JPH11239847A - Ingot-making apparatus for molten metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ingot-making apparatus for molten metal, by which vacuum induction melting can be executed in high vacuum degree and the defective inclusion and the deterioration of the ingot surface state are not brought into. SOLUTION: Relating to this ingot-making apparatus of the molten steel, a melting chamber containing a vacuum induction melting furnace 2 and a casting camber 9 containing a molten steel pouring tube 3 and a casting base board 5 provided with a mold 4 are connected with a passage 10 provided with a passage shut-off mechanism 11 and in this passage, a launder 12 reciprocatively movable between the melting chamber 8 and the casting chamber 9 is disposed, a ladle 13 which opens at the upper part, and has a molten steel pouring hole 13a at the bottom part and closes this molten steel pouring hole 13a with a stopper rod 15 vertically movable, is interposed between the launder 12 and the molten steel pouring tube 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for preparing molten steel in a vacuum induction melting furnace and ingoting the molten steel, and more particularly, to greatly increase the degree of vacuum during melting.
In addition, reduction of inclusion failure in the ingot obtained by ingot casting,
The present invention relates to a molten steel ingot making apparatus capable of improving the state of a steel ingot skin.

[0002]

2. Description of the Related Art Molten steel refined by a vacuum induction melting method is ingoted under vacuum and reduced pressure. FIG. 2 schematically shows an example of a conventionally used apparatus. In the drawing, a vacuum induction melting furnace 2 tilted by a tilting device (not shown) and a casting platen 5 on which a molten steel injection pipe 3 and a mold 4 are erected are arranged in one vacuum chamber 1. I have.

[0003] The molten steel injection pipe 3 and the mold 4 are connected via a runner 5a formed in a casting platen 5, and molten steel injected from a gate 3a of the molten steel injection pipe. The molten metal flows from the lower part to the upper part of the mold 4 through the molten steel injection pipe 3 and further through the runner 5a. Further, between the melting furnace 2 and the molten steel injection pipe 3, a molten steel receiving container 6 is provided.
Is arranged. The shape of the receiving container 6 is such that the upper portion is open and the bottom is relatively deep, and a molten steel outflow nozzle 6a having a predetermined diameter is formed at a bottom portion corresponding to a position immediately above the gate 3a of the molten steel injection pipe 3 described above.

[0004] Ingot making using this apparatus is performed as follows. First, a raw material is charged into the melting furnace 2 from a raw material charging inlet 1a. Then, the vacuum chamber 1 is operated to evacuate the inside of the vacuum chamber 1 to a predetermined degree of vacuum, and the melting furnace 2 is operated to melt the charged materials. Refining by proceeding with S removal. In this case, the higher the degree of vacuum, the better the refining state.

[0005] Next, as shown in FIG. 2, the melting furnace 2 is tilted to inject molten steel 7 into a container 6.
At this time, the injection state of the molten steel 7 was observed through the viewing window 1b,
By adjusting the tilt of the melting furnace 2, an operation is performed such that the depth of the molten steel in the receiving container 6 is made as constant as possible. The molten steel injected into the receiving container 6 sequentially flows out of the molten steel outflow nozzle 6a, flows into the molten steel injection pipe 3 from the gate 3a, flows into the mold 4 through the runner 5a of the casting platen 5, and rises. Go. Then, after filling the inside of the mold 4, it is cooled and turned into a steel ingot.

[0006]

By the way, in the case of the conventional apparatus described above, during vacuum induction melting, the entire interior of the vacuum chamber 1 is reduced to a degree of vacuum necessary for melting the charged raw material that proceeds in the melting furnace 2. It is necessary to evacuate.
However, the volume of the vacuum chamber 1 is much larger than the internal volume of the melting furnace 2. Therefore, even if it is intended to perform melting at a high degree of vacuum in the melting furnace 2, the entire inside of the large-volume vacuum chamber 1 must be brought to the high degree of vacuum. However, this is quite difficult as a practical problem. For example, in the case of a vacuum chamber having an inner volume of about 130 m ^{3, the} degree of vacuum that can be obtained is 0.1 T, although it depends on the capacity of the evacuation apparatus.
orr.

In the case of the above-mentioned conventional apparatus, the molten steel is injected into the receiving vessel 6, and flows into the gate 3a from the molten steel outflow nozzle 6a without being stored there.
Since the receiving container 6 does not have a function of storing molten steel, inclusions such as oxides mixed in the molten steel also flow into the mold 4 together with the molten steel. As a result, in the obtained steel ingot, problems such as defective inclusions and deterioration of the state of the steel ingot surface may occur.

The present invention solves the above-mentioned problems in the conventional apparatus shown in FIG. 2 and can increase the degree of vacuum during smelting. It is an object of the present invention to provide a molten steel ingot making apparatus capable of suppressing the deterioration of the state.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a melting chamber for accommodating a vacuum induction melting furnace and a casting chamber for accommodating a casting platen having a molten steel injection pipe and a mold. And the casting chamber is connected by a passage provided with a passage blocking mechanism, and a rounder capable of reciprocating between the melting chamber and the casting chamber is disposed in the passage. An ingot making apparatus, wherein between the rounder and the molten steel injection pipe, an upper part is opened, a molten steel outlet is provided at a bottom part, and the molten steel outlet is sealed with a vertically movable stopper rod. The present invention provides an ingot making apparatus for molten steel, wherein a ladle is interposed.

[0010]

FIG. 1 is a schematic diagram showing the basic configuration of the apparatus of the present invention. The apparatus of the present invention includes a melting chamber 8 and a casting chamber 9 as a whole, and the melting chamber 8 and the casting chamber 9 are connected via a passage 10. The melting chamber 8 accommodates a tiltable vacuum induction melting furnace 7, and the casting chamber 9 includes
A casting platen 5 having a molten steel injection pipe 3 and a mold 4 is housed therein.

The passage 10 connecting the two chambers is provided with a passage blocking mechanism 11 for opening or closing the passage. The passage 10 has a relatively shallow, trough-shaped rounder 12 which can reciprocate between the melting chamber 8 and the casting chamber 9.
Are arranged. The following ladle 13 is interposed between the rounder 12 and the molten steel injection pipe 3.

The ladle 13 has an opening at the top, and a molten steel outlet 13a having a predetermined diameter formed at a position corresponding to the gate 3a of the molten steel injection pipe 3 at the bottom. And
The molten steel outlet 13 a is sealed by a stopper rod 15 made of, for example, graphite or alumina, which moves up and down in response to an operation signal from an actuator 14. The smelting and ingot making by this device are carried out as follows. This will be described below.

First, the rounder 12 is moved toward the casting chamber 9 as shown by the imaginary line in the figure and accommodated therein, and in this state, the passage blocking mechanism 11 is operated to bring the passage 10 into a blocked state. . With this operation, the melting chamber 8 and the casting chamber 9 are separated from each other. Then, in the casting chamber 9, the stopper rod 15 is lowered by an operation signal from the operating device 14 to seal the molten steel outflow port 13 a of the ladle 13, and the chamber is evacuated to a predetermined degree of vacuum.

Next, after charging the raw materials into the vacuum induction melting furnace 2 from the raw material charging inlet 8a of the melting chamber 8, the inside of the chamber is evacuated to a predetermined degree of vacuum, and the melting furnace 2 is operated. Perform refining. At this time, since the volume of the melting chamber 8 is extremely small as compared with the volume of the vacuum chamber shown in FIG. For example, when the melting chamber 2 is a 9-ton furnace in a type in which the chamber of the melting chamber is integrated with the furnace body, the volume of the melting chamber 8 may be about 14 m ³ , and at this time, the degree of vacuum of the melting chamber 8 Can be reduced to about 0.01 Torr.

When the smelting in the melting chamber 8 is completed, next, the passage blocking mechanism 11 is operated to open the passage 10, and the rounder 12 housed in the casting chamber 9 is moved rightward in the figure. It moves and is disposed at the position of the passage 10. Then, the melting furnace 2 is tilted to inject the molten steel 7 from one end of the rounder 12.

The injected molten steel 7 is a long rounder 12.
1 through the nozzle 12a
Flow into 3 Since the molten steel outlet 13a of the ladle 13 is sealed by the stopper rod 15, the molten steel 7
Are stored in the ladle 13. Then, while being stored for a predetermined time, the inclusions mixed in the molten steel 7 float and separate. That is, the molten steel 7 is cleaned by the killing effect.

Further, since the ladle 13 has an appropriate depth, compared to a case where the ladle 13 is cast immediately from a shallow rounder (100 to 300 mm), the inclusion into the casting flow of inclusions due to turbulence of molten steel at the time of casting. Entanglement reduction is also possible.
Next, the stopper rod 15 is raised by an operation signal from the actuator 14 to open the molten steel outlet 13a.

The molten steel 7 which has been cleaned by the killing flows into the molten steel injection pipe 3 from the gate 3a, and fills the mold 4 through the runner 5a of the casting platen 5. The stopper rod 15 is moved down by the operation signal from the operating device 14 before the inclusions that are floating and separated are likely to flow out of the molten steel outlet 13a, thereby sealing the molten steel outlet 12a. Therefore, since inclusions are not mixed in the steel ingot formed by the mold 4, the inclusion defect does not occur, and the state of the ingot surface is also good.

In the case of the apparatus of the present invention, the amount of vertical movement of the stopper rod 15 can be adjusted by the operation signal of the operating device 14, so that the opening of the molten steel outlet 13a can be adjusted. Therefore, the casting speed of molten steel from the gate 3a can be arbitrarily changed.
When the level of the molten steel cast into the feeder approaches the feeder portion, the opening of the molten steel outlet 13b is reduced by the operation of the stopper rod 15 to reduce the casting speed, that is, the rising speed of the mold 4 in the mold 4. The cooling of the molten steel in the vicinity of the feeder surface can be slowly advanced to suppress the occurrence of pipe-like defects in the steel ingot.

[0020]

As is apparent from the above description, in the apparatus of the present invention, the melting chamber and the casting chamber are separated and independent, and the internal volume of the melting chamber is significantly smaller than that of the vacuum chamber of the conventional apparatus. Therefore, the degree of vacuum during melting and refining can be greatly increased. Moreover, since the ladle has a storage function for the molten steel injected, it is possible to float and separate inclusions mixed in the molten steel. Therefore, only clean molten steel can be cast into the mold, and as a result, an ingot with no inclusion failure and a good ingot skin condition can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a basic configuration of a device of the present invention.

FIG. 2 is a schematic diagram showing a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum chamber 1a, 8a Raw material loading port 1b Peep window 2 Vacuum induction melting furnace 3 Molten steel injection pipe 3a Mouth of molten steel injection pipe 4 Mold 5 Casting surface plate 5a Runner of casting surface plate 5 6 Receiving container 6a Receiving container 6 Nozzle of molten steel 7 Molten steel 8 Melting chamber 9 Casting chamber 10 Passage 11 Passage shutoff mechanism 12 Rounder 13 Ladle 12a Molten steel outlet of ladle 13 14 Actuator 15 Stopper rod

Claims (1)

[Claims] 1. A melting chamber for accommodating a vacuum induction melting furnace and a casting chamber for accommodating a casting platen provided with a molten steel injection pipe and a mold are connected by a passage having a passage blocking mechanism, And, in the passage, a molten steel ingot apparatus in which a rounder capable of reciprocating between the melting chamber and the casting chamber is disposed, wherein between the rounder and the molten steel injection pipe is provided. A molten steel ingot apparatus, characterized in that a ladle having an opening at the top, a molten steel outlet at the bottom, and the molten steel outlet closed by a vertically movable stopper rod is interposed. .