KR20120074670A - Rapid pre-heated tundish - Google Patents

Abstract

PURPOSE: A tundish capable of being rapidly preheated is provided to prevent the inflow of impurities into molten metal, and to minimize internal damages to a ceramic crucible. CONSTITUTION: A tundish capable of being rapidly preheated comprises a ceramic crucible(130), a spiral torch spark guide(140),a permanent lining, a steel shell(100), a flame inlet pipe(110), a flame outlet pipe(120), and a ceramic nozzle(170). The spiral torch spark guide winds an outer wall of the ceramic crucible at least one time. The permanent lining comprises refractory materials enclosing the spiral torch spark guide. The steel shell encloses the permanent lining. The flame inlet and outlet pipes are respectively installed in lateral lower and upper ends of the steel shell, and protruded outside. The flame inlet and outlet pipes fire sparks of a torch to the inside. The ceramic nozzle is penetrated through a lower center of the steel shell and a lower part of the ceramic crucible.

Description

Rapid pre-heated tundish {Rapid pre-heated tundish}

The present invention relates to an apparatus for rapidly heating a tundish used in a process of manufacturing a metal powder using a spraying process, and more particularly, directly heating a lower portion of the ceramic crucible 130 inside the tundish through a torch. And a rapid preheatable tundish comprising an apparatus for causing the melt discharging ceramic nozzle 170 to reach a temperature of 1,300 ° C. or higher in 30 minutes.

The atomization process uses a shock amount obtained by high-speed impact of high-pressure fluids (air, water, oil, etc.) onto a free-falling molten metal stem, and then quenched by fine metal droplets. It is a process of manufacturing.

Metal powders produced by the spraying process are widely used as raw materials for sintering parts having complex shapes required for automobiles, machinery, precision electronic parts, etc., and in particular, the use of iron-based powders accounts for 60% or more of the total. Iron-based powder usage is expected to use more than 60,000 tons of iron-based powder in 2010, the global market is expected to demand more than 1.2 million tons in 2010.

In order to manufacture the iron powder through the spraying process, a molten metal having a temperature of 1500 ^o C or more, in which a molten iron ingot, which is a parent metal, is melted in an induction furnace, is melted in a preheated tundish and sprayed under the tundish through a ceramic nozzle of several mm diameter. The chamber should be freely dropped in the form of a stem.

In this case, if the preheating of the tundish is not sufficient, a problem arises in that the hot molten metal is resolidified to clog the ceramic nozzle and the process is stopped. If the process is stopped, it is difficult to recycle the re-solidified molten metal. Therefore, the cost and time of unnecessary tundish device repair work are consumed, resulting in lower process efficiency.

In addition, when preheated for a long time to reach a satisfactory preheating degree, it is possible to damage the ceramic crucible of the tundish, and the efficiency decreases due to the prolonged processing time.

In addition, although the method of heating the torch flame directly inside the tundish is efficient, there is no external heat supply during the process, so it is difficult to keep the tundish temperature constant, and impurities generated from the torch combustion gas on the surface of the ceramic crucible directly contacted with the molten metal The adsorption may cause difficulty in preparing a powder having a desired composition.

Therefore, an object of the present invention is to solve the problems such as clogging of the ceramic nozzle, process efficiency due to long time preheating, crucible damage and difficulty controlling impurities due to direct heating inside the tundish, and the method of directly heating the inside of the crucible This is to provide a tundish that can be preheated rapidly at a high temperature so that the molten metal injected into the ceramic nozzle 170 is not resolidified only by heating outside the crucible.

In order to achieve the above object, in the present invention, in the tundish preheating of the spraying process, the ceramic crucible outer wall 150 positioned inside the tundish so as to rapidly heat the whole by shooting a torch flame at a position on the tundish outer surface. ) By adding a spiral shaped torch flame guide 140 wound around one or more times so that the flame rotates along the guide and exits to the discharge pipe 120, thereby providing a tundish capable of a uniform and rapid preheating as a whole.

The fast preheatable tundish according to the present invention changes the internal structure when the ceramic crucible 130 inside the tundish is fired by preheating the torch flame, thereby innovatively shortening the preheating time, thereby increasing process efficiency and indirect heating. Minimize damage to the ceramic crucible and at the same time has the effect of suppressing the influx of impurities into the molten metal.

1 is a schematic diagram (conventional method 1) of a conventional tundish preheating method.
2 is a schematic diagram of a conventional tundish preheating method (conventional method 2).
3 to 5 are schematic views of the tundish preheating method of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention relates to a fast preheatable tundish used in the process of producing a metal powder using a spraying process. That is, by storing molten steel and enabling rapid preheating of the tundish for dispensing into a mold (chamber for spraying), the present invention

In the tundish formed in the shape of the upper open to contain the molten metal,

An open ceramic crucible 130 positioned inside the tundish;

A spiral torch flame guide 140 having a passage shape wound around the ceramic crucible outer wall 150 at least once;

Permanent field consisting of the refractory surrounding the spiral torch flame guide 140;

A shell 100 surrounding the permanent field;

A fire pipe 110 installed to protrude to the outside at the bottom side of the iron shell 100 to shoot a torch flame;

An emission pipe 120 installed to protrude outward from the upper side of the iron shell 100 to discharge the torch flame input through the injection pipe 110; And

And; a ceramic nozzle 170 penetrating the lower center of the ceramic crucible 130 and the lower center of the iron shell 100;

The fire pipe 110, the spiral torch flame guide 140 and the fire pipe 120 is connected in a passage shape,

The torch flame introduced into the fire pipe 110 does not directly contact the ceramic crucible inner wall 160 and the ceramic nozzle 170 to provide a quick preheatable tundish.

The spiral torch flame guide 140 is characterized in that it starts from the fire pipe 110 and ends in the fire pipe 120, the fire pipe 110 may also include a key that can be used to lock the torch. have. In addition, the fire pipe 110 may be installed to be deflected to one side of the lower side of the iron shell of the tundish, the fire pipe 120 is in accordance with the final direction of the flame proceeds along the spiral torch flame guide 140 Can be installed to build.

In general, in the spraying process, a high temperature molten metal is injected through a nozzle having a small inner diameter, and is formed to meet at a lower temperature of the gas and the lower part of the nozzle, thereby clogging the lower part of the nozzle due to solidification of the molten metal before being differentiated. The nozzle clogging is caused by nozzle inflow of non-metallic inclusions having a high melting point, breakage of the lower part of the nozzle due to contact between high temperature melt and room temperature gas, and poor supply of nozzle melt due to pressure change in the chamber. Melt coagulation by lowering the temperature of a small amount of molten metal passing through the part is the most basic cause. The molten metal melted at a temperature of about 1500-1600 ° C. or higher is partially lowered in the process of tapping in the melting furnace and being transferred to the tundish through the furnace.

In the spraying step, the temperature of the molten metal before tapping is excessively increased in order to prevent the temperature of the molten metal from being lowered during the spraying. The heated molten metal has latent heat that does not solidify at the nozzle part even though the temperature decreases during the course of the furnace and the tundish, but the oxidation loss of the molten metal increases due to the excessive rise of the molten temperature and the life of the furnace refractory is eroded. In addition to the deterioration, the eroded refractory forms high melting point non-metallic inclusions that do not dissolve in the molten metal, and flows into the cutout portion together with the molten metal at the time of tapping to become another cause of nozzle clogging.

Therefore, maintaining the proper melt temperature is an important factor directly affecting the productivity as well as nozzle clogging.

Therefore, in the process of manufacturing the metal powder using the spraying process, the turn to reduce the temperature of the molten metal and blockage of the nozzle for spraying while maintaining the proper molten metal temperature before the molten metal is supplied to the tundish. It is necessary to preheat the dish to about 80-90% of the melt temperature.

The rapid preheatable tundish of the present invention has a structure in which a flame can circulate entirely on the outer wall of the ceramic crucible in the tundish along the spiral torch flame guide 140 wound around the ceramic crucible outer wall 150 located therein. By using the principle that the ceramic crucible 130 inside the tundish is heated at a uniformly high speed by heating the lower portion of the ceramic crucible 130 inside the tundish through a torch flame. It has the effect of reaching temperatures above 1,300 ° C in 30 minutes.

Therefore, according to the present invention, it is possible to manufacture the metal powder using the spraying process without problems such as clogging of the ceramic nozzle, process efficiency deterioration due to long-term preheating, crucible damage and adsorption of impurities due to direct heating inside the tundish.

In addition, the method of preheating the tundish with a torch flame (flame) as described above has the advantage that it is inexpensive and can be installed in a narrow space.

Hereinafter, a tundish preheating process according to an embodiment of the present invention will be described with reference to the accompanying drawings.

1 and 2 are schematic diagrams of a conventional tundish preheating system structure, and FIGS. 3 to 5 are schematic diagrams of a tundish preheating system structure of the present invention.

In the conventional tundish preheating system structure, as shown in FIG. 1, the torch is fixed to the lower part of the tundish to shoot the flame in the fire tube 30, and the flame is discharged by making the fire tube 40 on the upper side opposite the torch fixing portion. It is structured to preheat the ceramic crucible 20 while going out.

On the other hand, the tundish preheating system structure of the present invention, as shown in Figs. 3 to 5, fixes the torch to be deflected to one side of the bottom of the tundish to shoot the flame in the normal direction of the circular structure, and the flame as a whole to the outer wall of the crucible. The spirally circumferential guide structure was formed in a spiral shape so that the fire tube 120 was made in one normal direction of the upper portion of the tundish so as to be finally aligned with the direction in which the flame proceeds.

As described above, the flame creates a structure in which the outer wall of the ceramic crucible inside the tundish can be swung throughout, thereby reducing the heat loss due to the problem that the crucible is heated at a high speed uniformly and eccentrically, thereby discharging the molten metal. By indirect heating through the heat conduction to the part, it was possible to reach a high temperature fast enough to prevent resolidification of the melt.

At this time, the rising angle of the spiral torch flame guide 140 is preferably maintained to 10 to 20 degrees. If it is out of the range, it is difficult to achieve the expected effect, it is important to maintain the angle.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited only to these examples.

[Example 1]

In order to specifically calculate the three effects obtained by applying the present invention, the iron ingot was melted in an induction furnace to prepare an iron powder through a water spray process.

Also, for comparison, the inside of the tundish crucible was manufactured by using a conventional torch using the conventional method of FIG. 1 (conventional method 1) and the conventional method of FIG.

A tundish with LPG torch deflected to one side was mounted in a water spray process apparatus and the torch was ignited to preheat. As shown in FIG. 3, the temperature of each part was measured in real time using the thermocouple of R-type. The temperature of the three parts of ① crucible outer wall, ② crucible inner wall and ③ ceramic nozzle was measured in real time. Table 1 shows the temperature change during preheating of the two groups.

Temperature measurement site 10 minutes 20 minutes 30 minutes 1 hour Existing Method 1 Crucible Outer Wall 1,000 ℃ 1,130 ℃ 1,200 ℃ 1,310 ℃ Crucible inner wall 870 ℃ 1,010 ℃ 1,060 ℃ 1,100 ℃ Ceramic nozzle 865 ℃ 1,000 ℃ 1,030 ℃ 1,050 ℃ Existing Method 2 Crucible Outer Wall 890 ℃ 1,090 ℃ 1,210 ℃ 1,320 ℃ Crucible inner wall 1,010 ℃ 1,210 ℃ 1,300 ℃ 1,430 ℃ Ceramic nozzle 1,005 ℃ 1,200 ℃ 1,290 ℃ 1,410 ℃ Invention Crucible Outer Wall 1,080 ℃ 1,260 ℃ 1,410 ℃ 1,520 ℃ Crucible inner wall 990 ℃ 1,190 ℃ 1,320 ℃ 1,480 ℃ Ceramic nozzle 980 ℃ 1,175 ℃ 1,300 ℃ 1,450 ℃

As shown in Table 1, when the tundish is heated according to the present invention, the temperature of the crucible outer wall 150, the crucible inner wall 160, and the ceramic nozzle 170 is heated faster than 200 ° C. as compared to the conventional method 1. It was confirmed that the temperature of 10 ~ 20 ℃ was slightly higher than that of the conventional method 2, in which the nozzle and the outer wall were directly fired by heating the flame.

Therefore, when the present invention is applied to tundish heating, the heating efficiency is similar to that of the conventional method 2 for directly shooting a flame, and it can be judged that the efficiency is much better than the conventional method 1 without the flame guide.

In addition, the heating efficiency is similar to that of the conventional method 2, and since the inner wall and the nozzle are indirectly heated, it is expected that the inner wall and the nozzle are not damaged by the torch flame. In addition, it is also possible to solve the problem that the impurity generated from the torch combustion gas is adsorbed on the ceramic surface directly in contact with the molten metal may be difficult to produce a powder of the desired composition.

Example 2

The main components of the iron-based powder prepared by applying the present invention and the iron-based powder prepared by applying the conventional method 2 (the method of directly heating the inside of the tundish crucible with a flame) were compared. The impurity items for comparative analysis focused on items such as carbon, oxygen, nitrogen, sulfur, phosphorus, and silicon, which greatly influence the formability. Also shown.

division carbon
(wt%) Oxygen
(wt%) nitrogen
(wt%) sulfur
(wt%) sign
(wt%) silicon
(wt%) Iron ingot 0.0029 0.0095 0.001 0.0005 0.012 0.0057 Existing Method 2 0.025 0.13 0.023 0.0013 0.013 0.0017 Invention 0.004 0.11 0.022 0.0010 0.011 0.0013

As shown in Table 2, when the iron powder is prepared according to the present invention, the carbon content of the iron powder is higher than that of the method of heating the tundish directly from the top using a torch flame (conventional method 2). It was confirmed that clean iron was made. Carbon component is a component that greatly affects the formability of the iron powder has a feature that the formability is improved as the content is smaller, it is to use the present invention to obtain an iron powder with improved formability compared to the conventional method when manufacturing iron powder It is expected.

10, 100: bar
20, 130: ceramic crucible
30, 110: fire tube
40, 120: fire pipe
50, 170: ceramic nozzle
60: torch
140: Spiral Torch Flame Guide
150: ceramic crucible outer wall
160: ceramic crucible inner wall

Claims (5)

In the tundish formed in the shape of the upper open to contain the molten metal,
An open ceramic crucible 130 positioned inside the tundish;
A spiral torch flame guide 140 having a passage shape surrounding the ceramic crucible outer wall 150 at least once;
Permanent field consisting of the refractory surrounding the spiral torch flame guide 140;
A shell 100 surrounding the permanent field;
A fire pipe (110) installed to protrude to the outside at the bottom side of the iron shell (100) to shoot a torch flame;
An emission pipe 120 installed to protrude outward from the upper side of the iron shell 100 to discharge the torch flame input through the injection pipe 110; And
And; a ceramic nozzle 170 penetrating a lower center of the ceramic crucible 130 and a lower center of the iron shell 100;

The fire pipe 110, the spiral torch flame guide 140 and the fire pipe 120 is connected in a passage shape,

The torch flame introduced into the fire pipe 110 does not directly contact the ceramic crucible inner wall 160 and the ceramic nozzle 170, the preheatable tundish.
The method of claim 1,
The spiral torch flame guide 140 is a rapid preheatable tundish, characterized in that starting in the fire pipe 110 and ends in the fire pipe (120).
3. The method according to claim 1 or 2,
The spiral torch flame guide 140 is a rapid preheatable tundish, characterized in that the rising angle of 10 to 20 degrees.
3. The method according to claim 1 or 2,
The fire tube 110 is a quick preheatable tundish, characterized in that it comprises a key to the gun torch.
3. The method according to claim 1 or 2,
The fire pipe 110 and the fire pipe 120 is deflected to one of the iron shell 100 of the tundish, the fire pipe 120 is a flame that proceeds according to the spiral torch flame guide 140 Rapid preheatable tundish, characterized in that it is installed to fit in the final direction of the.

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