JP2002036271A - Method for manufacturing multilayered plastic pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of rapidly manufacturing a multilayered plastic pipe, which is usable as a duct wherein high-degree durability and heat resistance are required, with high accuracy. SOLUTION: In the method for manufacturing the multilayered plastic pipe using first and second split molds (15, 26), projected parts (16c) are provided to the periphery of the mold groove (16a) of the first split mold and recessed parts (15c) are provided to the periphery of the mold groove (15a) of the second split mold. Both split molds are set in such a state that a predetermined gap is provided between both split molds to supply a molten plastic substance in a cavity. The contact surfaces between the projected parts and the recessed parts permit air to pass but do not permit the molten plastic substance to pass.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer plastic pipe and a method for manufacturing the same, and more particularly, to a plastic pipe such as a duct used as an automobile part such as an intake manifold. .

[0002]

2. Description of the Related Art Since a method capable of forming a plastic pipe whose central axis changes in any two-dimensional or three-dimensional manner by blow molding has been provided, ducts used in automobiles have been increasingly plasticized. Have been. By providing such a plastic tube having an arbitrary two-dimensional or three-dimensional shape, when arranging ducts in a narrow space such as an engine room of an automobile,
By providing a single, complex, bent duct without the need to form multiple sections and assemble them together, the work of attaching the ducts is simplified and the ducts are joined together. There is no danger of fluid leakage occurring due to the absence of the. For this reason, most of the ducts used in the engine room of the automobile, which are conventionally manufactured from rubber products, have been replaced with plastic pipes.

[0003] However, for example, even if a duct is used in an engine room of an automobile, the required conditions are significantly different depending on the state of use. In particular, ducts such as intake manifolds
Since it is directly attached to the engine, it is exposed to a considerably high temperature and vibration is directly applied, so that a high degree of durability is also required. For this reason, conventionally, the intake manifold of the automobile is usually manufactured from a metal such as aluminum. However, when manufacturing a duct from metal, the operation is complicated and difficult, and the shape of the manufactured duct must be limited.

Accordingly, various attempts have been made to replace ducts such as intake manifolds with plastic pipes. However, since ducts are required to have high heat resistance and durability, At present, a practically usable plastic tube and a method for producing the same have not been provided yet.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and solves the above-mentioned drawbacks of the prior art, and is used as a duct requiring high durability and heat resistance. It is an object of the invention to provide a possible multi-layer plastic tube and a method for its production.

[0006]

According to the present invention, there is provided a multilayer plastic pipe having a structure capable of providing a plastic duct having high durability and heat resistance, and a method for producing the same.

According to one aspect of the present invention, a multi-layer plastic tube has a hollow body formed in a predetermined shape from a first plastic material. At a predetermined location on the outer surface of the hollow body, at least one spacer member formed of a second plastic material is provided. Further, on the outer surface of the hollow body, there is provided an outer layer made of a third plastic material integrally molded with the spacer member.

In a preferred embodiment, the hollow body is formed by blow molding, and the spacer member is formed integrally when the hollow body is blow-molded. Further preferably, the outer layer has a flange formed integrally therewith, the flange being formed at the end of the plastic tube.

In accordance with another aspect of the present invention, a multi-layer plastic tube is formed by integrally molding an outer layer from a third plastic material on an outer surface of a hollow core formed into a predetermined shape from a first plastic material. A method of manufacturing is provided. According to a preferred method of the present invention, when the hollow core is positioned in the cavity of the mold, at least one spacer member is interposed between the outer surface of the hollow core and the cavity surface. Next, the molten third plastic material is poured into the cavity, and the outer layer is integrally formed on the outer surface of the hollow core from the third plastic material together with the spacer member into a predetermined shape. Preferably, the hollow core is formed by blow molding together with the spacer member.
Thus, when the hollow core is located at a predetermined position in the cavity, by interposing a spacer member between the hollow core and the cavity surface, when pouring the third plastic substance into the cavity, The hollow core and the cavity surface can be maintained at a predetermined distance, and an outer layer having a desired thickness and shape can be formed over the entire hollow core.

In yet another preferred method of the present invention,
A cavity is formed by combining a plurality of split dies, and a hollow core is positioned in the cavity. In this case, a plurality of split dies are not completely matched, but a predetermined gap is set between the split dies, and air flows through the gap between the split dies. The plastic material is kept out of flow. In such a state, a plastic material in a molten state is supplied into the cavity, then a plurality of molds are completely clamped, the plastic material supplied into the cavity is compressed, and a predetermined amount of plastic material is supplied from the third plastic material. The shaped outer layer is integrally formed with the hollow core.
In order to prevent the hollow core from being deformed, the inside space of the hollow core is filled with particles such as sand particles, or when pressure is applied to the hollow core from outside, It is preferable to supply a high-pressure gas into the internal space of the hollow core.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIGS. 1 to 3 show a multilayer plastic tube 1 constructed according to one embodiment of the present invention, which is suitable for use as, for example, an intake manifold. The multilayer plastic tube 1 has a hollow body 11 molded into a predetermined shape from a first plastic material, and a predetermined portion (in the illustrated example, six locations) on the outer surface of the hollow body 11 is provided with a predetermined shape. And a spacer member 13 having a thickness of 2 mm and made of a second plastics material. Hollow body 11 excluding spacer member 13
An outer layer 12 made of a third plastic material is formed in a predetermined shape on the outer surface of the. The outer layer 12
The hollow body 11 and the spacer member 13 are integrally formed. For example, the outer layer 12 is integrally formed with the hollow body 11 and the spacer member 13 by bonding or welding.
The outer layer 12 forms flange portions 12a at both ends of the multilayer plastic pipe 1, and each flange portion 12a is provided with a mounting hole 12b.

In a preferred embodiment, the hollow body 11 is formed by blow molding and has a shape whose central axis is bent in a desired two-dimensional or three-dimensional manner. The spacer member 13 can be integrally formed at the same time as the hollow body 11 is blow-molded, and is also welded or bonded to a predetermined position on the outer surface of the hollow body 11 after the hollow body 11 is formed by blow molding. Can also be integrated. Also, the spacer member 13 can be formed of the same plastic material as the hollow body 11 or a different plastic material. Thus, the spacer member 13 can provide locally different properties, for example, for the multilayer plastic tube 1 to come into contact with other components or to attach other components.
The outer layer 12 is formed integrally with the hollow body 11, but can be made of a plastic material different from the plastic material of the hollow body 11. It is possible to provide properties. For example, since the hollow body 11 allows a fluid to flow through a passage inside the hollow body 11, the hollow body 11 can be made of a material having desired characteristics required in relation to the fluid to be passed. For example, when the multi-layer plastic tube 1 is used as an intake manifold, the multi-layer plastic tube 1 is made of a plastic material having good gasoline resistance and blow-by gas resistance.
When used as a radiator hose,
It is composed of a plastic material having good LC properties. on the other hand,
The outer layer 12 is intended in particular to provide the multilayer plastic tube 1 with mechanical strength and / or heat resistance properties. Thus, the outer layer 12 can be molded from essentially the same plastic material as the hollow body 11,
It is desirable to use a mixture of reinforcing substances such as a fibrous substance and a filling substance for improving the strength. Examples of such reinforcing materials include glass fiber, carbon fiber, talc, mica, and the like. The hollow body 11, the spacer member 13 and the outer layer 12 can be made of different plastic materials as long as they have compatibility. If the compatibility is lacking, an adhesive layer can be interposed between the plastic materials.
Further, the hollow body 11, the spacer member 13, and the outer layer 12 can be made of exactly the same plastic material. Examples of the plastic material forming the hollow body 11 and the spacer member 13 include nylon 6, nylon 6
6, nylon 6 or 6.6 (containing 20% glass fiber) nylon 11 or 12, nylon 4.6 or 6.1
0 or 6.12, nylon alloy, PPS (polyphenylene sulfide), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), P
There are ES (polyethersulfone), PEEK (polyetheretherketone), polyimide, polyamideimide and the like. On the other hand, as a plastic material that can be used to form the outer layer 12, about 30% of reinforcing fibers such as glass fibers are mixed with each of the above-mentioned plastic substances that can be used to form the hollow body 11. It is possible to use one.

As shown in FIGS. 1 and 3, the outer layer 1
2 is made of a plastic material having good mechanical strength, so that a flange portion 12a can be formed on a part thereof. The mounting hole 12 is provided in the flange portion 12a.
b is drilled, through which a bolt or the like can be inserted and the flange 12a can be directly attached to a main body such as an engine or a radiator. In the embodiment shown in FIGS. 1 and 2, the spacer member 13
Although provided at the upper and lower opposing positions, the spacer member 13 can be provided at at least one position on the outer surface of the hollow body 11, and it is only necessary to dispose the spacer member 13 at such opposing positions. It should not be limited to.
As will be described later, the arrangement position of the spacer member 13 can take various forms according to the use state of the multilayer plastic tube 1 or the manufacturing method thereof.

Next, referring to FIGS. 4a to 4c,
A specific method for manufacturing the multilayer plastic tube 1 according to one embodiment of the present invention will be described.

As shown in FIG. 4a, in this embodiment, a first half mold 15 and a second half mold 1 are obtained by dividing a mold into two.
6, the first half mold 15 and the second half mold 16
And are relatively movable in directions approaching and separating from each other. In the illustrated example, the first half mold 15 is fixedly positioned with its mating surface facing upward, while the second half mold 16 is movable up and down relatively to the first half mold 15. It is provided in. The first mold groove 1 having a predetermined shape and forming a part of the cavity is formed in the mold mating surface of the first half mold 15.
5a is engraved. At both ends of the first mold groove 15a,
The pedestals 15b are engraved, and these pedestals 15b
Functions as a mounting table when the hollow core 11 is positioned in the first mold groove 15a. A predetermined number of supply paths 17 are provided in the first half mold 15, and the supply paths 17 communicate with a supply source 18 that supplies a plastic substance. Accordingly, the third plastic material in a molten state can be supplied from the supply source 18 into the cavity through the supply path 17.

The second half mold 16 has a mold matching surface corresponding to the mold matching surface of the first half mold 15, and a second mold groove 16a having a predetermined shape is formed in the mold matching surface. Is engraved. Slide cores 19 are provided at both ends of the second mold groove 16a. Each slide core 19 is slidably provided in a guide hole formed in the second half mold 16. And is always in the forward position by the spring 20. The distal end of the slide core 19 is formed in a shape to receive the hollow core 11, and the distal end has a configuration capable of contacting the mating surface of the first half mold 15.

A method of manufacturing the multilayer plastic tube of the present invention using the pair of first and second half halves 15 and 16 as described above will be described. First, hollow core 1
1 is formed from a first plastics material into a desired shape, for example by blow molding. Hollow core (hollow body) 1
1 is a part where both ends are finally removed,
Using these parts, as shown in FIG. 4a, the hollow core 11 is placed on the base 15b of the first half mold 15 and
Is set at a predetermined position in the first mold groove 15a of the first half mold 15. The hollow core 11 is provided with a plurality of spacer members 13 on a selected outer surface. Preferably, these spacer members 13 are integrally formed when the hollow core 11 is formed. In this embodiment,
Since the third plastic substance is supplied into the cavity via the supply path 17 provided in the first half mold 15, the spacer member 13 is provided only on the upper surface of the hollow core 11. However, if desired, these spacer members 13 can be additionally provided at other locations. However, it is necessary to provide these spacer members 13 at positions facing the force applied by the third plastic substance into the cavity to the hollow core 11. Therefore, in this embodiment, it is necessary to provide these spacer members 13 on at least the outer surface of the upper half of the hollow core 11.

Next, as shown in FIG. 4B, when the second half mold 16 is lowered, first, the slide core 19 engages with both ends of the hollow core 11, and the tip of the slide core 19 is moved to the first position. It comes into contact with the mold mating surface of the half mold 15. As a result, the hollow core 11 includes the first half mold 15 and the second half mold 16.
At a predetermined position in the cavity defined by Further, when the second half mold 16 is lowered, the slide core 19 is in contact with the mold mating surface of the first half mold 15. It retracts into the guide hole in the split mold 16.
When the gap G between the mating surfaces of the first half mold 15 and the second half mold 16 reaches a predetermined value, the lowering operation of the second half mold 16 is stopped. The size of the gap G in this case is, for example, about 2 mm to 5 mm. In this state, the third plastic substance is supplied from the supply source 18 into the cavity via the supply path 17. In this case,
In this embodiment, since the spacer member 13 is provided on the outer surface of the hollow core 11 opposite to the direction in which the third plastic substance is supplied from the supply path 17, the hollow core 11 is It is brought into contact with the mold groove 16a to prevent the distribution state of the third plastic substance in the cavity from being shifted.

Next, after sufficiently supplying the third plastic substance into the cavity, the supply of the third plastic substance is stopped, and the second half mold 16 is further lowered as shown in FIG. The mold is completely clamped to the half mold 15. Thereby, the third plastic material supplied into the cavity spreads to every corner of the cavity,
A predetermined outer layer is formed by the third plastic material. In this case, the spacer member 13 comes into contact with the cavity surface (in the illustrated example, the second mold groove surface 16a). By this compression step, the third plastic substance supplied into the cavity is completely supplied to a large volume portion such as a flange portion or the like, while the spacer member 13 is provided at a necessary portion because the spacer member 13 is provided. The hollow core 11 is prevented from being deformed, and an outer layer 12 having a predetermined thickness is formed around the hollow core 11.

If the hollow core itself is not strong enough and the hollow core 11 may be deformed by the above-described compression process, the hollow core 11 is filled with particles such as sand particles. Good to put. Alternatively, a compressed gas can be injected into the hollow core 11 to balance the force applied from the outside and prevent the hollow core 11 from being deformed. If there is a possibility that the hollow core 11 comes into contact with the first mold groove 15a due to the compression process as described above, the spacer member 13 can be installed on the outer surface of the lower half of the hollow core 11. It is.

FIG. 5 shows an improved method of producing a flanged multilayer plastic tube by the method of FIGS. 4a to 4c. That is, as shown in FIG. 5, the cylinder device 21 is mounted on the first half mold 15, and the rod 21 a of the cylinder device 21 is provided to be able to advance and retreat through a hole in the first half mold 15. ing. The rod 21a is provided to be able to protrude into the flange forming portion of the first mold groove 15a. Accordingly, when the first and second mold halves 15 and 16 are completely clamped to compress the third plastic substance in the cavity and supply the third plastic substance to all of the cavity, the flange forming portion The third plastic material may not be completely compressed. Accordingly, in the compression step shown in FIG. 4c, the rod 21a is protruded into the space of the cylinder forming portion as shown in FIG. 6 to add the rod 21a to the third plastic member 12 'supplied into the cylinder forming portion. Compressive force can be applied. The rod 21a
As a result, a hole is formed in the shilling portion, and the hole thus formed can be used as a mounting hole 12b in the cylinder portion 12a later as a through hole.

Next, referring to FIGS. 7a and 7b,
According to the present invention, a spacer member 13 is provided on the hollow core 11.
The criterion for determining the position in the case of providing is described.
In the case of FIG. 7A, the hollow core 11 is set at a predetermined position by a pair of slide cores 19, and the plastic substance is supplied from below through the supply holes 17. In this case, the hollow core 11 is not deformed upward by the supplied plastic substance.
Spacer member 1 on the outer surface of the upper half of hollow core 11
3 need to be provided. FIG. 7A shows a case where one spacer member 13 is provided at a position opposite to the supply hole 17, but the spacer member 13 is not necessarily located at the position opposite to the supply hole 17. It is not necessary to provide any number of the hollow cores 11 at places where the hollow cores 11 may come into contact with the cavity surface depending on the shape of the hollow cores 11 and the like.

FIG. 7b shows a state in which the hollow core 11 is set at a predetermined position by a pair of slide cores 19, and the plastic substance is supplied into the cavity from above by the supply path 17. In this case, when the plastic substance is supplied into the cavity by the supply hole 17, the hollow core 11 tends to be pressed downward, so that the spacer member is provided at the lower position facing the supply path 17. 13 is provided to prevent the hollow core 11 from being brought into contact with the cavity surface. Therefore,
Basically, the spacer member 13 may be provided on the outer surface of the hollow core opposite to the supply direction of the plastic substance supplied into the cavity. However, depending on the shape of the hollow core 11 and the method of supplying the plastic substance into the cavity, it is possible to provide any number of spacer members 13 at any position on the outer surface of the hollow core 11.

For example, as shown in FIG. 8a, it is possible to provide a plurality of spacer members 13 in the circumferential direction of the hollow member 11. In particular, when the shape of the hollow member 11 is complicated and the plastic substance is supplied into the cavity through a plurality of supply holes, a plurality of the hollow members 11 are provided in the circumferential direction of the hollow core 11 as shown in FIG. It is desirable to provide the spacer member 13 of FIG. It should be noted that, even though a plurality of spacer members 13 are provided in the circumferential direction, it is not always necessary to provide them on the same circumference, and each spacer member 13 is provided in the longitudinal axis direction of the hollow core 11. Needless to say, it may be provided at a position shifted from the above. FIG. 8B shows a case where the hollow core 11 is partially bent to form the spacer member 13. this is,
When the hollow core 11 is blow-formed, it can be easily formed by forming a groove in the surface of the cavity. FIG. 8c shows a spacer member 13 formed by blow molding an insert part integrally with the hollow core 11. FIG. 8d shows a state in which after the hollow core 11 is formed by blow molding, the spacer member 13 formed separately is integrally formed by welding or bonding.

Next, referring to FIGS. 9a, 9b, 10a and 10b, the construction of a preferred mold used in the method of the present invention will be described in further detail. Ninth
As shown in Fig. a, the first half mold 15 has a first mold groove 15a, while the second half mold 16 has a second mold groove 16a. When the distance between the mating surfaces of the first and second half molds 15 and 16 is set to a predetermined gap G, a cavity is defined by the first mold groove 15a and the second mold groove 16a. A pair of protrusions 16b are formed on both sides of the second mold groove 16a, and these protrusions 16b have a height greater than the gap G. On the other hand, on both sides of the first mold groove 15a, these protruding portions 16b can be received. Therefore, in the state of FIG.
6b is partially inserted into the receiving portion of the first mold groove 15a, so that the cavity is partially closed. That is, the partially closed state is a state in which air flows but no plastic substance passes through a contact portion between the protruding portion 16b and the receiving portion of the first mold groove 15a. Therefore, when the plastic substance is supplied into the cavity in this state, the air in the cavity can flow out through the gap between the protrusion 16b and the receiving portion of the first mold groove a. However, the plastic material supplied into the cavity is maintained in the cavity and substantially prevented from flowing out. FIG. 9b shows a state in which the first and second halves 15 and 16 have been completely clamped after the plastic substance has been supplied into the cavity, and FIG. 9b corresponds to FIG. 4c. .

FIG. 10a shows the configuration of a mold used in another embodiment of the present invention. That is, the tenth
In the embodiment shown in Fig. a, the first half mold 15 has a first mold groove 15a, and a recess 15c is formed on both sides thereof, while the second half mold 15 is formed. 16 has a second mold groove 16a, and a pair of protrusions 16 on both sides thereof.
c is formed. In this case, the protrusion 16
9c differs from the embodiment of FIGS. 9a and 9b in that the tip is cut off and the sharp part is removed.
Accordingly, the strength of the protrusion 16c in this embodiment is improved, and the shape of the protrusion 16c does not change even when the mold is used repeatedly. Therefore, the same performance can be ensured even when a large number of multilayer plastic parts are formed. Furthermore, in this embodiment, as shown in FIG. 10b, even when the first and second half halves 15 and 16 are completely clamped, the projection 16c is completely inserted into the recess 15c. , The outer layer 12 of the molded multilayer plastic tube 1 has ribs 12c formed along its longitudinal direction. Such a rib 12c is provided in the outer layer 1
2 to provide additional strength.

Next, various modifications of the present invention will be described. 11a to 11f show a process for manufacturing a multilayer plastic tube with one end being a flexible fitting. As shown in FIG. 11a, the hollow body or the hollow core 11 is formed by a blow molding method. The hollow core 11 has a hard portion 11H made of a relatively hard plastic material and a soft portion 11S made of a relatively soft plastic material. As a hard plastic material, for example, nylon 6 is used,
On the other hand, nylon 11 is used as a soft plastic material. In the case where a single hollow core 11 is blow-molded from such materials having different hardnesses, the plastic material to be supplied to the nozzle for extracting the parison is switched to form a parison formed from different materials in the longitudinal axis direction. And the composite parison can be molded by blow molding. As shown in FIG. 11a, the blow-molded hollow core 11 has unnecessary portions 1 at both ends.
1H 'and 11S' are provided, and these unnecessary portions 11H 'and 11S' are cut off later. The eleventh
In the embodiment shown in Fig. a, the flexible portion 11S is formed in a state where the diameter is enlarged. On the other hand, in the embodiment shown in FIG. 11b, the hard portion 11H and the flexible portion 11S have the same diameter.

As shown in FIG. 11c, the hollow core 11 is set in the cavity defined by the first and second half halves 15 and 16. Next, as shown in FIG. 11d, the molten plastic substance is supplied into the cavity through the supply path 17 formed in the first half mold 15. The molten plastic material supplied in this case is typically a relatively hard material, for example a mixture of nylon 6 with 30% glass fiber fibers. Next, the mold is clamped and compressed, and the outer layer 12 is integrally formed on the outer surface of the hollow core 11. still,
In this case, it is preferable to inject a compressed gas into the hollow core 11 or to fill the hollow core 11 with particles such as sand particles in advance. Further, as described above, the hollow core 11
It is preferable to install a spacer member at a predetermined location on the outer surface of the device.

Next, after the molten plastic material is cured, the first and second halves 15 and 16 are opened, and the compression-molded molded product is removed from the mold. The state is 11th
This is shown in FIG. Next, unnecessary portions 11H 'and 11S' shown in FIG. 11e are cut off to obtain a desired multilayer plastic tube as shown in FIG. 11f. 11th g
The figure shows an embodiment in which the hard portion 11H and the flexible portion 11S of the core 11 have the same diameter. The multilayer plastic tube obtained in this way has, at one end,
Flange 12 made of hard plastic material
a is formed, and at the other end, a fitting portion 11S formed of a relatively soft plastic material is formed.

Next, a method for manufacturing a multilayer plastic pipe having a bellows will be described with reference to FIGS. 12a to 12c. First, the 12a
A hollow body or hollow core 11 as shown in the figure is formed.
The hollow core 11 in this case is a rigid part 1 made of a relatively hard plastic material, for example nylon 6.6.
1H and a bellows portion 11S made of a relatively soft plastic material such as nylon 12.
Further, unnecessary portions 1 to be removed later are provided at both ends.
1H 'is provided. Next, the hollow core 11 shown in FIG. 12a is set in the cavity defined by the first and second half halves 15 and 16, and the molten plastic material is supplied into the cavity via the supply path 17. I do. Such a molten plastic material can be, for example, a mixture of nylon 6.6 and 30% glass fiber. Note that, in this case, the molten plastic material is applied to the hard portion 1 excluding the bellows portion 11S.
Feed on 1H outer surface. Then, molds 15 and 1
6 is clamped and the molten plastic material is cured to form an outer layer 12 having a predetermined shape. In this embodiment, the outer layer 12 has flange portions 12a formed at both ends. In this compression step, it is preferable to inject compressed gas into the hollow core 11 or to fill the hollow core 11 with particles such as sand particles in advance to prevent deformation due to compression from the outside. Also, it is preferable to provide an appropriate number of spacer members at desired locations on the outer surface of the hard portion 11H of the hollow core 11.

After molding, the dies 15 and 16 are opened, the molded product is taken out from the dies, and the unnecessary portions 11 at both ends are removed.
H 'is removed. The resulting multilayer plastic tube is shown in FIG. 12c.

FIGS. 13a to 13d show a method of manufacturing a multilayer plastic tube having a plurality of independent passages. FIG. 13a shows a hollow body or hollow core 11 formed into a desired shape by blow molding.
As shown in FIG. 13b, the hollow core 11 has a pair of upper and lower grooves 11a formed therein, and the bottoms of these grooves 11a come into contact with each other to form a pair of independent conduits 11b.
Are formed. Such a hollow core 11 is set in a cavity defined between the first and second half molds as in the above-described embodiment, and then the molten plastic material is supplied into the cavity and the mold is clamped. And compression molding. After the molding is completed, the mold is opened, the molded product is removed from the mold, and unnecessary portions at both ends are cut off. This forms a multi-layer plastic tube having a plurality of independent conduits as shown in FIG. 13c. The multi-layer plastic tube has flange portions 12a formed at both ends, and has a cross-sectional structure as shown in FIG. 13d.

FIGS. 14a to 14c show another embodiment for producing a multilayer plastic tube having a plurality of independent conduits. As shown in FIG. 14a, a plurality of (two in this embodiment) hollow bodies or hollow cores 11-1 and 11-2 having respective desired shapes are formed by blow molding. Then, these two hollow cores 11-1 and 11-2 are set in a cavity formed between the first and second half halves 15 and 16 as shown in FIG. 14b. Next, the molten plastic material is supplied into the cavity, the mold is clamped, and the molten plastic material is compression-molded into a predetermined shape. After the molding, the mold is opened, the molded product is taken out, unnecessary portions at both ends are cut off, and a multilayer plastic tube having a plurality of conduits is formed. A cross section of the multilayer plastic tube thus formed is shown in FIG. 14c.

Next, with reference to FIGS. 15a to 15f, a method of manufacturing a multilayer plastic pipe having a flange covered with a metal member will be described. First, as shown in FIG. 15a, a hollow body or hollow core 11 is formed by blow molding using a cup-shaped metal member 31 as an insert part. FIG.
A state in which the cup-shaped metal member 31 is integrally formed with the hollow core 11 by blow molding is shown. Next, as shown in FIG. 15c, the hollow core 11 is set in the cavity of the mold. As described above, the first and second half molds 15 and 16 can be used as the molds in this case. An enlarged portion 16c of a mold groove capable of storing the metal member 31 is formed. Accordingly, in this case, the metal member 16c functions as a stopper for the first and second half halves 15 and 16, and the hollow core 11 is inserted by inserting the metal member 31 into the mold groove enlarged portion 16c. It is set at a predetermined position in the cavity.

Next, as shown in FIG. 15d, the molten plastic material is supplied into the cavity through a supply path 17 (not shown) formed in the first or second half mold 15 or 16. Next, the mold is clamped, compression molded, and the outer layer 12 having a predetermined shape is integrally formed from the molten plastic material. In this case, the compressed gas is injected into the hollow core 11 or the hollow core 11 is
The inside of the hollow core 11 is preferably filled with particles such as sand particles to prevent the hollow core 11 from being deformed by compression molding. Furthermore, it is also possible to provide an appropriate number of spacer members at desired positions on the outer surface of the hollow core 11. After molding,
Open the mold and remove the molded product from the mold. This state is shown in FIG. 15e.

Next, the hollow core 11 shown in FIG.
The unnecessary portion 11 'of the metal member 3 having a cup shape as shown in FIG.
1 and a mounting hole 12b is formed. In the multilayer plastic pipe thus formed, the flange portion 12a is reinforced by the metal member 31. Therefore, when the flange portion 12a is attached to a main body such as an engine, the flange portion 12a is tightened by a bolt. Can be prevented from being deformed, and secure attachment can be ensured.

FIGS. 16a and 16b show another embodiment for manufacturing a multi-layered plastic pipe whose flange is reinforced by a metal member. As shown in FIGS. 15a and 15b, a hollow core 11 integrally formed with a metal member 31 formed by blow molding is formed into a first half mold 15.
Set to a predetermined position. In this case, the first half mold 1
5, a mold groove 15a having a predetermined shape is engraved, and a mold groove enlarged portion 15c for receiving the mold member 32 is formed.
Are formed, and a pedestal portion 15b on which the end of the hollow core 11 is placed is formed. On the other hand, the second half mold 16 has a second mold groove 16 a having a predetermined shape, and has a slide core 19 that is movable forward and backward and is always biased to a forward position by a spring 20. The slide core 19 has a notch 19a for receiving the mold member 32.

When the second half 16 is lowered, the metal member 32 is housed in the cut portion 19a of the slide core 19,
Further, the second half mold 16 is lowered to set the distance between the mold matching surfaces to a predetermined distance G. This state is shown in FIG. 16b. In this state, the supply path 17 (not shown) provided in the first and / or second half molds 15 and 16 is provided.
Feeding the molten plastic substance into the cavity via the. After supplying the molten plastic material, the first and second halves 15 and 16 are completely clamped and compression molded,
The molten plastic material is formed into a predetermined shape. After the molten plastic material has hardened, the mold is opened and the molding is removed. Next, similarly to the above-described embodiment, unnecessary portions of the hollow core 11 are cut off to form a multilayer plastic tube.

In this embodiment, as in the above-described embodiments, when performing compression molding, a compressed gas is injected into the hollow core 11 or sand particles or the like are previously introduced into the hollow core 11. Such particles are preferably filled in advance to prevent the hollow core 11 from being deformed by external pressure. Also, it is possible to provide an appropriate number of spacer members at desired positions on the outer surface of the hollow core 11.

[0041]

As described in detail above, according to the present invention, it is possible to provide a multilayer plastic pipe having heat resistance and durability. In particular, in the present invention, by using the spacer member, it is possible to provide a multilayer plastic pipe having uniform characteristics over the entirety of the plastic pipe. Therefore, the multilayer plastic tube of the present invention has characteristics very close to the design conditions,
Reliability is extremely high. Further, the present invention provides a method capable of producing a multilayer plastic tube having high reproducibility and repeatedly having the same performance. Accordingly, there is provided a method suitable for manufacturing automotive parts, such as intake manifolds and radiator hoses, to which high temperatures and high vibrations are applied from plastic materials. In particular, when the present invention is applied as a duct for automobiles, the weight can be reduced. For example, as compared with an intake manifold made of aluminum die casting, the weight can be reduced by 50% or more when the present invention is applied.

Although the specific embodiments of the present invention have been described in detail, the present invention should not be limited to only these specific examples, but may be variously modified without departing from the technical scope of the present invention. Of course is possible.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a multilayer plastic tube configured according to one embodiment of the present invention.

FIG. 2 is a schematic sectional view taken along line AA in FIG. 1;

FIG. 3 is an end view of the multilayer plastic tube shown in FIG. 1;

FIGS. 4A to 4C are schematic diagrams showing steps of a method for manufacturing a multilayer plastic tube according to one embodiment of the present invention.

FIG. 5 is a schematic diagram showing a modification of FIGS. 4a to 4c.

FIG. 6 is a schematic diagram showing a modification of FIGS. 4a to 4c.

FIGS. 7A and 7B are schematic views showing the principle of positioning a spacer member in the present invention.

FIGS. 8A to 8D are schematic views showing some embodiments of a spacer member.

FIGS. 9A and 9B are schematic cross-sectional views showing the structure of a mold that can be used in the method of the present invention.

FIGS. 10A and 10B are schematic cross-sectional views showing the structure of a mold usable in the method of the present invention.

11A to 11G are schematic views showing steps in a method for manufacturing a multilayer plastic tube having a hard portion and a soft portion.

FIGS. 12A to 12C are schematic views showing steps in a method for manufacturing a multilayer plastic tube having a bellows portion.

FIGS. 13A to 13D are schematic views showing steps in a method for manufacturing a multilayer plastic pipe having a pair of independent pipes.

14A to 14C are schematic views showing steps in another method for manufacturing a multilayer plastic pipe having a pair of independent pipes.

15A to 15F are schematic views showing steps in a method for manufacturing a multilayer plastic pipe having a flange portion reinforced by a metal member.

FIGS. 16A and 16B are schematic views showing a modified example of a method of manufacturing a multilayer plastic pipe having a flange portion reinforced with a metal member.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) B29L 9:00 B29L 9:00 23:00 23:00 F term (Reference) 3H111 AA01 BA15 CA53 CB03 DA11 4F202 AA29 AD12 AD35 AG03 AG12 AH16 CA09 CB01 CB12 CB20 CK42 CK83 CQ07 4F204 AA29 AD12 AD35 AG03 AG12 AH16 FA01 FB01 FB12 FB20 FQ15 FW23

Claims (3)

[Claims] 1. A method for manufacturing a multi-layer plastic tube by integrally molding an outer layer from a second plastic material on an outer surface of a hollow core molded into a predetermined shape from a first plastic material, comprising the steps of: With the hollow core positioned, a plurality of split dies are set in a state where a predetermined gap is maintained between their mold mating surfaces, and the second plastic material in a molten state while the predetermined gap is maintained Supplying the inside of the cavity, the plurality of split molds are clamped, and an outer layer having a predetermined shape is integrally formed with the hollow core from the second plastic material, comprising the above steps, The plurality of split molds have a first half mold and a second half mold, and the first half mold and the second half mold define the cavity on respective mold mating surfaces. First mold groove and second mold groove are engraved The first half mold has a protrusion formed at least partially along the first mold groove, while the second mold groove of the second half mold receives the protrusion. A recess that can be accommodated is formed, and when set in a state where a predetermined gap is maintained between the mold mating surfaces of the split molds, the protrusion is received and received within the recess by a predetermined length. Wherein the contact surface between the protrusion and the recess is air-permeable but substantially impermeable to plastic material. 2. The method of claim 1, wherein the tip of the protrusion is a non-sharp end. 3. The method according to claim 1, wherein when the first and second halves are completely clamped, a predetermined distance is provided between a tip of the protrusion and a bottom of the recess. A method characterized by the presence of a gap.