JP2001047209A - Casting machine for die casting and casting method for die casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain increase in cost of a vacuum device while preventing the extension of the casting cycle of a die casting formed product, in the case of obtaining the vacuum state for sucking powdery releasing agent by evacuating in a cavity and the vacuum state for preventing the entrapment of the air into molten metal. SOLUTION: A die casting machine is provided with a vacuum tank 26 and a vacuum pump 27 for evacuating the cavity 40 in a die to a first vacuum degree and a vacuum tank 21 and a vacuum pump 22 for evacuating from a second vacuum degree at higher than the first vacuum degree. In such a way, since the first vacuum, degree and the second vacuum degree are obtained with the vacuum devices separately and independently arranged, the extension of the casting cycle can be prevented. Further, corresponding to the respective necessary vacuum degrees, the vacuum tank 26 is formed to have the smaller capacity than the vacuum tank 21. In this way, even two vacuum devices are separately and independently arranged, the increase in cost thereof can be restrained as low as possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die casting machine and a die casting method using a powder release agent as a release agent for facilitating removal of a die cast product from a mold.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 62-12271 discloses a die casting machine for performing die casting using a powder release agent.
No. 50 is shown. In this die casting casting machine, a mold including a fixed mold and a movable mold is clamped, and after the mold is clamped, air is exhausted from an exhaust port communicating with the mold cavity to reduce the pressure in the mold cavity. A mold release agent such as a powder mold release agent is supplied into the mold cavity through the coating and applied.

[0003] The use of a powder release agent has various advantages over the use of a liquid release agent. For example, in a liquid release agent, since a large amount of pyrolysis gas is generated when heated by a molten metal, a relatively large number of cavities are generated in a die-cast molded product, but in a powder release agent,
The occurrence of such nests can be reduced. In addition, as a method of applying a liquid release agent, spraying on a mold surface by air blowing is generally performed. However, in this method, mist and noise are generated, and the working environment is deteriorated. further,
When a liquid release agent is sprayed, the temperature of the mold heated by the molten metal sharply decreases, so that the temperature change width of the mold in one cycle in die casting becomes large. As a result, the life of the mold is reduced, and hair cracks and the like occur relatively early.

[0004] On the other hand, by using a powder release agent as in the above-described conventional example and applying the release agent after clamping, the scattering of the release agent outside the mold is reduced. As a result,
The release agent can be efficiently applied, and the working environment can be prevented from deteriorating. Further, since the temperature change width of the mold in the casting cycle can be reduced, the life of the mold can be improved.

[0005]

Here, when performing die casting, the cavity may be preliminarily depressurized to a high vacuum state in order to prevent the formation of nests due to the entrainment of air. As the degree of vacuum at this time, since it is necessary to sufficiently exhaust air, it is desired that the air be evacuated to a degree of vacuum of, for example, about 20 to 50 Torr.

On the other hand, as described above, it has been confirmed by the present inventor that when the powder release agent is sucked into the cavity, it is not necessary to maintain the high vacuum as described above. In other words, the powder release agent needs to be sucked into the cavity and stay there, whereas if the powder release agent is sucked at an excessively high vacuum, the powder passes through the cavity and reaches the vacuum device. The release agent increases. The degree of vacuum required to suck the powder release agent into the cavity is, for example, 700 to 750 Torr.

Here, the vacuum device for reducing the pressure in the cavity to a vacuum state is usually constituted by a vacuum tank and a vacuum pump. This is because attempting to depressurize the inside of the cavity directly with a vacuum pump requires the use of a very high capacity vacuum pump, which increases the cost of the apparatus. For this reason, a vacuum pump and a vacuum tank are combined, and the vacuum tank is gradually depressurized by the vacuum pump. Then, in a state where the degree of vacuum in the vacuum tank is a desired degree of vacuum, the vacuum tank is communicated with the cavity and the inside of the cavity is evacuated. Using such a vacuum device, when trying to obtain both the degree of vacuum for sucking the powder release agent and the degree of vacuum for exhausting air when injecting the molten metal, the following is obtained. Problems arise.

That is, once the vacuum tank is communicated with the cavity, the degree of vacuum in the vacuum tank is greatly reduced. Therefore, after the vacuum tank is connected to the cavity for sucking the powder release agent, it takes a considerable time until the degree of vacuum in the vacuum tank reaches the degree of vacuum for exhausting the cavity. As a result, the casting cycle of the die-cast molded product is lengthened, and the productivity is reduced.

On the other hand, if it is attempted to address the above problem by increasing the capacity of the vacuum device (increase the capacity of the vacuum tank and improve the vacuum pumping capability of the vacuum pump), the cost of the vacuum device will be greatly increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a vacuum state for suctioning a powder release agent by evacuating the inside of a cavity and a vacuum state for preventing entrainment of molten metal in air. It is an object of the present invention to provide a die-casting machine and a die-casting method capable of minimizing an increase in the cost of a vacuum apparatus while preventing the elongation of the casting cycle of a die-cast molded product even when obtaining a die-casting product.

[0011]

According to a first aspect of the present invention, there is provided a die casting caster having a fixed mold and a movable mold, wherein a mold is formed by clamping the fixed mold and the movable mold. And a powder release agent supply means for supplying a powder release agent into the cavity, and an exhaust port of the cavity and a first evacuation passage connected to each other. A first evacuation unit for evacuating to a degree of vacuum and sucking a powder release agent supplied from the powder release agent supply unit into the cavity; an exhaust port of the cavity; After a powder release agent is applied to the surface of the cavity, the predetermined second degree of vacuum is higher than the first degree of vacuum inside the cavity after being connected through a vacuum passage. Second evacuation means for evacuation to When in the cavity by the second vacuum means is evacuated to the second degree of vacuum of a predetermined, characterized in that it comprises a molten metal supply means for supplying a molten metal into the cavity.

As described above, the first degree of vacuum for sucking the powder release agent is achieved by the first vacuuming means.
The second degree of vacuum for exhausting the air in the cavity to prevent the entrainment of air into the molten metal is achieved by the second vacuuming means. That is, the first degree of vacuum and the second degree of vacuum are formed by the first and second vacuum means provided separately and independently.
There is no need to set a waiting time for obtaining a predetermined degree of vacuum. Thereby, the extension of the casting cycle can be prevented.

Further, in the present invention, a first degree of vacuum for sucking the powder release agent and a second degree of vacuum for exhausting air in the cavity to prevent entrainment of air into the molten metal. We focused on the difference between the levels. That is, as described above, when the powder release agent is sucked into the cavity, it is not necessary to establish a high vacuum as in preventing the entrainment of air into the molten metal. In this case, the first evacuation unit was set to generate a lower evacuation degree than the second evacuation unit, corresponding to each required degree of vacuum. Thus, while providing two independent and independent evacuation means, it is possible to suppress an increase in cost for this purpose as much as possible.

According to a second aspect of the present invention, the first vacuuming means includes a first vacuum tank, a first vacuum pump for vacuuming the first vacuum tank, and a first vacuum pump. A first opening / closing unit which is arranged on the upstream side of the first vacuum tank in the vacuum evacuation passage and switches communication / non-communication between the cavity and the first vacuum tank by opening / closing the first vacuum evacuation passage; Means, wherein the second vacuuming means comprises a second vacuum tank, a second vacuum pump for vacuuming the second vacuum tank, and the second vacuum pump in the second vacuuming passage. A second opening / closing means disposed upstream of the vacuum tank and switching communication / non-communication between the cavity and the second vacuum tank by opening / closing the second evacuation passage; Opening and closing means When it is opened, the second
The opening and closing means is closed, and the first opening and closing means is closed when the second opening and closing means is opened.

As described above, by selectively opening the first and second opening / closing means, the degree of vacuum in the cavity is reduced to the first degree of vacuum for sucking the powder release agent. The second degree of vacuum can be easily and accurately set to exhaust air in the cavity so as to prevent air from getting into the metal melt.

In a third aspect of the present invention, the second vacuum pump has a larger capacity than the first vacuum pump.

That is, the capacity of the second vacuum pump is made larger than the capacity of the first vacuum pump in consideration of the level of the degree of vacuum required for each.

According to a fourth aspect of the present invention, there is provided a die casting caster, wherein the filter opening is disposed between the first opening / closing means and the first vacuum tank and has a diameter smaller than at least an average particle diameter of the powder release agent. A first filter having:
Disposed between the opening / closing means and the second vacuum tank,
A second filter having a filtration diameter smaller than at least the average particle diameter of the powder release agent.

As described above, since the first and second filters having a filter diameter smaller than the average particle diameter of the powder release agent are provided, the corresponding opening / closing means is opened, and the first or second filter is opened. Most of the excess powder release agent remains in the first or second vacuum tank even when the vacuum
Captured by the filter. For this reason, since the powder release agent can be almost prevented from reaching the first or second vacuum tank, it is possible to prevent problems such as a failure in obtaining a desired degree of vacuum.

The filter diameters of the first and second filters are preferably set smaller than the minimum particle size of the powder release agent. This makes it possible to almost completely prevent the powder release agent from reaching the first and second vacuum tanks. Note that the first and second filters are periodically replaced.

According to a sixth aspect of the present invention, in the die casting caster, a third filter having a larger filter diameter than the first filter is provided between the cavity of the first vacuum passage and the first opening / closing means. And a fourth filter having a larger filter diameter than the second filter is provided between the cavity of the second evacuation passage and the second opening / closing means. I do.

The third and fourth filters capture relatively large foreign matter, such as burrs of a die-cast product. For this reason, the first due to the intrusion of a relatively large foreign matter,
And malfunction of the second opening / closing means can be prevented,
It is possible to extend the life of the first and second filters.

According to a seventh aspect of the present invention, the first and second opening / closing means are each constituted by an electromagnetic valve, and a sliding portion connected to the valve body when the valve body is opened. The valve body is shielded from the first or second evacuation path.

If the sliding portion of the electromagnetic valve constituting the first or second opening / closing means is in the state of being exposed to the first or second vacuum passage when the valve is opened, the powder release agent may be used. It may adhere to the sliding part and cause sliding failure of the sliding part. On the other hand, as described in claim 7, when the valve body is opened such that the sliding portion connected to the valve body is shielded from the vacuum passage by the valve body,
Malfunction of the solenoid valve can be prevented beforehand.

In the die casting machine according to the present invention, the metal melt supply means may include a sleeve for introducing the metal melt into the cavity, and a metal when the metal melt is supplied to the sleeve. A plunger for injecting the molten metal into the cavity; and a lubricant supply means for supplying a lubricant for the plunger sliding in the sleeve. The powder release agent supply means comprises: It is intended to supply a powder release agent into the lubricant supply means, after the powder release agent supply means completes the supply of the powder release agent, the lubricant into the sleeve It is characterized by supplying.

As described above, the powder release agent supply means
When the powder release agent is supplied into the cavity through the sleeve, as described above, the lubricant supplied into the sleeve may cause the powder release agent to be deposited in the sleeve. . For this reason, in the above-mentioned die casting casting machine, the lubricant supply means supplies the lubricant into the sleeve after the powder release agent supply means completes the supply of the powder release agent via the sleeve. .

Thus, the powder release agent can be supplied into the cavity through the sleeve while the inside of the sleeve is dry, so that the powder release agent is prevented from being deposited in the sleeve. .

In the die casting machine according to the ninth aspect, when the powder release agent supply means supplies the powder release agent, the surface temperature of the mold is reduced to 300 ° C. or less. And a cooling mechanism.

Experiments by the present inventors have confirmed that when the temperature of the mold release agent is as high as 300 ° C. or higher, the adhesion of the mold to the cavity surface is reduced. For this reason, a cooling mechanism is provided in the die casting machine as described above, and when the powder release agent is supplied, the mold temperature is set to 300 ° C.
It is preferable that it is reduced to the following.

According to a tenth aspect of the present invention, the cooling mechanism may be constituted by a cooling pipe formed in the mold and through which cold water passes. In this case, the cooling pipe is provided so that the temperature of the cavity surface of the mold can be reduced to 300 ° C. or less by the time the powder release agent is supplied after removing the die-cast molded product from the mold. The number and the installation position are set.

[0031] Claim 11 defines a die casting method.

That is, a die casting method in which a molten metal is supplied from a sleeve into a cavity formed by clamping a fixed die and a movable die, and die casting is performed. A first step of evacuating the inside of the cavity to a predetermined first degree of vacuum, and using the first degree of vacuum to suck the powder release agent supplied through the sleeve into the cavity; A second step, and a second vacuuming means provided separately from the first vacuuming means, so that the inside of the cavity has a predetermined second degree of vacuum higher than the predetermined first degree of vacuum. A third step of evacuating the metal melt to a degree of vacuum, and the cavity of the metal melt supplied to the sleeve is evacuated to the second degree of vacuum by a plunger sliding in the sleeve. 5 to take out the fourth step of injection, a metal casting which solidified in the cavity to
And a step of:

According to the above-described die casting method, it is possible to prevent the cost of the casting machine from increasing as much as possible and to prevent the casting cycle from being elongated.

In the die casting method according to a twelfth aspect, after the powder release agent is sucked into the cavity and before the molten metal is supplied to the sleeve, the inside of the sleeve is removed. A lubricant supply step of supplying a lubricant for the sliding plunger to the sleeve.

According to the above method, the accumulation of the powder release agent in the sleeve can be effectively prevented.

[0036]

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

FIG. 1 shows a die casting machine as an embodiment of the present invention.

As shown in FIG. 1, the mold is a movable mold 1
And a fixed mold 7. The fixed mold 7 includes a fixed matrix 9 and a fixed mold insert 10, and the fixed mold insert 10 is fixed to the fixed matrix 9 with bolts or the like. And they are attached to the fixed platen 8 of the die casting machine.
The movable mold 1 includes a movable matrix 4 and a movable mold insert 5. The movable mold insert 5 forming the cavity 40 between the movable mold 1 and the fixed mold insert 10 is fixed to the movable mold 4 with bolts or the like. . And
They are mounted on a movable platen 2 of a die casting machine via a die base 3.

One end of the cavity 40 is connected to the sleeve 13 fixed to the fixed matrix 9 and the fixed platen 8.
A powder release agent supply port 14 and a molten metal supply port 15 are formed in the upper part of the sleeve 13, and the powder release agent and the molten metal are supplied into the cavity 40 through the sleeve 13. Note that a chip lubricant is also supplied from the molten metal inlet 15 as described later. The other end of the cavity 40
The exhaust passage 12 is connected to an exhaust passage 17 for reducing the pressure in the cavity 40.

The cut-off pin 6 is provided so that the connection between the exhaust passage 12 and the cavity 40 can be opened and closed. The cut-off pin 6 switches the connection between the exhaust passage 12 and the cavity 40 by using a hydraulic pressure from a hydraulic supply source (not shown).

A passage 11 is formed so as to branch off from the slide passage of the cut-off pin 6.
Is connected to a pressure gauge 28 by a hose. The pressure gauge 28 is for detecting whether or not the degree of vacuum in the cavity 40 has reached a predetermined degree of vacuum when the molten metal is supplied into the cavity 40. An opening / closing valve 29 is provided in front of the pressure gauge 28 to prevent the powder release agent from reaching the pressure gauge 28 when the powder release agent is supplied.

Two exhaust systems are connected to the exhaust passage 12 of the cavity 40 via a vacuum passage 17. The first system is mainly a vacuum tank 2
1 and a vacuum pump 22, and a predetermined degree of vacuum (−20 mmHg or 700 to 750 Torr) is applied to the inside of the cavity 40 in order to suck the powder release agent into the cavity 40.
Vacuum to r). The capacity of the vacuum tank 21 is set to, for example, 100 L. The second evacuation mechanism mainly includes a vacuum tank 26 and a vacuum pump 27,
The cavity 40 is evacuated to a predetermined high degree of vacuum (60 Torr or less) in order to prevent the formation of nests due to air entrainment during the formation of the die cast molded product. The capacity of the vacuum tank 26 is set to, for example, 400 L, and a vacuum pump 27 having a higher capacity than the vacuum pump 22 is used.

In these first and second evacuation mechanisms,
The vacuum pumps 22 and 27 evacuate the respective vacuum tanks 21 and 26 so that the predetermined degree of vacuum is obtained in each cycle of die casting. Then, the evacuated vacuum tanks 21 and 26 are placed in the cavity 40.
By connecting to the above, the respective degrees of vacuum are obtained. The vacuum tank 21 and the vacuum tank 26 are connected to the cavity 40 at different timings.

In order to control the connection and disconnection between the cavity 40 and the vacuum tanks 21 and 26, solenoid valves 19 and 24 are arranged in the evacuation passage 17 upstream of the vacuum tanks 21 and 26, respectively.

FIG. 2 shows a schematic configuration of the solenoid valve 19.
The solenoid valve 24 has the same configuration as the solenoid valve 19. In the solenoid valve 19, a substantially cylindrical space is formed in a housing 44, and a sliding portion 45 is slidably provided in this space. The valve element 41 is connected to the tip of the sliding section 45, and the valve element 41 moves inside the housing 44 integrally with the sliding section 45. As shown in FIG. 2, a passage 43 forming a part of the evacuation passage 17 is formed in the housing 44. Further, although not shown, a spring for urging the sliding portion 45 downward in FIG. 2 and a sliding portion 4 when energized are provided in the housing 44.
A solenoid for sucking the sliding portion 45 is provided so that 5 moves upward.

FIG. 2 shows the solenoid valve 19 in the open state. In this open state, the solenoid is energized and the sliding portion 4
5 is achieved by moving upward. As shown in FIG. 2, when the solenoid valve 19 is open, only the valve element 41 is exposed to the passage 43, and the sliding portion 45 is
3 is shielded by a valve element 41. Therefore, even when the surplus powder release agent flows toward the vacuum tank 21, the powder release agent is prevented from adhering to the outer peripheral surface of the sliding portion 45. This can prevent the powder release agent from causing sliding failure of the sliding portion 45, so that the opening and closing operation of the solenoid valve 19 can be reliably performed.

Bag filters 20 and 25 are arranged between the solenoid valve 19 and the vacuum tank 21 and between the solenoid valve 24 and the vacuum tank 26, respectively. FIG. 3 is a partially sectional perspective view showing a schematic configuration of the bag filter 20. Note that the bag filter 25 has a similar configuration.

As shown in FIG. 3, a bag-shaped filter element 52 is provided in a housing 50 having an intake port 51 and an exhaust port 53. In the bag filter 20, as shown by a solid line arrow, the airflow containing the powder release agent introduced from the intake port 51 is filtered through the entire surface of the bag-shaped filter element 52 and then discharged from the exhaust port 53. Is done. Thus, the bag filter 25
Has a large filtration area, so that a reduction in the vacuum suction effect by the vacuum tank 21 can be suppressed.

The filter diameter (mesh size) of the filter element 52 is set to 3 μm. This means that the average particle size of the powder release agent is 8 μm, the minimum particle size is 4 μm,
Taking into account that the maximum particle size is 12 μm.
That is, if the filter diameter of the filter element 52 is smaller than the minimum particle size of the powder release agent, the powder release agent can be almost completely captured by the bag filter 20, so that such a relationship is established. Filter element 5
The filter diameter of 2 was selected.

FIG. 4 is a graph showing the relationship between the filter diameter of the filter element 52 and the number of failures per month of the vacuum apparatus including the vacuum tank 21 and the vacuum pump 22. When the bag filter 20 was not used, the vacuum device failed three times per month. However, it was confirmed that the number of failures was reduced as the bag filter 20 was provided and the filter diameter was reduced. In particular, when the filter diameter of the filter element 52 was 5 μm or less, no failure of the vacuum device occurred. Therefore, the filter element 52
The filter diameter can be sufficiently effective even if it is not smaller than the minimum particle size of the powder release agent, and it can be practically used if it is at least smaller than the average particle size (8 μm) of the powder release agent. I understand.

On the upstream side of the solenoid valves 19 and 24, filters 18 and 23 having a relatively large filtration aperture are provided. Specifically, filters having a filter diameter of 50 to 300 μm are used as the filters 18 and 23. These filters 18 and 23 are provided for capturing relatively large foreign matters such as burrs of a die-cast product. By the action of these filters 18 and 23, one of the electromagnetic valves due to the intrusion of relatively large foreign matter is reduced.
In addition to preventing malfunctions of the bag filters 9, 24, the life of the bag filters 20, 25 can be extended.

The die casting machine according to this embodiment further includes a powder supply device 30. This powder supply device 30
Has a metering / discharging section 31, which measures the amount of powder release agent to be supplied at one time and discharges it toward the powder release agent supply port 14. Further, a positive pressure supply source 34 is connected to the metering / discharging section 31 via an electromagnetic valve 33. Measuring discharge section 3
After the discharge of the predetermined amount of the powder release agent is completed, 1 applies a positive pressure from the positive pressure supply source 34 into the cavity 40. Thereby, uniform application of the powder release agent to the entire surface of the cavity 40 is achieved. That is, when a positive pressure is applied to the cavity 40 in a state in which the powder mold release agent is filled in the cavity 40, even if the cavity 40 has a complicated shape, the powder mold release agent is almost uniformly formed. The agent can be applied over the entire surface of the cavity 40.

The operation of the powder supply device 30 is controlled by the control panel 3
5. That is, the control panel 35 controls the operation of the metering and discharging unit 31 in the powder supply device 30 and the operation of the electromagnetic valve 3.
3 is controlled to open and close. The control panel 35 is provided with a vacuum gauge 36. The pressure in the cavity 40 is introduced into the vacuum gauge 36 via the powder supply device 30 to measure the degree of vacuum in the cavity 40. In particular, the vacuum gauge 36 is used to measure the degree of vacuum in the cavity 40 when the powder release agent is supplied.

Further, a control panel 38 for controlling the operation of the entire die casting machine is provided. That is,
The control panel 38 is provided with solenoid valves 19 and 24 in the vacuuming mechanism.
, The opening / closing operation of the cut-off pin 6 and the opening / closing valve 29, the position control of the plunger 16, the mold opening of the movable platen 2, the mold clamping operation, and the like.

Hereinafter, the control contents of the control panel 35 and the control panel 38 will be described together with the operation of the die casting machine. The main operating states of the die casting machine are shown in FIGS.
This is shown in FIG.

FIG. 5 is a flowchart showing the control contents of these control panels 35 and 38. The control panel 38 for controlling the die casting machine and the control panel 35 for controlling the device 30 for supplying the powder release agent exchange data on the control state by communication with each other.

First, in step 100, the movable mold 1
And the fixed mold 7 are clamped. Next, in step 110, the plunger 16 is advanced to a position at which the molten metal inlet 15 is closed. Then, in step 120, the electromagnetic valve 19 is opened to start reducing the pressure in the cavity 40.

The fact that the electromagnetic valve 19 has been opened is transmitted to the control panel 35 on the side of the powder supply device, and the control panel 35 enters the powder into the cavity 40 after the electromagnetic valve 19 is closed in step 130. When the time (several seconds) for obtaining the degree of vacuum necessary for sucking the release agent has elapsed, the degree of vacuum is measured by the vacuum gauge 36. At this time, if the degree of vacuum measured by the vacuum gauge 36 does not fall within the predetermined range (−20 mmHg or 700 Torr−750 Torr), it is determined that an abnormality of the vacuum device or the like has occurred, and the die casting machine is stopped (step 160). . On the other hand, when the measured degree of vacuum is within a predetermined range, in step 140, a predetermined amount of the powder release agent is discharged from the metering / discharging unit 31, and the powder release agent supply port 14, the sleeve 13 into the cavity 40 (FIG. 7).
(A)).

Next, at step 150, the degree of vacuum in the cavity 40 is measured again, and it is determined whether or not the measured degree of vacuum is within a predetermined range. Since the electromagnetic valve 19 is kept open from the start to the end of the supply of the powder release agent, if the powder release agent is normally supplied into the cavity 40, the supply of the powder release agent at the end of the supply is stopped. The degree of vacuum is a predetermined vacuum degree range (35 degrees higher than the degree of vacuum at the start of supply).
0 Torr to 450 Torr). That is, when the degree of vacuum in the cavity 40 is outside the above range at the end of the supply, it can be assumed that an abnormality such as clogging in the supply path of the powder release agent has occurred. Therefore, when it is determined that the degree of vacuum measured in step 150 is out of the predetermined range, the die casting machine is stopped in step 160.
On the other hand, when the measured degree of vacuum is within the predetermined range, the electromagnetic valve 33 is opened in step 180. Thus, a positive pressure is applied from the positive pressure supply source 34 into the cavity 40 via the electromagnetic valve 33, and the powder release agent filled in the cavity 40 is applied substantially uniformly over the entire surface of the cavity 40. You.

At this time, in synchronization with the opening of the solenoid valve 33,
In the control panel 38 of the die casting machine, the opening and closing valve 29
And the solenoid valve 19 is closed.

The reason why the opening / closing valve 29 is closed is that excess powder releasing agent is discharged from the cavity 40 and the pressure gauge 2
This is to prevent the number from reaching 8. In this case, the surplus powder release agent stays in the hose connecting the passage 11 and the opening / closing valve 29, but this hose is replaced periodically, and the vacuum by the pressure gauge 28 is changed. There is no effect on the degree measurement. Further, by closing the solenoid valve 19, the degree of vacuum of the vacuum tank 21 is prevented from lowering.

Next, in step 190, it is determined whether or not a predetermined time has elapsed.
In step 200, the solenoid valve 33 is closed, and the application of the positive pressure ends. In addition, regarding the level and time of the positive pressure applied at this time, a positive pressure of, for example, about ² to 8 kg / cm ^{2 is} applied for several seconds.

The fact that the solenoid valve 33 has been closed is transmitted to the control panel 38 on the die casting machine side. And the control panel 38
In step 210, the plunger 16 is retracted, and the molten metal feed port 15 is opened. In this state, the tip lubricant is injected from the molten metal supply port 15 through the tip lubricant nozzle 39 (see FIG. 7B). This tip lubricant is
For smooth sliding of the plunger 16, for example, trade name Graface P1200N (Hanano Shoji) can be used. This tip lubricant is liquid and has viscosity. Accordingly, if the powder release agent is supplied from the powder release agent supply port 14 after the tip lubricant is supplied to the sleeve 13, the powder release agent adheres to the chip lubricant and is Aggregate.
Then, when the molten metal is injected from the sleeve 13 into the cavity 40, the powder release agent agglomerated together with the molten metal is also extruded into the cavity 40 and mixed into the die-cast molded product. This is a factor that significantly reduces the quality of the die cast product.

For this reason, in this embodiment, the powder release agent is sucked into the cavity 40 before the tip lubricant is supplied to the sleeve 13. As a result, when the powder release agent is first supplied into the cavity 40 as compared with the powder residual amount in the sleeve when the tip lubricant is supplied to the sleeve 13 first, The difference could be reduced to about 1/8.

After the tip lubricant is supplied, the ladle 60
As a result, the molten metal is injected into the sleeve 13 from the molten metal inlet 15 (see FIG. 7C). And step 22
At 0, the plunger 16 is advanced to a position where the molten metal feed port 15 is closed to make the inside of the sleeve airtight.

In this state, the solenoid valve 24 is opened and the on-off valve 29 is opened. Thereby, the cavity 4
The inside of 0 is evacuated to a predetermined high vacuum degree (60 Torr or less), and the vacuum degree can be measured by the vacuum gauge 28. After the solenoid valve 24 is opened, when the time required to obtain the predetermined high vacuum degree elapses, the vacuum gauge 28
To measure the degree of vacuum in the cavity 40. At this time, if the measured degree of vacuum does not reach the predetermined high degree of vacuum, the casting machine is regarded as having some abnormality, and abnormally stopped (step 250). On the other hand, if the measured degree of vacuum has reached the predetermined high degree of vacuum, in step 260, the cutoff pin 6 is moved to a position at which the connection between the cavity 40 and the exhaust passage 12 is closed.
Is closed. This prevents the molten metal injected into the cavity 40 from flowing out to the exhaust passage 12 and the like.

In step 270, the plunger 16 is advanced at a high speed so that the molten metal is injected from the sleeve 13 into the cavity 40 (see FIG. 7D). Thereafter, the plunger 16 is retracted to the initial position at the timing when the molten metal in the cavity 40 solidifies.

In step 280, the movable mold 1 is moved to open the mold, and the formed die-cast product is taken out of the mold.

A die-cast molded article is formed by the above-described series of procedures, and the series of procedures is repeatedly executed.

Here, when the above-described series of procedures is repeatedly performed, the temperature of the molten metal is about 700 ° C., so that the die temperature at the time of removing the die-cast molded product is about 40 ° C.
The temperature of the mold becomes 0 ° C. to 500 ° C., and the temperature of the mold is maintained at a high temperature even when the process proceeds to the next casting cycle.

However, as a result of the study of the present inventors, it is clear that the powder release agent in the present embodiment has a lower adhesion to the mold at a high temperature such as a mold temperature exceeding 300 ° C. It became. Therefore, although not shown, a plurality of cooling pipes are formed inside the movable mold 1 and the fixed mold 7 in the same manner as the conventional mold, and the mold is cooled by flowing cold water through the cooling pipes. are doing.

Here, the surface of the cavity 40 of the mold to which the powder release agent is attached is a portion heated to the highest temperature by the molten metal. For this reason, in the present embodiment, the number of the plurality of cooling pipes and the forming position are set such that the temperature of the surface of the cavity 40 has a cooling capacity that can be reduced to 300 ° C. or less by the time the powder release agent is supplied. Has been determined. This has made it possible to prevent a decrease in the adhesion of the powder release agent.

The powder release agent used in the present embodiment is a mixture of talc 80% and wax 20%. Further, as the molten metal, a molten aluminum or a molten magnesium is used.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a die casting machine according to an embodiment of the present invention.

FIG. 2 is a view showing a schematic structure of a solenoid valve used in a vacuuming mechanism of the die casting machine of FIG. 1;

FIG. 3 is a partially cutaway perspective view showing the structure of a bag filter.

FIG. 4 is a graph showing a relationship between the filter diameter of the filter element of the bag filter and the number of failures per month of the vacuum device.

FIG. 5 is a flowchart showing a first half of control contents of control panels 35 and 38;

FIG. 6 is a flowchart showing the latter half of the control contents of the control panels 35 and 38.

FIG. 7 is an operation explanatory view showing main operation steps of the die casting machine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Movable type, 7 ... Fixed type, 15 ... Metal hot water supply port 18 ... Filter (3rd filter), 19 ... Solenoid valve (1st opening / closing means), 20 ... Bag filter (1st filter), 21 ... Vacuum tank (first vacuum tank), 23 ...
Filter (fourth filter) 24 ... solenoid valve (second opening / closing means), 25 ... bag filter (second filter) 26 ... vacuum tank (second vacuum tank), 30 ... powder supply device

Claims (12)

[Claims] 1. A mold having a fixed mold and a movable mold, wherein a mold is formed by clamping the fixed mold and the movable mold, and a powder release agent is supplied into the cavity. A powder release agent supply unit is connected to the cavity via a first vacuum passage, and the inside of the cavity is evacuated to a predetermined first vacuum degree and supplied from the powder release agent supply unit. First vacuuming means for sucking the powder release agent to be sucked into the cavity, and the cavity is connected to the cavity via a second vacuum passage, and the surface of the cavity is coated with the powder release agent. Then, the inside of the cavity is evacuated to a second predetermined degree of vacuum higher than the first degree of vacuum.
And a metal melt supply means for supplying a metal melt into the cavity when the inside of the cavity is evacuated to a predetermined second degree of vacuum by the second vacuum suction means. Die casting machine characterized. 2. The die casting machine according to claim 1, wherein the first vacuuming means includes: a first vacuum tank; a first vacuum pump for vacuuming the first vacuum tank; A first vacuum pumping passage disposed upstream of the first vacuum tank and opening and closing the first vacuum pumping passage to switch between communication and non-communication between the cavity and the first vacuum tank; Opening / closing means, wherein the second vacuuming means comprises: a second vacuum tank; a second vacuum pump for vacuuming the second vacuum tank; A second opening / closing means disposed upstream of the second vacuum tank and switching communication / non-communication between the cavity and the second vacuum tank by opening / closing the second evacuation passage; No. Wherein the second opening / closing means is closed when the second opening / closing means is opened, and the first opening / closing means is closed when the second opening / closing means is opened. Casting machine. 3. The die casting machine according to claim 2, wherein said second vacuum pump has a larger capacity than said first vacuum pump. 4. The die casting machine according to claim 2, wherein the filter is disposed between the first opening / closing means and the first vacuum tank and is smaller than at least an average particle diameter of the powder release agent. A first filter having a diameter;
Disposed between the opening / closing means and the second vacuum tank,
A second filter having at least a filter diameter smaller than an average particle diameter of the powder release agent. 5. The die casting machine according to claim 4, wherein the filter diameters of the first and second filters are set smaller than a minimum particle size of the powder release agent. Die casting machine. 6. A die casting machine according to claim 4, wherein a filter larger than said first filter is provided between said cavity of said first vacuum passage and said first opening / closing means. A third filter having a diameter is provided, and a fourth filter having a larger filter diameter than the second filter is provided between the cavity of the second evacuation passage and the second opening / closing means. Die casting machine. 7. A die casting machine according to claim 2, wherein said first and second opening / closing means are each constituted by a solenoid valve, and said valve body is opened when said valve body is opened. A die casting machine, wherein a sliding portion connected to the first member is shielded from the first or second evacuation path by the valve body. 8. The die casting machine according to claim 1, wherein the molten metal supply means includes a sleeve for introducing the molten metal into the cavity, and a metal molten metal on the sleeve. A plunger for injecting the molten metal into the cavity when supplied, and a lubricant supply means for supplying a lubricant for the plunger sliding in the sleeve, wherein the powder release agent supply means Is for supplying a powder release agent into the cavity via the sleeve, and the lubricant supply means is provided after the powder release agent supply means completes the supply of the powder release agent. A die casting machine for supplying the lubricant into the sleeve. 9. The die casting machine according to claim 1, wherein when the powder release agent supply means supplies the powder release agent, the surface temperature of the mold is 300. A die casting caster comprising a cooling mechanism for reducing the temperature to a temperature lower than or equal to ° C. 10. The die casting machine according to claim 9, wherein the cooling mechanism is formed by a cooling pipe formed in the mold and through which cold water passes, and the die casting product is removed from the mold. A die casting machine, wherein the temperature of the cavity surface of the mold is reduced to 300 ° C. or less by the time the powder release agent is supplied after the mold is removed. 11. A die casting method in which a molten metal is supplied from a sleeve into a cavity formed by clamping a fixed mold and a movable mold, and die casting is performed. A first step of evacuating the interior of the cavity to a predetermined first degree of vacuum, and using the first degree of vacuum, sucking the powder release agent supplied through the sleeve into the cavity. Second
And the second evacuation means provided separately from the first evacuation means to allow the predetermined first evacuation to be performed inside the cavity.
A third step of evacuating to a predetermined second degree of vacuum higher than the degree of vacuum of the second step, and a step of sliding the molten metal supplied to the sleeve through a plunger that slides inside the sleeve. A die casting method comprising: a fourth step of injecting into the cavity that has been evacuated to a degree of vacuum; and a fifth step of extracting a solid metal product in the cavity. 12. The die casting method according to claim 11, wherein after the powder release agent is sucked into the cavity and before the molten metal is supplied to the sleeve. A lubricant supply step of supplying a lubricant for a plunger sliding on the sleeve to the sleeve.