JP2002326249A - Resin molded product and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin molded product having a hollow wall structure only at a necessary part thereof as the resin molded product used in a car such as a truck or the like and molded from a reduced use amount of a resin material without relying on blow molding, and a method for manufacturing the same. SOLUTION: A hinge part 3 is formed to the intermediate part 11 of a molded object obtained by injection-molding a polypropylene material and the bending part of the molded object is bent along the hinge part 3 to be superposed on a substrate part 2 to form a superposed part 7. Since the resin molded product 1 is not entirely formed into a double-wall structure from the beginning by blow molding and only the necessary part of the resin molded product is formed into the double-wall structure corresponding to the bending part, the use amount of the resin material is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molded product manufactured by injection molding of a synthetic resin material, such as a resin molded panel such as a ceiling provided in an automobile such as a truck, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a resin molded product such as a truck ceiling is formed into a hollow wall structure by blow molding. FIG. 5A is a cross-sectional view of a conventional resin molded product at the time of molding, and FIG. 5B is a cross-sectional view showing a state in which a reinforcing member is arranged on the resin molded product shown in FIG.
FIG. 6C is a cross-sectional view illustrating the resin molded product in a state where a part of the resin molded product illustrated in FIG. A resin molded product 30 at the time of molding shown in FIG. 5A has a main body portion 32 formed in a hollow wall structure 31 by blow molding of resin.
A hinge part 33 formed by crushing the hollow wall as a boundary of the main body part 32 and being easily bent, and a folded part 34 connected to the hinge part 33 and having a double wall structure in which the wall parts are in close contact with each other.
It is composed of For blow molding, the main body 32
Burrs 35, 3
5 are left. One wall structure of the hollow wall structure 31 is:
A relatively flat lower wall 36 forming a ceiling surface;
The other wall structure comprises an uneven wall 38 which faces the lower wall 36 and is partially joined at a plurality of places, and an angle wall 37 which is connected to the uneven wall 38.
And an angle wall 39 forming a hollow portion 40 similar to the hollow wall structure 31 in cooperation with the above.

As shown in FIG. 5B, burrs 35, 35
Is cut and trimmed, a metal reinforcing plate 41 is disposed along the angle wall 39. Thereafter, the folded portion 34 located outside is folded back with the hinge portion 33 as a bending axis as shown by an arrow, and the reinforcing plate 41 is sandwiched between the angle wall 39 and the folded portion 34, and the distal end portion 42 of the folded portion 34. Is brought into contact with the uneven wall 38 of the main body 32. As shown in FIG. 5C, the angle wall 39, the reinforcing plate 41, and the folded portion 34 are fastened together by a rivet 43 that penetrates each other, thereby forming the cylindrical portion 44 that forms the hollow portion 40 inside. Is done.

As a resin molded product for an automobile, there is a shelf member used for a tonneau cover, a parcel shelf, etc. provided behind a rear seat of an automobile. Are disclosed. The shelf board member disclosed in this publication includes a resin body having a substantially flat portion and four peripheral edges therearound, and at least one peripheral edge of the four peripheral edges is closed in a square shape in cross section. It is formed in a hollow body, and reinforcing members are respectively arranged on upper and lower constituent walls substantially parallel to the plane portion among the constituent walls of the hollow body, so that it is reinforced against a load acting in a direction orthogonal to the plane portion. The members exhibit high rigidity, and achieve a high weight-stiffness ratio and a reduction in weight required as a shelf member from the viewpoint of mounting on a vehicle. Further, as a method of manufacturing a shelf member, a magnet is embedded in a mold bottom surface corresponding to an outer shape of a shelf member having a substantially flat portion and a hollow body having a closed cross section of at least one peripheral portion, and both mold surfaces of a molding die are formed. A method is disclosed in which a decorative skin material is set on a magnet, and a metal reinforcing member is suction-fixed to the magnet via the decorative skin material, and then blow-molded.

[0005] In the above resin molded product, if the hollow wall structure is formed by blow molding, the characteristics of blow molding are:
The entire product must be configured with a double wall structure, and unnecessary parts also have a double wall structure. As a result, the amount of resin material used for molding one resin molded product increases, and the weight increases and the resin material cost increases. Further, when a resin molded product is manufactured by blow molding, it is inevitable that burrs are generated. Therefore, the yield is reduced, the deburring step cannot be omitted, the production efficiency is reduced, and the manufacturing cost is increased. In addition, burrs remain and the appearance of the resin molded product is poor.

[0006]

The problem to be solved by the present invention is to provide a resin molded product for use in automobiles such as trucks, for example, in which the amount of resin material used is reduced without relying on blow molding. An object of the present invention is to devise a structure and to devise a production method which enables production of such a resin molded product.

An object of the present invention is to reduce the amount of resin used to reduce the weight and production cost of a resin molded product.
By avoiding the occurrence of burrs, which has occurred when a resin molded product was manufactured by blow molding, the appearance of the resin molded product is improved, the yield and production efficiency are improved, and the manufacturing cost is reduced. And a method for producing the same.

[0008]

According to the present invention, there is provided a molded article formed by injection, wherein a hinge formed at an intermediate portion of the molded article and a hinge formed by bending the hinge are used to form the molded articles. The present invention relates to a resin molded product comprising a superposed portion formed by superposing.

According to the present invention, a molded body having a hinge portion at an intermediate portion is formed by injection, the molded body is bent at the hinge portion, and the molded bodies are overlapped with each other to form an overlapped portion. And a method for producing a resin molded product.

According to the resin molded product and the method of manufacturing the same according to the present invention, a molded article is molded by injection,
A resin molded product is formed by bending the molded body at a hinge portion formed at an intermediate portion thereof. An overlapped portion is formed by bending the formed bodies and overlapping the formed bodies. Since it is not a double-walled structure from the beginning as in blow molding, by selecting and setting an area of a formed part to be bent, only a necessary part is formed in a double-walled structure.

[0011] In this resin molded product, the overlapping portion is welded at a part of the overlapped molded body.
By bending the formed bodies at the hinge portion and overlapping the formed bodies and welding a part thereof, separation of the bent formed body is reliably prevented, and the rigidity of the overlapped portion is increased.

In this resin molded product, a hollow portion is formed from the molded body bent at the hinge portion, and a reinforcing pipe is disposed inside the hollow portion. By arranging the reinforcing pipe inside the hollow portion, the rigidity of the entire resin molded article including the hollow portion as well as the hollow portion itself is enhanced, and deformation when an external force acts is prevented. In addition, by fixing the reinforcing pipe to the hollow portion, the strength of the hollow portion is further increased.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a resin molded product and a method of manufacturing the same according to the present invention will be described with reference to the accompanying drawings. 1 is a perspective view showing one embodiment of the resin molded product according to the present invention, FIG. 2 is a sectional view showing a state of the resin molded product shown in FIG. 1 at the time of molding, and FIG. 3 is an assembly of the resin molded product shown in FIG. Is a cross-sectional view showing a completed state.

The embodiment shown in FIG. 1 is an example in which the resin molded product of the present invention is embodied as a shelf structure 1 provided on the ceiling of a truck. The shelf structure 1 shown in FIG. 1 is formed by injection using polypropylene as a resin material, and is shown in the shape at the time of molding, similarly to FIG. The injection-molded shelf structure 1 includes a substrate portion 2 and a substrate portion 2
A hinge portion 3 formed at the intermediate portion 11 so as to be thinner along one side so as to be easily bent, and a bent plate portion 4 formed to extend from the hinge portion 3 to the opposite side to the substrate portion 2. And The hinge 3 is formed simultaneously with the molding of the resin molded product by injection molding of polypropylene. Since the lower surface 5 of the substrate portion 2 is a surface exposed to the human eye, it is subjected to a leather grain or satin surface treatment. A plurality of projections 8 (only a part is attached) are integrally formed on the upper surface 6 of the substrate unit 2.

Bending plate portion 4 using hinge portion 3 as a bending axis
Is folded and superimposed on the upper surface 6 side of the substrate portion 2,
The flat portion 4a of the bent plate portion 4 is overlapped with the flat plate portion 2a which is a part of the substrate portion 2 to form an overlap portion 7 (see FIG. 3). The flat portion 4a of the bent plate portion 4 is formed with unevenness for increasing strength, and a plurality of through-holes 9 (partially) for receiving the respective projections 8 are formed in the uneven portion in contact with the flat plate portion 2a. Only attached). When the bent plate portion 4 is overlapped on the substrate portion 2, the projections 8 are fitted into the through holes 9. Therefore, the overlap portion 7 has a double wall structure in which the substrate portion 2 and the bent plate portion 4 overlap. And the rigidity is increased. In addition, the tip of the projection 8 exposed from the through hole 9 is welded to the opening of the through hole 9 and the peripheral edge thereof to form a welded portion 10, whereby the bent plate portion 4 is firmly fixed to the substrate portion 2. The rigidity of the double wall structure is further enhanced.

The portions of the injection-molded substrate portion 2 close to the hinge portion 3 are walls 2b and 2c constituting a part of an angle of a hollow portion 12 to be described later. A hollow portion 12 is formed from a connecting portion 2e between the flat plate portion 2a and the wall portion 2b of the substrate portion 2.
The wall part 2d which constitutes a part of is extended upright. Since the connecting portion 2e is thick, the cavity 2f may be formed by using gas during injection molding. Folded plate part 4
Is bent, a wall portion 4b which is a part of the bent plate portion 4
Constitutes a part of the hollow portion 12, and the wall portion 4c, which is connected to the wall portion 4b at an angle, wraps around the outside of the wall portion 2d to form the wall portion 2d.
And the wall portion 4c constitute a double wall structure continuous with the overlapping portion 7.

When the bent plate portion 4 is bent, the substrate portion 2
The wall portions 2b to 2d and the wall portion 4b of the bent plate portion 4 form a hollow portion 12 surrounding the columnar space 13. A reinforcing member, that is, a reinforcing pipe 14 having a square cross section is previously provided in the columnar space 13.
When the bent plate portion 4 is bent, the reinforcing pipe 14 supports the wall portions 2b to 2d and the wall portion 4b from inside, so that the rigidity of the hollow portion 12 is remarkably improved. Let it. Pipe 1 reinforced with pop rivets 15
The rigidity of the hollow portion 12 can be further increased by connecting the 4 to the wall 2d and the wall 4c.

Another embodiment of the resin molded product according to the present invention is shown in the perspective view of FIG. The embodiment shown in FIG. 4 is an example of a shelf structure in which a portion to be reinforced by forming a bent plate portion into a double wall structure is limited to a necessary portion. In the shelf structure 20 shown in the drawing, the same reference numerals are given to the same parts and parts as those constituting the shelf structure 1 shown in FIG. 1, and the description thereof will not be repeated. In the shelf structure 20 shown in FIG. 4, the bent plate portion 24 has a portion at a middle position along the hinge portion 3 omitted, and only both end portions 24a and 24b are left. When the bent plate portion 24 is bent around the hinge portion 3, only the overlapping portions 27a and 27b on both sides corresponding to both end portions 24a and 24b are overlapped with the substrate portion 2 to form a double wall structure. Becomes As in the example of FIG. 1, the overlapping portions 27a and 27b are securely fixed by the welded portion 10 provided between the tip of the projection 8 and the opening of the through hole 9 in both end portions 24a and 24b, and have rigidity. Will be higher. In this example, since the center portion of the bent plate portion 24 is omitted, the weight is reduced and the amount of material used is reduced, so that the manufacturing cost can be reduced.

By using injection molding for the resin molding, it is possible to avoid the occurrence of burrs on the periphery of the molded body as in the case of blow molding. A gas injection molding method is used to form the cavity 2f in which gas is sealed. In the gas injection molding method, for example, molten resin is injected in advance into a cavity formed according to the shape of a resin molded product, and after 75% to complete filling, a resin filling shortage or a sink due to resin shrinkage is reduced. Gas is injected from the nozzle while filling.

[0020]

According to the resin molded article and the method of manufacturing the same according to the present invention, the resin molded article is manufactured not by blow molding but by injection molding. By setting the area, only a necessary part is formed in the double wall structure. Therefore, the amount of the resin material used is reduced, and the weight of the resin molded product can be reduced. Further, since burrs are not generated unlike in blow molding, the yield is improved, the deburring step can be omitted, and the appearance of the resin molded product due to the remaining burrs remains without deterioration. Therefore, the production efficiency of the resin molded product is improved, and the production cost can be reduced. Further, by forming a hollow portion at a necessary portion when bent at the hinge portion and arranging a reinforcing pipe in the hollow portion, the hollow portion and the resin molded product can be reinforced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a resin molded product according to the present invention.

FIG. 2 is a sectional view showing a state of the resin molded product shown in FIG. 1 during molding.

FIG. 3 is a sectional view showing a state where assembly of the resin molded article shown in FIG. 2 is completed.

FIG. 4 is a perspective view showing another embodiment of the resin molded product according to the present invention.

5A and 5B are views showing a conventional resin molded product obtained by blow molding. FIG. 5A is a cross-sectional view of the conventional resin molded product during molding, and FIG. 5B is a diagram showing the resin shown in FIG. FIG. 5C is a cross-sectional view showing a state in which a reinforcing member is disposed on the molded product, and FIG.
Sectional drawing which shows the resin molded product in the state which folded and completed the resin molded product shown in (b).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Resin molded product 2 Substrate part 3 Hinge part 4 Bent plate part 7 Overlapping part 10 Welding part 11 Intermediate part 12 Hollow part 13 Columnar space 14 Reinforcement pipe 15 Pop rivet

Claims (4)

[Claims] 1. A molded part formed by injection, and a hinge formed at an intermediate portion of the molded body, and an overlap formed by bending the molded part and overlapping each other by the hinge part. A resin molded product consisting of a mating part. 2. The superposed portion is welded at a part of the superimposed molded body.
The resin molded product according to the above. 3. The resin molded product according to claim 1, wherein a hollow portion is formed by bending at the hinge portion, and a reinforcing pipe is provided inside the hollow portion. 4. A resin comprising forming a molded body having a hinge portion at an intermediate portion by injection, bending the molded body at the hinge portion, and laminating the molded bodies to form an overlapped portion. Manufacturing method of molded article.