JPS5872408A - Preparation of synthetic resin formed article - Google Patents

Abstract

PURPOSE:To obtain a molded part in low cost without performing complicated processing to a mold by a method wherein a place corresponding to an undercut section of a molding part is molded as a protrusion by a fluororesin layer of suitable thickness and an undercut section is molded in this part. CONSTITUTION:On a male force 1, the edge 10 between the upper surface and and side wall and the edge 11 between the side walls form small radi and both sides of those edges 10, 11 are coated to form a fluororesin layer 3 of suitable width. The fluororesin layer 3 is formed by attaching fluororesin tape to the surface of the force 1. However, the force 1 may be coated directly with fluororesin. Necessary deformation and bulge forming are given by vacuum forming etc. to synthetic resin sheet 4 between a male force 1 and a female force 2 to form a formed part. In a place of the formed part corresponding to the bulge part 3 on the upper side wall of the male force 1, the side wall of the formed part is caved inside to make an undercut part (a).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a synthetic resin molded article, and aims to provide a method that can easily and inexpensively manufacture a molded article having a relatively small undercut portion.

Conventionally, in sheet forming such as vacuum forming, pressure forming, or press forming, in which a synthetic resin sheet is bulged according to a mold, when an attempt is made to form an undercut part in a molded product, it is difficult to form an undercut in the mold after molding. Since punching becomes difficult, the design of the mold, such as the use of split molds, becomes extremely troublesome, and the manufacturing cost becomes high. In particular, in the case of a relatively small amount of undercut, the use of the above-mentioned split mold increases the molding cost, so the shape of the molded product is often changed so that there is no undercut, and the function of the molded product is This sometimes caused inconvenience and decreased performance.

Therefore, the present invention provides a method that allows the undercut portion of a molded product to be formed using a normal mold without using a complicated device such as a split mold, and that also facilitates molding operations such as cutting the molded product. The method is as follows:
In the sheet molding mold, a portion corresponding to the undercut portion of the molded product is formed with a fluororesin layer of an appropriate thickness to protrude, and during sheet molding, the undercut portion of the molded product is formed at the blooming portion. It is characterized by molding.

Next, embodiments of the present invention will be illustrated below with reference to the drawings.

The figure shows the case where a box-shaped packaging container is manufactured as a molded product. (1) is the male mold of the molding mold, (!) is the female mold, and the female mold (! This is a mold for vacuum forming, which is provided by a member of staff.

Of the male molds (11), the ridge line between the top surface and the side wall surface and the ridge line (b) between the side wall surfaces form a relatively small radius. A fluororesin layer (3) is formed in the width.

The fluororesin layer (3) is formed by attaching a fluororesin tape to the mold (llii), but it is also possible to directly coat the gold II (11) with the fluororesin.In either case, the fluororesin layer (3) is formed to have a relatively thick thickness, and in particular, the upper side wall surface of the male II (11) protrudes slightly outward (see Fig. 1).

A synthetic resin sheet (4) is molded using the mold (1) as described above.

In the case of the figure, the synthetic resin sheet (4) is a foamed polystyrene cape foam sheet laminated with a non-foamed film (b), but other types of synthetic resins used for normal sheet molding are used. Single layer or laminated sheets can be used.

The molding process is carried out in exactly the same manner as before, and the synthetic resin sheet (4) is sandwiched between a male mold (11) and a female mold (11) and subjected to the necessary deformation and swelling process by vacuum forming etc. to form a molded product (
2) (see Figure 2).・Of the molded product (to), the part corresponding to the fluororesin layer (3) of the male mold (11) is slightly old, especially in the part corresponding to the protruding member on the upper side wall surface of the male mold (1). Since the side wall of the molded product is recessed inward, it becomes a so-called undercut portion (-).

Therefore, in the die-cutting process after molding, when the molded article (1111) is extracted from the male (1111), the elasticity of the synthetic resin sheet (4) and the fluorine The molded product is extracted by using the slipperiness of the resin layer (3) ◎ The molded product (G) manufactured in this way has four connecting edges on the four side walls and the bottom of the box-shaped packaging container. Near the corner where (Q is shallow and four people are formed,
When storing angular storage items (8), the corners do not directly hit the corners (Q) of the container, so they can be held with good cushioning properties on the sides or bottom of the storage items, preventing damage to the packaging container and storage items due to corners hitting. It is effective to prevent

According to the above manufacturing method, each ridgeline (gull) of the male mold 111 is
Even if the radius of b) is small, the fluororesin layer (3) formed on both sides of the ridgeline +1 (1αυ) can improve the slippage of the synthetic resin sheet (4) during molding, resulting in improved moldability. The packaging container that becomes the molded product (6) can have a very small radius at each corner of the inner surface, which is more convenient for effective use of the internal volume or for storing the angular storage items (see FIG. 4).

Note that the shape inside the molded product is not limited to the above examples, and can be implemented in various ways, and can be applied to various known molded products as long as a relatively shallow undercut is required in a part of the molded product. can.

Then, the shape of the undercut part or the molded product IAK
The formation position of the undercut part is the mold 11)
It can be easily changed by changing the shape and arrangement of the fluororesin layer (3) to be formed, and can be designed freely depending on the functional design of the molded product (6).

In addition, when forming the fluororesin layer (3) on the male mold (11), there are two methods: directly forming it on the flat part of the male mold (1), and forming a relatively small protrusion in advance on the male mold (1). There is a method of forming a tifK thin fluororesin layer (3) on the surface of this protrusion, but if a relatively small undercut is sufficient, the former method using only the fluororesin layer (11) is sufficient.

Furthermore, in the illustrated example, a protrusion (to) of the fluororesin layer (3) is formed only in the male die 11+ of the mold, and an undercut part (a) is manufactured only on the inward side of the molded product. However, depending on the structure of the molded product, it is also possible to form a protrusion of the fluororesin layer (3) on the outer side of the molded product, for example, to form an undercut portion on the outer surface of the molded product. According to the method of the present invention configured as described above, when an undercut portion is formed in a synthetic resin molded product, a protruding portion of the fluororesin layer is placed at a predetermined portion of the mold corresponding to the undercut portion. is formed in advance, and an undercut part is formed in the molded product using the protruding parts of this fluorine lN resin layer. Therefore, with the method of the present invention, it is difficult to cut out the undercut part, which is difficult to do with ordinary molds. Due to the properties of the fluororesin layer (3), which has very good sliding properties, the molded product (6) can be easily cut out beyond the above-mentioned protruding portions.

The fluororesin layer (3) can be easily formed by pasting fluororesin tape or directly coating it, so there is no need to perform any complicated processing on the mold itself, and there is no need to use a split mold. Therefore, the effect of reducing equipment costs and manufacturing costs is significant.

As mentioned above, it is an excellent manufacturing method that can easily form undercuts on synthetic resin molded products and can greatly contribute to improving the function or design of these molded products.

[Brief explanation of the drawing]

The figures illustrate embodiments of the present invention; the second figure is a partially cutaway perspective view of the mold, the second figure is a partially enlarged sectional view showing the molding process, and the eighth figure is a part of the molded product. Cutaway perspective view, 4th
The figure is an enlarged sectional IfN diagram of the main part showing the usage state of the molded product. 111...Male mold, (ri...Female mold, (3)...Fluororesin layer, (1)...Protruding portion, (4)...Synthetic resin sheet, ^...Molded product % (excitation... undercut part. Patent applicant Sekisui Plastics Co., Ltd. Figure 1 43 Figure 3 Figure 4

Claims (1)

[Claims] 1. A fluororesin layer of an appropriate thickness is formed to protrude at a portion of the sheet molding mold corresponding to the undercut portion of the molded product, and when sheet molding is performed, A method for producing a synthetic resin molded product, comprising forming an undercut portion of the molded product at an exit portion. 1. The method for manufacturing a synthetic resin molded product according to claim 1, wherein the fluororesin layer is formed by adhering a fluororesin tape; The method 08, wherein the fluororesin layer is formed by fluororesin coating A method for producing a synthetic resin molded article as described in Claim No. 1.