JP2000280061A - Vacuum molding device for die casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate casting cavity by removing entrainment of air when a molten metal is injected. SOLUTION: A passage of a molten metal is closed by a seal pin 25, and a product molding part 10' of a mold is decompressed by a vacuum source. Also, a reverse flow of the molten metal in a nozzle main body 11 is prevented by a nozzle chip 26, so that inside of the nozzle main body 11 is filled with the molten metal. At that time, if the passage of the molten metal is opened by moving the seal pin 25, the molten metal flows into the product molding part 10' of the mold. The molten metal is charged into the product molding part 10' without entrainment of the air, and is solidified.

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. 26 is a sectional view showing a general structure of a die casting apparatus. In FIG. 26, 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 section 8a, the runner section 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. 26, the sprue bush 6 in the die casting device 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 so as to be pressed against the mechanical nozzle touch portion 6a (see FIG. 28) 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. Further, a valve tip movable along the flow path is provided in the nozzle body.
The valve tip contacts the contact portion of the nozzle body when the molded product is removed from the mold, closes the flow path, and acts to prevent the backflow of the molten metal in the nozzle body. Also,
The valve chip opens when the molten metal is injected, and flows the molten metal from the flow path into the product forming portion of the mold. On the other hand, a sealing pin is provided on the movable mold, and the movable mold has a structure for opening and closing the flow path of the molten metal injected from the nozzle body. Further, the sealing pin 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, a vacuum source for evacuating the product forming section is connected to the mold, and the inside of the product forming section is evacuated to prevent air from being entrained when the molten metal is injected.

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. Further, a valve tip movable along the flow path is provided in the nozzle body. The valve tip contacts the contact portion of the nozzle body when the molded product is removed from the mold, closes the flow path, and acts to prevent the backflow of the molten metal in the nozzle body. The valve chip opens when the molten metal is injected, and flows the molten metal from the flow path into the product forming portion of the mold. On the other hand, a sealing pin is provided on the movable mold, and the movable mold has a structure for opening and closing the flow path of the molten metal injected from the nozzle body. Further, the sealing pin 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, a vacuum source for evacuating the product forming section is connected to the mold, and the inside of the product forming section is evacuated to prevent air from being entrained when the molten metal is injected.

In the vacuum forming apparatus for die casting according to a third aspect of the present invention, a nozzle tip as a molten metal injection section is fixed to a tip end portion of the nozzle body, and the nozzle tip insulates the mold and heats the mold. A heat insulating ring for maintaining the inside position is fixed to the nozzle body. The nozzle body is fixed to a mold with a fixing screw via a heat insulating ring. 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. Further, a valve tip movable along the flow path is provided in the nozzle body.
The valve tip contacts the contact portion of the nozzle body when the molded product is removed from the mold, closes the flow path, and acts to prevent the backflow of the molten metal in the nozzle body. Also,
The valve chip opens when the molten metal is injected, and flows the molten metal from the flow path into the product forming portion of the mold. On the other hand, a sealing pin is provided on the movable mold, and the movable mold has a structure for opening and closing the flow path of the molten metal injected from the nozzle body. Further, the sealing pin 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, a vacuum source for evacuating the product forming section is connected to the mold, and the inside of the product forming section is evacuated to prevent air from being entrained when the molten metal is injected.

In the vacuum forming apparatus for die casting according to claim 4 of the present invention, in order to maintain the position of the nozzle body in the mold, the heat insulating ring, the nozzle body, and the heat insulating spacer are assembled and fixed in the mold in this order. It is fixed with screws. Further, the fitting of the heat insulating ring and the mold, and the fitting of the heat insulating ring and the nozzle body are always clearance fits at room temperature and at the time of temperature rise during molding, respectively, 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. Further, a valve tip movable along the flow path is provided in the nozzle body. The valve tip contacts the contact portion of the nozzle body when the molded product is removed from the mold, closes the flow path, and acts to prevent the backflow of the molten metal in the nozzle body. The valve chip opens when the molten metal is injected, and flows the molten metal from the flow path into the product forming portion of the mold. on the other hand,
The movable die of the mold is provided with a sealing pin, and has a structure for opening and closing the flow path of the molten metal injected from the nozzle body. Further, the sealing pin 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, a vacuum source for evacuating the product forming section is connected to the mold, and the inside of the product forming section is evacuated to prevent air from being entrained when the molten metal is injected.

Further, in the vacuum forming apparatus for die casting according to claim 5 of the present invention, a tip portion of the sealing pin facing the flow path of the molten metal and a contact portion in contact with the tip portion of the sealing pin respectively fit. It has a conical surface.

Further, in the vacuum forming apparatus for die-casting according to claim 6 of the present invention, the tip of the sealing pin facing the flow path of the molten metal has a spherical surface, and the contact portion that contacts the tip of the sealing pin. Is a conical surface that fits the spherical surface of the tip of the sealing pin.

In the vacuum forming apparatus for die-casting according to claim 7 of the present invention, the front end of the sealing pin facing the flow path of the molten metal and the contact section in contact with the front end of the sealing pin are suitable. It is spherical.

Further, in the vacuum forming apparatus for die casting according to claim 8 of the present invention, the contact portion of the valve tip has a conical surface, and the contact portion of the nozzle body which contacts the contact portion of the valve tip also has a conical shape. It has become something to do.

Further, in the vacuum forming apparatus for die-casting according to claim 9 of the present invention, the contact portion of the valve chip has a spherical surface shape, and the contact portion of the nozzle body with which the valve chip contact portion contacts has a conical surface shape. It has become something to do.

Further, in the vacuum forming apparatus for die casting according to claim 10 of the present invention, the contact portion of the valve tip has a spherical shape, and the contact portion with which the contact portion of the valve tip of the nozzle body contacts also has a spherical shape. It has become.

[0020]

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 valve tip movable along the flow path is provided in the nozzle body. The valve chip closes the flow path to prevent the molten metal in the nozzle main body from flowing backward, and acts so that the inside of the nozzle main body is always filled with the molten metal.

The movable mold has a sealing pin which is movable in the axial direction. When the mold is closed and connected to a vacuum source, the sealing pin moves to the fixed mold. The tip portion is pressed against the contact portion between the nozzle tip and the nozzle body, and the flow path of the molten metal is closed. At this time, since the sealing pin is made of a material having low thermal conductivity, the amount of heat transmitted to the sealing pin and lost is very small. When the flow path of the molten metal is closed in this way, even if the product forming portion of the mold is decompressed to a state close to a vacuum, the sealing pin and the nozzle tip,
The molten metal does not flow from the contact portion of the nozzle body to the product forming portion of the mold.

As described above, in the vacuum molding apparatus for die casting of the present invention, it is possible to keep the product molding portion of the mold in a reduced pressure state close to a vacuum. Therefore, the pressure of the product forming portion of the mold is reduced by the vacuum source. In this state, when the sealing pin is moved to open the flow path of the melt, the melt flows into the product forming portion of the mold. At this time, the product forming part is in a vacuum state, and since the second forming cycle, since the molten metal is filled in the nozzle body by the valve tip, the molten metal is formed without entraining air. The part is filled and solidifies. Therefore, almost no voids are generated due to the entrainment of air, and the accuracy and quality of the product can be improved.

As described above, since the nozzle body is a hot nozzle, the molten metal in the nozzle body can be maintained in a molten state. 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 the 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, the front end of the sealing pin for opening and closing the flow path in the fixed mold side and the contact portion of the nozzle tip or the nozzle main body that comes into contact with the front end of the sealing pin are formed as a conical surface and a conical surface, respectively. Since it is composed of a spherical surface and a conical surface or a spherical surface and a spherical surface, even if the sealing pin is inclined or there is a gap between the sealing pin and the sliding part of the movable die, the sealing pin and the nozzle tip or nozzle body Can be surely brought into close contact with the contact portion.

Further, since the contact portion of the valve tip which opens and closes the flow path and the contact portion of the nozzle body which comes into contact with the valve tip are constituted by 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 valve tip is inclined or there is a gap between the valve chip and the sliding portion of the nozzle body, the contact portion between the valve chip and the nozzle body can be surely brought into close contact.

[0027]

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 cross-sectional views showing the state of the vacuum forming apparatus for die casting at the time of molding and the like, 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. It is.

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 shape, and has a flange portion 11a on the outer periphery. A nozzle tip 21 is provided at the end of the nozzle body 11 on the melt outflow side.
Is attached. The nozzle tip 21 has a flange-shaped tip portion 21a on the outer periphery of the tip, and a screw portion 21d is formed on the outer periphery of the other end portion. The screw portion 21d is provided inside the end portion of the nozzle body 11. It is fixed to the nozzle main body 11 by being screwed into the formed screw portion 11f. As shown in FIG. 10, the slit groove 32 provided on the end face of the nozzle tip 21 in the melt inflow direction is used for inserting a tool when the nozzle tip 21 is screwed into the nozzle body 11. It is. The nozzle body 11 and the nozzle tip 21 having the above configuration have a higher heat conductivity than heat-resistant steel or heat-resistant steel, for example, a heat conductivity of 0.3.
It is made of a tungsten alloy having a cal / sec · cm · ° C. or higher. Further, an annular concave portion 11g adapted to a heat-resistant gasket described later is formed on the outer end surface of the nozzle body 11 on the melt outflow side.
Is provided.

Inside the nozzle body 11, there is provided a valve tip 26 movable along a flow path through which the molten metal flows. The valve tip 26 has an outer diameter that matches the inner diameter of the hollow portion 11 e that connects to the flow path inside the nozzle body 11, and comes into contact with the conical contact portion 11 c that becomes the flow path for the molten metal in the nozzle body 11. It has a conical contact portion 26a. Further, as shown in FIGS. 2 and 7 to 9, the valve chip 26 has a groove 26c on its outer periphery for facilitating the flow of the molten metal.

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 fixing the nozzle tip 21 penetrating the heat insulating ring 12 to the nozzle body 11 as shown in FIG.
And between the nozzle body 11 and the end face thereof. 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 11, and prevents the molten metal from flowing out between the heat-insulating ring 12 and the nozzle body 11. This heat resistant gasket 14
Is made of a metal O-ring, a metal C-ring, a metal U-ring, or the like made of a soft material such as gold or copper having some heat resistance, stainless steel, Inconel, Hastelloy, or the like. It is formed in such a size that it can be accommodated in the inside and has a thickness that slightly protrudes from the concave portion 11g when not pressed. This heat-resistant gasket 14, as described above,
When the heat insulating ring 12 is fixed to the nozzle body 11,
Compressed in between. 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 11 and the heat insulating ring 12.

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 or the like 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 23 is externally fitted to the nozzle body 11 so as to sandwich the flange portion 11a, and is positioned by locking the guide ring 23 to the step in the mounting hole 22d.
The nozzle body 11 is supported in contact with the inner surface of 2d, and the mechanical nozzle touch portion 11h 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.

On the other hand, in the movable mold 22b, the tip 25a faces the flow path of the molten metal at the center of the nozzle tip 21 and can move in the axial direction (directions of arrows D and E in FIG. 1) toward the flow path. Is provided.
When the mold 22 is closed and connected to a vacuum source described later, the sealing pin 25 moves in the direction of the nozzle chip 21 and comes into contact with a contact portion 21 b serving as a flow path end of the nozzle chip 21. Is pressed. Thereby, when the product forming part 10 ′ of the mold 22 is decompressed, the nozzle tip 21
This prevents the molten metal from flowing into the product forming section 10 'from the flow path, and increases the airtight state of the product forming section 10' to make it close to a vacuum. This sealing pin 25
Is formed of a material having good heat resistance and low thermal conductivity, such as ceramics, to prevent the temperature of the nozzle tip 21 from dropping when the nozzle tip 21 comes into contact.

The vacuum source 20 (FIG. 1) sucks air in the product forming portion 10 ′ of the mold 22 to reduce the pressure, thereby bringing the vacuum to a state close to a vacuum. The fixed mold 22b is provided with an air escape groove 22ba and air escape holes 22bb, 22bc communicating with the product forming portion 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. By sliding the shut-off pin 48, the product molded portion 10 'and the air escape groove 22ba are communicated or shut off. be able to.

In the above configuration, the airtightness in the product forming portion 10 ′ of the mold 22 and the nozzle body 11 is determined by the gasket
7 and the heat-resistant gasket 14, and the sealing pin 25 and the nozzle tip 21 are kept in close contact with each other.
In particular, the tip 25a of the sealing pin 25 and the nozzle tip 21
Contact portions 21b are formed of conical surfaces that fit together, and when they come into close contact with each other, the molten metal cannot pass therethrough. In order to maintain such close contact, the sealing pin 25
Is set to such a size that the sealing pin 25 does not move and the sealing pin 25 and the nozzle tip 21 can be kept in close contact with each other even when the product forming section 10 ′ is in a vacuum state. I have. In addition, the nozzle tip 21 and the heat insulating ring 1
2, the gap between the heat insulating ring 12 and the fixed mold 22a, and the molten metal flowing from the screw portion 21d of the nozzle tip 21 pass through the heat-resistant gasket 14 and the gasket 47 which are fixed by compression. Therefore, the structure cannot be made to flow between the nozzle body 11 and the mold 22.

In the vacuum molding apparatus for die casting having the above structure, when the die casting is started, first, the mold 22 is closed, the fixed mold 22a and the movable mold 22b are brought into close contact with each other, and the state shown in FIG. Pin 25 is arrow D
Is moved in the direction of
The state shown in FIG. 4 is brought into close contact with the first contact portion 21b. In this state, the shut-off pin 48 is drawn out of the air escape groove 22ba as shown in FIG. 4, 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 shut-off pin 48 moves in the direction of arrow B, the air escape groove 22ba is shut off, and the inside of the nozzle body 11 and the product forming portion 10 'of the mold 22 are kept in a vacuum state.

In this state, the sealing pin 25 is pointed by the arrow E
In the state shown in FIG. 2, the molten metal is pressurized by the plunger 3 of the die casting machine, and the molten metal is injected from the machine nozzle 4 to the nozzle body 11. The injection pressure at this time presses the valve chip 26, and FIG.
Move to the middle left direction to open the flow path of the nozzle body 11. As a result, the molten metal flows into the nozzle main body 11, and flows from the nozzle tip 21 into the product forming section 10 'through the groove of the valve tip 26.

As described above, the product forming section 10 ′ of the mold 22.
The molten metal filled therein is cooled and solidified there. Thereafter, the movable product 22b moves in the direction of the arrow A (FIG. 1) to open the mold 22, and the molded product 10 is taken out.

When the molded product 10 is taken out as described above, at this time, the molten metal in the nozzle body 11 tries to return to the same level as the molten metal surface 9a of the melting furnace 1 and tries to flow backward.
At the same time, the valve tip 26 moves in the direction of the contact portion 11c of the nozzle body 11 and comes into close contact therewith, shuts off the flow path, and prevents the backflow of the molten metal.

Here, when the next molding cycle starts, similarly to the first molding cycle described above, the mold 2
2 is closed, the fixed mold 22a and the movable mold 22b come into close contact with each other,
The state shown in FIG. 3 is obtained. At this time, the molten metal whose backflow is prevented by the nozzle tip 26 is filled in the nozzle body 11. Here, as described above, the sealing pin 2
5 moves so that its tip 25a comes into close contact with the contact portion 21b of the nozzle tip 21, and the vacuum source 20 and the air escape hole 22b
is connected, and the inside of the product forming section 10 'is brought into a vacuum state. Then, when the sealing pin 25 moves in the direction E and at the same time the molten metal pressurized is injected, the valve chip 26
Moves and the molten metal flows into the product forming section 10 '. As described above, at this time, the molten metal in which the backflow is prevented by the nozzle tip 26 is filled in the nozzle main body 11 and there is almost no air in the nozzle main body 11, so that the molten metal entrains air. It is filled into the product forming part 10 'without any processing.

Here, when the movable mold 22b moves in the direction of arrow A again to open the mold 22, the movable mold 22b opens as shown in FIGS.
The molded product 10 in which the product portion 10a, the runner portion 10b, and the gate portion 10d are integrated as shown in FIG. 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.

When the molded article 10 is taken out as described above, the temperature of the tip portion 21a of the nozzle tip 21 is rapidly restored to an appropriate temperature at which molding can be performed 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.

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

FIGS. 13 and 14 are enlarged sectional views of essential parts showing a modification of the embodiment shown in FIG. 2 in which a heater 18 is provided on the outer periphery of the nozzle body 11 as a heating means for heating the nozzle body 11. 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 nozzle body 11 and the nozzle tip 21
Temperature can be accelerated to an appropriate temperature, and more efficient molding is facilitated. That is, the time for continuous molding can be extremely reduced. In addition, fixed type 2
When it is necessary to increase the thickness of the nozzle 2a and the nozzle 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. 13, 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.

The tip 25b of the sealing pin 25 in FIG. 13 is formed in a spherical shape.
Closes the contact portion 21b of the conical surface of the nozzle tip 21 to block the flow path of the nozzle tip 21, thereby preventing the molten metal from flowing into the product forming portion 10 'which is in a state close to a vacuum due to the reduced pressure. . Since the tip portion 25b of the sealing pin 25 has a spherical surface as described above, the sealing pin 25 comes into contact with the nozzle chip 21 in an inclined state due to play in the sliding portion of the sealing pin 25. Even so, the flow path of the nozzle tip 21 can be reliably sealed. An annular groove 25c is provided on the outer periphery of the sealing pin 25, and an O-ring 37 is fitted in the annular groove 25c. The O-ring 37 is provided between the sealing pin 25 and the movable mold 22.
b, is compressed between the sealing pin fitting portion 22bd of the movable die 22b and the air flows in through the gap even if there is a large gap between the sealing pin 25 and the sealing pin fitting portion 22bd of the movable die 22b. The product forming part 1 of the mold 22 is kept airtight so as not to
It is provided to maintain a vacuum degree of 0 '.

On the other hand, in the structure shown in FIG. 13, a metal C-ring shown in FIGS. 18 and 19 is used in place of the gasket 47 (FIG. 2) formed of an O-ring made of heat-resistant rubber or the like fitted on the outer periphery of the heat insulating ring 12. Is provided. The gasket 40 made of this metal C ring is
It is made of stainless steel, Inconel, Hastelloy, or the like, and is positioned by a flange portion 12b provided on the outer circumference of the heat insulating ring 12, and is compressed between the outer circumference of the heat insulating ring 12 and the inner circumference of the mounting hole 22d of the fixed mold 22a. Have been. Since the gasket 40 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 40 can be reliably sealed. .

In this modified example, the contact portion 26b at the tip of the valve chip 26 is formed in a spherical shape.
The flow path is closed by closely contacting the conical contact portion 11c of the nozzle body 11. Thus, the valve tip 2
By making the contact portion 26b of No. 6 spherical, even if there is a large gap between the valve chip 26 and the sliding portion of the nozzle body 11, the contact portion can be reliably brought into contact.

In this modification, a shut-off pin 49 that 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. 13 and 15 to 17, the cooling water flow path 49b is formed by partitioning the cavity in the shut-off pin 49 in the axial direction with the partition plate 49a, as shown in FIG. 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 blocking pin 49, and the O-ring 38 is housed in the annular concave portion 49c.
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.

FIG. 20 shows that the nozzle tip 21 shown in FIG. 2 and the like are integrated with the nozzle body 11 so that the heat insulation ring 27 is directly attached to the nozzle body 11 by screwing. It is a principal part sectional view which shows the example of a change comprised by the nozzle base 33. The heat insulating ring 27 is provided with a screw portion 27a on the inner peripheral surface thereof. The screw portion 27a is screwed into a screw portion 11i provided on the outer periphery near the tip end of the nozzle main body 11, thereby forming the nozzle main body. 11 is fixed. In addition, an annular concave portion 11g is formed on the step near the tip of the nozzle body 11.
, Where the heat-resistant gasket 14 is stored. The nozzle body 11 includes a nozzle body 42 on the melt outflow side and a nozzle base 33 attached to the melt inflow side. The nozzle body 42 is provided with a hollow portion 11e in which the valve chip 26 is accommodated. The hollow portion 11e is largely opened in the inflow direction of the molten metal, and the nozzle base 33 is fixed to the opening portion by screwing. . Between the nozzle body 42 and the nozzle base 33, a heat-resistant gasket 41 housed in a concave portion 42a of the nozzle body 42 is provided. Further, the nozzle base 33 is provided with a contact portion 33a with which the contact portion 26b of the valve chip 26 contacts. In this modified example, both the contact portions 26b and 33a are formed in a spherical shape. With such a spherical surface, even when there is a large gap between the valve chip 26 and the sliding portion of the nozzle main body 11, the valve chip 26 can be surely brought into contact with the nozzle base 33 in a state of close contact. In the structure shown in FIG. 20, a heater 18 and a gasket 40 made of a metal C-ring can be used.
5 and the blocking pin 48 may be changed to those having the structure shown in FIG.

The contact portion 21c provided at the tip of the nozzle main body 11 in FIG. 20 is formed of a spherical surface, and the tip portion 25b of the sealing pin 25 having the spherical surface is in close contact with the contact portion 21c. It is configured. The spherical surface of the contact portion 21c is set so as to have the same slightly larger radius as the spherical surface of the tip portion 25b of the sealing pin 25. In this manner, by forming both the tip portion 25b of the sealing pin 25 and the contact portion 21c of the nozzle body 11 as spherical surfaces, there is a gap between the sliding portion of the sealing pin 25 and the movable mold 22b, and the like. The sealing pin 25 can be brought into close contact with the nozzle body 11 even if it is tilted with respect to the nozzle body 11, and the product forming section 1 in a vacuum holding state
It is possible to prevent the molten metal from flowing into 0 '.

FIG. 21 is a sectional view of a main part showing a modified example in which the structure for fixing the nozzle main body 11 shown in FIG. 2 and the like to the mold is changed. FIGS. 23 and 24 show the molten metal outflow side and the molten metal inflow side. It is the side view seen. When the nozzle tip 21 is screwed and attached to the nozzle body 11, a heat insulating ring 12 is provided between the nozzle tip 21 and the nozzle body 11.
And a heat-resistant gasket 14 are interposed therebetween. The nozzle body 11, the nozzle tip 21 and the heat insulating ring 12 are attached to a mold by a ring-shaped fixing screw 51. That is, the fixing screw 51 has a screw portion formed on the outer periphery thereof, and is screwed into a screw portion formed on the inner periphery of the mounting hole 22 d of the fixed die 22 to contact the positioning projection 12 c of the nozzle tip 12. The positioning projection 12c is pressed against the step 22e in the mounting hole 22d to position and fix the positioning projection 12c. As shown in FIGS. 24 and 25, a slot 51a for engaging a tool when screwing the fixing screw 51 is provided on an end surface of the fixing screw 51 in the nozzle touch direction. The gasket 30 made of an O-ring is housed in an annular step 22f provided in the step 22e in the mounting hole 22d, and is fixed to the fixed mold 22a.
And the heat insulating ring 12. With such a configuration, the structure for fixing the nozzle body 11 and the like to the fixed mold 22a can be concentrated near the end in the melt outflow direction, and the overall length of the nozzle body 11 can be shortened. .

FIG. 22 shows that the nozzle tip 21 is integrated with the nozzle body 11 as shown in FIG.
FIG. 22 is a cross-sectional view of a main part showing a modified example in which 1 is composed of a nozzle body 42 and a nozzle base 33 and is fixed to a mold with fixing screws 51 as shown in FIG. 21. In this structure, the heat insulating ring 12, the nozzle body 11, and the heat insulating spacer 50 are fitted in the mounting hole 22d of the fixed mold 22a in this order, and are fixed by the fixing screw 51. That is, the heat-insulating ring 12 has an outer diameter set so that the molten metal outflow side is fitted to the heat-insulated ring fitting portion 22ab of the fixed mold 22a, and a positioning protruding portion 12c that protrudes radially around the outer periphery of the molten metal inflow side end. Is provided. In addition, the nozzle body 11 has an outer diameter at the end in the molten metal outflow direction that matches the inner diameter of the heat insulating ring 12, and a radially protruding positioning / fixing flange portion 11a is provided at a substantially central outer periphery. ing. The fixing screw 51 is connected to the flange portion 11a of the nozzle body 11 through the heat insulating spacer 50.
And the positioning protrusion 12c of the heat insulating ring 12 is attached to the mounting hole 2
These are fixed so as to be pressed against the step 22e in 2d. Also in this structure, it is possible to shorten the overall length of the nozzle body 11.

[0056]

According to the present invention, since the product forming portion of the mold is sealed and brought into a vacuum state and the inside of the nozzle body can be always filled with the molten metal, the inflowing molten metal does not involve air. It is possible to prevent the occurrence of a cavity in a molded product. 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 sectional view of a main part showing a state when a mold is closed in the vacuum molding apparatus for die casting shown in FIG.

FIG. 4 is an enlarged cross-sectional view of a main part showing a state when the inside of a product forming section is evacuated 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 chip shown in FIG. 2;

8 is a side view of the valve chip shown in FIG. 7 on the melt outflow side.

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

FIG. 10 is a side view of the nozzle tip shown in FIG. 2 on the melt inflow side.

FIG. 11 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. 12 is a plan view of the molded product shown in FIG.

FIG. 13 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;

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

FIG. 15 is a front view of the blocking pin shown in FIG. 13;

FIG. 16 is a sectional view taken along line GG of the blocking pin shown in FIG. 15;

FIG. 17 is a sectional view taken along line FF of the blocking pin shown in FIG. 16;

FIG. 18 is a sectional view of the metal C-ring shown in FIG.

FIG. 19 is a left side view of the metal C ring shown in FIG. 18;

20 is an enlarged sectional view of a main part showing a modified example in which the heat insulating ring is directly attached to the nozzle body in the vacuum forming apparatus for die casting shown in FIG. 2 and the like, and the nozzle body is changed to a nozzle body and a nozzle base.

FIG. 21 is an enlarged sectional view of a main part showing a modified example in which the structure for fixing the heat insulating ring, the nozzle body and the like to the mold in the vacuum forming apparatus for die casting shown in FIG. 2 and the like is changed.

22 is an enlarged sectional view of a main part showing a modification in which the heat insulating ring is directly mounted on the nozzle body by a gap fitting in the vacuum forming apparatus for die casting shown in FIG. 21.

23 is a side view of the melt forming side of the vacuum forming apparatus for die casting shown in FIG. 21.

24 is a side view of the melt forming side of the vacuum forming apparatus for die casting shown in FIG. 21.

FIG. 25 is a side view of the fixing screw shown in FIG. 21;

FIG. 26 is a cross-sectional view showing a conventional die casting apparatus.

FIG. 27 is a side view showing a molded article formed by the die casting apparatus shown in FIG. 26;

FIG. 28 is a sectional view showing a sprue bush used in the die casting forming apparatus shown in FIG. 26;

[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 surface 11 nozzle body 11b central part 11c, 11d contact part 11e hollow part 11f screw part 11g concave part 11h nozzle touch part 11i screw part 12, 27 Heat insulating ring 12a Concave portion 12b Flange portion 12c Positioning protrusion 14, 35 Heat resistant gasket 15 Back plate 16 Set screw 17 Gap 18 Heater 18a Lead wire 20 Vacuum source 21 Nozzle tip 21a Tip 21b, 21c Contact portion 22 Mold 22a Fixed type 22b Movable type 22aa Groove part 22ab Heat insulating ring fitting part 22ba Air escape groove 22bb, 22bc Air escape hole 22d Mounting hole 22e Step 23, 24 Guide ring 25 Sealing pin 25a, 25b Tip 25c Ring groove 26 Valve tip 26a , 26b Contact part 26c Groove part 30, 40, 47 Gasket 31, 36 Cooling water 32 Slot groove 37, 38 O-ring 48, 49 Cut-off pin 49a Partition plate 50 Heat insulating spacer 51 Fixing screw 51a Slot part

Claims (10)

[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 molds and seals the product molding portion of the mold to maintain a vacuum; and a gasket that is provided in a movable state in the nozzle body, and the molded article is taken out from the mold. A valve tip for closing the flow path of the molten metal in the nozzle body to prevent backflow of the molten metal in the nozzle body; and a valve chip provided on the movable mold of the mold to open and close the flow path of the molten metal injected from the nozzle body. And a vacuum source for vacuuming the product forming part of the mold. The sealing pin opens when the molten metal is injected, and opens from the flow path to the product forming part of the die. A vacuum forming apparatus for die casting. 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 in a vacuum; and a gasket that is provided movably in the nozzle body and closes a flow path of the molten metal in the nozzle body when a molded product is taken out from the mold. A valve tip for preventing backflow of the molten metal in the nozzle body, a sealing pin provided on a movable die of the die for opening and closing a flow path of the molten metal injected from the nozzle body, and a product molding of the die. Section in vacuum A vacuum source, wherein the sealing pin is opened when the molten metal is injected, and the molten metal is poured into the product molding portion of the mold from the flow path. 3. 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 fixing screw for fixing the nozzle body to the mold via the heat insulating ring; and a molten metal provided between the nozzle body and the heat insulating ring. A gasket provided between the heat-insulating ring and the mold, which seals the product forming part of the mold to keep a vacuum, and moves into the nozzle body. A valve tip that is provided in a possible state and closes the flow path of the molten metal in the nozzle body when a molded product is taken out of the mold to prevent backflow of the molten metal in the nozzle body; A sealing pin provided on a movable mold of the mold, for opening and closing a flow path of the molten metal injected from the nozzle body; and a vacuum source for vacuuming a product forming portion of the mold, wherein the sealing pin A vacuum forming apparatus for die casting, wherein the apparatus is opened when the molten metal is injected, and the molten metal is poured from the flow path into a product forming section of the mold. 4. 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, a heat insulating spacer and a fixing screw for fixing the nozzle body while maintaining heat insulation between the mold and the nozzle body, and provided between the nozzle body and the heat insulating ring to prevent the passage of molten metal. A heat-resistant gasket that can be compressed, a gasket that is provided between the heat-insulating ring and the mold, and seals the product molding part of the mold to maintain a vacuum, and that is movable in the nozzle body. A valve tip provided to close a flow path of the molten metal in the nozzle body when a molded product is taken out from the mold and to prevent a backflow of the molten metal in the nozzle body; and provided in a movable mold of the mold. La A sealing pin for opening and closing the flow path of the molten metal injected from the nozzle body; and a vacuum source for vacuuming the product forming part of the mold. A vacuum forming apparatus for die casting, wherein the apparatus is opened and a molten metal is poured from the flow path into a product forming section of the mold. 5. The sealing pin according to claim 1, wherein a tip of the sealing pin facing the flow path of the molten metal and a contact of the sealing pin contacting the tip of the sealing pin each have a conical surface. 5. The vacuum forming apparatus for die casting according to 2, 3, or 4. 6. A tip of the sealing pin facing the flow path of the molten metal has a spherical surface, and a contact portion that contacts the tip of the sealing pin conforms to a spherical surface of the tip of the sealing pin. 5. The vacuum forming apparatus for die casting according to claim 1, wherein the apparatus comprises a conical surface. 7. The sealing pin according to claim 1, wherein a tip portion of the sealing pin facing the flow path of the molten metal and a contact portion contacting the tip portion of the sealing pin are each formed of a suitable spherical surface. The vacuum forming apparatus for die casting according to 2, 3, or 4. 8. 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. The vacuum forming apparatus for die casting according to claim 2, 2, 3, 4, 5, 6, or 7. 9. 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. The vacuum forming apparatus for die casting according to 2, 3, 4, 5, 6, or 7. 10. The valve tip has a spherical contact portion, and the nozzle body has a spherical contact portion at a portion where the contact portion of the valve tip contacts. The vacuum forming apparatus for die casting according to any one of claims 3, 4, 5, 6, and 7.