Packing box

Abstract

To provide a packing box that is excellent in commodity display property and is hard to lower strength thereof even when large load and impact act thereon during commodity transportation.SOLUTION: A packing box 1 includes front, rear, right, and left side plates 11 to 14, a peak plate 20 and a bottom plate 30. The packing box further includes: a front break guide line L21 formed across the front edge part of the peak plate 20; a left break guide line L22 formed across the left edge part of the peak plate 20; a right break guide line L22 formed across the right edge part of the peak plate 20; a break starting part 25 that is formed on the peak plate 20 and becomes the starting point of the break of the front break guide line L21; a peak plate bending break line 28 that is provided on the surface of the peak plate 20 in parallel with the front edge part of the peak plate 20 and is for double-folding the peak plate 20; and an engaging part 24 that is provided in the longitudinal direction of the peak plate 20 with the peak plate bending guide line 28 as a border and engages the faces of the double-folded peak plate 20 by the peak plate bending guide line 28.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a packaging box. [Background technology]

[0002] BACKGROUND ART Conventionally, packaging boxes are known that are used as transport boxes when transporting products and also used when displaying products in stores (see, for example, Patent Document 1). The packaging box of Patent Document 1 is made of cardboard, and by cutting off the opening portion from the side panel to the top panel, the product can be displayed as is. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-15528 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional packaging box described above, the break guide line for separating the opening portion formed on the top plate is also formed on the side plate, so there is a risk that the break guide line may be broken unintentionally due to the load or impact acting on the packaging box during product transportation, etc., thereby reducing the strength of the packaging box. For this reason, there has been a demand for a packaging box that can maintain its strength during product transportation, etc.

[0005] The present invention aims to solve the above-mentioned problems and to provide a packaging box that is excellent in product display properties and is resistant to deterioration in strength even when subjected to large loads or impacts during product transportation, etc. [Means for solving the problem]

[0006] To solve the above-mentioned problems, the present invention provides a packaging box comprising front, rear, left, and right side panels, a top panel connected to the upper edges of the front, rear, left, and right side panels, and a bottom panel connected to the lower edges of the front, rear, left, and right side panels. The packaging box also comprises a front break guide line formed along the front edge of the top panel, a left break guide line formed along the left edge of the top panel, and a right break guide line formed along the right edge of the top panel. The packaging box further comprises a break initiation portion formed in the top panel that serves as a break initiation point for the front break guide line, a top panel folding guide line extending parallel to the front edge of the top panel within the plane of the top panel for folding the top panel in half front and rear, and engaging portions provided at the front and rear of the top panel across the top panel folding guide line for engaging the surfaces of the top panel folded in half by the top panel folding guide line. The top plate includes front and rear upper outer flaps connected to the upper edges of the front and rear side plates, and left and right upper inner flaps connected to the upper edges of the left and right side plates and overlapping the undersides of the front and rear upper outer flaps. The front and rear upper outer flaps are butted together at the center in the front-to-rear direction, and the top plate folding guide lines are formed on the left and right upper inner flaps along the butted portions of the front and rear upper outer flaps. The engagement portions are provided on the front upper outer flap and the rear upper outer flap, with the butted portions of the front and rear upper outer flaps as the boundary.

[0007] In the packaging box of the present invention, when the top plate is pulled up with the fingers starting from the break initiation point, the front break guide line is cut open, and the left and right break guide lines are cut open, causing the top plate to rise up above the rear side plate around the rear edge. The raised top plate is then folded in half along the folding guide line, and the two sides are engaged at the engaging portion. This allows the folded top plate to be used as a display sign, providing excellent product displayability. The packaging box of the present invention has a tear initiation portion on the top plate, which serves as the starting point for tearing. Furthermore, front, left, and right tear guide lines for cutting open the top plate are formed on the front, left, and right edges of the top plate. Therefore, the strength of the packaging box can be ensured compared to when tear initiation portions and tear guide lines for opening the top plate are formed within the surfaces of the front, rear, left, and right side plates. This makes it less likely for the strength of the packaging box to decrease even when subjected to large loads or impacts during product transportation, etc.

[0009] AlsoEven in an A-type packaging box, where the top plate is composed of front and rear upper outer flaps and left and right upper inner flaps, by pulling the top plate with your fingers starting from the tear initiation point, the front, left, and right tear guide lines are cut open, and the top plate is raised above the rear side plates around the rear edge as an axis. Then, by folding the raised top plate along the butt joint, the left and right upper inner flaps are folded along the top plate folding guide lines, and the top plate is folded in half in the front-to-back direction. The surfaces of the folded top plate are then engaged at the engagement parts. This allows the folded top plate to be used as a display sign, resulting in excellent product displayability. Even in this case, the strength of the packaging box can be ensured because no break initiation points or break guide lines are formed within the surfaces of the front, rear, left, and right side panels. This makes it difficult for the strength of the packaging box to decrease even when a large load or impact is applied during product transportation. [Effects of the Invention]

[0010] The packaging box of the present invention is excellent in terms of product displayability and is resistant to deterioration in strength even when subjected to a large load or impact during product transportation, etc. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing a packaging box according to a first embodiment of the present invention. [Figure 2] 1 is a diagram showing a blank sheet for a packaging box according to a first embodiment of the present invention. [Figure 3] 1 is a perspective view showing a state when the packaging box according to the first embodiment of the present invention is opened. [Figure 4] 1 is a perspective view showing a state in which the top plate of the packaging box according to the first embodiment of the present invention is folded in half and used as a signboard. FIG. [Figure 5] 1 is an enlarged perspective view showing an engaging portion of a top plate of a packaging box according to a first embodiment of the present invention when folded in half. FIG. [Figure 6] FIG. 10 is a perspective view showing a packaging box according to a second embodiment of the present invention. [Figure 7]FIG. 10 is a diagram showing a blank sheet for a packaging box according to a second embodiment of the present invention. [Figure 8] FIG. 10 is a perspective view showing a state when the packaging box according to the second embodiment of the present invention is opened. [Figure 9] FIG. 10 is a perspective view showing a state in which the top plate of a packaging box according to a second embodiment of the present invention is folded in half and used as a signboard. [Figure 10] FIG. 10 is a perspective view showing an opening start portion of a packaging box according to a modified example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the front, back, left, and right directions are set for the convenience of describing the packaging box of each embodiment, and do not limit the configuration of the packaging box of the present invention. Note that in each embodiment, the same parts are given the same reference numerals, and detailed descriptions will be omitted.

[0013] (First embodiment) As shown in Figures 1 and 2, the packaging box 1 of this embodiment is an A-type box and has a rectangular parallelepiped shape with a longer left-right dimension than a front-to-back dimension. The packaging box 1 includes a bottom plate 30, side plates 11-14 connected to the front, rear, left, and right edges of the bottom plate 30, and a top plate 20 facing the bottom plate 30 and closing the upper openings of the front, rear, left, and right side plates 11-14. The front, rear, left, and right side plates 11-14 form a rectangular cylindrical body 5. The packaging box 1 is used as a shipping box for transporting products, and, as described below, can also be used as a box for displaying products in stores by opening the top plate 20. When displaying products, the top plate 20 can be folded in half and used as a signboard.

[0014] The packaging box 1 is formed by mountain or valley folding a blank sheet S1 cut out from a single sheet of cardboard, along each of the creases, as shown in Fig. 2. The blank sheet S1 shown in Fig. 2 is arranged so that the outer surface is visible, but for ease of explanation, the creases formed on the inner surface are shown as solid lines. Each crease (fold line) on the blank sheet S1 is a linear groove (pressed crease) formed by pressing the surface of the blank sheet S1. Note that notches (half-cut lines, etc.) may be formed on the crease. This makes it easier to fold the blank sheet S1 at the crease.

[0015] 1, the body 5 includes a pair of front and rear side plates 11, 12 and a pair of left and right side plates 13, 14. The front side plate 11, the rear side plate 12, the left side plate 13, and the right side plate 14 are each a rectangular plate. A left side plate 13 is connected to the left edge of the front side plate 11 via a crease. A right side plate 14 is connected to the right edge of the front side plate 11 via a crease. A rear side plate 12 is connected to the rear edge of the right side plate 14 via a crease. A strip-shaped joining piece 16 is connected to the left edge of the rear side plate 12 via a crease. The joining piece 16 is bonded to the inner surface of the left side plate 13 by an adhesive such as hot melt.

[0016] Then, when the blank sheet S1 (see FIG. 2) is folded along each of the lines, the front plate 11, rear plate 12, left plate 13, and right plate 14 form a rectangular cylindrical body portion 5. The left and right side plates 13, 14 are formed with handholds 7, 7.

[0017] Side panel opening start portions 11a, 12a are formed in the approximate centers of the front side panel 11 and the rear side panel 12. The side panel opening start portions 11a, 12a are the starting points when the body portion 5 is divided into two parts in the vertical direction and opened. Each side panel opening start portion 11a, 12a is formed by a linear slit.

[0018] A tear strip 6 is attached to the body 5 so as to intersect with the side panel tear start portions 11a, 12a. The tear strip 6 is provided linearly on the inner surface of the body 5 along the entire circumferential direction of the body 5 (see FIG. 2). The tear strip 6 is parallel to the upper and lower edges of the body 5.

[0019] As shown in Figure 1, the top plate 20 closes the upper opening of the body 5. Break initiation portions 25, 25, which are the starting points for breaking, are formed at the left and right corners of the front side of the top plate 20. In addition, a front break guide line L21 is formed in the left-right direction at the front edge of the top plate 20, and a left break guide line L22 and a right break guide line L22 are formed in the front-rear direction at the left and right edges of the top plate 20. The top plate 20 is designed to be cut open from the body 5 by these front break guide line L21, left break guide line L22, and right break guide line L22 when opening the package.

[0020] Furthermore, top plate 20 is formed with top plate folding guide lines 28, 28. Top plate folding guide lines 28, 28 are used to fold top plate 20 in half in the front-to-back direction when opening the package. Also, an engagement portion 24 is formed in the center of top plate 20. Engagement portion 24 is used to engage top plate 20 in a folded state when opening the package. The top plate 20 will be described in detail below.

[0021] The top plate 20 has a pair of front and rear upper outer flaps 21, 21 connected to the upper edges of the front plate 11 and the rear plate 12, and a pair of left and right upper inner flaps 22, 22 connected to the upper edges of the left plate 13 and the right plate 14. The left and right upper inner flaps 22, 22 are overlapped on the undersides (inner surfaces) of the front and rear upper outer flaps 21, 21, and are adhered to the front and rear upper outer flaps 21, 21 with an adhesive such as hot melt.

[0022] The front upper outer flap 21 is a rectangular flat plate that extends rearward from the upper edge of the front plate 11. The front upper outer flap 21 closes the front half of the upper opening of the body 5. The rear upper outer flap 21 is a rectangular flat plate that extends forward from the upper edge of the rear plate 12. The rear upper outer flap 21 closes the rear half of the upper opening of the body 5. The tips of the front and rear upper outer flaps 21, 21 butt against each other at the center of the top plate 20 in the fore-and-aft direction.

[0023] The front upper outer flap 21 is connected to the upper edge of the front plate 11 via a front break guide line L21. The front break guide line L21 is for separating the front upper outer flap 21 from the front plate 11, and is formed along the entire upper edge of the front plate 11 (the front edge of the front upper outer flap 21). The front break guide line L21 is a perforated line with intermittent slits. The spacing and shape of the slits in the front break guide line L21 are not limited.

[0024] The tear initiation portions 25, 25 of the front upper outer flaps 21 are provided with fold guide lines L25, L25. The fold guide lines L25, L25 are linear grooves (pressed creases) formed by pressing into the surfaces (inner surfaces) of the upper outer flaps 21, 21. The fold guide lines L25, L25 have slits formed at intervals.

[0025] The fold guide line L25 of the left breaking initiation portion 25 extends obliquely from the left edge to the front edge of the upper outer flap 21, and its front end is connected to the front breaking guide line L21. The fold guide line L25 of the right breaking initiation portion 25 extends obliquely from the right edge to the front edge of the upper outer flap 21, and its front end is connected to the front breaking guide line L21.

[0026] As shown in Figures 1 and 2, the engagement portion 24 includes an engagement piece 26 and an opening piece 27. The engagement piece 26 and the opening piece 27 are formed on the front and rear sides of the butt portion of the top plate 20, and are arranged in a mutually opposing positional relationship when the top plate 20 is folded in half during opening, as described below (see Figure 5). The engagement piece 26 is formed on the rear edge of the front upper outer flap 21, and is defined in a substantially trapezoidal shape by left and right cut lines L26a and fold lines L26b. The opening piece 27 is formed on the front edge of the front upper outer flap 21, and is defined in a substantially rectangular shape by left and right cut lines L27a and fold lines L27b.

[0027] As shown in FIG. 5, the engagement pieces 26 are pushed by fingers toward the opposing opening pieces 27 to push open the opening pieces 27 and can engage with the opening edges bordered by the left and right cut lines L27a.

[0028] Next, the left and right upper inner flaps 22, 22 will be described. The left upper inner flap 22 is a rectangular flat plate that extends rightward from the upper edge of the left side panel 13. The left upper inner flap 22 partially covers the left side of the upper opening of the body 5. The left upper inner flap 22 is connected to the upper edge of the left side plate 13 via a left breaking guide line L22. The left breaking guide line L22 is for separating the upper inner flap 22 from the left side plate 13, and is formed along the entire upper edge of the left side plate 13 (the left edge of the left upper inner flap 22). The left breaking guide line L22 is a perforated line with intermittent slits. The spacing and shape of the slits of the left breaking guide line L22 are not limited.

[0029] The right upper inner flap 22 is a rectangular flat plate that extends leftward from the upper edge of the right side panel 14. The right upper inner flap 22 partially covers the right side of the upper opening of the body 5. The right upper inner flap 22 is connected to the upper edge of the right side plate 14 via a right breaking guide line L22. The right breaking guide line L22 is for separating the right upper inner flap 22 from the right side plate 14, and is formed along the entire upper edge of the right side plate 14 (the right edge of the right upper inner flap 22). The right breaking guide line L22 is a perforated line with intermittent slits. The spacing and shape of the slits in the right breaking guide line L22 are not limited.

[0030] The left and right upper inner flaps 22 have fold guide lines L23, L23 that form part of the tear initiation portions 25, 25, formed at positions corresponding to the fold guide lines L25, L25 of the front upper outer flap 21. The fold guide lines L23, L23 are linear grooves (pressed creases) formed by pressing the surfaces (inner surfaces) of the upper inner flaps 22, 22. The fold guide lines L23, L23 have slits formed at intervals.

[0031] The folding guide line L23 of the left upper inner flap 22 extends obliquely from the left edge to the front edge of the left upper inner flap 22. The folding guide line L23 of the right upper inner flap 22 extends obliquely from the right edge to the front edge of the right upper inner flap 22.

[0032] The folding guide lines L25, L25 of the upper outer flap 21 and the folding guide lines L23, L23 of the upper inner flaps 22, 22 overlap in the vertical direction. As a result, when the top plate 20, which will be described later, is opened, the front upper outer flap 21 and the left and right upper inner flaps 22 can be folded in an overlapping state at the left and right tear initiation portions 25, 25, respectively.

[0033] Top panel folding guide lines 28 are formed on the left and right upper inner flaps 22 at positions corresponding to the butt joints of the upper outer flaps 21. Each top panel folding guide line 28 has a folding line L28b extending in the left-right direction and a cut line L28a formed at a distance on the folding line L28b. The top panel folding guide lines 28 function as folding guide lines for folding the top panel 20 in half in the front-to-rear direction along the butt joints when opening the package.

[0034] The bottom plate 30 closes the lower opening of the body 5. The bottom plate 30 includes a pair of front and rear lower outer flaps 31, 31 connected to the lower edge portions of the front plate 11 and the rear plate 12, and a pair of left and right lower inner flaps 32, 32 connected to the lower edge portions of the left plate 13 and the right plate 14. The left and right lower inner flaps 32, 32 are placed on the upper surfaces (inner surfaces) of the front and rear lower outer flaps 31, 31, and are bonded to the front and rear lower outer flaps 31, 31 with an adhesive such as hot melt.

[0035] The front lower outer flap 31 is a rectangular flat plate that extends rearward from the lower edge of the front panel 11. The front lower outer flap 31 closes the front half of the lower opening of the body 5. The rear lower outer flap 31 is a rectangular flat plate that extends forward from the lower edge of the rear plate 12. The rear lower outer flap 31 closes the rear half of the lower opening of the body 5. The tips of the front and rear lower outer flaps 31, 31 butt against each other in the center of the bottom plate 30 in the fore-and-aft direction.

[0036] The left lower inner flap 32 is a rectangular flat plate that extends rightward from the lower edge of the left side panel 13. This left lower inner flap 32 partially covers the left side of the lower opening of the body 5. The right lower inner flap 32 is a rectangular flat plate that extends leftward from the lower edge of the right side panel 14. This right lower inner flap 32 partially covers the right side of the lower opening of the body 5.

[0037] When contents are accommodated in the packaging box 1 of this embodiment and transported or stored, the packaging box 1 is placed so that the top plate 20 faces upward, similar to a typical A-type cardboard box. When opening the packaging box 1, the worker presses the breaking initiation portions 25, 25 of the top plate 20 with his or her fingers, and then grasps the front corners of the top plate 20 with his or her fingers and pulls it up, as shown in Figure 3. This causes the front breaking guide line L21 to be cut open, as well as the left breaking guide line L22 and the right breaking guide line L22, and the top plate 20 is raised above the rear plate 12, with the upper edge of the rear plate 12 serving as the center of rotation.

[0038] 4, the front side of the top plate 20 is tilted forward (bent forward) along the butt portion of the top plate 20, folding the top plate 20 in half in the front-to-rear direction. Then, the fingers are placed on the engaging pieces 26 of the engaging portions 24, and the engaging pieces 26 are pushed toward the opening pieces 27, causing the opening pieces 27 to be pushed open. This causes the engaging pieces 26 to engage with the opening edges bordered by the left and right cut lines L27a, and the top plate 20 is engaged in a folded state.

[0039] In the packaging box 1 of this embodiment described above, the folded top panel 20 can be used as a display sign. Therefore, it has excellent product display properties. In addition, since the top panel 20 is folded in half and engaged with the engaging portion 24, it also has strength. Furthermore, the packaging box 1 of this embodiment has tear initiation portions 25, 25, which serve as tear starting points, provided on the top plate 20. Furthermore, a front tear guide line L21, a left tear guide line L22, and a right tear guide line L22 for cutting open the top plate 20 are formed on the front, left, and right edges of the top plate 20. Therefore, the strength of the packaging box 1 can be ensured compared to when tear initiation portions and tear guide lines for opening the top plate are formed within the surfaces of the front, rear, left, and right side plates 11 to 14. As a result, the strength of the packaging box 1 is less likely to decrease even when a large load or impact is applied during product transportation, etc.

[0040] (Second embodiment) Next, a packaging box according to a second embodiment of the present invention will be described with reference to Figures 6 to 10. Figure 6 is a perspective view showing the packaging box according to the second embodiment of the present invention, and Figure 7 is a diagram showing a blank sheet for the packaging box according to the second embodiment of the present invention. In this embodiment, the present invention is applied to a wrap-around type packaging box 1A.

[0041] 6, the packaging box 1A is a rectangular parallelepiped whose length in the left-right direction is greater than that in the front-to-rear direction. The packaging box 1A includes a bottom plate 51, a pair of front and rear side plates 53, 54, a pair of left and right end plates 60, 70, and a top plate 52.

[0042] The packaging box 1A is formed by mountain-folding or valley-folding a blank sheet S2 cut out from a single sheet of cardboard at each of the ruled lines, as shown in Fig. 7. The blank sheet S2 shown in Fig. 7 is arranged so that the outer surface is visible, but for ease of explanation, the ruled lines formed on the inner surface are shown as solid lines. Each crease (fold line) on the blank sheet S2 is a linear groove (pressed crease) formed by pressing the surface of the blank sheet S2. Note that notches (half-cut lines, etc.) may be formed on the crease lines, which makes it easier to fold the blank sheet S2 at the crease lines.

[0043] As shown in Fig. 6, the bottom plate 51 is a rectangular flat plate. A front side plate 53 is connected to the front edge of the bottom plate 51 via a score line, and a rear side plate 54 is connected to the rear edge of the bottom plate 51 via a score line. The front plate 53 and the rear plate 54 are the same rectangular flat plates and are formed perpendicular to the bottom plate 51 .

[0044] The top plate 52 is connected to the upper edge of the front plate 53 via a front breakage guide line L21. The top plate 52 is a rectangular flat plate like the bottom plate 51, and is formed perpendicular to the rear plate 54. In this embodiment, the front breakage guide line L21 is also formed along the entire upper edge of the front plate 53 (the front edge of the top plate 52).

[0045] A joining piece 56 is connected to the upper edge of the rear plate 54 via a score line. The joining piece 56 is a strip-shaped plate formed along the upper edge of the rear plate 54. The joining piece 56 is joined to the inner surface of the rear edge of the top plate 52 by an adhesive such as hot melt.

[0046] The left end plate 60 includes a pair of upper and lower outer flaps 61, 62 connected to the left edges of the bottom plate 51 and the top plate 52, respectively, and a pair of front and rear inner flaps 63, 64 connected to the left edges of the front plate 53 and the rear plate 54, respectively. The upper outer flap 62 is attached to the left edge of the top plate 52 via a left breakage guide line L22. The left end plate 60 has outer flaps 61 and 62 superimposed on the outer surfaces of inner flaps 63 and 64 and bonded together with an adhesive.

[0047] The right end plate 70 includes a pair of upper and lower outer flaps 71, 72 connected to the right edges of the bottom plate 51 and the top plate 52, respectively, and a pair of front and rear inner flaps 73, 74 connected to the right edges of the front plate 53 and the rear plate 54, respectively. The upper outer flap 72 is attached to the right edge of the top plate 52 via a right break guide line L22. The right end plate 70 has outer flaps 71 and 72 superimposed on the outer surfaces of inner flaps 73 and 74, which are bonded together with an adhesive.

[0048] Note that handles 7, 7 are formed on the upper rear portion of the left end plate 60 and the upper front portion of the right end plate 70. A tear strip 6 is attached from the front plate 53 to the left and right inner flaps 63, 73. Similarly, a tear strip 6 is attached from the rear plate 54 to the left and right inner flaps 64, 74.

[0049] The top plate 52 has break initiation portions 25, 25, a front break guide line L21, a left break guide line L22, and a right break guide line L22. That is, the top plate 52 can be opened by cutting open the front break guide line L21, the left break guide line L22, and the right break guide line L22, using the break initiation portions 25, 25 as the break initiation point. Furthermore, the top plate 52 has an engagement portion 24 and a top plate folding guide line 28. The top plate folding guide line 28 is made up of a folding line L28c formed in the center of the top plate 52 in the front-to-rear direction, spanning the left and right edges. Score lines are formed at intervals in the folding line L28c.

[0050] When the packaging box 1A of this embodiment is to be transported or stored with contents placed therein, the packaging box 1A is placed with the top plate 52 facing upward, similar to a typical wrap-around cardboard box (see FIG. 6). 8, the worker presses the breaking initiation portions 25, 25 of the top plate 52 with his / her fingers, and then grasps the front corners of the top plate 52 with his / her fingers and pulls it up. This causes the front breaking guide line L21 to be cut open, as well as the left breaking guide line L22 and the right breaking guide line L22, and the top plate 52 is raised above the rear plate 54, with the upper edge of the rear plate 54 serving as the center of rotation.

[0051] Thereafter, as shown in Figure 9, the front side of top plate 52 is bent forward along top plate folding guide line 28 of top plate 52, folding top plate 20 in half in the front-to-rear direction. Then, fingers are placed on engagement piece 26 of engagement portion 24, and engagement piece 26 is pushed toward opening piece 27, causing engagement piece 26 to push open opening piece 27. This causes engagement piece 26 to engage with the opening edge bordered by left and right cut lines L27a (not shown in Figure 9), and top plate 52 is engaged in the folded state.

[0052] In the packaging box 1A of this embodiment described above, as in the first embodiment, the top panel 52 folded in half can be used as a signboard for display, which provides excellent product displayability. In addition, in the packaging box 1A of this embodiment, break initiation portions 25, 25, which serve as the starting points for breaking, are provided on the top plate 52. Furthermore, a front break guide line L21, a left break guide line L22, and a right break guide line L22 for cutting open the top plate 52 are formed on the front, left, and right edges of the top plate 52. Therefore, the strength of the packaging box 1A can be ensured compared to when break initiation portions and break guide lines for opening the top plate are formed within the surfaces of the front and rear side plates 53, 54. As a result, the strength of the packaging box 1A is less likely to decrease even when a large load or impact is applied during product transportation, etc.

[0053] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be modified as appropriate within the scope of the invention. For example, in the above-described embodiments, the fracture initiation portions 25, 25 are formed at the left and right corners of the front of the top plates 20, 52. However, this is not limited thereto, and the fracture initiation portions 25, 25 may be formed at other locations on the front edge of the top plates 20, 52. In the example shown in FIG. 10, the fracture initiation portions 25A are formed at positions away from the left and right corners of the top plate 20. The fracture initiation portions 25A are defined by frame-shaped lines (including cut lines) on the front edge of the top plate 20, and have cut lines L25d, L25d on the inside. The number and shape of the fracture initiation portions 25A can be set as desired.

[0054] In addition, in each of the above embodiments, the top plates 20, 52 are folded in half at the center of the front-to-rear direction of the top plates 20, 52, but this is not limited to this. The top plates 20, 52 may be folded in half to different sizes at the front and rear by shifting the butt joint position and the position of the top plate folding guide line 28 in the front-to-rear direction.

[0055] The packaging boxes 1, 1A of the present embodiment are made of corrugated cardboard, but the packaging boxes may also be made of various known paperboards. [Explanation of symbols]

[0056] 1 packaging box 1A packaging box 11 Front plate (side plate) 12 Rear plate (side plate) 13 Left side plate (side plate) 14 Right side plate (side plate) 20 Top plate 24 Engagement part 25 Break initiation 25A Break start 28 Top plate bend guide line 30 Bottom plate 51 Bottom plate 52 Top plate 53 Front plate (side plate) 54 Rear plate (side plate) 60 End plate (side plate) 70 End plate (side plate) L23 Bend guide line L25 Bend guide line

Claims

[Claim 1] The front, back, left and right side panels, a top plate connected to the upper edges of the front, rear, left, and right side plates; A packaging box comprising: a bottom plate connected to the lower edge portions of the front, rear, left, and right side plates; a front break guide line formed along the front edge of the top plate; a left break guide line formed along the left edge of the top plate; a right break guide line formed along the right edge of the top plate; A break initiation portion formed on the top plate and serving as a break initiation portion of the front break guide wire; a top plate folding guide line provided in the plane of the top plate and parallel to the front edge of the top plate for folding the top plate in half forward and backward; and an engaging portion provided at the front and rear of the top plate across the top plate bending guide line, which engages the surfaces of the top plate folded in half along the top plate bending guide line, The top plate is front and rear upper outer flaps connected to upper edge portions of the front and rear side plates; left and right upper inner flaps connected to upper edge portions of the left and right side plates and overlapping the lower surfaces of the front and rear upper outer flaps; The front and rear upper outer flaps are butted against each other at the center in the front-rear direction, The top plate folding guide lines are formed on the left and right upper inner flaps along the butt joints of the front and rear upper outer flaps, The packaging box is characterized in that the engaging portion is provided on the front upper outer flap and the rear upper outer flap, with the abutting portion of the front and rear upper outer flaps as the boundary.

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