How the lid is manufactured

Abstract

To provide a method of manufacturing a lid adapted for forming a small-sized air hole in a lid.SOLUTION: A method of manufacturing a lid 3, in a food container of a disposal type, comprises a hole making step of forming an air hole 4 in a lid using a chisel die 10.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a lid, and more particularly to a method for manufacturing a lid for a disposable food container. [Background technology]

[0002] Food containers are known that have a container body for storing food such as boxed lunches and fresh food, and a lid that fits over the container body to close the top opening. Such 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. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-20850 A Summary of the Invention [Problem to be solved by the invention]

[0004] 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.

[0005] The present disclosure has been devised in light of the above circumstances, and has an object to provide a method for manufacturing a lid that is capable of forming a small-sized ventilation hole in the lid. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, A method for manufacturing a lid for a disposable food container, comprising: A hole processing step is included in which a vent hole is formed in the lid using a carving blade. A method for manufacturing a lid is provided.

[0007] 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.

[0008] Preferably, the engraving blade die has a scrap hole having a tapered cross section for allowing the scrap to fall therethrough.

[0009] Preferably, the blade is a single-edged type whose cutting edge is offset toward the air vent.

[0010] Preferably, the vent has a diameter or minimum width of at least 0.3 mm and not more than 1 mm.

[0011] Preferably, the ventilation holes are circular or slot-shaped. Effect of the Invention

[0012] According to the present disclosure, a small vent hole can be formed in the lid. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a diagram showing a food container according to the present embodiment. [Diagram 2] FIG. [Diagram 3] FIG. 13 is an enlarged plan view showing another ventilation hole. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. 11 is a diagram for explaining a hole processing step. [Figure 7] FIG. 11 is a diagram for explaining a hole processing step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to the following embodiments.

[0015] FIG. 1 shows a food container according to an embodiment of the present disclosure, where (A) is a plan view and (B) is a front cross-sectional view (cross-sectional view taken along line Ib-Ib in (A)). For convenience, the directions of front, back, left, right, top and bottom are defined as shown in the figure. However, it should be noted that these directions are defined merely for convenience of explanation. It should also be noted that the dimensions, shapes, etc. of each part shown in the figure may be exaggerated for ease of understanding and are not necessarily accurate.

[0016] The food container 1 is a disposable container that is used only when selling food at a store such as a convenience store or supermarket. 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 the upper opening. The food F in this embodiment is a boxed lunch, and the food container 1 is used as an airtight container for holding the boxed lunch sold at a convenience store, for example. The container body 2 and lid 3 in this embodiment are circular in plan view as shown in Fig. 1(A), but the shape is not limited thereto and may be rectangular, elliptical, or the like.

[0017] Both the container body 2 and the lid 3 are made of plastic, and are formed by vacuum forming or the like of a plastic sheet material. Examples of the plastic material 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.

[0018] The container body 2 and the lid 3 may be made of a material other than plastic, for example, paper.

[0019] The container body 2 is shaped like a circular bowl, and its upper edge 2A is folded back radially outward. The outer peripheral edge 3A of a substantially disk-shaped lid 3 is tightly fitted onto 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 that is inward from the outer peripheral edge 3A is a horizontal disk-shaped central portion 3B that is positioned lower than the outer peripheral edge 3A.

[0020] A vent hole 4 is formed in the center 3B of the lid 3 to keep the food F fresh in the container 1. In particular, in this embodiment, a plurality of very small vent holes 4 are formed by a hole processing step 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).

[0021] The number, position, arrangement and the like of the ventilation holes 4 are arbitrary, and the number may be one or any number other than six.

[0022] As shown enlarged in Fig. 2, the ventilation hole 4 in this embodiment 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. Furthermore, 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.

[0023] As described above, in order to prevent external dust and the like from entering the container 1 through the ventilation hole 4, it is desirable that the size of the ventilation hole 4 is as small as possible. In the hole processing step described below, the ventilation hole 4 is formed in the lid 3 using an engraving blade. Usually, ventilation holes are formed in the lid using a punch of a press die, but there is a limit to how small the punch can be made, and it is not possible to process a minute hole such as the ventilation hole 4 of this embodiment. However, in this embodiment, a high-precision type engraving blade as described below is used, so that it is possible to process a ventilation hole 4 that is smaller than when a normal punch is used.

[0024] 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, the minimum width when a normal punch is used exceeds 1 mm. Therefore, the minimum width of the ventilation hole 4 in this embodiment is preferably 0.3 mm or more and 1 mm or less.

[0025] In this embodiment, the width B of the vent hole 4 is 0.3 mm. Meanwhile, the length A is larger, 5.0 mm. These dimensions can be changed.

[0026] Incidentally, the shape of the ventilation hole 4 may be a circle as shown in Fig. 3. In this case, the diameter D of the ventilation hole 4 is preferably 0.3 mm or more and 1 mm or less.

[0027] 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.

[0028] 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 in the container 1 can be maintained in a good condition.

[0029] Meanwhile, food F in container 1, which is covered and sealed with lid 3, is planned to be heated in a microwave oven together with container 1. During such heating, water vapor and steam (called water vapor, etc.) are generated from food F, which must be released to the outside.

[0030] According to this embodiment, water vapor and the like can be efficiently released through the ventilation holes 4. Furthermore, since a plurality of ventilation holes 4 are provided, the total area of ​​the ventilation holes 4 is increased, and the total area required for discharging water vapor and the like can be sufficiently secured. Thus, the ventilation holes 4 function as efficient steam release holes.

[0031] However, the use of the ventilation hole 4 is 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 or the like that contain a lot of water, the vegetables or the like may sweat and water may accumulate inside the container. In this case, the ventilation hole 4 can also be used as a draining hole.

[0032] The size, number, shape, etc. of the ventilation holes 4 are optimally set so as to satisfy the above functions.

[0033] The present embodiment provides a method for manufacturing the lid 3 that can form such excellent small vent holes 4 in the lid 3.

[0034] The manufacturing method of the lid 3 of this embodiment includes a forming step of cutting and forming (particularly vacuum forming) a plastic sheet material to produce the lid 3 in a predetermined shape, and a hole processing step of forming the ventilation hole 4 in the lid 3 produced by the forming step. The manufacturing method of this embodiment is particularly characterized in that the ventilation hole 4 is formed using a carving blade in the hole processing step.

[0035] The engraving blade mold is shown in Fig. 4. (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 description will be given for the case where there is only one ventilation hole 4.

[0036] 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 durable and strong. On the other hand, the disadvantage is that the manufacturing costs are high.

[0037] The engraving blade die 10 includes a base plate 11 that forms a base, and a blade (engraving blade) 12 that is integrally formed with the base plate 11. The engraving blade die 10 also includes a scrap hole 13 through which scrap S (see FIG. 7) punched out from the lid 3 falls.

[0038] The base plate 11 is a rectangular plate-like member that is long in the left-right direction in a plan view (FIG. 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.

[0039] The blade 12 is provided to protrude upward from the upper surface portion 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 the cutting edge 14 in a plan view (FIG. 4(A)) is an elongated hole shape similar to the air hole 4. The height Hb1 of the blade 12 based on the lower surface portion 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 portion 11A of the base plate 11 is also constant around the entire circumference, and is naturally greater than the thickness of the lid 3.

[0040] In this manner, the blade 12 and the blade tip 14 of this embodiment have a closed shape in plan view (FIG. 4(A)). 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.

[0041] 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 the direction toward the inner surface 12A side (vent hole 4 side) of the blade 12 (see FIG. 7). This makes it possible to shorten the interval Bb between the cutting edges 14 located at the front and rear compared to the case where a center cutting 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, the scrap S can be dropped more smoothly compared to the case where a center cutting type blade is used.

[0042] The inner surfaces 12A of the blades 12 are parallel to each other in the vertical direction, and the inner surfaces 12A of the blades 12 facing each other are also parallel to each other. 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 to the vertical direction. The inner surface 12A starts from the blade tip 14 at the uppermost end 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. The height dimension Hbi in this embodiment is 1 to 1.5 mm.

[0043] An outer surface 12B of the blade 12 (the surface opposite to the air hole 4) is inclined so as to gradually approach the inner surface 12A from the bottom to the top.

[0044] The scrap hole 13 is a through hole that extends vertically below the blade inner hole 15, and is formed with a tapered cross section that becomes wider toward the bottom as shown in FIG. 4(B). The taper angle θ is, for example, 2 to 4°. By forming the scrap hole 13 with a tapered cross section in this manner, the punched scrap S can be smoothly dropped inside the scrap hole 13, and the adhesion of the scrap S to the lid 3 and the inclusion of the scrap S in the container 1 can be reliably suppressed.

[0045] Here, a method for producing the engraving blade die 10 will be described.

[0046] To manufacture the engraving blade die 10, a rectangular plate-shaped metal blank 16 having a height Hm equal to or greater than the height Hb1 of the blade 12 is used, as shown in Fig. 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, which forms a scrap hole 13 and a part of the blade inner hole 15, is machined in this blank 16 by a wire electric discharge machine.

[0047] Next, the blank 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 accuracy 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.

[0048] When forming the through hole 17 by wire electric discharge machining, the shape and dimensions of the through hole 17 are set in consideration of the finished dimensions of the engraving blade die 10 and so that the inner surface 12A of the height dimension Hbi can be machined.

[0049] When cutting out the engraving blade mold 10 by cutting, the blade length relative to the diameter of the blade used is important, and the blade length becomes shorter as the diameter becomes smaller. For example, when manufacturing an engraving blade mold 10 with a spacing Bb of the blade tips 14 of 0.3 mm, a blade with a diameter of φ0.3 mm or less is used, which is difficult to cut, and the blade length is short, making it difficult to achieve 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.

[0050] 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 lower surface of the upper die (not shown) of the press machine which can be raised and lowered. The backing plate 18 is 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.

[0051] When the upper die is lowered, the backing plate 18 approaches the lid 3. Fig. 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.

[0052] FIG. 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 10, and then cut by the blade 12. Then, the vent hole 4 is formed in the lid 3, and the scrap S having the same shape as the vent hole 4 is punched out from the lid 3. The upper die is lowered until the blade 12 slightly touches the backing plate 18. The scrap S passes through the blade hole 15 and the scrap hole 13 in order and falls. As described above, the scrap hole 13 is tapered, so that the scrap S falls smoothly. In this way, the scrap S can be completely separated from the lid 3, and therefore, the scrap S can be reliably prevented from adhering to the lid 3 and from being mixed into the container.

[0053] In this way, according to the manufacturing method of this embodiment, small vent holes 4 can be suitably formed in lid 3.

[0054] Although the embodiment of the present disclosure has been described in detail above, various other embodiments and modifications of the present disclosure are conceivable. For example, the cover 3 does not necessarily have to be transparent, and may be opaque. The above values ​​are merely examples and may be changed as appropriate. The vent hole 4 may have other shapes, such as a rectangle, an ellipse, etc.

[0055] The embodiments of the present disclosure are not limited to the above-described embodiments, and all modifications, applications, and equivalents encompassed within the spirit of the present disclosure as defined by the claims are included in the present disclosure. Therefore, the present disclosure should not be interpreted as being limited, and can be applied to any other technology that falls within the spirit of the present disclosure. [Explanation of symbols]

[0056] 1 Food containers 3 Lid 4 Ventilation holes 10 Engraving blade mold 12 blades 13. Scrap Hole 14 Cutting Edge S Scrap

Claims

1. 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:

2. The vent has a diameter or minimum width of 0.3 mm or more and 1 mm or less. A method for manufacturing the lid according to claim 1.

3. The ventilation hole is circular or slot-shaped. A method for manufacturing the lid according to claim 1 or 2.

4. A method for manufacturing the engraving blade mold used in the method for manufacturing a lid according to any one of claims 1 to 3, comprising the steps of: 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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