JP2684878B2 - Hollow resin product molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a hollow resin product for forming a resin product having a hollow portion such as a resin intake manifold assembled in an automobile engine.

[0002]

2. Description of the Related Art An intake manifold for guiding outside air into a cylinder is installed in a vehicle engine. In recent years, this intake manifold is often formed by injection molding using resin as a raw material. When the intake manifold is molded using resin, the intake manifold is composed of two resin molding members, a manifold body and a collector part, each of which has a hollow part in which a passage for air circulation is formed. ing. Although each resin molded member is molded by injection molding, since the inside of each resin molded member is hollow as described above, a core is used when injection molding is performed. There is. As the core, a low melting point material having a lower melting point than the resin material is used.

[0003]

Conventionally, in order to manufacture a hollow resin product as described above, each resin forming member, that is, a manifold body and a collector portion are molded, and then, after each core is eluted, Two resin molded members are joined together on the connecting surfaces. Such a manufacturing method is also called a meltable core method because the core is eluted. However, since the warp peculiar to the resin is generated after molding the molded member molded with the resin as it is, conventionally, the molded member is annealed after the molding. This annealing is a process of holding the product at an appropriate temperature for a predetermined time and then gradually cooling it in order to remove residual strain inside the molded member caused by heat or mechanical stress.

When the intake manifold is molded by resin, two molding members are joined at their respective contact surfaces, and in order to ensure airtightness at the contact surfaces, a sealing material such as an O-ring is provided on the contact surfaces. Is assembled. However, when the intake manifold is manufactured by the conventional manufacturing method, it is not possible to sufficiently secure the seal made on the contact surface, and it may be judged as a defective product by the inspection after manufacturing. There was a problem that was not good. The present invention has been made in view of the above problems of the prior art, and an object thereof is to eliminate the need for maintenance for annealing and improve the product yield.

[0005]

The present invention for achieving the above object has a first resin molding member and a second resin molding member each having a hollow portion, and is formed in each resin molding member. A method for molding a hollow resin product formed by connecting the hollow portions to each other by joining at a joining surface, wherein a core made of a low melting point material having a shape corresponding to the shape of each hollow portion is formed. The first resin molded member and the second resin molded member are resin molded using
After elution of the core of either one of the two resin molded parts,
The hollow resin product molding method is characterized in that the two resin molding members are bonded together on their respective bonding surfaces, and further the core of the other resin molding member is eluted.

[0006]

[Action] Of the two resin molding members each having the integral core, one of the resin molding members is eluted, and then the two resin molding members are joined to each other, and the other resin molding member is joined under the joined condition. Elute the core of the member. In this elution step,
The resin molded member is also heated, and the joint surfaces of the two resin molded members are heated in a state of being in contact with each other, so that the adhesiveness or sealability of the joint surfaces is improved. Also,
Since the resin refining member is heated for the final elution, the annealing step is unnecessary and the molding efficiency is greatly improved.

[0007]

EXAMPLES A method for molding the hollow resin product shown in the drawings will be described below with reference to the drawings. FIG. 1 is a diagram showing each step in the molding method of the present invention, and FIG. 2 is a resin intake manifold 10 as an example of a hollow resin product.
FIG. 3 is a view showing a manifold main body 11 which constitutes FIG.
FIG. 4 is a diagram showing a collector section 12. FIG. 2 and FIG.
FIG. 3 is a view showing a state in which each resin molded member, that is, the manifold main body 11 and the collector portion 12 are molded by injection molding. A core 13 for forming a hollow portion in these resin molded members 11, 12 at the time of molding, 14 is integrated with the resin molded members 11 and 12.

As described above, one of the two resin molded members 11 and 12 molded by injection molding, for example, the core 1 integrated with the collector portion 12 shown in FIG.
Elute 4. The material of the core 14 is a core 13
Similarly, a low melting point alloy such as an alloy of Sn and Bi (melting point is 138 ° C.) is used, and only the core 14 can be eluted without melting the resin. FIG. 4 is a view showing a state where the core 14 integrated with the collector portion 12 is eluted. In this way, after the core 14 of the collector portion 12 which is one resin molding member is eluted, the core 13 of the manifold main body 11 which is the other resin molding member is eluted.
Of these two resin molded members 11,
12 are bonded to each other on the bonding surfaces. In FIG. 5, the collector portion 12 after the core 14 is eluted is attached to the manifold main body 11 in which the core 13 is integrated with each of the joint surfaces 1.
It is a figure showing the state where it joined in the portion of 5 and 16. However, before joining, an O-ring 17 for maintaining airtightness between the joining surfaces is assembled to the joining surface 15 of the manifold body 11 as shown in FIG.

In this way, the two resin molding members 1
After joining 1 and 12, the core 13 in the manifold body 11 is eluted. The molding procedure described above is schematically shown in FIG. 1, which is a molding step 21 for molding the manifold body 11 and the collector portion 12 by injection molding.
And a first elution step 22 of elution of the core 14 of one resin molding member such as the collector portion 12, and these 2
Joining step 23 for joining one resin molded member to each other and second elution step 2 for leaching the core 13 of the other resin molded member
4 and 4 are included in the molding method of the present invention. However, the core 13 in the manifold body 11 is eluted in the first elution step 22, and the core 1 of the other resin molded member is eluted in the second elution step 24.
4 may be eluted. In these elution steps, the entire resin including the resin molding member is, for example, 140 ° C.
Heat to a degree.

In the present invention, the two resin molding members 1
Since 1 and 12 are forcibly joined to each other at the joining surfaces 15 and 16 and are heated together with the resin molding member in order to elute the core 13, the joining surfaces 15 and 1 after the molding are performed.
In No. 6, warpage does not occur, and the airtightness and sealing property in this portion can be sufficiently secured. Moreover, in the second elution step 24, since the entire resin molding member for elution of the core 13 is heated, the resin product 10 can also be annealed in this step, and the equipment therefor becomes unnecessary. In addition to the intake manifold 10 shown in the drawings, the present invention can be applied to various resin products having a hollow portion inside.

[0011]

As described above, according to the present invention, the sealing property at the joint surface between two resin molding members is improved,
Moreover, the conventionally used apparatus for annealing is no longer required, and it has become possible to mold high-quality resin products at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic process diagram showing a procedure of a method for molding a hollow resin product of the present invention,

FIG. 2 is a perspective view showing the manifold main body after completion of injection molding,

FIG. 3 is a perspective view showing a collector portion after completion of injection molding,

FIG. 4 is a perspective view showing a collector portion after the core is eluted,

FIG. 5 is a perspective view showing a state in which two resin molded members are joined to each other,

FIG. 6 is a cross-sectional view showing a part of the manifold main body after the O-ring is attached.

[Explanation of symbols]

10 ... Resin product (intake manifold), 11 ... Manifold main body (first resin molding member), 12 ... Collector (second resin molding member), 13, 14 ... Core, 15, 1
6 ... Bonding surface. 22 ... 1st elution process, 24 ... 2nd elution process.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B29L 31:30

Claims (1)

(57) [Claims] 1. A first resin molding member and a second resin molding member each having a hollow portion, and the hollow portions are made to communicate with each other by joining at a joint surface formed on each resin molding member. A method for molding a hollow resin product to be formed, wherein the first resin molding member and the second resin molding member are formed using cores made of a low melting point material each having a shape corresponding to the shape of the hollow portion. After resin molding and elution of the core of either one of the two resin molded members, the two resin molded members are joined at their respective joint surfaces, and the core of the other resin molded member is eluted. A method for molding a hollow resin product, characterized in that