JPH1157978A - Differential pressure casting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a differential pressure casting apparatus which can supply a necessary quantity of molten metal into a molten metal chamber. SOLUTION: This casting apparatus is provided with a molten metal holding furnace 1, the molten metal chamber 16 arranged above the molten metal holding furnace 1, a molten metal guiding passage 15 inserted into the molten metal 2 in the molten metal holding furnace 1 at the lower end part thereof and guiding the molten metal 2 into the molten metal chamber 16, a molten metal supplying means 35 for supplying the molten metal 2 in the molten metal holding furnace 1 into the molten metal chamber 16 through the molten metal guiding passage 15, a die cavity 29 arranged above the molten metal chamber 16, a molten metal filling passage 30 inserted into the molten metal chamber 16 at the lower end part and guiding the molten metal 2 in the molten metal chamber 16 into the die cavity 29 and a molten metal supplying means 46 for supplying the molten metal 2 in the molten metal chamber 16 into the die cavity 29 through the molten metal filling passage 30. In such a case, a projecting member 14c projected toward an opening hole 15b into the molten metal chamber 16, is arranged in the molten metal chamber 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure casting apparatus in which a differential pressure is provided between a molten metal holding furnace and a cavity, and the molten metal is filled into the cavity from the molten metal holding furnace by the differential pressure.

Here, the differential pressure casting apparatus is, for example, a casting apparatus that depressurizes a cavity and sucks molten metal to fill the cavity, or pressurizes a holding furnace and a cavity.
There is a casting apparatus in which a pressure difference is provided by reducing the pressure in the cavity to fill the cavity with the molten metal.

[0003]

2. Description of the Related Art An example of this type of differential pressure casting apparatus is shown in FIG. 10 (JP-A-5-1238).
No. 50).

This differential pressure casting apparatus comprises a holding furnace 70 for storing a molten metal 70a of aluminum, aluminum alloy or the like.
A casting mold 71 composed of a plurality of split molds 71a is disposed above the dies, and a Stoke 7 attached to the lower end of the casting mold 71 and communicating with a cavity 72 in the casting mold 71.
3 is inserted into the molten metal 70 a in the holding furnace 70, and a suction device 74 is connected to the cavity 72.

[0005] In the differential pressure casting apparatus constructed as described above, the inside of the cavity 72 is depressurized by the suction device 74 before starting the casting.
With this reduced pressure, the molten metal 70a in the holding furnace 70 is filled into the cavity 72 through the stalk 73, and the solidification of the molten metal 70a is repeated to continuously produce a cast product.

In addition, the other end of the molten metal guide path is connected to a side of a casting mold composed of a plurality of split molds disposed above the molten metal holding furnace by inserting the molten metal guide path into the molten metal holding furnace, Japanese Patent Application Laid-Open No. 4-274859 discloses a differential pressure casting apparatus for filling a molten metal in a molten metal holding furnace from a side of a casting mold into a cavity.

Furthermore, the basic structure is the same as that of the differential pressure casting apparatus disclosed in Japanese Patent Application Laid-Open No. 4-274859, and divided into four sides of a casting mold and the other end of the molten metal guide path is connected to hold the molten metal. A differential pressure casting machine that fills the cavity of the casting mold while rotating the molten metal in the furnace, prevents injection of the molten metal into the cavity, and produces a high-strength casting without gas entrainment etc. It is disclosed in JP-A-1-299754.

[0008]

However, in the above differential pressure casting apparatus, as the number of cast pieces increases,
The molten metal 70a in the holding furnace 70 gradually decreases and the molten metal 70a
Since the molten metal surface S0 gradually decreases, the distance from the molten metal surface S0 to the cavity 72 of the casting mold 71 increases.
As the distance becomes longer, the pressure for sucking the molten metal 70a into the cavity 72 also needs to be increased.

However, if the pressure reducing force is increased, the sealing performance between the split molds 71a, the sealing performance of the pipe connection to the cavity 72 and the suction device 74, and the stalk 7
It is necessary to improve the sealing performance of the connection between the casting 3 and the casting mold. For this purpose, each seal must be hermetically sealed.However, since there are hot spots in each seal, there is a problem that it is very difficult to maintain and manage the sealing performance against a large decompression force. Was.

In order to solve the problem of the conventional differential pressure casting apparatus, the present applicant has applied for a differential pressure casting apparatus as shown in FIG.

The differential pressure casting apparatus shown in FIG. 11 includes a molten metal holding furnace 80, a molten metal chamber 81 provided above the molten metal holding furnace 80, and a mold chamber provided above the molten metal chamber 81. 82 and a casting mold 83 that forms a cavity 83a housed in the mold chamber 82.

The molten metal holding furnace 80 stores a molten metal 80 a of a metal such as aluminum, an aluminum alloy, and a magnesium alloy, and a molten metal guiding path 84 for supplying the molten metal 80 a to the molten metal chamber 81 is provided in the molten metal holding furnace 80. From the molten metal chamber 81, and the tip of the molten metal guide path 84 in the molten metal holding furnace 80 is immersed in the molten metal 80a. In addition, a connection port 8 connected to a gas supply source 85 such as an inert gas or compressor air is provided above the molten metal holding furnace 80.
5a is provided.

The melt chamber 81 has a bottom wall 81a which expands upward in a tapered shape, and an opening 84a of a melt guide path 84 is located at the center of the bottom wall 71a. This melt chamber 8
The upper open end of 1 is covered with a bottom plate 82a of a mold chamber 82, and a molten metal level detector SE is provided on the bottom plate 82a. Also,
A connection port 87 a connected to an inert gas supply source 87 is formed in an upper part of the molten metal chamber 81.

The casting mold 83 comprises an upper mold 83c and a lower mold 8
The opening 86a of the molten metal filling path 86 is located on the cavity 83a side of the lower mold 83b, and the molten metal filling path 86 extends into the molten metal chamber 81. Upper mold 83c
Can be removed.

Such a differential pressure casting apparatus includes a molten metal holding furnace 8.
A gas such as an inert gas or a compressor air having a predetermined pressure is supplied from a connection port 85a of the upper space 8 in the molten metal holding furnace 80.
0b, and the molten metal 80a fills the molten metal chamber 81 via the molten metal guide path 84. Then, when the molten metal level of the molten metal 80a 'rising in the molten metal chamber 81 is detected by the molten metal level detector SE, the suction device 88 operates to reduce the pressure in the mold chamber 82 and reduce the pressure in the cavity 83a. The pressure is reduced. The pressure drop in the cavity 83a causes the melt 80a 'in the melt chamber 81 to move into the cavity 8a.
3a is filled by suction.

However, in the above differential pressure casting apparatus,
Before the start of casting in the casting process cycle, an inert gas is supplied into the melt chamber 81 and the cavity 83a from the connection port 87a connected to the inert gas supply source 87 of the melt chamber 81, and the inert gas is supplied to the melt holding furnace 80. No gas such as inert gas or compressor air is supplied from the connection port 85a connected to the gas supply source 85 such as gas or compressor air. In this state, the molten metal guide path 84
The molten metal surface inside is at the same level as the molten metal surface in the molten metal holding furnace 80.

When the casting is started, an inert gas or a gas such as a compressor having a predetermined pressure is supplied from a connection port 85a connected to a gas supply source 85 such as an inert gas or a compressor air in the upper space in the molten metal holding furnace 80. The molten metal 80a of the molten metal holding furnace 80 is supplied to the molten metal chamber 80b.
1, the molten metal surface in the molten metal chamber 81 rises, but the molten metal surface undulates due to the molten metal 80a that springs up from the central opening 84a of the bottom wall 81a, and the molten metal surface detector SE erroneously detects the undulating molten metal surface. And the molten metal chamber 8
There is a risk that the required amount of molten metal 80a 'will not be supplied into 1.

An object of the present invention is to provide a differential pressure casting apparatus capable of supplying a required amount of molten metal to a molten metal chamber.

[0019]

In order to achieve the above object, a first aspect of the present invention is a molten metal holding furnace, a molten metal chamber disposed above the molten metal holding furnace, and a lower end portion of the molten metal holding furnace. A molten metal guide path inserted into the molten metal and guiding the molten metal to the molten metal chamber, molten metal supply means for supplying the molten metal of the molten metal holding furnace to the molten metal chamber through the molten metal guiding path, and an upper part of the molten metal chamber. An arranged mold cavity, a molten metal filling path whose lower end is inserted into the molten metal chamber and guides the molten metal of the molten metal chamber to the mold cavity, and a molten metal of the molten metal chamber through the molten metal charging path. In a casting apparatus provided with a melt supply means for supplying to a mold cavity, a projecting member projecting toward an opening to the melt chamber is provided in the melt chamber. It is characterized in that there.

[0020]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIGS.

In FIG. 1, 1 is a molten metal holding furnace, 1a is a bottom wall of the molten metal holding furnace 1, 1b is a heater disposed above the molten metal holding furnace 1, 2 is aluminum, an aluminum alloy in the molten metal holding furnace 1 , A molten metal of a magnesium alloy or the like, 3 is a lid closing an upper opening end of the molten metal holding furnace 1, and 4 is a partition wall provided in the molten metal holding furnace 1.

In FIG. 1, the inside of the 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. 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 venting 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 injected from the molten metal supply port 9 to the outside (a known structure is adopted in this configuration).

A support plate 12 for supporting a mold is disposed above the molten metal holding furnace 1.
The mold support 13 is fixed to the upper part of the mold. A container-like heat insulating material 13a that opens upward is provided in the mold support base 13.
Is fixed to the heat insulating material 13a, and a molten metal container 14 made of cast iron, which is opened upward, is disposed. This molten metal container 1
4 is covered with a ceramic wool or the like (not shown) so as not to react chemically with the molten metal 2 '. Reference numeral 12a denotes an insertion hole provided in the support 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.

At the center of the bottom wall 14a, the upper end of a cylindrical stalk (melt guide path) 15 made of ceramic or the like is fixed. The molten metal guide path 15 extends downward through the insertion hole 12 a and penetrates through the lid 3 and is inserted into the molten metal 2 in the molten metal supply chamber 6. Reference numeral 15a denotes an opening in the molten metal guide path 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 down to the molten metal holding furnace 1 side, the molten metal container 14
The molten metal 2 ′ can be pushed down without remaining inside.

An upper wall 14b for covering the bottom wall 14a is provided above the bottom wall 14a.
b together with the molten metal chamber 16. Upper wall 14b
Is provided with a protruding member 14c protruding downward at the center of
The tip 14d faces the opening 15b of the molten metal guide path 15 fixed to the center of the bottom wall 14a. A connection port 17 communicating with an upper space 16a of the molten metal chamber 16 is provided at an upper portion of the molten metal container 14.

On the molten metal container 14, a closed case 18 is provided. The sealed case 18 has a bottom plate 19 on the top wall 14 b of the molten metal container 14, a peripheral wall member 20 airtightly fixed on the bottom plate 19, and a lid 21 closing the upper end of the peripheral wall member 20. Reference numeral 22 denotes a mold chamber in the closed case 18.

A molten metal level detecting sensor 23 projecting into the upper space 16a of the molten metal chamber 16 is fixed to the bottom plate 19, and a connection port 24 for suction is formed at an upper end of the peripheral wall member 20.

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. A product-shaped cavity 29 is formed between the dies 26 and 27. Further, a plurality of molten metal filling pipes 30 extending vertically and having upper ends communicating with the cavities 29 are fixed to the lower mold 26. This molten metal filling pipe 30
It penetrates through the bottom plate 19 and the upper wall 14 b of the molten metal container 14 and projects downward from the connection port 17 in the molten metal chamber 16.
Reference numeral 30a denotes a molten metal filling path in the molten metal filling pipe 30. The outer peripheral surface of the molten metal filling pipe 30, the outer peripheral surface of the protruding member 14c, and the lower surface of the upper wall 14b are covered with a protective layer 19a made of cast iron.
The surface of the protective layer 19a is covered with ceramic wool or the like (not shown). The ceramic wool prevents the protective layer 19a from chemically reacting with the molten metal 2 ', and the heat in the molten metal chamber 16 is transferred to the casting mold 25.
It also has a heat insulation function that makes it difficult to transmit to

The cover 21 is provided with a hydraulic cylinder (not shown) so as to be able to move up and down in FIG. 1. The hydraulic cylinder is driven and controlled by a hydraulic circuit 31. Further, the mold support 13, the bottom plate 19, and the peripheral wall member 20 can be integrally formed.

The mold support 13 and the peripheral wall member 20 are integrally formed, and an inner flange is protruded from the lower end of the illustrated peripheral wall member 20, 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 are changed due to a change in specifications of a product to be cast by the casting mold 25, it can be dealt with only by changing the bottom plate 19.

Here, the storage amount of the molten metal 2 'stored in the molten metal chamber 16 where the molten metal 2' is stored up to the vicinity of the casting mold 25 before performing the suction casting will be described. A predetermined level S1 detected by the level detecting sensor 23
The position is above the lower end of the molten metal filling pipe 30, that is, above the lower end of the molten metal filling path 30a. When the cavity 29 is filled with suction, the molten metal surface S1 of the molten metal chamber 16 temporarily drops, but the pressure P1 in the molten metal holding furnace upper space 6a is reduced.
Is maintained, the molten metal 2 in the molten metal supply chamber 6 is automatically supplied through the molten metal guide path 15a.
1 is maintained. The pressure P1 is 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 molten gas falls below the lower end of the molten metal charging path 30a and the inert gas is discharged.
Molten metal 2 'that does not enter cavity 29 from 0a
Need to be stored. That is, the storage amount of the molten metal 2 'in the molten metal chamber 16 is set such that the molten metal surface S1 of the molten metal chamber 16 is always above the lower end of the molten metal charging path 30a from the start of filling the cavity 29 to the end of the filling. ing. Note that the inert gas is for preventing oxidation of the molten metal.

The storage amount of the molten metal 2 '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 does not rise above the molten metal surface S1, and the temperature of the molten metal 2 'in the molten metal chamber 16 does not drop too much. Further, the storage amount of the molten metal 2 'is preferably 1 to 2 times. This is because if the molten metal surface S1 is slightly lowered, the molten metal 2 in the molten metal supply chamber 6 is supplied through the molten metal guide path 15 to raise the molten metal surface S1, thereby shortening the casting cycle and saving energy. preferable.

<Molten metal pressurizing system> The molten metal holding furnace 1 is provided with a connection port 11 communicating with the upper space 6a of the molten metal supply chamber 6, and with a connection port 17 communicating with the upper space 16a of the molten metal chamber 16. Have been. The connection port 11 has a pipe 32 for supplying inert gas or compressor air.
Is connected. A first port 33 a of an exhaust valve (three-way electromagnetic switching valve) 33 is connected to the pipe 32, and a discharge side of a gas supply pressure control valve 34 is connected to a second port 33 b of the exhaust valve 33 to control the pressure. A gas supply source 35 (melt supply means) such as an inert gas or compressor air is connected to the inflow side of the valve 34. In the present embodiment, the third port 33c of the exhaust valve 33 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. A first port 36a of an exhaust valve (three-way electromagnetic switching valve) 36 is connected to the pipe 17a, and a discharge side of a pressure control valve 37 for supplying inert gas is connected to a second port 36b of the exhaust valve 36. An inert gas supply source 38 is connected to the inflow side of the pressure control valve 37. In this 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. Note that 36
c ′ is a displacement control valve for controlling the displacement speed.

The pressure sensors 39, 40 are attached to the pipes 32, 17a. The gas supply source 35 is filled with an inert gas such as an argon gas or a nitrogen gas or compressor air.
8 is filled with an inert gas such as an argon gas or a nitrogen gas. The pressure signals from the pressure sensors 39 and 40 are input to an arithmetic control circuit (arithmetic control means) 41, which controls the operation of the exhaust valves 33 and 36 and the pressure control valves 34 and 37. I have.

<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 4 corresponding to the melt supply means of the present invention is connected to a second port 43b of the
6 is connected as pressure reducing means. The third port 43c of the air 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.

Further, a vacuum sensor 45 is mounted in the middle of the pipe 42. The output signal from the vacuum sensor (pressure reduction sensor) 45 is input to the arithmetic control circuit 41, and the operation of the atmosphere introduction valve 43 and the pressure reduction control valve 44 is controlled by the arithmetic 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, the casting process accompanying the control operation of the arithmetic and control circuit 41 having such a configuration will be described with reference to FIGS.
It will be described based on. 2 and 3 schematically show the entire casting process. The reference numerals shown in FIG. 1 are given the minimum reference numerals necessary for explanation, and the detailed reference numerals are shown in FIGS. Shown in

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 in FIG. 2A and the pressure characteristic curve 51 in FIG. 2C indicate that the molten metal 2 is pushed up to a predetermined height in the molten metal chamber 16 and the molten metal 2 ′ in the molten metal chamber 16. At the time when the molten metal level S1 is detected by the molten metal level detection sensor 23,
When the pressure in the upper space 16a in the melt chamber 16 is made equal to the atmospheric pressure, the pressure in the upper space 16a is set to "0".
It is illustrated as The pressure characteristic curve 5 in FIG.
2, when the pressure is not 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 set to "0". ".

(I) Start The time t1 in FIG. 2 corresponds to the start in FIG. 3A, that is, the start of casting. At this start point, the pressure in the upper space 6a of the molten metal supply chamber 6 is "0" as shown in FIG. In this state, the molten metal guide path 15, the molten metal chamber 16, the molten metal filling path 30a and the like are filled with an inert gas by the end of the previous casting process. 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 a 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. The supply into the chamber 16 is started.

(Ii) Clamping The arithmetic control circuit 41 controls the operation of the hydraulic circuit 31 at time t2 after the start of the supply of the inert gas to operate the hydraulic cylinder (not shown), and moves the lid 21 to the position shown in FIG. And FIG.
5 and is brought into contact with the upper end of the peripheral wall member 20 as shown in FIGS. 3 (2) and 5, and the upper open 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 operation control circuit 41
Communicates the ports 43a and 43c of the atmosphere introduction valve 43 to open the pipe 42 to the atmosphere. At this time, since the inert gas from the gas supply source 38 is supplied into the molten metal chamber 16 through the pipe 17a, the inert gas enters the cavity 29 of the casting mold 25 through the molten metal filling path 30a. While being supplied (filled), it leaks into the mold chamber 22 from a gap or the like between the mating portions of the molds 26 and 27.

(Iii) Detection of 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, a gas such as an inert gas or compressor air is pressurized and supplied from the gas supply source 35 to the upper space 6 a of the molten metal supply chamber 6 through the exhaust valve 33 and the pipe 32, and the upper space 6 a Pressure inside
Increase to 1. With the increase in the pressure in the upper space 6a, the molten metal 2 in the molten metal supply chamber 6 springs out of the opening 15a of the molten metal guide path 15 into the molten metal chamber 16, and the molten metal 2 'that springs out is suppressed by the tip 14d of the projecting member 14c. The molten metal is supplied into the molten metal chamber 16 while being heated, and the molten metal surface S1 of the molten metal 2 in the molten metal chamber 16 rises without waving.

The supply of the molten metal may be carried out by using an electromagnetic pump or by sucking a casting mold.

Then, the molten metal surface S1 in the molten metal chamber 16 is supplied to the molten metal surface detecting sensor 23 for a time t4 as shown in FIGS.
, The molten metal surface S1 is detected by the molten metal surface detection sensor 23, and a molten metal surface detection signal is output from the molten metal surface detection sensor 23 and input to the arithmetic and control circuit 41.

Further, upon receiving the molten metal level detection signal, the arithmetic and control circuit 41 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, when the arithmetic control circuit 41 receives the level detection signal from the level detection sensor 23,
In 4, the ports 43 a and 43 b of the air introduction valve 43 are communicated, and the pressure reduction control valve 44 is operated, so that the mold chamber 2
Start pressure reduction of 2. At this time, the pressure is detected by the vacuum sensor 45, and a detection signal from the vacuum sensor 45 is input to the arithmetic and control circuit 41.

The pressure reducing force in the cavity 29 of the casting mold 25 is changed from 0 to −P6 (K
g / cm2) and then from time t5 to time t6
-P6 (Kg / cm2) to -P7 (Kg / cm2)
2) Increased to (-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 surface level S1 of the molten metal 2 'in the molten metal chamber 16 is about to drop.
The pressure in the upper space 6a of P
Is maintained so that the molten metal 2 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 maintained substantially constant.
When the filling of the molten metal 2 ′ into the cavity 29 is completed, the heat of the molten metal 2 ″ in the cavity 29 is transferred to the dies 26, 2.
After being absorbed by the sample 7, the heat is released and solidification has already started.

(Pushing water) By the start of the solidification, the molten metal 2 ″ filled in the cavity 29 contracts.
In order to stabilize the quality of the casting (product), the cavity 29
To push the hot water.

That is, the arithmetic and control circuit 41 determines that the degree of decompression (vacuum degree) in the mold chamber 22 is a predetermined value (before the molten metal 2 ′ in the molten metal chamber 16 falls below the lower end of the molten metal filling path 30 a). -P6) is detected at time t5 based on the detection signal from the vacuum sensor 45, and the time t5
, The pressure control valve 34 is operated to further pressurize and supply an inert gas from the gas supply source 35 or a gas such as compressor air to the upper space 6 a of the molten metal supply chamber 6 through the exhaust valve 33 and the pipe 32. The pressure in the space 6a is changed from P1 to P2 in the time from time t5 to time t6.
Up to On the other hand, the arithmetic 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 6 a of the molten metal supply chamber 6, thereby cutting off the communication between the inert gas supply source 38 and the exhaust valve 36. . Thereby, when the pressure in the molten metal holding furnace 1 increases, the pressure in the upper space 16a of the molten metal chamber 16 is increased, and the upper space 1
The pressure in 6a is increased to P3 in the time from time t5 to time t6. Moreover, since the communication between the inert gas supply source 38 and the exhaust valve 36 is shut off, the pressure P3 in the upper space 16a of the molten metal chamber 16 becomes
The pressure is equal to the pressure P2 applied to the upper space 6a of the molten metal supply chamber 6.

The pressure P2 (= P3) acts on the molten metal 2 'in the molten metal chamber 16 and the cavity 29 of the casting mold 25 through the plurality of molten metal filling paths 30a, thereby reducing the volume of the molten metal 2 "by cooling. The molten metal is replenished in response to the shrinkage, thereby giving a so-called hot-water effect.

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

(Decompression stop) The arithmetic control circuit 41
After detecting at time t6 that the detection 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 the air The ports 43a and 43c of the introduction valve 43 are communicated, 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 2 'into the inside is completed.

(V) Hot Water Draining and Returning When a predetermined time t9 elapses after the filling of the molten metal 2 ″ into the cavity 29 is completed, the molten metal 2 ″ in the cavity 29 is removed.
Is absorbed by the molds 26 and 27 and is radiated to be solidified, but the molten metal in the molten metal filling path 30a is in a non-solidified state.

At this time t9, the arithmetic control circuit 41
Pressurizes and supplies an inert gas from an inert gas gas supply source 38 to an upper space 16a of the melt chamber 16 by a pressure control valve 37 to increase the pressure of the upper space 16a of the melt chamber 16 from P3 to P4. 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 filling pipe 30 as shown in FIGS.

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 rising inside the molten metal filling pipe 30 and flows downward by its own weight. The molten gas is flowed down to the molten metal supply chamber 6 by the inert gas supplied therein, so that the molten metal is cut off.

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 is returned to the molten metal supply chamber 6. Along with this,
The pressure in the upper spaces 6a and 16a drops, and the pressure is made substantially "0" at time t12.

(Vi) Product take-out Then, the arithmetic and control circuit 41 controls the upper spaces 6a and 16a.
After the pressure in a becomes substantially “0” at time t12, the hydraulic circuit 31 is immediately operated and the cover 21 is raised by a hydraulic cylinder (not shown) so as to be separated upward from the peripheral wall member 20 at the same time. The mold 27 is lifted integrally with the lid 21, and the upper mold 27 is separated from the lower mold 26 as shown in FIG. 3 (6) and FIG. Thereafter, the 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 product receiver is taken out from under the upper mold 27, so that the casting 60
Is taken out.

[0065]

As described above, according to the first aspect of the present invention, there is provided a molten metal holding furnace, a molten metal chamber disposed above the molten metal holding furnace, and a lower end inserted into the molten metal of the molten metal holding furnace. A molten metal guide path for guiding the molten metal to the molten metal chamber, molten metal supply means for supplying the molten metal of the molten metal holding furnace to the molten metal chamber via the molten metal guide path, and a mold cavity disposed above the molten metal chamber A molten metal filling path having a lower end inserted into the molten metal chamber and guiding the molten metal in the molten metal chamber to the mold cavity;
In a casting apparatus including a molten metal supply means for supplying molten metal in the molten metal chamber to the mold cavity via the molten metal filling path, a projecting member projecting toward an opening to the molten metal chamber is provided inside the molten metal chamber. When the molten metal of the molten metal holding furnace is supplied to the molten metal chamber through the molten metal guiding path, the molten metal that flows into the molten metal chamber from the opening of the molten metal guiding path is suppressed at the tip of the projecting member, and The molten metal surface is not undulating, and the undulating molten metal surface rises in the molten metal chamber, and a required amount of molten metal can be supplied into the molten metal chamber by the detection of the molten metal surface detecting sensor.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a differential pressure casting apparatus according to an embodiment of 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 a differential pressure casting apparatus.

FIG. 3 is an explanatory view of a casting step.

FIG. 4 is an enlarged schematic diagram illustrating a state of a differential pressure casting apparatus main body at the start of a casting process.

FIG. 5 is an enlarged schematic diagram illustrating a state of a differential pressure casting apparatus main body when a mold is closed in a casting process.

FIG. 6 is an enlarged schematic diagram illustrating a state of a differential pressure casting apparatus main body when a molten metal level is detected in a casting process.

FIG. 7 is an enlarged schematic diagram illustrating a state of a differential pressure casting apparatus main body at the time of filling a molten metal in a casting process.

FIG. 8 is an enlarged schematic diagram illustrating a state of a differential pressure casting apparatus main body at the time of hot water removal in a casting process.

FIG. 9 is an enlarged schematic diagram illustrating a state of a differential pressure casting apparatus main body at the time of product removal in a casting process.

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

FIG. 11 is an explanatory view showing an example of a differential pressure casting device obtained by improving a conventional differential pressure casting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Molten holding furnace 2 ... Molten 14 ... Molten container 14c ... Protrusion member 15 ... Molten guide path 15b ... Opening 16 ... Molten chamber 23 ... Metal surface detection sensor 25 ... Casting mold 29 ... Mold cavity 30 ... Molten filling path 35 ... Molten metal supply means (gas supply source) 46 ... Molten metal supply means (vacuum pump)

Claims (1)

[Claims] A molten metal holding furnace; a molten metal chamber disposed above the molten metal holding furnace; a molten metal guide path having a lower end inserted into the molten metal of the molten metal holding furnace and guiding the molten metal to the molten metal chamber; A molten metal supply means for supplying the molten metal of the molten metal holding furnace to the molten metal chamber via the molten metal guide path, a mold cavity disposed above the molten metal chamber, and a lower end portion inserted into the molten metal chamber and A casting apparatus comprising: a molten metal filling path for guiding a molten metal in a molten metal chamber to the mold cavity; and a molten metal supply means for supplying the molten metal in the molten metal chamber to the mold cavity through the molten metal filling path. A differential pressure casting apparatus, wherein a projecting member projecting toward an opening to the chamber is provided in the molten metal chamber.