Packing box and sheet material

Abstract

To provide a packing box and sheet material that facilitate height adjustment and can suppress surface layer cracking.SOLUTION: A packing box is broken along vertical ridges of four corners to be adjusted in height dimension. The packing box is provided with a pair of first side walls (11b) located between the vertical ridges of the four corners and opposed to each other in a first direction and a pair of second side walls (12b) located between the vertical ridges of the four corners and opposed to each other in a second direction. The pair of second side walls are provided with a pair of break lines (L21) along the vertical ridge on at lest one first side wall side. The pair of break lines have a plurality of intermediate cuts (L21b) side by side in an opening direction across a connection (C). The plurality of intermediate cuts starts at positions at a predetermined distance from the vertical ridges, extends toward the vertical ridges as going downstream in the opening directions from the starting points and then extends changing the directions away from the vertical ridges, and the intermediate cuts downstream in the opening directions have their starting points located in the extending directions after the intermediate cuts upstream in the opening directions change their directions.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Conventionally, packaging boxes whose height can be adjusted depending on the size and storage capacity of the goods have been used for shipping mail-order products. Packaging boxes of this type that have perforations or zippers on the vertical ridges at the four corners of the box are known (see, for example, Patent Documents 1 and 2). The packaging boxes described in Patent Documents 1 and 2 have horizontal planned fold lines at a predetermined height on each side wall, and perforations or zippers extend from the upper ends of each vertical ridge toward the planned fold lines. The height of the packaging box is adjusted by breaking each vertical ridge along the perforations or zippers and folding each side wall at a predetermined height along the planned fold lines. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-230806 [Patent Document 2] Patent No. 6912278 Summary of the Invention [Problem to be solved by the invention]

[0004] However, even if the vertical ridges are perforated, it is difficult to break them smoothly. Furthermore, if the vertical ridges are perforated or have zippers, surface cracks may occur when assembling the packaging box.

[0005] Therefore, an object of the present invention is to provide a packaging box and a sheet material that are easy to adjust in height and can prevent surface cracks. [Means for solving the problem]

[0006] A packaging box according to one embodiment of the present invention is a packaging box whose height can be adjusted by breaking along the vertical ridges of its four corners. The packaging box comprises a pair of first side walls located between the vertical ridges of the four corners and facing each other in a first direction, and a pair of second side walls located between the vertical ridges of the four corners and facing each other in a second direction. A pair of break lines is provided on the pair of second side walls along the vertical ridges of at least one of the first side walls. The pair of break lines has a plurality of intermediate notches aligned in the opening direction across a joint. The plurality of intermediate notches start at a position a predetermined distance from the vertical ridge, extend toward the vertical ridge as they proceed downstream in the opening direction, and then change direction and extend away from the vertical ridge. The start point of the intermediate notch downstream in the opening direction is located in the extension direction of the intermediate notch upstream in the opening direction after changing direction. [Effects of the Invention]

[0007] According to the present invention, when the first side wall is pushed inward, it is pushed a predetermined distance from the vertical ridge, causing the second side wall to twist and deform. The connections between the multiple intermediate slits are twisted and the second side wall is easily torn along the fracture line. At this time, because the start point of the upstream intermediate slit in the opening direction is located in the extension direction after the upstream intermediate slit changes direction in the opening direction, the connections are easily torn from the end point of the upstream intermediate slit in the opening direction toward the start point of the downstream intermediate slit in the opening direction. In addition to the torsional deformation of the second side wall, the ease with which the connections between the intermediate slits can be torn allows the packaging box to be smoothly torn along the fracture line, making it easy to adjust the height. Furthermore, because the multiple intermediate slits overlap the vertical ridges minimally or not at all, surface cracks in the vertical ridges are suppressed when the packaging box is folded. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view of the packaging box of the present embodiment. [Figure 2] FIG. 10 is a diagram showing a fracture line of a comparative example. [Figure 3] FIG. 2 is a plan view of the sheet material of the present embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a break line according to the present embodiment. [Figure 5]10A to 10C are diagrams illustrating an example of a breaking operation of the packaging box according to the present embodiment. [Figure 6] 10A to 10C are diagrams illustrating an example of a breaking operation of the packaging box according to the present embodiment. [Figure 7] FIG. 2 is a diagram showing a portion of the folded sheet of the present embodiment. [Figure 8] FIG. 10 is a diagram showing an example of a break line in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, this embodiment will be described with reference to the drawings. Arrows Fr, Rr, L, R, U, and Lo in each drawing indicate the front, rear, left, right, upper, and lower sides when the packaging box is viewed from the front. Furthermore, although terms indicating directions and positions are used in this embodiment, these terms are used for convenience of explanation and do not limit the technical scope of the present invention.

[0010] The packaging box of this embodiment will be described with reference to Figures 1 to 3. Figure 1 is a perspective view of the packaging box of this embodiment. Figure 2 is a diagram showing the break lines of a comparative example. Figure 3 is a plan view of the sheet material of this embodiment. Note that Figure 2(A) shows an example of a comparative example in which the break lines are formed by perforations, and Figure 2(B) shows another example of a comparative example in which the break lines are formed by zippers. Note that for ease of explanation, Figure 2 shows the packaging box in an unfolded state.

[0011] As shown in Figure 1, packaging box 1 is an A-type corrugated cardboard box used for shipping mail-order products, etc., and is formed so that its height can be adjusted by breaking along the vertical ridges 3 at the four corners. Packaging box 1 has short walls (first side walls) 11a, 11b and long walls (second side walls) 12a, 12b located between the vertical ridges 3 at the four corners. Short walls 11a, 11b face each other in a first direction (front-to-back direction), and long walls 12a, 12b face each other in a second direction (left-to-right direction). These short walls 11a, 11b and long walls 12a, 12b are connected via the vertical ridges 3 to form a peripheral wall that is rectangular in top view.

[0012] Inner bottom flaps 13a, 13b are connected to the lower edges of the short walls 11a, 11b, and outer bottom flaps 14a, 14b are connected to the lower edges of the long walls 12a, 12b. The inner bottom flaps 13a, 13b are folded inside (upper sides of) the outer bottom flaps 14a, 14b, sealing the bottom opening. Inner lid flaps 15a, 15b are connected to the upper edges of the short walls 11a, 11b, and outer lid flaps 16a, 16b are connected to the upper edges of the long walls 12a, 12b. The inner lid flaps 15a, 15b are folded inside (lower sides of) the outer lid flaps 16a, 16b, sealing the top opening.

[0013] Planned folding lines (see FIG. 3) that cross the short walls 11a, 11b are provided at predetermined height positions on the short walls 11a, 11b. Planned folding lines (see FIG. 3) that cross the long walls 12a, 12b are provided at predetermined height positions on the long walls 12a, 12b. Four breaking lines L18-L21 (see FIG. 3 for breaking lines L18 and L19) are provided near the vertical ridge 3 of the long walls 12a, 12b along the vertical ridge 3. When the short walls 11a, 11b are pressed in, the vertical ridges 3 at the four corners are broken along the breaking lines L18-L21. The height dimension of the packaging box 1 is adjusted by folding the short walls 11a, 11b at a predetermined height along the planned folding lines and folding the long walls 12a, 12b at a predetermined height along the planned folding lines.

[0014] 2(A), the packaging box of the comparative example has perforations 34 on vertical ridges 33 as tear lines. Because the perforations 34 have joints C formed to prevent surface cracks from forming on the vertical ridges 33, the vertical ridges 33 are less likely to tear along the perforations 34 when the short walls 36 are pressed against them. Even if the joints C are made smaller to the extent that no manufacturing problems arise, the resistance to tearing remains the same. This is because, even if the joints C begin to tear from the end point of the upper notch 35 of the perforations 34, the start point of the lower notch 35 is not located at the destination F of the tear, making it difficult for the pressing force to be transmitted smoothly to the perforations 34.

[0015] 2(B), in another packaging box of the comparative example, a zipper 44 is provided on the vertical ridge 43 as a breaking line. The zipper 44 is formed by lining up L-shaped notches 45, and the vertical lines of the notches 45 are on the vertical ridge 43. Therefore, when the packaging box is folded, the vertical ridge 43 between the short wall 46 and the long wall 47 pulls the joint C, making it prone to surface cracks. Furthermore, if the zipper 44 is inserted with a horizontal offset during manufacturing of the packaging box, there is a risk that the box will be folded along the vertical line of the zipper 44 rather than along the fold line of the vertical ridge 43. As such, the perforations 34 of the comparative example deteriorate workability, and the zipper 44 of the comparative example deteriorates quality.

[0016] Therefore, in the packaging box 1 of this embodiment, the break lines L18-L21 are provided in the long walls 12a, 12b along the vertical ridges 3, rather than on the vertical ridges 3 at the four corners, ensuring a sufficient pushing margin for the long walls 12a, 12b to twist and deform when the short walls 11a, 11b are pushed in. By pushing the short walls 11a, 11b in a twisted state, the long walls 12a, 12b are more likely to twist and break along the break lines L18-L21. Furthermore, each cut of the break lines L18-L21 is formed in a convex curve to prevent surface cracking when the packaging box 1 is folded and to prevent deterioration of the folding accuracy of the vertical ridges 3 when the packaging box 1 is assembled. Details of the break lines L18-L21 will be described later.

[0017] As shown in Figure 3, the sheet material 5 shows the packaging box 1 in an unfolded state, and is formed by applying various processes to a single piece of cardboard sheet made of paper produced by a corrugator using a flexo folder gluer. The cardboard sheet is a double-sided cardboard sheet in which a front liner and a back liner are bonded to a corrugated core 6. Note that Figure 3 shows the cardboard sheet as seen from the front liner side. In the following explanation, the direction in which the corrugation crests of the core 6 of the cardboard sheet extend is referred to as the "corrugation direction X," and the direction perpendicular to the core 6 of the cardboard sheet is referred to as the "flow direction Y."

[0018] In the sheet material 5, a seam 17, long walls 12a, short walls 11a, long walls 12b, and short walls 11b are lined up on one side of the flow direction Y via fold lines L1-L4. Rectangular outer lid flaps 16a, 16b are connected to one side of the long walls 12a, 12b in the row direction X via fold lines L5, L6, and rectangular outer bottom flaps 14a, 14b are connected to the other side of the long walls 12a, 12b in the row direction X via fold lines L7, L8. Rectangular inner lid flaps 15a, 15b are connected to one side of the short walls 11a, 11b in the row direction X via fold lines L9, L10, and rectangular inner bottom flaps 13a, 13b are connected to the other side of the short walls 11a, 11b in the row direction X via fold lines L11, L12.

[0019] The seam 17 is formed in a substantially trapezoidal shape, while the long walls 12a, 12b, short walls 11a, 11b, outer lid flaps 16a, 16b, outer bottom flaps 14a, 14b, inner lid flaps 15a, 15b, and inner bottom flaps 13a, 13b are formed in a rectangular shape. The fold lines L1-L12 are formed by creases. A crease refers to a crease formed by linearly squeezing the cardboard sheet from the back liner side. The creases L1-L12 may be formed by other creases, such as lead creases, as long as the cardboard sheet is foldable. A lead crease refers to a crease formed by intermittently forming multiple cuts on a crease.

[0020] Planned fold lines L13-L17 are provided at intermediate positions in the row direction X of the joint margin 17, long wall 12a, short wall 11a, long wall 12b, and short wall 11b. Planned fold lines L13, L15, and L17 of the joint margin 17 and short walls 11a and 11b are formed by fold lines, while planned fold lines L14 and L16 of the long walls 12a and 12b are formed by interrupted fold lines. Note that the planned fold lines L13-L17 may be formed by other fold lines, taking into account the durability of the box, etc. Planned fold lines L18-L21 are provided along fold lines L1-L4 near both ends of the long walls 12a and 12b in the flow direction Y. Planned fold lines L18-L21 are formed by multiple curved notches.

[0021] Furthermore, a flexographic folder-gluer is used to manufacture the sheet material 5, and after the fold lines L1-L4 are formed in the sheet material 5 by a greaser, the planned fold lines L13-L17 and the break lines L18-L21 are formed in the sheet material 5 by a die cutter. Because the fold lines L1-L4 and the break lines L18-L21 are formed at different times, unlike when the fold lines L1-L4 and the break lines L18-L21 are formed simultaneously, the die does not require the punching die to be closely spaced, improving manufacturing suitability. Note that the fold lines L1-L4 may be formed after the planned fold lines L13-L17 and the break lines L18-L21 are formed in the sheet material 5. Alternatively, when manufacturing cardboard sheets using a corrugator, the planned fold lines L13-L17 and the fold lines L5-L12 may be formed simultaneously with the corrugator creasing, and the fold lines L1-L4 and the break lines L18-L21 may be formed by the flexographic folder-gluer.

[0022] The break lines will be described with reference to Fig. 4. Fig. 4 is a diagram showing an example of break lines in this embodiment. Here, only break line L21 will be described, but the same applies to break lines L18-L20. In the following description, the direction from top to bottom will be described as the opening direction in which the packaging box is opened.

[0023] 4, the fracture line L21 is formed in the long wall 12b along the fold line L4 that becomes the longitudinal ridge 3 when the sheet material 5 is assembled. The fracture line L21 has a leading notch L21a, multiple (three in this embodiment) intermediate notches L21b, a final notch L21c, and a connector C connecting each of the notches L21a to L21c. The leading notch L21a is located above (upstream in the opening direction) the uppermost (most upstream in the opening direction) intermediate notch L21b, with the connector C in between, the multiple intermediate notches L21b are lined up in the vertical direction (opening direction) with the connector C in between, and the final notch L21c is located below (downstream in the opening direction) the lowermost (most downstream in the opening direction) intermediate notch L21b, with the connector C in between.

[0024] The leading notch L21a extends diagonally downward from the lower end of the slit between the outer-lid flap 16b and the inner-lid flap 15b (the upper edge of one of the four corners of the packaging box 1), moving away from the fold line L4 (vertical ridge 3) as it progresses downward. The starting point of the uppermost intermediate notch L21b is located in the extension direction of the leading notch L21a. Because the starting point of the uppermost intermediate notch L21b is located at the end of the tear from the end point of the leading notch L21a, the joint C is likely to tear from the end point of the leading notch L21a toward the starting point of the uppermost intermediate notch L21b. The leading notch L21a assists in the start of tearing of the packaging box 1.

[0025] The multiple intermediate notches L21b start at a position a predetermined distance D away from the fold line L4 toward the long wall 12b, and as they extend downward from their starting points toward the fold line L4, they then change direction in an arc shape away from the fold line L4. The starting points of the lower intermediate notches L21b are located in the extension direction of the upper intermediate notch L21b after changing direction. Because the starting point of the lower intermediate notch L21b is located at the end of the tear from the end point of the upper intermediate notch L21b, the joint C is likely to tear from the end point of the upper intermediate notch L21b toward the start point of the lower intermediate notch L21b. The multiple intermediate notches L21b make the packaging box 1 prone to breaking.

[0026] As the final cut L21c extends downward, it curves toward the planned fold line L17 and extends diagonally downward beyond the fold line L4. The starting point of the final cut L21c is located in the extension direction of the lowest intermediate cut L21b after it changes direction. Because the starting point of the final cut L21c is located at the end of the tear in the lowest intermediate cut L21b, the joint C is likely to tear from the end point of the lowest intermediate cut L21b toward the starting point of the final cut L21c. The pressing force on the short wall 11b is transmitted from the final cut L21c to the planned fold line L17, and the short wall 11b is bent at the planned fold line L17, preventing overrunning of the fracture.

[0027] Furthermore, the starting point of the first notch L21a is located closer to the long wall 12b than the fold line L4, and only the vertices of the direction change points of the multiple intermediate notches L21b slightly overlap the fold line L4, while the final notch L21c intersects with the fold line L4. The first notch L21a does not overlap the fold line L4, and the overlap of the multiple intermediate notches L21b and the final notch L21c with the fold line L4 is kept to a minimum. Therefore, when the vertical ridge 3 is formed by bending along the fold line L4 between the long wall 12b and the short wall 11b, surface cracks are prevented even if tensile forces act on the vertical ridge 3 to the left and right.

[0028] As described above, the first notch L21a extends diagonally downward, the multiple intermediate notches L21b are curved in an arc, and the final notch L21c extends diagonally downward. The first notch L21a, the multiple intermediate notches L21b, and the final notch L21c are formed non-parallel to the fold line L4. Because the fracture line L21 has almost no portions parallel to the fold line L4, the sheet material 5 is not bent along the fracture line L21 instead of the fold line L4 between the long wall 12b and the short wall 11b. Even if the fracture line L21 is formed laterally offset relative to the sheet material 5, the sheet material 5 will not break at the fracture line L21, and the folding accuracy of the fold line L4 will not be impaired.

[0029] Next, the work of breaking the packaging box will be described with reference to Fig. 5 and Fig. 6. Fig. 5 and Fig. 6 are diagrams showing an example of the work of breaking the packaging box of this embodiment. Note that the packaging box is broken after being assembled up to a state where the top surface of the packaging box is opened.

[0030] As shown in Figure 5(A), when an operator grasps the short wall 11a of the packaging box 1, the inner-lid flap 15a is folded inward along the fold line L11. The inner-lid flap 15a bends relative to the short wall 11a, increasing the rigidity of the short wall 11a in the pushing direction. Therefore, the short wall 11a and the inner-lid flap 15a are pushed as an L-shaped structure or double wall, making the short wall 11a less likely to bend concavely even when subjected to a pushing force. Because the bending of the short wall 11a is suppressed, the pushing force against the short wall 11a is smoothly transmitted to the break lines L19 and L20 of the long walls 12a and 12b.

[0031] As shown in Figure 5(B), the short wall 11a begins to fold along the planned folding line L15, and the long walls 12a, 12b are pushed in from the longitudinal ridge 3 by the pushing margin. Both ends of the long walls 12a, 12b are twisted and deformed, and the leading notches L19a, L20a of the fracture lines L19, L20 are opened. As the short wall 11a is pushed in up to the pushing margin, the joints begin to tear from the end points of the leading notches L19a, L20a. At this time, because the leading notches L19a, L20a extend from the upper edge of the corner of the packaging box 1 toward the long walls 12a, 12b, the short wall 11a is easily pushed in up to the pushing margin, assisting the start of breaking of the packaging box 1.

[0032] As shown in Figure 6(A), when the short wall 11a is pushed in beyond the pushing margin, the long walls 12a, 12b are twisted and broken along the fracture lines L19, L20. At this time, the joints C between the end points of the first cuts L19a, L20a and the uppermost intermediate cuts L19b, L20b (see Figure 4) are torn. The joints C between the multiple intermediate cuts L19b, L20b are also torn, and the joints C between the uppermost intermediate cuts L19b, L20b and the final cuts L19c, L20c are also torn. Because the start point of the next cut is located at the end of the tear, the joints C between the multiple cuts are easily torn, and the long walls 12a, 12b are smoothly broken.

[0033] As shown in FIG. 6(B), when the long walls 12a and 12b are broken up to the final cuts L19c and L20c, the final cuts L19c and L20c open and the pushing force is transmitted to the planned folding line L15. By bending the short wall 11a at the planned folding line L15, the pushing force is no longer transmitted to the long walls 12a and 12b, preventing overrunning of the breakage. The short wall 11a is folded along the planned folding line L15, adjusting the height of the short wall 11a. Furthermore, the short wall 11b and the long walls 12a and 12b are folded along the planned folding lines L13, L15, L16, and L17, adjusting the height of the short wall 11b and the long walls 12a and 12b.

[0034] As described above, according to this embodiment, when the short walls 11a, 11b are pushed inward, the short walls 11a, 11b are pushed a predetermined distance from the longitudinal ridge 3, causing the long walls 12a, 12b to twist and deform. The joints C between the multiple intermediate cuts L18b-L21b tend to twist and break, causing the long walls 12a, 12b to fracture along the fracture lines L18-L21. Because the start point of the lower intermediate cut L18b-L21b is located at the end of the upper intermediate cut L18b-L21b, the joints C tend to tear from the end point of the upper intermediate cut L18b-L21b toward the start point of the lower intermediate cut L18b-L21b. In addition to the torsional deformation of the long walls 12a, 12b, the ease of tearing of the joints C between the intermediate cuts L18b-L21b allows the packaging box 1 to be smoothly broken at the break lines L18-L21, making it easy to adjust the height. Also, because the overlap of the multiple intermediate cuts L18b-L21b with the vertical ridges 3 is minimized or nonexistent, surface cracking of the vertical ridges 3 is suppressed when the packaging box 1 is folded.

[0035] Next, modified examples of the packaging box will be described. Fig. 7 shows a part of the folded sheet of this embodiment. Fig. 8 shows an example of a breaking line of the modified example.

[0036] As shown in FIG. 7, when the sheet material 5 of this embodiment is folded, the change-of-direction portions of the multiple intermediate notches L21b protrude convexly from the longitudinal ridge 3 between the short wall 11b and the long wall 12b. Therefore, as shown in FIG. 8, in the packaging box of the modified example, joints C are interposed at the change-of-direction portions of the multiple intermediate notches L31b, and the joints of the change-of-direction portions of the multiple intermediate notches L31b are located on the short wall 25b side. Even when the sheet material 5 is folded, the short wall 25b and the long wall 26b are connected by the joints C of the change-of-direction portions of the multiple intermediate notches L31b, so that the change-of-direction portions of the multiple intermediate notches L31b do not protrude from the longitudinal ridge 23 between the short wall 25b and the long wall 26b. In this case, the joints of the change-of-direction portions of the multiple intermediate notches L31b may be located on the longitudinal ridge 23.

[0037] In addition, in the present embodiment, one planned folding line is provided on each of the pair of short walls and the pair of long walls of the packaging box, but two or more planned folding lines may be provided on each of the pair of short walls and the pair of long walls of the packaging box, thereby making it possible to adjust the height dimension of the packaging box in multiple stages.

[0038] In this embodiment, the pair of long walls have four break lines along the vertical edges of the four corners of the packaging box, but a pair of break lines may be provided on the pair of long walls along the vertical edges of one of the short walls. In this case, auxiliary lines for folding the pair of long walls may be provided, and the pair of long walls and the other short wall may be folded to adjust the height of the packaging box.

[0039] In the present embodiment, the pair of long walls and the pair of short walls of the packaging box have different dimensions in the flow direction, but the long walls and the short walls may have the same dimensions.Furthermore, a breaking line may be provided on the pair of short walls, and the packaging box may be broken by pushing in the long walls.

[0040] In addition, in this embodiment, four break lines are provided on the top side of the vertical ridges at the four corners of the packaging box, but four break lines are provided on the bottom side of the vertical ridges at the four corners of the packaging box, so that the packaging box can be turned upside down when breaking it.

[0041] In addition, in this embodiment, the sheet material is designed to pass through from the bottom side (ground through) so that the top side is processed later when manufacturing using a flexo folder gluer, but it may also be designed to pass the sheet material through from the top side (top through).

[0042] In addition, in this embodiment, the planned fold lines of the pair of short walls are formed by creases, and the planned fold lines of the pair of long walls are formed by discontinuous creases, but the planned fold lines may be appropriately selected in consideration of the durability of the packaging box. For example, the planned fold lines may be formed by lead creases.

[0043] In addition, in this embodiment, the packaging box is provided with flaps, but the packaging box does not necessarily have to be provided with flaps.

[0044] In addition, in this embodiment, the multiple intermediate incisions extend toward the vertical ridge as they proceed downward (downstream in the opening direction) from the starting point, and then change direction to extend away from the vertical ridge, but the multiple intermediate incisions may change direction just before the vertical ridge, may change direction on the vertical ridge, or may change direction after crossing the vertical ridge.

[0045] In addition, in this embodiment, the starting point of the lower intermediate notch is located in the extension direction after the upper (upstream in the opening direction) intermediate notch changes direction, but the starting point of the lower (downstream in the opening direction) intermediate notch may be located on the extension line after the upper intermediate notch changes direction, or the starting point of the lower intermediate notch may be located at a position slightly off the extension line.

[0046] In addition, in this embodiment, the starting point of the final cut is located in the extension direction after the lowest (most downstream in the opening direction) intermediate cut changes direction, but the starting point of the final cut may be located on the extension line after the lowest intermediate cut changes direction, or may be located at a position slightly off from the extension line.

[0047] In addition, in this embodiment, the leading notch extends away from the vertical ridge as it moves downward from the upper edge of the four corners, but the leading notch may also extend from the upper end of the vertical ridge, the upper edge of the long wall, or the upper edge of the short wall, as long as it is near the upper edge of the four corners.

[0048] In addition, in this embodiment, the starting point of the uppermost intermediate notch (most upstream in the opening direction) is located in the extension direction of the leading notch, but the starting point of the uppermost intermediate notch may be located on the extension line of the leading notch, or may be located slightly off the extension line.

[0049] In addition, although the multiple intermediate incisions are curved in an arc shape in this embodiment, the multiple intermediate incisions may have any shape as long as they extend downward from the starting point toward the longitudinal ridge and then change direction. For example, the multiple intermediate incisions may change direction in a rectangular shape or a V-shape.

[0050] In addition, in each of the above embodiments, the packaging box is formed from a double-sided corrugated cardboard sheet, but the packaging box may also be formed from a single-sided corrugated cardboard sheet, a double-sided corrugated cardboard sheet, single paper, thick paper, a resin sheet, etc.

[0051] As described above, the first embodiment is a packaging box (1) whose height dimension can be adjusted by breaking along the vertical ridges (3) at the four corners, and which comprises a pair of first side walls (11a, 11b) located between the vertical ridges at the four corners and facing each other in a first direction, and a pair of second side walls (12a, 12b) located between the vertical ridges at the four corners and facing each other in a second direction, and a pair of break lines (L18-L21) are provided on the pair of second side walls along the vertical ridge on at least one of the first side walls, and the pair of break lines have a plurality of intermediate notches (L18b-L21b) lined up in the opening direction with a joint (C) between them, and the plurality of intermediate notches start at a position a predetermined distance from the vertical ridge, extend toward the vertical ridge as they proceed downstream in the opening direction from the start point, and then change direction and extend away from the vertical ridge, and the start point of the intermediate notch downstream in the opening direction is located in the extension direction of the intermediate notch upstream in the opening direction after changing direction. According to this configuration, when the first side wall is pushed inward, it is pushed a predetermined distance from the vertical ridge, causing the second side wall to twist and deform. The connections between the multiple intermediate slits twist and tear, easily causing the second side wall to tear along the break line. Because the tear advances from the end point of the upstream intermediate slit in the opening direction to the start point of the downstream intermediate slit in the opening direction, the connections easily tear from the end point of the upstream intermediate slit in the opening direction toward the start point of the downstream intermediate slit in the opening direction. Due to the twisting deformation of the second side wall and the ease with which the connections between the intermediate slits tear, the packaging box breaks smoothly along the break line, making it easy to adjust the height. Furthermore, because the multiple intermediate slits overlap the vertical ridges minimally or not at all, surface cracks in the vertical ridges are suppressed when the packaging box is folded.

[0052] In the second aspect, in the first aspect, at least one first side wall has a planned fold line (L15, L17) that crosses the first side wall, and the pair of tear lines has a final slit (L18c-L21c) located downstream in the opening direction from the most downstream intermediate slit in the opening direction, with the final slit extending toward the planned fold line as it moves downstream in the opening direction from its start point, and the start point of the final slit is located in the extension direction of the most downstream intermediate slit after changing direction in the opening direction. With this configuration, since the start point of the final slit is located at the end of the tear in the most downstream intermediate slit in the opening direction, the joint is likely to tear from the end point of the most downstream intermediate slit in the opening direction toward the start point of the final slit. When the second side wall is broken up to the final slit, the pushing force on the first side wall is transmitted from the final slit to the planned fold line, and the short wall is bent at the planned fold line, preventing overrun of the tear. Furthermore, the first side wall is bent along the intended bending line to adjust the height dimension of the first side wall.

[0053] In the third aspect, in the first or second aspect, the pair of break lines have a leading notch (L18a-L21a) located upstream in the opening direction from the most upstream intermediate notch in the opening direction, sandwiching the joint, and the leading notch extends from the upper edge of each of the four corners so as to move away from the vertical ridge as it proceeds downstream in the opening direction, and the start point of the most upstream intermediate notch in the opening direction is located in the extension direction of the leading notch. With this configuration, since the start point of the most upstream intermediate notch in the opening direction is located at the end of the tear from the end point of the leading notch, the joint is likely to tear from the end point of the leading notch toward the start point of the most upstream intermediate notch in the opening direction. Because the leading notch extends from the upper edge of each of the four corners, the leading notch assists in the initiation of tearing, making it easier to break.

[0054] In a fourth aspect, in any one of the first to third aspects, the pair of second side walls are provided with four break lines (L18-L21) along the vertical ridges at the four corners, and a pair of other planned fold lines (L14, L16) that cross the second side walls are provided. According to this configuration, the second side walls are folded along the other planned fold lines to adjust the height dimension of the second side walls.

[0055] The fifth aspect is any one of the first to fourth aspects, in which a joint is interposed between the direction change points of the multiple intermediate incisions (L31b), and the joint between the direction change points of the multiple intermediate incisions is located on the first side wall (35b) or the longitudinal ridge. With this configuration, even when the sheet is folded, the first and second side walls are connected by the joint between the direction change points of the multiple intermediate incisions. Therefore, the direction change points of the multiple intermediate incisions do not protrude convexly from the longitudinal ridge between the first and second side walls.

[0056] In a sixth aspect, in any one of the first to fifth aspects, the plurality of intermediate notches are formed non-parallel to the longitudinal ridges. With this configuration, the break line has almost no portion parallel to the longitudinal ridges, so that the folding accuracy of the fold line is not deteriorated by folding along the break line instead of the fold line between the first and second side walls.

[0057] The seventh aspect is any one of the first to sixth aspects, and further includes a pair of flaps (inner lid flaps 15a, 15b) connected to the upper edges of the pair of first side walls via a fold line. With this configuration, the flaps are folded against the first side walls, and the first side walls and the flaps are pressed together as an L-shaped structure, making the first side walls less likely to bend concavely even when subjected to a pressing force. The pressing force against the first side walls is smoothly transmitted to the breaking line of the second side walls, making them more likely to break.

[0058] An eighth aspect is a sheet material (5) formed so that the packaging box of any one of the first to seventh aspects can be assembled. According to this configuration, a packaging box that is easy to adjust in height and can prevent surface cracks can be assembled from the sheet material.

[0059] Although the present embodiment has been described, other embodiments may be obtained by combining the above-described embodiments and modifications in whole or in part.

[0060] Furthermore, the technology of the present invention is not limited to the above-described embodiments, and may be variously modified, substituted, or altered within the scope of the spirit of the technical idea. Furthermore, if the technical idea can be realized in a different way due to technological advances or other derived technologies, it may be implemented using that method. Therefore, the claims cover all embodiments that may fall within the scope of the technical idea. [Explanation of symbols]

[0061] 1: Packaging box 3: Longitudinal ridge 5: Sheet material 11a, 11b: Short wall (first side wall) 12a, 12b: Long walls (second side walls) 15a, 15b: Inner flap of the lid (flap) C: Connection L14, L16: planned bending lines L15, L17: Planned bending lines (other planned bending lines) L18-L21: Break line L18a-L21a: Leading cut L18b-L21b: Intermediate depth of cut L18c-L21c: Final cutting depth

Claims

1. A packaging box (1) whose height dimension can be adjusted by breaking along the vertical edges (3) at the four corners, a pair of first side walls (11a, 11b) positioned between the vertical ridges of the four corners and facing each other in a first direction; a pair of second side walls (12a, 12b) positioned between the vertical ridges at the four corners and facing each other in a second direction; A pair of break lines (L18, L21) are provided along the longitudinal ridge on at least one of the first side walls in the pair of second side walls, The pair of breaking lines has a plurality of intermediate notches (L18b, L21b) arranged in the opening direction with the joint (C) in between, The plurality of intermediate notches start at positions spaced a predetermined distance from the vertical ridge, extend toward the vertical ridge as they proceed downstream in the opening direction from the start point, and then change direction and extend in a direction away from the vertical ridge, A packaging box characterized in that the starting point of the intermediate slit downstream in the opening direction is located in the extension direction after the direction of the intermediate slit upstream in the opening direction is changed.

2. A planned folding line (L17) that crosses the first side wall is provided on the at least one first side wall, The pair of breaking lines have final notches (L18c, L21c) located downstream in the opening direction from the most downstream intermediate notch in the opening direction across the joint, 2. The packaging box according to claim 1, wherein the final cut extends toward the intended fold line as it proceeds downstream in the opening direction from the starting point, and the starting point of the final cut is located in the extension direction after the direction of the most downstream intermediate cut in the opening direction is changed.

3. The pair of breaking lines have leading notches (L18a, L21a) located upstream in the opening direction from the most upstream intermediate notch in the opening direction across the joint, 2. The packaging box according to claim 1, wherein the leading notch extends from the upper edge of the four corners so as to move away from the vertical ridge as it proceeds downstream in the opening direction, and the starting point of the intermediate notch located most upstream in the opening direction is located in the extension direction of the leading notch.

4. The packaging box according to claim 2, characterized in that four break lines (L18-L21) are provided along the vertical edges of the four corners of the pair of second side walls, and a pair of other planned fold lines (L14, L16) are provided that cross the second side walls.

5. The packaging box according to claim 1, characterized in that a joint is interposed at the change of direction of the plurality of intermediate notches (L31b), and the joint of the change of direction of the plurality of intermediate notches is located on the first side wall (35b) or the vertical ridge.

6. 2. The packaging box according to claim 1, wherein the plurality of intermediate notches are formed non-parallel to the longitudinal ridges.

7. 2. The packaging box according to claim 1, further comprising a pair of flaps (15a, 15b) connected to upper edges of the pair of first side walls via folding lines.

8. A sheet material formed so as to be able to assemble the packaging box according to any one of claims 1 to 7.

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