JPH0910905A - Vacuum casting method and vacuum casting equipment - Google Patents

Abstract

PURPOSE: To obtain the reduction of cost and a space and to facilitate the maintenance of a device by reducing the pressure in a cavity with a porous material and flowing molten metal therein. CONSTITUTION: The cavity 6 is formed in a openable/closable die 2 in the closed condition and a chamber 3 is made to be communicatable with the cavity 6. A porous material 1 is arranged in the chamber 3 and an extra-low temp. gas supplying source 5 is communicated through a passage 10 and a valve 4. A sensor 8 for detecting the flowing of molten metal into the cavity 6. Then, the extra-low temp. gas is supplied into the porous material 1 to cool the porous material 1 and a property absorbing the air into this material is generated to reduce the pressure in the cavity. Successively, the molten metal is flowed into the cavity. By this method, the porous material can repeatedly be used and the durability of the device can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum casting method and a vacuum casting apparatus for depressurizing the inside of a cavity by utilizing an air adsorption action which indicates that a porous material is cooled to an extremely low temperature.

[0002]

2. Description of the Related Art Conventionally, there has been known a vacuum casting method such as a vacuum die casting method in which a cavity is depressurized and a molten metal is injected into the cavity for the purpose of obtaining a product having no porosity. In the conventional vacuum casting method, as disclosed in, for example, Japanese Patent Laid-Open No. 60-56464, a mechanical means is used to generate a vacuum in a cavity, and a vacuum pump, a vacuum tank, and these are operated. Needed control equipment.

[0003]

However, in the conventional method,
There were problems in cost, space, and equipment maintenance due to equipment such as vacuum pumps and control equipment. It is an object of the present invention to provide a vacuum casting method and a vacuum casting apparatus that generate a vacuum in a cavity without using a mechanical vacuum pump.

[0004]

The method and apparatus of the present invention for achieving the above object are as follows. (1) A step of arranging a porous material in a chamber that can communicate with a cavity in a mold, supplying a cryogenic gas to the porous material to cool the porous material, and supplying air to the porous material. A vacuum casting method comprising: a step of depressurizing the inside of the cavity by causing an adsorption property; and a step of flowing a molten metal into the cavity. (2) A chamber that can communicate with the cavity in the mold, a porous material that is placed in the chamber, a source of cryogenic gas that can communicate with the chamber, and a passage that communicates the cavity with the chamber. A vacuum casting apparatus comprising: a shut-off mechanism for opening and closing a passage, which is provided in the passage, and a valve for opening and closing the passage, which is provided in a passage that connects the chamber and the supply source of the cryogenic gas.

[0005]

In the above method (1), the cavity is decompressed and the molten metal is injected or sucked into the cavity by utilizing the property that the porous substance adsorbs air when it becomes extremely low temperature and acts as a vacuum pump. Mechanical vacuum pumps are eliminated, reducing space, cost and equipment maintenance issues. In the apparatus of (2) above, in addition to the same operation as in the method of (1) above, since the shut-off mechanism is provided, it is possible to prevent the molten metal from entering the chamber from the cavity when the molten metal flows in.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows an apparatus (also a vacuum casting apparatus according to an embodiment of the present invention) for carrying out a vacuum casting method according to an embodiment of the present invention. As shown in FIG. 1, a vacuum casting apparatus according to an embodiment of the present invention includes a mold 2 that can be opened and closed, and a cavity 6 (product casting space) formed in the mold 2 when the mold 2 is in a closed state. A chamber 3 that can communicate with the cavity 6, and a porous substance 1 disposed in the chamber 3,
The cryogenic gas supply source 5 that can communicate with the chamber 3 and the chamber 3
And a shut-off mechanism 7 for opening and closing a passage, which is provided in a passage 9 that communicates with the cavity 6, and a valve 4 for opening and closing a passage, which is provided in a passage 10 that communicates between the chamber 3 and the supply source 5 of the cryogenic gas. With. A hot water supply pipe 11 for supplying molten metal is connected to the cavity 6. Further, a sensor 8 for detecting the inflow of the molten metal into the cavity 6 is installed in the mold 2. The melt is a metal melt, for example, an aluminum alloy melt.

The porous substance 1 has a property of adsorbing air when cooled to an extremely low temperature. This porous material 1
Examples include activated carbon, molecular sieve 4A, molecular sieve 5A, molecular sieve 13X, silica gel and the like. The surface area per gram of these porous substances 1 is as shown in Table 1, and the larger the surface area per unit weight, the larger the air adsorption amount at the cryogenic temperature. The amount of porous material 1 to be inserted into the chamber 3 is about 1/10 of the cavity 6 in volume.

[0008]

[Table 1]

The cryogenic gas supply source 5 comprises, for example, a liquid nitrogen tank, the cryogenic gas in that case is nitrogen, and the temperature thereof is an cryogenic temperature of about 73 ° K. The cryogenic gas supply source 5 is not limited to the liquid nitrogen tank,
For example, liquid oxygen or the like may be used. The shutoff mechanism 7 is composed of a mechanism that opens and closes the passage 9 by moving the shutoff pin 7a by an air (or hydraulic) cylinder 7b. In the illustrated example, the chamber 3, the passage 9, the shutoff mechanism 7
Although they are provided inside the mold 2, they may be provided outside the mold 2 as long as they are in communication with the cavity 6. The valve 4 is, for example, a solenoid valve. In addition, the inflow of the molten metal into the cavity 6 through the supply pipe 11 is performed by an injection mechanism in the die casting method, and is performed by using a differential pressure as a driving force in an apparatus having no injection mechanism.

In the vacuum casting method of the embodiment of the present invention, the step of placing the porous substance 1 in the chamber 3 which can communicate with the cavity 6 in the mold 2, and the step of supplying the cryogenic gas to the porous substance 1 to make the porous substance 1 porous. Of cooling the porous substance 1 and depressurizing the inside of the cavity 6 communicating with the chamber 3 by causing the property of adsorbing air to the porous substance 1, and injecting the molten metal (for example, molten aluminum alloy) into the cavity 6. And a step of making it.

With the solenoid valve 4 closed and the shut-off mechanism 7 open, the mold 2 is closed. At this time, the cavity 6 is in a sealed state. Then, the solenoid valve 4 is opened, and atomized cryogenic gas (for example, nitrogen gas, but not limited to nitrogen gas) is supplied to the chamber 3, and the porous substance 1 is cryogenically cooled (for example, 73 ° K). ).
As a result, the porous substance 1 exhibits an air adsorption action and reduces the pressure inside the cavity 6. When the inside of the cavity 6 is sufficiently decompressed, the shut-off mechanism 7 is closed and the solenoid valve 4 is also closed, and then the molten metal inflow process into the cavity 6 is started.
The inflow of the molten metal is detected by the sensor 8 installed in the mold 2. The inflow of the molten metal into the cavity 6 is performed by injection in a casting method having an injection mechanism such as a die casting method. If the injection mechanism is not provided, the molten metal is sucked into the cavity 6 by using a differential pressure as a driving force. To do. In the step of filling the cavity 6 with the molten metal, since the shut-off mechanism 7 is closed, the molten metal does not enter the chamber 3.

After casting, the mold 2 is opened and the product is
At the same time, the shut-off mechanism 7 is opened and returned to the position. On the other hand, porous substance 1 adsorbing air
Since the temperature rises due to heat transfer from the mold 2, the air gradually dissipates air into the atmosphere, changes to a state where it can act as a vacuum pump (air adsorbing means) again, and automatically returns to the initial state. No need for special conservation.

[0013]

According to the vacuum casting method of the first aspect, since the air adsorbing action of the porous material at a cryogenic temperature is utilized to reduce the pressure in the cavity, a mechanical air pump conventionally required is used. This eliminates the need for control equipment, reduces costs and space, and facilitates equipment maintenance.
According to the vacuum casting apparatus of claim 2, since the air adsorbing action of the porous material at a cryogenic temperature is used for depressurizing the inside of the cavity, the mechanical air pump and its control equipment which have been conventionally required are unnecessary. Therefore, cost and space can be reduced, and facility maintenance is easy. In addition to this, by providing the shut-off mechanism, invasion of the molten metal into the porous substance installation chamber is suppressed, the porous substance can be repeatedly used, and the durability of the apparatus is improved.

[Brief description of the drawings]

FIG. 1 is an apparatus for performing a vacuum casting method according to an embodiment of the present invention (also a vacuum casting apparatus according to an embodiment of the present invention).
FIG.

[Explanation of symbols]

 1 Porous substance 2 Mold 3 Chamber 4 Valve 5 Cryogenic gas supply source 6 Cavity 7 Shut-off mechanism 8 Sensor

Claims (2)

[Claims] 1. A step of arranging a porous material in a chamber that can communicate with a cavity in a mold, and supplying a cryogenic gas to the porous material to cool the porous material to form the porous material. A vacuum casting method comprising: a step of depressurizing the inside of the cavity by causing a property of adsorbing air; and a step of flowing a molten metal into the cavity. 2. A chamber capable of communicating with a cavity in a mold, a porous substance disposed in the chamber, a source of a cryogenic gas capable of communicating with the chamber, and a cavity communicating with the chamber. A vacuum casting apparatus comprising a passage opening / closing shut-off mechanism provided in the passage, and a passage opening / closing valve provided in the passage that connects the chamber and the supply source of the cryogenic gas.