JPS63295852A - Manufacture of synthetic resin intake pipe for engine - Google Patents

Abstract

PURPOSE:To prevent the dislocation of a core from the predetermined position when synthetic resin is injected, and ensure high product accuracy by supporting the core with support pins and drawing out the support pins from a synthetic resin layer prior to the solidification thereof. CONSTITUTION:A filler 21 is filled in a blow-molded bend pipe 20 so as to prevent the deformation thereof due to high pressure in an injection molding process. The bend pipe 20 is set as a core in a metal mold 22 for injection molding. The mold 22 is provided with a pair of opposing injection gates 24 and 24, and a pair of support pins 25 and 25 are provided at positions orthogonal with the gates 24 and 24. A thermo-plastic synthetic resin material is injected into the mold 22, thereby filling a space 23 formed by the mold 22 and the bend pipe 20. The support pins 25 and 25 are made to retreat in the mold 22 before the synthetic resin material solidifies. And the mold 22 is opened and the filler 21 is removed from the bend pipe 20.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a synthetic resin intake pipe used in an automobile engine.

(Prior Art) Conventionally, as a method for manufacturing a synthetic resin intake pipe, the method disclosed in, for example, Japanese Patent Application Laid-Open No. 58-82059 is known.

In this conventional manufacturing method, a hollow core made of a low melting point alloy is prepared in advance, the hollow core is set in an injection mold, and then a thermoplastic synthetic resin is injected into the mold. After the resin is solidified, it is heated at a temperature at which only the hollow core made of the low melting point alloy melts without melting the resin, and the hollow core is eluted to obtain a synthetic resin intake pipe.

(Problems to be Solved by the Invention) However, in this conventional manufacturing method, support for the hollow core during synthetic resin injection, especially at the injection gate portion of the synthetic resin, was insufficient, so the resin There is a problem in that the hollow core may be displaced from a predetermined position due to the injection pressure, etc., and the thickness of the synthetic resin layer may not be constant.

(Method for Solving the Problems) The present invention aims to solve the above-mentioned problems, and in order to achieve this purpose, the present invention has a bent shape corresponding to the shape of the intake pipe. A core is formed, the core is placed in an injection mold having an intake pipe shape, and at least one pair of cores are provided on a plane including injection gates provided facing each other in the injection mold. After that, the synthetic resin material is injected from the injection gate between the mold and the core, and the support pins are pulled out from the synthetic resin layer before the synthetic resin layer solidifies. This method is characterized by the fact that

(Function) Therefore, according to the method of manufacturing a synthetic resin intake pipe for an engine of the present invention, the synthetic resin is injected from the opposing injection gates, and at the time of this injection, at least one core is placed on the same plane as the injection gate. Since the core is supported by a pair of support pins, the injection pressure on the core is canceled out, making it difficult for the core to be misaligned.Furthermore, the core is supported by the support pin on the same plane that receives this injection pressure. This makes it even more difficult for the core to become misaligned.

Therefore, it is possible to prevent the core from shifting from a predetermined position during injection of the synthetic resin, thereby making it possible to maintain a constant thickness of the synthetic resin layer and obtain a constant product accuracy.

In addition, since the support pin is removed from the synthetic resin layer before the synthetic resin solidifies, the plastic resin around it flows into and fills the hole in the synthetic resin layer created by the support pin, and when it solidifies, the support pin hole is formed in the intake pipe. It never gets cold.

(Example) Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a sectional view showing a first embodiment of a synthetic resin intake pipe for an engine (hereinafter referred to as an intake pipe) according to the present invention.

The intake pipe 10 includes an inner layer 11 made of blow molding, and an inner layer 1 made of blow molding.
1, a flange portion 13 integrally formed at the end of this outer layer 12, and a duct portion 14.
The inside of the duct portion 14 is an intake pipe line 15. Further, the inner layer 11 and the outer layer 12 are formed to have uniform thickness.

Note that the ventilation pipe 16 is connected to a pickup pipe of an intake air amount sensor, a blow-by gas recirculation pipe, and the like.

Next, a method for manufacturing the intake pipe 10 shown in FIG. 2 will be explained step by step.

First, as shown in FIG. 2(a), a bent pipe 20 matching the shape of the intake pipe path 15 in the intended intake pipe 10 is created by blow molding. As is well known, blow molding allows the curved pipe 20 to be formed no matter how complicated its shape.

Next, as shown in FIG. 2(b), the bent pipe 2 is blow-molded.
0 is filled with a filler 21 that does not deform the shape of the bent tube 20 against high pressure during injection molding, such as fine sand such as ceramics or an incompressible liquid.

Thereafter, as shown in FIG. 2(C), the bent pipe 20, which has been treated to prevent deformation, is set as a core in an injection mold 22.

As shown in FIG. 3, which is a cross-sectional view, and FIG. 4, which is a longitudinal sectional view, this injection mold 22 is provided with a pair of injection games 24, 24 facing each other at a plurality of locations. , and a pair of support pins 25, 25 are provided on the same plane containing the pair of injection gates 24.degree. 24 and at positions perpendicular to a line connecting the injection gates 24.degree. This support pin 25 is provided so as to be able to move in and out of the mold 22, and by supporting the bent tube 20 (core) with this support pin 25 in a protruding state, the above-mentioned target tube 20 is set. .

In this state, as shown in FIG. 2(d), a thermoplastic synthetic resin material is injected into the injection mold 22, and the mold 22 and the bent pipe 2 are
The space 23 formed by 0 and 0 is filled.

When this synthetic resin is injected, injection pressure is applied to the bent tube (core) 20, but since the injection gates 24 and 24 are facing each other, this injection pressure is canceled out and has little effect on the bent tube (core) 20. Child) 20 is less likely to be misaligned.

Furthermore, since the bent tube 20 is made of resin by blow molding, there is a risk that it may deform or move in a direction perpendicular to the injection gate 24 due to the injection pressure. Since it is supported by 25, its deformation and movement are unlikely to occur.

Note that the molding conditions at this time are carried out in accordance with conventional methods, taking into consideration the materials used, shape, etc.

Then, when the support pin 25 is moved into the mold 22 from the outer layer 12 (the part that was the space 23) while the synthetic resin is still plastic before solidifying, the support pin 25 is positioned. The resin also flows into the exposed areas and fills them with resin.

Thereafter, the synthetic resin solidifies, and the outside of the bent pipe 20 is integrally covered with the injected synthetic resin material to form the outer layer 12. At the same time, a flange portion 13 is formed at one end and a duct portion 14 is formed.
A ventilation pipe 16 is formed.

When the molding is completed, the mold 22 is opened to take out the molded product, the filler 21 inside the bent tube 20 is taken out, and further,
The intake pipe 10 shown in FIG. 1 can be obtained by making a hole in the inner layer 11 with the same diameter as the inside diameter of the ventilation pipe 16 to serve as the pipe hole 16a.

FIG. 5 is a sectional view showing a second embodiment of the intake pipe 10 according to the present invention.

This second embodiment is an example in which the strength of the flange portion 13 and the ventilation pipe 16, which are functional parts, is further increased.

Next, a method for manufacturing the intake pipe IO shown in FIG. 5 will be explained step by step.

First, as shown in FIG. 6(a), a bent pipe 20 matching the shape of the intake pipe path 15 in the intended intake pipe 10 is created by blow molding.

When the bent pipe 20 is blow-molded, the flange projection 20a and the ventilation pipe projection 20b are also molded at the same time.

Next, as shown in FIG. 6(b), the bent pipe 2 is blow-molded.
0 is filled with a filler 21 that does not deform the shape of the bent pipe 20 against high pressure during injection molding.

Thereafter, as shown in FIG. 6(C), the bent pipe 20, which has been treated to prevent deformation, is set as a core in an injection mold 22.

This mold has a pair of injection gauges as shown in Figure 7.
24. Two pairs of support pins 25.25 on the same plane as 24,
25.25 is provided, and the bent pipe 20 is set by supporting it with this support pin 25.

In this state, as shown in FIG. 6(d), a synthetic resin material is injected into the injection mold 22, filling the space 23 formed by the mold 22 and the bent pipe 20, and the synthetic resin material is Before solidification, the support pins 25 are moved into the mold 22 from the outer layer 12 (the part that was the space 23), and the space 23 where the support pins 25 were located is filled with resin.

After that, the synthetic resin is solidified, and the outside of the bent pipe 20 is integrally covered with the injected synthetic resin material to form the outer layer 12, and the flange part 13 having the reinforcing inner layer 13a at one end is attached to the duct part. 14 is formed with a ventilation pipe 16 having a reinforcing inner layer 16b.

When the molding is completed, the mold 22 is opened to take out the molded product, the filler 21 inside the bent tube 20 is taken out, and further,
Cut the upper part of the ventilation pipe protrusion 20b and make a pipe hole 16.
By setting a, the intake pipe IO shown in FIG. 5 can be obtained.

As described above, according to the method for manufacturing the intake pipe IO of this embodiment, the following effects are achieved.

■ Injection gate 24.2 facing the injection of this synthetic resin
4, the injection pressure is canceled out and the effect on the bent tube (core) 20 is small.
Positional deviation of 20 is less likely to occur.

Therefore, the thickness of the outer layer 12 can be made constant and product precision can be improved.

■ Since the bent tube (core) 20 is made of resin by blow molding, there is a risk that it may deform or move in a direction perpendicular to the injection gate 24 due to the injection pressure. Since it is supported by the support pins 25, deformation and movement of the outer layer 12 is difficult to occur.This also makes it possible to keep the thickness of the outer layer 12 constant and improve product precision.

■ Bent pipe 2 made of synthetic resin molded by blow molding
0 is integrated with the product while performing the function of a core during injection molding, so a separate core molding process and core elution process by heating are no longer required, and the synthetic resin intake pipe 10 can be manufactured with fewer steps. It can be manufactured in a short time and at low cost.

■ The synthetic resin oil pipe 2° made by blow molding becomes the inner layer 11 of the intake pipe 10 finally obtained, and this inner layer 11
The double structure of the outer layer 12 formed by injection molding prevents variations in tube thickness and ensures high tube strength.

(2) Since the flange portion 13 and ventilation pipe 16, which are functional parts, are formed together with the outer layer 12 during injection molding, there is no need for molding or joining in a separate process, and the process for adding functional parts can be omitted.

- Since the flange portion 13 and the ventilation vibrator 16, which are functional parts, are formed integrally with the outer layer 12, their strength and reliability are high even when subjected to external forces.

■ In the second embodiment, the functional parts such as the flange part 13 and the ventilation vibrator 16 have a double structure with inner and outer layers, so the strength of the functional parts is further improved, and especially high breaking stress (such as vibration and fatigue) is achieved. ) is useful when added.

Although the present invention has been described above with reference to examples, the specific manufacturing process is not limited to these examples, and there may be additions or changes to the process without changing the gist of the present invention. are also included in the present invention.

For example, in the above embodiment, the bent pipe 20 formed by blow molding and serving as the inner layer of the intake pipe is used as the core, but a low melting point alloy may be used as the core.

Moreover, although the case where the wall thickness of the bent pipe 20 is approximately uniform has been described, it is also possible to change the wall thickness depending on strength requirements.

In this case, it may be selected arbitrarily at the time of blow molding.

Furthermore, the curved shape is not limited to one location, but may be provided at multiple locations.In this case as well, since this can be done during blow molding, there is no need to take any special steps during injection molding.

Further, in the embodiment, an example of a ventilation pipe is shown as a functional part formed to protrude from the intake pipe, but a mounting screw part or other protruding functional part may be formed.

Further, as shown in FIG. 8, during blow molding, an uneven rough surface 13b may be formed on the flange projection 13a to enhance the adhesion between the inner and outer layers 13a and 13 due to the anchor effect.

Further, when the intake pipe according to the present invention is attached to an engine, it may be of a type provided at a place where outside air is directly taken in, or of a type connected to the supercharging side of a turbocharger. Moreover, the system is not limited to a system in which the system is directly attached to the engine, but a system in which the system is installed in a path that forms an intake passage that communicates with the engine may be used.

(Effects of the Invention) As described above, in the manufacturing method of the present invention, synthetic resin is injected from opposing positions, and at least one pair of support pins are provided on a plane including an injection gate for performing this injection. By supporting the core and pulling out the support pin from the synthetic resin layer before the synthetic resin layer solidifies, it is possible to prevent the core from shifting from the specified position due to injection pressure etc. during injection of the synthetic resin. This makes it possible to maintain a constant thickness of the synthetic resin layer and obtain high product accuracy, and also to prevent holes formed by the support pins from forming in the intake pipe.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a first embodiment of a synthetic resin intake pipe for an engine according to the present invention, Fig. 2 is an explanatory diagram showing the manufacturing process of the first embodiment, and Fig. 3 is a cross-sectional view of the first embodiment. 4 is a longitudinal sectional view showing the manufacturing process of the first embodiment; FIG. 5 is a sectional view showing the second embodiment of the synthetic resin intake pipe for engines according to the present invention; Fig. 6 is an explanatory diagram showing the manufacturing process of the second embodiment, Fig. 7 is a longitudinal sectional view showing the manufacturing process of the second embodiment, and Fig. 8 is a sectional view of main parts showing another reinforcing structure of the flange part. It is. 10... Synthetic resin intake pipe for engine 12... Outer layer (synthetic resin layer) 15... Intake pipe line (pipe line) 20... Bent pipe (core) 22... Injection molding metal Mold 24...Injection gate 25...Support pin patent application Hito Nippon Radiator Co., Ltd. Figure 3

Claims (1)

[Claims] (1) A core with a curved shape corresponding to the shape of the intake pipe is formed, this core is placed in an injection mold forming the shape of the intake pipe, and the core is placed facing the inside of the injection mold. The core is supported by at least one pair of support pins provided on a plane including an injection gate provided at A method for manufacturing a synthetic resin intake pipe for an engine, characterized in that the support pin is removed from the synthetic resin layer before the resin solidifies.