Packing box

Abstract

To provide a packing box capable of suppressing separation of an insertion piece from an insertion hole.SOLUTION: A packing box 1 comprises: a pair of lower inner flaps 12 connected with a pair of first side walls 10; a pair of lower outer flaps 13 connected with a pair of second side walls 11; insertion apertures 25 formed in the pair of lower inner flaps 12; and insertion pieces 35 defined by a pair of slits 30 in the pair of lower outer flaps 13. The insertion aperture 25 has a pressed-in recessed part 27 recessed to widen an insertion opening part 26. The insertion piece 35 has a pair of engagement parts 37 protruding from both sides of an insertion body part 36. The insertion body part 36 is inserted into the insertion opening part 26, and the pair of engagement parts 37 is covered with both side edge parts 28 of the insertion opening part 26 from a top surface of the lower inner flap 12, and then, the insertion body part 36 exposed from the press-in recessed part 27 is pressed in, so that the pair of engagement parts 37 enters the insertion opening part 26 to engage with both the side edge parts 28 of the insertion opening part 26 from a reverse side of the lower inner flap 12.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] A paperboard packaging box is known in which bottom-forming flaps are connected to the lower ends of two pairs of opposing side panels (Patent Document 1). One pair of bottom-forming flaps (hereinafter referred to as "inner flaps") has a diagonal cutout (hereinafter referred to as "first cutout") formed therein for inserting the leading edge corners of the other pair of bottom-forming flaps (hereinafter referred to as "outer flaps"). The outer flaps have a cutout (hereinafter referred to as "second cutout") formed at a right angle toward the oblique side. When the leading edge corners of the outer flaps are inserted into the first cutout, the leading edges of the outer flaps overlap the inner flaps from below, and the inner flaps are sandwiched between the leading edge corners and leading edges from above and below. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-104377 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described packaging box, the leading corners of the outer flaps are essentially inserted into the first notches of the inner flaps, so that the leading corners can be easily pulled out of the first notches. This raises the risk of the bottom of the packaging box collapsing due to the weight of the items stored in the packaging box or vibrations during transportation.

[0005] In order to solve the above problem, the present invention provides a packaging box that can prevent an insertion piece from coming off an insertion hole. [Means for solving the problem]

[0006] In order to achieve the above object, the packaging box of the present invention comprises a peripheral wall formed into a cylindrical shape by alternately connecting a pair of first side walls and a pair of second side walls, a pair of inner flaps connected to the pair of first side walls and folded in a direction to close an opening of the peripheral wall, a pair of outer flaps connected to the pair of second side walls and folded in a direction to close the opening of the peripheral wall and stacked on the pair of inner flaps, an insertion hole formed in at least one of the pair of inner flaps, and an insertion piece defined by a pair of slits in a corner region of at least one of the pair of outer flaps, wherein the insertion hole has an insertion opening into which the insertion piece is inserted and a slit for inserting the insertion opening. and a push-in recess formed so as to widen toward the tip end in the insertion direction, and the insertion piece has an insertion main body portion connected to the outer flap via an insertion fold line formed between the pair of slits, and a pair of engaging portions protruding from both sides of the insertion main body portion in the width direction perpendicular to the insertion direction, and after the insertion main body portion is inserted into the insertion opening in a state bent at the insertion fold line and the pair of engaging portions are covered from the surface of the inner flap to both side edges of the insertion opening, the insertion main body portion exposed in the push-in recess is pushed in, so that the pair of engaging portions enter the insertion opening and engage with the both side edges of the insertion opening from the back surface of the inner flap.

[0007] In this case, the base edge portion that is the base end of the insertion direction of the insertion opening is inclined with respect to the boundary line between the first side wall and the inner flap, the insertion fold line is inclined at an angle that makes it parallel to the base edge portion when the insertion piece is inserted into the insertion hole, the side edges of the insertion opening are inclined so as to move away from each other from both ends of the base edge portion toward the tip in the insertion direction, the pair of slits are inclined so as to move away from each other from both ends of the insertion fold line toward the tip in the insertion direction, the inclination angle of the slits with respect to the insertion fold line is set larger than the inclination angle of the side edges with respect to the base edge of the insertion opening, and the engaging edges of the engaging portions divided by the slits may intersect with the side edges of the insertion opening when the insertion piece is inserted into the insertion hole.

[0008] In this case, the pair of slits have a pair of first cut portions that curve toward each other near both ends of the insertion fold line, a pair of second cut portions that extend linearly from the tips of the pair of first cut portions so as to move away from each other, and a pair of third cut portions that extend from the tips of the pair of second cut portions to the outer end of the outer flap while slanting toward each other, and when the insertion piece is inserted into the insertion hole, the base end of the insertion piece separated by the pair of first cut portions may have a gap between it and both side edges of the insertion opening.

[0009] In this case, the insertion hole may be formed by bending an opening forming piece defined by a cut line that is cut leaving one side that serves as the base end in the insertion direction, toward the inside of the peripheral wall. [Effects of the Invention]

[0010] According to the present invention, it is possible to prevent the insertion piece from coming off the insertion hole. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing a packaging box according to an embodiment of the present invention. [Figure 2] 1 is a plan view showing a blank for a packaging box according to an embodiment of the present invention. FIG. [Figure 3] 1 is a plan view showing a part of a lock structure portion of a packaging box blank according to one embodiment of the present invention. FIG. [Figure 4] 1 is a perspective view illustrating a process of assembling a packaging box according to an embodiment of the present invention. [Figure 5] 10A and 10B are bottom views illustrating the right part of the packaging box according to one embodiment of the present invention, and explaining the partially locked state and the locked state. [Figure 6] 10A and 10B are perspective views (plan views) illustrating the inside of the right part of the packaging box according to one embodiment of the present invention, and explaining a temporary lock state and a locked state. [Figure 7] 1 is a graph showing the results of a bottom penetration strength test of a packaging box according to one embodiment of the present invention. [Figure 8]10 is a plan view showing a part of a lock structure portion of a packaging box blank according to a modified example of an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that Fr, Rr, L, R, U, and D in the drawings indicate front, rear, left, right, top, and bottom. The front-to-back, left-to-right, and top-to-bottom directions are perpendicular to one another. Terms indicating directions and positions are used in this specification, but these terms are used for convenience of explanation and do not limit the technical scope of the present invention. Furthermore, the terms indicating directions and positions are based on the directions and positions when assembling the packaging box.

[0013] A packaging box 1 according to one embodiment will be described with reference to Figures 1 to 3. Figure 1 is a perspective view showing the packaging box 1. Figure 2 is a plan view showing a blank 1A of the packaging box 1. Figure 3 is a plan view showing a part of a lock structure 17.

[0014] As shown in FIG. 1, the packaging box 1 is a so-called A-type cardboard box, and includes a peripheral wall W formed in a substantially rectangular cylindrical shape and a plurality of flaps 12 to 15 (upper flaps 14, 15 are not shown) that close the openings at the top and bottom ends of the peripheral wall W. As will be described in detail later, the lower flaps 12, 13 are held in a state in which the openings are closed without using staples, adhesives, adhesive tape, or the like. Note that FIG. 1 and other figures show a state in which the bottom of the packaging box 1 faces upward. Therefore, when actually using the packaging box 1, the packaging box 1 shown in FIG. 1 is used upside down.

[0015] The packaging box 1 is formed by assembling blanks 1A shown in FIG. 2. The blank 1A is formed by punching out a single cardboard sheet using a die or the like. The cardboard sheet is, for example, a double-sided cardboard sheet in which a front liner 9B and a back liner 9C (see FIG. 4 described later) are attached to a corrugated core 9A. The core 9A extends along the axial direction of the peripheral wall W and from the base ends of the multiple flaps 12 to 15 to their tips (free ends). Note that FIGS. 2 and 3 show the front liner 9B side (the outer surface of the packaging box 1). In this specification, the direction parallel to the core 9A of the cardboard sheet is referred to as the "corrugation direction," and the direction perpendicular to the corrugation direction is referred to as the "flow direction." In the drawings, "X" indicates the "corrugation direction," and "Y" indicates the "flow direction."

[0016] [blank] 2, the blank 1A includes a pair of first side walls 10, a pair of second side walls 11, a pair of lower inner flaps 12, a pair of lower outer flaps 13, a pair of upper inner flaps 14, and a pair of upper outer flaps 15. Since the pair of regions have substantially the same shape, hereinafter, only one region will be described unless otherwise specified.

[0017] <First side wall, second side wall> A pair of first side walls 10 and a pair of second side walls 11 are alternately connected in the flow direction via a first fold line L1. The first side walls 10 and the second side walls 11 are formed in a substantially rectangular shape. More specifically, the first side walls 10 are formed in a substantially rectangular shape that is longer in the flow direction than the second side walls 11. A joining piece 16 is connected to one end of the first side walls 10 in the flow direction via the first fold line L1.

[0018] <Lower inner flap, lower outer flap> The lower inner flap 12 is connected to one end (lower end) of the first side wall 10 in the corrugation direction via the second fold line L2. The lower outer flap 13 is connected to one end (lower end) of the second side wall 11 in the corrugation direction via the second fold line L2. The lower inner flap 12 and the lower outer flap 13 are each formed in a substantially rectangular shape, and their dimension in the corrugation direction (extension dimension) is set to approximately half the dimension of the second side wall 11 in the flow direction.

[0019] <Upper inner flap, upper outer flap> The upper inner flap 14 is connected to the other end (upper end) in the corrugation direction of the second side wall 11 via the third fold line L3. The upper outer flap 15 is connected to the other end (upper end) in the corrugation direction of the first side wall 10 via the third fold line L3. The upper inner flap 14 has a generally rectangular shape that is generally the same size as the lower outer flap 13, and the upper outer flap 15 has a generally rectangular shape that is generally the same size as the lower inner flap 12.

[0020] The first to third fold lines L1 to L3 are general-purpose creases formed by crushing the cardboard sheet in the thickness direction from the rear liner 9C side. The general-purpose creases have the function of folding the cardboard sheet (mountain fold or square fold) so that the rear liner 9C faces inward. The first to third fold lines L1 to L3 are not limited to general-purpose creases, and may be any structure for folding the cardboard sheet in the desired direction, such as perforation lines formed by cutting multiple lines at predetermined intervals or lead creases formed by perforation lines on general-purpose creases.

[0021] [Lock structure] As shown in Figure 2, the pair of lower inner flaps 12 and the pair of lower outer flaps 13 are provided with a locking structure 17 that keeps the opening below the peripheral wall W closed. The locking structure 17 has two pairs of opening-forming pieces 20, four pairs of slits 30, and two pairs of insertion pieces 35. A pair of opening-forming pieces 20 is formed on both sides of each lower inner flap 12 in the flow direction, and two pairs of slits 30 and a pair of insertion pieces 35 are formed on both sides of each lower outer flap 13 in the flow direction.

[0022] In the following description, with reference to Figure 3, the description will focus on one lower inner flap 12 and one lower outer flap 13. Furthermore, since the two opening-forming pieces 20 formed on one lower inner flap 12 are formed symmetrically with respect to a line that bisects the lower inner flap 12 in the flow direction, unless otherwise specified, the description will focus on one opening-forming piece 20. Similarly, the description will focus on one slit 30 and one insertion piece 35.

[0023] <Aperture forming piece> As shown in Figure 3, the opening-forming piece 20 is defined by a press-in cutting line 23 cut into the lower inner flap 12, leaving one edge (the edge serving as the base end in the insertion direction) on the end side in the flow direction. The press-in fold line L4 formed on the remaining edge is formed as a straight line inclined at an angle θ1 of approximately 45 degrees with respect to the second fold line L2 (the boundary line between the first side wall 10 and the lower inner flap 12). In other words, the press-in fold line L4 intersects with the center core 9A at an angle of approximately 45 degrees. As will be described in detail later, the opening-forming piece 20 is folded toward the inside of the peripheral wall W at the press-in fold line L4 and cut and raised from the lower inner flap 12 along the press-in cutting line 23, thereby forming an insertion hole 25 into which the insertion piece 35 is inserted.

[0024] The opening-forming piece 20 (pressed cutting line 23) is formed in a generally trapezoidal shape that widens from the pressed fold line L4 toward the base end of the lower inner flap 12. The opening-forming piece 20 is formed symmetrically about a center line CL1 that extends at an angle of 45 degrees from the tip corner of the lower inner flap 12 toward the second fold line L2 (in the insertion direction). The opening-forming piece 20 has a piece main body portion 21 that is connected to the upper inner flap 14 via the pressed fold line L4, and a pressed protrusion 22 that protrudes from the tip of the piece main body portion 21. The piece main body portion 21 is formed in a generally trapezoidal shape in the main portion of the opening-forming piece 20. The base end sides of the piece main body portion 21 (pressed cutting line 23), which are near both ends of the pressed fold line L4, are curved. The push-in protrusion 22 is provided in a generally triangular (mountain-shaped) shape at the center of the one main body portion 21 in the width direction (direction perpendicular to the center line CL1 (insertion direction)).

[0025] (insertion hole) The insertion hole 25 has an insertion opening 26 that opens at the position where the piece main body portion 21 is cut and raised, and a push-in recess 27 that opens at the position where the push-in protrusion 22 is hollowed out. The insertion opening 26 is an opening into which the insertion piece 35 is mainly inserted, and both side edges 28 of the insertion opening 26 curve near both ends of the push-in fold line L4 (base end edge) and then slope away from each other toward the tip in the insertion direction. The inclination angle θ2 (the angle between the push-in fold line L4 and the side edge 28) of the side edge 28 (straight portion) relative to the push-in fold line L4 (base end edge of the insertion opening 26) is set to, for example, approximately 120 degrees. The push-in recess 27 is recessed so as to widen the insertion opening 26, into which the insertion piece 35 is inserted, toward the tip in the insertion direction.

[0026] <Slit> The pair of slits 30 are cuts that define the insertion piece 35 in the corner region on the tip side of the lower outer flap 13. One of the pair of slits 30 is cut from the tip of the lower outer flap 13 toward the base end, and the other of the pair of slits 30 is cut from the outer edge of the lower outer flap 13 toward the inside. An insertion fold line L5 is formed linearly between the base ends of the pair of slits 30. The insertion fold line L5 is inclined at an angle θ3 of approximately 45 degrees with respect to the second fold line L2 (the boundary line between the second side wall 11 and the lower outer flap 13). As will be described in detail later, the insertion fold line L5 is inclined at an angle that makes it parallel to the push-in fold line L4 (the base edge) when the insertion piece 35 is inserted into the insertion hole 25. Note that "parallel" does not mean that perfect parallelism is required, but rather that slight inclination or misalignment is allowed.

[0027] The pair of slits 30 are inclined away from each other from both ends of the insertion fold line L5 toward the tip in the insertion direction. Specifically, the pair of slits 30 have a pair of first cutouts 31 that curve toward each other near both ends of the insertion fold line L5, a pair of second cutouts 32 that extend linearly from the tips of the pair of first cutouts 31 so as to move away from each other, and a pair of third cutouts 33 that extend from the tips of the pair of second cutouts 32 to the outer end of the lower outer flap 13 while inclining toward each other. The insertion fold line L5 is formed at a position where the spacing between the pair of first cutouts 31 narrows. The dimension W2 between the base ends of the pair of first cutouts 31 is approximately the same as the dimension W1 between the inflection points at the base end of the insertion hole 25 (opening-forming piece 20). The inclination angle θ4 of the second cut portion 32 relative to the insertion fold line L5 (the angle formed between the insertion fold line L5 and the second cut portion 32) is, for example, approximately 148 degrees, which is set larger than the inclination angle θ2 of the side edge portion 28 of the insertion opening 26.

[0028] <insertion piece> A pair of insertion pieces 35 constitute both corners of the leading edge of the lower outer flap 13 (see FIG. 2). The insertion pieces 35 are formed in a generally arrow-shaped configuration that is symmetrical about a center line CL2 extending at a 45-degree angle from the leading edge corner of the lower outer flap 13 toward the second fold line L2 (in the insertion direction). The insertion pieces 35 are formed so that their maximum dimensions in the insertion direction and width direction are larger than those of the insertion hole 25. The insertion pieces 35 have an insertion body portion 36 connected to the lower outer flap 13 via the insertion fold line L5 and a pair of engagement portions 37 protruding from both sides of the insertion body portion 36 in the width direction perpendicular to the center line CL2 (insertion direction). The insertion body portion 36 is defined between a pair of imaginary lines VL that extend parallel to the center line CL2 from both ends of the insertion fold line L5 toward the outer edge of the lower outer flap 13. The pair of engagement portions 37 are in the outer regions of the pair of imaginary lines VL and are formed in a substantially triangular shape that is line-symmetric with respect to the insertion body portion 36 as the center.

[0029] A pressing piece 38 is provided between the pair of insertion pieces 35 at the tip side of the lower outer flap 13 (see FIG. 2). The pressing piece 38 is formed in a generally trapezoidal shape that gradually narrows in the flow direction toward the tip side (see FIG. 2).

[0030] Although the push-in fold line L4 and the insert fold line L5 are general-purpose creases, they are not limited to these and may be any other structure, such as a lead crease, that allows the cardboard sheet to be folded in a desired direction.

[0031] [Assembly of packaging boxes] Next, the assembly process of the packaging box 1 will be described with reference to Figures 1 and 4 to 6. Figure 4 is a perspective view illustrating the process of assembling the packaging box 1. Figure 5 is a bottom view showing the right part of the packaging box 1. Figure 6 is a perspective view (plan view) showing the inside of the right part of the packaging box 1. Here, as an example, a case where a worker manually assembles the packaging box 1 will be described. Note that in the initial state before assembling the packaging box 1, the first side wall 10 and the second side wall 11 located on both outer sides in the flow direction of the blank 1A are folded along the first fold line L1, the joint piece 16 is adhered to the inner surface of the second side wall 11 on the opposite side, and the packaging box 1 is double-folded (not shown).

[0032] The worker bends the pair of first side walls 10 and the pair of second side walls 11 at approximately right angles along the first folding line L1. The pair of first side walls 10 and the pair of second side walls 11 are alternately connected in the circumferential direction to form a rectangular cylindrical peripheral wall W (see FIG. 4).

[0033] Next, the worker closes the bottom surface (opening) of the peripheral wall W with the pair of lower inner flaps 12 and the pair of lower outer flaps 13, and secures the pair of lower outer flaps 13 in a stacked state on the pair of lower inner flaps 12 using the locking structure 17. Note that the securing procedure for the pair of lower outer flaps 13 is the same, so the following description will focus mainly on one lower outer flap 13. In addition, in this specification, the lower inner flaps 12 and the lower outer flaps 13 form the bottom surface of the packaging box 1, but will be described as facing upward in consideration of workability during assembly.

[0034] As shown in FIG. 4, the worker folds the pair of lower inner flaps 12 along the second fold line L2 in a direction that closes the bottom surface (opening) of the peripheral wall W. The tips of the pair of lower inner flaps 12 are butted together. Next, the worker folds the pair of insertion pieces 35 downward (inward) along the insertion fold line L5, and presses the tips of the pair of insertion pieces 35 against the pair of opening-forming pieces 20 provided on the pair of lower inner flaps 12 while folding the lower outer flap 13 along the second fold line L2 in a direction that closes the bottom surface of the peripheral wall W. The insertion pieces 35 assume a position that is inclined downward from the insertion fold line L5 toward the tips, and the base end surfaces of the pair of engagement portions 37 (hereinafter referred to as "engagement edges 37A") separated by the pair of slits 30 are exposed.

[0035] The worker further folds the lower outer flap 13, pushes the pair of insertion pieces 35 diagonally downward, and folds the pair of opening-forming pieces 20 inward toward the peripheral wall W along the fold line L4. The opening-forming pieces 20 are bent at the fold line L4 and punched out of the lower inner flap 12 along the cut line 23, leaving an insertion hole 25 where the opening-forming pieces 20 were punched out (see the right side of FIG. 4). As shown on the left side of FIG. 4, the upper part of FIG. 5, and the upper part of FIG. 6, the insertion body portion 36 of the insertion piece 35 is inserted into the insertion opening 26 of the insertion hole 25 while bent at the fold line L5. The pair of engagement portions 37 of the insertion piece 35 are not inserted into the insertion hole 25 but are covered on both side edges 28 of the insertion opening 26 from the surface of the lower inner flap 12 (see the upper part of FIG. 5).

[0036] In this state, the engaging portion 37 simply rests on the side edge 28 of the insertion opening 26. Therefore, the insertion piece 35 (insertion main body 36) is in a temporary locked state S1 in which it can be easily pulled out of the insertion hole 25 (insertion opening 26). In the temporary locked state S1 (a state in which the insertion piece 35 is inserted into the insertion hole 25), the base end of the insertion piece 35, which is separated by the pair of first cutouts 31, has a gap G between it and the side edge 28 of the insertion opening 26 (see the upper part of Figure 5). The insertion fold line L5 is arranged so as to roughly overlap the base end edge (press-in fold line L4) of the insertion hole 25. The pressing piece 38 overlaps the surface of the pair of lower inner flaps 12 (see the left side of Figure 4).

[0037] After achieving the temporary locked state S1, the operator pushes the exposed insertion body 36 into the push-in recess 27 of the insertion hole 25. As the insertion body 36 is pushed in, the pair of engagement portions 37 (or the entire insertion pieces 35) bend (elastically deform) and enter the insertion opening 26. At this time, because the third cutout 33 of the slit 30 is bent slightly inward relative to the second cutout 32 (see FIG. 5, etc.), there is less overlap between the engagement edge 37A of the engagement portion 37 and the side edges 28 of the insertion opening 26, making it easier for the engagement portion 37 to enter the insertion opening 26.

[0038] As a result of the above, as shown in Figures 1, the lower part of Figure 5, and the lower part of Figure 6, a locked state S2 is reached in which the pair of engaging portions 37 engage with the side edges 28 of the insertion opening 26 from the back surface of the lower inner flap 12. In the locked state S2, the engaging edges 37A of the engaging portions 37 separated by the slits 30 intersect with the side edges 28 of the insertion opening 26, thereby restricting the insertion pieces 35 from being pulled out of the insertion holes 25. In addition, the pressing pieces 38 overlap the surfaces of the pair of lower inner flaps 12 (see Figure 1), and the pair of lower inner flaps 12 are sandwiched between the pair of insertion pieces 35 and the pressing pieces 38. Note that even in the locked state S2, a gap G is maintained between the base ends of the insertion pieces 35 and the side edges 28 of the insertion opening 26 (see the lower part of Figure 5).

[0039] In this way, the bottom surface of the packaging box 1 is formed without using adhesive tape or the like. The worker places a product (not shown) inside the peripheral wall W. The placed product is placed on the insert piece 35 and the opening forming piece 20, which presses down on the insert piece 35, etc. This makes it possible to firmly restrict the insertion piece 35 from being pulled out.

[0040] Next, the worker closes the top surface (opening) of the peripheral wall W (seals the packaging box 1). The worker folds the pair of upper inner flaps 14 along the third fold line L3 in a direction to close the top surface (opening) of the peripheral wall W, and then folds the pair of upper outer flaps 15 along the third fold line L3 in a direction to close the top surface of the peripheral wall W. The pair of upper outer flaps 15 are stacked on the pair of upper inner flaps 14 with their tips butted together (not shown). The worker applies adhesive tape along the butted portion of the pair of upper outer flaps 15 (not shown).

[0041] In this way, the top surface of the packaging box 1 is formed and the packaging box 1 is sealed (see FIG. 1). The upper outer flap 15 may be fixed to the upper inner flap 14 via staples or adhesive instead of adhesive tape.

[0042] [Bottom break strength test] The applicant conducted a bottom-break strength test on the packaging box 1 according to this embodiment. This test was also conducted on the packaging box 1 according to this embodiment, as well as on the cardboard box shown in Figure 1 of Japanese Patent No. 3897737 as a comparative example. The packaging box 1 and the cardboard box according to the comparative example (hereinafter referred to as "packaging box 1, etc.") are formed with cardboard sheets of the same thickness and with the same dimensions.

[0043] Figure 7 is a graph showing the results of the bottom puncture strength test. In the bottom puncture strength test, the load applied to the bottom surface (lower inner flap 12 and lower outer flap 13) of the packaging box 1 or the like was changed (increased) and the amount of downward deflection of the bottom surface (how many mm it bulged downward) was measured. The position where the bottom surface was approximately horizontal was defined as "0 mm." The various test conditions, such as temperature and humidity, were in accordance with the specifications of the Japanese Industrial Standards.

[0044] As shown in Fig. 7, when a load of 50 N was applied to the bottom surface, the cardboard box according to the comparative example deflected by more than 20 mm, whereas the packaging box 1 according to the present embodiment deflected by less than 10 mm. Furthermore, even when the load applied to the bottom surface was increased, a similar tendency to that in the case of 50 N was observed. As described above, it was confirmed that the packaging box 1 according to the present embodiment has a higher bottom-opening strength than the cardboard box according to the comparative example.

[0045] In the packaging box 1 according to the present embodiment described above, the insertion body 36 is inserted into the insertion opening 26, and the pair of engagement portions 37 are positioned over the surface of the lower inner flap 12 and cover both side edges 28 of the insertion opening 26, resulting in a temporary lock state S1. Furthermore, by pushing the insertion body 36 exposed in the push-in recess 27 from the temporary lock state S1, the pair of engagement portions 37 enter the insertion opening 26 and engage with both side edges 28 of the insertion opening 26 from the back surface of the lower inner flap 12, resulting in a locked state S2. By shifting to the locked state S2, the pair of engagement portions 37 are caught on both side edges 28 of the insertion hole 25, thereby preventing the insertion piece 35 from coming off the insertion hole 25. This securely locks the lower outer flap 13 and the lower inner flap 12 together, preventing the packaging box 1 from falling out. Furthermore, since the push-in recess 27 is formed so as to widen the insertion opening 26 toward the tip in the insertion direction, the operator can push in the tip side of the insertion piece 35 (insertion main body 36) that is away from the insertion folding line L5. This allows the operator to push the insertion piece 35 (pair of engagement portions 37) into the insertion hole 25 with a small force, and easily switch from the temporary locked state S1 to the locked state S2.

[0046] Furthermore, in the packaging box 1 according to this embodiment, the pair of slits 30 are formed so as to extend outward beyond both side edges 28 of the insertion opening 26, and the engaging edge 37A of the engaging portion 37 intersects with the side edge 28 of the insertion opening 26. With this configuration, in the locked state S2, the engaging portion 37 can be stacked (facing) on ​​the back surface of the lower inner flap 12, thereby firmly restricting the removal of the insertion piece 35.

[0047] Furthermore, in the packaging box 1 according to this embodiment, the tip portion (third cut portion 33) of the slit 30 is bent slightly inward relative to the second cut portion 32. With this configuration, when switching from the temporary-locked state S1 to the locked state S2, the overlap of the engaging portion 37 with the side edge portion 28 of the insertion opening 26 can be reduced, allowing the engaging portion 37 to be smoothly pushed into the insertion opening 26. Furthermore, the base end portion (first cut portion 31) of the slit 30 is curved to bulge inward, and when the insertion piece 35 is inserted into the insertion opening 26, a gap G is formed between the base end of the insertion piece 35 and the side edge portion 28 of the insertion opening 26. With this configuration, when switching from the temporary-locked state S1 to the locked state S2, interference of the base portion of the insertion piece 35 with the edge portion of the insertion opening 26 can be prevented, making it easier to push the engaging portion 37 into the insertion opening 26.

[0048] Furthermore, according to the packaging box 1 of this embodiment, the opening forming piece 20 clamps the insertion piece 35 inserted into the insertion hole 25 by using the restoring force around the push-in fold line L4 (the side that serves as the base end), thereby further firmly restricting the removal of the insertion piece 35.

[0049] [Variations] In the packaging box 1 according to the present embodiment, two opening-forming pieces 20 (insertion holes 25) are provided in each lower inner flap 12, and two pairs of slits 30 and a pair of insertion pieces 35 (hereinafter referred to as "insertion pieces 35, etc.") are provided in each lower outer flap 13, but the present invention is not limited to this. At least one opening-forming piece 20 (insertion hole 25) may be provided in at least one of the pair of lower inner flaps 12 (not shown). Also, at least one insertion piece 35, etc. may be provided in at least one of the pair of lower outer flaps 13 (not shown).

[0050] Furthermore, in the packaging box 1 according to the present embodiment, the insertion hole 25 is opened by folding the opening-forming piece 20, but the present invention is not limited to this. The opening-forming piece 20 (press-in cutting line 23) may be omitted, and the insertion hole 25 may be punched in the lower inner flap 12 (not shown). In this case, it is sufficient that the base edge portion of the insertion hole 25, which is the base end of the insertion opening 26 in the insertion direction, is inclined with respect to the second fold line L2.

[0051] Furthermore, in the packaging box 1 according to the present embodiment, the slit 30 is a cut line. However, this is not limited thereto, and the slit 30 may be formed in a groove shape (notch shape) having a width (see FIG. 8 described later). Furthermore, while the slit 30 is composed of the first to third cut portions 31 to 33, the present invention is not limited thereto. For example, the slit 30 may be formed as a single straight line, or may be formed in a slightly curved arc shape so as to approach or move away from each other (neither is shown). Similarly to the slit 30, the side edge portions 28 of the insertion opening 26 may also be formed in a slightly curved arc shape so as to approach or move away from each other (not shown). When these are formed in an arc shape, the inclination angles θ2 and θ4 of the side edge portions 28 and the slit 30 (engagement edge portion 37A) may be the angles of the tangents at the intersections of the two edges (not shown).

[0052] In addition, in the packaging box 1 according to this embodiment, the angles θ1 and θ3 shown in FIG. 3 are set to approximately 45 degrees, the inclination angle θ2 to approximately 120 degrees, and the inclination angle θ4 to approximately 148 degrees, but these angles θ1 to θ4 are merely examples and may be changed as appropriate. Furthermore, while the insertion fold line L5 and the push-in fold line L4 (the base end edge of the insertion opening 26) are inclined with respect to the second fold line L2, the present invention is not limited to this. For example, as shown in FIG. 8, the insertion fold line L5 may be formed parallel to the second fold line L2, and the push-in fold line L4 may be formed perpendicular to the second fold line L2.

[0053] Furthermore, in the packaging box 1 according to this embodiment, the pressing piece 38 is provided on the lower outer flap 13, but this is not limiting, and the pressing piece 38 may be omitted (not shown).

[0054] Furthermore, in the packaging box 1 according to this embodiment, the locking structure 17 is provided on the lower inner flap 12 and the lower outer flap 13, but the present invention is not limited to this. The locking structure 17 may be provided on the upper inner flap 14 and the upper outer flap 15 instead of or in addition to the lower flaps 12 and 13 (not shown). In this case, the upper outer flap 15 may be provided with an opening-forming piece 20 (insertion hole 25), and the upper inner flap 14 may be provided with an insertion piece 35 or the like. In other words, the upper outer flap 15 may be the "inner flap" as defined in the claims, and the upper inner flap 14 may be the "outer flap" as defined in the claims.

[0055] Furthermore, in the packaging box 1 according to the present embodiment, the first side wall 10 (lower inner flap 12, upper outer flap 15) is formed in a generally rectangular shape that is longer in the flow direction than the second side wall 11 (lower outer flap 13, upper inner flap 14), but this is not limited thereto, and the first side wall 10, etc. may be formed in a generally rectangular shape that is shorter in the flow direction than the second side wall 11, etc., or may be formed in a generally rectangular shape that is the same as the second side wall 11, etc. (not shown). Furthermore, the joining piece 16 is connected to the end of the first side wall 10, but this is not limited thereto, and the joining piece 16 may be connected to the end of the second side wall 11 (not shown).

[0056] Furthermore, although the packaging box 1 according to this embodiment is a so-called A-type cardboard box, the present invention is not limited to this. For example, the packaging box may be a semi-A-type cardboard box in which the upper flaps 14, 15 are omitted (not shown). Alternatively, the packaging box may be another type of box (not shown) as long as it has multiple flaps that close the opening in the peripheral wall W. Furthermore, in the packaging box 1 according to this embodiment, the pair of lower inner flaps 12 and the pair of upper outer flaps 15 abut each other at their leading ends to completely close the opening in the peripheral wall W. However, this is not limiting, and the pair of lower inner flaps 12 and the pair of upper outer flaps 15 may be so-called short flaps that space their leading ends apart (not shown).

[0057] Furthermore, although the packaging box 1 according to this embodiment is formed from a double-sided corrugated cardboard sheet made of paper, the present invention is not limited to this. The packaging box 1 may be formed from single-sided corrugated cardboard, double-sided corrugated cardboard, triple-sided corrugated cardboard, etc., and may also be formed from cardboard or a resin plate (sheet) instead of corrugated cardboard. Furthermore, the dimensions (width, depth, height) and shape of each part of the packaging box 1, the thickness of the sheet, the extension direction of the core 9A, etc. may be freely changed.

[0058] The above embodiment shows one aspect of the packaging box according to the present invention, and the technical scope of the present invention is not limited to the above embodiment. The present invention may be variously changed, substituted, or modified within the scope of the technical idea, and the claims include all embodiments that may fall within the scope of the technical idea. [Explanation of symbols]

[0059] 1 packaging box 10 First side wall 11 Second side wall 12 Lower inner flap 13 Lower outer flap 20 Aperture forming piece 23 Push-in cutting line 25 Insertion hole 26 Insertion opening 27 Press-in recess 28 Side edge 30 slits 31 First cut 32 Second cut 33 Third cut 35 Insert 36 Insertion body 37 Engagement part 37A Engagement edge G Gap L2 2nd fold line (border line) L5 Insertion line W Peripheral wall θ2, θ4 Tilt angle

Claims

1. a cylindrical peripheral wall (W) formed by alternately connecting a pair of first side walls (10) and a pair of second side walls (11); a pair of inner flaps (12) connected to the pair of first side walls and bent in a direction to close the opening of the peripheral wall; a pair of outer flaps (13) connected to the pair of second side walls, folded in a direction to close the opening of the peripheral wall, and stacked on the pair of inner flaps; An insertion hole (25) formed in at least one of the pair of inner flaps; and an insertion piece (35) defined by a pair of slits (30) in at least one corner region of the pair of outer flaps, The insertion hole is an insertion opening (26) into which the insertion piece is inserted; a push-in recess (27) recessed so as to widen the insertion opening toward the tip end in the insertion direction, The insertion opening includes a base edge portion that is a base end in the insertion direction, and both side edge portions (28) that extend from both ends of the base edge portion toward the tip side in the insertion direction, The insert piece is an insertion body portion (36) connected to the outer flap via an insertion fold line (L5) formed between the pair of slits; a pair of engaging portions (37) protruding from both sides of the insertion body portion in a width direction perpendicular to the insertion direction, The pair of engaging portions have a pair of engaging edge portions (37A) which are base end surfaces separated by the pair of slits, The insertion body is inserted into the insertion opening in a state where it is bent at the insertion fold line, and the pair of engagement portions are placed in a temporary locked state (S1) where they are covered from the surface of the inner flap to the both side edges (28) of the insertion opening. Then, the insertion body exposed in the push-in recess is pushed in, whereby the pair of engagement portions enter the insertion opening and are placed in a locked state (S2) where they are engaged with the both side edges of the insertion opening from the back surface of the inner flap. In the temporary locking state, the insertion folding line is arranged to be parallel to and overlap the base end edge portion of the insertion opening, In the locked state, the pair of engaging edges intersect with the side edges of the insertion opening.

2. A peripheral wall (W) formed in a cylindrical shape by alternately connecting a pair of first side walls (10) and a pair of second side walls (11), a pair of inner flaps (12) connected to the pair of first side walls and bent in a direction to close the opening of the peripheral wall; a pair of outer flaps (13) connected to the pair of second side walls, folded in a direction to close the opening of the peripheral wall, and stacked on the pair of inner flaps; An insertion hole (25) formed in at least one of the pair of inner flaps; and an insertion piece (35) defined by a pair of slits (30) in at least one corner region of the pair of outer flaps, The insertion hole is an insertion opening (26) into which the insertion piece is inserted; a push-in recess (27) recessed so as to widen the insertion opening toward the tip end in the insertion direction, The insert piece is an insertion body portion (36) connected to the outer flap via an insertion fold line (L5) formed between the pair of slits; a pair of engaging portions (37) protruding from both sides of the insertion body portion in a width direction perpendicular to the insertion direction, The insertion body is inserted into the insertion opening in a state where it is bent at the insertion fold line, and the pair of engaging portions are provided covering both side edges (28) of the insertion opening from the surface of the inner flap, and then the insertion body exposed in the push-in recess is pushed in, so that the pair of engaging portions enter the insertion opening and engage with both side edges of the insertion opening from the back surface of the inner flap, a base end edge portion that is a base end of the insertion opening in the insertion direction is inclined with respect to a boundary line (L2) between the first side wall and the inner flap, The insertion folding line is inclined at an angle so as to be parallel to the base end edge portion when the insertion piece is inserted into the insertion hole, The side edges of the insertion opening are inclined so as to move away from each other from both ends of the base edge toward the tip in the insertion direction, The pair of slits are inclined so as to move away from each other from both ends of the insertion folding line toward the tip in the insertion direction, A packaging box characterized in that the inclination angle (θ4) of the slit relative to the insertion fold line is set larger than the inclination angle (θ2) of the side edge relative to the base edge of the insertion opening, and the engagement edge portion (37A) of the engagement portion divided by the slit intersects with the side edge portion of the insertion opening when the insertion piece is inserted into the insertion hole.

3. A peripheral wall (W) formed in a cylindrical shape by alternately connecting a pair of first side walls (10) and a pair of second side walls (11), a pair of inner flaps (12) connected to the pair of first side walls and bent in a direction to close the opening of the peripheral wall; a pair of outer flaps (13) connected to the pair of second side walls, folded in a direction to close the opening of the peripheral wall, and stacked on the pair of inner flaps; An insertion hole (25) formed in at least one of the pair of inner flaps; and an insertion piece (35) defined by a pair of slits (30) in at least one corner region of the pair of outer flaps, The insertion hole is an insertion opening (26) into which the insertion piece is inserted; a push-in recess (27) recessed so as to widen the insertion opening toward the tip end in the insertion direction, The insert piece is an insertion body portion (36) connected to the outer flap via an insertion fold line (L5) formed between the pair of slits; a pair of engaging portions (37) protruding from both sides of the insertion body portion in a width direction perpendicular to the insertion direction, The insertion body is inserted into the insertion opening in a state where it is bent at the insertion fold line, and the pair of engaging portions are provided covering both side edges (28) of the insertion opening from the surface of the inner flap, and then the insertion body exposed in the push-in recess is pushed in, so that the pair of engaging portions enter the insertion opening and engage with both side edges of the insertion opening from the back surface of the inner flap, The pair of slits are A pair of first cut portions (31) curved so as to approach each other near both ends of the insertion fold line; a pair of second cutouts (32) extending linearly from the tips of the pair of first cutouts so as to be spaced apart from each other; a pair of third cutouts (33) extending from the tips of the pair of second cutouts to the outer ends of the outer flaps while inclining toward each other; A packaging box characterized in that, when the insertion piece is inserted into the insertion hole, the base end of the insertion piece, which is divided by a pair of first cut portions, has a gap (G) between it and both side edges of the insertion opening.

4. The packaging box according to any one of claims 1 to 3, characterized in that the insertion hole is formed by bending an opening forming piece (20) defined by a push-in cutting line (23) cut in while leaving one side (L4) that is the base end in the insertion direction, toward the inside of the peripheral wall.

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