JP2688423B2 - Synthetic resin composite pipe manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a synthetic resin composite pipe used for, for example, a dual duct in an automobile engine or an intake system, an intake pipe, and the like. is there.

[Conventional technology]

Conventionally, as a synthetic resin composite pipe of this type, one disclosed in, for example, JP-A-58-82059 is known.

This will be described with reference to FIGS. 8 and 9 by taking the intake pipe as an example. An intake pipe 3 is attached to each intake port 2 of the engine 1 via a flange portion 4. The center line of the intake passage 3a of the intake pipe 3 has a complicated shape of two dimensions or more.

Recently, the intake pipe 3 is made of a lightweight and inexpensive heat-resistant synthetic resin material instead of a metal material such as an aluminum material. Blow molding or injection molding is adopted as the molding method.

However, the intake pipe 3 needs to be integrally provided with the flange portion 4 for attaching to the engine 1. However, in blow molding, the surface accuracy of the flange portion 4 cannot be obtained.

Further, since the center line of the intake passage 3a of the intake pipe 3 has a two-dimensional or more complicated shape as described above, there is a problem that the mold cannot be removed by injection molding and molding cannot be performed.

For the above reasons, conventionally, a molding method has been adopted in which the flange portion 4 is formed by injection molding, the duct portion 5 is formed by blow molding, and both are welded (6).

However, the welding of the deformed members such as the flange portion 4 and the duct portion 5 requires a large amount of mounting, and the operation thereof is complicated.
Moreover, the mechanical strength and the hermeticity of the obtained product are not always satisfactory, and there is a risk of lack of reliability.

Therefore, the present applicants have previously made synthetic resin for an engine in which the outer periphery of a blow-molded synthetic resin bent pipe is integrally coated with synthetic resin and a flange portion is integrally provided at the end of the coating layer. Filed for a manufactured intake pipe (Japanese Patent Application No. 61-288485)
issue).

This will be described with reference to FIG. In the figure, 7 is an inner layer made of blow-molded synthetic resin, the outer periphery of which is integrally covered with a synthetic resin material to form an outer layer 8. A flange 9 is integrally formed on one end of the outer layer 8.

The intake pipe 10 thus manufactured is attached to the engine via the flange 9.

The intake pipe 10 is manufactured, for example, by the method shown in FIG.

First, blow molding synthetic resin bent pipe 11 having flange portions 11a at both ends is formed by blow molding, and both ends of this blow molded synthetic resin bent pipe 11 are removed (
Figure 11 (a)). Next, the blow molding synthetic resin bent pipe 11 is filled with a non-deformable material 12 capable of withstanding the pressure at the time of injection molding, and fixed pins 13 are attached to both ends of the non-deformable material 12 to close it.
Figure 11 (b)). Then, using this as a core, the injection mold
Insert within 14. At this time, another mold 15 is arranged on the fixing pin 13 and is clamped (FIG. 11 (c)). After that, blow molding synthetic resin bent pipe 11 and injection mold 14
The synthetic resin material 17 is injected into the space 16 between the wall surface and the outer wall of the blow molded synthetic resin bent pipe 11 to make it integral (No. 11).
Figure (d).

[Problems to be solved by the invention]

However, the blow-molded synthetic resin bent pipe 11 has the drawback that the cross-sectional area becomes distorted and cannot be a perfect circle, and it is difficult to obtain the same cross-sectional shape, and as shown in FIG. There is a problem that the pinch-off portion, that is, the bulge 11b or the recess 11c is formed by the mating portion of the mold used for molding. Therefore, when the fixing pin 13 is inserted into both ends of the blow molded synthetic resin bent pipe 11,
As shown in FIG. 12, a gap 18 will be formed. As a result, the non-deformable material 12 may leak from the gap 18 after the filling work of the non-deformable material 12 in FIG. 11 (b), and at the time of injection molding in FIG. 11 (d). There is a possibility that the synthetic resin material 17 thus produced may enter the blow-molded synthetic resin bent pipe 11 through the gap 18.

The present invention has been made to solve such a conventional problem, and an object thereof is to manufacture a composite pipe having a constant shape regardless of the shape of the end portion of the synthetic resin bent pipe made of blow molding. It is to provide a method for manufacturing a resin composite pipe.

[Means for solving the problem]

In the method for manufacturing a synthetic resin composite pipe according to claim 1, a curved pipe is formed by blow molding, at least one end of the blow molded synthetic resin curved pipe is removed and opened, and the blow molded synthetic resin curved pipe is formed. The pipe is filled with a non-deformable material that can withstand the pressure during injection molding, and the inner wall of the opening is filled with
A plug made up of a sealing material having elasticity and a rod material that compresses and expands the sealing material is bulged and deformed by pressing the sealing part to attach the plug to close the end part, As a child, insert it into the injection molding die, inject the synthetic resin material between the blow molding synthetic resin curved pipe and the wall of the injection molding die, and place the synthetic resin material on the outer periphery of the blow molding synthetic resin curved pipe. It is an integral coating.

[Action]

In the method for producing a synthetic resin composite pipe according to claim 1, at least one end of the blow molded synthetic resin curved pipe is removed and opened, and the pressure at the time of injection molding is injected into the blow molded synthetic resin curved pipe. After filling with a non-deformable material that can withstand, by bulging and deforming the seal portion on the inner wall of the open end, press-fitting and attaching an elastic plug,
Since the end is closed, this is inserted as a core into the injection molding die, and the synthetic resin material is injected between the blow molding synthetic resin curved pipe and the wall surface of the injection molding die to make the blow molding synthesis. When the synthetic resin material is integrally coated on the outer circumference of the curved resin tube, the synthetic resin material which is about to flow from the open portion of the blow molded synthetic resin curved tube is blocked by the injection molding pressure.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, as shown in FIG. 1, a blow molding synthetic resin bent pipe 20 which constitutes a predetermined bent pipe framework is prepared in the same manner as the conventional method as described above.

The blow molding synthetic resin bent pipe 20 is formed by the blow molding method using a predetermined mold as in the conventional method as described above. The end 21 is cut after blow molding. This blow-molded synthetic resin bent pipe 20 has a structure similar to that of the prior art, for example, as shown in FIG.
A pinch-off portion, that is, a raised portion 212 or a recess 213 is formed.

Next, a sealing material 31 of an elastic plug 30 is inserted into one end of the blow molded synthetic resin bent pipe 20, and a rod 32
Is operated to bulge and deform the sealing material 31 and crimp it into the inner wall 211 of the end 21 of the blow molded synthetic resin bent pipe 20, and the other end 21 is non-deformable to withstand the pressure during injection molding. A material (23) is filled, a plug (30) having elasticity is also inserted into the end portion (21), and a stick material (32) is operated to bulge and deform the sealing material (31) to end the end portion (21) of the blow molding synthetic resin bent pipe (20). Crimp inside the inner wall 211 of.

Here, as the non-deformable material 23, for example, fine sand or incompressible liquid is used.

As shown in FIGS. 1 and 3, the elastic plug 30 is made of a synthetic resin material having elasticity and heat resistance, such as silicon, and has an end portion of the blow molded synthetic resin bent pipe 20. Cylindrical seal material with a diameter smaller than 21
31 and a bolt-shaped rod member 32 that penetrates the seal member 31
And a supporting member 33 having rigidity made of metal, which is arranged at the rear end of the seal material 31 and penetrates the rod 32, and a nut 34 arranged at the tip of the seal material 31, By rotating 32, the sealing material 31 can be pulled toward the support portion 33 side and bulged and deformed. It is preferable that the nut 34 has a large number of flat portions. The nut 34 is prevented from idling when the seal material 31 is bulged and deformed by the anti-rotation pin 35 fitted into the seal material 31, and the pulling force of the bar material 32 is reliably ensured. You will be able to communicate.

Next, the inside is filled with a non-deformable material 23, and both ends 21 are plugged with a stopper 30.
Blow-molded synthetic resin bent tube 20 fitted with is attached to an injection molding die as a core in the same manner as the conventional method as described above.
Install in 40, 41.

At this time, the support portion 33 of the stopper 30 has an outer diameter φA and a length l that match the outer diameter 43 of the injection molding dies 40 and 41.
It is used as positioning when the blow molding synthetic resin bent pipe 20 is mounted in the injection molding dies 40, 41 as a core.

Then, as shown in FIG. 5, a synthetic resin material is injected between the outer surface of the blow molded synthetic resin bent pipe 20 and the inner wall surfaces of the injection molding dies 40, 41 to blow molded synthetic resin bent pipe. The outer periphery of 20 is covered with the synthetic resin material 42, and the flange portion 25 is integrally formed.

At the time of injection of the synthetic resin material, the molten synthetic resin material injected from between the end portion 21 of the blow molding synthetic resin bent pipe 20 and the seal material 31 of the plug 30 tries to flow in, but the end portion 21
Since the sealing material 31 is firmly press-fitted into the inner wall 211 of the, the injection pressure can be prevented so as not to flow in.

Finally, this molded product is injected into the injection mold 40, 41 and the outer diameter 43.
Take out the mold. Then, after removing the stopper 30 and taking out the non-deformable material 23, the product is obtained by performing a predetermined post-processing.

As described above, according to the present embodiment, since the sealing material 31 of the plug 30 is firmly attached to the end portion 21 of the blow molded synthetic resin bent pipe 20, the blow molded synthetic resin bent pipe 20 is in the molded state. Regardless, the non-deformable material 23 filled inside does not leak out, and even in injection molding, in a molten state that tries to flow from between the end 21 of the synthetic resin bent pipe 20 made of blow molding and the plug 30. The synthetic resin material is shut off. Further, since the support portion 33 of the stopper 30 functions as a positioning member, the blow molding synthetic resin bent pipe 20 as the core can be easily positioned.

FIG. 6 shows another embodiment of the stopper used in the method for producing a synthetic resin composite pipe according to the present invention, in which a cylindrical reinforcing portion 331 fitted into the sealing member 31 is integrally attached to the supporting portion 33. Has been.

The cylindrical reinforcing portion 331 eliminates a gap that may occur at the boundary between the seal material 31 and the support portion 33.

FIG. 7 shows an application example in the case where the pinch-off portion of the end portion 21 of the blow molded synthetic resin bent pipe 20 has a large unevenness. The raised portion 212 is formed on the side wall portion of the sealing material 31 of the plug 30. The concave groove 311 is provided in the portion corresponding to the above, and the protrusion 312 is provided in the portion corresponding to the depression 213.

According to this modification, the end portion can be processed according to the pinch-off portion, and the filled non-deformable material is the same as in the above embodiment.
The leakage of 23 can be prevented, and the problem that the synthetic resin flows in at the time of injection molding is solved.

In the above embodiment, the rod member 32 is used as the elastic stopper.
By rotating the seal material 31 to bulge and deform,
Although the description has been given of the case where the inner wall 211 of the end portion 21 of the blow molded synthetic resin bent pipe 20 is closed, a cone-shaped rubber plug whose diameter decreases toward the tip may be used. Cork may be used as the elastic stopper.

〔The invention's effect〕

As described above, according to the method for manufacturing the synthetic resin composite pipe of the first aspect, the bent pipe is formed by blow molding, and at least one end portion of the blow molded synthetic resin bent pipe is removed and opened. A blow molding synthetic resin bent pipe is filled with a non-deformable material that can withstand the pressure at the time of injection molding, and the inner wall of the open end has an elastic sealing material and a rod for compressing and expanding this sealing material. A plug made up of a material is bulged and deformed at the seal part and press-fitted to attach it to close the end part, which is inserted as a core into the injection molding die, and made by blow molding synthetic resin bending. The synthetic resin material is injected between the pipe and the wall of the injection molding die, and the synthetic resin material is integrally coated on the outer periphery of the blow molding synthetic resin curved pipe, so the end of the blow molding synthetic resin curved pipe Irrespective of the shape of The non-deformable material filled in the molded synthetic resin curved pipe will not leak out, and the synthetic resin material that will flow from between the open end of the blow molded synthetic resin curved pipe and the plug during injection molding. Is blocked.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of essential parts showing a state in which a core is attached to an injection mold in a method for manufacturing a synthetic resin composite pipe according to an embodiment of the present invention. FIG. 2 is a sectional view taken along the line II-II in FIG. FIG. 3 shows an end portion of a synthetic resin bent pipe made by blow molding with a sealing material of a plug after a core is attached to an injection mold in a method for manufacturing a synthetic resin composite pipe according to an embodiment of the present invention. FIG. 4 is a cross-sectional view of a main part showing a state in which the is sealed. FIG. 4 is a sectional view taken along the line IV-IV in FIG. FIG. 5 is a perspective view showing a synthetic resin composite pipe manufacturing method according to an embodiment of the present invention, in which a core is attached to an injection molding die and the end portion of a blow molding synthetic resin bent pipe is sealed with a sealing material of a plug. FIG. 6 is a cross-sectional view of relevant parts showing a state in which the outer periphery of a blow molded synthetic resin bent pipe is injection-molded with synthetic resin after being formed. FIG. 6 is a sectional view showing a stopper used in a method of manufacturing a synthetic resin composite pipe according to another embodiment of the present invention. FIG. 7 is a cross-sectional view showing a modified example of the sealing material in the stopper used in the method for manufacturing a synthetic resin composite pipe according to another embodiment of the present invention. FIG. 8 is a sectional view showing a conventional example. FIG. 9 is an external view of the intake pipe in FIG. FIG. 10 is a sectional view of the intake pipe according to the prior application. FIG. 11 is a sectional view showing the manufacturing example. FIG. 12 is a sectional view taken along line XII-XII in FIG. [Description of symbols for main parts] 20 …… Blow-molded synthetic resin bent pipe 21 …… End 211 …… Inner wall 23 …… Non-deformable material 30 …… Elastic plug 31 …… Seal material 32 …… Bar Material 33 …… Support section 34 …… Nut 40,41 …… Injection mold 42 …… Synthetic resin material.

Claims (1)

(57) [Claims] 1. A bend pipe is formed by blow molding, and at least one end of the blow mold synthetic resin bend pipe is removed and opened to resist the pressure at the time of injection molding in the blow molding synthetic resin bend pipe. A non-deformable material is filled, and a plug made up of an elastic sealing material and a rod material that compresses and bulges the sealing material is bulged and deformed on the inner wall of the open end. Then, the end is closed by press-fitting and mounting, and it is inserted into the injection molding die as a core, and the synthetic resin material is placed between the blow molding synthetic resin warp pipe and the wall surface of the injection molding die. And a synthetic resin material is integrally coated on the outer circumference of the blow molded synthetic resin bent pipe.