How the lid is manufactured

Abstract

To provide a lid manufacturing method which can balance suppression of intrusion of dust etc. in normal times and augmentation of discharge of water vapor, etc. during heating.SOLUTION: A manufacturing method of a lid for a disposable food container includes a hole processing step in which a vent hole and a cantilevered valve that closes the vent hole in an openable manner are simultaneously formed in a lid by making a cut in the lid using a Thomson mold 10. The Thomson mold includes a base plate 11, a Thomson blade 12, and a blade groove 13 provided on the base plate and into which the Thomson blade is inserted. The Thomson blade is inserted into the blade groove with at least one return.SELECTED DRAWING: Figure 4

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 vent as small as possible so that external dust and other particles do not enter the container through the vent. On the other hand, it is planned that the food inside the container will be heated in a microwave oven or the like, and water vapor and other substances will be generated from the food during heating. It is also desirable for the vent to be able to smoothly exhaust this water vapor and other substances to the outside, and in order to do so, it is necessary for the vent to be at least a certain size.

[0005] The present disclosure has been devised in consideration of these circumstances, and its purpose is to provide a method for manufacturing a lid that can achieve a good balance between preventing the intrusion of dust and other particles under normal conditions and promoting the expulsion of water vapor and the like when heated. [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 of simultaneously forming an air hole in the lid and a cantilever-shaped valve that closes the air hole in an openable and closable manner by making a cut in the lid using a Thomson die; The Thomson type is A base plate; Thomson blade, a cutting groove provided on the base plate and into which the Thomson cutting blade is inserted; Equipped with The Thomson blade is inserted into the blade groove in a state where it is folded back at least once. A method for manufacturing a lid is provided.

[0007] Preferably, the Thomson blade has a front folded portion, a folded portion, and a rear folded portion arranged in this order from one end side to the other end side in the longitudinal direction thereof.

[0008] Preferably, the Thomson die includes a spacer sandwiched between the front folded portion and the rear folded portion.

[0009] Preferably, the Thompson blade is folded back such that the front folded portion and the rear folded portion are in close contact with each other.

[0010] Preferably, the Thomson blade is of a single-edged type, and is folded back so that the offset side of the front folded portion and the offset side of the rear folded portion approach each other.

[0011] Preferably, the Thompson blade is folded once in a U-shape to form a U-shaped vent and valve.

[0012] Preferably, the Thompson blade is folded once in a U-shape and bent in a wavy manner to form a wavy U-shape of the vent and the valve.

[0013] Preferably, a plurality of the Thomson blades are inserted into the cutting groove in a state of being arranged in parallel.

[0014] Preferably, the Thompson blade is folded three times in a cross shape to form a cross-shaped vent and valve.

[0015] According to another aspect of the present disclosure, A Thomson die for simultaneously forming an air hole in a lid of a disposable food container and a cantilever valve for opening and closing the air hole by making a slit in the lid, A base plate; Thomson blade, a cutting groove provided on the base plate and into which the Thomson cutting blade is inserted; Equipped with The Thomson blade is inserted into the blade groove in a state where it is folded back at least once. A Thomson type is provided, characterized in that Effect of the Invention

[0016] According to the present disclosure, it is possible to provide a method for manufacturing a lid that can achieve a good balance between preventing the intrusion of dust and other particles under normal conditions and promoting the expulsion of water vapor and other particles when heated. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a diagram showing a food container according to the present embodiment. [Diagram 2] FIG. [Diagram 3] FIG. 4 is a front cross-sectional view showing ventilation holes and the like. [Figure 4] FIG. 2 is a diagram showing a Thomson type according to the present embodiment. [Diagram 5] FIG. [Figure 6] FIG. 1 shows a Thomson blade. [Figure 7] FIG. [Figure 8] FIG. 11 is a front cross-sectional view for explaining a hole processing step. [Figure 9] FIG. 11 is a front cross-sectional view for explaining a hole processing step. [Figure 10] FIG. 13 is a diagram showing a Thomson blade according to a first modified example. [Figure 11] FIG. 13 is a diagram showing a Thomson blade according to a second modified example. [Figure 12] FIG. 1 is a front view showing an example of a Thompson blade type. [Figure 13] FIG. 13 is a diagram showing a Thomson type of a third modified example. [Figure 14] FIG. 13 is a diagram showing a base plate of a third modified example. [Figure 15] FIG. 13 is a plan view showing an air hole of a third modified example. [Figure 16] FIG. 13 is a diagram showing each member of a Thomson type according to a fourth modified example. [Figure 17] FIG. 13 is a plan view showing an air hole of a fourth modified example. [Figure 18] FIG. 13 is a diagram showing each member of a Thomson type according to a fifth modified example. [Figure 19] FIG. 13 is a plan view showing an air hole of a fifth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 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.

[0019] 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 of the figures described below may be exaggerated for ease of understanding and are not necessarily accurate.

[0020] 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.

[0021] 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.

[0022] The container body 2 and the lid 3 may be made of a material other than plastic, for example, paper.

[0023] 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.

[0024] A vent hole 4 for maintaining the freshness of the food F in the container 1 is formed in the center 3B of the lid 3. In particular, in this embodiment, a cantilevered valve 5 for opening and closing the vent hole 4 is formed at the same time as the vent hole 4 by a hole processing step described later. In this embodiment, six pairs of vent holes 4 and valves 5 (for convenience, referred to as a hole pair) are provided and arranged in a lattice pattern. In this embodiment, the group of six hole pairs (for convenience, referred to as a hole pair group) is arranged radially outward (to the front) from the center of the lid 3, as shown in FIG. 1(A).

[0025] The number, positions, arrangement method, etc. of the hole sets are arbitrary, and may be one or a number other than six. The same applies to the hole set groups.

[0026] As shown enlarged in Fig. 2, the vent hole 4 and the valve 5 in one hole set are U-shaped (or hairpin shaped) extending in the left-right direction in this embodiment. A U-shaped slit 6 is formed in the lid 3, penetrating it, thereby simultaneously forming the vent hole 4 and the plate-like valve 5. A straight dashed line 7 represents the base end (one end) in the longitudinal direction of the vent hole 4 and the base end (one end) in the longitudinal direction of the valve 5 connected to the lid 3. Meanwhile, a tip (other end) 8 in the longitudinal direction of the vent hole 4 and a tip (other end) 9 in the longitudinal direction of the valve 5 are formed in a semicircular shape.

[0027] The vent 4, valve 5 and slit 6 (referred to as vent 4, etc.) have a very small size and are extremely elongated. In this embodiment, the length A and width B of the vent 4, valve 5 and slit 6 are substantially equal, with the length A being 30 mm and the width B being 0.6 mm.

[0028] 3, under normal circumstances, the valve 5 substantially completely closes the vent hole 4. The only gap between them is the slit 6. Therefore, it is possible to almost completely prevent external dust and the like (dust, insects, foreign objects, etc.) from entering the container 1 through the vent 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.

[0029] At this time, air can circulate between the inside and outside of the container through the slits 6. This allows the food F in the container 1 to be kept fresh.

[0030] Even if the valve 5 is opened for some reason, the width B of the ventilation hole 4 is very small, so that the risk of intrusion of dust and the like through the ventilation hole 4 can be minimized.

[0031] 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.

[0032] At this time, the valve 5 is pushed by the steam etc. V as shown by the imaginary line a and elastically bends upward, opening the vent hole 4. This allows the steam etc. V to be smoothly discharged through the vent hole 4, allowing heating to be performed smoothly and safely. In this way, the vent hole 4 also functions as an excellent steam release hole.

[0033] As described above, according to this embodiment, it is possible to achieve a good balance between preventing the intrusion of dust and other particles into the container under normal conditions and promoting the discharge of water vapor and the like out of the container when heated.

[0034] However, the use of the vent hole 4 is not limited to the above. For example, when the food F is noodles for instant yakisoba, the vent hole 4 can be used as a drain hole. In this case, the valve 5 is pushed by the hot water and bent upward, so that the hot water in the container can be smoothly drained through the vent hole 4.

[0035] Furthermore, when the food F is a vegetable or the like that contains a lot of water, the vegetable 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 drain hole.

[0036] The size, number, shape, etc. of the ventilation holes 4 etc. are optimally set so as to satisfy the above functions.

[0037] The present embodiment provides a method for manufacturing the lid 3 having such an excellent small-sized vent hole 4 with a valve 5.

[0038] The manufacturing method of the lid 3 of this embodiment includes a forming step in which a plastic sheet material is cut and formed (particularly vacuum formed) to create the lid 3 in a predetermined shape, and a hole processing step in which the vent hole 4 and the valve 5 are simultaneously formed in the lid 3 created by the forming step. The manufacturing method of this embodiment is characterized in that a Thomson die, which will be described later, is used in this hole processing step.

[0039] Figure 4 shows the Thomson die used in the hole processing step. (A) is a plan view, and (B) is a front cross-sectional view (IVb-IVb cross-sectional view of (A)). Note that since six ventilation holes 4, etc. 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, etc.

[0040] The Thomson die 10 includes a base plate 11, a Thomson blade 12, and a blade groove 13 that is provided on the base plate 11 and into which the Thomson blade 12 is inserted. The Thomson blade 12 is inserted into the blade groove 13 in a state where it is folded back at least once. The Thomson die 10 also includes a spacer 14.

[0041] 5 shows the base plate 11 alone. (A) is a plan view, and (B) is a front cross-sectional view (Vb-Vb cross-sectional view of (A)).

[0042] The base plate 11 is a plate-like member for supporting the Thomson blade 12 in an upright state. Its material may be wood, resin, or metal. In this embodiment, a conductive metal, particularly iron, is used in consideration of durability and workability. The base plate 11 in this embodiment is rectangular in shape, elongated in the left-right direction, in a plan view.

[0043] The base plate 11 is formed with a U-shaped cutting groove 13 that extends linearly in the left-right direction in a plan view. The cutting groove 13 is shaped to match the outer shape of the Thomson blade 12, and is configured so that the Thomson blade 12 fits snugly into the cutting groove 13. The cutting groove 13 has a length Ag, a width Bg, and a depth Cg. In this embodiment, Ag=30.23 mm, Bg=1.06 mm in accordance with the size of the ventilation hole 4 (A=30 mm, B=0.6 mm) and the size of the Thomson blade 12 described below. Since the cutting groove 13 is a through hole, its depth Cg is equal to the thickness Cp of the base plate 11.

[0044] In plan view, the base end (right end) 15 in the longitudinal direction (left-right direction) of the cutting groove 13 is linear and perpendicular to the longitudinal direction, and the tip (left end) 16 is semicircular. The radius of curvature of the tip 16 is, for example, 0.53 mm. Furthermore, the front and rear side edges 17, 18 extending between the base end 15 and the tip 16 are linear and parallel to the longitudinal direction (left-right direction) in plan view.

[0045] The cutting groove 13 is formed by hollowing out the base plate 11 by wire electric discharge machining. For this reason, the base plate 11 is made of iron, which is a conductive metal. Since the cutting groove 13 is formed by wire electric discharge machining, a small cutting groove 13 can be formed with high precision. If a material other than a conductive metal (for example, an insulating material such as wood or resin) is used for the base plate 11, the cutting groove 13 can be formed by cutting using a machining center or the like. The cutting groove 13 may also be formed by a laser processing machine.

[0046] 4(B), the base plate 11 is placed on a base plate holder 19, which is also a metal plate, and fixed with a plurality of bolts 20. For this purpose, a plurality of female screw holes 21 into which the bolts 20 are screwed are provided penetrating the outer periphery of the base plate 11. When the base plate 11 is fixed to the base plate holder 19, the lower end of the cutting edge 13 is closed by the base plate holder 19.

[0047] 6 shows the Thomson blade 12 alone. (A) is a plan view, and (B) is a front cross-sectional view (VIb-VIb cross-sectional view of (A)).

[0048] The Thomson blade 12 is a plate-shaped blade made of metal (especially iron) and has a base end (one end) 22 and a tip (the other end) 23 in the longitudinal direction. The Thomson blade 12 is folded (or folded) once in the thickness Tb direction at the middle part in the longitudinal direction to form a U-shape in a plan view. The part on the base end 22 side from the folded part 24 is called a front folded part 25, and the part on the tip 23 side from the folded part 24 is called a rear folded part 26. The Thomson blade 12 has the front folded part 25, the folded part 24, and the rear folded part 26 arranged in this order from the base end 22 side to the tip 23 side in the longitudinal direction. The Thomson blade 12 is folded so that its length is approximately halved. The base end 22 and the tip 23 are located at the same position in the left-right direction.

[0049] The front folded portion 25 and the rear folded portion 26 extend linearly in parallel to the left-right direction. A gap 27 of a constant width Db is formed between the front folded portion 25 and the rear folded portion 26.

[0050] The Thomson blade 12 is disposed upright with the cutting edge 28 facing upward. The Thomson blade 12 integrally comprises a lower base portion 29 having a constant thickness Tb, and an upper blade portion 30 whose thickness gradually decreases from the upper end of the base portion 29 toward the cutting edge 28. The Thomson blade 12 of this embodiment is a center blade type, and the cutting edge 28 is located exactly halfway through the thickness Tb. It goes without saying that the base portion 29, the blade portion 30, and the cutting edge 28 are provided over the entire length of the Thomson blade 12.

[0051] In this embodiment, the thickness Tb of the Thomson blade 12 is a general-purpose size of 0.45 mm. Another general-purpose size of 0.7 mm is also preferable. The length Ab of the Thomson blade 12 in the folded-back state is 30.225 mm, and the width Bb is 1.05 mm. The height Cb of the Thomson blade 12 is set to be greater than the depth Cg of the cutting groove 13, and is set to a height such that the entire blade portion 30 and the upper end of the base portion 29 protrude upward from the cutting groove 13, as shown in FIG. 4(B).

[0052] 7 shows the spacer 14 alone, in which (A) is a plan view and (B) is a front cross-sectional view (a cross-sectional view taken along line VIIb-VIIb in (A)).

[0053] The spacer 14 is formed of a plate or sheet made of metal (especially iron or stainless steel). In this embodiment, the spacer 14 is formed by cutting a commercially available shim tape to a predetermined length. The material of the spacer 14 is not limited to metal, and may be plastic or the like.

[0054] The spacer 14 is a rectangular plate that is elongated linearly in the left-right direction. The spacer 14 is arranged upright so that its thickness Ts direction coincides with its width Bs direction (front-rear direction). The thickness Ts of the spacer 14 is set equal to the width Db of the gap 27. The length As of the spacer 14 is set equal to the lengths of the front-fold portion 25 and the rear-fold portion 26.

[0055] 4(B), the spacer 14 is disposed between the front and rear folded portions 25 and 26 of the Thomson blade 12, and disposed in the gap 27 between them. This allows the spacer 14 to accurately position both portions 25 and 26, and prevents both portions 25 and 26 from collapsing toward each other (toward the center of the width Bb of the Thomson blade 12) during hole drilling. In this sense, the spacer 14 constitutes a reinforcing plate.

[0056] In this embodiment, the width Bs and thickness Ts of the spacer 14 are equal to the width Db of the gap 27, which is set to 0.15 mm. The height Cs of the spacer 14 is equal to the depth Cg of the cutting edge groove 13.

[0057] The thickness Tb of the Thomson blade 12 is 0.45 mm, and the thickness Ts of the spacer 14 is 0.15 mm. Adding a clearance of 0.01 mm to this, the width Bg of the cutting groove 13 is 0.45+0.45+0.15+0.01=1.06 mm.

[0058] The length Ag of the cutting groove 13 is equal to the sum of the length of the ventilation hole 4 (A=30 mm), half the thickness Tb of the Thomson blade 12 (Tb / 2=0.45 / 2=0.225 mm), and the clearance (0.01 mm), which is 30.235 mm.

[0059] The Thomson die 10 is assembled as follows. First, the Thomson blade 12 in a folded state and the spacer 14 cut to a predetermined length As are prepared, and the spacer 14 is sandwiched between the Thomson blade 12 in advance. These are then inserted or pressed together into the blade groove 13 of the base plate 11. The base plate 11 is attached to the base plate holder 19 before or after this insertion. The insertion brings the entire lower end of the Thomson blade 12 into contact with the base plate 11. This allows the height position of the cutting edge 28 of the Thomson blade 12 to be accurately positioned, and makes it possible to suppress variation in the height position.

[0060] As shown in Fig. 4(A), in the assembled Thomson die 10, the shape of the cutting edge 28 matches the shape of the slit 6 in the lid 3. In other words, the cutting edge 28 and the blade portion 30 including the cutting edge 28 form the slit 6 in the lid 3. The distance Bt (see Fig. 6(B)) between the cutting edges 28 of the front-folded portion 25 and the rear-folded portion 26 is equal to the width B of the slit 6.

[0061] As shown in Fig. 8, in the hole processing step, the Thomson die 10 is fixed to the lower die (not shown) of a press machine, while the lid 3 is fixed to the lower surface of an upper die 31 of the press machine which can be raised and lowered. The upper die 31 is then lowered, and the lid 3 is brought close to the Thomson die 10. The figure shows a state immediately before the blade portion 30 of the Thomson blade 12 cuts into the lid 3. Note that, contrary to the illustrated example, the Thomson die 10 may be fixed to the upper die 31, and the lid 3 may be fixed to the lower die.

[0062] 9 shows the state when the upper die 31 is further lowered, the lid 3 is pressed against the blade portion 30 of the Thomson blade 12, and the lid 3 is completely cut. At this time, the blade tip 28 of the Thomson blade 12 comes into contact with the upper die 31, and a U-shaped vent hole 4, valve 5, and slit 6 are simultaneously formed in the lid 3. In the figure, the part of the lid 3 sandwiched between the blade portions 30 of the front and rear folded portions 25 and 26 is the valve 5. In this way, the vent hole 4 and the like can be easily formed by a single downward movement.

[0063] In this manner, according to the manufacturing method of this embodiment, the vent hole 4 with the valve 5 can be suitably formed in the lid 3.

[0064] In particular, the folded Thomson blade 12 is inserted into one cutting groove 13. This ensures the formation of a slit 6 with a small width B equal to the distance Bt between the cutting edges 28 of the front and rear folded portions 25 and 26. This is extremely effective in miniaturizing the ventilation hole 4 and in preventing the intrusion of dust and other particles.

[0065] Since the lid 3 is only cut with a slit 6 and is not completely punched out, no punching waste is generated and it is possible to prevent the punching waste from being mixed in the container by mistake.

[0066] In this embodiment, the blade tip interval Bt determines the width B of the slit 6 and therefore the air hole 4 etc. The size of the blade tip interval Bt can be set arbitrarily, and can also be made smaller as described later.

[0067] In this embodiment, the length A of the ventilation hole 4 is made larger than the width B thereof to form an elongated ventilation hole 4. This increases the area of ​​the ventilation hole 4, facilitating the discharge of water vapor and the like. Even in this case, the width B of the ventilation hole 4 is small, and the valve 5 closes the ventilation hole 4, so that the intrusion of dust and the like can be suppressed. The valve 5 also has an elongated shape, so that the valve 5 can be easily opened when discharging water vapor and the like.

[0068] In this embodiment, the base plate 11 is made of metal, and the Thomson blade 12 is detachably inserted into the cutting groove 13. Therefore, when the Thomson blade 12 deteriorates or breaks, it can be replaced, reducing running costs. Because the base plate 11 is made of metal, deformation of the cutting groove 13 can be prevented even if the Thomson blade 12 is repeatedly inserted and removed.

[0069] In addition, materials other than metal such as wood and resin may be used as the material of the base plate, in which case the Thomson blade is generally attached by press-fitting into the blade groove. Wood, resin, etc. are fragile, and when the Thomson blade is inserted and then removed, the groove width of the blade groove becomes wider and the Thomson blade cannot be fixed properly. Therefore, when the Thomson blade 12 deteriorates, the entire base plate must be replaced, which tends to increase running costs. This embodiment can solve such problems.

[0070] Incidentally, with a normal Thomson die, it is practically impossible to create a narrow vent hole 4 with width B as in this embodiment. With a normal Thomson die, when the Thomson blade is folded back, the blade groove must also be folded back along the folded shape. However, a wall with a thickness of only about the spacer thickness Ts (0.15 mm) is formed between the pre-fold and post-fold parts of the blade groove. This thin wall is highly likely to collapse during use, leading to the above conclusion.

[0071] Next, modified examples of the present disclosure will be described. Note that a description of the same parts as those in the basic embodiment will be omitted, and the following description will focus mainly on the differences from the basic embodiment.

[0072] [First Modification] 10 shows the Thomson blade 12 of the first modified example alone. (A) is a plan view, and (B) is a front cross-sectional view (Xb-Xb cross-sectional view of (A)).

[0073] In this first modified example, the spacer 14 and the gap 27 are omitted, and the Thomson blade 12 is folded back so that the front folded portion 25 and the rear folded portion 26 are in close contact with each other. This minimizes the blade tip interval Bt, which is smaller than that of the basic embodiment by the spacer thickness Ts (0.15 mm), and allows the width B of the ventilation hole 4, etc. to be made smaller. Incidentally, the Thomson blade 12 is a center blade type similar to that of the basic embodiment.

[0074] The width Bb of the Thomson blade 12 in this modification is also smaller than that of the basic embodiment by the spacer thickness Ts. The length Ab of the Thomson blade 12 is the same as that of the basic embodiment. In accordance with the change in size of the Thomson blade 12, the size of the cutting groove 13 of the base plate 11 is also changed.

[0075] According to this modification, the width B of the ventilation holes 4 etc. can be made smaller, which is even more advantageous in preventing the intrusion of dust and the like.

[0076] [Second modified example] 11 shows the Thomson blade 12 of the second modified example alone. (A) is a plan view, and (B) is a front cross-sectional view (XIb-XIb cross-sectional view of (A)).

[0077] In the second modified example, a gap 27 similar to that in the basic embodiment is provided, and a spacer 14 is inserted therein. However, the Thomson blade 12 is a single-edged type different from that in the basic embodiment, and as a result, the blade tip distance Bt is made smaller than that in the basic embodiment.

[0078] That is, in the Thomson blade 12 of this modification, the blade tip 28 is not exactly at the halfway point 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. In this modification, the Thomson blade 12 is folded back so that the offset side of the pre-folded portion 25 and the offset side of the post-folded portion 26 approach each other.

[0079] By using a single-edged blade in this manner, the blade tip distance Bt can be made smaller than in the basic embodiment while maintaining the basic shape of the Thomson blade 12 similar to that of the basic embodiment.

[0080] In the first modified example described above, in order to make the blade tip distance Bt smaller than in the basic embodiment, the folded-back portion 24 must be bent more tightly than in the basic embodiment, and the radius of curvature of the folded-back portion 24 must be made smaller. However, this increases the risk of breakage due to bending.

[0081] On the other hand, in this modified example, the blade tip interval Bt can be reduced without sharply bending the folded-back portion 24. This reduces the risk of breakage due to bending the folded-back portion 24. According to this modified example, a blade tip interval Bt smaller than that of the basic embodiment can be achieved with the same degree of bending as in the basic embodiment.

[0082] In this way, it is preferable to use an appropriate type of Thompson blade 12 depending on the width B of the ventilation hole 4 or the like, and to determine whether or not to use the spacer 14.

[0083] Figure 12 shows some examples of the types of Thompson blades 12 that can be used in this embodiment. (A) shows a center blade type similar to that of the basic embodiment. (B) shows another type of center blade type in which the blade angle θ is larger than that of (A) and the length of the blade portion 30 is shorter. (C) shows a single-blade type similar to the second modified example, with the left side in the figure being the offset direction. Note that a short blade surface 30X is also formed on the offset side from the cutting edge 28.

[0084] (D) shows a two-stage blade type. The blade portion 30 has, in order from the cutting edge 28 side, a first blade portion 30A with a large blade angle θ1 and a second blade portion 30B with a small blade angle θ2. The position of the cutting edge 28 is the same as that of the center blade type.

[0085] (E) shows a three-stage blade type. The blade portion 30 has, in order from the cutting edge 28 side, a first blade portion 30A with the largest blade angle θ1, a second blade portion 30B with an intermediate blade angle θ2, and a third blade portion 30C with the smallest blade angle θ3. The position of the cutting edge 28 is the same as that of the center blade type.

[0086] (F) shows a single-sided two-stage blade type, with the left side of the figure being the offset direction. The blade portion 30 has, in order from the cutting edge 28 side, a first cutting edge portion 30A with a large cutting edge angle θ1 and a second cutting edge portion 30B with a small cutting edge angle θ2. A short cutting edge 30X is also formed on the offset side from the cutting edge 28.

[0087] [Third Modification] 13 shows a Thomson mold 10 of a third modified example, in which (A) is a plan view and (B) is a front cross-sectional view (XIIIb-XIIIb cross-sectional view of (A)).

[0088] In this modified example, multiple (specifically, three) Thomson blades 12 sandwiching a spacer 14 as described in the basic embodiment are arranged in parallel in the width direction (front-to-back direction) and inserted into one blade groove 13.

[0089] Figure 14 shows the base plate 11 in this Thomson die 10. (A) is a plan view, and (B) is a front cross-sectional view (cross-sectional view taken along XIVb-XIVb in (A)). As shown in the figure, the shape of the cutting groove 13 is modified to match the overall outer shape of the three Thomson blades 12 arranged in parallel and adjacent to each other. The width Bg of the cutting groove 13 is three times the width Bg of the basic embodiment shown in Figure 5. The tip (left end) 16 of the cutting groove 13 is shaped in plan view as three semicircles continuing in the width Bg direction.

[0090] By using such a Thomson die 10, three parallel ventilation holes 4, etc. can be simultaneously formed in the lid 3 in a single hole processing step, as shown in Figure 15, thereby improving processing efficiency.

[0091] Moreover, like the width B of the ventilation holes 4, the distance D between adjacent ventilation holes 4 can also be narrowed. This is effective when it is desired to form many ventilation holes 4 in a small area. Note that, by inserting a spacer (not shown) between adjacent Thomson blades 12, the distance D between the ventilation holes 4 can also be widened.

[0092] [Fourth Modification] 16(A) to 16(C) are plan views showing a base plate 11 and a cutting groove 13, a Thomson blade 12, and a spacer 14 used in a Thomson die of a fourth modified example. This Thomson die is configured to form a wavy U-shaped ventilation hole 4 as shown in FIG.

[0093] The ventilation holes 4, etc. are obtained by modifying the straight U-shaped ventilation holes 4, etc. described in the basic embodiment (see FIG. 2) into a wavy U-shape. The length A and width B of the ventilation holes 4, etc. of this modification are the same as those of the basic embodiment. The ventilation holes 4, etc. of this modification are curved to describe one period of a wave shape while maintaining a constant width B.

[0094] As shown in Fig. 16(B), in the Thomson blade 12, the front folded portion 25 and the rear folded portion 26 of the Thomson blade 12 in the basic embodiment (see Fig. 6) are bent in a wavy shape in accordance with the shape of the ventilation hole 4, etc. Correspondingly, the cutting groove 13 and the spacer 14 are also bent in a wavy shape.

[0095] Such a corrugated vent hole 4 also has the same effect as described above because it is small in size and has a valve 5. Furthermore, according to this modification, vent holes 4 of different designs can be easily created by only making slight improvements to the Thomson type of the basic embodiment.

[0096] It will be easily understood that vent holes 4 and the like having a jagged shape similar to this wave shape can also be easily created.

[0097] [Fifth Modification] 18(A) to 18(C) are plan views of a base plate 11 and a cutting groove 13, a Thomson blade 12, and a spacer 14 used in a Thomson die of a fifth modified example. This Thomson die is configured to form a cross-shaped vent hole 4, a valve 5, and a slit 6 as shown in FIG.

[0098] These vents 4 etc. have a length A and a width B (A>B). The vents 4 etc. have a first extension 32 extending in the length A direction and a second extension 33 extending in the width B direction and perpendicular to the first extension 32. The first extension 32 has a length Aa equal to the length A of the vents 4 etc. and a width Ba smaller than the width B of the vents 4 etc. These length Aa and width Ba are equal to the length A and width B of the basic embodiment shown in FIG. 2. The second extension 33 has a length Ab equal to the width B of the vents 4 etc. and a width Bb equal to the width Ba of the first extension 32. The length Aa of the first extension 32 is longer than the length Ab of the second extension 33. The vents 4 etc. are formed symmetrically with respect to the center of the width B.

[0099] In order to form the ventilation holes 4 and the like, the Thomson blade 12 is folded three times to form a cross shape, as shown in Fig. 18(B). The Thomson blade 12 has first, second and third folded portions 24A, 24B and 24C, corresponding first, second and third folded front portions 25A, 25B and 25C, and first, second and third folded back portions 26A, 26B and 26C. The first folded back portion 26A is common to the second folded front portion 25B, and the second folded back portion 26B is common to the third folded front portion 25C.

[0100] As it moves from the base end 22 side to the tip end 23 side, the first folded front portion 25A moves from the base end 22 to the right side and is bent at a right angle toward the rear side along the way. The Thomson blade 12 is then folded back 180° toward the front side to form the first folded back portion 24A. The first folded back portion 26A (second folded front portion 25B) is then bent at a right angle toward the right side. The Thomson blade 12 is then folded back 180° toward the left side to form the second folded back portion 24B.

[0101] Similarly, the second folded back portion 26B (third folded back portion 25C) is bent at a right angle toward the front. The Thomson blade 12 is then bent 180° toward the rear to form the third folded back portion 24C. The third folded back portion 26C is bent at a right angle toward the left and reaches the tip 23.

[0102] The cutting groove 13 is also formed in a cross shape following the external shape of this cross-shaped Thomson blade 12. A cross-shaped gap 27 is formed inside the Thomson blade 12, and a cross-shaped spacer 14 is inserted into this gap 27. The spacer 14 is made by cutting a metal plate (e.g., a steel plate) having the same thickness as the height Cs (see FIG. 7(B)) into a cross shape by wire electric discharge machining.

[0103] The cross-shaped vent 4 created using this Thomson die is still small in size and has a valve 5, so it can achieve the same effect as above. As can be seen from this modification, the manufacturing method of this embodiment allows for a high degree of freedom in the design of the vent 4, etc., and can easily create vents 4 with relatively complex shapes. This greatly improves the commercial value of the lid 3.

[0104] Regarding the shape of the ventilation holes 4 etc., other complex shapes (for example, an asterisk shape) are also possible.

[0105] 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 lid 3 does not necessarily have to be transparent, and may be opaque. The above numerical values ​​are merely examples and may be changed as appropriate.

[0106] The configurations of the basic embodiment and each of the modified examples described above can be combined in part or in whole, unless there is a particular contradiction. For example, a combination of the first modified example (FIG. 10) and the third modified example (FIG. 13), a combination of the second modified example (FIG. 11) and the third modified example (FIG. 13), a combination of the third modified example (FIG. 13) and the fourth modified example (FIG. 16), a combination of the first or second modified example (FIG. 10 or FIG. 11) and the fourth modified example (FIG. 16), etc. are possible.

[0107] 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]

[0108] 1 Food containers 3 Lid 4 Ventilation holes 5 Valves 6. Break 10 Thomson type 11 Base plate 12 Thomson blade 13. Cutting groove 14 Spacer 22 Proximal end 23 Tip 24 Folding part 25 Front fold 26 After fold

Claims

1. A method for manufacturing a lid for a disposable food container, comprising: a hole processing step of simultaneously forming an air hole in the lid and a cantilever-shaped valve that closes the air hole in an openable and closable manner by making a cut in the lid using a Thomson die; The Thomson type is A base plate; Thomson blade, a cutting groove provided on the base plate and into which the Thomson cutting blade is inserted; Equipped with The Thomson blade is inserted into the blade groove in a state where it is folded back at least once, The cutting groove has a width equal to or greater than the sum of twice the thickness of the Thomson cutting edge and the clearance. A method for manufacturing a lid comprising the steps of:

2. The Thomson blade has a front folded portion, a folded portion, and a rear folded portion that are arranged in this order from one end side to the other end side in the longitudinal direction. A method for manufacturing the lid according to claim 1.

3. A gap is formed between the front folded portion and the rear folded portion, the Thomson die includes a spacer disposed in the gap and sandwiched between the front folded portion and the rear folded portion; The spacer constitutes a reinforcing plate that prevents the front and rear folded portions from collapsing toward each other during hole drilling. A method for manufacturing the lid according to claim 2.

4. The Thomson blade is folded back so that the front folded portion and the rear folded portion are in close contact with each other. A method for manufacturing the lid according to claim 2.

5. The Thomson blade is a single-edged blade, and is folded back so that the offset side of the folded front portion and the offset side of the folded rear portion approach each other. A method for manufacturing the lid according to any one of claims 2 to 4.

6. The Thompson blade is folded once in a U-shape to form the U-shaped vent and valve. A method for manufacturing the lid according to any one of claims 1 to 5.

7. The Thompson blade is folded once in a U-shape and bent in a wavy manner to form the vent and the valve in a wavy U-shape. A method for manufacturing the lid according to any one of claims 1 to 5.

8. A plurality of the Thomson blades are inserted into the cutting groove in a state of being arranged in parallel. A method for manufacturing a lid according to any one of claims 1 to 7.

9. The Thompson blade is folded three times in a cross shape to form the vent and the valve in a cross shape. A method for manufacturing the lid according to any one of claims 1 to 5.

10. A Thomson die for simultaneously forming an air hole in a lid of a disposable food container and a cantilever valve for opening and closing the air hole by making a slit in the lid, A base plate; Thomson blade, a cutting groove provided on the base plate and into which the Thomson cutting blade is inserted; Equipped with The Thomson blade is inserted into the blade groove in a state where it is folded back at least once, The cutting groove has a width equal to or greater than the sum of twice the thickness of the Thomson cutting edge and the clearance. The Thomson type is characterized by

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