JP2000176620A - Nozzle for vacuum die casting forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the formation of casting blow hole by eliminating the entrapment of air at injecting time of molten metal. SOLUTION: Relating to a nozzle 11 connected with a molten metal flow-out hole 1a in a die casting machine at the one end and directed to a molten metal flow-in hole in a die 22 at the other end, molten metal flowing passages 17, 18, 19 are formed in the inner part of the nozzle body. Further, a valve chip 15 pushed with a coil spring 16 in the inner part is disposed so as to be shiftable and the molten metal flowing passages 17, 18, 19 are closed with the valve chip 15 pushed with the coil spring 16 at the ordinary time. On the other hand, the molten metal flowing passages 17, 18, 19 are opened by pushing back the valve chip 15 with the injection pressure of the molten metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art FIG. 13 is a sectional view showing the structure of a conventional die casting apparatus. In this figure, the nozzle 4 and the die 7 of the die casting machine have an inclination of about 10 degrees with respect to the horizontal, and the molten metal injection part 4a of the nozzle 4 is connected to the molten metal 9 (molten metal) in the melting furnace 1. Is arranged at a position higher than the upper surface 9a of the molten metal, and has a structure for preventing dripping from the molten metal injection part 4a.

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

At this time, air is filled in the nozzle 4, the sprue bush 6, and the product forming portion 8 '. 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,
As shown in FIG. 14, the molded product 8 in which the product portion 8a, the runner portion 8b, and the sprue portion 8c are integrated is taken out.
The molded product 8 is formed along with the sprue portion 8c and the runner portion 8b.
Is cut off at the gate portion 8d to form a product. 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.

The sprue bush 6 in the die casting apparatus is cooled by a cooling water 31 circulating in an outer peripheral portion, as shown in FIGS.
Is configured to prevent the sprue portion 8c from being cut off halfway due to insufficient cooling when is opened.

The outer periphery of the nozzle 4 is heated by the nozzle heater 5 so that the molten metal does not solidify in the nozzle 4. Further, the injection portion 4a of the nozzle 4 is connected to the nozzle touch portion 6a of the sprue bush 6 so that the molten metal does not leak.
It is set in a state pressed against.

[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, as described above, the cavity is exposed to the surface when the runner portion 8b is cut off or subjected to a cutting process to form a hole, and a correct shape cannot be obtained. 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 nozzle capable of shutting off a flow path of a molten metal and maintaining a vacuum in a mold to eliminate air entrapment during injection of the molten metal. Another object of the present invention is to provide a nozzle for a vacuum die casting apparatus which eliminates the occurrence of cavities.

[0010]

According to a first aspect of the present invention, there is provided a nozzle for a vacuum die casting apparatus, wherein one end of the nozzle is connected to a molten metal outlet of a die casting machine, and the other end is directed to a molten metal inlet of a mold. In addition, a molten metal flow path is formed inside the nozzle body, and a valve chip pressed by an elastic member is movably disposed inside the nozzle body, and the molten metal flow is normally performed by the valve chip pressed by the elastic member. While closing the path, the injection pressure of the molten metal pushes the valve tip back,
It is characterized in that the molten metal channel is opened.

According to a second aspect of the present invention, there is provided a nozzle for a vacuum die casting apparatus, wherein a molten metal flow path in a nozzle body closed by the valve tip is connected to a vacuum source together with a product forming part of a mold. When the inside of the product forming section is sucked by the vacuum source, the inside of the molten metal flow path in the nozzle body is also sucked, so that the inside of the product forming section of the mold and the inside of the molten metal flow path are close to a vacuum.

According to a third aspect of the present invention, there is provided a nozzle for a vacuum die-casting molding apparatus, wherein the nozzle body is composed of a nozzle body and a nozzle base, and a heat-resistant gasket as a sealing member is provided therebetween by compression. It is characterized by the following.

A nozzle for a vacuum die casting apparatus according to a fourth aspect of the present invention is characterized in that a heat-resistant metal material having higher thermal conductivity than heat-resistant steel is used for the nozzle body.

According to a fifth aspect of the present invention, in the nozzle for a vacuum die casting apparatus, the valve tip has a conical or spherical contact portion, while the nozzle body is in contact with the contact portion of the valve tip. It is characterized by having a conical contact portion in the portion to be formed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a nozzle for a vacuum die casting apparatus according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing a state in which the nozzle of the present invention is mounted on a die casting machine, FIG. 2 is an enlarged sectional view showing the configuration of the nozzle and the mold of FIG. 1 and FIG. 3 is a detailed view of the nozzle.

As shown in FIG. 1, a nozzle 1 according to the present invention
1 is attached to the tip of the die casting machine 1, and the tip 11 a of the nozzle 11 is attached to the sprue bush 21 of the mold 22.
It is set in a state pressed against. The nozzle body is
As shown in FIGS. 2 and 3, the nozzle body 12 includes a substantially cylindrical nozzle body 12 and a nozzle base 13 screwed to a rear end of the nozzle body 12 via a heat-resistant gasket 14. The valve chip 15 is movably disposed in the internal space of the nozzle base 13. The nozzle body 12, the nozzle base 13, and the valve chip 15 are all coaxial internal flow paths 17, 18, 1.
The tip 11a of the nozzle body 12 is pressed against the nozzle touch portion 21b of the sprue bush 21, and the rear end of the nozzle base 13 is connected to the molten metal outlet 1a of the die casting machine 1.

On the other hand, the valve tip 15 is shown in FIGS.
As shown in the figure, the cylindrical body 15b and the body 1
An outer peripheral flange 15c formed overhanging at the tip of 5b;
And a conical contact portion 15a formed at the tip thereof. The body portion 15b is slidably inserted into a substantially cylindrical hole 12a formed in the nozzle body 12, and the contact portion 1
5a is in close contact with the conical contact portion 13a formed at the end of the internal flow path 18 on the nozzle base 13 side, and the internal flow path 18 on the nozzle base 13 side and the internal flow path 17 on the nozzle body 12 side Cut off. Also, an outer peripheral space 15e of the valve chip 15 is provided between the contact portion 15a and the outer peripheral flange 15c.
A pair of through-holes 15d communicating between the inner passage 19 and the inner passage 19 are formed. The valve tip 15 is urged by a coil spring 16 compressed and housed in a hole 12a formed in the nozzle body 12, and as shown in FIG.
Is pushed back by the injection pressure of the molten metal from the die casting machine 1 while being in close contact with the contact portion 13a formed on the nozzle base 13, and as shown in FIG.
c is pushed to a position where it engages with the step 12b on the nozzle body 12 side, so that a flow path 13b of the molten metal is formed between the contact portion 15a and the contact portion 13a. The nozzle 1
Even when the inside of the nozzle 1 is decompressed to a state close to a vacuum, the valve tip 15 does not move due to the urging force of the coil spring 16, and the contact portion 15 a is in close contact with the contact portion 13 a and the molten metal is It does not flow.

It should be noted that the nozzle body 12 having the above configuration
And the nozzle base 13 has a higher heat conductivity than heat-resistant steel or heat-resistant steel, for example, a heat conductivity of 0.3 cal / sec · c.
A tungsten alloy having a temperature of at least m · ° C. is used. By using such a material having good thermal conductivity, heat transfer to the nozzle tip portion (injection portion) is performed in a short time, so that the molding start time after attaching the mold can be shortened and the molding cycle can be shortened. Also becomes easier. In addition, a nozzle heater 24 having a built-in temperature detecting unit is provided on the outer periphery of the nozzle body 12 and the nozzle base 13 so that the molten metal in the nozzle 11 can be kept in a molten state. The nozzle heater 24 is connected to a temperature control device (not shown) and controls the temperature of the nozzle 11.

The heat-resistant gasket 14 is made of a heat-resistant soft material such as gold or copper, a metal O-ring, a metal C-ring, or a metal U-ring made of stainless steel, Inconel, Hastelloy, or the like. In addition, the airtightness inside the nozzle 11 is maintained, and the molten metal is prevented from flowing out to the outer peripheral surface of the nozzle 11 through the threaded portion between the nozzle body 12 and the nozzle base 13. The coil spring 16 is made of heat-resistant Inconel or ceramics.

The vacuum source 20 (FIG. 1) sucks air in the product forming section 10 ′ of the mold 22 to reduce the pressure, thereby bringing the vacuum to a state close to a vacuum. As shown in FIG. 2, the movable mold 22b has an air escape groove 2 communicating with the product forming portion 10 '.
2ba and air escape holes 22bb, 22bc are provided. The air escape groove 22ba and the air escape hole 22b
b and 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 and the air escape hole 22bc are connected.
The air in the product forming unit 10 ′ is sucked by the vacuum source 20 via bb and 22 bc. The movable die 22b is provided with a shut-off pin 23 that separates the product forming part 10 'from the air escape groove 22ba. The shut-off pin 23 is slidable in the directions of arrows B and C in FIG. 1 (left and right directions in FIG. 2). It can communicate with or block the groove 22ba.

A sprue bush 21 is fitted in the fixed mold 22a, and a molten metal flow passage 21 provided therein is provided.
The injection portion 11a of the nozzle 11 is pressed against the nozzle touch portion 21b on the inlet side of a, and the outlet 21c of the molten metal flow path 21a communicates with the product forming portion 10 'of the mold 22. As in the prior art, an annular water passage 21d for circulating the cooling water 31 through a cooling water passage 22aa provided in the fixed mold 22a is provided on the outer peripheral portion of the sprue bush 21.

Next, a description will be given of the die-casting vacuum forming using the nozzle 11 having the above structure. When the molding 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 to be in a state shown in FIG. In this state, the shut-off pin 23 is in a state of being pulled out from the air escape groove 22ba. Therefore, when air is sucked by the vacuum source 20, the inside of the nozzle 11 and the product forming portion 10 'of the mold 22 are moved. The pressure is reduced to a state close to a vacuum. At this time, even if the pressure inside the nozzle 11 is reduced, the molten metal does not flow into the nozzle 11 because the valve tip 15 is pressed by the coil spring 16 and is in close contact with the nozzle base 13.
As a result, it is possible to maintain the product forming portion 10 'of the mold 22 in a reduced pressure state close to a vacuum. Then, the shut-off pin 23
Moves in the direction of arrow B, as shown in FIG. 2, the air escape groove 22ba is shut off, and the inside of the nozzle 11 and the mold 22
Is held in a state close to a vacuum.

An air escape groove 22b formed by the shut-off pin 23
When the molten metal is injected by the plunger 3 of the die-casting machine 1 at the same time as the cut-off of a, the injection pressure presses the valve tip 15 in the nozzle 11 and moves to the left as shown in FIGS. As a result, the contact portion 15a of the valve chip 15 is separated from the contact portion 13a of the nozzle base 13, and a flow path 13b therebetween is formed. Thereby, the molten metal flow paths 17, 18, and 19 in the nozzle 11 communicate with each other, and the molten metal flows into the product forming portion 10 'via the sprue bush 21 to fill the internal space. At this time, since the inside of the nozzle 11 and the product forming section 10 'of the mold 22 are substantially in a vacuum state, the molten metal does not entrain the air and the product forming section 10'
Is filled in.

Thereafter, when the injection of the molten metal from the nozzle 11 is completed, the valve tip 15 is moved rightward by the urging force of the coil spring 16, and as shown in FIG.
a is in close contact with the contact portion 13a of the nozzle base 13 so that the flow path 1
Block 3b.

On the other hand, the molten metal filled in the product forming portion 10 ′ of the mold 22 is cooled by the mold 22 and solidified. As described above, since the molten metal is injected in a vacuum and does not entrain air, almost no cavities are generated inside the molded product. Thereafter, the movable mold 22b moves in the direction of the arrow A (FIG. 1) to open the mold 22, so that the product section 10a, the runner section 10b, and the sprue section 1 as shown in FIGS.
The molded product 10 in which the Oc and the gate portion 10d are integrated is taken out.

FIG. 11 shows a second embodiment of the present invention, which has the same structure as the above embodiment except that the contact portion 15a at the tip of the valve chip 15 is formed in a spherical shape. Detailed description is omitted. By bringing the contact portion 15a into close contact with the conical contact portion 13a formed on the nozzle base 13, it is possible to prevent the molten metal from flowing into the nozzle 11 brought into a state close to a vacuum due to the reduced pressure. By making the contact portion 15a of the valve chip 15 a spherical surface, even if the valve chip 15 is tilted with respect to the nozzle body 12 due to play in the sliding portion between the valve chip 15 and the nozzle body 12, the hermetic sealing is ensured. be able to.

FIG. 12 shows a third embodiment of the present invention. In this embodiment, the valve chip 15 includes a valve chip body 15g having a concave portion 15f formed at a tip thereof,
The ball 41 is integrally fixed to the concave portion 15f, and the same effects as in the second embodiment can be obtained. In this embodiment, the communication hole 15d is provided to be inclined along the fitting portion 15f.

[0028]

As described above, according to the nozzle for a vacuum die-casting apparatus according to the present invention, the product forming portion of the mold and the inside of the nozzle can be sealed and brought into a vacuum state. Air is not involved, and the formation of cavities in the molded product 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 sectional view showing a state in which a nozzle for a vacuum die casting apparatus according to the present invention is attached to a die casting machine.

FIG. 2 is a sectional view showing a nozzle and a mold according to the present invention.

FIG. 3 is an enlarged cross-sectional view of the nozzle shown in FIG.

FIG. 4 is an enlarged view of a valve tip of the nozzle.

FIG. 5 is a sectional view taken along line EE of FIG. 4;

FIG. 6 is a sectional view showing the state of the nozzle and the mold when the pressure inside the mold is reduced.

FIG. 7 is a sectional view showing a state of a nozzle and a mold when a molten metal is injected into the mold.

FIG. 8 is an enlarged sectional view of the nozzle in FIG. 7;

FIG. 9 is a side view of a molded product using the nozzle.

FIG. 10 is a front view of the molded product shown in FIG. 9;

FIG. 11 is a sectional view of a nozzle showing a second embodiment of the present invention.

FIG. 12 is a sectional view of a nozzle showing a third embodiment of the present invention.

FIG. 13 is a cross-sectional view illustrating an example of a conventional die casting apparatus.

FIG. 14 is a side view of a molded article molded by a conventional die casting molding apparatus.

FIG. 15 is a sectional view of a sprue bush used in a conventional die casting apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Die-casting machine 1a Molten metal outlet 10 'Product forming part 11 Nozzle 12 Nozzle body 13 Nozzle base 15 Valve chip 15a Contact part 16 Coil spring 17 Internal flow path of nozzle body 18 Internal flow path of nozzle base 19 Internal flow path of valve chip Reference Signs List 20 vacuum source 21b nozzle touch part 22 mold

Claims (5)

[Claims] 1. A nozzle having one end connected to a molten metal outlet of a die casting machine and the other end directed to a molten metal inlet of a mold, wherein a molten metal flow path is formed inside the nozzle body, and The valve chip pressed by the elastic member is movably disposed, and the molten metal flow path is normally closed by the valve chip pressed by the elastic member, while the valve chip is pushed back by the injection pressure of the molten metal, and the molten metal flow path is closed. A nozzle for a vacuum die casting apparatus characterized by being opened. 2. The molten metal flow path in the nozzle body closed by the valve tip is connected to a vacuum source together with a product forming part of a mold, and when the inside of the product forming part is sucked by the vacuum source, the inside of the nozzle body is opened. 2. The nozzle for a vacuum die casting apparatus according to claim 1, wherein the inside of the molten metal flow path is also sucked, so that the product forming portion of the mold and the inside of the molten metal flow path are close to a vacuum. 3. The vacuum die-casting apparatus according to claim 1, wherein the nozzle body comprises a nozzle body and a nozzle base, and a heat-resistant gasket as a sealing member is provided between the nozzle body and the nozzle base. Nozzle. 4. The vacuum forming apparatus for die casting according to claim 1, wherein a heat-resistant metal material having a higher thermal conductivity than heat-resistant steel is used for the nozzle body. 5. The valve tip has a conical or spherical contact portion, and the nozzle body has a conical contact portion at a portion where the contact portion of the valve tip contacts. Item 5. A nozzle for a vacuum die casting apparatus according to any one of Items 1 to 4.