JPH1147912A - Differential pressure casting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a differential pressure casting device capable of smoothly charging a molten metal in a cavity and obtaining excellent finish without generating irregular casting and capable of stably charging the molten metal in the cavity through the molten metal charging passage because plural charging passage are freely formed at parts where a shrinkage cavity is easy to generate. SOLUTION: A molten metal chamber 16 to hold a molten metal to be fed from a molten metal guide passage 15a is provided between a molten metal holding furnace 1 and a casting die 25, a molten metal charging passage 30a is formed between the molten metal chamber 16 and the casting die 25 and a vacuum pump 46, etc., to charge a molten metal 2' into the molten metal chamber 16 via the molten metal charging passage 30a by introducing an inert gas into the molten metal chamber 16. The plural molten metal charging passages 30a are formed therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method in which
The present invention relates to a differential pressure casting apparatus in which a cavity is filled by reducing the pressure in the cavity. Here, the differential pressure casting apparatus is, for example, a casting apparatus in which the cavity is depressurized and the molten metal is sucked and filled into the cavity, or a holding furnace and the cavity are pressurized, and then the cavity is depressurized to provide a pressure difference, thereby forming the molten metal. Casting device that fills the cavity.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 5-123850, a decompression type casting in which the inside of a cavity of a mold is depressurized by a suction device and molten metal is filled into the cavity by the decompression force. There is a device.

In such a device, for example, as shown in FIG.
2 is formed, and the gate 103 communicating with the cavity 102 is formed.
Are opened at the lower part of the mold 101.

The gate 103 is connected to an upper end of a stalk 104. The lower end of the stalk 104 is immersed in the molten metal 2 in the molten metal holding furnace 105.

In the conventional apparatus having the above-described structure, the molten metal 2 is pressurized or the inside of the mold 101 is sucked by a suction device 74.
The pressure is reduced to introduce the molten metal 2 into the cavity 102. The introduced molten metal 2 is configured to be solidified in the cavity 102 to cast a product.

[0006]

However, in the casting apparatus configured as described above, when casting is performed using the large mold 101, a large amount of molten metal is always held in the molten metal holding furnace 105. I have to put it. The holding furnace 10 is set such that the pressure of the molten metal 2 raised from the stalk 104 is constant with respect to the surface S0 of the large amount of molten metal 2 as described above.
It is difficult to adjust the pressure inside 5, and there is a possibility that uneven casting may occur due to fluctuations in the pressure of the molten metal 2 raised from the stalk 104.

Accordingly, an object of the present invention is to provide a differential pressure casting apparatus capable of smoothly filling a cavity with a molten metal and obtaining a good finish without causing casting unevenness.

[0008]

According to the first aspect of the present invention, there is provided a molten metal holding furnace in which a molten metal is heated and held, and a metal melting furnace provided above the molten metal holding furnace. A molten metal chamber, a molten metal guide path whose lower end is inserted into the molten metal of the molten metal holding furnace and guides the molten metal to the molten metal chamber, and the molten metal in the molten metal holding furnace through the molten metal guiding path. Means for supplying molten metal to the molten metal chamber, means for supplying inert gas to the molten metal chamber, a casting mold disposed immediately above the molten metal chamber, a cavity provided in the casting mold, and a lower end Parts are inserted into the melt chamber and guide the melt in the melt chamber to the cavity, and the melt is depressurized into the cavity through the plurality of melt fill paths. A decompression means for Hama, in counter pressure casting and control means for actuating controls each of the units,
By the decompression means, the molten metal in the molten metal chamber is
The operation is controlled so that the cavity is filled through the plurality of molten metal filling paths.

[0010] In the above-mentioned structure, the molten metal chamber provided on the mold supporting plate is provided between the molten metal holding furnace and the metal mold from the molten metal guide path. The supplied molten metal is held at a position raised to a predetermined height from a molten metal surface position in the molten metal holding furnace.

[0010] At this time, the amount of the molten metal in the molten metal chamber may be only the amount required for one mold filling. For this reason, the molten metal surface position in the molten metal chamber can set the capacity of the molten metal chamber relatively small, so that the differential pressure can be adjusted more easily than the molten metal surface position in the conventional molten metal holding furnace. It can be balanced and held at a substantially constant position.

Then, the molten metal in the molten metal chamber is filled into the cavity from a plurality of molten metal filling paths by a filling means with a relatively small head and a small differential pressure.

Therefore, even if the size of the mold is increased, the pressure in the melt chamber is reduced by the pressure reducing means, so that the melt can be stably filled in the cavity through the melt filling path.

Therefore, without causing casting unevenness,
A good finish can be obtained by filling the cavity with the molten metal smoothly.

Further, since a plurality of the molten metal filling paths are freely formed at locations where shrinkage cavities are likely to occur, it is possible to further stably fill the cavity with the molten metal through the molten metal filling paths. Can be.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

<Mechanical Configuration of Molten Casting Side> In FIG. 1, 1 is a molten metal holding furnace heated by a heater 1b or the like, and 2 is a molten metal of aluminum, aluminum alloy, magnesium alloy or the like in the molten metal holding furnace 1. Reference numeral 3 denotes a lid closing the upper open end of the molten metal holding furnace 1, and 4 denotes a partition provided in the molten metal holding furnace 1.

In FIG. 1, the inside of a molten metal holding furnace 1 is divided by a partition wall 4 into a molten metal supply chamber (a molten metal injection chamber) 5 on the right side and a molten metal supply chamber 6 on the left side.
It is divided into and. Moreover, a communication port 1c is provided between the upper end of the partition 4 and the lid 3, and between the partition 4 and the bottom wall 1a of the molten metal holding furnace 1, the molten metal supply chamber 5, the molten metal supply chamber 6, The communication port 7 is formed to communicate with.

Reference numeral 8 denotes a degassing device (gas release device) inserted into the molten metal supply chamber 5 through the lid 3, and 9 denotes a molten metal supply provided on the lid 3 positioned on the molten metal supply chamber 5. Mouth, 10
Is a lid for closing the molten metal supply port 9, and 11 is a connection port communicating with the upper space 6a of the molten metal supply chamber 6. The degassing device 8 discharges a gas (mainly hydrogen or the like) in the molten metal 2 injected from the molten metal supply port 9 to the outside (a known structure is adopted in this configuration). .

A mold support plate 12 is disposed above the molten metal holding furnace 1, and a mold support 13 is fixed above the plate 12. A container-shaped heat insulating material 13a which is opened upward is fixed, and a cast iron molten metal container 14 which is opened upward is fixed in the heat insulating material 13a.
Are arranged. The surface of the molten metal container 14 is covered with ceramic wool or the like (not shown), and the molten metal 2 ′
And do not react chemically. 12a is an insertion hole provided in the plate 12. Moreover, the molten metal container 14 is formed in a tapered shape such that the bottom wall 14a is lowered downward toward the center.

In the center of the bottom wall 14a, a cylindrical stalk (melt guide pipe) 1 made of ceramic or the like is provided.
The upper end of 5 is fixed. The stalk 15 extends downward through the insertion hole 12 a and penetrates the lid 3 and is inserted into the molten metal 2 in the molten metal supply chamber 6. 15a
Is a molten metal guide path in the Stoke 15.

By forming the bottom wall 14a of the molten metal container 14 into a tapered shape, when the molten metal 2 'in the molten metal container 14 is pushed downward to the molten metal holding furnace 1, the molten metal 2 'Can be pushed down without remaining. A molten metal chamber 16 for the molten metal 2 ′ is formed in the molten metal container 14, and a connection port 17 communicating with an upper space 16 a of the molten metal chamber 16 is formed above the molten metal container 14.

The mold support 13 and the molten metal container 1
A sealed case 18 is provided on the top 4. The sealed case 18 closes the bottom plate 19 that closes the upper ends of the mold support 13 and the molten metal container 14, the peripheral wall member 20 that is air-tightly fixed on the bottom plate 19, and closes the upper end of the peripheral wall member 20. It has a lid 21.

Reference numeral 22 denotes a mold chamber in the sealed case 18.
Moreover, the bottom plate 19 has an upper space 16 of the molten metal chamber 16.
a level detecting sensor 23 as a detecting means projecting into the inside of the peripheral wall member 20 is fixed at the upper end of the peripheral wall member 20.
4 are formed.

A casting mold 25 is provided in the mold chamber 22. The casting mold 25 has a lower mold 26 fixed on the bottom plate 19 and an upper mold 27 arranged on the lower mold 26. The upper mold 27 is fixed to a lower surface (inner surface) of the lid 21 via a support member 28. This mold 2
A product-shaped cavity 29 is formed between 6 and 27. Further, the lower mold 26 has a plurality of molten metal filling pipes 30 extending vertically and having upper ends communicating with the cavities 29.
Has been fixed. The molten metal filling pipe 30 is connected to the bottom plate 1.
9 and protrudes into the melt chamber 16. 30
a is a molten metal filling path in the molten metal filling pipe 30. Also,
The outer peripheral surface of the molten metal filling pipe 30 and the lower surface of the bottom plate 19 are covered with a protective layer 19a made of cast iron, and the surface of the protective layer 19a is covered with ceramic wool (not shown) or the like.
The ceramic wool has a heat insulating function that prevents the protective layer 19a from chemically reacting with the molten metal and makes it difficult for the heat in the molten metal chamber 16 to be transmitted to the casting mold 25.

The lid 21 is a hydraulic cylinder (not shown)
1, the hydraulic cylinder is driven and controlled by a hydraulic circuit 31.
In addition, the mold support 13, the bottom plate 19, and the peripheral wall member 20 can be formed integrally. In addition, the mold support 13 and the peripheral wall member 20 are integrally formed, and the peripheral wall member 2
0, an inner flange is protruded from the lower end of the casting mold 2 and the bottom plate 19 is detachably attached to the inner flange.
Even if the number and position of the molten metal filling pipes 30 change due to a change in the specification of the product to be cast in Step 5, it can be dealt with only by changing the bottom plate 19.

Here, a description will be given of the amount of the molten metal 2 'stored in the molten metal chamber 16 where the molten metal 2' is deepened to near the casting mold 25 in advance before suction casting. The predetermined level S1 detected by the level detecting sensor 23 is at the lower end of the molten metal filling pipe 30, that is, at the molten metal filling path 3
0a is above the lower end. When the cavity 29 is filled with suction, the molten metal surface S1 of the molten metal chamber 16 is temporarily lowered, but the pressure P1 in the molten metal holding furnace upper space 6a is maintained. Since the molten metal is automatically supplied through the molten metal guide path 15a, the molten metal surface S1 is maintained. Note that P1 is pressure-corrected every several shots as the molten metal level S2 decreases.

When the molten metal surface S1 of the molten metal chamber 16 is temporarily lowered by suction filling into the cavity 29, the inert gas does not enter the cavity 29 from the molten metal filling passage 30a below the lower end of the molten metal filling passage 30a. A large amount of molten metal is required. That is, the storage amount of the molten metal 2 ′ in the molten metal chamber 16 is set such that the molten metal surface S 1 of the molten metal chamber 16 is always above the lower end of the molten metal charging path 30 a from the start of filling the cavity 29 to the end of filling. ing. Note that the inert gas is for preventing oxidation of the molten metal.

The amount of molten metal stored in the molten metal chamber 16 before the start of suction is suitably 1 to 5 times the volume of the casting space including the cavity 29 above the lower end of the molten metal filling path 30a.
Under this condition, the lower end of the molten metal filling path 30a is
And does not come above, the melt 2 in the melt chamber 16
The water temperature of 'does not drop too much. Furthermore, this molten metal 2
The storage amount of 'is preferably 1 to 2 times. This is preferable for lowering the casting cycle and saving energy because the molten metal 2 in the molten metal supply chamber 6 is supplied through the stalk 15 if the molten metal surface S1 lowers even slightly.

<Molten metal pressurizing system> As described above, the molten metal holding furnace 1
Has a connection port 11 communicating with the upper space 6a of the molten metal supply chamber 6.
Is provided, and a connection port 17 communicating with the upper space 16 a is provided in the molten metal chamber 16.

The connection port 11 is connected to a pipe 32 for supplying inert gas or compressor air, and the pipe 32 is connected to a first port 33a of an exhaust valve (three-way electromagnetic switching valve) 33. 33 second port 33
A discharge side of a pressure control valve 34 for gas supply is connected to b, and a gas supply source 35 such as an inert gas or compressor air is connected to an inflow side of the pressure control valve 34. In this embodiment, the exhaust valve 33
The third port 33c is open to the atmosphere. However, the third port 33c may be connected to a gas recovery device to reuse the inert gas discharged from the third port 33c.

The connection port 17 is connected to a pipe 17a for supplying an inert gas, and the pipe 17a is connected to a first port 36a of an exhaust valve (three-way electromagnetic switching valve) 36. The discharge side of an inert gas supply pressure control valve 37 is connected to the second port 36b, and an inert gas supply source 38 is connected to the inflow side of the pressure control valve 37. In the present embodiment, the third port 36c of the exhaust valve 36 is open to the atmosphere. However, the third port 36c may be connected to a gas recovery device to reuse the inert gas discharged from the third port 36c. 36c 'is
This is a displacement control valve for controlling the discharge speed.

The pressure sensors 39, 40 are attached to the pipes 32, 17a. The gas supply source 3
5 is filled with an inert gas such as argon gas or nitrogen gas or compressor air, and the inert gas supply source 38 is filled with an inert gas such as argon gas or nitrogen gas. The pressure signals from the pressure sensors 39 and 40 are input to an arithmetic and control circuit (control means) 41, and the arithmetic and control circuit 41 converts the exhaust signals to the exhaust valves 33 and 36 and the pressure control valve 3.
4, 37 are operated.

<Decompression System> As described above, the connection port 24 for suction is formed at the upper end of the peripheral wall member 20 of the sealed case 18. The connection port 24 is connected to a pipe 42 for suction (for pressure reduction), and the pipe 42 is connected to a first port 43 a of an atmosphere release valve, that is, an atmosphere introduction valve (three-way electromagnetic switching valve) 43. A vacuum pump 46 is connected to the second port 43 b of the 43 via a pressure reducing control valve 44 as a pressure reducing means.
The third port 43c of the atmosphere introduction valve 43 is open to the atmosphere. However, the third port 43c may be connected to a gas recovery device to reuse the inert gas discharged from the third port 43c.

In addition, a vacuum sensor 45 is attached in the middle of the pipe 42. The output signal from the vacuum sensor (pressure reduction sensor) 45
The operation of the atmospheric introduction valve 43 and the pressure reduction control valve 44 is controlled by the arithmetic and control circuit 41. Note that the level detection signal from the level detection sensor 23 is also input to the arithmetic and control circuit 41.

<Operation> Next, a casting process involving a control operation by the arithmetic and control circuit 41 having such a configuration will be described with reference to FIGS. 2 and 3 schematically show the entire casting process. Therefore, the minimum reference numerals required for the description among the reference numerals shown in FIG. 4 to 9.

In FIG. 2, (a) shows the pressure in the upper space 16a of the molten metal chamber 16 (pressure in the molten metal chamber), and (b) shows the pressure in the upper space 6a of the molten metal holding furnace 1 (pressure in the molten metal holding furnace). (C) shows the suction pressure acting on the casting mold 25. The pressure characteristic curve 50 of (a) and the pressure characteristic curve 51 of (c) show that the molten metal 2 is pushed up to a predetermined height in the molten metal chamber 16, and the molten metal surface S 1 of the molten metal 2 ′ in the molten metal chamber 16 is changed. When the pressure in the upper space 16a in the molten metal chamber 16 is made equal to the atmospheric pressure at the time when it is detected by the molten metal level detection sensor 23, the pressure in the upper space 16a is shown as "0". The pressure characteristic curve 52 of (b) indicates that when no pressure is applied to the molten metal surface S2 in the molten metal supply chamber 6, that is, when the pressure in the upper space 6a of the molten metal supply chamber 6 is set to the atmospheric pressure,
The pressure in the upper space 6a is shown as "0".

(I) Start t1 in FIG. 2 is the start of (1) in FIG. 3, that is, the casting start time. In this start position, the molten metal supply chamber 6
Is "0" as shown in FIG. 2 (b). In this state, by the end of the previous casting process,
Melt guide path 15a, melt chamber 16, melt filling path 30
a and the like are filled with an inert gas. In the figure, the inert gas is represented by a set of small points.

Then, the arithmetic and control circuit 41 controls the casting mold 2
At time t1 before the mold clamping of No. 5, the ports 36a and 36b of the exhaust valve 36 are communicated, and the pressure control valve 37 is operated so that the inert gas from the inert gas supply source 38 is melted through the pipe 17a. It is supplied into the chamber 16.

(Ii) Mold clamping The operation control circuit 41 controls the operation of the hydraulic circuit 31 at time t2 immediately after the start of the supply of the inert gas to operate the hydraulic cylinder (not shown), and the lid 21 is moved to the position shown in FIG. And FIG.
3 and brought into contact with the upper end of the peripheral wall member 20 as shown in FIGS. 3 (2) and 5, and the upper opening end of the mold chamber 22 is closed and hermetically closed. At this time, the upper mold 27 is also lowered and brought into contact with the lower mold 26 to perform mold clamping.

At this point, the arithmetic control circuit 41
By connecting the ports 43a and 43c of the air introduction valve 43,
The pipe 42 is open to the atmosphere. Moreover, in this case,
The inert gas from the inert gas supply source 38 is supplied to the pipe 17a.
The inert gas is supplied into the molten metal chamber 16 via the molten metal filling path 30a.
Is supplied (filled) into the cavity 29 and leaks into the mold chamber 22 from a gap between the mating portions of the molds 26 and 27.

(Iii) Detection of the molten metal level The arithmetic and control circuit 41 stops the operation of the pressure control valve 37 at time t3 immediately after the closing of the casting mold 25 and stops the supply of the inert gas to the molten metal chamber 16. Stop.

On the other hand, the arithmetic and control circuit 41 connects the ports 33a and 33b of the exhaust valve 33 at time t3,
By operating the pressure control valve 34, the inert gas from the gas supply source 35 or the gas such as compressor air is supplied to the molten metal supply chamber 6 through the exhaust valve 33 and the pipe 32.
Is supplied to the upper space 6a by pressure to increase the pressure in the upper space 6a to P1.

As the pressure in the upper space 6a rises, the molten metal 2 in the molten metal supply chamber 6 is pushed up into the molten metal chamber 16 via the molten metal guide path 15a. The molten metal may be supplied by using an electromagnetic pump.

Then, as the molten metal 2 is pushed up,
When the molten metal surface S1 in the molten metal chamber 16 comes into contact with the molten metal surface detection sensor 23 at time t4 as shown in FIGS.
Is detected by the water level detection sensor 23, and a water level detection signal is output from the water level detection sensor 23 and input to the arithmetic and control circuit 41. In addition, the operation control circuit 41
Receives the molten metal level detection signal, controls the operation of the pressure control valve 34 to maintain the pressure P1 in the upper space 6a. In this state, the lower end of the molten metal filling pipe 30 is inserted into the molten metal 2 ′ in the molten metal chamber 16.

(Iv) Filling of the molten metal (decompression of the mold chamber 22) On the other hand, the arithmetic and control circuit 41 receives the molten metal level detection signal and holds P1 by controlling the pressure control valve 34. The pressure reduction control valve 44 is operated by communicating the ports 43a and 43b of the 43, and the pressure reduction of the mold chamber 22 is started. At this time, the pressure is detected by a vacuum sensor 45, and a detection signal from the vacuum sensor 45 is
1 is input.

At this time, the depressurizing force in the cavity 29 of the casting mold 25 changes from 0 to −P6 between time t4 and time t5.
(Kg / cm2) and then from time t5 to t
-P6 (Kg / cm2) to -P7 (Kg / c
m2) (-P6> -P7). And
The molten metal 2 ′ in the molten metal chamber 16 is sucked into the cavity 29 of the casting mold 25 through the molten metal filling path 30 a, and FIG.
And filling as shown in FIG. This filling is performed until time t5.

With this filling, the molten metal surface S1 of the molten metal 2 'in the molten metal chamber 16 tends to drop, but the molten metal supply chamber 6
The pressure in the upper space 6a of P
Is maintained so that the molten metal in the molten metal holding furnace 1 is replenished into the molten metal chamber 16 by the pressure P1, and the molten metal surface S1 is to be maintained substantially constant.

When the filling of the molten metal into the cavity 29 is completed, the heat of the molten metal in the cavity 29 is transferred to the mold 26,
After being absorbed by 27, heat is released and solidification has already started.

(Feeding water) By the start of the solidification, the molten metal filled in the cavity 29 is shrunk, so that the molten metal filled in the cavity 29 is fed into the cavity 29 in order to stabilize the quality of the cast product (product). That is, the arithmetic and control circuit 41 determines the degree of vacuum (degree of vacuum) in the mold chamber 22 before the molten metal 2 ′ in the molten metal chamber 16 falls below the lower end of the molten metal introduction pipe 30.
Reaches a predetermined value (-P6).
When a time t5 is detected based on the detection signal from the controller 3, the pressure control valve 34 is operated, and the gas such as the inert gas of the gas supply source 35 or the compressor air is discharged from the exhaust valve 3.
3 and the upper space 6a of the molten metal supply chamber 6 via the pipe 32.
And the pressure in the upper space 6a is increased from P1 to P2 in a period from time t5 to time t6.

On the other hand, the arithmetic and control circuit 41 controls the operation of the pressure control valve 37 almost simultaneously with the start of the pressure increase in the upper space 6a of the molten metal holding furnace 1, and the communication between the inert gas supply source 38 and the exhaust valve 36. Break the state. Thereby, when the pressure in the molten metal holding furnace 1 rises, the pressure in the upper space 16a of the molten metal chamber 16 is increased, and the upper space 16a is increased.
The pressure in a is increased to P3 in the time from time t5 to time t6. In addition, the inert gas supply source 3
Since the communication between the exhaust gas 8 and the exhaust valve 36 is shut off, the pressure P3 in the upper space 16a of the molten metal chamber 16 becomes the same as the pressure P2 applied to the upper space 6a of the molten metal supply chamber 6.

This pressure P2 (= P3) acts on the cavity 29 of the casting mold 25 through the molten metal 2 'in the molten metal chamber 16 and the plurality of molten metal introduction paths 30a, and the volume is reduced by cooling. Replenish the molten metal. As a result, a so-called feeder effect is provided.

The pressure P3 is maintained until the time t9 by the operation control circuit 41 controlling the pressure control valve 37 based on the detection signal of the pressure sensor 40, and the pressure P2 is calculated based on the detection signal of the pressure sensor 39. Control circuit 4
1 is maintained until time t10 by controlling the pressure control valve 34.

(Decompression stop) Also, the arithmetic control circuit 41
After detecting at time t6 that the pressure signals from the pressure sensors 39 and 40 have reached P2 and P3, at time t7 the operation of the pressure reducing control valve 44 is controlled to close the middle of the passage in the pressure reducing control valve 44 and to release the air. Inlet valve 43
The ports 43a and 43c are communicated with each other, and the pipe 42 is communicated with the atmosphere. As a result, the pressure in the mold chamber 22 rises to atmospheric pressure (here, “0”). When the pressure reduction control valve 44 is stopped, the cavity 29
The filling of the molten metal into the interior has been completed.

(V) Hot Water Draining and Hot Water Return When the predetermined time t9 elapses after the filling of the cavity 2 ″ with the molten metal 2 ″ is completed, the heat of the molten metal 2 ″ in the cavity 29 is absorbed by the molds 26 and 27. Although the heat is radiated and solidified, the molten metal in the molten metal filling path 30a is not solidified.
At this time t9, the arithmetic and control circuit 41 pressurizes and supplies the inert gas from the inert gas supply source 38 to the upper space 16a of the molten metal chamber 16 by the pressure control valve 37 to increase the pressure of the upper space 16a of the molten metal chamber 16. P3
To P4, and the molten metal in the molten metal chamber 16 is lowered to the lower end of the molten metal chamber 16 below the lower end of the molten metal introduction pipe 30 as shown in FIG. 3 (5) and FIG.

As a result, the molten gas in the molten metal filling pipe 30 is cut off at the lower end of the cavity 29 by the inert gas ascending in the molten metal filling pipe 30 and flows downward by its own weight. With the supplied inert gas, the molten metal is positively flowed down to the molten metal supply chamber 6,
Margins are made.

The operation control circuit 41 controls the operation of the pressure control valve 33 at time t10 to open the upper space 6a of the molten metal holding furnace 1 to the atmosphere, and then controls the operation of the pressure control valve 36 at time t11. Then, the upper space 16a of the molten metal chamber 16 is opened to the atmosphere, and the molten metal guide path 1 is opened.
The molten metal in 5 a is returned to the molten metal supply chamber 6. As a result, the pressure in the upper spaces 6a and 16a drops and the time t
At the time of 12, it is set to approximately “0”.

(Vi) Product take-out Then, the arithmetic and control circuit 41 controls the upper spaces 16a and 6a
Immediately after the internal pressure becomes substantially “0” at time t12, the hydraulic circuit 31 is operated and the lid 21 is lifted up by a hydraulic cylinder (not shown) to be separated upward from the peripheral wall member 20, and The mold 27 is raised integrally with the lid 21, and the upper mold 27 is separated from the lower mold 26 as shown in FIGS. Thereafter, a product receiver (not shown) is moved below the upper mold 27 to release the product held by the upper mold 27, so that the cast product (product) 60 held by the upper mold 27 is transferred to the product receiver. After receiving the product, the cast 60 is taken out by taking out the product from below the upper mold 27.

[0058]

As described above, according to the first aspect of the present invention, the molten metal chamber provided on the die supporting plate between the molten metal holding furnace and the die is provided with the molten metal guide. The molten metal supplied from the path is held at a position raised to a predetermined height from a molten metal surface position in the molten metal holding furnace.

At this time, the amount of the molten metal in the molten metal chamber may be only an amount required for one mold filling. For this reason, the molten metal surface position in the molten metal chamber can set the capacity of the molten metal chamber relatively small, so that the differential pressure can be adjusted more easily than the molten metal surface position in the conventional molten metal holding furnace. It can be balanced and held at a substantially constant position.

Then, the molten metal in the molten metal chamber is filled into the cavity from a plurality of molten metal filling paths by a filling means with a relatively small head and a small differential pressure.

Therefore, even when the size of the mold is increased, the cavity can be stably filled with the molten metal through the molten metal charging path by reducing the pressure in the molten metal chamber by the pressure reducing means.

Therefore, without causing casting unevenness,
A good finish can be obtained by filling the cavity with the molten metal smoothly.

Since the plurality of molten metal filling paths are freely formed at locations where shrinkage cavities are likely to occur, it is possible to further stably fill molten metal into the cavity via the molten metal filling path. Can be achieved, which is a practically useful effect.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a differential pressure casting device according to the present invention.

FIG. 2 is a pressure characteristic curve diagram showing a temporal relationship such as a suction pressure to a casting mold of the differential pressure casting apparatus shown in FIG.

FIG. 3 is controlled according to the pressure characteristic curve diagram of FIG. 2;
It is explanatory drawing of the casting process by the differential pressure casting apparatus.

FIG. 4 is an enlarged explanatory view of (1) of FIG. 3;

FIG. 5 is an enlarged explanatory view of (2) in FIG. 3;

FIG. 6 is an enlarged explanatory view of (3) in FIG. 3;

FIG. 7 is an enlarged explanatory view of (4) in FIG. 3;

FIG. 8 is an enlarged explanatory view of (5) in FIG. 3;

FIG. 9 is an enlarged explanatory view of (6) in FIG. 3;

FIG. 10 is an explanatory view showing an example of a conventional differential pressure casting apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Molten holding furnace 2 ... Molten 6 ... Molten supply chamber 6a ... Upper space 15 ... Stoke (melt guide pipe) 15a ... Molten guide path 16 ... Molten chamber 16a ... Upper space 25 ... Casting die 26 ... Lower die 27 ... Upper mold 29 ... Cavity 30 ... Molten filling pipe 30a ... Molten filling path 34 ... Pressure control valve (one of molten metal supply means) 35 ... Gas supply source 37 ... Pressure control valve (one of inert gas supply means) 38 ... Inert gas supply source 41 ... Operation control circuit 46 ... Vacuum pump (one of pressure reducing means) S2 ... Metal surface position (in molten metal holding furnace 1)

Claims (1)

[Claims] 1. A molten metal holding furnace in which a molten metal is heated and held, a molten metal chamber disposed above the molten metal holding furnace, and a lower end portion is inserted into the molten metal of the molten metal holding furnace and the molten metal is inserted into the molten metal. A molten metal guide path guided to the molten metal chamber;
Molten metal supply means for supplying the molten metal in the molten metal holding furnace to the molten metal chamber via the molten metal guide path, means for supplying an inert gas to the molten metal chamber, and a casting disposed immediately above the molten metal chamber. A mold, a cavity provided in the casting mold, a plurality of molten metal filling paths each having a lower end inserted into the molten metal chamber and guiding the molten metal in the molten metal chamber to the cavity; and the plurality of molten metal filling paths. In a differential pressure casting apparatus comprising: a decompression unit that fills the cavity with a molten metal by a reduced pressure via a passage; and a control unit that controls the operation of each unit, the molten metal in the molten metal chamber is reduced by the decompression unit. A differential pressure casting apparatus characterized in that the operation is controlled so that the cavity is filled through a plurality of molten metal filling paths.