JPH0673724B2 - Tundish stopper - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tundish stopper or tundish stopper used for continuous casting of metal,
More specifically, in order to control the amount of molten metal in the tundish flowing down into the mold, and to suppress the deposition of non-metallic inclusions in steel on the refractory placed in the molten metal flow path from the tundish to the mold. The present invention relates to a tundish stopper for continuous casting, which has an inert gas bubbling function.

(Conventional Technology) Conventional technology will be described by taking continuous casting of steel as an example. The tundish stopper for continuous casting is used to control the amount of molten steel that is poured into the mold from the tundish in the continuous casting operation, and to stop the casting when the casting is completed. Further, there is a type in which the entire length is divided into a certain size and an integrated type, and the present invention is mainly directed to an integrated tundish stopper (referred to as a long stopper). (Hereinafter referred to as tundish stopper.) Conventionally, in continuous casting of steel types such as aluminum killed steel and silicon killed steel in which non-metallic inclusions are contained in molten steel to be cast, the casting is performed many times continuously for a long time. And, since the inclusions gradually accumulate in the immersion noise inner hole located between the tundish and the mold, that is, the molten steel flow path surface, and it becomes impossible to maintain the continuation of casting, the tip of the tundish stopper (long stopper) 1a in FIG. A method of suppressing the adhesion and deposition of the non-metallic inclusions by bubbling the inert gas from the inner hole 6a side of the gas bubbling single hole 7 of the portion 5a to the inner hole portion 3 of the immersion nozzle 2 of FIG. Alternatively, an inert gas such as argon gas is bubbled into the inner hole 3 of the immersion nozzle 2 from a gas reservoir provided on the wall surface of the inner hole 3 of the immersion nozzle 2 through the pores of the inner wall. It is well known that a slit type dipping nozzle of a type in which the inclusions are washed away to wash out the inclusions is used as a means for preventing the adhesion and deposition of the non-metallic inclusions.

Each of the above methods was adjusted to various conditions for continuous casting operation, such as steel type, casting speed, molten steel temperature, casting time, molten steel flow rate in the immersion nozzle inner hole portion 3, mold powder component and usage amount. Bubbling of the inert gas, that is, the position and range of the bubbling, the type of the inert gas, the bubbling pressure and its flow rate, and the bubbling of the inert gas at the tip portion 5a of the tundish stopper 1a and the immersion nozzle inner hole portion 3. By performing delicate control over the balance of the amount sharing, etc., the non-metallic inclusions are prevented from adhering and depositing in the vertical inner hole portion 3 of the immersion nozzle 2, and a certain number of castings can be extended for a long time to some extent. I was able to do it, but I am in a situation where I have not reached the target level. This is because no measures have been taken for the deposition and accumulation of the non-metallic inclusions on the top bosh portion that becomes the fitting portion 4 with the tundish stopper 1a other than the vertical inner hole portion 3 of the immersion nozzle 2, so that the tundish stopper is not provided. The flow control, which is the main purpose of 1a, becomes ineffective, and the flow rate itself is reduced, and due to this point, the continuous casting for many times in continuous casting is obstructed, and it is forced to be limited. The deposits generated in 1) are peeled off, and they are rolled up into a cast slab, which has a significant adverse effect on the quality and yield, and leaves many important problems such as pushing up the operating cost.

(Problems to be Solved by the Invention) Similarly, continuous casting of steel will be described as an example. As described above, when performing continuous casting for a long time many times in casting aluminum killed steel or silicon killed steel, nozzle clogging due to adhesion and deposition of non-metallic inclusions over the entire length of the immersion nozzle, disturbance of control, slab quality In addition, the present invention has a significant adverse effect on the continuous casting operation such as a decrease in yield. In this invention, the present invention is a non-metallic interposition at both the top bosh portion of the immersion nozzle and the bottom portion of the tundish stopper that fits. This is intended to suppress the adhesion and deposition of substances.

As mentioned above, the tundish stopper is used to prevent non-metallic inclusions from adhering to the gas blowing single hole 7 provided at the bottom tip.
And bubbling of inert gas from the embedded porous plug 7 ', which prevents the non-metallic inclusions from adhering or accumulating at the fitting portion 4 between the tundish stopper 1a and the bosh portion of the immersion nozzle 2. There is no inhibitory effect.

In this invention, the tundish stopper is used only.
1a Fitting part 4 between the bottom part and the top bosh part of the dipping nozzle 2
In order to suppress the adhesion and deposition of non-metallic inclusions in the above-mentioned manner, and to employ a combination of various other known methods for suppressing the inclusions of inclusions in the vertical inner hole portion 3 of the dipping nozzle 2, a large number of continuous castings can be performed. The objective is to achieve smooth operation while maintaining the quality and yield of slabs within an acceptable level continuously for a long time.

(Means for Solving Problems) The present invention has been made to solve the above problems and is configured as follows.

That is, the tundish stopper of the present invention has a plurality of gas bubbling diameters of 0.1 mm to 0.5 mm or 1 near the fitting portion of the immersion nozzle with the top bosh portion in the molten steel flow rate control at the time of casting. Circular or polygonal penetrating pores of side size are radiated with respect to the axis of the tundish stopper, and up and down in the range of 30 ° vertically and 45 ° horizontally respectively. According to the above, the arrangement is made up to the three-dimensional orientation, and further, the arrangement limited to the local area is selected if necessary, and the inert gas introduced from the inert gas supply device to the tundish stopper is required. The above problem is solved by bubbling a required amount from the inner hole toward the outer surface.

Here, the reason for limitation will be described. First of all, the size of the through hole is 0.1m.
The m-0.5 mm is 0.1 mm or less because it is impossible to manufacture, and the 0.5 mm or less is the tundish of the tundish even if the inert gas is fed into the inner hole of the tundish stopper with a back pressure suitable for casting. This is because the molten steel head pressure causes the molten steel to flow back into the tundish stopper inner hole.

Also, the arrangement angle of the through pores should be within 30 ° in the vertical direction and 45 in the left and right.
The reason for setting the angle within ° is that it is a manufacturing limit.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to embodiments with reference to FIGS.

〔Example〕

First, 1 is a tundish stopper, 2 is a dipping nozzle, and both are made of alumina graphite.

Fitting part 4 in molten steel flow rate control during casting in Fig. 1
In the vicinity of the tip 5 of the tundish stopper 1 as a center, that is, in the range of 10 mm downward and 200 mm upward, the thickness is 0.1 mm to 0.5 mm, and the cross-sectional shape is circular or polygonal. A plurality of through-holes 9 and 9 ′ penetrating from the inner hole 6 to the outer surface in a radial range from the upward direction of 30 ° to the downward direction of 30 ° with respect to the axis 8 of the tundish stopper 1. The radiation angle is 45 degrees to the left and right, and it is possible to combine various angles in three-dimensional directions depending on the casting conditions. Plural through-holes 9 and 9'are arranged at regular intervals. A through-pore zone is formed which is arranged.

In the embodiment shown in FIGS. 4 and 5, a plurality of through pores 9 are provided in the tip end portion 5 of the tundish stopper 1 at a radial downward angle of 30 ° with respect to the shaft core 8.

Further, FIGS. 1 to 3 are examples of arrangement only in the upper portion, and most of the inert gas bubbled from the through holes 9'is drawn into the dipping nozzle side by molten steel, although there are differences depending on the casting conditions. For the purpose of the present invention, the remaining part rises up to the surface of the tundish and, at the same time, captures nonmetallic inclusions and floats on the surface of the molten steel to exert a cleaning effect.

In FIGS. 1 to 3, the invention of claim 1 (a plurality of through pores of 0.1 to 0.5 m / m are arranged in a horizontal direction from the inner hole surface to the outer surface in the horizontal direction with respect to the axis of the tundish stopper. A tundish stopper characterized by being installed.)
The embodiment of FIG. 4 and FIG.
It is arranged at an angle in the range of °. 6), the through-holes are arranged at a radial angle in the range of 45 ° to the left and right with respect to the stopper shaft center in the horizontal cross section of the stopper. 7 and 8 show the invention of claim 4 (the angle formed by the through-pores with respect to the stopper axis is in the range of 30 ° in the vertical direction of the horizontal line and in the horizontal cross section of the stopper, respectively). The embodiment of the invention according to claim 5 is shown in FIG. 9 (where the through-holes are localized horizontally and vertically). The present invention is limited to the above embodiment). Further, in the present invention according to claim 1, there is one in which a plurality of through pores are radially arranged, and in this case, the number of through pores is "2".
In the above case, it is needless to say that the problem of the present invention can be solved if, for example, only two of them are arranged "radially".

(Effects of the Invention) The effects of the present invention based on the embodiments are that continuous deposition can be achieved by effectively suppressing the adhesion and deposition of non-metallic inclusions generated in the fitting portion of the tundish stopper and the immersion nozzle by bubbling an inert gas. The target number of operations is made possible, and the growth of inclusions is greatly suppressed by suppressing the deposition and deposition of non-metallic inclusions. As a result, the size of inclusions that are rolled into the slab is miniaturized. Since there is no size affecting the quality, there is no decisive influence on the quality of the slab and the yield, and both are improved.

Further, as compared with the conventional one, the present invention brings about a great effect in that the operating cost can be drastically reduced such that continuous casting for a longer time becomes possible.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the tundish stopper of the present invention, FIG. 2 is the same vertical sectional view, and FIG. 3 is the same horizontal sectional view.
FIG. 4 is a longitudinal sectional view showing an embodiment of the tundish stopper of the present invention, FIG. 5 is a bottom view of the same, FIG. 6 is a transverse sectional view showing an embodiment of the tundish stopper of the present invention, and FIG. 7 is the present invention. FIG. 8 is a longitudinal sectional view showing an embodiment of a tundish stopper, FIG. 8 is a transverse sectional view of the same, FIG. 9 is a longitudinal sectional view showing an embodiment of the tundish stopper of the present invention, and FIG. 10 is a tundish stopper and an immersion nozzle. FIG. 11 and FIG. 12 are vertical cross-sectional views showing the connection, and are vertical cross-sectional views of a conventional tundish stopper. 1,1a …… Tundish stopper, 2 …… immersion nozzle, 3 …… inner hole, 4 …… fitting part, 5,5a …… tip part, 6,
6a ... inner hole, 7 ... single gas blow hole, 7 '... embedded porous plug, 8 ... axial core, 9,9' ... through hole,

Claims (5)

[Claims] 1. A radial direction of 0.1 to 0.1 from the inner hole surface to the outer surface in the horizontal direction with respect to the axis of the tundish stopper.
A tundish stopper characterized by arranging a plurality of through pores of 0.5 m / m. 2. The tundish stopper according to claim 1, wherein the through holes are arranged at an angle of 30 ° in the vertical direction of the horizontal line with respect to the axis of the stopper. 3. The tundish stopper according to claim 1, wherein the through-holes are arranged at a radial angle in the range of 45 ° to the left and right with respect to the stopper axis in the horizontal cross section of the stopper. 4. The combined angle of the through-pores with respect to the stopper axis is in the range of 30 ° in the vertical direction of the horizontal line, and in the horizontal direction of the stopper in the horizontal direction, the angle of radiation is 45 °. The tundish stopper according to claim 1, which is provided. 5. The tundish stopper according to claim 1, wherein the through-holes are locally limited and arranged in the horizontal direction and the vertical direction.