KR20040056928A - Ingredient deflection decrease equipment for cast metal pin iron and the decrease method thereof - Google Patents

Abstract

PURPOSE: An apparatus and a method for decreasing ingredient deflection of pig iron for casting are provided to lower cooling rate of the surface of side part and lower part on which pig iron is contacted with the mold by preheating mold and suppress concentration of silicon and carbon on the surface by rapid cooling the surface of an upper part of the mold using nitrogen. CONSTITUTION: The apparatus comprises mold heating means(10) installed at an input side of molds(4) of strand(3) into which molten iron is supplied to uniformly distribute carbon and silicon in pig iron; inert gas injection means(20) installed in rear of the mold heating means to form a stabilized compound protection layer on the surface of the molten iron supplied to the molds by injecting an inert gas; air injection means(30) for injecting an external air and mist spray means(20) for spraying mist sequentially installed in rear of the inert gas injection means to stabilize the compound protection layer and maintain uniform cooling; and cooling water injection means(50) installed in rear of the mist spray means to finally cool a product, wherein at least two or more of burners are installed at the mold heating means with the burners being spaced apart from each other in a certain distance.

Description

Infrared deflection decrease equipment for cast metal pin iron and the decrease method

The present invention relates to a device for reducing component deviation of foundry pig iron and a method for reducing the same. More specifically, since solidification proceeds from the outside during the cooling of the molten iron of foundry pig iron, carbon [C], silicon [ Si], manganese [Mn], sulfur [S], phosphorus [P] are not evenly distributed inside pig iron, and are suppressed from being pushed to the last solidified core and upper surface and impurities inside pig iron, especially carbon and silicon The present invention relates to a device for reducing component deviation of foundry pig iron and to a method for reducing the same.

In the manufacture of pig iron for casting, after analyzing the components of the molten iron produced in the blast furnace, in order to increase the content of silicon (Si), additional addition of Fe-Si is poured into the mold and cooled to a certain shape. It means manufacturing with pig iron. Since the solidification proceeds from the outside during the cooling of the molten metal poured into the mold, carbon (C), silicon (Si), manganese (Mn), sulfur (S), phosphorus (P), etc., which correspond to impurities, are evenly distributed inside pig iron. It is not distributed and is pushed to the last solidified central and upper surfaces.

Therefore, there is an urgent need for a technique for adjusting the cooling pattern of the pig iron to suppress the phenomenon that the components corresponding to the impurities are pushed to the center and the surface and to evenly distribute the impurities, particularly carbon and silicon, in the pig iron.

In the conventional cast iron manufacturing process, the component specification of pig iron for casting product manufacturing is in the range of 3.5% or more carbon and 1.4-1.8% silicon. The carbon content of pig iron produced in the blast furnace is 4.3 ~ 4.5%, which is completely saturated, and no additional component adjustment is needed.However, in the case of silicon, it is 0.4% on average, and the component discharged from the blast furnace to meet the target range of 1.4 ~ 1.8%. The amount of silicon should be injected by analyzing the difference.

At this time, in order to increase the additional efficiency of the silicon as shown in Figure 1 when the waste is contained in torpedo car (Torpedo Car) (1) by adding the temporary regulation using the temporary regulation system (2) at the same time to vortex So that the temporary regulation can be sufficiently dissolved.

After inputting the target provisional regulation, the topedoca (1) is transferred to the main liner and the mold (4) is poured into strands (3) to which the mold 4 is continuously connected. After storage, cool down to room temperature and transport.

On the other hand, in order to supply the molten metal from the topedoca (1) to the mold 4 as shown in Figure 2 by inclining the torpedo car (1) poured into the induction tube (1a) and put in the mold (4) To do that. The mold 4 is connected to the chain to rotate in the form of a conveyor for continuous operation in the form of a top open bowl, which is called a strand.

The molten water contained in the mold 4 proceeds according to the rotation of the strand 3 while maintaining the air-cooled state (A) at the mouth side, and the primary spraying water (B), which maintains a small amount of watering water, and a large amount of watering water. After the second watering (C), and after passing through the Pan Conveyor (D) to the air cooling yards (F) and then through the third watering (E).

At this time, looking at the cooling temperature of each process, the air cooling step (1300 ℃) (A), the first watering (1200 ℃) (B2) of the strand 3 in the waste water stage of 1500 ℃, that is, topedoca (1) (700 ° C.) (C) Fan Conveyor Air-cooled (650 ° C.) (D) Yard Wetting followed by sprinkling (300-500 ° C.) (F).

The problem of the conventional method for manufacturing pig iron for casting is, firstly, the pig iron product due to the sudden expansion of moisture caused by pouring the molten metal into the mold without completely removing the water adhered to the surface of the mold at the lower end of the strand. Deterioration of the shape and low temperature of the mold has a problem that the cooling of the molten metal poured into the mold proceeds rapidly from the mold surface.

Second, since the cooling state is maintained in an air-cooled state until it meets the first sprinkling water, there is a problem in that carbon and silicon are locally concentrated on the upper surface due to slow cooling at a cooling rate of 116 ° C. per minute.

Third, since the surface is bent by water sprayed from the top because the high temperature is maintained until just before the first watering, the surface area of the carbon and silicon layers is increased, so that rust occurs during long-term storage.

For reference, since the general storage place of pig iron is an outdoor yard, carbon and silicon on the surface easily react with moisture, change to rust, and then detach from the surface. In particular, the rust generated by the silicon is similar to dried ocher, so it is easily removed from the surface of the product, leading to significant loss of silicon.

The present invention has been invented to solve the above problems, the object of which is to prevent rapid cooling at the interface between the mold and the metal contact, to suppress the phenomenon of concentrated carbon and silicon to the upper surface, and to store for a long time The present invention provides a device for reducing component deviation of cast iron, and a method of reducing the same, so that the silicon content adjusted in the manufacturing process of the pig iron is kept constant until the final use stage by preventing rust and the like from occurring on the surface of the drawings.

1 is a schematic view showing a pig iron manufacturing process for casting,

Figure 2 is a schematic diagram showing a conventional pig iron cooling process for casting,

3 is a schematic view showing a pig iron cooling apparatus for casting according to the present invention,

Figure 4 is a graph showing a cast iron cooling flow according to the present invention.

※ Explanation of symbols on main parts of drawing ※

10: mold heating means 11: burner

20: inert gas injection means 30: air injection means

40: mist spray means 50: cooling water spray means

In the characteristic technical configuration of the present invention for achieving the above object, the method for reducing the component deviation of pig iron for casting, heating the mold inlet side of the strand to be supplied with iron to uniformly distribute the carbon and silicon in pig iron; Spraying inert gas to supply the molten metal to the heated mold and form a stable compound protective layer on the surface of the molten metal; Sequentially performing external air and mist injection to stabilize the compound protective layer and maintain uniform cooling; Spraying the cooling water at a high pressure on the surface of the product made of the uniform cooling. The heating means of the mold is a burner and its heating temperature is 400 to 500 占 폚.

In addition, the characteristic technical configuration of the element deviation reduction device of the cast iron for casting according to the present invention, the mold on the entrance side of the mold (4) of the strand (3) to be supplied with iron in order to uniformly distribute the carbon and silicon in the pig iron A mold heating means 10 is installed to heat the mold, and an inert gas injection means 20 for injecting an inert gas to form a stable compound protective layer on the surface of the molten metal supplied to the mold is installed at the rear of the mold heating means. In order to stabilize the compound protective layer and maintain uniform cooling, the air spraying means 30 for spraying external air and the mist spraying means 50 for spraying mist are sequentially installed at the rear of the inert gas spraying means. Behind the mist injection means is a cooling water injection means 50 is installed for the final cooling of the product.

In addition, the mold heating means 10 is installed so that at least two or more burners 11 maintain a constant interval, and the inert gas spraying means 20, air spraying means 30, mist spraying means 40 ), The coolant injection means 50 is provided on the mold 4, and they are provided with two or more injection nozzles, respectively.

Hereinafter, with reference to the accompanying drawings, a device for reducing component deviation of the cast iron of the present invention and a method for reducing the same will be described in detail.

The present invention is a mold heating means for first drying the moisture in the mold (4) in the lower part of the mouth (the side where the waste water is injected into the mold 4) of the strand 3 and heating the mold 4 to 400 ~ 500 ℃ ( 10), the mold heating means 10 may be used by installing a heater using electricity, but it is most preferred to use the burner (11). Therefore, in the present invention, a plurality of burners 11 are installed at regular intervals.

The reason why the mold 4 is heated to 400 to 500 ° C. is to maintain the temperature of the mold as high as possible within the range that the strength of the mold and the iron recrystallization temperature are not reached.

However, the strand (3) is made by weaving the mold (4) in the form of a small bowl with a chain to form a belt conveyor to wind and install the drive roller and the return roller installed at a certain distance by weaving the mold (4) in a chain Refers to a device that continuously returns and rotates a belt conveyor.

As described above, when the moisture of the mold 4 is removed and the temperature is heated to 400 to 500 ° C., the molten water of the topedoca 1 is injected into the mold 4 through the induction tube 1a and then the inert gas. Nitrogen gas is injected through the nozzle of the injection means 20. The reason for injecting nitrogen gas, which is an inert gas, on the surface of the molten metal is to block external air and form a stable compound protective layer.

On the other hand, the nozzle which is the inert gas injection means 20 for injecting the nitrogen gas is preferably installed at the same time to maintain at least two or more constant intervals along the direction of rotation of the strand 3, that is, the mold 4 is injected at the same time. .

When an inert gas is injected into the waste water supplied to the mold 4 to form a stable compound protective layer, the air spraying means 30 and the mist spraying means are sequentially installed in order to stabilize the compound protective layer and maintain uniform cooling. Use 40 to inject external air, followed by a mist (injecting water in the form of a mist).

Again, like the inert gas spraying means 20, it is injected from the nozzle which is the air spraying means 30 and the mist spraying means 40, and the nozzle is a direction in which the mold 4 moves behind the inert gas spraying means 20. Along the at least two are installed to maintain a constant interval is sprayed at the same time.

After the mist spraying, the cooling water is sprayed by using the nozzle which is the cooling water spraying means 50, thereby the final cooling of the produced product is performed.

In addition, in order to cool the upper surface of the molten metal using nitrogen and air as quickly as possible, a fixed nozzle is installed on the upper portion of the strand 3 to cool the upper portion of the molten metal as the strand 3 progresses, and in particular, nitrogen is injected. The cover is installed in the section to create an inert atmosphere by nitrogen gas.

Since the rotation speed of the strand 3 is in the range of 10m per minute, it is possible to calculate the cooling time according to the nozzle installation section. In the 5m section from the tail of the water fall, i.e., the strand (3), the discharge pressure of nitrogen is maintained at a minimum atmospheric pressure of + 2kg / cm2 or more, cooled for 0.5 minutes, and at the same time, a reactant is formed on the surface. Install an air spray nozzle of / cm2 or larger to ensure sufficient cooling of the top of the water for 2 minutes.

To spray the first watering stage, that is, mist, install a tail tail nozzle with a good ability to mist water in a 5m section. Maintain water pressure above 2kg / cm2 for smooth mist formation.

Hereinafter, the present invention will be described with reference to Examples.

4 is a view showing an embodiment of the present invention, as the mold is pre-heated in comparison with the conventional pig iron cooling rate, the cooling rate is reduced at the interface with the mold, the upper surface is cooled faster than the conventional method, the overall cooling rate is Similar adjustments can be seen.

In addition, by changing to the mist spray, which is the first watering step, the cooling temperature may be lowered to such an extent that the reaction of the product surface does not proceed in the strand 3.

The nitrogen injection section is provided with a cover and a chain curtain is installed at the tip of the cover so that an inert atmosphere by nitrogen is sufficiently formed inside the cover.

The cooling time of each section will change slightly depending on the running speed of the strand (3), but if the average strand moving speed is assumed to be 10m / sec, the cooling time is 0.5 minutes for nitrogen cooling, 2 minutes for high pressure air cooling, In the case of mist cooling, the cooling time is 1 minute.

Compared with the conventional cooling rate according to the conventional air cooling, the average temperature drop of 116 ℃ / min, while in the present invention, by the nitrogen and high pressure air has an average temperature reduction rate of 196 ℃ / min. This is a similar overall distribution of cooling as compared to the cooling rate of 200 ~ 250 ℃ / min by spraying.

As described above, according to the present invention, the cooling rate of the surfaces (side and bottom) where pig iron and the mold come in contact with the preheating of the mold is lowered, and the rapid cooling of the upper surface by nitrogen causes the concentration of silicon and carbon to be pushed to the surface. It has a suppressing effect.

In addition, in an inert atmosphere, nitrogen, silicon and titanium on the surface of the metal react to form SiN and TiN, which are stable compounds as shown in Equation 1 below.

Si + 1 / 2N2 SiN, Ti + 1 / 2N2 TiN ------- (Equation 1)

The SiN and TiN are both compounds having a high melting point, and the compound layer grows according to the cooling rate from the outside, and has a characteristic of increasing thickness. Since the coating film on the surface needs to be formed uniformly and stably, the 20m section after nitrogen cooling maintains the cooling rate of the surface by maintaining the air spray at the appropriate pressure (atmospheric pressure + 1.0 kg / cm2), thereby maintaining the surface cooling rate. It has the effect of growing a TiN compound film. Therefore, by forming a stable coating layer on the surface it is possible to exclude the possibility of rust caused by atmospheric moisture or rain.

In addition, the change of the primary spraying from the general spraying to mist spraying is to prevent the possibility that the coating layer on the surface may be destroyed when the water is boiled when spraying on the upper part of the hot pig iron. Through mist spraying, the temperature of pig iron is lowered to a stable temperature to prepare for the second spraying stage, which is a full spraying stage.

In summary, in the manufacture of pig iron for casting, cooling of the molten iron proceeds from the interface (side, bottom) with the conventional mold so that the front surface maintains cooling at a similar speed as the upper surface was later cooled down. Therefore, the important components in the production of cast products of carbon and silicon concentrated on the surface and lost in the form of rust, etc. can be uniformly retained inside the pig iron in the original content without loss in the pig iron and stable to the surface of the product. Forming a protective layer has the effect of increasing the added value of the product with a beautiful appearance compared to ordinary pig iron.

Claims (5)

Heating the mold mouth of the strand to which the molten metal is to be supplied to uniformly distribute the carbon and silicon in the pig iron; Spraying inert gas to supply the molten metal to the heated mold and form a stable compound protective layer on the surface of the molten metal; Sequentially performing external air and mist injection to stabilize the compound protective layer and maintain uniform cooling; The method of reducing the component deviation of pig iron for casting consisting of the step of spraying the cooling water at a high pressure on the surface of the product made uniform cooling. The method of claim 1, wherein the heating means of the mold is a burner and its heating temperature is 400 to 500 ° C. In order to distribute the carbon and silicon inside the pig iron uniformly, a mold heating means 10 is installed at the inlet side of the mold 4 of the strand 3 to be supplied with the molten water, and behind the mold heating means. Inert gas injection means 20 is provided for injecting inert gas to form a stable compound protective layer on the surface of the molten metal supplied to the mold, and in order to stabilize the compound protective layer and maintain uniform cooling behind the inert gas injection means. The air spraying means 30 for spraying external air and the mist spraying means 40 for spraying the mist are sequentially installed, and the cooling water spraying means 50 for the final cooling of the product is installed at the rear of the mist spraying means. Component deviation reduction device of cast iron for casting characterized in that. 2. The apparatus of claim 1, wherein the mold heating means is installed so that at least two burners (11) maintain a predetermined interval. The method of claim 1, wherein the inert gas spraying means, air spraying means, mist spraying means, cooling water spraying means are installed on a mold, they are reduced in the component deviation of pig iron for casting, characterized in that two or more injection nozzles are provided Device.