JPH02169158A - Tundish and continuous casting method using it - Google Patents

Abstract

PURPOSE:To improve the quality at joint part at the time of changing the metal kind by providing opening/closing means parting a molten metal receiving vessel into plural chambers, connecting each chamber and a molten metal pouring vessel with passage providing opening/ closing means and making at least one of the opening/closing means electromagnetic induction device. CONSTITUTION:At the time of continuously casting the steel A, the opening/closing means 3, C1, C2 are opened and the molten steel is poured into molds from the molten metal receiving vessel 1 through the molten metal pouring vessel 2 and nozzles 5. When supply of the molten metal steel in a ladle L1 comes to end stage, the opening/closing means 3 and C1 are closed and the casting of the molten steel in the chamber R2 is continued. Components of the steel A in the chamber R1 is adjusted. When supply of the molten steel in a lade L2 completes, the passage C2 and the nozzles 5 are closed, and the opening/closing means 3 is opened. The passages C1, C2 are opened and the molten steel in the molten metal receiving vessel 1 and the molten metal pouring vessel 2 is circulated with the electromagnetic induction device 41 to change to the steel B. The pouring nozzle 5 is opened to execute the continuous casting of the steel B. The component adjustment at the time of changing the steel kind is executed for short time, and at the time of changing to the different steel kind, the casting can be executed without deteriorating the quality at the joint part.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a tundish used for continuous casting of molten metal, and a method for continuously casting different types of steel using the tundish.

(Conventional technology and its problems) The continuous casting method has many advantages such as saving energy and improving yield.
It is a highly profitable casting method, and has been widely used for casting rope, copper, aluminum, and other metals.Recently, continuous casting of sea bream, in particular, involves heating water from multiple ladles one after another and using the same method. Not only continuous casting of steel types, but also different steel types (
Continuous casting of different types of steel is also being carried out, and the productivity of slabs is greatly improving.

During continuous casting, hot water (molten metal) from a ladle is first received in a tundish, and then poured into a mold by an injection nozzle from the tundish. The tandaitsu not only plays an important role in storing hot water and keeping the conditions for pouring it into the mold constant, but it has also recently been proposed that the hot water be refined and its composition adjusted here (
For example, Japanese Patent Publication No. 56-39366, No. 62-21
Publication No. 2044).

As mentioned above, continuous casting has recently been trending, but this has the following problems. (Hereinafter, continuous casting of steel will mainly be described as an example.) ■ In the case of continuous casting of the same type of steel, at the end of the supply of hot water from one ladle, the hot water in the tundish will decrease and the tundish will be moved from the tundish to the mold. This causes slag to flow into the slab and deteriorates the quality of the slab joints.

■ In the case of continuous casting of different steel types, if the previous steel A is completely poured, the quality of the slab will deteriorate due to the outflow of slag. If the previous steel A is left behind and the next steel @B is fed, different steel types will be mixed and the steel will have a composition different from that of the intended steel B.

Regarding the problem (2), one solution is disclosed in "Materials and Processes", Vol. 1, No. 1 (198B), page 304. That is, the tandate is divided into two parts, one on the receiving side and one on the injection side.
This method uses an H-shaped tundish with two tanks connected by a single passage. In conventional tundishing, molten steel is delivered and received in the same tank, so the influence of the slag that flows out at the end of the first injection tends to reach the mold and slab. In order to adopt a two-tank structure with a partitioned tank on the injection side,
It is possible to eliminate the adverse effects of the slag in the treadmill, and to keep the amount of molten steel in the tundish at a constant level with the molten steel supplied from the rear ladle by injecting at the time of two strands, and to minimize the outflow of slag at the end of the first part. This makes it possible to prevent quality deterioration at the seam.

However, even if the above-mentioned H-shaped tundish is used, problem ① cannot be solved. In other words, in the case of continuous casting of different steel types, the previous steel must be completely poured, and the influence of slag outflow is unavoidable, even if the previous fI4
When pouring the next steel, leaving A in place, it is necessary to stop pouring into the mold for a predetermined period of time and adjust the composition in the tundish, but with the above equipment, this process takes time.
Continuous casting becomes virtually impossible.

(Problems to be Solved by the Invention!!) The present invention provides a tundish that is suitable for continuous casting of molten metal, particularly continuous casting of different types of metal, and uses the tundish to switch steel types. The object of the present invention is to provide a new continuous AVL manufacturing method for continuous casting of different steel types without the above-mentioned problems.

(Means for Solving the Problems) FIG. 1 is a schematic perspective view showing the concept of an example of a tundish of the present invention, and FIG. 2 is a detailed plan view showing the same.

The tundish of the present invention has an independent hot water receiving tank l and a hot water pouring tank f.
! 12, which are connected by two passages (C1°C1). The hot water receiving tank 1 is equipped with an opening/closing means (preferably an electromagnetic induction device) 3, and this device partitions the hot water receiving tank 1 into two chambers (R+, Rg) as necessary, and allows hot water in one chamber to flow into the other. It has the function of blocking the inflow.

The passages (C+, Cm) connect the chambers R and R□ to the pouring tank, and are provided with opening/closing means 4+ and 4g, respectively. This opening/closing means may be mechanical, but as will be described later, since it is necessary to circulate hot water between the receiving tank and the pouring tank, it is preferable to use an electromagnetic induction device similar to 3.
In order to circulate and mix this hot water, the above-mentioned hot water tank opening/closing means 3
, passage opening/closing means 41°4. At least one of them! Must be a magnetic induction device.

The pouring tank 2 has a pouring nozzle 5 equipped with a normal stopper, through which pouring is carried out into the mold. is not limited to two.

Hot water is supplied to chambers R1 and R8 of the hot water tank from separate ladles. The ladle can be placed above the receiving tank using a crane or other equipment.

Next, a second invention of the present application, which is a method for continuous casting of different steel types using the above-mentioned tundish of the present invention, will be explained.

FIG. 3 is a schematic diagram showing the steps of this method.

This is a process of continuously casting steel A (A means a steel type with a certain composition). IIA is supplied with 1% hot water from L+ and L2 to chambers R1 and i of the hot water tank 1 of Tandaitsu, respectively.
is poured into a mold 6 (see FIG. 2) through a pouring tank 2 and a nozzle 5. At this time, the opening/closing means 3 and the passage Nt c
r and C2 are in the "open" state.

When the supply of hot water from the ladle L1 reaches its final stage, the opening/closing means 3 is closed to partition the chambers R+ and h. Close passage C8 at the same time so that the hot water level in room R8 does not fluctuate.

(In this state, continue supplying hot water from the line A from the ladle L1 to the passage C8 and through the nozzle 5 of the pouring tank 2.)
Continue casting lA.

Since the previous preparation A remains in the chamber P1, the composition is adjusted by adding ferroalloy and other additives to the chamber R8.This adjustment is done by closing the nozzle 5 in the next step When the hot water tank and note? lf'! In consideration of the total amount remaining in the steel, this is done so that the total amount will have a composition of mB when circulating and mixing in step 2. However, it is possible to adjust the composition in step 2, so this step The component adjustment may be preliminary.

In this step, since the chambers R1 and R1 are separated by the opening/closing means 3, IIA in the chamber R1 is not affected by the additive.

Component adjustment in room R3 and its f! Approximately 7~
Although it takes 25 minutes, the time required for hot water supply from one ladle is usually 30 to 40 minutes, so if you choose the timing to start hot water supply from intake H4t, t, during the component adjustment in room R1,
Casting of Steel A never stops.

After finishing hot water supply of steel A from the ladle, make sure that the hot water level does not change in the passage C! and close nozzle 5°.

Then, the opening/closing means 3 is opened.

The passages C, , Ct are opened and the hot water receiving tank N1 and pouring tank 2 are opened.
Circulate the hot water inside. This circulation is performed by opening/closing means 3 or 41.4! If all of these kings are electromagnetic induction devices, the circulation efficiency will be high (
Naru, the hot water is as shown in the diagram! It circulates between both vessels via sc+-Cm. The hot water is sufficiently stirred by circulating about three times, and the hot water in the hot water receiving tank and the hot water pouring tank becomes uniform IIB. The time required for this is, for example, the hot water capacity 130
'> (Total of molten metal receiving tank and molten pouring tank) tandaishu,
When the circulation speed is 150 t/min, it takes about 3 minutes. Note that the composition can also be adjusted by adding additives such as ferroalloy. During this time, a casting block is placed in the mold to serve as a partition between IiA and rope 8. Also, ladle 5, a ladle containing sea bream B instead of Lm! , L, are placed above the chamber R1, P.

Continuous casting of steel B is started by opening the injection nozzle 5. At this time, the opening/closing means 3 is opened and the passages C5,
C1 is also in an open state. IIB is supplied with hot water in predetermined amounts from ladle 1 and L4.

As described above, continuous casting of a different steel type from steel A to steel B is smoothly performed through the steps from ① to ②. When switching from steel B to steel A again, or when changing to another steel type C, the steps from (1) to (2) may be repeated.

In the above-mentioned continuous casting method of the present invention, what is important is to always keep the molten metal level in the receiving tank and pouring tank constant during stirring. If the hot water level is constant, partitioning and circulation using a magnetic induction device can be carried out industrially with extremely low power consumption.

In the tundish of the present invention, the hot water tank is divided into two chambers,
Moreover, since each of them has an individual passage that can be opened and closed, the level of the hot water can be easily adjusted.

Another feature of the different-tuned continuous casting method using the tundish of the present invention is that the composition adjustment when changing the sea bream stock can be carried out in an extremely short time.

When changing steel types, a casting block is inserted after the previous steel type has been cast, but the slab is still being drawn out during this time. Depending on the size of the mold and casting speed, the casting block charging process usually takes 2 to 30 minutes.
It must be completed in 3 minutes, and during that time, the composition adjustment for the next steel type must be completed.If you cast hot water whose composition has not been completely adjusted, that part will have to be discarded later, which will reduce the yield. According to the method of the present invention, in the steps (1) and (2), the composition adjustment is carried out quickly, and it is possible to complete the composition adjustment during the charging work of the casting block. can.

In addition, in steps (1) and (2), it is also possible to further speed up the stirring by, for example, blowing inert gas (bubbling) from an immersion lance.

According to the above-mentioned casting method using the tundish of the present invention, as compared to the conventional method, the quality deterioration due to fluctuations in the melt level, slag inclusion, and the decrease in yield due to discarding defective parts are significantly reduced.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Example] Steels A and IIB shown in the table below were continuously cast by using the tandem sheets shown in FIGS. 1 and 2.

Table (composition of class, wt%) (Hereafter, margin) , set j01 yuan Capacity of Tandaitsu hot water tank 1: 40 tons.

Capacity of tundish pouring tank 2...40 toshi passage CI
, Inner diameter of C1...300■■φ Opening/closing means 3 and 4
1.4. The following electromagnetic induction device i) Number of coils: 12 (
Coil cooling air cooling, heat resistance 500℃) ii) Duct material: Sialon-BN iii) Capacity: 210kw, circulation capacity 150 t＞/win■ (+) Capacity 200 ): / no tori! at,,,Lo(
Semi-parallel pouring is performed from the
Once hot water supply from the tank was completed, it was moved by the upper crane. A charge is applied to the opening/closing means (electromagnetic induction device) 3, which was not charged at this point, and the chamber R1 is opened in the receiving tank 1.
In addition to stopping the flow of molten steel between chamber R8 and chamber R8,
, the opening/closing means (electromagnetic induction device) 41 was closed to stop the flow of molten steel into and out between the chamber and the pouring tank 2.

(2) Meanwhile, from the ladle of the same capacity, to the chamber R of the receiving tank.
, the supply of hot water from IIA continued, and casting continued at a pouring speed of 7 tons and 7 minutes from passage C8 to pouring tank 2 into the mold.

Electromagnetic induction device 3.4. It took about 30 minutes from the time the engine was started until the tank was empty.

(2) After charging the if magnetic induction device 3.41, use metal manganese (99.9% Mn) and 0 kg of steel for component adjustment.
into the molten steel (20) 1) in chamber R1, and AhOs9
Bubbling was carried out for 2 minutes at 501/min using a immersion lance with a stable coating.

After this operation, the hot water was sampled and analyzed to confirm its components. During this time, a total of 7 minutes was required, including 2 minutes for scouring and 5 minutes for product confirmation.

When the temperature was measured at the same time, the temperature drop of the molten steel was 10°C, but ultimately there was no problem with casting, and no heating of the molten steel was performed.

(4) When the ladle is finished pouring, the sliding gate of the pouring nozzle 5 under the pouring tank 2 is closed to prevent the level of the molten metal in the pouring tank from dropping, and a casting block is installed in the mold. I entered. The time required was 3 minutes.

(5) Next, the opening/closing means (1 [induction device) 3] of the receiving tank and the opening/closing means (1ft magnetic induction device) 41 of the passage C1 are opened to uniformly mix the inside of the tundish. electromagnetic induction device 43.4 for passages C+ and Ct;
A charge of 70 kW was applied to each of the tubes, and the molten steel was circulated clockwise at a rate of 150 minutes per minute. Three cycles were completed in 2 minutes, and the components were homogenized to become Steel B.

(6) Therefore, the opening/closing means (electromagnetic induction device) for the receiving tank l and the passages C1, C, 3.4 and 4. The charge on the injection nozzle 5 is released, and the sliding gate of the injection nozzle 5 is opened. At the same time, the ladle (I[B
250', housing), the supply of hot water to the chamber R1 of the hot water receiving tank was started, and casting was continued.

During (1) to (6) above, the level of the molten metal in the pouring tank 2 remained at a constant level with only slight fluctuations. Therefore, almost no slag entered the mold (the casting conditions were also kept constant, and slabs with no quality deterioration were stably obtained).

(Effects of the Invention) The explanation above has mainly been given using continuous casting of different steel types as an example, but the tundish of the present invention has an excellent property of not deteriorating the quality of the joint when changing the ladle even in continuous casting of the same steel type. be effective. In addition, refining within Tanditshu,
This can be done while casting continues.

The tandaitsu of the present invention is not limited to continuous casting of steel.
It can be used for continuous casting of copper, aluminum, and many other metals, and is extremely useful industrially because it can produce high-quality slabs at a high yield.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view showing the concept of the tundish of the present invention, Fig. 2 is a schematic plan view showing details of the tundish of the present invention, and Fig. 3 is a diagram illustrating the continuous casting method of different steel types of the present invention. in,
■～■correspond to the process.

Claims (2)

[Claims] (1) A tundish that has an independent molten metal receiving tank and a molten pouring tank, and the two tanks are connected by a plurality of passages each having an opening/closing means, and the molten metal receiving tank has the same number of tanks as the passages. The plurality of passages each lead from the same number of chambers of the receiving tank to the pouring tank, and at least one of the opening/closing means for the passages and the opening/closing means for the receiving tank is an electromagnetic induction device. A tandate for continuous casting characterized by the following. (2) A continuous casting method of different steel types using a tundish according to claim 1, characterized in that the following steps [1] to [6] are repeated. [1] Process of continuously casting steel A while supplying hot water into two chambers (R_1, R_2) of the receiving tank from separate ladles (L_1, L_2), [2] From one ladle (L_1) At the end of hot water supply for Steel A, the opening/closing means of the hot water tank is closed to partition the hot water tank, the passage (C_1) connecting chamber R_1 and the pouring tank is closed, and continuous casting of Steel A is continued by only supplying hot water to chamber R_2. Process, [3] Room R_
[4] Supplying steel A from ladle L_2 to room R_2; [4] Supplying steel A from ladle L_2 to room R_2; When the process is completed, the partition by the opening/closing means of the molten metal receiving tank is released, and the passage (C_2) connecting the chamber R_1 and the pouring tank is closed with the molten metal pouring from the molten metal pouring tank to the mold blocked, and the molten metal level in the molten metal receiving tank is closed. [5] Opening the passages C_1 and C_2, circulating and stirring the hot water in the receiving tank and the pouring tank by the at least one electromagnetic induction device, during which time the casting block is inserted into the mold, and the steel a step of preparing ladles L_3 and L_4 containing B on chambers R_1 and R_2, respectively, [6]
The process of restarting pouring from the pouring tank into the mold and performing continuous casting of Steel B.