KR19990018028U - Blocking structure of tundish nozzle - Google Patents

Abstract

The present invention relates to a blockage preventing structure of a tundish nozzle which prevents a non-metallic inclusion or a current attached to the tundish nozzle inner surface to supply molten steel from the tundish to the mold during the continuous casting process.

Argon gas is supplied to an inner wall 7 made of porous refractory, an outer wall 11 made of a dense material to surround the inner wall 7, and a slit 8 formed between the inner wall 7 and the outer wall 11. In the tundish nozzle made of an argon gas supply pipe 17 to supply molten steel from the tundish to the mold, an ultrasonic vibration oscillator 21 is attached to the argon gas supply pipe 17, and the ultrasonic vibration oscillator ( 21 is characterized in that the power supply is connected to the power supply 22,

By applying an ultrasonic vibration to the argon gas supply pipe so that the vibration is transmitted to the inner wall of the tundish nozzle, it is possible to prevent the non-metallic inclusions or the now attached.

Description

Blocking structure of tundish nozzle

The present invention relates to a structure designed to prevent non-metallic inclusions or clogging by attaching to the inner surface of a tundish nozzle which is to supply molten steel from the tundish to the mold during the continuous casting process. More specifically, the tundish nozzle is made of porous material. A clogging prevention structure of a tundish nozzle which is capable of preventing nonmetallic inclusions or current from being attached by applying ultrasonic vibration to an argon gas supply pipe for supplying argon gas to the inner wall of the tungsten nozzle. will be.

In general, the continuous casting process is a ladle (1) that can contain molten steel, as shown in Figure 1, and located in the lower portion of the ladle (1) to temporarily receive the molten steel supplied from the ladle (1) And a mold (3) positioned at the lower portion of the tundish (2) and receiving molten steel supplied from the tundish (2) for discharging the cast steel to be manufactured in a predetermined shape, and the mold It is made up of the sprinkling cooling stand 4 which is installed in the lower part of (3) and performs a cooling action to completely solidify a cast of a certain shape which is discharged from the mold 3 in the form of an initial solidification layer. Here, the tundish nozzle 6, which is an immersion nozzle, is installed at the lower portion of the tundish 2 to supply the molten steel of the tundish 2 to the mold 3 and at the same time serve to block the molten steel from the atmosphere. .

Typically, during such continuous casting, the tundish nozzle 6 is often faced with a so-called nozzle clogging phenomenon in which a non-metallic inclusion 15 or now 16 is attached to an inner surface in contact with molten steel as shown in FIG. 2. Bar, the fluid side of the molten steel side forms a so-called boundary layer with almost no flow velocity of molten steel, so that molten steel or inclusions can be attached. Chemically, the inclusions in the molten steel have a higher inner portion of the tundish nozzle than the stir of the molten steel. Since the stirring resistance with the refractory material is large, it adheres to the refractory wall and causes clogging of the intervening nozzle, and when the stirring ability with the refractory is high even in molten steel, the molten steel is attached and causes the clogging of the now-expanding nozzle. In addition, since heat of molten steel is dissipated to the outside through the nozzle wall, the inner surface portion of the tundish nozzle is low in temperature, so that the current layer is easy to grow.

When the tundish nozzle is clogged by the nozzle clogging in this way, the casting is stopped, and even though casting is possible, the molten steel discharged from the nozzle is unevenly formed, resulting in a change in the molten steel surface 12 in the mold 3. Injected mold solvent 13 in the contaminated molten steel to contaminate the molten steel or clogged nozzles 14 or the peeling from the inner surface portion of the tundish nozzle also contaminates the molten steel, which is a major factor in deteriorating the product quality. .

Argon gas blowing methods and induction heating methods are known as conventional methods disclosed to prevent such clogging of nozzles, and melted nozzles and insulated nozzles are also known.

Currently, argon gas blowing is the most widely applied among the above-described methods, which comprises a tundish nozzle 6 as an outer wall 11 and an inner wall 7, as shown in FIG. (7) is formed of a porous refractory and argon gas, etc. can be supplied to the molten steel side through it, the outer wall 11 is made of a dense material so that the argon gas and the like can not penetrate while supporting the inner wall (7). . Here, the inner wall 7 may be supplied to the molten steel side through the slit 8 and the inner wall 7 by forming a slit 8 on the outer wall 11 to connect with the argon gas supply pipe 17. To prevent nozzle clogging.

However, such an argon gas blowing method often causes nozzles to be clogged during prolonged casting by multi-cast casting, requiring an additional nozzle prevention method in addition to this method.

In addition, the melted nozzle is a nozzle manufactured to be washed together with molten steel by forming a low melting point compound when the inclusion and the nozzle material react by varying the material of the nozzle according to the composition of the inclusion. This is effective for clogging the intervening nozzle, but has a disadvantage in that it is not effective for clogging nozzles and is expensive.

In addition, the insulating nozzle is formed of a heat insulating slit instead of the argon gas slit (8) to minimize the heat transfer to the outside air through the nozzle in the state without blowing the argon gas, but there is some effect in preventing the clogging of the nozzle now. There is a disadvantage that there is no effect on clogging the physical nozzle.

In addition, the induction heating method has a disadvantage in that the induction coil is installed around the nozzle to dissolve the current in the nozzle or intervening nozzle clogging and is not effective.

The present invention was devised to solve such a conventional problem, by applying ultrasonic vibration to the argon gas supply pipe for supplying argon gas to the molten steel side through the inner surface portion of the tundish nozzle, the vibration forming the inner surface portion of the tundish nozzle. It is an object of the present invention to provide a clogging prevention structure of a tundish nozzle which can be prevented from clogging a nozzle by preventing the non-metallic inclusion or the adherence by vibrating the inner wall side.

1 is a schematic configuration diagram showing a general continuous casting process

FIG. 2 is a cross-sectional view showing a tundish nozzle having a conventional argon gas supply configuration, inclusions on its inner surface, and a state of attachment thereof.

Figure 3 is a schematic diagram showing a tundish with a blockage preventing structure of the tundish nozzle according to the present invention

4a and 4b are schematic explanatory diagrams showing a tundish nozzle according to the structure of the prior art and the present invention and the resulting argon gas bubble formation and inclusion or attachment phenomenon

Figure 5 is a test schematic for grasping the inclusion state or the present attachment state attached to the present invention and the conventional tundish nozzle

6 and 7 are graphs showing the amount of inclusions attached to the present invention and a conventional tundish nozzle.

Explanation of symbols on the main parts of the drawings

1 ... ladle

2 ... tundish

3 ... mold

4 ... sprinkler cooling stand

6,20 ... tundish nozzle

7 ... the inner wall

8 ... slit

11 ... exterior walls

17 ... argon gas supply pipe

21 ... Ultrasonic Vibrator

22 ... power supply

The present invention as a technical configuration for achieving the above object is made of an inner wall made of porous refractory, an outer wall made of a dense material to surround the inner wall, and an argon gas supply pipe configured to supply argon gas to the slit side formed on the inner wall. A tundish nozzle configured to supply molten steel from a tundish to a mold, wherein an ultrasonic vibration oscillator is attached to the argon gas supply pipe, and the ultrasonic vibration oscillator is connected to a power supply to block power of the tundish nozzle. By providing a prevention structure.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

3 is a schematic cross-sectional view showing a tundish nozzle 20 having a structure of the present invention, which is an inner wall 7 made of porous refractory material and an outer wall 11 made of a dense material to surround the inner wall 7. ) And an argon gas supply pipe 17 adapted to supply argon gas to the slit 8 side formed in the inner wall 7 is substantially similar to the prior art.

The present invention attaches the ultrasonic vibration oscillator 21 to the appropriate portion of the argon gas supply pipe 17, the ultrasonic vibration oscillator 21 is connected to the power supply unit 22 is operated by the power supply unit 22 to ultrasonic vibration It has a configuration to generate.

In order to derive the above structure, the present inventors have conducted research and tests to solve the disadvantages of the conventional nozzle clogging prevention technology, and as a result, the inclusions that are initially attached to the wall surface when a fine ultrasonic vibration is applied to the inner wall of the tundish nozzle It has been found that the formation and growth of nozzle clogging materials can be suppressed by inhibiting adhesion of molten steel particles.

That is, when the ultrasonic vibration oscillator 21 is attached to the argon gas supply pipe 17 for supplying the argon gas to generate ultrasonic vibration from the ultrasonic vibration generator 21 by the power supplied from the power supply unit 22, such ultrasonic waves Vibration is transmitted to the inner wall 7 of the tundish nozzle 20 through the argon gas supply pipe 17 to suppress the attachment of inclusions and molten steel to the coagulation nuclei on the nozzle wall surface.

In particular, when ultrasonic vibration is applied to the inner wall of the tundish nozzle 20 by this structure, argon gas supplied to the molten steel side through the porous inner wall 7 is shown on the inner surface of the inner wall 7 as shown in FIG. 4B. It is formed finely to form a uniform layer of bubble 20a on the nozzle wall surface, which not only reduces the adhesion between the inclusions 15 and 16 but also improves the efficiency of inclusions in the molten steel attached to and removed from the bubble surface. There is also an advantage. Fig. 4a shows a layer of bubble 6a which is shown in a conventional method (i.e., a method of supplying only argon gas without attaching an ultrasonic vibrator), and this layer of bubble 6a is applied to the bubble layer 20a of the present invention. It can be seen that the formation of the inclusions 15 and the now 16 is easy because the formation is very large and not uniform.

Hereinafter, the effects of the present invention will be described in detail through examples.

EXAMPLE

The inventors conducted a test by induction melting to grasp the phenomenon of inclusions and molten steel on the inner surface of the tundish nozzle, heating the molten steel (32) to 1650 ℃ in the induction melting furnace (30) containing the molten steel (32) After melt | dissolution, the test material 34 which processed the porous refractory body of the nozzle inner wall into the rectangle was hung on the steel pipe 35, and it was deposited in molten steel 32. As shown in FIG.

Argon gas was cut off when the test material 34 was selected as the insulating material, and argon gas was supplied to the test material 34 through the steel pipe 35 when the test material 34 was selected as the insulating material. Most of the refractory material was alumina-carbon, but Cao-ZrO ₂ material was used for the melted material. Insulation type ensures insulation by inserting ceramic inside the refractory. Induction heating was made by mounting an induction coil 36 around the refractory. In addition, in order to compare the effect of the present invention by applying an ultrasonic vibration oscillator on the surface of the steel pipe 35, the vibration was applied.

After being deposited for a predetermined time, the test material 34 is taken out to the top, and after cooling, the test material 34 is collected by collecting the inclusions attached to the surface of the test material 34 to determine the total amount, and measuring the current weight of the test material 34. , That is, inclusions and now adhesion inhibition for the tundish nozzle was compared.

As a result of collecting and measuring the inclusions deposited on the low-carbon aluminum deoxidized steel where the inclusion nozzle clogging occurs, as shown in the graph of FIG. 6, the insulating material was prepared in case of argon gas injection only. The amount of inclusions was slightly smaller when used or induction heating was performed, and the amount of inclusions was very small in case of using a dissolving material and when ultrasonic vibration was applied according to the present invention, which has a significant effect on reducing nozzle clogging. I could see that. However, in the case of using a molten iron material, as well as the inclusions in the molten steel, the refractory reacts with the molten steel to be mixed into the molten steel, which causes a problem of contamination of the molten steel. It can be seen that is very practical.

As a result of measuring the total amount of the current layer deposited by depositing on the ultra-low carbon steel in which the nozzle nozzle clogging occurs, it was as shown in the graph of FIG. It can be seen that the amount of adhesion decreases in the order of type, induction heating method, and the structure of the present invention. That is, the melted type is effective in preventing the clogging of the intervening nozzle, but it can be seen that there is no effect in preventing the clogging of the nozzle now, and it can be seen that the thermal insulation is less effective than the induction heating method and the present invention. Induction heating method is expected to cause the damage of the refractory material in actual use due to the induction heating of the undeposited portion due to the induction heating of the similar amount of the present invention and the amount of adhesion.

According to the present invention as described above, by mounting the ultrasonic vibration oscillator in the argon gas supply pipe for injecting the argon gas into the tundish nozzle to generate ultrasonic vibrations so that the vibration is transmitted to the inner wall side of the tundish nozzle and the attachment of the present It has an excellent effect of suppressing such inclusion and clogging of the nozzle.

Claims (1)

An argon gas supply pipe configured to supply argon gas to an inner wall 7 made of porous refractory material, an outer wall 11 made of a dense material to surround the inner wall 7, and a slit 8 formed on the inner wall 7 ( 17) A tundish nozzle which is configured to supply molten steel from a tundish to a mold, An ultrasonic vibration oscillator 21 is attached to the argon gas supply pipe 17, and the ultrasonic vibration oscillator 21 is connected to the power supply unit 22 to receive power.