JP3155142B2 - Inert gas injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inert gas blowing device. More specifically, for example, in the present invention, in low-pressure casting of metals such as aluminum and magnesium and their alloys, in order to prevent generation of oxides and oxidative combustion inside the casting apparatus, a mold and a hot water supply pipe are provided. The present invention relates to an apparatus for replacing an active atmosphere with an inert gas.

[0002]

2. Description of the Related Art FIGS. 4 and 5 show an example of a conventional inert gas blowing apparatus for preventing oxide formation and oxidative combustion in a mold and a hot water supply pipe in low pressure casting. In the structure of the conventional inert gas injection device, an annular groove 121 communicating with the inert gas injection hole 107 is formed at an interval radially outward from the peripheral surface of the sprue 103. Inwardly, a plurality of extremely shallow grooves having a width of several mm and a depth of about 0.1 mm are formed radially. The shallow groove forms a thin air passage 123 at the joint between the gate plate 104 and the heat insulating packing 105 in the joint state. The ventilation passage 123 is configured so that the pressurized molten metal cannot enter and the inert gas can pass through.

[0003] With the above-mentioned inert gas blowing device, the mold 1
After the mold closing of No. 01 is completed, an inert gas is supplied to the inert gas injection hole 107 of the gate plate 104. By this supply, the inert gas is blown from the inert gas injection hole 107 through the annular groove 121, through the thin ventilation path 123, and from various directions around the lower end of the gate 103. Thereby, the inert atmosphere in the supply pipe 106 and the cavity of the mold 101 is replaced with the inert gas. By adopting this procedure, generation of oxides and oxidative combustion in the mold 101 and the hot water supply pipe 134 are prevented.

[0004] Details of the above-mentioned "inert gas blowing method and apparatus for low-pressure casting machine" are described in Japanese Patent Publication No. 2-24183.

[0005]

However, the above-mentioned prior art has the following problems.

[0006] (1) The frequency of occurrence of troubles in which inert gas cannot be supplied due to solidification of the molten metal in the slit portion of the ventilation passage 123 is high.

(2) The molten metal tends to solidify at the lower part of the gate due to the cooling effect of the supply of the inert gas.

(3) Since the gas inlet is provided on the gate plate 104 connected to the mold, the number of man-hours for manufacturing the gate plate is increased and the maintenance of the gate plate takes time.

[0009] These problems cause a reduction in the efficiency of the casting operation and increase the cost of the cast product.

[0010] It is an object of the present invention to provide an inert gas blowing device capable of improving the working efficiency of casting.

[0011]

In order to achieve the above object, an inert gas blowing apparatus according to the present invention is used in a low pressure casting machine to supply an inert gas for supplying an inert gas into a mold gate and a stalk. In a gas blowing device, the blowing device has a plate shape.
Formed and interposed between the sluice plate and the upper end of the stalk ,
A hollow portion communicating the gate and the stalk is formed in a central portion, a supply port for supplying the inert gas is formed in an outer peripheral portion, and an annular shape communicates the supply port with the hollow portion.
A groove and a shallow groove are formed on one surface to constitute the supply path of the inert gas, and at least a portion facing the cavity is made of ceramics. .

[0012]

Further, the inert gas blowing device is composed of two parts, an outer peripheral part and an inner peripheral part. The inner peripheral part is formed of ceramics, and is a joint between the outer peripheral part and the inner peripheral part. It is preferable that a groove is formed in a ring shape, a plurality of shallow grooves are radially formed on one plane of the inner peripheral portion, and the supply port communicates with the groove and the shallow groove to form an inert gas supply path.

[0014]

Therefore, according to the inert gas blowing device of the present invention, the blowing device is formed in a plate shape so that it can be connected to the sluice plate by a stroke
Maintenance is easy because it is interposed between the ends. Ma
The contact surface of the cavity with the molten metal is made of ceramics
So it is difficult to get wet with the molten metal and has low thermal conductivity
Therefore, infiltration of molten metal into shallow groove and solidification of molten metal in shallow groove
Can be prevented.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an inert gas blowing apparatus and an inert atmosphere casting method according to the present invention. FIGS. 1 to 3 show an embodiment of an inert gas blowing apparatus and an inert atmosphere casting method of the present invention.

First, referring to FIG. 3, the overall structure of a casting apparatus to which the present embodiment is applied will be described. The casting apparatus shown in FIG. 3 includes a peripheral portion of a furnace 31 which is provided with a heating device and is sealed, a mold 1, a peripheral portion of an inert gas tank 62, and control devices 60 and 65. A crucible 32 containing a molten metal 33 is installed in a furnace 31.
3 is provided with a hot water supply pipe 34 immersed in the lower part and penetrating through the furnace 31 and protruding upward. The mold 1 is connected above the hot water supply pipe 34 via the upper stalk 12, the heat-resistant packing 5, and the gate plate 4. The gate 3 is formed over the lower end of the mold 1 and the gate plate 4. Compressed air is supplied into the furnace 31 from a pressurization control device 60, and the compressed air is configured to pressurize the inside of the furnace 31 and push up the molten metal 33 into the mold 1 through a hot water supply pipe 34.

On the other hand, an inert gas injection hole 7 is formed in the inert gas injection plate 8, and the inert gas is constituted by the gate 3, the upper stalk 12, and the like through an inert gas supply pipe 63 from an inert gas tank 62. The molten metal 33 is supplied into the passage. This supply is performed by controlling the solenoid valve 64 provided in the inert gas supply pipe 63 by the blowing control device 65.

FIG. 1 shows the path of the molten metal 33 from the hot water supply pipe 34 to the mold 1 in FIG. 3 and the supply path of the inert gas in more detail. In FIG. 1, the path of the molten metal 33 is a mold or a mold 1 for forming the shape of the casting.
And a mold surface plate 2 for fixing the mold 1 to the lower fixed platen 10, and a gate 3 which is an entrance of the molten metal 33 into the mold 1.
Plate with the mold 1, a heat-resistant packing 5 for ensuring airtightness between the gate plate 4 and the inert gas blowing device, and an upper stalk 12 connecting the hot water supply pipe 34 and the mold 1. You. The supply path of the inert gas includes an inert gas supply pipe 6, an inert gas inlet 7 for supplying the inert gas into the upper stalk 12, and an inert gas inlet for forming the inert gas inlet 7. Plate 8, silicon nitride ceramics 9 formed on the inner periphery of inert gas blowing plate 8, gas blowing annular groove 1
3. Gasket for ensuring the airtightness of the joint 14,
It is composed of 15 parts. Further, a lower fixed platen 10 for holding the mold 1, the mold surface plate 2, the inert gas supply pipe 6, and the like, and a distortion prevention jig 11 are provided.

FIG. 2 shows the above-mentioned inert gas supply path in more detail. The inert gas supply path shown in FIG. 2 includes an inert gas blowing plate 8 and a silicon nitride ceramic 9. The inert gas blowing plate 8 has a hollow circular shape at the center, and has an inert gas blowing hole 7, an annular gas blowing groove 13, and gaskets 14 and 15.

The inert gas injection hole 7 is a hole for connecting the inert gas supply pipe 6 and the inert gas injection plate 8.
At least one hole penetrating from the outer periphery of the inert gas blowing plate 8 to the central cavity is formed. Gas injection annular groove 13
Is a groove for connecting a gas passage between the inert gas injection hole 7 and the central cavity. In this embodiment,
A ring-shaped groove is provided together with the silicon nitride ceramics 9 fitted into the central cavity of the inert gas blowing plate 8. This gas injection annular groove 13 is
A ring-shaped groove for supplying the inert gas into the upper stalk 12 from the entire circumferential direction of the inert gas blowing plate 8 is opened. Gasket 1
Reference numerals 4 and 15 denote grooves for maintaining the airtightness between the inert gas blowing plate 8 and the joining member. A heat-resistant packing is inserted into the grooves. It works between the upper stalk 12.

The silicon nitride ceramics 9 is a component for forming a shallow air passage 23 together with the inert gas blowing plate 8. The air passage 23 is a very shallow groove, for example, having a width of several mm and a depth of about 0.1 mm, which connects the gas injection annular groove 13 and the inner peripheral portion in a state of being joined to the upper stalk 12. Are formed radially . Air passage 23 of this <br/> can not penetrate the molten metal 33 under pressure, and is supposed to form the inert gas can pass. The material used was ceramics, and in the examples, silicon nitride ceramics was used.

The components of the inert gas blowing plate 8 and the silicon nitride ceramics 9 are set between the heat-resistant packing 5 and the upper stalk 12, and the inert gas supply pipe 6 is connected to the inert gas blowing hole 7. Connected. In this state, the inert gas reaches the gas injection annular groove 13 from the inert gas supply pipe 6 via the inert gas injection hole 7. Gas injection annular groove 13
Reaches the inside of the path of the molten metal 33 of the nitrogen silicide ceramic 9 from the shallow groove ventilation path 23.

In the inert gas tank 62, for example,
When casting magnesium, CO ₂ gas cylinder 66 and SF ₆
The gas cylinder 67 is connected. When casting aluminum, an N ₂ gas cylinder or an Ar gas cylinder is connected. When casting magnesium, CO ₂ gas and SF ₆ gas are used in 50:
The mixed gas mixed in 1 is used. Alternatively, CO ₂ gas and SF ₆ may be used alone.

At the start of casting, after closing of the mold 1 is completed, the solenoid valve 64 is opened by a signal from the blow control device 65,
The inert gas is supplied from the inert gas tank 62 to the inert gas injection hole 7 of the inert gas injection plate 8 via the inert gas supply pipe 6. The inert gas that has reached the inert gas injection hole 7 is
The gas is blown from the lower end portion of the silicon nitride ceramics 9 to the inner periphery of the molten metal 33 through the thin gas passage 23 through the gas injection annular groove 13. By blowing the inert gas, the active atmosphere in the hot water supply pipe 34, the upper stalk 12 and the cavity of the mold 1 is replaced with the inert gas. The blowing time of the inert gas is set by a timer (not shown).

Next, compressed air is supplied from the pressurization control device 60 into the furnace 31 to pressurize the inside of the furnace 31 and raise the molten metal 33 into the hot water supply pipe 34. When the molten metal 33 reaches the upper stalk 12, the blowing of the inert gas is stopped. The control of the injection of the inert gas is such that the molten metal 33 has
Is performed by detecting the pressurizing force at the time when the pressure reaches a pressure gauge (not shown). After that, the molten metal 33 is continuously pressed
Is filled in the cavity of the mold 1, and pressurization is further performed for a predetermined time to cast a good casting. After a predetermined pressurizing time has elapsed, pressurization is stopped, and the inside of the furnace 31 is returned to atmospheric pressure. Due to this reduced pressure, the molten metal 33 descends in the hot water supply pipe 34 and returns into the crucible 32.

[0026] To resume blowing pressurized stopped simultaneously with inert gas within the furnace 31. The blowing of the inert gas is easily performed when the molten metal 33 descends because the inert gas is sucked into the hot water supply pipe 34. Further, since a large negative pressure phenomenon does not occur in the hot water supply pipe 34 due to the supply of the inert gas, a rapid inflow of air into the hot water supply pipe 34 when the casting is released is prevented. The formation of oxides and oxidative combustion in the furnace are greatly reduced.

When the casting is continuously performed, the blowing of the inert gas, which is started when the pressurization in the furnace 31 is stopped, is performed by chill time,
Continued when opening the mold. In the next casting step, the mold is closed, the pressurization in the furnace 31 is started, and the blowing of the inert gas in the previous step is continued until the molten metal 33 reaches the upper stalk 12 again. Subsequent casting steps are the same as the previous steps.

In the above embodiment, by forming the air passage 23 of the gas blowing section with ceramics,
The following effects occur.

1. Ceramics have a smaller coefficient of thermal expansion than metals and have excellent corrosion resistance to molten metal, so that the height of the space of the ventilation path can be stably maintained.

2. Since it is difficult to get wet with the molten metal, it is possible to prevent the molten metal from flowing into the ventilation path and solidifying the molten metal at the opening of the ventilation path.

3. Since the heat transfer coefficient is small, the temperature drop of the silicon nitride ceramics 9 due to the blowing of the inert gas can be suppressed, and the cooling and solidification of the molten metal can be prevented.

4. By installing a ceramic having high corrosion resistance on the side of the passage of the molten metal, the inert gas blowing plate 8 is made stronger, and the life is extended and the maintenance is facilitated.

Although the above-described embodiment is one preferred embodiment of the present invention, the present invention is not limited to this embodiment, and various modifications can be made without departing from the gist of the present invention. For example, although silicon nitride ceramics are partially used for the inert gas blowing plate, the inert gas blowing plate may also be formed integrally or separately using silicon nitride ceramics.

The material is not limited to silicon nitride ceramics, but may be silicon carbide, alumina carbon, zirconia, or the like.

[0035]

As is apparent from the above description, the inert gas blowing device according to claims 1 to 3 is separate from the gate plate.
The portion of the inert gas supply passage facing the molten metal is made of ceramics and the opening is formed by a shallow groove . Ceramics have a low thermal conductivity and a low coefficient of thermal expansion, do not easily wet the molten metal, and have high corrosion resistance.

(1) It is difficult for the molten metal to flow into the supply path of the inert gas .

(2) Solidification hardly occurs in the supply path of the inert gas .

(3) The life of the inert gas injection device can be extended.

Further, the above inert gas blowing device has a gate plate and
Since is a plate-like body separate to form a shallow groove in one of the planes <br/> constituting the apertures of the inert gas injection into the cavity by the shallow grooves, (4) construction It is simple and easy to process and maintain.

The inert gas purging device according to claim 2, since that is composed of two parts of the inner peripheral portion and outer peripheral portion, and (5) facilitate the formation of the supply path of the inert gas.

The inert gas blowing device according to the third aspect of the present invention has a plurality of openings . (6) The capability of supplying the inert gas is increased, the descending speed of the molten metal can be increased, and the casting cycle can be improved. Can be shortened.

[Brief description of the drawings]

FIG. 1 is a detailed sectional view of a molten metal path and an inert gas passage section of a low pressure casting apparatus to which an inert gas blowing apparatus of the present invention is applied.

FIG. 2 is a detailed cross-sectional view of an inert gas blowing plate constituting the inert gas blowing device of the present invention.

FIG. 3 is a diagram showing a cross section of a low-pressure casting apparatus to which the inert gas blowing apparatus of the present invention is applied and a configuration of peripheral devices.

FIG. 4 is a detailed sectional view of a molten metal path and an inert gas passage of a low-pressure casting apparatus to which the prior art inert gas blowing apparatus corresponding to FIG. 1 is applied.

FIG. 5 is a detailed cross-sectional view of an inert gas blowing plate constituting the prior art inert gas blowing device corresponding to FIG. 2;

[Explanation of symbols]

 1,101 mold, 2 mold surface plate, 3,103 gate, 4,104 gate plate, 5,105 heat-resistant packing, 6,106 inert gas supply pipe, 7,107 inert gas blowing hole, 8 inert Gas blow plate, 9 silicon nitride ceramics, 10 lower fixed platen, 11 distortion prevention jig, 12 upper stalk, 13 gas injection annular groove, 14, 15 gasket, 23, 123 ventilation path, 31 furnace, 33 molten metal, 32 crucible, 34 Hot water supply pipe, 60, 65 control device, 62 inert gas tank, 63 inert gas supply pipe, 64 solenoid valve, 66, 67 gas cylinder, 121 annular groove, 134 hot water supply pipe.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B22D 18/04

Claims (3)

(57) [Claims] 1. An inert gas blowing device used in a low-pressure casting machine for supplying an inert gas into a gate and a stalk of a mold, wherein the blowing device is formed in a plate shape and has a gate plate and an upper end of the stalk.
Is interposed between said cavity for communicating the sprue and stalk is formed in the central portion, the supply port for supplying an inert gas is formed in the outer peripheral portion, the hollow portion and the supply port The annular groove and the shallow groove
Formed on one side to constitute the supply path for the inert gas.
An inert gas blowing device characterized in that at least a portion facing the hollow portion is made of ceramics. Wherein said inert gas purging means is constituted by two portions of the outer peripheral portion and an inner peripheral portion, the inner peripheral portion of claim 1, characterized in that it is formed by the ceramic not Active gas injection device. 3. A joint portion between the outer peripheral portion and the inner peripheral portion, wherein a groove is formed in the one plane in a ring shape, and a plurality of the shallow grooves are formed radially in the one plane in the inner peripheral portion. inert gas purging means according to claim 2, characterized in that it is.