JPH08164454A - Pouring nozzle for continuous casting apparatus for wide and thin cast slab - Google Patents

Abstract

PURPOSE: To form the spouting flow having good straightness while restraining clogging by providing a many hole nozzle for straightening flow having pouring small holes so that the pouring small holes communicate with slitting spouting holes. CONSTITUTION: Molten steel is supplied into a movable mold from a tundish through an immersion nozzle 6 via an inner nozzle 6i. The molten steel is straightened in the desirable condition with the pouring small holes 10 in the many-hole nozzle 11 for straightening flow provided in the immersion nozzle 6 and spouted into the movable mold from the slitting spouting holes 5c, 5s. Since this molten steel is spouted into the movable mold by straightening the flow in the desirable condition, the molten steel spouting flow from the center part spouting hole 5c and both side part spouting holes 5c is formed to the uniform and stable flow having many horizontal directional components at the shallow range near the molten metal surface, and the generation of stable solidified shell at the initial stage is accelerated and the entrapment of scum is restrained. By this constitution, the wide and thin cast slab having good surface characteristic can stably be cast for the long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel using a moving mold such as a twin-drum type continuous casting method or a twin-belt type continuous casting method and a dipping nozzle having slit-shaped discharge ports on both side surfaces of the lower end portion.
The present invention relates to an injection nozzle for a continuous casting device that casts wide and thin slabs of metals such as stainless steel, copper and aluminum.

[0002]

2. Description of the Related Art For example, in continuous casting of thin steel slabs using a twin drum type continuous casting apparatus which has been conventionally generally known, as shown in FIG. 5, a pair of rotating cooling drums 1a, 1b and side weirs 2a, 2b abutting on both ends of this drum, into a movable mold 3 formed from inside the tundish 4 through an inner nozzle 6i attached to this tundish, and slits on both sides of the lower end. Molten steel 7 is supplied through a dipping nozzle 6 having a discharge port 5, and a molten pool 8 is formed in the moving mold 3 while being cooled to form a solidified shell. A wide thin slab 9 is cast by pressure contact and integration at a gap portion (kissing point) formed in the closest portion of the drums 1a and 1b.

In this twin-drum type continuous casting, in order to form a solidified shell having a uniform thickness, and to stably cast a thin cast piece having no component segregation and no surface defects such as entrainment flaws, a moving mold is required. It is required to stabilize the molten metal flow in a preferable state. For example, Japanese Patent Application Laid-Open No. 62-282753 discloses that a filter is built in the immersion nozzle to obtain a discharge flow without disturbance over the entire width of the nozzle.

In this case, however, the filter is apt to be clogged, the filter function is easily lost, and it is difficult to maintain the discharge flow in a preferable state for a long time. Is insufficient for stable casting.

[0005]

DISCLOSURE OF THE INVENTION The present invention is directed to the continuous casting of wide and thin slabs using a moving mold such as a twin belt type continuous casting method and a twin drum type continuous casting method. Continuation of wide and thin slabs that suppresses entrainment and produces a solidified shell with a uniform thickness, and that does not cause segregation of components and that does not cause surface flaws such as entrainment flaws or cracks that can be cast at low cost. An injection nozzle for a casting machine is provided.

[0006]

The first invention of the present invention is as follows:
In an injection nozzle for a continuous casting apparatus for wide and thin cast pieces, which has an inner nozzle insertion hole in the upper part and slit-shaped discharge holes on both sides of the lower end, the slit-shaped discharge hole is formed in the slit-shaped discharge hole forming portion. A pouring nozzle for a continuous casting apparatus for wide and thin cast pieces, characterized in that a rectifying multi-hole nozzle having a smaller diameter pouring small hole is internally provided so that the pouring small hole communicates with a slit-shaped discharge hole.

In a second aspect of the invention, in the first aspect of the invention, the diameter of the pouring small hole of the rectifying multi-hole nozzle is 3 to 10 mm, and the central part of the pouring small hole communicating with each slit-shaped discharge hole is provided. The direction of the pouring small hole is facing the long side of the mold,
In addition, the direction of the small pouring holes on both sides is outward with respect to the direction of the central small pouring hole, and the flow of molten metal discharged from each slit-shaped discharge hole spreads outward. It is characterized by.

[0008]

In the pouring nozzle of the present invention, since the slit-shaped nozzle (main body) is provided with the straightening porous nozzle, a plurality of such straightening porous nozzles are prepared, and the suitability is high depending on the steel type, the slab size, and the casting conditions. It is possible to easily select and use one having nozzle characteristics, and when pouring the molten metal into the moving mold, it is possible to form a discharge flow with good rectifying property while suppressing clogging, and surface properties for a long time. It is possible to stably cast a wide and thin slab with good quality. In addition, the straightening porous nozzle is a plate-shaped body that is easy to process and can be obtained at low cost, and the slit-shaped nozzle body can be mass-produced with a small number of types (at least one type is required), and the nozzle cost can be reduced. Is.

The straightening multi-hole nozzle of the present invention is formed by a pair of plate-like members having a large number of small pouring holes, and inside the slit forming portions on both sides of the lower end of the slit-like nozzle (main body). In addition, the pouring small holes are arranged by adhering or fitting so as to face the slits.

This pouring small hole has a diameter of 3 to 3 that does not cause clogging.
In the state of being installed in the slit-shaped nozzle, it is formed so as to face the side of the mold in the horizontal direction in the state of being installed in the slit-shaped nozzle. If the diameter of the small pouring hole is 10 mm or more, the rectifying effect is not so remarkable.

A space is provided between a pair of plate-like members forming the straightening porous nozzle, and the molten metal is discharged into the mold through the pouring small holes of the straightening porous nozzle through the space.
In this case, the molten metal discharge flow from the pouring small hole of the straightening porous nozzle tends to be tapered, and it is easy to create a nonuniform flow. It is effective to make the discharge flow distribution in the width direction uniform by directing it toward the outside within a range not exceeding 45 degrees with respect to the small pouring hole. If it exceeds 45 degrees, diffusion of the molten metal flow becomes large, and a good molten metal flow cannot be obtained.

Here, it is desirable that the both-sides pouring small hole regions directed to the outside are within 70% or less of the whole pouring small holes. When it exceeds 70%, the flow in the central part becomes insufficient,
The flow in the width direction becomes uneven.

If the distance between adjacent small pouring holes of the rectifying multi-hole nozzle is too wide, the discharge flow will not be continuous in the width direction,
Since it is difficult to form a uniform flow in the width direction, the distance between adjacent small pouring holes may be set to a region of twice the diameter of the small pouring holes or less so that the discharge flow is continuous in the width direction. It is valid.

The discharge holes of the slit-shaped nozzle used in the present invention need not be formed by only one slit, but may be formed by a plurality of slits, but it is preferable to form them symmetrically as much as possible. Moreover, it is preferable that the pouring small holes of the straightening multi-hole nozzle are arranged symmetrically as much as possible. The shape of the pouring out hole is not necessarily required to be a circle, and may be an ellipse, a semicircle, a quadrangle, a polygon, or the like. It is selected in consideration of the workability of holes, the formability of discharge flow, and the like.

The present invention is applied to a twin-drum type continuous casting apparatus or a twin-belt type continuous casting apparatus using an injection nozzle having slit-shaped discharge holes on both sides of the lower end.
Steel, stainless steel, copper, aluminum, alloys and the like can be applied as casting targets.

[0016]

【Example】

(Embodiment 1) This embodiment is a case where the injection nozzle according to the present invention is applied to a twin-drum type continuous casting apparatus for casting thin steel slabs. The twin-drum type continuous casting apparatus is configured as shown in FIG. 5, and will be described with reference to FIG.

A moving mold 3 is composed of a pair of rotating cooling drums 1a and 1b, and a pair of side dams 2a and 2b slidably disposed on both end faces of the cooling drum. Reference numeral 8 denotes a hot water pool portion formed in the movable mold 3. The present invention has a slit-shaped discharge hole 5 at the center of the hot water pool portion 8 which is connected to a tundish carried in above. The submerged nozzle 6 is submerged.

A slit-shaped discharge hole 5c (center portion) for discharging molten steel 7 to the long side (cooling drum side) of the moving mold 3 is provided on both side surfaces of the lower end portion of the immersion nozzle 6 which is immersed in the molten metal pool. Two 5s (side portions) are juxtaposed in the horizontal direction.
The three slit-shaped ejection ports 5c and 5s have the same size and are formed in the same direction.

The immersion nozzle 6 adopts the present invention and, as shown in FIG. 1, has slit-shaped discharge holes 5c,
A straightening multi-hole nozzle 11 formed of a plate-like body made of a refractory in which a large number of small pouring holes 10 are arranged inside a forming portion of 5s (there are 5s on both sides across the central hole 5c). Is decorated. The pouring small hole 10 of this straightening multi-hole nozzle has a diameter 3 which is less likely to be clogged with inclusions or molten metal.
-10 mm, and is arranged such that its spout is located inside the slit-shaped discharge holes 5c, 5s when it is internally installed,
Like the slit-shaped discharge holes, it is formed so as to face the cooling drum 1a (1b) in the horizontal direction. The distance a between adjacent small holes is 2 of the diameter d of the small holes.
It is desirable that the number be less than or equal to twice.

A space 12 is provided between the plate-like members forming the straightening porous nozzle, and the molten steel 7 is discharged into the moving mold 3 from the pouring small hole 10 of the straightening porous nozzle through this space. It is like this. The tundish 4 is provided with a stopper (not shown), and controls the supply amount of the molten steel 7 to the moving mold 3.

A case where continuous casting is carried out in the continuous casting apparatus for thin plates using the immersion nozzle 6 of the present invention thus constructed will be described (see also FIG. 5). After positioning the immersion nozzle 6 of the present invention at a predetermined position, the tundish stopper is raised to form a predetermined gap between the lower end surface of the tundish and the upper end surface of the immersion nozzle 6, and the molten steel 7 is removed from the tundish. It is supplied into the moving mold 3 through the dipping nozzle 6 and is cooled and solidified by the moving mold 3 while forming the molten metal pool 8 of a predetermined level, and the solidified shell generated is the gap between the pair of cooling drums 1a and 1b. A thin slab 9 is continuously cast by pressure contact and integration at a portion (kissing point).

In the present invention, the molten steel 7 is supplied from the tundish 4 through the inner nozzle 6i to the moving mold through the immersion nozzle 6 of the present invention, and the molten steel 7 is incorporated in the immersion nozzle 6. Small pouring hole 1 of straightening porous nozzle 11
0 is rectified to a preferable state, and the slit-shaped discharge port 5c,
Discharge from 5 s to the moving mold 3.

Since this molten steel is rectified into a preferable state and discharged into the moving mold 3, the molten steel discharge flow from the central discharge hole 5c and both side discharge ports 5s is horizontal in a shallow region near the molten metal surface. A uniform and stable flow with many components is created, which promotes the formation of a stable initial solidified shell, suppresses scum entrainment, and casts a thin slab with a uniform thickness and excellent surface quality. be able to.

In this example, the pouring small holes 10 of the straightening multi-hole nozzle 11 built in the dipping nozzle 6 face the cooling drum and are all arranged in the same direction. The molten steel discharge flow from the small pouring hole 10 is tapered in each slit-shaped discharge hole, and the flow tends to be nonuniform.

When it is feared that such a phenomenon will occur, as shown in FIG. 2, the direction of the pouring small holes 10a, 10b on both sides of each slit-shaped discharge hole of the straightening multi-hole nozzle 11 is set to the center. It is effective to direct the angle toward the outside of the angle θ with respect to the partial pouring small hole 10. This angle θ is preferably 45 degrees or less.

In addition, small holes 10a + on both sides for directing outward
The area 10b is a small pouring hole 10 for each slit-shaped discharge hole unit.
The area is preferably 70% or less of the a + 10 + 10b area. By doing so, the molten steel discharge flow distribution in the width direction of the immersion nozzle 6 can be made more uniform.

Further, in the nozzle of the present invention, in order to further secure the rectification effect, for example, as shown in FIG. 3, the rectification multi-hole nozzle 11 is formed in a thick plate-like body, It is also effective to narrow the flow path (space) 12 of the molten steel in the nozzle 6.

The present invention is not limited to this embodiment, but may be modified within the scope of satisfying the constituent requirements of claims 1 and 2 according to the casting object, size, casting conditions and the like. is there.

(Embodiment 2) A wide width obtained by carrying out continuous casting in a twin-drum type continuous casting apparatus having the structure shown in FIG. 5 using the immersion nozzle shown in FIG. 1 adopting the present invention. The surface defect index of the thin slab was investigated. The results are shown in FIG. 4 together with the cases of the conventional example and the comparative example.

Implementation Conditions (Common to Examples and Comparative Examples) Cast Steel Type: Stainless Steel (SUS304) Casting Speed: 40 to 130 m / min Thin Piece Size: Thickness 3 mm x Width 1300 mm Casting Volume: 30 t Cooling Drum Diameter: 1200 mm Cooling Drum Width: 1300 mm Immersion nozzle: Three slit-shaped discharge ports having the same width are provided on one side in the width direction of the cooling drum, and the height position of the slit-shaped discharge ports is 12 mm. Straightening Porous Nozzle (Al ₂ O ₃ -C refractory) Thickness: 10 mm Small pouring hole Diameter: 2 to 12 mm Outward angle: 0 to 10 degrees Angle application area: 0 to 50% Distance between small pouring holes: 2 ~ 12mm Bonding with slit nozzle (main body): Bonding with ceramics bond

In the embodiment of the present invention, the straightening multi-hole nozzle 11 is used.
The pouring small hole 10 of is made 5 mm in diameter, and all are cooling drums 1.
It is the case where the distance a between the small pouring holes is set to 5 mm by directly facing a (1b). In this embodiment, it is possible to obtain the same rectifying property as in the case where a filter is incorporated in the immersion nozzle 6, and the pouring small hole 10 was not clogged, but the molten steel discharge flow tends to be slightly tapered. It was However, the surface defect index of the obtained wide and thin cast piece could be improved to 1/4 of that of the conventional example.

In the embodiment, the pouring small hole of the straightening multi-hole nozzle has a diameter of 5 mm, and the pouring small hole 10 at the center of each slit-shaped discharge hole is 50% of the whole, and its direction is the cooling drum. Placed so as to face each other, and the pouring small holes 10a and 10b on both sides thereof are 25% of the whole, respectively, and are arranged outward with an angle θ of 10 degrees with respect to the direction of the central portion. (See FIG. 2). In this example, there is no clogging of the pouring small holes, the molten steel discharge flow can form a uniform and stabilized rectification in the slit width direction, the surface defect index of the obtained wide thin cast piece is It could be improved to less than half that in the case of the example.

The comparative example is a case where the pouring small holes of the straightening multi-hole nozzle have a diameter of 12 mm, all are directly opposed to the cooling drum, and the distance between the pouring small holes is 12 mm. In this comparative example, the diameter of the pouring small hole was too large, the pressure loss was small, and an unstable discharge flow without rectification was obtained, and the pouring small hole was not clogged. Regarding the surface defect index of the piece, no improvement effect was recognized as compared with the case of the conventional example.

The comparative example is a case where the pouring small holes of the straightening multi-hole nozzle have a diameter of 2 mm, all are directly opposed to the cooling drum, and the distance between the pouring small holes is 2 mm. In this comparative example, molten steel is difficult to pass due to surface tension, and inclusions and the like are clogged, and when 10 tons of casting is performed,
Casting was stopped because the deterioration of operability became remarkable.

The conventional example shown in FIG. 4 is a case where a slit-shaped nozzle having no rectifying multi-hole nozzle is used.

[0036]

In the injection nozzle of the present invention, since the slit-shaped nozzle (main body) is internally provided with the straightening porous nozzle,
Multiple types of this straightening porous nozzle are prepared, and one having highly suitable nozzle characteristics can be easily selected and used according to steel type, slab size, casting conditions, and when pouring molten metal into the moving mold, It is possible to form a discharge flow having a good flow straightening property while suppressing clogging, and it is possible to stably cast a wide and thin slab having a good surface property for a long time. In addition, the straightening porous nozzle is a plate-shaped body that is easy to process and can be obtained at low cost, and the slit-shaped nozzle body can be mass-produced with a small number of types (at least one type is required) and the nozzle cost can be reduced. Is.

[Brief description of drawings]

FIG. 1 (a) is a partial cross-sectional schematic front view showing a structural example of a dipping nozzle for a continuous casting apparatus for wide and thin cast pieces according to the present invention, and FIG. 1 (b) is a view taken along line XX in FIG. 1 (a). Arrow cross-sectional outline explanatory diagram,
FIG. 7C is a schematic cross-sectional view taken along the line YY of FIG.

FIG. 2 is a horizontal cross-sectional schematic explanatory view showing another structural example of the immersion nozzle for the continuous casting apparatus for wide and thin cast pieces of the present invention.

FIG. 3 is a vertical cross-sectional partial schematic explanatory view showing another structural example of the immersion nozzle for the continuous casting apparatus for wide and thin cast pieces of the present invention.

FIG. 4 is an explanatory view showing a surface defect index of a thin cast piece obtained in an example of the present invention.

FIG. 5 is a stereoscopic schematic explanatory view showing an example of a known twin-drum type continuous casting device.

[Explanation of Codes] 1a Cooling drum 2a, 2b Side weir 3 Moving mold 4 Tundish 5,5c, 5s Discharge port 6,6i Immersion nozzle 7 Molten steel 8 Hot water pool portion 9 Thin cast piece 10, 10a, 10b Small pouring hole 11 Straightening Porous Nozzle 12 Molten Steel Passage (Space) in Nozzle

[Procedure amendment]

[Submission date] January 30, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

Further, in the nozzle of the present invention, in order to further secure the rectifying effect, for example, as shown in FIG. 3, a plate-like body for forming the rectifying multi-hole nozzle 11 is formed thick, It is also effective to narrow the flow path (space) 12 of the molten steel in the nozzle 6.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

Implementation Conditions (Common to Examples and Comparative Examples) Cast Steel Type: Stainless Steel (SUS304) Casting Speed: 40 to 130 m / min Thin Piece Size: Thickness 3 mm x Width 1300 mm Casting Volume: 30 t Cooling Drum Diameter: 1200 mm Cooling Drum Width: 1300 mm Immersion nozzle: Three slit-shaped discharge ports of the same width are provided on one side in the width direction of the cooling drum, and the slit-shaped discharge ports are picked up.
The width (in the height direction) is 12 mm. Straightening Porous Nozzle (Al ₂ O ₃ -C refractory) Thickness: 10 mm Small pouring hole Diameter: 2 to 12 mm Outward angle: 0 to 10 degrees Angle application area: 0 to 50% Distance between small pouring holes: 2 ~ 12mm Bonding with slit nozzle (main body): Bonding with ceramics bond

Claims (2)

[Claims] 1. An injection nozzle for a continuous casting apparatus of a wide thin cast piece, which has an inner nozzle insertion hole in an upper part and has slit-shaped discharge holes on both side surfaces of a lower end portion, in the slit-shaped discharge hole forming portion, Continuation of wide and thin cast pieces, characterized in that a rectifying multi-hole nozzle having a pouring small hole having a diameter smaller than that of the slit-shaped discharging hole is internally provided so that the pouring small hole communicates with the slit-shaped discharging hole. Injection nozzle for casting equipment. 2. The diameter of the pouring small hole of the rectifying multi-hole nozzle is 3
Of the small pouring holes that are 10 mm in diameter and communicate with each slit-shaped ejection hole, the direction of the central pouring small hole faces the long side of the mold and the small pouring holes on both sides 2. The injection nozzle for a continuous casting apparatus for wide and thin cast slabs according to claim 1, characterized in that the direction of is directed outward with respect to the direction of the pouring small hole in the central portion.