JP4916672B2 - Die casting apparatus and vacuum casting method - Google Patents

Description

The present invention relates to a die casting apparatus (die casting machine) and a vacuum casting method for the die casting apparatus.
In particular, the present invention relates to a die casting apparatus to which an oxygen substitution die casting method is applied, and a vacuum casting method in the die casting apparatus.

One of the causes of reduced reliability due to variations in the quality of die-cast products, such as aluminum die-cast products, is the inclusion of gas or the like in the die-cast product. That is, molten metal that is injected under high-speed and high-pressure conditions and filled (poured) into the injection sleeve (molten metal), for example, molten aluminum, becomes turbulent in the cavity of the injection sleeve and the mold, and air, water vapor, etc. The gas is entrained and filled in the cavity of the mold, and these gases become bubbles to generate nests in the die-cast product, thereby deteriorating the quality of the die-cast product.
In order to overcome the above problems, the gas to the die-cast product in the cavity is cast by casting using a die-casting machine by a vacuum die-casting method in which the inside of the mold cavity sealed against the outside air is decompressed to a vacuum state. A technique is known that suppresses the variation in the quality of die-cast products due to the inclusion of gas in the die-cast products (for example, see Patent Document 1).

In a die casting machine using such a vacuum die casting method, it is necessary to reduce the pressure in the mold cavity to a lower pressure in a short time. The reason will be described below.
The pressure in the cavity is reduced by, for example, connecting a pressure reducing tank that has been reduced to a low pressure in advance to a sealed cavity, and the pressure is rapidly reduced in the range where the pressure difference between the pressure reducing tank and the cavity is large. Since the flow rate of the gas exhausted from the cavity decreases as the difference becomes smaller, it takes a very long time to reach the desired pressure. In the die casting machine, it is necessary to reduce the pressure inside the cavity while supplying molten metal (molten metal) to the sleeve. If the time required for decompression increases, the molten metal supplied to the sleeve before filling the cavity There is a possibility of cooling and solidifying inside.

  Further, even if the pressure inside the mold cavity can be reduced from an atmospheric pressure of 1.01325 × 105 Pa to a very low pressure of, for example, about 5.33289 × 103 Pa by the vacuum die casting method, Gas such as water vapor remains. Even if such a die-cast product containing residual gas does not cause defects in the die-cast product by heat treatment such as T6 treatment, it becomes small bubbles under high-temperature conditions during welding and causes defects in the welded part of the die-cast product.

In order to prevent the occurrence of defects in the die-cast product due to the residual gas in the cavity, the gas in the mold cavity is replaced with oxygen gas, the molten metal and oxygen gas are reacted (oxidized), and the cast die casting A so-called oxygen substitution die casting method for preventing bubbles from occurring in a product is known (see, for example, Patent Documents 2 and 3).
For example, when the molten metal is aluminum, when aluminum reacts with oxygen gas, fine particles of aluminum dioxide (alumina) Al2 O3 are produced.
US Pat. No. 2,785,448 JP-A-10-113757 JP-A-9-1306

  In the oxygen substitution die casting method, if the amount of substituted oxygen gas is large, a large amount of molten metal oxide is generated in the die casting product, and there is a problem that the quality of the die casting product is deteriorated. For example, in an aluminum die-cast product containing a large amount of aluminum dioxide (Al2 O3), the properties or quality of the die-cast product such as malleability deteriorates. In addition, if the amount of substituted oxygen gas is large, oxygen gas that does not react with the molten metal remains, and bubbles due to oxygen are generated in the die cast product.

  On the other hand, even if the pressure is reduced while the mold is sealed, it is difficult to completely eliminate the air (outside air) outside the mold cavity and / or the sleeve that leaks from the seal portion and enters the mold. It is not easy to completely replace the gas in the formed cavity with oxygen gas. Even if a gas other than oxygen gas remains in the cavity, bubbles are generated in the die-cast product.

  The object of the present invention is to prevent moisture and nitrogen gas, which cause internal defects in the casting, from remaining in the cavity of the mold and the gas intrusion path to the cavity. An object of the present invention is to provide a die casting apparatus (die casting machine) and a reduced pressure casting method that can surely replace with gas and can reduce the time required to reduce the pressure in the cavity to a predetermined pressure.

According to the present invention, an internal stationary mold, an external stationary mold surrounding the internal stationary mold, and a stationary mold flow formed as a gap between the internal stationary mold and the external stationary mold. A fixed mold having a path, an internal moving mold that forms a cavity in which a molten metal is accommodated together with the internal fixed mold, an external moving mold that surrounds the internal moving mold, and the internal moving mold A movable mold having a movable mold flow path formed as a gap between the first movable pressure mold and the external movable mold, a first decompression tank, and a first opening / closing valve connected to the first decompression tank. The oxygen supply means, the second pressure reduction tank, and the second pressure reduction tank having the first pressure reduction means, the oxygen gas supply device, and a second opening / closing valve connected to the oxygen gas supply device. A third on-off valve, the third on-off valve and the fixed A second pressure reducing means having an exhaust pipe disposed between the mold flow path and the fixed mold flow path; and the first pressure reducing means or the oxygen gas supply means provided in the moving mold. An inner cylinder having a first open / close valve means for bringing the cavity into communication or non-communication, an opening communicating with the cavity, and a supply port for pouring the molten metal on a side facing the opening An injection sleeve, a plunger tip fitted into the inner cylinder of the injection sleeve, and a plunger rod connected to the plunger tip and moving the plunger tip, and the injection from the supply port Injection plunger means for injecting molten metal poured into the sleeve toward the cavity through the opening, a position sensor for detecting the position of the plunger rod, and a front Comprising an injection cylinder means for driving the injection plunger means, and control means, and
The control means includes
When the start of pouring of the molten metal into the injection sleeve is detected by a detection signal from a temperature sensor disposed near the supply port of the injection sleeve or an operator's instruction, the second on-off valve and the The first on-off valve means is opened to fill the cavity and the injection sleeve with oxygen gas and fill the oxygen gas while oxidizing the surface of the molten metal poured into the injection sleeve. gas Ru is exhausting gas other than oxygen gas together with oxygen gas in the injection sleeve and the cavity are released from the supply port, performing a first process,
When pouring of the molten metal into the pre-Symbol injection sleeve is completed, and the distal end of the plunger rod of the injection plunger means drives the injection cylinder unit is moved at a first speed toward the opening , Starting the injection of the molten metal poured into the injection sleeve into the cavity, performing a second process,
The second process by the time it is detected that has passed a predetermined time after the start of the movement in the first speed of the plunger rod, the second on-off valve in the closed state to terminate the filling of the oxygen gas, the Performing a third process for closing the first on-off valve means ;
Based on the amount of movement of the plunger rod obtained from the detection value of the position sensor, the plunger tip until the plunger tip by the second process exceeds the supply port of the injection sleeve and closes the supply port. the Before moving at the first speed, it performs the fourth process,
After the supply port by the fourth processing becomes closed state, the first within the first pressure reducing means off valve and the first on-off valve means within said cavity by said first vacuum tank by the opened and starts to vacuum the injection sleeve, performs a fifth processing, after the fifth of the first on-off valve by the process and the first on-off valve means is in the open state, the second pressure reducing Opening the third on-off valve of the means, and starting to depressurize the fixed mold flow path and the fixed mold flow path connected to the exhaust pipe by the second pressure reducing tank , Process
In the sixth process, the decompression of the cavity and the injection sleeve is continued for a predetermined time by the first decompression tank, and then a seventh process of closing the first on-off valve means is performed.
The molten metal poured into the injection sleeve by driving the injection cylinder means and moving the tip of the plunger rod of the injection plunger means toward the opening at a second speed higher than the first speed. Is injected into the cavity at a high speed, and an eighth process is performed.
After a predetermined time has elapsed after the start of the movement of the plunger rod at the second speed by the eighth process , the first open / close valve and the third open / close valve are closed to operate the first decompression tank and Performing the ninth process of ending the pressure reducing operation by the second pressure reducing tank;
A die casting apparatus is provided.

Preferably, the internal moving mold is formed with a first through hole facing the cavity, and the first opening / closing valve means provided in the moving mold is provided between the through hole and the cavity. And a driving means for moving the valve body. The internal movement mold and the external movement mold include the first through hole and the first opening / closing. A second through hole connected to a pipe connected to the valve and the second on-off valve is formed .

Further, according to the present invention, an internal fixed mold, an external fixed mold surrounding the internal fixed mold, and a fixed mold formed as a gap between the internal fixed mold and the external fixed mold A stationary mold having a flow path, an internal movement mold that forms a cavity in which the molten metal is accommodated together with the internal stationary mold, an external movement mold that surrounds the internal movement mold, and the internal movement mold A moving mold having a moving mold channel formed as a gap between the mold and the external moving mold, a first pressure reducing tank, and a first opening / closing valve connected to the first pressure reducing tank. An oxygen supply means having a first pressure reducing means, an oxygen gas supply device, and a second opening / closing valve connected to the oxygen gas supply device; a second pressure reduction tank; and the second pressure reduction tank. A third on-off valve, the third on-off valve and the A second pressure reducing means having an exhaust pipe disposed between the fixed mold flow path and the fixed mold flow path; and the first pressure reducing means or the oxygen gas supply provided in the moving mold. A first opening / closing valve means for bringing the means and the cavity into communication or non-communication, an opening communicating with the cavity, and a supply port for pouring the molten metal on the side facing the opening. A cylindrical injection sleeve; a plunger tip that is movably inserted in the inner cylinder of the injection sleeve; and a plunger rod that is connected to the plunger tip and moves the plunger tip; Injection plunger means for injecting the molten metal poured into the injection sleeve toward the cavity via the opening, and a position sensor for detecting the position of the plunger rod; A control method of a die casting apparatus comprising, an injection cylinder means for driving the injection plunger means,
When the start of pouring of the molten metal into the injection sleeve is detected by a detection signal from a temperature sensor disposed near the supply port of the injection sleeve or an operator's instruction, the second on-off valve and the The first on-off valve means is opened to fill the cavity and the injection sleeve with oxygen gas and fill the oxygen gas while oxidizing the surface of the molten metal poured into the injection sleeve. gas Ru is exhausting gas other than oxygen gas together with oxygen gas in the injection sleeve and the cavity are released from the supply port, performing a first process,
When pouring of the molten metal into the pre-Symbol injection sleeve is completed, and the distal end of the plunger rod of the injection plunger means drives the injection cylinder unit is moved at a first speed toward the opening , Starting the injection of the molten metal poured into the injection sleeve into the cavity, performing a second process,
The second process by the time it is detected that has passed a predetermined time after the start of the movement in the first speed of the plunger rod, the second on-off valve in the closed state to terminate the filling of the oxygen gas, the Performing a third process for closing the first on-off valve means ;
Based on the amount of movement of the plunger rod obtained from the detection value of the position sensor, the plunger tip until the plunger tip by the second process exceeds the supply port of the injection sleeve and closes the supply port. the Before moving at the first speed, it performs the fourth process,
After the supply port by the fourth processing becomes closed state, the first within the first pressure reducing means off valve and the first on-off valve means within said cavity by said first vacuum tank by the opened And starting a decompression of the inside of the injection sleeve, performing a fifth process,
After the first on-off valve and the first on-off valve means is in the open state by the fifth processing, and the third on-off valve of the second pressure reducing means in the open state, is connected to the exhaust pipe Starting a pressure reduction of the fixed mold flow path and the fixed mold flow path by the second pressure reducing tank , and performing a sixth process,
In the sixth process, the decompression of the cavity and the injection sleeve is continued for a predetermined time by the first decompression tank, and then a seventh process of closing the first on-off valve means is performed.
The molten metal poured into the injection sleeve by driving the injection cylinder means and moving the tip of the plunger rod of the injection plunger means toward the opening at a second speed higher than the first speed. Is injected into the cavity at a high speed, and an eighth process is performed.
After a predetermined time has elapsed after the start of the movement of the plunger rod at the second speed by the eighth process , the first open / close valve and the third open / close valve are closed to operate the first decompression tank and Performing the ninth process of ending the pressure reducing operation by the second pressure reducing tank;
A method for controlling a die casting apparatus is provided.

According to the present invention, in addition to the vacuum exhaust in the cavity in the mold by the pressure reducing operation by the first pressure reducing means, the sleeve that is harmful to the die casting manufacturing in the cavity, the injection sleeve, etc. by the pressure reducing operation by the second pressure reducing means. And / or gases such as outside air from outside the cavity are excluded. As a result, a high quality die cast product can be manufactured.
Further, according to the present invention, a high-quality die-cast product can be manufactured by an appropriate oxygen supply by the reduced pressure oxygen substitution die casting method.
Furthermore, according to the present invention, since a series of operations can be performed continuously in a short time, a large temperature drop does not occur in the molten metal poured into the injection sleeve, and a high-quality die-cast product can be manufactured.
According to the present invention, there is an effect on cycle extension for manufacturing a die-cast product.

  In the present invention, after the inside of the closed space used for the die casting process of the die casting apparatus including the cavity in the mold is filled with oxygen gas, the first mold, for example, the fixed mold flow of the fixed mold is used by the second decompression means. In order to evacuate by the second decompression from the path, the second mold, for example, the moving mold flow path of the moving mold and the flow path formed between the groove of the plunger tip and the inner peripheral surface of the sleeve, It is possible to surely replace every corner of the closed space with oxygen gas, and it is also possible to reliably replace the gas intrusion passage with oxygen gas.

  Furthermore, in the present invention, even after the inside of the closed space used for the die casting process of the die casting apparatus including the cavity is reliably replaced with oxygen gas, by continuing the exhaust in the closed space by the second decompression means, Gas that is harmful to die casting such as outside air does not enter inside the sleeve.

  Furthermore, in the present invention, since the second decompression means and the first decompression means operate in parallel, the time required for decompression can be shortened, and oxygen gas filled in the oxygen replacement method and remaining in the cavity can be reduced. Can be reduced.

  Preferred embodiments of a die casting apparatus (die casting machine) and a reduced pressure casting method of the present invention will be described with reference to the accompanying drawings.

Configuration of Die Casting Device The configuration of the die casting device according to one embodiment of the present invention will be described.
FIG. 1 is a sectional view showing a structure around a mold of a die casting apparatus according to an embodiment of the present invention.
The die casting apparatus 1 of this embodiment includes a fixed mold 2, a moving mold 3 that moves relative to the fixed mold 2, an injection apparatus 10, a controller 30, a main decompression tank TA, an auxiliary decompression tank TB, a shutoff valve ( Check valve) 60 and an oxygen gas supply device 80.
The controller 30 is a part that performs various controls of the die casting apparatus 1 that will be described in detail below, and is realized using arithmetic processing means, for example, a computer.

The injection device 10 includes a hydraulic cylinder 11, a piston rod 12, a coupling 13, an injection plunger 17, and an injection sleeve 16.
The hydraulic cylinder 11 is driven by a predetermined pressure of oil (operating oil), and moves the piston rod 12 to the left and right in the state shown in FIG.
The injection plunger 17 has a plunger rod 14 and a plunger tip 15.
The coupling 13 connects a piston rod 12 and a plunger rod 14 connected to the hydraulic cylinder 11.
The injection sleeve 16 is formed of a cylindrical heat-resistant / pressure-resistant member, and the injection sleeve 16 is provided with a supply port 16h for pouring molten metal (molten metal) into the inner cylinder of the injection sleeve 16 in which the plunger tip 15 moves. It has been. The opposite side of the supply port 16 h of the injection sleeve 16 is fixed to the fixed mold 2 and communicates with a cavity C defined by the fixed mold 2 and the movable mold 3.
A plunger tip 15 is connected to the tip of the plunger rod 14, and the plunger tip 15 is movably fitted in the inner cylinder of the injection sleeve 16.
A space between the outer peripheral surface of the plunger tip 15 and the inner peripheral surface of the injection sleeve 16 is sealed in an airtight state against the outside air. As the plunger tip 15 moves forward from the supply port 16h toward the cavity C, the injection sleeve 16 is blocked from the outside.

FIG. 2 is an enlarged view of the fixed mold 2, the movable mold 3, and portions around them in the die casting apparatus 1 illustrated in FIG. 1.
The fixed mold 2 and the movable mold 3 illustrated in FIGS. 1 and 2 are in a clamped state. For example, the fixed mold 2 is fixed to a fixed die plate (dieplate) of a mold clamping machine (not shown), and the movable mold 3 is fixed to a movable die plate of a mold clamping apparatus (not shown). . For example, the fixed die 2 and the movable die 3 are clamped by pressing the movable die plate toward the fixed die plate with a predetermined force by a toggle mechanism or the like.
When the fixed mold 2 and the moving mold 3 are combined, a cavity C for filling a molten metal and manufacturing a die-cast product is defined.
The fixed mold 2 includes an internal fixed mold 2a that defines the cavity C in combination with the internal movable mold 3a of the movable mold 3, and an external fixed mold 2b that surrounds the internal fixed mold 2a. A fixed mold channel 2c is defined in a gap (clearance) at the corner of the joint surface between the internal fixed mold 2a and the external fixed mold 2b. The fixed mold 2 has a dividing surface 2f having an annular cross section in contact with the moving mold 3 along the outer periphery. Further, on the side of the inner fixed mold 2a facing the surface in contact with the outer fixed mold 2b, a cavity surface 2d that defines the cavity C and a valve movement space Sp that allows the valve element 62 of the shutoff valve 60 to move are provided. And a valve movement space surface 2e to be defined.
When viewed from the direction A, the cross section of the fixed mold 2 is, for example, substantially circular, and the fixed mold flow path 2c is illustrated by a broken line between the internal fixed mold 2a and the external fixed mold 2b. The corner is annular.
An injection sleeve 16 communicating with the cavity C is fixed to the fixed mold 2. The space between the fixed mold 2 and the injection sleeve 16 is sealed against the outside.

The moving mold 3 includes an internal moving mold 3a that defines the cavity C in combination with the internal fixed mold 2a of the fixed mold 2, and an external moving mold 3b that surrounds the internal moving mold 2a. A moving mold flow path 3c is defined in the gap at the corner of the joint surface between the internal moving mold 2a and the external moving mold 3b. The moving mold 3 has a split surface 3f having an annular cross section in contact with the fixed mold 2 along the outer periphery and facing the cavity surface 2d of the fixed mold 2.
When the moving mold 3 is viewed from the direction A, for example, the cross section has a substantially circular shape, and the moving mold flow path 3c is illustrated by a broken line between the inner moving mold 3a and the outer moving mold 3b. Located in the corner, it is annular.

A cavity C for casting a cast product is formed (defined) between the cavity surface 2 d of the internal fixed mold 2 a of the fixed mold 2 and the dividing surface 3 f of the movable mold 3.
Between the annular dividing surface 2f on the outer periphery of the fixed mold 2 and the outer peripheral annular portion of the dividing surface 3f of the moving mold 3 facing the dividing surface 2f, that is, the external fixed mold 2b and the outside A sealing member SL that seals the space between the split surface 2f and the split surface 3f in an airtight state so that outside air does not enter the cavity C is provided on the joint surface of the split surface with the moving mold 3b. .
The seal member SL is, for example, an annular O-ring formed of silicon rubber as viewed from the direction A.

The moving mold 3 is provided with a shutoff valve 60.
The shut-off valve 60 includes an electromagnetic actuator 61 whose operation is controlled by a control signal 30SC from the controller 30, a valve body 62 facing the valve movement space surface 2e of the internal fixed mold 2a of the fixed mold 2, and a valve shaft 63. And a valve seat member 64.
The valve seat member 64 is a cylindrical member having a first through hole 64a into which the valve shaft 63 is inserted and a second through hole 64b that allows the valve shaft 63 to move in a loosely fitted state. Embedded in the inner moving mold 3a and the outer moving mold 3b. Between the valve seat member 64 and the external moving mold 3b of the moving mold 3, a second seal member SL2, for example, an O-ring made of silicon rubber is provided in a direction orthogonal to the axial direction.
The valve seat member 64 is disposed at a position where the valve seat surface 64 f coincides with the dividing surface 3 f of the movable mold 3.
An exhaust passage 52 that communicates with the second through hole 64 b of the valve seat member 64 is formed in the movable mold 3 and the valve seat member 64. An exhaust pipe 51 is connected to the exhaust path 52, and a main decompression tank TA is connected to the exhaust pipe 51 via a first opening / closing valve MV that is controlled according to a control signal 30 SA from the controller 30.

The valve shaft 63 is fitted in the first through hole 64a of the valve seat member 64, and is moved in the linear motion direction L shown in FIG. 2 by the electromagnetic actuator 61 that operates in response to the control signal 30SC from the controller 30. .
Between the valve movement space surface 2e of the inner fixed mold 2a of the fixed mold 2 and the dividing surface 3f of the outer movement mold 3b of the movable mold 3, a valve body 62 provided at the tip of the valve shaft 63 is provided. A valve movement space Sp in which can be moved is formed.
The valve movement space Sp communicates with the cavity C. The cavity C communicates with the exhaust pipe 51 through the valve movement space Sp, the second through hole 64 b of the valve seat member 64, and the exhaust passage 52 when the valve body 62 is separated from the valve seat member 64.

The valve body 62 provided at the tip of the valve shaft 63 is moved from the valve movement space surface 2e of the internal fixed mold 2a to the valve seat member 64 side in the valve movement space Sp, so that the valve seat member 64 The second through hole 64b is closed by contacting the valve seat surface 64f. As a result, the exhaust path connecting the cavity C and the exhaust path 52 and the exhaust pipe 51 is closed. On the contrary, the valve element 62 in contact with the valve seat surface 64f of the valve seat member 64 is moved to the valve moving space surface 2e side of the internal fixed mold 2a of the fixed mold 2, thereby causing the cavity C and the exhaust pipe to be moved. 51 is opened.
The electromagnetic actuator 61 that moves (opens / closes) the valve body 62 described above is driven in response to a control command 30SC from the controller 30.

A plurality of push pins 65 are provided so as to be movable with respect to the movable mold 3 through the internal movable mold 3 a and the external movable mold 3 b.
In the final step of the operation of the die casting apparatus 1, the die cast product cast in the cavity C can be taken out by extruding the extrusion pin 65 toward the cavity C. The push pin 65 is fitted into a through-hole formed in the movable mold 3, and an airtight state is provided between the push pin 65 and the movable mold 3 so that outside air does not enter the cavity C from the outside. Is sealed.

As illustrated in FIGS. 1 and 2, a position detection sensor 35 is provided to detect the movement position and movement speed of the plunger rod 14, in other words, to detect the movement position and movement speed of the plunger tip 15. ing. Therefore, for example, magnetic poles are formed on the outer periphery of the plunger rod 14 at a constant pitch along the axial direction. The position detection sensor 35 detects, for example, a change in the magnetic pole of the moving plunger rod 14, converts the change in the magnetic pole into a pulse signal, and outputs the pulse signal. The position detection sensor 35 outputs a detection signal 35 s to the controller 30.
Based on the detection signal 35 of the position detection sensor 35, the controller 30 calculates the moving speed from the position of the injection plunger 17 (or the plunger tip 15 in the injection sleeve 16) and the temporal change (time differentiation) of the position.
From the reading of the position detection sensor 35, the controller 30 identifies a first speed described later, for example, an injection position at a low speed, a second speed, for example, an injection position at a high speed, or a low-speed injection start timing, or a high-speed injection. You can identify the timing.

The main decompression tank TA is connected to the exhaust pipe 51 via a first opening / closing valve MV. The main decompression tank TA passes through the exhaust pipe 51, the exhaust passage 52, the second through hole 64b, and the valve movement space Sp in the closed space including the cavity C formed between the moving mold 3 and the fixed mold 2. Depressurize and exhaust.
The first opening / closing valve MV is opened / closed by a control command 30SA from the controller 30.
A vacuum pump 50A is connected to the main decompression tank TA, and the inside of the main decompression tank TA is decompressed to a predetermined pressure by the vacuum pump 50A. For example, when the vacuum pump 50A is activated by the controller 30, the vacuum pump 50A automatically turns on and off, for example, so that a predetermined vacuum state is maintained in the main decompression tank TA. The main decompression tank TA is decompressed to a predetermined pressure (substantially vacuum state) by the vacuum pump 50A before the operation of the die casting apparatus 1 described below.

The oxygen gas supply device 80 is connected to a connection path 53 between the exhaust pipe 51 and the main decompression tank TA via a second opening / closing valve GV.
The second opening / closing valve GV is opened / closed by a control command 30SD from the controller 30. When the second on-off valve GV is opened with the first on-off valve MV closed, the oxygen gas O2 from the oxygen gas supply device 80 passes through the exhaust pipe 51, the exhaust passage 52, the second through-hole 64b, and the valve movement space Sp to form the cavity C. Supplied in.

The valve movement space Sp, the cavity C, and the space in the injection sleeve 16 communicate with each other, and these constitute a closed space.
The joint surface between the split surface 2f of the external fixed mold 2b of the fixed mold 2 and the split surface 3f of the external movable mold 3b of the movable mold 3 is sealed against the outside air by the seal member SL, and the plunger tip 15 is sealed. In the state where the inside of the injection sleeve 16 is moved to the left side beyond the supply port 16h to close the supply port 16h of the sleeve 16 and the shut-off valve 60 is closed, the valve movement space Sp, cavity C, injection sleeve 16 are closed. The closed space formed inside is sealed from the outside.
However, the space between the split surfaces 2f and 3f, between the valve seat member 64 and the moving mold 3, between the push pin 65 and the moving mold 3, between the plunger tip 15 and the sleeve 16, etc. is completely free from outside air. The outside air that has passed through these seals enters a closed space composed of the valve movement space Sp, the cavity C, and the inside of the injection sleeve 16, and when the inside of the closed space is made high vacuum. May be a hindrance.

Further, in the fixed mold 2, a clearance (clearance) between the internal fixed mold 2a and the external fixed mold 2b, and in the movable mold 3, a gap between the internal movable mold 3a and the external movable mold 3b, the dividing surface 2f. , 3f, outside air may enter between the valve seat member 64 and the moving mold 3 and between the push pin 65 and the moving mold 3. That is, these portions serve as an intrusion path through which outside air enters the closed space formed by the valve movement space Sp, the cavity C, and the internal space of the injection sleeve 16. Similarly, the passage between the plunger tip 15 and the sleeve 16 is an outside air entry path.
Furthermore, unnecessary gas for vacuum casting such as air and water vapor tends to remain in these intrusion paths.
Therefore, in the present embodiment, in the fixed mold 2, a fixed mold flow path 2c formed with a slight gap is formed between the internal fixed mold 2a and the external fixed mold 2b, and the fixed mold flow A first auxiliary exhaust pipe 90 is connected to the path 2c to allow exhaust.
Similarly, in the moving mold 3, a moving mold flow path 3c formed with a slight gap is formed between the internal moving mold 3a and the external moving mold 3b. 2 Auxiliary exhaust pipe 91 is connected to enable exhaust.
The auxiliary exhaust pipes 90 and 91 are connected to the auxiliary pressure reducing tank TB via the third opening / closing valve SV.
The third open / close valve SV is opened / closed according to a control signal 30SB of the controller 30.

A groove 15 h is formed up to almost half of the outer peripheral surface of the plunger tip 15 fitted on the inner peripheral surface of the injection sleeve 16 on the cavity C side. The groove 15h communicates with an inner hole from the outer peripheral surface of the half of the plunger tip 15, and the hole further communicates with a conduit formed in the plunger rod 14. This conduit is connected to the auxiliary decompression tank TB. The third open / close valve SV is connected.
The groove 15 h serves as an auxiliary exhaust flow path for the gas that has entered the internal space of the injection sleeve 16, the cavity C, and the valve movement space Sp by fitting the outer periphery of the plunger tip 15 to the inner periphery of the sleeve 16.

The auxiliary decompression tank TB includes a fixed mold flow path 2c between the internal fixed mold 2a of the fixed mold 2 and the external fixed mold 2b, and an internal movable mold 3a and an external movable mold of the movable mold 3. 3b and the flow path formed between the groove 15h formed in the plunger tip 15 and the plunger rod 14 and the inner peripheral surface of the sleeve 16 through the moving mold flow path 3c between the injection sleeve 16 and the movable sleeve 3b. The gas in the closed space constituted by the internal space, the cavity C, and the valve movement space Sp is decompressed and exhausted.
The third open / close valve SV is opened / closed by a control command 30SB from the controller 50.
A vacuum pump 50B is connected to the auxiliary pressure reducing tank TB, and the pressure in the auxiliary pressure reducing tank TB is reduced to a predetermined pressure by the vacuum pump 50B. For example, when the vacuum pump 50B is operated by the controller 30, the vacuum pump 50B automatically turns on and off, for example, in order to maintain a predetermined reduced pressure state, for example, preferably a substantially vacuum state, in the auxiliary pressure reducing tank TB. . As described above, it is assumed that the auxiliary decompression tank TB is decompressed to a predetermined pressure (substantially vacuum state) by the vacuum pump 50B before the operation of the die casting apparatus 1.

Preferably, the first open valve OV1 is provided in the connection path 53 between the exhaust pipe 51 and the first opening / closing valve MV, and the second open valve OV2 is connected to the first and second auxiliary exhaust pipes 90, 91 and the third opening / closing. It is provided in a pipeline between the valve SV. These open valves OV1 and OV2 are on-off valves for bringing the inside of the mold into an atmospheric pressure state, and are closed during normal operation. When the first open valve OV1 and the second open valve OV2 are opened after the filling of the molten metal into the cavity C, the inside of the mold becomes an atmospheric pressure state, so that the pressure difference can be reduced and the mold can be opened. It becomes easy.
In order to further enhance the above-described effect of the first open valve OV1, it is desirable to open the shut-off valve 60 together with the opening of the first open valve OV1.
The control operation of the first open valve OV1, the second open valve OV2, and the shutoff valve 60 can be preferably performed by the controller 30.

Hereinafter, the correspondence between the above-described components and the terms of the present invention will be described.
The stationary mold 2 corresponds to the first mold of the present invention, and the moving mold 3 corresponds to the second mold of the present invention. The oxygen gas supply device 80 and the second opening / closing valve GV correspond to the oxygen gas supply means of the present invention.
The main decompression tank TA corresponds to the first decompression tank of the present invention, and the main decompression tank TA and the first opening / closing valve MV correspond to the first decompression means of the present invention.
A shut-off valve 60 mounted on the movable mold 3 corresponds to the first on-off valve means of the present invention.
The injection sleeve 16 having the supply port 16h corresponds to the injection sleeve of the present invention.
The injection plunger 17 composed of the plunger rod 14 and the plunger tip 15 corresponds to the injection plunger means of the present invention.
The hydraulic cylinder 11 and the piston rod 12 correspond to the injection cylinder means of the present invention.
The auxiliary decompression tank TB corresponds to the second decompression tank of the present invention, and the third open / close valve SV, the exhaust pipe 90, the exhaust pipe 91, the groove 15h, the pipe line in the plunger rod 14 and the like serve as the second decompression means of the present invention. Correspond.
The controller 30 corresponds to the control means of the present invention.

Operation Method of Die Casting Device, Vacuum Casting Method With reference to FIGS. 3 to 12, the operation method of the die casting device 1 and the vacuum casting method will be described.
FIG. 3 is a flowchart illustrating the operation mode of the die casting apparatus 1 in time series.
4 to 12 are diagrams illustrating the operation state of the main part of the die casting apparatus 1 in each process illustrated in FIG. 3.
The operation of the die casting apparatus 1 described below corresponds to a part of the vacuum casting method according to the embodiment of the present invention.
In the present embodiment, the controller 30 performs the following main control operations that can be automatically controlled by the die casting apparatus 1.

FIG. 3 shows the overall operation of the die casting apparatus 1, the operating state of the shut-off valve 60, the operating state of the oxygen gas supply device 80 and the second opening / closing valve GV indicating the operating state of the oxygen gas supply system, and the operating state of the main decompression system. The operation states of the main decompression tank TA and the first on-off valve MV shown, and the operation states of the auxiliary decompression tank TB and the third on-off valve SV showing the operation state of the auxiliary decompression system are illustrated in time series.
In addition, although the time t0 to the time t16 in FIG. 3 are illustrated at equal intervals for convenience of illustration, they are not always equal intervals. Similarly, the length of the time intervals T1 to T4 is not limited to the illustrated scale.

Time t0, initial state, FIG.
FIG. 2 shows an initial state of the die casting apparatus 1 at the time point t0.
In the initial state at time t0, the controller 30 is stopped. In the initial state of the die casting apparatus 1, the first on-off valve MV, the second on-off valve GV, and the third on-off valve SV are in a “closed” state. The first open valve OV1 and the second open valve OV2 are also closed. The first and second vacuum pumps 50A and 50B are also stopped.
In this initial state, oxygen is not supplied from the oxygen gas supply device 80 to the cavity C, there is no pressure reducing operation in the cavity C by the main pressure reducing tank TA, and there is no pressure reducing operation in the cavity C by the auxiliary pressure reducing tank TB. In this initial state, it is exposed to the internal space of the injection sleeve 16 and the outside air (atmosphere) of the cavity C communicating with the injection sleeve 16.
The shutoff valve 60 is also de-energized. That is, the valve element 62 of the shutoff valve 60 is seated on the valve seat member 64, and the shutoff valve 60 is closed.
The plunger tip 15 is located on the right side of the supply port 16h of the injection sleeve 16, and the supply port 16h is open.

Time t1: Mold clamping operation (FIG. 3, S1-1), FIG.
At the time point t1, as shown in FIG. 2, the fixed mold 2 and the movable mold 3 are clamped using, for example, a mold clamping device (not shown). Thereby, a cavity C in which the molten metal ML is filled between the fixed mold 2 and the movable mold 3 is defined.
Since the supply port 16h of the sleeve 16 is open, the molten metal ML can be poured from the supply port 16h.

Time t2: At the preparation time t2 of the main pressure reduction system and the auxiliary pressure reduction system , the controller 30 operates the first vacuum pump 50A.
Accordingly, the first vacuum pump 50A brings the inside of the main decompression tank TA of the main decompression system to a state close to a vacuum state (substantially vacuum state). Of course, a vacuum state is preferable.
Thereafter, the first vacuum pump 50A is preferably automatically turned on / off so as to maintain the inside of the main decompression tank TA in a predetermined vacuum state until the operation is stopped by the controller 30. Similarly, the controller 30 operates the second vacuum pump 50B at the time point t2. Thus, the second vacuum pump 50B brings the auxiliary pressure reducing tank TB of the auxiliary pressure reducing system into a state close to a vacuum state. Thereafter, the second vacuum pump 50B is preferably automatically turned on / off so as to maintain the inside of the auxiliary decompression tank TB in a predetermined vacuum state until the operation is stopped by the controller 30.
The operation of the first vacuum pump 50A is continued until the start of pouring at time t3. Similarly, the operation of the second vacuum pump 50B is also continued until the start of pouring at time t3. As a result, the main decompression tank TA is brought into a state sufficiently close to a vacuum state during a period from time t2 to time t3. Similarly, the auxiliary decompression tank TB is sufficiently close to the vacuum state for the period from the time point t2 to the time point t3.
At this time t2, the first on-off valve MV and the second on-off valve GV are both closed, and the cavity C is not decompressed yet.
Thus, the controller 30 operates the first vacuum pump 50A and the second vacuum pump 50B only during a period necessary for preparation for the pressure reducing operation.
The starting and stopping of the first vacuum pump 50A and the second vacuum pump 50B can be performed manually by the operator of the die casting apparatus 1 in addition to the controller 30 described above. In the present embodiment, a case where the controller 30 drives the first vacuum pump 50A and the second vacuum pump 50B will be described.

Time point t3: Start of pouring (S1-2), FIG.
At time t3, pouring of molten metal ML into the injection sleeve 16 from the supply port 16h of the injection sleeve 16 is started.

Time t4: oxygen supply start (S2-1), FIG.
When the controller 30 detects the start of the pouring operation of the molten metal ML from the supply port 16h into the injection sleeve 16 at time t4, the controller 30 energizes the shut-off valve 60 in the closed state to the open state (energise). The signal 30SC is output to the electromagnetic actuator 61. Further, the controller 30 outputs a control signal 30SD for energizing the closed second open / close valve GV to the open state.
Thereby, as illustrated in FIG. 4, the valve body 62 of the shut-off valve 60 moves from the seating state of the valve seat member 64 toward the valve movement space Sp, and the shut-off valve 60 is opened. As a result, the second through hole 64b and the valve movement space Sp are in communication with each other. Therefore, oxygen gas is filled from the oxygen gas supply device 80 through the second opening / closing valve GV and the exhaust passage 52 through the second through hole 64b into the internal space of the valve movement space Sp, the cavity C, and the injection sleeve 16. .

By filling oxygen gas into the cavity C and the injection sleeve 16, the surface of the molten metal ML poured into the injection sleeve 16 is oxidized, and the oxygen substitution die casting method starts. That is, the oxygen gas O2 supplied to the cavity C from the oxygen gas supply device 80 passes through the internal space of the injection sleeve 16 through the cavity C and is discharged from the supply port 16h to the outside of the injection sleeve 16.
In this state, the closed space formed by the valve movement space Sp, the cavity C, and the inner space of the injection sleeve 16 is filled with oxygen gas O2, and the oxygen gas released from the supply port 16h causes the valve movement space Sp, cavity. C and gas that is harmful to the die-casting process such as outside air gas that has entered (residual) in the injection sleeve 16 is discharged to the outside of the injection sleeve 16. As described above, the oxygen gas remains in the cavity C and the like, and the gas is purged which adversely affects the quality of the die cast product.

  The start of pouring of the molten metal ML into the injection sleeve 16 is performed by, for example, inputting a detection signal of a temperature sensor disposed in the vicinity of a supply port 16h of the injection sleeve 16 (not shown) to the controller 30, and the controller 30 detects the temperature sensor. It is possible to detect and detect a sudden change in the detection signal. Alternatively, the controller 30 can detect the injection of the molten metal ML according to an instruction from the operator of the die casting apparatus 1.

  The supply of oxygen gas O2 from the oxygen gas supply device 80 into the cavity C and the injection sleeve 16 is started before the start of pouring of the molten metal ML into the internal space of the injection sleeve 16, or during the pouring, Either immediately after the start of pouring may be used.

Time t5: pouring end (S1-3), FIG.
When the amount of molten metal ML necessary for manufacturing one die-cast product is poured into the injection sleeve 16 at time t5, the pouring operation is finished.
The time T1 from the start of pouring to the end of pouring is defined by the amount of the molten metal ML poured into the injection sleeve 16 and is not constant.
By the end of this pouring, the inside of the injection sleeve 16 near the supply port 16h portion of the injection sleeve 16 is almost closed with the molten metal ML. However, even in this state, the second opening / closing valve GV is in an open state, and the oxygen filling process from the oxygen gas supply device 80 is still performed.

Time t6, start of low speed injection (S1-4), FIG.
When it is detected at the time point t6 that the pouring operation has been completed, the controller 30 drives the hydraulic cylinder 11 to drive the piston rod 12 at a low speed. As a result, as illustrated in FIG. 5, the plunger tip 15 connected to the tip of the plunger rod 14 connected to the piston rod 12 shown in FIG. Move on.
The controller 30 calculates the position and moving speed of the plunger rod 14 or the plunger tip 15 based on the detection signal S35 of the position detection sensor 35 and uses it for driving the hydraulic cylinder 11. The moving speed is obtained by the controller 30 by time differentiation of the position.
As the plunger tip 15 moves at a low speed, the molten metal ML introduced into the injection sleeve 16 receives pressure and expands not only in the longitudinal direction in the injection sleeve 16 but also in the cross-sectional direction.
At this time, the third open / close valve SV is in an open state, and the filling of the oxygen gas from the oxygen gas supply device 80 into the cavity C is continued.

Time t7, oxygen supply stop (S2-2), FIG.
The controller 30 starts the low-speed injection of the plunger rod 14 (or the plunger tip 15) at the time t6 at the time t7, and after a predetermined time has elapsed (period from the time t6 to the time t7), the molten metal ML enters the injection sleeve 16. When full, the control signal 30SD for deactivating and closing the second open / close valve GV is output, the second open / close valve GV is closed, and oxygen from the oxygen gas supply device 80 to the cavity C is output. Stop filling gas. Thereby, the filling process of the oxygen gas into the cavity C and the injection sleeve 16 by the oxygen gas supply device 80 is completed.
Further, the controller 30 deenergizes the shut-off valve 60 and closes the shut-off valve 60, that is, the valve body 62 comes into contact with the valve seat member 64 and closes the gap between the valve body 62 and the valve seat member 64. To a state to do.

A certain time (period) T2 from time t4 to time t7 is preferably as short as possible in order to prevent oxidation of the molten metal ML poured into the injection sleeve 16 and to prevent a temperature drop of the molten metal ML. .
In the oxygen substitution die casting method, oxygen gas is supplied only for a short period of time during which the plunger rod 14 (or plunger tip 15) is injected and advanced toward the cavity C after the molten metal ML starts to be poured from the supply port 16h. It may be replaced.

Time point t8: Preparation of the main decompression system and the auxiliary decompression system is stopped, FIG.
After the controller 30 closes the second open / close valve GV and the oxygen gas supply device 80 stops filling the cavity C and the injection sleeve 16 with oxygen gas, at time t8, the controller 30 turns the first vacuum pump 50A on. Stop and stop the decompression operation in the main decompression tank TA. Similarly, the controller 30 stops the operation of the second vacuum pump 50B and stops the pressure reducing operation in the auxiliary pressure reducing tank TB.
It is assumed that the main pressure-reducing tank TA and the auxiliary pressure-reducing tank TB are decompressed to a sufficiently low pressure state, preferably a substantially vacuum state, by the above-described pressure reducing preparation operation.
The first vacuum pump 50A and the second vacuum pump 50B are stopped before the timing when the pressure states in the main decompression tank TA and the auxiliary decompression tank TB reach a sufficiently low pressure, preferably almost a vacuum state. At any point in time, the stop operation may be performed independently.

Time t9: Supply port 16h is closed (S1-5), FIG.
At time t9, the controller 30 drives the hydraulic cylinder 11 while monitoring the detection signal S35 of the position detection sensor 35, so that the plunger tip 15 exceeds the supply port 16h of the injection sleeve 16 and closes the supply port 16h. The plunger tip 15 (plunger rod 14) is ejected at a low speed until this occurs. As a result, as illustrated in FIG. 7, in the injection sleeve 16 in the vicinity of the supply port 16 h, the molten metal ML that has received the pressure of the plunger tip 15 expands in the direction of the inner wall of the injection sleeve 16 and closes the injection sleeve 16. It becomes like this. Therefore, the inside of the injection sleeve 16 that is not filled with the valve movement space Sp, the cavity C, and the molten metal ML is sealed with respect to the outside of the injection sleeve 16 by the molten metal ML and the plunger tip 15. As a result, no outside air enters from the supply port 16h.

Time point t10: Start of decompression of the main decompression system, FIG.
After closing the supply port 16h, the controller 30 outputs a control signal 30SA for opening the first opening / closing valve MV to the first opening / closing valve MV at time t10. Actually, after the time t9 when the controller 30 performs the closing operation of the supply port 16h at the time t9, the first time after a predetermined time T4 when the inside of the injection sleeve 16 near the supply port 16h is actually closed with the molten metal ML is passed. Open / close valve MV is opened.
Further, the controller 30 opens the shutoff valve 60. Thereby, the valve body 62 is separated from the valve seat member 64.
Through the above-described operation, the main decompression tank TA in the vacuum state or substantially in the vacuum state passes through the exhaust pipe 51, the exhaust passage 52, the second through hole 64 b, and the gap between the valve body 62 and the valve seat member 64. The inside of the main decompression system defined by the closed space such as the internal space not filled with the molten metal ML, the cavity C following the internal space, the valve moving space Sp and the exhaust passage 52 is depressurized. By this decompression operation, the oxygen gas filled in the closed space is also discharged to the outside.
This decompression operation is referred to as a first decompression operation in the present specification, and is continued after the high-speed injection at time t13 and further to time t15 after completion of filling at time t14.

Time t11: Start of operation of the auxiliary decompression system, FIG.
After closing the supply port 16h at time t9, the controller 30 outputs a control signal 30SB for opening the third opening / closing valve SV to the third opening / closing valve SV at time t11.
Actually, the controller 30 performs the closing operation of the supply port 16h at time t9, and then the third opening / closing valve SV after a predetermined time T3 when the inside of the injection sleeve 16 near the supply port 16h is actually closed with the molten metal ML. Open.
As a result, the injection sleeve 16 is disposed in the fixed mold flow path 2 c through the exhaust pipe 90, in the movable mold flow path 3 c through the exhaust pipe 91, the groove 15 h of the plunger tip 15, and the inner pipe of the plunger rod 14. The inside is evacuated by being evacuated by an auxiliary decompression tank TB in a vacuum state or a substantially vacuum state.
That is, the fixed mold flow path 2c through the exhaust pipe 90 and the moving mold flow path through the exhaust pipe 91 by supplying (filling) oxygen gas into the cavity C and the injection sleeve 16 from the oxygen gas supply device 80. 3c and the oxygen gas remaining in the groove 15h, as well as the oxygen gas purge, the oxygen pipe purge, the fixed mold flow path 2c, the exhaust pipe 91, the movable mold flow path 3c, the groove 15h, etc. Minute gas such as the outside air that has entered these places is harmful to the die casting and is discharged to the outside by the auxiliary decompression tank TB.
Due to the gas discharging operation by the auxiliary decompression tank TB, there is no outside air in the fixed mold flow path 2c, the movable mold flow path 3c and the like, and no outside air gas enters these portions.
This decompression operation is referred to as a second decompression operation in this specification, and is continued until time t15 before the die-cast product removal operation at time t16.

In the above example, the end timing of the first decompression operation by the main decompression tank TA and the termination timing of the second decompression operation by the auxiliary decompression tank TB are the same time t15.
In the example described above, the decompression operation (first decompression operation) of the main decompression system (first decompression system) is performed first, and the decompression operation (first decompression operation) of the auxiliary decompression system (second decompression system) is performed later. As described above (predetermined time T4> T3), the predetermined time T3 = T4 may be set after the supply port 16h is closed.
Alternatively, the controller 30 can simultaneously start the decompression of the main decompression system by the opening operation of the first on-off valve MV and the decompression start of the auxiliary decompression system by the opening operation of the third on-off valve SV.
Contrary to the above, it is also possible to start the decompression of the auxiliary decompression system first and start the decompression of the main decompression system later (predetermined time T3> T4).

Time t12: Partial operation stop of main decompression system, FIG.
At a time t12 after the elapse of a predetermined time T5 when the operation of the main pressure reducing system is started at the time t10 and before the high-speed injection at the time t13, the controller 30 sends a control signal 30SC for closing the shutoff valve 60 to the electromagnetic actuator 61. The shut-off valve 60 is closed, that is, the valve body 62 is seated on the valve seat member 64.
As a result, as illustrated in FIG. 10, the shut-off valve 60 is closed, and communication between the valve movement space Sp and the exhaust path 52 is lost. However, since the first open / close valve MV is in the open state, the pressure reducing operation of the exhaust passage 52 and the second through hole 64b by the main pressure reducing tank TA is continuously performed.
The shut-off valve 60 is closed before the high-speed injection at the time point t13 because the molten metal ML introduced into the cavity C at high speed and high pressure by the high-speed injection enters the valve movement space Sp, the second through hole 64b, and the like. This is to prevent being pulled in. On the other hand, even if the auxiliary decompression system is operating, there is no concern as described above, so the operation of the auxiliary decompression system is continued.

During the period from time t10 to time t12, or from time t11 to time t12, the main decompression system and the auxiliary decompression system operate in parallel.
By the operation of the main decompression system, oxygen gas and outside air (if any) in the cavity C are exhausted to the outside via the valve movement space Sp, the second through hole 64b, and the exhaust passage 52, while the main decompression system. By the initial operation, the oxygen gas filled in the cavity C or the like from the oxygen gas supply device 80 is filled to every corner of the closed space such as the cavity C or the injection sleeve 16 to enhance the effect of the oxygen substitution die casting method. . Further, by the operation of the auxiliary pressure reducing system, the outside air is discharged from the fixed mold flow path 2c, the movable mold flow path 3c, the groove 15h, and the like through the exhaust pipe 90, the exhaust pipe 91, and the like.
As described above, by the parallel operation of the main pressure reducing system and the auxiliary pressure reducing system, the gas that adversely affects the die casting process in the die casting apparatus 1 is continuously removed everywhere in the die casting apparatus or enters from the outside. Can not.

Time t13: High-speed injection (S1-6), FIG.
At time t13, the controller 30 drives the hydraulic cylinder 11 to move the piston rod 12 to the left side at high speed in the illustrated state. As a result, the plunger tip 15 connected to the plunger rod 14 moves toward the cavity C at a high speed in the injection sleeve 16.
As a result, the molten metal ML poured into the injection sleeve 16 is rapidly filled into the cavity C from the injection sleeve 16. Due to the high-speed injection of the molten metal ML, the pressure in the high-speed cavity C of the cavity C increases rapidly after time t13.

The plunger tip 15 is maintained in a state of being moved within the injection sleeve 16 by a predetermined distance. Thereby, the pressure in the cavity C is maintained in a high state.
The molten metal ML filled in the cavity C fills the cavity C and becomes a desired die-cast product.

Time t14: Completion of filling (S1-7), FIG.
After the cavity C is filled with the molten metal ML by high-speed injection, the filling is completed at a time t14 when a predetermined time has elapsed.

Time t15: complete stop of main decompression system, end of operation of auxiliary decompression system, FIG.
After filling, the controller 30 outputs a control signal 30SA for closing the first opening / closing valve MV to the first opening / closing valve MV at time t15. As a result, as illustrated in FIG. 12, the first opening / closing valve MV is closed, and the pressure reducing operation from the main pressure reducing tank TA ends.
The controller 30 also outputs a control signal 30SB for closing the third open / close valve SV to the third open / close valve SV. As a result, as illustrated in FIG. 12, the first opening / closing valve MV and the third opening / closing valve SV are closed, and the fixed die flow path 2c via the exhaust pipe 90 and the exhaust pipe 91 are opened by the auxiliary decompression tank TB. The decompression operation in the injection sleeve 16 via the moving mold flow path 3c, the groove 15h of the plunger tip 15 and the plunger rod 14 is terminated.

From the initial state to the time point t15 described above, the first open valve OV1 and the second open valve OV2 are closed.
Preferably, after the elapse of a predetermined time at time t15, when the die-cast product in the cavity C is cooled and can be removed, that is, after the filling of the molten metal into the cavity C at time t15 and before time t16. After the die casting process is completed, for example, the controller 30 opens the first open valve OV1 and the second open valve OV2. As a result, since the inside of the mold is in the atmospheric pressure state, the pressure difference is reduced, and the mold opening operation at time t16 is facilitated.
In order to further enhance the above-described effect of the first open valve OV1, it is desirable that the controller 30 opens the shut-off valve 60 as well as the first open valve OV1.

Time t16, removal of die-cast product (S1-8)
When the die-cast product in the cavity C is cooled and can be removed after a predetermined time at the time t15, the fixed state of the fixed mold 2 and the movable mold 3 is released, and the push pin 65 is pushed to enter the cavity C. Take out the die-cast product.

As described above, according to the embodiment of the present invention, in addition to the exhaust in the cavity C by the decompression operation by the main decompression system, by the decompression operation by the auxiliary decompression system, the inside of the cavity C, the injection sleeve 16, the valve moving space. Gases that adversely affect die casting in Sp and the like are eliminated, and high quality die casting products can be manufactured.
Further, according to the present embodiment, a high-quality die-cast product can be manufactured by appropriate oxygen supply by the reduced pressure oxygen substitution die casting method.
Furthermore, in this embodiment, since a series of operations can be performed continuously in a short time, a large temperature drop does not occur in the molten metal ML poured into the injection sleeve 16, and a high-quality die-cast product can be manufactured.
According to the present embodiment, an effect is exerted on cycle extension.

According to the present embodiment, after the closed space including the cavity C is filled with oxygen gas, the fixed mold flow path 2c of the fixed mold 2 and the movable mold flow path 3c of the moving mold 3 are filled by the auxiliary decompression tank TB. Since exhaust by decompression is performed from the flow path formed between the groove 15h of the plunger tip 15 and the inner peripheral surface of the sleeve 16, oxygen gas can be surely replaced to every corner in the closed space including the cavity C, Also, the gas intrusion path can be reliably replaced with oxygen gas.
Further, after the inside of the closed space including the cavity C is surely replaced with oxygen gas, unnecessary gas such as air does not enter the cavity C by continuing the exhaust in the closed space by the auxiliary decompression tank TB.
Further, since both the auxiliary pressure reducing tank TB and the main pressure reducing tank TA reduce the pressure in the cavity C, the sleeve, and the clearance (clearance), the time required for pressure reduction can be shortened, and the oxygen gas remaining in the cavity C can be reduced. Can be very little.

The implementation of the die casting apparatus and the reduced pressure casting method of the present invention is not limited to the above-described exemplary embodiment, and various modifications can be made.
In the above-described embodiment, the case where the main pressure reducing means and the auxiliary pressure reducing means of the present invention are configured by the main pressure reducing tank TA and the auxiliary pressure reducing tank TB has been described. It is also possible to do.

  The portion where the auxiliary decompression tank TB is operated to decompress the cavity C is not limited to the above-described fixed mold flow path 2c, moving mold flow path 3c, groove 15h of the plunger tip 15, and other outside air. It can be applied to a portion that may enter the cavity C or the like. Examples of such other parts include a gap between the moving mold 3 and the shut-off valve 60 attached to the moving mold 3, such as a gap between the valve seat member 64 and the external moving mold 3b. There is.

  As an example of the operation in the die casting apparatus of the embodiment of the present invention, the case where the molten metal ML is injected at a low speed and then injected at a high speed has been described. However, in the die casting apparatus of the embodiment of the present invention, the molten metal ML is described. The movement speed of the plunger tip 15 is not limited to the above-described two-stage movement speed, and for example, the molten metal is poured at an appropriate movement speed such as only one movement speed or a movement speed by three-stage switching. It can be injected into the cavity.

  The above-described control operations by the controller 30 in the die casting apparatus according to the embodiment of the present invention, for example, switching of the opening / closing operation of the shut-off valve 60, opening / closing switching control of the first to third opening / closing valves MV, GV, SV, etc. The state of the entire die casting apparatus to be performed, for example, the moving position and moving speed of the plunger tip 15 can be performed according to predetermined conditions. Such determined conditions are registered in advance in a memory in the controller 30, for example. Therefore, as described above, the controller 30 reads the position detection sensor 35 and / or the position detection sensor 35 without recognizing an operation state such as low speed injection or high speed injection of the plunger tip 15 or the molten metal ML. The control operation similar to that described above can be performed with reference to the detected value and its change.

  The shut-off valve 60 corresponding to the first on-off valve means of the present invention may be mounted not only on the movable mold 3 but also on the fixed mold 2. Preferably, the shut-off valve 60 can be attached to the moving mold 3 and the stationary mold 2. Thereby, the decompression time of the cavity can be shortened.

Furthermore, the main decompression tank TA and the auxiliary decompression tank TB used for the same application may be made into one common tank. By doing so, the equipment of the die casting apparatus is simplified, and the cost of the equipment of the die casting apparatus can be reduced.
Further, instead of the hydraulic cylinder 11, the piston rod 12 can be moved left and right by using another hydraulic medium driving means, for example, a hydraulic medium driving means.
Moreover, not only the illustration mentioned above but the piston rod 12 can also be moved with an electric actuator.

FIG. 1 is a diagram showing a configuration of a die casting apparatus according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of the die casting apparatus illustrated in FIG. 1 centering on a fixed mold and a movable mold, and is a view showing the operation of the die casting apparatus from time t0 to time t3. FIG. 3 is a process diagram (flow chart) showing the operation of the die casting apparatus illustrated in FIG. 1 in time series. FIG. 4 is a diagram illustrating the operating state of the main part of the die casting apparatus in each step illustrated in FIG. FIG. 5 is a diagram illustrating the operating state of the main part of the die casting apparatus in each step illustrated in FIG. FIG. 6 is a diagram illustrating the operating state of the main part of the die casting apparatus in each step illustrated in FIG. FIG. 7 is a diagram illustrating the operating state of the main part of the die casting apparatus in each step illustrated in FIG. FIG. 8 is a diagram illustrating the operating state of the main part of the die casting apparatus in each step illustrated in FIG. FIG. 9 is a diagram illustrating the operating state of the main part of the die casting apparatus in each step illustrated in FIG. FIG. 10 is a diagram illustrating the operating state of the main part of the die casting apparatus in each step illustrated in FIG. FIG. 11 is a diagram illustrating the operating state of the main part of the die casting apparatus in each step illustrated in FIG. FIG. 12 is a diagram illustrating the operating state of the main part of the die casting apparatus in each step illustrated in FIG.

Explanation of symbols

1 ... Die casting device 2 ... Fixed mold
2a ... internal fixed mold, 2b ... external fixed mold, 2c ... fixed mold flow path
2d ... cavity surface, 2e ... valve movement space surface, 2f ... divided surface 3 ... moving mold
3a ... Internal moving mold, 3b ... External moving mold, 3c ... Moving mold flow path
3f ... Dividing surface Sp ... Valve movement space C ... Cavity 10 ... Injection device
11 ... Hydraulic cylinder, 12 ... Piston rod, 13 ... Coupling
14 ... plunger rod, 15 ... plunger tip, 15h ... groove
16 ... Injection sleeve, 16h ... Supply port
17 ... Injection plunger 30 ... Controller 51 ... Exhaust pipe, 52 ... Exhaust passage, 50A, 50B ... Vacuum pump 60 ... Shut-off valve
61 ... Electromagnetic actuator, 62 ... Valve body, 63 ... Valve stem,
64. Valve seat member
64a ... 1st through-hole, 64b ... 2nd through-hole, 64f ... Valve seat surface 65 ... Extrusion pin 80 ... Oxygen gas supply apparatus, 90, 91 ... Exhaust pipe TA, TB ... 1st, 2nd decompression tank,
MV, GV, SV ... 1-3 open / close valves OV1, OV2 ... 1st, 2nd open valves

Claims (3)

A fixed mold having an internal fixed mold, an external fixed mold surrounding the internal fixed mold, and a fixed mold channel formed as a gap between the internal fixed mold and the external fixed mold Type,
An internal moving mold that forms a cavity in which the molten metal is accommodated together with the internal fixed mold, an external moving mold that surrounds the internal moving mold, and between the internal moving mold and the external moving mold A moving mold having a moving mold flow path formed as a gap in
A first pressure reducing means having a first pressure reducing tank and a first on-off valve connected to the first pressure reducing tank;
An oxygen supply means having an oxygen gas supply device and a second on-off valve connected to the oxygen gas supply device;
A second pressure reducing tank, a third on-off valve connected to the second pressure reducing tank, and an exhaust for gas disposed between the third on-off valve, the fixed mold flow path, and the fixed mold flow path A second decompression means having a pipe;
A first on-off valve means, provided in the moving mold, for bringing the first decompression means or the oxygen gas supply means and the cavity into communication or non-communication;
An inner cylindrical injection sleeve having an opening communicating with the cavity and a supply port for pouring the molten metal on the side facing the opening;
A plunger tip movably inserted in the inner cylinder of the injection sleeve; and a plunger rod connected to the plunger tip for moving the plunger tip, and poured into the injection sleeve from the supply port. Injection plunger means for injecting the molten metal toward the cavity via the opening;
A position sensor for detecting the position of the plunger rod;
Injection cylinder means for driving the injection plunger means;
Control means;
Comprising
The control means includes
When the start of pouring of the molten metal into the injection sleeve is detected by a detection signal from a temperature sensor disposed near the supply port of the injection sleeve or an operator's instruction, the second on-off valve and the The first on-off valve means is opened to fill the cavity and the injection sleeve with oxygen gas and fill the oxygen gas while oxidizing the surface of the molten metal poured into the injection sleeve. gas Ru is exhausting gas other than oxygen gas together with oxygen gas in the injection sleeve and the cavity are released from the supply port, performing a first process,
When pouring of the molten metal into the pre-Symbol injection sleeve is completed, and the distal end of the plunger rod of the injection plunger means drives the injection cylinder unit is moved at a first speed toward the opening , Starting the injection of the molten metal poured into the injection sleeve into the cavity, performing a second process,
The second process by the time it is detected that has passed a predetermined time after the start of the movement in the first speed of the plunger rod, the second on-off valve in the closed state to terminate the filling of the oxygen gas, the Performing a third process for closing the first on-off valve means ;
Based on the amount of movement of the plunger rod obtained from the detection value of the position sensor, the plunger tip until the plunger tip by the second process exceeds the supply port of the injection sleeve and closes the supply port. the Before moving at the first speed, it performs the fourth process,
After the supply port by the fourth processing becomes closed state, the first within the first pressure reducing means off valve and the first on-off valve means within said cavity by said first vacuum tank by the opened And starting a decompression of the inside of the injection sleeve, performing a fifth process,
After the first on-off valve and the first on-off valve means is in the open state by the fifth processing, and the third on-off valve of the second pressure reducing means in the open state, is connected to the exhaust pipe Starting a pressure reduction of the fixed mold flow path and the fixed mold flow path by the second pressure reducing tank , and performing a sixth process,
In the sixth process, the decompression of the cavity and the injection sleeve is continued for a predetermined time by the first decompression tank, and then a seventh process of closing the first on-off valve means is performed.
The molten metal poured into the injection sleeve by driving the injection cylinder means and moving the tip of the plunger rod of the injection plunger means toward the opening at a second speed higher than the first speed. Is injected into the cavity at a high speed, and an eighth process is performed.
After a predetermined time has elapsed after the start of the movement of the plunger rod at the second speed by the eighth process , the first open / close valve and the third open / close valve are closed to operate the first decompression tank and Performing the ninth process of ending the pressure reducing operation by the second pressure reducing tank;
Die casting device. A first through hole facing the cavity is formed in the internal movement mold,
The first on-off valve means provided in the moving mold is
A valve body for communicating or non-communication between the through hole and the cavity;
Driving means for moving the valve body;
Have
The internal movement mold and the external movement mold have a first through hole and a second through hole connected to a pipe connected to the first on-off valve and the second on-off valve. Being
The die casting apparatus according to claim 1. A fixed mold having an internal fixed mold, an external fixed mold surrounding the internal fixed mold, and a fixed mold channel formed as a gap between the internal fixed mold and the external fixed mold A mold, an internal moving mold that forms a cavity in which the molten metal is accommodated together with the internal fixed mold, an external moving mold that surrounds the internal moving mold, the internal moving mold, and the external moving mold A first depressurizing means having a moving mold having a moving mold channel formed as a gap between the first depressurizing tank and a first open / close valve connected to the first depressurizing tank; An oxygen supply means, an oxygen supply means having a second open / close valve connected to the oxygen gas supply apparatus, a second decompression tank, and a third open / close valve connected to the second decompression tank; The third on-off valve, the fixed mold flow path, and the front A second decompression unit having an exhaust pipe disposed between the fixed mold flow path, the first decompression unit or the oxygen gas supply unit, and the cavity provided in the movable mold. An inner cylindrical injection sleeve having a first on-off valve means to be in a communication state or a non-communication state, an opening communicating with the cavity, and a supply port for pouring the molten metal on a side facing the opening; A plunger tip movably fitted in the inner cylinder of the injection sleeve, and a plunger rod connected to the plunger tip and moving the plunger tip, and pouring water into the injection sleeve from the supply port Injection plunger means for injecting the molten metal toward the cavity via the opening, a position sensor for detecting the position of the plunger rod, and the injection plunger A control method of a die casting apparatus comprising an injection cylinder means for driving the stage, and
When the start of pouring of the molten metal into the injection sleeve is detected by a detection signal from a temperature sensor disposed near the supply port of the injection sleeve or an operator's instruction, the second on-off valve and the The first on-off valve means is opened to fill the cavity and the injection sleeve with oxygen gas and fill the oxygen gas while oxidizing the surface of the molten metal poured into the injection sleeve. gas Ru is exhausting gas other than oxygen gas together with oxygen gas in the injection sleeve and the cavity are released from the supply port, performing a first process,
When pouring of the molten metal into the pre-Symbol injection sleeve is completed, and the distal end of the plunger rod of the injection plunger means drives the injection cylinder unit is moved at a first speed toward the opening , Starting the injection of the molten metal poured into the injection sleeve into the cavity, performing a second process,
The second process by the time it is detected that has passed a predetermined time after the start of the movement in the first speed of the plunger rod, the second on-off valve in the closed state to terminate the filling of the oxygen gas, the Performing a third process for closing the first on-off valve means ;
Based on the amount of movement of the plunger rod obtained from the detection value of the position sensor, the plunger tip until the plunger tip by the second process exceeds the supply port of the injection sleeve and closes the supply port. the Before moving at the first speed, it performs the fourth process,
After the supply port by the fourth processing becomes closed state, the first within the first pressure reducing means off valve and the first on-off valve means within said cavity by said first vacuum tank by the opened And starting a decompression of the inside of the injection sleeve, performing a fifth process,
After the first on-off valve and the first on-off valve means is in the open state by the fifth processing, and the third on-off valve of the second pressure reducing means in the open state, is connected to the exhaust pipe Starting a pressure reduction of the fixed mold flow path and the fixed mold flow path by the second pressure reducing tank , and performing a sixth process,
In the sixth process, the decompression of the cavity and the injection sleeve is continued for a predetermined time by the first decompression tank, and then a seventh process of closing the first on-off valve means is performed.
The molten metal poured into the injection sleeve by driving the injection cylinder means and moving the tip of the plunger rod of the injection plunger means toward the opening at a second speed higher than the first speed. Is injected into the cavity at a high speed, and an eighth process is performed.
After a predetermined time has elapsed after the start of the movement of the plunger rod at the second speed by the eighth process , the first open / close valve and the third open / close valve are closed to operate the first decompression tank and Performing the ninth process of ending the pressure reducing operation by the second pressure reducing tank;
Control method for die casting equipment.

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