JP2002355849A - Method for manufacturing multilayer plastic molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer plastic molding which improves durability against a high temperature and/or a high pressure and to provide a method for manufacturing the same. SOLUTION: The multilayer plastic molding 1 comprises a hollow unit 11, an outside layer 12, and a spacer member 13. The hollow unit 11 can at least partly constitute multilayers. A crosslinking member extended in an internal space can be provided at a suitable position of the hollow unit. An insert component can be provided by embedding in at least outside layer. Further, a method for manufacturing the multilayer plastic molding according to a low pressure injection molding is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer plastic molded article and a method for producing the same, and more particularly, to a plastic molded article such as a duct used as an automobile part such as an intake manifold and the like and a method for producing the same. It is about the method.

[0002]

2. Description of the Related Art Since the provision of a method capable of molding a plastic pipe whose central axis changes in two or three dimensions by blow molding has been provided, ducts used in automobiles have been made plastic. ing. By providing such a plastic tube having an arbitrary two-dimensional or three-dimensional shape, a plurality of portions can be formed 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 combine them, the work of attaching the ducts is simplified,
Further, since there is no seam in the duct, there is no danger of fluid leakage occurring. For this reason, ducts conventionally used in the engine room of automobiles and manufactured from rubber products are gradually being converted into 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 an automobile is usually manufactured from a metal such as aluminum. However, when manufacturing ducts from metal,
The operation is complicated and difficult, and the shape of the duct to be manufactured must be limited.

Therefore, various attempts have been made to use plastics for ducts such as intake manifolds, etc., but ducts that require high heat resistance and durability are still practical. There is no plastic molded body that can be used for the present invention and a method for producing the same.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a multilayer film which can be used as a duct having desired durability and heat resistance. An object of the present invention is to provide a plastic molded body and a method for producing the same.

[0006]

According to the present invention, there is provided a multilayer plastic molded article such as a plastic duct having desired durability and heat resistance, and a method for producing the same.

The inventors of the present invention have previously described in Japanese Patent Application No. Hei.
No. 317985 describes a novel multilayer plastic molded article and a method for producing the same. SUMMARY OF THE INVENTION The present invention provides a multilayer plastic molded article which is a further improvement of the technique described in Japanese Patent Application No. 2-317895, and a method for producing the same.

[0008] According to one aspect of the invention, a multi-layer plastic molding has a hollow body formed from a plastic material into a predetermined shape. At least one spacer member made of a plastic material is provided at a predetermined position on the outer surface of the hollow body. Further, on the outer surface of the hollow body there is provided an outer layer of a plastic material integrally molded with the spacer member. The hollow body is characterized in that it has at least partially a structure of two layers or more.

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. The spacer member can be formed as a part of the hollow body. Further, preferably, the outer layer has a flange portion formed integrally therewith, and the flange portion is formed at an end portion of a plastic molded body or the like.

[0010] Preferably, the hollow body has a two-layer structure of an inner layer having an inner peripheral surface and an outer layer having an outer peripheral surface. When the hollow body has a two-layer structure as described above, the inner layer and the outer layer can be made of different materials according to the respective required conditions. For example, it is possible to select a desired substance for the inner layer so as to impart smoothness to the inner peripheral surface in order to reduce frictional resistance to a fluid flowing inside the hollow body. On the other hand, since the fluid flowing inside the hollow body has chemical properties, it is possible to select a good material such as chemical resistance and oil resistance in order to impart durability to such fluid. On the other hand, for the outer layer having an outer peripheral surface, it is possible to use a high-strength substance mixed with a reinforcing substance such as a fibrous substance or a filling substance so as to impart mechanical strength to the hollow body.

According to another aspect of the present invention, there is also provided a multilayer plastic molded article having a hollow body, a spacer member, and an outer layer, wherein a bridging member is provided to extend into an inner space of the hollow body. Provided is a multi-layer plastic molded article. Such a bridging member is preferably provided by fixing both ends thereof to the wall of the hollow body by welding or the like. Such a bridging member is preferably provided at a location where the internal space of the hollow body is relatively large, and has an action of preventing the wall of the hollow body from vibrating. In this case, the hollow body may be a single layer or a multilayer.

Further, according to another aspect of the present invention, there is also provided a multilayer plastic molded body having a hollow body, a spacer member, and an outer layer, wherein at least one insert part embedded in at least the outer layer. Is provided. Such an insert part is preferably a metal part and may be a desired mechanical element such as a bush, a collar, a bolt, a nut and the like. Preferably, such an insert part is provided with a groove or notch, and when the insert part is embedded in the outer layer, a part of the outer layer penetrates into such a notch or groove to insert the insert. It is desirable that the component be held firmly in the outer layer. Instead of or in addition to such grooves or notches, it is possible to knurl at least a part of the outer peripheral surface of the insert part. Preferably, the insert part may be provided so as to partially extend into the hollow body via an interface between the outer layer and the hollow body. Also in this case, the hollow body may be a single layer or a multilayer.

In accordance with yet another aspect of the present invention, a multi-layer plastic is formed by integrally forming an outer layer of a second plastic material on an outer surface of a hollow core formed into a predetermined shape from a first plastic material. A method for producing a molded article is provided. According to the method of the present invention, a plurality of split molds constituting a mold are closed to define a cavity. At that time,
The hollow core is positioned in the cavity while maintaining a gap with the surface of the cavity. Next, a second plastic material is fed into the gap in a molten state and within a predetermined pressure range of 500 kg / cm ² or less. The second plastic material supplied into the gap is cured and integrated with the hollow core to form a multilayer plastic molded product. This molding method is similar to the so-called injection molding technique, but the so-called injection molding technique is 500
In contrast to injecting the resin at a relatively high pressure of at least kg / cm ² , the method of the present invention supplies the resin into the cavity at a relatively low pressure range, ie, a pressure of 500 kg / cm ² or less. It is characterized by doing.

In the method of the present invention, the resin or plastic is preferably injected into the cavity within a pressure range of 50 to 400 kg / cm ² . According to the inventor's earnest research results, the lower the injection pressure, the more the plastic can be injected into every corner of the cavity even in the case of a molded article having a complicated shape.
If the pressure is not more than cm ² , the injection pressure into the cavity from the gate provided in the supply path is too low, so that the plastic in the molten state may solidify on the way, and therefore, the plastic may not sufficiently enter the cavity. May not be supplied. Further, the supply path may be closed halfway, and the supply may be stopped completely, or a void may be generated in the cavity. Therefore, the lower limit of the injection pressure in the method of the present invention is desirably 50 kg / cm ² .

On the other hand, if the injection pressure is increased, it is possible to supply plastic into the cavity in a short time. However, since the multilayer plastic molded body produced by this method has a hollow core, However, if the injection pressure is too high, a large pressure is locally applied to the hollow core from the supply path through which the plastic in a molten state is supplied into the cavity, and the hollow core is locally deformed or deformed. A gap may occur. For this reason, a multilayer plastic molded article having a desired shape is not formed. For this reason, the supply pressure of the plastic in the molten state into the cavity is desirably 400 kg / cm ² or less.

The above-described injection pressure range is the same when the filling material is filled in the hollow core or when the high-pressure gas is at least temporarily injected into the hollow space of the hollow core. Further, the method of the present invention is equally applicable whether the hollow core has a single layer or a multilayer. More preferably, when applying the method of the present invention, it is desirable that the supply of the molten plastic to the cavity is supplied from a plurality of supply points. With such a multi-point supply configuration, not only can the supply time be reduced, but also plastic can be sufficiently supplied to every corner of the gap between the hollow core and the cavity surface. Therefore, no problem occurs even when the shape of the plastic molded article to be molded is complicated.

[0017]

1A to 1C show a duct-shaped multilayer plastic molded article 1 constructed according to an embodiment of the present invention, which is, for example, a duct for an intake manifold or the like. Suitable for use.
The multilayer plastic molded body 1 has a hollow body 11 formed into a predetermined shape from a first plastic material, and is provided at predetermined positions (eight positions in the illustrated example) on the outer surface of the hollow body 11. A spacer member 13 having a predetermined thickness and made of a second plastic material is provided. An outer layer 12 made of a third plastic material is formed in a predetermined shape on the outer surface of the hollow body 11 excluding the spacer member 13. The outer layer 12 is formed integrally with the hollow body 11 and the spacer member 13. For example, the outer layer 12 is integrally formed with the hollow body 11 and the spacer member 13 by bonding or welding. Outer layer 12
Form flange portions 12a at both ends of the multilayer plastic molded body 1, and each flange portion 12a
A 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 molded at the same time as the hollow body 11 is blow-molded. After the hollow body 11 is formed by blow molding, the spacer member 13 is welded or bonded to a predetermined position on the outer surface of the hollow body 11. Can be integrated. The spacer member 13 can be formed of the same plastic material as the hollow body 11 or a different plastic material, or can be formed as a part of the hollow body 11. Thus, the spacer members 13 can give the multilayer plastic molding 1 different properties, for example, for local contact with other components or for mounting other components.

Although the outer layer 12 is formed integrally with the hollow body 11, the outer layer 12 can be made of a plastic material different from the plastic material of the hollow body 11. It is possible to provide the desired characteristics according to the requirements. For example, the hollow body 11
Since the fluid flows through the internal passage, the fluid can be made of a substance that provides desired characteristics required in connection with the fluid to flow. For example, when the multilayer plastic molded article 1 is used as an intake manifold, it is made of a plastic material having good gasoline resistance and blow-by gas resistance. On the other hand, when the multilayer plastic molded article 1 is used as a radiator hose, In particular, it is made of a plastic material having a good LLC resistance. On the other hand, the outer layer 12 aims at giving the multilayer plastic molded body 1 mechanical strength and / or heat resistance. Therefore, the outer layer 12 can be formed of the same plastic material as the hollow body 11, but a mixture of reinforcing materials such as a fibrous material and a filling material for improving strength is used. It is desirable. Examples of such reinforcing materials include glass fiber, carbon fiber, talc, mica, and the like. It should be noted that different plastic materials can be used for the hollow body 11, the spacer member 13 and the outer layer 12 as long as they have compatibility. If compatibility is required, an adhesive layer can be interposed between the plastic materials. Furthermore, it is also possible for the hollow body 11, the spacer member 13 and the outer layer 12 to 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 1
2, nylon 4.6 or 6.10 or 6.12, nylon alloy, PPS (polyphenylene sulfide),
PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PES (polyether sulfone), PEEK (polyether ether ketone),
Examples include polyimide and polyamide imide. On the other hand, as a plastic material that can be used to form the outer layer 12, about 30 to 50% of a reinforcing fiber such as a glass fiber is mixed with each of the above plastic substances that can be used to form the hollow body 11. Can be used.

In the embodiment shown in FIGS. 1A to 1C, since the outer layer 12 is formed of a plastic material having good mechanical strength, a part of the flange portion 1 is formed.
2a can be formed. The flange portion 12a is provided with a mounting hole 12b, through which a bolt or the like can be inserted to directly mount the flange 12a to a body such as an engine or a radiator. In the embodiment shown in FIG. 1 (C), the spacer members 13 are provided at vertically opposed positions.
The spacer member 13 can be provided at at least one position on the outer surface of the hollow body 11, and is not limited to being disposed only at such a specific opposed position. For example, the arrangement position of the spacer member 13 can take various forms according to the use state of the multilayer plastic molded body 1 or the manufacturing method thereof. For example,
The spacer member 13 can be provided on the outer peripheral surface of the hollow body 11 in a circumferential direction, a spiral direction, or any other arrangement state, and when provided in the circumferential direction, continuously or intermittently. Can also be provided. It is also possible to substitute one or more of the spacer members 13 with one made of a metal or other substance.

The embodiment shown in FIGS. 1A to 1C is characterized in that the hollow body 11 has a two-layer structure. That is, as shown in FIGS. 1A and 1B, the hollow body 11 in this embodiment has an inner layer 11a having an inner peripheral surface.
And an outer layer 11b integrally formed on the outer peripheral surface of the inner layer 11a and having an outer peripheral surface.
Incidentally, such a hollow body 11 is preferably integrally formed by blow molding. In this embodiment, the hollow body 1
1 has a two-layer structure of an inner layer 11a and an outer layer 11b, so that the inner layer 11a is formed by using an optimal substance for a fluid flowing through the conduit of the hollow body 11, while the hollow body 11b
It is possible to form the outer layer 11b from a suitable material in order to optimize its own mechanical strength. That is,
This hollow body 11 is formed as a hollow core by integrally forming a spacer member 13 and an outer layer 12 on the outer surface thereof.
This constitutes the multilayer plastic molded body 1 as shown in FIG. In this case, when the outer layer 12 is formed on the outer peripheral surface of the hollow body 11, a force is applied on the outer peripheral surface of the hollow body 11. Therefore, there is a possibility that the hollow body 11 is deformed and the multilayer plastic molded body 1 having a desired shape cannot be obtained. In order to solve such a problem, in the present embodiment, the hollow body 11 itself has a two-layer structure, and a material for increasing the mechanical strength is used in at least the outer layer 11b. It is possible to improve the mechanical strength of itself.

For example, in the case of a multilayer plastic molded article 1 having a plastic tube shape shown in FIG.
The inner layer 11a can be formed by using a material whose inner peripheral surface of the hollow body 11 has an optimal smoothness with respect to the fluid flowing through the conduit and which is suitable for reducing frictional resistance. is there. Further, depending on the nature of the fluid flowing in the conduit, for example, a substance having good chemical resistance and oil resistance may be used to form the inner layer 11.
It is possible to form a. On the other hand, the outer layer 11b mainly improves the mechanical strength of the entire hollow body 11,
For example, it can be configured using a material filled with a filler such as a reinforcing fiber. As described above, the rigidity of the hollow body 11 in the present embodiment is improved. Therefore, when the outer layer 12 is integrally formed on the outer peripheral surface of the hollow body 11, the hollow body 11 is compressed and deformed. Because there is no
It is possible to obtain the multilayer plastic molded body 1 having an arbitrary complicated shape more quickly. In the above-described embodiment, the hollow body 11 has been described as having a two-layer structure as a whole, but it is needless to say that the hollow body 11 can be at least partially formed as a two-layer structure. .
Further, the hollow body 11 may have a structure of three or more layers for improving the mechanical strength or for other reasons, and may have a locally different structure such as partially two layers or three layers. It is also possible to have a multi-layer configuration having the configuration.

Next, FIGS. 2 to 5 show a multilayer plastic molded article 1 constructed according to another embodiment of the present invention. The multilayer plastic molded body 1 in this case is an example of a case where the multilayer plastic molded body 1 is configured as an intake manifold assembly. That is, FIG. 2 shows a hollow body 11 of the multilayer plastic molded body 1 configured as the intake manifold assembly, and this hollow body 11 is preferably integrally formed by blow molding. The hollow body 11 shown in FIG.
The suction pipe section 11-1, the pressure chamber section 11-2, and the four branch pipe sections 11-3 are integrally formed. That is, the fluid is supplied to the pressure chamber 11-2 via the suction pipe section 11-1.
And the fluid is supplied from the pressure chamber 11-2 to each of the four branch pipes 11-3.

As shown in FIG. 2, such a hollow body 11
Is different from the pipe-shaped multilayer plastic molded article shown in FIG. 1, for example, in the portions indicated by W1 and W2, there are areas having a relatively large internal space and a wide surface. That is, in the section W1, the inlet conduit 11-1 has an elliptical cross section, and therefore, the upper and lower portions have relatively wide opposed wall portions. Furthermore,
In the section W2, the pressure chamber 11-2 has a substantially rectangular parallelepiped shape, and therefore, there is a relatively wide opposing wall portion between the upper wall and the lower wall. When the opposed wall portions having a relatively large area are present, the hollow body 1
Because 1 is made of plastic material,
Vibration may occur in the use condition, which may cause noise, and in extreme cases, the hollow body 11
Cracks may be formed and damaged. Therefore, in the hollow body 11 shown in FIG.
In 2, the bridge member 15 is provided to extend between the upper wall and the lower wall. The bridging member 15 has a rod shape in the illustrated example, and has one end fixed to the upper wall and the other end fixed to the lower wall. These bridging members 15 are preferably made of a plastic material, and their upper and lower ends are desirably fixed to the respective walls of the hollow body 11 by welding or bonding. For example, after the hollow body 11 is integrally formed by blow molding, holes are drilled at predetermined locations in the sections W1 and W2 at a wall position facing each other with a drill or the like, and the bridging member 15 made of a plastic material is inserted through the holes. After cutting to predetermined dimensions, the ends can be fixed to the respective walls.

FIG. 4 is a sectional view taken along the line BB in FIG. As shown in FIG. 4, holes are formed in the hollow body 11 so as to face the upper wall and the lower wall of the pressure chamber 11-2, respectively. A state is shown in which both ends of the member 15 are cut and then both ends are fixed to corresponding walls of the pressure chamber 11-2 by heat welding or the like. As described above, when the internal space of the hollow body 11 is relatively large and the opposing wall surface is a relatively large flat wall, the wall of the hollow body 11 is provided by providing such a bridge member 15. Vigorous vibration is prevented. In addition, the bridge member 15 can be provided in an arbitrary number and an arbitrary position. The bridge member 15 does not need to be entirely made of a plastic material, and may be partially or entirely made of another material.

FIG. 3 shows a state in which an outer layer 12 is integrally formed on the outer peripheral surface of the hollow body 11 of FIG. Also in this embodiment, the outer layer 12 contains a reinforcing material such as a reinforcing fiber to provide mechanical strength, so that a flange portion 12a is formed at each end of the inlet pipe and the branch pipe. I have. Further, a mounting hole 12b is formed at an appropriate position of the flange portion 12a. Also, outer layer 1
When integrally forming 2, the insert part 17 is provided so as to be integrally embedded in the side surface of the pressure chamber.

FIG. 5 is a schematic sectional view taken along line CC of FIG.
2 shows a state in which the outer layer 12 is integrally formed on the outer peripheral surface of -2. Since the hollow body 11 is surrounded by the outer layer 12, the cross-linking member 15 and the hollow body 11-
Even if the connection between the two is not completely sealed, the inner space of the hollow body 11 is completely sealed by providing the outer layer 12. Further, as shown in FIG. 5, a spacer member 13 is provided at an appropriate position on the outer peripheral surface of the hollow body 11 together with the outer layer 12. By providing such a spacer member 13, it is possible not only to give desired characteristics locally to an appropriate portion of the completed multilayer plastic molded body 1, but also to form the outer layer 12 when forming the outer layer 12. The height can be regulated to a predetermined thickness.

The hollow body 11 shown in FIG. 2 may have a single-layer structure, or a part or all of the hollow body 11 may have a two- or more-layer structure. Of course there is.

FIGS. 6 to 17 show another aspect of the present invention, which is characterized in that an insert part 17 is provided so as to be embedded in the outer layer 12. First, FIG.
In the embodiments shown in FIGS. 7 and 7, when the hollow body 11 is formed by blow molding, the hollow body 11 is formed simultaneously with the insert part 17 partially embedded. The illustrated insert component 17 has grooves formed on the outer peripheral surface thereof as a first locking portion 17a and a second locking portion 17b. That is,
The first locking portion 17a is positioned so as to be embedded inside the wall of the hollow body 11 when the hollow body 11 is formed by blow molding. Therefore, when the insert component 17 and the hollow body 11 are integrally formed by blow molding. In addition, a part of the plastic material of the hollow body 11 enters into the groove 17a of the first locking portion to firmly hold the insert part 17. Insert part 1
7, a screw portion 17c is engraved in advance inside. Next, as shown in FIG. 7, an outer layer 12 is integrally formed on the outer peripheral surface of the hollow body 11. Therefore, a part of the outer layer 12 is formed with the groove 17 b as the second locking portion of the insert part 17.
The insert part 17 is firmly held in the form embedded in the outer layer 12. Incidentally, as shown in FIG.
In this embodiment, the outer peripheral surface of the outer layer 12 and the end surface of the insert component 17 are substantially coplanar. Therefore, in this case, the insert part 17 can exhibit the function of the spacer member 13 and can partially replace the spacer member 13. The insert part 17 can be made of metal or other desired material, and is, for example, a mechanical element having a desired function such as a bush, a collar, a bolt, a nut, and the like. Is possible. In this embodiment, the insert part 17 is formed integrally with the hollow body 11 by blow molding in advance. However, instead of the insert part 17 being integrally formed with the hollow body 11,
After the hollow body 11 is formed by blow molding, the hollow body 11 may be integrated with the hollow body 11 by an adhesive or another method.
It is also possible to adopt a configuration in which the hollow 7 is partially embedded in the hollow body 11 or a configuration in which the hollow 7 is not embedded.
As described above, in this embodiment, since the insert component 17 is provided so as to be embedded at least in the outer layer 12, the insert component 17 constitutes a part of the outer layer 12,
It is firmly held in the outer layer 12.

Next, another embodiment shown in FIGS. 8 to 10 will be described. This embodiment is substantially the same as the embodiment shown in FIGS. 6 and 7, except that the insert part 17 is not provided with a screw hole 17c in advance. That is, as shown in FIG. 8, the insert part 17 is formed integrally with the hollow body 11 in a state where the insert part 17 is partially embedded, preferably by blow molding. The insert part 17 includes a first locking part 17 a and a second locking part 1.
7b, and the portion of the first locking portion 17a is the hollow body 1
1 is buried inside.

Next, as shown in FIG. 9, an outer layer 12 is integrally formed on the outer peripheral surface of the hollow body 11. Also in this case, the insert part 1 is provided on the outer peripheral surface of the outer layer 12.
7 is substantially the same as the end face. Therefore, the second locking portion 17b of the insert component 17 is embedded in the outer layer 12, and therefore, the insert component 17 is
It is firmly held inside. Next, as shown in FIG. 10, in the state of FIG. 9, machining is performed to form a screw hole 17 c in the embedded insert part 17.
In this embodiment, a screw hole 17c is provided to penetrate the insert part 17 and also penetrate the hollow body 11. In this case, since the internal space and the external space of the multilayer plastic molded body communicate with each other through the screw hole 17c, for example, a pressure gauge or the like is provided through the screw hole 17c to measure the pressure in the internal space. Is possible.

The other embodiment shown in FIGS. 11 to 13 has basically the same structure as the embodiment shown in FIGS. 8 to 10, except that knurling is performed on the outer peripheral surface of the insert part 17. This is the case. By performing knurling on the outer peripheral surface of the insert component 17 in this manner,
When the insert component 17 is embedded in the outer layer 12 by forming the outer layer 12 on the outer peripheral surface of the hollow body 11 as shown in FIG. 12, the insert component 17 rotates around its central axis. The effect of preventing this is improved. That is, as shown in FIG. 13, when the screw hole 17c is provided through the insert component 17, a rotational force is applied to the insert component 17, and in this case, the insert component 1
7 rotates relative to the outer layer 12 and the outer layer 12 and the hollow body 11 are deformed or, in the worst case, the insert part 1
7 may come off. However, by performing such a knurling process, the insert component 17 is prevented from rotating relative to the outer layer 12, so that a rotational force is applied to the insert component 17 such as when the screw hole 17c is provided. , The integrity of the insert component 17 and the outer layer 12 is not degraded. As a modified example of this embodiment, in addition to or instead of performing knurling on the outer peripheral surface of the insert component 17, the outer peripheral surface of the insert component 17 has a shape different from the circumference, for example, Radial dimensions such as an elliptical shape, a hexagonal shape, or a star shape may be different in the circumferential direction. Alternatively, a groove extending in a direction parallel to the longitudinal axis direction or in a direction inclined thereto may be provided on the outer peripheral surface of the insert component 17. This modified embodiment effectively prevents the insert part 17 from rotating relative to the outer layer 12.

Next, FIGS. 14 to 17 show an embodiment in which the insert part 17 is provided by being embedded only in the outer layer 12. In particular, in this embodiment, the insert part 17 is provided inside the flange 12a formed as a part of the outer layer 12.
Is provided in a state of being buried. That is, FIG.
As shown in FIGS. 6 and 17, the outer layer 12 is provided on the outer peripheral surface of the hollow body 11, and a flange 12a is integrally formed at one end of the outer layer 12. The insert part 17 is embedded in a part of the flange 12a.
Is provided. In the insert component 17, a groove 17b as a second locking portion is formed on the outer peripheral surface, and a screw hole 17c is provided therethrough. In this case, the insert part 17 is provided so as to be embedded in the outer layer 12, particularly the flange 12a thereof, but is not embedded in the hollow body 11.

One example of manufacturing the configuration shown in FIGS. 16 and 17 is shown in FIGS. That is, as shown in FIG. 14, the mold is provided as a split mold between the split mold 21 and the split mold 20, and in the illustrated example, the split mold 21 is
Is provided so as to be able to move up and down relatively to the. Split mold 2
0 is formed with a recess 20b, and a projection 20a is formed to protrude upward from the bottom of the recess 20b. on the other hand,
The split mold 21 is formed with a recess 21a that can receive the tip of the projection 20a and a convex portion 21b that can be inserted into the recess 20b of the split mold 20. As shown in FIG. 14, the insert part 17 is arranged inside the recess 20b by extrapolating to the projection 20a. In this state, the split mold 21 is lowered so that the tip of the projection 20a is recessed 21a.
Insert into. In this state, the split mold 20 and the split mold 21 are in a mold closed state, and a cavity 23 is defined between them. Also, the concave portion 20b of the split mold 20 and the convex portion 2 of the split mold 21
1b, a predetermined gap 22 is formed. The gap 22 allows the gas such as air existing in the cavity 23 to flow out when the plastic material in the molten state is supplied into the cavity 23, but allows the molten plastic to be supplied into the cavity 23. Has a size that prevents the passage of

In the mold closed state shown in FIG. 15, a plastic material in a molten state is supplied into the cavity 23, and then the plastic material supplied into the cavity 23 is cured. Next, the split mold 21 is raised to be separated from the split mold 20, and the molded multilayer plastic molded body is taken out. By such a process, as shown in FIGS. 16 and 17, it is possible to provide the insert part 17 while being embedded in the flange 12a of the outer layer 12. As shown in FIGS. 14 and 15, in this embodiment, since the insert part 17 has the function of regulating the distance between the split mold 20 and the split mold 21, the spacer member 13 described above is used.
It is possible to exhibit the function of.

Next, with reference to FIGS. 18 to 22, a method for producing a multilayer plastic molded article by low pressure injection molding according to the present invention will be described. First, as shown in FIG. 18, the hollow body 1 having a desired shape is preferably formed by blow molding.
Form one. In the illustrated example, the hollow body 11 has a two-dimensional or three-dimensional pipe shape. After forming the hollow body 11 by blow molding, preferably, the hollow body 1
1 is filled with the filling material 24. Examples of the filling 24 may be particles such as, for example, sand particles or other substances. After filling with the filling 24, the opening of the hollow body 11 used for filling the filling 24 is sealed in a sealed state. This state is indicated by 25.
Accordingly, the hollow body 11 has a filling 24 filled therein in a sealed state.

Next, as shown in FIG.
Is set in the cavity of the mold. That is, in FIG. 19, the dies are split mold 20 and split mold 2.
It is composed of one pair of split molds. Split mold 20 and split mold 2
1 is relatively movable, and FIG. 19 shows a state where the split mold 20 and the split mold 21 are matched and the mold is closed. The split mold 20 and the split mold 21 can be moved in opposite directions to be separated from each other. That is, with the split mold 20 and the split mold 21 separated from each other, the hollow body 11 shown in FIG. In this case, in the illustrated split mold 20, pedestal portions 20c are formed at both left and right end portions, and both end portions of the hollow body 11 are placed on the pedestal portion 20c. Further, the spacer member 13 is arranged at an appropriate position in the mold groove of the split mold 20, and the hollow body 11 is placed thereon. Further, the spacer member 13 is disposed at an appropriate position above the hollow body 11. In this state, the split mold 21 is closed with the split mold 20 to obtain the state shown in FIG. In this case, pedestal portions 21c are formed at the left and right ends of the split mold 21, and these pedestal portions 21c come into contact with the hollow body 11, and the split mold 2 is formed.
The surface of one mold groove is substantially in contact with the spacer member 13. Accordingly, the hollow body 11 is disposed in the cavity defined by the split molds 20 and 21, and the spacer member 13 forms a predetermined gap 27 between the surface of the cavity and the outer peripheral surface of the hollow body 11. Will be maintained.

In the above-described embodiment, the case where the spacer member 13 and the hollow body 11 are separately provided has been described. However, the spacer member 13 is integrally formed at the same time when the hollow body 11 is formed by blow molding. Alternatively, after the hollow body 11 is formed by blow molding, the spacer member 13 can be integrated with a desired portion of the hollow body 11 by welding or bonding. When the hollow body 11 is provided with an insert part 17, one or more of the spacer members 13 can be replaced with such an insert part 17.

Next, as shown in FIG. 19, the split mold 20 and the split mold 21 are closed, and the plastic in a high-temperature molten state is supplied to the gap 27 with the hollow body 11 placed in the cavity. . In this case, the split mold 20 and the split mold 21
Are provided with a plurality of plastic material supply paths 26, respectively. That is, in the split mold 20, a total of three supply paths are formed, one at each of the two ends forming the flange portion later and one at the center position. The split mold 21 is provided with a supply path 26 symmetrically to the split mold 20. These supply channels 26 are in communication with one or more molten plastic sources from which hot molten plastic is supplied under pressure.

FIG. 20 shows a state in which the plastic substance is supplied to the gap 27 via the supply path 26. That is, the outer layer 12 is formed on the outer peripheral surface of the hollow body 11 by the supplied plastic substance, and the flanges 12 a are formed at both ends as a part of the outer layer 12. still,
The pressure at which the plastic material in the molten state is supplied to the gap 27 through the supply path 26 is set at 500 kg / cm ² or less, particularly in the range of 50 to 400 kg / cm ² . That is, the lowest possible injection pressure is used in order to sufficiently supply the plastic material to every corner of the gap 27 and to prevent the occurrence of voids and undesirable local thicknesses or thin portions at that time. It is desirable. However, according to the findings of the present inventors, when an injection pressure of less than 50 kg / cm ² is used, the plastic material in a high-temperature molten state is cooled and solidified while passing through the supply path 26, Was found to be closed or cooled and solidified in the middle of the gap 27. Therefore, in order to avoid such a problem, the injection pressure needs to be 50 kg / cm ² or more. On the other hand, it is desirable to have as high an injection pressure as possible in order to supply the plastic substance into the gap 27 as quickly as possible and to every corner. However, if the injection pressure is too high, the hollow body 11 may locally move or deform. For example, as shown in FIG. 22B, when a plastic material in a molten state supplied from the supply path 26 is supplied into the gap 27 with an excessively high pressure, the hollow body 11 is locally deformed and deformed. The unit D may be configured. On the other hand, FIG.
(A) shows a state where the hollow body 11 is not deformed when the supply pressure from the supply path 26 is appropriate. In order to avoid such deformation and displacement of the hollow body 11 and non-uniformity of the material, the injection pressure is set to 500
It has been found that it is necessary to be at most 400 kg / cm ² at kg / cm ² or less. Therefore, in the injection molding method of the present invention, the injection pressure of the high-temperature molten plastic material supplied from the supply path 26 to the gap 27 is set to 5
It is desirable to set the pressure within the range of 0 to 400 kg / cm ² .

Further, as shown in FIGS. 19 and 20, in this embodiment, a plurality of supply paths 26 are provided in each of the split dies 20 and 21. Supply path 26 so that the substance is supplied
Are arranged. By supplying the plastic substance from the plurality of supply paths 26 to the gap 27 in this manner, not only can the supply be performed more quickly, but also the composition of the outer layer 12 formed can be made uniform and the thickness can be increased. Can have a desired thickness. In the state of FIG. 20, after the plastic material forming the outer layer 12 is cured, the split mold 20 and the split mold 21 are separated, and the plastic molded body is taken out. Next, unnecessary portions at both ends of the hollow body 11 are cut off, and as shown in FIG. 21, a multilayer plastic molded body having a desired shape is obtained. In the manufacturing method described above, it is needless to say that the hollow body 11 can be a single layer or at least a part thereof can be a multilayer. Although the multilayer plastic molded article shown in FIG. 21 has a relatively simple shape, for example, a multilayer plastic molded article having a complicated shape as shown in FIG. Is of course possible.

[0042]

As described above, according to the present invention, a multilayer plastic molded article having heat resistance and / or durability is provided. In particular, according to the present invention, by using the spacer member, it is possible to provide a multilayer plastic molded article having uniform characteristics over the entire plastic molded article. Therefore, according to the present invention, it is possible to provide a multilayer plastic molded product having characteristics very close to design conditions, and the reliability thereof is significantly improved. Further, according to the present invention, there is provided a method capable of producing a multilayer plastic molded article having high reproducibility and repeatedly having the same performance. Therefore, for example, it is possible to manufacture an automobile part to which high temperature and high vibration are applied, such as an intake manifold and a radiator hose, from a plastic material. Further, according to the present invention, it is possible to reduce the weight of an automobile part, and it is possible to reduce the weight by 50% or more as compared with the case where a metal substance is used. Further, the method of the present invention enables a multilayer plastic molded article having a desired shape and size to be molded quickly and accurately even with a complicated shape and configuration.

Although the specific embodiments of the present invention have been described in detail above, the present invention should not be limited to 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]

1 (A) to 1 (C) are schematic views showing a pipe-shaped multilayer plastic molded article constituted based on one embodiment of the present invention.

FIG. 2 is a schematic perspective view showing a hollow body used in forming an intake manifold assembly according to another embodiment of the present invention.

3 is a schematic perspective view showing a state in which an outer layer is formed on the outer surface of the hollow body of FIG. 2 to form a multilayer plastic molded body.

FIG. 4 is a schematic sectional view taken along the line BB in FIG. 2;

FIG. 5 is a schematic sectional view taken along the line CC in FIG. 3;

FIG. 6 is a schematic view showing a state in which an insert part is provided integrally with a hollow body during blow molding according to another embodiment of the present invention.

FIG. 7 is a schematic diagram showing a state in which an outer layer is formed on the structure of FIG. 6;

FIG. 8 is a schematic diagram showing a state in which insert parts are integrally provided when a hollow body is formed by blow molding.

FIG. 9 is a schematic diagram showing a state in which an outer layer is provided in the configuration of FIG. 8;

FIG. 10 is a schematic view showing a state in which a through hole is formed through the insert part in the state of FIG. 9;

FIG. 11 is a schematic view showing a state where an insert part subjected to knurling is provided on the outer peripheral surface at the same time when a hollow body is formed by blow molding.

FIG. 12 is a schematic diagram showing a state where an outer layer is provided from the state of FIG. 11;

FIG. 13 is a schematic diagram showing a state in which a through-hole is formed through the insert part in the state of FIG. 12;

FIG. 14 is a schematic view showing a state in which the insert part is arranged in the split mold with the split mold and the split mold separated.

FIG. 15 is a schematic diagram showing a state in which the split mold and the split mold are closed from the state of FIG. 14;

FIG. 16 is a schematic perspective view showing a state in which an insert part is embedded in a flange and provided by the method of FIGS. 14 and 15;

FIG. 17 is a schematic sectional view taken along the line DD in FIG. 16;

FIG. 18 is a schematic view showing a hollow body used in the low-pressure injection molding method of the present invention.

FIG. 19 is a schematic view showing a state where the hollow body shown in FIG. 18 is arranged in a cavity formed between the split molds with the mold closed;

FIG. 20 is a schematic diagram showing a state in which a plastic substance is supplied to a gap between the hollow body and the cavity surface from the state of FIG. 19;

FIG. 21 is a schematic view showing a state in which an unnecessary portion has been removed from the molded article formed in FIG. 20 to complete a multilayer plastic molded article.

FIGS. 22A and 22B are schematic diagrams showing the influence of the state of injection pressure of a plastic substance.

[Explanation of symbols]

 1: Multi-layer plastic molded body 11: Hollow body 12: Outer layer 13: Spacer member 15: Cross-linking member 17: Insert part

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 23:00 F02M 35/10 102N (72) Inventor Yasuo Ezaki 119 Hatsukawa, Nitta-cho, Nitta-cho, Nitta-gun, Gunma Prefecture F term (reference) 3D038 BA00 BB01 BC00 4F202 AD05 AD13 AD20 AG03 AG12 AH17 AR02 CA11 CB01 CB11 CK81 CQ03 CQ05 4F206 AD05 AD13 AD20 AG03 AG12 AH17 AR022 AR025 JA07 JB11 JF05 JL02 JM04 JN11 JQ81

Claims (6)

[Claims] 1. A method of manufacturing a multilayer plastic molded body by integrally forming an outer layer made of a second plastic material on an outer surface of a hollow core formed into a predetermined shape from a first plastic material. A plurality of split molds constituting the mold are closed to define a cavity, and the hollow core is positioned in the cavity while maintaining a gap with the surface of the cavity, and then the second plastic material is melted. And supplying the second plastic material supplied to the gap within the predetermined pressure range of 500 kg / cm ² or less and curing the second plastic material to be integrated with the hollow core. 2. The method according to claim 1, wherein the second plastics material is supplied to the gap from a plurality of supply points of the cavity. 3. The method according to claim 1, wherein the predetermined pressure range is 50 to 400 kg / cm ² . 4. The gap between the hollow core and the cavity surface according to claim 1, wherein at least one spacer is interposed between the cavity surface and the hollow core. The method characterized by positioning. 5. The method of claim 4, wherein the spacer is integrally formed with the outer layer. 6. The hollow core according to claim 1, wherein the hollow core is filled with a filler in advance, and after the outer layer is formed, the filler is removed from the hollow core. A method characterized by removing.