JP7630172B2 - How the lid is manufactured - Google Patents

Description

This disclosure relates to a method for manufacturing a lid, and in particular to a method for manufacturing a lid for a disposable food container.

Food containers are well known that have a container body for storing food such as boxed lunches and fresh foods, and a lid that fits over the container body and closes the top opening. These food containers are generally disposable and are used only when food is sold at stores such as convenience stores and supermarkets, and the lid is made of a transparent plastic sheet so that the contents can be seen. In addition, the lid has ventilation holes to maintain the freshness of the food inside the container.

JP 2018-20850 A

It is desirable to make the size of this ventilation hole as small as possible so that external dust and other particles do not enter the container through the ventilation hole.

Therefore, this disclosure was devised in consideration of the above circumstances, and its purpose is to provide a method for manufacturing a lid that can form a small vent hole in the lid.

According to one aspect of the present disclosure,
A method for manufacturing a lid for a disposable food container, comprising:
The method for manufacturing a lid is characterized by comprising a hole processing step of forming an air hole in the lid using a carving blade.

Preferably, the engraving blade mold has a blade having a closed shape in a plan view,
In the hole processing step, the lid is cut by the blade, and a scrap having the same shape as the vent hole is punched out from the lid.

Preferably, the engraving blade has a scrap hole with a tapered cross section for dropping the scrap.

Preferably, the blade is a single-edged type with the cutting edge offset toward the air vent.

Preferably, the ventilation hole has a diameter or minimum width of 0.3 mm or more and 1 mm or less.

Preferably, the ventilation holes are circular or slot-shaped.

According to this disclosure, it is possible to form a small vent in the lid.

FIG. 2 is a diagram showing a food container according to the present embodiment. FIG. FIG. 13 is an enlarged plan view showing another ventilation hole. FIG. FIG. FIG. 11 is a diagram for explaining a hole processing step. FIG. 11 is a diagram for explaining a hole processing step.

Embodiments of the present disclosure will be described below with reference to the accompanying drawings. Please note that the present disclosure is not limited to the following embodiments.

Figure 1 shows a food container according to an embodiment of the present disclosure, with (A) being a plan view and (B) being a front cross-sectional view (cross-sectional view taken along line Ib-Ib in (A)). For convenience, the front, back, left, right, top and bottom directions are defined as shown in the figure. However, please note that these directions have been defined merely for convenience of explanation. Also, please note that the dimensions, shapes, etc. of each part shown in the figure may be exaggerated for ease of understanding and are not necessarily accurate.

The food container 1 is a disposable type container that is used only when selling food at stores such as convenience stores and supermarkets. The food container 1 comprises a container body 2 that holds food F, and a lid 3 that fits over the container body 2 and closes its upper opening. The food F in this embodiment is a boxed lunch, and the food container 1 is used, for example, as an airtight container for holding boxed lunches sold at convenience stores. The container body 2 and lid 3 in this embodiment are circular in plan view as shown in Figure 1 (A), but the shape is not limited and may be rectangular, elliptical, etc.

The container body 2 and the lid 3 are both made of plastic and are formed by vacuum forming or the like of a plastic sheet material. Examples of plastic materials that can be used include polyethylene, polypropylene, polystyrene, and polyethylene terephthalate. For example, the container body 2 can be made of polypropylene and the lid 3 can be made of polyethylene. The lid 3 is transparent so that the contents can be seen.

The container body 2 and the lid 3 may be made of materials other than plastic, for example paper.

The container body 2 is circular bowl-shaped, and its upper edge 2A is folded back radially outward. The outer peripheral edge 3A of the roughly disk-shaped lid 3 is tightly fitted to the outside of this upper edge 2A, sealing the inside of the container 1. The outer peripheral edge 3A of the lid 3 also has a folded back shape that matches the upper edge 2A of the container body 2. The part of the lid 3 inside the outer peripheral edge 3A is a horizontal disk-shaped central portion 3B that is positioned lower than the outer peripheral edge 3A.

In the center 3B of the lid 3, a vent hole 4 is formed to keep the food F fresh inside the container 1. In particular, in this embodiment, a number of very small vent holes 4 are formed by a hole processing process described below. In this embodiment, six elongated vent holes 4 are arranged in a lattice pattern. In this embodiment, the group of six vent holes 4 is offset radially outward (toward the front) from the center of the lid 3, as shown in FIG. 1(A).

The number, position, arrangement, etc. of the ventilation holes 4 are arbitrary, and may be one or a number other than six.

As shown enlarged in FIG. 2, in this embodiment, the ventilation hole 4 is an elongated hole extending in the left-right direction. The ventilation hole 4 has a length A and a width B. The width B is constant in the length A direction. The base end (right end) 5 and the tip (left end) 6 of the ventilation hole 4 in the length A direction are formed in a semicircular shape. In addition, the front and rear side edges 7, 8 connecting the base end 5 and the tip 6 are linear and parallel to the left-right direction.

As mentioned above, in order to prevent external dust and the like from entering the container 1 through the ventilation hole 4, it is desirable for the size of the ventilation hole 4 to be as small as possible. In addition, in the hole processing step described below, the ventilation hole 4 is formed in the lid 3 using an engraving blade. Normally, ventilation holes are formed in the lid using a punch in a press die, but there is a limit to how small the punch can be, and it is not possible to process a minute hole such as the ventilation hole 4 in this embodiment. However, in this embodiment, a high-precision type of engraving blade is used as described below, so it is possible to process a ventilation hole 4 that is smaller than when a normal punch is used.

The width B defines the minimum width (Bmin) of the ventilation hole 4. Here, the minimum width refers to the width of the portion of the ventilation hole 4 that has the smallest width. In this embodiment, this minimum width can be made smaller than when a normal punch is used, and can be made as small as 0.3 mm. On the other hand, when a normal punch is used, the minimum width exceeds 1 mm. Therefore, it is preferable that the minimum width of the ventilation hole 4 in this embodiment is 0.3 mm or more and 1 mm or less.

In this embodiment, the width B of the ventilation hole 4 is 0.3 mm. Meanwhile, the length A is larger, at 5.0 mm. These dimensions can be changed.

Incidentally, the shape of the ventilation hole 4 can also be a circle as shown in FIG. 3. In this case, it is preferable that the diameter D of the ventilation hole 4 is 0.3 mm or more and 1 mm or less.

As described above, the ventilation hole 4 of this embodiment has a very small size. Therefore, it is possible to effectively prevent external dust and the like (dust, insects, foreign objects, etc.) from entering the container 1 through the ventilation hole 4. The lid 3 of this embodiment is extremely advantageous in preventing the intrusion of external dust and the like into the container 1.

Of course, air can circulate between the inside and outside of the container through the ventilation holes 4, so the freshness of the food F inside the container 1 can be maintained.

On the other hand, food F in container 1, which is covered and sealed with lid 3, is planned to be heated in a microwave oven along with container 1. During this heating, water vapor and steam (called water vapor, etc.) are generated from food F, which must be released to the outside.

According to this embodiment, water vapor and the like can be effectively released through the ventilation holes 4. In addition, since multiple ventilation holes 4 are provided, the total area of the ventilation holes 4 can be increased, and the total area required for discharging water vapor and the like can be sufficiently secured. In this way, the ventilation holes 4 function as effective steam release holes.

However, the uses of the ventilation hole 4 are not limited to the above. For example, when the food F is noodles for instant yakisoba, the ventilation hole 4 can be used as a draining hole. Also, when the food F is vegetables that contain a lot of water, the vegetables may sweat and water may accumulate inside the container. In this case, the ventilation hole 4 can also be used as a draining hole.

The size, number, and shape of the ventilation holes 4 are optimally set to satisfy the above functions.

This embodiment provides a method for manufacturing a lid 3 that can form such excellent small-sized ventilation holes 4 in the lid 3.

The method for manufacturing the lid 3 in this embodiment includes a forming step in which a plastic sheet material is cut and formed (particularly vacuum formed) to produce a lid 3 of a predetermined shape, and a hole processing step in which the vent hole 4 is formed in the lid 3 produced by the forming step. The manufacturing method in this embodiment is particularly characterized in that the vent hole 4 is formed using a carving blade in the hole processing step.

Figure 4 shows the engraving blade mold. (A) is a plan view, and (B) is a side cross-sectional view (IVb-IVb cross-sectional view of (A)). Note that since the six ventilation holes 4 are created in the same manner, for the sake of convenience, the following explanation will be given for the case where there is only one ventilation hole 4.

A carving blade mold is a mold that is cut out of a block or plate of metal material and has a blade machined into it. The high hardness of the metal material gives it the advantage of being highly durable and strong. On the other hand, it has the disadvantage of being expensive to manufacture.

The engraving blade mold 10 has a base plate 11 that forms the base, and a blade (engraving blade) 12 that is integrally formed with the base plate 11. The engraving blade mold 10 also has a scrap hole 13 through which the scrap S (see Figure 7) punched out from the lid 3 falls.

The base plate 11 is a rectangular plate-like member that is long in the left-right direction when viewed from above (Figure 4 (A)). In this embodiment, the scrap holes 13 are formed in the base plate 11 by wire electric discharge machining, so the material of the base plate 11 is a conductive metal, in particular iron.

The blade 12 protrudes upward from the upper surface 11A of the base plate 11. The blade 12 has a cutting edge 14 located at its uppermost end, and the thickness Tb gradually decreases from the lower end toward the cutting edge 14 at the uppermost end. The shape of the blade 12 and cutting edge 14 in a plan view (FIG. 4(A)) is an elongated hole shape similar to the air vent 4. The height Hb1 of the blade 12 based on the lower surface 11B of the base plate 11 is constant around the entire circumference of the blade 12 in a plan view. The height Hb2 of the blade 12 based on the upper surface 11A of the base plate 11 is also constant around the entire circumference, and is naturally greater than the thickness of the lid 3.

In this way, the blade 12 and cutting edge 14 of this embodiment have a closed shape when viewed in a plan view (Figure 4(A)). Then, in the hole processing step, the blade 12 cuts the lid 3, and a scrap S having the same shape as the vent hole 4 is punched out of the lid 3.

In this embodiment, the blade 12 is a single-edged type. That is, the cutting edge 14 is not exactly halfway from the center of the thickness Tb, but is offset to one side in the thickness Tb direction. This offset direction is called the offset direction or offset side. The offset direction in this embodiment is toward the inner surface 12A side (vent hole 4 side) of the blade 12 (see FIG. 7). This makes it possible to shorten the distance Bb between the cutting edges 14 located in the front and rear compared to when a center blade type blade (a blade whose cutting edge is exactly halfway from the center of the thickness) is used, which is advantageous in reducing the width B (minimum width Bmin) of the vent hole 4. In addition, scrap S can be dropped more smoothly compared to when a center blade type blade is used.

The inner surfaces 12A of the blades 12 are parallel in the vertical direction, and the inner surfaces 12A of the blades 12 facing each other are also parallel. The inner hole of the blade 12 defined by the inner surfaces 12A of the blades 12, i.e., the inner blade hole 15, is a straight hole with a constant cross section that extends parallel in the vertical direction. The inner surface 12A starts from the uppermost cutting edge 14 and extends downward. The inner surface 12A has a predetermined height dimension Hbi. The height dimension Hbi is greater than the thickness of the lid 3. In this embodiment, the height dimension Hbi is 1 to 1.5 mm.

The outer surface 12B of the blade 12 (the side opposite the air vent 4) is inclined so that it gradually approaches the inner surface 12A as it moves from bottom to top.

The scrap hole 13 is a through hole that extends vertically below the blade hole 15 and is tapered in cross section, becoming wider as it goes downward, as shown in FIG. 4(B). The taper angle θ is, for example, 2 to 4°. By tapering the scrap hole 13 in cross section in this way, the punched scrap S can be smoothly dropped inside the scrap hole 13, and adhesion of the scrap S to the lid 3 and, ultimately, contamination of the scrap S into the container 1 can be reliably prevented.

Here we explain how to make the engraving blade mold 10.

To make the engraving blade mold 10, a rectangular plate-shaped metal material 16 with a height Hm equal to or greater than the height Hb1 of the blade 12 is used, as shown in Figure 5. In the figure, (A) is a plan view, and (B) is a side cross-sectional view (Vb-Vb cross-sectional view of (A)). A tapered through hole 17 that forms the scrap hole 13 and part of the blade inner hole 15 is machined into this material 16 using a wire electric discharge machine.

Next, the material 16 is cut using a high-precision machining center until it assumes the shape shown in FIG. 4, and the blade 12 is cut out to complete the engraving blade mold 10. At this time, in order to ensure the precision of the height position of the cutting edge 14 and to make the blade 12 a cutting edge with sufficient sharpness, the inside of the blade 12 is also cut to form the inner surface 12A.

When forming the through hole 17 by wire electric discharge machining, the shape and dimensions of the through hole 17 are set taking into consideration the finished dimensions of the engraving blade die 10 and so that the inner surface 12A of the height dimension Hbi can be machined.

When cutting out the engraving blade mold 10 by cutting, the blade length relative to the diameter of the blade used is important; as the diameter becomes smaller, the blade length becomes shorter. For example, when manufacturing an engraving blade mold 10 with a spacing Bb of 0.3 mm between the blade tips 14, a blade with a diameter of φ0.3 mm or less is used, which makes the cutting process difficult, and since the blade length is short, it is difficult to achieve this by cutting alone. However, in this embodiment, it is combined with electric discharge machining using a wire electric discharge machine, so it is possible to stably manufacture an engraving blade mold 10 with an extremely small spacing Bb.

As shown in FIG. 6, in the hole processing step, the engraving die 10 is fixed to the lower die (not shown) of the press machine, and the lid 3 is placed on the engraving die 10 and positioned. Meanwhile, a backing plate 18 is fixed to the underside of the upper die (not shown) of the press machine, which can be raised and lowered. The backing plate 18 may be made of a resin plate, a high-performance film, a stainless steel plate, or the like. Note that, contrary to the illustrated example, the engraving die 10 may be fixed to the upper die, the backing plate 18 may be fixed to the lower die, and the lid 3 may be placed on the backing plate 18.

When the upper die is lowered, the backing plate 18 approaches the lid 3. Figure 6 shows the state just before the backing plate 18 comes into contact with the lid 3 and the lid 3 is cut by the blade 12 of the engraving die 10.

Figure 7 shows the state when the upper die and the backing plate 18 are further lowered, and the lid 3 is lowered accordingly. At this time, the lid 3 is pressed against the blade 12 of the engraving blade die 10, and is then cut by the blade 12. Then, the air hole 4 is formed in the lid 3, and scrap S having the same shape as the air hole 4 is punched out of the lid 3. The upper die is lowered until the blade 12 barely touches the backing plate 18. The scrap S passes through the blade hole 15 and the scrap hole 13 in sequence and falls. As described above, the scrap hole 13 is tapered, so the fall is smooth. In this way, the scrap S can be completely separated from the lid 3, and therefore it is possible to reliably prevent the scrap S from adhering to the lid 3 and from being mixed into the container.

In this way, the manufacturing method of this embodiment makes it possible to effectively form small vent holes 4 in the lid 3.

Although the embodiment of the present disclosure has been described in detail above, various other embodiments and modifications of the present disclosure are possible. For example, the lid 3 does not necessarily have to be transparent, and may be opaque. The above numerical values are merely examples and may be modified as appropriate. The ventilation hole 4 may have other shapes, such as a rectangle or an oval.

The embodiments of the present disclosure are not limited to the above-mentioned embodiments, and all modifications, applications, and equivalents encompassed within the concept of the present disclosure as defined by the claims are included in the present disclosure. Therefore, the present disclosure should not be interpreted in a limited manner, and may be applied to any other technology that falls within the scope of the concept of the present disclosure.

1 Food container 3 Lid 4 Vent 10 Engraving blade mold 12 Blade 13 Scrap hole 14 Blade tip S Scrap

Claims (4)

A method for manufacturing a lid for a disposable food container, comprising:
A hole processing step is provided in which a vent hole is formed in the lid using a carving blade mold;
The engraving blade mold has a blade having a closed shape in a plan view,
In the hole processing step, the lid is cut by the blade, and a scrap having the same shape as the vent hole is punched out from the lid,
The blade is a single-edged type whose cutting edge is offset toward the air vent,
the engraving blade die has a base plate, the blade formed integrally with the base plate and projecting upward from an upper surface of the base plate, and a scrap hole formed in the base plate through which the scrap punched out from the lid falls,
a blade bore is defined by the opposing inner surfaces of the blades;
The scrap hole is formed continuously below the blade hole,
The blade hole is a straight hole that extends parallel to the vertical direction and has a constant cross section,
The scrap hole is formed in a tapered cross section that becomes wider toward the bottom.
A method for manufacturing a lid comprising the steps of: The method for manufacturing a lid according to claim 1 , wherein the vent hole has a diameter or minimum width of 0.3 mm or more and 1 mm or less. The method for manufacturing a lid according to claim 1 or 2 , wherein the ventilation hole is circular or elongated. A method for manufacturing the engraving blade die used in the method for manufacturing the lid according to any one of claims 1 to 3,
a first step of forming a tapered through hole, which constitutes the scrap hole and a part of the blade hole, in a metal blank by wire electric discharge machining;
A second step of cutting the material by a machining center until it has a final shape, and cutting out the blade to complete the engraving blade mold;
A method for manufacturing an engraving blade mold, comprising:

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