JP3887579B2 - Metal gas generation method and metal gas generation apparatus in reduction casting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal gas generation method and a metal gas generation apparatus in a reduction casting method.
[0002]
[Prior art]
There is known a reduction casting method in which a reducing compound produced by reacting a metal gas and a reactive gas is introduced into a mold cavity, and an oxide film on the surface of the molten metal is reduced by the reducing compound to cast a cast product. It has been.
According to this reduction casting method, the surface of the molten metal becomes pure aluminum, the surface tension of the molten metal is lowered, and the fluidity of the molten metal is enhanced. As a result, it is possible to obtain a cast product with excellent appearance, free from casting defects and free from hot water wrinkles.
[0003]
Japanese Patent Application Laid-Open No. 2001-321916 discloses a metal gas generator in this reduction casting method.
In this metal gas generator, the inside of a heating furnace equipped with an electric heater is divided by a plurality of shielding plates to prevent the metal powder (magnesium powder) from rising, and the metal powder is introduced into the cavity as a powder. Try to prevent.
[0004]
[Problems to be solved by the invention]
However, the above reduction casting method has the following problems.
That is, when heating the heating furnace with an electric heater at the start of casting, it takes about 1 hour to raise the heating furnace to the required temperature (preliminary heating), and the work efficiency is poor. is there.
Further, in the above reduction casting method, since powdered magnesium is used, piping is clogged and difficult to handle, and it is not possible to completely prevent the powder from being introduced into the cavity, There is a problem that the quality of cast products is deteriorated.
Therefore, the present invention has been made to solve the above-described problems, and the object of the present invention is to improve the working environment and improve the working efficiency and the metal gas generating method and the metal gas generating in the reduction casting method. To provide the equipment.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention comprises the following arrangement.
That is, in the metal gas generation method in the reduction casting method of the present invention, a reducing compound produced by reacting a metal gas and a reactive gas is introduced into a mold cavity, and the surface of the molten metal is oxidized by the reducing compound. In the method of generating metal gas in the reduction casting method of casting a cast product by reducing the film, the metal contained in the heating furnace is directly or indirectly heated by high frequency induction heating to generate the metal gas. And
Further, the generated metal gas is introduced into the cavity by a carrier gas.
Further, magnesium is used as a metal and argon gas is used as a carrier gas.
Further, the metal is put in a crucible made of a material heated by high-frequency induction heating, and stored in a heating furnace, and the crucible is heated by high-frequency induction to indirectly heat the metal to generate a metal gas. And
Further, the temperature detection unit detects the temperature in the heating furnace so that the temperature in the heating furnace is maintained at a required set temperature lower than the metal gas generation temperature, and at the time of casting injecting molten metal into the cavity, The inside of the heating furnace is heated each time to generate a metal gas.
[0006]
In the metal gas generator in reduction casting according to the present invention, a reducing compound produced by reacting a metal gas and a reactive gas is introduced into a cavity of a mold, and an oxide film on the surface of the melt is formed by the reducing compound. In a metal gas generator used in a reduction casting method for casting a cast product by reduction, a heating furnace in which the metal is stored,
A heating coil surrounding the heating furnace, a power supply unit that supplies electric power to the heating coil to inductively heat the heating furnace, a control unit that controls the power supply unit, and a metal gas generated in the heating furnace. And an introduction path for introducing the cavity.
[0007]
It is preferable to provide a chamber for temporarily storing the metal gas generated in the heating furnace.
Moreover, the crucible which accommodates a metal in the said heating furnace is provided, It is characterized by the above-mentioned.
Preferably, the crucible is made of a material heated by high frequency induction heating, and the metal is indirectly heated to generate a metal gas by heating the crucible.
A carrier gas supply unit for introducing a carrier gas into the heating furnace is provided.
Magnesium is used for the metal and argon gas is used for the carrier gas.
Furthermore, a temperature detection unit for detecting the temperature in the heating furnace is provided, and the control unit maintains the required set temperature lower than the metal gas generation temperature by the control unit, and at the time of casting, It is preferable to control the power supply unit so that the inside of the heating furnace is heated each time to generate the metal gas.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an explanatory diagram showing the overall configuration of the casting apparatus 10.
Reference numeral 11 denotes a molding die, 12 denotes a cavity, and 17 denotes a pouring bath disposed on the upper part of the molding die 11. The pouring bath 17 and the cavity 12 communicate with each other through the pouring gate 14, and the pouring of the cavity 12 is controlled by opening and closing the tenon 15 attached to the pouring gate 14. Reference numeral 16 denotes a pipe provided through the tenon 15 in the vertical direction.
Reference numeral 13 denotes a flow path through which the cooling water flows.
[0009]
Reference numeral 20 denotes a nitrogen gas cylinder, which is connected to the mold 11 via a pipe 22 and a valve 24, and is provided so that nitrogen gas can be introduced into the cavity 12 from the nitrogen gas inlet 11a. 11 b is an exhaust port provided in the mold 11. A vacuum device is connected to the exhaust port 11b via a pipe having a valve 25 inserted therein, and the vacuum device is operated with the valve 25 opened, whereby the inside of the cavity 12 can be made into a non-oxygen atmosphere.
[0010]
21 is an argon gas cylinder. The argon gas cylinder 21 is connected to a heating furnace 28 that generates a metal gas via a pipe 26. By opening and closing a valve 30 provided on the pipe 26, the injection of argon gas into the heating furnace 28 is controlled. .
[0011]
The heating furnace 28 is connected to the cavity 12 of the mold 11 through the pipe 49, the valve 45, and the pipe 16 attached to the tenon 15. Magnesium gas gasified in the heating furnace 28 or magnesium in a mist form is formed by using an argon gas as a carrier gas by opening / closing the valve 45 inserted in the pipe 49 and controlling the argon gas pressure by the valve 30. 11 cavities 12 are introduced.
[0012]
In the present embodiment, the heating furnace 28 is heated by the high frequency induction heating device 29. FIG. 2 shows the configuration of the high-frequency induction heating device 29, 31 is a high-frequency power supply unit, 33 is a matching unit, and 35 is a heating coil. The heating coil 35 surrounds the heating furnace 28. Reference numeral 37 denotes a control unit that controls the high-frequency power supply unit 31. The matching unit 33 is cooled by a water cooling pump 39. As this high-frequency induction heating device 29, a known device can be used.
[0013]
The temperature in the heating furnace 28 is detected by a temperature detection unit 41 made of a thermocouple or the like, and the detected temperature data is input to the control unit 37. In the control unit 37, when the temperature in the heating furnace 28 becomes lower than the set temperature during the casting process, the heating coil 35 is energized by the power supply unit 31, and the inside of the heating furnace 28 is always set temperature (for example, 600 ° C.). The temperature is maintained so that No metal gas (magnesium gas) is generated at the set temperature of about 600 ° C. In addition, when the temperature in the heating furnace 28 becomes equal to or higher than a predetermined set temperature, an alarm device (not shown) is operated by the control unit 37 to notify the abnormality.
[0014]
In the heating furnace 28, a crucible 43 (FIG. 2) containing magnesium is stored.
Magnesium is not in powder form but can be in granular or massive form. Therefore, handling is easy.
The crucible 43 is preferably made of a magnetic material such as iron. By using the crucible 43 made of a magnetic material, the crucible 43 is high-frequency induction heated by the heating coil 35, whereby magnesium is indirectly heated and gasified. The gasification temperature is about 800 ° C. Since the inside of the heating furnace 28 is maintained at a temperature of about 600 ° C. as described above, the heating coil 35 may be energized in a short time, and the temperature in the crucible 43 is easily raised to the gasification temperature or higher.
[0015]
The crucible 43 may be made of a nonmagnetic material. In this case, the material of the crucible 43 is preferably a non-oxidizing ceramic such as silicon nitride or aluminum nitride that does not react with a metal gas (magnesium gas).
When the crucible 43 is made of a nonmagnetic material, the magnesium accommodated in the crucible 43 is directly subjected to high frequency induction heating. In this case, it is possible to heat magnesium in a stable state by relaxing the heating conditions.
[0016]
Argon gas is introduced into the lower part of the heating furnace 28 from the argon gas cylinder 21, and magnesium gas generated in the heating furnace 28 is introduced into the cavity 12 from the pipe 49 by argon gas as a carrier gas.
The upper portion of the heating furnace 28 is formed in a chamber 47, and magnesium gas generated in the heating furnace 28 is temporarily stored.
[0017]
FIG. 3 schematically shows the control state (a) of the power supply unit 31 by the control unit 37 and the temperature in the heating furnace 28.
As described above, the inside of the heating furnace 28 is maintained at a required set temperature (for example, 600 ° C.) where no magnesium gas is generated.
Since the high frequency induction heating device 29 is used, the temperature rise (preheating) to the set temperature can be performed in a short time. Also, the heating time for maintaining the set temperature is very short.
[0018]
At the time of casting, when the molten metal is poured into the cavity 12 of the mold 11, the heating coil 35 is energized each time, and the inside of the heating furnace 28 is heated in a short time, thereby generating magnesium gas. That is, when necessary, magnesium gas can be generated in a short time.
Thus, since the heating coil 35 is not always energized, it is possible to save power.
Moreover, since it is high frequency induction heating, the heating device and the heating furnace can be reduced in size, and the surroundings of the heating furnace do not become unnecessarily high, and the working environment is improved.
[0019]
Aluminum casting by the casting apparatus 10 shown in FIG. 1 is performed as follows.
First, in a state where the tenon 15 is fitted to the gate 14 and the gate 14 is closed, the valve 24 is opened, and nitrogen gas is injected into the cavity 12 of the mold 11 from the nitrogen gas cylinder 20 via the pipe 22. As a result, the air in the cavity 12 is purged, and the inside of the cavity 12 becomes a substantially non-oxygen atmosphere. After the cavity 12 is in a non-oxygen atmosphere, the valve 24 is closed.
[0020]
In the heating furnace 28, a crucible 43 in which granular or lump magnesium is accommodated is stored.
When nitrogen gas is being injected into the cavity 12 of the mold 11 or in advance, the valve 30 is opened and argon gas is injected into the heating furnace 28 from the argon gas cylinder 21 to make the inside of the heating furnace 28 oxygen-free. . Whether or not the inside of the heating furnace 28 is in an oxygen-free state may be checked by the oxygen sensor 19.
[0021]
On the other hand, the heating coil 35 is energized, the crucible 43 accommodated in the heating furnace 28 is heated, the temperature in the heating furnace 28 is detected by the temperature detector 41, and the temperature in the heating furnace 28 is set to about 600 ° C. Manage to maintain temperature.
Since the initial temperature raising time (preliminary heating) can be performed in a short time of about several tens of seconds by high-frequency induction heating, the working efficiency is greatly improved.
[0022]
When casting is performed, the control unit 37 energizes the heating coil 35 through the power supply unit 31 and heats the crucible 43 to a temperature of 800 ° C. or higher by high-frequency induction heating, thereby heating the magnesium. Generate gas.
Next, the valve 45 is opened to adjust the pressure and flow rate of the argon gas, and magnesium gas is injected into the cavity 12 of the mold 11 from the heating furnace 28 via the pipe 49 while using the argon gas as a carrier gas. Mist magnesium is also sent from the heating furnace 28 together with the magnesium gas.
[0023]
After injecting magnesium gas into the cavity 12, the valve 45 is closed, then the valve 24 is opened, and nitrogen gas is injected into the cavity 12 from the nitrogen gas inlet 11a. By injecting nitrogen gas into the cavity 12, the previously injected magnesium gas and nitrogen gas react in the cavity 12 to generate a magnesium nitrogen compound (Mg ₃ N ₂ ), which is a reducing compound. The magnesium nitrogen compound is mainly deposited on the inner wall surface of the cavity 12.
[0024]
Next, in a state where the magnesium nitrogen compound is generated on the inner wall surface of the cavity 12, the tenon 15 is opened, and the molten metal 18 is poured into the cavity 12 from the gate 14 to perform casting.
In the case of this reduction casting method, the molten metal 18 is filled in the cavity 12 in a very short time. Therefore, the molten metal 18 filled in the mold 11 is cooled to solidify the molten metal 18 in a short time. Is effective.
Although the casting cycle depends on the capacity of the cavity 12, high-speed casting can be performed in a cycle of about 30 seconds.
[0025]
In the above embodiment, magnesium gas and nitrogen gas are directly introduced into the cavity to produce a magnesium nitrogen compound in the cavity. A reaction chamber (not shown) is provided immediately before the mold, and this reaction chamber Magnesium gas and nitrogen gas may be introduced together with argon gas and reacted in the reaction chamber to produce a magnesium nitrogen compound, which may be introduced into the cavity.
[0026]
In the above-described embodiment, the magnesium nitrogen compound has been described as an example of the reducing substance of the molten metal. However, magnesium alone or other reducing substances may be used.
As the carrier gas, an inert gas or non-oxidizing gas other than argon gas may be used. These are collectively referred to as non-reactive gases.
Further, the solidification rate and filling time of the molten metal are not limited to the above.
Furthermore, in the said embodiment, although the aluminum casting method was demonstrated, it is not limited to aluminum casting, Various aluminum alloys, various metals, such as magnesium and iron, or the casting method which uses these alloys as a casting material Can be applied to.
[0027]
【The invention's effect】
According to the present invention, as described above, the metal is directly or indirectly heated by high frequency induction heating, so that the preheating for preheating the heating furnace can be performed in a short time, and the working efficiency is improved. Greatly improved.
In addition, the entire apparatus can be reduced in size, and the working environment is improved because the temperature around the heating furnace does not become higher than necessary.
Moreover, granular or lump metal can be accommodated in a heating furnace and heated, and it is not necessary to use powder metal as in the prior art, so that handling is improved.
Furthermore, since heating during the casting cycle can be performed in a short time, the casting cycle can be shortened.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an outline of an entire casting apparatus.
FIG. 2 is an explanatory diagram of a high-frequency induction heating device and a heating furnace.
FIG. 3 is a schematic diagram showing a relationship between an energization cycle to a heating coil and a temperature in a heating furnace.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Casting apparatus 11 Mold 11a Nitrogen gas introduction port 11b Exhaust port 12 Cavity 13 Channel 14 Pouring port 15 Tenon 16 Pipe 17 Pouring bath 18 Molten metal 20 Nitrogen gas cylinder 21 Argon gas cylinder 28 Heating furnace 29 High frequency induction heating apparatus 31 Power supply unit 33 Matching device 35 Heating coil 37 Control unit 39 Water cooling pump 41 Temperature detector 43 Crucible 47 Chamber 49 Piping

Claims (12)

A metal in a reduction casting method in which a reducing compound produced by reacting a metal gas and a reactive gas is introduced into a cavity of a mold, and an oxide film on the surface of the molten metal is reduced by the reducing compound to cast a cast product. In the method of generating gas,
A metal gas generation method in a reduction casting method, wherein metal contained in a heating furnace is directly or indirectly heated by high frequency induction heating to generate a metal gas. 2. The method for generating metal gas in a reduction casting method according to claim 1, wherein the generated metal gas is introduced into the cavity by a carrier gas. 3. The method for generating metal gas in the reduction casting method according to claim 2, wherein magnesium is used for the metal and argon gas is used for the carrier gas. A metal is put in a crucible made of a material heated by high-frequency induction heating, and is stored in a heating furnace, and the metal is generated by indirectly heating the metal by high-frequency induction heating. The method for generating metal gas in the reduction casting method according to claim 1, 2 or 3. The temperature detection unit detects the temperature in the heating furnace so that the temperature in the heating furnace is maintained at a required set temperature lower than the metal gas generation temperature,
5. The metal gas generation in the reduction casting method according to claim 1, wherein the metal gas is generated by heating the inside of the heating furnace each time when casting the molten metal into the cavity. Method. A reducing compound produced by reacting a metal gas and a reactive gas is introduced into a mold cavity, and the reducing compound is used to reduce the oxide film on the surface of the molten metal to cast a cast product. In the metal gas generator,
A heating furnace in which the metal is stored;
A heating coil surrounding the heating furnace;
A power supply unit that supplies power to the heating coil and heats the metal contained in the heating furnace directly or indirectly by high-frequency induction heating to generate a metal gas;
A control unit for controlling the power supply unit;
An apparatus for generating metal gas in a reduction casting method, comprising: an introduction path for introducing metal gas generated in the heating furnace into the cavity. The metal gas generator in the reduction casting method according to claim 6, further comprising a chamber for temporarily storing the metal gas generated in the heating furnace. The metal gas generator in the reduction casting method according to claim 6 or 7, further comprising a crucible in which metal is accommodated in the heating furnace. The metal in the reduction casting method according to claim 8, wherein the crucible is made of a material heated by high frequency induction heating, and the metal is indirectly heated by the heating of the crucible to generate a metal gas. Gas generator. The metal gas generator in the reduction casting method according to claim 6, further comprising a carrier gas supply unit that introduces a carrier gas into the heating furnace. The metal gas generator in the reduction casting method according to claim 10, wherein magnesium is used for the metal and argon gas is used for the carrier gas. A temperature detection unit for detecting the temperature in the heating furnace;
The control unit is configured to maintain the required set temperature lower than the metal gas generation temperature by the control unit and to heat the inside of the heating furnace each time during casting to generate metal gas. The metal gas generator in the reduction casting method according to any one of claims 6 to 11, wherein the part is controlled.

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