JPH0999484A - Mold for styrenic resin foamed container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the wt. irregularity of a molded container in the molding of a styrenic resin foamed container. SOLUTION: In a mold for molding a plurality of styrenic resin foamed containers at the same time by holding styrenic resin foamed sheets passing through a heating furnace to hold them between the male and female molds of a male and female fitted alloy mold, at least the friction coefficient to the styrenic resin foam sheet on the fitting surface of a male piece 5B among a plurality of the male pieces 5B constituting the female mold and a plurality of the female pieces 6B constituting the female mold fitted to the male pieces 5B.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a mold for molding a styrene resin foam container for molding a styrene resin foam container using a styrene resin foam sheet.

[0002]

2. Description of the Related Art Generally, a styrene resin foam container is shown in FIG.
The molding is performed by a molding apparatus shown in FIG. A male / female fitting die 4 provided in this apparatus is composed of a male die 5 and a female die 6 which are vertically movable at upper and lower portions sandwiching a movement path of the styrene resin foam sheet 2, respectively. When the styrene-based resin foam sheet 2 that has passed through the heating furnace 3 moves onto the male mold 5 located below, the female mold 6 and the male mold 5 move toward the side closer to each other. 6 and the male mold 5 are fitted to each other to mold the styrene resin foam container 1, but among the female mold 6 and the male mold 5 that are moving closer to the styrene resin foam sheet 2. After contacting the upper surface of one of the molds, that is, the male mold 5 in the figure, the female mold 6 moves further from the point where the bottom surface of the female mold 6 contacts, and Male mold 5 until fitting is completed
8B because the tensile force F acts on the styrene-based resin foam sheet 2 in the portion corresponding to the bottom of the molded container 1 molded as shown in FIG. As shown, the wall thickness N of the bottom of the molded container 1 after molding becomes smaller than the wall thickness n of the side wall of the molded container 1, and the bottom of the molded container 1 becomes weaker in strength. Also,
When it is desired to print a design, characters, etc. on the outer surface of the side wall portion of the molding container, it is sometimes desired to increase the thickness of the side wall portion so that the side wall portion of the molding container can withstand the printing.

As described above, it is desired to partially increase the thickness of the molded container 1 to be molded, and as a response to this, there is, for example, the one disclosed in Japanese Patent Publication No. 59-19090. This is composed of a plurality of molds provided with a male mold that can expand and contract in the fitting direction and is urged toward the extension side by a spring, and the styrene resin foam sheet is gradually pressed against the mold. By doing so, it is possible to prevent the wall thickness of the bottom portion of the molded container after molding from becoming thinner than the wall thickness of the side wall portion of the molding container, or to increase the wall thickness of the side wall portion.

However, in the above-mentioned male die structure, the die production cost is increased due to an increase in the number of parts required for die production and a complicated internal structure of the die. Moreover, although the male die is divided into a plurality of dies in the fitting direction, the wall thickness of a specific portion of the molding container is changed, for example, to increase the wall thickness of a part of the side wall portion of the molding container to be molded. It was impossible.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, the present invention is to solve the problem that the wall thickness of the molded container to be molded can be partially changed while suppressing the cost increase. There is a point in doing so.

[0006]

In order to solve the above problems, the present invention sandwiches a styrene resin foam sheet that has passed through a heating furnace between male and female molds of male and female fitting molds. Then, in a mold for molding a styrene resin foam container for molding a plurality of styrene resin foam containers at the same time, a plurality of male mold pieces constituting the male mold and the female fitting to these male mold pieces are formed. Since the friction coefficient of at least the fitting surface of the male mold piece among the plurality of female mold pieces constituting the mold with respect to the styrene resin foam sheet is partially different, the styrene resin foam container molding mold is constituted. is there. Therefore, the sliding condition of the styrene resin foam sheet with respect to the mold can be adjusted by changing the value of the friction coefficient.

The coefficient of friction of the portion of the fitting surface of the male mold piece in the molding die of the styrene resin foam container corresponding to the bottom portion of the molding container to be molded with respect to the styrene resin foam sheet is determined by the bottom portion of the molding container. Since the friction coefficient with respect to the styrene-based resin foam sheet in the other parts excluding the part corresponding to is set to be higher than the friction coefficient with respect to the styrene resin foam sheet, for example, as shown in FIG. It is possible to prevent the thickness of the bottom portion of the molded container to be molded from becoming thin, for example, the thickness of the bottom portion of the molding container 1 can be made thicker than the thickness of the side wall portion, although not shown. can do.

The friction coefficient with respect to the styrene resin foam sheet of the portion of the fitting surface of the male mold piece in the molding die of the styrene resin foam container corresponding to the bottom portion of the molding container and the bottom portion of the molding container. It is preferable that the ratio of the friction coefficient to the styrenic resin foam sheet of the other parts excluding the parts is in the range of 1: 0.1 to 1: 0.8.

Squeeze ratio (container height / container diameter) of a molded container obtained by a mold for molding a styrene resin foam container
Particularly good results are obtained when is 0.8 or more.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The styrene resin in the foamed styrene resin sheet or laminated styrene resin foam sheet used in the present invention means polystyrene, rubber-modified polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene-acrylonitrile copolymer. Polymer, styrene-
Examples thereof include homopolymers and copolymers of styrene and its derivatives such as maleic anhydride copolymers. A blend of these resins with a styrene-conjugated diene block copolymer rubber and a hydrogenated product thereof is also applicable.

The styrene resin foam sheet is
It is a foamed sheet obtained by kneading the above-mentioned styrene resin with a foaming agent such as butane or freon by an extruder and then extruding and foaming. Further, the laminated styrene resin foam sheet, the styrene resin foam sheet, the styrene resin, polypropylene, olefin resin such as polyethylene, non-foamed thermoplastic resin film such as polyvinylidene chloride resin on one or both sides. This is a laminated sheet that can be used in the same manner as a styrene resin foam sheet. Here, as a method of laminating and laminating a thermoplastic resin film on a styrene-based resin foam sheet, a method of hanging and laminating a film resin on a styrene-based resin foam sheet, a method of directly laminating a resin film by heat, and There is a method of laminating a resin film via an adhesive or the like. In addition, when it is not necessary to particularly distinguish a styrene-based resin foam sheet and a laminated styrene-based resin foam sheet, both are referred to as a raw sheet.

A method of manufacturing the container 1 from the raw sheet obtained by the above method will be briefly described with reference to FIG.
First, a raw sheet 2 wound in a roll is heated through a heating furnace 3 to be secondarily foamed, and then sandwiched between a male die 5 and a female die 6 of a male / female fitting die 4 and at the same time. 26 per shot
The individual container body 7 is molded. During this molding, the inside of the male and female fitting mold 4 is depressurized by the vacuum exhaust means 8 to enhance the transferability of the mold shape. After this container body 7 is molded, it is punched from the raw sheet 2 with an automatic punching machine 9 equipped with a punching blade, a Thomson blade, or the like, leaving a mouth 11 protruding outward around the opening 10 of the container body 7. , Individual containers 1. Here, as shown in FIG. 5, the male die 5 is composed of 26 male die pieces 5B ...
Are composed of 26 female mold pieces 6B, ... Fitting to the 26 male mold pieces 5B. The male mold 5 and the female mold 6 are provided so as to be movable up and down, respectively, and both molds 5 and 5 are driven by a separately provided driving device S such as a hydraulic cylinder.
6 is fitted to form the container body 7, and the container body 7
After the molding, the two dies 5 and 6 can be switched to a separated state. The male piece 5B ... And the female piece 6B
The number of ··· is not limited to 26, but may be any number of 2 or more.

In addition to the zigzag arrangement shown in FIG. 5, the male mold pieces 5B are arranged in a zigzag pattern in which the male mold pieces in the rear row overlap with the male mold pieces in the front row when viewed from the traveling direction P of the original sheet 2. They may be arranged, but the arrangement of the male pieces 5B is not limited to these.

When the original sheet 2 is positioned on the male piece 5B by a chain electric device (not shown), as shown in FIG. 4 (a), the drive devices S and S are operated to drive the male piece. 5
B and the female die 6B are moved closer to each other. Then, after contacting the upper surface of the male mold piece 5B that has risen to the original sheet 2, the male mold piece 5B and the female mold piece 6B are further approached from the point where the bottom surface of the female mold piece 6B that has descended contacts. Move it to Figure 4 (C).
During the period until the fitting of the molds 5 and 6 shown in Fig. 4 is completed,
As shown in (b), the original sheet 2 of the fitting surface of the male mold piece 5B corresponding to the bottom of the molded container 1 to be molded.
The pulling force F acts on. Therefore, FIG.
As shown in (b), the wall thickness N of the bottom of the molded container 1 after molding is smaller than the wall thickness n of the side wall of the molded container 1. Therefore, in the present invention, the friction coefficient of the fitting surface of the male mold piece 5B with respect to the original sheet 2 and the female mold piece 6B.
The coefficient of friction of the mating surface with respect to the original sheet 2 is partially different so that the thickness of the molded container 1 to be molded can be partially changed and adjusted.

Specifically, as shown in FIGS. 2 and 3,
A part 5G of the fitting surface of the male mold piece 5B corresponding to the bottom of the molded container 1 to be molded and a part 5H corresponding to the bottom end of the side wall of the molded container 1 to be molded. , Sandblasting is performed to determine the coefficient of friction of the portion corresponding to the bottom of the molding container 1 with respect to the original sheet 2 by the male mold piece 5B.
0.8 higher than the friction coefficient of other parts
And slide the lower surface of the original sheet 2 which is in contact with the upper surface of the male mold piece 5B until the fitting of the molds 5 and 6 shown in FIG. 4B is completed. This makes it difficult for the original sheet 2 located on the upper surface of the male mold piece 5B to move downward, and the mouth of the molded container 1 to be molded on the fitting surface of the female mold piece 6B. That is, the opening edge 6G and the portion 6H corresponding to the opening edge side end portion of the side wall portion of the molded container 1 to be formed are subjected to Teflon processing so that the friction coefficient with respect to the raw sheet 2 is about 0.2, The upper surface of the original sheet 2 located below the opening edge 6G and the portion 6H can be made slippery easily, and the original sheet 2 located on the lower surface of the female die 6B can be easily moved in the horizontal direction. And the sandblasted male piece 5B and the Teflon coating By fitting molded in the female piece 6B that, it is possible to thicken the bottom of the molded container 1. When a molded container having a drawing ratio of 0.8 (container height / container diameter) was molded using the mold configured as described above, the following wall thickness distribution of each molded container was obtained.

That is, as compared with the case of using a mold in which the coefficient of friction with respect to the original sheet 2 is set to about 0.4 at any part, the mold of which the friction coefficient is about 0.4 of the mold of the present invention The results were obtained with a wall thickness K of 2.4 mm, 2.2 mm and a bottom wall thickness of N 1.8 mm 2.1 mm. Therefore, the wall thickness of the molding container could be made substantially uniform at any part.

The mold was sandblasted or Teflon processed in order to make the coefficient of friction different from the original sheet 2. However, aluminum powder was vapor-deposited on the mold, or a plurality of types were fitted to the fitting surface of the mold. Mirror finishing or the like, as shown in FIG. 6, in order to change the contact area with the original sheet 2, a fine projection T such as crystal deposition is attached to the surface of the male mold piece 5B of the mold, As shown in FIG. 7, a large number of grooves M may be cut on the surface of the male mold piece 5B of the mold, or knurling and rib standing may be performed at different pitches for each part of the mold. The coefficient of friction with respect to the original sheet 2 may be changed in combination, and the specific configuration for making the coefficient of friction different is not limited to these.

[0018]

According to the mold for molding a styrene resin foam container of the present invention as described above, the friction coefficient of the fitting surface of the male mold piece with respect to the styrene resin foam sheet is only partially changed, The wall thickness of only a specific part of the molded container to be molded can be changed and adjusted to a desired thickness, and the bottom part of the molded container to be molded can be thickened to increase the strength of the bottom part or the wall part of the molded container. It has been possible to increase the thickness and form a side wall portion that can withstand printing, while suppressing an increase in cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a container manufacturing apparatus.

FIG. 2 is a partially cutaway perspective view of a male piece.

FIG. 3 is a partially cutaway perspective view of a male piece and a female piece.

FIG. 4 is a schematic cross-sectional view showing a part of the container manufacturing process.

FIG. 5 is a schematic plan view of a male piece.

FIG. 6 is a perspective view showing a main part of a male piece.

FIG. 7 is a perspective view showing a main part of a male mold piece.

FIG. 8 is a vertical sectional view showing a comparative example of a container.

[Explanation of symbols]

1 container 2 original sheet (styrene resin foam sheet) 3 heating furnace 4 male / female fitting mold 5 male mold 5A base 5B male mold 5G part 5H part 6 female mold 6A base 6B female mold 7 container body 8 Vacuum evacuation means 9 Automatic punching machine 10 Opening 11 Mouth F Pulling force K Thickness M Groove N Groove thickness n Thickness S Drive device T Projection

Claims (4)

[Claims] 1. A styrene resin foam sheet that has passed through a heating furnace is sandwiched between male and female dies of male and female fitting dies,
In a mold for molding a styrene resin foam container for simultaneously molding a plurality of styrene resin foam containers, a plurality of male mold pieces constituting the male mold and the female mold fitted to these male mold pieces A mold for molding a styrene-based resin foam container in which a friction coefficient of at least a fitting surface of a male mold piece among the plurality of female mold pieces with respect to the styrene-based resin foam sheet is partially different. 2. The coefficient of friction with respect to the styrene resin foam sheet of a portion of the fitting surface of the male mold piece in the molding die of the styrene resin foam container corresponding to the bottom of the molding container to be molded is defined as the friction coefficient of the molding container. The mold for molding a styrene-based resin foam container according to claim 1, wherein a coefficient of friction with respect to the styrene-based resin foam sheet in a region other than the region corresponding to the bottom of the styrene resin foam is higher. 3. A friction coefficient with respect to the styrene resin foam sheet at a portion corresponding to the bottom portion of the molding container in the fitting surface of the male mold in the molding die of the styrene resin foam container and the bottom portion of the molding container. The molding of a styrene-based resin foam container according to claim 2, wherein the ratio of the friction coefficient to the styrene-based resin foam sheet of the other parts excluding the corresponding part is in the range of 1: 0.1 to 1: 0.8. Mold. 4. The styrene-based resin foam container according to claim 2, wherein the molded container obtained by the molding die for the styrene-based resin foam container has a drawing ratio (container height / container diameter) of 0.8 or more. Mold for.