JP2000052412A - Manufacture of flat container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of wall-thinning of a corner of a container by disposing a parison in a mold in the state that a lower end of the parison is closed, supporting air amount is regulated and the parison is locally enlarged, and then blow molding the parison. SOLUTION: For example, a mold 2 is a structure in which a cutting blade 21 is provided at an edge of a cavity 22. An enlarged part 11 is formed at the parison 1 by supporting air. The parison 1 is disposed in the mold 2 so that the part 11 becomes a sidewall, and a parison 11a extended from the cavity 22 is cut in the case of mating an upper mold and a lower mold of the mold 2. Thereafter, when the parison is blow molded in this state, the parison is thin-walled, and expansion of the parison is proceeded. Then, when the parison is brought into contact with an inner wall of the cavity, the expansion of the parison is stopped. Accordingly, a part IC corresponding to a corner of the parison is suppressed in wall-thinning more in the smaller degree of the expansion. At the time of cutting, a discontinuous surface 1R is formed as a rib at a sidewall of the container to prevent a deformation of the container.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a flat container used for sealing foodstuffs, medical drugs and the like. More specifically, the present invention relates to a method for manufacturing a flat container, which can prevent a wall thickness of a container, for example, a corner portion of an infusion bag, from being reduced.

[0002]

2. Description of the Related Art Conventionally, flat containers have been widely used for infusions and the like, but most of them are manufactured by blow molding. That is, it is manufactured by a method in which a parison is driven into a molding die, a blow pin is inserted into an opening of the parison, and blow molding is performed.

[0003]

However, in the case of the flat container manufactured by such a manufacturing method, the parison part which moves to the corner part of the container is greatly stretched at the time of blowing, and the degree of expansion also moves to other parts. Since the shape of the container was larger than that of the container, the corner portion of the molded container tended to be thin. FIG. 6 is a schematic view showing a main part of a conventional flat container manufacturing method. In FIG. 6, 2 is a mold, 22 is a cavity, 3 is a parison, 3
C indicates a portion corresponding to the corner of the parison. As shown by the arrow in FIG. 6, the part 3C corresponding to the corner of the parison is the cavity 2 during blow molding.
Since the inside of the container is greatly stretched, the corner of the manufactured container is most likely to be thinned.

[0004] The thinning of the corner portion of the container may cause the strength of the container itself to be impaired.
In other words, the drop strength is weak, which may cause damage due to falling, damage due to static load of the stack when stocking the product, and decrease in strength during heat sterilization. Therefore, there is room for improvement in reducing the thickness of the corner portion, which may cause such a problem.

It is an object of the present invention to provide a method for manufacturing a flat container which can prevent the corner portion of the container from being thinned.

[0006]

As a result of repeated investigations to solve the above problems, the present inventor has completed the present invention by devising the shape of the parison corresponding to the corner of the container. It is. The present invention arranges the parison locally enlarged by the support air in a state where the lower end is closed, the enlarged part of the parison is arranged in the molding die in a state where the enlarged part protrudes from the cavity of the molding die,
The gist of the invention is a method for producing a flat container, which is characterized by blow molding.

The present invention is directed to a flattening method in which a parison is locally enlarged by adjusting the amount of support air by closing the lower end of the parison, and the parison is arranged in a molding die and then shaped into a container by blow molding. This is a method for manufacturing a container. According to the manufacturing method of the present invention, the degree of expansion of the parison at the time of molding can be suppressed to a small degree. Is maintained to some extent.

[0008] The support air is used to maintain the shape of the parison in the conventional blow molding, but in the present invention, the amount is increased, and the molding is started in a state where the parison is enlarged. I just need.

A second aspect of the present invention is to dispose a parison in a molding die provided with a cutting blade at the edge of the cavity, adjust the molding die so as to cut the parison protruding from the inside of the cavity, and then perform blow molding. The gist of the present invention is a method of manufacturing a flat container according to claim 1.

[0010] In the present invention, using a molding die provided with a cutting blade at the edge of the cavity (hereinafter may be abbreviated as a bladed molding die), a portion where the parison locally enlarged is protruded. Are arranged so as to be cut and molded. Since the cut parison is in a molten state, if the cut surfaces come in contact with each other, they are easily joined. According to the present invention, in addition to the above-described prevention of the thinning of the container corner portion, such an excess protruding portion serving as the container side wall portion is cut by a mold with a blade, and the parison end swells during blow molding, so-called. Meat puddles can be prevented.

Further, by cutting the end of the parison, the end of the container becomes a discontinuous so-called rib state, and as a result, the shape of the container is maintained. Specifically, when a container filled with the content liquid is suspended during use,
When the side wall is drawn inward by the weight of the content liquid, the container is deformed, and a so-called downward swelling state is obtained. However, in the container manufactured by the manufacturing method of the present invention, since the above-described rib is formed on the side wall portion, the rib prevents the deformation of the side wall, so that the container does not deform and the shape maintaining effect is exhibited. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view for explaining a main part of a method for manufacturing a flat container according to the present invention. In FIG. 1, 1 indicates a parison, and 2 indicates a mold. Mold 2
It has a structure in which a cutting blade is provided at the edge of the cavity. The parison 1 has an enlarged portion 11 formed by the support air. The enlarged portion 11 is arranged in the mold 2 so that the enlarged portion 11 serves as a side wall. When the molds are combined, the parison protruding portion 11a is cut. Thereafter, when blow molding is performed in this state, the parison becomes thinner and the parison expands further. When the parison comes into contact with the inner wall of the cavity, the parison stops expanding. Therefore, as the degree of expansion of the portion 1C corresponding to the corner portion of the parison is smaller, the thinning is suppressed.

Here, when the degree of expansion of the parison 1 used in the present invention and the parison 3 used in the conventional manufacturing method shown by the broken line is compared with the degree of expansion to the corner, it is apparent that the parison corner used in the present invention is clear. The degree of expansion of 1C is smaller than that of the parison corner 3C used in the conventional manufacturing method, so that the wall thickness can be prevented.

FIG. 2 is a schematic view showing a cross-sectional view of FIG. 1 taken along the line XX. The molding die 2 is provided with a cutting blade 21 at the edge of the cavity 22 so that the parison 11a protruding from the cavity 22 can be cut when the upper die and the lower die are aligned. Further, at the time of cutting, a discontinuous surface 1R formed by joining the upper parison 1u and the lower end parison 11 is formed as a rib on the side wall of the container. In addition, the excess parison 11a is cut, so that bulging of the end of the parison during blow molding, that is, the so-called meat puddle can be prevented. The shape of the cutting blade 21 is not particularly limited, but it is preferable that the protruding parison can be completely cut by adjusting the mold.

As shown in FIG. 3, the parison used in the present invention is manufactured by locally enlarging it by blowing support air with its lower end closed. The resin used is not particularly limited. The method of closing the lower end of the parison is not particularly limited, but a pinch is used in the present embodiment. In FIG. 3, 1 is a parison, 4 is a parison extruder, and 5 is a pinch. Parison 1 extruded from parison extruder 4
Is closed at the lower end by a pinch 5, and the parison is made into a locally enlarged shape by blowing support air from a parison extruder. The shape and the degree of enlargement are not particularly limited. However, in the case of a lantern type, the degree of expansion of the parison with respect to each of the four corners is substantially equal, and it is easy to prevent thinning as a whole. If the shape is enlarged such that it protrudes from the side wall of the mold, a rib can be formed at the time of molding, and a container that can prevent deformation during use can be manufactured.

FIG. 4 is a schematic view showing a cross section of a parison whose area is enlarged. The enlarged parison 1 is shown in FIG.
As shown in the figure, the thickness of the enlarged portion 11 is
It is often thinner than the part. Therefore, when blow molding is performed using the parison 1, the difference in wall thickness between the container corner and the side wall is often kept small.

The parison 1 is placed in the mold 2.
At this time, whether or not to remove the used pinch may be arbitrarily set depending on the shape of the molding die, the presence or absence of the cutting blade, and the like. Further, the shape of the parison used and the degree of enlargement are not particularly limited as described above, and there is no particular problem as long as the parison is locally enlarged. Depending on the shape of the parison used, the parison may be arranged such that the protruding portion is provided only on the side wall as shown in FIG. 1 or may be arranged so as to protrude over the entire container. However,
It is necessary to use a bladed mold with a blade on the edge to cut the parison protruding from the cavity. It should be noted that there is no particular problem if the parison 1 is arranged so as to completely fit in the cavity of the mold, but in this case, the rib is not formed because the mold is not cut by the blade-equipped mold, and the shape maintaining effect is not obtained. Cannot be demonstrated.

Next, after the parison is arranged, the molds are combined, and the excess parison is cut, followed by blow molding to form a container. FIG. 5 shows an example of a flat container manufactured by the manufacturing method according to the present invention. In FIG. 5, reference numeral 4 denotes a container, and 4R denotes a rib. Since the flat container 4 is formed by cutting a parison corresponding to a part of the side wall, the rib portion 4 serving as a discontinuous surface is formed on the side wall.
R is formed.

Therefore, when the container is suspended in a state of being filled with the content liquid at the time of use, the rib portion 4R prevents the side wall of the container from being deformed, so that the shape of the container is hardly deformed.

[0020]

According to the method for manufacturing a flat container of the present invention, the parison locally enlarged by the support air with the lower end closed is formed in a state where the enlarged portion of the parison protrudes from the cavity of the mold. Since the gist is arranged in a mold and blow molded, the thickness of the container can be prevented from being reduced in thickness at the corner, and the rib is formed on the side wall of the container, thereby preventing deformation of the container. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating a main part of a method for manufacturing a flat container according to the present invention.

FIG. 2 is a schematic view showing a cross-sectional view taken along line XX of FIG.

FIG. 3 is a schematic view showing a manufacturing process of a parison used in the present invention.

FIG. 4 is a schematic view showing a cross section of a parison whose local area is enlarged.

FIG. 5 is a schematic view showing one example of a flat container manufactured by the manufacturing method according to the present invention.

FIG. 6 is a schematic view showing a main part of a conventional flat container manufacturing method.

[Explanation of symbols]

Reference Signs List 1 parison 11 enlarged part 11a protruding part 11C part corresponding to corner of parison 2 molding die 3 parison in conventional manufacturing method 3C part corresponding to corner of parison in conventional manufacturing method 4 Manufactured by the manufacturing method of the present invention Container 4R rib

Claims (4)

[Claims] 1. A parison locally enlarged by support air with its lower end closed, placed in a molding die with the enlarged part of the parison protruding from a cavity of the molding die, and blow molded. A method for producing a flat container. 2. A parison is arranged on a mold having a cutting blade provided at an edge of the cavity, and the mold is aligned so as to cut the parison protruding from the inside of the cavity.
The method for producing a flat container according to claim 1, wherein the flat container is blow-molded. 3. The method for producing a flat container according to claim 1, wherein the parison is enlarged into a lantern shape. 4. A flat container manufactured by the method according to claim 1.