JPH0734982B2 - Mold degassing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mold degassing device for extracting gas from a mold cavity during molding in an injection molding device such as a die casting machine or an injection molding machine. .

[Conventional technology]

The die casting machine has been widely used as a device for casting a large amount of precision products, but since it fills the molten metal into the cavity at high speed and high pressure, the gas in the cavity cannot be fully exhausted. It may remain as a nest in the product after being mixed, and it may not be suitable for a product in which integrity without a nest is important.

Therefore, as a means for eliminating such inconvenience, the applicant of the present invention can reliably and easily generate a large amount of gas in the cavity as described in, for example, Japanese Patent Publication No. 58-46386 and Japanese Patent Publication No. 59-309. We have developed a degassing device for molds to obtain die-cast products without voids by removing gas and entraining gas.

FIG. 3 is a partially cutaway front view of a main part of a conventional mold degassing device seen from a mold dividing surface. This will be described with reference to FIG. The degassing block 3 of the degassing device 2 is divided on the same surface and joined to the mold 1 divided into the side and the cylindrical surface 4 also called a spool is formed on the divided surface. A valve seat 4a is formed on the inner surface of the lower end of the cylindrical portion 4. Reference numeral 5 is a valve composed of a valve rod 5a and a valve head 5b, and is configured to open and close between a taper portion 5c provided on the upper outer periphery of the valve head 5b and a valve seat 4a by raising and lowering. In the cylindrical portion 4 above the valve seat 4a, there is formed a space portion 7 in which the exhaust port 6 provided in the cylindrical portion 4 opens, and outside the exhaust port 6, an electromagnetic switching valve and a vacuum suction valve (not shown) are provided. The devices are connected. Further, in the mold block 3, a gas vent groove 9 communicating with the mold cavity 8 is introduced, and in the middle of the gas vent groove 9 from the front of the valve head 5b, bypassing the valve head 5b, and guided to a portion immediately in front of the valve seat 4a. A gas vent passage 10, also called a bypass, is provided.

With this structure, the gas at the time of injecting the molten metal is discharged to the outside of the apparatus through the gas vent groove 9, the gas vent passage 10 and the space 7 in the valve open state, and the filling of the molten metal is completed. At or just before that, the valve 5 is closed by the inertial force of the molten metal advancing through the gas vent groove 9 at a high speed, and the cylindrical portion 4 is closed.
It is configured to block the intrusion of the molten metal into the inner space 7.

[Problems to be solved by the invention]

However, in such a conventional mold degassing apparatus, the valve 5 is completely closed when the inflow speed of the molten metal into the degassing groove 9 is slow or when the inertial force is small such as when the inflow amount is small. Sometimes it does not close, and because a vacuum suction device is used, a portion of the molten metal advances to the degassing passage 10 that bypasses before the molten metal sufficiently acts on the valve head. Although it is extremely rare, the molten metal becomes droplets or small particles and adheres to the taper portion 5c or the valve seat 4 on the upper outer periphery of the valve head 5b and solidifies to completely close the valve 5. The molten metal may enter the space 7 in the cylindrical portion 4 and damage it,
There was a problem that it spouted out of the cylindrical portion 4.

Therefore, the present applicant has filed Japanese Patent Application No. 62-56798 (Japanese Patent Publication No. 3-3
3059), the valve body (valve head) of the valve has a substantially conical shape, and a groove-like passage provided along the surface of this conical surface serves as a degassing groove and a bypass gas. A gas venting device has been previously proposed in which the valve is fully closed by connecting the vent passage and the entire amount of the molten metal passing through the groove passage to act on the conical surface of the valve head.

Then, with such a configuration, it is possible to substantially eliminate the above-mentioned problems.

However, in the degassing device having such a structure, the groove-like passage along the conical surface of the valve head is narrow and long at the time of maximum valve opening, so that there is a problem in terms of gas exhaust capacity. Was left. On the other hand, when the valve head moves in the valve closing direction, the flow passage cross-sectional area of the groove-like passage expands rapidly, and by the time the valve is closed, the molten metal droplets will pass through the expanded passage portion. Passing through to the opening and closing of the valve,
There was also a problem that the valve could be clogged. This is because in order to reduce the discharge resistance and to efficiently discharge the gas and the air, it is necessary to increase the flow passage cross-sectional area in the portions other than the groove-like passages to some extent. .

Further, according to the structure described above, the inertial force of the molten metal acting on the valve head due to the shape of the valve head and the shape of the groove-like passage is not necessarily the best state, and in consideration of such a point, It is desired to take some measures so that it can function as a mold degassing device.

The present invention has been made in view of such circumstances,
When injecting the molten metal into the cavity, the gas and air can be exhausted properly and sufficiently by the passage having an appropriate cross-sectional area, and the inertial force of the valve is released when the molten metal reaches the gas vent groove side from the cavity. It is an object of the present invention to provide a mold degassing device which can be operated in the best condition on the valve head to ensure the fully closed state of the valve.

[Means for solving problems]

In order to solve such a problem, a mold degassing apparatus according to the present invention is a valve of a valve slidably provided in a valve chamber connected to an end of a gas vent groove communicating with a mold cavity. The head shape is formed in a step shape composed of a large diameter portion and a concentric small diameter portion protruding from the large diameter portion in the direction of the gas vent groove, and the outer peripheral surface of the small diameter portion of the valve head and the valve are formed. An annular passage having a throttle portion that gives resistance to the flow of molten metal, between the inner peripheral surface and the cavity-side end surface of the small diameter portion in the valve open state and the cavity-side bottom surface of the valve chamber facing the inner peripheral surface. The annular passage and the passage originating from the inner peripheral surface of the valve chamber corresponding to the side opposite to the cavity of the annular passage and diverting to the valve opening / closing portion open / close the valve from the gas vent groove communicating with the mold cavity. With a gas vent passage leading to the That.

[Action]

According to the present invention, when the molten metal is injected into the cavity, the molten metal and the solidified material such as small particles are caused by the existence of the annular passage having the throttle portion formed between the valve head small diameter portion and the valve chamber. Before entering the bypass degassing passage, the small-diameter portion of the valve head collides against the cavity-side end face to completely close the valve, so that molten metal or the like does not enter the valve chamber.

Further, the gas in the cavity goes to the valve head through the gas vent groove, but since a passage having an appropriate cross-sectional area is formed between the outer peripheral surface of the small diameter portion of the valve head and the inner peripheral surface of the valve chamber. , Exhausted well. However, if the passage on the outer peripheral side of the small diameter part is slightly throttled so that it does not become wider than necessary, the gas is sufficiently discharged and the molten metal becomes difficult to pass through, and the cavity of the small diameter part in the valve head part The end face on the side surely collides, the separation property between the gas and the molten metal becomes extremely good, and the valve is surely closed every time so that the valve can withstand continuous operation.

〔Example〕

FIG. 1 is a longitudinal sectional view showing an embodiment of a mold degassing device according to the present invention. In the figure, a fixed cylinder or a movable mold, or a separation surface portion of one of the molds is provided with a degassing block 11, and a fluid pressure cylinder 12 is fixed on a bracket 11a fixed on the upper surface thereof. In the flange 12b, which is the working end of the piston rod 12a that advances and retracts due to the fluid pressure, the main body of the mold degassing device indicated by the whole reference numeral 13 is fixed by bolting the holder 14 at the upper end. ing. The main body of this gas venting device
13 has a bottomed cylindrical spool 15 whose upper end is clamped by a holder 14, and the lower end of the spool 15 has a small diameter step 15
The a is detachably fitted into the spool hole 16 of the gas vent block 11. Then, when the gas in the mold cavity 22 is discharged or the valve is closed by using the main body 13 of the mold degassing device at the time of injection molding, the piston rod 12a advances to form the small diameter stepped portion 15a and the spool hole 16. As shown in FIG. 1, the piston rod 12a is retracted to fit the small diameter stepped portion 15a and the spool hole 16 when the die is opened to clean the valve head after injection. The small-diameter step portion 15a and the valve head portion are provided so as to be located outside the gas venting block 11 after being unraveled. The spool 15 is the upper and lower members 15b, 15
It is divided into c, and the flange of the valve guide 17 fitted in the inner hole 15d is sandwiched between the upper and lower members 15b,
15c is integrated. Reference numeral 18 denotes a piston located above the valve guide 17 and slidably fitted in the inner hole 15d of the member 15b of the spool 15.
The threaded portion of the valve rod 19 which is fitted into the inner hole 17a of 17 so as to move forward and backward and penetrates the lower end small diameter stepped portion 15a of the spool 15 is screwed into and integrated with the lower end of the valve rod 19. A valve head 20, which will be described in detail later, is integrated.

On the other hand, the degassing block 11 and the mold 21 to which it is joined and fixed are divided into a front side and a paper back side with the plane of the drawing as a boundary, and a cavity 22 is formed in the mold 21. . The gas venting block 11 is formed with a gas venting groove 23 continuous to the cavity 22.
Between the spool hole 16 in which the spool 15 is fitted,
A stepped cylindrical valve chamber 24 is provided with a large diameter hole 24a and a small diameter hole 24b. The valve head 20 is a valve chamber.
A cylindrical large-diameter portion 20a slidably fitted in the hole 24b of the small-diameter portion of 24 and a tapered small-diameter portion 20b protruding from the large-diameter portion 20a toward the gas vent groove 23 form a step shape. A conical hole 20c, which is integrally formed and has a diameter larger than the width of the gas vent groove 23, is provided on the end face side of the central portion. On the outer periphery of the upper end of the base end flange portion 20d of the valve head 20, a taper portion 20e which forms a valve opening portion with a valve seat 15e formed on the inner surface of the lower end of the spool 15 is formed. Then, when the valve head 20 is pushed up by the molten metal from the cavity 22, the taper portion 20e is pressed by the valve seat 15e to close the valve.
The valve opens when air or oil is sent to the chamber above the piston 18 in response to a command from the controller, but illustration and detailed description thereof are omitted. Further, the piston 18 can be forcibly closed by supplying air or oil to the lower chamber.

The gas vent passage 25, which can be called a bypass following the gas vent groove 23, includes an end surface of the tapered small diameter portion 20b of the valve head 20 on the side of the cavity 22 and a bottom surface of the valve chamber 24 (valve chamber 24 which faces the end surface). Molten metal between the outer peripheral surface of the small diameter portion 20b and the inner peripheral surface of the valve chamber 24 (wall surface portion of the inner peripheral surface of the valve chamber 24), and between the outer peripheral surface of the small diameter portion 20b and the inner peripheral surface of the valve chamber 24. Of the annular passage 25a having the first and second throttle portions 25a1 and 25a2 for giving resistance to the flow of the gas and communicating with the gas vent groove 23, and the valve chamber corresponding to the outer peripheral surface of the small diameter portion 20b on the side opposite to the cavity 22 side. It is formed from a part of the inner peripheral surface of 24 and is formed by a pair of bypass passages 25b communicating with the valve chamber 24 immediately before the valve seat 15e. First
In the illustrated embodiment, the bypass passage 25b moves slightly laterally to the downward direction, then to the outer lateral direction, then to the upper direction, and finally to the inner lateral direction toward the valve seat 15b.
It reaches just before e. However, this may have another shape as long as it has a necessary and sufficient length. The spool 15
An exhaust hole 15f is opened in the inner hole 15d of the gas, and the gas in the cavity 22 is discharged from the gas vent groove 23 and the passage 2 when the valve is open.
It is configured such that it enters the inner hole 15d of the spool 15 through 5a, the bypass passage 25b, and the hole 24a in the upper large diameter portion of the valve chamber 24, and is discharged to the outside from the exhaust hole 15f.

In this embodiment, the thickness of the large diameter portion 20a of the valve head 20 slidably provided on the inner peripheral surface of the hole 24b of the small diameter portion of the valve chamber 24 is the valve opening dimension, that is, the valve seat in the valve open state. It is thicker than the axial distance between 15e and the tapered portion 20e so that when the valve is closed, the molten metal does not pass through the outer periphery of the large diameter portion 20a directly to the hole 24a of the large diameter portion of the valve chamber 24.

Further, the axial length of the tapered small diameter portion 20b of the valve head 20 is longer than the width of the bypass passage 25b in the portion extending laterally from the root of the small diameter portion 20b when the valve is open. .
If possible, the length of the small diameter portion 20b in the axial direction should be the bypass passage 2
It is preferable to make the width more than twice the width of 5b or longer than the width of the bypass passage 25b plus the valve opening size. It is a small diameter part from the gas vent groove 23 to the valve head 20.
This is to prevent the molten metal that has entered laterally from the end surface of the cavity 20b of the cavity 20b from proceeding into the bypass passage 25b.

The passage 25a formed along the end surface on the cavity 22 side and the outer peripheral surface of the tapered small diameter portion 20b of the valve head 20 in the valve open state is a passage 25a in a properly narrowed state, and has a gas exhaust capacity. Is so large that the molten metal is a little difficult to progress. That is, of the passage 25a, the portion of the valve head 20 along the end surface on the cavity 22 side of the small diameter portion 20b has a taper surface on the lower side, and the portion of the valve head 20 on the cavity 22 side of the small diameter portion 20b. The flow of the molten metal can be restricted near the outer circumference of the end face of the. However, this throttling portion works effectively at the moment when the molten metal collides with the valve head 20 when the valve is open, but once the valve begins to close, the space here rapidly expands and the throttling effect fades away immediately. I will end up. On the other hand, the first and second throttle portions 25a1 in the passage 25a provided on the outer periphery of the tapered small diameter portion 20b of the valve head 20.
If 25a2 is made narrow enough to discharge gas sufficiently, the throttling effect hardly changes even when the valve starts to close, and the throttling state is maintained even when the valve head 20 moves in the axial direction. . Since these throttle portions are provided along the end surface on the cavity 22 side and the outer peripheral surface of the small-diameter portion 20b of the valve head 20, even though the gas can easily pass, the molten metal cannot easily go. The valve head
The small-diameter portion 20b of 20 may be formed in a cylindrical shape without being necessarily tapered. That is, even if such a small-diameter portion 20b is formed in a cylindrical shape, between the end surface on the cavity 22 side of the small-diameter portion 20b and the bottom surface of the valve chamber 24 facing this, and further, the outer peripheral surface of the small-diameter portion 20 and the valve chamber 24. First and second throttle parts capable of giving resistance to the flow of molten metal between the inner peripheral surface and the inner peripheral surface of the
25a1 and 25a2 from the degassing groove 23 to the anti-cavity 2 of the valve chamber 24.
It can be formed in the middle of the annular passage 25a extending from the inner peripheral surface on the second side to the pair of detour passages 25b, and substantially the same operational effect as that of the above-described embodiment can be obtained.

Of course, from a practical point of view, it is advantageous that the small-diameter portion 20 has a draft angle for reasons such as workability. Further, if the small-diameter portion 20 is gradually tapered toward the end surface on the cavity 22 side so that the diameter is gradually reduced, not only the throttling effect but also the valve head from the solidified metal portion after injection is obtained. There is also an effect that the portion 20 can be smoothly acted upon withdrawing.

On the other hand, a conical hole 20c is provided from the end surface on the cavity 22 side of the small-diameter portion 20b of the valve head 20 to the inside, and at this time, the diameter of the inlet of the conical hole 20c is larger than the width of the gas vent groove 23. However, this ensures that the first part of the molten metal that rushes straight from the degassing groove 23 enters this conical hole 20c, and the valve is opened before the molten metal tries to go to the passage 25a. This is to ensure that they are closed quickly. Furthermore, the reason why the valve head 20 is provided with the hole 20c is that the valve head 20 itself is lightened so that the valve head 20 can be pushed up with a lighter force. The conical hole 20c is used because it has a draft and it is not necessary to reduce the strength of the valve head 20 itself more than necessary.

The operation of the die degassing device configured as described above will be described. Set the main body 13 of the mold degassing device in the state shown in FIG. 1 and open the cavity of the mold 21 with the valve open.
When the molten metal is injected into the cavity 22, the gas in the cavity 22 becomes
Enters the passage 25a through the degassing groove 23, and both detour passages 25b
Then, it bypasses and enters the spool 15 from the valve opening portion immediately before the valve seat 15e, and is discharged to the outside from the exhaust hole 15f.
In this case, the cross-sectional area of the passage 25a is set to an extent necessary for discharging gas, and the bypass passage is relatively wide.
Since 25b is in communication with this, gas can easily pass therethrough and the exhaust capacity is large. The gas may be released to the atmosphere from the exhaust hole 15f, but the exhaust hole 15f is often connected to an electromagnetic switching valve (not shown) and a vacuum device to suck the gas in vacuum.

When the molten metal fills the cavity 22, this molten metal vigorously rises into the degassing groove 23 and reaches the valve head 20 before entering the passage 25a.
Since it reliably acts on the end surface of the small-diameter portion 20b on the cavity 22 side, the valve head 20 rises, the taper portion 20e comes into close contact with the valve seat 15e, and the valve is surely fully closed. After this, the molten metal advances to the bypass passage 25b via the passage 25a, so that the molten metal entering the bypass passage 25 or the solidified material in the form of droplets or small particles does not clog the valve opening / closing part or enter the spool 15. .

In this case, in the valve open state, the passage 25a along the end surface on the side of the cavity 22 formed as a horizontal surface in the small diameter portion 20b of the valve head 20 is in a state where the outer peripheral side of the valve head 20 is narrowed to some extent, Further, the outer peripheral surface of the small diameter portion 20b of the valve head 20 is also tapered, and the passage 2 along the outer periphery of the small diameter portion 20b is formed.
5a is also squeezed to some extent, so the gas can be sufficiently discharged, but the molten metal can be passed through the passage 25 by the action of these throttles.
It is difficult to smoothly flow into the detour passage 25b through a. In addition,
When the valve is open, both the end surface of the small diameter portion 20b and the outer peripheral portion are squeezed, but when the valve begins to close, only the outer peripheral portion of the small diameter portion 20b is opened on the cavity 22 side of the small diameter portion 20b. Even if the action of the first throttle portion 25a1 on the end face side of the is suddenly weakened, there is no problem because it is when the valve is closed.

While making it difficult for the molten metal to reach the passage 25a and the bypass passage 25b in this way, a conical hole 20c is provided from the end face of the valve head 20 to the back to make the valve head 20 itself lighter and push up easily. The diameter of the inlet of the conical hole 20c to the gas vent groove 2
Since the width is slightly larger than the width of 3, the molten metal that has vigorously advanced straight from the gas vent groove 23 first enters into the conical hole 20c and easily pushes up the valve head 20.

In this way, by the synergistic effect of the effect of reliably acting the molten metal on the valve head 20 and the throttling effect of the passage 25a that prevents the molten metal from advancing toward the passage 25a and the bypass passage 25b side as much as possible, The valve can be closed surely and quickly every time without clogging the droplets on the valve seat 15 and beyond. With such a structure, not only when a large amount of molten metal solidifies from the gas vent groove 23 and goes straight, but also when a small amount of molten metal comes or a molten metal with a slightly weaker force comes forward. The valve can be closed quickly and reliably even when the inertia of the melt is rather weak, as is the case.

When the molten metal is cooled under pressure, the entire body 13 of the degassing device is raised by the cylinder 12 to fill the gas vent groove 23 and the gas vent passage 25 and solidify the solidified metal into the valve head 20.
After releasing, the mold is opened and the product is taken out.

FIG. 2 is a vertical cross-sectional view showing another embodiment of the present invention corresponding to a part of FIG. 1, and members having the same configurations as those in FIG. Is omitted. In the present embodiment, the valve head portion 30 is formed in a two-step shape including a large diameter portion 30a having a tapered portion 30e on the upper outer peripheral portion that is in close contact with the valve seat 15e when the valve is open, and a tapered small diameter portion 30b. did. That is, without providing the upper flange portion 20d shown in FIG. 1, the portion corresponding to the flange portion 20d has the same diameter as the large diameter portion 30a. In addition, the hole 24b in the small diameter portion on the lower side of the valve chamber 24 in which the valve head portion 30 is located has two upper and lower portions.
The diameter of the valve head 30 and spool 15 is made somewhat smaller by making the lower end side into a smaller diameter part in steps, and the device is made compact, and the valve is made slightly lighter for easier movement. You can also do so.

It should be noted that if the width of the step indicated by reference numeral 1 in FIG. 3 is made wider, the passage of gas becomes easier and the exhaust capacity is improved. In FIG. 2, in order to show another embodiment, the small diameter portion
Although the cavity 30 side end surface of 30b is shown as a flat surface, in this case as well, the cavity 22 side end surface of the small diameter portion 30b has a diameter larger than the width of the degassing groove 23 as shown in FIG. It goes without saying that the holes can be provided to make the action of the molten metal more effective and the valve head 30 can be made lighter and easier to close.

〔The invention's effect〕

As described above, according to the mold degassing apparatus of the present invention, the valve head shape of the valve slidably provided in the valve chamber connected to the end of the gas vent groove communicating with the mold cavity. Is formed in a step shape composed of a large-diameter portion and a concentric small-diameter portion protruding from the large-diameter portion in the direction of the gas vent groove, and the outer peripheral surface of the small-diameter portion of the valve head and the inner peripheral surface of the valve chamber. And a cavity-side end surface of the small-diameter portion in the valve open state and a cavity-side bottom surface of the valve chamber facing the small-diameter portion, an annular passage having a throttle portion that gives resistance to the flow of the molten metal is formed. Further, a gas vent passage from the gas vent groove to the valve opening / closing portion is formed by the annular passage and a passage originating from the inner surface of the valve chamber corresponding to the side opposite to the cavity of the annular passage and diverting to the valve opening / closing portion. Therefore, various excellent effects listed below To.

That is, the molten metal that has risen from the cavity through the degassing groove is the cavity-side end surface of the small-diameter portion of the valve head and the outer peripheral surface thereof, and the cavity-side bottom surfaces facing the valve chambers, and The narrowed portion formed between the inner peripheral surface and the inner peripheral surface narrows the passage, making it relatively difficult to pass through this portion, and the molten metal conversely enters the degassing passage, which is the bypass passage. Before that, the whole amount surely acts as a large inertial force on the cavity side end surface of the small diameter part of the valve head, so the valve is fully closed surely, molten metal and its solidified solids enter the valve chamber, It does not spout to the outside, improving the durability of the device and the safety of work.

Further, the gas that has entered the gas vent groove from the cavity enters the annular passage around the valve head, which is not large for the molten metal passage but has a large cross-sectional area for gas discharge, and then the entire peripheral surface of this passage. Since it goes to the valve opening / closing portion through the bypass passage having the wide opening communicating with the valve, the gas can easily pass therethrough and the gas is surely discharged, so that the quality of the molded product is improved.

If a hole with a diameter larger than the width of the gas vent groove is provided in the valve head, the molten metal will act on the valve head more easily, the valve closing operation will be faster, and more reliably. It becomes possible to do it.

[Brief description of drawings]

1 and 2 show an embodiment of a mold degassing apparatus according to the present invention. FIG. 1 is a longitudinal sectional view thereof, and FIG. 2 is another embodiment of the present invention. FIG. 3 is an enlarged vertical cross-sectional view of the vicinity of the valve head of the conventional mold degassing device, corresponding to the parts. 13 …… Main body of degassing device for mold, 15 …… Spool, 15
e …… Valve chamber, 20,30 …… Valve head, 20a, 30a …… Large diameter part, 20
b, 30b …… Small diameter part, 20c …… Conical hole, 20e …… Tapered part, 2
1 …… Mold, 22 …… Cavity, 23 …… Degassing groove, 24
...... Valve chamber, 24a ...... Large diameter part hole, 24b ...... Small diameter part hole, 25
...... Venting passage, 25a ...... annular passage, 25a ₁ , 25a ₂ ...... first and second throttle parts, 25b ...... detour passage.

Claims (1)

[Claims] 1. A valve slidably provided in a valve chamber connected to an end of a gas vent groove communicating with a mold cavity, and a side of a moving path of the valve branched from a part of the gas vent groove. In a mold degassing device provided with a degassing passage that is bypassed to and led to a valve opening / closing part of a valve chamber, a valve head shape of the valve is defined as a large diameter part and the gas discharging groove from the large diameter part. Formed in a stepped shape consisting of a concentric small-diameter portion projecting in the direction, between the outer peripheral surface of the small-diameter portion and the inner peripheral surface of the valve chamber in the valve head of this valve, and in the valve open state. An annular passage having a throttle portion that gives a resistance to the flow of the molten metal is formed between the cavity-side end surface of the small-diameter portion and the cavity-side bottom surface of the valve chamber facing the cavity-side end surface, and the annular passage and the annular passage. The valve opening / closing portion is generated from the inner peripheral surface of the valve chamber corresponding to the side opposite to the cavity of the passage. A degassing apparatus for a die, wherein the degassing path is formed by a path that bypasses to the degassing path.