JPH072262B2 - Vacuum induction furnace - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vacuum induction furnace, and in particular, by forming a casting chamber separately from a melting and refining chamber, the melting and refining chamber and the casting chamber are operated in parallel and continuously. The present invention relates to a vacuum induction furnace that can be operated.

[Prior Art] In general, there is known a steelmaking method using a vacuum induction furnace in which an induction furnace is arranged in a vacuum to melt and smelt a material to be melted such as a metal ingot and then directly ingot in a vacuum or an inert gas atmosphere. ing.
Conventionally, this type of vacuum induction furnace 1 is constructed as shown in FIG. As shown in the figure, an induction furnace 3, a tundish 4, and a mold 5 are sequentially arranged in the outer shell 2 of the vacuum induction furnace 1 from the upper side to the lower side. The furnace outer shell 2 is formed of a closed hollow cylindrical body, and is formed so as to be vertically separable by a flange joint 7 for charging the material 6 to be melted into the induction furnace 3. A nozzle 8 for evacuating the inside of the furnace outer shell 2 by a vacuum exhaust device (not shown) such as a vacuum pump, or for filling an inert gas or atmosphere into the inside after evacuating. Is provided. Also,
The furnace body 9 of the induction furnace 3 is formed as a bottomed straight cylindrical body, and a spout 10 is formed at the upper edge portion. Furthermore,
A high-frequency energizing means 11 is formed in a coil shape on the outer peripheral portion of the side wall of the furnace body 9 so as to surround the side wall of the furnace body 9. The inside of the furnace shell 2 is evacuated, and a high-frequency current is applied along the circumferential direction of the furnace body 9 by the high-frequency energizing means 11 so that a secondary material is injected into the melted material 6 charged in the furnace body 9. The material 6 to be melted is melted by the induced heat generated by the induced current. The molten metal 12 of the material 6 to be melted, which is melted by the high-frequency current supplying means 11, is subsequently refined by convection due to electromagnetic induction of the high-frequency current supplying means 11. The molten metal 12 refined in the furnace body 9 of the induction furnace 3 is a hydraulic cylinder (not shown) for the furnace body 9
And so on, the liquid is poured into the tundish 4 provided below the spout 10 formed at the upper edge of the side wall. The molten metal 12 once received in the tundish 4 is cast from a casting port 13 formed at the bottom of the tundish 4 into a mold 5 provided below the casting port 13. The tundish 4 is for once receiving the molten metal 12 from the induction furnace 3 in order to keep the casting speed constant and rectifying the molten metal flow from the molten metal 12. Tundish 4 of molten metal 12 refined in the furnace body 9 of the induction furnace 3
Therefore, the injection work into the mold 5 is carried out in a vacuum or an inert gas atmosphere. Then, the ingot 14 of the melted material 6 cast in the mold 5 and cast into the ingot 14 is moved while being accommodated in the mold 5 while being placed on the carriage 15 positioned below the ingot 14. It is designed to be carried out from the upper part of the.

[Problems to be Solved by the Invention] The conventional vacuum induction furnace 1 has the following problems.

Since the induction furnace 3 and the mold 5 are provided in the same outer shell 2, the induction furnace 3 completes the melting and refining in the induction furnace 3, and after the casting in the mold 14, the induction furnace 3 continues until the molten metal 12 solidifies. However, there was a problem in that it was not possible to shift to the melting step of No. 3, loss time was generated, batch operation was performed, and continuous operation could not be performed.

Further, there is a problem that the temperature in the outer shell 2 of the induction furnace 3 rises due to the heat of the induction furnace 3 and affects the mold 5, and the time required for cooling the molten metal 12 contained in the mold 5, that is, the time required for casting, becomes long. .

[Object of the Invention] The present invention was devised to solve the problems in a vacuum induction furnace.

It is an object of the present invention to provide a vacuum induction furnace which can achieve parallel drying of a melting and refining process using an induction furnace and a casting process using a mold, and at the same time achieve continuous operation to improve productivity.

[Summary of the Invention] In order to achieve the above object, the present invention has a melting and refining chamber having an induction furnace inside and maintained in a vacuum or an inert gas atmosphere, and is formed separately from the melting and refining chamber. Is maintained in a vacuum or an inert gas atmosphere to receive the molten metal from the induction furnace for ingot making, through holes connecting these melting and refining chambers and the casting room, and the through holes are closed airtightly. And an opening / closing door for opening this, and a molten metal transfer gutter for transferring the molten metal in the induction furnace to the casting chamber, which is provided so as to be retractable so as to be inserted into the through hole when the opening / closing door is opened. Since the casting chamber is separated from the melting and refining chamber, the melting and refining process and the casting process can be performed in parallel, and the melting and refining chamber and the casting chamber can be freely opened and closed. And appears at the through-hole that communicates airtightly Since the molten metal transfer trough for freely transferring the molten metal from the induction furnace to the casting chamber is provided, continuous operation can be created, so that productivity is improved.

[Embodiment] An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The vacuum induction furnace 1 of this embodiment is constructed as shown in FIG. As shown in the figure, the furnace body 9 of the induction furnace 3 of the vacuum induction furnace 1 is arranged in a melting and refining chamber 20 formed by a closed hollow cylinder. The outer wall of the melting and refining chamber 20 is usually formed by an iron plate 20a. In addition, the melting and refining room 20 is the induction furnace 3
A flange joint 7 is formed so as to be vertically separable so as to open the upper portion when the material 6 to be melted is charged into the furnace body 9.

Further, a first nozzle 21 is formed on the side wall of the melting and refining chamber 20, and the inside of the melting and refining chamber 20 is evacuated by a vacuum discharge device (not shown) such as a vacuum pump from the first nozzle 21. Alternatively, the inside of the melting and refining chamber 20 that is evacuated or vacuumed is filled with an inert gas or the atmosphere. The reason for maintaining the inside of the melting and refining chamber 20 in a vacuum or an inert gas atmosphere is to prevent the molten metal 12 in the induction furnace 3 from being oxidized during the refining. On the other hand, the reason for introducing a large amount into the melting and refining chamber 20 is to transfer the molten metal 12 in the induction furnace 3 to the casting chamber 24 and open / close the door 32.
This is to make the inside of the smelting and refining chamber 20 equal to the atmospheric pressure after closing, so that the refining chamber 20 can be easily divided up and down at the flange joint 7 portion. It should be noted that the inside of the smelting and refining chamber 20 may be made equal to the large pressure by introducing an inert gas instead of the atmosphere. The furnace body 9 of the induction furnace 3 is formed of a bottomed straight cylindrical body. At the upper edge of the side wall of the furnace body 9, a molten metal transfer gutter described later is provided.
A pouring port 10 for pouring the molten metal 12 in the furnace body 9 is formed in 28 and the like. The inner wall of the furnace body 9 is formed of refractory 9b. Inside the furnace body 9 thus formed, the material to be melted 6 such as a metal lump is charged. Further, a high frequency energizing means 11 is provided on the outer peripheral portion of the side wall of the furnace body 9 along the circumferential direction of the side wall of the furnace body 9. The high-frequency energizing means 11 is formed in a coil shape so as to surround the outer peripheral portion of the side wall of the furnace body 9 having the straight cylindrical body, and a high-frequency power supply facility (not shown) provided outside the melting and refining chamber 20. It is connected to the. A secondary induction current is generated in the material to be melted 6 from the high-frequency energizing means 11 and is melted by its resistance heat. Thus, the molten metal 12 of the material 6 to be melted, which is housed in the furnace body 9 and melted by the high-frequency energizing means 11, is refined as it is by convection by electromagnetic induction of the high-frequency energizing means 11. Furthermore,
On the side wall of the furnace body 9, an elevating means 22 such as a hydraulic cylinder is provided at the bottom of the chamber.
It stands up from 20c. When the molten metal 12 is poured into a molten metal transfer gutter 28, which will be described later, the rotary shaft 23 provided below the pouring port 10 serves as a fulcrum to move the furnace body 9 by the lifting means 22.
Is designed to rise and roll over. Further, a casting chamber 24 formed separately from the melting and refining chamber 20 is adjacent to the melting and refining chamber 20 at a level lower than the melting and refining chamber 20. In the present embodiment, the casting chamber 24 is formed as a closed hollow cylinder having a carriage storage portion 24a protruding outward in the width direction at the center of the side wall. The outer wall of this casting chamber 24 is usually formed by an iron plate 24b, and the inner wall is a refractory material 24c such as refractory bricks.
It is formed in. A manhole 25 is formed in the upper part of the casting chamber 24, and a second nozzle 26 is formed below the side wall of the manhole 25. From the second nozzle 26, a vacuum exhaust device such as a vacuum pump (not shown) is formed. The interior of the casting chamber 24 by a vacuum, or an inert gas atmosphere filled with an inert gas, or a vacuumed casting chamber 24.
It is designed to enclose an inert gas and the atmosphere inside. The reason for maintaining the interior of the casting chamber 24 in a vacuum or an inert gas atmosphere is that the molten metal poured into the mold 5 and the mold 5
This is to prevent oxidation of the molten metal poured inside. On the other hand, the reason for introducing the atmosphere into the casting chamber 24 is to make the casting chamber 24 equal to the atmospheric pressure after the molten metal 12 in the mold 5 is cooled,
This is because it is easy to open the lid member that covers the manhole 25. In addition, an inert gas is introduced instead of the atmosphere and the casting chamber
The inside of 24 may be made equal to the atmospheric pressure. A mold 5 for receiving and refining the refined molten metal 12 is arranged at the bottom 24 of the casting chamber 24 thus formed. The mold 5 is usually formed by a metal mold and has a bottomed cylindrical body for molding a casting product such as the ingot 14. Further, a carriage 27 is provided below the mold 5, and the ingot 14 of the material 6 to be melted is placed on the carriage 27 while being accommodated in the mold 5 and moved to be formed above the casting chamber 24. Manhole
Made to be carried out from 25. Also this casting room
24 is equipped with a molten metal transfer gutter 28 for transferring the molten metal 12 from the induction furnace 3 to the casting chamber 24. The molten metal transfer gutter 28 is provided so as to be capable of opening and closing the melting and refining chamber 20 and the casting chamber 24 and to be retractable in a through hole 30 formed in a partition wall 29 which is a common side wall so as to communicate with each other in an airtight manner. This partition
An opening / closing door 32 that pivots around a shaft 31 as a fulcrum is provided on the upper portion of the through hole 30 of 29 so as to be openable and closable. A third nozzle 33 protruding from the melting and refining chamber 20 to the casting chamber 24 is formed in the through hole 30, and the opening / closing door 32 opens and closes the third nozzle 33 to close it. It is sometimes made to be sealed. Further, the molten metal transfer gutter 28 is placed on a carriage 34, moves on a rail 35, and can freely move in and out from the carriage storage portion 24a formed in the casting chamber 24 to the through hole 30. When the molten metal 12 of the material 6 to be melted which has been refined is transferred from the induction furnace 3 provided in the melting and refining chamber 20 into the mold 5 provided in the casting chamber 24, the through hole 30 is closed. The opened / closed door 32 is opened, and the molten metal transfer gutter 28 is inserted into the through hole 30. Normally, a tundish is provided between the induction furnace 3 and the mold 5 in order to keep the casting speed constant. In the molten metal transfer gutter 28 of this embodiment, the tundish is supplied from the melting and refining chamber 20 according to this function. It is also configured to have a function of guiding the refined molten metal 12 into the casting chamber 24.
The smelted molten metal 12 from the induction furnace 3 is once received on the molten metal transfer gutter 28, and the molten metal flow from the molten molten metal 12 is rectified from a casting hole 36 formed at the bottom of the molten molten metal 12 and cast into the mold 5. Is made like.

In this embodiment, the smelting and refining chamber 20 and the casting chamber 24 are adjacently arranged so as to share the partition wall 29 with the side walls, but when the smelting and refining chamber 20 and the casting chamber 24 are separated from each other, It is also possible to extend the length of the third nozzle 33 so as to communicate with it in an airtight manner, and to enlarge the length or size of the molten metal transfer gutter 28.

The operation of the vacuum induction furnace 1 configured as described above will be described based on the operating procedure.

First, the melting and refining chamber 20 is divided into upper and lower parts from the flange joint 7 by a carriage (not shown) or the like, and the upper part thereof is opened. Next, the material 6 to be melted, such as a metal lump, is charged into the furnace body 9 of the induction furnace 3 from above, and then the divided flange joints 7 of the melting and refining chamber 20 are engaged and integrated. And seal.
And the first nozzle formed on the side wall of the melting and refining chamber 20.
The material 21 to be melted contained in the furnace body 9 is melted by the high-frequency energizing means 11 while the inside of the melting and refining chamber 20 is evacuated by drawing a vacuum from a vacuum pump 21 or other vacuum exhaust device. The interior of the melting and refining chamber 20 may be evacuated and then filled with an inert gas. The melting by the high-frequency energizing means 11 causes the secondary induced current in the material 6 to be melted as described above, and melts by the resistance heat. After this melting is completed, the material 6 to be melted becomes a molten metal 12. Then, the process proceeds to the vacuum refining process, and the molten metal 12 is refined as it is by the electromagnetic induction of the high-frequency energizing means 11. During the melting and refining process, the through hole 30 formed in the partition 29 is an opening / closing door.
It is closed by being closed by 32. After the completion of the melting and refining process, the interior of the casting chamber 24 is evacuated from the second nozzle 26 formed on the side wall of the casting chamber 24 by a vacuum exhaust device (not shown) such as a vacuum pump, and the melting and refining chamber 20 is
After equalizing the pressure in both the casting chamber 24 and the casting chamber 24, the opening / closing door 32 is opened. It should be noted that the inside of the casting chamber 24 may be evacuated and then filled with an inert gas so as to be equalized with the melting and refining chamber 20. And the through hole 30 having the opened third nozzle 33.
Then, the molten metal transfer gutter 28 is moved by the carriage 34 from the carriage storage portion 24a and inserted. Next, the induction furnace 3 containing the refined molten metal 12 is turned over by raising and lowering the elevating means 22 such as a hydraulic cylinder provided in the furnace body 9, and the molten metal 12 is poured into the molten metal transfer gutter 28. The molten metal 12 once received by the molten metal transfer gutter 28 is to be transferred from the melting and refining chamber 20 into the casting chamber 24, and the molten metal flow from there is rectified from a casting port 36 formed at the bottom thereof. It is cast into the mold 5 arranged in the casting chamber 24. After completion of casting operation, melt transfer gutter
The carriage 28 is moved backward by the carriage 34 to the carriage storage portion 24a, and the through hole 30 of the third nozzle 33 is closed again by the opening / closing door 32. After that, the atmosphere or an inert gas is filled in the inside of the melting and refining chamber 20 to equalize the pressure with the atmospheric pressure, the upper portion thereof is reopened from the flange joint 7, and the induction furnace 3 enters the next melting and refining step. On the other hand, the casting chamber 24 enters the cooling of the casting process, and when the ingot is finished and it becomes a casting product such as the ingot 14, the carriage 27
The casting chamber 24 is filled with the atmosphere or an inert gas from the nozzle 26 so as to be equalized with the atmospheric pressure, and then discharged from the manhole 25 formed in the upper portion of the casting chamber 24.

Since the casting chamber 24 is formed separately from the melting and refining chamber 20 in this manner, the melting and refining process and the casting process can be operated in parallel, so that the loss time is reduced.

Further, the melting and refining chamber 20 and the casting chamber 24 can be freely opened and closed, and
Since a molten metal transfer gutter 28 for transferring the molten metal 12 from the smelting and refining chamber 20 to the casting chamber 24 is provided in the through hole 30 that communicates airtightly, continuous operation is performed.

Further, since the furnace heat of the induction furnace 3 in the melting and refining chamber 20 does not affect the molten metal 12 contained in the mold 5 in the casting chamber 24, the time required for cooling the casting is shortened.

[Effects of the Invention] In summary, according to the present invention, the following excellent effects are exhibited.

(1) Since the smelting and refining chamber and the casting chamber are provided separately, it is possible to operate the smelting and refining process and the casting process in parallel so that the loss time can be reduced, and the molten metal transfer gutter is provided at the through hole connecting these. With this, continuous operation is possible and productivity can be improved.

(2) Since it is configured as in the item (1), only the melting and refining chamber needs to be evacuated to a vacuum in the melting and refining step, so that the capacity of the vacuum exhaust device can be reduced and the operating cost can be reduced.

(3) In the induction furnace provided in the melting and refining chamber during the casting process in the casting chamber, which is configured as described in (1) and (2) and the opening / closing door provided at the through hole is closed. Since the furnace heat does not affect, the time required for cooling the molten metal cast in the mold is shortened and the casting process can be shortened.

(4) Since it is configured as in the items (1), (2) and (3), the range of contamination can be limited without the inside of the melting and refining chamber becoming dirty due to the splash of the molten metal generated during the casting of the molten material. Maintenance can be reduced.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention, and FIG. 2 is a side sectional view showing a conventional example. In the figure, 1 is a vacuum induction furnace, 3 is an induction furnace, 12 is a molten metal, 20 is a melting and refining chamber, 24 is a casting chamber, 28 is a molten metal transfer gutter, and 30 is a through hole.

Claims (1)

[Claims] 1. A melting and refining chamber that has an induction furnace inside and is maintained in a vacuum or an inert gas atmosphere; and a melting and refining chamber that is formed separately from the melting and refining chamber, and the inside is maintained in a vacuum or an inert gas atmosphere. A casting chamber for receiving molten metal from the induction furnace and making an ingot, through-holes for communicating these melting and refining chambers with the casting chamber, an opening / closing door for hermetically closing the through-hole and opening the same, and the opening / closing A vacuum induction furnace provided with a molten metal transfer gutter for transferring the molten metal in the induction furnace to a casting chamber so that the molten metal in the induction furnace can be retracted and inserted so as to be inserted into the through hole when the door is opened. .