JP2000280353A - Synthetic resin-made hollow molded product and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture efficiently a synthetic resin-made hollow molded product of an excellent quality while the hollow molded product having a high fracture-resistance strength against an internal pressure load can be manufactured by a two-stage injection molding method even through there is a joining line disposed inside the hollow molded product. SOLUTION: This hollow molded product is provided wherein a plurality of synthetic resin-made divided pieces formed by injection molding are joined mutually by their joining parts. In this case, a passage part 3 (3a, 3b) formed by synthetic resin allowed to flow in for mutual fusion welding of the joining parts is disposed between the mutual joining parts, and the passage part is elongated in a longitudinal direction of the joining part, and has a branched passage part 3 branched in a direction crossing the longitudinal direction of the joining part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a synthetic resin hollow molded article formed by fusing and joining together a plurality of synthetic resin split pieces with a molten synthetic resin. The present invention relates to a synthetic resin molded product having excellent fracture resistance at a joint.

[0002]

2. Description of the Related Art A synthetic resin hollow molded article having a complicated shape, such as an air intake manifold part of an automobile, is difficult to produce by a general injection molding method or a blow molding method. Specifically, it is manufactured by a construction method such as a lost core method or a vibration welding method.

In the lost core method, a core made of a tin-bismuth alloy or the like is set in a molding die, a synthetic resin is injected into the molding die, and then heated to melt and remove the core. This is a method for obtaining a resin hollow molded article, which is excellent in pressure resistance of the molded article and has a high degree of freedom in shape. However, in this lost core method, since the weight of the core is large and the equipment including the melting equipment becomes large,
There is a problem that production efficiency is poor.

[0004] The vibration welding method refers to a method in which a hollow body is divided into at least two pieces and separately manufactured by injection molding, and then vibration energy is applied to the joints to melt the joints and bond the joints to each other. This is a method for obtaining a molded article, and is a method by which a hollow body can be obtained relatively efficiently. However, when a synthetic resin filled with a reinforcing material is used, there are problems such as a decrease in joint strength and a relatively low degree of freedom in shape.

[0005] Recently, as a method of improving the drawbacks of the above-mentioned conventional method, a two-stage injection molding method, that is, a method in which a plurality of divided pieces formed by injection molding are formed into a primary hollow molded article in which joints are joined together. A method of manufacturing a hollow molded product by disposing a molten synthetic resin at the proper position in a molding die and then injecting the molten synthetic resin from the outer periphery to the boundary surface between the joints by injection molding to fuse the joints. (JP-A-62-87315, etc.).

In this two-stage injection molding method, the boundary surface between the joints is fused from the outer periphery with the molten resin. When pressure is applied, a relatively high strength can be achieved by concentration of stress on the resin forming the flow path portion extending along the longitudinal direction of the joining line. But,
In the case of a hollow molded product having a branch, such as an intake manifold component having the shape shown in FIG. 1, it has been difficult to obtain high strength in a joining line.

For example, in the case of an intake manifold part having the shape shown in FIG. 1, as shown in FIG. 2, the joints 1a and 1b of two injection-molded products (the upper divided piece 10 and the lower divided piece 20).
The joining line 2 is formed by abutting each other, and the joining portion 30b located on the outer peripheral surface has a sectional structure as shown in FIG. In the portions joined by such a structure, when an internal pressure is applied to the hollow molded product, a tearing stress is applied to the portion 4, so that the stress is concentrated on the resin forming the flow path portion 3b, so that a relatively high pressure is applied. Strength can be developed.

However, at the joint surface 30a located inside the hollow molded article, the flow path portion 3a through which the molten resin flows is shown in FIG.
When the internal pressure is applied to the hollow molded article, the flow path 3a and the joint 1
Since a tensile stress is applied to the fusion interfaces 5a and 5b with a and 1b, even a relatively low load stress easily leads to destruction. Here, FIG. 8 is a cross-sectional view taken along line II-II in FIG. 1, FIGS. 9 and 10 are cross-sectional views of a main part of a connecting portion between pipes in the intake manifold, and FIG. FIG. 10 is a cross-sectional perspective view taken along line XX in FIG. 9.

[0009]

SUMMARY OF THE INVENTION The present invention has been made as a result of studying to solve the above-mentioned problems in the prior art, and a main object of the present invention is to provide a bonding member located inside a hollow molded article. It is an object of the present invention to provide a synthetic resin hollow molded product capable of producing a hollow molded product having high breaking strength against internal pressure load by a two-stage injection molding method even if there is a line, and a method for producing the same.

[0010]

In order to achieve the above-mentioned object, a synthetic resin hollow molded article of the present invention joins a plurality of synthetic resin divided pieces formed by injection molding at their joints. A hollow molded article made of synthetic resin, comprising a flow path portion formed by a synthetic resin that has flowed in for joining and bonding the bonded portions between the bonded portions, and the flow path portion Is characterized by having a branch path portion extending in the longitudinal direction of the joint and branching in a direction intersecting with the longitudinal direction of the joint. Further, the manufacturing method is such that a plurality of synthetic resin divided pieces formed by injection molding are engaged with each other at their joints to form a primary hollow molded article in which a flow path is formed between the joints. After placing in the molding die with
A method of manufacturing a synthetic resin hollow molded article by joining the joints by fusion by flowing molten synthetic resin into the flow path, wherein the flow path extends in the longitudinal direction of the joint and the longitudinal direction of the joint. And a branch path portion that branches in a direction intersecting with.

As described above, the present invention provides a flow path 3a formed by injecting a molten resin in order to increase the resistance to breakage when an internal pressure is applied to a joining line located inside a hollow molded product.
And a branch path portion 3c extending in the longitudinal direction of the joint and branching in a direction intersecting with the longitudinal direction of the joint.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing an intake manifold component as an example of a synthetic resin hollow molded product to which the present invention can be applied. 2 and 3 show one embodiment of the structure of the joint portion 30a of the connecting portion between the pipes of the synthetic resin hollow molded product shown in FIG. 1 according to the present invention, and each is an enlarged vertical cutaway perspective view of a main part, FIG. 3 is a sectional perspective view taken along line III-III in FIG. 2. FIG. 4 shows a joint portion 30 of the pipe connection portion.
It is a principal part enlarged longitudinal break perspective view which shows another embodiment of the structure of a. FIG. 5 and FIG.
6A and 6B show still another embodiment of the structure of Oa, respectively, and are an enlarged vertical cutaway perspective view of a main portion and a vertical cutaway view taken along line VI-VI in FIG. 5. FIG. 7 shows a joint portion 30 on the outer peripheral surface.
It is a principal part enlarged longitudinal fracture | rupture perspective view which shows one Embodiment of the structure of b.

As shown in FIG. 1, a synthetic resin hollow molded article to which the present invention is applied has a plurality of divided pieces (in FIG. 1, an upper divided piece 10 and a lower divided piece 20 obtained by injection molding).
It has a structure in which it is fused and integrated via the joints 30a and 30b. In this synthetic resin hollow molded article, as shown in FIG. 2 and the like, a flow path in which a resin for fusing the upper and lower divided pieces 10 and 20 is provided inside the connection portion at the connection portion 30a at the pipe connection portion. Since it flows into 3a, it is affected by the deformation of the two pipes when an internal pressure is applied, and a load of tensile stress is applied to the fusion bonding interface.

Here, when the branch path portion 3c is formed in the flow path 3a at the joint portion 30a, the branch path portion 3c is formed.
In c, the fusion bonding surface is widened, and furthermore, since a fusion interface where no tensile stress is applied when an internal pressure is applied is formed, the resistance to the tensile stress load is greatly improved, and a hollow molded product having high apparent strength is obtained. .

As shown in FIGS. 5 and 6, the branch path portion 3c may be a branch to be embedded in one of the divided pieces. However, as shown in FIGS. 2 and 3, or FIG. In addition, it is preferable to branch in two reciprocal directions embedded in the divided piece, and in this case, a T-shaped or cross-shaped channel cross-sectional shape is formed at the branch point. Fork part 3 at the fork
The branch angle of c is approximately 90 with respect to the longitudinal direction of the flow path section 3.
Degrees, and the position of the branch point is
In the case of the structure as shown in FIG. 1, it is preferable to provide it at the connection between pipes near the position where the pipe branches from the chamber. The branch portion 3c may be provided at a plurality of locations.

In the hollow molded article having the above-mentioned joint structure, first, a plurality of synthetic resin divided pieces are formed by primary injection molding, and the plurality of synthetic resin divided pieces are engaged with each other at the joints. In the molding die at a position where a primary hollow molded article in which a flow path is formed between the joints, the molten synthetic resin flows into the flow path in the arrangement state, thereby joining the joints. It may be manufactured by a two-stage injection molding method of joining by fusion. At this time, the flow path has a branch path portion extending in the longitudinal direction of the joint and branching in a direction intersecting with the longitudinal direction of the joint. Therefore, it is necessary to correct the shape of the joint in the divided piece.

The two-stage injection molding method used in the present invention comprises:
An ordinary two-color molding method in which a primary hollow molded article is molded and then placed in another mold to perform secondary molding may be used, or primary molding such as die slide injection or die rotary injection may be used. And the secondary molding may be performed in the same mold by moving or rotating a part of the mold.

In the present invention, the synthetic resin used for forming the above-mentioned divided piece by primary injection molding is not particularly limited, but it is generally applied to engineering plastics, specifically, polyamides such as nylon 6, nylon 66, polyethylene terephthalate, and polystyrene. In addition to polyesters such as butylene terephthalate, polyacetals, polyphenylene sulfides, etc., polyolefins such as polyethylene and polypropylene, polyvinyl halides such as polyvinyl chloride and polyvinylidene fluoride, and thermoplastic resins such as ABS are exemplified.

Known additives such as a crystal nucleating agent, an antioxidant, a heat stabilizer, a lubricant, a UV inhibitor, a coloring agent, a plasticizer, and a weathering agent can be added to these synthetic resins as required. , Among which glass fiber, glass flakes, glass beads, carbon fiber, potassium whisker, silica, diatomaceous earth, alumina, titanium oxide, magnesium oxide, talc, clay, mica, asbestos, wollastenite, calcium silicate, calcium carbonate, Montmorillonite, bentonite, boron fiber, aramid fiber, alumina fiber,
When a filler or a reinforcing material such as silicon carbide fiber, ceramic fiber, stone fiber, metal fiber, or the like is appropriately contained, a synthetic resin molded article having higher strength can be obtained.

The flow passages 3a, 3 are formed by secondary injection molding.
The synthetic resin used for forming b is not particularly limited as long as it can be melt-bonded to the divided piece manufactured by the primary injection molding. May be used.

The hollow molded article made of synthetic resin, in which it is particularly effective to provide the branch path portion according to the present invention, includes a hollow molded article having a structure having a chamber and at least two pipes branched from the chamber. It can be widely applied to various industrial applications by taking advantage of the fact that the strength of the joint portion is significantly increased. For example, intake system components such as automobile air intake manifolds, cooling system components such as water inlets and water outlets, and fuels It can be suitably used for hollow parts such as containers in addition to fuel parts such as delivery pipes, tanks such as oil tanks, and the like.

[0022]

EXAMPLES The present invention will be further described with reference to examples, but the present invention is not limited to these examples.

The following Examples and Comparative Examples were molded under the following molding conditions. Molding machine: Die slide injection J-220EII-2M manufactured by Nippon Steel Works Resin temperature: Nylon 6 resin composition 290/290 /
280/270 ° C PPS resin composition 320/320/310/30
0 ° C. However, the same resin temperature was used for both primary injection molding and secondary injection molding. Mold temperature: Nylon 6 resin composition 80 (movable) / 8
0 (fixed) ° C PPS resin composition 130 (movable) / 130 (fixed)
° C

Primary injection speed: 100% Secondary injection speed: 100% Primary injection pressure: 30% Secondary injection pressure: 18% Gate position at the time of secondary injection molding: Four places on the outer peripheral surface, connecting portion between pipes 1 location Primary cooling time: 20 seconds Secondary cooling time: 20 seconds

Example 1 In both primary injection molding and secondary injection molding, a glass fiber reinforced nylon 6 resin composition (CM10
11G30, manufactured by Toray Industries, Inc.). This was injection-molded under the above conditions to obtain the upper and lower divided pieces shown in FIG. By die slide injection in which a part of the mold is slid to engage the two divided pieces in the same mold, secondary injection molding is performed under the above-described conditions to form a flow path portion, and the two divided pieces are formed. To produce a hollow molded article having the shape shown in FIG. The obtained hollow molded product has an inner volume of 500 cc, a general portion thickness of 3 mm, and a flange thickness of 5 mm. The joint portion 30b on the outer peripheral surface has the structure shown in FIG. And the structure of FIG. The pipe-shaped end of the obtained hollow molded product was sealed with epoxy resin, and a water pressure of 1.13 g / sec was applied from the chamber side with an electric water pump (manufactured by Iwaki Co., Ltd.). It exhibited a high breaking strength of 11.2 kg / cm ² withstands an internal pressure load.

Example 2 The same resin composition and molding method as in Example 1 were used to form the joint 3 at the pipe connection.
The structure of Oa was implemented as shown in FIGS. The pressure resistance of the obtained hollow molded article was 13.1 kg / cm ² , showing a high breaking strength against an internal pressure load.

Example 3 The same resin composition and molding method as in Example 1 were used to form the joint 3 at the pipe-to-pipe connection.
The structure of Oa was implemented as shown in FIGS. The pressure resistance of the obtained hollow molded product was 10.6 kg / cm ² , showing a high breaking strength against an internal pressure load.

COMPARATIVE EXAMPLE 1 The same resin composition and molding method as in Example 1 were used to form the joint 3 at the pipe connection.
The structure of Oa was implemented as shown in FIGS. The pressure resistance of the obtained hollow molded product was inferior to 8.8 kg / cm ² .

Example 4 In both primary injection molding and secondary injection molding, a glass fiber reinforced polyphenylene sulfide resin composition (A604X95, manufactured by Toray Industries, Inc.) was used.
According to the same molding method as in the first embodiment, the structure of the joint portion 30a in the inter-pipe connection portion was implemented as shown in FIGS. The pressure resistance of the obtained hollow molded product is 8.1 kg.
/ Cm ² and a high breaking strength against an internal pressure load.

Comparative Example 2 The same resin composition as in Example 4 was used, and as in Comparative Example 1, the structure of the joint portion 30a in the pipe-to-pipe connecting portion was changed as shown in FIGS. Performed by method. The pressure resistance of the obtained hollow molded product was inferior to 6.3 kg / cm ² .

[0031]

By adopting the structure of the synthetic resin hollow molded article according to the present invention, even if there is a joining line located inside the hollow molded article, a hollow molded article having high breaking strength against internal pressure load can be obtained. It can be manufactured by a step injection molding method, and a synthetic resin hollow molded article of excellent quality can be efficiently manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an intake manifold component as an example of a synthetic resin hollow molded product to which the present invention is applied.

FIG. 2 is an enlarged vertical cutaway perspective view of an essential part showing one embodiment of a structure of a joint portion 30a of a connecting portion between pipes of the synthetic resin hollow molded product shown in FIG. 1 according to the present invention.

FIG. 3 is a joint part 30a of the pipe connection part shown in FIG. 2;
FIG. 3 is a vertical cutaway perspective view taken along line III-III in FIG. 2.

4 is an enlarged vertical cutaway perspective view of a main part showing another embodiment of the structure of the joint portion 30a of the connecting portion between pipes of the synthetic resin hollow molded product shown in FIG. 1 according to the present invention.

FIG. 5 is an enlarged vertical cutaway perspective view of a main part showing still another embodiment of the structure of the joint portion 30a of the connecting portion between pipes of the synthetic resin hollow molded product shown in FIG. 1 according to the present invention.

FIG. 6 shows a joint portion 30a of the pipe-to-pipe coupling portion shown in FIG.
FIG. 6 is a longitudinally cutaway perspective view taken along line VI-VI in FIG. 5.

7 is an enlarged vertical cutaway perspective view of an essential part showing one embodiment of a structure of a joining portion 30b on the outer peripheral surface of the synthetic resin hollow molded article shown in FIG.

8 is a cross-sectional view taken along line II-II of the synthetic resin hollow molded article shown in FIG. 1 according to the prior art.

9 is an enlarged vertical cutaway perspective view of a main part showing a structure of a joint portion 30a of a connecting portion between pipes of the synthetic resin hollow molded product shown in FIG. 1 according to the prior art.

10 is a joint part 30 of the pipe connection part shown in FIG. 9;
FIG. 10 is a longitudinally cutaway perspective view showing the structure of FIG.

[Explanation of symbols]

10: Upper split piece, 20: Lower split piece, 30a: Joint at the connecting portion between pipes, 30b: Joint at the outer peripheral surface, 1a: Joint at the upper split piece, 1b:
Joint of lower split pieces, 2: joint line, 3a: flow path at pipe connection, 3b: flow path at outer peripheral surface, 3c: branch path, 4: stress concentration part,
5a, 5b: fusion interface,

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F202 AD12 AG07 AG29 CA11 CB01 CB20 CK11 CK90 4F206 AD12 AG07 AG29 JA07 JB20 JF05 JQ81 4F211 AD12 AG07 AG29 TA08 TC14 TC19 TD01 TN82 TN87

Claims (4)

[Claims] 1. A synthetic resin hollow molded article formed by joining a plurality of synthetic resin divided pieces formed by injection molding at their joints, wherein the joints are formed between the joints. There is a flow path formed by the synthetic resin that has been flowed in for the purpose of fusion bonding, and the flow path extends in the longitudinal direction of the joint, and has a branch path portion branched in a direction intersecting with the longitudinal direction of the joint. A hollow molded article made of synthetic resin, comprising: 2. A reciprocal 2 in which a branch path portion is embedded in a divided piece.
2. A synthetic resin hollow molded product according to claim 1, wherein the cross section is branched in a direction, and a cross-shaped or T-shaped channel cross-sectional shape is formed at the branch point. 3. The hollow molded article made of synthetic resin is a hollow molded article having a structure including a chamber and at least two pipes branched from the chamber, and the branch path portion is formed of two or more pipes.
The synthetic resin hollow molded article according to claim 1, wherein the synthetic resin hollow molded article is provided at a connecting portion between the pipes. 4. A plurality of synthetic resin divided pieces formed by injection molding are molded at positions where the joints are engaged with each other to form a primary hollow molded article in which a flow path is formed between the joints. A method of manufacturing a synthetic resin hollow molded article by disposing a molten synthetic resin into a flow path and then joining the joints by fusion after placing the molten synthetic resin in the mold, wherein the flow path has a longitudinal length of the joint. A method for producing a synthetic resin hollow molded article, comprising: a branch path portion extending in a direction and branching in a direction intersecting with a longitudinal direction of a joining portion.