JPH10160355A - Oxidation inhibition type light metal melting and holding furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce using amount of inert gas for degassing by reducing oxidation from a molten metal surface. SOLUTION: Inert gas is fully filled in a space between molten metal surface of light metal and ceiling of a molten metal pool 11 in the pool of a sealed structure and removed by an inert gas circulating means 15, and again returned to a molten metal bottom side in the pool 11. An agitating means 20 for agitating the molten metal is provided at the ceiling of the pool 11, and a degassing port 21 for exhausting gas (hydrogen gas and the like) generated in the case of melting the metal is formed thereat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reduces the area in which a high-temperature light metal comes into contact with an atmosphere containing oxygen, reduces oxidation from the surface of a molten metal, and reduces the amount of inert gas used for degassing. And an antioxidant type light metal melting and holding furnace.

[0002]

2. Description of the Related Art Conventionally, the surface of a molten metal in a melting furnace for light metals such as aluminum has been exposed to air in an indirect heating type and to a combustion gas in a direct heating type. For example, in the indirect heating type melting furnace 1 shown in FIG. 2, a light metal body 4 to be melted is put into a
The light metal body 4 is melted by heating from the outside by the burner 5, but the surface of the melt in the melt pool 3 is exposed to outside air, that is, air and combustion gas. On the other hand, there is a structure in which the surface of a molten metal is covered with an inert gas, such as a low-pressure casting furnace (not shown), but there is no structure in which melting is performed only by holding.

[0003]

However, light metals such as aluminum have a strong bonding force with oxygen, and their surfaces are easily oxidized even at room temperature, and much more easily oxidized at high temperatures. In this case, even if the outside air is water vapor or carbon dioxide, it is oxidized, and an oxide film is immediately formed on the surface of the molten metal. For this reason, (1) it is inevitable that a certain amount of oxides comes out, and it is difficult to reduce it. (2) Particularly when used for casting, it is necessary to constantly remove oxides frequently. (3) The longer the retention time, the greater the amount of oxidation. (4) It is necessary to perform bubbling with an inert gas in order to remove hydrogen gas in the molten metal generated during normal melting.
Since the inert gas is used up, it is necessary to always prepare a new gas. SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is an antioxidant type light metal melting and melting method that reduces oxidation from the surface of a molten metal and reduces the amount of an inert gas used for degassing. It is intended to provide a holding furnace.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has a molten metal pool for holding a light metal melted by indirect heating, and the light metal to be melted is stored in the molten metal pool. It has a raw material charging pipe for charging, a molten metal outlet port is formed on the side wall of the molten metal pool, and the inside of the molten metal pool has a sealed structure, and the surface space of the molten metal is filled with an inert gas. In the above-described configuration, it is possible to adopt a configuration in which the inert gas is taken out from the molten metal surface space and circulated so as to be returned to the molten metal from the bottom side of the molten metal pool. Further, a stirring means for stirring the molten metal in the molten metal pool can be provided. In addition, a lid can be provided at a charging opening of the raw material charging pipe. Further, a configuration may be employed in which an inert gas is fed into the raw material charging pipe. Further, a lid can be provided at the molten metal outlet on the side wall of the molten metal pool. Further, it is possible to adopt a configuration in which an inert gas is fed into the molten metal outlet on the molten metal pool side wall. In addition, the inert gas can be pressure-fed to the surface space of the molten metal in the molten pool, and the molten gas can be pushed out of the molten pool by the introduction pressure of the inert gas. In addition, a degassing port for discharging gas in the molten metal can be provided on a ceiling above a surface of the molten metal in the molten metal pool. Further, a raw material pushing means can be provided in the raw material charging pipe. Further, the molten metal in the molten metal pool can be configured to be swingable.
Further, an openable and closable opening for removing oxides and cleaning the inside of the molten metal pool can be formed on the ceiling side of the molten metal pool. Further, a filter may be provided at the molten metal outlet.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an antioxidant type light metal melting and holding furnace according to the present invention will be described with reference to the accompanying drawings, with reference to one embodiment. FIG. 1 shows an antioxidant type light metal melting and holding furnace 10 which has a molten metal pool 11 for holding indirectly heated and melted light metal. The molten metal pool 11 has a structure in which the inside of the pool is sealed with a well-known refractory material, and a heating means (not shown) for heating from the outside of the molten metal pool 11 is provided. In addition, the molten metal pool 11 is provided with a raw material charging pipe 12 for charging a light metal to be melted from the upper outside of the side wall to the bottom of the molten metal pool 11. Further, the molten metal pool 11 is provided with a molten metal outlet 13 for extracting the molten light metal melt. The space between the surface of the light metal melt and the ceiling of the melt pool 11 in the melt pool 11 is filled with an inert gas (described later), and the inert gas is introduced into the side wall of the melt pool 11. The inert gas supply port 14 is formed.
The inert gas may be supplied from the inert gas supply port 14 to the space in the molten metal pool by increasing the pressure by, for example, a compressor (not shown). As the inert gas, for example, a nitrogen gas or an argon gas can be used. In addition, the molten metal pool 11
On the side wall, there is provided an inert gas circulation means 15 for taking out an inert gas filled in the space between the molten metal surface in the molten metal pool 11 and the ceiling of the molten metal pool and returning it to the molten metal bottom side in the molten metal pool 11 again. Have been. The inert gas circulating means 15 includes an inert gas circulating pipe 17 provided to return the inert gas from an inert gas outlet 16 provided at an upper portion of the side wall of the melt pool 11 to the bottom of the melt in the melt pool 11. And a pump 18 which is means for forcibly circulating the inert gas circulating in the inert gas circulation pipe 17. A branch pipe 19 is provided in the inert gas circulation pipe 17 so as to supply an inert gas to the molten metal outlet 13. Further, a stirring means 20 for stirring the molten metal is provided at the ceiling of the molten metal pool 11. Further, a degassing port 21 for discharging a gas (eg, hydrogen gas) generated when the light metal is melted is formed in the ceiling of the molten metal pool 11.

A lid 22 is provided in the raw material charging tube 12 at a light metal charging opening for melting. A communication pipe 23 is penetrated through the side wall of the molten metal outlet 13,
A portion outside the side wall of the communication pipe 23 is vertically opened upward to form an opening. A lid 24 is formed at the opening. In addition, in the place rising vertically above,
A filter 25 can be interposed.

In the inert gas circulating means 15, an inert gas circulating pipe 17 extends along the bottom from the outside of the side wall to the bottom of the molten metal pool 11, and the inert gas exposed on the bottom is exposed. A plurality of small-diameter jet ports (not shown) so that the inert gas is jetted into the circulation pipe 17.
Are dispersedly formed. In addition, an inert gas may be supplied to the raw material charging pipe 12 through an inert gas circulation pipe 17 at the bottom of the molten metal pool 11.

Further, the stirring means 20 includes a stirrer body 20a having a built-in drive mechanism, a stirring shaft 20b, and a stirring plate 2
0c. By the drive mechanism in the stirrer body 20a, the stirrer shaft 20b is operated up and down in the figure to
The molten metal is stirred while c is immersed in the molten metal. The stirring means 20 is provided with a blade member instead of the stirring plate 20c, and a driving mechanism in the stirrer body 20a rotates the stirring shaft 20b to immerse the blade member in the molten metal. May be rotated to agitate the molten metal.

The antioxidant light metal melting and holding furnace according to the present invention is constructed as described above. Next, the operation of the antioxidant light metal melting and holding furnace will be described. First, in the molten metal pool 11, the lid 22 on the charging opening side of the raw material charging pipe 12 is opened, and the raw material M, which is a light metal to be melted, is charged. The raw material M reaches the furnace bottom. At this time, an inert gas can be supplied into the molten metal pool 11 from the inert gas supply port 14 in advance to fill the inside of the furnace. Further, at that time, the inert gas circulation means 15
The pump 18 is started to circulate the inert gas in the furnace, and the degassing port 21 in the ceiling of the molten metal pool 11 is opened, so that the oxygen-containing atmosphere lighter than the inert gas in the furnace is set in the furnace. It can be released from the degassing port 21. In this state, the raw material M charged into the furnace can be melted without being oxidized by the heating means (not shown) outside the molten metal pool 11.

[0010] In this way, even if the raw material M is melted and accumulated in the furnace as molten metal, the atmosphere in the furnace is filled with the inert gas. Therefore, the amount of oxidation is reduced, and the oxidation of the molten metal can be suppressed. In addition, when the inert gas is supplied to the opening side of the raw material supply pipe 12 and the vertically rising portion of the molten metal outlet port 13 outside the molten metal pool 11,
Even if held for a long time, the oxidation of the molten metal can be suppressed.
The raw material M is melted and accumulated in the furnace as molten metal, and when the molten metal surface reaches the position of the molten metal outlet 13, the molten metal passes through the communication pipe 23 and opens on the opening side of the vertically raised portion outside the molten metal pool 11. Leads to. At this time, impurities remaining in the molten metal can be removed by the filter 25. If the pressure is increased from the inert gas supply port 14 by a compressor (not shown) to supply the inert gas to the space in the molten pool 11, the molten metal can be discharged from the molten metal outlet 1.
3 can be promoted to the opening side of the vertically raised portion outside the molten metal pool 11 through the third communication pipe 23.

An inert gas circulation means 1 is provided in the molten metal.
5, the inert gas is recirculated through the inert gas circulation pipe 17 extending from the upper side of the side wall to the bottom of the molten metal pool 11 along the bottom surface, and the inert gas is jetted into the molten metal. When the inert gas passes through the molten metal, bubbles of the inert gas promote degassing of gas (hydrogen gas, etc.) in the molten metal, and oscillate and stir the molten metal.
Further, it can also serve as a sealing effect of the inert gas on the surface of the molten metal. Further, since the inert gas is circulated by the inert gas circulating means 15, the supply of the inert gas can be newly reduced during the normal operation. Further, the stirrer body 20a in the stirring means 20
By driving the stirring shaft 20b up and down in the figure by the driving mechanism inside, the molten metal is agitated while the agitating plate 20c is immersed in the molten metal, whereby the molten metal is oscillated to promote oxide separation. And a high-quality molten metal can be obtained.

Although an example of the antioxidant type light metal melting and holding furnace according to the present invention has been described above, if the raw material introduction pipe 12 is provided with a raw material pushing means, the present invention can be applied to the melting of light metal chips. be able to. In addition, molten metal pool 1
Forming an opening on the ceiling side greatly helps oxide removal, cleaning of the molten metal pool 11, and the like.

[0013]

As described above, according to the present invention: (1) Compared with the conventional type, the amount of molten metal in contact with the oxidizing atmosphere is greatly reduced, so that the amount of oxidation is reduced. (2) Since the inside of the raw material charging pipe has a structure in which the replacement of the atmospheric gas is small, even if the material is kept for a long time, the molten metal is hardly oxidized. (3) In the type in which the raw material introduction pipe or the molten metal outlet has a lid, the lid can further prevent oxidation during holding. (4) When an inert gas is fed into the raw material introduction pipe or the molten metal outlet, oxidation loss is extremely small even if the inert gas is held for a long time. (5) In a furnace of a type in which pressure can be applied to the surface of a molten metal by an inert gas, melting and casting can be performed by combining with a casting machine. (6) When air bubbles due to the inert gas are allowed to pass through the inside of the molten metal, the degassing operation, the swinging and stirring operations of the molten metal, and the sealing operation of the molten metal surface with the inert gas can be achieved. (7) Since the inert gas is circulated by passing bubbles of the inert gas through the molten metal, the supply of the inert gas is unnecessary or reduced during normal operation. (8) If oxides can be separated in the furnace, a high-quality molten metal can be obtained. (9) It can be applied to dissolution of metal chips.

[0014]

[Brief description of the drawings]

FIG. 1 is a schematic side view illustrating an example of an antioxidant type light metal melting and holding furnace according to the present invention.

FIG. 2 is a schematic side view showing an example of a current indirect heating type light metal melting furnace.

[Explanation of symbols]

REFERENCE SIGNS LIST 10 Antioxidant type light metal melting and holding furnace 11 Molten pool 12 Raw material charging pipe 13 Molten outlet 14 Inert gas supply port 15 Inert gas circulation means 16 Inert gas outlet 17 Inert gas circulation pipe 18 Pump 19 Branch pipe 20 Stirring means 20a Stirrer body 20b Stirring shaft 20c Stirring plate 21 Degassing port 22 Lid 23 Communication pipe 24 Lid 25 Filter M Raw material

Claims (13)

[Claims] 1. A molten metal pool for holding a light metal melted by heating indirectly, a raw material charging pipe for charging a light metal to be melted into the molten metal pool, and a discharge of a molten metal on a side wall of the molten metal pool. An antioxidant type light metal melting and holding furnace, wherein a mouth is formed, the inside of the molten metal pool is sealed, and a surface space of the molten metal is filled with an inert gas. 2. The antioxidant light metal melting and holding apparatus according to claim 1, wherein an inert gas is taken out from the surface space of the molten metal and circulated so as to return to the inside of the molten metal from the bottom of the molten metal pool. Furnace. 3. The antioxidant light metal melting and holding furnace according to claim 1, further comprising a stirring means for stirring the molten metal in the molten metal pool. 4. The oxidation-resistant light metal melting and holding furnace according to claim 1, wherein a lid is provided at a charging opening of said raw material charging pipe. 5. The antioxidant light metal melting and holding furnace according to claim 4, wherein an inert gas is fed into said raw material charging pipe. 6. The antioxidant type light metal melting and holding furnace according to claim 1, wherein a lid is provided at a molten metal outlet on the side wall of the molten metal pool. 7. The oxidation-resistant light metal melting and holding furnace according to claim 6, wherein an inert gas is fed into a molten metal outlet on the side wall of the molten metal pool. 8. The apparatus according to claim 1, wherein an inert gas is pressure-fed to a surface space of the molten metal in the molten metal pool, and the molten metal is pushed out of the molten metal pool by the introduction pressure of the inert gas. 7. An antioxidant light metal melting and holding furnace according to any one of claims 1 to 7. 9. The antioxidant type light metal melting and holding apparatus according to claim 1, wherein a degassing port for releasing gas in the molten metal is provided on a ceiling above a surface of the molten metal in the molten metal pool. Furnace. 10. An antioxidant type light metal melting and holding furnace according to claim 1, wherein a raw material pushing means is provided in said raw material charging pipe. 11. The antioxidant light metal melting and holding furnace according to claim 1, wherein the molten metal in the molten pool is swingable. 12. The antioxidant type light metal melting and melting apparatus according to claim 1, wherein an openable and closable opening for removing oxides and cleaning the inside of the molten pool is formed on the molten metal pool ceiling side. Holding furnace. 13. The antioxidant light metal melting and holding furnace according to claim 1, wherein a filter is provided at the molten metal outlet.