Packing box
The packaging box design with a convex auxiliary fold line addresses stability issues by concentrating load on corners, enhancing frictional force, and improving manufacturing efficiency.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOMOKU CO LTD
- Filing Date
- 2022-04-28
- Publication Date
- 2026-06-23
AI Technical Summary
Conventional packaging boxes with straight-line fold lines face issues with stability when stacked due to interference between outer and inner flaps, leading to tilting and sliding, and require additional crease lines to mitigate buckling resistance.
A packaging box design with a convex auxiliary fold line on the outer flap fold line side, allowing the outer flap to be folded along this line, reducing interference and creating a shape where the corners protrude and the center is recessed, enhancing frictional force and stability.
The design improves stacking stability by concentrating load on the corners, reducing tilting and sliding, and allows for easy manufacturing without special equipment, potentially reducing material thickness and manufacturing costs.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a packaging box for accommodating various articles.
Background Art
[0002] Conventionally, as a packaging box for accommodating various articles, a grooved packaging box formed (assembled) by folding a single blank sheet provided with a plurality of grooves (slits) cut from an end has been widespread. In this grooved type, a cylindrical body portion is formed by adhering an overlap provided at an end portion of the blank sheet where no groove is formed to the opposite end portion, and at least one of the openings at both axial ends of the body portion is closed by folding the flaps formed by the grooving.
[0003] Normally, in this grooved type, the body portion is configured in a square cylindrical shape in which a pair of first side plates facing each other and a pair of second side plates facing each other are connected via a body fold line. And the closing portion is composed of a pair of outer flaps connected to the pair of first side plates via an outer flap fold line and a pair of inner flaps connected to the pair of second side plates via an inner flap fold line. After folding the pair of inner flaps inward along the inner flap fold line, the pair of outer flaps are folded inward along the outer flap fold line and overlapped on the inner flaps so that the opening of the body portion is closed.
[0004] Also, in this grooved type, usually, by providing the outer flap fold line and the inner flap fold line on the blank sheet in a straight line, the formation of these fold lines is facilitated and the productivity is improved. However, when the outer flap fold line and the inner flap fold line are provided in a straight line, the folding of the outer flap is hindered by interference with the inner flap. For this reason, it becomes difficult to connect the tip portions of the pair of outer flaps to each other and fix them to the body portion with an adhesive tape, and even after fixing with the adhesive tape, the tip portions of the pair of outer flaps protrude, and the closing portion bulges in a roof shape, resulting in a problem that the stacking of the packaging boxes becomes unstable.
[0005] Conventionally, to address this problem, a so-called staggered crease line has been employed, in which the outer flap crease line is offset from the inner flap crease line by the thickness of the material. In addition, methods such as providing an auxiliary crease line parallel to the outer flap crease line on the outer flap (see, for example, Patent Document 1) have also been proposed. [Prior art documents] [Patent Documents]
[0006] [Patent Document 1] Japanese Public Gazette No. 62-9213 [Overview of the project] [Problems that the invention aims to solve]
[0007] However, while the packaging box described in Patent Document 1 solves the problem of reduced buckling resistance in the first side panel caused by the stepped crease by providing auxiliary fold lines instead of the stepped crease, it still has the problem of not being very stable when stacked. In other words, the packaging box described in Patent Document 1 only suppresses tilting of the packaging box by making the closing part almost flat, and does not suppress sliding between the upper and lower packaging boxes.
[0008] In view of these circumstances, the present invention aims to provide a packaging box that can improve stability when stacked. [Means for solving the problem]
[0009] The present invention relates to a packaging box having a cylindrical body and a closing portion that closes one of the two open ends of the body, wherein the body has a pair of first side plates facing each other and a pair of second side plates facing each other in a direction intersecting the opposing direction of the pair of first side plates, and the closing portion has a pair of outer flaps connected to the first side plates via an outer flap fold line and folded inward along the outer flap fold line, and a pair of inner flaps connected to the second side plates via an inner flap fold line and folded inward along the inner flap fold line, wherein the pair of outer flaps have an auxiliary fold line on the outer flap fold line side that is convex on the outer flap fold line side.
[0010] According to the packaging box of the present invention, while the outer flap fold line and the inner flap fold line are aligned in a straight line, the outer flap is folded along the auxiliary fold line, which not only reduces interference between the outer and inner flaps but also allows the closing portion to have a shape in which the vicinity of the four corners protrudes and the central portion is relatively recessed. This not only prevents the tilting of the packaging box placed on top of the packaging box, but also concentrates the load on the protruding portions near the four corners of the closing portion, increasing the frictional force between the upper and lower packaging boxes and suppressing slippage between them. In other words, the stability when stacked can be improved to a greater extent than before.
[0011] Furthermore, in the packaging box of the present invention, it is preferable that the auxiliary fold line has a portion that is separated from the outer flap fold line by a distance greater than the thickness of the outer flap.
[0012] According to this method, the repulsive force of the inner flap interfering with the outer flap, which was the cause of the conventional problem, can be effectively utilized to further improve productivity and stability when stacking. Specifically, when folding the outer flap along the outer flap fold line during box making, it becomes possible to bring both ends of the previously folded inner flap into contact with the area between the outer flap fold line and the auxiliary fold line on the outer flap. As a result, the repulsive force of the inner flap can be applied in the direction of folding the outer flap into a mountain fold along the auxiliary fold line.
[0013] This allows for easy box manufacturing without requiring special procedures or equipment, as the outer flap is already folded along the auxiliary fold line. Furthermore, the repulsive force of the inner flap helps maintain the folded state of the outer flap along the auxiliary fold line even after box manufacturing, thus providing a stable anti-slip effect.
[0014] Furthermore, in the packaging box of the present invention, it is preferable that the distance from the outer flap fold line to the tip of the pair of outer flaps is set such that when the pair of outer flaps are folded in a mountain fold along the auxiliary fold line, their tips abut against each other.
[0015] According to this method, the pair of outer flaps, whose ends are butted together, support each other, so that the folded state at the auxiliary fold line of the outer flaps is maintained even after box manufacturing, thus providing a stable anti-slip effect. [Effects of the Invention]
[0016] The packaging box of the present invention offers the excellent effect of improving stability when stacked. [Brief explanation of the drawing]
[0017] [Figure 1] This is a schematic perspective view of a packaging box according to one embodiment of the present invention. [Figure 2] This is a diagram of the packaging box. [Figure 3] Figures A and B are schematic diagrams showing multiple packaging boxes stacked vertically, viewed from the side. [Figure 4] This is a schematic diagram showing multiple packaging boxes stacked vertically, viewed from the side. [Figure 5] Figure A is a schematic diagram viewed from the side, showing a typical packaging box with a roof-like bulge at the closure, stacked on top of another packaging box. Figure B is a schematic diagram viewed from the side, showing a packaging box with staggered lines, stacked on top of another packaging box. [Figure 6] Figures A through D are schematic diagrams showing variations of the auxiliary fold lines.
Best Mode for Carrying Out the Invention
[0018] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic perspective view of a packaging box 1 according to an embodiment of the present invention, FIG. 2 is an exploded view of the packaging box 1, and shows the surface of a blank sheet 1x before the packaging box 1 is formed into a box.
[0019] The packaging box 1 of the present embodiment is a grooved type also called the A type or the A-1 type, and is made of double-sided corrugated cardboard composed of a surface liner, a back liner, and a core. The packaging box 1 is formed into a box shape (assembled) by bending a flat blank sheet 1x formed by making grooves and ruled lines in the double-sided corrugated cardboard.
[0020] As shown in FIG. 1, the packaging box 1 includes a rectangular tube-shaped body 10, and two closing parts 20a and 20b that close two open ends 10a at both ends in the axial direction (vertical direction in FIG. 1) of the body 10. In the present embodiment, similar to the normal grooved type, since the axial direction of the body 10 is the vertical direction, the closing part 20a constitutes the top plate of the packaging box 1, and the closing part 20b constitutes the bottom plate.
[0021] The body 10 is composed of a pair of first side plates 11 facing each other, and a pair of second side plates 12 facing each other in a direction substantially orthogonal to the facing direction of the pair of first side plates 11. Therefore, the pair of second side plates 12 connect the pair of first side plates 11 at both ends in the circumferential direction, and the pair of first side plates 11 connect the pair of second side plates 12 at both ends in the circumferential direction. The first side plate 11 and the second side plate 12 are each configured as a rectangular plate having different dimensions in the circumferential direction of the body 10. In the present embodiment, the one with the longer dimension in the circumferential direction is defined as the first side plate 11.
[0022] The closing sections 20a and 20b consist of a pair of outer flaps 21 and a pair of inner flaps 22 that are superimposed on the inside of the pair of outer flaps 21. The outer flaps 21 and inner flaps 22 are each made up of rectangular plates with different dimensions in the circumferential direction of the body 10. In this embodiment, the longer circumferential dimension is designated as the outer flap 21, and the shorter dimension is designated as the inner flap 22.
[0023] The closing sections 20a and 20b are configured to close the entire open end 10a by closing the pair of outer flaps 21 with their tips 21a in contact (butted against each other). In this embodiment, the tips 22a of the inner flaps 22 do not contact each other, as is the case with conventional grooved types, but they may be made to contact each other.
[0024] As shown in Figure 2, in the blank sheet 1x, the first side plate 11 and the second side plate 12 are arranged alternately in the X direction (left-right direction in Figure 2), which is the circumferential direction of the body portion 10. In this embodiment, the first side plate 11 and the second side plate 12 are arranged in the order of first side plate 11, second side plate 12, first side plate 11, second side plate 12 from left to right in Figure 2, and a joint 15 is placed to the left of the leftmost first side plate 11. This joint 15 is bonded to the rightmost second side plate 12 to form a cylindrical body portion 10.
[0025] The outer flaps 21 are positioned on both sides (upper and lower sides in Figure 2) of the blank sheet 1x in the Y direction (up and down direction in Figure 2), which is perpendicular to the X direction with respect to the first side plate 11. The inner flaps 22 are positioned on both sides of the blank sheet 1x in the Y direction relative to the second side plate 12. Therefore, one side of the blank sheet 1x in the Y direction is provided with a pair of outer flaps 21 and a pair of inner flaps 22 that constitute the closure section 20a, while the other side is provided with a pair of outer flaps 21 and a pair of inner flaps 22 that constitute the closure section 20b.
[0026] The first side plate 11, the second side plate 12, and the joint 15 are connected to each other via the body fold line a when adjacent to each other. The outer flap 21 is connected to the first side plate 11 via the outer flap fold line b1, and the inner flap 22 is connected to the second side plate 12 via the inner flap fold line b2. The outer flap 21 and the inner flap 22 are also separated from each other in the X direction by slit-shaped grooves 23 cut from three locations at both ends of the blank sheet 1x in the Y direction, extending in the Y direction.
[0027] In other words, the first side plate 11, the second side plate 12, the joint 15, the outer flap 21, and the inner flap 22 are defined by the body fold line a, the outer flap fold line b1, the inner flap fold line b2, and the groove 23 provided on the blank sheet 1x.
[0028] The fold line a on the body is intended to form the body 10 into a rectangular tube shape when folded during box manufacturing. The fold line a on the body is provided on a straight line extending in the Y direction, connecting the inner ends of adjacent grooves 23 in the Y direction.
[0029] The outer flap fold line b1 and the inner flap fold line b2 are for folding the outer flap 21 and the inner flap 22 during box manufacturing to form the closed portions 20a and 20b. The outer flap fold line b1 and the inner flap fold line b2 are provided on a straight line extending in the X direction so as to connect the inner ends of adjacent grooves 23 in the X direction.
[0030] In this embodiment, similar to a typical grooved packaging box, the outer flap fold line b1 and the inner flap fold line b2 are aligned in a straight line on both sides in the Y direction. An auxiliary fold line c is provided near the outer flap fold line b1 on each outer flap 21, and when the outer flap 21 is folded along the outer flap fold line b1, it is also folded along the auxiliary fold line c in a mountain fold (so that the surface side is convex), thereby reducing interference between the outer flap 21 and the inner flap 22.
[0031] However, simply providing an auxiliary fold line c that extends in the Y direction parallel to the outer flap fold line b1, as in the conventional method, would not significantly improve the stability when stacking the packaging boxes 1; in other words, there is a possibility that a packaging box 1 placed on top of another packaging box 1 could slide off.
[0032] As will be described in detail later, in this embodiment, an auxiliary fold line c extending in the Y direction (the direction connecting both ends 21b) is provided along a line where the outer flap fold line b1 side (first side plate 11 side) is convex, thereby actively enhancing stability when stacked. More specifically, the auxiliary fold line c is provided along a curved arc that connects both ends 21b of the outer flap 21 and where the outer flap fold line b1 side is convex.
[0033] Therefore, the auxiliary fold line c is closest to the outer flap fold line b1 at its intermediate position. Furthermore, the auxiliary fold line c gradually moves away from the outer flap fold line b1 from its intermediate position toward both ends 21b of the outer flap 21, and is furthest away from the outer flap fold line b1 at both ends where it reaches both ends 21b of the outer flap 21.
[0034] In this embodiment, the distance L1 between the auxiliary fold line c and the outer flap fold line b1 at the midpoint of the auxiliary fold line c (shortest distance) is set to be approximately the same as the thickness of the corrugated cardboard material. Furthermore, the distance L2 between the auxiliary fold line c and the outer flap fold line b1 at both ends of the auxiliary fold line c (longest distance) is set to be approximately four times L1.
[0035] In this way, by separating the auxiliary fold line c from the outer flap fold line b1 by at least the thickness of the material, both ends 22b of the inner flap 22 can be brought into contact with the area between the outer flap fold line b1 and the auxiliary fold line c on the back surface of the outer flap 21. This makes it possible to apply the repulsive force (restoring force of elastic deformation) of the inner flap 22 in the direction of bending the outer flap 21 at the auxiliary fold line c when the outer flap 21 is folded at the outer flap fold line b1.
[0036] Furthermore, in this embodiment, the distance L3 from the outer flap fold line b1 to the tip 21a of the outer flap 21 is set to be greater than half the distance L4 between the two body fold lines a on the second side plate 12, so that the pair of outer flaps 21 support each other by abutting their tips 21a together, thereby maintaining the auxiliary fold line c in a mountain fold state. In other words, the distance L3 is set to the distance at which, when the pair of outer flaps 21 are folded along the outer flap fold line b1, the tips 21a of the outer flaps 21 abut against each other in a mountain fold state along the auxiliary fold line c.
[0037] Furthermore, the body fold line a, the outer flap fold line b1, and the inner flap fold line b2 are formed from creased lines provided on the back surface of the blank sheet 1x (the surface that becomes the inner surface of the packaging box 1), similar to a typical grooved packaging box. In this embodiment, the auxiliary fold line c is also formed from creased lines provided on the back surface of the blank sheet 1x.
[0038] The box making process for packaging box 1 is the same as for general packaging boxes. Specifically, adhesive is first applied to the surface of the joint 15, and then the first side panels 11 and the second side panels 12 at both ends in the X direction are folded along the body fold line a, and the joint 15 is glued to the back surface of the second side panel 12, forming a cylindrical body in a folded state of two layers. This process is usually performed by machine, along with printing, scribing, and grooving. Subsequent processes may be performed by hand or by machine.
[0039] Next, the cylindrical body is folded along the fold line a of the body that has not been folded, and the pair of first side plates 11 are separated from each other to form a rectangular cylindrical body 10. Then, one of the pair of inner flaps 22 and the pair of outer flaps 21 on either side in the axial direction are folded inward along the inner flap fold line b2 and the outer flap fold line b1 in that order and fixed with adhesive tape or the like, closing one of the open ends 10a. This forms the closed portion 20b that constitutes the bottom plate.
[0040] Afterward, once the contents are placed inside the body 10 from the open top side, the inner flap 22 and outer flap 21 on the top side are folded in the same way as on the bottom side and secured with adhesive tape or the like to close the other open end 10a. This forms the closed portion 20a that constitutes the top, and the packaging box 1 is completed.
[0041] In this embodiment, as described above, the reaction force of the inner flap 22 acts in the direction that bends the outer flap 21 at the auxiliary fold line c. Therefore, when the outer flap 21 is bent at the outer flap fold line b1, it also bends naturally at the auxiliary fold line c. Consequently, the packaging box 1 does not require any special procedures or equipment for bending the outer flap 21 at the auxiliary fold line c, and can be manufactured using a general grooved packaging box machine.
[0042] Furthermore, as the outer flap 21 bends along the auxiliary fold line c, interference between the outer flap 21 and the inner flap 22 is reduced, and the tip 21a of the outer flap 21 sinks toward the body 10. This prevents roof-like bulging in the closed sections 20a and 20b. Also, since the tip 21a of the outer flap 21 is close to the inner flap 22, it is possible to easily attach adhesive tape or the like when forming the closed sections 20a and 20b.
[0043] Furthermore, since the auxiliary fold line c is provided along a line that is convex on the outer flap fold line b1 side, the distance between the auxiliary fold line c and the outer flap fold line b1 is greater at both ends (both ends 21b of the outer flap 21) than in the middle. As a result, the closing portions 20a and 20b of the packaging box 1 have a shape in which the vicinity of the four corners protrude in a triangular pyramidal shape, and the central part is recessed relative to this. In this embodiment, by configuring the closing portions 20a and 20b in this shape with the auxiliary fold line c, the stability of the packaging box 1 when stacked is actively enhanced.
[0044] Figures 3A and 3B, and Figure 4 are schematic side views of multiple packaging boxes 1 stacked vertically. Figure 3A shows the view from the first side panel 11, while Figures 3B and 4 show the view from the second side panel 12.
[0045] By making the corners of the closure portions 20a and 20b protrude in a triangular pyramidal shape and the central portion relatively recessed, it is possible not only to prevent the packaging box 1 placed on top of the packaging box 1 from tilting, but also to concentrate the load on the closure portions 20a and 20b near the corners, as if they were provided with four legs. This makes it possible to locally increase the frictional force between the upper and lower packaging boxes 1 near the corners of the closure portions 20a and 20b, thereby suppressing relative slippage between them and further improving the stability when the packaging boxes 1 are stacked.
[0046] In particular, as shown in Figure 4, when a lateral force is applied to the stacked packaging boxes 1, the load on the side where the force is applied (left side of the figure) decreases, but the load on the opposite side (right side of the figure) increases. Therefore, even if the packaging boxes 1 are slightly tilted, the increased frictional force prevents them from collapsing.
[0047] Furthermore, as described above, in this embodiment, the repulsive force of the inner flap 22 is applied to fold the outer flap 21 along the auxiliary fold line c, and the pair of outer flaps 21 support each other by abutting their tips 21a together. Therefore, even when the weight of the packaging box 1 or the weight of its contents is large, the protruding parts near the four corners are less likely to be crushed, and it is possible to generate appropriate frictional force.
[0048] Thus, the packaging box 1 of this embodiment can be manufactured at low cost using existing machinery, while also actively enhancing stability when stacked. Furthermore, the improved frictional force of the closing sections 20a and 20b makes it possible to omit anti-slip hot melt adhesive or anti-slip sheets depending on the usage conditions, thereby further reducing manufacturing costs and improving handling during use.
[0049] Furthermore, in packaging box 1, the load is concentrated near the corners of the body section 10, rather than being concentrated on the first side panel 11 as in the case of a box with staggered creases. As a result, buckling resistance and strength are improved compared to conventional packaging boxes with staggered creases. Therefore, it is possible to obtain sufficient buckling resistance or strength even while using thinner material than, for example, a conventional packaging box with staggered creases, and further reductions in manufacturing costs are also possible.
[0050] Furthermore, packaging box 1 can be made more stable even when stacked together with conventional packaging boxes. Figure 5A is a schematic diagram viewed from the side showing a typical packaging box 100, in which the closing section 120 bulges out like a roof, stacked on top of packaging box 1, and Figure 5B is a schematic diagram viewed from the side showing a packaging box 200, which has staggered grid lines, stacked on top of packaging box 1, and
[0051] As shown in Figure 5A, the closing portions 20a and 20b of the packaging box 1 have a shape in which the central part is recessed relative to the vicinity of the four corners, thus complementing the roof-like bulge of the closing portion 120 of the packaging box 100. Therefore, when such a packaging box 100 is placed above or below the packaging box 1, the bulging portion of the closing portion 120 fits into and engages with the closing portion 20a or 20b, thereby suppressing lateral sliding. In this case as well, the protruding portions near the four corners of the closing portion 20a or 20b preferentially contact the closing portion 120, so that the load can be concentrated near the four corners and the frictional force can be increased.
[0052] As shown in Figure 5B, in a packaging box 200 with staggered lines, the closing portion 220 is in a substantially flat state. Even when such a packaging box 200 is placed above or below the packaging box 1, the protruding portions near the four corners of the closing portion 20a or 20b can be preferentially brought into contact with the closing portion 220, thereby concentrating the load near the four corners.
[0053] Thus, the packaging box 1 can enhance stacking stability not only when used in a single type, but also when a conventional packaging box 100 or 200 is placed on top of the packaging box 1, and when the packaging box 1 is placed on top of a conventional packaging box 100 or 200. This is particularly effective when stacked together with a packaging box 100 whose closure portion 120 bulges out.
[0054] Furthermore, in order to reliably achieve the above-mentioned effects, it is preferable that the position where the auxiliary fold line c is provided on the outer flap 21 is at least on the side of the outer flap fold line b1, that is, closer to the outer flap fold line b1 than the midpoint between the outer flap fold line b1 and the tip 21a, and the closer it is to the outer flap fold line b1, the more preferable. In addition, by providing the auxiliary fold line c in a position close to the outer flap fold line b1, it is possible to make it easier to fold the outer flap 21 at the auxiliary fold line c during box manufacturing.
[0055] Next, a modified example of the packaging box 1 will be described. Figures 6A to 6D are schematic diagrams showing modified examples of the auxiliary fold line c, and show the surface of the outer flap 21 on the blank sheet 1x.
[0056] The type of line along which the auxiliary fold line c follows is not particularly limited as long as the outer flap fold line b1 side is convex. Not only various curves such as parabolas and circular arcs, but also lines made up of multiple straight lines or lines made up of straight lines and curves can be used. Therefore, the auxiliary fold line c may follow a V-shaped line, as shown in Figure 6A, for example, or it may follow a line made up of a straight line parallel to the outer flap fold line b1 and a straight line (or curve) that is not parallel to it, as shown in Figure 6B.
[0057] Furthermore, the auxiliary fold line c may, for example, have an intermediate position that is in contact with the outer flap fold line b1, as shown in Figure 6C, or it may consist of two straight lines (or curves) that extend from the middle of the outer flap fold line b1 toward both ends 21b of the outer flap 21, gradually moving away from the outer flap fold line b1, as shown in Figure 6D. In cases such as when the tips 22a of the inner flaps 22 do not abut each other, or when it is expected that the tips 22a of the inner flaps 22 will sink into the body portion 10, the intermediate portion of the auxiliary fold line c does not necessarily need to be separated from the outer flap fold line b1.
[0058] In the example shown in Figure 6D, the auxiliary fold line c is divided into two parts, but it goes without saying that it is provided along the line that is convex to the outer flap fold line b1. In other words, the auxiliary fold line c may be provided intermittently or discontinuously. Furthermore, the auxiliary fold line c may not reach the side edge 21b of the outer flap 21.
[0059] In addition, although not shown in the illustration, the auxiliary fold line c may be wavy or zigzag in shape, following a line that is convex to the outer flap fold line b1. Furthermore, multiple auxiliary fold lines c, either parallel or non-parallel to each other, may be provided on a single outer flap 21.
[0060] Furthermore, the auxiliary fold line c may consist of continuous or intermittent half-cut lines or full-cut lines, in which case, for example, arc-shaped cuts may be intermittently arranged along a line that is convex to the outer flap fold line b1.
[0061] Furthermore, the packaging box 1 may have an auxiliary fold line c provided only on either the closing portion 20a that constitutes the top plate or the closing portion 20b that constitutes the bottom plate. In this case as well, the same effect as when used in combination with the conventional packaging box 100 can be achieved. Also, the packaging box 1 may have only one of the closing portion 20a or the closing portion 20b. Furthermore, the packaging box 1 may have a body portion 10 such as a hexagonal tube or an octagonal tube.
[0062] While embodiments of the present invention have been described above, the packaging box of the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, the dimensions and dimensional ratios of each part of the packaging box 1 are not particularly limited. Furthermore, the material of the packaging box 1 is not particularly limited and may be various types of corrugated cardboard other than double-sided corrugated cardboard, thick paper, various types of resin corrugated cardboard, or resin boards.
[0063] Furthermore, the actions and effects described in the embodiments described above are merely a list of the most preferred actions and effects resulting from the present invention, and the actions and effects according to the present invention are not limited to these. [Explanation of Symbols]
[0064] 1 packaging box 10 Torso 10a open end 11 1st side plate 12 Second side plate 20a, 20b Blocked area 21 Outer flap 21a Tip of the outer flap 22 Inner flap a. Fold line on the body b1 Outer flap fold line b2 Inner flap fold line c. Auxiliary fold line
Claims
1. A packaging box having a cylindrical body and a closing portion that closes one of the two open ends of the body, The body portion has a pair of first side plates facing each other, and a pair of second side plates facing each other in a direction intersecting the direction in which the pair of first side plates face each other, The closing portion has a pair of outer flaps connected to the first side plate via an outer flap fold line and folded inward along the outer flap fold line, and a pair of inner flaps connected to the second side plate via an inner flap fold line and folded inward along the inner flap fold line. The packaging box is characterized in that the pair of outer flaps have an auxiliary fold line provided along the line on the outer flap fold line side, where the outer flap fold line side is convex.
2. In the packaging box according to claim 1, The packaging box is characterized in that the auxiliary fold line has a portion that is separated from the outer flap fold line by a distance greater than the thickness of the outer flap.
3. In the packaging box according to claim 1, A packaging box characterized in that the distance from the outer flap fold line to the tip of the pair of outer flaps is set such that when the flaps are folded in a mountain fold along the auxiliary fold line, their tips abut against each other.