Packaging box, blank, and method for sealing packaging box

Abstract

A corrugated cardboard packaging box (1) includes a cylindrical body (3) with a closed bottom face, and can be broken along the vertical ridge lines (L1) of the cylindrical body (3) to thereby change the height of the cylindrical body (3) in accordance with the height of an object (90) to be accommodated therein. The cylindrical body (3) has cut lines (21) that are cut along the vertical ridge lines (L1) at corners of an opening part (4) of a top surface. The vertical ridge lines (L1) are portions excluding lead lines on which perforations are formed. The cut lines (21) are formed above positions at which the maximum height (H1) of the packaging box (1) after sealing is obtained. The compression-to-failure ratio (Z [mN / (m·Pa)]) of a corrugated cardboard sheet constituting the cylindrical body 3, which is a ratio of the vertical compression strength (Y [kN / m]) of the corrugated cardboard sheet to the burst strength (X [kPa]) of the corrugated cardboard sheet, is 3.9 [mN / (m·Pa)] or more.

Description

Packaging box, blank, and method for sealing a packaging box

[0001] The present invention relates to a cardboard packaging box, a blank, and a method for sealing the packaging box, in which the height of a cylindrical body is changed according to the height of an object to be accommodated by a packaging device.

[0002] A box body (box sheet) is known in which a pair of first side panels and a pair of second side panels form a square tube-shaped body, and a plurality of intermediate folding easy lines that cross the pair of first side panels and the pair of second side panels are formed at intervals in the vertical direction. At the boundary between the first side panel and the second side panel, a vertical break easy line (perforation) connecting the upper edge of the body and the plurality of intermediate folding easy lines is formed. By breaking the body along the vertical break easy line to an arbitrary intermediate folding easy line and folding the upper parts of the broken first to second side panels along the intermediate folding easy line, the height of the box body can be changed.

[0003] Utility Model Registration No. 3244633

[0004] In the above-described box body, for example, when the body is broken along the vertical break easy line to the uppermost intermediate folding easy line and the upper parts of the first to second side panels are folded at the uppermost intermediate folding easy line, other intermediate folding easy lines except the uppermost intermediate folding easy line remain on the first to second side panels. Then, since the first to second side panels are easily bent along the other intermediate folding easy lines, there is a problem that the compressive strength of the box body decreases in the sealed state.

[0005] In view of the above circumstances, the present invention provides a packaging box, a blank, and a method for sealing the packaging box that can suppress a decrease in compressive strength.

[0006] The present invention relates to a corrugated cardboard packaging box that includes a cylindrical body with a closed bottom, and whose height can be changed according to the height of the contents by breaking along the longitudinal ridge of the cylindrical body, wherein the cylindrical body has a cut line cut along the longitudinal ridge at the corner of the opening of the top surface, the longitudinal ridge is excluding the lead crease that forms the perforation, the cut line is formed above the position that will result in the maximum height of the packaging box after sealing, and the crushing ratio of the corrugated cardboard sheet [mN / (m·Pa)], which is the ratio of the vertical compressive strength [kN / m] of the corrugated cardboard sheet to the bursting strength [kPa] of the corrugated cardboard sheet constituting the cylindrical body, is 3.9 [mN / (m·Pa)] or more.

[0007] The blank of the present invention forms the packaging box described above.

[0008] The present invention relates to a method for sealing a cardboard packaging box, which includes a cylindrical body with a closed bottom, wherein the packaging device changes the height of the cylindrical body according to the height of the contents contained in the packaging box, and the packaging device comprises: a scoring section that forms a horizontal fold line on the wall of the cylindrical body through an opening on the top surface of the cylindrical body according to the height of the contents contained inside the cylindrical body, and divides the wall into a side wall and an upper flap; and a dividing section that presses a non-sharp plate-shaped blade against the corner of the opening and lowers it along the vertical ridge from the upper end of the vertical ridge of the cylindrical body to the horizontal fold line, thereby dividing the upper flap which is connected via the vertical ridge, and the cylindrical body is cut along the vertical ridge at the corner of the opening The packaging has a cut line, the vertical ridge is excluding the lead crease that forms the perforation, the cut line is formed above the position that will be the maximum height of the packaging box after sealing, the crushing ratio of the corrugated cardboard sheet [mN / (m·Pa)], which is the ratio of the vertical compressive strength [kN / m] of the corrugated cardboard sheet to the bursting strength [kPa] of the corrugated cardboard sheet constituting the cylindrical body, is 3.9 [mN / (m·Pa)] or more, and comprises a creasing step in which the creasing section forms the horizontal fold line on the wall of the cylindrical body and divides the wall into the side wall and the upper flap, and a cutting step in which the cutting section cuts the upper flap connected via the vertical ridge by lowering the blade from the upper end of the vertical ridge to the horizontal fold line.

[0009] According to the present invention, it is possible to suppress the decrease in the compressive strength of the packaging box.

[0010] This is a schematic side view showing a packaging device according to one embodiment of the present invention. This is a plan view showing a blank packaging box according to the first embodiment of the present invention. This is a perspective view showing a temporarily assembled packaging box according to the first embodiment of the present invention. This is a plan view showing the creasing portion of the packaging box and packaging device according to the first embodiment of the present invention. This is a perspective view showing a part of the creasing portion of the packaging device according to one embodiment of the present invention. This is a plan view showing the dividing portion of the packaging box and packaging device according to the first embodiment of the present invention. This is a perspective view showing a part of the dividing portion of the packaging device according to one embodiment of the present invention. This is a perspective view showing a packaging box according to the first embodiment of the present invention in a state in which a third fold curve has been formed. This is a side view illustrating the dividing process by the packaging device according to one embodiment of the present invention. This is a side view showing the state in which the dividing process by the packaging device according to one embodiment of the present invention has been completed. This is a plan view showing the state in which the dividing process by the packaging device according to one embodiment of the present invention has been completed. This is a perspective view showing the sealed state (maximum height) of the packaging box according to the first embodiment of the present invention. This is a perspective view showing the sealed state (minimum height) of the packaging box according to the first embodiment of the present invention. This is a plan view showing a blank packaging box according to a first modified example of the first embodiment of the present invention. This is a plan view showing a blank packaging box according to a second modified example of the first embodiment of the present invention. This is a plan view showing a blank packaging box according to a third modification of the first embodiment of the present invention. This is a plan view showing a blank packaging box according to a fourth modification of the first embodiment of the present invention. This is a plan view showing a blank packaging box according to a fifth modification of the first embodiment of the present invention. This is a perspective view showing a test cylinder used in a test to verify the effectiveness of the crushing ratio set for the corrugated cardboard sheet constituting the packaging box according to the first embodiment of the present invention. This is a chart showing the results of a test to verify the effectiveness of the crushing ratio set for the corrugated cardboard sheet constituting the packaging box according to the first embodiment of the present invention. This is a plan view showing a blank packaging box according to the second embodiment of the present invention. This is a perspective view showing the packaging box according to the second embodiment of the present invention in a temporarily assembled state. This is a side view showing the packaging box and the blade of the packaging device according to the second embodiment of the present invention. This is a perspective view showing how the groove formed in the packaging box (cylinder) widens from top to bottom.

[0011] Embodiments of the present invention will be described below with reference to the attached drawings. In the drawings, Fr, Rr, L, R, U, and D indicate front, back, left, right, top, and bottom. The front-to-back, left-to-right, and up-to-down directions are orthogonal to each other. While this specification uses terms to indicate direction and position, these terms are used for convenience of explanation and do not limit the technical scope of the present invention. Furthermore, the terms indicating direction and position are based on the direction and position when the packaging device is in use.

[0012] Referring to Figures 1 to 3, a packaging box 1 and a packaging device 5 for sealing the packaging box 1 according to the first embodiment will be described. Figure 1 is a schematic side view showing the packaging device 5. Figure 2 is a top view showing the blank 1A of the packaging box 1. Figure 3 is a perspective view showing the packaging box 1 in a temporarily assembled state.

[0013] The packaging device 5 is a device for packaging contents 90 in a cardboard packaging box 1. When packaging contents 90 in one type of packaging box 1, the packaging device 5 has a function to change the height of the packaging box 1 according to the height of the contents 90. In other words, the packaging device 5 can package (package) contents 90 of different heights in one type of packaging box 1. Furthermore, the packaging device 5 can also package contents 90 in two or more types of packaging boxes 1 with different bottom (or top) area (footprint) by changing the height of each packaging box 1.

[0014] [First Embodiment: Packaging Box] A packaging box 1 in which the height of the cylindrical body 3 is changed according to the height of the contents 90 by a packaging device 5 will be described. The packaging box 1 is formed from a blank 1A shown in Figure 2. The blank 1A is formed by punching out a sheet of corrugated cardboard using a die or the like. The corrugated cardboard is, for example, double-sided corrugated cardboard in which a front liner 9B (front surface) and a back liner 9C (back surface) are laminated to a corrugated core 9A. In this specification, the direction parallel to the core 9A of the corrugated cardboard is called the "corrugation direction," and the direction perpendicular to the corrugation direction is called the "flow direction." In the drawings, "X" indicates the "corrugation direction," and "Y" indicates the "flow direction." Also in this specification, when the front liner 9B and the back liner 9C are described together, they may simply be called "liners 9B, 9C."

[0015] [Blank] As shown in Figure 2, Blank 1A has a pair of first base walls 10, a pair of second base walls 11, a pair of lower inner flaps 13, and a pair of lower outer flaps 14. Since the pair of first base walls 10 (wall portions) are substantially the same shape, this specification will mainly describe one first base wall 10. For the same reason, this specification will mainly describe one second base wall 11 (wall portion), one lower inner flap 13, and one lower outer flap 14. Also, in this specification, when the first base walls 10 and the second base walls 11 are described together, they may simply be referred to as "base walls 10, 11". The dashed lines shown in Figure 2 and Figures 14 to 18 described later are hypothetical lines shown to illustrate the maximum height (H1) and minimum height (H2) of the packaging box 1.

[0016] <First and Second Foundation Walls> The first foundation wall 10 is formed in a roughly rectangular shape with the step direction as the longer side. The second foundation wall 11 has the same dimensions as the first foundation wall 10 in the step direction and is formed in a roughly rectangular shape with the flow direction as the longer side. The pair of first foundation walls 10 and the pair of second foundation walls 11 are arranged alternately in the flow direction and connected via a first bend curve L1 (vertical ridge line (e.g., general-purpose ruled line)). A connecting piece 12 is connected to one end of the second foundation wall 11 in the flow direction via the first bend curve L1. As will be described in detail later, the pair of first foundation walls 10 and the pair of second foundation walls 11 are connected in a rectangular tubular shape via the connecting piece 12 to form a cylindrical body 3 (see Figure 3).

[0017] (Notches) At one end (upper end) of the blank 1A in the step direction, notches 20 are recessed at the corners of the foundation walls 10 and 11 at both ends in the flow direction, and at the boundary between the first foundation wall 10 and the second foundation wall 11 (first bend curve L1). The notches 20 are cut out in a shape that gradually narrows from one end (upper end) in the step direction of the foundation walls 10 and 11 to the other end (downward). Specifically, the notches 20 are formed in a generally V-shape. A portion of the notch 20 formed in the first foundation wall 10 is cut out to be wider in the flow direction than the other portion of the notch 20 formed in the second foundation wall 11. The angle (α) between the hypotenuse of the notch 20 formed in the first foundation wall 10 and the extension of the first bent curve L1 is greater than the angle (β) between the hypotenuse of the notch 20 formed in the second foundation wall 11 and its extension.

[0018] The notch portion 20 is not formed in a perfect V-shape with a bend at a single point at its lower end, but rather, more precisely, it is formed in a bathtub shape (inverted trapezoidal shape) with one side extending in the flow direction at its lower end. The width (dimension in the flow direction) of the lower end of the notch portion 20 is set to be between 4 mm and 10 mm. The notches 20 formed at the corners of the foundation walls 10 and 11 at both ends in the flow direction are shaped like two halves of the other notches 20, and when the cylindrical body 3 is formed, they become substantially the same shape as the other notches 20. Alternatively, the notch portion 20 may be formed in a V-shape with a bend at a single point at its lower end (not shown).

[0019] (Cutting line) Near one end (near the top end) of the first fold curve L1 in the direction of the corrugation, a cutting line 21 is cut along the first fold curve L1 (vertical ridge). The cutting line 21 is cut downward from the lower end (the other end in the direction of the corrugation) of the notch 20. The cutting line 21 is formed between the lower end of the notch 20 and the upper end of the first fold curve L1. The cutting line 21 is a single cut made by passing a blade through the corrugated cardboard in the thickness direction. The length of the cutting line 21 should be set in the range of 3 mm or more and 20 mm or less. Note that the cutting line 21 is formed above the position of the maximum height (H1) of the packaging box 1. Furthermore, the combined length (height) of the notch 20 and the cut line 21 in the step direction should be set to be shorter than 3 / 4 of the distance (H4) obtained by subtracting the maximum height (H3) of the contents 90 from the height (H0) of the foundation walls 10, 11 (see Figure 8, described later). Preferably, the combined height of the notch 20 and the cut line 21 may be set to about half of the said distance (H4).

[0020] <Lower Inner Flap, Lower Outer Flap> The lower inner flap 13 is connected to the other end (lower end) of the first foundation wall 10 in the step direction via a second bend curve L2 (for example, a general-purpose ruled line). The lower inner flap 13 has approximately the same dimensions as the first foundation wall 10 in the flow direction and is formed in a roughly rectangular shape with the flow direction as the longer side. The step direction dimension (extension dimension) of the lower inner flap 13 is approximately half the flow direction dimension of the first foundation wall 10. The lower outer flap 14 is connected to the other end (lower end) of the second foundation wall 11 in the step direction via a second bend curve L2. The lower outer flap 14 has approximately the same dimensions as the second foundation wall 11 in the flow direction and is formed in a roughly rectangular shape with the flow direction as the longer side. The step direction dimension (extension dimension) of the lower outer flap 14 is the same as the extension dimension of the lower inner flap 13.

[0021] The first fold line L1 and the second fold line L2 were general-purpose creases, but the design is not limited to these. Any structure that allows the corrugated cardboard sheet to be folded in the desired direction is acceptable, such as a lead crease with perforations formed on a general-purpose crease.

[0022] [Initial state of the packaging box] Although not shown in the diagram, a flatly folded packaging box 1 is formed from a blank 1A. Specifically, the first base wall 10 and the second base wall 11 located on both sides of the blank 1A in the flow direction are folded inward by approximately 180 degrees along the first fold line L1, and the connecting piece 12 is adhered to the back surface (back liner 9C) of the first base wall 10 on the opposite side. As a result, the packaging box 1 is in its initial state of being double-folded.

[0023] [Temporary assembly of the packaging box] The packaging box 1 in its initial state is temporarily assembled in order to contain the contents 90 and package (seal) them with the packaging device 5. Specifically, as shown in Figure 3, the packaging box 1 in its initial state is raised so that a pair of first base walls 10 and a pair of second base walls 11 are approximately perpendicular to each other. The pair of first base walls 10 and the pair of second base walls 11 form a rectangular cylindrical body 3 with open upper and lower end faces (not shown).

[0024] Next, the lower inner flap 13 is folded inward at approximately a right angle along the second fold line L2, and then the lower outer flap 14 is folded inward at approximately a right angle along the second fold line L2. The pair of lower inner flaps 13 are spaced apart at their tips, and the pair of lower outer flaps 14 are butted together at their tips and stacked on the surface of the pair of lower inner flaps 13. Adhesive tape T is applied to the butted portion of the pair of lower outer flaps 14. The lower inner flaps 13 and lower outer flaps 14 form the bottom that closes the bottom surface of the cylindrical body 3.

[0025] As a result, the packaging box 1 is in a provisionally assembled state. In the provisionally assembled packaging box 1, the bottom surface of the cylindrical body 3 is closed, and an opening 4 is open on the top surface of the cylindrical body 3. The notch 20 is formed in a V-shape, narrowing downwards from the upper edge of the corner of the opening 4. The cut line 21 is cut along the first fold line L1 at the corner of the opening 4 (notch 20). The packaging box 1, with the contents 90 inside, is introduced into the packaging device 5 (see Figure 1).

[0026] [Packaging Device] Next, the packaging device 5 will be described with reference to Figures 1, 4 to 7. Figure 4 is a plan view showing the packaging box 1 and the creasing section 31. Figure 5 is a perspective view showing a part of the creasing section 31. Figure 6 is a plan view showing the packaging box 1 and the dividing section 32. Figure 7 is a perspective view showing a part of the dividing section 32.

[0027] As shown in Figure 1, the packaging device 5 includes a height measuring section 30, a creasing section 31, a dividing section 32, a folding section 33, and a sealing section 34. The packaging device 5 also includes a conveyor 35 for intermittently transporting the packaging box 1. The packaging device 5 also includes a control unit 36 ​​for appropriately controlling each section 30-34 and the conveyor 35. The height measuring section 30, creasing section 31, dividing section 32, folding section 33, and sealing section 34 are arranged in this order in a line from upstream to downstream in the transport direction of the packaging box 1. The conveyor 35 is laid over the entire area of ​​the height measuring section 30, creasing section 31, dividing section 32, folding section 33, and sealing section 34. In this specification, the terms "upstream" and "downstream" refer to the upstream or downstream in the transport direction of the packaging box 1.

[0028] <Height Measurement Unit> The height measurement unit 30 measures the height of the contents 90 housed inside the cylindrical body 3 (temporarily assembled packaging box 1) through the opening 4 on the top surface of the cylindrical body 3. As shown in Figure 1, the height measurement unit 30 has a laser light source 30A that emits a strip-shaped laser beam onto the contents 90 and a light-receiving element 30B that receives the reflected light reflected from the surface of the contents 90, and measures the height (shape) of the contents 90 using the principle of the light section method. The height measurement unit 30 is electrically connected to the control unit 36 ​​and is driven and controlled by the control unit 36. The light-receiving information from the light-receiving element 30B (measurement result of the height measurement unit 30) is transmitted to the control unit 36.

[0029] <Ruled Section> The ruled section 31 forms a third fold line L3 (horizontal fold line) on the base walls 10, 11 (wall sections) of the cylindrical body 3 according to the height of the contents 90 (see Figure 8, described later). The ruled section 31 has a first ruled section 40 that forms the third fold line L3 on a pair of first base walls 10 that are on the short side of the opening 4, and a second ruled section 50 that forms the third fold line L3 on a pair of second base walls 11 that are on the long side of the opening 4. The second ruled section 50 is located downstream of the first ruled section 40 (see Figure 1).

[0030] <First Scratching Section> As shown in Figure 1, the first scratching section 40 has two pairs of first arms 41, a first drive unit 42, and a pair of first roller sections 43. Since the two pairs of first arms 41, which are provided corresponding to the pair of first foundation walls 10, have substantially the same structure, this specification will mainly describe the pair of first arms 41. Also, since the pair of first roller sections 43 have substantially the same structure, this specification will mainly describe one of the first roller sections 43.

[0031] (First Arm, First Drive Unit) The pair of first arms 41 are each suspended substantially vertically from the first drive unit 42. The pair of first arms 41 are spaced apart from each other in the front-rear direction (conveying direction) and are substantially parallel to each other. The first drive unit 42 raises and lowers the entire pair of first arms 41, and also moves them in the front-rear direction and the left-right direction (width direction perpendicular to the conveying direction). The first drive unit 42 also moves the pair of first arms 41 closer together and further apart. The first drive unit 42 is electrically connected to the control unit 36 ​​and is driven and controlled by the control unit 36. As will be described in detail later, when the first drive unit 42 lowers the pair of first arms 41 toward the temporarily assembled packaging box 1, the first base wall 10 enters relatively between the pair of first arms 41, and the pair of first arms 41 face each other with the first base wall 10 in between.

[0032] (First Roller Section) As shown in Figures 4 and 5, the first roller section 43 has a pair of first outer rollers 44 and a first inner roller 45. The first outer rollers 44 and the first inner roller 45 are formed in a substantially cylindrical (substantially disc-shaped) form. The pair of first outer rollers 44 are attached via a first bracket 46 to the lower end of the outer first arm 41 of a pair of first arms 41 that sandwich the first base wall 10. The pair of first outer rollers 44 are arranged side by side with a gap between them in the left-right direction (lateral direction along the third bend curve L3) and are supported by the first bracket 46 so as to be rotatable around an axis. The first inner roller 45 is attached via a first bracket 46 to the lower end of the inner first arm 41 of a pair of first arms 41 that sandwich the first base wall 10. The first inner roller 45 is arranged to face the pair of first outer rollers 44 and is supported by the first bracket 46 so as to be rotatable around an axis.

[0033] <Second Scratching Section> As shown in Figure 1, the second scratching section 50 has two pairs of second arms 51, a second drive unit 52, and a pair of second roller sections 53. Since the two pairs of second arms 51, which are provided corresponding to the pair of second foundation walls 11, have substantially the same structure, this specification will mainly describe the pair of second arms 51. Also, since the pair of second roller sections 53 have substantially the same structure, this specification will mainly describe one of the second roller sections 53. Furthermore, in Figure 1, only the left second arm 51 and the left second roller section 53 are shown. Also, since the second roller section 53 etc. have generally the same structure as the first roller section 43 etc., the second roller section 53 etc. will be described by referring to Figure 5, which was used to describe the first roller section 43 etc.

[0034] (Second Arm, Second Drive Unit) The pair of second arms 51 are each suspended approximately vertically from the second drive unit 52. The pair of second arms 51 are spaced apart from each other in the left-right direction and are approximately parallel to each other. The second drive unit 52 raises and lowers the entire pair of second arms 51, and also moves them in the front-back and left-right directions. The second drive unit 52 also moves the pair of second arms 51 closer together and further apart. The second drive unit 52 is electrically connected to the control unit 36 ​​and is driven and controlled by the control unit 36. As will be described in detail later, when the second drive unit 52 lowers the pair of second arms 51 toward the temporarily assembled packaging box 1, the second base wall 11 enters relatively between the pair of second arms 51, and the pair of second arms 51 face each other with the second base wall 11 in between.

[0035] (Second Roller Section) As shown in Figures 4 and 5, the second roller section 53 has a pair of second outer rollers 54 and a second inner roller 55. The second outer rollers 54 and the second inner roller 55 are formed in a substantially cylindrical (substantially disc-shaped) form. The pair of second outer rollers 54 are attached via a second bracket 56 to the lower end of the outer second arm 51 of a pair of second arms 51 that sandwich the second base wall 11. The pair of second outer rollers 54 are arranged side by side with a gap in the front-rear direction (lateral direction along the third bend curve L3) and are supported by the second bracket 56 so as to be rotatable around an axis. The second inner roller 55 is attached via a second bracket 56 to the lower end of the inner second arm 51 of a pair of second arms 51 that sandwich the second base wall 11. The second inner roller 55 is arranged to face the pair of second outer rollers 54 and is supported by the second bracket 56 so as to be rotatable around an axis.

[0036] (Details of the outer and inner rollers) The first roller section 43 and the second roller section 53 will be described in detail with reference to Figures 4 and 5. In this specification, when the first roller section 43 and the second roller section 53 are described together, they are simply referred to as "roller sections 43, 53," when the first outer roller 44 and the second outer roller 54 are described together, they are simply referred to as "outer rollers 44, 54," and when the first inner roller 45 and the second inner roller 55 are described together, they are simply referred to as "inner rollers 45, 55."

[0037] The outer rollers 44, 54 and inner rollers 45, 55 are made of metal, such as carbon steel, and are all formed to the same shape. The outer rollers 44, 54 and inner rollers 45, 55 are formed in a roughly circular disc shape with a diameter of 20 mm. Each of the outer rollers 44, 54 and inner rollers 45, 55 has a roughly trapezoidal projection outward in the radial direction. The distance (center distance) between a pair of first outer rollers 44 and the distance (center distance) between a pair of second outer rollers 54 are each approximately 20 mm, the same as their diameter. The diameters of the outer rollers 44, 54 and the inner rollers 45, 55 should be set within the range of 5 mm to 60 mm. The distance between a pair of outer rollers 44, 54 should be changed to match the diameter of the pair of outer rollers 44, 54. The outer rollers 44, 54 and the inner rollers 45, 55 may have different diameters.

[0038] Furthermore, the inner rollers 45 and 55 are positioned opposite the outer rollers 44 and 54 at a position offset downward from the outer rollers 44 and 54. Specifically, the inner rollers 45 and 55 (center of thickness) are positioned approximately 2 mm lower than the outer rollers 44 and 54 (center of thickness). The amount of offset between the inner rollers 45 and 55 and the outer rollers 44 and 54 should be set within the range of, for example, 0 mm to 6 mm (thickness of the protruding parts of the inner rollers 45 and 55).

[0039] As shown in Figure 4, the rollers 43 and 53 of the creasing section 31 sandwich the base walls 10 and 11 of the cylindrical body 3 and roll along both the front and back surfaces of the base walls 10 and 11, moving laterally (see the thick arrows shown in Figure 4) to form a third fold curve L3. The first roller section 43 forms the third fold curve L3 on a pair of first base walls 10 that are opposite each other in the front-to-back direction (first direction) when viewing the cylindrical body 3 from a plane. The second roller section 53 forms the third fold curve L3 on a pair of second base walls 11 that are opposite each other in the left-to-right direction (second direction perpendicular to the first direction) when viewing the cylindrical body 3 from a plane. The outer rollers 44 and 54 rotate around their axes while their protruding portions are pressed against the surfaces of the base walls 10 and 11. The inner rollers 45 and 55 rotate around their axes while their protruding portions are pressed against the back surfaces of the base walls 10 and 11. The inner rollers 45 and 55 are positioned to contact a pair of outer rollers 44 and 54, with the base walls 10 and 11 in between. The third fold line L3 is the line created by crushing (indenting) the base walls 10 and 11 (corrugated cardboard) in the thickness direction from both the front and back sides. More specifically, the indentation on the back side (back liner 9C) of the base walls 10 and 11 is located slightly below the indentation on the front side (front liner 9B) of the base walls 10 and 11.

[0040] As will be described in detail later, the first base wall 10 is divided into a first side wall 15 and an upper inner flap 16 by a third fold curve L3, and the second base wall 11 is divided into a second side wall 17 and an upper outer flap 18 by a third fold curve L3 (see Figure 8, described later). The pair of first side walls 15 and the pair of second side walls 17 are alternately connected via a first fold curve L1, and the pair of upper inner flaps 16 and the pair of upper outer flaps 18 are also alternately connected via the first fold curve L1. In this specification, when the first side walls 15 and the second side walls 17 are described together, they are simply referred to as "side walls 15, 17," and when the upper inner flap 16 and the upper outer flap 18 are described together, they are simply referred to as "upper flaps 16, 18."

[0041] <Separation Section> The separation section 32 cuts the cylindrical body 3 along the first fold line L1 (vertical ridge) from the four corners of the opening 4 of the temporarily assembled packaging box 1. As shown in Figures 1 and 6, the separation section 32 has four separation arms 61, a separation drive unit 62, four blades 63, and eight guide rollers 64. Since the four separation arms 61 and four blades 63 are provided corresponding to the four corners of the opening 4, this specification will mainly describe one separation arm 61 and one blade 63 corresponding to one corner. Also, since the eight guide rollers 64 are provided corresponding to the four corners of the opening 4, this specification will mainly describe two guide rollers 64 corresponding to one corner.

[0042] (Dividing Arms, Dividing Drive Unit) As shown in Figure 1, the dividing arms 61 are suspended approximately vertically from the dividing drive unit 62. The four dividing arms 61 are arranged so as viewed from above, facing the outside of the four corners of the opening 4 (see Figure 6). The dividing drive unit 62 raises and lowers the entire set of four dividing arms 61 and moves them in a direction (radial direction RD) along the line that bisects the corners (approximately right angles) of the cylindrical body 3 as viewed from above. The dividing drive unit 62 is electrically connected to the control unit 36 ​​and is driven and controlled by the control unit 36. The "radial direction RD" is the direction inclined at approximately 45 degrees with respect to the first base wall 10 and the second base wall 11 of the packaging box 1 (cylindrical body 3) as viewed from above (see Figure 6).

[0043] (Blade) As shown in FIGS. 6 and 7, one end of the blade 63 is fixed to the dividing arm 61. The blade 63 is made of a synthetic resin such as monomer cast nylon, and is formed in a generally rectangular plate shape with a thickness of about 5 mm. That is, the blade 63 is formed in a non-sharp plate shape. Here, the fact that the blade 63 is "non-sharp" refers to a dull state (aspect) such that it cannot cut (move while cutting) a cardboard sheet (the material constituting the packaging box 1). The four blades 63 are inclined along the radial direction RD as viewed from the plane (see FIG. 6), and are provided in an inclined posture that slopes downward from the outside to the inside of the cylindrical body 3 as viewed from the side (front and side) (see FIG. 7). That is, the four blades 63 extend obliquely downward from the four dividing arms 61 toward the inside. On the tip side of the blade 63, a drawing auxiliary surface 63A that becomes a substantially vertical surface by cutting off the upper corner is formed (see FIG. 7). On the lower side of the blade 63, a tapered portion 63B that gradually becomes thinner toward the lower end (the packaging box 1) is formed (see FIG. 7). The tip (lower end) of the tapered portion 63B is not sharp and has a slight thickness. The blade 63 is in an inclined posture with the tapered portion 63B facing downward (the packaging box 1).

[0044] Details will be described later. The dividing portion 32 presses the blade 63 against the corner of the opening 4 of the cylindrical body 3, and descends along the first bending line L1 from the upper end to the third bending line L3 of the first bending line L1 (vertical ridge line) of the cylindrical body 3, thereby dividing the upper flaps 16 and 18 connected via the first bending line L1. In this specification, "breaking" means that something integral is cut off. Specifically, it means that the core 9A and the liners 9B and 9C of the cardboard are torn (ripped). "Dividing" means cutting off something integral and separating it separately. Specifically, it means that the cardboard (the upper flaps 16 and 18) is torn (ripped) and separated. In other words, in this specification, "breaking" and "dividing" do not mean that a sharp blade or the like cuts (moves while cutting) the cardboard, but rather mean tearing while locally destroying something integral.

[0045] (Guide Rollers) As shown in Figures 6 and 7, two guide rollers 64 are attached to the lower part of the dividing arm 61 via a roller arm 65. The guide rollers 64 are supported by the roller arm 65 so as to be rotatable around an axis, at a position below the blade 63. The guide rollers 64 are made of synthetic resin such as monomer cast nylon and are formed in a substantially cylindrical (subclavian) shape. The two guide rollers 64 are supported in a direction in which their axes of rotation are perpendicular to each other. As the blade 63 is lowered, the two guide rollers 64 rotate while contacting the surfaces of the upper flaps 16 and 18 which are connected via a first bend curve L1 (see Figure 6).

[0046] <Folding Section> As shown in Figure 1, the folding section 33 includes a pair of inner folding arms 70 that fold a pair of upper inner flaps 16 along a third folding curve L3, an outer folding arm 71 that folds one of a pair of upper outer flaps 18 along the third folding curve L3, and a folding drive unit 72 that drives the inner folding arms 70 and the outer folding arm 71. The folding drive unit 72 is electrically connected to the control unit 36 ​​and is driven and controlled by the control unit 36.

[0047] <Sealing section> The sealing section 34 includes a sealing folding arm 80 that folds one of a pair of upper outer flaps 18 along a third folding curve L3, an adhesive tape T that is attached to the other upper outer flap 18 to fix it to the other upper outer flap 18, and a sealing drive section 82 that drives the sealing folding arm 80 and the adhesive section 81. The sealing drive section 82 is electrically connected to the control unit 36 ​​and is driven and controlled by the control unit 36.

[0048] <Conveyor>The conveyor 35 has a plurality of rollers (not shown) arranged side by side in the conveying direction. Each roller is supported by a frame (not shown) so as to be rotatable about its axis. Each roller is connected to a drive source such as an electric motor via a drive transmission mechanism such as a gear or a belt (none of them are shown). When each roller is rotationally driven about its axis, the packaging box 1 moves to the downstream side in the conveying direction. Further, the conveyor 35 is provided with a plurality of positioning and holding portions (not shown) for holding the conveyed packaging box 1 at a predetermined position set so that the operations at each of the portions 30 to 34 are properly executed. The drive source and the positioning and holding portions are electrically connected to the control unit 36 and are drive-controlled by the control unit 36.

[0049] <Control Unit>The control unit 36 has a storage unit that stores programs, data, etc., an arithmetic processing unit that executes arithmetic processing according to programs, etc., and a communication unit that is communicably connected to each of the portions 30 to 34 and the conveyor 35. The storage unit, the arithmetic processing unit, and the communication unit are electrically connected to each other and are configured to be communicable with each other. The storage unit includes, for example, a storage medium such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and the arithmetic processing unit includes, for example, a CPU (Central Processing Unit). Note that the control unit 36 may include an operation terminal (not shown) for an operator to input various operations or confirm the output results from the control unit 36. Further, it is preferable that the storage unit stores in advance data on the dimensions (length, width, height, etc.) of the temporarily assembled packaging box 1 and various parameters necessary for control. Further, the control unit may be realized by a logic circuit (hardware) formed in an integrated circuit or the like instead of the CPU.

[0050] As an example of the first drive unit 42, second drive unit 52, disassembly drive unit 62, folding drive unit 72, and sealing drive unit 82, actuators such as electric motors, servo motors, linear motors, solenoids, and piston-cylinders can be employed. Furthermore, the first drive unit 42, second drive unit 52, disassembly drive unit 62, folding drive unit 72, and sealing drive unit 82 may include drive transmission mechanisms such as gears and pulleys (belts) that transmit power from the actuators to the object to be driven (not shown). In addition, these drive units 42, 52, 62, 72, 82 and the control unit 36 ​​are connected to a power supply means (not shown).

[0051] [Operation of the Packaging Device] Next, the operation of the packaging device 5 (method of sealing the packaging box 1) will be described with reference to Figures 1, 4, 6, 8 to 13. Figure 8 is a perspective view showing the packaging box 1 with the third fold curve L3 formed. Figure 9 is a side view illustrating the cutting process. Figure 10 is a side view showing the state after the cutting process is completed. Figure 11 is a top view showing the state after the cutting process is completed. Figure 12 is a perspective view showing the sealed packaging box 1 (maximum height (H1)). Figure 13 is a perspective view showing the sealed packaging box 1 (minimum height (H2)).

[0052] First, the worker places the contents 90 into the pre-assembled packaging box 1, places it at the uppermost part of the conveyor 35, and operates the control unit 36 ​​to activate the packaging device 5.

[0053] <Height Measurement Process> The conveyor 35 transports the packaging box 1 to the height measurement unit 30 and holds the packaging box 1 in the positioning and holding unit (temporarily stops it). As shown in Figure 1, the height measurement unit 30 emits laser light from the laser light source 30A toward the contents 90 inside the packaging box 1, and receives the reflected light reflected from the surface of the contents 90 with the light receiving element 30B (height measurement process). The light received data from the light receiving element 30B (measurement result of the height measurement unit 30) is transmitted to the control unit 36, and the control unit 36 ​​calculates the height (H3) of the contents 90 inside the packaging box 1 based on the measurement result of the height measurement unit 30 (see Figure 8). If the packaging box 1 contains multiple contents 90 of different heights, the tallest contents 90 is calculated as the height (H3) of the contents 90. Furthermore, the control unit 36 ​​calculates the distance (H4) from the upper end of the cylindrical body 3 (base walls 10, 11) of the packaging box 1 to the top of the contents 90 (height of base walls 10, 11 (H0) - height of contents 90 (H3)) (see Figure 8), and calculates the amount each arm 41, 51, 61 lowers based on this distance (H4). The amount each arm 41, 51, 61 lowers is set to be slightly higher than the height (H3) of the contents 90 so that the roller sections 43, 53 and blades 63 do not interfere with the contents 90. The amount each arm 41, 51, 61 lowers may be calculated, for example, as the driving time of each drive unit 42, 52, 62 or the rotation angle of the output shaft.

[0054] <Creasing Process> After measuring the height of the contents 90, the creasing section 31 forms a third curve L3 on the base walls 10, 11 of the cylindrical body 3 based on the measurement results of the height measuring section 30, dividing the base walls 10, 11 into side walls 15, 17 and upper flaps 16, 18 (creasing process).

[0055] Specifically, the conveyor 35 transports the packaging box 1 to the first creasing section 40 and holds the packaging box 1 in the positioning and holding section. The two pairs of first arms 41 (first roller section 43) of the first creasing section 40 are positioned, for example, above the right end of the pair of first base walls 10 of the packaging box 1 (see Figures 1 and 4). The first drive unit 42 of the first creasing section 40 lowers the two pairs of first arms 41 (first outer roller 44, first inner roller 45) by a calculated downward amount. The first base wall 10 of the packaging box 1 enters relatively between the pair of descending first arms 41. Next, the first drive unit 42 moves the pair of first arms 41 toward each other, sandwiching the first base wall 10 between the pair of first outer rollers 44 and first inner rollers 45 (see Figure 4). Next, the first drive unit 42 moves the pair of first arms 41 (first roller section 43) from right to left in a substantially horizontal manner, while maintaining the state in which the first base wall 10 is sandwiched between the pair of first outer rollers 44 and the first inner roller 45 (see the thick arrow in Figure 4). As a result, a third bend curve L3 is formed in the first base wall 10, separating the first side wall 15 and the upper inner flap 16 (see Figure 8). After the formation of the third bend curve L3, the first drive unit 42 returns the first arms 41 (first outer roller 44, first inner roller 45) to their initial positions (raises them).

[0056] Next, the conveyor 35 transports the packaging box 1 to the second creasing section 50 and holds the packaging box 1 in the positioning and holding section. The two pairs of second arms 51 (second roller sections 53) of the second creasing section 50 are positioned, for example, above the rear end (upstream end) of the pair of second base walls 11 of the packaging box 1 (see Figures 1 and 4). The second drive unit 52 of the second creasing section 50 lowers the two pairs of second arms 51 by a calculated downward amount. The second base wall 11 of the packaging box 1 enters relatively between the pair of descending second arms 51. Next, the second drive unit 52 moves the pair of second arms 51 toward each other, sandwiching the second base wall 11 between the pair of second outer rollers 54 and second inner rollers 55 (see Figure 4). Next, the second drive unit 52 moves the pair of second arms 51 (second roller section 53) from rear to front in a substantially horizontal manner, while maintaining the state in which the second base wall 11 is sandwiched between the pair of second outer rollers 54 and the second inner roller 55 (see the thick arrows in Figure 4). As a result, a third fold curve L3 is formed on the second base wall 11, separating the second side wall 17 and the upper outer flap 18 (see Figure 8). After the formation of the third fold curve L3, the second drive unit 52 returns the second arms 51 (second outer roller 54, second inner roller 55) to their initial positions (raises them).

[0057] In Figure 8, as an example, the third fold curve L3 is formed at a position corresponding to the maximum height (H1) of the sealed packaging box 1. The maximum height (H1) of the packaging box 1 (see also Figure 2) is the height at which the distance (H4) obtained by subtracting the maximum height (H3) of the contents 90 from the height (H0) of the base walls 10, 11 is approximately equal to half the width (dimension in the flow direction) of the first base wall 10. In contrast, the minimum height (H2) of the packaging box 1 (see also Figure 2) is the height at which this distance (H4) is approximately equal to the width of the first base wall 10. The third fold curve L3 only needs to be formed laterally (in the left-right and front-back directions) within the range of the minimum height (H2) and maximum height (H1) of the packaging box 1. On the base walls 10, 11, the third fold curve L3 is formed in the range excluding the radius of the outer rollers 44, 54 and the inner rollers 45, 55 from both ends in the lateral direction. In other words, near both ends of the foundation walls 10 and 11 in the lateral direction (left-right and front-back direction), there is a small area where the third fold curve L3 is not formed. This area where the third fold curve L3 is not formed decreases as the diameter (radius) of the outer rollers 44 and 54 and the inner rollers 45 and 55 decreases.

[0058] <Separation Process> After forming the third bend curve L3 in the foundation walls 10 and 11, the separation section 32 is formed by making cuts on the upper side of the four corners of the cylindrical body 3 based on the measurement results of the height measuring section 30 (separation process).

[0059] Specifically, the conveyor 35 transports the packaging box 1 to the dividing section 32 and holds the packaging box 1 in the positioning and holding section. The four dividing arms 61 of the dividing section 32 are positioned outside the four corners of the opening 4 of the packaging box 1 when viewed from above (see Figure 6). The dividing drive unit 62 of the dividing section 32 lowers the four dividing arms 61 (blades 63, etc.) by a calculated amount (see the white arrows shown in Figure 9). In this case, even if the blade 63 is slightly misaligned from the corner of the opening 4, the blade 63 descends while being guided by the notch 20 of the cylindrical body 3 (while sliding against the V-shaped slanted side) and bites into the cut line 21. Since a tapered portion 63B is formed on the lower edge of the blade 63, the blade 63 can easily bite into the cut 23A. The blade 63 descends along the first fold line L1, tearing the corrugated cardboard (core 9A, front liner 9B, back liner 9C) as it reaches the position where the third fold line L3 is formed. The blade 63 is held in an inclined position as it descends, sandwiching the upper flaps 16 and 18 between itself and the two guide rollers 64 (see Figures 6 and 9). The two guide rollers 64 support the upper flaps 16 and 18, which are separated by the blade 63 and attempt to open outwards.

[0060] As shown in Figures 10 and 11, the dividing unit 32 (dividing drive unit 62) lowers the blade 63 while holding it in an inclined position, and then moves it approximately horizontally to pull the blade 63 out of the cylindrical body 3 (radial direction RD) while holding it in an inclined position. Since the blade 63 has a pull-out assist surface 63A that is approximately parallel to the broken first fold line L1, the amount of movement in the pull-out direction (outside the radial direction RD) can be reduced compared to when the blade 63 is simply a rectangular plate. When the blade 63 is pulled out of the cylindrical body 3, the dividing drive unit 62 returns the dividing arm 61 (blade 63, etc.) to its initial position (raises it).

[0061] As described above, the blade 63 of the dividing section 32 descends from the corner of the opening 4 of the cylindrical body 3 to the third fold line L3 (horizontal fold line), thereby dividing the upper flaps 16 and 18, which are connected via the first fold line L1, along the first fold line L1. A groove 66 is formed in the cylindrical body 3 along the first fold line L1 (vertical ridge line). In this embodiment, the blade 63 breaks the first fold line L1 at least from the upper end of the cylindrical body 3 (upper edge of the opening 4) to a position corresponding to the maximum height (H1) of the packaging box 1. Furthermore, if the height of the contents 90 is low (small), the first fold line L1 is broken within the range from the upper end of the cylindrical body 3 (upper edge of the opening 4) to a position corresponding to the minimum height (H2) of the packaging box 1. In the packaging box 1 at the minimum height (H2), the side walls 15 and 17 will be connected along approximately the lower half of the first fold line L1.

[0062] <Folding Process> After separating the upper flaps 16 and 18, the conveyor 35 transports the packaging box 1 to the folding section 33 and holds the packaging box 1 in the positioning and holding section. The folding section 33 folds the upper flaps 16 and 18, separated by the separating section 32, inward along the third fold line L3 (horizontal fold line) of the cylindrical body 3 (folding process). The folding drive unit 72 of the folding section 33 rotates a pair of inner folding arms 70 to fold the pair of upper inner flaps 16 along the third fold line L3, and then rotates the outer folding arm 71 to fold one of the upper outer flaps 18 (for example, the left one) along the third fold line L3 (see Figure 1). The one upper outer flap 18 is superimposed on the surface of the pair of upper inner flaps 16 (see Figure 12 or Figure 13).

[0063] <Sealing Process> After folding the pair of upper inner flaps 16 and one of the upper outer flaps 18, the conveyor 35 transports the packaging box 1 to the sealing section 34, where the packaging box 1 is held in the positioning and holding section. The sealing section 34 seals the packaging box 1 (sealing process). The sealing drive unit 82 of the sealing section 34 rotates the sealing folding arm 80 to fold the other upper outer flap 18 along the third folding curve L3 (see Figure 1). At this point, when the sealed packaging box 1 reaches its maximum height (H1), the pair of upper outer flaps 18, separated along the first folding curve L1, will come into contact with each other at their ends (see Figure 12). On the other hand, in packaging boxes 1 that are at a height other than the maximum height (H1) (for example, the minimum height (H2)), the leading edge of the other upper outer flap 18 will overlap the surface of the first upper outer flap 18 (see Figure 13). The adhesive portion 81 of the sealing portion 34 is applied by attaching adhesive tape T along the abutting portion of the pair of upper outer flaps 18 (see Figure 12), or by attaching adhesive tape T along the leading edge of the other upper outer flap 18 (see Figure 13).

[0064] As a result, the opening 4 of the cylindrical body 3 is closed, and the packaging box 1 is sealed (see Figures 12 and 13).

[0065] In the packaging device 5 described above, a non-sharp, plate-shaped blade 63 is configured to break the cylindrical body 3 along the first fold line L1. With this configuration, even if the blade 63 contacts the cylindrical body 3 at a position offset from the upper corner (first fold line L1), it is not a sharp blade, so it is prevented from cutting further along the offset position L1. Furthermore, because the blade 63 is not sharp but formed in a high-strength plate shape, damage and wear of the blade 63 can be suppressed. This prevents problems such as a part of the blade 63 breaking off and getting mixed into the packaging box 1. In addition, the frequency of blade 63 replacement can be reduced, thus suppressing an increase in the running costs of the packaging device 5.

[0066] Furthermore, with the packaging device 5 described above, since the blade 63 is held in an inclined position as it descends, the contact resistance between the blade 63 and the vertical ridge (first fold line L1) of the cylindrical body 3 can be reduced. As a result, the cross-section along the first fold line L1 of the cylindrical body 3 is not crushed, and the vertical ridge (first fold line L1) of the cylindrical body 3 can be cleanly broken by the descending blade 63.

[0067] Here, if, after the first fold line L1 is broken, the descended blade 63 is raised and pulled out of the cylindrical body 3, there is a risk that the position of the packaging box 1 on the conveyor 35 may shift due to frictional resistance between the fracture surface of the first fold line L1 and the surface of the blade 63. In contrast, with the packaging device 5 described above, the blade 63, which has descended to a predetermined position, is held in an inclined position and pulled out almost horizontally to the outside of the cylindrical body 3 (see Figures 10 and 11), thereby suppressing the shifting of the position of the packaging box 1 on the conveyor 35.

[0068] Furthermore, in the packaging device 5 described above, the guide roller 64 rotates while contacting the surfaces of the adjacent upper flaps 16 and 18, which are straddling the first fold curve L1, as the blade 63 descends (see Figure 9). With this configuration, when the descending blade 63 breaks the first fold curve L1, the upper flaps 16 and 18, which tend to fall outward, can be supported by the guide roller 64. This allows the descending blade 63 to follow the vertical ridge (first fold curve L1) of the cylindrical body 3.

[0069] In the packaging box 1 according to the first embodiment described above, a third fold curve L3 corresponding to the height of the contents 90 is formed on the base walls 10, 11 (wall portion) by the packaging device 5, and then the cylindrical body 3 is broken from the upper end of the first fold curve L1 (vertical ridge) up to the third fold curve L3. With this configuration, there is no need to form multiple third fold curves L3 on the base walls 10, 11 in advance, and side walls 15, 17 without the third fold curve L3 can be formed when the packaging box 1 is sealed. This makes it possible to suppress a decrease in the compressive strength of the sealed packaging box 1. In addition, since the first fold curve L1 (vertical ridge) of the cylindrical body 3 is not weakened by perforations or the like, the corner portion of the cylindrical body 3 can firmly receive the load.

[0070] Furthermore, according to the packaging box 1 of the first embodiment, since a V-shaped notch 20 is recessed at the corner of the opening 4, even if the blade 63 is positioned slightly off from the first bend curve L1 of the cylindrical body 3, the blade 63 can be guided into the notch 20. Also, by setting the width of the lower end of the notch 20 within the range of 4 to 10 mm, the blade 63 can be guided into the notch 20 and then guided to the cutting line 21.

[0071] Furthermore, according to the packaging box 1 of the first embodiment, since the cut line 21 is cut downward from the lower end of the notch 20, the blade 63 guided by the notch 20 can be bitten into the cut line 21. This ensures that the blade 63 is reliably guided to the upper end of the first fold line L1, and the blade 63 can make a cut in the cylindrical body 3 along the first fold line L1.

[0072] [Modifications of the First Embodiment] Next, with reference to Figures 14 to 18, the packaging box 1 (blank 1A) according to the first to fifth modifications of the first embodiment will be briefly described. Figures 14 to 18 are plan views showing the blank 1A of the packaging box 1 according to the first to fifth modifications, in this order. In the description of the first to fifth modifications, components that are the same as or corresponding to the packaging box 1 (blank 1A) described above will be denoted by the same reference numerals, and their descriptions will be omitted.

[0073] <First and Second Modified Examples> In the packaging box 1 according to the first embodiment described above, the notch 20 was recessed in a V-shape, but the present invention is not limited thereto. As a first modified example of the packaging box 1 (blank 1A), as shown in Figure 14, the notch 22 may be formed in a groove shape (U-shape) of substantially the same width from the upper edge of the corner of the opening 4 downwards, and the cut line 21 may be cut downwards from the lower end of the notch 22. Also, as shown in Figure 15, for example, as a second modified example of the packaging box 1 (blank 1A), the notches 20 and 22 may be omitted. In this case, the cut line 21 is cut downwards from the upper ends of the base walls 10 and 11.

[0074] <Third Modification> As shown in Figure 16, in the packaging box 1 (blank 1A) according to the third modification, a pair of guide fold lines 23 may be formed in a V-shape instead of the notch 20. Specifically, the pair of guide fold lines 23 are formed to be inclined so as to move away from each other from the lower end of the cut line 21 toward the upper end of the base walls 10, 11 (the upper edge of the opening 4 of the cylindrical body 3). One guide fold line 23 is formed at the corners of the base walls 10, 11 at both ends in the flow direction, and when the cylindrical body 3 is formed, it becomes a pair of guide fold lines 23. The guide fold lines 23 may also be general-purpose creases or lead creases, or they may be reverse creases formed by crushing the corrugated cardboard in the thickness direction from the front liner 9B side.

[0075] In the third modified packaging box 1 (blank 1A), for example, if the blade 63 is positioned slightly offset from the cut line 21, the descending blade 63 will collide with the upper edge of the opening 4, causing the tip corners of the upper flaps 16 and 18 to bend along the guide fold line 23. As a result, the blade 63 can enter the cut line 21 along the fold in the guide fold line 23, and thus guide the blade 63 from the cut line 21 to the upper end of the first fold curve L1. The pair of guide fold lines 23 extended from the lower end of the cut line 21 to the upper end of the base walls 10 and 11, but this is not limited to this, and they do not have to reach the upper end of the base walls 10 and 11 (not shown). Also, the pair of guide fold lines 23 extended diagonally upward from the lower end of the cut line 21, but this is not limited to this, and they may extend diagonally upward from slightly above the lower end of the cut line 21 (not shown). In other words, the "lower end of the cutting line" as used in the claim does not refer only to the lower end of the cutting line 21, but also includes the portion that is slightly above the lower end of the cutting line 21.

[0076] <Fourth Modification> In addition, as shown in Figure 17, the packaging box 1 (blank 1A) according to the fourth modification may have multiple guide fold lines 23 formed parallel to each other at intervals. With this configuration, when the descending blade 63 collides with the upper edge of the opening 4, the triangular area weakened by the multiple guide fold lines 23 can be easily deformed. This makes it possible to obtain the same effect as the packaging box 1 (blank 1A) according to the third modification described above. Note that the number of guide fold lines 23 is not limited to three; it is sufficient to have two or more guide fold lines 23 formed parallel to each other at intervals.

[0077] <Fifth Modification> Furthermore, as a packaging box 1 (blank 1A) according to the fifth modification, as shown in Figure 18, a triangular region 24 enclosed by a pair of imaginary lines (lines that do not actually exist, shown as dashed lines in Figure 18) that are inclined to move away from each other from the lower end of the cut line 21 toward the upper end of the foundation walls 10, 11 (cylindrical body 3) may be flattened. Here, "flattened" refers to a structure in which the corrugated cardboard sheet is flattened in the thickness direction, and is shown as a hatch (diagonal line) in Figure 18. In the packaging box 1 according to the fifth modification, for example, the core 9A is flattened in the thickness direction from the back side (back liner 9C) of the corrugated cardboard sheet, but it may also be a structure in which the core 9A is flattened in the thickness direction from the front side (front liner 9B) of the corrugated cardboard sheet. Note that one imaginary line is formed at the corners of the foundation walls 10, 11 at both ends in the flow direction, and these become a pair of imaginary lines when the cylindrical body 3 is formed. In the fifth modified example of the packaging box 1 (blank 1A), the triangular region 24 is weakened by the collapsing of the ridges, so the same effect as the packaging box 1 (blank 1A) according to the third and fourth modified examples described above can be obtained. The features of the fifth modified example of the packaging box 1 (blank 1A) (collapsing of the triangular region 24) may be combined with the packaging box 1 (blank 1A) according to the third and fourth modified examples (not shown).

[0078] [Problems with using a non-sharp blade] In the first embodiment (including the first to fifth modified examples; the same applies hereinafter), the corrugated cardboard sheet constituting the packaging box 1 (cylindrical body 3) was broken by a non-sharp blade 63. Considering the breakage by a non-sharp blade 63, it is preferable to construct the packaging box 1 (cylindrical body 3) from a corrugated cardboard sheet that is easily broken (easily torn). On the other hand, considering the protection of the contents 90 contained in the packaging box 1, it is preferable to construct the packaging box 1 (cylindrical body 3) from a corrugated cardboard sheet that is difficult to crush.

[0079] Furthermore, the non-sharp blade 63 descends while slightly crushing the upper corner portion of the cylindrical body 3 (the upper edge of the notch portion 20) and dragging the corrugated cardboard sheet around the first fold curve L1. For example, if the corrugated cardboard sheet is tear-resistant, the corrugated cardboard sheet around the first fold curve L1 may tear in a strip that spreads horizontally from top to bottom, and a large hole may be created at the base portion of the adjacent upper flaps 16 and 18 (the lower end of the groove 66) (see Figure 24). In other words, the groove 66 formed along the vertical ridge of the cylindrical body 3 widens from top to bottom, resulting in a groove width that far exceeds the thickness of the blade 63 (blade thickness). Since the hole created at the base portion of the upper flaps 16 and 18 appears at the upper corner portion of the sealed packaging box 1, not only does it become impossible to properly package the contents 90, but the aesthetic appearance of the packaging box 1 may also be significantly impaired.

[0080] [Breaking Ratio] Considering the above-mentioned problems, the packaging box 1 according to the first embodiment is made of corrugated cardboard sheets having a breaking ratio (Z) = 0.0039 [N / (m・Pa)] = 3.9 [mN / (m・Pa)] or higher. The breaking ratio (Z) is the ratio of the vertical compressive strength (Y [kN / m]) of the corrugated cardboard sheet to the bursting strength (X [kPa]) of the corrugated cardboard sheet, and is calculated by the following formula 1. Note that the "m" at the beginning of the unit in the above-mentioned breaking ratio (Z) = 3.9 [mN / (m・Pa)] is the SI prefix milli (10^-3).

[0081]

[0082] ​The greater the burst strength (X) of a corrugated cardboard sheet, the more difficult it is to break, and the less the burst strength (X) is, the easier it is to break. The burst strength (X) of a corrugated cardboard sheet should be measured according to the test method specified in JIS P 8131. Also, the greater the vertical compressive strength (Y) of a corrugated cardboard sheet, the more difficult it is to crush, and the less the vertical compressive strength (Y) is, the easier it is to crush. The vertical compressive strength (Y) of a corrugated cardboard sheet should be measured according to the test method specified in JIS Z 0403-2. There is a certain degree of correlation between the burst strength (X) and the vertical compressive strength (Y) of a corrugated cardboard sheet; for example, when the vertical compressive strength (Y) is large, the burst strength (X) tends to be large as well. Therefore, in the above-mentioned equation 1, increasing the vertical compressive strength (Y) also increases the bursting strength (X), so the increase in the crushing ratio (Z) plateaus, and it is estimated that the crushing ratio (Z) will never reach an infinitely large value. Also, for example, corrugated cardboard sheets made from base paper containing a large amount of reinforcing agent may have a bursting strength (X) that does not change significantly compared to corrugated cardboard sheets made from conventional base paper that does not contain a large amount of reinforcing agent, but the vertical compressive strength (Y) may be higher. For this reason, the vertical compressive strength (Y) may be larger relative to the bursting strength (X), and the crushing ratio (Z) may increase. Furthermore, for example, corrugated cardboard sheets made from base paper containing a large amount of short-fiber recycled paper may have a vertical compressive strength (Y) that does not change significantly compared to corrugated cardboard sheets made from conventional base paper that does not contain a large amount of recycled paper, but the bursting strength (X) may be lower. For this reason, the bursting strength (X) may be smaller relative to the vertical compressive strength (Y), and the crushing ratio (Z) may increase.

[0083] In the fracture of a cylindrical body 3 (corrugated cardboard sheet) using a non-sharp blade 63, the ratio (percentage) of the bursting strength (X) to the vertical compressive strength (Y) of the corrugated cardboard sheet is important in order to suppress the spread of the cut groove 66 from top to bottom. In the packaging box 1 according to the first embodiment, by setting the crushing ratio (Z) to 3.9 [mN / (m・Pa)] or higher, proper fracture of the cylindrical body 3 (corrugated cardboard sheet) is made possible even with a non-sharp blade 63.

[0084] [Verification] The applicant conducted tests (verification) to confirm that setting the crushing ratio (Z) of the corrugated cardboard sheet to 3.9 [mN / (m·Pa)] or higher is effective in crushing the corrugated cardboard sheet using a non-sharp blade 63. The tests to verify the effectiveness of the crushing ratio (Z) set for the corrugated cardboard sheet will be described below with reference to Figures 19 and 20. Figure 19 is a perspective view showing the test cylinder 3A used in the test. Figure 20 is a chart showing the results of the test. In the following description and drawings, the units [kPa], [kN / m] and [mN / (m·Pa)] for burst strength (X), vertical compressive strength (Y), and crushing ratio (Z) may be omitted.

[0085] <Test Conditions and Methods> In this test (verification), as shown in Table 1 below, five sheets each of multiple corrugated cardboard sheets with different crushing ratios (Z) (four examples and two comparative examples) were prepared. Each corrugated cardboard sheet was humidified in a humidity-controlled environment as specified in JIS P 8111:1998, and this test (verification) was conducted in the above humidity-controlled environment.

[0086]

[0087] Each corrugated cardboard sheet had a first fold line L1 and cut lines 21 formed on it, similar to the blank 1A. As shown in Figure 19, by folding the corrugated cardboard sheet along the first fold line L1, a rectangular cylindrical test cylinder 3A similar to the cylindrical body 3 of the packaging box 1 was created. Five test cylinders 3A were created for each type of corrugated cardboard sheet. As an example, groove-shaped notches 22 of the same width are formed at the four upper corners of the test cylinder 3A, but the notches 22 may be omitted.

[0088] ​In this test (verification), the upper side of the longitudinal ridge (first fold line L1) of each test cylinder 3A was broken by the cutting section 32 (blade 63) of the packaging device 5. The applicant observed (visually) the way the test cylinder 3A (corrugated cardboard sheet) was torn and the cut surface after being broken by the non-sharp blade 63, and evaluated the results according to the following three criteria: • Good: The cut groove 66 is approximately the same width as the blade thickness from top to bottom. • Poor: The cut groove 66 widens downwards and the groove width significantly exceeds the blade thickness. • Average: The cut groove 66 has a groove width that is somewhere between good and poor.

[0089] <Test Results> The test results of this test (main verification) are shown in Figure 20. In Figure 20, "○" indicates good, "×" indicates poor, and "△" indicates average. Figure 20 also shows a photograph of the groove 66 formed in the test cylinder 3A.

[0090] In the corrugated cardboard sheets of Comparative Example 1 (crushing ratio (Z) = 2.0) and Comparative Example 2 (crushing ratio (Z) = 3.8), the grooves 66 widened downwards, resulting in groove widths significantly exceeding the thickness of the blade 63. In other words, the corrugated cardboard sheets of Comparative Examples 1 and 2 received a defective (×) rating. Therefore, when a packaging box 1 is formed using the corrugated cardboard sheets of Comparative Examples 1 and 2, unnecessary holes appear in the upper corners of the packaging box 1, making it impossible to properly package the contents 90, and significantly impairing the aesthetic appearance of the packaging box 1.

[0091] In the corrugated cardboard sheet according to Example 1 (crushing ratio (Z) = 3.9), the groove 66 widens slightly downwards, but not as much as the groove 66 in the corrugated cardboard sheets according to Comparative Examples 1 and 2. In the corrugated cardboard sheet according to Example 1, the fracture surface on the right side of the groove 66 in the photograph is formed almost vertically, showing a slight improvement over the groove 66 in the corrugated cardboard sheets according to Comparative Examples 1 and 2. In other words, the corrugated cardboard sheet according to Example 1 received an average (△) rating. Therefore, it is considered that the corrugated cardboard sheet according to Example 1 is more suitable for breaking with a non-sharp blade 63 than the corrugated cardboard sheets according to Comparative Examples 1 and 2. Accordingly, when a packaging box 1 is formed with the corrugated cardboard sheet according to Example 1, it is considered that unnecessary holes will be less likely to appear in the upper corner portion of the packaging box 1, making it possible to properly package the contents 90 and maintain the aesthetic appearance of the packaging box 1.

[0092] In the corrugated cardboard sheets according to Example 2 (crushing ratio (Z) = 6.1), Example 3 (crushing ratio (Z) = 6.9), and Example 4 (crushing ratio (Z) = 7.2), the groove 66 was approximately the same width as the thickness of the blade 63 from top to bottom. In other words, the corrugated cardboard sheets according to Examples 2 to 4 received a good (〇) evaluation. Therefore, it is considered that the corrugated cardboard sheets according to Examples 2 to 4 are more suitable for breaking using a non-sharp blade 63 than the corrugated cardboard sheet according to Example 1. Accordingly, when a packaging box 1 is formed using the corrugated cardboard sheets according to Examples 2 to 4, the appearance of unnecessary holes in the upper corner portion of the packaging box 1 is suppressed, the contents 90 can be properly packaged, and the aesthetic appearance of the packaging box 1 can be maintained.

[0093] <Conclusion> Based on the test results described above, it was confirmed that setting the crushing ratio (Z) of the corrugated cardboard sheet to 3.9 or higher is effective in crushing the corrugated cardboard sheet using a non-sharp blade 63. In this test (verification), it was not possible to prepare a corrugated cardboard sheet with a crushing ratio (Z) in the 5.0 range. However, considering the test results of Example 1 (crushing ratio (Z) = 3.9) and Example 2 (crushing ratio (Z) = 6.1), it is estimated that a corrugated cardboard sheet with a crushing ratio (Z) in the 5.0 range can form a better cut groove 66 compared to the corrugated cardboard sheet of Example 1. Therefore, it is estimated that it is preferable to set the crushing ratio (Z) of the corrugated cardboard sheet to 5.0 or higher. Furthermore, in this test (verification), it was not possible to prepare a corrugated cardboard sheet with a crushing ratio (Z) of 6.0. However, considering the test results of Example 2 (crushing ratio (Z) = 6.1), it is estimated that even a corrugated cardboard sheet with a crushing ratio (Z) of 6.0 would yield substantially the same test results as the corrugated cardboard sheet in Example 2. Therefore, it is estimated that it is even more preferable to set the crushing ratio (Z) of the corrugated cardboard sheet to 6.0 or higher.

[0094] As explained earlier, increasing the vertical compressive strength (Y) also increases the bursting strength (X), so it is presumed that the increase in the crushing ratio (Z) plateaus (there is an upper limit to the crushing ratio (Z)). In this test (this verification), it was not possible to determine the upper limit of the crushing ratio (Z), but the applicant has confirmed the existence of corrugated cardboard sheets with a crushing ratio (Z) of 10.4. The applicant presumes that even if a corrugated cardboard sheet is formed from base paper containing a large amount of reinforcing agent or base paper containing a large amount of short-fiber recycled paper, there are no corrugated cardboard sheets with a crushing ratio (Z) exceeding 11.0. In this test, as the crushing ratio (Z) increased, better test results were obtained, so it is presumed that even a corrugated cardboard sheet with a crushing ratio (Z) of 11.0 would yield similar test results to the corrugated cardboard sheet in Example 4 (crushing ratio (Z) = 7.2). Based on the above, it is estimated that by setting the crushing ratio (Z) of the corrugated cardboard sheet to 3.9 [mN / (m・Pa)] or more and 11.0 [mN / (m・Pa)] or less, even a non-sharp blade 63 can be properly fractured. Preferably, by setting the crushing ratio (Z) to 5.0 [mN / (m・Pa)] or more and 11.0 [mN / (m・Pa)] or less, and more preferably, by setting the crushing ratio (Z) to 6.0 [mN / (m・Pa)] or more and 11.0 [mN / (m・Pa)] or less, even a non-sharp blade 63 can be properly fractured.

[0095] In the packaging box 1 according to the first embodiment described above, the value obtained by dividing the vertical compressive strength Y [kN / m] of the corrugated cardboard sheet by the bursting strength X [kPa] is defined as the crushing ratio (Z) [mN / (m・Pa)], and the crushing ratio (Z) of the corrugated cardboard sheet was set to 3.9 [mN / (m・Pa)] or higher. With this configuration, even with a non-sharp blade 63, it is possible to crush the cylindrical body 3 (side walls 15, 17) while breaking the cylindrical body 3 along the first fold line L1. As a result, the formation of an appropriate packaging box 1 with the upper corner portion securely closed is suppressed.

[0096] [Second Embodiment: Packaging Box] Next, a packaging box 2 (blank 2A) according to the second embodiment will be described with reference to Figures 21 to 23. Figure 21 is a plan view showing the blank 2A ​​of the packaging box 2. Figure 22 is a perspective view showing the packaging box 2 in a temporarily assembled state. Figure 23 is a side view showing the packaging box 2 and the blade 63 of the packaging device 5. In the description of the packaging box 2 (blank 2A) according to the second embodiment, the same reference numerals are used for components that are the same as or correspond to those of the packaging box 1 (blank 1A) described in the first embodiment, and their descriptions are omitted.

[0097] As shown in Figure 21, in the blank 2A ​​of the packaging box 2, a pair of first base walls 10 and a pair of second base walls 11 are arranged alternately in the flow direction and connected via bent sections 25 (vertical ridges). The pair of first base walls 10 and the pair of second base walls 11 are bent at the bent sections 25 to form a rectangular cylindrical body 3 (see Figure 22).

[0098] <Folded Section> The folded section 25 has a first fold line L1 formed on the other side (downward) in the step direction and a breaking guide line 26 formed on the one side (upward) in the step direction. The first fold line L1 and the breaking guide line 26 are arranged side by side on the same straight line along the step direction. The first fold line L1 is formed between the lower end of the base walls 10, 11 (cylindrical body 3) and the position corresponding to the minimum height (H2) of the sealed packaging box 2. The breaking guide line 26 is formed between the first fold line L1 and the cut line 21. The breaking guide line 26 is formed to be longer in the step direction than the first fold line L1.

[0099] (Breakage guide line) The breakage guide line 26 has a first breakage line 27 and a second breakage line 28. The first breakage line 27 is formed between the lower end of the cut line 21 and the upper end of the second breakage line 28. The second breakage line 28 is formed between the lower end of the first breakage line 27 and the upper end of the first fold line L1. The first breakage line 27 is formed to be shorter in the step direction than the second breakage line 28. As shown in Figure 22, when the packaging box 2 is temporarily assembled, the first breakage line 27 is formed between the corner of the opening 4 of the cylindrical body 3 (more precisely, the lowest part of the notch 20) and the position corresponding to the maximum height (H1) of the packaging box 2 after sealing. The second breakage line 28 is formed between the lower end of the first breakage line 27 and the position corresponding to the minimum height (H2) of the packaging box 2 after sealing. In other words, the lower end position of the first break line 27 (the upper end position of the second break line 28) corresponds to the maximum height (H1) of the sealed packaging box 2, and the lower end position of the second break line 28 (the upper end position of the first fold line L1) corresponds to the minimum height (H2) of the sealed packaging box 2.

[0100] As shown in Figure 21, the first break line 27 is a perforation formed by alternating first cuts 27A and first seams 27B. The second break line 28 is a perforation formed by alternating second cuts 28A and second seams 28B. The first cuts 27A and the second cuts 28A are straight cuts made by passing a blade through the corrugated cardboard in the thickness direction. The first seams 27B and the second seams 28B are portions of the corrugated cardboard sheet that connect adjacent cuts 27A and 28A, respectively, and have not been cut. In this specification, when the first cuts 27A and the second cuts 28A are described together, they may simply be called "cuts 27A, 28A," and when the first seams 27B and the second seams 28B are described together, they may simply be called "seams 27B, 28B."

[0101] The lengths of the first cut 27A, first joint 27B, second cut 28A, and second joint 28B are set so that the second fracture line 28 is less likely to break than the first fracture line 27. The lengths of the cuts 27A, 28A and the joints 27B, 28B should be set within the following ranges so as to satisfy the condition of making the second fracture line 28 less likely to break. The lengths of the cuts 27A, 28A and the joints 27B, 28B should be set within the range of 3 mm or more and 40 mm or less, preferably 3 mm or more and 20 mm or less, and more preferably 3 mm or more and 10 mm or less. For example, the second cut 28A should be formed shorter than the first cut 27A, and the second joint 28B should be formed longer than the first joint 27B. Note that the relationship between the lengths of the cuts 27A, 28A and the joints 27B, 28B is not limited to the above. For example, the first cut 27A and the second cut 28A may be the same length, and the second joint 28B may be formed to be longer than the first joint 27B (not shown). Alternatively, for example, the first joint 27B and the second joint 28B may be the same length, and the second cut 28A may be formed to be shorter than the first cut 27A (not shown). Furthermore, for example, the first cut 27A may be formed to be longer than the second cut 28A, and the first joint 27B may be formed to be longer than the second joint 28B (not shown).

[0102] The first fracture line 27 and the second fracture line 28 are each formed by at least one cut 27A, 28A and at least one joint 27B, 28B. Furthermore, if the first fracture line 27 includes multiple first cuts 27A and multiple first joints 27B, the multiple first cuts 27A may all be of the same length or may be of different lengths (not shown). Similarly, the multiple first joints 27B may all be of the same length or may be of different lengths (not shown). The same applies to the second fracture line 28 if it includes multiple second cuts 28A and multiple second joints 28B.

[0103] The temporarily assembled packaging box 2 (see Figure 22), with the contents 90 inside, is placed at the uppermost part of the conveyor 35 and sealed by the packaging device 5 described earlier. The sealing method of the packaging box 2 (operation of the packaging device 5) is generally the same as the sealing method of the packaging box 1 according to the first embodiment described earlier, so a detailed explanation is omitted.

[0104] Since the lower end position of the first break line 27 corresponds to the maximum height (H1) of the sealed packaging box 2, the entire first break line 27 is broken regardless of the height of the packaging box 2 (contents 90). In the packaging box 2 at the maximum height (H1), the side walls 15 and 17 are connected by the first fold curve L1 and the second break line 28. In contrast, in the packaging box 2 at the minimum height (H2), the entire break guide line 26 is broken, and the side walls 15 and 17 are connected only by the first fold curve L1. Furthermore, in the packaging box 1 at heights other than the maximum height (H1) and minimum height (H2), a portion of the second break line 28 is broken, and the side walls 15 and 17 are connected by the first fold curve L1 and the remaining unbroken portion of the second break line 28.

[0105] In the packaging box 2 according to the second embodiment, the upper portion of the vertical ridge line including the boundary between adjacent upper flaps 16 and 18 was weakened by the breaking guide line 26 (first breaking line 27 and second breaking line 28). With this configuration, even with a non-sharp blade 63, the cylindrical body 3 (side walls 15 and 17) can be easily broken along the breaking guide line 26 while suppressing crushing of the cylindrical body 3. Furthermore, since the side walls 15 and 17 without the third fold line L3 can be formed when the packaging box 2 is sealed, the decrease in the compressive strength of the sealed packaging box 2 can be suppressed, and similar effects to the packaging box 1 according to the first embodiment can be obtained.

[0106] Furthermore, in the packaging box 1 according to this embodiment, the lengths of the cuts 27A, 28A and the joints 27B, 28B were set such that the second break line 28 is less likely to break than the first break line 27. With this configuration, for example, in the packaging box 1 at its maximum height after sealing, the second break line 28 remains unbroken, but because the second break line 28 is structured to be less likely to break, the compressive strength of the packaging box 1 at its maximum height can be maintained at a high level.

[0107] In the packaging box 2 according to the second embodiment, the break guide line 26 had a first break line 27 and a second break line 28, but the present invention is not limited thereto. The second break line 28 may be omitted, and the break guide line 26 may have only the first break line 27 (modified example (not shown)). In this case, instead of the second break line 28, a first fold line L1 is formed, and the first break line 27 is formed between the lower end of the cut line 21 and the upper end of the first fold line L1.

[0108] [Problems with using a non-sharp blade] When a non-sharp blade 63 breaks the cylindrical body 3 along the fracture guide line 26, it descends while being guided by the cuts 27A and 28A. Therefore, if the cuts 27A and 28A are extremely short, the blade 63 may not be guided by the cuts 27A and 28A, and the blade may deviate from the fracture guide line 26 as the fracture progresses. If the derailment of the blade 63 occurs immediately after the start of the first fracture line 27, there is a risk that the deviation due to derailment will increase when the second fracture line 28, which is more difficult to break than the first fracture line 27, is broken. Therefore, in order to properly divide the cylindrical body 3 along the fracture guide line 26, it is important to firmly guide the descending blade 63 to the first cut 27A of the first fracture line 27.

[0109] [Crossing Distance] Considering the above-mentioned problems, in the packaging box 2 according to the second embodiment, the length of the first cut 27A (H5) (see Figure 21) is set to be 1 / 8 or more of the crossing distance (H6) (see Figure 23), which is the maximum height of the blade 63 that contacts the fracture surface (cut) of the first break line 27 (longitudinal ridge) ((H5) ≥ (H6) / 8). As shown in Figure 23, since the blade 63 is provided in an inclined position in the packaging device 5, the crossing distance (H6) is the length of a vertical line extended vertically upward from a point in the tapered portion 63B that contacts the first break line 27 (see the black circle shown in Figure 23) so as to cross the blade 63. This vertical line extends approximately parallel to the pull-out assist surface 63A. The crossing distance (H6) can also be said to be the maximum length over which the first break line 27 can contact the side surface of the blade 63.

[0110] According to the packaging box 2 of the second embodiment described above, by setting the length (H5) of the first cut 27A of the first breaking line 27 to 1 / 8 or more of the crossing distance (H6), the descending blade 63 can be guided to the first cut 27A. As a result, the non-sharp blade 63 is less likely to deviate from the breaking guide line 26, and the cylindrical body 3 can be properly broken along the first breaking line 27. The applicant has experimentally confirmed that the guiding function of the descending blade 63 is effectively performed by setting the length (H5) of the first cut 27A to 1 / 8 or more of the crossing distance (H6) of the blade 63, preferably 1 / 4 or more of the crossing distance (H6).

[0111] Furthermore, the features of the packaging box 1 according to the first to fifth modifications of the first embodiment (notches 22, guide fold lines 23, and stepped folds) may be applied to the packaging box 2 according to the second embodiment (not shown).

[0112] In the packaging boxes 1 and 2 according to the first and second embodiments, the lower inner flap 13 and the lower outer flap 14 are folded over to form the bottom, and the tips of the pair of lower outer flaps 14 are joined together, but the present invention is not limited to this. For example, the tips of the pair of lower outer flaps 14 may be spaced apart (not shown). Also, for example, the bottom of the packaging boxes 1 and 2 may be a so-called one-touch bottom or a so-called hell bottom (not shown).

[0113] Furthermore, while the packaging boxes 1 and 2 according to the first and second embodiments were formed from double-sided corrugated cardboard, the present invention is not limited thereto. The packaging boxes 1 and 2 may be formed from single-sided corrugated cardboard, double-sided corrugated cardboard, or triple-double-sided corrugated cardboard, etc.

[0114] In the packaging device 5 described above, the second creasing section 50 was located downstream of the first creasing section 40, but it is not limited to this and may be located upstream of the first creasing section 40 (not shown). In other words, in the creasing process, the third fold curve L3 may be formed on the first base wall 10 after the third fold curve L3 is formed on the second base wall 11. Furthermore, the creasing section 31 may be configured such that the first creasing section 40 and the second creasing section 50 are integrated to form the third fold curve L3 on all four sides of the cylindrical body 3 at the same time (not shown).

[0115] Furthermore, in the packaging device 5 described above, one inner roller 45, 55 of the creasing section 31 is configured to face the pair of outer rollers 44, 54, but the present invention is not limited to this. For example, the outer rollers 44, 54 may be reduced to one, and one inner roller 45, 55 may face the outer roller 44, 54 (not shown). Alternatively, the inner rollers 45, 55 may be made into a pair, and the pair of outer rollers 44, 54 may face the pair of inner rollers 45, 55 (not shown). Alternatively, the outer rollers 44, 54 may be reduced to one, the inner rollers 45, 55 may be made into a pair, and one outer roller 44, 54 may face the pair of inner rollers 45, 55 (not shown).

[0116] Furthermore, in the packaging device 5 described above, the inner rollers 45 and 55 were slightly lower than the outer rollers 44 and 54, but the present invention is not limited to this. The inner rollers 45 and 55 may be arranged to face the outer rollers 44 and 54 at the same height (not shown).

[0117] Furthermore, in the packaging device 5 (creasing section 31) described above, the third fold curve L3 was formed horizontally (left-right and front-back directions) within a range of minimum height (H2) to maximum height (H1) of the packaging boxes 1 and 2, but the present invention is not limited thereto. For example, the third fold curve L3 may be formed horizontally (left-right and front-back directions) within a range of maximum height (H1) or more of the packaging boxes 1 and 2 (not shown). In this case, when the packaging boxes 1 and 2 are sealed, the tips of the pair of upper outer flaps 18 will be separated from each other (not shown).

[0118] Furthermore, in the packaging device 5 described above, the blades 63 of the dividing section 32 were in an inclined position, but the present invention is not limited to this. For example, the four blades 63 may be in a position perpendicular to the first base wall 10 when viewed from above, or perpendicular to the second base wall 11 (not shown). Also, for example, the blades 63 may be in a position that is substantially horizontal when viewed from the side (front and side) (not shown). In this case, the crossing distance (H6) of the blades 63 is the length of a virtual vertical line perpendicular to the tip edge of the tapered section 63B (not shown).

[0119] Furthermore, in the packaging device 5 described above, a tapered portion 63B was formed on the lower edge of the blade 63 of the dividing section 32, but the present invention is not limited to this. For example, a pair of tapered portions 63B may be formed on both the upper and lower edges of the blade 63 (not shown). In this case, if the lower tapered portion 63B wears out, the blade 63 can be turned upside down, and the upper tapered portion 63B can be turned downward, saving the trouble of replacing the blade 63 with a new one. Alternatively, the tapered portion 63B may be omitted, and the blade 63 may be formed in the shape of a plate with substantially uniform thickness (not shown).

[0120] Furthermore, in the packaging device 5 described above, an extraction assist surface 63A was formed on the blade 63 of the cutting section 32, but this is not limited to this, and the extraction assist surface 63A may be omitted (not shown). Also, the guide roller 64 and roller arm 65 of the cutting section 32 may be omitted (not shown).

[0121] Furthermore, in the packaging device 5 described above, the sealing section 34 sealed the packaging boxes 1 and 2 using adhesive tape T, but the present invention is not limited to this. For example, a pair of upper outer flaps 18 may be bonded to a pair of upper inner flaps 16 via an adhesive, or the other upper outer flap 18 may be bonded to the other upper outer flap 18 via an adhesive (not shown).

[0122] Furthermore, although the packaging device 5 described above is provided with a folding section 33 and a sealing section 34, the present invention is not limited thereto. For example, if the sealing work is performed manually by an operator closing the upper flaps 16, 18 and applying adhesive tape T, the folding section 33 and sealing section 34 may be omitted (not shown). Also, although the packaging device 5 described above is provided with a height measuring section 30, the present invention is not limited thereto. For example, if the operator inputs the height (H3) of the contents 90 by operating the control unit 36, the height measuring section 30 may be omitted (not shown).

[0123] Furthermore, in the packaging device 5 described above, the height measuring section 30, the creasing section 31, the dividing section 32, the folding section 33, and the sealing section 34 are fixedly provided, and the packaging box 1 is transported by a conveyor 35. However, the present invention is not limited to this. For example, in a modified packaging device, the conveyor 35 may be omitted, the packaging boxes 1 and 2 may be fixedly arranged (without being moved), and a moving mechanism may be provided to move each of the parts 30 to 34 (not shown). That is, in a modified packaging device, a fixed base (not shown) for fixing the packaging box 1 may be provided, and the moving mechanism may intermittently move each of the parts 30 to 34 on the packaging boxes 1 and 2 fixed to the fixed base.

[0124] The above description of embodiments illustrates one aspect of the packaging box, blank, and method for sealing the packaging box according to the present invention, and the technical scope of the present invention is not limited to the above embodiments. The present invention may be modified, substituted, or transformed in various ways without departing from the spirit of the technical idea, and the claims include all embodiments that may fall within the scope of the technical idea.

[0125] 1, 2 Packaging box 1A, 2A blank 3 Cylindrical body 4 Opening 5 Packaging device 10 First base wall (wall section) 11 Second base wall (wall section) 15 First side wall (side wall) 16 Upper inner flap (upper flap) 17 Second side wall (side wall) 18 Upper outer flap (upper flap) 20, 22 Notch section 21 Cutting line 23 Guide fold line 24 Triangular area 26 Breaking guide line 27 First break line 27A First cut 27B First joint 28 Second break line 28A Second cut 28B Second joint 31 Scoring section 32 Divided section 63 Blade 67 Fracture surface 90 Contents L1 First fold line (vertical ridge) L3 Third fold line (horizontal fold line)

Claims

1. A corrugated cardboard packaging box (1, 2) comprising a cylindrical body (3) with a closed bottom, wherein the height of the cylindrical body can be changed according to the height of the contents (90) by breaking along the longitudinal ridge (L1) of the cylindrical body, wherein the cylindrical body has a cut line (21) cut along the longitudinal ridge at the corner of the opening (4) on the top surface, the longitudinal ridge is excluding the lead crease that forms the perforation, the cut line is formed above the position that will be the maximum height (H1) of the packaging box after sealing, and the crushing ratio (Z [mN / (m・Pa)]) of the corrugated cardboard sheet, which is the ratio of the vertical compressive strength (Y [kN / m]) of the corrugated cardboard sheet to the bursting strength (X [kPa]) of the corrugated cardboard sheet constituting the cylindrical body, is 3.9 [mN / (m・Pa)] or more.

2. The packaging box according to claim 1, characterized in that the cylindrical body has notches (20, 22) cut downward from the upper edge of the corner of the opening above the cut line, and the cut line is cut downward from the lower end of the notches.

3. The packaging box according to claim 1, wherein the cylindrical body has a notch (20) cut out above the cut line, which is narrowed downward from the upper edge of the corner of the opening, and the cut line is cut downward from the lower end of the notch.

4. The packaging box according to claim 1, characterized in that the cylindrical body has a pair of guide fold lines (23) formed thereon, which are inclined to move away from each other from the lower end of the cut line toward the upper edge of the opening.

5. The packaging box according to claim 1, characterized in that a triangular region enclosed by a pair of imaginary lines that are inclined to separate from each other from the lower end of the cut line toward the upper edge of the opening is flattened in the cylindrical body.

6. The packaging box according to claim 1, wherein the cylindrical body further has a breaking guide line (26) that weakens the upper portion of the vertical ridge, the breaking guide line has a first breaking line (27) formed between the corner of the opening and a position corresponding to the maximum height of the packaging box after sealing, and the first breaking line is a perforation in which a first cut (27A) and a first joint (27B) are arranged alternately.

7. The packaging box according to claim 6, wherein the breakage guide line further comprises a second breakage line (28) formed between the lower end of the first breakage line and a position corresponding to the minimum height of the packaging box after sealing, the second breakage line being a perforation in which a second cut (28A) and a second seam (28B) are arranged alternately, and the lengths of the first cut, the first seam, the second cut and the second seam are set such that the second breakage line is less likely to break than the first breakage line.

8. A blank characterized by forming the packaging box described in claim 1.

9. A method for sealing a packaging box, wherein a packaging device (5) changes the height of the contents (90) contained in a corrugated cardboard packaging box (1, 2) including a cylindrical body (3) with a closed bottom, and packages the contents in the packaging box, the packaging device comprising: a scoring section (31) that forms a horizontal fold line (L3) on the wall portion (10, 11) of the cylindrical body according to the height of the contents contained inside the cylindrical body through an opening (4) on the top surface of the cylindrical body, and divides the wall portion into a side wall (15, 17) and an upper flap (16, 18); and a dividing section (32) that presses a non-sharp, plate-shaped blade (63) against the corner of the opening and lowers it along the vertical ridge (L1) of the cylindrical body from the upper end of the vertical ridge to the horizontal fold line, thereby dividing the upper flap which is connected via the vertical ridge, The cylindrical body has a cut line (21) cut along the vertical ridge at the corner of the opening, the vertical ridge is excluding the lead crease that forms the perforations, the cut line is formed above the position that will be the maximum height (H1) of the packaging box after sealing, the crushing ratio (Z [mN / (m·Pa)]) of the corrugated cardboard sheet, which is the ratio of the vertical compressive strength (Y [kN / m]) of the corrugated cardboard sheet to the bursting strength (X [kPa]) of the corrugated cardboard sheet constituting the cylindrical body, is 3.9 [mN / (m·Pa)] or more, the creasing portion forms the horizontal fold line on the wall of the cylindrical body, and the creasing process divides the wall into the side wall and the upper flap, A method for sealing a packaging box, characterized in that the dividing section comprises a dividing step in which the dividing section lowers the blade from the upper end of the vertical ridge to the horizontal fold line, thereby dividing the upper flap which is connected via the vertical ridge.

10. The method for sealing a packaging box according to claim 9, characterized in that the cylindrical body has a breaking guide line (26) that weakens the upper portion of the longitudinal ridge line including the boundary of the adjacent upper flap, the breaking guide line has a first breaking line (27) formed between the corner of the opening and a position corresponding to the maximum height (H1) of the sealed packaging box, the first breaking line is a perforation in which first cuts (27A) and first joints (27B) are arranged alternately, and the length (H5) of the first cut is 1 / 8 or more of the crossing distance (H6), which is the maximum height of the blade that contacts the broken surface of the first breaking line.

11. The method for sealing a packaging box according to 10, wherein the breakage guide line further comprises a second breakage line (28) formed between the lower end of the first breakage line and a position corresponding to the minimum height of the packaging box after sealing, the second breakage line being a perforation in which a second cut (28A) and a second joint (28B) are arranged alternately, and the lengths of the first cut, the first joint, the second cut, and the second joint are set such that the second breakage line is less likely to break than the first breakage line.

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