JPS5824243B2 - Method for manufacturing molded bodies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a molded box such as an inner box with an insulating wall that needs to insulate the inside of a refrigerator from ambient temperature.

More specifically, when a undiluted solution of polyurethane foam, which is a foaming heat insulating material, is injected into the space created between an inner box and an outer box, such as a refrigerator box, using an in-situ foaming method, the foam is foamed.
It is necessary to prevent the synthetic resin inner box from becoming brittle or cracking due to erosion due to freon contained in the foam insulation material.

If the inner box is made of a synthetic resin and is made of a freon-resistant resin plate such as ABS resin, the purpose can be achieved, but the disadvantage is that it becomes expensive.

In the present invention, a thermoplastic film having freon resistance and a softening temperature (melting point) lower than that of a flat material is superimposed on substantially the entire surface of one side of the material, and the film is softened and fused to the material by heating. Then, the inner box is formed by vacuum forming the material surface in correspondence with a male mold made into a predetermined shape.

For this reason, an inexpensive resin such as styrene resin can be used as the flat material without using a freon-resistant resin.

Conventionally, the inner box of a refrigerator made of styrene resin is coated with a vinyl chloride or polyethylene film to make it a freon-resistant material. A two-step covering operation is required, which increases the equipment and workload, which is a major obstacle to reducing costs in mass production.However, in the present invention, the process of heating the inner plate material during vacuum forming improves durability. Since a Freon layer can be formed, such drawbacks are eliminated.

Next, embodiments of the present invention will be described in detail based on the drawings.

1 is a styrene resin plate that is the main body material for the inner box of refrigerators, etc.; 2
is a freon-resistant thermoplastic film superimposed on substantially the entire surface of one side of the styrene resin plate, which has a softening temperature (melting point) lower than that of the styrene resin, and is, for example, a nylon-12 film.

The composite plate 3 in which the styrene resin plate 1 and film 2 are stacked in this manner is attached to a vacuum forming apparatus 4 as shown in FIG.

That is, in the device 4, a male mold 6 having the inner surface shape of the inner box formed on the surface is installed inside the casing 5 on a lifting platform 7, and a clamp is placed over the male mold 6 so as to close the upper opening of the casing 5. The peripheral edges of the plywood plate 3 are supported by the devices 8,8.

In this state, the inside of the casing 5 is in a sealed state. 9 is a heat device located above the overlapping plate 3; 10 is a compressed air inlet for introducing compressed air into the housing 5 from a compressor (not shown).

A large number of air suction holes 12 are formed in the male die 6 to suck air inside the housing 5 through an air suction port 11 to a vacuum device (not shown).

In this manner, with the polymerization plate 3 attached to the vacuum forming device 4, the film 2 faces the heater device 9 and does not face the male mold 6, and the surface of the material 1 corresponds to the male mold 6. .

In the state shown in FIG. 2, the overlapping plate 3 is heated to about 120° C. to 160° C. by the heater device 9.

This heating softens the styrene resin plate 1 and also softens the film 2.

However, since the film 2 has a lower melting point than the styrene resin plate 1, the heating temperature causes the film 2 to melt and adhere to the entire upper surface of the styrene resin plate 1 in a wet state.

Since the styrene resin plate 1 is sufficiently adhered to the film 2 and softened, when the heater device 9 is raised after heating and compressed air is blown from the compressed air inlet 10, the softened polymer plate 3 is transferred to the third layer.
It expands upward as shown in the figure.

This expansion is a step to eliminate significant non-uniformity in the wall thickness of the inner box that will occur when vacuum suction is performed in the next step.

Next, as shown in Fig. 4, the lifting platform 7 is raised to be close to or in contact with the overlapping plate 3, and air is sucked in through the suction port 11 using a vacuum device, so that the overlapping plate 3 is brought into close contact with the surface of the male mold 6, and the inner box is closed. Molded into the inner shape.

Finally, by cooling and stopping suction, the film 2 was fused to the outer surface and an inner box 13 was formed.

The inner box 13 formed in this manner is combined with an outer box 14 made of a steel plate as shown in FIG.

In this combined state, the layer of film 2 is attached to the outer box 14.
On the side, the surface of the styrene resin 1 is exposed in the chamber interior 16.

For this purpose, a raw solution of polyurethane foam is injected into the space between the inner box 13 and the outer box 14 and foamed to fill the space with a heat insulating material 15. The inner box 13 and the outer box 14 are combined by the heat insulating material 15 to form a heat insulating box body 17. .

The present invention is applicable not only to the inner box of a heat-insulating box but also to the inner panel of a heat-insulating door for a heat-insulating box.

That is, it is effective as an inner plate constituting a heat insulating wall.

Although the above embodiment is a method of vacuum forming, the heater device 9
are provided so as to heat both sides of the polymer plate 3, and the heated polymer plate can be combined with a vacuum forming device to form a predetermined shape.

In the present invention, since the inner box or inner panel is molded as described above, the Freon-resistant inner box or inner panel does not require a two-step work as in the past, improving workability and making it suitable for mass production. It is cheaper than an inner box or inner panel made of Freon-resistant resin, and has sufficient strength as a heat-insulating box or door.

Furthermore, since the film layer does not face the male mold during molding, the molten film does not adhere to the male mold, making molding extremely easy.

In the present invention, bending parts such as shelf support grooves and corner parts of the inner box tend to become thinner due to vacuum forming, so by overlapping several films in advance in these parts, the thickness of the fused layer can be reduced. It is also extremely easy to make it large and to sufficiently reinforce the thin portions caused by vacuum forming.

[Brief explanation of the drawing]

Each figure shows an example of the present invention. Figure 1 is a partial view of the inner box material and film laminated board, Figures 2 to 4 are vacuum forming process diagrams, and Figure 5 is a refrigerator. FIG. 6 is an enlarged view of section P in FIG. 5. 1... Inner box body material, 2... Freon resistant, film, 3... Polymer board, 13...
・Inner box, 17... Insulated box body.

Claims (1)

[Claims] 1 A thermoplastic film with freon resistance and a softening temperature (melting point) lower than that of the flat material is superimposed on substantially the entire surface of one of the materials, and the material is heated by a heating device that heats the materials during vacuum forming. The film surface is made to correspond to the material, and the film is softened and fused to the material by heating with the heating device, and the material surface is made to correspond to a male mold having a predetermined shape with an air intake hole communicating with the air intake device, and the material surface is heated by the heating device. A method for producing a molded body, which comprises molding.