JPH03224719A - Mold for manufacture of hollow molded product - Google Patents

Abstract

PURPOSE:To make an optional site of a molded product hollow by forming a fluid injection path along a clearance between a push-up pin and a pin inserting hole and communicating the path with a fluid injection device. CONSTITUTION:Synthetic resin in the softened state is injected into a cavity 90 and fluid 82 using nitrogen gas is injected from a fluid injection path 2 into the synthetic resin. The fluid 82 is stored in a high pressure chamber 4, and then said fluid 82 is injected into the softened synthetic resin through the fluid injection path 2. After molding, a movable mold 92 is lowered and a push-up pin 93 is pushed up to push out a hollow molded product in the cavity. Said mold utilizes a clearance C between the push-up pin 93 and an inserting hole 1 to form the fluid injection path 2. The fluid 82 can be injected in a wide range by said arrangement, and an optional site of the molded product can be made hollow.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a mold for producing a hollow molded product.

More specifically, the present invention relates to the structure of a fluid injection passage for injecting a fluid for forming a hollow portion into a softened synthetic resin injected into a cavity.

[Prior art] Synthetic resin hollow molded products are made by injecting softened synthetic resin into the cavity of a mold and injecting a fluid such as nitrogen gas or water into the synthetic resin to make the inside hollow. Manufactured by

Conventionally, the molds used to manufacture such hollow molded products include (1) a resin injection passage for injecting softened synthetic resin into the cavity, and a fluid for forming the hollow part into the softened synthetic resin in the cavity. The same passage (e.g. sprue) that also serves as the fluid injection passage for injection (
(Special Publication No. 57-14968).

(2) Molding molds such as those in which the fluid injection passage is specially provided in addition to the resin injection passage (Japanese Patent Publication No. 58211425) are generally known.

FIG. 8 is a drawing showing the specific structure of the former mold, which consists of a fixed mold 91 attached to a fixed plate 910, a movable mold 92 attached to a movable plate 920, and 9 molds. A cavity 90 formed between 91 and 92, a resin injection passage 911 for injecting the softened synthetic resin 81 into the cavity, and a fluid 82 injected into the softened synthetic resin 81 in the cavity 90. a fluid injection passage 911 (the resin injection passage and the fluid injection passage are shared),
It has a push-up pin 93 and a pin insertion hole 921 for pushing the formed hollow molded product out of the mold.

The base of the push-up pin 93 is connected to a push-up plate 94. The push-up plate 94 is connected to an actuator (path shown) that moves it up and down.

Further, the resin injection passage 91 bored in the fixed mold 91
1 is connected to an injection nozzle 95.

In manufacturing the hollow molded product, as shown in FIG. 8, a softened synthetic resin 81 is injected into the cavity 90 from an injection nozzle 95 in a short shot.

The injection amount of the injected synthetic resin is the volume obtained by subtracting the hollow part (i.e., the fluid injection amount) from the cavity volume (i.e., the volume of the hollow molded product). Immediately after the injection, the fluid 82 such as nitrogen gas is introduced into the fluid injection passage 911.
Inject through.

As a result, the softened synthetic resin 8 inside the cavity 90
1 is pressed against the cavity wall surface and the cavity space portion by the fluid 82 injected into the interior thereof. After the cavity 90 is filled with the synthetic resin 81 and the fluid 82 therein, water is flowed through a cooling pipe (not shown) to cool and solidify the synthetic resin 81.

After that, the movable mold 92 and the movable plate 920 are lowered. As a result, the fixed mold 91 and the movable mold 92 are separated, and the cavity 90 is opened. Then, the push-up pin 93 is pushed up by the push-up plate 94, and the hollow molded product inside the cavity 90 is taken out.

Moreover, FIG. 9 is a drawing showing the specific structure of the latter, that is, a mold in which a resin injection passage and a fluid injection passage are separately provided in the movable die 92 of the mold.

A fluid injection passage 922 is drilled. Then, the fluid injection passage 922 is communicated with a fluid injection device (the illustrated path).

Therefore, in this mold, as shown in FIG. 9, fluid is injected into the synthetic resin in the cavity 90 from the movable mold 92 side.

[Problem to be solved]

However, conventional molds have secondary problems.

In the former mold, that is, a mold that uses a resin injection passage as a fluid injection passage, in the center of the cavity for a synthetic resin molded product.

Although it is easy to make the inside of the synthetic resin hollow, it may be difficult to make the inside of the synthetic resin hollow at the end of the cavity depending on the shape of the mold. This is because the resin injection passage is often located in the center of the fixed mold, as shown in Figure 8, and this creates a restriction when attempting to make any part of the molded product hollow. The first problem lies in this point.

In addition, in the latter mold, that is, a mold that has separate resin injection passages and fluid injection passages, cooling pipes and the like are installed inside the mold, so there are problems with the structure and size of the mold. ,
In some cases, it may not be possible to add a fluid injection passage. There is a second problem in this point.

In view of these conventional problems, the present invention provides a mold for producing hollow molded products, which allows any part of the molded product to be made hollow, and in which it is easy to add a fluid injection passage to the mold. This is what we are trying to provide.

[Means for Solving the Problem] The present invention has three cavities for molding a synthetic resin hollow molded product, a resin injection passage for injecting the softened synthetic resin into the cavity, and a resin injection passage for injecting the softened synthetic resin into the cavity. A blow molding having a fluid injection passage for injecting a fluid for forming a hollow part with a fluid injection device, and a push-up pin and pin insertion hole for pushing the formed hollow molded product out of the mold. In molds for manufacturing products.

The fluid injection passage is formed along a clearance formed between the push-up pin and the pin insertion hole, and the fluid injection passage is communicated with the fluid injection device. in the mold.

The most noteworthy feature of the present invention is that the fluid injection passage is formed by utilizing the clearance formed between the push-up pin and the pin insertion hole, which are used in any mold.

Examples of means for forming the fluid injection passage include the following.

(1) A method of forming the above-mentioned clearance by widening its width (first embodiment).

(2) A method of forming a groove by carving a groove in the outer periphery of the push-up pin (second embodiment).

(3) A method of forming a groove by carving a groove in the inner circumference of the pin insertion hole (third embodiment).

(4) A method in which a groove is formed in both the push-up pin and the pin insertion hole.

Regardless of the means used to form the fluid injection passage, the width of the gap must be 0.2- or less. This is 0. This is because if it exceeds 2rm, the softened synthetic resin injected into the cavity may enter the fluid injection path of the push-up pin due to its high pressure.

The fluid injection passages (2) to (4) above may be provided at a plurality of locations along the outer circumference of the push-up pin, along the inner circumference of the pin insertion hole, or both.

Furthermore, as mentioned above, the fluid injection passage is provided along the clearance formed between the push-up pin and the pin insertion hole;
One or more such push-up pins are provided. If multiple locations are provided, fluid is injected from each location. Furthermore, it goes without saying that in addition to the push-up pin with a fluid injection passage according to the present invention, a push-up pin without a fluid injection passage similar to the conventional one can also be provided.

Furthermore, a check valve may be provided in the fluid injection passage. Thereby, it is possible to reliably prevent the softened synthetic resin from flowing back into the fluid injection passage.

[For production]

In the present invention, after the softened synthetic resin is injected into the cavity, a fluid such as gas, water, etc. inject. Then, a blow molded product is manufactured in the same manner as before. After manufacturing the hollow molded product, the cavity is opened and the push-up pin is pushed up to push out the hollow molded product inside the cavity.

2. In the present invention, the fluid injection passage is formed along the clearance formed between the push-up pin and the pin insertion hole, and a plurality of push-up pins are generally provided, so that the fluid can be injected into any part of the molded product. Can be injected.

In addition, by forming the fluid injection passage along the clearance as described above, it is possible to add a fluid injection passage in order to modify the general mold currently in use into a mold for manufacturing hollow molded products. It is also easy.

(Effects) Therefore, 1. According to the present invention, any part of a molded product can be made hollow, and a general mold currently in use can be modified into a mold for manufacturing hollow molded products. It is easy to provide a mold for producing hollow molded products.

〔Example〕

First Embodiment This is an embodiment of the present invention. A mold for producing a hollow molded product will be explained using FIGS. 1 and 2.

In the mold of this example, the fluid injection passage 2 is formed by widening the width of the clearance C formed between the push-up thin 93 and the pin insertion hole 1.

As shown in FIG. 1, the mold of this example has a pin insertion hole 1 in a movable mold 92 through which a push-up pin 93 is inserted. A clearance C is formed between the pin insertion hole 1 and the push-up pin 93 in correspondence with the tip of the push-up pin 93.

The width of the clearance C is set to 0.2 m.

Then, a fluid injection passage 2 is formed along the clearance C. The fluid injection passage 2 utilizes the clearance C as it is, and as shown in FIG. 2, the cross section of the fluid injection passage 2 is annular.

Further, as shown in FIG. 1, a high pressure chamber 3 is formed between the push-up pin 93 and the pin insertion hole 1 in communication with the fluid injection passage 2. The high pressure chamber 3 has a larger opening area than the fluid injection passage 2. In addition, the high pressure chamber 3
is communicated with a fluid injection device (path shown) via a fluid supply passage 31 and a fluid supply port 32 carved in the movable mold 92.

Further, between the push-up pin 93 and the pin insertion hole 1, there is a seal chamber 4 that opens to the outside at the end of the high pressure chamber 3.
will be established. An O-ring 41 as a sealing member is fitted into the seal chamber 4, and a seal pressing plate 42 is attached to the movable mold 92 by fixing bolts 43 to prevent the O-ring 41 from falling off. Attach.

The rest is the same as the conventional example described above (FIGS. 8 and 9).

Since the mold of this example is configured as described above, it exhibits the fifth-order effect.

In manufacturing a hollow molded product using the mold of this example, a softened synthetic resin (path shown) is injected into the cavity 90 in the same manner as in the prior art. and.

When the softened synthetic resin is located outside the fluid injection passage 2 in the cavity 90, a fluid 82 using nitrogen gas is injected into the synthetic resin through the fluid injection passage 2.

In this case, the fluid supply port 32 is
Then, the fluid 82 is once sent into the high pressure chamber 3 via the fluid supply passage 31, and the fluid 82 is temporarily stored in the high pressure chamber 3 in this way.

The fluid 8 is introduced into the softened synthetic resin through the fluid injection passage 2.
Inject 2. Further, the O-ring 41 prevents the fluid 82 in the high pressure chamber 3 from leaking to the outside.

Then, a blow molded product is manufactured in the same manner as before.

After molding, the movable mold 92 is lowered to open the cavity 90 and the push-up plate 94 is then raised to release the push-up pin 9.
Push up 3. As a result, the hollow molded product inside the cavity is pushed out.

According to one example of the mold as described above, the push-up pin 9
A fluid injection passage 2 is formed using a clearance C formed between the pin insertion hole 1 and the pin insertion hole 1 . Therefore, the fluid 82 can be injected not only into the center of the cavity 90 but also over a wide range corresponding to the position of the push-up pin 93. Therefore, it is possible to make any part of the molded product hollow.

In addition, the push-up pin 93 is also used in general molds, and by using the clearance C, the general mold currently in use can be modified into a mold for manufacturing hollow molded products. It is easy to do.

Furthermore, the width dimension of the fluid injection passage 2 is as described above<,0.
2 am, the softened synthetic resin will not enter into the fluid injection passage 2, and the fluid 8 will not flow at an appropriate speed.
2 can be injected.

Second example Regarding the mold for manufacturing hollow molded products according to this example.

This will be explained using FIGS. 3 and 4.

In the mold of this example, the fluid injection passage 2 is formed by carving a groove 51 on the outer periphery of the push-up pin 5 along the clearance C.

That is, as shown in FIGS. 3 and 4, the Oshiage Keihin 9
A groove 5 is formed on the outer circumferential portion of 3 so as to communicate with the clearance C. The groove portion 5 is formed from the tip of the push-up pin 93 to the middle portion so as to be able to communicate with the high pressure chamber 3 . Further, a certain gap S is provided between the bottom of the groove 5 and the inner circumference of the pin insertion hole 1, as shown in FIG.

The size of the gap S is set to 0.2 am.

The rest is the same as the first embodiment.

Note that the width of the clearance C in the two examples is within the range through which the push-up pin 93 can be inserted (generally 0.02 to 0.04 mm).
m).

Therefore, the same effects as in the first embodiment can be obtained also in the two embodiments.

Third Embodiment A mold for producing a hollow molded article according to this embodiment will be explained with reference to FIGS. 5 and 6.

The mold of this example has a pin insertion hole 1 along the clearance C.
Fluid injection passage 2 is formed by carving a groove 6 on the inner circumference of
was formed.

That is, as shown in FIGS. 5 and 6, a groove 6 is formed in the inner peripheral portion of the pin insertion hole 1 so as to communicate with the clearance C. The groove portion 6 is formed in the movable mold 92 from the upper end facing the cavity 90 to the middle portion so as to be able to communicate with the high pressure chamber 3 . Further, a certain gap S is provided between the bottom of the groove 6 and the outer circumference of the push-up pin 93, as shown in FIG. The size of the gap S is set to 0.2 mm.

Further, the size of the clearance C is set in the same manner as in the second embodiment.

The rest is the same as the first embodiment.

Therefore, even in this example, the same effects as in the first example can be obtained.

Fourth example Regarding the mold for manufacturing hollow molded products according to this example.

This will be explained using FIG.

The mold of this example uses a seal 7 instead of the O-ring 41 as a seal member in the first example.

That is, as shown in FIG.
1, and a spring 72 embedded in the seal main body 71 and having a cross section shaped like a square.

The rest is the same as the first embodiment.

Therefore, even in this example, the same effects as in the first example can be obtained.

[Brief explanation of drawings]

1 and 2 show a first embodiment, FIG. 1 is a sectional view of the main part of a mold for manufacturing a hollow molded product, FIG. 2 is an enlarged cross-sectional view of a push-up pin and a pin insertion hole, Figures 3 and 4
The drawings show the second embodiment, Fig. 3 is a cross-sectional view of the main part of a mold for manufacturing a hollow molded product, Fig. 4 is an enlarged cross-sectional view of the push-up pin and pin insertion hole, and Figs. 5 and 6. 5 shows the third embodiment, FIG. 5 is a cross-sectional view of the main parts of a mold for manufacturing hollow molded products. FIG. 6 is an enlarged cross-sectional view of the push-up pin and pin insertion hole, and FIG. 7 is the fourth embodiment. 8 and 9, which are cross-sectional views of main parts of a mold for producing a hollow molded product, show the prior art,
FIG. 8 is an overall sectional view of a conventional mold for manufacturing a hollow molded product, and FIG. 9 is an overall sectional view of another similar conventional mold. 1゜3゜4゜41゜5, 6゜pin insertion hole. Fluid injection passage. Hyperbaric chamber. Seal room. 0 ring. 6. Groove portion 711. sticker. 90,,Cavity 91,,Fixed type. 92,, Movable type. 93... Push up pin. C01, clearance. S90. Gap applicant Toyota burying

Claims (1)

[Claims] A cavity for molding a synthetic resin hollow molded product, a resin injection passage for injecting a softened synthetic resin into the cavity, and a fluid injection path into the softened synthetic resin in the cavity. A molding for manufacturing a hollow molded product having a fluid injection passage for injecting a fluid for forming a hollow part by a device, and a push-up pin and pin insertion hole for pushing the molded hollow molded product out of the mold. In the mold, the fluid injection passage is formed along a clearance formed between the push-up pin and the pin insertion hole, and the fluid injection passage is communicated with the fluid injection device. Molding mold for manufacturing products.