JP2002030331A - Vacuum degassing apparatus and vacuum degassing treating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum degassing apparatus and vacuum degassing treating method with which molten metal in a ladle can positively be stirred during the vacuum degassing treatment and the degassing treatment can efficiently be performed. SOLUTION: This vacuum degassing apparatus is provided with a degassing vessel 10 connected with a pressure reducing device 19 and constituted so as to be able to reduce the pressure in the inner part and plural sets of immersion tubes 21, 22 arranged at the bottom part 12 of the degassing vessel 10, and constituted so as to dip the immersion tubes 21, 22 into the molten metal 8 in the ladle 3, introduce the molten metal 8 into the inner part of the degassing vessel 10 from one side of the immersion tube 21 and return back into the ladle 3 from the other side of immersion tube 22 after degassing. The immersion tubes 21, 22 are arranged so as to be relatively shiftable to the ladle 3 and constituted so as to stir the molten metal 8 in the ladle 3 with this shifting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum degassing apparatus for performing a degassing process on a molten metal in a manufacturing process of a metal product.

[0002]

2. Description of the Related Art In a process of manufacturing a metal product, a degassing process for removing a gas harmful to quality such as hydrogen and oxygen contained in a molten metal is performed. As a degassing method,
There are various methods, one of which is a vacuum circulation degassing method (RH) in which a molten metal is circulated between a ladle and a vacuum vessel.
Is widely used.

As an apparatus for performing the vacuum circulation degassing method, there is a vacuum degassing apparatus 9 as shown in FIG. The vacuum degassing device 9 includes a degassing tank 90 as shown in FIG.
And two dip tubes 2 provided at the bottom of the degassing tank 90.
The immersion tubes 21 and 22 are immersed in the molten metal 8 in the ladle 3, and the molten metal 8 is introduced into the degassing tank 90 from one immersion tube 21 and degassed. It is configured to return to the ladle 3 from the rear other immersion tube 22.

The upper opening of the ladle 3 is sealed by a flange 95 disposed below the degassing tank 90 so that no harmful gas such as oxygen enters the molten metal from the outside. I have. In addition, the ladle 3 is provided on the flange 95.
A supply pipe 78 for supplying the inert gas 7 is provided inside the ladle 3, so that the atmosphere inside the ladle 3 is maintained at an inert gas atmosphere.

[0005] In the vacuum degassing device 9, an inert gas 7 is blown into the immersion tube 21 to guide the molten metal 8 from one immersion tube 21 into the degassing tank 90. As a result, a so-called air lift pump function is obtained, and the molten metal 8 is supplied into the upper degassing tank 90.

[0006]

In order to efficiently degas the molten metal 8 in the ladle 3, it is desired that the molten metal 8 flows sufficiently in the ladle 3 to be in a uniform state. . In the conventional vacuum degassing device 9, the molten metal 8 in the ladle 3 is caused to flow by sucking and discharging the molten metal 8 from the immersion tubes 21 and 22. However, there is a case where a sufficient flow of the molten metal is not necessarily obtained only by the flow caused by the suction and the discharge of the molten metal from the immersion tubes 21 and 22. In this case, it is difficult to efficiently perform the degassing process.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and it is possible to actively stir a molten metal in a ladle during a vacuum degassing process, and to efficiently perform a degassing process. It is an object of the present invention to provide a vacuum degassing apparatus and a vacuum degassing method capable of performing the above.

[0008]

According to a first aspect of the present invention, there is provided a degassing tank connected to a decompression device and configured to be able to depressurize the inside, and a plurality of immersion tubes provided at the bottom of the degassing tank. The immersion tube is immersed in the molten metal in the ladle, the molten metal is introduced from one immersion tube into the degassing tank, degassed, and then returned to the ladle from the other immersion tube. In the vacuum degassing apparatus, the immersion pipe is provided so as to be relatively movable with respect to the ladle, and is configured so that the movement can stir the molten metal in the ladle. In vacuum degasser.

The most remarkable point in the present invention is that at least the dip tube is provided so as to be movable as described above. As a specific method of moving the immersion tube, as described later, there is a method of integrally moving the immersion tube together with the degassing tank, and a method of moving only the immersion tube while fixing the degassing tank. As the direction of movement, various methods such as horizontal rotation, reciprocation, or movement to any method can be used as described later.

Next, the operation of the present invention will be described. As described above, the vacuum degassing apparatus of the present invention is configured so that the dip tube can be moved relative to the ladle. The molten metal in the ladle can be stirred by the relative movement of the immersion tube. That is, the vacuum degassing apparatus can mechanically stir the molten metal in the ladle while performing the degassing processing of the molten metal. Therefore, the molten metal in the ladle that is being degassed flows sufficiently and is homogenized. Therefore, it is possible to prevent the bias of the process in which a part of the molten metal in the ladle is degassed, and it is possible to perform an efficient degassing process.

Next, the immersion pipe is fixed to the degassing tank, and the immersion pipe is moved by moving the degassing tank relative to the ladle. Preferably, it is configured to be moved. In this case, since it is not necessary to move the immersion pipe relative to the degassing tank, the structures of the degassing tank and the immersion pipe can be relatively simplified, and the airtightness in the degassing tank can be easily improved. Can be secured.

It is preferable that the movement of the immersion tube be a rotational movement in a substantially horizontal direction. In this case, whether the immersion pipe and the degassing tank are moved as a whole with respect to the ladle, or whether only the immersion pipe is moved with respect to the degassing tank, it is comparatively relatively small. The structure can be simple. Further, the airtightness between the degassing tank and the ladle can be relatively easily secured.

Next, a fourth aspect of the present invention uses a degassing tank connected to a decompression device and configured to be able to depressurize the inside, and a plurality of immersion tubes provided at the bottom of the degassing tank. Vacuum degassing method in which the immersion tube is immersed in the molten metal in the ladle, the molten metal is introduced from one immersion tube into the degassing tank, degassed, and then returned from the other immersion tube to the ladle. In the vacuum degassing method, the immersion tube is moved relative to the ladle so as to stir the molten metal in the ladle. In the way.

The most remarkable point in the present invention is that the vacuum degassing method is performed while relatively moving the dip tube and mechanically stirring the molten metal. According to the method of the present invention, the molten metal in the ladle on which the degassing process is being performed can sufficiently flow and be uniform. Therefore, it is possible to prevent the bias of the process in which a part of the molten metal in the ladle is degassed, and it is possible to perform an efficient degassing process.

Next, it is preferable that the movement of the dip tube be a rotational movement in a substantially horizontal direction. Thereby, as described above, simplification of the structure and improvement of airtightness can be achieved.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment A vacuum degassing apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG.
As shown in the figure, the degassing tank 10 is connected to a decompression device 19 and configured to be able to decompress the inside, and has two immersion tubes 21 and 22 provided at the bottom 12 of the degassing tank 10.
The immersion tubes 21 and 22 are immersed in the molten metal 8 in the ladle 3, the molten metal 8 is introduced from one immersion tube 21 into the degassing tank 3 and degassed. It is configured to return to the ladle 3.

The immersion tubes 21 and 22 are provided so as to be relatively movable with respect to the ladle 3, and are configured so that the molten metal 8 in the ladle 3 can be stirred by the movement. The details are described below.

The degassing tank 10 is, as shown in FIG.
The main body 11 and the bottom 12 are combined. At the upper end of the main body 11, a suction hole 111 for vacuum suction is provided.
And a suction tube 112 in the suction hole.
A vacuum pump 19 for reducing pressure is connected to the suction pipe 112. The bottom 12 of the degassing tank 10 is disposed so as to close the lower end of the cylindrical main body 11 and has a through hole 12 communicating with the immersion pipes 21 and 22.
1,122. In addition, near the upper end of one immersion pipe 21, a gas inlet 127 communicating with the inert gas introduction pipe 71 is provided so that the inert gas 7 for raising the metal melt 8 can be introduced.

At the lower end of the bottom portion 12, a flange portion 15 for closing the upper opening 30 of the ladle 3 is provided. A supply pipe 7 through which an inert gas 7 is introduced to make the atmosphere inside the ladle 3 an inert atmosphere is provided in the flange portion 15.
8 is provided. In this example, the immersion pipes 21 and 22 are fixed to the degassing tank 10, and the
Is moved relative to the ladle 3, so that the immersion tubes 21, 22 are moved.

More specifically, a moving mechanism 4 is provided between the flange 15 and the upper end 31 of the ladle 3 so as to seal between them and to slide. The moving mechanism 4 has a structure in which an O-ring is fixed in a water-cooled groove, and a flange portion slides on the O-ring. And
The degassing tank 10 and the immersion pipes 21 and 22 are integrally rotated together with the flange 15 by a driving source (not shown). Thereby, the immersion tube 21,
22 can rotate and move relative to the ladle 3 in a substantially horizontal direction.

Next, an example of a degassing process using the vacuum degassing apparatus 1 of this embodiment will be briefly described. For example, when degassing a steel material as a molten metal, the molten metal 8 at a temperature of 1400 ° C. is stored in the ladle 3. Next, dip tube 2
The vacuum degassing device 1 is arranged so that the lower ends of the metal plates 1 and 22 are sufficiently immersed in the molten metal 8. At this time, the flange 15 and the upper end 31 of the ladle 3 are brought into contact with each other via the moving mechanism 4.

Next, the inside of the degassing tank 10 is evacuated by operating the vacuum pump 19 connected to the degassing tank 10. The degree of vacuum is controlled, for example, to about 0.5 Torr. In addition, an inert gas 7 is introduced into the ladle 3 from the supply pipe 75 to maintain the inside of the ladle 3 in an inert atmosphere. Then, by driving the moving mechanism 4, the entire degassing tank 10 is rotationally moved in the horizontal direction, and accordingly, the immersion pipes 21 and 22 are rotationally moved in the metal melt 8 in the horizontal direction.

Next, the inert gas 7 is guided from an inert gas supply source connected to the inert gas introduction pipe 71,
1 is blown out to the communication hole 121 communicating with 1. As a result, the molten metal 8 is supplied from the immersion pipe 21 into the upper degassing tank 10 by the action of a so-called air lift pump. Then, the gas contained in the molten metal 8 is removed by the depressurizing action in the degassing tank 10 and then returned to the ladle 3 below through the other immersion pipe 22.

Here, the vacuum degassing apparatus 1 of this embodiment is constructed so that the immersion tubes 21 and 22 can be moved relative to the ladle 3 as described above. And this immersion tube 21,
The molten metal in the ladle 3 can be agitated by the relative movement of 22. That is, the vacuum degassing apparatus 1 can mechanically stir the molten metal 8 in the ladle 3 while performing the degassing processing of the molten metal 8. Therefore, the molten metal in the ladle 3 that is performing the degassing process flows sufficiently,
Be uniformed. Therefore, it is possible to prevent the bias of the process in which a part of the molten metal in the ladle is degassed, and it is possible to perform an efficient degassing process.

Further, in the present embodiment, the immersion pipes 21 and 22 are fixed to the degassing tank 3, and the immersion pipes 21 and 22 are moved by moving the degassing tank 10 relative to the ladle 3. It is configured as follows. Therefore, the immersion tubes 21 and
2 need not be moved with respect to the degassing tank 10,
The airtightness in the degassing tank 10 can be easily secured. Therefore, the degassing process in the degassing tank 10 can be performed stably. Further, in the present example, by providing the moving mechanism 4 between the flange portion 15 and the ladle 3, the entire degassing tank 10 can be rotationally moved. Thus, the immersion tubes 21 and 22 can be rotated while the opening 31 of the ladle 3 is always closed by the flange portion 15, and the atmosphere in the ladle 3 is maintained in a sufficiently inert atmosphere. The stirring of the molten metal 8 can be performed.

[0026]

As described above, according to the present invention, the metal melt in the ladle can be positively stirred during the vacuum degassing process, and the vacuum degassing process can be efficiently performed. An apparatus and a vacuum degassing method can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a structure of a vacuum degassing apparatus in an embodiment.

FIG. 2 is an explanatory view showing the structure of a vacuum degassing device in a conventional example.

[Explanation of symbols]

 1. . . Vacuum degassing device, 10. . . Degassing tank, 11. . . Body part, 111. . . Suction hole, 112. . . 11. Suction tubes 112,12. . . Bottom, 120. . . Upper surface, 121, 122. . . Communication hole, 123, 124. . . Opening, 15; . . Flange section, 19. . . Vacuum pump, 21, 22,. . . Dip tube, 215, 225. . . 2. inner peripheral surface; . . Ladle, 4. . . 6. moving mechanism, . . Inert gas, 71. . . 7. inert gas introduction pipe, . . Molten metal,

Claims (5)

[Claims] 1. A degassing tank connected to a decompression device and configured to be able to depressurize the inside thereof, and a plurality of immersion pipes provided at the bottom of the degassing tank. In a vacuum degassing apparatus configured to immerse in the molten metal of the above and introduce the molten metal from one immersion pipe into the degassing tank and degas, and then return the molten metal to the ladle from the other immersion pipe, The pipe is provided movably relative to the ladle,
A vacuum degassing apparatus characterized in that the metal melt in the ladle can be stirred by the movement. 2. The immersion pipe according to claim 1, wherein the immersion pipe is fixed to the degassing tank, and the immersion pipe is moved by moving the degassing tank relative to the ladle. A vacuum degassing device. 3. The vacuum degassing apparatus according to claim 1, wherein the movement of the immersion tube is a rotational movement in a substantially horizontal direction. 4. A degassing tank connected to a decompression device and configured to be able to depressurize the inside, and a plurality of dip tubes provided at the bottom of the degas tank, wherein the dip tubes are placed in a ladle. In the vacuum degassing method, the molten metal is immersed in the molten metal and introduced into the degassing tank from one immersion pipe, degassed, and then returned to the ladle from the other immersion pipe. Vacuum degassing, wherein the immersion tube is moved relative to the ladle so as to stir the molten metal in the ladle. 5. The vacuum degassing method according to claim 4, wherein the movement of the immersion tube is a rotational movement in a substantially horizontal direction.