KR101201768B1 - Sliding gate assembly and method for controlling the same - Google Patents

Abstract

The present invention relates to a sliding gate assembly and a method of controlling the same, which prevents the outside air from being mixed in the molten steel flowing between the tundish and the immersion nozzle, in particular, the sliding gate assembly according to an embodiment of the present invention A sliding gate installed to adjust the amount of molten steel injected into the mold from the tundish; A sealing cassette disposed below the tundish to enclose and seal the sliding gate; And a decompression unit for measuring and regulating the vacuum pressure inside the sealing cassette.

Description

SLIDING GATE ASSEMBLY AND METHOD FOR CONTROLLING THE SAME}

The present invention relates to a sliding gate assembly and a control method thereof, and more particularly, to a sliding gate assembly and a control method thereof to prevent the outside air is mixed in the molten steel flowing between the tundish and the immersion nozzle.

In general, continuous casting facilities are molten steel produced in the steelmaking process in ladles are transported to the tundish using a long nozzle in the continuous casting process, and then supplied as a mold to continuously produce cast pieces of the desired size.

As a method of controlling the amount of molten steel injected into the mold in the tundish, a method using a stopper and a method using a sliding gate are used.

FIG. 1 is a view schematically showing a main part of a continuous casting facility to which a conventional sliding gate method is applied, and FIG. 2 is a view showing a crack of a central plate generated by a negative pressure in a conventional sliding gate.

Referring to FIG. 1, the sliding gate 20 includes an upper plate 21, a middle plate 22, and a lower plate 23 stacked thereon. As the plate 22 slides between the upper plate 21 and the lower plate 23 by the operation of the cylinder 25, the flow rate of the molten steel is controlled.

The sliding gate 20 has a structure that is open to the atmosphere, and due to the negative pressure generated on the upper and lower surfaces of the central plate 22 during discharge of the molten steel, as shown in FIG. C) occurs a problem occurs. When the crack (C) is generated in the center plate 22, the outside air is mixed into the sliding gate 20 to the area (S) where the negative pressure is generated through this, thereby re-molding the molten steel, deepening nozzle clogging, Problems such as bubble instability and turbulence instability due to turbulence generation have occurred.

Thus, to date, a gas injection pipe 30 is formed at the molten steel outlet of the sliding gate 20 and the tundish 10 to prevent the outside air from being mixed into the sliding gate 20, and the gas injection pipe ( A method of reducing the mixing of outside air by injecting an inert gas such as argon (Ar) into the sliding gate 20 through 30 has been proposed and used. However, such a method was also difficult to completely prevent the outside air is mixed into the sliding gate 20, and when argon gas is injected in a large amount in order to prevent the outside air from being mixed, the argon gas is mixed into the molten steel, resulting in a bubble defect. There was a problem acting as a cause.

Embodiments of the present invention provide a sliding gate assembly and a control method thereof, which seal a sliding gate for injecting molten steel into a mold in a tundish and reduce the sliding gate and its surroundings to prevent mixing of outside air into the sliding gate. to provide.

In particular, when molten steel flows through the sliding gate, the sliding gate and the surrounding pressure of the decompression pressure are adjusted in response to a change in sound pressure generated inside the sliding gate according to the opening amount of the sliding gate, thereby causing damage to the sliding gate and the outside of the molten steel. It provides a sliding gate assembly and a control method thereof that can also prevent leakage.

Sliding gate assembly according to an embodiment of the present invention is installed on the lower portion of the tundish sliding gate for adjusting the amount of molten steel injected into the mold in the tundish; A sealing cassette disposed below the tundish to enclose and seal the sliding gate; And a decompression unit for measuring and regulating the vacuum pressure inside the sealing cassette.

The decompression unit includes a vacuum pipe connected to the sealing cassette; A vacuum pressure gauge connected to the vacuum pipe to measure a vacuum pressure inside the sealing cassette; Vacuum means connected to said vacuum piping to provide a vacuum inside said sealing cassette; And a vacuum controller connected to the vacuum means to adjust a vacuum pressure inside the sealing cassette.

The vacuum means is characterized in that the vacuum ejector.

Sound pressure measuring means for measuring the sound pressure generated in the molten steel flowing along the sliding gate.

In the sliding gate assembly control method according to an embodiment of the present invention, in the method of controlling the amount of molten steel injected into the mold in the tundish containing the molten steel in the sliding gate assembly, the sliding gate is sealed with a sealing cassette, It is characterized by reducing the inside of the sealing cassette.

The degree of decompression of the inside of the sealing cassette is adjusted according to the opening amount of the sliding gate.

The sound pressure generated in the molten steel flowing along the sliding gate is measured, and the degree of decompression inside the sealing cassette is adjusted according to the degree of the measured sound pressure.

It is characterized in that the inside of the sealing cassette to reduce the pressure to 61.325 Kpa ~ 101.315 Kpa.

According to an embodiment of the present invention, when the molten steel is injected into the mold by using the sliding gate, the molten steel is reoxidized by sealing the inside and the periphery of the sliding gate and preventing the outside air from entering the interior of the sliding gate. It can prevent.

Accordingly, it is possible to stably produce steel grades requiring ultra-cleanness, and to restrain the generation of inclusions by oxygen contained in the outside air, and to stabilize the bath surface by reducing the inclusion defects, the plugging of the immersion nozzle, and reducing the outside air.

In addition, in order to prevent the flowing molten steel from coming into contact with the outside air, it is not necessary to blow an inert gas such as argon gas into the sliding gate, thereby preventing the problem that inert gas is mixed into the molten steel causing foaming defects. .

1 is a view schematically showing the main part of a continuous casting equipment to which a conventional sliding gate method is applied,
2 is a view showing the crack of the center plate caused by the negative pressure in the conventional sliding gate,
3 is a view showing a sliding gate assembly according to an embodiment of the present invention,
4 is a graph showing the effect of the decompression degree of the sliding gate,
5a and 5b is a graph analyzing the degree of defects of the cast produced before and after the application of the sliding gate assembly according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know. Wherein like reference numerals refer to like elements throughout.

3 is a view showing a sliding gate assembly according to an embodiment of the present invention.

As shown in FIG. 3, the molten steel reoxidation prevention device in the sliding gate according to the exemplary embodiment of the present invention is installed under the tundish 10 to inject the molten steel injected into the mold 40 from the tundish 10. A sliding gate 20 for adjusting; A sealing cassette (100) installed below the tundish (10) to enclose and seal the sliding gate (20); It includes a decompression unit 200 for measuring and adjusting the vacuum pressure inside the sealing cassette 100. And, it includes a sound pressure measuring means 300 for measuring the sound pressure generated in the molten steel flowing along the sliding gate 20.

The sliding gate 20 is provided between the bottom surface of the tundish 10 and the upper end of the immersion nozzle 11 to adjust the flow of molten steel flowing from the tundish 10 into the mold 40. The gate 20 has an upper plate 21, a middle plate 22, and a lower plate 23 in the upper direction of the immersion nozzle 11 at the lower surface of the tundish 10. ) Are sequentially arranged, and the central plate 22 is provided to slide between the upper plate 21 and the lower plate 23. At this time, the center plate 22 is installed on the axis of motion of the cylinder 25 is slide movement by the operation of the cylinder (25). At this time, the sliding gate 20, that is, the upper plate 21, the center plate 22 and the lower plate 23 does not need to be formed a separate gas inlet pipe (30 in FIG. 1) for the inlet gas inlet. .

The sealing cassette 100 is a means for closing the sliding gate 20 and its periphery to block the outside and the inside of the sealing cassette 100. The sealing cassette 100 may be sealed to seal the sliding gate 20 and the periphery thereof. If it is, it may be manufactured in any shape. Preferably, the interior of the sealing cassette 100 is formed with an accommodating portion for accommodating the sliding gate 20, and an upper portion of the sealing cassette 100 is manufactured in a shape corresponding to the bottom surface of the tundish 10 so that Seal the bottom surface. In addition, a lower portion of the sealing cassette 100 is manufactured to have a shape in which the immersion nozzle 11 is sealed, and the sealing cassette 100 and the immersion nozzle 11 are sealed.

The decompression unit 200 is a means for decompressing the inside and the periphery of the sealing cassette 100. The decompression unit 200 includes a vacuum pipe 210 connected to the sealing cassette 100; A vacuum pressure gauge (220) connected to the vacuum pipe (210) for measuring a vacuum pressure in the sealing cassette (100); A vacuum means (230) connected to the vacuum pipe (210) to provide a vacuum in the sealing cassette (100); It is connected to the vacuum means 230 includes a vacuum controller 240 for adjusting the vacuum pressure in the sealing cassette 100.

One side of the vacuum pipe 210 communicates with the inside of the sealing cassette 100, and the other side thereof is connected to the vacuum pressure gauge 220, the vacuum means 230, and the vacuum controller 240.

The vacuum pressure gauge 220 is a means for measuring and displaying the pressure inside the vacuum pipe 210, and measures the pressure inside the vacuum pipe 210, preferably the pressure inside the sealing cassette 100, and the measured value. This is indicated to be confirmed and the measured value is transmitted to a computer (PC) 50 that controls the operation of the vacuum controller 240 and the sliding gate 20.

The vacuum means 230 is connected to the vacuum pipe 210 to reduce the inside of the sealing cassette 100, various means for reducing the inside of the sealing cassette 100 may be applied. However, conventional rotary pumps and cylinder pumps can produce high pressure, but since refractory debris is mixed, they cause frequent failures, making it difficult to use for long time castings. It is desirable to use a vacuum ejector as a device that is not sensitive and capable of vacuum.

The vacuum controller 240 is a means for controlling the operation of the vacuum means 230 to adjust the amount of decompression inside the sealing cassette 100 by the vacuum means 230.

Sound pressure measuring means 300 is a means for measuring the degree of sound pressure generated in the molten steel flowing in the sliding gate 20, various means for measuring the sound pressure generated in accordance with the flow of molten steel is used Can be. In addition, the sound pressure measuring means 300 may be replaced by a method for calculating the opening amount of the sliding gate 20 by numerical analysis without installing a separate measuring device.

A method of preventing remelting of molten steel in the sliding gate during playing by using the molten steel reoxidation prevention device in the sliding gate configured as described above will be described.

First, the sealing cassette 100 is installed between the tundish 10 and the immersion nozzle 11 while the molten steel of the tundish 10 is prevented from flowing into the mold by the sliding gate 20. 20) Seal. Then, the vacuum means 230 is operated to depressurize the inside of the sealing cassette 100. Then, the inside of the sliding gate 20 and its surroundings are decompressed to a state lower than atmospheric pressure. Accordingly, outside air is prevented from entering the sliding gate 20.

The molten steel is injected into the mold 40 by sliding the center plate 22 of the sliding gate 20 while preventing outside air from entering into and around the sliding gate 20.

Then, the sound pressure generated in the sliding gate 20 through the sound pressure measuring means 300 at the same time as the injection of molten steel is measured. In addition, the vacuum pressure inside the sealing cassette 100 is measured through the vacuum pressure gauge 220. The sound pressure value and the vacuum pressure value measured by the sound pressure measuring means 300 and the vacuum pressure gauge 220 are transmitted to the computer 50, and the computer 50 adjusts the vacuum pressure value according to the measured sound pressure value. The operation of the vacuum controller 240 and the sliding gate 20 is controlled.

For example, when the opening amount of the sliding gate 20 increases, so that the sound pressure generated by the sliding gate 20 increases, the amount of decompression inside the sealing cassette 100 is improved. On the contrary, when the opening amount of the sliding gate 20 decreases and the sound pressure generated by the sliding gate 20 decreases, the amount of decompression inside the sealing cassette decreases.

The pressure inside the sealing cassette 100 is adjusted in response to the opening amount of the sliding gate 20 and / or the sound pressure value measured by the sound pressure measuring means 300. The pressure inside the sealing cassette 100 is adjusted lower than atmospheric pressure. Preferably, the appropriate pressure in the sealing cassette 100 is 61.325 Kpa ~ 101.315 Kpa. When the internal pressure of the sealing cassette 100 is greater than the suggested pressure, the outside air may be mixed, and when the internal pressure of the sealing cassette 100 is smaller than the suggested pressure, the crack of the refractory caused by thermal shock may be cracked. (C in Fig. 2) and the molten steel is to be sucked into the yongson site, which causes a problem that causes the operation accident.

Next, the embodiment using the molten steel reoxidation prevention device in the sliding gate which concerns on this invention is compared with the comparative example by the conventional playing system which does not use the apparatus which concerns on this invention.

4 is a graph showing the effect according to the decompression degree of the sliding gate, this experiment is performed by changing the decompression amount inside the sealing cassette using the molten steel reoxidation prevention device in the sliding gate according to the present invention, The results of observations on the condition of equipment and cast steel are shown.

As shown in FIG. 4, when the performance was performed by reducing the pressure below the appropriate decompression degree (the "A" section and the "C" section), it was judged that the effects of the fluctuation of the surface of the bath, the quality of the cast steel, etc. were almost ineffective. This is a result showing that outside air continues to be mixed between the center plates of the sliding gate due to the insufficient amount of decompression.

In addition, when performance was performed by decompressing the proper depressurization more excessively (section "B"), problems occurred in controlling the surface level and sliding gate discharge amount after the casting progressed and time passed. As a result of the analysis, as the casting started, microcracks caused by thermal shock occurred on the sliding gate, and the cracks grew as the casting progressed, and the melting of the refractory occurred due to the friction between the central plate and the molten steel. It was confirmed that the molten steel was sucked in, causing an abnormality in the discharge amount control of the sliding gate, leading to a severe fluctuation in the water surface.

From this experience, it was judged that there was an appropriate amount of decompression, and when the performance was measured using the numerical analysis at the appropriate decompression degree ("D" section), there was no problem in the performance of the performance. When the process data were analyzed, the surface hit ratio was 98.1%, and 99.4% when the decompression unit was applied.

Figures 5a and 5b is a graph analyzing the degree of defects of the cast produced in the playing equipment before and after the application of the sliding gate assembly according to an embodiment of the present invention, as shown in Figure 5a the pressure reduction unit in the surface inspection of the cast It was confirmed that the installed example significantly reduced the defects under the surface of the cast steel as compared with the conventional comparative example.

In addition, as can be seen in Figure 5b when the inspection of the surface layer 10mm or less by using an ultrasonic apparatus compared to the conventional comparative example, the defects of the size of 1mm or more, which may cause problems in the actual rolling process is improved by more than 80% is significantly reduced The result was obtained.

As can be seen from the above results, it has been found that the decompression degree of the sliding gate is most important.

In addition, the vacuum ejector is used as the vacuum means of the decompression unit to satisfy the desired purposes such as pressure control and durability. Conventional centrifugal (Rotary) pumps or cylinder pumps have a significant decrease in durability due to foreign substances, but the change to the vacuum ejector type did not cause any problems even after ten tests.

The present invention is not limited to the above-described embodiments, but may be embodied in various forms. In other words, the above-described embodiments are provided so that the disclosure of the present invention is complete, and those skilled in the art will fully understand the scope of the invention, and the scope of the present invention should be understood by the appended claims .

10: tundish 20: sliding gate
21: upper plate 22: center plate
23: lower plate 40: mold
50: computer 100: sealing cassette
200: decompression unit 210: vacuum piping
220: vacuum pressure gauge 230: vacuum means
240: vacuum controller 300: sound pressure measuring means

Claims (8)

A sliding gate installed at a lower portion of the tundish to adjust the amount of molten steel injected into the mold from the tundish;
A sealing cassette disposed below the tundish to enclose and seal the sliding gate;
A decompression unit for measuring and adjusting the vacuum pressure inside the sealing cassette;
Sound pressure measuring means for measuring the sound pressure generated in the molten steel flowing along the sliding gate Including,
The decompression unit
A vacuum pressure gauge for measuring a vacuum pressure inside the sealing cassette;
And a vacuum controller for controlling the vacuum pressure inside the sealing cassette by controlling the sliding gate operation according to the sound pressure value measured by the sound pressure measuring means to adjust the opening amount of the sliding gate.
The method of claim 1, wherein the decompression unit
A vacuum pipe connected to the sealing cassette;
A vacuum means connected to the vacuum pipe to provide a vacuum inside the sealing cassette,
The vacuum pressure gauge is connected to the vacuum pipe sliding gate assembly.
The method according to claim 2,
Said vacuum means being a vacuum ejector.
delete In the method of controlling the amount of molten steel injected into the mold in the tundish containing the molten steel with the sliding gate assembly,
Sealing the sliding gate with a sealing cassette and depressurizing the inside of the sealing cassette;
Measuring a sound pressure value inside the sliding gate by molten steel flowing along the sliding gate;
Controlling the degree of decompression inside the sealing cassette;
The process of adjusting the decompression degree in the sealing cassette,
And controlling the opening amount of the sliding gate by controlling the operation of the sliding gate according to a sound pressure value inside the sliding gate.
delete delete The method according to claim 5,
Sliding gate assembly control method for reducing the pressure inside the sealing cassette to 61.325 Kpa ~ 101.315 Kpa.

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