Blank

Abstract

To provide a blank that can maintain well a state in which a first face plate and a second face plate are bent and connected to a bottom face plate.SOLUTION: A blank of the present invention comprises a polygonal-shaped bottom face plate, a first face plate and a second face plate. The first face plate and the second face plate are bent with respect to the bottom face plate to form a box body, and the blank has at least one locking structure that maintains a connected state of the bent first and second face plates. The locking structure comprises a protruding piece that protrudes from an end of the first face plate towards the second face plate in a first direction, a slit provided in the second face plate, and a notch provided in the second face plate in a second direction and closer to the protruding piece than the slit and extending in the second direction, and the locking structure maintains the connected state by inserting the protruding piece, which is bent at a base end, into a gap formed by the slit and the notch opening.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a blank that is folded to form a box. [Background technology]

[0002] Various structures have been developed so far as blanks for assembling boxes such as packaging boxes, etc. One example is the blank described in Patent Document 1.

[0003] The blank described in Patent Document 1 (hereinafter, the blank in Document 1) is a blank for forming a box, and has a polygonal bottom panel, a first panel connected to one of two adjacent sides of the bottom panel that sandwich a vertex so as to be bent, and a second panel connected to the other side so as to be bent. The first panel can be folded along a first folding line provided between the bottom panel and the first panel, and has a first side panel portion that forms a side panel of the box at a position adjacent to the first folding line. The second panel can be folded along a second folding line provided between the bottom panel and the second panel, and has a second side panel portion that forms a side panel of the box at a position adjacent to the second folding line.

[0004] The blank in Document 1 has at least a locking structure configured such that when the first panel and the second panel are both folded, a connecting structure between the first panel and the second panel is formed at the apex of the bottom panel. The locking structure is composed of a flap portion provided at the edge of the first side panel portion and connected in a direction perpendicular to the first fold line, and a hook-shaped slit portion provided on the second panel, on the edge side of the second panel, inside the edge of the second panel, and extending from the second side panel portion outward with respect to the second fold line. When the second panel is folded along the second fold line relative to the bottom panel, the slit portion opens to form a gap portion and a second panel pressing portion. When the first panel is folded back in this state and the flap portion is folded back, the tip of the flap portion is inserted into the slit portion and the gap portion and pressed by the second panel pressing portion to form the connecting structure.

[0005] According to the blank of Document 1 configured as described above, a box body can be easily assembled. In addition, the blank of Document 1 can ensure the self-supporting and storability of a box body in a state where both the first panel and the second panel are folded, i.e., a box body in a partially assembled state. This can improve the storage efficiency (hereinafter also referred to as stackability) when a plurality of boxes in a partially assembled state are stacked and stored. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2022-123864 A Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, in the locking structure portion provided on the blank of Document 1, when the flap portion is inserted into the gap portion, the tip of the flap portion engages with the edge of the gap portion and is pressed by the second panel pressing portion, thereby maintaining (locking) the state in which the flap portion is inserted into the gap portion.

[0008] On the other hand, it is preferable that the flap portion can be easily inserted into the gap, but for example, when a thick blank is used, a repulsive force is generated when the flap portion is folded, so that the folded flap portion tries to return to its original state before folding, making it difficult to insert the tip of the flap portion into the gap. Also, if the slit portion is made larger for the purpose of making it easier to insert the flap portion into the gap, the tip of the flap portion inserted into the gap will easily come out of the gap, making it difficult to maintain the state in which the flap portion is inserted into the gap. In view of the above, there is a demand for a blank having a locking structure that allows the flap portion to be smoothly inserted into the gap while properly maintaining (locking) the state in which the flap portion is inserted into the gap, in other words, that better maintains the connecting structure between the first panel and the second panel.

[0009] The present invention aims to solve the problems of the conventional technology described above, and specifically, to provide a blank that can maintain the state in which the first panel and the second panel are folded and connected to the bottom panel in a good condition.

[0010] A second object of the present invention is to provide a blank for forming a box that can be easily opened after being sealed. A third object of the present invention is to provide a blank that allows a protruding piece portion (flap portion) of a lock structure portion to be more easily inserted into a gap portion. [Means for solving the problem]

[0011] In order to achieve the above object, the blank of the present invention comprises a polygonal bottom panel, a first panel extending from one of two adjacent sides that sandwich an apex of the bottom panel, and a second panel extending from the other of the two sides, and the first and second panel are folded relative to the bottom panel to form a box-shaped blank, and has at least one locking structure that maintains a connected state in which the folded first and second panel are connected with their apex in between, and the locking structure comprises a protruding piece that protrudes from an end of the first panel side facing the second panel in a first direction in which the second panel extends and is bendable at its base end in the first direction, a slit section provided in the second panel, and a slit section provided in the second panel, the protruding piece side of the slit section in a second direction intersecting the first direction and extending from the slit section along the second direction, and the connected state is maintained by inserting the protruding piece bent at its base end into a gap formed by the opening of the slit section and the slit section.

[0012] In the blank of the present invention, the above-mentioned configuration makes the gap wider, making it easier for the protruding piece portion to be inserted into the gap, thereby making it possible to better maintain the connection state of the folded first panel and second panel.

[0013] In addition, in the blank of the present invention, the locking structure portion extends from the slit in the second direction and further has a cross slit that crosses the slit, and the cross slit may have a portion extending toward the bottom panel in the first direction.

[0014] In addition, in the blank of the present invention, the locking structure portion extends from the slit in the second direction and further has a cross slit that intersects with the slit, and the cross slit may have a portion extending on the opposite side to the bottom plate in the first direction.

[0015] In addition, in the blank of the present invention, the locking structure portion extends from the slit in the second direction and further has a cross slit that crosses the slit, and the cross slit may have both a portion extending toward the bottom plate in the first direction and a portion extending opposite the bottom plate in the first direction. Furthermore, in the above configuration, it is more preferable that, at the intersecting slit, the portion extending from the slit towards the bottom plate and the portion extending from the slit to the opposite side from the bottom plate are continuous in a straight line.

[0016] Furthermore, in the blank of the present invention, when the second panel is folded along a fold line formed in the second direction, a cut may be provided on the fold line.

[0017] In the blank of the present invention, the second panel may have an outer edge portion located on the opposite side to the bottom panel in the first direction, the outer edge portion having a notch formed along the first direction.

[0018] In the blank of the present invention, the second panel may have an end fold line formed along the first direction at an end portion thereof located on the opposite side to the bottom panel in the first direction.

[0019] In the blank of the present invention, the slit portion may have a first extending portion extending along the first direction and a second extending portion extending intersecting the first extending portion, and in the second direction, an end of the second extending portion opposite the protruding piece may be farther away from the protruding piece than an end of the first extending portion opposite the second extending portion. In this case, the slit may extend along the second direction from the second extending portion or an intersection of the first extending portion and the second extending portion.

[0020] In the blank of the present invention, a break line may be formed on the protruding piece portion to break the protruding piece portion. In the above configuration, the break line may be formed on a bending curve provided at the base end of the projecting piece and may be a cut line extending along the second direction.

[0021] In the blank of the present invention, the slit portion may have a first extending portion extending along the first direction and a second extending portion extending intersecting the first extending portion and including an inclined portion inclined with respect to the first direction. In this case, the second panel may be provided with an opening fold line which is a fold line for folding a portion of the second panel opposite the first extending portion and adjacent to the second extending portion when opening the slit portion. The opening fold line may extend from a position on the second panel farther from the bottom panel than the inclined portion toward the inclined portion. In the above configuration, the opening fold line may extend along the first direction toward a location of the second extending portion that is closer to a center of the inclined portion than to both ends of the inclined portion. Furthermore, in the above configuration, the second panel may include a side panel that forms a side portion of the box body and is connected to the bottom panel in the first direction, and the first and second extending portions of the slit portion and the opening fold line may be provided on the side panel. Effect of the Invention

[0022] According to the present invention, it is possible to provide a blank that can satisfactorily maintain (lock) the connection structure of the first panel and the second panel that are bent relative to the bottom panel. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a diagram showing a blank (left diagram) according to one embodiment of the present invention, and a box (right diagram) that is assembled by folding the blank. [Diagram 2] FIG. 2 is a plan view of a blank according to one embodiment of the present invention. [Diagram 3] FIG. [Figure 4] 13 is a diagram showing a state immediately before the protruding piece is inserted into the gap. FIG. [Diagram 5] 13 is a diagram showing a state in which the protruding piece portion is inserted into the gap portion. FIG. [Figure 6] 13 is a diagram showing a state in which the first panel is tilted relative to the second panel with the protruding piece portion inserted into the gap portion. FIG. [Figure 7] 7 is an enlarged view of the vicinity of the protruding piece in FIG. 6. FIG. [Figure 8] FIG. 8 is a diagram showing a cross section II of FIG. [Figure 9] FIG. 13 is a diagram showing a modified example of an intersecting cut. [Figure 10] FIG. 13 is a diagram showing a lock structure according to a first modified example. [Figure 11] FIG. 13 is a diagram showing a lock structure according to a third modified example. [Figure 12] FIG. 13 is a diagram showing a lock structure according to a fourth modified example. [Figure 13] FIG. 13 is a diagram showing a lock structure according to a fifth modified example. [Figure 14] FIG. 13 is a diagram showing a configuration of a blank according to a sixth modified example. [Figure 15] FIG. 13 is a diagram showing a configuration of a blank according to a seventh modified example. [Figure 16] FIG. 13 is a diagram showing a configuration of a blank according to an eighth modified example. [Figure 17] FIG. 13 is a diagram showing a configuration of a blank according to a ninth modified example. [Figure 18] FIG. 13 is a diagram showing a configuration of a blank according to a first reference example having the characteristics of a ninth modified example. [Figure 19]FIG. 11 is a diagram showing variations of blanks according to the eighth and ninth modified examples (part 1). [Figure 20] FIG. 13 is a diagram showing variations of blanks according to the eighth and ninth modified examples (part 2). [Figure 21] FIG. 13 is a diagram showing variations of blanks according to the eighth and ninth modified examples (part 3). [Figure 22] FIG. 20 is a diagram showing a configuration of a blank according to a second reference example having the features of the eighth and ninth modified examples, and corresponds to FIG. 19. [Figure 23] FIG. 21 is a diagram showing a configuration of a blank according to a third reference example having the features of the eighth and ninth modified examples, and corresponds to FIG. 20. [Figure 24] FIG. 24 is a diagram showing the configuration of a blank according to a third reference example having the features of the eighth and ninth modified examples, which is a modification of the configuration shown in FIG. [Diagram 25] FIG. 22 is a diagram showing the configuration of a blank according to a fourth reference example having the features of the eighth and ninth modified examples, and corresponds to FIG. 21. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The blank of the present invention will be described below with reference to specific embodiments. It should be noted that the embodiments described below are merely examples given to facilitate understanding of the present invention, and are not intended to limit the present invention. In other words, the present invention may be modified or improved from the embodiments described below without departing from the spirit of the present invention. Furthermore, the present invention includes equivalents thereof.

[0025] In addition, in this specification, the meanings of "same," "identical," and "equal" may include a generally acceptable range of error in the technical field to which the present invention belongs.

[0026] In this specification, "orthogonal," "vertical," and "parallel" include the range of error permitted in the technical field to which the present invention pertains. For example, "orthogonal," "vertical," and "parallel" in this specification mean that the difference is within a range of less than ±10° from the strict orthogonal, vertical, or parallel. The error from strictly orthogonal (perpendicular) or strictly parallel is preferably 5° or less, and more preferably 3° or less.

[0027] [Overall blank configuration] A blank 10 according to one embodiment of the present invention (hereinafter referred to as this embodiment) is a sheet-like or plate-like member for forming a box such as a packaging box. When unfolded, the blank 10 has a substantially T-shape as shown in the left diagram of Fig. 1, and when each portion of the blank is folded, a box 1 is formed as shown in the right diagram of Fig. 1. In other words, by folding one blank 10, a box 1 having a bottom portion, side portions, and a top portion is assembled.

[0028] The blank 10 is made of a paper material such as cardboard or thick paper. The paper material is not particularly limited, and a paper material that has been coated to improve the paper quality may be used. The blank 10 may also be a sheet or plate made of a material other than paper, such as a resin material or metal. In the following, the paper material constituting the blank 10 is a cardboard sheet, more specifically, a cardboard structure in which a medium is sandwiched between two liners on the front and back will be described as an example.

[0029] The blank 10 of this embodiment is folded to form an N-type box 1, as shown in Fig. 1. The top plate portion of the N-type box 1 is configured by overlapping an outer flap portion on the outer side of an inner flap portion. The blank of the present invention is not limited to one for forming an N-type box body, and may be one for forming, for example, a tatoo-type box body, an A-type box body, a B-type box body, or a C-type box body. The N-type box body formed by folding the blank may be of an insert type (more specifically, a top insert type or a side insert type) or a frame type.

[0030] 2, fold lines that serve as bending starting points when forming the box body 1 are formed at various locations on the blank 10, specifically, the protruding piece fold line 22, the first fold line 24, the second fold line 26, the first top panel fold line 38, the front fold line 42, and the insertion piece fold line 46. These fold lines only need to have lower rigidity than the surrounding areas, and may be, for example, perforations or groove-like recesses formed by embossing or the like.

[0031] The core of the cardboard sheet constituting the blank 10 has a corrugated shape, and the direction in which the waves continue (the direction of the stripes drawn inside the dashed circle in FIG. 2) corresponds to the grain direction of the cardboard sheet. The grain direction of the cardboard sheet is not particularly limited, but may cross each of the X and Y directions described below, or may be inclined at 45 degrees to each direction, for example. In this case, the foldability of the blank 10 can be improved.

[0032] As shown in Fig. 2, the blank 10 has a bottom panel 12, a plurality of first panels 14, and a plurality of second panels 16 as main components of the blank 10. As shown in Fig. 2, the bottom panel 12 is a polygonal portion provided on the blank 10, and forms the bottom surface of the box body 1 when the box body 1 is formed. As shown in Fig. 2, the bottom panel 12 of this embodiment is rectangular and has four vertices, a pair of long sides, and a pair of short sides. The long sides and short sides extending from each vertex of the bottom panel 12 correspond to two adjacent sides sandwiching the vertex, with one of the two sides corresponding to one side and the other corresponding to the other side. The shape of the bottom plate 12 is not limited to a rectangle, but may be a quadrangle other than a rectangle, including a square, a trapezoid, or a parallelogram, or a polygon other than a square.

[0033] Hereinafter, the direction in which the long sides of the four sides of the rectangle that defines the outline of the bottom panel 12 extend will be referred to as the X direction, and the direction in which the short sides extend will be referred to as the Y direction. Here, the X direction corresponds to the first direction of the present invention, and the Y direction corresponds to the second direction of the present invention. However, this is not limited thereto, and the above-mentioned short side direction may be the X direction (first direction), and the above-mentioned long side direction may be the Y direction (second direction). In the following, in the X and Y directions, the side closer to the center of the blank 10 (specifically, the center of the bottom panel 12) will be referred to as the "inner side," and the opposite side, i.e., the side away from the center of the blank 10, will be referred to as the "outer side."

[0034] The first panel 14 is continuous with the bottom panel 12 in the blank 10, and is a portion extending in the Y direction from the long side of the bottom panel 12, with one on each side of the bottom panel 12 in the Y direction as shown in Fig. 2. A first fold line 24 is formed along the X direction between each first panel 14 and the bottom panel 12, more precisely at the boundary position of the double-sided panels.

[0035] The first fold lines 24 are formed on each long side of the bottom panel 12, more specifically, from a vertex corresponding to one end of each long side of the bottom panel 12 to a vertex corresponding to the other end, and in this embodiment, form a straight line parallel to the X direction. Each first panel 14 is configured to be bendable at the first fold lines 24, and when the box 1 is formed, it is folded perpendicular to the bottom panel 12 at the first fold lines 24.

[0036] Each of the two first panel plates 14 has a substantially rectangular first side panel 34, as shown in Fig. 2. The first side panel 34 is connected to the bottom panel 12 in the Y direction, and forms a side surface of the box body 1 when the blank 10 is folded to form the box body 1. One of the two first panel plates 14 (hereinafter, one first panel 14a) has a first top panel 36 on the outer side of the first side panel 34 in the Y direction, as shown in Fig. 2.

[0037] The first top plate 36 is a rectangular portion having substantially the same shape and size as the bottom plate 12. A first top plate fold line 38 is provided between the first top plate 36 and the first side plate 34, and the first top plate fold line 38 is formed linearly along the X direction and extends parallel to the first fold line 24. The first top plate 36 is connected to the first side plate 34 via the first top plate fold line 38, and can be folded along the first top plate fold line 38. The first top plate 36 forms a top plate portion (outer flap portion) of the box body 1 at the stage when the blank 10 is folded and the box body 1 is assembled.

[0038] 2, one of the first panel 14a has a front panel 40 on the outer side of the first top panel 36 in the Y direction (opposite the first side panel 34). The front panel 40 is a substantially rectangular portion with two corners located on the outer side in the Y direction chamfered, and has a length (dimension in the X direction) slightly shorter than the first top panel 36 and substantially the same width (dimension in the Y direction) as the first side panel 34.

[0039] A front fold line 42 is provided between the front panel 40 and the first top panel 36, and the front fold line 42 is formed linearly along the X direction and extends parallel to the first fold line 24. The front panel 40 is connected to the first top panel 36 on the opposite side to the first side panel 34 via the front fold line 42, and can be folded along the front fold line 42. When the blank 10 is folded to form the box body 1, the front panel 40 forms a front portion of the box body 1, more specifically, a lid portion that covers the side portion on the front side of the box body 1.

[0040] 2, one of the first panel 14a has an insertion piece 44 on the outside of the front panel 40 in the Y direction. The insertion piece 44 protrudes from the center in the X direction of the outer edge located at the outer end of the front panel 40 in the Y direction. The insertion piece 44 has a narrow base, and the width of the insertion piece 44 is wider at the portion adjacent to the base than at the base, and the width gradually narrows toward the tip, forming a generally trapezoidal shape. The insertion piece 44 can be folded along an insertion piece fold line 46 formed at the boundary between the insertion piece 44 and the front panel 40.

[0041] 2, an insertion line 48, which is a cutout for inserting the insertion piece 44, is provided on the other of the two first panel 14 (hereinafter, the other first panel 14b). Two first fold lines 24 are provided at an interval in the X direction at the boundary between the other first panel 14b and the bottom panel 12, and the insertion line 48 is located between the two first fold lines 24 in the X direction and at approximately the same position as the first fold lines 24 in the Y direction.

[0042] Then, when the other first panel 14b is folded along the first fold line 24, an insertion hole is formed in a corner portion between the other first panel 14b and the bottom panel 12, adjacent to the insertion line 48. The insertion piece 44 is inserted into this insertion hole when the blank 10 is folded to assemble the box body 1. This forms the box body 1 with the upper opening closed by the first top panel 36 (outer flap).

[0043] The second panel 16 is continuous with the bottom panel 12 in the blank 10 and is a portion extending in the X direction from the short side of the bottom panel 12, and is provided on each side of the bottom panel 12 in the X direction, as shown in Fig. 2. A second fold line 26 formed along the Y direction is provided between each second panel 16 and the bottom panel 12, more specifically, on each short side of the bottom panel 12. The second fold line 26 is formed from a vertex corresponding to one end of each short side of the bottom panel 12 to a vertex corresponding to the other end, and in this embodiment, forms a straight line parallel to the Y direction.

[0044] Each second panel 16 is configured to be bendable relative to the bottom panel 12 at the second fold line 26, and when assembling the box 1, the second panel 16 is bent perpendicularly to the bottom panel 12 at the second fold line 26. When the second fold line 26 is perpendicular to the grain direction of the cardboard sheets constituting the blank 10, the repulsive force against bending at the protruding piece fold line 22 in the second panel 16 becomes strong. In that case, when the second panel 16 is folded inward at the second fold line 26, an outward repulsive force is generated starting from the second fold line 26. This makes it easier for the slit portion 28 and the cut 62 described later to open and form the gap portion 60, and as a result, it becomes easier to insert the protruding piece portion 20 described later into the gap portion 60. Here, "inner" means the inside of box body 1 (i.e., the side facing the storage space of box body 1) when blank 10 is folded to complete box body 1, and "outer" means the outside of box body 1 (i.e., the side opposite the storage space of box body 1).

[0045] As shown in FIG. 2, each of the two second panel 16 has a substantially rectangular second side panel 50 and a substantially trapezoidal second top panel 52 located outside the second side panel 50 in the X direction.

[0046] The second side plate 50 is connected to the bottom plate 12 in the X direction, and when the blank 10 is folded to assemble the box 1, it forms a side surface of the box 1, more specifically, a side surface adjacent to the side surface formed by the first side plate 34. The above-mentioned second fold line 26 is provided at the boundary between the second side plate 50 and the bottom plate 12. The end portion (bottom portion) of the second side plate 50 on the bottom plate 12 side in the X direction has a shape in which the width (dimension in the Y direction) gradually narrows as it moves outward in the X direction.

[0047] As shown in FIG. 2, the second top plate 52 has a shape in which the width (dimension in the Y direction) gradually narrows toward the outside in the X direction. The width of the second top plate 52 changes more gradually than the width change at the bottom of the second side plate 50. In addition, a second top plate fold line 54, which is a fold line formed linearly along the Y direction, is provided between the second top plate 52 and the second side plate 50. The second top plate 52 is configured to be bendable along the second top plate fold line 54, and when the blank 10 is folded and the box body 1 is assembled, the second top plate 52 overlaps with the first top plate 36 below the first top plate 36 in the box body 1 to form a top plate portion (inner flap portion) of the box body 1.

[0048] 2, a V-shaped cutout 56 is provided on the outer end in the X direction of the second top plate 52, i.e., on the outer edge in the X direction, at a portion located slightly closer to the center than the end in the Y direction. In this embodiment, two cutouts 56 are provided on the outer edge of each second top plate 52 at positions spaced apart from each other in the Y direction.

[0049] Furthermore, as shown in Fig. 2, an end fold line 58 is provided along the X direction at the end on the outer side in the X direction of the second top plate 52. In each second top plate 52, the end fold line 58 is provided at a portion located slightly closer to the center than the end in the Y direction, and more specifically, is formed at approximately the same position as the innermost portion (bottom portion) of the cutout portion 56 in the Y direction. In addition, in each second top plate 52, two end fold lines 58 are provided at positions separated from each other in the Y direction in correspondence with the two cutout portions 56. Each end fold line 58 is provided in the X direction between the bottom portion of the cutout portion 56 and a second extending portion end portion 32a of the slit portion 28 described later (see Fig. 3).

[0050] 2, the blank 10 has a locking structure 18 at each of the four vertices of the rectangular bottom panel 12. When the blank 10 is folded to form the box 1, the locking structure 18 maintains a connected state between the first panel 14 and the second panel 16 that are adjacent to each other across the vertex of the bottom panel 12. In other words, the first panel 14 folded along the first fold line 24 and the second panel 16 folded along the second fold line 26 are both held in a connected state by the locking structure 18 provided at the vertex located between them.

[0051] 1 and 2, in this embodiment, one locking structure 18 is provided for each of the four vertices of the bottom panel 12. In other words, the blank 10 has four locking structures 18. However, this is not limited thereto, and it is sufficient that a locking structure 18 is provided for at least one of the four vertices, and the locking structure 18 may be provided for any one, any two, or any three of the four vertices.

[0052] When two lock structures 18 are provided, it is preferable that the lock structures 18 are provided at two vertices diagonally opposite each other. When the bottom panel 12 has a rectangular or square shape with four vertices, it is most preferable that a lock structure 18 is provided at each of the four vertices. In this case, when both the first panel 14 and the second panel 16 are folded so as to stand up relative to the bottom panel 12, the lock structures 18 provided at each of the four vertices simultaneously form a connection structure between the first panel 14 and the second panel 16 at all four vertices of the bottom panel 12.

[0053] As shown in Fig. 3, each lock structure 18 has a protruding piece 20 that protrudes outward in the X direction from an end position of the first panel 14 in the X direction, and a slit portion 28 formed at the Y direction end portion of the second panel 16. Also, as shown in Fig. 3, the lock structure 18 has a slit 62 that extends outward in the Y direction from the slit portion 28 (toward the side where the nearest protruding piece 20 is located), and an intersecting slit 64 that intersects with the slit 62.

[0054] In the locking structures 18, when the blank 10 is folded to form the box 1, the slits 28 and the cuts 62 open to form gaps 60 into which the protruding pieces 20 are inserted (see FIGS. 4 and 5). This allows each locking structure 18 to maintain the connection between the first panel 14 and the second panel 16.

[0055] The protruding piece 20 is a portion that protrudes along the X direction from an end of the first side plate 34 of the first panel 14 on the second panel 16 side, i.e., an end (side end) of the first panel 14 in the X direction. As shown in FIG. 3, the protruding piece 20 is adjacent to the second panel 16 in the Y direction, and a slight gap is provided between the protruding piece 20 and the second panel 16. Also, as shown in FIG. 3, a protruding piece fold line 22 formed along the Y direction is provided at the boundary position between the protruding piece 20 and the first side plate 34, i.e., the base end position of the protruding piece 20. The protruding piece fold line 22 forms a straight line parallel to the Y direction, and is provided slightly outside the second fold line 26 in the X direction.

[0056] The protruding piece 20 is configured to be bendable relative to the first side panel 34 of the first panel 14 at the protruding piece fold line 22. Here, when the protruding piece fold line 22 is perpendicular to the grain direction of the cardboard sheets constituting the blank 10, the repulsive force against bending at the protruding piece fold line 22 becomes strong. This improves the holding force of the locking structure 18 when the protruding piece 20 is inserted into the gap 60, and the connected state between the first panel 14 and the second panel 16 is more appropriately held (locked).

[0057] As shown in Fig. 3, the protruding piece 20 of this embodiment has a protruding piece base 20a and a protruding piece tip 20b. The protruding piece base 20a is connected to the first side plate 34 via a protruding piece fold line 22, and has the same length (width) as the first side plate 34 in the Y direction. The protruding piece tip 20b is continuous with the protruding piece base 20a on the outside of the protruding piece base 20a in the X direction, and both ends in the Y direction are cut to be narrower and thinner than the protruding piece base 20a, forming a substantially pentagonal shape. When the protruding piece 20 is inserted into the gap 60, the protruding piece tip 20b is inserted into the gap 60.

[0058] 3, a protruding piece notch 20c is provided at the end of the protruding piece tip 20b opposite the second panel 16. The protruding piece notch 20c is formed long in the X direction, and the cut amount of the protruding piece notch 20c is larger at the center in the X direction than at both end portions in the X direction. Therefore, the protruding piece notch 20c has a pointed shape toward the second panel 16 in the Y direction.

[0059] By providing the protruding piece cutout 20c on the protruding piece 20, when the protruding piece tip 20b is inserted into the gap 60 and the first panel 14 tries to return to the state before folding due to a reaction force, the protruding piece cutout 20c engages with the upper side portion of the outer edge of the gap 60. As a result, the upper end opening of the box body 1, which is still open during assembly, can be widened, improving the ease of stacking the box body 1. In other words, when the first panel 14 is tilted so as to fall outward relative to the bottom panel 12, the protruding piece tip 20b inserted into the gap 60 is engaged with the edge of the gap 60, so that the tilted state of the first panel 14 can be maintained, improving the stackability of the box body 1 in the temporary assembly stage.

[0060] Furthermore, when the top opening of the box 1 is closed by the first top plate 36 and the second top plate 52, the protruding piece tip 20b inserted into the gap 60 is locked to the edge of the gap 60, so that the protruding piece 20 is securely locked by the first top plate 36 and the second top plate 52. This allows the locking structure 18 to securely maintain (lock) the connected state between the first panel 14 and the second panel 16. At this time, the action of the protruding piece notch 20c described above maintains the protruding piece 20 inserted into the gap 60 in both the open and closed states of the top opening of the box 1, and prevents the protruding piece 20 from coming off the gap 60.

[0061] 3, the corners of the outer edge of the protruding piece tip 20b on the second panel 16 side in the Y direction are chamfered. Also, as shown in Fig. 3, the end of the protruding piece tip 20b on the second panel 16 side in the Y direction is provided with a protruding piece recess 20d consisting of a substantially triangular recess. Of the two sides forming the outer edge of the protruding piece recess 20d, the side located on the base end side of the protruding piece 20 runs along the Y direction, and the other side is inclined with respect to the Y direction.

[0062] Furthermore, by providing the protruding piece recess 20d in the protruding piece 20, when the protruding piece 20 is inserted into the gap 60, a portion of the protruding piece 20 adjacent to the protruding piece recess 20d contacts and engages with a portion of the edge of the gap 60 adjacent to the end portion of the slit portion 28 (more specifically, the end portion 30a of the first extending portion). This makes it possible to more reliably maintain (lock) the state in which the protruding piece 20 is inserted into the gap 60. Incidentally, by providing a protruding piece recess 20d, the protruding piece tip 20b may be prevented from contacting the edge of the gap 60 when the protruding piece 20 is inserted into the gap 60.

[0063] 3, the slit portion 28 is made of a cut line bent at an obtuse angle, and is provided in a portion of the second panel 16 that is located more inward in the Y direction than the end adjacent to the protruding piece portion 20. As shown in FIG. 3, the slit portion 28 has a first extending portion 30 extending along the X direction, and a second extending portion 32 extending from one end of the first extending portion 30 in a direction intersecting with the first extending portion 30.

[0064] The first extending portion 30 extends linearly toward the bottom panel 12 in a direction slightly inclined with respect to the X direction, and is displaced inward in the Y direction as it approaches the bottom panel 12. As shown in FIG. 3, the outer end (one end) of the first extending portion 30 in the X direction is at the same position as the second top panel fold line 54 in the X direction. Of the first extending portion 30, the end portion (hereinafter, the first extending portion end portion 30a) located on the inner side in the X direction is curved in an arc shape or semicircle shape as shown in FIG. 3, and is located slightly outside the second fold line 26 in the X direction. In other words, there is a gap between the first extending portion end portion 30a and the second fold line 26 in the X direction.

[0065] The end position and shape of the first extending portion 30 are not particularly limited, and the first extending portion 30 may extend beyond the second top fold line 54 in the X direction, with one end of the first extending portion 30 located outside the second top fold line 54. Conversely, one end of the first extending portion 30 may be located inside the second top fold line 54 in the X direction. The first extending portion 30 may also extend until the end on the inner side in the X direction is located on (reaches) the second fold line 26.

[0066] The second extending portion 32 extends inward in the Y direction from one end of the first extending portion 30 in a direction inclined with respect to the Y direction, and is displaced outward in the X direction as it extends inward in the Y direction. The inclination angle (acute angle) between the extending direction of the second extending portion 32 and the Y direction is not particularly limited, but may be within a range of 30° to 60°. In addition, one end of the second extending portion 32 (the end on the first extending portion 30 side) coincides with one end of the first extending portion 30 as shown in FIG. 3, and therefore exists on the second top panel folding line 54.

[0067] The second extending portion 32 extends in the Y direction to approximately the same position as the notch 56 and the end fold line 58 provided on the second panel 16, and further, the end portion of the second extending portion 32 located more inward in the Y direction (hereinafter, the second extending portion end 32a) is curved in an arc or semicircle. As shown in Fig. 3, the second extending portion end 32a is located more inward in the Y direction than the first extending portion end 30a, in other words, it is farther from the protruding piece 20 than the first extending portion end 30a.

[0068] The end position and shape of the second extending portion 32 are not particularly limited, and one end of the second extending portion 32, i.e., the end on the first extending portion 30 side, may be located outside the second top panel fold line 54 in the X direction, or may be located inside the second top panel fold line 54. In addition, the second extending portion end portion 32a may be located outside or inside the cutout portion 56 and the end fold line 58 in the Y direction.

[0069] The slit 62 is a cut line, and in this embodiment, extends linearly from the bending point of the slit portion 28, that is, the intersection of the ends of the first extending portion 30 and the second extending portion 32. The slit 62 is located outside the slit portion 28 in the Y direction and extends parallel to the Y direction, and in this embodiment, is provided at a position overlapping with the second top panel folding line 54 as shown in Fig. 3. The length of the slit 62 (extension in the Y direction) is relatively short and smaller than the extension of the second extending portion 32 in the Y direction, and is, for example, about 1 to 5 mm.

[0070] The slit 62 may extend in a direction inclined with respect to the Y direction as long as it is located outside the slit portion 28 in the Y direction. The slit 62 may be provided at a position that does not overlap with the second top folding line 54, for example, inside the second top folding line 54 in the X direction, in other words, may extend from the first extending portion 30 of the slit portion 28. Alternatively, the slit 62 may be provided outside the second top folding line 54 in the X direction, in other words, may extend from the second extending portion 32 of the slit portion 28.

[0071] The intersecting slit 64 is made of a cut line and extends from the outer end (tip) of the slit 62 in the Y direction in a direction intersecting the slit 62, as shown in Fig. 3. In this embodiment, the intersecting slit 64 has an outer portion 64a extending outward in the X direction (i.e., the side opposite the bottom plate 12) and an inner portion 64b extending inward in the X direction (i.e., toward the bottom plate 12), as shown in Fig. 3. The length (extension in the X direction) of each of the outer portion 64a and the inner portion 64b is smaller than the extension of the first extending portion 30 in the X direction, and is, for example, about 1 to 5 mm.

[0072] Both the outer portion 64a and the inner portion 64b extend parallel to the X direction and are perpendicular to the slit 62. In addition, the outer portion 64a and the inner portion 64b are continuous in a straight line in the cross slit 64. With this configuration, the cross slit 64 having the outer portion 64a and the inner portion 64b can be easily provided in the second panel 16. However, this is not limited thereto, and at least one of the outer portion 64a and the inner portion 64b may extend in a direction intersecting with the other. For example, both the outer portion 64a and the inner portion 64b may extend in a direction intersecting with each other to form a cross slit 64 having a cross lateral V-shape. In addition, only one of the outer portion 64a and the inner portion 64b may be provided in the cross slit 64, and the other may not be provided.

[0073] According to the lock structure 18 configured as above, the tip of the protruding piece 20 (protruding piece tip 20b) is inserted into the gap 60 formed by the opening of the slit 28 and the cut 62, as shown in Figures 4 and 5. This maintains the connection state of the first panel 14 and the second panel 16 bent relative to the bottom panel 12. In addition, "the slit portion 28 and the cut 62 open" means that of the two portions of the second panel 16 adjacent to each other via the slit portion 28 and the cut 62, the portion located more inward in the Y direction than the slit portion 28 is pressed toward the outside of the box body 1 (strictly speaking, the box body 1 in the middle of assembly), thereby forming a gap between the two portions.

[0074] More specifically, when the second panel 16 is bent at the second fold line 26 and the first panel 14 is bent at the first fold line 24, the protruding piece 20 rotates around the first fold line 24 toward the second panel 16 as shown in FIG. 4. This causes the protruding piece 20 to turn around the outside of the second side panel 50 of the second panel 16. Then, the part of the second panel 16 located inside the slit portion 28 in the Y direction is pressed toward the outside of the box 1, so that the slit portion 28 and the gap portion 60 are opened as shown in FIG. 4, and the protruding piece tip portion 20b is inserted into the gap portion 60 and enters the inside of the second panel 16 from the outside of the second panel 16 through the gap portion 60. This causes the protruding piece tip portion 20b to be completely inserted into the inside of the second panel 16 through the gap portion 60 as shown in FIG. 5.

[0075] As a result of the above, a connecting structure between the first panel 14 and the second panel 16 is formed on the outside of the second panel 16, or more precisely, on the outside of the second side panel 50, at the locations where each of the four vertices of the bottom panel 12 is located. Furthermore, when the protruding piece portion 20 is inserted into the gap portion 60, a portion of the second panel 16 adjacent to the slit portion 28 (more specifically, the first extending portion 30) on the inside of the slit portion 28 in the Y direction constitutes a second panel pressing portion 66. Note that the side opposite the second panel pressing portion 66, i.e., the portion adjacent to the slit portion 28 on the outside in the Y direction, will be referred to as the adjacent portion 68 hereinafter.

[0076] A force acts on the second panel pressing portion 66 to return to its original state due to the rigidity of the paper material (more specifically, the cardboard sheet) that constitutes the blank 10. The second panel pressing portion 66 utilizes this restoring force to press the protruding piece 20 inserted into the gap 60 from the outside to the inside of the protruding piece 20. As a result, the state in which the protruding piece 20 is inserted into the gap 60, that is, the connected state of the folded first panel 14 and second panel 16, is securely maintained (locked).

[0077] In this embodiment, the slit portion 28 is bent, in other words, the slit portion 28 is formed by the first extending portion 30 and the second extending portion 32 which intersect with each other. As a result, when the protruding piece portion 20 is inserted into the gap portion 60 formed by the opening of the slit portion 28, contact between the edge of the gap portion 60 and the protruding piece portion 20 is minimized, and the protruding piece portion 20 can be inserted into the gap portion 60 more smoothly. In particular, in the present embodiment, in the Y direction, the second extending portion end portion 32a, which is the end of the second extending portion 32 opposite the protruding piece portion 20, is farther away from the protruding piece portion 20 than the first extending portion end portion 30a, which is the end of the first extending portion 30 opposite the protruding piece portion 20. This allows the slit portion 28 to be opened more widely, and the protruding piece portion 20 can be inserted into the gap portion 60 more smoothly.

[0078] In this embodiment, the first extending portion end 30a is located outside the second folding line 26 in the X direction. In other words, a gap is provided between the first extending portion end 30a and the second folding line 26 in the X direction. As a result, when the protruding piece 20 is inserted into the gap 60, the protruding piece tip 20b is engaged with a portion of the edge of the gap 60 adjacent to the outer end of the first extending portion 30 in the X direction, including the first extending portion end 30a. This prevents the protruding piece 20 from rotating upward with respect to the bottom plate 12 (i.e., falling down), and the first panel 14 and the second panel 16 can be well maintained in a state in which they stand upright perpendicularly to the bottom plate 12. As a result, the size of the storage space in the box 1 assembled by folding the blank 10 is appropriately maintained.

[0079] In this embodiment, the second fold line 26 is provided between the vertices located at both ends of each short side of the bottom panel 12, and forms a straight line parallel to the Y direction. With this configuration, the protruding piece portion 20 can be inserted into the gap portion 60 starting from the vertices of the bottom panel 12. This makes it possible to minimize the gap between the protruding piece base portion 20a and the second panel 16 when the protruding piece portion 20 is inserted into the gap portion 60. The protruding piece tip portion 20b is inserted into the gap portion 60 while being pressed by a portion of the second panel 16 adjacent to the slit portion 28, i.e., the second panel pressing portion 66.

[0080] To explain in more detail, when the protruding piece 20 is inserted into the gap 60, the adjacent portion 68 presses the protruding piece base portion 20a outwardly of the box body 1 (strictly speaking, the box body 1 in the middle of assembly), and the second panel pressing portion 66 presses the protruding piece tip portion 20b inwardly of the box body 1. As a result, the protruding piece 20 inserted into the gap 60 is sandwiched between two adjacent portions of the second panel 16 via the slit portion 28, so that the protruding piece 20 and the second panel 16 abut against each other without any gaps, and as a result, the locking force for the protruding piece 20 inserted into the gap 60 can be improved.

[0081] In this embodiment, the protruding piece fold line 22 is offset outward from the second fold line 26 in the X direction. Therefore, when the protruding piece 20 is inserted into the gap 60, the protruding piece 20 moves outward from the second panel 16 standing upright relative to the bottom panel 12 by the plate thickness of the second panel 16. This allows the protruding piece 20 to be smoothly inserted into the gap 60 while avoiding interference with the second panel 16.

[0082] In this embodiment, the slit 62 extends from the slit 28 outward in the Y direction, so that the protruding piece 20 can be inserted more smoothly into the gap 60, and the protruding piece 20 can be more reliably held (locked) in the state inserted into the gap 60. Specifically, the portion of the second panel 16 adjacent to the slit 28 on the inside of the slit 28 in the Y direction is displaced toward the outside of the box 1, so that the slit 28 opens. At this time, the portion of the second panel 16 adjacent to the slit 28 (more specifically, the adjacent portion 68) is more likely to displace toward the inside of the box 1 from the Y direction end of the slit 62 by the amount of the slit 62, so that the slit 28 opens more easily. As a result, the gap 60 widens, and the protruding piece 20 can be more easily inserted into the gap 60.

[0083] In this embodiment, as shown in FIG. 3, the second top plate 52 of the second panel 16 is provided with an end fold line 58, which makes it easier to open the slit portion 28 and the cut 62. To explain in detail, the pressing force from the pressing tool (not shown) and the force when bending the second panel 16 at the second fold line 26 act on the portion of the second panel 16 adjacent to the slit portion 28, and the portion is pressed outward, thereby opening the slit portion 28. Furthermore, at this time, the above-mentioned force is applied to the end fold line 58, and the portion of the second panel 16 adjacent to the slit portion 28 on the outer side in the Y direction, i.e., the adjacent portion 68, is bent inward at the end fold line 58. As a result, the slit portion 28 can be opened wider, and a larger gap portion 60 is formed. Furthermore, the cut 62 is provided, so that the gap portion 60 is further widened.

[0084] Furthermore, in this embodiment, by providing a V-shaped cutout portion 56 on the outer edge portion of the second top panel 52, stress is concentrated at the cutout portion 56, and the second panel 16 can be folded at the end fold line 58 more easily. To explain in more detail, when the protruding piece portion 20 is inserted into the gap portion 60, the second panel pressing portion 66 is pressed in the second panel 16, and the pressing force and the force for bending the second panel 16 from the second fold line 26 are applied to the end fold line 58 via the cutout portion 56. As a result, the slit portion 28 and the slit 62 are opened further widely, and the gap portion 60 can be widened further, so that the protruding piece portion 20 can be inserted into the gap portion 60 even more easily.

[0085] In order to insert the protruding piece 20 into the gap 60, it is necessary to appropriately design the dimensions of the protruding piece 20, the positional relationship between the protruding piece 20 and the slit portion 28, and the length of the slit portion 28 in the X direction and the Y direction. Here, as shown in FIG. 3, the length (width) of the protruding piece tip 20b in the Y direction is A, and the length (protruding amount) of the protruding piece 20 in the X direction is B. Also, the distance from the second fold line 26 to the outer end of the second extension portion 32 of the slit portion 28 in the X direction is C, and the distance from the first fold line 24 to the inner end of the second extension portion 32 in the Y direction is D. In this case, in this embodiment, the lock structure 18 is configured to satisfy the following formulas (1) and (2). C≧A formula (1) D≧B Formula (2)

[0086] By satisfying the above formulas (1) and (2), the connection state of the folded first panel 14 and second panel 16 is stably maintained (locked). To explain in more detail, when the first panel 14 and second panel 16 are folded using a pressing tool (not shown), the pressing force acting on each of the first panel 14 and second panel 16 that stand vertically relative to the bottom panel 12, i.e., the force that makes them stand vertically, disappears when the pressing tool moves away from the first panel 14 and second panel 16. As a result, each of the first panel 14 and second panel 16 tends to fall slightly outward due to the reaction force generated by the folding, as shown in FIG. 6.

[0087] On the other hand, in this embodiment, the width A of the protruding piece tip 20b is smaller than the distance C from the second fold line 26 to the outer end in the X direction of the second extending portion 32 of the slit portion 28. In this case, when the first panel 14 falls outward, the protruding piece 20 inserted into the gap 60 rotates so that its tip is slightly raised, as shown in Fig. 6. As a result, the protruding piece tip 20b is engaged with the upper end portion of the edge of the gap 60, and it is possible to prevent the protruding piece 20 from detaching from the gap 60.

[0088] In this embodiment, since the second panel 16 is provided with the slit 62, when the protruding piece 20 rotates as described above, the portion of the second panel 16 immediately above the slit 62 and adjacent to the slit 62 (hereinafter referred to as the edge portion of the slit) locks the protruding piece tip 20b. To explain in more detail, as shown in Figs. 7 and 8, the protruding piece tip 20b abuts against the edge portion of the slit in a state where it crosses the edge portion of the slit in an X-shape when viewed from the height direction of the box body 1. This keeps the protruding piece 20 at the position where the protruding piece tip 20b abuts against the edge portion of the slit, and further rotation of the protruding piece 20 can be suppressed. As a result, it is possible to more effectively suppress the protruding piece 20 from coming off the gap portion 60.

[0089] The above-mentioned effect is particularly effective when the thickness of the blank 10 is increased. That is, the thicker the paper material constituting the blank 10, the stronger the repulsive force generated around the slit portion 28 when the slit portion 28 opens. Therefore, the gap 60 becomes easier to close, and the opening size of the gap 60 becomes easier to reduce. Also, the thicker the blank 10, the stronger the repulsive force when the blank 10 is folded, so that the protruding piece 20 inserted in the gap 60 becomes easier to rotate, and as a result, the protruding piece 20 becomes easier to detach from the gap 60.

[0090] In contrast, in this embodiment, since the slit 28 extends along the slit 28, a repulsive force is less likely to occur near the slit 28, and therefore a reduction in the opening size of the gap 60 due to the repulsive force can be suppressed. As a result, even if the thickness of the blank 10 increases, the protruding piece 20 can be easily inserted into the gap 60. Furthermore, even if the protruding piece 20 inserted into the gap 60 rotates, the protruding piece tip 20b is engaged with the edge of the slit as described above, and therefore, the protruding piece 20 can be more effectively prevented from coming off the gap 60.

[0091] In the present embodiment, the second panel 16 has a slit 62 formed on the folding line, more specifically, on the second top panel fold line 54 along the second top panel fold line 54. This makes it possible to more appropriately prevent the protruding piece 20 from detaching from the gap 60. To explain in more detail, the slit 62 extends from the slit 28 along the Y direction, and when the slit 28 opens, the void 60 is formed in the second panel 16 starting from the slit 62. In other words, a gap is formed when the slit 62 tears, and the void 60 expands by the amount of the gap, making it easier to insert the protruding piece 20 into the void 60. However, as the void 60 expands, the protruding piece 20 becomes more likely to detach from the void 60.

[0092] In contrast, in this embodiment, since the slit 62 is formed on the second top folding line 54, when the second panel 16 is folded at the second top folding line 54 after the protruding piece 20 is inserted into the gap 60, the gap formed by the slit 62 being torn is blocked by the portion of the second panel 16 adjacent to the second top folding line 54. By blocking the gap in this manner, it is possible to appropriately prevent the protruding piece 20 inserted into the gap 60 from coming off the gap 60.

[0093] Further, the second panel 16 is provided with an intersecting slit 64 that intersects with the slit 62, and the intersecting slit 64 has an outer portion 64a that extends outward in the X-direction as shown in Fig. 3. This allows the slit portion 28 to open starting from the outer portion 64a, and allows the slit portion 28 to open larger than when the outer portion 64a is not provided. This makes the gap 60 wider, and allows the protruding piece portion 20 to be inserted into the gap 60 more easily.

[0094] Furthermore, by providing the outer portion 64a as the intersecting slit 64, the edge of the slit can be easily displaced outward, and the angle (intersecting angle) formed by the edge of the slit with respect to the protruding piece tip 20b can be made larger. This increases the area of ​​the protruding piece tip 20b that abuts against the edge of the slit, making it easier for the protruding piece tip 20b to be engaged with the edge of the slit. As a result, it is possible to more effectively prevent the protruding piece 20 from coming off the gap 60.

[0095] More specifically, when the protruding piece 20 is inserted into the gap 60, a portion of the second panel 16 adjacent to the slit portion 28 (specifically, the second extending portion 32) on the Y-direction outer side of the slit portion 28 is pushed inwardly of the box body 1 (strictly speaking, the box body 1 in the middle of assembly) by the protruding piece 20. On the other hand, a portion located outside the slit 62 in the X-direction is disconnected from the portion pushed inwardly of the box body 1 by the protruding piece 20 due to the presence of the slit 62, and is not pushed inwardly of the box body 1 together with the portion. As a result, a portion of the second panel 16 located outside the slit 62 in the X-direction, specifically, an end portion of the second top panel 52 on the second side panel 50 side, is separated from the portion pushed inwardly of the box body 1 and can be displaced (opened) outwardly of the box body 1. Therefore, the portion of the protruding piece 20 inserted into the gap 60 that abuts against the end portion of the second top panel 52 on the second side panel 50 side increases. As a result, the protruding piece tip portion 20b can be easily engaged with the edge portion of the slit, and the protruding piece portion 20 can be prevented from coming off the gap portion 60 more effectively.

[0096] Furthermore, the intersecting slit 64 has an inner portion 64b extending inward in the X direction. This makes it easier to displace the portion of the second panel 16 adjacent to the slit 28 on the outer side in the Y direction toward the inside of the box body 1 when the slit portion 28 and the slit 62 open. In other words, the provision of the inner portion 64b of the intersecting slit 64 makes it possible to increase the opening length when the slit portion 28 and the slit 62 open. This makes it easier for the slit portion 28 and the slit 62 to open, and as a result, the opening size (opening area) is enlarged, making it even easier to insert the protruding piece portion 20 into the gap portion 60.

[0097] On the other hand, when the slit 62 opens, the second panel 16 tears at the position where the slit 62 is formed, forming a gap, and the void portion 60 can be widened by the gap, but there is a risk that the slit 62 will extend further and the second panel 16 will tear excessively. In contrast, in this embodiment, both the outer portion 64a and the inner portion 64b constituting the above-mentioned intersecting slit 64 extend continuously in a straight line along the X direction. With this configuration, it is possible to prevent the second panel 16 from tearing more than necessary starting from the slit 62.

[0098] In the present embodiment, each of the outer portion 64a and the inner portion 64b constituting the intersecting slit 64 extends from the tip of the slit 62, but is not limited to this. For example, as shown in Fig. 9, both the outer portion 64a and the inner portion 64b may extend from a middle position of the slit 62. Also, one of the outer portion 64a and the inner portion 64b may extend from the tip of the slit 62, and the other may extend from a middle position of the slit 62. However, if both the outer portion 64a and the inner portion 64b extend from the tip of the slit 62, the effect of providing the intersecting slit 64 described above is maximized. In addition, in a configuration in which the intersecting slit 64 extends from a midpoint of the slit 62, only one of the outer portion 64a and the inner portion 64b may be provided, but from the viewpoint of more effectively exerting the above-mentioned effect, it is preferable to provide both the outer portion 64a and the inner portion 64b.

[0099] Furthermore, the protruding piece tip 20b has the protruding piece notch 20c at the end opposite the second panel 16 in the Y direction, as described above. When the protruding piece 20 is inserted into the gap 60, the portion of the protruding piece tip 20b adjacent to the protruding piece notch 20c firmly engages with the edge of the gap 60. As a result, when the blank 10 is folded to obtain the box 1 with the upper end opening open, and the first panel 14 falls outward due to the reaction force of the folding, the connected state of the folded first panel 14 and second panel 16 can be maintained, improving the ease of stacking (stackability) of the box 1.

[0100] As described above, in this embodiment, the connected state of the first panel 14 and the second panel 16 can be maintained (locked) by inserting the protruding piece portion 20 into the gap portion 60. This makes it possible to assemble the box body 1 easily and appropriately without requiring skilled techniques when folding the blank 10 to assemble the box body 1.

[0101] Furthermore, when the blank 10 is folded until it becomes a box with its top opening open, as described above, the folded first panel 14 and second panel 16 each tilt slightly outward from a vertically standing state relative to the bottom panel 12 due to the reaction force of the folding. This causes the top opening to open, and the box 1 becomes self-supporting, allowing the box 1 to be stored efficiently, thereby improving the efficiency of the storage operation (specifically, stacking operation) of the box 1.

[0102] Furthermore, in this embodiment, only the protruding piece tip 20b of the protruding piece 20 is inserted into the gap 60 and enters from the outside to the inside of the second panel 16. This makes it easier to stack boxes 1 with open upper end openings. In other words, if only the protruding piece tip 20b is inserted into the gap 60, when stacking a plurality of boxes 1 with open upper end openings, there is less interference between two vertically adjacent boxes 1, so the boxes can be stacked well. Furthermore, by tilting the first panel 14 and the second panel 16 slightly outward from the state where they stand perpendicular to the bottom panel 12, a so-called slide effect is created, allowing one box body 1 to slide smoothly into another box body 1. This makes it even easier to stack the boxes 1 on top of each other.

[0103] [Modifications of the lock structure in the blank of the present invention] The configuration of the lock structure part of the blank of the present invention is not limited to the above-mentioned embodiment (i.e., this embodiment), and other examples (variations) are possible. The configurations of the lock structure part according to the first to fifth variations will be described below. In the following description, components that are the same as those in the already described embodiments and content that is common to the already described embodiments will not be described, and in the drawings, the same symbols as those in the above described embodiments will be used.

[0104] (First Modification) 10, the lock structure according to the first modified example (hereinafter, lock structure 118) has a protruding piece 20, a slit portion 128, a slit 62, and an intersecting slit 64. The protruding piece 20 has substantially the same configuration and shape as the protruding piece 20 of the present embodiment.

[0105] As shown in FIG. 10, the slit portion 128 has a first extension portion 130 extending toward the bottom panel 12 along the X direction, and a second extension portion 132 intersecting the first extension portion 130 and extending inward in the Y direction. One end of the first extension portion 130 is on the second top panel folding line 54 in the X direction. The first extension portion 130 extends in a direction slightly inclined with respect to the X direction, and the portion other than the first extension portion end portion 130a is displaced inward in the Y direction as it approaches the bottom panel 12. In addition, the first extension portion end portion 130a is curved in a semicircular shape, and the end of the first extension portion 130 opposite the first extension portion end portion 130a is curved in an arc shape so as to move inward in the Y direction as it moves away from the bottom panel 12.

[0106] 10, the second extending portion 132 has a parallel portion 132a extending parallel to the Y direction from one end of the first extending portion 130, and an inclined portion 132b extending in a direction inclined with respect to the Y direction from an end of the parallel portion 132a on the inner side in the Y direction. The parallel portion 132a extends toward the inside in the Y direction and is approximately on the same line as the second top panel folding line 54 in the X direction. The inclined portion 132b extends toward the outside in the X direction.

[0107] 10, the second extending portion 132 may further have a vertical slit 132c extending parallel to the X direction and inward in the X direction at the intersection of the parallel portion 132a and the inclined portion 132b. By providing this vertical slit 132c, the gap 60 formed by the opening of the slit portion 128 and the slit 62 can be further widened, and the protruding piece portion 20 can be more easily inserted into the gap 60.

[0108] In the first modified example configured as described above, the slit portion 128 and the cut 62 are opened to form the gap portion 60, and when the protruding piece portion 20 is inserted into the gap portion 60, the protruding piece tip portion 20b is locked into the portion of the edge of the gap portion 60 that is adjacent to the parallel portion 132a of the second extending portion 132. In addition, the protruding piece portion 20 is pressed by the second panel pressing portion 66, whereby the state in which the protruding piece portion 20 is inserted into the gap portion 60 is satisfactorily maintained (locked).

[0109] Furthermore, the protruding piece tip portion 20b inserted into the gap 60 is also engaged with the first extending portion end portion 130a of the slit portion 128. According to this configuration, the first panel 14 and the second panel 16 are well maintained in a state in which they stand up substantially perpendicular to the bottom panel 12.

[0110] The second extending portion 132 of the slit portion 128 is not limited to a configuration having the inclined portion 132b, and may be a configuration not having the inclined portion 132b. However, when the inclined portion 132b is provided, the opening size of the gap portion 60 formed by the opening of the slit portion 128 can be made larger, and as a result, the protruding piece portion 20 can be inserted into the gap portion 60 more easily.

[0111] (Second Modification) Although not shown in the drawings, in the lock structure according to the second modified example, the protruding piece 20 has a protruding piece tip portion 20b whose tip (the end on the outer side in the X direction) is flat. This makes it easier to insert the protruding piece 20 into the gap portion 60. In other respects, the protruding piece 20 according to the second modified example has the same configuration as the protruding piece 20 in the present embodiment. In the second modified example, the slit portion 128 has the same configuration as in the first modified example, and may further include a vertical slit 132c extending inward in the X direction from the intersection of the parallel portion 132a and the inclined portion 132b.

[0112] (Third Modification) In a lock structure portion according to a third modified example (hereinafter, lock structure portion 318), as shown in Fig. 11, a protruding piece portion 320 has a protruding piece base portion 320a, a protruding piece tip portion 320b, and a protruding piece recessed portion 320d, but does not have a protruding piece notch portion. Also, in the third modified example, the protruding piece tip portion 320b has a protruding piece protrusion portion 320t. As shown in Fig. 11, the protruding piece protrusion portion 320t protrudes in parallel to the Y direction toward the opposite side to the second panel 16. A protruding bend line 320s parallel to the X direction is provided at the base end of the protruding piece protrusion portion 320t.

[0113] As shown in FIG. 11, the slit portion 328 of the third modified example has a first extension portion 330 extending toward the bottom panel 12 along the X direction, and a second extension portion 332 intersecting the first extension portion 330 and extending inward in the Y direction. The first extension portion 330 is located slightly inward from the end position of the second top panel fold line 54 in the Y direction, and extends across the second top panel fold line 54 in the X direction, with one end located outside the second top panel fold line 54 in the Y direction. The first extension portion 330 extends in a direction slightly inclined with respect to the Y direction, and is displaced inward in the Y direction as it approaches the bottom panel 12. The first extension portion end portion 330a is curved in a semicircular shape.

[0114] 11, the second extending portion 332 has an inclined portion 332a and a parallel portion 332b. The inclined portion 332a extends outward in the X direction from one end of the first extending portion 330 in a direction inclined with respect to the Y direction. The parallel portion 332b extends inward in the Y direction parallel to the Y direction from an inner end of the inclined portion 332a in the Y direction. A second extending portion end portion 332c, which is an inner end of the parallel portion 332b in the Y direction, is curved in a semicircular shape.

[0115] In the third modified example, the slit portion 328 opens from the end of the first extension portion 330 on the inner side in the X direction (toward the bottom panel 12) and the end of the parallel portion 332b on the outer side in the Y direction, and the size of the gap portion 60 formed thereby is larger than in this embodiment.

[0116] Moreover, the first extending portion 330 and the inclined portion 332a are provided in a position in the Y direction relatively close to the outer end of the second panel 16 in the Y direction. Furthermore, a slit 62 extends outward in the Y direction from the intersection of the first extending portion 330 and the inclined portion 332a. As a result, even if the size of the protruding piece tip portion 320b increases to include the protruding piece protrusion 320t, the slit portion 328 can be opened sufficiently to accommodate the protruding piece tip portion 320b, and the protruding piece portion 320 can be appropriately inserted into the gap portion 60.

[0117] Moreover, after the protruding piece 320 is inserted into the gap 60, when the second panel 16 is folded at the second top panel folding line 54, the protruding piece protrusion 320t is folded at the folding line 320s. At this time, the protruding piece protrusion 320t is folded approximately perpendicular to the direction in which the protruding piece 320 is inserted into the gap 60. As a result, the protruding piece protrusion 320t is engaged with the edge of the gap 60, so that it is possible to appropriately prevent the protruding piece 320 from being detached from the gap 60. Furthermore, when the protruding piece 320 is inserted into the gap 60, the protruding piece tip 320b is engaged with a portion of the edge of the gap 60 adjacent to the parallel portion 332b of the slit portion 328, and the state in which the protruding piece 320 is inserted into the gap 60 is well maintained (locked).

[0118] (Fourth Modification) In a lock structure portion according to a fourth modified example (hereinafter, lock structure portion 418), a protruding piece portion 420 has a protruding piece base portion 420a and a protruding piece tip portion 420b as shown in Fig. 12. Also, a slit portion 328 according to the fourth modified example has a similar configuration to the slit portion 328 of the third modified example as shown in Fig. 12.

[0119] Similar to the second modified example, the tip (the outer end in the X direction) of the protruding piece tip portion 420b is parallel to the Y direction and has a flat shape. Furthermore, the end of the protruding piece tip portion 420b on the second panel 16 side in the Y direction forms a semicircular protruding piece protrusion portion 420t that protrudes toward the second panel 16 side in the Y direction. Furthermore, a protruding piece recess 420d is provided at the end of the protruding piece 420 on the second panel 16 side in the Y direction, the protruding piece recess 420d being located between the protruding piece base 420a and the protruding piece tip 420b and formed parallel to the Y direction. Further, a protruding piece notch 420c is formed at the end of the protruding piece tip 420b on the opposite side to the second panel 16 in the Y direction.

[0120] In the locking structure 418 configured as described above, when the protruding piece 420 is inserted into the gap 60, the portion of the protruding piece tip 420b adjacent to the protruding piece recess 420d abuts against the portion of the edge of the gap 60 adjacent to the first extending portion end 330a of the slit portion 328, and is engaged with the first extending portion end 330a.

[0121] In the fourth modified example, the protruding piece portion 420 is provided with the protruding piece protrusion portion 420t, so that it is possible to increase the contact area with the second panel pressing portion 66 when the protruding piece portion 420 is inserted into the cavity portion 60. Furthermore, since the protruding piece protrusion portion 420t is provided, the portion of the protruding piece tip portion 420b that is engaged with the edge of the cavity portion 60 increases, so that it is possible to prevent the protruding piece portion 420 from coming off the cavity portion 60.

[0122] The protruding piece protrusion 420t protrudes parallel to the Y direction as described above. On the other hand, when the first panel 14 is folded at the first folding line 24 and the protruding piece 420 rotates around the first folding line 24, the protruding piece 420 moves in a direction substantially perpendicular to the first extending portion 330 of the slit portion 328 and is inserted into the gap 60. At this time, the protruding piece protrusion 420t comes into contact widely with a portion of the edge of the gap 60 adjacent to the first extending portion end portion 330a, and is pressed over a wide range by the second panel pressing portion 66. This allows the protruding piece 420 to be well maintained (locked) in a state where it is inserted into the gap 60.

[0123] (Fifth Modification) In a lock structure portion according to a fifth modified example (hereinafter, lock structure portion 618), a protruding piece portion 620 has a protruding piece base portion 620a and a protruding piece tip portion 620b, as shown in Fig. 13. A protruding piece recess portion 620d is formed between the protruding piece base portion 620a and the protruding piece tip portion 620b at the end portion of the protruding piece portion 620 on the second panel 16 side in the Y direction. The protruding piece recess portion 620d is inclined (towards the lower right in Fig. 13) so as to approach the protruding piece folding line 22 as it approaches the second panel 16.

[0124] Furthermore, a protruding piece protrusion 620u is provided at the end of the protruding piece tip 620b on the second panel 16 side in the Y direction, and a protruding piece protrusion 620t is provided at the end opposite the second panel 16. The protruding piece protrusion 620u is inclined (towards the lower right in FIG. 13) so as to approach the protruding piece fold line 22 as it approaches the second panel 16. The protruding piece protrusion 620t protrudes parallel to the Y direction toward the opposite side to the second panel 16. In the fifth modified example, even a protruding piece 620 having two protruding piece protrusions 620t, 620u at both ends of the protruding piece tip 620b in the Y direction can be reliably inserted into the gap 60. In addition, each of the two protruding piece protrusions 620t, 620u is engaged with the edge of the gap 60, and the protruding piece tip portion 620b is pressed by the second panel pressing portion 66, so that the protruding piece portion 620 is securely maintained (locked) in the inserted state in the gap 60.

[0125] In the fifth modified example, the slit portion 628 has a first extending portion 630 and a second extending portion 632, as shown in FIG. 13. The first extending portion 630 extends toward the outside in the X direction and in a direction slightly inclined with respect to the X direction. The end portion on the inside of the X direction of the first extending portion 630 is inclined so as to be positioned inward in the Y direction as it moves toward the outside in the X direction. The portion of the first extending portion 630 that extends from a position slightly inside the second top panel fold line 54 in the X direction to a position beyond the second top panel fold line 54 is inclined so as to be positioned outward in the Y direction as it moves toward the outside in the X direction. The first extending portion end portion 630a is curved in a semicircular shape. The second extending portion 632 is similar to the second extending portion 332 of the third modified example, and as shown in FIG. 13, has an inclined portion 632a and a parallel portion 632b, and the second extending portion end portion 632c is curved in a semicircular shape.

[0126] In the fifth modified example, when the protruding piece 620 is inserted into the gap 60, the protruding piece recess 620d engages with the edge of the gap 60, specifically, the portion adjacent to the end of the first extending portion 630 of the slit portion 628 on the inner side in the X direction, and the protruding piece tip 620b is locked to the portion. In addition, since the protruding piece protrusion 620u is inclined toward the protruding piece folding line 22 as it approaches the second panel 16, when the protruding piece 620 inserted into the gap 60 rotates upward, the protruding piece tip 620b is locked to a portion of the edge of the gap 60 adjacent to the first extending portion end portion 630a. In addition, the protruding piece 620 inserted into the gap 60 is pressed by the portion of the second panel 16 adjacent to the slit portion 628, i.e., the second panel pressing portion 66. This allows the protruding piece 620 to be well-inserted into the gap 60 and locked in place.

[0127] [Further Modifications of the Invention] Further variations of the blank of the present invention may include Variations 6 to 9. These variations will be described below.

[0128] (Sixth Modification) In the blank 10 described above, the second fold line 26 is arranged on a straight line. In contrast, in the blank 10X according to the sixth modified example, as shown in FIG. 14, the second fold line 26X is formed by a plurality of straight lines at different positions in the X direction. To explain in more detail, in the blank 10X shown in FIG. 14, the second fold line 26 has a fold line forming an end in the X direction (hereinafter, side end fold line 26a) and a fold line forming a center in the X direction (hereinafter, center fold line 26b). In other words, the blank 10X is configured such that the center fold line 26b is disposed between the two side end fold lines 26a.

[0129] The side end fold line 26a and the central fold line 26b are each a fold line consisting of a straight line parallel to the Y direction. On the other hand, the central fold line 26b is offset in the X direction from the side end fold line 26a, and is positioned slightly (for example, about 2 mm) outward in the X direction from the side end fold line 26a. Also, as shown in FIG. 14, the Y-direction inner end of each side end fold line 26a is connected to the X-direction inner end of the slit portion 28 adjacent to the side end fold line 26a (more specifically, the end of the first extension portion 30). According to the above-mentioned configuration, when the second panel 16 is folded at the second fold line 26X so as to rise vertically relative to the bottom panel 12, the Y-direction end portion of the second panel 16 is folded at the side end fold line 26a, and the Y-direction center portion is folded at the center fold line 26b. As a result, in a state in which the second panel 16 rises vertically relative to the bottom panel 12, the Y-direction center portion of the second panel 16 is located outside the box 1 relative to the Y-direction end portion. As a result, the slit portion 28 and the cut 62 can be opened more easily to form the gap portion 60. Also, the second panel pressing portion 66 can be more easily formed in the portion of the second panel 16 adjacent to the slit portion 28.

[0130] (Seventh Modification) In the above-described embodiment, the protruding piece fold line 22 is offset slightly outward from the second fold line 26 in the Y direction. In contrast, in the seventh modified example, the protruding piece fold line 22X is provided at the same position as the second fold line 26 in the Y direction, as shown in Fig. 15. In other words, the second fold line 26 is located on an extension line of the protruding piece fold line 22 in the Y direction, and the second fold line 26, the apex of the bottom panel 12 (shown by a black dot in Fig. 3), and the protruding piece fold line 22X are continuous on a straight line.

[0131] In the seventh modified example configured as described above, when the protruding piece 20 is inserted into the gap 60, the first panel 14 rotates relative to the bottom panel 12 from the apex of the bottom panel 12, i.e., the first fold line 24, as a starting point, so that the protruding piece 20 moves toward the gap 60. At this time, the protruding piece tip 20b abuts without any gap against a portion of the second panel 16 adjacent to the slit portion 28 in the Y direction, i.e., the second panel pressing portion 66, and is smoothly inserted into the gap 60 while being pressed by the second panel pressing portion 66. Furthermore, when the protruding piece 20 is inserted into the gap 60, the protruding piece tip 20b is locked without any rattle against the edge of the gap 60. This makes the joining area between the protruding piece tip 20b and the edge of the gap 60 wider, thereby improving the locking force of the edge of the gap 60 against the protruding piece tip 20b.

[0132] (Eighth Modification) In the above-described embodiment, the protruding piece 20 is continuous with the first panel 14 and cannot be separated from the first panel 14. In contrast, in the eighth modified example, as shown in FIG. 16, a break line 70 for breaking the protruding piece 20 is provided, and the protruding piece 20 can be separated from the first panel 14 along the break line 70. The break line 70 is formed on the protruding piece fold line 22 provided at the base end of the protruding piece 20 and extends along the Y direction (second direction). This cut line may be, for example, a perforation provided intermittently from one end to the other end of the protruding piece fold line 22, or a half-cut line and a cut formed along the protruding piece fold line 22. The perforation, the half-cut line, and the cut may be formed obliquely with respect to the protruding piece fold line 22. The breaking line 70 is not particularly limited as long as it is configured to enable the protruding piece portion 20 to be cut off, and may be formed by any known technique.

[0133] The blank of the eighth modified example (hereinafter, blank 10Y) forms a box body of a yoke type (tatou type), and although it is different in type and shape from blank 10 forming the N type box shown in Fig. 1, the basic structure is the same except for the inclusion of a break line 70. Therefore, in Fig. 16 and the following description of the eighth modified example, each part of blank 10Y will be given the same reference numeral as the corresponding part of blank 10 shown in Fig. 1; for example, in Fig. 16, the part corresponding to the bottom panel of blank 10Y is given the reference numeral "12".

[0134] 16, a zipper portion 36a, which is a cuttable band-shaped portion, may be provided along the X direction on the first top plate 36 of one of the first face plates 14a of the blank 10Y. In this case, zipper cut lines 36b, which are perforations or cuts, may be formed on both side ends (both ends in the Y direction) of the zipper portion 36a. Similarly to the blank 10 shown in FIG. 1, the material of the blank 10Y is not particularly limited, but for example, corrugated cardboard, thick paper, coated cardboard, paperboard, plastic corrugated cardboard, etc. can be used as the material of the blank 10Y.

[0135] In the eighth modified example, the projecting piece portion 20 can be torn along the breaking line 70 and separated from the first panel 14, so that the sealed box 1 can be easily opened. That is, in the sealed box 1, the projecting piece portion 20 is separated from the first panel 14, so that the locked state by the locking structure portion 18, that is, the connection state between the first panel 14 and the second panel 16, is released. This allows the first panel 14 to move away from the second panel 16, and specifically, the first side panel 34 and the first top panel 36 included in the first panel 14 can move to open toward the outside of the box 1. As a result, the side and top surfaces of the box 1 (that is, the surfaces closed by the first side panel 34 and the first top panel 36) are opened, and the storage space of the box 1 is exposed to the outside of the box 1 at the opened portion. Then, by opening the side and top surface of the box 1, the contents in the box 1 can be easily taken out.

[0136] The above effect is particularly effective when the size of the contents (strictly speaking, the size of the contents when viewed from the top side of the box body 1, and the same applies hereinafter) is approximately equal to the size of the top surface. To explain in more detail, a conventional box body may be one in which the opening opening is provided on the bottom surface. If an item of the same size as the top surface is stored inside such a box body, when the part of the bottom surface of the box body that covers the opening opening is pressed with a finger or the like to open it, the part pressed with the finger or the like may hit the contents. In that case, the opening opening on the bottom surface is difficult to open, and it is difficult to remove the contents from the box body.

[0137] In contrast, as described above, the side and top surfaces of the box 1 according to the eighth modified example can be opened, so that the opening in the storage space of the box 1 can be opened widely. This allows the holder of the box 1 to easily remove the contents from the box 1 through the opening, and more specifically, the contents can be removed from the side of the box 1 with one hand. At this time, the first side plate 34 and the first top plate 36 open toward the outside of the box 1 and are aligned substantially on the same plane as the bottom plate 12, so that the contents can slide along that plane, and as a result, the contents can be removed more smoothly.

[0138] When the protruding piece 20 is to be separated from the first panel 14 along the breaking line 70, the holder of the box 1 lifts up a portion of the box 1 near the breaking line 70. This lifting action exerts a force on the portion near the breaking line 70, causing the protruding piece 20 to break along the breaking line 70. Furthermore, when the protruding piece 20 is torn and separated from the first panel 14, a restoring force (resistance force) due to the rigidity of the paper material constituting the blank 10Y acts on the first panel 14, and this force makes it easier for the first side panel 34 and the first top panel 36 to move in a direction that opens outward. As a result, it becomes easier to open the first side panel 34 and the first top panel 36, i.e., to open the box 1.

[0139] Furthermore, in the eighth modified example, the ease of opening the box body 1 can be improved without significantly changing the shape and structure of the box body 1 (in other words, the blank 10Y) by a relatively simple design of providing the break line 70 on the protruding piece fold line 22. Therefore, the machinery and equipment for folding the blank 10Y to make and seal the box body 1 can continue to be used without changing the specifications from when the break line 70 is not provided. In other words, the ease of opening the box body 1 can be improved while maintaining the mechanical suitability for the work of making and sealing the box body 1.

[0140] (Ninth Modification) In the ninth modified example, the above-described embodiment is improved to have a configuration in which the protruding piece portion 20 can be more easily inserted into the gap portion 60. Specifically, in the ninth modified example, as shown in Fig. 17, an opening fold line 72 is provided near the slit portion 728 of the second panel 16. The opening fold line 72 is preferably a valley fold. When the slit portion 28 is opened to form the gap portion 60, the second panel 16 is bent at the opening fold line 72, making it easier to form the gap portion 60.

[0141] More specifically, as shown in FIG. 17, in the ninth modification, the slit portion 728 has a first extending portion 730 and a second extending portion 732, similar to the third modification. The first extending portion 730 extends toward the bottom plate 12 side along the X direction. The second extending portion 732 has an inclined portion 732a and a parallel portion 732b, as shown in FIG. 17. The inclined portion 732a extends from one end (more specifically, the outer end in the X direction) of the first extending portion 730 toward the outside in the X direction in a direction intersecting with the first extending portion 730, and is inclined toward the inside in the Y direction with respect to the X direction. The parallel portion 732b extends from the inner end of the inclined portion 732a in the Y direction toward the inside in the Y direction in a direction parallel to the Y direction. In addition, it is preferable that the inner end (terminal portion) of the parallel portion 732b in the Y direction is curved in a semicircular shape.

[0142] In the ninth modified example, the second panel 16 is provided with the above-mentioned opening fold line 72. As shown in Fig. 17, the opening fold line 72 extends from a position on the second panel 16 that is farther from the bottom panel 12 than the inclined portion 732a of the second extending portion 732 toward the inclined portion 732a.

[0143] More specifically, the opening fold line 72 extends along the X direction toward a portion of the inclined portion 732a that is closer to the center of the inclined portion 732a than both ends of the inclined portion 732a in the Y direction. In the embodiment shown in Fig. 17, the opening fold line 72 extends approximately parallel to the X direction toward approximately the center of the inclined portion 732a in the Y direction. However, the opening fold line 72 may be a line (ruled line) that extends in a direction inclined with respect to the X direction.

[0144] The opening fold line 72 configured as above functions as a fold line when bending the second panel 16 on the opposite side to the first extending portion 730, that is, the portion adjacent to the inclined portion 732a on the outer side of the first extending portion 730 in the X direction (hereinafter, the opening fold line) when opening the slit portion 728. When opening the slit portion 728, the opening fold line is folded toward the inside of the box body 1 along the opening fold line 72, so that the slit portion 728 can be opened larger, and a wider gap portion 60 is formed. As a result, the protruding piece portion 20 can be inserted into the gap portion 60 more easily. In addition, since the opening fold line 72 is provided on the outer side of the inclined portion 732a in the X direction, the external force (input) when bending the opening fold line 72 is directed from the opening fold line 72 to the gap portion 60 and is easily concentrated on the gap portion 60, so that the slit portion 728 is easily opened. As a result, the protruding piece 20 can be inserted into the gap 60 even more easily.

[0145] Note that the blank of the ninth modified example (hereinafter, blank 10Z) forms a tray-shaped box without a top plate, and although its type and shape are different from the blank 10 shown in Fig. 1, its basic configuration is similar except that it does not have a top plate and is provided with the above-mentioned opening fold line 72. Therefore, in Fig. 17 and the following description of the ninth modified example, each part of blank 10Z will be given the same reference numeral as the corresponding part of blank 10 shown in Fig. 1, and for example, in Fig. 17, the part corresponding to the second panel of blank 10Z is given the reference numeral "16".

[0146] In the blank 10Z, the second panel 16 includes a second side panel 50 as a side panel, and the second side panel 50 forms a side surface of a tray-shaped box and is connected to the bottom panel 12 in the X direction. In the configuration shown in FIG. 17, the first extension portion 730 and the second extension portion 732 of the slit portion 728, the opening fold line 72, and the opening fold portion are all provided on the second side panel 50. This makes it easier to concentrate the external force (input) when bending the opening fold portion on the gap portion 60. As a result, the slit portion 728 is made even easier to open, and the protruding piece portion 20 can be inserted into the gap portion 60 even more easily.

[0147] 1, the material of the blank 10Z is not particularly limited, but for example, corrugated cardboard, thick paper, coated cardboard, paperboard, plastic corrugated cardboard, etc. can be used as the material of the blank 10Y. When the blank 10Z is made of a harder or thicker paper material, the effect of providing the opening fold line 72 to facilitate insertion of the protruding piece portion 20 into the gap portion 60 becomes more pronounced.

[0148] Furthermore, in the ninth modified example, the ease of assembling the box body, more specifically, the ease of inserting the protruding piece portion 20 into the gap portion 60, can be improved without significantly changing the shape and structure of the box body (in other words, the blank 10Z) by a relatively simple design of providing the opening fold line 72 on the second panel 16. Therefore, the machinery and equipment for folding the blank 10Z to make and seal the box body can continue to be used without changing the specifications from when the opening fold line 72 is not provided. In other words, the ease of assembling the box body can be improved while maintaining the mechanical suitability for the box body making and sealing operations.

[0149] The effect of providing the opening fold line 72 on the second panel 16 is also exhibited in a configuration such as a blank 800 shown in Fig. 18 that includes the protruding piece 20 and the slit portion 728 but does not include the slit 62 or the cross slit 64. The blank 800 is a blank according to a reference example different from the present invention, but also in this reference example, by providing the opening fold line 72 on the second panel 16, the slit portion 728 can be easily opened and the protruding piece 20 can be easily inserted into the gap 60. However, in terms of making it easier to open the slit portion 728 and making it easier to insert the protruding piece 20 into the gap 60, it is preferable to provide the slit 62 and the cross slit 64. Incidentally, the blank 800 according to the above reference example has substantially the same configuration as the blank 10Z according to the ninth modified example, except that it does not have the slit 62 and the intersecting slit 64. Therefore, the same reference numerals as the corresponding parts of the blank 10Z shown in FIG. 17 are used for the respective parts of the blank 800 shown in FIG.

[0150] (Application of modified examples to blanks of other shapes) Although the eighth and ninth modified examples have been described above using the blanks 10Y and 10Z shown in Figures 16 and 17 as examples, these blanks are merely examples. That is, the configurations of the above two modified examples can also be applied to blanks having shapes other than the blanks 10Y and 10Z shown in Figures 16 and 17, for example, the blank 810 shown in Figure 19. The blank 810 has an insertion protruding piece 74 protruding from an end of the first top plate 36 at one end in the Y direction and an insertion slit 76 formed in the first top plate 36 at the other end in the Y direction, and is a blank for forming a box body of a fold type that is sealed by inserting the insertion protruding piece 74 into the insertion slit 76. Moreover, the blank 810 has a breaking line 70 at the base end of the protruding piece portion 20, and an opening fold line 72 on the second panel 16, as shown in FIG. Note that the basic configuration of blank 810 is substantially similar to that of blank 10Y shown in Fig. 16, and therefore in Fig. 19, the same reference numerals are used for the respective parts of blank 810 as for the corresponding parts of blank 10Y shown in Fig. 16. Also, in Fig. 19, the stripes drawn within the dashed circle in the center of bottom panel 12 indicate the grain of the core of the cardboard sheet constituting blank 810, and the direction of the stripe lines corresponds to the direction of the grain of the core.

[0151] Furthermore, blanks having a configuration in which two or more of the above-mentioned modified examples are combined may be considered. For example, as shown in Fig. 20, a blank 820 in which the shape of the slit portion 728 of the blank 10Y according to the eighth modified example is replaced with the shape of the slit portion 128 of the first modified example may be given as an example. 20, the blank 820 has a break line 70 at the base end of the protruding piece portion 20, and also has an opening fold line 72 on the second panel 16. Moreover, in the blank 820, the slit portions 128 and the opening fold line 72 are all provided on the second side panel 50 of the second panel 16. The basic configuration of blank 820 is substantially the same as that of blank 10Y shown in Fig. 16, except for the shape of slit portion 128, and therefore in Fig. 20, the same reference numerals are used for the respective parts of blank 820 except for the slit portion as for the corresponding parts of blank 10Y shown in Fig. 16. On the other hand, the slit portion of blank 820 is used for the same reference numeral as slit portion 128 of the first modified example shown in Fig. 10.

[0152] In addition, in FIG. 20, the stripes drawn inside the dashed circle in the center of the bottom panel 12 indicate the grain of the corrugated cardboard sheet constituting the blank 820, and the direction of the stripe line corresponds to the direction of the grain of the corrugated cardboard sheet. In the blank 820 shown in FIG. 20, the grain of the corrugated cardboard sheet is parallel to the X direction. Also, as shown in FIG. 20, the opening fold line 72 extends approximately parallel to the X direction. That is, in the blank 820 shown in FIG. 20, the opening fold line 72 is formed along the grain of the corrugated cardboard sheet. With this configuration, the opening fold portion is more easily bent at the opening fold line 72, and the slit portion 128 is more easily opened, so that the protruding piece portion 20 can be more easily inserted into the gap portion 60.

[0153] In addition, the configurations of the eighth and ninth modified examples may be applied to the blank 10 shown in Figure 1 (i.e., the blank 10 related to the present embodiment described above), and one example of this is the blank 830 shown in Figure 21. As shown in FIG. 21, the blank 830 has a breaking line 70 at the base end of the protruding piece portion 20, and also has a folding line 72 for opening on the second panel 16. Since the basic configuration of the blank 830 is substantially the same as that of the blank 10 shown in FIG. 1, the parts of the blank 830 in FIG. 21 are given the same reference numerals as the corresponding parts of the blank 10 shown in FIG. Also, in Figure 21, the stripes drawn inside the dashed circle in the center of the bottom panel 12 indicate the grain of the core of the cardboard sheet that makes up the blank 830, and the direction of the stripe lines corresponds to the direction of the grain of the core. 21, the inner end in the X direction of the slit portion 28 (specifically, the first extending portion 30 of the slit portion 28) reaches the second fold line 26. With this configuration, the slit portion 28 can be opened more easily, and the protruding piece portion 20 can be inserted into the gap portion 60 more easily. This effect is more remarkable when the slit 62 and the intersecting slit 64 are provided. However, this is not limited thereto, and the inner end in the X direction of the first extending portion 30 of the slit portion 28 may be located outside the second fold line 26 in the X direction.

[0154] The effect of allowing the protruding piece 20 to be cut along the break line 70, and the effect of providing an opening fold line 72 on the second panel 16 are also achieved in configurations such as blanks 840, 850, 860 shown in Figures 22 to 24, which have the protruding piece 20 and slit portions 28, 128, 728 but do not have the slit 62 or the intersecting slit 64. Although the blanks 840, 850, 860 are blanks according to reference examples different from the present invention, in these reference examples too, by providing the second panel 16 with an opening fold line 72, it becomes easier to open the slit portions 28, 128, 728, and the protruding piece portion 20 can be easily inserted into the gap portion 60. However, in terms of making it easier to open the slit portions 128, 728 and making it easier to insert the protruding piece portion 20 into the gap portion 60, it is preferable to provide the slits 62 and the intersecting slits 64. Incidentally, the blank 840 shown in Fig. 22 has substantially the same configuration as the blank 810 shown in Fig. 19, except that it does not have the slit 62 and the intersecting slit 64. Therefore, the same reference numerals as the corresponding parts of the blank 810 shown in Fig. 19 are used for the respective parts of the blank 840 shown in Fig. 22. 20. Similarly, the blank 850 shown in Fig. 23 has substantially the same configuration as the blank 820 shown in Fig. 20, except that it does not have the slit 62 and the cross slit 64. Therefore, the same reference numerals are used for the parts of the blank 850 shown in Fig. 23 as the corresponding parts of the blank 820 shown in Fig. 20. Note that, as a modification of the blank 850 shown in Fig. 23, as shown in Fig. 24, the end portion (the end portion on the inner side in the X direction) of the first extending portion 130 may reach the second fold line 26. With this configuration, the slit portion 128 becomes easier to open, and the protruding piece portion 20 can be more easily inserted into the gap portion 60. 21, except that the blank 860 shown in FIG. 25 does not include the slit 62 and the cross slit 64. Therefore, the blank 860 shown in FIG. 25 is denoted by the same reference numerals as the corresponding parts of the blank 830 shown in FIG. 21. In the blank 860 shown in FIG. 25, the inner end in the X direction of the slit portion 28 (specifically, the first extending portion 30 of the slit portion 28) reaches the second fold line 26. With this configuration, the slit portion 28 is more easily opened, and the protruding piece portion 20 can be more easily inserted into the gap portion 60. However, the present invention is not limited to this, and the inner end in the X direction of the first extending portion 30 of the slit portion 28 may be located outside the second fold line 26 in the X direction. [Explanation of symbols]

[0155] 1 box body 10,10X,10Y,10Z Blank 12 Bottom plate 14 First face plate 14a One of the first panels 14b The other first panel 16 Second face plate 18,118,318,418,618 Lock structure 20,320,620 Projecting piece 20a,320a,420a,620a Protruding piece base 20b, 320b, 420b, 620b Tip of protruding piece 20c,420c protruding piece notch 20d, 320d, 420d, 620d Protruding piece recess 22 Protruding piece folding line 24 1st fold line 26,26X 2nd fold curve 26a Side end fold line 26b Center fold line 28,128,328,428,628,728 Slit section 30,130,330,630,730 1st extension part 30a, 130a, 330a, 630a 1st extension part end 32,132,332,632,732 2nd extension part 32a, 332c, 632c End of second extension part 34 1st side plate 36 First tabletop 36a Zipper section 36b Zipper cut line 38 First top panel fold curve 40 Front plate 42 Front bending curve 44 Insert 46 Insertion piece folding curve 48 Plug-in Wire 50 2nd side plate 52 Second Top Board 54 Second top panel fold curve 56 Cutout 58 End fold line 60 Void 62 Break 64 Cross Break 64a outer part 64b Inner part 66 Second face plate pressing part 68 Adjacent Parts 70 Break Line 72 Folding line for opening 74 Insertion piece 76 Insertion slit 132a,332b,632b,732b parallel part 132b,332a,632a,732a Sloped part 132c Vertical cut 320s protruding curve 320t,420t,620t,620u protruding piece protrusion 800, 810, 820, 830, 840, 850, 860 Blank

Claims

1. A blank comprising a polygonal bottom panel, a first panel extending from one of two sides adjacent to each other across a vertex of the bottom panel, and a second panel extending from the other of the two sides, the first panel and the second panel being folded relative to the bottom panel to form a box body, The first panel and the second panel are bent, and the bent first panel and the second panel are connected to each other with the apex interposed therebetween. The bent first panel and the second panel are connected to each other with the apex interposed therebetween. The lock structure is a protruding piece portion that protrudes from an end of the first panel on the second panel side along a first direction in which the second panel extends and is bendable at a base end in the first direction; A slit portion provided in the second face plate; a slit provided on the second panel closer to the protruding piece portion than the slit portion in a second direction intersecting with the first direction and extending from the slit portion along the second direction; The blank comprises: a protruding piece portion bent at the base end, the protruding piece portion being inserted into a gap portion formed by the opening of the slit portion and the cut line, and the connected state is maintained.

2. the locking structure further includes a cross cut extending from the cut in the second direction and crossing the cut, The blank of claim 1 , wherein the intersecting cut has a portion that extends toward the bottom panel in the first direction.

3. the locking structure further includes a cross cut extending from the cut in the second direction and crossing the cut, The blank of claim 1 , wherein the cross cut has a portion that extends opposite the bottom plate in the first direction.

4. the locking structure further includes a cross cut extending from the cut in the second direction and crossing the cut, The blank according to claim 1 , wherein the intersecting cut has both a portion extending toward the bottom panel in the first direction and a portion extending away from the bottom panel in the first direction.

5. The blank according to claim 4 , wherein at the intersecting cut, a portion extending from the cut toward the bottom panel and a portion extending from the cut toward the opposite side from the bottom panel are continuous in a straight line.

6. The blank according to claim 1 , wherein when the second panel is folded along a fold line formed along the second direction, the cut is provided on the fold line.

7. A blank as described in any one of claims 1 to 5, wherein an outer edge portion of the second panel, located opposite the bottom panel in the first direction, has a notch formed along the first direction.

8. A blank according to any one of claims 1 to 5, wherein an end of the second panel, which is located opposite the bottom panel in the first direction, has an end fold line formed along the first direction.

9. The slit portion has a first extending portion extending along the first direction and a second extending portion extending intersecting the first extending portion, In the second direction, an end of the second extending portion opposite to the protruding piece is farther from the protruding piece than an end of the first extending portion opposite to the second extending portion, The blank of claim 1 , wherein the cut line extends along the second direction from the second extending portion or an intersection of the first extending portion and the second extending portion.

10. The blank according to claim 1 , further comprising a break line formed in said protruding piece for breaking said protruding piece.

11. The blank according to claim 10 , wherein the break line is formed on a fold line of the protruding piece provided at a base end of the protruding piece and is a cut line extending along the second direction.

12. The slit portion has a first extending portion extending along the first direction and a second extending portion extending intersecting the first extending portion and including an inclined portion inclined with respect to the first direction, The second panel is provided with an opening fold line which is a fold line for folding a portion of the second panel adjacent to the second extending portion on the opposite side to the first extending portion when opening the slit portion, The blank according to claim 1 , wherein the opening fold line extends from a position on the second panel that is farther from the bottom panel than the inclined portion, toward the inclined portion.

13. The blank according to claim 12 , wherein the opening fold line extends along the first direction toward a portion of the second extension portion that is closer to a center of the inclined portion than both ends of the inclined portion.

14. the second panel includes a side panel that forms a side surface of the box body and is connected to the bottom panel in the first direction, The blank according to claim 12 or 13, wherein the first extending portion and the second extending portion of the slit portion and the opening fold line are provided on the side plate.

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