JP2008044008A - Low-pressure casting apparatus, and inert gas filling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-pressure casting apparatus capable of filling an inert gas in a stoke or a guide hole by easily communicating a space formed above a molten metal in a pressurizing chamber with the guide hole to be connected to the stoke hanging from a sprue of a mold or the sprue of the mold. <P>SOLUTION: The low-pressure casting apparatus comprises a molten metal holding chamber 1 for holding a molten metal, a pressurizing chamber 2 which is communicably arranged in the molten metal holding chamber via a communication hole 4 to pressurize the molten metal with an inert gas with a lower end of a stoke 8 being opposite thereto or the other end of a guide hole 21 being connected thereto, an on-off valve 5 for opening/closing the communication hole, a pressure sensor 9 for sensing the predetermined pressure in the pressurizing chamber at which a space formed above the molten metal in the pressurizing chamber with the stoke or the guide hole when a top level of the molten metal in the pressurizing chamber is pressurized with the inert gas, the molten metal is filled in the mold, the communication hole is opened after the filled molten metal is solidified, the molten metal in the pressurizing chamber is returned to the molten metal holding chamber, and the level of the molten metal in the pressurizing chamber is lowered, and an inert gas feed means for feeding the inert gas to an upper part of the pressurizing chamber. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a low pressure casting apparatus and an inert gas filling method.

Conventionally, as a low-pressure casting machine that can efficiently replace the mold, the stalk, and the air in the holding furnace with non-oxidizing gas without complicating the structure of the casting machine, the following one has been proposed. Yes. That is, the low-pressure casting machine includes a holding furnace that is hermetically sealed, a gas supply unit that supplies a non-oxidizing gas to the holding furnace, a stalk that communicates the holding furnace and the mold, and the stalk. A position for switching the position between the casting position where the opening to the holding furnace side is immersed in the molten metal in the holding furnace and the position conversion where at least a part of the opening is opened above the molten metal surface in the holding furnace Switching means, and in a state where the stalk is moved to the replacement position, an inert gas is supplied into the holding furnace, and the holding furnace, the stalk and the air in the mold can be replaced with the inert gas. Yes.
JP 2000-42715 A

However, in the conventional low pressure casting machine configured in this way, it is necessary to raise and lower the holding furnace every time the holding furnace, the stalk and the air in the mold are replaced with the inert gas, so the casting cycle time is long. As a result, the productivity and efficiency are poor, the structure is complicated, and furthermore, there is a problem that a sufficient sealing property between the holding furnace lid and the stalk cannot be secured.

The present invention has been made in view of the above circumstances, and its purpose is to connect a space formed above the molten metal in the pressurizing chamber and a stalk or a mold pouring port suspended from the mold pouring port. An object of the present invention is to provide a low-pressure casting apparatus and a method for filling an inert gas that can easily communicate with the induction hole to fill the inert gas in the stalk or the induction hole.

In order to solve the above problems, the low-pressure casting apparatus according to the present invention pressurizes the upper surface of the molten metal with an inert gas and connects it to the stalk suspended from the mold pouring port or the induction hole connected to the mold pouring port. A casting apparatus in which a molten metal is filled in a mold; a molten metal holding chamber for holding molten metal; and a lower end of the stalk that faces the molten metal holding chamber through a communication hole. A pressurizing chamber that is connected to the other end of the mold and pressurizes the molten metal with an inert gas; an on-off valve that opens and closes the communication hole; After the molten metal is solidified, the communication hole is opened and the pressure of the inert gas is controlled to return the molten metal in the pressurizing chamber to the molten metal holding chamber and lower the molten metal level in the pressurizing chamber. When letting A predetermined value of the pressure in the pressurizing chamber that allows communication between the space formed above the melt in the pressurizing chamber and the inside of the stalk or the guide hole is detected by a decrease in the melt level in the pressurizing chamber. A pressure sensor; and inert gas supply means for supplying an inert gas to an upper portion of the pressurizing chamber.

In such a configuration, the inert gas is supplied by the inert gas supply means above the molten metal in the pressurizing chamber, and the inert gas is released so that the space above the molten metal in the pressurized chamber is excessive. The communication hole for communicating the molten metal holding chamber and the pressurizing chamber is opened and the molten metal in the molten metal holding chamber is supplied to the pressurizing chamber while preventing the pressure from being reached. The communication hole for communicating is closed. Next, an inert gas supply means supplies an inert gas at a high pressure to the pressurizing chamber to pressurize the molten metal, and the molten metal in the pressurizing chamber fills the product cavity of the mold through the stalk or the induction hole. Is done.

After the molten metal filled in the product cavity of the mold is solidified, the communication hole is opened and the pressure of the inert gas from the inert gas supply means is controlled so that the molten metal in the pressurizing chamber is returned to the molten metal holding chamber. When the melt level in the pressure chamber is lowered and the melt level in the pressurization chamber communicates the space above the melt in the pressurization chamber with the stalk or the guide hole, the pressure in the pressurization chamber becomes a predetermined value. As a result, the pressure sensor detects this predetermined value. By detecting the predetermined value of the pressure sensor, the communication hole is closed and the molten metal in the pressurizing chamber is stopped from returning to the molten metal holding chamber. Along with this, the space above the molten metal in the pressurizing chamber is communicated with the stalk or the induction hole, and the inert gas in the pressurizing chamber flows into the stalk or the induction hole. As a result, it is possible to prevent the molten metal in the guide hole from being exposed to air thereafter.

As is apparent from the above description, the present invention is such that the upper surface of the molten metal in the pressurizing chamber is pressurized with an inert gas to fill the mold with the molten metal, and after the molten metal has solidified, the communication hole is opened and inert. When the molten metal in the pressurizing chamber is returned to the molten metal holding chamber by controlling the gas pressure and the molten metal level in the pressurizing chamber is lowered, the space formed above the molten metal in the pressurizing chamber, the stalk or the induction hole Since a pressure sensor that detects a predetermined value of the pressure in the pressurizing chamber that enables communication with the pressure chamber is provided, the molten metal in the pressurizing chamber is returned to the molten metal holding chamber until the pressure sensor detects the predetermined value of the pressure in the pressurizing chamber. By lowering the melt level in the pressurization chamber, the space above the melt in the pressurization chamber communicates with the stalk or the induction hole, and the inert gas in the pressurization chamber flows into the stalk or the induction hole. Is possible Therefore, the surface of the molten metal in the stalk or the induction hole is not exposed to the air, and it is possible to accurately prevent the oxide film from being generated in the molten metal in the stalk or the induction hole. There is a practical effect.

An embodiment of a low-pressure casting apparatus to which the present invention is applied will be described in detail with reference to FIGS. As shown in FIG. 1, the low-pressure casting apparatus includes a molten metal holding chamber 1 that holds molten metal, a pressurizing chamber 2 that is arranged to communicate with the molten metal holding chamber 1 and pressurizes the molten metal with an inert gas, An open / close valve 5 that opens and closes a communication hole 4 that allows the molten metal holding chamber 1 and the pressurizing chamber 2 to communicate with each other via an auxiliary chamber 3, and a lid member 6 that closes the upper end opening of the pressurizing chamber 2 in an airtight manner. And a stalk 8 which is suspended from the pouring port of the mold 7 and vertically penetrates the lid member 6 and faces the pressurizing chamber 2, and is vertically suspended by penetrating the lid member 6 and The upper surface of the molten metal in the pressurizing chamber 2 is pressurized with an inert gas to fill the mold with the molten metal, and after the filled molten metal has solidified, the communication hole 4 is opened and the pressure of the inert gas is controlled. Then, the molten metal in the pressurizing chamber 2 is returned to the molten metal holding chamber 1 to lower the molten metal level in the pressurizing chamber 2. When the molten metal level in the pressurizing chamber 2 is lowered, the pressure in the pressurizing chamber 2 is such that the space formed above the melt in the pressurizing chamber 2 and the stalk 8 can communicate with each other. A pressure sensor 9 for detecting a predetermined value of the gas, and an inert gas supply means connected to an inert gas supply hole 10 provided in the lid member 6 to supply an inert gas to the upper portion of the pressurizing chamber 2 (see FIG. (Not shown).

And in the said inert gas supply means, the tank which stored the inert gas is connected to the said inert gas supply hole 10 via the on-off valve and the conduit | pipe. Further, an exhaust gas hole (not shown) for discharging an inert gas is provided in the upper part of the pressurizing chamber 2 so that the pressure in the space above the molten metal is almost equal to the atmospheric pressure. Is equipped with an electromagnetic on-off valve (not shown). The lid member 11 that closes the upper end opening of the molten metal holding chamber 1 is provided with a level sensor 12 and a level sensor 13 that detect an upper limit level and a lower limit level of the molten metal in the molten metal holding chamber 1, respectively. Each member 6 is provided with a level sensor 14 for detecting the upper limit level of the molten metal in the pressurizing chamber 2.

In this configuration, the inert gas is supplied from the inert gas supply hole 10 to the upper side of the molten metal in the pressurizing chamber 2 by the inert gas supply means, and the inert gas is released from the exhaust gas hole and added. While preventing the space above the molten metal in the pressure chamber 2 from becoming an excessive pressure, first, the on-off valve 5 is operated to open the communication hole 4, and the molten metal in the molten metal holding chamber 1 is moved into the pressurizing chamber 2. When the level sensor 14 detects the upper limit level of the molten metal in the pressurizing chamber 2, the on-off valve 5 is actuated and the communication hole 4 is closed. Next, an inert gas having a higher pressure is supplied from the inert gas supply hole 10 to pressurize the molten metal in the pressurizing chamber 2, and the molten metal in the pressurizing chamber 2 passes through the stalk 8 in the product cavity of the mold 6. (See FIG. 2A), after the molten metal in the product cavity of the mold 6 is solidified, the on-off valve 5 is actuated to open the communication hole 4, and the pressure of the inert gas from the inert gas supply means Is controlled, the molten metal in the pressurizing chamber 2 is returned to the molten metal holding chamber 1, the molten metal level in the pressurized chamber 2 is lowered, and the pressure sensor 9 detects that the molten metal level has reached the lower end of the stalk 8. (See FIG. 2-B) After further lowering the molten metal level by a predetermined amount, the on-off valve 5 is actuated to close the communication hole 4 (see FIG. 2-C).

In the process where the molten metal level is lowered from the lower end of the stalk 8, the inert gas in the pressurizing chamber 2 flows into the stalk 8. Next, after the inert gas is discharged from the exhaust gas hole, the pressure in the space above the molten metal in the pressurizing chamber 2 becomes substantially the same as the atmospheric pressure, and then the casting formed by solidifying the molten metal is taken out from the mold 6.

  In this low pressure casting apparatus, after the upper mold of the mold 7 is separated from the lower mold, the casting formed by solidification of the molten metal is taken out from the product cavity, and then the upper mold of the mold 7 is stacked on the lower mold to obtain the product. By defining the cavity, the inert gas in the pressurized chamber 2 can be caused to flow into the product cavity via the stalk 8 to be filled.

  In addition, in a state where the lower end of the stalk 8 is immersed in the molten metal in the pressurizing chamber 2 supplied from the molten metal holding chamber 1, a part of the lower end opening is more than the molten metal surface of the pressurizing chamber 2. As shown in FIG. 3A and FIG. 3B so as to open upward, the lower end portion of the stalk 8 is formed in an obliquely open or intermittently open shape so that the molten metal is more pressurized by pressurization with an inert gas. It is possible to smoothly flow into the stalk 8.

In the above-described embodiment, the molten metal in the pressurizing chamber 2 is filled into the product cavity of the mold 6 via the stalk 8; however, the present invention is not limited to this. For example, FIG. As shown in FIG. 3, a structure in which a guide hole 21 for guiding the molten metal in the pressurizing chamber 22 to the pouring port of the mold 6 is connected to the pressurizing chamber 22 may be adopted. In this case, the pressure sensor 29 having the same function as that of the pressure sensor 9 described above has the inside of the pressurizing chamber 22 in which the space formed above the molten metal in the pressurizing chamber 22 can communicate with the inside of the guide hole 21. A predetermined value of the pressure is detected.
The pressure sensor 9 may also be used as a pressure sensor provided to control the pressure in the pressurizing chamber 2 when the inside of the pressurizing chamber 2 is pressurized to fill the product cavity of the mold 6 with molten metal. Good.

It is a longitudinal cross-sectional view of the low-pressure casting apparatus of 1st Example to which this invention is applied. It is operation | movement explanatory drawing of the low pressure casting apparatus shown in FIG. It is a longitudinal cross-sectional view which shows the other Example of the lower end of Stoke. It is a longitudinal cross-sectional view of the low pressure casting apparatus of 2nd Example to which this invention is applied.

Explanation of symbols

1 Melting chamber 2 Pressurizing chamber 4 Communication hole 5 On-off valve 8 Stoke 21 Guide hole

Claims (4)

A casting apparatus in which the upper surface of the molten metal is pressurized with an inert gas, and the molten metal is filled into the mold through a stalk suspended from the pouring port of the mold or an induction hole connected to the pouring port of the mold;
A molten metal holding chamber for holding molten metal;
A pressurizing chamber which is arranged to be able to communicate with the molten metal holding chamber through a communication hole, has a lower end of the stalk facing or connected to the other end of the induction hole, and pressurizes the molten metal with an inert gas;
An on-off valve for opening and closing the communication hole;
The upper surface of the molten metal in the pressurizing chamber is pressurized with an inert gas to fill the mold with the molten metal. After the molten metal has solidified, the communication hole is opened and the pressure of the inert gas is controlled to control the pressure. When the molten metal in the pressure chamber is returned to the molten metal holding chamber and the molten metal level in the pressurized chamber is lowered, a space formed above the molten metal in the pressurized chamber by lowering the molten metal level in the pressurized chamber; A pressure sensor that detects a predetermined value of the pressure in the pressurizing chamber that allows communication in the stalk or in the guide hole;
An inert gas supply means for supplying an inert gas to an upper portion of the pressurizing chamber;
A low-pressure casting apparatus comprising: The low pressure casting apparatus according to claim 1,
In a state where the lower end of the stalk is immersed in the molten metal in the pressurizing chamber supplied from the molten metal holding chamber, the lower end opening is partially opened above the molten metal surface of the pressurized chamber. A low pressure casting apparatus characterized in that a lower end portion of Stoke is formed. A method of filling an inert gas in the stalk or the induction hole in the low-pressure casting apparatus according to claim 1 or 2,
The upper surface of the molten metal in the pressurizing chamber is pressurized with an inert gas, and the molten metal is filled into the mold via a stalk or induction hole. After the filled molten metal is solidified, the communication hole is opened and the inert gas is By controlling the pressure, the molten metal in the pressurized chamber is returned to the molten metal holding chamber and the molten metal level in the pressurized chamber is lowered until the pressure sensor detects that the pressure in the pressurized chamber has reached a predetermined value. A space formed above the molten metal in the pressurizing chamber is communicated with the inside of the stalk or the induction hole, and the inert gas in the pressurizing chamber is allowed to flow into the stalk or the induction hole. An inert gas filling method in a low-pressure casting apparatus. A method for filling an inert gas into a product cavity of the mold in the low-pressure casting apparatus according to claim 1 or 2,
The upper surface of the molten metal in the pressurizing chamber is pressurized with an inert gas, and the molten metal is filled into the mold via a stalk or induction hole. After the filled molten metal is solidified, the communication hole is opened and the inert gas is By controlling the pressure, the molten metal in the pressurized chamber is returned to the molten metal holding chamber and the molten metal level in the pressurized chamber is lowered until the pressure sensor detects that the pressure in the pressurized chamber has reached a predetermined value. The space formed above the molten metal in the pressurizing chamber communicates with the inside of the stalk or the guide hole, and after defining the product cavity of the mold, the inert gas is introduced into the pressurizing chamber. A method for filling an inert gas in a low-pressure casting apparatus, characterized in that the product cavity is filled with an inert gas.