JP2519481B2 - Manufacturing method of pipe with flange - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention comprises a blow-molded resin-made bent pipe main body and a resin-made flange portion that is externally mounted on the end of the bent pipe main body. To produce a flanged pipe comprising For example, it is suitable for manufacturing a pipe that connects a hose and a device in an engine intake pipe or a pipe that requires airtightness related to an air conditioner.

In the present invention, "heat resistance" means a continuous heat resistance temperature of about 13
It means one having a temperature of 0 ° C or higher.

<Prior Art> FIG. 6 shows a conventional flanged pipe (hereinafter referred to as “pipe”) 1 used as an intake pipe for an engine.

This pipe 1 has a bent pipe body 3 and a flange portion 5.
The flange portion 5 is provided with two screw holes 7 for fixing to the engine body (not shown). The bent pipe body 3 is connected to a port portion 9 made of a rubber hose, and the port portion 9 is gathered at a chamber portion 11 to form a so-called inlet manifold portion.

Pipe 1 fixed directly to the engine body as described above
Were typically manufactured from aluminum die cast to withstand the heat of the engine. However, from the standpoint of reducing material costs and reducing the weight around the engine, pipe 1
It has been attempted to mold a resin material by injection. Thus, by injection molding, the pipe body 3 and the flange portion 5 (including the screw hole 7) can be integrally molded, and the product is lighter than the product made of aluminum die casting. Regarding the heat resistance of resin materials, the recent development of materials has provided polyamides, polyphenylene sulfides, etc. (and those filled with inorganic fillers) that can withstand sufficient use ( See JP-A-58-82059, 59-198116, etc.).

However, when a pipe is injection-molded, there is a problem with the core. That is, when the pipe body is bent linearly or concentrically, the core could be slid out, but recently, due to the complexity of the engine, the pipe body has been three-dimensionally It is forced to bend. Therefore, it becomes impossible to slide out the core, and the pipe cannot be manufactured by injection.

Although a method of forming the core with fusible gold and melting and removing the core can be considered, it is not practical because it takes too much time.

Therefore, the inventors of the present invention have devised a flanged pipe comprising a blow-molded resin-made bent pipe body and a resin-made flange portion that is exteriorly mounted on the original end of the bent pipe body ( See Japanese Patent Application No. 61-201151; JP-A-63-56426).

Since the bent pipe main body of this pipe is a blow-molded product, the problem of the core as in the case of molding by injection does not occur even if the pipe is three-dimensionally bent. Since the flange portion is fixed to such a bent pipe body, a pipe having a resin-made three-dimensionally bent bent pipe body can be easily molded.

<Problems to be Solved by the Invention> However, in the pipe having the above structure, the bent pipe main body and the flange portion are separate bodies, so in order to obtain reliable airtightness between them, the bent pipe main body The dimensional variation of each of the original end and the flange is severely limited. Also, when a parting line appears on the mating surface of both, deburring work is required. Such a restriction impedes the improvement in the productivity of the flanged pipe having the above configuration.

Therefore, an object of the present invention is to provide a method for easily manufacturing the flanged pipe having the above-described structure while obtaining sufficient airtightness between the bent pipe body and the flange portion.

<Means for Solving Problems> As a result of intensive studies to achieve the above object, the present inventors have found that it is sufficient to bond the bent pipe body and the flange portion with a hot melt adhesive, After blow molding the bent pipe main body in which the mounting groove is continuously formed on the outer peripheral surface of the straight portion, a string-shaped hot melt adhesive is mounted in the mounting groove, and the hot melt adhesive layer is continuously formed in the circumferential direction. Formed, and the original end of the bent pipe main body is mounted as a cavity insert of the molding die for the flange portion, and a resin material having a temperature equal to or higher than the melting temperature of the hot melt adhesive is injected into the cavity. The flanged pie of the present invention, which is heat-resistant to ensure airtightness between the bent pipe body and the flange portion, by molding the flange portion and using a hot-melt adhesive layer. Invented a method of manufacturing

<Examples> Hereinafter, the present invention will be described in detail based on Examples.

The manufacturing method of the embodiment includes a step of blow-molding the bent pipe body 23, a step of forming the hot melt adhesive layer 24 on the end portion of the bent pipe body 23, and a step of injection-molding the flange portion 31.

Blow-molding the bent pipe body 23 (FIG. 1) The bent pipe body 23 has a three-dimensionally bent shape (see FIG. 5), and the engine and the port portion 9 are formed similarly to the conventional example.
To connect. Circumferential bulge on the side connected to the port 9
25 is formed so that the bent pipe body 23 does not go into the port portion 9. Further, a cylindrical straight portion 27 and a locking flange 29 are formed on the entire circumference of the end portion of the cylindrical straight portion 27 at the end portion to which the flange portion 31 is fixed. Straight part
On the outer peripheral surface of 27, a mounting groove 28 for mounting a string-shaped hot melt adhesive is continuously formed in the circumferential direction. The locking flange 29 is preferably formed with a protrusion or a notch portion for preventing rotation.

Such a bent pipe body 23 is made of, for example, a thermoplastic resin material having high heat resistance (polyamide such as nylon 6, nylon 66, polyphenylene sulfide, etc., or those filled with an inorganic filler such as glass fiber). Used and molded by standard blow. When the inorganic filler is filled, considering that the heat effect becomes smaller as it goes away from the engine (flange portion 31), the filling density of the inorganic filler is inclined (the flange portion 31 side has a high density and the port portion 9 has a high density). It can also be formed by attaching (side to low density). Further, the port portion 9 side of the bulging portion 25 may be formed in a bellows shape and extended from the figure, and the port portion 9 may be substituted by giving plasticity to the portion.

Step of forming the hot melt adhesive layer 24 on the original end of the bent pipe body 23. A string-shaped hot melt adhesive is attached to the mounting groove 28 formed in the straight portion 27 of the bent pipe body 23 to form a ring shape. That is, the hot melt adhesive layer 24 that is continuous in the circumferential direction is formed.

Examples of the adhesive used for the string-shaped hot-melt adhesive include ethylene-vinyl acetate copolymer-based adhesives, polyamide-based adhesives, polyester-based adhesives, and the like.

Further, the hot-melt adhesive layer 24 is not particularly limited in its cross-sectional shape as long as it is continuous with the straight portion 27 in the circumferential direction, and can have a rectangular cross-section as shown in FIG. 3 (hot-melt adhesive agent). Layer 24a). Further, the method of forming the hot melt adhesive on the bent pipe body 23 is not particularly limited.

Process of injection molding the flange portion (Fig. 2) The flange portion 31 is a straight portion 27 of the bent pipe body 23.
And a ring-shaped member fitted to the outer peripheral surface of the locking flange 29, and has two screw holes 33 as shown in FIG. The portion where the screw hole 33 is formed is the thick wall portion 35.
It is said that it is reinforced.

As shown in FIG. 2, the flange portion 31 is formed by connecting the original end of the bent pipe body to the cavity 39 of the molding die 36 for the flange portion.
It is mounted as an insert into a flange, and a flange forming material having a temperature equal to or higher than the melting temperature of the hot melt adhesive is passed through a sprue, runner and gate (not shown) to make a cavity.
It is injected into 39 and injection molded. Reference numeral 37 is a slide core.

The temperature above the melting temperature of the hot melt adhesive is about 200 ° C.

When the injection temperature of the material for forming the flange portion 31 is equal to or higher than this temperature, the hot melt adhesive is melted and the airtightness is secured between the flange portion and the bent pipe body.

The material for forming the flange portion 31 is to be directly attached to the engine, and thus needs to be formed of a heat resistant material. In this embodiment, the same thermoplastic resin as the material for forming the bent pipe body 23 such as polyamide is used. The bent pipe body 23 and the flange
From the viewpoint of improving the adhesiveness, it is preferable that the forming materials of 31 and 31 are the same kind of materials that fuse with each other. For example, the material forming the flange portion 31 is nylon 66, and the material forming the bent pipe body 23 is nylon 6.

When the mold is opened after the injection work is completed, both members are bonded,
The flanged pipe 21 apparently shown in FIG. 5 is obtained.

The shape of the flange portion 31a may be such that it surrounds the straight portion 27 and the engaging flange 29 of the bent pipe body 23 as in the fourth embodiment.

[Brief description of drawings]

1 to 6 show an embodiment of the present invention, FIG. 1 is a sectional view showing a bent pipe main body 23 and a hot melt adhesive layer 24 of a blow molded product, and FIG. 2 is a bent pipe main body 23 and a hot melt adhesive layer. 24 is a sectional view showing a state in which 24 and 24 are set as inserts in a molding die of the flange portion 31, FIG. 3 is a sectional view showing a hot melt adhesive layer 24a having another shape, and FIG. 4 is a flange portion having another shape. 31a is a cross-sectional view, FIG. 5 is a front view of the flanged pipe 21 manufactured by the manufacturing method of the embodiment (the line AA is a cross-sectional direction line in FIGS. 1 to 5),
FIG. 6 is a perspective view of a conventional pipe 1 with a flange. 1,21 …… Flanged pipe, 3,23 …… Bent pipe main body, 24,24a …… Hot melt adhesive layer, 5,31,31a …… Flange part, 36 …… Molding die, 39 …… Cavity .

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Claims (1)

(57) [Claims] 1. A flanged pipe comprising a blow-molded resin-made bent pipe main body and a resin-made flange portion which is mounted on the original end of the bent pipe main body, and which is required to have heat resistance. In the method for producing, a blow pipe main body is formed by continuously forming a mounting groove in the outer peripheral surface of the straight portion in the circumferential direction, and then, in the mounting groove, a string-shaped hot melt adhesive is mounted. ,
A hot melt adhesive layer is continuously formed in the circumferential direction, and the original end of the bent pipe body is mounted as a cavity insert of a molding die for the flange portion, and the melting temperature of the hot melt adhesive is equal to or higher than the melting temperature. The flange portion forming material at the temperature of is injected into the cavity to form the flange portion, and the hot melt adhesive layer ensures the airtightness between the bent pipe body and the flange portion. Method for manufacturing flanged pipe.