JP2500863B2 - Vacuum die casting mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mold having excellent airtightness for injection molding in which a cavity is vacuum-depressurized.

[Prior art]

Generally, the vacuum die casting method is known as a method for producing a casting by injecting molten metal at high speed into a vacuumed mold. According to this method, there is an advantage that a thin-walled casting having a complicated shape can be mass-produced with high precision and high precision.

However, on the other hand, this method has a drawback that bubble cavities are easily generated in the casting. In order to eliminate this drawback, attempts have been made to make the inside of the mold as vacuum (depressurized) as possible.

As one of the trials, an apparatus using a vacuum die casting mold is used as shown in FIG.

That is, according to the present invention, the fixed die 4, the movable movable die 6 that contacts the fixed die 4 to form the cavity 5 and the runner 51, the injection sleeve 7 and the sprue bush 70 that guide the molten metal to the cavity 5. A vacuum device 81 having an injection plunger 71 that slides in the injection sleeve 7 and the sprue bush 70 to inject molten metal into the cavity 5, and a vacuum exhaust passage 8 that sucks the cavity 5 into a depressurized state.
And consists of.

In addition, in the above device, the fixed mold 4 and the movable mold 6 are
A cooling pipe 9 is provided therein, and an extrusion pin 72 that penetrates the movable die 6 and communicates with the cavity 5 is provided therein. In the figure, reference numeral 10 is a fixed base, 11 is a fixed platen arranged thereon, 12 is a movable platen, 41 is a fixed block, and 61 is a movable block.

Therefore, in the above device, the movable die 6 is moved in the left-right direction by a hydraulic piston (not shown). And
A cavity 5 is formed by the movable mold 6 corresponding to the fixed mold 4. In addition, the mold is clamped between the two molds.

In molding, first, the inside of the cavity 5 is depressurized by the vacuum device 81 via the vacuum exhaust passage 8. Then, the molten metal is pressed by the injection plunger 71 and press-fitted into the cavity 5. The pyrolysis gas generated in the cavity 5 is discharged to the outside of the cavity 5 through the vacuum exhaust passage 8. The fixed mold 4 and the movable mold 6 are cooled by a cooling pipe 9. Then, after the molten metal has cooled and solidified, the movable die 6 is retracted to open between the fixed die 4 and the movable die 6, and the extrusion pin 72
The product casting in the cavity 5 is extruded by.

[Problems to be solved]

However, the conventional die for vacuum die casting has the following problems.

That is, air is introduced into the cavity 5 through the gap between the extrusion pin 72 and the insertion hole of the movable die 6 through which the molten metal is injected after the inside of the cavity 5 is evacuated and until the molten metal is injected. . In addition, the runner is provided through the insertion hole of the cooling pipe 9 provided in the fixed die, the contact surface between the fixed platen 11 and the fixed die block 41, and between the fixed die 4 and the outer periphery of the sprue bush 70.
51, air also enters the cavity 5. Air similarly enters through the fitting surface between the sprue bush 70 and the fixed platen 11 or between the sprue bush 70 and the injection sleeve 7.

Therefore, the degree of vacuum in the cavity 5 is lowered, which in turn causes the generation of porosity.

Further, the most important point regarding the above-mentioned air intrusion is the problem of air intrusion between the sprue bush 70 and the injection sleeve 7. This point will be explained with reference to FIG. 7. The contact surface between the sprue bush 70 and the injection sleeve 7
At 701, when air 88 enters the runner 702 from this contact surface, the air 88 violently collides with the surface of the molten metal 75 that is about to be inserted into the cavity 5 under vacuum.

Therefore, an air trap is generated on the surface of the molten metal,
Splashes 750 of molten metal. And this splash 750,
After passing through the cavity 5 not yet filled with the molten metal and the vacuum exhaust passage 8, it enters the vacuum apparatus. Therefore, it may cause a failure of the vacuum device.

Further, the air intrusion on the contact surface 701 also enters the inside of the molten metal filled in the cavity 5 to generate the porosity as described above.

As described above, the air intrusion between the sprue bush 70 and the injection sleeve 7 has a great adverse effect on the molten metal in the runner 702 and the molten metal 5, and is a problem that must be particularly prevented.

The present invention has been made in view of the above conventional problems, and secures a vacuum pressure reduction state in the cavity and the runner,
An object of the present invention is to provide a die for vacuum die casting, which can prevent the occurrence of cavities and the failure of the vacuum device.

[Means for solving problems]

The present invention relates to a fixed mold, a movable movable mold that forms a cavity and a runner communicating with the cavity by contacting the fixed mold, the movable mold that communicates with the runner for introducing molten metal into the cavity, and the runner. A sprue bush having an inner diameter larger than the inner diameter of the spout, an injection sleeve communicating with the sprue bush, an injection plunger that slides in the injection sleeve and the sprue bush and injects molten metal into the cavity, and the cavity. A vacuum die cast comprising a vacuum exhaust path for sucking the inside into a depressurized state, wherein a fixed block is arranged adjacent to the fixed mold, and a seal material is interposed between the fixed mold and the movable mold. The movable blocks are arranged adjacent to each other, and a sealing material is interposed between them, and the fixed block penetrates the fixed mold. A cooling pipe inserted into the movable mold, a cooling pipe inserted through the movable block into the movable die, and an extrusion pin penetrating the movable block and the movable die into the cavity. At the contact surface between the sprue bush and the injection sleeve, a sealing material is interposed between the sprue bush and the injection sleeve, and a seal is provided on the outer circumference of the sprue bush between the sprue bush and the fixed die. A die for vacuum die casting in which a material is interposed is provided.

A packing, a gasket, or the like is used as the sealing material. In addition, examples of the material thereof include a heat resistant elastic body such as a fluorine O-ring and a silicon rubber member, and a combination thereof can be used.

[Action and effect]

In the present invention, as in the above-mentioned configuration, the seal member is provided between the contact surface between the sprue bush and the injection sleeve and between the sprue bush and the fixed die. Therefore, ensure that the cavity and oil passage are in a vacuum depressurized state,
It is possible to provide a vacuum die casting mold capable of preventing the occurrence of a blowhole and preventing the failure of the vacuum device.

〔Example〕

First Embodiment A mold according to this embodiment will be described with reference to FIGS. 1 to 3.

That is, the mold of this example has a fixed mold 4 as shown in FIG.
And the cavity 5 and the runner 51 in contact with the fixed mold 4.
A movable die 6 that forms a mold, an injection sleeve 7 and a sprue bush 70 that guide molten metal into the cavity 5, and an injection that slides inside the injection sleeve 7 and the sprue bush 70 to inject molten metal into the cavity 5. It is composed of a plunger 71 and a vacuum exhaust passage 8 for sucking the inside of the cavity 5 in a depressurized state.

Then, in this mold, a fixed block 41 is arranged adjacent to the fixed mold 4, and a contact plate 2 and a packing 3 as a seal material are interposed between them.

Further, a movable block 61 is disposed adjacent to the movable mold 6, and a contact plate 2 and packing 3 similar to the above are disposed between them.
Intervene.

Further, the fixed mold 4 is provided with a cooling pipe 9 inserted through the fixed block 41 and the contact plate 2, and the movable mold 6 is also provided.
Also, the cooling pipe 9 inserted through the movable block 61 and the contact plate 2 is provided. In addition, an extruding pin 72 that penetrates the movable block 61, the contact plate 2, and the movable die 6 and communicates with the cavity 5 is provided. In the figure, reference numeral 13 is a cut-off pin that shuts off the passage in vacuum, reference numeral 91 is a gap between the cooling pipe 9 and the fixed block 41 and movable block 61, and reference numeral 721 is movable with the extrusion pin 72. It is a gap with the block 61. Both gaps are drawn large in the drawing.

A sprue bush 70 connected to the injection sleeve 7 is disposed at the tip of the injection sleeve 7, and the sprue bush 70 and the injection sleeve 7 are provided between the sprue bush 70 and the injection sleeve 7.
Between the 70 and the fixed mold 4, an O-ring 31 is used as a sealing material.
Intervene.

The contact plate 2 includes the fixed die 4 and the fixed block.
Use the same shape as the size of the gap between 41 and.

The packing 3 is made of a thin plate made of silicon rubber. The packing 3 is located between the contact plate 2 and the movable die 6 and is located at the intermediate portion a of the push pin 72.
Etc.

Further, the packing 3 is provided between the contact plate 2 and the fixed mold 4 and between the corresponding plate 2 and the movable mold 6, and also in the vicinity b of the tip of the cooling pipe 9.

The packing 3 is also provided between the contact plate 2 and the fixed block 41, between the plate 2 and the movable block 61, and in the vicinity c of both ends of the plate 2.

On the other hand, the O-ring 31 arranged around the sprue bush 70 is made of a fluororesin annular body. The O-ring 31
Is the outer circumference of the sprue bush 70,
It is provided between the 70 and the fixed mold 4 at d. Also, the O-ring 31
Is also provided at a connecting portion e which is a contact surface between the end surface of the sprue bush 70 and the injection sleeve 7.

Since the mold of this example is configured as described above, it has the following effects.

That is, in the mold of this example, the contact plate 2 and the packing 3 are interposed as described above. Therefore, the fixed die 4, the fixed block 41, the movable die 6, the movable block 61, the extrusion pin 72,
Air entering through the gap with the cooling pipe 9 can be blocked by the plate 2 and the packing 3.

In the mold of this example, the O-ring 31 is also provided around the sprue bush as described above. Therefore, the air that enters through the gap between the sprue bush 70, the fixed die 4, and the injection sleeve 7 can be completely blocked by the O-ring 31.

In addition, in this example, the packing interposition position (a,
b, c, d, e) and the number of interventions (5, 3, none) were changed, and the ultimate vacuum degree during decompression was tested. The results are shown in Table 1.

As is known from Table 1 above, the packing 3 is a, b, c,
The ultimate vacuum in the cavity 5 when it was provided at 5 locations d and e was 10 Toor. The amount of gas in the casting at this time was 2-3cc. On the other hand, when the packing 3 was provided at each position of a, b, and c (reference example), the vacuum degree was 30 Toor. The amount of gas in the casting at this time was 4 to 5 cc. When the packing 3 was not provided, the vacuum degree was 60 Torr. Also,
The amount of gas in the casting at this time was 7 to 8 cc.

The relationship between the degree of vacuum and the porosity (gas amount) is as shown in FIG. That is, the amount of gas in the casting
In order to achieve 2.5 cc or less, the ultimate vacuum in the cavity before injection of molten metal must be 25 Torr or less.

The relationship between the degree of vacuum and the degree of vacuum decrease after the discharge path is cut off is as shown by the vacuum exhaust characteristic curve as shown in FIG. That is, the lower the ultimate vacuum is,
It is known that the degree of vacuum decrease after the exhaust path is cut off is low.

Therefore, according to this example, after the ultimate vacuum in the molten metal before the molten metal injection is set to 10 Torr, the molten metal such as aluminum is injected into the cavity within a certain time (for example, within 0.1 seconds). By doing so, the amount of gas in the casting can be reduced to 2.5 cc or less.

Therefore, according to this example, a die for vacuum die casting excellent in airtightness capable of reliably maintaining the degree of vacuum in the cavity, preventing the occurrence of blowholes, and preventing the failure of the vacuum device is provided. Can be provided.

Second Embodiment A mold according to this embodiment will be described with reference to FIG.

That is, the mold of the present embodiment is the same as that of the first embodiment except that the O-shape is provided on the contact surface between the sprue bush 70 and the injection sleeve 7.
The arrangement position (e) of the ring 31 is changed to the position on the injection sleeve side f. The other structure is the same as that of the first embodiment.

Therefore, according to this example, in addition to the effects of the first example, the durability of the sealing material is improved.

Third Embodiment A mold according to this embodiment will be described with reference to FIG.

That is, the mold of this example is the same as the contact plate 2 of the first embodiment.
Without using, the packing 3 alone is provided as a sealing material in the gap between the fixed die 4 and the fixed block 41 and between the movable die 6 and the movable block 61. The other structure is the same as that of the first embodiment.

Therefore, according to this example, the fixed type 4, fixed block
When the gap between the movable block 61 and the movable die 6 and the movable block 61 is small, air entering through the gap 721 between the push pin 72 and the movable block 61 can be blocked by the packing 3. Similarly, the cooling pipe 9 and the movable block 61
Also, the air entering through the gap 91 between the cooling pipe 9 and the fixed block 41 can be blocked by the packing 3.

[Brief description of drawings]

1 to 3 show the mold according to the first embodiment and the results of its use, FIG. 1 is a sectional view of the mold, and FIG. 2 shows the degree of vacuum in the cavity and the amount of gas in the casting. A graph showing the relationship,
FIG. 3 is a graph showing the relationship between the degree of vacuum and the degree of vacuum drop after vacuum, FIG. 4 is a cross-sectional view of the mold according to the second embodiment, and FIG. 5 is a graph of the mold according to the third embodiment. A sectional view, FIG. 6 is a sectional view of a conventional mold, and FIG. 7 is an explanatory view for explaining a problem of air intrusion between a sprue bush and an injection sleeve in the conventional mold. 10 …… Fixed base, 11 …… Fixed platen, 2 …… Attach plate, 3 …… Packing, 31 …… O-ring, 32 …… Gasket, 4 …… Fixed type, 41 …… Fixed block, 5 …… Cavity , 51 …… Runner, 6 …… Movable type, 61 …… Movable block, 7 …… Injection sleeve, 70 …… Sprue bush, 702 …… Runner, 71 …… Injection plunger, 72 …… Extrusion pin, 75… … Metallic melt, 750 …… Metallic metal splash, 8 …… Vacuum exhaust path, 81 …… Vacuum device, 9 …… Cooling pipe,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Fumitaka Takehisa, 1-1, Showa-cho, Kariya, Aichi Prefecture, Nippon Denso Co., Ltd. (72) Fumio Kondo, 1-1, Showa-cho, Kariya, Aichi Prefecture, Nippon Denso Co., Ltd. (72) Inventor Hiromi Takagi, 1-1, Showa-cho, Kariya city, Aichi prefecture, Nippon Denso Co., Ltd. (72) Inventor, Seiji Iketani, 1-1, Showa-machi, Kariya city, Aichi prefecture, Nihon Denso Co., Ltd. (56) References JP-A-63-72463 (JP, A) JP-B 55-50747 (JP, B2) JP-B 35-5408 (JP, Y1)

Claims (1)

(57) [Claims] 1. A fixed die, a movable movable die that abuts on the fixed die and forms a cavity and a runner communicating with the cavity, and communicates with the runner for introducing molten metal into the cavity, and A sprue bush having an inner diameter larger than the inner diameter of the runner, an injection sleeve communicating with the sprue bush, an injection plunger that slides in the injection sleeve and the sprue bush and injects molten metal into the cavity, A die for vacuum die casting comprising a vacuum exhaust path for sucking the inside of the cavity to a decompressed state, wherein a fixed block is disposed adjacent to the fixed die, and a sealing material is interposed between the two. A movable block is disposed adjacent to the movable die, a sealing material is provided between the movable die and the movable die, and the fixed block is attached to the fixed die. A cooling pipe inserted through the cooling die is disposed, a cooling pipe inserted through the movable block is disposed in the movable die, and an extrusion pin that penetrates the movable block and the movable die and communicates with the cavity. A sealing material is provided between the sprue bush and the injection sleeve at the contact surface between the sprue bush and the injection sleeve. A die for vacuum die casting, characterized in that a sealant is provided on the outer periphery.