so as to be movable in the axial direction of the roll, the stress on the side weir due to the occurrence of casting is not reduced. It was caused by abrasion of the weir, and in extreme cases, the possibility of damaging the side weir was recognized.

In this embodiment, the side weir is divided into four. However, the present invention is not limited to this embodiment, and the number of divisions of the side weir can be changed in consideration of the roll diameter and the like. Further, in the present embodiment, although the side dam made of graphite was used,
A material having self-sliding property may be selected in consideration of the material of the molten metal to be cast and the casting temperature. For example, boron nitride or the like can be used.

In addition, in the present embodiment, an example of casting stainless steel has been described. However, the present invention can be applied to the casting of other steel materials, thin plates of Cu or Cu alloy, Al or Al alloy, and the like. The twin-roll continuous casting apparatus according to the present invention can prevent hot water between the bottom of the side weir and the peripheral surface of the roll, and can also prevent damage to the side weir due to casting at the end of the thin metal plate. In the case of using graphite for the side weir when casting a thin plate of Cu or Cu alloy, Al or Al alloy,
It is not necessary to spray coat BN on the side dam in advance as in this embodiment.

[0025]

As described above, the present invention is characterized in that a pair of side weirs made of a self-sliding material is divided into right and left parts in a casting line and is independently pressed against a roll by a pressing means. In addition, the gap between the side weir and the roll can be reduced, which has the effect of preventing the occurrence of hot water. Further, by attaching each of the divided side weirs independently so as to be movable in the roll axis direction, it is possible to prevent the side weir from being damaged and to reduce the wear amount of the side weir.

As described above, according to the present invention, by providing a simple device to the side weir of the twin-roll continuous casting device,
The effect of preventing hot water between the bottom of the side weir and the peripheral surface of the roll, improving the quality and productivity of the sheet metal, and preventing damage to the side weir due to casting at the end of the sheet metal. It has.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a structure of a side weir of a twin-roll continuous casting apparatus of the present invention.

FIG. 2 is a view showing a mounting mechanism in a roll axis direction of a side weir of a twin roll continuous casting apparatus of the present invention (a view taken in the direction of an arrow aa in a schematic diagram showing the structure of the side weir of FIG. 1).

FIG. 3 is a schematic view of a twin-roll continuous casting apparatus of a type in which a side weir is pressed against a roll end surface.

FIG. 4 is a schematic diagram of a twin-roll continuous casting apparatus of a type in which a side weir is pressed onto a roll peripheral surface.

[Explanation of symbols]

1a, 1b Roll 2 Side weir (type pressed against roll end surface) 3 Pouring nozzle 4 Molten metal pool 5 Metal sheet 6 Side weir (type installed on roll peripheral surface) 7 Side weir support 8a, 8b, 8c, 8d Springs 9a, 9b, 9c, 9d Side weir holding plate 10 Divided side weirs 10a, 10b, 10c, 10d Divided side dams 11 Bolt 12 Spring 13 Spring stand 14 Washer 15 Nut 16 Through hole (side weir) 17 Through hole (side weir support)

Claims (4)

[Claims] 1. A molten metal is supplied to a molten metal pool formed by a pair of rolls and a pair of side weirs provided between the pair of rolls, and the molten metal passes through a gap between the pair of rolls. In the twin-roll continuous casting apparatus for directly manufacturing a thin metal sheet from a molten metal, the pair of side dams is formed of a self-sliding material, and these side dams are formed on the left and right (casting) in a casting line. A twin-roll continuous casting apparatus, which further comprises pressing means for pressing the bottoms of the divided side weirs and the roll independently. 2. The divided side weir is further divided into two or more in a direction perpendicular to the casting direction, and has a pressing means for independently pressing the bottom of the divided side weir and the roll. The twin-roll continuous casting apparatus according to claim 1. 3. The twin-roll continuous casting apparatus according to claim 1, wherein each of the divided side weirs is independently movably mounted in the roll axis direction. 4. The twin-roll continuous casting apparatus according to claim 1, wherein the self-slidable material forming the pair of side weirs is graphite.