KR100870596B1 - Die cast apparatus and casting method - Google Patents

Abstract

An object of the present invention is to provide a die-casting apparatus capable of shortening the time required for depressurization and reducing the pressure to a lower pressure when injecting and filling a molten metal by depressurizing the inside of the cavity. The diecast apparatus is connected to a closed space to be decompressed including the cavity C, and includes a plurality of vacuum tanks TA and TB previously depressurized, and a closed space including the vacuum tanks TA and TB and the cavity C. A plurality of on / off valves 70A and 70B that open and close the gaps respectively, and the vacuum tank used by the control means 30 for depressurization of the closed space including the cavity C is used to open and close the on / off valves 70A and 70D. It switches over and depressurizes the inside of the closed space containing the cavity C to desired pressure.

Closed spaces, metal baths, die cast units, vacuum tanks, on / off valves, control means

Description

Die casting apparatus and casting method {DIE CAST APPARATUS AND CASTING METHOD}

The objects, features, and other objects and features of the present invention described above will become more apparent from the following description based on the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view showing a structure around a die of a die casting apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing an example of the operation of the diecast apparatus shown in FIG.

FIG. 3 is a diagram showing a relationship between the cavity C and the vacuum tanks TA and TB in the diecasting device shown in FIG.

FIG. 4 is a graph showing a change in pressure in the cavity shown in FIG.

Fig. 5 is a sectional view showing a structure around a die of the die casting apparatus according to the second embodiment of the present invention.

FIG. 6 is a flowchart showing an example of the operation of the diecast apparatus shown in FIG. 5; FIG.

FIG. 7 is a graph showing the pressure change in the cavity when the auxiliary tanks STA and STB in the die-casting apparatus shown in FIG. 5 are used. FIG.

FIG. 8 is a graph showing the pressure change in the cavity when the auxiliary tank STR is not used in the diecasting device shown in FIG.

<Explanation of symbols for the main parts of the drawings>                 

1: diecast device

2: fixed mold

2a, 2b, 3a, 3b: absence

3: moving mold

10: injection device

11: hydraulic cylinder

12: piston rod

13: coupling

14: plunger rod

15: plunger chip

16: injection sleeve

30: controller

35: position detection sensor

51: exhaust pipe

60: shutoff valve

61: electronic actuator

62: valve member

63: valve shaft

64: valve seat member

65: extrusion pin                 

TA, TB: Vacuum Tank

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diecasting apparatus, and more particularly, to a diecasting apparatus using a vacuum diecasting method in which gas in a mold cavity is evacuated before injection and filling of molten metal and cast under reduced pressure.

One of the causes of the deterioration of reliability due to the variation of the material of the die cast product is the mixing of gas into the die cast product. That is, the molten metal injected and filled at high speed and high pressure becomes turbulent in the cavity of the injection sleeve and the mold, and the molten metal is wound up by evaporating the release agent coated with air or the mold.

In order to overcome the above problems, casting by using a die-casting machine by the vacuum die-casting method, which die-casts in an atmosphere in which air or the like is not drawn in, suppresses the mixing of gas into the die-cast product and die-casts. Techniques for reducing variations in quality due to the incorporation of gas in products are known (see, eg, US Pat. No. 2,785,448).

In the die-casting machine using the vacuum die-casting method, in order to cast a diecast product of high strength and high quality, it is required to be able to make a high vacuum in a metal mold and to maintain a high pressure reduction state. If the mold is not highly vacuumed, gas is contained in the cast die-cast product, and when the heat treatment such as annealing after casting is performed on the product, distortion or deformation tends to occur in the product, thereby obtaining a sufficient effect by the vacuum die-casting method. Because it is difficult.

By the way, in the die-casting machine using the vacuum die-casting method, in order to shorten a casting cycle, it is necessary to shorten the time required for pressure reduction in a metal mold | die.

In order to shorten the time required for depressurization in the mold, a method of connecting the vacuum tank, which has been depressurized to a predetermined pressure in advance, to the mold, and decompressing the mold can be considered by opening and closing the valve.

However, in the above-described method, the decompression rate decreases when the pressure in the mold and the pressure in the vacuum tank are equalized. For this reason, there existed a disadvantage that it takes a long time to pressure-reduce the inside of a metal mold to a predetermined pressure.

When the pressure in the mold and the pressure in the vacuum tank are equalized, when a pressure lower than the equalized pressure is required, the pressure in the mold needs to be reduced to a pressure lower than the equalized pressure by a vacuum pump or the like. Cost more time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a die casting apparatus and a casting method which can shorten the time required for decompression when injecting and filling a molten metal by depressurizing the inside of the cavity and reducing the pressure to a lower pressure. .

The die-casting apparatus of the present invention is a die-casting apparatus for evacuating and reducing the inside of a cavity formed by a mold, and molding and casting a molten metal by injecting and filling a molten metal into the pressurized cavity, the closed space being reduced in pressure including the cavity. And a plurality of opening / closing means and control means connected to each other to open and close the connection path between the plurality of vacuum tanks previously depressurized and the plurality of vacuum tanks and the closed space, respectively. The control means depressurizes the closed space by using a part of the plurality of vacuum tanks, and then closes the connection path between the partial vacuum tank and the closed space, and simultaneously with the other vacuum tank and the closed space decompressed. Open the connection path to further depressurize.

The plurality of vacuum tanks are connected to an exhaust path provided in the mold, and are connected to a main vacuum tank for depressurizing the closed space including the cavity, and to a leakage path of air in the closed space other than the exhaust path. It has a 1st and 2nd auxiliary vacuum tank which auxiliary pressure-reduces the containing closed space. The control means may employ a configuration in which the main vacuum tank and the first auxiliary vacuum tank are depressurized after the vacuum closed space is decompressed, and the pressure is further reduced using the second auxiliary vacuum tank.

The casting method of the present invention is a casting method for evacuating and depressurizing a cavity formed by a mold, and molding a casting by injecting and filling a molten metal into the pressure-reduced cavity, and connected to a closed space to be reduced in pressure including the cavity. And a first depressurization step of depressurizing a portion of the plurality of vacuum tanks previously depressurized, a second depressurization step of further depressurizing the decompressed closed space by another vacuum tank of the plurality of vacuum tanks, and the other vacuum. And a filling step of injecting and filling the molten metal into the cavity decompressed by the tank.

In this invention, pressure reduction is started first using a part of several vacuum tank as a 1st pressure reduction process. When the pressure is reduced by this partial vacuum tank and the pressure in the cavity becomes equal to the pressure of the vacuum tank, the decompression rate decreases. Therefore, when the pressure is reduced by using another vacuum tank instead of some vacuum tanks as the second pressure reduction process, another pressure reduction of the cavity is quickly performed by the pressure difference existing between the cavity (part of the vacuum tank) and the other vacuum tank. The pressure in the cavity can be reduced to a lower pressure.

According to the present invention, the time required for depressurization in the cavity of the mold can be shortened, and the pressure can be reduced to a lower pressure.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described with reference to drawings.

<First Embodiment>

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the structure around the metal mold | die of the die-casting apparatus which concerns on one Embodiment of this invention.

The die cast apparatus 1 has a stationary mold 2, a moving mold 3, an injection apparatus 10, a controller 30, vacuum tanks TA, TB, a shutoff valve 60, and the like.

In addition, the stationary die 2 and the moving die 3 are one embodiment of the mold of the present invention, and the injection device 10 is an embodiment of the injection device of the present invention.

The controller 30 is also an example of the control means of the present invention. The controller 30 is configured using a computer and a memory, and performs various control processes of the diecast apparatus described below.                     

The stationary metal mold | die 2 is comprised by the some member 2a, 2b. The fixed die 2 is fixed to a fixed die plate of a die fastening device (not shown). The injection sleeve 16 of the injection apparatus 10 mentioned later is being fixed to the fixed die 2.

The moving mold 3 is comprised by the some member 3a, 3b. The shutoff valve 60 is integrally attached to the moving die 3. Moreover, the some extrusion pin 65 is provided in the movement metal mold | die 3 so that a movement is possible.

The stationary die 2 and the movable die 3 shown in Fig. 1 are in a mold clamping state. The stationary die 2 is fixed to the stationary die plate of the mold clamping apparatus which is not shown in figure, and the moving die 3 is fixed to the movable die plate of the mold clamping apparatus which is not shown in figure. For example, by the toggle mechanism or the like, the moving die plate is pressed against the fixed die plate by a predetermined force, whereby the fixed die 2 and the moving die 3 are mold-fastened.

The cavity C for casting a casting is formed between the divided surface 2f of the stationary mold 2 and the divided surface 3f of the moving mold 3.

Between the divided surface 2f of the fixed mold 2 and the divided surface 3f of the moving mold 3, the sealing member SL which seals between the divided surface 2f and the divided surface 3f is provided. . This sealing member SL is made of silicone rubber, for example.

The shutoff valve 60 is provided in the moving die 3. The shutoff valve 60 is one embodiment of the on-off valve of the present invention.

The shutoff valve 60 has an electromagnetic actuator 61, a valve member 62, a valve shaft 63, and a valve seat member 64.                     

The valve seat member 64 is a cylindrical member having a through hole 64a and is embedded in the moving mold 3. The sealing member SL is provided between the valve seat member 64 and the member 3b of the moving mold 3. The valve seat member 64 is disposed at a position corresponding to the valve seat surface 64f or the divided surface 3f of the moving mold 3.

In the moving mold 3 and the valve seat member 64, an exhaust path 52 penetrating the through hole 64a of the valve seat member 64 is formed. The exhaust pipe 51 is connected to the exhaust path 52, and a plurality of vacuum tanks TA and TB are connected to the exhaust pipe 51 via the open / close valves 70A and 70B.

The valve shaft 63 is inserted into the through hole 64a of the valve seat member 64, and is driven by the electromagnetic actuator 61 in the straight movement direction indicated by the arrow in FIG.

Between the stationary die 2 and the movable die 3, a space Sp in which the valve member 62 provided at the distal end of the valve shaft 63 is movable is formed. The space Sp communicates with the cavity C. Therefore, the cavity C communicates with the exhaust pipe 51 through the space Sp, the through hole 64a of the valve seat member 64 and the exhaust passage 52.

The valve member 62 provided at the tip end of the valve shaft 63 is driven toward the valve seat member 64 side, thereby contacting the valve seat surface 64f of the valve seat member 64. As a result, the exhaust path connecting the cavity C and the exhaust pipe 51 is closed. The valve member 62 is driven to the stationary mold 2 side, whereby an exhaust path connecting the cavity C and the exhaust pipe 51 is opened.

The electronic actuator 61 is driven by receiving the control command 30sc from the controller 30.

The injection apparatus 10 is equipped with the injection sleeve 16, the injection plunger 17 which consists of the plunger rod 14 and the plunger chip 15, and the hydraulic cylinder 11. As shown in FIG.

The injection sleeve 16 is made of a cylindrical member and fixed to the fixed mold 2, and communicates with the cavity C described above. On the rear end side of the injection sleeve 16, a supply port 16h for supplying a molten metal is formed.

The plunger chip 15 is fixed to one end of the plunger rod 14 and fitted to the inner circumference of the injection sleeve 16. As the plunger chip 15 moves forward from the supply port 16h, the injection sleeve 16 is closed against the outside.

The other end of the plunger rod 14 is connected to the piston rod 12 of the hydraulic cylinder 11 via the coupling 13.

The hydraulic cylinder 11 is driven by the hydraulic oil of a predetermined pressure to move the piston rod 12.

In order to detect the position of the plunger rod 14, the position detection sensor 35 is provided.

On the outer periphery of the plunger rod 14, magnetic poles are formed at a constant pitch with respect to the axial direction. The position detection sensor 35 detects a change in the magnetic pole of the moving plunger rod 14, for example, converts the change of the magnetic pole into a pulse signal, and outputs it. The position detection sensor 35 outputs a pulsed position detection signal 35s to the controller 30. The controller 30 calculates the position or speed of the injection plunger 17 based on the pulsed position detection signal 35.                     

The first vacuum tank TA is connected to the exhaust pipe 51 via a first opening / closing valve 70A. The first vacuum tank TA exhausts the inside of the closed space including the cavity C formed between the moving mold 3 and the stationary mold 2 through the exhaust pipe 51.

The vacuum tank TA is decompressed to a predetermined pressure in advance by the vacuum pump 50.

The second vacuum tank TB is connected to the exhaust pipe 51 via a second open / close valve 70B. The second vacuum tank TB, like the first vacuum tank TA, has a closed space including a cavity C formed between the moving mold 3 and the fixed mold 2 through the exhaust pipe 51. Exhaust. The second vacuum tank TB is previously depressurized to a predetermined pressure by the vacuum pump 50.

The first opening / closing valve 70A opens and closes a path between the first vacuum tank TA and the exhaust pipe 51. The first opening / closing valve 70A is opened and closed by the control signal 30sa from the controller 30.

The second open / close valve 70B opens and closes the path between the second vacuum tank TB and the exhaust pipe 51. The second open / close valve 70B is opened and closed by the control signal 30sb from the controller 30.

The controller 30 comprehensively controls the die cast apparatus 1 and controls the injection apparatus 10, the shutoff valve 60, the opening / closing valves 70A and 70B, the mold clamping apparatus, the hot water supply apparatus, and the like. In addition, the control means, such as the injection apparatus 10, the shutoff valve 60, the open / close valve 70A, 70B by the controller 30, is mentioned later.

Next, an example of the operation of the diecast apparatus 1 having the above configuration will be described with reference to the flowchart shown in FIG.

At the time of starting casting, the plunger chip 15 is located at the initial position P ₁ which opens the supply port 16h of the sleeve 16. In this state, the cavity C is not sealed, and the pressure in the cavity C is equal to atmospheric pressure.

On the other hand, as shown in Fig. 3A, the vacuum tanks TA and TB are depressurized to -100 kPa when the atmospheric pressure is 0 kPa, and the on-off valves 70A and 70B together. It is closed.

In a state where the plunger chip 15 is located at the initial position P ₁ , the controller 30 outputs a command to a hot water supply device (not shown). Thereby, the molten metal which melt | dissolved metal, such as aluminum alloy and magnesium alloy, is supplied through the supply port 16h of the sleeve 16, for example (step S1).

After the supply (charging) of the predetermined amount of the molten metal to the sleeve 16 is completed, the controller 30 drives the injection apparatus 10 to advance the plunger chip 15 at low speed (step S2).

The controller 30 has reached the position P ₂ at which the plunger chip 15 closes the supply port 16h of the sleeve 16 based on the position detection signal 35s of the position detection sensor 35. It judges (step S3).

When the plunger chip 15 reaches the position P ₂ which closes the supply port 16h of the sleeve 16, the closed space composed of the sleeve 16 and the cavity C is closed.

When the controller 30 determines that the plunger chip 15 has reached the position P ₂ , the controller 30 opens the shutoff valve 60 and the on-off valve 70A (step S4).

If TS is the time point at which the on-off valve 70A is opened, the pressure in the cavity C starts to decrease rapidly from the time point Ts as shown in FIG.

The decompression rate of the pressure in the cavity C decreases with time, and the pressure in the cavity C and the pressure in the vacuum tank TA become equal.

As shown in Fig. 3B, in the state where the pressure in the cavity C and the pressure in the vacuum tank TA are equalized, the pressure in the vacuum tank TA rises from the initial state. For this reason, it is not possible to reduce the pressure in the cavity C to the initial pressure of the vacuum tank TA, for example, -100 kPa.

The controller 30 determines whether or not it is the switching timing Tc for switching the first vacuum tank TA to the second vacuum tank TB (step S5). The switching timing Tc is determined based on, for example, the time when the depressurization speed is lower than the predetermined value, the time when the pressure in the cavity C and the pressure in the vacuum tank TA become substantially equal. Moreover, the pressure in the cavity C is monitored, and the switching timing Tc can be made into the timing at which this pressure was reduced to predetermined pressure, for example, -90 kPa. Alternatively, the position of the plunger chip 15 at the time when the pressure in the cavity C decreases to a predetermined pressure is determined in advance, and the timing at which the plunger chip 15 reaches this position is the switching timing Tc. Can be.

When it is determined that the switching timing Tc has been reached, the controller 30 closes the first on-off valve 70A and opens the second on-off valve 70B (step S6). As a result, the first vacuum tank TA is separated from the cavity C, and the second vacuum tank TB is connected to the cavity C. FIG.

When the second vacuum tank TB is connected to the cavity C, there is a pressure difference between the pressure in the cavity C and the pressure in the second vacuum tank TB, and the pressure in the second vacuum tank TB is lower. . For this reason, as shown in FIG. 4, the pressure in the cavity C falls rapidly again from the time of switching from the 1st vacuum tank TA to the 2nd vacuum tank TB.

As shown in Fig. 3C, when the pressures of the second vacuum tank TB and the cavity C become equal, since the pressure in the cavity C is already reduced by the first vacuum tank TA, The increase in the pressure of the second vacuum tank TB is minimal, and the pressure in the cavity C can be reduced to almost the initial pressure (-100 kPa) of the vacuum tank TB.

Subsequently, the controller 30 determines whether the plunger chip 15 has reached the closed position P ₃ that closes the shutoff valve 60 (step S7). This is to prevent the intrusion of the molten metal into the shutoff valve 60 by reliably closing the shutoff valve 60 before the forward speed of the plunger chip 15 switches to the high speed.

If it is determined that the controller 30 has reached the closed position P ₃ , the controller 30 closes the shutoff valve 60 (step S8).

Subsequently, the controller 30 determines that the plunger chip 15 has reached the high speed switching position P ₄ (step S9). When it is determined that the high speed switching position P ₄ has been reached, the forward speed of the plunger chip 15 is switched at high speed (step S10). Thereby, the molten metal in the sleeve 16 is injected and filled into the cavity C rapidly depressurized.

Subsequently, the controller 30 determines whether the plunger chip 15 has reached the pressure increase switching position P ₅ (step S9). If it is determined hayeotdago reach a pressure increase switch position (P ₅₎ is, the switching of the injection device 10 to the pressure control from the speed control, and increase the casting pressure by the plunger chip 15 (step S11).

The controller 30 determines whether the injection and filling process is completed (step S12), and closes the second on-off valve 70B when determined to be completed.

As a result, the vacuum tanks TA and TB are separated from the exhaust pipe 51. In the vacuum tanks TA and TB, the pressure is reduced to a predetermined pressure by the vacuum pump 50 in the next casting cycle. Thereafter, the above steps are repeated again through processes such as mold opening and product extrusion.

According to this embodiment, the some vacuum tank TA, TB previously decompressed to predetermined pressure is prepared, the inside of cavity C is decompressed by the 1st vacuum tank TA, and the 1st vacuum tank TA As a result of equalizing the pressure between the cavity and the cavity C, by switching to the second vacuum tank TB and separating the first vacuum tank TA, it is possible to further reduce the pressure from the equal state.

In addition, by switching from the vacuum tank TA to the vacuum tank TB and separating the vacuum tank TA, the simultaneous operation of the vacuum tank TA and the vacuum tank TB (opening and closing valves 70A and 70B simultaneously) is performed. The pressure inside the cavity C can be reduced to a lower pressure than in the case of the opening.

In addition, although the case where vacuum tanks TA and TB were used was demonstrated in this embodiment, it is also possible to use many vacuum tanks.

<2nd embodiment>

5 is a cross-sectional view showing a structure around a mold of the die casting apparatus according to another embodiment of the present invention. 5, the same code | symbol is used about the same component part as the die-casting apparatus 1 which concerns on 1st Embodiment.

Although the above-mentioned stationary mold 2 and the moving mold 3 are sealed by the wax member SL, it is not possible to seal completely by this sealing member SL at the time of pressure reduction, and it is the sealing member SL. Air may leak from the gap between the mold and the die and air may enter the closed space where the pressure is reduced.

In addition, since the stationary die 2 and the movable die 3 are composed of a combination of a plurality of members, there is a possibility that air may enter the closed space where the air is decompressed through the members due to dimensional error or rattle between the members. have.

In addition, although the plunger chip 15 and the sleeve 16 are fitted, there is a possibility that air enters into the closed space where the air is decompressed from between the plunger chip 15 and the sleeve 16.

If air enters into the cavity from the gap, a high degree of vacuum cannot be obtained.

In the second embodiment, as illustrated in FIG. 5, the exhaust pipes 151 and 152 are connected between the members 2a and 2b of the stationary mold 2 and between the members 3a and 3b of the moving mold 3. have. If there is a gap between the members 2a and 2b of the stationary mold 2 or between the members 3a and 3b of the moving mold 3, this gap becomes a path through which air flows. Therefore, the exhaust gas is assisted not only from the exhaust pipe 51 opening and closing the shutoff valve 60 but also from the gap between the members 2a and 2b and between the members 3a and 3b.

In addition, an exhaust path 15h is formed in the plunger chip 15, and the exhaust air is also assisted from the gap formed between the plunger chip 15 and the sleeve 16.

As shown in Fig. 5, the exhaust pipe 51 is connected to the main tank MT through the on / off valve 170M.

In addition, the exhaust passages 15h of the exhaust pipes 151 and 152 and the plunger chip 15 are connected to the auxiliary tank STA via the on / off valve 170A.

In addition, the exhaust passages 15h of the exhaust pipes 151 and 152 and the plunger chip 15 are connected to the auxiliary tank STB via the opening / closing valve 170B.

The main tank MT and the auxiliary tanks STA and STB are respectively depressurized by predetermined pressure, for example, -100 kPa by the vacuum pump 50, respectively.

The main tank MT is one embodiment of the main vacuum tank of the present invention, and the auxiliary tank STA is one embodiment of the first auxiliary vacuum tank of the present invention, and the auxiliary tank STB is the first embodiment of the present invention. 2 is an embodiment of an auxiliary vacuum tank.

The open / close valves 170M, 170A, 170B open and close by the commands 30sM, 30sA, 30sB from the controller 30.

The exhaust pipe 51 is directly connected to the cavity C, and since the cross-sectional area of the flow path is relatively large, decompression is rapidly performed by the main tank MT. Because it is small, it is not done rapidly.                     

Next, an example of the operation of the diecast apparatus 101 having the above configuration will be described with reference to the flowchart shown in FIG.

At the time of starting casting, the plunger chip 15 is located at the initial position P ₁ which opens the supply port 16h of the sleeve 16. In this state, the cavity C is not depressurized, and the pressure in the cavity C is equal to atmospheric pressure. In addition, it is assumed that the opening / closing valve 170M of the main tank MT is opened, and the shutoff valve 60 on the mold side is closed.

In a state where the plunger chip 15 is located at the initial position P ₁ , the controller 30 outputs a command to a hot water supply device (not shown). Thereby, the molten metal which melt | dissolved metal, such as aluminum alloy and magnesium alloy, is supplied through the supply port 16h of the sleeve 16, for example (step S21).

After filling the sleeve 16 with the predetermined amount of molten metal is completed, the controller 30 drives the injection apparatus 10 and advances the plunger chip 15 at low speed (step S22).

The controller 30 determines whether the plunger chip 15 has reached the position P ₂ that closes the supply port 16h of the sleeve 16 based on the detection signal 35s of the position detection sensor 35. It judges (step S23).

When the plunger chip 15 reaches the position P ₂ which closes the supply port 16h of the sleeve 16, the closed space composed of the sleeve 16 and the cavity C is closed.

When the controller 30 determines that the plunger chip 15 has reached the position P ₂ , the controller 30 opens the on / off valve 170A of the auxiliary tank STA (step S24). Thereby, the auxiliary pressure reduction of the cavity C by the auxiliary tank STA is started.

Subsequently, the controller 30 opens the shutoff valve 60 (step S25). When the shutoff valve 60 is opened, the pressure reduction of the cavity C by the main tank MT is started.

7 shows an example of the pressure change in the cavity C. FIG.

At the time Tss at which the opening / closing valve 170A of the auxiliary tank STA is opened, the pressure in the cavity C does not change as much, but from the time Tms at which the shutoff valve 60 is opened, the pressure in the cavity C is changed. The pressure drops rapidly.

In addition, although the timing of opening / closing valve 170A of auxiliary tank STA was made just before the timing of opening cutoff valve 60, you may carry out simultaneously.

Subsequently, the controller 30 determines whether the plunger chip 15 has reached the closed position P ₃ for closing the shutoff valve 60 (step S26). This is to prevent the intrusion of the molten metal into the shutoff valve 60 by reliably closing the shutoff valve 60 before the forward speed of the plunger chip 15 switches to the high speed.

If it is determined that the controller 30 has reached the closed position P ₃ , the controller 30 closes the shutoff valve 60 (step S27). Thereby, the pressure reduction in the cavity C by the main tank MT is complete | finished.

The closed position P ₃ which closes the shutoff valve 60 is set to the position where the molten metal in the sleeve 16 is not blown into the pressure-reduced cavity C. As shown in FIG.

Immediately after closing the shut-off valve 60, the controller 30 opens the open / close valve 170B of the auxiliary tank STB to close the open / close valve 170A of the auxiliary tank STA (step S28). Thereby, the auxiliary tank which performs auxiliary pressure reduction in the cavity C switches from the auxiliary tank STA to the auxiliary tank STB.

In addition, the timing Tc for opening the on-off valve 170B shown in FIG. 7 and closing the on-off valve 170A may be just before the timing Tme for closing the shut-off valve 60.

The reason why the auxiliary tank performing auxiliary pressure reduction in the cavity C switches from the auxiliary tank STA to the auxiliary tank STB will be described.

In 2nd Embodiment, in order to prevent that the pressure in the cavity C decompressed by the main tank MT raises by the leakage of air, it is auxiliary pressure reduction by the auxiliary tank STA.

However, in order to start using the auxiliary tank STA at approximately the same time as the main tank MT, the pressure of the auxiliary tank STA is also increased at the time Tme of closing the shutoff valve 60. At the time Tme of closing the shutoff valve 60, if the difference between the pressure of the auxiliary tank STA and the pressure in the cavity C is small, after the time Tme of closing the shutoff valve 60, It becomes impossible to depressurize.

For example, in the case where only the auxiliary tank STA is used as shown in Fig. 8, the pressure is not reduced after the time Tme of closing the shutoff valve 60, so as to advance the plunger chip 15. The pressure may be increased on the contrary as the volume of the enclosed space comprising the cavity C is reduced.                     

For this reason, in this embodiment, when switching from the completion | finish of auxiliary tank STA to the unused auxiliary tank STB, since the difference between the pressure of the auxiliary tank STB and the pressure in the cavity C is large, decompression continues. Is done.

For example, by switching from the auxiliary tank STA to the auxiliary tank STB, the pressure is reduced even after the time Tme of closing the shutoff valve 60 as shown in FIG.

In addition, when the pressure is reduced to the desired pressure by the main tank MT, the molten metal in the sleeve 16 is blown into the cavity C as described above, which causes a failure of the die cast product.

Therefore, at the time of closing the shutoff valve 60, it is necessary to reduce the pressure to the pressure at which the molten metal in the sleeve 16 is not blown into the cavity C, and after closing the shutoff valve 60 to a predetermined pressure. It is necessary to reduce the pressure.

At this time, if the difference between the pressure of the auxiliary tank STA and the pressure in the cavity C is small, since the pressure is not reduced after the time Tme of closing the shutoff valve 60, the controller 30 ends use. Switch from the auxiliary tank STA to the unused auxiliary tank STB.

Since the pressure reduction by the auxiliary tank STB is not performed rapidly, the molten metal in the sleeve 16 is not blown into the cavity C. As shown in FIG.

Subsequently, the controller 30 determines whether the plunger chip 15 has reached the high speed switching position P ₄ (step S29). When it is determined that the high speed switching position P ₄ has been reached, the forward speed of the plunger chip 15 is switched at high speed (step S30). As a result, the molten metal in the sleeve 16 is injected and filled into the cavity C rapidly depressurized.

The controller 30 determines whether the plunger chip 15 has reached the boost switching position P ₅ (step S31). When it is determined that the controller 30 has reached the pressure-increasing switching position P ₆ , the controller 30 switches the injection device 10 from the speed control to the pressure control to increase the casting pressure by the plunger chip 15 (step S32).

The controller 30 determines whether the injection and filling process is completed (step S33), and closes the on / off valve 170B when determined to be complete (step S34). Thereby, the auxiliary tank STB is isolate | separated, and the inside of the main tank MT and the auxiliary tank STA, STB is equipped in the next casting cycle, and is reduced by the vacuum pump 50 to a predetermined pressure again. Thereafter, the above steps are repeated again through processes such as mold opening and product extrusion.

As described above, according to the present embodiment, when the pressure inside the cavity is depressurized, the auxiliary tank is exhausted from the path where air easily enters, and further depressurization after closing the shutoff valve 60 by the auxiliary tank is performed. By doing so, it is possible to prevent the molten metal from being sucked into the cavity C before injecting and filling the molten metal into the cavity C. That is, since the path cross section area where air easily penetrates is small, the abrupt exhaustion is not performed, so that the molten metal is not sucked into the cavity C.

In addition, the pressure reduction after closing the shutoff valve 60 can be reliably performed by switching the auxiliary tank from the finished use to the unused one during the casting step.

In addition, by using the main tank and the plurality of auxiliary tanks together and switching the auxiliary tanks from the unused ones to the unused ones, a higher degree of vacuum can be obtained than when the main tank and the plurality of auxiliary tanks are used simultaneously.

In addition, in embodiment mentioned above, on-off valve 70A, 70B and on-off valve 170A, 170B are respectively controlled independently. Therefore, with respect to the timing for closing the on-off valves 70A and 170A, the timing for opening the on-off valves 70B and 170B can be appropriately and freely changed, and the operation for closing the on-off valves 70A and 170A and the on / off valve ( The operations for opening the 70B and 170B may overlap.

According to the present invention, it is possible to provide a die casting apparatus and a casting method capable of shortening the time required for decompression when injecting and filling a metal bath by depressurizing the inside of the cavity and reducing the pressure to a lower pressure.

Claims (7)

It is a die-casting apparatus which exhausts the inside of the cavity formed with a metal mold | die, and depressurizes it, and injects and fills the molten metal in the pressure-reduced cavity, and shape | molds a casting product, A plurality of vacuum tanks connected to a depressurized closed space including the cavity and depressurized in advance; A plurality of opening and closing means for opening and closing a connection path between the plurality of vacuum tanks and the closed space, respectively; Control means, The control means depressurizes the closed space using a part of the plurality of vacuum tanks, and then closes the connection path between the part of the plurality of vacuum tanks and the closed space. And a die-casting device for further depressurizing by opening a connection path between the vacuum tank different from the vacuum tank and the decompressed closed space. It is a die-casting apparatus which exhausts the inside of the cavity formed with a metal mold | die, and depressurizes it, and injects and fills the molten metal in the pressure-reduced cavity, and shape | molds a casting product, A plurality of vacuum tanks connected to a depressurized closed space including the cavity and depressurized in advance; A plurality of opening and closing means for opening and closing a connection path between the plurality of vacuum tanks and the closed space, respectively; Have control means, The control means, after depressurizing the closed space using a part of the plurality of vacuum tanks, closes the opening and closing means provided in the connection path between the partial vacuum tank and the closed space, and the plurality of vacuums. A die-casting apparatus for performing further depressurization by performing an operation of opening and closing the opening and closing means provided in a connection path between a vacuum tank different from the partial vacuum tank of the tank and the decompressed closed space. The said plurality of vacuum tanks of Claim 1 or 2, A main vacuum tank connected to an exhaust path provided in the mold and for depressurizing a closed space including the cavity; It has a 1st and 2nd auxiliary vacuum tank connected to the leakage path | route of the air of the said closed space other than the said exhaust path, and auxiliary-pressure-reducing the closed space containing the said cavity, And the control means further reduces the closed space using the main vacuum tank and the first auxiliary vacuum tank, and further reduces the pressure using the second auxiliary vacuum tank. The die casting apparatus according to claim 3, wherein the first and second auxiliary vacuum tanks are connected to the plunger chip and the mold of an injection apparatus for injecting and filling the molten metal into the cavity. 4. The die-casting apparatus according to claim 3, wherein the control means controls to inject and fill the molten metal into the cavity while the exhausting by the second auxiliary vacuum tank is continued. It is a casting method for forming a casting by exhausting the inside of the cavity formed by the mold to reduce the pressure, by injection and filling the molten metal in the reduced pressure cavity, A first decompression step connected to a decompressed closed space including the cavity and depressurized using a part of a plurality of vacuum tanks previously decompressed; A second depressurizing step of further depressurizing the closed space depressurized by another vacuum tank of the plurality of vacuum tanks, And a filling step of injecting and filling a molten metal into the cavity decompressed by the other vacuum tank. The method of claim 6, wherein the plurality of vacuum tanks, A main vacuum tank connected to an exhaust path provided in the mold; It has a 1st and 2nd auxiliary vacuum tank connected to the leakage path | route of the air of the said closed space other than the said exhaust path, In the first depressurization step, after the pressure reduction of the closed space is performed using the main vacuum tank and the first auxiliary tank, the shutoff valve provided in the exhaust passage is closed, The casting method according to the second depressurization step, wherein the closed space is further reduced in pressure using the second auxiliary vacuum tank.

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