JP4210457B2 - Casting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a casting method for obtaining a cast product by pouring molten aluminum into a cavity in a mold.
[0002]
[Prior art]
For example, a work of casting various aluminum parts by pouring a molten aluminum or aluminum alloy (hereinafter simply referred to as aluminum) into a cavity in a mold is widely performed.
[0003]
By the way, in the casting process of aluminum parts, an oxide film is easily generated on the surface of the molten aluminum poured into the cavity. For this reason, the surface tension of the molten aluminum is increased, the fluidity of the molten metal is decreased, and various casting defects are generated.
[0004]
Therefore, for example, a reduction casting method disclosed in Japanese Patent Laid-Open No. 2001-321919 is known. As shown in FIG. 5, the apparatus for carrying out this reduction casting method includes a mold 1, and this mold 1 is provided with a cavity 1a. The molten aluminum 3 stored in the pouring tank 2 can be poured into the cavity 1 a through the hole 4. The cavity 1a in the mold 1 is connected to a nitrogen gas cylinder 6 through a pipe 5a, and is connected to a vacuum generator (not shown) through a decompression pipe 5b.
[0005]
The argon gas cylinder 7 is connected to a heating furnace 9 through a pipe 8. A tank 11 containing magnesium powder is connected to the argon gas cylinder 7 via a pipe 10, and the tank 11 is connected to the pipe 8 via a pipe 12. The heating furnace 9 is configured to be able to heat the furnace temperature to a predetermined temperature via a heater 13, and the heating furnace 9 communicates with the cavity 1 a via a pipe 14 and a pipe 15.
[0006]
In such a configuration, first, a vacuum generator (not shown) is driven, and the air in the cavity 1a is sucked through the decompression pipe 5b. For this reason, when the cavity 1a is decompressed and the cavity 1a is substantially in a non-oxygen atmosphere, the vacuum generator is stopped. On the other hand, argon gas is injected into the heating furnace 9 from the argon gas cylinder 7 through the pipe 8, and the inside of the heating furnace 9 is in an oxygen-free state.
[0007]
Next, argon gas is supplied into the tank 11 from the argon gas cylinder 7 through the pipe 10, and the magnesium powder in the tank 11 is sent into the heating furnace 9 from the pipe 8. In that case, in the heating furnace 9, it is heated by the heater 13 to the furnace temperature more than the temperature which magnesium powder sublimates. Thereby, the magnesium powder sent into the heating furnace 9 is sublimated to become magnesium gas, and this magnesium gas is injected into the cavity 1 a from the pipe 14 through the pipe 15.
[0008]
After magnesium gas is injected into the cavity 1a, nitrogen gas is supplied to the cavity 1a from the nitrogen gas cylinder 6. Therefore, in the cavity 1a, the magnesium gas and the nitrogen gas react to generate magnesium nitride (Mg ₃ N ₂ ). This magnesium nitride is deposited as powder on the inner wall surface of the cavity 1a. At that time, more preferably, under the action of the vacuum generator, the cavity 1a is decompressed to positively attach the magnesium nitride to the inner wall surface of the cavity 1a.
[0009]
Therefore, the molten aluminum 3 in the pouring tank 2 is poured from the hole 4 into the cavity 1a. Magnesium nitride is a reducing substance, and oxygen is removed from the oxide film on the surface of the molten aluminum 3 when the molten aluminum 3 comes into contact with the magnesium nitride in the cavity 1a. As a result, the surface of the molten aluminum 3 is reduced to pure aluminum.
[0010]
[Problems to be solved by the invention]
However, in the above prior art, a vacuum generator (not shown) is used to make the cavity 1a a non-oxygen atmosphere, and there is a problem that the entire apparatus is considerably large. Moreover, since the cavity 1a must be kept airtight and a seal structure is required, there is a problem that the configuration is complicated.
[0011]
The present invention solves this type of problem, and aims to provide a casting method capable of effectively reducing oxygen in a cavity and efficiently performing a good casting operation with a simple process. .
[0012]
[Means for Solving the Problems]
In the casting method according to the present invention, the magnesium, by supplying a heated argon gas, after the feed comprising magnesium particulate magnesium gas and / or the magnesium gas is generated by aggregation is generated, this The supply is supplied from the supply introduction hole to the cavity in the mold. For this reason, in the cavity, the supply itself is oxidized to be in a low oxygen state, and the magnesium fine particles and / or the magnesium oxide fine particles float in the cavity and / or adhere to the inner wall surface of the cavity. Next, the molten aluminum is poured into the cavity in a state where the feed introduction hole is closed to prevent the back flow of the molten aluminum .
[0013]
Thus, in the cavity, the supply is combined with oxygen to reduce oxygen, and a seal for maintaining airtightness becomes unnecessary. Furthermore, it is possible when the molten aluminum is poured into the cavity, even if oxygen is introduced into the cavity, the magnesium particles suspended is effectively prevented that the molten aluminum is oxidized in conjunction with the oxygen . Thereby, the fluidity | liquidity of molten aluminum , etc. can be maintained and it becomes possible to perform favorable casting work smoothly.
[0014]
Moreover, since the magnesium fine particles and / or the magnesium oxide fine particles adhere to the inner wall surface of the cavity in a porous shape, an effect as a heat insulating agent can be obtained.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic configuration explanatory view of a main part of a casting apparatus 20 for carrying out a casting method according to the first embodiment of the present invention.
[0016]
The casting apparatus 20 includes a metal particle generation mechanism 22 and a casting mold 24 to which the metal particle generation mechanism 22 is attached. The metal fine particle generation mechanism 22 includes a metal holding unit 30 in which a powdered metal, for example, magnesium 26 is accommodated via filters (porous bodies) 28a and 28b made of, for example, SUS material (stainless steel), A cylindrical part 32 that is provided in the metal holding part 30 and passes through the filter 28a and supplies an inert gas, for example, argon gas, to the magnesium 26, and a flow rate of the argon gas supplied to the cylindrical part 32 And an argon gas heating control unit 36 provided in the cylindrical part 32 and for heating the argon gas supplied to the magnesium 26 to a predetermined temperature.
[0017]
As the metal accommodated in the metal holding unit 30, a metal that is more active against oxygen than the molten metal is used. For example, when the molten aluminum is used as the molten metal, for example, magnesium 26 is employed as the metal. .
[0018]
The metal holding part 30 is detachable from the mold 24 and communicates with the cavity 40 in the mold 24. Metal holder 30 is formed into a substantially box shape which penetrates, into the hole portion 40a side of the mold 24, soluble water backflow prevention mechanism 42 is mounted.
[0019]
As shown in FIGS. 1 and 2, the molten metal backflow prevention mechanism 42 includes a stay 43 fixed to the mold 24 and a slide key 44 slidable with respect to the stay 43. The stay 43 is formed with a hole 43a coaxially with the hole 40a, and the slide key 44 is formed with a hole 44a capable of opening and closing the hole 40a and the hole 43a .
[0020]
For example, the cartridge 46 is accommodated in the metal holding unit 30 in a replaceable manner. As shown in FIG. 2, the cartridge 46 includes a substantially cylindrical case 48, and a filter 28 a is inserted into the case 48 while sitting on the bottom 48 a on one end side. In the case 48, the powdered magnesium 26 is sealed between the filter 28a and the filter 28b. A thread groove 50 is formed on the inner periphery of the case 48 on the other end side, and a set screw 51 is screwed into the thread groove 50.
[0021]
The metal holding unit 30 is provided with a lid 30a that can be opened and closed in order to attach and detach the cartridge 46. For example, the lid 30 a may be configured to be swingable with respect to the metal holding unit 30 via a hinge (not shown), or may be configured to be slidable with respect to the metal holding unit 30. .
[0022]
One end of a cylindrical portion 32 is attached to the metal holding portion 30. A heating element, for example, a heating wire 54 is disposed in the cylindrical portion 32, and the heating wire 54 is connected to a power source 58 via a current / voltage controller 56 outside the cylindrical portion 32. The argon gas heating control unit 36 is configured.
[0023]
A pipe line 60 is connected to the end of the cylindrical part 32, and an argon gas cylinder 62 constituting the argon gas flow rate control unit 34 is connected to the pipe line 60. The argon gas cylinder 62 can communicate with the cylindrical portion 32 via the on-off valve 64 and the flow rate control valve 66.
[0024]
The operation of the casting apparatus 20 configured as described above will be described below in relation to the casting method according to the first embodiment.
[0025]
First, the metal holding unit 30 holds the powdered magnesium 26 held by the cartridge 46. Specifically, outside the metal holding part 30, the case 48 constituting the cartridge 46 is arranged with the bottom part 48a facing downward, and the filter 28a is inserted while sitting on the bottom part 48a. Next, after powdery magnesium 26 is appropriately put on the filter 28a, the filter 28b is inserted. Further, the set screw 51 is screwed into the thread groove 50 of the case 48, and the magnesium 26 is sealed in the cartridge 46.
[0026]
In the metal holding part 30, the lid 30a is rocked or slid in the opening direction, and after the cartridge 46 is inserted into the metal holding part 30, the lid 30a is rocked or slid in the closing direction. As a result, the cartridge 46 is loaded into the metal holding unit 30.
[0027]
Therefore, in the state where the hole 43a and the hole 40a of the stay 43 are opened via the hole 44a of the slide key 44 constituting the molten metal backflow prevention mechanism 42, the argon gas heating is performed prior to the argon gas flow rate control unit 34. The control unit 36 is driven (see FIG. 1). In the argon gas heating control unit 36, current / voltage is controlled by the controller 56, the heating wire 54 generates heat, and the inside of the cylindrical part 32 is heated. When the inside of the cylindrical part 32 reaches a predetermined temperature, the argon gas flow rate control part 34 is driven.
[0028]
In the argon gas flow rate control unit 34, the argon gas led out from the argon gas cylinder 62 is introduced into the tubular portion 32 from the pipe line 60 with the flow rate controlled by the flow rate control valve 66. The argon gas is heated to a predetermined temperature via the heating wire 54 when passing through the cylindrical portion 32, and the heated argon gas passes through the filter 28 a constituting the metal holding unit 30 and is sprayed on the magnesium 26. It is done.
[0029]
For this reason, the magnesium 26 is evaporated to generate magnesium gas, and this magnesium gas is supplied to the cavity 40 of the mold 24 along the flow of the argon gas. In the cavity 40, there is a supply 70 containing magnesium gas and magnesium fine particles produced by agglomeration of a part of the magnesium gas.
[0030]
Accordingly, in the cavity 40, the supply 70 itself is oxidized to be in a low oxygen state, and magnesium fine particles or magnesium oxide fine particles float in the cavity 40 or adhere to the inner wall surface of the cavity 40.
[0031]
Next, the slide key 44 constituting each molten metal backflow prevention mechanism 42 slides, the hole 44a moves, and the hole 43a and the hole 40a of the stay 43 are closed. In this state, for example, molten aluminum (not shown) is poured into the cavity 40 of the mold 24. At that time, magnesium fine particles (and magnesium gas) exist in the cavity 40, and the magnesium fine particles are a substance that is more easily oxidized than aluminum. Therefore, the magnesium fine particles are reliably combined with oxygen in the cavity 40 and can effectively prevent oxidation of the molten aluminum.
[0032]
In this case, in the first embodiment, since the supply 70 containing magnesium gas and / or magnesium fine particles is combined with oxygen in the cavity 40, the cavity 40 can be easily reduced in oxygen. In addition, a sealing structure for maintaining the airtightness of the cavity 40 is not required, and the configuration of the entire casting apparatus 20 is simplified.
[0033]
Furthermore, even when oxygen flows into the cavity 40 when molten aluminum is poured into the cavity 40, the floating magnesium gas and / or magnesium fine particles are likely to be combined with the oxygen. Thereby, it can prevent effectively that a molten aluminum is oxidized, it becomes possible to maintain the fluidity | liquidity of the said molten aluminum, etc., and a favorable casting operation can be performed smoothly.
[0034]
In addition, since the magnesium fine particles and / or the magnesium oxide fine particles adhere to the inner wall surface of the cavity 40 in a porous shape, an effect as a heat insulating agent is obtained. Therefore, there is an advantage that it is not necessary to provide a heat insulating agent, and a coating operation is not necessary and the operation is simplified.
[0035]
In the first embodiment, the powdered magnesium 26 is held by the cartridge 46 and is detachable from the metal holding unit 30. However, the present invention is not limited to this. For example, the magnesium 26 may be directly filled in the metal holding unit 30 or, for example, a long magnesium 26a such as a wire or a band may be held by the cartridge 46 as shown in FIG. You may arrange | position in the said metal holding | maintenance part 30. FIG.
[0036]
Figure 4 is a main part schematic diagram illustrating the configuration of a casting apparatus 100 for carrying out the casting method associated with Casting method of the present invention. In addition, the same referential mark is attached | subjected to the component same as the casting apparatus 20 which concerns on 1st Embodiment, and the detailed description is abbreviate | omitted.
[0037]
The casting apparatus 100 includes a metal fine particle generation mechanism 102 and a mold 24 on which the metal fine particle generation mechanism 102 is mounted. The metal fine particle generation mechanism 102 is provided in the cylindrical part 32 with a nitrogen gas flow rate control unit 106 provided with a nitrogen gas cylinder 104 for supplying a predetermined amount of nitrogen gas to the cylindrical part 32, and the nitrogen gas is brought to a predetermined temperature. And a nitrogen gas heating control unit 108 for heating.
[0038]
In the casting apparatus 100 configured as described above, powdered magnesium 26 (or long magnesium 26a) is accommodated in the metal holding unit 30, and first, after the nitrogen gas heating control unit 108 is driven, The nitrogen gas flow rate control unit 106 is driven. For this reason, the inside of the cylindrical part 32 is heated to a predetermined temperature, and a predetermined amount of nitrogen gas supplied from the nitrogen gas cylinder 104 into the cylindrical part 32 is heated to a desired temperature.
[0039]
Accordingly, the magnesium 26 accommodated in the metal holding part 30 evaporates when nitrogen gas having a predetermined amount and a desired temperature is supplied through the filter 28a. Then, at least a part of the magnesium gas reacts with the high-temperature nitrogen gas (3Mg + N ₂ → Mg ₃ N ₂ ) to produce fine particles of magnesium nitride (Mg ₃ N ₂ ), and the remaining magnesium gas is almost completely Changes to magnesium fine particles due to aggregation. Further, Mg ₃ N ₂ fine particles are also generated when magnesium fine particles react with high-temperature nitrogen gas.
[0040]
As a result, a supply 110 containing Mg ₃ N ₂ fine particles and magnesium fine particles is introduced into the cavity 40 of the mold 24 and is preferentially combined with oxygen in the cavity 40 to effectively oxidize the molten aluminum. Can be suppressed. For this reason, it becomes possible to maintain the fluidity and the like of the molten aluminum, and the effect that a good casting operation can be performed smoothly is obtained.
[0041]
【The invention's effect】
In the casting method according to the present invention, a supply containing magnesium gas and / or magnesium fine particles is generated by supplying a heated gas to magnesium , and then the supply is supplied to a cavity in a mold. Therefore, in the cavity, the supply is combined with oxygen to reduce oxygen, and a seal for maintaining airtightness becomes unnecessary.
[0042]
Furthermore, it is possible when the molten aluminum is poured into the cavity, even if oxygen is introduced into the cavity, the magnesium particles suspended is effectively prevented that the molten aluminum is oxidized in conjunction with the oxygen . Thereby, the fluidity | liquidity of molten aluminum , etc. can be maintained and it becomes possible to perform favorable casting work smoothly.
[0043]
Moreover, since the supply material adheres to the inner wall surface of the cavity, an effect as a heat insulating agent can be obtained, and a coating operation becomes unnecessary.
[Brief description of the drawings]
FIG. 1 is a schematic configuration explanatory diagram of a main part of a casting apparatus for carrying out a casting method according to a first embodiment of the present invention.
FIG. 2 is an exploded perspective view of a main part of the casting apparatus.
FIG. 3 is an explanatory diagram of a schematic configuration of a main part of the casting apparatus in a state where elongated magnesium is loaded.
4 is a main part schematic diagram illustrating the configuration of a casting apparatus for carrying out the casting method associated with Casting method of the present invention.
FIG. 5 is an explanatory diagram of a schematic configuration of a casting apparatus according to a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 20,100 ... Casting apparatus 22, 102 ... Metal fine particle generation mechanism 24 ... Die 26, 26a ... Magnesium 28a, 28b ... Filter 30 ... Metal holding part 32 ... Cylindrical part 34 ... Argon gas flow control part 36 ... Argon gas heating Control unit 40 ... Cavity 42 ... Melt backflow prevention mechanism 43 ... Stay 44 ... Slide key 43a, 44a ... Hole 46 ... Cartridge 54 ... Heat wire 56 ... Controller 58 ... Power source 60 ... Pipe 62 ... Argon gas cylinder 64 ... Open / close valve 70, 110 ... Supply 104 ... Nitrogen gas cylinder 106 ... Nitrogen gas flow rate control unit 108 ... Nitrogen gas heating control unit

Claims (1)

A casting method in which molten aluminum is poured into a cavity in a mold to obtain a cast product,
Supplying magnesium with heated argon gas to produce a feed containing magnesium gas and / or magnesium fine particles produced by aggregation of the magnesium gas;
By supplying the feed from the feed introduction hole to the cavity, the cavity is brought into a low oxygen state by an oxidation reaction of the feed, and the magnesium fine particles and / or the magnesium oxide fine particles are allowed to pass through the cavity. Floating and / or adhering to the inner wall of the cavity;
Pouring the molten aluminum into the cavity in a state where the feed introduction hole is blocked to prevent a back flow of the molten aluminum ;
A casting method characterized by comprising:

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