JP2000271715A - Vacuum forming apparatus for die casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of casting blow hole by preventing the entrapment of the air at molten metal injection. SOLUTION: In a nozzle body 11, a pressure chamber 26 is arranged. When the pressure in the pressure chamber 26 is raised, a molten metal valve 60 is shifted and the flowing passage in a nozzle base is closed. Then, the nozzle body 11 and a product forming part 10' become in a vacuum state and the molten metal valve 60 is opened with the injected molten metal, and the molten metal is filled and solidified into the product forming part 10' without entraping the air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum molding apparatus for die casting for vacuum injection molding of a molten metal such as a zinc alloy or a magnesium alloy.

[0002]

2. Description of the Related Art FIG. 25 is a sectional view showing a general structure of a die casting apparatus. In FIG. 25, the machine nozzle 4 and the mold 7 of the die casting machine are about 10
In addition, the molten metal injection part 4a of the mechanical nozzle 4 has a molten surface 9a of the molten metal (molten metal 9) in the melting furnace 1.
Of the molten metal injection part 4a
It has a structure to prevent hot water from flowing out.

When a product is formed by this die casting apparatus, first, a molten metal 9 melted in a melting furnace 1 is sent out by a plunger 3 reciprocating within a sleeve 2 and passes through a mechanical nozzle 4. Then, it is injected into the mold 7. The mold 7 includes a fixed mold 7a and a movable mold 7b. The molten metal injected from the mechanical nozzle 4 passes through a sprue bush 6 of the fixed mold 7a, and is formed into a product forming part formed by the fixed mold 7a and the movable mold 7b. 8 '.

At this time, the inside of the machine nozzle 4, the inside of the sprue bush 6, and the inside of the product forming portion 8 'are filled with air. For this reason, the filled molten metal advances while pushing out the air filled in the product forming portion 8 ′ from the gap of the mold 7. However, since the speed of the molten metal is very high, the molten metal may entrain the air. There is. The air entrained in the molten metal as described above is partially left in the molten metal filled in the product forming section 8 '.

Thereafter, the molten metal supplied to the product forming section 8 'as described above is cooled by the mold 7 and solidified. Then, the movable mold 7b is moved in the direction of arrow A to open the mold 7, and the product portion 8a, the runner portion 8b,
The molded product 8 integrated with the sprue portion 8c is taken out. The molded article 8 is formed by breaking off the runner section 8b together with the sprue section 8c at the gate section 8d. Here, in the case where the protrusion of the portion where the runner portion 8b is cut off is not allowed, or when high shape accuracy is required, the portion where the runner portion 8b is cut off is subjected to file processing, cutting processing, and the like. Is arranged.

As shown in FIG. 25, the sprue bush 6 in the die casting apparatus is cooled by cooling water 31 circulating around the outer periphery, and the sprue portion 8c of the sprue portion 8c due to insufficient cooling when the mold 7 is opened. It was configured to prevent premature disconnection.

Further, the outer periphery of the mechanical nozzle 4 is heated by the mechanical nozzle heater 5 so that the molten metal does not solidify in the mechanical nozzle. Furthermore, the injection part 4a of this machine nozzle
Was set in a state of being pressed against the mechanical nozzle touch portion 6a (see FIG. 27) of the sprue bush 6 so that the molten metal did not leak.

[0008]

As described above, since the molten metal is injected into the mold 7 at a high speed, air is inevitably entrained in the molten metal, and when a molded product is solidified, a cavity is formed therein. Let me do it. With such a cavity, when the runner portion 8b is cut off or cut as described above, the cavity is exposed on the surface and becomes a hole, and a correct shape cannot be obtained. In addition, when performing the surface treatment, there is a problem that the surface treatment cannot be performed to the depth of the hole. Also, when plating is performed, there is a problem that the plating solution remains in the holes and the corrosion resistance is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has a vacuum inside a mold to eliminate the entrapment of air during injection of molten metal and eliminate the occurrence of cavities. An apparatus is provided.

[0010]

Means for Solving the Problems Claim 1 of the present invention
In the vacuum forming apparatus for die-casting according to the present invention, a nozzle tip as a molten metal injection section is fixed to a tip end portion of a nozzle body, and the nozzle tip insulates the mold and maintains a position in the mold. Is fixed to the nozzle body. In addition, the heat-insulating ring and the mold, and the heat-insulating ring and the nozzle tip are always fitted with a gap at room temperature and when the temperature rises during molding, so that the heat-insulating ring is prevented from being damaged. . Further, a compressible heat-resistant gasket is provided between the nozzle body and the heat insulating ring to prevent the passage of the molten metal. In addition, a gasket is provided between the heat insulating ring and the mold in order to keep the product molded portion of the mold in a vacuum. On the other hand, in the nozzle body, there is provided a molten metal valve which is guided by a valve guide and is movable along a flow path whose movement is restricted by a valve stopper. The molten metal valve includes a valve piston movably provided in the nozzle body, a valve tip guide attached to an end of the valve piston, a valve spring provided in the valve tip guide, and a valve. And a valve tip movably provided in the tip guide and urged by a valve piston and a valve spring. This valve tip is
When the valve piston moves due to the pressure in the pressure chamber formed by the valve guide, the valve piston is pressed against the nozzle base of the nozzle body by the valve spring, and acts to close the flow path and maintain the airtightness in the nozzle body. The pressure in the pressure chamber is increased by compressed air sent from a pressure source via a connection pipe, and energizes the molten metal valve. Further, the valve tip of the molten metal valve is opened when the molten metal is injected, and flows the molten metal from the flow path into the product forming portion of the mold. Further, the vacuum source is for bringing the product forming portion of the mold into a vacuum state, and the inside of the nozzle body is also brought into a vacuum state together with the product forming portion to prevent air from being entrained at the time of injection of the molten metal.

In the vacuum forming apparatus for die casting according to a second aspect of the present invention, the heat insulating ring is directly fixed to the tip of the nozzle body. The fitting between the heat insulating ring and the mold is always a clearance fit at both room temperature and when the temperature rises during molding, so that the heat insulating ring is prevented from being damaged. Further, a compressible heat-resistant gasket is provided between the nozzle body and the heat insulating ring to prevent the passage of the molten metal. In addition, a gasket is provided between the heat insulating ring and the mold in order to keep the product molded portion of the mold in a vacuum. On the other hand, in the nozzle body, there is provided a molten metal valve which is guided by a valve guide and is movable along a flow path whose movement is restricted by a valve stopper. The molten metal valve includes a valve piston movably provided in the nozzle body, a valve tip guide attached to an end of the valve piston, a valve spring provided in the valve tip guide, and a valve. And a valve tip movably provided in the tip guide and urged by a valve piston and a valve spring. The valve tip is pressed against the nozzle base of the nozzle body by the valve spring when the valve piston moves by the pressure in the pressure chamber formed by the valve guide, so that the flow path is closed and the airtightness in the nozzle body is maintained. Works. The pressure in the pressure chamber is increased by compressed air sent from a pressure source via a connection pipe, and energizes the molten metal valve. Further, the valve tip of the molten metal valve is opened when the molten metal is injected, and flows the molten metal from the flow path into the product forming portion of the mold. Furthermore,
The vacuum source is used to bring the product forming portion of the mold into a vacuum state, and the inside of the nozzle body is also brought into a vacuum state together with the product forming portion to prevent air from being entrained when the molten metal is injected.

According to a third aspect of the present invention, there is provided a vacuum forming apparatus for die casting, wherein the valve tip has a conical contact portion, and the nozzle body has a conical surface at a portion where the contact portion of the valve tip contacts. It is configured to have a contact portion.

According to a fourth aspect of the present invention, there is provided a vacuum forming apparatus for die-casting, wherein the valve tip has a spherical contact portion, and the nozzle body has a conical contact with a portion where the contact portion of the valve tip contacts. It is configured to have a portion.

Further, in the vacuum forming apparatus for die casting according to claim 5 of the present invention, the valve tip has a spherical contact portion, and the nozzle body has the same contact portion as the contact portion of the valve tip. It is configured to have a spherical contact with a slightly larger radius.

Further, in the vacuum forming apparatus for die casting according to claim 6 of the present invention, a valve stopper is provided on the nozzle body for guiding the valve tip guide and restricting the movement of the valve piston, and the valve piston has a conical contact. The valve stopper has a conical first contact portion at a portion where the contact portion of the valve piston contacts.

According to a seventh aspect of the present invention, there is provided a vacuum forming apparatus for die casting, wherein a valve stopper for guiding a valve tip guide and restricting movement of a valve piston is provided in a nozzle body, and the valve piston has a spherical contact portion. And the valve stopper is configured to have a conical first contact portion at a portion where the contact portion of the valve piston contacts.

In the vacuum forming apparatus for die casting according to claim 8 of the present invention, a valve stopper for guiding the valve tip guide and restricting the movement of the valve piston is provided on the nozzle body, and the valve piston has a spherical contact portion. And the valve stopper is configured to have a first spherical contact portion having the same or slightly larger radius as the contact portion at the portion where the contact portion of the valve piston contacts.

According to a ninth aspect of the present invention, in the vacuum forming apparatus for die casting, a valve stopper for guiding the valve tip guide and restricting the movement of the valve tip guide is provided on the nozzle body, and the valve tip guide has a conical surface shape. , And the valve stopper has a conical second contact portion at a portion where the contact portion of the valve tip guide contacts.

According to a tenth aspect of the present invention, there is provided a vacuum forming apparatus for die casting, wherein a valve stopper for guiding the valve tip guide and restricting the movement of the valve tip guide is provided on the nozzle body, and the valve tip guide has a spherical shape. The valve stopper has a contact portion, and the valve stopper has a conical second contact portion at a portion where the contact portion of the valve tip guide contacts.

Further, in the vacuum forming apparatus for die casting according to claim 11 of the present invention, a valve stopper for guiding the valve tip guide and restricting the movement of the valve tip guide is provided on the nozzle body, and the valve tip guide has a spherical shape. The valve stopper has a contact portion, and the valve stopper has a spherical second contact portion having a radius equal to or slightly larger than the contact portion at a portion where the contact portion of the valve tip guide contacts.

Further, in the vacuum forming apparatus for die casting according to claim 12 of the present invention, a heating means capable of controlling the temperature is provided on the nozzle body.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The nozzle body of the vacuum forming apparatus for die casting according to the present invention is a hot nozzle because it is supplied with heat from the mechanical nozzle by contact with the mechanical nozzle and is insulated from the mold. The molten metal in the nozzle body is kept in a molten state. A pressure chamber formed by a melt valve movable along the flow path and a valve guide for guiding a valve piston forming a part of the melt valve is provided in the nozzle body. The pressure chamber is connected to a pressure source via a connection pipe, and increases the pressure in the pressure chamber by compressed air from the pressure source to urge the molten metal valve to close the flow path. That is, the nozzle body is composed of a nozzle body, a valve guide, a valve stopper, and a nozzle base. One of the molten metal valves is provided with a valve piston movably provided in the valve guide, and an end of the valve piston. A valve tip guide is mounted, a valve spring provided in the valve tip guide, and a valve tip movably provided in the valve tip guide and urged by a valve piston and a valve spring. ing. The valve tip is pressed against the nozzle base by the movement of the valve piston and the displacement of the valve spring. The nozzle base forms an inlet of a flow path into which the injected molten metal flows, and the valve tip is urged to press the nozzle base so as to close the flow path of the nozzle base. When the flow path of the molten metal is closed in this way, the molten metal does not flow into the nozzle body from the contact portion between the valve chip and the valve base even when the product forming portion of the mold is decompressed to a state close to a vacuum. Absent. Further, the valve piston is pressed against the valve stopper due to the pressure in the pressure chamber and is brought into close contact with the valve stopper, so that the compressed air can be prevented from flowing out from the sliding portion between the valve piston and the valve guide.

As described above, in the vacuum forming apparatus for die casting according to the present invention, it is possible to keep the product forming portion of the mold in a reduced pressure state close to a vacuum. Therefore, when the product forming part of the mold is depressurized by the vacuum source and the flow path of the melt is opened in this state, the melt flows from the nozzle body into the product forming part of the mold. At this time, since the product forming section is in a vacuum state, the molten metal is filled into the product forming section and solidified without involving air. Therefore, almost no voids are generated due to the entrainment of air, and the accuracy and quality of the product can be improved.

Since the nozzle body is a hot nozzle as described above, the molten metal in the nozzle body can be maintained in a molten state, the temperature of the molten metal does not drop due to the sprue bush, and the product forming portion of the mold can be formed. The filling of the molten metal into the finely shaped portion and the ultrathin portion is facilitated, and insufficient filling is eliminated.

In particular, when molten metal flows between the nozzle body and the mold, heat escapes from the nozzle body to the mold via the molten metal,
Since the temperature of the nozzle main body cannot be maintained at a temperature suitable for die casting, it is necessary to reliably prevent the flow of the molten metal between the nozzle main body and the mold. In the present invention, a heat-resistant gasket and a gasket are provided between the respective parts, not only to improve airtightness, but also to prevent molten metal from flowing between the mold and the nozzle body, thereby ensuring heat insulation.

Also, since the contact portion between the valve tip and the nozzle base for opening and closing the flow path is formed of a conical surface and a conical surface, a spherical surface and a conical surface, or a spherical surface and a spherical surface, respectively, Even if the gap of the sliding portion is large or the valve tip is inclined, the valve tip and the nozzle base can be surely brought into close contact with each other.

Further, the contact portions of the valve piston and the valve stopper are each formed as a conical surface and a conical surface, or a spherical surface and a conical surface, respectively.
Or, since it is composed of a spherical surface and a spherical surface, the valve piston and the valve stopper can be surely brought into close contact even if the clearance between the sliding portion of the valve piston and the valve guide is large, and the compressed air in the pressure chamber is reduced. Outflow can be reliably prevented.

Furthermore, since the contact portion between the valve tip guide and the valve stopper is formed as a conical surface and a conical surface, a spherical surface and a conical surface, or a spherical surface and a spherical surface, respectively, the sliding portion between the valve piston and the valve guide is formed. Even if the gap is large, the valve tip guide and the valve stopper can be surely brought into close contact with each other, and the molten metal can be reliably prevented from flowing into the pressure chamber from the sliding portion between the valve tip guide and the valve stopper. .

On the other hand, by providing the nozzle body with a heating means capable of controlling the temperature, the nozzle body is heated not only by the heat supply from the mechanical nozzle but also by the heat of the heating means, so that the optimum temperature is rapidly reached. . For this reason, it is possible to shorten the time from the mounting of the mold to the start of molding. Such heating by the heating means is particularly effective when a long nozzle body is used or when a metal material having a high melting point is formed.

[0030]

FIG. 1 is a sectional view showing a state in which a vacuum forming apparatus for die casting according to one embodiment of the present invention is incorporated in a mold 22 and is mounted on a die casting machine. FIG. 2 is a sectional view showing the vacuum for die casting shown in FIG. It is a principal part expanded sectional view which shows the detailed structure of a shaping | molding apparatus. 3 and 4 are sectional views showing the state of the vacuum forming apparatus for die casting at the time of molding, and FIGS. 5 and 6 are side views of the vacuum forming apparatus for die casting as viewed from the molten metal outflow side and the molten metal inflow side. is there.

As shown in FIGS. 1 and 2, the fixed die 22a of the mold 22 is provided with a substantially cylindrical mounting hole 22d, and the nozzle body 11 is accommodated in the mounting hole 22d. The nozzle body 11 has a substantially cylindrical nozzle body 41, a nozzle base 42 provided at an end of the nozzle body 11 on the molten metal inflow side, and a valve guide provided between the nozzle body 41 and the nozzle base 42. 50 and a valve stopper 43. The nozzle body 41, the valve guide 50, the valve stopper 43, and the nozzle base 42 are set with a set screw 44 so as to penetrate them.
Are screwed and connected. The contact portion between the nozzle body 41 and the valve guide 50 is provided with a contact portion 41a having a convex conical surface and a contact portion 50a having a concave conical surface. The contact portion is provided with a contact portion 50b having a concave conical surface and a contact portion 43a having a convex conical surface, and further includes a valve stopper 43 and a nozzle base 42.
Are provided with a contact portion 43b having a concave conical surface and a contact portion 42a having a convex conical surface.
These contact portions 41a, 50a, 50b, 43a, 43
The close contact between b and 42a prevents outflow of the molten metal.

A nozzle tip 21 is attached to the end of the nozzle body 41 on the molten metal outflow side.
This nozzle tip 21 has a flange-shaped tip portion 21a on the outer periphery of the tip, and a screw portion 2 on the outer periphery of the other end.
1b is formed, and is fixed to the nozzle body 41 by screwing the screw portion 21b to a screw portion 41b formed in the end of the nozzle body 41. FIG.
As shown in FIG. 4, the slit groove 32 provided on the end face of the nozzle tip 21 in the molten metal inflow direction is for inserting a tool when the nozzle tip 21 is screwed into the nozzle body 41. Nozzle body 1 having the above configuration
1 and the nozzle tip 21 have a higher heat conductivity than heat-resistant steel or heat-resistant steel, for example, a heat conductivity of 0.3 cal / sec ·
It is made of a tungsten alloy having a temperature of at least cm. Further, a mechanical nozzle touch portion 42d is provided on the outer end surface of the nozzle base 42 on the molten metal inflow side.
An annular concave portion 41c that is compatible with a heat-resistant gasket described later is provided on the outer end surface on the molten metal outflow side.

The valve guide 50, which constitutes a part of the nozzle main body 11, is directed toward the inside of the nozzle body 41 as shown in FIGS. 2 and 7 to 10 in addition to the above-mentioned contact portions 50a and 50b. Truncated cone-shaped projection 50
i, a hole 50c with a bottom formed from the end face on the melt inflow side in the melt outflow direction, a connection hole 50d communicating from the outer peripheral surface to the hole 50c, and a plurality of flows provided around the hole 50c. It has a path 50e and a through hole 50f through which the above-mentioned set screw 44 passes. A valve piston 25 of a molten metal valve 60, which will be described in detail later, is slidably fitted in the hole 50c of the valve guide 50 so as to be movable in the direction in which the molten metal flows. The valve stopper 43 connected to the valve guide 50 has a ring shape as shown in FIGS.
The inner diameter of the hole 43g is set smaller than that of the hole 50c. For this reason, the valve stopper 43 is configured such that the valve piston 25 of the molten metal valve 60 that fits into the hole 50c of the valve guide 50 and a part of the valve tip guide 30 attached to the end thereof contact a part of both end surfaces. In this portion, a conical first contact portion 43c (FIG. 3) and a conical second contact portion 43d (FIG. 4) are provided. Further, similarly to the valve guide 50, a plurality of flow paths 43h provided around the hole 43g and communicating with the flow path 50e, and a through hole 43i through which the set screw 44 described above is provided.

On the other hand, the molten metal valve 60 is
A valve piston 25 having a sliding portion 25c that fits into the hole 50c and having a substantially convex shape and movably provided in the valve guide 50; And a valve spring 40 provided inside the valve tip guide 30. The valve tip guide 30 is movably provided in the valve tip guide 30, and a distal end portion protrudes outward from the valve tip guide 30. And a valve tip 45. The valve piston 25 and the valve tip guide 30 have conical contact portions 25a and 30a at opposite ends thereof, and are fixed so that they are in close contact with each other, and the molten metal flows between the contact portions 25a and 30a. It is configured so that it cannot pass. Also,
The valve tip guide 30 has an outer diameter that matches the inner diameter of the valve stopper 43 on the molten metal outflow side, and is set so that the outer diameter of the end on the molten metal inflow side is larger than that. Therefore, the valve tip guide 30
Is movable together with the valve piston 25 within a range of the length of the portion adapted to the valve stopper 43. The valve piston 25 and the valve tip guide 30
As described above, the conical contact portions 25b, 3c that contact the first contact portion 43c and the second contact portion 43d of the valve stopper 43 to stop the movement and increase the airtightness.
0b. The valve spring 40 is provided between the end face of the valve piston 25 and the end face of the valve tip 45, and is configured to urge the valve tip 45 toward the nozzle base 42. Further, the valve tip 45 moves together with the valve tip guide 30 when the valve piston 25 slides toward the nozzle base 42 due to the pressure of the pressure chamber 26 formed in the hole 50c. In addition, a portion of the end of the valve tip 45 facing the nozzle base 42 has a conical contact portion 45a.
Is provided. On the other hand, a conical contact portion 42b is provided at a portion of the nozzle base 42 facing the contact portion 45a of the valve chip 45. These contact portions 45a, 4
2b, when the valve piston 25 slides due to the pressure of the pressure chamber 26, the valve tip 45 moves together with the valve tip guide 30 and comes into contact with the nozzle base 42. At this time, the valve tip 45 and the valve piston 25
The valve spring 40 is displaced between the positions, and the valve tip 45 is pressed with a force proportional to the displacement, thereby sealing the flow path 42 e of the nozzle base 42. Since the outer diameter of the valve tip 45 is larger than the opening at the end of the valve tip guide 30, the valve tip 45 does not protrude from the valve tip guide 30.

On the other hand, compressed air is supplied to the pressure chamber 26 from a pressure source 28 (FIG. 1) via a connecting pipe 27, so that the internal pressure is increased. The connection pipe 27 is fixed so as to communicate with the connection hole 50d of the valve guide 50, and in order to prevent leakage of compressed air,
A heat-resistant gasket 29 is provided between the valve guide 50 and the connecting pipe 27.

The heat insulating ring 12 is made of a material having good heat resistance and low thermal conductivity, such as ceramic, and a material having mechanical strength enough to withstand screwing and pressing. A nozzle tip 21 is provided on an end surface of the heat insulating ring 12 on the emission side.
An annular concave portion 12a that fits the front end portion 21a is provided. As shown in FIG. 2, when the nozzle tip 21 penetrating the heat insulating ring 12 is fixed to the nozzle body 41 as shown in FIG.
a and the end surface of the nozzle body 41. The heat insulating ring 12 has an outer diameter that can be fitted into the heat insulating ring fitting portion 22ab at the end of the mounting hole 22d on the molten metal outflow side.

The heat-resistant gasket 14 is disposed between the heat insulating ring 12 and the nozzle body 41, and prevents the molten metal from flowing out or the air from flowing in between. The heat-resistant gasket 14 is made of a soft material such as gold or copper having some heat resistance, a metal O-ring made of stainless steel, Inconel, Hastelloy, or the like, a metal C-ring, a metal U-ring, or the like. 41 is formed so as to have a thickness that can be accommodated in the concave portion 41c and that slightly protrudes from the concave portion 41c when not pressed. This heat resistant gasket 14
As described above, the heat insulating ring 12 is
When fixed at one, they are compressed between them. The heat-resistant gasket 14 thus compressed acts to prevent the molten metal from flowing out between the mold 22 and the nozzle body 11 through the gap between the nozzle body 41 and the heat insulating ring 12. Further, it also acts to maintain the airtightness in the nozzle body 11. The above-described heat-resistant gasket 29 also has the same material and configuration as the heat-resistant gasket 14.

The gasket 47 made of an O-ring or the like is made of a heat-resistant material such as fluorine rubber or silicon rubber or a metal C-ring as described later when the temperature of the molten metal is high. It is housed in an annular groove 22aa provided on the inner circumference of the heat insulating ring fitting portion 22ab. The gasket 47 has mechanical elasticity in the radial direction, and has a fixed mold 22a and a heat insulating ring 1.
2 to prevent air from flowing into the gap between the fixed mold 22a and the heat insulating ring 12 therebetween.

The guide rings 23 and 24 have heat resistance,
The guide ring 2 is fitted outside so as to sandwich the nozzle body 11.
3 is engaged with the stepped portion in the mounting hole 22d and is positioned. The outer periphery thereof contacts the inner surface of the mounting hole 22d to support the nozzle body 11, and the mechanical nozzle touch portion 42d
Is positioned at an appropriate position.

The back plate 15 is fixed to the end surface of the fixed die 22a with screws 16 in order to prevent the nozzle body 11 and the guide rings 23 and 24 from dropping out of the mounting holes 22d.

The vacuum source 20 (FIG. 1) sucks air in the product forming section 10 ′ of the mold 22 to reduce the pressure to make a vacuum or a state close to a vacuum. The movable mold 22b is provided with an air escape groove 22ba and air escape holes 22bb, 22bc communicating with the product forming section 10 '. The air escape groove 22ba and the air escape holes 22bb, 22bc are configured to allow air to flow therethrough. When the air escape hole 22bc is connected to the vacuum source 20, the air escape groove 22ba, the air escape hole 22bb, The air in the product forming section 10 ′ is sucked by the vacuum source 20 through the 22 bc. Further, the movable die 22b is provided with a shut-off pin 48 for separating the product forming portion 10 'from the air escape groove 22ba. The shut-off pin 48 is slidable in the directions of arrows B and C in FIG. 1 (in the left-right direction in FIG. 2). The communication with the groove 22ba can be made or cut off.

In the vacuum forming apparatus for die casting having the above structure, when the die casting is started, first, the mold 22 is closed, and the fixed mold 22a and the movable mold 22b are brought into close contact with each other, and the state shown in FIG. 3 is obtained. In this state, the shut-off pin 48 is pulled out of the air escape groove 22ba as shown in FIG. 3, so that when the air is sucked by the vacuum source 20, the inside of the nozzle body 11 and the mold 22 The product forming section 10 'is decompressed and almost in a vacuum state. Thereafter, when the blocking pin 48 moves in the direction of arrow B, as shown in FIG. 2 or FIG. 4, the air escape groove 22ba is blocked,
The inside of the nozzle body 11 and the product forming section 10 'of the mold 22 are kept in a vacuum state.

In the state shown in FIG.
The seal when the pressure is reduced by the vacuum source 20 connected to the bc is as follows: the O-ring 47 and the heat-resistant gasket 14, the nozzle body 41 and the valve guide 50, the valve guide 50 and the valve stopper 43, the valve stopper 43 and the nozzle The close contact between the base 42 and the close contact between the valve chip 45 and the nozzle base 42 is maintained.

At this time, the valve chip 45
When the pressure in the pressure chamber 26 is increased by the compressed air from the pressure source 28, the pressure chamber 28 moves rightward in FIG. 3 together with the valve piston 25 and the valve tip guide 30, and the contact portion 45 a of the valve tip 45 becomes the contact portion of the nozzle base 42. 4
Contact 2b. Further, the valve piston 25 is further moved by the pressure of the pressure chamber 26, and the valve piston 2
The valve spring 40 is displaced between the nozzle tip 5 and the valve tip 45 already in contact with the nozzle base 42, and the contact portion 45 a of the nozzle tip 45 contacts the nozzle base 42 with a pressing force corresponding to the displacement of the valve spring 40. It is in close contact with the portion 42b and closes the flow path 42e of the nozzle base 42. Further, at this time, the contact portion 25b of the valve piston 25 abuts on the first contact portion 43c of the valve stopper 43, and the movement is restricted and the airtightness of the pressure chamber 26 is enhanced by tight contact.
The pressure in the pressure chamber 26 brings the contact portion 25b of the valve piston 25 into close contact with the first contact portion 43c of the valve stopper 43 even when the inside of the nozzle body 11 is in a vacuum state. The size is set to such an extent that the tip 45 does not move and keeps close contact with the nozzle base 42.

As shown in FIG. 2, when the air escape groove 22ba is shut off by the shut-off pin 48, the connection between the connecting pipe 27 and the pressure source 28 is released, and the pressure chamber 26 is connected to the atmosphere and depressurized. Is done. For this reason, the valve piston 25,
The pressing of the valve tip 45 toward the nozzle base 42 by the valve tip guide 30 and the valve spring 40 is released. After the connection between the connection pipe 27 and the pressure source 28 is released, the connection pipe 27 is connected to the vacuum source 20 and the pressure chamber 26
The inside may be in a vacuum state.

In this state, when the molten metal is pressurized by the plunger 3 of the die casting machine, the molten metal is injected from the mechanical nozzle 4 to the nozzle body 11. The valve tip 45 is pressed by the injection pressure at this time, and moves to the left in FIG. 4 together with the valve piston 25 and the valve tip guide 30. Thus, the valve tip 45 moves,
When the flow path 42e of the nozzle base 42 is opened, the molten metal flows into the nozzle body 11, and the flow path 50e of the valve guide 50
It flows into the product forming part 10 'from the nozzle tip 21 through the inside. At this time, since the inside of the nozzle body 11 and the product forming portion 10 'of the mold 22 are substantially in a vacuum state, the molten metal is filled into the product forming portion 10' without involving air.

At this time, the contact portion 30b of the valve tip guide 30 comes into close contact with the second contact portion 43d of the valve stopper 43, thereby preventing the molten metal from flowing into the sliding portion between the valve guide 50 and the valve piston 25. I'm preventing.
In this way, the molten metal flows into the valve chip 45 and
When the valve tip guide 30 moves to the middle left direction, the contact portion 30b of the valve tip guide 30
Close to. For this reason, the molten metal flows between the contact portion 45a of the valve tip 45 and the contact portion 42a of the nozzle base 42 and flows into the valve guide 50, but the contact portion 30b and the second contact portion as described above. By the closeness of 43d,
Sliding portion 25b between valve guide 50 and valve piston 25
Does not flow in between.

Thereafter, when the injection of the molten metal is stopped and the injection of the molten metal from the mechanical nozzle 4 is stopped, the connecting pipe 27 is connected to the pressure source 28 again, and the compressed air is sent into the pressure chamber 26 so that the molten metal valve 60 is released. Moves rightward in the figure as shown in FIG. The contact portion 45a of the valve tip 45 is brought into close contact with the contact portion 42a of the nozzle base 42 again by the pressure of the valve spring 40 and the pressure of the compressed air, and the contact portion 25b of the valve piston 25 is further brought into contact with the valve stopper 43.
And closes the first contact portion 43c to block the flow path.

On the other hand, the melt filled in the mold 22 is cooled and solidified there. As described above, since the molten metal does not flow in the vacuum and entrain the air, almost no cavities are generated inside the molded product. At this time,
The molten metal at the tip 21a of the nozzle tip 21 is also cooled and solidified. Thereafter, the movable mold 22b moves in the direction of the arrow A (FIG. 1) to open the mold 22, whereby the product section 10a, the runner section 10b, and the gate section 10d are integrated as shown in FIGS. The molded article 10 is taken out. At this time, since the nozzle body 11 is heated by the heat from the mechanical nozzle, the sprue portion 8c is not formed unlike the conventional molded product 8 shown in FIG.

As described above, when the molded article 10 is taken out, the temperature of the tip portion 21a of the nozzle tip 21 is rapidly restored to an appropriate temperature at which molding is possible by the heat of the central portion 11b of the nozzle body 11. If a material having good thermal conductivity is used for the nozzle body 11, it is possible to recover the temperature more rapidly.

At the time of the die casting, the molten metal tends to flow between the heat insulating ring 12 and the nozzle body 11.
The heat-resistant gasket 14 includes the heat insulating ring 12 and the nozzle body 11.
Is melted between the nozzle body 11 and the fixed mold 22a, so that the molten metal does not flow between the nozzle body 11 and the fixed mold 22a.

The temperature of the fixed mold 22a is much lower than the temperature of the molten metal.
If the gap 17 (FIG. 2) with the heat insulating ring fitting portion 22ab is made small, the molten metal solidifies before flowing into the interior, so that the molten metal does not flow.

The gas supplied from the pressure source 28 may be not only air but also a gas capable of preventing oxidation of metal.

FIGS. 17 and 18 are enlarged cross-sectional views of a main part showing a modified example in which a heater 18 is provided on the outer peripheral portion of the nozzle main body 11 as a heating means for heating the nozzle main body 11 in the embodiment shown in FIG. And a side view. The heater 18 has a temperature detection unit inside, and the nozzle body 1
The temperature control of 1 is performed. Reference numeral 18a denotes a lead wire of the heater 18, which is connected to a temperature control device (not shown). By providing the heater 18 in this manner, the temperature of the nozzle body 11 can be quickly raised to an appropriate temperature, and more efficient molding is facilitated. That is, the time for continuous molding can be extremely reduced. When the fixed mold 22a needs to be thickened and the nozzle main body 11 must be lengthened, it is particularly effective to provide a heating means such as a heater. Further, it is more effective to provide a heating means in the nozzle body for a die-cast metal material having a higher melting point.

In the modification shown in FIG. 17, a heat-resistant gasket 35 is further provided between the heat insulating ring 12 and the nozzle tip 21. The heat-resistant gasket 35 is formed between the concave portion 12 a of the heat insulating ring 12 and the tip 2 of the nozzle tip 21.
1a is sealed by being compressed between the nozzle tip 21 and the nozzle tip 21 and the screw portion of the nozzle body 11, which may be generated in the gap 34 between the fitting portion of the heat insulating ring 12 and the nozzle tip 21 due to the molten metal. Who is preventing.

In the valve chip 51 shown in FIG. 17, a contact portion 51a at the tip is formed in a spherical shape, and this contact portion 51a is formed in a conical contact portion 42b of the nozzle base 42.
The nozzle body 11 closes the flow path of the nozzle base 42 by being in close contact with the
This prevents the molten metal from flowing into the interior. Further, the contact portion 25d of the valve piston 25 is also formed in a spherical shape, and the contact surface 25d is in close contact with the conical first contact portion 43c of the valve stopper 43, thereby improving the airtightness of the pressure chamber 26. It has become. Further, the contact portion 30c of the valve tip guide 30 is also formed in a spherical shape,
This contact portion 30c is the second conical shape of the valve stopper 43.
The close contact with the contact portion 43d prevents the flow of the molten metal into the pressure chamber when filling the molten metal. As described above, by making the contact portion 51a of the valve tip 51, the contact portion 25d of the valve piston 25, and the contact portion 30c of the valve tip guide 30 spherical, the valve tip 51 is inclined with respect to the nozzle base 42 or the valve tip 51 The gap between the sliding part of the valve tip guide 30 and
Alternatively, the valve piston 25 is inclined with respect to the valve stopper 43, the gap between the sliding portion of the valve piston 25 and the valve guide 50 is increased, or the valve tip guide 30 is inclined with respect to the valve stopper 43, or the valve piston 25 and the valve Even if the gap between the sliding portions of the guide 50 becomes large, the gaps between the nozzle base 42 and the valve tip 51, between the valve piston 25 and the valve stopper 43, and between the valve tip guide 30 and the valve stopper 43 are surely secured. Can be sealed.

On the other hand, in the structure shown in FIG. 17, a gasket 52 made of a metal C-ring shown in FIGS. 22 and 23 is provided instead of the gasket 47 (FIG. 2) made of an O-ring fitted on the outer periphery of the heat insulating ring 12. ing. The gasket 52 is made of stainless steel, Inconel, Hastelloy, or the like, is positioned by a flange portion 12b provided on the outer periphery of the heat insulating ring 12, and is formed on the outer periphery of the heat insulating ring 12 and the inner periphery of the mounting hole 22d of the fixed mold 22a. Has been compressed between. Since the gasket 52 can further improve heat resistance as compared with an O-ring made of heat-resistant rubber or the like, even if the temperature of the molten metal is high and the temperature of the heat insulating ring 12 is high, the gasket 52 can be reliably sealed. .

In this modification, a shut-off pin 49 which can be cooled is used. The shut-off pin 49 has a cooling water channel 49b in which the cooling water 36 flows. As shown in FIGS. 17 and 19 to 21, the cooling water flow path 49 b is formed by partitioning a cavity in the shut-off pin 49 in the axial direction with a partition plate 49 a, as shown in FIG. 17. The cooling water 36 can be circulated through the upper and lower portions of the inside. By using such a cooling pin 49 which can be cooled, the molten metal filled in the product forming part 10 'is solidified, and the molten metal is released into the air escape groove 22ba.
Can be reliably prevented from flowing into the air. In addition, an annular concave portion 49c is provided on the outer periphery of the shut-off pin 49, and the O-ring 33 is housed therein.
Even if there is a large gap between them, the airtightness can be increased and the degree of vacuum in the product molded portion 10 'can be prevented from lowering.

The contact portions 51a and 42c between the valve tip 51 and the nozzle base 42 in FIG.
Further, the contact portion 25d and the first contact portion 43e of the valve piston 25 and the valve stopper 43 are respectively spherical, and the contact portion 30 of the valve tip guide 30 and the valve stopper 43 is further formed.
c and the second contact portion 43f are each formed by a spherical surface, whereby the valve piston 25 and the valve guide 5 are formed.
Even if the gap between the sliding part of 0 and the sliding part between the valve tip 51 and the valve tip guide 30 is large, or the valve tip 51 and the valve piston 25 are inclined,
Each contact portion can be surely brought into close contact. Therefore, it is possible to prevent the molten metal from flowing into the nozzle body 11 in a state close to a vacuum, and to reliably prevent the molten metal from flowing into the pressure chamber when filling the molten metal.

Further, in the structure shown in FIG.
The heat insulating ring 53 is eliminated by integrating the nozzle tip 21 shown in FIG.
It has been modified so that it can be directly screwed onto the. In the structure shown in FIG.
8 or a metal C ring 52 can be used.

[0061]

According to the present invention, since the product forming portion of the mold and the nozzle body can be sealed and brought into a vacuum state, the inflowing molten metal does not entrain the air, and the cavity of the molded product can be reduced. Occurrence can be prevented. For this reason, it is possible to eliminate shape defects and surface treatment defects caused by the occurrence of cavities, and it is possible to significantly improve the quality of products.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which a vacuum forming apparatus for die casting according to one embodiment of the present invention is incorporated in a mold and attached to a die casting machine.

FIG. 2 is an enlarged sectional view of a main part showing a detailed configuration of the vacuum forming apparatus for die casting shown in FIG.

FIG. 3 is an enlarged cross-sectional view of a main part showing a state when a vacuum is applied to a product forming part and a nozzle body in the vacuum forming apparatus for die casting shown in FIG. 2;

FIG. 4 is an enlarged sectional view of a main part showing a state when a molten metal is injected in the vacuum forming apparatus for die casting shown in FIG.

FIG. 5 is a side view of the melt forming side of the vacuum forming apparatus for die casting shown in FIG. 2;

6 is a side view of the vacuum forming apparatus for die casting shown in FIG. 2 on the molten metal inflow side.

FIG. 7 is a sectional view of the valve guide shown in FIG. 2;

8 is a side view of the valve guide shown in FIG. 7 on the molten metal inflow side.

FIG. 9 is a plan view of the valve guide shown in FIG. 7;

10 is a side view of the valve guide shown in FIG. 7 on the molten metal injection side.

FIG. 11 is a sectional view of the valve stopper shown in FIG. 2;

12 is a side view of the valve stopper shown in FIG. 11 on the molten metal inflow side.

13 is a side view of the valve stopper shown in FIG. 11 on the molten metal injection side.

FIG. 14 is a side view of the nozzle tip shown in FIG. 2 on the molten metal inflow side.

FIG. 15 is a side view showing a molded product molded by the vacuum molding apparatus for die casting shown in FIG. 1 and the like.

FIG. 16 is a plan view of the molded product shown in FIG.

FIG. 17 is an enlarged sectional view of a main part showing a modification example in which a heater is provided on the outer peripheral portion of the main body as a heating means for heating the nozzle main body in the embodiment shown in FIG. 2;

FIG. 18 is a side view of the molten metal inflow side of the vacuum forming apparatus for die casting shown in FIG.

FIG. 19 is a front view of the blocking pin shown in FIG. 17;

20 is a sectional view of the blocking pin shown in FIG. 19 taken along line GG.

FIG. 21 is a sectional view taken along line FF of the blocking pin shown in FIG. 20;

FIG. 22 is a sectional view of the metal C-ring shown in FIG.

FIG. 23 is a left side surface of the metal C ring shown in FIG. 14;

24 is an enlarged sectional view of a main part showing a modification in which the shape of the contact portion such as the valve tip shown in FIG. 2 and the like is changed and the heat insulating ring is changed to be directly attached to the nozzle body.

FIG. 25 is a sectional view showing a conventional die casting apparatus.

26 is a side view showing a molded product formed by the die casting device shown in FIG. 25.

FIG. 27 is a cross-sectional view showing a sprue bush used in the die casting apparatus shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Melting furnace 2 Sleeve 3 Plunger 4 Mechanical nozzle 4a Molten metal injection part 5 Mechanical nozzle heater 6 Sprue bush 6a Mechanical nozzle touch part 7 Mold 7a Fixed mold 7b Movable mold 8, 10 Molded product 8a, 10a Product part 8b, 10b Runner Part 8c sprue part 8d, 10d gate part 8 ', 10' product forming part 9 molten metal 9a molten metal surface 11 nozzle body 12, 55 heat insulating ring 12a concave part 12b flange part 14, 29, 25, 43 heat resistant gasket 15 back plate 16, 44 Set screw 17, 34 Gap 18 Heater 18a Lead wire 20 Vacuum source 21 Nozzle tip 21a Tip 21b Screw 22 Die 22a Fixed 22b Movable 22aa Groove 22ab Insulation ring fitting 22ba Air escape groove 22bb, 22bc Air escape hole 23, 2 Guide ring 25 Valve piston 26 Pressure chamber 27 Connecting pipe 28 Pressure source 30 Valve tip guide 31, 36 Cooling water 32 Slot groove 33, 47 Gasket 35 Heat resistant gasket 41 Nozzle body 41a Contact part 42 Nozzle base 42a, 42b, 42c Contact part 42d Mechanical nozzle touch part 43 Valve stopper 43a, 43b Contact part 43c, 43e First contact part 43d, 43f Second contact part 43g Hole 43h Flow path 43i Through hole 44 Set screw 45 Valve tip 45a, 45b Contact part 48, 49 Blocking pin 49a Partition plate 50 Valve guide 50a, 50b Contact part 50c Hole part 50d Connection hole 50e Flow path 50f Through hole 51 Valve chip 51a Contact part 52 Gasket 53 Heat insulation ring 60 Melt valve

Claims (12)

[Claims] A nozzle body, a nozzle tip fixed to the nozzle body, heat insulation between a mold, the nozzle body and the nozzle tip, and a position of the nozzle body in the mold and the metal mold. A heat-insulating ring fitted to the mold and the nozzle tip with a clearance fit; a compressible heat-resistant gasket provided between the nozzle body and the heat-insulating ring to prevent the passage of molten metal; and the heat-insulating ring and the mold. A gasket that is provided between the mold and seals the product forming portion of the mold to maintain a vacuum, a valve piston movably provided in the nozzle body, and attached to an end of the valve piston. A valve tip guide, a valve spring provided in the valve tip guide, and a valve piston and a valve movably provided in the valve tip guide. A valve tip that is urged by a spring to open and close the flow path of the molten metal in the nozzle body; and a molten metal valve that is formed in the nozzle body and that when the internal pressure increases, the molten metal valve is opened. A pressure chamber that urges and closes the flow path in the nozzle body by the valve tip; a pressure source that adjusts the pressure in the pressure chamber; and a vacuum source that puts the product forming part of the mold into a vacuum state. The vacuum forming apparatus for die casting, wherein the molten metal valve is opened when the molten metal is injected, and the molten metal is poured into the product forming part of the mold from the flow path. 2. A nozzle body, which is fixed to the nozzle body, maintains heat insulation between the mold and the nozzle body, maintains the position of the nozzle body in the mold, and fits in the mold with a clearance fit. A heat-insulating ring that is provided between the nozzle body and the heat-insulating ring, and that is a compressible heat-resistant gasket that prevents the passage of molten metal; and a heat-insulating ring that is provided between the heat-insulating ring and the mold. A gasket for sealing to keep the product molding section vacuum, a valve piston movably provided in the nozzle body, a valve tip guide attached to an end of the valve piston, and the valve tip guide A valve spring provided in the nozzle tip guide and movably provided in the valve tip guide. A melt valve configured to open and close a passage; and a melt valve formed in the nozzle body. When the internal pressure increases, the melt valve is urged to flow through the nozzle body by the valve chip. A pressure chamber for closing the pressure chamber, a pressure source for adjusting the pressure in the pressure chamber, and a vacuum source for vacuuming the product forming portion of the mold. The molten metal valve opens when the molten metal is injected and opens. A vacuum forming apparatus for die casting, wherein a molten metal is poured from a flow path into a product forming section of the mold. 3. The valve tip has a conical contact portion, and the nozzle body has a conical contact portion at a portion where the contact portion of the valve tip contacts. Or the vacuum forming apparatus for die casting according to 2. 4. The valve tip has a spherical contact portion, and the nozzle body has a conical contact portion at a portion where the contact portion of the valve tip contacts. 3. The vacuum forming apparatus for die casting according to 2. 5. The valve tip has a spherical contact portion, and the nozzle body has a spherical contact at a portion where the contact portion of the valve tip contacts the same or a slightly larger radius than the contact portion. 2. The device according to claim 1, wherein
Or the vacuum forming apparatus for die casting according to 2. 6. The valve body is provided with a valve stopper for guiding the valve tip guide and restricting the movement of the valve piston, the valve piston having a conical contact portion, and the valve stopper being provided in the nozzle body. The part where the contact part of the said valve piston contacts has a 1st contact part of a conical surface shape, The Claim 1, 2, 3, characterized by the above-mentioned.
6. The vacuum forming apparatus for die casting according to 4 or 5. 7. The nozzle body is provided with a valve stopper for guiding the valve tip guide and restricting the movement of the valve piston, the valve piston having a spherical contact portion, and the valve stopper being provided with the valve stopper. A first conical surface is formed at the portion where the contact portion of the valve piston contacts.
5. The method according to claim 1, further comprising a contact portion.
Or a vacuum forming apparatus for die casting according to 5. 8. The valve body is provided with a valve stopper that guides the valve tip guide and restricts the movement of the valve piston, the valve piston having a spherical contact portion, and the valve stopper being provided with the valve stopper. 6. The valve piston according to claim 1, wherein the contact portion of the valve piston has a spherical first contact portion having the same or slightly larger radius as the contact portion. Vacuum forming equipment for die casting. 9. The valve body is provided with a valve stopper that guides the valve tip guide and restricts movement of the valve tip guide, wherein the valve tip guide has a conical contact portion, 9. The die-casting device according to claim 1, wherein the stopper has a second conical contact portion at a portion where the contact portion of the valve tip guide contacts. Vacuum forming equipment. 10. The valve body includes a valve stopper that guides the valve tip guide and restricts movement of the valve tip guide, wherein the valve tip guide has a spherical contact portion, 9. The vacuum for die-casting according to claim 1, wherein the valve tip guide has a conical second contact portion at a portion where the contact portion of the valve tip guide contacts. Molding equipment. 11. The valve body is provided with a valve stopper for guiding the valve tip guide and restricting the movement of the valve tip guide, wherein the valve tip guide has a spherical contact portion. Has a spherical second contact portion having the same or slightly larger radius as the contact portion at the portion where the contact portion of the valve tip guide contacts.
The vacuum forming apparatus for die casting according to 3, 4, 5, 6, 7, or 8. 12. The nozzle body according to claim 1, further comprising a heating means capable of controlling the temperature.
The vacuum forming apparatus for die-casting according to 5, 6, 7, 8, 9, 10 or 11.