JP2009178722A - Low-pressure casting apparatus and low-pressure casting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-pressure casting apparatus capable of preventing the liquid level of a metal melt from being raised within an inert gas supply pipe by pressurization into a pressurization chamber during filling of the metal melt into a cavity, and a low-pressure casting method using the low-pressure casting apparatus. <P>SOLUTION: A gas supply pie 31 and an inert gas supply pipe 41 are connected via a communicative connection pipe 33, and are communicatively connectable through the communicative connection pipe 33 with each other. The communicative connection pipe 33 is provided with a first valve 34 consisting of a solenoid valve, and the first valve 34 is movable between the communicative connection position and a shutoff position. By setting first valve in the communicative connection position, the inside of the gas supply pipe 31 and the inside of the inert gas supply pipe 41 are communicative connected, and by setting the first valve in the shutoff position, the inside of the gas supply pipe 31 and the inside of the inert gas supply pipe 41 are shutoff. Air is supplied from a gas supply device 32 to the gas supply pie 31, and through a part of the communicative connection pipe 33 and the inert gas supply pipe 41 into the pressurization chamber 10 to pressurize the inside of the pressurization chamber 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a low-pressure casting apparatus and a low-pressure casting method, and in particular, a low-pressure casting apparatus including an inert gas supply means for supplying an inert gas to a molten metal in a pressurizing chamber. The present invention relates to a low pressure casting method performed using a casting measure.

  Conventionally, as a low pressure casting apparatus, an inert gas is supplied to a metal mold in which a stalk extending in the vertical direction in the pressurizing chamber, a cavity communicating with the upper end of the stalk is formed, and a molten metal in the pressurizing chamber. The thing of the structure which has an inert gas supply means for doing is known.

Japanese Patent Application Laid-Open No. 2001-71116 describes a low-pressure casting apparatus having this configuration. The lower end of the stalk is opened in the pressurizing chamber, and the molten metal is held in the pressurizing chamber. Further, an inert gas supply pipe is provided, one end of the inert gas supply pipe is connected to the inert supply device, and the other end is opened in the molten metal in the pressurizing chamber. During casting, an inert gas is supplied to the molten metal in the pressurizing chamber through the inert gas supply pipe, and the molten metal is degassed. Further, by supplying gas into the pressurizing chamber and pressurizing the pressurizing chamber, the molten metal in the pressurizing chamber flows into the stalk from the lower end of the stalk, and is filled into the cavity via the stalk.
JP 2001-71116 A

  However, in the above-described conventional low pressure casting apparatus, in order to fill the cavity with the molten metal from the pressurizing chamber through the stalk, a gas is supplied into the pressurizing chamber to pressurize the pressurizing chamber. However, at this time, the molten metal in the pressurized chamber flows not only into the stalk but also into the inert gas supply pipe. The liquid level rises. The molten metal whose liquid level has risen in the inert gas supply pipe is cooled and solidified in the inert gas supply pipe. For this reason, the inert gas supply pipe is clogged with the solidified molten metal, and when continuous casting is performed, the inert gas can be supplied to the molten metal in the pressurizing chamber during the second and subsequent castings. The problem of not being possible arises.

  Accordingly, the present invention provides a low pressure casting apparatus capable of preventing the liquid level of the molten metal from rising and solidifying in the inert gas supply pipe due to pressurization in the pressurizing chamber when the molten metal is filled into the cavity. And a low-pressure casting method performed using the low-pressure casting apparatus.

  In order to achieve the above object, the present invention stores a casting machine 20 having a stalk 21 extending in the vertical direction and a mold 22 having a cavity 22a formed at the upper end of the stalk 21 and a molten metal 2 stored therein. Pressurized chamber 10, gas supply pipe 31 for supplying gas into pressurizing chamber 10, and gas supply device for supplying gas into gas supply pipe 31 connected to gas supply pipe 31 32, a pressurizing means 30 having an opening 32 in the melt 2 in the pressurizing chamber 10, and an inert gas supply pipe 41 for supplying an inert gas connected to the inert gas supply pipe 41. An inert gas supply means 40 having an inert gas supply device 42 for supplying an inert gas into the inert gas supply pipe 41, and the lower end of the stalk 21 opens in the pressurizing chamber 10. In the pressurizing chamber 10 by the pressurizing means 30 In the low pressure casting apparatus 1 capable of being filled with the molten metal 2 in the pressurizing chamber 10 from the lower end of the stalk 21 into the stalk 21 by being pressurized, and filling the cavity 22a through the stalk 21. A communication pipe 33 that is connected to the gas supply pipe 31 and the inert gas supply pipe 41 and communicates the gas supply pipe 31 and the inert gas supply pipe 41 is provided. There is provided a low pressure casting apparatus 1 provided with a first valve 34 for switching communication / blocking between a pipe 31 and an inert gas supply pipe 41.

  Here, one end 41 </ b> A of the inert gas supply pipe 41 is connected to the inert gas supply apparatus 42, and the other end 41 </ b> B opens into the molten metal 2 of the pressurizing chamber 10. The second valve 43 is provided in a portion closer to the inert gas supply device 42 than the portion connected to the communication pipe 33, and the second valve 43 is provided with the inert gas supply. It is preferable that communication / blocking between the one end 41 </ b> A side and the other end 41 </ b> B side in the pipe 41 can be switched.

  One end 41A of the inert gas supply pipe 41 is connected to the inert gas supply apparatus 42, and the other end 41B opens into the molten metal 2 of the pressurizing chamber 10, and a part of the inert gas supply pipe 41 is provided. A third valve 44 is provided in a portion closer to the other end 41B of the inert gas supply pipe 41 than a portion connected to the communication pipe 33, and the third valve 44 It is preferable that communication / blocking between the one end 41A side and the other end 41B side in the active gas supply pipe 41 can be switched.

  Further, one end 31 A of the gas supply pipe 31 is connected to the gas supply device 32, and the other end 31 B opens into the pressurizing chamber 10, and is a part of the gas supply pipe 31 and connected to the communication pipe 33. A branch pipe 35 branched from the gas supply pipe 31 is provided in a part closer to the gas supply device 32 than the part where the gas supply pipe 32 is provided. It is preferable that the 4th valve 36 which can switch interruption | blocking is provided.

  Further, one end 31 A of the gas supply pipe 31 is connected to the gas supply device 32, and the other end 31 B opens into the pressurizing chamber 10, and is a part of the gas supply pipe 31 and connected to the communication pipe 33. A fifth valve 37 is provided in a portion closer to the other end 31B of the gas supply pipe 31 than a portion where the gas supply pipe 31 is provided, and the fifth valve 37 is connected to the one end 31A side and the other end in the gas supply pipe 31. It is preferable that communication / blocking with the 31B side can be switched.

  The present invention also provides a low pressure casting method for performing low pressure casting using the low pressure casting apparatus 1.

  According to the low-pressure casting apparatus according to claim 1 of the present invention and the low-pressure casting method according to claim 6, the gas supply pipe and the inert gas supply pipe are connected to each other and connected to the gas supply pipe and the inert gas supply pipe. A communication pipe is provided, and the communication pipe is provided with a first valve for switching communication / blocking between the gas supply pipe and the inert gas supply pipe. By making the inert gas supply pipe communicate with each other, the gas supplied from the gas supply device into the gas supply pipe can be flowed into the inert gas supply pipe through the communication pipe, and the gas supply pipe and the inert gas supply Gas can be supplied into the pressurizing chamber from both the pipe. For this reason, it is possible to prevent the liquid level of the molten metal from rising in the inert gas supply pipe by pressurizing the inside of the pressurizing chamber, and that the molten metal whose liquid level has risen solidifies in the inert gas supply pipe. Can be prevented.

  According to the low pressure casting apparatus according to claim 2 and the low pressure casting method according to claim 6, the inert gas supply apparatus is more than a part of the inert gas supply pipe connected to the communication pipe. Since the second valve is provided at the close side, the second valve is switched and the one end side and the other end side in the inert gas supply pipe communicate with each other with respect to the second valve. Can be supplied to the other end side of the inert gas supply pipe from the second valve. Moreover, the other end of the inert gas supply pipe is switched over from the second valve by switching the second valve so that one end side and the other end side in the inert gas supply pipe are blocked with respect to the second valve. The supply of inert gas to the side can be stopped.

  According to the low-pressure casting apparatus according to claim 3 and the low-pressure casting method according to claim 6 of the present invention, the inert gas supply pipe is more than the part of the inert gas supply pipe that is connected to the communication pipe. Since the third valve is provided near the other end of the first valve, the third valve is switched to the one end side in the inert gas supply pipe until the third valve starts to pressurize. The other end side can be cut off.

  According to the low-pressure casting apparatus according to claim 4 and the low-pressure casting method according to claim 6 of the present invention, a part of the gas supply pipe closer to the gas supply apparatus than a part connected to the communication pipe. Is provided with a branch pipe branched from the gas supply pipe, and the branch pipe is provided with a fourth valve capable of switching communication / blocking between the gas supply pipe and the atmosphere. The inside of the gas supply pipe and the pressurized chamber can be communicated with the atmosphere, and the gas in the pressurized chamber in a pressurized state can be discharged to the atmosphere so that the pressurized chamber can be at atmospheric pressure. In addition, by switching the fourth valve to shut off the gas supply pipe, the pressurized chamber, and the atmosphere, the pressurized chamber can be sealed, and the gas can be added by supplying gas into the pressurized chamber. The pressure chamber can be pressurized.

  According to the low-pressure casting apparatus according to claim 5 of the present invention and the low-pressure casting method according to claim 6, the gas supply pipe is closer to the other end than the part of the gas supply pipe connected to the communication pipe. Since the fifth valve is provided in this part, the fifth valve is switched, and the first valve and the other end in the gas supply pipe are communicated with each other with respect to the fifth valve. Rather, the gas can be supplied to the other end of the gas supply pipe and supplied to the pressurizing chamber. In addition, by switching the fifth valve and shutting off the one end side and the other end side in the gas supply pipe with respect to the fifth valve, the gas to the other end side of the gas supply pipe rather than the fifth valve Can be stopped and pressurization in the pressurization chamber can be stopped.

  A low-pressure casting apparatus and a low-pressure casting method according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the low-pressure casting apparatus 1 includes a pressurizing chamber 10, a casting machine 20 having a stalk 21 and a mold 22, which will be described later, a pressurizing unit 30, and an inert gas supply unit 40. Control device. The pressurizing chamber 10 is defined by a wall portion 10A made of a heat insulating material, and the periphery of the wall portion 10A is covered with a casing (not shown) made of an iron plate. A metal melt 2 made of an aluminum alloy is stored in the pressurizing chamber 10.

  A mold 22 is connected to the upper end portion of the stalk 21, and the mold 22 is supported by the mold support member 11. The mold 22 includes a lower mold 22A and an upper mold 22B (FIG. 2 and the like), and the upper mold 22B can be separated from and connected to the lower mold 22A. The upper die 22B approaches the lower die 22A and comes into contact with the lower die 22A, so that a cavity 22a (FIG. 2 and the like) is defined by the upper die 22B and the lower die 22A. The upper end of the stalk 21 communicates with a runner 22b formed in the lower mold 22A of the mold 22, and as shown in FIG. 2, the stalk 21 communicates with the cavity 22a via the runner 22b. . The portion other than the upper end portion of the stalk 21 is located in the pressurizing chamber 10, and the lower end of the stalk 21 is opened in the pressurizing chamber 10.

  A pressurizing means 30 is connected to the pressurizing chamber 10. The pressurizing means 30 includes a gas supply pipe 31 and a gas supply apparatus 32, and an upper end of the gas supply pipe 31 shown in FIG. 1 which is one end 31 </ b> A of the gas supply pipe 31 is connected to the gas supply apparatus 32. The gas supply device 32 can supply gas into the gas supply pipe 31. The lower end of the gas supply pipe 31 shown in FIG. 1 which is the other end 31 </ b> B of the gas supply pipe 31 opens into the gas phase of the pressurizing chamber 10.

  Further, an inert gas supply means 40 is connected to the pressurizing chamber 10. The inert gas supply means 40 includes an inert gas supply pipe 41 and an inert gas supply device 42, and the upper end of the inert gas supply pipe 41 shown in FIG. 1, which is one end 41 </ b> A of the inert gas supply pipe 41. Is connected to an inert gas supply device 42, and the inert gas supply device 42 can supply gas into the inert gas supply pipe 41. The lower end of the inert gas supply pipe 41 shown in FIG. 1, which is the other end 41 </ b> B of the inert gas supply pipe 41, opens into the molten metal 2 in the pressurizing chamber 10. The inert gas supply device 42 can supply argon gas as an inert gas.

  The gas supply pipe 31 and the inert gas supply pipe 41 are connected via a communication pipe 33 and can communicate with each other through the communication pipe 33. The communication pipe 33 is provided with a first valve 34 made of an electromagnetic valve, and the first valve 34 is movable between a communication position and a cutoff position. By setting the communication position, the gas supply pipe 31 and the inert gas supply pipe 41 can be communicated with each other. By switching from the communication position to the shut-off position, the gas supply pipe 31 and the inert gas supply pipe 41 can be communicated. It is comprised so that the inside can be interrupted | blocked.

  A second valve 43 formed of an electromagnetic valve is provided in a portion of the inert gas supply pipe 41 that is closer to the inert gas supply device 42 than a portion connected to the communication pipe 33. The second valve 43 is movable between the communication position and the shut-off position, and by setting the communication position, the one end 41A side and the other end 41B side in the inert gas supply pipe 41 can be communicated. By switching from the communication position to the blocking position, the one end 41A side and the other end 41B side in the inert gas supply pipe 41 can be blocked. For this reason, the supply of the inert gas to the other end 41 </ b> B side of the inert gas supply pipe 41 can be stopped from the second valve 43.

  A part of the inert gas supply pipe 41 and a portion closer to the other end 41B of the inert gas supply pipe 41 than a part connected to the communication pipe 33 is provided with a third valve 44 made of an electromagnetic valve. It has been. The third valve 44 can move between the communication position and the shut-off position, and by setting the communication position, the one end 41A side and the other end 41B side in the inert gas supply pipe 41 can be communicated. By switching from the communication position to the blocking position, the one end 41A side and the other end 41B side in the inert gas supply pipe 41 can be blocked.

  A branch pipe 35 branched from the gas supply pipe 31 is provided in a part of the gas supply pipe 31 closer to the gas supply device 32 than a part connected to the communication pipe 33. One end of the branch pipe 35 is connected to the gas supply pipe 31, and a fourth valve 36 made of an electromagnetic valve is provided at the other end. The fourth valve 36 is movable between a communication position and a shut-off position, and by setting the communication position, the inside of the gas supply pipe 31 and the branch pipe 35 can be communicated with the atmosphere and pressurized. The gas in the pressurized chamber 10 can be discharged into the atmosphere to make the pressurized chamber 10 atmospheric pressure. Further, by switching from the communication position to the shut-off position, the gas supply pipe 31 and the branch pipe 35 can be shut off from the atmosphere, the inside of the pressurizing chamber 10 can be sealed, and the pressurizing chamber The inside of the pressurizing chamber 10 can be pressurized by supplying gas into the inside.

  A fifth valve 37 formed of an electromagnetic valve is provided in a part of the gas supply pipe 31 that is closer to the other end 31B of the gas supply pipe 31 than a part connected to the communication pipe 33. The fifth valve 37 can move between the communication position and the shut-off position. By setting the fifth valve 37 to the communication position, the one end 31A side and the other end 31B side in the gas supply pipe 31 can communicate with each other. By switching from the position to the shut-off position, the one end 31A side and the other end 31B side in the gas supply pipe 31 can be shut off, and the gas supply pipe 31 is connected to the other end 31B side from the fifth valve 37. The supply of gas can be stopped and the pressurization in the pressurizing chamber 10 can be stopped.

  The first valve 34, the second valve 43, the third valve 44, the fourth valve 36, and the fifth valve 37 are each connected to a control device (not shown), and the control device (not shown). Switching is performed by controlling the above. When the first valve 34, the second valve 43, the third valve 44, the fourth valve 36, and the fifth valve 37 are in the communication position, the communication amount (the amount by which the valve is opened) is finely adjusted. It is possible to finely adjust the pressure in the pressurizing chamber 10 by this fine adjustment.

  In the low pressure casting method, first, the first valve 34 is set to the shut-off position, the second valve 43 is set to the communication position, the third valve 44 is set to the communication position, the fourth valve 36 is set to the communication position, The valve 37 is set to the communication position. In this state, as shown by an arrow A in FIG. 1, argon gas is supplied from the inert gas supply device 42 to the molten metal 2 through the inert gas supply pipe 41, and so-called degassing processing is performed on the molten metal 2. At this time, since the first valve 34 of the communication pipe 33 is in the blocking position, the argon gas or the like is prevented from flowing into the gas supply pipe 31 from the inert gas supply pipe 41.

  The argon gas degassed in the pressurizing chamber 10 and the hydrogen gas discharged from the molten metal 2 by the argon gas are gas from the other end 31B of the gas supply pipe 31 as indicated by an arrow B in FIG. It flows into the supply pipe 31 and is discharged to the atmosphere through the branch pipe 35. At this time, since the first valve 34 of the communication pipe 33 is in the blocking position, the argon gas or the like is prevented from flowing into the inert gas supply pipe 41 from the gas supply pipe 31.

  Next, the upper mold 22B of the mold 22 is moved relative to the lower mold 22A, and as shown in FIG. 2, the upper mold 22B is brought into contact with the lower mold 22A and the mold 22 is clamped to close the cavity 22a. Define. Further, the first valve 34 is set to the cutoff position, the second valve 43 is set to the cutoff position, the third valve 44 is set to the cutoff position, the fourth valve 36 is set to the cutoff position, and the fifth valve 37 is set to the cutoff position. As shown in FIG.

  Next, as shown in FIG. 3, the first valve 34 is set to the blocking position, the second valve 43 is set to the blocking position, the third valve 44 is set to the blocking position, and the fourth valve 36 is set to the blocking position. The fifth valve 37 is set to the communication position. In this state, as indicated by an arrow C, the supply of air from the gas supply device 32 through the gas supply pipe 31 into the gas phase of the pressurizing chamber 10 is started, and pressurization in the pressurizing chamber 10 is started.

  Next, as shown in FIG. 4, the first valve 34 is in the communicating position, the second valve 43 is in the blocking position, the third valve 44 is in the communicating position, and the fourth valve 36 is in the blocking position. The fifth valve 37 is set to the communication position. As a result, as indicated by an arrow C in FIG. 4, air is supplied from the gas supply device 32 through the gas supply pipe 31 into the gas phase of the pressurizing chamber 10, and as indicated by an arrow D in FIG. Then, air is supplied from the gas supply device 32 through the gas supply pipe 31, the communication pipe 33, and a part of the inert gas supply pipe 41 into the pressurizing chamber 10, and the inside of the pressurizing chamber 10 is about 5 to 10 atm. Pressurize. As a result, as indicated by an arrow E, the molten metal 2 in the pressurizing chamber 10 flows into the stalk 21 and fills the cavity 22a through the stalk 21 and the runner 22b. At this time, as described above, the gas supplied from the gas supply device 32 into the gas supply pipe 31 can flow into the inert gas supply pipe 41 through the communication pipe 33, and the gas supply pipe 31 and the inert gas supply can be supplied. Since gas can be supplied into the pressurizing chamber 10 from both the pipe 41 and the pressurizing chamber 10 is pressurized, the liquid level of the molten metal 2 is prevented from rising in the inert gas supply pipe 41. It is possible to prevent the molten metal 2 whose liquid level has risen from solidifying in the inert gas supply pipe 41.

  Next, after the molten metal 2 in the cavity 22a is solidified, as shown in FIG. 5, the first valve 34 is set to the communication position, the second valve 43 is set to the cutoff position, and the third valve 44 is set to the communication position. The fourth valve 36 is in the communication position, and the fifth valve 37 is in the communication position. As a result, the inside of the stalk 21 and the pressurizing chamber 10 is opened to the atmosphere, and the air in the pressurizing chamber 10 that pressurizes the pressurizing chamber 10 is supplied with gas as shown by an arrow F in FIG. The air in the inert gas supply pipe 41 that has been exhausted to the atmosphere through a part of the pipe 31 and the branch pipe 35 and pressurized the inside of the pressurizing chamber 10 is communicated as shown by an arrow G in FIG. 33, part of the gas supply pipe 31 and the branch pipe 35 are discharged into the atmosphere. As a result, the molten metal 2 located in the stalk 21 is moved downward and the hot water is cut off.

  Next, the upper mold 22B is moved vertically upward so as to be separated from the lower mold 22A, thereby performing mold opening. At this time, the casting 2 ′ (FIG. 5) solidified in the cavity 22a is attached to the upper mold 22B. Next, the casting 2 ′ solidified in the cavity 22a is removed from the upper mold 22B by lowering an unillustrated push pin. Then, air blow is performed on the upper die 22B and the lower die 22A defining the cavity 22a, and a release agent is applied to prepare for the next casting. The above is one low-pressure casting process, and low-pressure casting is continuously performed by repeating this one low-pressure casting process.

  The low-pressure casting apparatus and the low-pressure casting method according to the present invention are not limited to the above-described embodiments, and various modifications and improvements can be made within the scope described in the claims. For example, in the present embodiment, five valves of the first valve 34, the second valve 43, the third valve 44, the fourth valve 36, and the fifth valve 37 are provided. The configuration is not limited as long as at least the first valve 34 is provided. Moreover, although the molten metal 2 was comprised from the aluminum alloy, it is not limited to an aluminum alloy. Moreover, although the inert gas supply apparatus 42 was able to supply argon gas, it is not limited to argon gas.

  The low-pressure casting apparatus and the low-pressure casting method of the present invention are extremely useful in the field of low-pressure casting in which degassing is performed on the molten metal filled in the cavity.

Schematic which shows a mode that the degassing process is performed in the low pressure casting apparatus by embodiment of this invention. Schematic which shows a mode that the pressure chamber is prepared for pressurization in the low-pressure casting apparatus by embodiment of this invention. Schematic which shows the state which started pressurizing the pressurization chamber in the low-pressure casting apparatus by embodiment of this invention. Schematic which shows the state immediately before complete | finishing the pressurization with respect to a pressurization chamber in the low pressure casting apparatus by embodiment of this invention. Schematic which shows the state which open | released the pressurization chamber to air | atmosphere in the low pressure casting apparatus by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Low pressure casting apparatus 2 Molten metal 10 Pressurization chamber 21 Stoke 22 Mold 22a Cavity 30 Pressurization means 31 Gas supply pipe 31A, 41A One end 31B, 41B The other end 32 Gas supply apparatus 33 Communication pipe 34 First valve 35 Branch pipe 36 Fourth valve 37 Fifth valve 40 Inert gas supply means 41 Inert gas supply pipe 42 Inert gas supply device 43 Second valve 44 Third valve

Claims (6)

A casting machine having a stalk extending in the vertical direction and a mold having a cavity communicating with the upper end of the stalk;
A pressure chamber in which molten metal is stored;
A pressurizing means having a gas supply pipe for supplying gas into the pressurization chamber and a gas supply device connected to the gas supply pipe for supplying gas into the gas supply pipe;
An inert gas supply pipe for opening the molten metal in the pressurized chamber to supply an inert gas and an inert gas connected to the inert gas supply pipe for supplying the inert gas into the inert gas supply pipe. An inert gas supply means having an active gas supply device,
The lower end of the stalk opens in the pressurizing chamber, and the pressurizing means pressurizes the pressurizing chamber, so that the molten metal in the pressurizing chamber flows into the stalk from the lower end of the stalk. In a low-pressure casting apparatus that can be filled into the cavity via
A communication pipe connected to the gas supply pipe and the inert gas supply pipe and communicating the gas supply pipe and the inert gas supply pipe is provided, and the communication pipe includes the inside of the gas supply pipe and the inert gas. A low-pressure casting apparatus, wherein a first valve for switching between communication / blocking with a supply pipe is provided.   One end of the inert gas supply pipe is connected to the inert gas supply apparatus, and the other end opens into the molten metal in the pressurizing chamber, and is part of the inert gas supply pipe and connected to the communication pipe. The second valve is provided in a portion closer to the inert gas supply device than the portion being provided, and the second valve is connected to the one end side and the other end side in the inert gas supply pipe. The low-pressure casting apparatus according to claim 1, wherein the shut-off can be switched.   One end of the inert gas supply pipe is connected to the inert gas supply apparatus, and the other end opens into the molten metal in the pressurizing chamber, and is part of the inert gas supply pipe and connected to the communication pipe. A third valve is provided in a portion closer to the other end of the inert gas supply pipe than a portion where the third gas is present, and the third valve is connected to the one end side and the other end side in the inert gas supply pipe. 2. The low-pressure casting apparatus according to claim 1, wherein the communication / interruption of the air can be switched.   One end of the gas supply pipe is connected to the gas supply apparatus, and the other end opens into the pressurizing chamber, and the gas supply apparatus is more than a part of the gas supply pipe connected to the communication pipe. A branch pipe branching from the gas supply pipe is provided in a portion near the gas supply pipe, and a fourth valve capable of switching communication / blocking between the gas supply pipe and the atmosphere is provided in the branch pipe. 2. The low-pressure casting apparatus according to claim 1, wherein   One end of the gas supply pipe is connected to the gas supply apparatus, and the other end opens into the pressurizing chamber, and the gas supply pipe is more than a part of the gas supply pipe connected to the communication pipe. A fifth valve is provided in a portion near the other end of the gas valve, and the fifth valve is capable of switching between communication / blocking between one end side and the other end side in the gas supply pipe. Item 1. The low pressure casting apparatus according to Item 1.   A low-pressure casting method, wherein low-pressure casting is performed using the low-pressure casting apparatus according to any one of claims 1 to 5.

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