JP3344437B2 - Method of manufacturing composite hollow double-walled molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a composite hollow double-walled molded article having a surface layer member which is filled and embedded by injection hollow molding on the wall surface of a hollow double-walled molded article integrally formed by blow molding. It is about the method.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a hollow double-walled molded product integrally formed by blow molding used for housings of various electric equipments has a pair of walls 101, opposing each other at intervals. A plurality of recesses 103 formed in one wall 101 are welded to the other wall 102, and the peripheral surfaces of both walls 101 and 102 are closed by an end wall 104 (actually-explained 4-). No. 10018). In order to use the hollow double-walled molded product shown in FIG. 6 for the housing panel, another member such as a foolproof, a bracket, and a mounting flange is attached to the surface of the housing panel by a fixing means such as a screw and assembled to the housing or the like. I have.

[0003] A method of integrally forming a projection by blow molding on a plastic container as shown in Fig. 7 is also known.

In this method, a parison extruded from a main injection port 205 is expanded along a cavity of a pair of closed molds 201 and 202, and at the same time, an auxiliary injection port 20 is expanded.
6, 207, respectively, to supply a molten resin to integrally form each projection 204 with the hollow molded article 203 (see Japanese Patent Publication No. 58-42017).

[0005]

However, among the above-mentioned prior arts, the method of attaching a separate member to the hollow double-walled molded product by using a fixing means such as a screw requires post-processing of the hollow double-walled molded product. Therefore, there is a problem that it is troublesome and productivity is low.

On the other hand, in the method of forming the projection by supplying the molten resin from the auxiliary injection port, since there is no means for regulating the shape of the projection, the accuracy of the outer shape of each projection and the accuracy of the boundary line with the container body are not improved. However, it is not suitable for the housing or the like that requires good appearance, and in addition, the welding area between the container main body and each projection cannot be increased, so that the welding strength is low.

The present invention has been made in view of the above-mentioned problems of the prior art, and has a high welding strength between a hollow double-walled molded product and a surface member, and the boundary between the two is also highly accurate. Further, it is another object of the present invention to realize a method for producing a composite hollow double-walled molded product with high productivity.

[0008]

In order to achieve the above-mentioned object, a method for producing a composite hollow double-walled molded product according to the present invention comprises a pair of walls opposed to each other at intervals, and at least one of the walls is provided. After a hollow double-walled molded product provided with a concave portion extending toward the other wall is integrally formed by blow molding on the wall, the surface of an injection hollow molding die is formed in the concave portion of the hollow double-walled molded product. After positioning the member molding cavity and injecting or injecting the molten resin into the space formed by the concave portion and the surface layer member forming cavity, or by injecting a pressurized fluid into the inside of the molten resin while injecting and injecting the molten resin. A surface member is formed along the space.

Further, the cavity for molding the surface layer of the mold for injection hollow molding has a space for molding a skin between substantially the entire surface of one of the walls provided with the concave portions of the hollow double-wall molded product. It is effective if the shape is formed.

[0010]

Since the hollow double-walled molded product is integrally formed by blow molding, the shapes of the wall surfaces of one wall and the other wall can be easily formed into an arbitrary complicated shape. In addition, since the surface member to be filled and embedded into the hollow double-walled molded product is injection-molded, even if the pressure of the molten resin is relatively low, the pressurized fluid evenly spreads the molten resin to a portion far from the injection inlet. Forming can be performed with high precision by the application of a pressing force.

[0011]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of a method for producing a composite hollow double-walled molded product according to the present invention. FIG. 1 (a) shows a hollow double-walled molded product integrally molded by blow molding for injection hollow molding. Schematic cross-sectional view showing a step of placing in a mold and clamping the mold,
(B) is a schematic cross-sectional view showing a step of injecting and injecting the molten resin after the step shown in (a), and (c) is a schematic view showing a step of forcing a pressurized fluid into the interior of the molten resin after the step shown in (b). It is sectional drawing. FIG. 2 is a sectional view taken along the line AA of FIG.

First, the hollow double-walled molded product 1 is integrally molded by blow molding. The hollow double-walled molded product 1 of the present embodiment includes one wall 2 and the other wall 3 opposed to each other at a distance from each other, the periphery of which is closed by an end wall 4. A stepped portion 2c is provided on the peripheral edge, and a streak-shaped concave portion 2a whose leading end surface is in contact with the other wall 3 is formed. On the other wall 3, a foolproof 3a whose wall surface swells outward is provided. A streak-shaped bracket hole 2b which is formed and penetrates one wall 2 and the other wall 3 is provided substantially parallel to the recess 2a.

The hollow double-walled molded product 1 obtained as described above is placed in a mold for injection hollow molding composed of one mold 11 and the other mold 12 to perform mold clamping.

This mold for injection hollow molding is composed of the other mold 1
The second cavity surface 12a is formed with a bracket recess 12b and a recess 12c corresponding to the bracket hole 2b and the foolproof 3a of the hollow double-wall molded product 1, respectively. Is a surface layer member molding in which when the mold is clamped after the hollow double-walled molded product 1 is arranged, a space for molding the skin 6a is formed between the hollow double-walled molded product 1 and almost the entire surface including the stepped portion 2c. Surface 11a for forming a cavity for use is provided.

After the above, the injection nozzle 14 is advanced to abut on the opening of the runner 13 and a predetermined amount of the molten resin 5
Is injected into the space, or while the injection is being performed, the pressurized fluid is press-fitted into the molten resin 5. Then
A frame portion 6d which is a thick portion where the flowability of the molten resin 5 is good;
A small hollow portion 6e communicating with the bracket 6c and the anchor portion 6b is formed and expands, and the molten resin spreads to every corner of the space portion.
c, and is filled and embedded in the bracket hole 2b and the concave portion 2a. Thereby, the skin portion 6a, the anchor portion 6b,
A composite hollow double-walled molded product including the surface layer member 6 including the bracket 6c and the frame portion 6d and the hollow double-walled molded product 1 is integrally formed. The surface member may have a concave portion on its surface as needed.

After cooling, the injection nozzle 14 is retracted and the mold is opened to take out a composite hollow double-walled molded product.

In this embodiment, as shown in FIG. 2, a runner 13 and a pressurized fluid inlet 15 are provided at one corner of the injection mold so as to sandwich the corner, and the remaining three By providing a resin escape portion 12d for allowing the resin to escape, a pressurized fluid is press-fitted into the interior of the molten resin to release the excess molten resin when a small hollow portion is formed, thereby increasing the hollow ratio of the surface member 6. Can be.

Further, in this embodiment, almost the entire surface of one wall is covered by the skin portion 6a of the surface layer member 6 formed by injection blow molding which has a better surface appearance as compared with blow molding. Good composite hollow double-walled molded products can be manufactured.

FIG. 3 is a partially cutaway perspective view showing a composite hollow double-walled molded product as a housing panel of an electric device manufactured according to a modification of the first embodiment.

The composite hollow double-walled molded article manufactured according to this modification is the same as the foolproof 3a and the recess 2 of the first embodiment.
a, foolproof 23 having enlarged portions 23b each having a shorter length in the longitudinal direction instead of the bracket hole 2b
a, a plurality of recesses 23c protruding toward one wall 22 are interspersed in the bracket hole 22b and the other wall 23. The other points are the same as in the first embodiment, and the description is omitted.

Next, a second embodiment of the present invention will be described.

First, the split type mold used in the present embodiment will be described. As shown in FIG.
Are one wall 42 and the end wall 4 of the hollow double-walled molded product 41.
4 is provided with a cavity that regulates half of
Is the other wall 43 and the end wall 4 of the hollow double-walled molded product 41.
4 and a guide hole 46a for selectively inserting a slide core 47 or an injection blow molding die 48 to be described later, and selectively inserted into the guide hole 46a. It consists of a slide core 47 and an injection molding die 48.

The slide core 47 has a concave portion 4 extending toward the one wall 42 formed on the other wall 43 on the distal end surface thereof.
A protrusion 47a for molding 3a is provided,
A bracket 50, which is a cavity for molding a surface layer member, is formed on the distal end surface of the injection molding die 48 together with the concave portion 43a.
Has a recess 48a for a bracket for molding the same, and the recess 48a for the bracket is communicated with a runner 48c having an open end on the bottom wall surface of the injection nozzle insertion hole 48b.

The steps of this embodiment will be described.

The slide core 47 is inserted into the guide hole 46 a of the other mold 46, the molds 45, 46 are opened, and then the molten parison is extruded from an extrusion head of an extruder (not shown) to extrude both molds. Place between molds.

After that, the mold is closed, the parison is sandwiched between the two molds 45 and 46, and a piercing needle (not shown) is inserted into the parison to introduce a pressurized fluid such as air to expand the mold. Blow molding is performed along a cavity formed by the molds 45 and 46 and the slide core 47 to obtain a hollow double-walled molded product 41 integrally molded.

Then, after pulling out the slide core 47 from the other mold 46, an injection blow molding mold 48 is inserted into the guide hole 46 a, and the front end surface thereof is formed into the other wall 43 of the hollow double-wall molded product 41. After a predetermined amount of molten resin is injected and injected from the injection nozzle 49 inserted into the injection nozzle insertion hole 48b, or while the injection resin is being injected, a pressurized fluid is press-fitted into the interior of the molten resin. By forming the hollow portion 50a, the bracket 50 having the small hollow portion 50a therein is injection-molded along the space surrounded by the concave portion 43a and the bracket concave portion 48a. Thereby, the other wall 4 of the hollow double-walled molded product 41
A bracket 50 having a small hollow portion 50a is filled and embedded in a concave portion 43a provided in the device 3.

After cooling, the injection nozzle 49 and the injection mold 48 are retracted, the molds 45 and 46 are opened, and the hollow double-walled molded product 41 in which the bracket 50 is filled and embedded is taken out. .

Instead of the concave portion 43a in the present embodiment, the concave portion may be a concave portion in which the tip end surface is in contact with one wall, and the concave portion 48a for the bracket of the injection molding die 48 is formed.
In place of this, a composite hollow double-walled molded product in which a concave portion having a shape for molding other functional components such as fool proof is provided on the tip end surface of the injection hollow molding die, and other functional components are filled and molded. Can be manufactured.

In the present invention, the pressurized fluid may be nitrogen gas, air, water or a vaporizable liquid. The resin used for blow molding or injection blow molding is ABS.
Resin, polypropylene, polystyrene, polyethylene,
Thermoplastic synthetic resin materials such as modified polyphenylene oxide, polycarbonate, polyamide, polyethylene terephthalate, polybutylene terephthalate, and other resins having elastomeric properties can be used. It should be noted that known fillers, flame retardants, pigments, foaming agents, and the like can be added to the above-described materials as necessary.

The blow molding material and the injection hollow molding material are:
It is preferable to use a material of the same quality in order to improve the welding strength or utilize recycled materials.

The hollow molded article obtained by the present invention is used for electric equipment such as copying machines, computers, printers, and electronic musical instruments, housing equipment such as cabinets, wagons, desks, and partitions, and automobiles such as dashboards, seat backs, and soundproof covers. It can be used as a plate material, a frame material, and other members constituting parts.

[0034]

Since the present invention is configured as described above, the following effects can be obtained.

Even a hollow double-walled molded product in which the shape and size of the hollow portion changes in a complicated manner can be easily manufactured.
The injection hollow molding allows filling and embedding of the surface layer member at relatively low pressure, so that the hollow double-wall molded product does not deform,
In addition, since the surface layer member is filled and embedded in the concave portion of the hollow double-walled molded product, the welding strength of both is increased, and the position and the shape accuracy are high, so that the appearance is good. Composite hollow double wall moldings can be manufactured.

Further, the invention according to claim 2 can produce a composite hollow double-walled molded product having a good surface appearance in addition to the above effects.

[Brief description of the drawings]

1A and 1B show a first embodiment, in which FIG. 1A is a schematic cross-sectional view showing a process of placing a hollow double-walled molded product in an injection blow molding die and clamping the die, and FIG. Schematic cross-sectional view showing a step of injecting molten resin into the cavity after the step shown in,
(C) is a schematic sectional view showing a step of forming a small hollow part by press-fitting a pressurized fluid into the molten resin after the step shown in (b).

FIG. 2 is a cross-sectional view taken along line AA of FIG. 1 (c).

FIG. 3 is a partially cutaway perspective view showing a composite hollow double-walled molded product manufactured according to a modification of the first embodiment.

FIG. 4 is a schematic sectional view of a main part showing a blow molding step of a second embodiment.

FIG. 5 is a schematic sectional view of a main part showing an injection blow molding step of a second embodiment.

FIG. 6 is a schematic sectional view of a main part of a conventional hollow double-wall molded product.

FIG. 7 is a schematic cross-sectional view showing one step of a conventional method for producing a composite molded article.

[Explanation of symbols]

 1, 21, 41 Hollow double-wall molded product 2, 22, 42 One wall 2a, 23c, 43a Concave portion 2b, 22b Bracket hole 2c Stepped portion 3, 23, 43 Other wall 3a, 23a Full proof 4, 44 End wall 5 Molten resin 6, 25 Surface member 6a, 25a Skin 6b Anchor 6c, 25c, 50 Bracket 6d Frame 11, 45 One mold 11a, 12a Cavity surface 12, 46 The other mold 12b, 48a Bracket Recess 12c Recess 13,48c Runner 14,49 Injection nozzle 46a Guide hole 47 Slide core 47a Projection 48 Injection hollow molding die 48b Injection nozzle insertion hole

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/00-45/84 B29C 49/00-49/80 B29D 24/00

Claims (2)

(57) [Claims] 1. A hollow double-walled molded product having a pair of walls facing each other at intervals and having a concave portion extending toward at least one of the walls on at least one of the walls is formed by blow molding. After being integrally molded, a cavity for molding a surface layer member of an injection molding die is positioned in the concave portion of the hollow double-wall molded product, and a molten resin is formed in a space formed by the concave portion and the cavity for molding the surface layer member. And forming a surface layer member along the space by injecting a pressurized fluid into the molten resin while injecting or injecting the molten resin into the molten resin. . 2. The cavity for molding a surface member of a mold for injection hollow molding has a space for molding a skin between substantially the entire surface of one of the walls provided with the concave portions of the hollow double-wall molded product. The method for producing a composite hollow double-walled molded product according to claim 1, wherein the molded product has a shape to be formed.