JPH08164449A - Continuous casting equipment for wide and thin slabs - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a continuous casting apparatus for wide and thin cast pieces capable of appropriately guiding a discharge flow from a nozzle toward a cooling rotator and almost completely preventing inclusion of scum or the like. In an apparatus for continuously casting wide and thin slabs using a moving mold, a partition plate having its immersion depth changed in the longitudinal direction in the molten metal pool between a cooling rotor and a nozzle,
Preferably, it is a continuous casting device for wide-width thin cast pieces in which partition plates are formed along the width direction of the cooling rotator, the partition plates being formed so that the immersion depth of the central portion is shallow and deep on both end sides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting apparatus for casting a wide and thin slab with a mold composed of a pair of cooling rotors such as twin drums and a pair of metal belts. The present invention relates to a casting device for preventing entanglement of floating scum.

[0002]

2. Description of the Related Art In recent years, a technique for continuously casting wide and thin slabs directly from molten metal has been developed and put into practical use. This casting method is a twin-drum (also called twin-roll) type continuous casting method in which a casting space is created by using a pair of drums (rolls) and side weirs, and molten metal is supplied from an injection nozzle to the casting space for casting. A belt-type continuous casting method in which a casting space is formed by using a pair of endless metal belts and side blocks that face each other and a molten metal is supplied from a nozzle to the casting space is widely known. In the present invention, a pair of drums or belts forming a casting space for such wide and thin cast pieces is referred to as a cooling rotator, and a casting space constituted by the cooling rotator, a side dam, etc. is a moving mold. Called.

In the wide-width thin-wall cast casting method using the above moving mold, the casting speed is fast and the pool is small, unlike the continuous casting with a large cross section such as a normal slab.
It cannot be said that general continuous casting powder is suitable for use, and therefore inclusions and oxides called scum (hereinafter simply referred to as scum) are likely to be generated on the surface of the pool. If these scums or the like are caught in the cast piece, the surface of the cast piece is cracked, which is not preferable in terms of the surface properties of the cast piece.

Conventionally, as a means for preventing the inclusion of scum, etc., a method of installing a refractory heat insulator in the molten metal pool of the moving mold to partition the vicinity of the cooling rotor (Japanese Patent Laid-Open No. 63-63).
(JP-A No. 4-158959), or a method of providing a good molten metal flow by disposing a pair of plate-shaped scum weirs in the widthwise direction of the cooling drum in the molten metal pool.

[0005]

DISCLOSURE OF THE INVENTION The above-mentioned conventional method, in particular, the scum weir of Japanese Patent Laid-Open No. 4-158959 has a function of blocking the scum and the like directly toward the cooling rotor by the flow of the molten metal and suppressing eddies and ripples. As a result, the effect of preventing the entrainment of scum or the like was observed to some extent, but a new problem arises under the recent circumstances where a wider slab is being cast.

That is, in order to widen the width of the slab, it is inevitable to use a wide nozzle, but in this case, considering the strength of the discharge portion of the nozzle 4, as shown in FIG. It is inevitable to employ a device in which a plurality of (three in the figure) discharge port slits 4a are formed on one side with a column portion interposed instead of one discharge port. For example, when the molten metal is discharged from the three slits, as shown in the drawing, the discharge flows independently flow, and a stagnation Y is generated on the molten metal surface at a portion just corresponding to the columns between the adjacent slits. Will result in the retention of Even if a rectangular scum weir is immersed in the pool of water, this problem is somewhat alleviated, but it shows a tendency almost similar to that shown in FIG. 7, and it is impossible to prevent the inclusion of scum etc. Can not.

The present invention solves the problems found in the conventional casting means for wide and thin wall slabs, and properly guides the discharge flow from the nozzle toward the cooling rotor to substantially completely prevent the inclusion of scum. It is an object of the present invention to provide a continuous casting device for wide and thin slabs that can be prevented.

[0008]

The gist of the present invention for achieving this object is as follows. (1) Molten metal is injected into a moving mold composed of a pair of rotating drums and a cooling rotating body such as a moving belt from a nozzle having a slit-shaped discharge port directed to the moving mold to form a basin. In an apparatus for continuously casting wide and thin slabs, a partition plate whose immersion depth is changed in the longitudinal direction is arranged along the width direction of the cooling rotor in the molten metal pool between the cooling rotor and the nozzle. A continuous casting device for wide and thin slabs characterized by the above.

(2) The partition plate is formed such that the central part has a shallow immersion depth and deeper on both ends, and the flow of the molten metal discharged from the nozzle between the cooling rotor and the partition plate is near the center. (1) characterized by increasing the size
A continuous casting device for the wide and thin cast piece described.

(3) Molten metal is injected into a moving mold composed of a pair of rotating drums and a cooling rotating member such as a moving belt from a nozzle having a slit-shaped discharge port directed to the moving mold to form a molten metal pool. In a device for continuously casting a wide-width thin cast piece, a partition plate bent in the middle in the longitudinal direction is arranged along the width direction of the cooling rotor in the molten metal pool between the cooling rotor and the nozzle. A continuous casting device for wide and thin cast slabs, characterized in that the part is located closer to the drum than the nozzle.

[0011]

[Function] The discharge flow from the slit-shaped discharge port of the wide nozzle once hits the partition plate provided between the cooling rotator and the nozzle. At that time, since the central part of the partition plate has a shallow immersion depth,
The flow reaching between the partition plate and the cooling rotator is larger than that on both end sides of the partition plate having a deep immersion depth. as a result,
For the molten metal in the pool of water between the cooling rotor and the partition plate,
A flow occurs from the central portion toward both end sides, scum and the like are carried to both end sides of the moving mold and easily discharged there, and are not caught in the slab. Also, when the partition plate is bent in the middle and the distance from the nozzle and the cooling rotator is changed depending on the position of the partition plate, substantially the same operation as described above can be obtained.

A specific example of the present invention will be described below with reference to the drawings. 1 and 2 show a case where the present invention is applied to a twin-drum type continuous casting apparatus, in which a molten metal pool 3 is formed by a pair of cooling drums 1 and a pair of side dams 2, and molten metal is stored in the molten metal pool 3. The nozzle 4 for injecting the molten steel is immersed from above, but the molten metal from the nozzle is cooled by the drum and the side weir, and is drawn out as the wide and thin cast piece 5 below. The illustrated nozzle 4 has a wide width and is formed by forming three slit-shaped molten metal discharge ports 4a on one side of the lower portion of the main body so as to face each drum. The reason why the plurality of ejection ports 4a are provided is that it is not sufficient to form one slit in terms of nozzle strength.

In the above twin drum type continuous casting apparatus,
Hot water pool 3 formed by the drum 1 and the side dam 2
Two partition plates 6 are arranged inside the nozzle width direction (drum axis direction) with the nozzle 4 interposed therebetween. As shown in FIG. 1, the partition plate 6 has a width close to the width of the basin 3, and as shown in FIG. 3, part of the flow from the discharge port of the nozzle 4 is the partition plate. It is set in a state in which it is inclined toward the nozzle side and a part of its lower part is immersed so as to reach the drum 1 after passing through 6. Further, the partition plate 6 is so arranged that the immersion depth is changed in the width direction thereof.
That is, in the illustrated case, the central portion of the lower portion is cut out in a rectangular shape so that the central portion is shallowly dipped, and both side portions thereof are relatively deeply dipped.

When such a partition plate 6 is provided, as shown in FIG. 4, there is a cutout at the time when it reaches the drum, even if it is uniformly discharged from the three discharge ports 4a of the nozzle 4. The flow in the center of the partition plate is larger than that at both ends, and no stagnation point occurs even when discharged from the three slits shown in the figure. Moreover, the flow of molten metal is from the center to both sides (in the direction of the side dam) ) Is generated, and scum is concentrated on the end side where it is easy to discharge.

FIG. 5 shows various aspects of the partition plate.
(A) is a shape with a notch at the lower center adopted in FIG. 1, (b) is an example in which the lower side of the plate to be dipped is notched in a mountain shape, and the flow on the center side is the end side It can be expected to have almost the same function as (a). In addition,
(C) is an example in which a difference is provided in the distance from the drum without changing the immersion depth, and a rectangular partition plate 6A is bent in the middle in the shape of a dogleg in the longitudinal direction to form a planar shape as shown in the figure. See
The central portion is separated from the nozzle 4 and arranged near the drum 1. Similar to (a) and (b) in this mode (c), the flow on the drum center side becomes larger than that on both ends, and as a result, a flow occurs between the drum and the partition plate from the vicinity of the center of the drum toward the side dam. However, it prevents the scum and the like floating on the molten metal surface of the molten metal pool between the drum and the partition plate from being caught in the drum. Of course, any shape other than the illustrated partition plate may be used as long as it has a similar function.

Although the twin drum type continuous casting equipment has been described as an example in the drawings, the present invention can be applied to the metal belt type continuous casting equipment in almost the same manner.

[0017]

【Example】

 -Casting conditions Cooling drum diameter: 1200 mm Casting speed: 40 to 130 m / min Mold width: 1300 mm Partition plate immersion depth: 10 to 30 mm Steel type: SUS304 Casting amount: 10Ton Slab size: Thickness 3 mm x width 1300 mm

As a result of actually casting a wide and thin cast piece under the above-mentioned casting conditions, the surface defect index of the obtained cast piece is compared between the casting apparatus of the present invention (Examples of the present invention ~) and the conventional example. As shown in FIG. From the figure, it can be seen that the present invention has significantly less surface defects, the scum entrainment in the vicinity of the drum is effectively prevented, and the slab quality is improved.

The partition plate or scum weir dipping depth of each example in FIG. 6 is as follows. Conventional scum weir: 15 mm Example of the present invention: central part 10 mm in the shape of Fig. 5 (a), both ends 20 mm Example of the present invention: central 10 mm in the shape of Fig. 5 (b), the endmost part 30 mm Example of the present invention: Fig. 5 15mm in the shape of (c), drum ~
10 mm distance between the center of the partition plate, 30 mm distance between the drum and the end of the partition plate

[0020]

As described above, according to the continuous casting apparatus of the present invention, it is possible to guide the flat flow of the molten metal discharged from the nozzle to a good state, prevent the inclusion of scum and the like, and improve the quality. Can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view of essential parts showing an example of a casting apparatus according to the present invention.

FIG. 2 is an overall perspective view when the present invention is applied to a twin-drum type continuous casting device.

FIG. 3 is an explanatory view showing a state of discharging molten metal from a nozzle in the present invention.

FIG. 4 is a schematic diagram for explaining the operation of the present invention.

5 (a) and 5 (b) are front views showing an embodiment of a partition plate used in the present invention, and FIG. 5 (c) is a plan view showing another partition plate and its installation state.

FIG. 6 is a diagram showing a surface defect index in an example of the present invention in comparison with a conventional example.

FIG. 7 is a schematic diagram for explaining the flow of molten metal due to a wide nozzle discharge port slit.

[Explanation of symbols]

 1 Drum 2 Side weir 3 Hot water pool 4 Injection nozzle 5 Cast slab 6 Partition plate

Claims (3)

[Claims] 1. A molten metal is injected into a moving mold composed of a pair of rotating drums, a cooling rotating body such as a moving belt, and a molten metal is injected from a nozzle having a slit-shaped discharge port directed to the moving mold to form a molten metal pool. In an apparatus for continuously forming wide and thin cast slabs that are formed, a partition plate whose dipping depth is changed in the longitudinal direction is arranged along the width direction of the cooling rotor in the molten metal pool between the cooling rotor and the nozzle. A continuous casting device for wide and thin slabs, which is characterized by being installed. 2. The partition plate is formed such that the central part has a shallow immersion depth and deeper on both end sides, and the flow of the molten metal discharged from the nozzle between the cooling rotor and the partition plate is increased near the center. The continuous casting device for wide and thin cast slabs according to claim 1. 3. A molten metal is injected from a nozzle having a slit-shaped discharge port directed to the moving mold into a moving mold composed of a pair of rotating drums and a cooling rotating body such as a moving belt to form a molten metal pool. In a device for continuously forming wide and thin slabs formed in the molten metal pool between the cooling rotor and the nozzle, a partition plate bent in the middle in the longitudinal direction is arranged along the width direction of the cooling rotor, and the central portion is formed. Is a continuous casting device for wide and thin cast slabs, characterized in that it is located closer to the drum than the nozzle.