JPS6283112A - Manufacture of hollow resin part - Google Patents

Abstract

PURPOSE:To easily manufacture a hollow resin part with out the needs to take out a core by using a manufacturing method consisting of a core-setting process to set a core in the cavity, a resin-molding process to pack a resin material into the cavity for molding, and a hollow-forming process to form a hollow by melting and contracting the core. CONSTITUTION:Cores 36 and 38 having much the same shape as through-holes 20 and 22 are set on given positions in the cavity 32, and a mold 24 is clamped. The cores 36 and 38 of expanded polystyrene which can be melted, degassed, and contracted on heating are supported on both end portions in the longitudinal direction (core-setting process A). A resin base material 16 of rigid urethane foam is formed in such a way as to embrace the cores 36 and 38 in the cavity 32 (resin molding process B). Through-holes 20 and 22 are formed in both side walls 12 and 14 of the resin base material 16 so molded (hollow-forming process C).

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method of manufacturing a resin hollow part having a hollow portion, and particularly to a manufacturing method that allows the hollow portion to be easily formed.

BACKGROUND OF THE INVENTION Hollow portions are sometimes provided in resin parts due to structural needs or to reduce the weight of the parts.

When manufacturing hollow resin parts with such hollow parts, generally a core molded with sand, low melting point alloy, wax, etc. into the same shape as the hollow part is used, and this is inserted into the product cavity of the mold. After placing the resin material in the product cavity, the resin material to form the resin hollow part is filled and molded, and then the core is taken out from the molded resin material to form the hollow part. Usually, a resin hollow part is obtained. According to such a manufacturing method, compared to the case where a hollow part is formed by integrally butting a pair of halves formed by dividing the desired resin hollow part into two, manufacturing man-hours and manufacturing equipment are required. This has the advantage that less is required and the product can be manufactured at low cost.

Problems to be Solved by the Invention However, the work of removing the core from the molded resin material is troublesome, and especially when the core has a hollow part with a complicated shape, the core may be destroyed or melted. I had to take it out. In addition, when manufacturing hollow resin parts with closed hollow parts, it is necessary to close the opening of the extraction hole after taking out the core, which makes the work even more troublesome and reduces the aesthetic quality of the product. Another problem was that the appearance was compromised.

Means for Solving the Problems The present invention has been made to solve the above problems, and its gist is a method of manufacturing a resin hollow part having a hollow part, a) A core molded using a foamed resin material that can be melted and shrunk by heating,
(b) a step of placing a core in a product cavity having a shape corresponding to the resin hollow part; (b) a resin material forming the resin material by filling the resin material to form the resin hollow part into the product cavity; and (C) a hollow portion forming step of melting and shrinking the core by heating to form the hollow portion.

According to such a manufacturing method, the core used to form the hollow portion melts and shrinks when heated, so that the core is removed from the formed hollow portion afterwards. The troublesome work of taking out the product is eliminated, and even resin hollow parts having complex-shaped hollow parts or closed hollow parts can be easily manufactured, and the cost of the product can be reduced. In particular, when manufacturing a resin hollow part having a closed hollow part, there is no need for a hole for taking out the core as in the conventional method, which has the advantage of improving the aesthetic effect of the product.

The foamed resin material for forming the core may be any material as long as it melts and shrinks when heated; for example, foams made of thermoplastic resin materials such as polystyrene foam, polyethylene foam, polypropylene foam, etc. It can be suitably used.

In addition, thermosetting resin is preferably used as the resin material that should constitute the resin hollow part, and especially if it emits reaction heat during molding and curing, the reaction heat will cause the core to be heated. Hollow parts can also be formed by melting and shrinking, making it possible to create hollow parts made of resin.
It has the advantage of being easier to construct. Such resin materials include, for example, urethane resin and monomer cast nylon resin.

EXAMPLE Hereinafter, an example of the present invention will be explained in detail based on the drawings.

First, FIG. 1 is a front view showing an automobile center console box 10 as a resin hollow part manufactured according to the manufacturing method according to the present invention, and FIGS.
The figures are the ■-■ cross-sectional view and ■-■ in Figure 1, respectively.
FIG. As is clear from FIG. 3, this center console box IO includes a resin base material 16 having a substantially U-shaped cross section and a side wall portion 12.14, and is fixed to the outer peripheral surface of the resin base material 16. The epidermis 18 is made up of The resin base material 16 and the skin 18 are made of hard urethane resin foam and vinyl chloride resin, respectively.

In addition, through holes 20 and 22 are provided in both side walls 12 and 14 of the resin base material 16, respectively, to penetrate the center console box 10 in the longitudinal direction.
For example, it can be used as a passage for conveying air-conditioned air to the rear seats of an automobile. In this embodiment, these through holes 20 and 22 form a hollow portion.

Next, a method of manufacturing such a center console box 10 will be explained according to FIGS. 4 to 6. In these figures, 24, 26° 28 and 30 are molds for integrally molding the center console box 10, and when these molds are clamped, there are molds inside that correspond to the center console box 10. A product cavity 32 having a shape is formed.

First, after the molds 26, 28 and 30 are clamped, the vinyl chloride sheet 34 which is to constitute the skin 18 is placed along the molding surfaces of the molds 26, 28 and 30. Thereafter, cores 36 and 38 having substantially the same shape as the through holes 20 and 22 are placed at predetermined positions within the product cavity 32, and the mold 24 is clamped. The cores 36 and 3 are made of polystyrene foam that can be melted and defoamed and contracted by heating, and are supported at both ends in the longitudinal direction. The above is the core arrangement process, and FIG. 4 shows this state. Note that both ends of the vinyl chloride sheet 34 are molded into molds 24 and 26.
．． 30.

Next, the stock solution of the hard urethane resin foam that is to constitute the resin base material 16 is mixed with a mixing head or the like and injected into the product cavity 32 from an injection port (not shown) to foam it. Then harden and mold. As a result, inside the product cavity 32, the core 36.
The resin base material 16 made of a hard urethane resin foam is molded so as to enclose the resin base material 38 . This step is a resin material molding step, and FIG. 5 shows the resin base material 16 molded in this manner.

Here, since reaction heat is generated by the urethanization reaction during molding of the hard urethane resin foam, the reaction heat is stored in the product cavity 32 as the hard urethane resin foam is molded and cured. The cores 36 and 38 made of the polystyrene foam are heated and melted by the heat of reaction, and are no longer able to retain gas, causing them to shrink. The thickness and density of the resin base material 16 around the core 36.38 are set so that the core 362.3 can be melted and shrunk by the reaction heat during molding. .38 size etc., but for example, the wall thickness is 10m or more, the density is 0.3g/ai1
It is set as above. As a result, the through holes 20.1 are formed in both side wall portions 12.degree.
22 will be formed. This process is the hollow part forming process, and FIG.
It shows the state in which a is formed. Note that the melted and shrunk resin 40.42 accumulates in the lower part of the through hole 20.22 and is welded to the resin base material 16.

On the other hand, the vinyl chloride sheet 34 is fixed to the outer circumferential surface of the resin base material 16 at the same time as the resin base material 16 is molded by the reaction heat of the hard urethane resin foam or a pre-applied adhesive. Ru.

Thereafter, the molds 24, 26, 28, and 30 are released, the resin base material 16 is taken out, and both ends of the vinyl chloride sheet 34 are cut off, thereby obtaining the center console box 10 described above.

As described above, according to the manufacturing method of this embodiment, the through hole 20
．． The cores 36 and 38 for forming the core 22 are made of polystyrene foam, and are melted and shrunk by the heat of reaction during molding of the resin base material 16 made of hard urethane resin foam. Therefore, resin base material 1
The troublesome work of taking out the cores 36 and 38 after molding of the center console box 6 is eliminated, the center console box 10 having the through holes 20 and 22 can be easily manufactured, and the product can be provided at low cost. In particular, in this embodiment, the reaction heat of the rigid urethane resin foam is used to melt and shrink the core 36.38, so the core 36.38 is heated from the outside to melt and shrink. This has the advantage of eliminating the need for additional work and making manufacturing easier.

Note that since the resin 40.42 obtained by melting and shrinking the cores 36, 38 is welded into the through holes 20, 22 of the resin base material 16, the functions of the product are not impaired by them.

Next, we reduced the thickness of the resin foam to simplify the mold structure by lowering the foaming pressure, or due to structural or design constraints.
An example of manufacturing a resin hollow part having an internally closed hollow part will be described with reference to FIGS. 7 and 8. FIG.

First, a skin material 56 such as a vinyl chloride sheet and a core 58 are placed in a product cavity 54 formed by a pair of molds 50 and 52 (core placement step). This core 58 is made of the same polystyrene foam as in the previous embodiment, and is held at a predetermined position within the product cavity 54 by a support rod 60 provided in the mold 50.

Next, the product cavity 54 is filled with a stock solution of hard urethane resin foam, and it is foam-molded. As a result, a resin base material 62 made of a hard urethane resin foam is molded into the product cavity 54 so as to wrap around the core 58 (resin material molding). As the molding and curing of the rigid urethane resin foam progresses, heat of reaction is stored in the product cavity 54, and the core 58 made of polystyrene foam is melted and shrunk by this reaction heat, as shown in FIG. As shown in , a closed hollow portion 64 is formed inside the resin base material 62 (hollow portion forming step).

Thereafter, the pair of molds 50 and 52 are released, the resin base material 62 is taken out, and the excess portion of the skin material 56 is cut off, thereby obtaining the desired resin hollow part.

Note that, like the vinyl chloride sheet 34 in the above embodiment, the skin material 56 is formed on the resin base material 6 by the reaction heat of the hard urethane resin foam or the adhesive applied in advance.
It is fixed to the surface of 2. Further, the melted and shrunk resin 66 is welded to the resin base material 62 at the lower part of the hollow portion 64.

In this embodiment as well, since the hollow portion 64 is formed by melting and shrinking the core 58 as in the previous embodiment, a resin base is used to take out the core 58 as in the conventional case. There is no need to provide a take-out hole or the like in the material 62, which facilitates the manufacturing work of resin hollow parts, and has the advantage that the aesthetic appearance of the product is not impaired.

Although the embodiments of the present invention have been described above in detail based on the drawings, the present invention can also be implemented in other embodiments.

For example, in the embodiment described above, the reaction heat of the hard urethane resin foam constituting the resin base materials 16 and 62 is used to
．． 38.58 is melted and shrunk, but the reaction heat of the rigid urethane resin foam alone may not be enough to melt and shrink it, or the resin base material 16, 62 may be a resin material that does not cause an exothermic reaction during molding. When using the core 36, the core 36.
38.58 may be heated to melt and shrink.

Furthermore, although polystyrene foam is used as the cores 36, 38, 58 in the above embodiments, other foamed resin materials that can be melted and shrunk by heating may also be used. Moreover, other types of resin materials than the hard urethane resin foam can be used as the resin material that should constitute the resin base materials 16, 62.

Furthermore, in the embodiment, the resin base materials 16, 62 and the epidermis 1
Although the resin hollow part is made up of a skin made of 8 or skin material 56, the skin does not necessarily need to be made of a resin material, and can be made of woven fabric, synthetic leather, etc. Yes, there is also a resin base material 16
, 62 alone can constitute a resin hollow part.

Furthermore, in the embodiments shown in FIGS. 1 to 6, the present invention is applied to the manufacture of a center console box 10 having through holes 20, 22, but the present invention is applicable to other resin hollow Of course, it can also be applied to the manufacture of parts.

Although other examples are not given, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a front view showing an example of an automobile center console box manufactured according to the manufacturing method according to the present invention. FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1. FIG. 3 is a cross-sectional view taken along line -III in FIG. 1. 4 to 6 are cross-sectional views explaining the manufacturing process of the center console box shown in FIG. 1. FIG. 4 shows the core placement process, FIG. 5 shows the resin material molding process, and FIG. FIG. 6 is a diagram illustrating the hollow portion forming process. 7 and 8 are cross-sectional views illustrating manufacturing steps in other embodiments of the present invention. FIG. 7 is a diagram illustrating a resin material molding process, and FIG. 8 is a diagram illustrating a hollow part forming process, respectively. . 10: Center console box (resin hollow part) 20.227 Through hole (hollow part) 32.54: Product cavity 36.38.58: Core 64: Hollow part Applicant
Toyota Motor Corporation 11111M 3vIJ Figure 4 Figure 7 Figure 8

Claims (2)

[Claims] (1) A method for manufacturing a resin hollow part having a hollow part, the product comprising: a core molded using a foamed resin material that can be melted and shrunk by heating to a shape corresponding to the resin hollow part; a core placement step in which the core is placed in the cavity; a resin material molding step in which the resin material to constitute the resin hollow part is filled into the product cavity and molded; and the core is melted and shrunk by heating. A method for manufacturing a resin hollow part, comprising: a hollow part forming step of forming the hollow part by using a hollow part. (2) A claim in which the resin material constituting the resin hollow part emits reaction heat during molding and curing, and the hollow part forming step melts and shrinks the core by the reaction heat. A method for manufacturing a resin hollow part according to item 1.