JPH0133270B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an immersion nozzle used when continuously casting thin slabs at high speed.

[Conventional technology]

As a recent trend, when manufacturing slabs by continuous casting, the thickness of the slab is made as thin as possible and the slab is cast at high speed. This is because the thinner the wall thickness of the slab, the more the rolling force in the subsequent rolling process can be reduced.

In order to cast this thin slab, a mold having an internal space commensurate with its shape is used.
Further, an immersion nozzle corresponding to the cross-sectional shape of the mold is used so as to evenly supply molten metal to the interior space of the mold.

For example, the immersion nozzle disclosed in Japanese Patent Application Laid-Open No. 49-39524 has a cylindrical upper part and a rectangular lower part, and the shape changes continuously from the upper part to the lower part. However, this immersion nozzle
Because the nozzle is integrally molded, it is difficult to manufacture, and even if localized damage occurs, the entire nozzle must be replaced. Therefore, the burden on manufacturing costs and repair costs was large.

The present applicant also proposed a split-type immersion nozzle as shown in FIG. 6 in Japanese Patent Laid-Open No. 74257/1983. This immersion nozzle is installed in a mold 4 with an internal space that accommodates the wide, thin-walled slab to be cast.
The above-mentioned publication describes the sliding nozzle as a sliding nozzle that is immersed in water. That is, mold 4
An injection nozzle 42 that is immersed in the internal space of 1 is supported by a support 43, and a lower nozzle plate 44, a middle nozzle plate 45, and an upper nozzle plate 46 are arranged above the injection nozzle 42. Further, the upper nozzle plate 46 comes into contact with an upper nozzle 49 attached to a tap hole 48 provided at the bottom of the tundish 47.

Of these, the middle nozzle plate 45 slides in the left-right direction in FIG. 6 by a sliding mechanism 50.
As a result, when the nozzle holes drilled in each nozzle plate 44 to 46 match, the tundish plate 47
The molten metal in the mold 41 passes through the upper nozzle 49, upper nozzle plate 46, middle nozzle plate 45, lower nozzle plate 44, and injection nozzle 42.
injected into the body. At this time, lower nozzle plate 4
In the process of flowing into the flat inner space 52 of the injection nozzle 42 from the cylindrical nozzle hole 51 provided in the injection nozzle 42, the molten metal becomes a wide and thin flow. The molten metal injected into the mold 41 as this flat stream is cooled by heat removal through the vessel wall of the mold 41, and becomes a thin slab.

[Problem to be solved by the invention]

However, when a thin slab was cast using the immersion nozzle proposed in JP-A-58-74257,
There were cases where the flow of molten metal passing through the flat internal space 52 of the injection nozzle 42 was uneven in flow rate or temperature. The present inventors considered the cause of this as follows.

In the immersion nozzle shown in FIG. 6, the inner wall surface of the nozzle hole 51 and the inner wall surface of the flat inner space 52 are continuous. Therefore, in the process of the molten metal flowing down from the nozzle hole 51 to the flat inner space 52,
Although the molten metal is spread in the width direction perpendicular to the plane of the paper, the spread in the thickness direction is not sufficient. FIG. 7 is a diagram schematically representing this stage.

When viewed in the thickness direction of the flat inner space 52, as shown in FIG. 42, it flows along the inner wall surface of the flat internal space 52 as it is without being diffused. Therefore, when viewed in the width direction of the flat internal space 52, as shown in FIG. 7B, the molten metal flow 53
is supplied into the flat interior space 52 in a shape that expands toward the end around the nozzle hole 51 . Therefore, the flow rate distribution of the molten metal is such that the flow rate of the molten metal is high at the center in the width direction of the flat internal space 52 and is low at both ends. Furthermore, cavities 5 are provided on both sides of the flat inner space 52.
4 is generated, and this cavity 54 gives a temperature deviation in the width direction to the molten metal flowing in the flat internal space 52.

Therefore, the present invention creates a flat flow that is uniform both in flow rate and temperature by eliminating the flow along the inner wall surface when molten metal flows into the flat internal space from the cylindrical nozzle hole. It was developed for the purpose of obtaining

[Means to solve the problem]

In order to achieve the objective, the immersion nozzle of the present invention includes a cylindrical body having a rectangular internal space whose length in the width direction is larger than the length in the thickness direction, and a cylindrical body that is attached to the upper part of the cylindrical body so as to be divisible. It has a rectangular top plate and a molten metal inlet hole bored in the rectangular top plate, the upper part of the rectangular internal space is a molten metal pool part, and the horizontal part extending from the molten metal inlet hole to the inner surface of the cylinder is the molten metal pool part. It is characterized in that it is formed in both the width direction and the thickness direction on the lower surface of the top plate that is in contact with the section.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained using examples with reference to the drawings.

FIG. 1 shows a submerged nozzle in a first embodiment of the invention. Figure A is a front cross-sectional view of this immersion nozzle, Figure B is a cross-sectional view taken along the - line in Figure A, Figure C is a plan view, and Figure D is a bottom view.

The cylindrical body 1 of the immersion nozzle in this embodiment has a rectangular internal space 2 suitable for producing thin and wide slabs. The cylindrical body 1 includes a neck portion 3 that expands upward, and a top plate 5 is attached to the neck portion 3 in a fitted state. Further, a circular tapered molten metal inflow opening 4 is formed in the center of the top plate 5. This top plate 5 is integrally fixed to the cylindrical body 1 with mortar or the like. Further, the neck portion 3 of the cylindrical body 1 forms a pool portion 6 directly below the molten metal inflow opening 4.

The molten metal that has flowed into the cylindrical body 1 flows through the molten metal inflow opening 4
At the stage of transitioning from the molten metal to the rectangular internal space 2, the molten metal is diffused in both the width direction and the thickness direction in the sump portion 6.
The molten metal filling this pool 6 is
It becomes a uniform flat stream and flows down into a continuous casting mold (not shown). Therefore, the molten metal is
The flow uniformly flows down within the rectangular internal space 2 over its entire width, and the discharge flow from the cylindrical body 1 becomes a flow having a uniform flow rate distribution in the width direction.

Further, in the example shown in FIG. 1, since the molten metal inflow opening 4 is circular, the opening degree of the molten metal inflow opening 4 can be adjusted by abutting a stopper on this portion from above. In addition, molten metal inflow opening 4
It is not limited to a circular shape, but can also be formed into an ellipse or a rectangle. In this case, the molten metal inflow opening 4
Use a stopper with a cross-sectional shape that corresponds to the cross-sectional shape of the

FIG. 2 shows a submerged nozzle in which an annular recess 7 is formed in the molten metal inflow opening 4. FIG. Figure A is a front cross-sectional view of this immersion nozzle, and Figure B is a cross-sectional view taken along the - line in Figure A. Further, in this embodiment, a bottom wall 8 is provided on the bottom surface of the cylindrical body 1.
, and discharge holes 9 and 11 are formed in the bottom wall 8 and side wall 10, respectively. By closing the bottom surface of the cylindrical body 1 with the bottom wall 8 in this way, the molten metal flowing in from the molten metal inflow opening 4 becomes a discharge flow with reduced outflow energy and flows out into the mold from the discharge holes 9 and 11. do. Note that a horizontal stepped portion 12 is provided at the connection portion between the top plate 5 and the neck portion 3 of the cylindrical body 1. This horizontal stepped portion 12 allows the top plate 5 to be connected to the cylindrical body 1 through mortar, packing, etc. in a more stable state.

FIG. 3 shows an example in which the top plate 5 and the cylindrical body 1 are joined on a horizontal plane. Figure A is a front sectional view of this immersion nozzle, and Figure B is a side sectional view. In this case, the top plate 5
and the cylindrical body 1 are integrated by covering with a metal case 15. In addition, when connecting the two, a suitable sealing material is sandwiched between the joint surfaces of the top plate 5 and the cylinder body 1, and the upper end of the metal case 15 is bent after the brick is inserted. Thereby, the top plate 5 is fixed to the cylindrical body 1. In this way, metal case 1
5, it becomes easy to assemble the submerged nozzle and connect it to a container or sliding nozzle device.

Furthermore, in this embodiment, a plurality of molten metal inflow openings 4 are formed in the top plate 5. Therefore, the supply of molten metal to each part of the thin and wide rectangular internal space 2 is more evenly distributed. As a result, together with the diffusion and mixing in the sump 6, the discharge flow flowing out from the cylindrical body 1 becomes a uniform flat flow.

FIG. 4 shows an embodiment in which a top plate 5 on which a cylindrical protrusion 18 is formed is fitted into a cylindrical body 1 to form a submerged nozzle. In this case, the molten metal inflow opening 4 is the cylindrical protrusion 1
8. Further, the cylinder body 1 is composed of an upper expansion part 19 and a lower cylinder part 20 that can be divided. These upper expanded portion 19 and lower cylindrical body portion 20
are integrated by a metal case 21. Note that instead of the metal case 21, mechanical means such as bolts/nuts or clamps may be used.

The immersion nozzle shown in Figures 1 to 4 above is
In each case, a horizontal portion is formed from the molten metal inflow opening 4 toward the inner surface of the cylinder 1 along both the width direction and the thickness direction. Therefore, the molten metal from the molten metal inlet opening 4 flows into the sump 6 after being sufficiently diffused.

This state will be schematically explained in FIG. 5. Figure A is a cross-sectional view seen in the width direction, and Figure B is a cross-sectional view seen in the thickness direction. Between the lower opening of the molten metal inflow opening 4 and the inner surface of the cylinder 1, the top plate 5 contacts the sump 6 with a horizontal portion 5a in the thickness direction and a horizontal portion 5b in the width direction. That is, the flow path cross-sectional area of the molten metal inflow opening 4 rapidly expands in both the width direction and the thickness direction at the point where the molten metal inflow opening 4 exits from the molten metal inflow opening 4 to the sump 6. Therefore, the molten metal flow 22 that has passed through the molten metal inflow opening 4 is diffused in both the width direction and the thickness direction.

In this regard, in the case of the submerged nozzle introduced in JP-A-58-74257, since the inner wall surfaces of the lower nozzle plate 44 and the injection nozzle 42 are continuous, the molten metal flow 53 is preferentially directed to the inner wall surface of the lower nozzle plate 44 and the injection nozzle 42. It flows along the wall surface and is not affected by the diffusion effect in the thickness direction, as shown in FIG. 5A. In contrast, in the immersion nozzle of the present invention, the molten metal flow 22 exiting from the molten metal inflow opening 4 does not come into contact with the inner wall surface of the cylinder 1.
Therefore, in the vicinity of the outlet from the molten metal inflow opening 4 to the sump 6, the molten metal instantly diffuses in the thickness direction as shown in FIG. 5A. This diffusion in the thickness direction, together with the diffusion in the width direction, instantaneously spreads the molten metal flow 22 also in the width direction, as shown in FIG. 5B. At this time, the cavities formed at the tops of both sides of the rectangular internal space 2 also become small.

Since the cross-sectional area of the flow path expands discontinuously in this manner, the molten metal in the tundish pool 6 is sufficiently diffused. As a result, the molten metal can be evenly distributed to each part of the molten metal sump 6. Since the molten metal filling the pool 6 uniformly flows down within the rectangular internal space 2, temperature segregation in the width direction is also reduced. Furthermore, as the molten metal spreads at the point where it exits from the molten metal inflow opening 4 to the sump 6, mixing of the molten metal is also promoted, so that the molten metal flow 22 has a rectangular shape without segregation of alloy components, etc. It flows down the internal space 2. Moreover, even if the molten metal is drawn out at high speed, no problem occurs.

The discharge flow discharged from the immersion nozzle in this manner has a uniform flow rate distribution and temperature distribution in the width direction. Therefore, when poured into a continuous casting mold, each part is uniformly cooled and a solidified shell is formed, resulting in a healthy thin slab.

〔Effect of the invention〕

As explained above, in the present invention, in the process of molten metal flowing into the molten metal pool in the cylinder from the molten metal inflow opening provided in the top plate, the cross-sectional area of the flow path is discontinuous in both the width direction and the thickness direction. It is expanding to
Therefore, the molten metal flow is sufficiently diffused at the point where it exits the molten metal inflow opening, and the molten metal can be evenly distributed even in the thin and wide flat interior space. As a result, molten metal is injected into the mold as a uniform flat stream from the immersion nozzle,
A healthy thin slab with no variation in the width direction is produced.

[Brief explanation of drawings]

FIG. 1 shows a submerged nozzle in the first embodiment of the present invention in which the top plate is tapered fitted to the cylinder body, and the second to
FIG. 4 shows another embodiment, and FIG. 5 is a diagram for explaining the operation of the immersion nozzle of the present invention. On the other hand, FIG. 6 shows a submerged nozzle previously proposed by the present applicant, and FIG. 7 is a diagram for explaining problems with the submerged nozzle. DESCRIPTION OF SYMBOLS 1: Cylindrical body, 2: Rectangular internal space, 4: Molten metal inflow opening, 5: Top plate, 5a: Horizontal part in the thickness direction, 5b:
Width direction horizontal part, 6: Hot water pool part.

Claims (1)

[Claims] 1 A cylindrical body having a rectangular internal space whose length in the axial direction is larger than the length in the thickness direction, a rectangular top plate detachably attached to the upper part of the cylindrical body, and a molten metal inflow hole drilled in the rectangular top plate. The upper part of the rectangular internal space is a pool part, and a horizontal part extending from the molten metal inflow hole to the inner surface of the cylinder is attached to the lower surface of the top plate in contact with the pool part in the width direction and thickness direction. An immersion nozzle for high-speed continuous casting of thin-walled slabs, characterized in that it is formed on both sides.