JPS6246425B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an inexpensive, easy-to-open lid, and more particularly to a method of manufacturing a lid by partial pressure vacuum forming.

Conventionally, many thermoplastic synthetic resin molded products have been produced by air pressure forming methods such as vacuum forming, since vacuum forming methods have the advantage of being mass-produced at relatively low cost.

That is, in the vacuum forming method, as shown in FIG. 1, a film-like sheet 12 is placed on top of a female mold 10, and the sheet 12 is placed inside the mold 10 by reducing the pressure in the inner cavity of the mold 10. The sheet 12 is drawn into a desired shape according to the shape of the mold 10. Note that there are cases in which the pressure is applied above the sheet 12 while reducing the pressure in the mold cavity.

In forming by this vacuum forming method, as shown in FIG. Since it is only curved, the thickness is approximately equal to the thickness of the portion close to the convex portion 11. In other words, in vacuum forming products, unless deep drawing is used, the wall thickness of many parts of the product will be approximately the same, making it difficult to make the dimensional accuracy of a desired part of the product different from other parts. It was hot.

As described above, molded products produced using conventional vacuum forming methods etc. have the disadvantage of low dimensional accuracy. As for the body,
Since the thickness of the weakened line is extremely thin, high dimensional accuracy is required in some parts to form the opening, and molded products with parts with high dimensional accuracy are almost always manufactured using injection molding. I had to take it.
However, when using the injection molding method, expensive equipment and molds are used, and in order to improve the flow of the molten plastic, the wall must be relatively thick, resulting in a high manufacturing cost. It was hot.

The present invention eliminates these drawbacks and provides a method for manufacturing an easy-to-open lid that requires high dimensional accuracy in part at a low cost, as described below.

As shown in FIG. 2, the thermoplastic synthetic resin sheet 12 is clamped onto a female mold 13 and heated, and a negative pressure is applied to the inner cavity 15 of the female mold 13 to form a molded product along the inside of the female mold 13. 16, the clamping body 18 is immediately lowered as shown in FIG.
The film 17 on 4 is pinched, and the film 1
This is a method in which the thickness of a part of the molded product is set to a desired thinness, thereby making only that part of the molded product thinner than other parts and finished with the desired dimensional accuracy.

In the embodiment shown in FIGS. 2 and 3, a protrusion 14 is provided in the inner cavity 15 of the female mold 13, and the film 17 is held with the protrusion 14 and the lower surface of the clamping body 18 that is lowered. Although the thickness of the molded product at that portion is made thinner as desired, the present invention is not limited to this embodiment. female type 13
Of course, there are cases in which a desired part of the molded product immediately after being suctioned into the female mold 13 and molded is subjected to clamping pressure, thereby forming a part of the molded product into a desired shape with a thinner wall. It is. That is, an annular protrusion 19 having an oval shape as shown in FIG. 4 is provided on the lower surface of the clamping body 18, and as soon as negative pressure is applied in the female mold 13 to mold the lid body 20, the clamping body 18 is immediately removed. However, the lid body 2
0, the top plate 21 is compressed, thereby forming an annular thin wall portion 23 on the top plate 21 as shown in FIG.

After the container is sealed with the lid 20 formed in this manner, when the container is to be opened, the container can be easily opened by breaking the thin wall portion 23.

As described above, in the present invention, after heating the thin sheet 12 made of thermoplastic synthetic resin to a required temperature and placing the sheet 12 along the inside of the female mold 13 with gas pressure,
Easy-to-open lid body 2 characterized in that a desired part is compressed using both the inside of the female mold 13 and a clamping body 18 while it is still in a heated state to make the part extremely thin.
0 manufacturing method, the lid body 20 can be easily formed in the same manner as the conventional vacuum forming method, and ultra-thin parts can be easily formed in required parts simply by pressing the clamping body 18. Lid body 20 that can
This is a manufacturing method that does not require expensive equipment or expensive molds as in the case of injection molding, and it is also easy to make a large number of pieces, making it possible to easily open the lid at a low cost. There is an advantage that 20 pieces can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a normal vacuum-formed product, FIGS. 2 and 3 are cross-sectional views showing the manufacturing procedure of the lid according to the present invention, FIG. 4 is a bottom view of the clamping body, and FIG. The figure is a sectional view of a lid according to the present invention. 10...Mold, 11...Protrusion in the mold, 1
2... sheet, 13... female mold, 14... protrusion in female mold, 15... lumen of female mold, 16... molded product,
17...Film on the protrusion, 18...Pressing body,
19... Protrusion on the lower surface of the clamping body, 20... Lid, 2
1...Top plate, 23...Thin section.

Claims (1)

[Claims] 1. After heating a thin sheet made of thermoplastic synthetic resin to a desired temperature and aligning it along the inside of the mold with gas pressure, while still in the heated state, hold both the inside of the female mold and the clamping body to the required temperature. A method for producing an easy-to-open lid, characterized by compressing a portion and making the portion extremely thin.