JPH11151723A - Preparation of hollow molding, and hollow core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow core with a thin thickness and a specified shape and being easily pulled out without deformation and to simply and highly accurately prepare a required hollow molding. SOLUTION: A hollow core 1 which has a specified shape of the hollow part of a hollow molding and is molded of a resin 11 and in which a liq. G1 being a low b.p. such as water, alcohol and hexane and for holding the core is encapsulated is molded. Then, when the hollow core 1 is arranged in a hollow molding mold and a molten molding material is fed, temp. of the hollow core 1 is elevated to vaporize the liq. G1 and inner pressure of the hollow core 1 is elevated. After molding, the liq. G1 for holding the core existing in the hollow core is discharged outside and the hollow core is softened by heating or contracted to take it out and to remove it and to prepare the hollow molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a hollow molded article such as an intake manifold for an automobile, and more particularly to a method of molding using a hollow core, extracting and removing the hollow core after molding. The present invention relates to a product having a shape.

[0002]

2. Description of the Related Art As a hollow molded product, there is, for example, a synthetic resin manifold used for an intake manifold for an automobile. This has a complicated shape in which a gas suction part, a cylinder head joint part, and a branch pipe connecting both parts are integrated. This is traditionally
For example, it was manufactured by a method as shown in FIG. First, a core 10 having a predetermined shape of a hollow portion of a hollow resin molded product is formed.
1 is formed from a low melting point alloy. Next, the core 101 is placed in an injection mold 105 having a hollow portion 103 having a predetermined shape, and a resin 107 is injected between the core 101 and the hollow portion 103 to form the core 101 and the hollow resin molded product. A molded article 111 composed of 109 is formed. Next, the molded article 111 is heated to elute and remove the core 101 of the low melting point alloy, thereby obtaining a hollow resin molded article 109.

[0003]

According to the above-mentioned conventional method, there are the following problems. First, core 1 of low melting point alloy
01 is a metal and has a high thermal conductivity.
However, there is a problem that the non-rotation easily occurs due to the temperature drop. Further, it is conceivable to increase the injection pressure in order to eliminate such a non-rotation, but it is necessary to strengthen the structure of the molding die, which causes an increase in cost.

Further, since the core 101 of the low melting point alloy is solid, it is heavy and difficult to handle. Further, there is a problem that it takes a long time to heat and soften the material to be extracted from the mold, and the production efficiency is poor.

[0005] Therefore, a hollow core made of resin is molded, placed in an injection mold, and a resin melted in a gap between the hollow core and the hollow portion is injected. Will collapse. For this reason, a hollow resin molded product with high precision cannot be manufactured. Therefore, it is not practical unless a hollow core having a large thickness is used. In this case, there is a problem that the hollow core cannot be removed from the mold after molding.

The present invention has been made on the basis of the above-mentioned problems. It is an object of the present invention to provide a hollow core having a predetermined shape even with a thin wall, without causing deformation, and being easy to remove. Is to provide a method for manufacturing a hollow molded article that can be manufactured simply and with high precision.

[0007]

In order to achieve the above object, the hollow core according to the first aspect of the present invention, which is used in the method of manufacturing a hollow molded article according to the present invention, has a hollow portion of the hollow molded article having a predetermined shape. And a liquid holding a core having a low boiling point, such as water, alcohol or hexane, is enclosed therein.

According to a second aspect of the present invention, when the molten core is injected by disposing the hollow core of the first aspect in a hollow mold, the temperature of the hollow core is increased to vaporize the liquid inside. And thereby increasing the internal pressure of the hollow core.

[0009] In a third aspect of the present invention, after the molding, the liquid in the hollow core is discharged to the outside, and the hollow core is heated and softened or deflated to be removed and removed. 2. A method for producing a hollow molded article according to 2.

According to a fourth aspect of the present invention, the hollow core is formed by a gas assist method, and a liquid holding the core is filled and sealed during the molding. This is a method for producing a molded article.

According to a fifth aspect of the present invention, the hollow molded product is a resin having a higher melting point than the hollow core.
Or a method for producing a hollow molded article according to 4.

A sixth aspect of the present invention is a method of manufacturing a hollow molded article according to the second, third or fourth aspect, wherein the hollow molded article is an aluminum alloy having a higher melting point than the hollow core. .

[0013]

In the hollow core of the present invention, a resin material is injected into a molding die so as to form a predetermined shape of a hollow portion of a hollow molded product, and a hollow is formed by introducing a gas to form a hollow. At this time,
A liquid holding a core having a low boiling point, such as water, alcohol, or hexane, is sealed inside the hollow core to obtain a finished product.
Thereby, a hollow core having a complicated shape is simply manufactured.
The resin for the hollow core is selected to have a relatively lower melting point than the hollow molded product.

In the method of manufacturing a hollow molded product according to the present invention, the hollow core is placed in a hollow mold having a hollow portion having a predetermined shape. Thereafter, a molded member having a relatively higher melting point than the hollow core is injected between the hollow core and the hollow portion to form a molded product including the hollow core and the hollow molded product. When the molding member is injected into the molding die, the liquid sealed in the hollow core has a low boiling point, so that the temperature of the hollow core is increased by e.g. Increase the internal pressure of the. Thus, the thin hollow core is not crushed inward by the injection pressure of the molding member injected into the molding die, and a high-precision hollow molded product is simply molded.

After the above-mentioned molding, the liquid in the hollow core is discharged to the outside, and the hollow core is heated and softened, and the hollow core is extracted and removed to complete the hollow molded article, or the liquid is discharged. The sealed core is cooled and liquefied, and a hollow core with a low melting point is removed and removed to complete a hollow molded product. In addition, the hollow core is heated and softened to suck and remove the liquid therein, and after being deflated by negative pressure, the hollow core is extracted and removed. This facilitates liquid management.

According to this method, the amount of heat for softening the core is small, and it can be easily extracted from the hollow molded product in a short time, and the production is easy. In the latter case, the hollow core can be reused, and the production is easy and the cost is low.

The hollow core is formed by a gas assist method.
When the liquid holding the core is filled and sealed at the time of molding, the hollow core becomes seamless, the injection port does not have to be closed, and a hollow core having a complicated shape can be simply manufactured.

When the hollow molded article is made of a resin having a higher melting point than that of the hollow core, the hollow molded article of the resin molded article can be easily manufactured with high precision and at low cost.

When the hollow molded product is made of an aluminum alloy having a higher melting point than that of the hollow core, the hollow molded product of the aluminum molded product can be easily manufactured with high precision and at low cost.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. As a method of manufacturing a hollow molded product according to the present invention, an example of manufacturing a resin-made automobile intake manifold 25 shown in FIG. 5 will be described.

First, as shown in FIG. 1, a hollow core 1 having a predetermined shape in a hollow portion of a hollow molded product is molded from a resin having a relatively low melting point. The illustrated one is a gas assist molding apparatus, in which a cavity 7 having the shape of a hollow part of a hollow molded product is formed between a fixed mold 3 and a movable mold 5 for core molding, and an injection device is formed in the cavity 7. 9, a molten resin (molded member) 11 is injected, and a nozzle N
The gasified liquid G is introduced, and the inside of the molten resin is hollowed by vaporizing the gasified liquid G to form the hollow core 1. It is necessary that the resin 11 has a relatively low melting point with respect to a resin of a hollow molded article described later, and a resin satisfying this condition is a PA resin (polyamide), a PP resin (polypropylene), and an AS resin (acrylic). Nitrile styrene),
PE resin (polyethylene) or the like is used.

Next, as shown in FIG. 1, a liquid G1 for holding the core is introduced from the nozzle N, and the hollow core 1 is hollowed out.
After filling the space S, the resin is injected again and sealed. As the liquid G1, a material having a low boiling point (80 to 100 ° C.) such as water, alcohol, and hexane is selected. As described above, the formed hollow core 1 is taken out of the molds 3 and 5 as a finished product.

Next, as shown in FIG.
Is disposed in an injection mold having a hollow portion having a predetermined shape, and a resin having a relatively higher melting point (100 to 300 ° C.) than the hollow core 1 is provided between the hollow core 1 and the molds 13 and 15. 21 is injected to form a molded product comprising the hollow core 1 and the hollow resin molded product 23. The illustrated one is an insert injection mold, in which a cavity 17 having the outer shape of a hollow molded product 23 is formed between an upper mold 13 and a lower mold 15, and the hollow core 1 is arranged in the cavity 17. The resin 21 is injected from the injection device 19 into the space S1 between the cavity 17 and the hollow core 1. The resin 21 has a relatively higher melting point (1
It is necessary to satisfy the above conditions. PPS resin (polyphenylene sulfide), PA resin (polyamide), PBT resin (polybutylene terephthalate), PC resin (polycarbonate), etc. used. By the above-described molding, a molded product 25 including the hollow core 1 and the hollow resin molded product 23 is molded.

At the time of injecting the resin 21 into the molding dies 13 and 15, the liquid G1 in the hollow core 1 is removed from the molding dies 13 and 15.
In response to the heat of 5, the temperature rises to about 50 to 80 ° C. and evaporates to increase the internal pressure of the hollow core 1. This prevents the hollow core 1 from being crushed inward during the molding of the hollow resin molded product 23, thereby producing a highly accurate hollow resin molded product. In order to raise the internal pressure by raising the temperature of the liquid G1 in the hollow core 1 to a predetermined temperature and evaporating the liquid G1, the heating may be performed by a heater H disposed in the molds 13 and 15.

Then, as shown in FIG. 3, after molding,
First, the liquid G1 holding the core is discharged to the outside, and then heated again to soften the low-melting-point hollow core 1 and extract and remove it from the hollow resin molded product 23. Thus, the molded product 25 shown in FIG. 4 is completed.

As another method of extracting and removing the hollow core 1, the hollow core 1 is cooled to liquefy the liquid G 1 therein again, the hollow core 1 is deflated, and the hollow resin molded product 23 is removed. Remove and remove. Thus, the molded product 25 shown in FIG. 4 is completed. According to this extracting and removing method, the hollow core 1 can be reused depending on the shape. Further, as another extraction / removal method, the hollow core 1 is heated and softened to suck and remove the liquid G1 inside, and after being deflated by negative pressure, the hollow core 1 is removed and removed. .

According to the first embodiment, the following effects can be obtained. First, the hollow core 1 is formed by molding a resin into a hollow shape and sealing a liquid for holding a core having a low boiling point such as water, alcohol, hexane, etc., so that the inside of the hollow core 1 is appropriately heated at the time of molding. Since the liquid is vaporized and an internal pressure is applied, it is not deformed even when the molding material is injected, and the hollow molded article 23 having a precise and accurate shape is formed.
Can be manufactured.

Further, the hollow core 1 is formed by a gas assist method at the time of this molding, and the liquid holding the core is sealed therein. Therefore, the hollow core becomes seamless, and the injection port does not need to be closed. A hollow core having a complicated shape can be manufactured simply and at low cost.

The hollow core 1 made of resin is thin and lightweight, and is cooled and liquefied while the liquid inside is sealed, and the hollow core having a withdrawn low melting point is removed and removed. Can be reused. Further, if the liquid is heated and softened, and the liquid inside is removed by suction and then deflated and removed and removed by negative pressure, the liquid is not scattered.

Further, since a resin can be selected as a molding member having a higher melting point than the hollow core 1, a hollow resin molded article can be easily manufactured at a low cost.

Next, a second embodiment of the present invention will be described. The method of molding the core into a hollow shape is not limited to gas-assisted injection molding, and sheet molding or the like may be used. FIG. 6 shows a method of manufacturing the hollow core 1 'by blow molding. First, two resin sheets 1A and 1B are overlapped,
This is placed in a mold 50, 60 composed of an upper mold and a lower mold (a cylindrical parison may be used). Subsequently, the molds 50 and 60 are heated to soften the resin sheets 1A and 1B. In this state, air E is injected from the nozzle N to inflate the resin sheets 1A and 1B along a predetermined shape in the molding die. Thereafter, as shown in FIG. 7, the peripheral portion is cut off to complete the hollow core 1 ', and a liquid G1 holding the core is injected by a syringe or the like, and the injection port is closed to obtain a finished product. .

A hollow molded article 2 using the hollow core 1 '
5 can be manufactured in the same manner as in the first embodiment, but as another example, the hollow core 1 ′ is arranged in a die-casting mold, and is formed in a cavity. By injecting the aluminum alloy, a hollow molded article made of the aluminum alloy can be manufactured. Other configurations and effects obtained by the configuration are basically the same as those of the method of manufacturing the molded product 25 in the first embodiment, and thus description thereof is omitted. In addition to the casting using a die-casting die, sand casting and vanishing model casting are also possible.

According to the second embodiment, the hollow core 1 '
Is simple and can be manufactured at low cost, so that there is an effect that the hollow molded article can be easily manufactured at low cost.

[0034]

According to the first aspect of the present invention, since the hollow portion of the hollow molded article has a predetermined shape and is formed of a resin, and a liquid holding a low-boiling core such as water, alcohol, hexane or the like is sealed inside. A hollow core with a complicated shape is manufactured simply, and the internal pressure can be applied by evaporating the liquid at the time of molding using it, so that hollow molded products can be easily manufactured with high precision and low cost The effect that can be achieved is exhibited.

According to a second aspect of the present invention, when the hollow core is placed in the hollow mold and the molten molded member is injected, the temperature of the hollow core is increased to evaporate the liquid and the internal pressure of the hollow core. Therefore, the hollow core is not crushed inward by the injection pressure of the injected molding material, and an effect of forming a hollow molded article with high precision is exhibited.

According to the third aspect of the present invention, after the molding, the liquid in the hollow core is discharged to the outside, and the hollow core is heated and softened to be extracted and removed, or the liquid holding the core is removed. Is cooled and liquefied while enclosing the hollow core. . In addition, it cools and liquefies while the liquid holding the core is sealed, and extracts the withered hollow core.
In the case of removal, the hollow core can be reused, and the effect of manufacturing at low cost is exhibited. In addition, if the liquid is heated and softened, and the liquid inside is removed by suction, the liquid is evacuated and removed and removed under a negative pressure, the liquid is not scattered.

According to the fourth aspect of the present invention, the hollow core is formed by the gas assist method, and the liquid holding the core is filled and sealed at the time of the molding, so that the hollow core becomes seamless and the injection port is closed. And the effect that a hollow core having a complicated shape can be simply produced is exhibited.

According to the fifth aspect, since the hollow molded article is a resin having a higher melting point than the hollow core, the effect that the hollow molded article made of resin can be easily manufactured at a low cost is exhibited.

According to the sixth aspect, since the hollow molded article is an aluminum alloy having a higher melting point than the hollow core, the hollow molded article made of an aluminum alloy can be easily produced at a low cost.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment of the present invention, and is a cross-sectional view showing a mold for forming a hollow core.

FIG. 2 is a view showing the first embodiment of the present invention, and is a cross-sectional view showing an injection mold of a molded product including a hollow core and a hollow molded product.

FIG. 3 is a view showing the first embodiment of the present invention, and is a cross-sectional view showing the hollow core at the time of extraction.

FIG. 4 is a view showing the first embodiment of the present invention, and is a cross-sectional view showing a hollow molded product.

FIG. 5 is a perspective view of an intake manifold manufactured according to the first embodiment of the present invention.

FIG. 6 is a view showing a second embodiment of the present invention, and is a cross-sectional view showing a molding die of a hollow core.

FIG. 7 is a view showing a second embodiment of the present invention, and is a cross-sectional view of a hollow core.

FIG. 8 is a view showing a conventional example, and is a cross-sectional view showing an injection mold of a molded product composed of a core and a hollow resin molded product.

[Explanation of symbols]

 1, 1 'Hollow core 1A, 1B Resin sheet 3, 5 Mold 9 Injector 11 Resin 13, 15 Mold 17 Cavity 19 Injector 21 Molded member 23 Hollow molded product 25 Molded product 50, 60 Mold N nozzle G gas G1 core retention liquid

Claims (6)

[Claims] 1. A hollow molded product, wherein a hollow portion of a hollow molded product has a predetermined shape and is formed of resin, and a liquid holding a core having a low boiling point, such as water, alcohol, or hexane, is enclosed therein. Child. 2. When the hollow core according to claim 1 is placed in a hollow mold and a molten molded member is injected, the temperature of the hollow core is increased to evaporate the liquid therein and to reduce the temperature of the hollow core. A method for producing a hollow molded article, wherein the internal pressure is increased. 3. The hollow molding according to claim 2, wherein, after the molding, the liquid in the hollow core is discharged to the outside and the hollow core is heated and softened or deflated and removed and removed. Product manufacturing method. 4. The method for producing a hollow molded article according to claim 2, wherein the hollow core is formed by a gas assist method, and a liquid for holding the core is filled and sealed during the molding. . 5. The method for producing a hollow molded article according to claim 2, wherein the hollow molded article is a resin having a higher melting point than the hollow core. 6. The method according to claim 2, wherein the hollow molded article is an aluminum alloy having a higher melting point than the hollow core.