Packing box

Abstract

To provide a packing box capable of preventing the occurrence of unexpected buckling on a side face even when boxes are combined to be loaded in a pallet.SOLUTION: A trunk 20 of a packing box 10 is configured by connecting a pair of first walls 21 and 22 facing each other in a vertical direction and a pair of second walls 23 for connecting the pair of first walls 21 and 22 via trunk crease lines 40 and 50. The trunk crease lines 40 and 50 include two or more connection crease lines 41 and 42 extending along boundary lines between the first walls 21 and 22 and the second walls 23, and leaf-like crease lines 43 and 53 connecting the ends of the adjacent connection crease lines 41 and 42. Each second wall includes a pair of buckling inducement crease lines 80 and 90 formed to face each other in the vertical direction, extend away from the trunk crease lines 40 and 50, and overlap the connection crease lines 41 and 42 when seen in the vertical direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rectangular parallelepiped packaging box formed by folding a blank sheet along crease lines. [Background technology]

[0002] Conventionally, wrap-around cases have been known in which packaged items such as bottles and cans arranged on a blank sheet obtained by punching out a cardboard sheet are placed, the blank sheet is folded along creases to enclose the products, and the flaps are joined to form a case while packaging the products. When stacking cases of this type, wrap-around cases have had the problem that, when cases containing items are stacked, the weight of the upper cases causes the lower cases to bulge, resulting in unexpected buckling and damaging the appearance of the case.

[0003] To address this problem, a rectangular parallelepiped packaging box is known in which wavy fold lines are formed symmetrically along the top and bottom edges on the side surfaces (Patent Document 1). With this conventional packaging box, when cases containing items are stacked together, the load of the upper case causes the side surfaces of the lower case to bend as planned along the pair of wavy fold lines, and the part sandwiched between the pair of wavy fold lines protrudes outward from the packaging box to relieve the load, thereby preventing unexpected buckling. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Design Registration No. 1548930 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in order to prevent the boxes from collapsing when being loaded onto a pallet, they must be stacked one above the other and one below the other. In this case, when a conventional packing box tries to protrude a part of its side outward due to the load of the upper case, the side of the adjacent packing box gets in the way and prevents the protrusion, preventing the load from being released, resulting in a different type of unexpected buckling.

[0006] Therefore, the present invention has been made in consideration of the above points, and aims to provide a packaging box that can prevent unexpected buckling of the sides even when boxes are stacked together on a pallet. [Means for solving the problem]

[0007] The packaging box of the present invention has a rectangular cylindrical body portion extending horizontally and a closing portion that closes an open end of the body portion, and the body portion is configured by a pair of first wall portions that face each other in the up-down direction and a pair of second wall portions that connect the pair of first wall portions, and the body portion fold lines formed at each boundary portion between the first wall portions and the second wall portions include two or more connecting fold lines that extend along the boundary line between the first wall portions and the second wall portions, and first curved fold lines that connect ends of adjacent connecting fold lines and curve convexly toward the first wall portion side and the second wall portions. and a leaf-shaped fold line consisting of a second curved fold line that curves convexly toward the second wall portion, and each second wall portion has a pair of buckling induction fold lines that face each other in the vertical direction and extend along each of the body fold lines on the upper and lower edge sides while being spaced apart from the body fold lines, respectively, and are formed so as to overlap the body fold lines when viewed in the vertical direction, and when a plurality of the packaging boxes are stacked one on top of the other, they are mountain-folded along the pair of buckling induction fold lines so that the area sandwiched between the pair of buckling induction fold lines protrudes outward from the packaging box (hereinafter referred to as the "first packaging box of the present invention").

[0008] In the first packaging box of the present invention, part of the body fold line includes a leaf-shaped fold line, so that when the blank sheet is folded at right angles along the body fold line to form the body during box making, part of the second wall protrudes outward along the second curved fold line of the leaf-shaped fold line.

[0009] Next, when the packaging boxes of the first aspect of the present invention are arranged horizontally on a pallet, the second wall portions of adjacent packaging boxes come into contact with each other at their protruding parts, resulting in a gap between them.

[0010] Next, in the packaging box of the first invention, buckling induction fold lines are formed near the upper and lower edges of the second wall portion at positions where the above-mentioned leaf-shaped fold lines are not formed (positions that overlap the body fold lines when viewed in the vertical direction), so that when the packaging boxes are stacked in the vertical direction, the second wall portion is folded in a mountain shape along this pair of buckling induction fold lines, and the area sandwiched between the pair of buckling induction fold lines protrudes outward from the packaging box.

[0011] Therefore, according to the packaging box of the first invention, even when boxes are stacked together on a pallet, gaps are created between adjacent second wall portions, so when the boxes are stacked vertically, the load can be released by deforming the second wall portions as intended, and unexpected buckling of the second wall portions can be avoided.

[0012] Furthermore, in the packaging box of the first invention, it is preferable that the leaf-shaped fold lines are formed in two or more positions for each body fold line and are symmetrical in the vertical direction in each second wall portion, the connecting fold lines include a central connecting fold line connecting the inner ends of two adjacent leaf-shaped fold lines, and the buckling-inducing fold line has a first buckling portion which is an area that overlaps with the central connecting fold line when viewed in the vertical direction (hereinafter referred to as the "packaging box of the second invention").

[0013] In the second packaging box of the present invention, two or more leaf-shaped fold lines are formed for each body fold line, and are formed at positions that are symmetrical above and below on each second wall portion. Therefore, when the blank sheet is folded along the body fold lines to form the body portion, the second wall portion protrudes outward at four positions that are symmetrical above and below along the second curved fold line of the leaf-shaped fold line.

[0014] Therefore, when the packaging boxes of the second invention are arranged horizontally on a pallet, the second wall portions of adjacent packaging boxes are butted against each other at the four protruding portions, so that a gap is sure to be created between them.

[0015] Next, in the packaging box of the second invention, buckling-inducing fold lines are formed near the upper and lower edges of the second wall portion at positions where the above-mentioned leaf-shaped fold lines are not formed (positions that overlap the central connecting fold line when viewed in the vertical direction), so that when the packaging box is stacked on a pallet, the second wall portion is folded in a mountain shape along this pair of buckling-inducing fold lines, and the area sandwiched between the pair of buckling-inducing fold lines protrudes outward from the packaging box.

[0016] Therefore, according to the packaging box of the second invention, even when boxes are stacked together on a pallet, gaps are created between adjacent second wall portions, making it possible to avoid unexpected buckling of the second wall portions.

[0017] Furthermore, in the packaging box of the second invention, it is preferable that the buckling-inducing fold line has a second buckling portion which is connected to the first buckling portion and is an area which overlaps with the second curved fold line when viewed in the vertical direction, and each second wall portion has an auxiliary fold line which connects the central connecting fold line and the horizontal middle portion of the second buckling portion (hereinafter referred to as the "packaging box of the third invention").

[0018] In the third packaging box of the present invention, the packaging box is formed to be longer and has not only a first buckling portion which is an area that overlaps with the central connecting fold line, but also a second buckling portion which is an area that overlaps with the second curved fold line, so that the second wall portion can be made to protrude widely.

[0019] Incidentally, when the blank sheet is folded along the body fold line to form the body, the area of ​​the second wall portion that overlaps the second curved fold line protrudes symmetrically from above and below, deforming into a columnar shape, increasing the strength of the wall. Therefore, when the packaging boxes are stacked on a pallet, the second buckling portion may be slightly difficult to bend along the buckling-inducing fold line.

[0020] However, in the third packaging box of the present invention, each second wall portion has an auxiliary fold line connecting the central connecting fold line and the horizontal middle portion of the second buckling portion, so that the load applied from the bottom plate (first wall portion) of the upper packaging box to the vicinity of the central connecting fold line of the top plate of the lower packaging box can be guided to the second buckling portion while causing the auxiliary fold line to fold in a mountain shape.

[0021] Therefore, in the packaging box of the third aspect of the present invention, the buckling induction fold line can be reliably mountain-folded up to the second buckling portion by using a load applied to the vicinity of the central connecting fold line. Therefore, in the packaging box of the third aspect of the present invention, the second wall portion can be protruded widely by reliably mountain-folding the entire buckling induction fold line.

[0022] As a result, in the packaging box of the third aspect of the present invention, it is possible to prevent the second wall portion from unexpectedly buckling by making the second wall portion protrude widely.

[0023] In the packaging box of the third invention, it is preferable that the second buckling portion and the auxiliary fold line are formed so as to be curved along the second curved fold line (hereinafter referred to as "the packaging box of the fourth invention").

[0024] In the fourth packaging box of the present invention, the second buckling portion and auxiliary fold line are formed by curving along the second curved fold line, so that the load applied near the central connecting fold line is smoothly connected, thereby ensuring a mountain fold up to the second buckling portion of the buckling-inducing fold line.

[0025] As a result, according to the packaging box of the fourth invention, even when boxes are stacked together on a pallet, gaps are created between adjacent second wall portions, thereby preventing unexpected buckling of the second wall portions. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a perspective view showing a configuration of a packaging box according to an embodiment of the present invention. [Figure 2A] FIG. 2 is a top view showing the configuration of the packaging box of FIG. [Figure 2B] FIG. 2 is a side view showing the configuration of the packaging box of FIG. [Figure 2C] FIG. 2 is an end view showing the configuration of the packaging box of FIG. [Figure 3] FIG. 2 is a development view of the paperboard that constitutes the packaging box of FIG. 1. [Figure 4A] 2 is a diagram showing a schematic diagram illustrating a detailed configuration of a compound fold line at the upper edge of the packaging box of FIG. 1. FIG. [Figure 4B] 2 is a diagram schematically showing a detailed configuration of a compound fold line at the bottom edge of the packaging box of FIG. 1. FIG. [Figure 5A] FIG. 2 is a top view showing the top surface when two packaging boxes of the present invention are placed side by side. [Figure 5B] 5B is a cross-sectional view schematically showing the outer shape of the packaging box in a cross-section taken along line AA (broken line) and a cross-section taken along line BB (solid line) shown in FIG. 5A. [Figure 6A] 1 is a top view showing a state when a load is applied to a packaging box stacked with packaging boxes of the present invention, as viewed from above. FIG. [Figure 6B] 1 is a side view showing a state when a load is applied to a packaging box loaded with packaging boxes of the present invention, as viewed from the side. FIG. [Figure 7] FIG. 10 is a diagram schematically showing a compound fold line at the top edge of a packaging box according to Modification 1 of the present invention. [Figure 8] FIG. 10 is a diagram schematically illustrating details of the upper edge composite fold line of the packaging box according to the second modified example of the present invention. [Figure 9] FIG. 10 is a diagram schematically illustrating details of the upper edge composite fold line of the packaging box according to the third modified example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, a packaging box 10 according to one embodiment of the present invention (hereinafter simply referred to as "this embodiment") will be described with reference to FIGS.

[0028] The packaging box 10 of this embodiment is a packaging box (for example, a wrap-around case) for storing articles. That is, as shown in the assembled state in Fig. 1, the packaging box 10 is formed in a rectangular parallelepiped shape by a body portion 20 having a rectangular cylindrical shape extending horizontally and a closing portion 30 that closes the open end of the body portion 20. The body 20 is composed of a top plate 21 (corresponding to the "first wall portion"), a bottom plate 22 (corresponding to the "first wall portion"), and a pair of side plates 23 (corresponding to the "second wall portion") connecting the top plate 21 and the bottom plate 22. The top plate 21 and the bottom plate 22 are opposed to each other in the vertical direction to form a pair. The top plate 21 and the pair of side plates 23 are connected to each other via an upper edge body fold line 40 (corresponding to the "body fold line"). The bottom plate 22 and the pair of side plates 23 are connected to each other via a lower edge body fold line 50 (corresponding to the "body fold line"). The closing sections 30 that close both ends of the body section 20 are formed by bonding together upper outer flaps 31 connected to both ends of the top plate 21, lower outer flaps 32 connected to both ends of the bottom plate 22, and inner flaps 33 connected to both ends of each side plate 23.

[0029] 2A to 2C show each side of the packaging box 10. Fig. 2A shows the packaging box 10 as seen from the top plate 21 side. Fig. 2B shows the packaging box 10 as seen from the side plate 23 side. Fig. 2C shows the packaging box 10 as seen from the closing portion 30 side.

[0030] The packaging box 10 is formed from a single, substantially rectangular blank sheet 10X made of corrugated cardboard, as shown in an exploded view in Fig. 3. Fig. 3 shows the back side of the blank sheet 10X (the surface that will become the inside of the box when made into the packaging box 10). The blank sheet 10X comprises a top plate 21 (first wall portion) at the right end on the left side in Figure 3, a side plate 23 (second wall portion) connected to the left edge of the top plate 21 via an upper edge trunk fold line 40 (trunk fold line), a bottom plate 22 (first wall portion) connected to the left edge of the side plate 23 via a lower edge trunk fold line 50 (trunk fold line), a side plate 23 (second wall portion) connected to the left edge of the bottom plate 22 via the lower edge trunk fold line 50 (trunk fold line), and an adhesive piece 24 connected to the left edge of the side plate 23 via the upper edge trunk fold line 40 (trunk fold line).

[0031] 3, the top panel 21 has upper outer flaps 31 connected to its upper and lower edges via flap fold lines 61. The bottom panel 22 has lower outer flaps 32 connected to its upper and lower edges via flap fold lines 62. The side panels 23 have inner flaps 33 connected to their upper and lower edges via flap fold lines 63. The upper outer flap 31, the lower outer flap 32, and the pair of inner flaps 33 constitute the closing portion 30 of the packaging box 10. That is, the upper outer flap 31 and the lower outer flap 32 are adhered to the outer surface of the inner flap 33 to constitute the closing portion 30. In addition, the upper outer flap 31 is provided with a finger insertion section 71 formed by a breakable line and a slit, into which fingers can be inserted when lifting the packaging box 10, and further has an additional fold line 72 parallel to the flap fold line 61.

[0032] The side panel 23 and the inner flap 33 are provided with a tear strip 73 for opening by cutting the liner.

[0033] 3 and 4A, the upper edge trunk fold line 40 connecting the top panel 21 and the side panel 23 has two or more connecting fold lines 41, 42 extending along the boundary line between the top panel 21 and the side panel 23, and a leaf-shaped fold line 43 connecting the ends of adjacent connecting fold lines 41, 42 and consisting of a first curved fold line 43A that curves convexly toward the top panel 21 and a second curved fold line 43B that curves convexly toward the side panel 23. Of the connecting fold lines described above, the connecting fold line that connects the inner ends of two adjacent leaf-shaped fold lines 43 is defined as the central connecting fold line 42.

[0034] 3 and 4B, the lower body fold line 50 connecting the bottom plate 22 and the side plate 23 has two or more connecting fold lines 51, 52 extending along the boundary line between the bottom plate 22 and the side plate 23, and a leaf-shaped fold line 53 connecting the ends of adjacent connecting fold lines 51, 52 and consisting of a first curved fold line 53A that curves convexly toward the bottom plate 22 and a second curved fold line 53B that curves convexly toward the side plate 23. Of the connecting fold lines described above, the connecting fold line that connects the inner ends of two adjacent leaf-shaped fold lines 53 is defined as the central connecting fold line 52.

[0035] There are two or more leaf-shaped fold lines 43, 53 for each of the upper edge trunk fold line 40 and the lower edge trunk fold line 50, and they are formed at positions symmetrical from top to bottom on each side panel 23 (second wall portion). In other words, when the imaginary boundary line when the top panel 21 is folded relative to the side panel 23 is referred to as the upper edge line 44, the two leaf-shaped fold lines 43 are spaced apart from each other on the upper edge line 44. The two leaf-shaped fold lines 43 have the same configuration, i.e., the same shape, width, and length. Similarly, when the imaginary boundary line when the side panel 23 is folded relative to the bottom panel 22 is referred to as the lower edge line 54, two leaf-shaped fold lines 53 are arranged spaced apart from each other on the lower edge line 54. The two leaf-shaped fold lines 53 have the same configuration, i.e., the same shape, width, and length.

[0036] Each side panel 23 also has a buckling fold line 80 that extends along and away from the upper body fold line 40, overlapping the upper body fold line 40 when viewed in the vertical direction. Similarly, each side panel 23 has a buckling fold line 90 that extends along and away from the lower body fold line 50 on the lower side, overlapping the lower body fold line 50 when viewed in the vertical direction. The buckling fold lines 80 and 90 face each other in the vertical direction and are formed symmetrically (vertically) with respect to a center line CX ( FIG. 2B ) that extends horizontally through the center of the side panel 23 in the vertical direction. The buckling fold line 80 has a first buckling portion 81, which is a region overlapping with the central connecting fold line 42 when viewed in the vertical direction, and a second buckling portion 82, which is connected to the first buckling portion 81 and is a region overlapping with the second curved fold line 43B when viewed in the vertical direction. Similarly, the buckling fold line 90 has a first buckling portion 91, which is a region overlapping with the central connecting fold line 52 when viewed in the vertical direction, and a second buckling portion 92, which is connected to the first buckling portion 91 and is a region overlapping with the second curved fold line 53B when viewed in the vertical direction.

[0037] 4A, in this embodiment, the upper edge trunk fold line 40 and the buckling induction fold line 80 collectively form an upper edge compound fold line 85. The upper edge trunk fold line 40 has end connecting fold lines 41 at both ends that connect the ends 40T to the outer ends 43T of the two leaf-shaped fold lines 43. The buckling induction fold line 80 is formed as a fold line having a wave shape along the two leaf-shaped fold lines 43 and the central connecting fold line 42 in the lateral (horizontal) direction, within a range not exceeding the outer ends 43T of the two leaf-shaped fold lines 43.

[0038] 4B, the lower edge trunk fold line 50 and the buckling induction fold line 90 together form a lower edge compound fold line 95. The lower edge trunk fold line 50 has end connecting fold lines 51 at both ends that connect both ends 50T to the outer ends 53T of the two leaf-shaped fold lines 53. The buckling induction fold line 90 is formed as a fold line having a wave shape along the two leaf-shaped fold lines 53 and the central connecting fold line 52 in the lateral (horizontal) direction, within a range not exceeding the outer ends 53T of the two leaf-shaped fold lines 53.

[0039] The packaging box 10 shown in FIG. 1 is assembled from the blank sheet 10X having the above-described structure shown in FIG.

[0040] That is, the top plate 21, bottom plate 22, and pair of side plates 23 of the blank sheet 10X are folded in the same direction along the upper body fold line 40 or the lower body fold line 50, and then the adhesive piece 24 connected to the left edge (FIG. 3) of the side plate 23 is superimposed on and adhered to the inner surface of the right end of the top plate 21. This forms the rectangular cylindrical body 20. 2, a leaf-shaped recess is formed in the upper ridge of the body 20, inclined relative to the top plate 21 and the side plate 23. Similarly, a leaf-shaped recess is formed in the lower ridge of the body 20, inclined relative to the side plate 23 and the bottom plate 22. Therefore, when the box is made, the edges of the upper leaf-shaped fold line 43 and the lower leaf-shaped fold line 53 protrude outward.

[0041] Next, the inner flaps 33 connected to both ends of the pair of side panels 23 are folded inward along the flap fold lines 63, and then the upper outer flaps 31 connected to both ends of the top panel 21 are folded inward along the flap fold lines 61, and the lower outer flaps 32 connected to both ends of the bottom panel 22 are folded inward along the flap fold lines 62, and are overlapped on the outside of the inner flaps 33, and the overlapped parts are adhered with adhesive to form the closure part 30. In this way, the packaging box 10 is formed as shown in FIG.

[0042] Next, with reference to Figs. 5 and 6, the state of the packaging box 10 of this embodiment when in use will be described, and the effects of this embodiment will be described. Fig. 5A shows the state when two packaging boxes 10 are placed side by side as viewed from above. Fig. 5B is a cross-sectional view schematically showing the outer shape of the packaging box 10 in a cross section taken along line AA (broken line) and a cross section taken along line BB (solid line) shown in Fig. 5A. Fig. 6A shows the state when a load is applied to the stacked packaging boxes 10 as viewed from above. Fig. 6B is a side view showing the state when a load is applied to the packaging box 10 with the packaging boxes 10 stacked thereon as viewed from the side. Note that although each figure is depicted as having angular deformation, this is merely a representation as a schematic diagram, and in reality, packaging boxes are usually rounded and deformed gently.

[0043] As shown in Figure 5A, in the packaging box 10 of this embodiment, leaf-shaped fold lines 43, 53 are included in parts of the upper edge body fold line 40 and the lower edge body fold line 50. Therefore, when the blank sheet 10X is folded at right angles along the upper edge body fold line 40 and the lower edge body fold line 50 to form the body 20 during box making, parts of the side panels 23 protrude outward along the second curved fold lines 43B, 53B of the leaf-shaped fold lines 43, 53.

[0044] Furthermore, when the packaging boxes 10 are arranged horizontally on a pallet, the side plates 23 of adjacent packaging boxes 10 come into contact with each other at their protruding portions, resulting in a gap between them. In particular, in the packaging box 10 of the embodiment, two leaf-shaped fold lines 43, 53 are formed for each of the upper edge body fold line 40 and the lower edge body fold line 50, and are formed at positions symmetrical from top to bottom on each side panel 23.Therefore, when the blank sheet 10X is folded along the body fold lines 40, 50 to form the body 20, the side panels 23 protrude outward at four positions symmetrical from top to bottom along the second curved fold lines 43B, 53B of the leaf-shaped fold lines 43, 53.

[0045] Therefore, when the packaging boxes 10 are arranged horizontally on a pallet, the side panels 23 of adjacent packaging boxes 10 are abutted against each other at the four protruding portions, so that a gap is surely created between them.

[0046] Furthermore, in the packaging box 10, buckling induction fold lines 80, 90 are formed near the upper and lower edges of the side panels 23, respectively, so as to include positions where the leaf-shaped fold lines 43, 53 are not formed (positions that overlap the central connecting fold lines 42, 52 when viewed in the vertical direction).Therefore, when the packaging boxes 10 are stacked in the vertical direction, the side panels 23 are mountain-folded along this pair of buckling induction fold lines 80, 90, and the area sandwiched between the pair of buckling induction fold lines 80, 90 protrudes outward from the packaging box 10.

[0047] Therefore, according to the packaging box 10 of this embodiment, even when boxes are loaded on a pallet with one another attached to the other, gaps are formed between adjacent side panels 23. Therefore, when the boxes are stacked vertically, the side panels 23 can be deformed as intended to release the load, thereby preventing unexpected buckling of the side panels 23.

[0048] Furthermore, the packaging box 10 has an additional fold line 72 on the upper outer flap 31. Therefore, according to the packaging box 10 of this embodiment, when the packaging boxes 10 are stacked vertically, the closing portion 30 side is first buckled in advance, which facilitates the application of load to the buckling-inducing fold lines 80, 90. This makes it easier to protrude almost the entire area of ​​the side panel 23, excluding the outer edge, outward, thereby suppressing deterioration of the appearance.

[0049] [Variation 1] Next, a first modified example of the packaging box 10 of this embodiment will be described. Note that the same components as those of the packaging box 10 of this embodiment will be assigned the same reference numerals and descriptions thereof will be omitted.

[0050] In the packaging box 10 according to the embodiment described above, the pair of buckling fold lines 80, 90 formed on each side panel 23 includes a first buckling portion 81, 91 that overlaps the central connecting fold line 42, 52 when viewed in the vertical direction, and a second buckling portion 82, 92 that is connected to the first buckling portion 81, 91 and overlaps the second curved fold line 43B, 53B when viewed in the vertical direction (i.e., the buckling fold line 80 coincides with both outer ends of the two leaf-shaped fold lines 43 when viewed in the vertical direction). However, the present invention is not limited to this example. Below, the positional relationship between the upper body fold line 40 and the buckling fold line 80 (180) will be described using the upper compound fold line 185 in FIG. 7 .

[0051] As shown in Figure 7, the upper edge compound fold line 185 is composed of the upper edge body fold line 40 and a buckling induction fold line 180. The buckling induction fold line 180 has a first buckling portion 181, which is a region that overlaps with the central connecting fold line 42 when viewed in the up-down direction, and a second buckling portion 182, which is connected to the first buckling portion 181 and is a region that overlaps with a portion of the second curved fold line 43B when viewed in the up-down direction. In other words, the buckling induction fold line 180 is formed as a fold line having an inverted bottom shape along the two leaf-shaped fold lines 43 and the central connecting fold line 42, within a range (within the range RX) inside both outer ends 43T of the two leaf-shaped fold lines 43 in the lateral (horizontal) direction.

[0052] Furthermore, in variant example 1, there is a lower edge composite fold line (not shown) that has the same configuration as the upper edge composite fold line 185 and is arranged symmetrically to the upper edge composite fold line 185 with respect to the lateral center line CX (Figure 2B) of the side panel 23, as in the above-mentioned embodiment.

[0053] According to this configuration, as in the above-described embodiment, the provision of the buckling-inducing fold line 180 can absorb distortion that cannot be fully absorbed by the leaf-shaped fold line 43, and also prevents the side panel 23 from bulging out in a convex shape, thereby preventing deterioration of the appearance. The ease of distortion absorption during loading can be adjusted by the formation range (length) of the second buckling portion 82 (182).

[0054] [Variation 2] Next, a second modified example of the packaging box 10 of this embodiment will be described. In the packaging box 10 according to the above-described embodiment, the upper edge composite fold line 85 formed on each side panel 23 is described as being composed only of the upper edge body fold line 40 and the buckling induction fold line 80, but the present invention is not limited to this.

[0055] 8, the upper edge compound fold line 285 is composed of the upper edge trunk fold line 40, the buckling induction fold line 280, and the auxiliary fold line 283. The buckling induction fold line 280 has a first buckling portion 281, which is an area that overlaps with the central connecting fold line 42 when viewed in the vertical direction, and a second buckling portion 282, which is connected to the first buckling portion 281 and is an area that overlaps with the second curved fold line 43B when viewed in the vertical direction. The auxiliary fold line 283 is formed to connect the central connecting fold line 42 and the horizontally intermediate portion (connection point 283C) of the second buckling portion 282. The auxiliary fold line 283 has a downwardly convex arc shape, and curves from the inner end portion 43C of the leaf-shaped fold line 43 along the leaf-shaped fold line 43 to be smoothly connected to the intermediate portion (connection point 283C) of the second buckling portion 282.

[0056] In addition, in the second modification, the lower edge compound fold line (not shown) that is provided symmetrically to the upper edge compound fold line 285 has the same configuration as the above-described upper edge compound fold line 285, and therefore detailed description thereof will be omitted.

[0057] Next, a description will be given of the effects of Modification 2. As in the present embodiment described above, packaging box 10 of Modification 2 is formed longer and has not only first buckling portion 281, which is the region overlapping central connecting fold line 42, but also second buckling portion 282, which is the region overlapping second curved fold line 43B. Therefore, if the entire area of ​​buckling-inducing fold line 280 can be mountain-folded, side panel 23 can be made to protrude widely.

[0058] However, when the blank sheet 210X (not shown) is folded along the upper edge body fold line 40 and the lower edge body fold line 50 to form the body 20, the area of ​​the side panel 23 that overlaps the second curved fold line 43B (53B) protrudes symmetrically from top to bottom, causing part of the side panel to deform into a columnar shape, thereby increasing the strength of the wall. Therefore, when the packaging boxes 10 are stacked on a pallet, the part of the buckling induction fold line 280 corresponding to the second buckling portion 282 may be slightly more difficult to bend.

[0059] However, in the packaging box 10 of variant example 2, each side panel 23 has an auxiliary fold line 283 connecting the central connecting fold line 42 and the horizontal middle part of the second buckling portion 282, so that the load applied to the central part (near the central connecting fold line 42) of the top panel 21, where the load from the bottom panel 22 of the upper packaging box 10 is greatest, can be guided to the second buckling portion 282 by folding the auxiliary fold line 283 in a mountain fold.

[0060] Therefore, in packaging box 10 of modified example 2, buckling induction fold line 280 can be reliably mountain-folded to both ends (second buckling portions 282) by guiding the load applied to the vicinity of central connecting fold line 42. Therefore, in packaging box 10 of modified example 2, side panel 23 can be made to protrude widely by reliably mountain-folding the entire area of ​​buckling induction fold lines 80, 90.

[0061] As a result, in the packaging box 10 of the second modified example, it is possible to prevent the side plates 23 from unexpectedly buckling due to the side plates 23 being made to protrude widely.

[0062] In particular, in the packaging box 10 of variant example 2, the second buckling portion 282 and the auxiliary fold line 283 are formed to be curved along the second curved fold line 43B, so that the load acting near the central connecting fold line 42 can be smoothly guided, thereby ensuring a mountain fold up to the second buckling portions 82, 92 of the buckling induction fold lines 80, 90. In addition, in the description of the second modification, the lower edge compound fold line is provided symmetrically with the upper edge compound fold line 285, but if only one of the buckling-inducing fold lines 280, 290 is difficult to fold depending on the height of the products to be stored in the packaging box or the number of packaging boxes stacked, an auxiliary fold line can be provided only on the one that is difficult to fold. Also, in the description of the second modification, the second buckling portion 282 and the auxiliary fold line 283 are formed by curving along the second curved fold line 43B, but there is no limitation on the shape, and the second buckling portion 282 and the auxiliary fold line 283 may each be straight, may have an upwardly convex arc shape, or may have a wavy shape. [Variation 3] Next, a third modification of the packaging box 10 of this embodiment will be described. In the second modification described above, the second buckling portion 282 of the buckling-inducing fold line 280 is formed by a fold line, but the present invention is not limited to this. For example, as in the third modification described below, a part of the second buckling portion may be formed by a perforation.

[0063] 9, buckling-inducing fold line 380 has first buckling portion 381, which is a region overlapping central connecting fold line 42 when viewed in the vertical direction, second buckling portion 382A, which is a region connected to first buckling portion 381 and overlapping a portion of second curved fold line 43B when viewed in the vertical direction, and perforation 382B, which is a region connected to second buckling portion 382A and overlapping another portion of second curved fold line 43B when viewed in the vertical direction. Perforation 382B functions as the second buckling portion of the present invention together with second buckling portion 382A. According to this configuration, each of the second buckling portions 382A of the buckling-inducing fold line 380 is formed from a perforation 382B on the outer end side of the connection point 65C with the auxiliary fold line 283, making it easier to bend than the second buckling portion 82 of the above-mentioned variant example 2.

[0064] Furthermore, in the above-described embodiment, corrugated cardboard has been used as an example of the material, but cardboard materials such as cardboard other than corrugated cardboard may also be used. In the above-described embodiment, the buckling induction fold line 80 has the first buckling portion 81 and the second buckling portion 82, but the second buckling portion 82 may be omitted as long as there is at least the first buckling portion 81. The buckling induction fold line 80 may overlap the outer connecting fold line 41. Furthermore, the buckling induction fold line 80 may be provided over the entire side panel 23 so as to overlap the connecting fold lines 41 on both sides and the central connecting fold line 42, or it may be provided as three separate lines that mainly overlap these lines (but not the second buckling portion 82).

[0065] The present invention is not limited to the above-described embodiments, and its technical scope includes various modified design forms within the scope that do not deviate from the gist of the invention described in the claims. [Explanation of symbols]

[0066] 10 packaging box 20 Torso 21 Top plate (first wall) 22 Bottom plate (first wall) 23 Side plate (second wall) 30 Occlusion 40 Upper edge body fold line 41 Connecting fold line 42 Center connecting fold line 43 Leaf-shaped fold line 43A First curved fold line 43B Second curved fold line 50 Lower edge body fold line 51 Connecting fold line 52 Center connecting fold line 53 Leaf-shaped fold line 53A First curved fold line 53B Second curved fold line 80 Buckling induced fold line 81 1st buckling part 82 Second buckling part 90 Buckling induced fold line 91 1st buckling part 92 Second buckling part 283 Auxiliary fold line

Claims

1. A packaging box having a rectangular cylindrical body portion extending horizontally and a closing portion that closes an open end of the body portion, The body portion is configured by a pair of first wall portions facing each other in the vertical direction and a pair of second wall portions connecting the pair of first wall portions, each of which is connected via a body portion fold line, The trunk fold lines formed at each boundary between the first wall portion and the second wall portion include two or more connecting fold lines extending along the boundary line between the first wall portion and the second wall portion, and leaf-shaped fold lines connecting ends of adjacent connecting fold lines and consisting of a first curved fold line that is curved convexly toward the first wall portion side and a second curved fold line that is curved convexly toward the second wall portion side, Each second wall portion is A pair of buckling induction fold lines are formed so as to face each other in the vertical direction, extend along the body fold lines while being spaced apart from the body fold lines on the upper edge side and the lower edge side, and overlap the body fold lines when viewed in the vertical direction, When a plurality of the packaging boxes are stacked one on top of the other, the packaging boxes are folded along the pair of buckling induction fold lines, and the area sandwiched between the pair of buckling induction fold lines protrudes outward from the packaging box.

2. The packaging box according to claim 1, The leaf-shaped fold lines are formed at two or more positions symmetrically in the up-down direction on each second wall portion with respect to each trunk fold line, the connecting fold lines include a central connecting fold line connecting inner ends of two adjacent leaf-shaped fold lines; The packaging box is characterized in that the buckling induction fold line has a first buckling portion which is a region that overlaps with the central connecting fold line when viewed in the vertical direction.

3. The packaging box according to claim 2, The buckling-inducing fold line has a second buckling portion that is connected to the first buckling portion and overlaps with the second curved fold line when viewed in the up-down direction, A packaging box characterized in that each second wall portion has an auxiliary fold line connecting the central connecting fold line and a horizontally intermediate portion of the second buckling portion.

4. The packaging box according to claim 3, The packaging box is characterized in that the second buckling portion and the auxiliary fold line are formed to be curved along the second curved fold line.

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