JP2002239705A - Die casting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die casting apparatus with which the inner part in a cavity in the die can be evacuated to further higher vacuum, in the die casting apparatus using a vacuum die casting method. SOLUTION: In the die casting apparatus for forming a die casting product by reducing the pressure in the cavity formed in between a pair of dies and injecting and filling up molten metal into this cavity, the dies 2, 3 are provided with a gas exhaust path Ep communicating with the cavity C, a valve body opening/closing the gas exhaust path Ep and an electromagnetic actuator 22 as an electromagnetic driving means directly driving the valve body 24 in the opening/closing direction with the electromagnetic force.

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, more particularly, to a die casting apparatus using a vacuum die casting method in which gas in a mold cavity is evacuated before molten metal is injected, and die casting is performed under reduced pressure.

[0002]

2. Description of the Related Art A die casting machine is, for example, formed by extending a fixed die and a movable die, a fixed die plate and a movable die plate holding the fixed die and the movable die, and a tie bar, respectively. A mold clamping device for clamping a moving mold, an injection device for injecting molten metal into a cavity formed between a fixed mold and a moving mold, a hot water supply device for supplying molten metal to the injection device, and the like. I have. In such a die casting machine, while the fixed mold and the movable mold are clamped by the mold clamping device, the molten metal is supplied to the sleeve of the injection device by the hot water supply device, and the injection plunger is driven. A die casting product is cast by injecting and filling molten metal into the cavity.
Incidentally, one of the causes of the decrease in reliability due to the variation in quality of the die-cast product is the inclusion of gas in the die-cast product. That is, the molten metal injected and filled at high speed and high pressure becomes a turbulent flow in the sleeve and the cavity, and entrains the air and the mold release agent applied to the vaporized mold.

[0003] In order to overcome the above-mentioned problems, casting is performed using a die-casting machine based on a vacuum die-casting method, thereby suppressing the content of gas in a die-cast product.
2. Description of the Related Art There is known a technique for reducing variation in quality of a die-cast product due to gas content. In a die casting machine using a vacuum die casting method, for example, US Pat.
As disclosed in Japanese Patent No. 785,448, by injecting and filling a molten metal into a cavity that has been decompressed by a vacuum pump, gas content in the molten metal is suppressed. In the die casting machine using the vacuum die casting method as described above, in order to cast a product of high strength and quality, it is required that the inside of the cavity can be made higher in vacuum and a reduced pressure can be maintained. If the inside of the cavity is not vacuumed, gas will be contained in the cast product,
This is because when a product is subjected to a heat treatment such as annealing after casting, the product is easily deformed or deformed, and it is difficult to obtain a sufficient effect by the vacuum die casting method. In order to cast a product of higher strength and quality, it is specifically required to reduce the pressure inside the cavity to about several tens Torr. Further, from the viewpoint of improving the productivity by the die casting machine, it is also required to shorten the time required for evacuation by the vacuum pump as much as possible.

[0004]

In order to reduce the pressure in the cavity, it is necessary to provide a valve in the middle of an exhaust passage connecting the vacuum pump and the cavity, and to open and close the exhaust passage with the valve. It is known that a valve is opened and closed using, for example, a cylinder device that operates by air pressure or hydraulic pressure. The timing of closing the valve is preferably as short as possible immediately before injecting and filling the molten metal into the cavity from the viewpoint of preventing the degree of vacuum in the cavity from being lowered. However, the cylinder device has a low response, the response time tends to vary, and precise control is difficult. Therefore, it is necessary to close the valve with some allowance. When the valve is closed, the evacuation by the vacuum pump is stopped, and there is a disadvantage that the degree of vacuum in the cavity is easily reduced due to the intrusion of air from the outside into the cavity.

[0005] As another opening and closing method of the valve, a cylinder device is used when opening the exhaust passage, and when closing the exhaust passage, the valve is driven by the inertia force of the molten metal injected and filled into the cavity, or the molten metal is opened or closed. 2. Description of the Related Art There is known a method of driving a valve by converting inertial force into pressure. However, in this method, since the valve touches the molten metal, there is a possibility that the molten metal may enter the exhaust passage, and if it does, the equipment may be seriously damaged. Further, in order to convert the inertial force of the molten metal into pressure, a throttle is required in the flow path of the molten metal, and the cross-sectional area of this portion is reduced, and there is a disadvantage that it is difficult to efficiently exhaust the gas. Furthermore, when the valve is driven by the inertia of the molten metal injected and filled into the cavity at high speed, the valve vigorously collides with the valve seat, and the reaction may lift the valve from the valve seat. Molten metal may enter from between the valve seat.

On the other hand, in order to further increase the vacuum inside the cavity, a sufficient seal is provided between the mating surfaces of the dies and between the extrusion pins for extruding the product and the dies, so that air from the outside is prevented. It is necessary to prevent intrusion. If these seals are not performed reliably, it is difficult to obtain a high vacuum even when evacuating with a vacuum pump. The seal between the mating surfaces of the dies can be achieved by disposing a resin sealing member between the mating surfaces of the dies. When it is located, even if a heat-resistant material is used for the sealing member, the sealing member cannot withstand continuous use due to high temperature. For this reason, conventionally, it is difficult to arrange the seal member so as to continuously surround the periphery of the cavity between the mating surfaces of the molds. Particularly, in the method of mounting the vacuum valve unit on the extension of the mold mating surface. However, it has been difficult to reliably seal between the mating surfaces of the molds. Since the extrusion pin directly contacts the product in a high temperature state, the temperature of the extrusion pin itself cannot be avoided. Therefore, the seal between the extrusion pin and the mold has a resinous O
When a seal member such as a ring is used, there is a problem that the seal member cannot withstand high temperatures. For this reason, conventionally, it has been difficult to sufficiently seal between the extrusion pin and the mold.

As described above, in the related art, the structure of the valve that opens and closes the exhaust path for reducing the pressure in the cavity and the seal structure between the mating surfaces of the mold and between the extrusion pin and the mold have been conventionally used. Then, it was difficult to reduce the pressure inside the cavity to a high vacuum of about several tens Torr and maintain the reduced pressure.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a die casting apparatus using a vacuum die casting method, which can make the inside of a mold cavity a higher vacuum. With the goal.

[0009]

According to the present invention, there is provided a die casting apparatus for reducing the pressure in a cavity formed between a pair of dies, and injecting and filling a molten metal into the cavity to form a die casting product. In the apparatus, the mold has an exhaust path communicating with the cavity, a valve element for opening and closing the exhaust path, and electromagnetic driving means for directly moving the valve element in an opening and closing direction by an electromagnetic force.

[0010] Preferably, the valve body and the electromagnetic driving means are attached to a movable mold side. Also, preferably,
The mold integrally includes a valve seat that the valve body contacts when the valve body closes the exhaust path, and a material for forming the valve seat suppresses rebound due to collision with the valve body. Made of material.

More preferably, the material for forming the valve seat is softer than the material for forming the valve body.

The valve element is disposed between the divided surfaces of the mold and is driven in a direction perpendicular to the divided surface.

The exhaust passage is connected to a first exhaust passage communicating with the cavity formed between the divided surfaces of the mold and an end of the first exhaust passage, and is formed inside the mold. A second exhaust passage, wherein the valve seat is disposed at a connection portion between the first and second exhaust passages, and the valve body abuts in a direction along the dividing surface. It has a valve seat surface.

[0014] The die casting apparatus of the present invention further includes an annular seal member interposed between the divided surfaces of the mold and disposed on the outer periphery of the cavity and the first exhaust path.

In the present invention, an electromagnetic drive means for directly moving in an opening and closing direction by an electromagnetic force is used for driving a valve element for opening and closing an exhaust passage formed in a mold. Therefore, the movement of the valve body can be performed with high response. Further, in the present invention, the exhaust passage can be reliably opened and closed by disposing the valve element between the divided surfaces and integrally forming the valve seat portion with the mold.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a diagram showing an example of the configuration of a die casting machine to which the present invention is applied. In FIG. 1, a die casting machine 1 includes a base 100, a fixed die plate 91 installed on the base 100, a fixed mold 2 attached to the fixed die plate 91, and a fixed mold 2 of the fixed die plate 91. Are mounted on the movable die plate 92 so as to face the injection device 95 provided on the opposite side, the movable die plate 92 provided on the base 100 so as to face the fixed die plate 91, and the fixed die 2. A fixed die plate 91 is provided between the movable die 3 and the movable die plate 92.
And link housing 7 connected by tie bar 80
1 and a toggle mechanism 110 composed of a plurality of links connecting the link housing 71 and the movable die plate 92.

The fixed die plate 91 is fixed to the base 100, and the movable die plate 92 is fixed to the base 100.
Is provided so as to be movable. The link housing 71 and the fixed die plate 91 are connected by four tie bars 80 penetrating the movable die plate 92.

The toggle mechanism 110 is composed of a plurality of links, and connects the link housing 71 and the movable die plate 92. The configuration of the toggle mechanism 110 is a well-known configuration, and a detailed description thereof will be omitted. The toggle mechanism 110 is connected to a crosshead 72, and the crosshead 72 is
It operates by moving in the directions 1 and A2 to move the link housing 71 and the moving die plate 92 closer to or away from each other. The screw shaft 73 is driven by a servo motor (not shown) provided on the link housing 71, and is rotated by the screw shaft 73 to be screwed with the crosshead 7.
2 moves in the directions of arrows A1 and A2.

As shown in FIG. 1, when the crosshead 72 is moved in the direction of arrow A2 by driving a servo motor (not shown), the toggle mechanism 110 is operated, and the movable die plate 92 is separated from the link housing 71. (The mold closing direction), and the fixed mold 2 and the movable mold 3 are closed. Further, when the crosshead 72 is moved in the direction of arrow A2, the tie bar 80 extends,
The fixed mold 2 and the movable mold 3 are clamped by the tension generated in the above.

The injection device 95 injects and fills a molten metal into a cavity (not shown) formed in the fixed mold 2 and the movable mold 3 which have been clamped. By solidifying the molten metal injected and filled into the cavity, a die-cast product is obtained.

On the other hand, when the die casting product is cast and the die casting product is taken out, as shown in FIG. 2, when the crosshead 72 is moved in the direction of arrow A1, the moving die plate 92 moves relative to the link housing 71. The moving mold 3 moves in the approaching direction (mold opening direction), and the fixed mold 2
Open against. When the fixed mold 2 and the movable mold 3 are opened, the die cast product moves while being fitted to the movable mold 3. The die cast product fitted to the movable mold 3 is extruded from the movable mold 3 by an extruding mechanism described later to take out the die cast product.

FIG. 3 is a sectional view showing a structure around a mold according to a first embodiment of the die casting apparatus of the present invention. FIG. 4 is a diagram showing a structure of a mating surface (divided surface) of the fixed mold 2, and FIG. 5 is a diagram showing a structure of a mating surface (divided surface) of the movable mold 3. The fixed mold 2 and the movable mold 3 shown in FIG. 3 are in a mold-clamped state. As shown in FIG. 3, an injection device 95 is provided on the back side of the fixed mold 2.

The injection device 95 has a cylindrical sleeve 96 provided on the back side of the fixed mold 2, a plunger tip 97 fitted on the inner periphery of the sleeve 96, and one end connected to the plunger tip 97. A plunger rod 98,
An injection cylinder device 99 connected to the other end of the plunger rod 98 is provided.

The sleeve 96 has a supply port 96a, and the molten metal ML is supplied into the sleeve 96 from the supply port 96a by the ladle 100. The injection cylinder device 99 has a built-in piston, and a piston rod 99a and a plunger rod 98 connected to the piston.
And are connected by a coupling 99b. The injection cylinder device 99 is driven by hydraulic pressure to extend and retract the piston rod 99a.

The plunger tip 97 is connected to a plunger rod 98, and moves within the sleeve 96 by driving the injection cylinder device 99. By moving the plunger tip 97 in the sleeve 96 to which the molten metal ML is supplied toward the fixed mold 2, the molten metal ML is passed through the runner portion Rn formed by the fixed mold 2 and the movable mold 3. The cavity C is filled. Note that 98
Reference numeral a denotes a sensor in which magnetic poles N and S are formed at a constant pitch in the axial direction on the outer circumference of the plunger rod 98, and detects the number of passages of the magnetic poles as a pulse train, and measures the injection speed of the plunger tip 97. . As shown, the sensor output is provided to a machine controller 52. Reference numeral 52a in the machine controller 52 denotes an injection plunger current position counter, which indicates the position of the plunger chip 97. 52b is a molten metal supply port passing position setting register,
A high-speed injection start position setting register 52c stores the value of the counter 52a in registers 52b and 52c, respectively.
, The machine controller 52 operates the valve controller 51 to open and close the corresponding valve.
To give instructions.

The runner portion Rn is provided in the movable mold 3 shown in FIG.
Is formed by the groove Rna formed on the divided surface 3a of the fixed mold 2 and the divided surface 2a of the fixed mold 2. The cavity C has a concave surface Ca formed on the dividing surface 2a of the fixed mold 2 shown in FIG. 4 according to the shape of the die-cast product, and a concave surface Ca formed on the dividing surface 3a of the moving mold 3 shown in FIG. It is formed by the formed concave surface Cb.

An exhaust passage Ep is formed above the cavity C, as shown in FIG. This exhaust path Ep is
The groove Epa connected to the concave surface Cb formed on the dividing surface 3a of the movable mold 3 shown in FIG. 5 and the fixed mold 2 shown in FIG.
And the groove portion Epb formed on the divided surface 2a. The concave portion Sa adjacent to the groove portion Epb is a contact portion of a valve described later.

As shown in FIG. 3, the split surface 2 of the fixed mold 2
A valve mechanism 21 is provided in communication with an exhaust passage Ep formed between the movable mold 3 and the dividing surface 3a of the movable mold 3. The structure around the valve mechanism 21 will be described with reference to FIG.

As shown in FIG. 6, the valve mechanism 21
An electromagnetic actuator 22, a valve shaft 23 connected to the electromagnetic actuator 22, and a disc-shaped valve body 24 integrally formed at the tip of the valve shaft 23 are provided. Valve shaft 23
The valve body 24 is made of, for example, a metal material such as stainless steel. The electromagnetic actuator 22 is fixed via a flange member 32 to an opening end 29b of a bottomed cylindrical guide member 29 fitted and inserted into an insertion hole 3h formed in the movable mold 3. An O-ring 3 made of resin is provided between the guide member 29 and the insertion hole 3h formed in the movable mold 3.
0 is interposed, and seals between the insertion hole 3h and the guide member 29.

A guide hole 2 is provided at the bottom of the guide member 29.
9a are formed. The valve shaft 23 is movably fitted and inserted into the guide hole 29a. Valve shaft 23
From the viewpoint of stabilization at the time of movement, the portion fitted into the guide hole 29a is larger in diameter than the valve body 24 side. Also,
The guide hole 29a and the valve shaft 23 are precisely fitted, and the space between the guide hole 29a and the valve shaft 23 is sealed. The interior of the valve shaft 23 is a hollow portion 23a. This is because the inertia of the valve shaft 23 is reduced by reducing the weight, and the movement of the valve shaft 23 is accelerated.

The movable die 3 has an exhaust passage 26 communicating with the exhaust passage Ep and having the valve shaft 23 inserted therein.
It is formed along the direction perpendicular to a. The portion of the movable mold 3 where the exhaust path 26 is formed is the valve mechanism 2
It is formed of another metal member 3d for incorporating 1 into the movable mold 3.

A valve seat 39 is formed at the tip of the exhaust passage 26 (on the side of the dividing surface 3a). This valve seat 39 is
When the valve body 24 comes into contact with a valve seat surface 39 a formed on the valve seat portion 39, the exhaust passage 26 is opposed to the valve body 24.
Close. Note that the valve seat surface 39a is formed along the dividing surface 3a of the movable mold 3. The valve seat portion 39 is formed of a material that is softer than the valve body 24 and is familiar when it comes into contact with the valve body 24. Specifically, it is a metal material such as a copper alloy.

The moving die 3 has an exhaust path 25 formed along a direction orthogonal to the exhaust path 26. The exhaust path 25 and the exhaust path 26 communicate with each other. A mounting hole 3g is formed above the exhaust path 25, and an exhaust pipe 55 is inserted into the mounting hole 3g. The exhaust pipe 55 has a screw formed on the outer periphery of the distal end, and the screw is screwed with a screw formed on the inner periphery of the mounting hole 3g. In addition, mounting holes 3
In order to seal the space between the exhaust pipe 55 and the mounting hole 3g, resin O-rings 59a and 59b
The ring member 59 is fixed via the.

The electromagnetic actuator 22 includes a shaft member 22a connected to the valve shaft 23 inside the case, a permanent magnet (not shown) fixed to the shaft member 22a, and an electromagnet (not shown) provided around the permanent magnet. And
By supplying power to the electromagnet from the outside, an attractive force is generated between the permanent magnet and the electromagnet, and the shaft member 22a moves directly. The electromagnetic actuator 22 drives the valve body 24 in a direction to open and close the exhaust path 26 indicated by arrows C1 and C2 in FIG. 6 by appropriately changing the direction of the current supplied to the electromagnet.

The electromagnetic actuator 22 is electrically connected to the valve controller 51 as shown in FIG. The valve controller 51 includes the electromagnetic actuator 2
2 is controlled to open and close the valve element 24. The valve controller 51 is electrically connected to a machine controller 52 that comprehensively controls the driving of the die casting machine 1, and controls the driving of the electromagnetic actuator 22 according to a signal input from the machine controller 52.

The exhaust pipe 55 is connected to a vacuum pump 50 as shown in FIG. The vacuum pump 50 exhausts the inside of the cavity C through the exhaust pipe 55, the exhaust path 25, the exhaust path 26, and the exhaust path Ep. As the vacuum pump 50, a pump that can be evacuated to a high vacuum of about several Torr to several tens Torr is used.

A groove 3b into which the sealing member 35 is fitted is formed in the dividing surface 3a of the movable mold 3, and the sealing member 35 is fitted in the groove 3b, and a part of the sealing member 35 projects from the dividing surface 3a. ing. When the protruding portion of the seal member 35 is aligned with the dividing surface 3a of the movable mold 3 and the dividing surface 2a of the fixed mold 2, the dividing member 2 comes into contact with the dividing surface 2a.
a and the dividing surface 3a are sealed. Seal member 35
It is preferable to use, for example, a material formed of a material having relatively high heat resistance such as silicon rubber. In addition, it is also possible to adopt a configuration in which the sealing member 35 is fitted into the dividing surface 2a of the fixed mold 2.

The sealing member 35 is, as shown in FIG.
It is provided continuously on the outer peripheral portion of the divided surface 3a of the movable mold 3, and has no joint. Further, an exhaust path Ep, a cavity C, and a runner portion Rn are arranged on the inner peripheral side of the seal member 35, and are sufficiently separated from the seal member 35.

Next, the specific structure of the pushing mechanism 41 will be described. The pushing mechanism 41 is, as shown in FIG.
It is installed on the back of the movable mold 3. This pushing mechanism 4
Reference numeral 1 denotes a plurality of push pins 42, holding plates 43 and 44 holding one end of the push pins 42, a movable plate 45 to which the hold plates 43 and 44 are fixed, and a movable plate 45 with respect to the movable mold 3. A guide shaft 46 for movably guiding and a seal cooling mechanism 61
And

The push-out pin 42 is formed of, for example, a metal member such as stainless steel, and is fitted and inserted into each of the insertion holes 3 k formed in the movable mold 3. As will be described later, the insertion hole 3k is fitted to the push pin 42 only at a position close to the dividing surface 3a of the movable mold 3, and the other portions are enlarged in diameter so that the push pin 42 slides easily. Have been. As shown in FIG. 5, the insertion hole 3k is open in the dividing surface 3a of the movable mold 3. Each insertion hole 3k is provided in the periphery of the runner portion Rn and the cavity C and in the exhaust passage Ep. By protruding the tip of the push pin 42 from these insertion holes 3k, the die casting product fitted in the movable mold 3 can be pushed out.

The holding plates 43 and 44 hold the enlarged rear ends of the push pins 42. The holding plates 43, 44
Is fixed to the movable plate 45. The movable plate 45 is shown in FIG.
As shown in FIG. 7, the guide is movably guided in the directions of arrows E1 and E2. The movable plate 45 is moved in a predetermined range in the directions of arrows E1 and E2 by driving means (not shown). By moving the movable plate 45 in the direction of the arrow E2, the tip of the push pin 42 is moved to the movable mold 3.
Project from the divided surface 3a.

The extrusion pin 42 and the insertion hole 3k are fitted with each other, and there is no possibility that the molten metal ML may enter between the extrusion pin 42 and the insertion hole 3k. Air can enter between them. If air enters from the outside between the push pin 42 and the insertion hole 3k, when the inside of the cavity C is depressurized, the inside of the cavity C cannot be made high vacuum. In addition, since the extrusion pin 42 directly contacts the high-temperature die-cast product, the temperature of the extrusion pin 42 itself may become high. Therefore, if a resin sealing member (O-ring) is provided between the push pin 42 and the insertion hole 3k to seal the space between the push pin 42 and the insertion hole 3k, the O
The ring may not withstand high temperatures and may not be able to be used continuously.

In this embodiment, the seal cooling mechanism 61 is provided at the back of the movable mold 3 in order to solve the above problem. FIG. 7 is a diagram showing a specific structure of the seal cooling mechanism 61. As shown in FIG. 7, the seal cooling mechanism 61
Are fixed to the plate-shaped first member 63 having the recess 63h, the plate-shaped second member 64 fixed to the recess 63h side of the first member 63, and the first member 63 and the second member 64. And a seal holding member 65.

The first member 63 and the second member 64 are connected to each other, and constitute a coolant storage space Sa between the recess 63h of the first member 63 and the facing surface of the second member 64. First
An O-ring 75 made of resin is interposed between the member 63 and the second member 64 to seal between the first member 63 and the second member 64.

The second member 64 is fixed to the back of the movable mold 3. An O-ring 74 made of resin is interposed on the outer peripheral portion between the second member 64 and the rear surface of the movable mold 3 to seal between the second member 64 and the rear surface of the movable mold 3. I have. A concave portion 64 a is formed on the surface of the second member 64 facing the movable mold 3, which is located on the inner peripheral side of the O-ring 74, and a gap is provided between the movable mold 3 and the second member 64. S is formed.

A supply port 63b for supplying the cooling liquid W to the cooling liquid storage space Sa and a discharge port for discharging the cooling liquid W stored in the cooling liquid storage space Sa are provided on the peripheral wall of the first member 63. An outlet 63c is formed.

The seal holding member 65 is formed of a cylindrical member, and has an enlarged diameter portion at the rear end of the movable mold 3.
Insertion hole 63a formed in member 63 and second member 64
The outer periphery is fitted and inserted into an insertion hole 64b formed in
It is fixed to the member 63 and the second member 64. Insertion hole 63a of first member 63 and insertion hole 64 of second member 64
O-rings 72 and 73 made of resin are held on the inner circumference of b. These O-rings 72 and 73
Seals between the outer periphery of the seal holding member 65 and the insertion holes 63a and 64b.

The seal holding member 65 has a through hole 65a at the center thereof into which the push pin 42 is fitted and inserted. On the inner periphery of the through hole 65a, a resin O-ring 70 is held on the second member 64 side, and a resin O-ring 71 is held on the first member 63 side. O-ring 70, 71
Seals between the extrusion pin 42 and the through hole 65a. The seal holding member 65 has a hollow portion 65c inside.
And a through-hole 6 formed in a direction orthogonal to the extrusion pin 42.
5b.

In the seal cooling mechanism 61 having the above structure, the supply port 63b of the first member 63 is
0 is connected, and the coolant W is supplied through the coolant supply pipe 30. As the cooling liquid W, for example, water is used.

The cooling liquid W supplied from the cooling liquid supply pipe 30
Is introduced into the coolant storage space Sa, and a part of the coolant W
Is supplied to the cavity 65c through the through hole 65b of the seal holding member 65. The cooling liquid W supplied to the cavity 65c cools a part of the extrusion pin 42 exposed in the cavity 65c. Therefore, the extrusion pin 42 existing near the hollow portion 65c is partially cooled. Coolant supply pipe 30
, The coolant W is continuously supplied, so that the fresh coolant W circulates in the vicinity of the cavity 65c,
b and is discharged to the discharge port 63c.

On the other hand, of the O-rings 70 and 71 fitted on the outer periphery of the push-out pin 42, the O-ring 70 is disposed between the push-out pin 42 and the insertion hole 3k formed in the movable mold 3 from outside. It has a role of preventing air from entering and a role of preventing the coolant W from entering the insertion hole 3k. O
The ring 71 has a function of preventing the coolant W from leaking from the coolant storage space Sa to the outside. Even if these O-rings 70 and 71 are formed of a heat-resistant material such as silicon rubber or fluorine rubber, they can be used continuously in an environment where the temperature of the extrusion pin 42 reaches a high temperature of 200 ° C. or more, for example. Can not stand. In this embodiment, even if the temperature of the extrusion pin 42 rises due to contact with the high-temperature die-cast product, the hollow portions 65c are arranged near the O-rings 70 and 71.
The portion in contact with 1 is kept at, for example, 100 ° C. or lower. As a result, the O-rings 70 and 71 are not damaged by heat.

Next, an example of the operation of the die casting machine 1 having the above configuration will be described. First, die casting machine 1
From the state shown in FIG. 2, that is, the state where the fixed mold 2 and the movable mold 3 are in the mold open state,
By the control of 2, the toggle mechanism 110 is operated, and the fixed mold 2 and the movable mold 3 are clamped. When the fixed mold 2 and the movable mold 3 are clamped, the gap between the divided surface 2a of the fixed mold 2 and the divided surface 3a of the movable mold 3 is sealed by the seal member 35. When the die casting machine 1 is started, the cooling liquid W is supplied to the seal cooling mechanism 61 described above. When the die casting machine 1 is started, the vacuum pump 50 is also started.
Reference numeral 4 denotes a state in which the discharge path 26 is closed. Therefore, the inside of the cavity C is not exhausted.

On the other hand, the sleeve 96 of the injection device 95
A predetermined amount of molten metal such as an aluminum alloy is supplied by the ladle 100. When the supply of the molten metal by the ladle 100 is completed, the plunger chip 97 is driven under the control of the machine controller 52. When the tip of the plunger tip 97 passes through the supply port 96a of the sleeve 96, the sleeve 96 is sealed by the plunger tip 97, and the intrusion of air from the sleeve 96 into the cavity C is blocked. When the movement of the plunger tip 97 is started, the plunger tip 97 is usually moved at a low speed.

For example, the machine controller 52 determines the position of the plunger chip 97 from the detection position of the plunger chip 97.
It is determined that the valve 7 has passed through the supply port 96 a of the sleeve 96, and a command to open the valve body 24 of the valve mechanism 21 is output to the valve controller 51. Valve controller 51
Receives an instruction from the machine controller 52 and supplies electric power for driving the electromagnetic actuator 22 of the valve mechanism unit 21 to the electromagnetic actuator 22.

When the electromagnetic actuator 22 is driven,
As shown in FIG. 8, the valve element 24 moves in the direction of the arrow C2, and the valve element 24 comes into contact with the contact surface Sa formed on the divided surface 2a of the fixed mold 2 and stops. At this time, since the valve body 24 is driven by the electromagnetic actuator 22, for example, the valve body 24 opens in a time of several msec to tens of msec and substantially in a constant time. For example, when a hydraulic cylinder is used to drive the valve body 24, the valve body 24 is fully opened until the valve body 24 is completely opened.
It takes a time of one hundred and several tens msec, and the time varies.

By the movement of the valve element 24, a gap is formed between the valve element 24 and the valve seat surface 39a. The discharge path Ep, the discharge path 26, the discharge path 25, and the discharge pipe 5 communicating with the cavity C are formed through the gap between the valve body 24 and the valve seat surface 39a.
5, the air (gas) in the cavity C is exhausted.

The space between the divided surface 2a of the fixed mold 2 and the divided surface 3a of the movable mold 3 is securely sealed by a seal member 35. The space between the extrusion pin 42 and the movable mold 3 is Since the seal is securely sealed by the O-ring 70 provided in the seal cooling mechanism 61, the pressure in the cavity C is rapidly reduced.

Here, the relationship between the pressure reduction in the cavity C and the injection speed will be described with reference to the graph shown in FIG. A graph (1) shown in FIG. 9 shows a decompression curve in the cavity C, and a graph (2) shows the plunger tip 9.
7 illustrates an injection speed waveform. In addition, graph (3)
As a comparative example, the cavity C in the case of opening and closing the valve using the conventional electromagnetic switching valve and the hydraulic / pneumatic cylinder device
The graph (4) shows the pressure reduction curve in the cavity C when the valve is driven by the inertial force of the molten metal injected and filled in the cavity when the exhaust path is closed. Graphs (3) and (4)
This is the case where the seal cooling mechanism 61 is not provided, and the seal member is not continuously interposed between the division surface 2a of the fixed mold 2 and the division surface 3a of the movable mold 3.

As shown in the graph (1), if the decompression start time is Pt1, the response of the valve body 24 is good, so that the inside of the cavity C is rapidly decelerated from the decompression start time Pt1. Furthermore, since there is almost no air leakage from between the extrusion pin and the mold or between the divisional surface 2a of the fixed mold 2 and the divisional surface 3a of the movable mold 3, decompression can be performed efficiently in a short time. Understand.

On the other hand, in the graphs (3) and (4),
Since the cylinder device is used to drive the valve, the time lag from the decompression start point Pt1 to the actual start of decompression is relatively long, and the distance between the extrusion pin and the die or between the split surface 2a of the fixed die 2 and the movable die It can be seen that the pressure is not efficiently reduced because air leaks from between the mold 3 and the dividing surface 3a.

As the movement of the plunger tip 97 progresses, the runner portion Rn that connects the cavity C and the sleeve 96 is also filled with the molten metal ML. In this state, the inside of the cavity C is, for example, 20 to 40 Torr.
It is in a state of high vacuum.

Injection of molten metal ML into cavity C
Filling is performed by switching the injection speed of the plunger tip 97 to high speed. That is, at the high-speed injection start time point Pt2 shown in FIG. 9, the injection speed is switched to high speed. However, before switching to high-speed injection, the exhaust path needs to be closed by the valve element 24 in order to prevent the molten metal ML from entering the valve mechanism 21. The timing for closing the exhaust path 26 by the valve element 24 is preferably immediately before the high-speed injection start point Pt2. That is, after the exhaust path 26 is closed by the valve element 24, the exhaust in the cavity C is not performed, and the pressure in the cavity C may increase due to air leakage.

In the present embodiment, the electromagnetic actuator 22 is used to drive the valve element 24, and the valve shaft 23 is reduced in weight, so that it can be closed in a short time of about several msec to about several tens msec. In addition, since there is almost no variation in the response of the electromagnetic actuator 22, the response can be performed immediately before the high-speed injection start point Pt2.

The timing at which the exhaust path 26 is closed by the valve 24 is determined by the machine controller 52 detecting the pressure in the cavity C with the detection position of the plunger chip 97 or a pressure sensor provided in the mold. . The machine controller 52 outputs a command to the valve controller 51 in response to detection of these signals.

When the electromagnetic actuator 22 is driven and the discharge path 26 is closed by the valve element 24, the valve element 24 collides with the valve seat surface 39 a of the valve seat portion 39 at a high speed.
May rebound from the valve seat 39 and jump up. However, in the present embodiment, as the material for forming the valve seat portion 39, a material that suppresses rebound, that is, a material that is softer and more familiar than the material for forming the valve body 24 is used. Bouncing up when colliding with the valve seat portion 39 can be suppressed as much as possible. As a result,
It is possible to prevent the molten metal from entering the valve mechanism 21.

When switching to high-speed injection is performed at the high-speed injection start point Pt2, the molten metal ML is
Filled and solidified. Thereby, a desired die-cast product is obtained.

In order to take out the formed die-cast product from the fixed mold 2 and the movable mold 3 in the clamped state, the toggle mechanism 110 is operated to open the fixed mold 2 and the movable mold 3. When the fixed mold 2 and the movable mold 3 are opened (at this time, the plunger tip presses the biscuit section following the runner section with a predetermined pressure), the formed die-cast product is separated from the fixed mold 2. In this state, the die casting product can be removed from the movable mold 3 by operating the extrusion mechanism 41 and projecting the extrusion pin 42 from the dividing surface 3 a of the movable mold 3.

At this time, the temperature of the extrusion pin 42 also rises because the extrusion pin 42 directly contacts the die-cast product in a high temperature state. On the other hand, in the seal cooling mechanism 61, the O-rings 70 and 71 fitted to the push pin 42 are
Since the extrusion pin 42 is partially cooled, it is not exposed to a high temperature, and the functions of the O-rings 70 and 71 are not deteriorated by heat.

Further, since the cooling liquid W is continuously supplied to the seal cooling mechanism 61, the seal cooling mechanism 6
The temperature of 1 is sufficiently lower than the temperature of the moving mold 3. Therefore, if the seal cooling mechanism 61 is in direct contact with the movable mold 3, it may affect the temperature distribution of the movable mold 3 and affect the quality of the die-cast product. Since a gap is formed between the seal cooling mechanism 61 and the movable mold 3 so that the seal cooling mechanism 61 and the movable mold 3 are not in direct contact with each other, the movable mold 3 of the seal cooling mechanism 61 is not provided. Can be suppressed.

As described above, according to the present embodiment, the opening and closing of the exhaust path can be quickly performed by using the electromagnetic actuator 22 to drive the valve element that opens and closes the exhaust path that connects the cavity C and the vacuum pump 50. It can be carried out. Since the electromagnetic actuator 22 is driven by electric power,
There is no need to supply hydraulic oil or the like, and the valve mechanism 21 can be downsized. For this reason, the degree of freedom in the arrangement of the valve mechanism 21 with respect to the mold is increased, and it becomes easy to optimize the arrangement of the exhaust path that communicates the valve body 24 and the cavity C with the vacuum pump 50. Since the arrangement of the exhaust path communicating the cavity C and the vacuum pump 50 can be optimized, the divided surface 2a of the fixed mold 2 and the divided surface 3a of the movable mold 3 can be optimized.
The seal member 35 can be interposed seamlessly on the outer peripheral portion of the seal member 35, and a sufficient distance can be secured between the seal member 35 and the exhaust path communicating the cavity C and the vacuum pump 50. Burnout due to heat can be prevented. Furthermore, according to the present embodiment, by partially forcibly cooling the extruding pin 42 that becomes high temperature,
A general-purpose resin sealing member such as an O-ring can be easily used for the seal between the extrusion pin 42 and the mold.

Second Embodiment FIG. 10 is a sectional view showing a structure around a mold according to a second embodiment of the die casting machine of the present invention. The same components as those in the above-described embodiment are denoted by the same reference numerals. As shown in FIG. 10, the movable mold 3 of the die casting machine according to the present embodiment is provided with a plurality of valve mechanisms 201 and 202. Valve mechanism 20
The configuration of the components 202 is the same as the configuration of the valve mechanism 21 described above.

The valve mechanism 201 is provided in the middle of the exhaust passage Ep formed between the dividing surface 3a of the movable mold 3 and the dividing surface 2a of the fixed mold 2. Exhaust passage Ep
Communicates with the cavity C. The exhaust passage Ep communicates with the vacuum pump 501 through exhaust passages 301 and 302 formed in the movable mold 3 corresponding to the valve mechanism unit 201, and exhaust gas formed corresponding to the valve mechanism unit 202. Vacuum pump 5 through channels 303 and 304
02. Vacuum pumps 501 and 502
Have equivalent exhaust capacity.

The electromagnetic actuators 22 of the valve mechanisms 201 and 202 are connected to a common valve controller 51. This valve controller 51
Can independently drive the valve mechanisms 201 and 202, respectively.

As described in the first embodiment, by using the electromagnetic actuator 22 to drive the valve element 24, the size of the valve mechanism can be reduced, and the degree of freedom of arrangement with respect to the mold can be increased. Will be possible. For this reason, it is possible to easily install the plurality of valve mechanisms 201 and 202 in the mold.

As described above, the plurality of valve mechanisms 20
By installing 1,202 in the mold, the total cross-sectional area of the exhaust passage for exhaust can be increased as compared with the case where a single valve mechanism is installed. Good exhaust is possible. That is, when a single valve mechanism is installed, even if the exhaust capacity of the vacuum pump is increased, if the cross-sectional area of the exhaust passage is small, the pressure cannot be rapidly reduced in a short time. In addition, if the cross-sectional area of the discharge path is enlarged, the molten metal easily enters the discharge path.

Further, a plurality of valve mechanisms 201, 202
Is installed in a mold and can be independently driven, so that the timing of opening and closing the valve can be optimized according to the arrangement of the valve mechanism.

Next, a plurality of valve mechanisms 201, 202
An example of the decompression operation in the cavity C in the case where is used will be described with reference to FIG. In FIG. 11, a graph (1) shows a pressure reduction curve in the cavity C, and a graph (2) shows an injection speed waveform of the plunger tip 97. First, the valve mechanisms 201 and 202 start moving the plunger tip 97 at a low speed from a state in which the discharge path is closed. Next, at the injection start time point Pt1, one of the valve mechanisms 201 is opened, and the cavity C is opened.
Start depressurizing the inside. In this state, the other valve mechanism 202 is closed.

When the valve mechanism 201 is opened, the pressure in the cavity C is rapidly reduced by the vacuum pump 501. Next, when the inside of the cavity C is reduced to a certain pressure Pt2, the valve mechanism 201 is closed and the valve mechanism 202 is opened. Thus, the pressure in the cavity C is continuously reduced by the vacuum pump 502. The opening and closing operations of the valve mechanisms 201 and 202 are performed by the machine controller 52 through the valve controller 5.
This is performed when a command is output to # 1.

As a characteristic of the vacuum pump, it is known that the evacuation speed gradually decreases as the pressure decreases. For example, as the pressure is reduced by the vacuum pump 501, the exhaust speed gradually decreases. For this reason, after a certain degree of decompression has progressed by the vacuum pump 501,
A vacuum pump 50 for reducing the pressure in the cavity C;
By exchanging with 2, the reduction in the exhaust speed can be suppressed as much as possible, and the time required to reduce the pressure to a desired pressure can be reduced.

When the pressure inside the cavity C is reduced by the vacuum pump 502, the inside of the cavity C reaches a high vacuum state. In this state, the injection speed of the plunger tip 97 is switched to a high speed as shown at the point Pt3 in the graph (2).

On the other hand, the timing of closing the valve mechanism 202 is preferably made as late as possible from the viewpoint of maintaining the inside of the cavity C in a high vacuum state. Therefore,
Even after switching to high-speed injection, as long as the molten metal does not reach the valve mechanism 202, the valve mechanism 20
2 is opened, the vacuum pump 50
The pressure increase in the cavity C after closing the exhaust passage communicating with the second can be surely suppressed. In the present embodiment, the valve mechanism 202 is closed after switching to the high-speed injection as at the point Pt4 in the graph (2).

The time required for high-speed injection is, for example, 40
Although it is as short as about 200 msec, in this embodiment, since the electromagnetic actuator 22 is used for the valve mechanism,
During such a limited time, the valve mechanism 202 can be closed at an appropriate timing. Also, of the plurality of valve mechanisms 201 and 202, the valve mechanism 20
Numeral 2 is at a position farther from the cavity C than the valve mechanism 201, and by closing the valve mechanism 202 at such a position last, it is possible to close the exhaust path communicating with the cavity C It is possible to prevent the molten metal from entering the valve mechanism while delaying as much as possible.

[0083]

According to the present invention, in a die casting apparatus using a vacuum die casting method, the inside of a mold cavity can be made higher in vacuum. Further, according to the present invention, the pressure inside the mold cavity can be efficiently reduced in a short time.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a configuration of a die casting machine to which the present invention is applied.

FIG. 2 is a view showing a die-open state of the die casting machine shown in FIG. 1;

FIG. 3 is a sectional view showing a structure around a mold according to the first embodiment of the die casting apparatus of the present invention.

FIG. 4 is a view showing a structure of a division surface of a fixed mold 2;

FIG. 5 is a view showing a structure of a division surface of a movable mold 3;

FIG. 6 is a sectional view showing a structure around a valve mechanism 21;

FIG. 7 is a sectional view showing a specific structure of the seal cooling mechanism 61.

FIG. 8 is a diagram for explaining an operation state of the valve mechanism unit 21.

FIG. 9 is a diagram for explaining the relationship between the pressure reduction in the cavity C and the injection speed.

FIG. 10 is a sectional view showing a structure around a mold according to a second embodiment of the die casting machine of the present invention.

FIG. 11 is a diagram for explaining the relationship between the pressure reduction in the cavity C and the injection speed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Die-casting machine 2 ... Fixed mold 3 ... Moving mold 21 ... Valve mechanism part 22 ... Electromagnetic actuator 23 ... Valve shaft 24 ... Valve body 39 ... Valve seat part 39a ... Valve seat surface 50, 501, 502 ... Vacuum pump

Claims (7)

[Claims] 1. A die casting apparatus for reducing the pressure in a cavity formed between a pair of dies, and injecting and filling a molten metal into the cavities to form a die casting product. A die casting device comprising: an exhaust passage communicating with a cavity; a valve body for opening and closing the exhaust passage; and an electromagnetic driving unit for directly moving the valve body in an opening and closing direction by an electromagnetic force. 2. The die casting apparatus according to claim 1, wherein said valve body and said electromagnetic driving means are attached to a movable mold side. 3. The mold according to claim 1, further comprising a valve seat portion to which the valve body comes into contact when the valve body closes the exhaust passage, wherein a material for forming the valve seat portion collides with the valve body. The die-casting device according to claim 1, wherein the die-casting device is formed of a material that suppresses repulsion due to the slab. 4. The die casting apparatus according to claim 3, wherein the material for forming the valve seat is softer than the material for forming the valve body. 5. The valve body according to claim 1, wherein the valve body is disposed between the divided surfaces of the mold and is driven in a direction perpendicular to the divided surfaces.
A die casting apparatus according to any one of claims 1 to 4. 6. The exhaust path is connected to a first exhaust path communicating with the cavity formed between the divided surfaces of the mold, an end of the first exhaust path, and the inside of the mold. And a second exhaust passage formed at the connection portion between the first and second exhaust passages, and the valve body is disposed in a direction along the dividing surface. The die casting apparatus according to claim 4, further comprising a valve seat surface that abuts. 7. The die casting apparatus according to claim 6, further comprising an annular seal member interposed between the divided surfaces of the mold and disposed on the outer periphery of the cavity and the first exhaust path.