JPH0741381B2 - Tundish for continuous casting - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a weir plate (hereinafter, simply referred to as “weir”) provided inside a tundish of a continuous casting facility for molten steel, and in particular, an inert gas is used for molten steel. The present invention relates to a continuous casting tundish in which air is evenly blown into the interior.

[Prior Art] A continuous casting tundish distributes molten steel from a ladle to a continuous casting mold and causes molten steel to flow to float and separate non-metallic inclusions such as slag and deoxidation products in the molten steel. It is a container for making the molten steel temperature and the molten steel components uniform.

In order to promote these functions, multiple weirs and perforated weirs have been conventionally used, and inert gas is blown from the bottom of the tundish using a plug or lance.

FIG. 11 is a cross-sectional view showing a tundish and its peripheral equipment in a continuous casting facility. In FIG. 11, 1 is a pan for containing molten steel, 2 is a spout, and 3 is a slide valve device attached to this spout ( Molten steel flow rate control device), 4 is a chute nozzle communicating with the lower part, 5 is a long air seal pipe, and 6 is a tundish.

7 is a tundish cover, 8 is a liner brick on the side wall of the tundish, 9 is the bottom of the tundish, and 10 is a plate-like weir provided between both inner wall surfaces on the long side of the tundish. A through hole 11 which is a passage is opened in the weir thickness direction.

This through hole is 3-4 above and below to promote molten steel flow.
In some cases, steps are provided, and in order to direct the molten steel flow upward, the through holes may be provided at an angle of 60 ° to 70 ° instead of being horizontal.

A long stopper 12 for restricting the flow rate of molten steel and a slide valve device 3 are attached to the spout of the lower part of the tundish, and an immersion nozzle 14 for injecting the molten steel into a mold 13 is connected to the lower part thereof. Reference numeral 15 is a molten steel injection hole into the mold 13.

Further, the tundish weir is not a single wall that connects the tundish cover 7 and the tundish bottom 9 as described above, but is divided into upper and lower parts and staggered so as to stagger the flow of molten steel. There is a double weir structure designed to promote the floating of objects.

In the above-mentioned conventional tundish, in order to promote the function thereof, an inert gas or air is blown from the bottom of the tundish.

FIG. 12 is a vertical sectional view showing gas blowing by a plug. In FIG. 12, 16 is a gas blowing plug provided on the tundish bottom 9. FIG. 13 is a longitudinal sectional view showing gas blowing using a lance, and 17 is a gas blowing lance.

The arrows shown in FIGS. 12 and 13 indicate the flow of molten steel.

[Problems to be Solved by the Invention] In the conventional tundish for continuous casting as described above, a plug or lance for gas injection is provided separately from the weir, the molten steel spouting hole, and the air seal pipe in the tundish. A part or space for setting is necessary,
Especially in a small tundish, there is no room.

In addition, traditionally from the bottom to the top of the tundish 50
Since it is a gas blowing method with a thin tube of ~ 100 mmφ,
There is a problem that the temperature and components of the molten steel become insufficiently uniformed because the molten metal surface rises due to the local levitation pressure of the gas, so-called local variation of the molten metal surface occurs.

The present invention has been made to solve such a problem, and in particular, even in a small tundish, the molten steel is uniformly stirred so that the temperature and components of the molten steel are made uniform and the floating separation of non-metallic inclusions is prevented. The object is to obtain a continuous casting tundish that can be effectively used.

[Means for Solving the Problems] In the continuous casting tundish according to the present invention, a gas introduction pipe communicating with the outside of the tundish is embedded in the weir, and the tip of the pipe is exposed to the molten steel. It is a method of blowing active gas.The tip of the pipe is located below the weir, below the through-hole of the weir, or above the lower weir and below the flow of molten steel, and is widely distributed at this tip. The gas is blown in through the large number of pores.

[Operation] In the present invention, the gas blows upward toward the entire lower surface of the molten steel flow in the tundish, so that the molten steel is uniformly stirred by the wide dispersion of the gas bubbles.

[Embodiment] FIG. 1 is a front view of a weir showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG.

In these figures, 10 is a through hole of a weir that is provided in a staggered manner in 5 steps above and below, and these through holes 10 have a diameter of 60 mm, an interval of 120 mm, and are inclined 65 degrees to the horizontal direction. It is a passage for molten steel flow.

Reference numeral 18 is a gas introduction pipe made of stainless steel and having a diameter of 9 mm, which is embedded inside the weir, and communicates with the outside at the upper part and is connected to a gas supply device (not shown).

Reference numeral 19 is the tip of the gas introduction pipe 18, and 70 from the lower end of the weir.
It extends horizontally in the length direction of the weir at the position of mm.
Is a large number of gas-blowing thin tubes communicating with the lower end in a direction perpendicular to the lower end, and has a diameter of 2.0 mm in the embodiment.

FIG. 3 is an enlarged cross-sectional view of the lower end portion of FIG. 2, and 21 is a gas blow-out fine hole communicating with the gas blow-out narrow tube 20. Fig. 4 is a partially enlarged view of Fig. 3. 22 is a nylon wire with a diameter of 0.8 mm inserted from the gas blowing thin tube to the outside of the weir at the time of construction of the weir in order to form gas blowing pores. The gas is blown out later to form gas blowout pores, and 23 is a gas discharge port.

FIG. 5 is a perspective view for explaining the gas blowing mechanism of the above embodiment, in which 24 is a long side wall of the tundish, 25 is a molten steel surface, and the molten steel passes through the through hole 11 from left to right in the figure. Is flowing. The gas supplied to the gas introduction pipe 18 flows horizontally at the tip portion 19 and is connected to the direction orthogonal to this at a direction (thickness direction of the weir) with 15 pipes on one side and 20 pipes on both sides 20 and a gas blowing thin pipe. Gas is discharged into the molten steel from the gas discharge port 23 through the hole 21. That is, the discharged gas becomes fine bubbles from below the molten steel flow that has passed through the through holes 11 and is uniformly dispersed and raised in a wide range.

6 and 7 are a front view and a cross-sectional view of a weir showing another embodiment in which gas is blown from the lower end of the weir,
A porous brick 26 connected to the tip portion 19 is attached along the lower end side surface of the weir, and this porous brick has a pore diameter of 20.
The gas is widely discharged into the molten steel through the open pores of up to 100 μm. The porous brick 26 can be attached to both sides of the weir in the thickness direction.

FIG. 8 and FIG. 9 show still another embodiment, in which the horizontal tip portion 19 of the gas introducing pipe is extended not only to the lower end portion of the weir but also to the lower side of each of the multi-stage through holes. The gas is discharged from the lower side of each through hole, that is, the lower side of each molten steel passage by communicating these with the gas discharge port 23 formed on the lower side of each through hole.

FIG. 10 shows an embodiment in the case of multiple weirs, the figure is a longitudinal sectional view of the weir in the longitudinal direction of the tundish, and 27 is a lower weir,
28 is a weir. The gas introducing pipe tip portion 19 is extended to the upper part of each lower weir 27 and is connected to the gas blowing thin tube 20 to discharge the gas upward from the lower portion of the molten steel passage. Also in this case, a large number of gas discharge ports 23 are provided along the upper surface of each lower weir 27, and the gas can be dispersed over the entire surface of the flow of molten steel.

[Effect of the Invention] In the invention according to claim 1 of the present application, the weir is provided with a molten steel passage for passing molten steel from the molten steel supply side space to the molten steel discharge side space, and a gas blowing means for blowing an inert gas into the molten steel, Since the gas supply means for supplying the inert gas was connected to the gas blowing means, the molten steel passing through the molten steel passage of the weir became a turbulent flow near its outlet, and was blown from the gas blowing means to the molten steel in this turbulent state. The inert gas is mixed well, and the non-metallic inclusions in the molten steel are effectively floated and separated.

Further, in the invention according to claim 2 of the present application, since the molten steel passage is composed of a large number of through holes provided in the lower part of the weir, the molten steel passing through the through holes becomes a large number of small turbulent flows, and is inactive with the molten steel. The gas is mixed very well, and the non-metallic inclusions are floated and separated very well.

Further, since the invention according to claim 2 of the present application has such a feature, the molten steel that has passed through the through-hole has a uniform flow as a whole, and the molten steel is supplied to the continuous casting machine in a stable state,
This has the effect of producing a strand of constant quality.

Further, in the invention according to claim 3 of the present application, since the gas blowing means is provided in the lower part of the weir, the gas blown into the molten steel floats over a long distance (depth), and the molten steel and the gas are extremely good. And the non-metallic inclusions are floated and separated very well.

Further, in the invention according to claim 4 of the present application, since the gas blowing means comprises the gas blowing pores, the bubbles of the inert gas blown from the gas blowing means become extremely fine, and the contact area between the inert gas and the molten steel is The effect is that it becomes extremely wide and the non-metallic inclusions float and separate very well.

Further, in the invention according to claim 5 of the present application, since the gas blowing means is made of porous brick, the bubbles of the inert gas blown from the gas blowing means become extremely fine, and the contact area between the inert gas and the molten steel is extremely wide. Therefore, the effect that the non-metallic inclusions are floated and separated very well can be obtained.

Further, in the invention according to claim 6 of the present application, since the gas blowing means is provided in the through hole, the inert gas surely comes into contact with the untreated molten steel, and the non-metallic inclusions are very favorably floated and separated. The effect is that the molten steel is purified very well.

Further, in the invention according to claim 7 of the present application, the weir comprises an upper weir and a lower weir, the molten steel passage comprises a gap between the upper weir and the lower weir, and the gas blowing means is provided above the lower weir. Therefore, the molten steel is effectively supplied to the molten steel discharge side space from the molten steel supply side space, and is effectively purified by the inert gas.

[Brief description of drawings]

1 is a front view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA in FIG. 1, FIG. 3 is an enlarged view of a lower portion of FIG. 2, and FIG. 4 is a partially enlarged view of FIG. 5 and FIG. 5 are perspective views for explaining the gas blowing mechanism of the above embodiment, FIGS. 6 and 7 are front and sectional views showing another embodiment, and FIGS.
The figure shows a front view and a cross-sectional view showing still another embodiment,
FIG. 10 is a sectional view showing an embodiment of the multiple weir, FIG. 11 is a sectional view showing a tundish and its peripheral equipment, and FIGS. 12 and 13 are sectional views showing a conventional gas blowing method. 6 ... Tundish, 10 ... Tundish weir, 11 ...
… Through hole, 18 …… Gas introduction pipe, 19 …… Gas introduction pipe tip, 20 …… Gas blowing thin tube, 21 …… Gas blowing pore, 23 …… Gas outlet, 26 …… Porous brick, 27… …
Lower weir, 28 …… Upper weir.

Claims (7)

[Claims] 1. A tundish for continuous casting comprising a tundish and a weir that divides the space in the tundish into a molten steel supply side space and a molten steel discharge side space. A molten steel passage for passing molten steel from the space to the molten steel discharge side space and a gas blowing means for blowing an inert gas into the molten steel are provided, and a gas supply means for supplying an inert gas to the gas blowing means is connected. Characteristic continuous casting tundish. 2. The molten steel passage comprises a large number of through holes provided in a lower portion of the weir.
Tundish for continuous casting described. 3. The tundish for continuous casting according to claim 1, wherein the gas blowing means is provided below the weir. 4. The continuous casting tundish according to claim 1, wherein the gas blowing means comprises gas blowing pores. 5. The continuous casting tundish according to claim 1, wherein the gas blowing means is made of porous brick. 6. The tundish for continuous casting according to claim 1, wherein the gas blowing means is provided in the through hole. 7. The weir comprises an upper weir and a lower weir, the molten steel passage comprises a gap between the upper weir and the lower weir, and the gas blowing means is provided above the lower weir. The continuous casting tundish according to claim 1.