JPH081157B2 - Manufacturing method of synthetic resin intake pipe for engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a synthetic resin intake pipe used in an automobile engine.

(Prior Art) Conventionally, as a method for manufacturing a synthetic resin intake pipe, for example, the one disclosed in JP-A-58-82059 is known.

In this conventional manufacturing method, a hollow core formed of a low melting point alloy is prepared in advance, the hollow core is set in an injection molding die, and then a thermoplastic synthetic resin is injected into the die. ,
After the resin is solidified, the resin is not melted and heated at a temperature at which only the hollow core made of the low melting point alloy is melted, 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, since the hollow core was not sufficiently supported at the time of injection of the synthetic resin, particularly, the support at the injection gate portion of the synthetic resin was insufficient, There is a problem that the hollow core may be displaced from a predetermined position due to the injection pressure or the like and the thickness of the synthetic resin layer may not be constant.

(Method for Solving Problems) An object of the present invention is to solve the above problems, and in order to achieve this object, the present invention has a curved shape corresponding to the shape of the intake pipe. A core is formed, the core is placed in an injection-molding die having an intake pipe shape, and at least one pair is provided on a plane including an injection gate provided in the injection-molding die so as to face each other. The core is supported by the support pin that is provided, then the synthetic resin material is injected from the injection gate between the mold and the core, and the support pin is pulled out from the synthetic resin layer before the synthetic resin layer solidifies. The method is characterized in that

(Operation) Therefore, according to the method for manufacturing the engine synthetic resin intake pipe of the present invention, the synthetic resin is injected from the opposing injection gates, and at the time of this injection, the core is at least 1 flush with the injection gate. Since it is supported by the support pin provided in a pair, the injection pressure to the core is offset and the position shift is unlikely to occur in the core, and further, the core is supported by the support pin in the same plane as receiving this injection pressure. As a result, it becomes more difficult for the core to be displaced.

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

Further, since the support pin is pulled out from the synthetic resin layer before the solidification of the synthetic resin, the plastic resin around the support pin flows into and is filled in the hole of the synthetic resin layer generated by the support pin. There is no opening.

(Examples) Examples of the present invention will be described below with reference to 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, an outer layer 12 coated on the outer periphery of the inner layer 11, a flange portion 13 integrally formed at an end portion of the outer layer 12, and a duct 14 in the middle thereof. A ventilation pipe (protruding functional portion) 16 formed integrally with the duct portion 14 is provided with an intake pipe line 15.
Further, the inner layer 11 and the outer layer 12 are formed to have a uniform thickness.

The ventilation pipe 16 is connected with a pickup pipe of an intake air amount sensor, a blow-by gas recirculation pipe, or the like.

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

First, as shown in FIG. 2 (a), a bend pipe 20 corresponding to the shape of the target intake pipe 15 in the intake pipe 10 is formed by blow molding. As is well known, blow molding enables molding of the bent tube 20 no matter how complicated the shape thereof.

Next, as shown in FIG. 2 (b), blow-molded bent pipe
A filling material 21 that does not deform the shape of the bent tube 20 against the high pressure at the time of injection molding, for example, fine sand particles such as ceramics or an incompressible liquid is filled in the inside 20.

After that, as shown in FIG. 2 (c), the bent tube 20 which has been treated so as not to be deformed is set in a mold 22 for injection molding as a core.

This injection molding die 22 is provided with a pair of injection gates 24, 24 facing each other at a plurality of positions, as shown in FIG. And this one
A pair of support pins 25, 25 are provided on the same plane including the pair of injection gates 24, 24 at a position perpendicular to the line connecting the injection gates 24, 24. The support pin 25 is provided so as to be able to move in and out of the mold 22, and the bend pipe 20 (core) is supported by setting the support pin 25 in a protruding state to set the bend pipe 20.

In this state, as shown in FIG. 2D, a thermoplastic synthetic resin material is injected into the injection molding die 22 and filled in the space 23 formed by the die 22 and the bent pipe 20.

The injection pressure is applied to the bending pipe (core) 20 at the time of injecting the synthetic resin, but since the injection gates 24 and 24 are opposed to each other, the injection pressure is canceled and the influence on the bending pipe 20 is small. (Child) 20 is less likely to be misaligned.

In addition, since the bent pipe 20 is made of resin by blow molding, there is a possibility that the bent pipe 20 may be deformed in the direction perpendicular to the injection gate 24 due to the injection pressure or may try to move in that direction. Since it is supported by 25, its deformation and movement are unlikely to occur.

The molding conditions at this time are set in accordance with a conventional method in consideration of materials used, shapes and the like.

Then, while the synthetic resin has plasticity before solidifying, the support pin 25 is attached to the outer layer 12 (the portion which was the space 23).
When retracted into the mold 22 from, the resin also flows into the portion where the support pin 25 was located and is filled with the resin.

Thereafter, the synthetic resin is solidified, and the outer side of the bent pipe 20 is integrally covered with the injected synthetic resin material to form the outer layer 12, and the flange portion 13 is provided at one end portion and the ventilation pipe is provided at the duct portion 14. 16 are formed.

When the molding is completed, the mold 22 is opened, the molded product is taken out, the filling material 21 in the bent pipe 20 is taken out, and the same hole as the inner diameter of the ventilation pipe 16 is opened in the inner layer 11 to make the pipe hole 16a.
Thus, the intake pipe 10 shown in FIG. 1 can be obtained.

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

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

Next, a method of manufacturing the intake pipe 10 shown in FIG. 5 will be described step by step.

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

During blow molding of this bent pipe 20, the protrusion for the flange
20a and the ventilation pipe projection 20b are also molded at the same time.

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

Thereafter, as shown in FIG. 6 (c), the bent tube 20 which has been treated so as not to be deformed is set in the injection molding die 22 as a core.

This mold has a pair of injection gates as shown in FIG.
Two pairs of support pins 25, 25, 25, 25 are provided on the same plane as 24, 24, and the bent pipe 20 is set by being supported by the support pins 25.

In this state, as shown in FIG. 6 (d), a synthetic resin material is injected into the injection molding die 22 and filled in the space 23 formed by the die 22 and the bent pipe 20. Support pin 25 before solidification
Is withdrawn from the outer layer 12 (the part that was the space 23) into the mold 22, and the space 23 in the part where the support pin 25 was located is filled with resin.

Thereafter, the synthetic resin is solidified, and the injected synthetic resin material is integrally coated on the outside of the bent pipe 20 to form the outer layer 12, and the flange portion 13 having the reinforcing inner layer 13a at one end.
However, the ventilation pipe 16 having the reinforcing inner layer 16b is formed in the duct portion 14.

When the molding is completed, the mold 22 is opened, the molded product is taken out, the filler 21 in the bent pipe 20 is taken out, and further, the upper portion of the ventilation pipe projection 20b is cut to form the pipe hole 16a. The intake pipe 10 shown in FIG. 5 can be obtained.

As described above, according to the method for manufacturing the intake pipe 10 of the present embodiment, the following effects can be achieved.

Since the injection of the synthetic resin is performed from the injection gates 24, 24 facing each other, the injection pressure is canceled out, and the influence on the bent pipe (core) 20 is small, and the displacement of the bent pipe (core) 20 is unlikely to occur. . Therefore, the thickness of the outer layer 12 can be made constant, and the product precision can be improved.

Since the bent pipe (core) 20 is made of resin by blow molding, there is a possibility that it may be deformed in the direction perpendicular to the injection gate 24 by the injection pressure or may try to move in that direction. Since it is supported by the support pin 25, its deformation and movement are unlikely to occur. Therefore, also by this, the product accuracy can be improved while keeping the thickness of the outer layer 12 constant.

Bent pipe 20 made of synthetic resin molded by blow molding
Since it integrates with the product while performing the function of the core during injection molding, an independent core molding process and core elution process by heating are unnecessary, and the number of synthetic resin intake pipes 10 is reduced. It can be manufactured in a short time and at low cost.

The synthetic resin bent pipe 20 formed by blow molding becomes the inner layer 11 of the finally obtained intake pipe 10, and the double structure of this inner layer 11 and the outer layer 12 formed by injection molding prevents variation in pipe thickness and ensures high pipe strength. Ensuring is achieved.

Since the flange portion 13 and the ventilation pipe 16 which are the functional portions are formed at the time of injection molding together with the outer layer 12, molding or joining in a separate step is not required, and the step for adding the functional portion can be omitted.

Since the flange portion 13 and the ventilation pipe 16 which are the functional portions are formed integrally with the outer layer 12, the strength reliability is high even if an external force is applied.

In the second embodiment, the flange portion that is the functional portion
Since the 13 and the ventilation pipe 16 have a double structure of inner and outer layers, the strength of the functional portion is further improved, which is particularly useful when a large breaking stress (vibration, fatigue, etc.) is applied.

Although the present invention has been described above with reference to the embodiment, the specific manufacturing process is not limited to this embodiment, and there are additions and modifications of the process within the scope not changing the gist of the present invention. Also included in the present invention.

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

Further, the case where the wall thickness of the bent pipe 20 is made substantially uniform has been described, but the wall thickness can be changed according to the strength requirement.

In this case, the blow molding may be arbitrarily selected.

Further, the curved shape is not limited to one place, and may be provided at a plurality of places. Also in this case, since it can be treated during blow molding,
No special treatment is required during injection molding.

Further, in the embodiment, the ventilation pipe is shown as an example of the functional portion formed so as to project on the intake pipe, but a mounting screw portion or another protruding functional portion may be formed.

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

Further, when the intake pipe according to the present invention is attached to an engine, it may be a type provided at a place for directly sucking the outside air,
A type that is connected to the supercharged side of the turbocharger may be used.
Further, it is not limited to the method of directly attaching to the engine, but may be a type provided in a path forming an intake passage communicating with the engine.

(Effects of the Invention) As described above, in the manufacturing method of the present invention, the synthetic resin is injected from the facing position, and at least one pair of support pins are provided on the plane including the injection gate that performs this injection. The core is supported and the support pin is pulled out from the synthetic resin layer before the synthetic resin layer is solidified.Therefore, it is possible to prevent the core from shifting from the predetermined position due to injection pressure when the synthetic resin is injected. As a result, it is possible to obtain a high product accuracy by keeping the thickness of the synthetic resin layer constant and to prevent the holes formed by the support pins from being formed in the intake pipe.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of an engine synthetic resin intake pipe according to the present invention, FIG. 2 is an explanatory view showing a manufacturing process of the first embodiment, and FIG. 3 is a view of the first embodiment. FIG. 4 is a cross-sectional view showing the manufacturing process, FIG. 4 is a vertical cross-sectional view showing the manufacturing process of the first embodiment, and FIG. 5 is a cross-sectional view showing the second embodiment of the synthetic resin intake pipe for an engine according to the present invention. FIG. 6 is an explanatory view showing the manufacturing process of the second embodiment, FIG. 7 is a vertical sectional view showing the manufacturing process of the second embodiment, and FIG. 8 is a sectional view of a main part showing another reinforcing structure of the flange portion. 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 mold 24 …… Injection Gate 25: Support pin

Claims (1)

[Claims] 1. A bending-shaped core corresponding to the shape of a pipe line of an intake pipe is formed, and the core is arranged in an injection-molding mold having an intake pipe shape, and the core is placed in the injection-molding mold. The core is supported by at least one pair of support pins provided on a plane including the injection gates facing each other, and then a synthetic resin material is injected from the injection gate between the mold and the core, and the synthetic resin is injected. A method of manufacturing a synthetic resin intake pipe for an engine, wherein a support pin is pulled out from the synthetic resin layer before the resin layer is solidified.