JPS61242814A - Molding method for plastic molded article - Google Patents

Abstract

PURPOSE:To enable to mold a molded article in a complicated form by an inexpensive mold, by a method wherein a material is stuck to a male mold, a split female mold is abutted against the outside of the material from the outside, a heat-shrinkable tape is wound round the external circumference of the split female mold further and molded into a preset form through heating. CONSTITUTION:Mold processing of a molded article is performed by making use of about a flat platelike material 8 having heat-curing properties or heat- fusing properties and having flexibility. After a material 8 has been stuck to a male mold 7, a split female molds 9, 10, 11 are abutted against the outside of the material 8 and after a heat-shrinkable tape 12 has been wound round the external circumference of the split female molds 9, 10, 11, the material 8 is made to mold into a predetermined form. The female mold can be made into split type one and the molded article in a complicated form can be molded easily by making use of the heat-shrinkable tape. As the titled method can be made one wherein heating is performed in the heating chamber, cost of the mold becomes low and a molded article can be offered at low cost.

Description

[Detailed description of the invention] [Technical field to which the invention belongs] The present invention relates to a method for molding plastic molded articles.

[Prior art]

When molding a molded product by heating and pressurizing it in a mold using a flexible heat-curable or heat-meltable material (hereinafter referred to as the "material"), the shape of the molded product may be an undercut shape, etc. When the shape is complicated, for example, a mold consisting of an upper mold 3, a lower mold 4, a side mold 5, a side mold sliding cylinder 6, and a core male mold 7 is generally used, as shown in Fig. 4. The mold is heated by passing heated steam through the mold. However, when the shape becomes a more complicated undercut shape or when the required number of molded products is small, the mold manufacturing cost becomes extremely high (and -
The drawback is that the depreciation cost per piece is naturally higher.

[Problem that the invention seeks to solve]

The present invention has been made in view of the above-mentioned drawbacks, and uses a tape that shrinks when heated and has a strong shrinkage force (hereinafter referred to as heat-shrinkable tape) to provide molded products with complex shapes at low cost using inexpensive molds. The purpose is to protect children.

[Means for solving problems]

The structure of the present invention for achieving the above object will be explained using FIG. 1 to FIG. 3 corresponding to the embodiment. In a method of molding a molded product using a flat element (8), after pasting the material (8) on a male mold (7), split female molds (9), (10), ( 11) on the outer surface of the material (8), and then split female molds (9) and (1
0), (11) and then heat the material (8) to shape it into a predetermined shape.

That is, after laminating and pasting the number of materials on the male mold surface so that the wall thickness after molding is the designed wall thickness, a split female mold is brought into contact from the outside, and heat shrink tape is applied around the outer periphery of the split female mold. Wrap it as many times as necessary to obtain the required amount of contraction and force.
Then, secure the ends of the heat shrink tape with heat-resistant adhesive tape to prevent them from loosening.

After wrapping with heat shrink tape as above, place it in the heating chamber (
(approximately 100-180℃). By heating in a heating chamber, the material softens and the heat-shrinkable tape contracts, pressurizing the material and molding the material into a predetermined shape.

〔Example〕

An embodiment of the present invention will be described using FIGS. 1 to 3.

Molding material made by impregnating reinforcing carbon fiber with thermosetting resin (
This is an example of a case where a cylindrical molded product is obtained using CF prepreg (hereinafter referred to as CF prepreg).

After laminating and pasting the required number of CF prepregs 8 on the core male mold 7, split female mold 9, split female mold 10, split female mold 11
are brought into contact with each other from the outside, and a heat-shrinkable tape 12 is further wrapped around the outer periphery to obtain the necessary shrinkage amount and necessary shrinkage force, and the ends are fixed with a heat-resistant adhesive tape 13 so as not to loosen.

As mentioned above, after setting the CF prepreg 8, heat shrink tape 12, etc. in the mold, place the CF prepreg 8, heat shrink tape 12, etc.
(about 0℃). When heated in the heating chamber, the thermosetting resin component of the CF prepreg 8 temporarily lowers its viscosity and becomes fluid. At this time, the heat-shrinkable tape 12 is also heated and contracts, and the split female mold is tightened from the outer periphery and moved to the fitting position as shown in FIG. 2 while pressurizing the CF prepreg 8. In this state, the temperature is maintained at a high temperature until the thermosetting resin component of the CF prepreg 8 is cured. After the curing is completed, it is removed from the heating chamber and slowly cooled.

After cooling is completed, the heat shrink tape 12 is cut, the split female mold is removed, and the core male mold 7 is extracted.

In this case, the thermal expansion coefficient of the core male mold 7 is the CF prepreg 8
If the coefficient of thermal expansion is larger than that of the molded product, the core male mold 7 does not need a draft angle, but in the opposite case, it is necessary to provide a draft angle. In addition, if the core male mold 7 has an undercut part, a thermosetting resin can be used by using a low melting point material such as an alloy or thermoplastic resin whose melting point is slightly higher than the curing temperature of the thermosetting resin of the CF prepreg 8. After curing for a few minutes, the temperature is raised to the melting point to melt the core male mold 7 and take it out.

In the case of this example, since it is desired to clamp the mold in the H7 dimension direction first, the H7 dimension is made larger than the H1 dimension, and the heat shrink tape 1 is
It is designed so that it can be moved to a large position.

If the heating chamber is a vacuum heating chamber, air bubbles in the CF prepreg 8 will be removed when the resin is softened, making it possible to obtain a highly reliable molded product free of air bubbles.

〔effect〕

Since the present invention has the above configuration, it has the following effects.

1) By using heat-shrinkable tape, the female mold can be divided into parts, and molded products with complex shapes (for example, undercut shapes) can be easily molded.

2) Since it can be configured by a combination of a core male mold and a split female mold, and can be heated in a heating chamber, mold manufacturing costs can be reduced and molded products can be provided at low prices.

3) Since the winding height and winding thickness of the heat-shrinkable tape can be selected arbitrarily, the winding method of the heat-shrinkable tape can be selected to correspond to the direction in which fast mold clamping is desired or the direction in which a strong mold clamping force is required.

4) By using a vacuum heating chamber as the heating chamber, a highly reliable molded product without bubbles can be obtained.

[Brief explanation of drawings]

Fig. 1 is a side view showing an embodiment of the present invention, Fig. 2 is a sectional view taken along line AA in Fig. 1, Fig. 3 is a sectional view after heating in Fig. 2, and Fig. 4 is a conventional embodiment. This is a cross section showing. Explanation of symbols■...Press upper plate 2...Press lower plate 3...
・Top mold 4...Bottom mold 5...Side mold
6...Syria for side type slide...Core male type
Nender 8... CF prepreg 9... Split female mold 10.
...Divided female mold 11...Divided female mold summary 2 diagram
Figure 3 Figure 4

Claims (1)

[Claims] 1. In a method of molding a molded product using a flexible heat-setting or heat-melting material in the form of a substantially flat plate, after the material is attached to a male mold, A method for molding a plastic molded article, which comprises applying a split female mold to the outer surface of the material, wrapping a heat-shrinkable tape around the outer periphery of the split female mold, and then heating the material to mold the material into a predetermined shape. 2. The method for molding a plastic molded article according to claim 1, wherein the male mold is made of a low melting point material. 3. The method for molding a plastic molded article according to claim 1, wherein the heating is performed in a vacuum heating chamber.