JP7763991B1 - How to seal a packaging box - Google Patents

Abstract

A method for sealing a packaging box that can suppress a decrease in compressive strength is provided.
[Solution]
This is a method for sealing a cardboard packaging box 2 in which a packaging device changes the height of a cylindrical body 3 for packaging. The packaging device includes a scoring section that forms a third fold line L3 (horizontal fold line) in the base wall 11 of the cylindrical body 3, and a dividing section that divides the upper flap 18 with a blade 63 formed in a non-sharp plate shape. The cylindrical body 3 has score lines cut along the vertical ridge lines and break assist lines 26 that weaken the upper portion of the vertical ridge lines. The cardboard sheet has a compression-to-break ratio (Z [mN/(m Pa)]) of 3.9 [mN/(m Pa)] or more. The break assist lines 26 have first break lines 27 formed between the corners of the opening and a position corresponding to the maximum height. The first break lines 27 are perforations in which first cuts and first seams are arranged alternately. The length of the first cuts is 1/8 or more of the intersection distance (H6), which is the maximum height of the blade 63 that contacts the fracture surface of the first break line 27.
[Selected figure] Figure 23

Description

The present invention relates to a method for sealing a cardboard packaging box in which the height of the cylinder can be adjusted depending on the height of the contents.

A box (box sheet) is known in which a pair of first side panels and a pair of second side panels form a rectangular tubular body, and multiple intermediate easy-fold lines that cross the pair of first side panels and the pair of second side panels are formed at intervals in the vertical direction (Patent Document 1). At the boundary between the first and second side panels, vertical easy-break lines (perforations) are formed, connecting the upper edge of the body to the multiple intermediate easy-fold lines. The height of the box can be changed by breaking the body along the vertical easy-break lines up to any intermediate easy-fold line and folding the upper portions of the broken first and second side panels along the intermediate easy-fold lines.

Utility Model Registration No. 3244633

In the above-mentioned box, for example, if the body is broken along the vertical easy break line up to the uppermost intermediate easy fold line, and the tops of the first and second side panels are folded at the uppermost intermediate easy fold line, the other intermediate easy fold lines, excluding the uppermost intermediate easy fold line, will remain on the first and second side panels. This makes the first and second side panels more likely to bend along the other intermediate easy fold lines, resulting in a problem of reduced compressive strength of the box when sealed.

The present invention takes the above circumstances into consideration and provides a method for sealing packaging boxes that can prevent a decrease in compressive strength.

The present invention relates to a method for sealing a packaging box, in which a packaging device adjusts the height of a cardboard packaging box including a cylindrical body with a closed bottom in accordance with the height of the contents contained in the packaging box, and packages the contents in the packaging box. The packaging device includes a scoring unit that forms horizontal fold lines in the wall of the cylindrical body according to the height of the contents contained inside the cylindrical body through an opening in the top surface of the cylindrical body, dividing the wall into side walls and an upper flap, and a dividing unit that presses a blade formed in a blunt plate shape against the corner of the opening and moves it down along the vertical ridge line from the upper end of the vertical ridge line of the cylindrical body to the horizontal fold line, thereby dividing the upper flap connected via the vertical ridge line. The cylindrical body has a score line cut along the vertical ridge line at the corner of the opening, and a dividing unit that divides the upper flap adjacent to the vertical ridge line. and a break assist line that weakens the upper portion of the vertical ridge line including the boundary between the opening and the box; the score line is formed above the position that will be the maximum height of the packaging box after sealing; the cardboard sheet has a compression-break ratio (Z [mN/(m Pa)]), which is the ratio of the vertical compressive strength (Y [kN/m]) of the cardboard sheet that makes up the cylindrical body to the bursting strength (X [kPa]) of the cardboard sheet, of 3.9 [mN/(m Pa)] or more; the break assist line has a first break line formed between the corner of the opening and a position that corresponds to the maximum height of the packaging box after sealing; the first break line is a perforation in which first cuts and first seams are arranged alternately; and the length of the first cut is 1/8 or more of the intersection distance, which is the maximum height of the blade that contacts the broken surface of the first break line.

In this case, the break assist line may further include a second break line formed between the lower end of the first break line and a position corresponding to the minimum height of the packaging box after sealing.

In this case, the second break line is a perforation in which second cuts and second seams are arranged alternately, and the lengths of the first cuts, first seams, second cuts, and second seams are preferably set so that the second break line is less likely to break than the first break line.

This invention makes it possible to prevent a decrease in the compressive strength of packaging boxes.

1 is a side view schematically showing a packaging device according to an embodiment of the present invention; 1 is a plan view showing a blank for a packaging box according to a first embodiment of the present invention; 1 is a perspective view showing a temporarily assembled state of a packaging box according to a first embodiment of the present invention. FIG. 1 is a plan view showing a packaging box and a creasing section of a packaging device according to a first embodiment of the present invention; 1 is a perspective view showing a part of a creasing unit of a packaging device according to an embodiment of the present invention. 1 is a plan view showing a dividing portion of a packaging box and a packaging device according to a first embodiment of the present invention. FIG. 1 is a perspective view showing a part of a dividing portion of a packaging device according to an embodiment of the present invention. FIG. 2 is a perspective view of the packaging box according to the first embodiment of the present invention, showing a state in which a third fold line has been formed. 10A and 10B are side views illustrating a cutting process performed by the packaging device according to one embodiment of the present invention. FIG. 10 is a side view showing a state in which the cutting process by the packaging device according to one embodiment of the present invention has been completed. FIG. 10 is a plan view showing a state in which a cutting process by the packaging device according to one embodiment of the present invention has been completed. 1 is a perspective view showing a sealed state (maximum height) of a packaging box according to a first embodiment of the present invention; FIG. 1 is a perspective view showing a sealed state (minimum height) of a packaging box according to a first embodiment of the present invention; FIG. FIG. 10 is a plan view showing a blank for a packaging box according to a first modified example of the first embodiment of the present invention. FIG. 10 is a plan view showing a blank for a packaging box according to a second modified example of the first embodiment of the present invention. FIG. 10 is a plan view showing a blank for a packaging box according to a third modified example of the first embodiment of the present invention. FIG. 10 is a plan view showing a blank for a packaging box according to a fourth modified example of the first embodiment of the present invention. FIG. 10 is a plan view showing a blank for a packaging box according to a fifth modified example of the first embodiment of the present invention. FIG. 1 is a perspective view showing a test cylinder used in a test to verify the effectiveness of the compression-break ratio set for the cardboard sheets that make up the packaging box according to the first embodiment of the present invention. 1 is a table showing the results of a test verifying the effectiveness of the compression-breaking ratio set for the cardboard sheets that make up the packaging box according to the first embodiment of the present invention. FIG. 10 is a plan view showing a blank for a packaging box according to a second embodiment of the present invention. FIG. 10 is a perspective view showing a packaging box according to a second embodiment of the present invention in a temporarily assembled state. FIG. 10 is a side view showing a packaging box and a blade of a packaging device according to a second embodiment of the present invention. 10 is a perspective view showing how a cut groove formed in a packaging box (cylindrical body) widens from above toward below. FIG.

Embodiments of the present invention will now be described with reference to the accompanying drawings. Note that Fr, Rr, L, R, U, and D shown in the drawings indicate front, rear, left, right, top, and bottom. The front-to-back, left-to-right, and top-to-bottom directions are perpendicular to one another. Terms indicating directions and positions are used in this specification for the convenience of explanation and do not limit the technical scope of the present invention. Furthermore, terms indicating directions and positions are based on directions and positions when the packaging device is in use.

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

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 the function of changing the height of the packaging box 1 depending on the height of the contents 90. In other words, the packaging device 5 can package (pack) 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) areas (footprints) by changing the height of each packaging box 1.

[First embodiment: packaging box]
A packaging box 1 in which the height of the cylindrical body 3 is adjusted by a packaging device 5 according to the height of the contents 90 will be described. The packaging box 1 is formed from a blank 1A shown in FIG. 2. The blank 1A is formed by punching out a single sheet of cardboard using a die or the like. The cardboard is, for example, double-sided cardboard in which a front liner 9B (surface) and a back liner 9C (back) are bonded to a corrugated core 9A. Note that in this specification, the direction parallel to the core 9A of the cardboard is referred to as the "corrugation direction," and the direction perpendicular to the corrugation direction is referred to as the "flow direction." In the drawings, "X" indicates the "corrugation direction," and "Y" indicates the "flow direction." In addition, in this specification, when the front liner 9B and the back liner 9C are collectively described, they may be simply referred to as "liners 9B, 9C."

[blank]
As shown in FIG. 2 , the blank 1A has a pair of first foundation walls 10, a pair of second foundation walls 11, a pair of lower inner flaps 13, and a pair of lower outer flaps 14. Because the pair of first foundation walls 10 (wall portions) have substantially the same shape, this specification will mainly describe one first foundation wall 10. For the same reason, this specification will mainly describe one second foundation wall 11 (wall portion), one lower inner flap 13, and one lower outer flap 14. Furthermore, when the first foundation wall 10 and the second foundation wall 11 are collectively described, they may be simply referred to as the "foundation walls 10, 11." The two-dot chain lines shown in FIG. 2 and FIGS. 14 to 18 (described later) are imaginary lines used to explain the maximum height (H1) and minimum height (H2) of the packaging box 1.

<First foundation wall, second foundation wall>
The first foundation wall 10 is formed in a substantially rectangular shape with its long side in the step direction. The second foundation wall 11 has the same dimension in the step direction as the first foundation wall 10 and is formed in a substantially rectangular shape with its long side in the flow direction. A pair of first foundation walls 10 and a pair of second foundation walls 11 are alternately arranged in the flow direction and connected via a first fold line L1 (a vertical ridge line (e.g., a general-purpose crease)). A joint piece 12 is connected to one end of the second foundation wall 11 in the flow direction via the first fold line 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 joint pieces 12 to form the tubular body 3 (see FIG. 3).

(Notch)
At one end (top end) of the blank 1A in the step direction, notches 20 are recessed at the corners of the foundation walls 10, 11 at both ends in the flow direction and at the boundary (first fold line L1) between the first foundation wall 10 and the second foundation wall 11. The notches 20 are cut out in a shape that gradually narrows from one end (top end) of the foundation walls 10, 11 in the step direction toward the other end (downward). Specifically, the notches 20 are formed in a roughly V-shape. A portion of the notch 20 formed in the first foundation wall 10 is cut out so as 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) formed between the hypotenuse of the notch 20 formed in the first foundation wall 10 and an extension of the first fold line L1 is larger than the angle (β) formed between the hypotenuse of the notch 20 formed in the second foundation wall 11 and the extension line.

The cutouts 20 are not formed in a perfect V-shape, bending at a single point at the bottom, but rather in a bathtub shape (inverted trapezoid) with one side extending in the flow direction at the bottom. The width (dimension in the flow direction) of the bottom of the cutouts 20 is set to 4 mm or more and 10 mm or less. The cutouts 20 formed at the corners of the foundation walls 10, 11 at both ends in the flow direction are shaped like two separate cutouts 20, and will have approximately the same shape as the other cutouts 20 when the cylindrical body 3 is formed. The cutouts 20 may also be formed in a V-shape, bending at a single point at the bottom (not shown).

(Cutting line)
Near one end (near the upper end) of the first fold line L1 in the corrugation direction, a score line 21 is cut along the first fold line L1 (vertical ridge line). The score line 21 is cut downward from the lower end (the other end in the corrugation direction) of the cutout portion 20. The score line 21 is formed between the lower end of the cutout portion 20 and the upper end of the first fold line L1. The score line 21 is a single cut made by using a blade in the thickness direction of the cardboard. The length of the score line 21 is preferably set to be between 3 mm and 20 mm. The score line 21 is formed above the position that corresponds to the maximum height (H1) of the packaging box 1. The combined length (height) of the cutout portion 20 and the score line 21 in the corrugation direction is preferably set to be shorter than three-quarters 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 FIG. 8 described below). Preferably, the combined height of the notch 20 and the cut line 21 may be set to about half the distance (H4).

<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 fold line L2 (e.g., a general-purpose crease). The lower inner flap 13 has approximately the same dimension in the flow direction as the first foundation wall 10 and is formed in a generally rectangular shape with its long side in the flow direction. The dimension in the step direction (extension dimension) of the lower inner flap 13 is approximately half the dimension in the flow direction 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 fold line L2. The lower outer flap 14 has approximately the same dimension in the flow direction as the second foundation wall 11 and is formed in a generally rectangular shape with its long side in the flow direction. The dimension in the step direction (extension dimension) of the lower outer flap 14 is the same as the extension dimension of the lower inner flap 13.

Note that the first fold line L1 and the second fold line L2 are general-purpose creases, but they are not limited to this. For example, they may be lead creases with perforations formed on general-purpose creases, or any other structure that allows the cardboard sheet to be folded in the desired direction.

[Initial state of packaging box]
Although not shown, the blank 1A is folded flat to form the packaging box 1. 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 approximately 180 degrees along the first fold line L1, and the joining piece 12 is adhered to the back surface (back liner 9C) of the opposite first base wall 10. This completes the packaging box 1's initial double-folded state.

[Temporary assembly of packaging box]
The packaging box 1 in the initial state is temporarily assembled to accommodate an item 90 and be packaged (sealed) by the packaging device 5. Specifically, as shown in Fig. 3, the packaging box 1 in the initial state is raised so that the pair of first foundation walls 10 and the pair of second foundation walls 11 are substantially perpendicular to each other. The pair of first foundation walls 10 and the pair of second foundation walls 11 form a rectangular cylindrical body 3 (not shown) with open upper and lower end faces.

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 leading edges, and the pair of lower outer flaps 14 are layered on the surfaces of the pair of lower inner flaps 13 with their leading edges butted together. Adhesive tape T is attached to the butted portion of the pair of lower outer flaps 14. The lower inner flap 13 and lower outer flaps 14 form the bottom that closes the bottom surface of the cylindrical body 3.

The packaging box 1 is now in a pre-assembled state. In the pre-assembled packaging box 1, the bottom of the cylindrical body 3 is closed, and the opening 4 is open on the top surface of the cylindrical body 3. The cutout 20 is formed in a V-shape that narrows downward from the upper edge of the corner of the opening 4. A score line 21 is cut along the first fold line L1 at the corner of the opening 4 (cutout 20). The packaging box 1, with the contents 90 inside, is introduced into the packaging device 5 (see Figure 1).

[Packaging equipment]
Next, the packaging device 5 will be described with reference to Figures 1 and 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 portion 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 portion of the dividing section 32.

As shown in FIG. 1, the packaging device 5 includes a height measurement unit 30, a creasing unit 31, a separating unit 32, a folding unit 33, and a sealing unit 34. The packaging device 5 also includes a conveyor 35 that intermittently transports the packaging box 1. The packaging device 5 also includes a control unit 36 that appropriately controls the units 30-34 and the conveyor 35. The height measurement unit 30, creasing unit 31, separating unit 32, folding unit 33, and sealing unit 34 are arranged in a line in this order from upstream to downstream in the transport direction of the packaging box 1. The conveyor 35 extends over the entire area of the height measurement unit 30, creasing unit 31, separating unit 32, folding unit 33, and sealing unit 34. In this specification, the terms "upstream" and "downstream" refer to the upstream or downstream direction in the transport direction of the packaging box 1.

<Height measurement unit>
The height measurement unit 30 measures the height of the item 90 contained inside the cylindrical body 3 (provisionally assembled packaging box 1) through an opening 4 on the top surface of the cylindrical body 3. As shown in FIG. 1 , the height measurement unit 30 has a laser light source 30A that emits a band-shaped laser beam toward the item 90 and a light receiving element 30B that receives the light reflected from the surface of the item 90, and measures the height (shape) of the item 90 using the principle of light sectioning. The height measurement unit 30 is electrically connected to the control unit 36 and is driven and controlled by the control unit 36. Light reception information from the light receiving element 30B (measurement results of the height measurement unit 30) is transmitted to the control unit 36.

<Creasing section>
The creasing unit 31 forms a third fold line L3 (horizontal fold line) in the foundation walls 10, 11 (wall portions) of the cylindrical body 3 in accordance with the height of the contained item 90 (see FIG. 8 described below). The creasing unit 31 has a first creasing unit 40 that forms the third fold line L3 in a pair of first foundation walls 10 that form the short side sides of the opening 4, and a second creasing unit 50 that forms the third fold line L3 in a pair of second foundation walls 11 that form the long side sides of the opening 4. The second creasing unit 50 is disposed downstream of the first creasing unit 40 (see FIG. 1).

<First creasing section>
1 , the first creasing unit 40 has two pairs of first arms 41, a first drive unit 42, and a pair of first roller units 43. Since the two pairs of first arms 41 provided corresponding to one first foundation wall 10 have substantially the same structure, this specification will mainly describe one pair of first arms 41. Furthermore, since the pair of first roller units 43 have substantially the same structure, this specification will mainly describe one first roller unit 43.

(First arm, first drive unit)
Each pair of first arms 41 is suspended substantially vertically from a first drive unit 42. The pair of first arms 41 are arranged substantially parallel to each other with a gap in the front-to-rear direction (the conveying direction). The first drive unit 42 raises and lowers the two pairs of first arms 41 as a whole and moves them in the front-to-rear and left-to-right directions (the width direction perpendicular to the conveying direction). The first drive unit 42 also moves the pair of first arms 41 closer to and apart from each other. 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 foundation wall 10 relatively enters between the pair of first arms 41, and the pair of first arms 41 face each other with the first foundation wall 10 interposed therebetween.

(First roller part)
As shown in FIGS. 4 and 5 , the first roller unit 43 includes 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 generally cylindrical (approximately disc-like) shape. 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 foundation wall 10. The pair of first outer rollers 44 are arranged side by side at a distance from each other in the left-right direction (the horizontal direction along the third fold line L3) and are supported by the first bracket 46 to be rotatable about their axes. The first inner roller 45 is attached via the first bracket 46 to the lower end of the inner first arm 41 of the pair of first arms 41 that sandwich the first foundation wall 10. The first inner roller 45 is disposed opposite the pair of first outer rollers 44 and is supported by the first bracket 46 to be rotatable about its axis.

<Second creasing section>
As shown in FIG. 1 , the second creasing unit 50 includes two pairs of second arms 51, a second drive unit 52, and a pair of second roller units 53. Because the two pairs of second arms 51 provided corresponding to one second foundation wall 11 have substantially the same structure, this specification will mainly describe one pair of second arms 51. Because the pair of second roller units 53 have substantially the same structure, this specification will mainly describe one second roller unit 53. Furthermore, FIG. 1 illustrates only the left second arm 51 and the left second roller unit 53. Because the second roller units 53 and the like have substantially the same structure as the first roller units 43 and the like, the second roller units 53 and the like will be described with reference to FIG. 5 , which was used to describe the first roller units 43 and the like.

(Second arm, second drive unit)
The pair of second arms 51 are each suspended substantially vertically from a second drive unit 52. The pair of second arms 51 are arranged substantially parallel to each other with a gap between them in the left-right direction. The second drive unit 52 raises and lowers the two pairs of second arms 51 as a whole and moves them in the front-back and left-right directions. The second drive unit 52 also moves the pair of second arms 51 closer to and apart from each other. The second drive unit 52 is electrically connected to the control unit 36 and is drive-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 foundation wall 11 relatively enters between the pair of second arms 51, and the pair of second arms 51 face each other with the second foundation wall 11 between them.

(Second roller section)
As shown in FIGS. 4 and 5 , the second roller unit 53 includes 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 generally cylindrical (approximately disc-like) shape. 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 foundation wall 11. The pair of second outer rollers 54 are arranged side by side with a gap in the front-to-rear direction (the horizontal direction along the third fold line L3) and are supported by the second bracket 56 to be rotatable about their axes. The second inner roller 55 is attached via the second bracket 56 to the lower end of the inner second arm 51 of the pair of second arms 51 that sandwich the second foundation wall 11. The second inner roller 55 is disposed opposite the pair of second outer rollers 54 and is supported by the second bracket 56 to be rotatable about its axis.

(Details of outer and inner rollers)
4 and 5, the first roller unit 43 and the second roller unit 53 will be described in detail. In this specification, when the first roller unit 43 and the second roller unit 53 are described collectively, they may be simply referred to as "roller units 43, 53," when the first outer roller 44 and the second outer roller 54 are described collectively, they may be simply referred to as "outer rollers 44, 54," and when the first inner roller 45 and the second inner roller 55 are described collectively, they may be simply referred to as "inner rollers 45, 55."

The outer rollers 44, 54 and the 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 the inner rollers 45, 55 are formed in a generally circular disk shape with a diameter of 20 mm. The outer rollers 44, 54 and the inner rollers 45, 55 each have a generally trapezoidal protrusion extending radially outward. The spacing (center distance) between the pair of first outer rollers 44 and the spacing (center distance) between the pair of second outer rollers 54 are the same as the diameter, approximately 20 mm. The diameters of the outer rollers 44, 54 and the inner rollers 45, 55 are preferably set in the range of 5 mm to 60 mm. The spacing between the pair of outer rollers 44, 54 may be changed to match the diameters of the pair of outer rollers 44, 54. The outer rollers 44, 54 and the inner rollers 45, 55 may also have different diameters.

Furthermore, the inner rollers 45, 55 are positioned opposite the outer rollers 44, 54 at a position offset downward relative to the outer rollers 44, 54. Specifically, the inner rollers 45, 55 (center of thickness) are positioned approximately 2 mm below the outer rollers 44, 54 (center of thickness). The amount of offset between the inner rollers 45, 55 and the outer rollers 44, 54 may be set, for example, in the range of 0 mm to 6 mm (the thickness of the protruding portions of the inner rollers 45, 55, etc.).

As shown in FIG. 4, the roller units 43, 53 of the creasing unit 31 sandwich the foundation walls 10, 11 of the cylindrical body 3 and move laterally (see the thick arrows in FIG. 4) while rolling on both the front and back surfaces of the foundation walls 10, 11, forming the third fold line L3. The first roller unit 43 forms the third fold line L3 in a pair of first foundation walls 10 that face each other in the front-to-back direction (first direction) when viewed from above the cylindrical body 3. The second roller unit 53 forms the third fold line L3 in a pair of second foundation walls 11 that face each other in the left-to-right direction (second direction perpendicular to the first direction) when viewed from above the cylindrical body 3. The outer rollers 44, 54 rotate around their axes while their protruding portions are pressed against the surfaces of the foundation walls 10, 11. The inner rollers 45, 55 rotate around their axes while their protruding portions are pressed against the back surfaces of the foundation walls 10, 11. The inner rollers 45, 55 are positioned so that they contact a pair of outer rollers 44, 54, sandwiching the foundation walls 10, 11 between them. The third fold line L3 is a line that crushes (depresses) the foundation walls 10, 11 (corrugated cardboard) in the thickness direction from both the front and back sides. Specifically, the depression in the back surface (back liner 9C) of the foundation walls 10, 11 is located slightly lower than the depression in the front surface (front liner 9B) of the foundation walls 10, 11.

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

<Divided part>
The dividing unit 32 makes cuts along the first fold line L1 (vertical ridge line) from the four corners of the opening 4 of the temporarily assembled packaging box 1 to the cylindrical body 3. As shown in FIGS. 1 and 6 , the dividing unit 32 has four dividing arms 61, a dividing drive unit 62, four blades 63, and eight guide rollers 64. Note that the four dividing arms 61 and the four blades 63 are provided corresponding to the four corners of the opening 4, and therefore, this specification will mainly describe one dividing arm 61 and one blade 63 corresponding to one corner. Also, the eight guide rollers 64 are provided corresponding to the four corners of the opening 4, and therefore, this specification will mainly describe two guide rollers 64 corresponding to one corner.

(Separating arm, separating drive unit)
As shown in FIG. 1 , the separating arms 61 are suspended substantially vertically from the separating drive unit 62. The four separating arms 61 are arranged to face the outside of the four corners of the opening 4 when viewed from above (see FIG. 6 ). The separating drive unit 62 raises and lowers the four separating arms 61 as a whole and moves them in a direction (radial direction RD) along a line that bisects the corners (substantially right angles) of the cylindrical body 3 when viewed from above. The separating 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" refers to a direction inclined at approximately 45 degrees with respect to the first foundation wall 10 and second foundation wall 11 of the packaging box 1 (cylindrical body 3) when viewed from above (see FIG. 6 ).

(blade)
As shown in Figures 6 and 7, one end of each blade 63 is fixed to the cutting arm 61. The blade 63 is made of a synthetic resin, such as monomer cast nylon, and is formed into a roughly rectangular plate shape with a thickness of approximately 5 mm. That is, the blade 63 is formed into a blunt plate shape. Here, "blunt" refers to a state (state) in which the blade 63 is so blunt that it cannot cut (or move while cutting) cardboard sheets (the material constituting the packaging box 1). The four blades 63 are inclined along the radial direction RD when viewed from above (see Figure 6), and are inclined downward from the outside to the inside of the cylindrical body 3 when viewed from the side (front and side) (see Figure 7). That is, the four blades 63 extend diagonally downward from the four cutting arms 61 toward the inside. A pulling-out assist surface 63A is formed at the tip of each blade 63, with the upper corners cut off to form a roughly vertical surface (see Figure 7). The blade 63 has a tapered portion 63B formed at its lower edge, which gradually becomes thinner toward the lower end (packaging box 1) (see FIG. 7). The tip (lower end) of the tapered portion 63B is not sharp and has a slight thickness. The blade 63 is inclined with the tapered portion 63B facing downward (toward the packaging box 1).

As will be described in detail below, the separating unit 32 separates the top flaps 16, 18 connected via the first fold line L1 by pressing the blade 63 against the corner of the opening 4 of the cylindrical body 3 and descending along the first fold line L1 from the top end of the first fold line L1 (vertical ridge line) of the cylindrical body 3 to the third fold line L3. Note that, in this specification, "breaking" means cutting something together, specifically meaning that the corrugated cardboard core 9A and liners 9B, 9C are torn (ripped). "Separating" means cutting something together and separating it, specifically meaning that the cardboard (top flaps 16, 18) are torn (torn) and separated. In other words, in this specification, "breaking" and "separating" do not mean cutting the cardboard with a sharp blade or the like (moving while cutting), but rather mean tearing a single piece of material while locally destroying it.

(Guide roller)
As shown in Figures 6 and 7, two guide rollers 64 are attached to the lower part of the cutting arm 61 via roller arms 65. The guide rollers 64 are supported by the roller arms 65 to be rotatable about their axes at positions below the blade 63. The guide rollers 64 are made of a synthetic resin such as monomer cast nylon and are formed in a generally cylindrical (approximately disk-like) shape. The two guide rollers 64 are supported so that their rotation axes are perpendicular to each other. During the process of lowering the blade 63, the two guide rollers 64 rotate while contacting the surfaces of the upper flaps 16, 18 connected via the first fold line L1 (see Figure 6).

<Folding section>
1, the folding unit 33 has a pair of inner folding arms 70 that fold the pair of upper inner flaps 16 along the third fold line L3, an outer folding arm 71 that folds one of the pair of upper outer flaps 18 along the third fold line L3, and a folding drive unit 72 that drives the inner folding arm 70 and the outer folding arm 71. The folding drive unit 72 is electrically connected to the control unit 36 and is drive-controlled by the control unit 36.

<Sealing section>
The sealing unit 34 has a sealing folding arm 80 that folds the other of the pair of upper outer flaps 18 along the third fold line L3, an adhering unit 81 that applies adhesive tape T to fix the other upper outer flap 18 to one upper outer flap 18, and a sealing drive unit 82 that drives the sealing folding arm 80 and the adhering unit 81. The sealing drive unit 82 is electrically connected to the control unit 36 and is driven and controlled by the control unit 36.

<Conveyor>
The conveyor 35 has multiple 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 belt (neither of which is shown). As each roller is driven to rotate about its axis, the packaging box 1 moves downstream in the conveying direction. The conveyor 35 also has multiple positioning holders (not shown) that hold the conveyed packaging box 1 in predetermined positions set so that the operations of each of the sections 30 to 34 are performed appropriately. The drive source and the positioning holders are electrically connected to the control section 36 and are drive-controlled by the control section 36.

<Control unit>
The control unit 36 includes a memory unit that stores programs, data, etc.; a calculation processing unit that executes calculations according to the programs, etc.; and a communication unit that is communicatively connected to each of the units 30-34 and the conveyor 35. The memory unit, calculation processing unit, and communication unit are electrically connected to each other and are configured to be able to communicate with each other. The memory unit includes a storage medium such as a read-only memory (ROM) or a random access memory (RAM), and the calculation processing unit includes a central processing unit (CPU). The control unit 36 may also include an operation terminal (not shown) that allows an operator to input various operations and check output results from the control unit 36. The memory unit may also pre-store data on the dimensions (length, width, height, etc.) of the temporarily assembled packaging box 1 and various parameters required for control. The control unit may also be implemented by a logic circuit (hardware) formed on an integrated circuit or the like instead of a CPU.

Note that examples of actuators that can be used for the first drive unit 42, second drive unit 52, cutting drive unit 62, folding drive unit 72, and sealing drive unit 82 include electric motors, servo motors, linear motors, solenoids, and piston-cylinders. The first drive unit 42, second drive unit 52, cutting drive unit 62, folding drive unit 72, and sealing drive unit 82 may also include a drive transmission mechanism such as a gear or pulley (belt) that transmits the power of the actuator to the driven object (not shown). These drive units 42, 52, 62, 72, 82, and control unit 36 are connected to a power supply means (not shown).

[Operation of packaging device]
Next, the operation of the packaging device 5 (a method for sealing the packaging box 1) will be described with reference to Figures 1, 4, 6, and 8 to 13. Figure 8 is a perspective view showing the packaging box 1 after the third fold line L3 has been formed. Figure 9 is a side view illustrating the dividing process. Figure 10 is a side view showing the state after the dividing process has been completed. Figure 11 is a plan view showing the state after the dividing process has been completed. Figure 12 is a perspective view showing the packaging box 1 in a sealed state (maximum height (H1)). Figure 13 is a perspective view showing the packaging box 1 in a sealed state (minimum height (H2)).

First, the worker places the contents 90 in the pre-assembled packaging box 1, places it at the most upstream position on the conveyor 35, and operates the control unit 36 to activate the packaging device 5.

<Height measurement process>
The conveyor 35 transports the packaging box 1 to the height measurement unit 30, where the packaging box 1 is held (temporarily stopped) by a positioning and holding unit. As shown in FIG. 1 , the height measurement unit 30 emits laser light from a laser light source 30A toward the contents 90 in the packaging box 1, and receives the light reflected from the surface of the contents 90 with a light receiving element 30B (height measurement process). The light reception data (measurement results of the height measurement unit 30) from the light receiving element 30B is transmitted to the control unit 36, which calculates the height (H3) of the contents 90 in the packaging box 1 based on the measurement results of the height measurement unit 30 (see FIG. 8 ). When multiple contents 90 of different heights are contained in the packaging box 1, the height (H3) of the tallest contents 90 is calculated as the height of the contents 90. The control unit 36 also calculates the distance (H4) from the upper end of the cylindrical body 3 (foundation walls 10, 11) of the packaging box 1 to the top of the contents 90 (height (H0) of the foundation walls 10, 11 - height (H3) of the contents 90) (see FIG. 8), and calculates the amount of descent of each arm 41, 51, 61 based on this distance (H4). The amount of descent of each arm 41, 51, 61 is set to be slightly higher than the height (H3) of the contents 90 so that the roller units 43, 53 and the blade 63 do not interfere with the contents 90. The amount of descent of each arm 41, 51, 61 may be calculated, for example, as the drive time of each drive unit 42, 52, 62 or the rotation angle of the output shaft.

<Insertion process>
After measuring the height of the contents 90, the creasing section 31 forms a third fold line L3 on the foundation walls 10, 11 of the cylindrical body 3 based on the measurement results of the height measuring section 30, and divides the foundation walls 10, 11 into side walls 15, 17 and upper flaps 16, 18 (crissing process).

Specifically, the conveyor 35 transports the packaging box 1 to the first creasing unit 40, where the packaging box 1 is held by the positioning and holding unit. The two pairs of first arms 41 (first roller units 43) of the first creasing unit 40 are positioned, for example, above the right ends of the pair of first base walls 10 of the packaging box 1 (see Figures 1 and 4). The first driving unit 42 of the first creasing unit 40 lowers the two pairs of first arms 41 (first outer rollers 44, first inner rollers 45) by a calculated amount. The first base wall 10 of the packaging box 1 enters relatively between the pair of descending first arms 41. Next, the first driving unit 42 moves the pair of first arms 41 in a direction approaching 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, while keeping the first foundation wall 10 sandwiched between the pair of first outer rollers 44 and first inner rollers 45, the first drive unit 42 moves the pair of first arms 41 (first roller units 43) approximately horizontally from right to left (see the thick arrows in FIG. 4). As a result, a third fold line L3 that separates the first side wall 15 and the upper inner flap 16 is formed in the first foundation wall 10 (see FIG. 8). After the third fold line L3 is formed, the first drive unit 42 returns (raises) the first arm 41 (first outer roller 44, first inner roller 45) to its initial position.

Next, the conveyor 35 transports the packaging box 1 to the second creasing unit 50, where the packaging box 1 is held by the positioning and holding unit. The two pairs of second arms 51 (second roller units 53) of the second creasing unit 50 are positioned, for example, above the rear ends (upstream ends) 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 unit 50 lowers the two pairs of second arms 51 by the calculated lowering 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 in a direction approaching 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 units 53) approximately horizontally from rear to front while keeping the second foundation wall 11 sandwiched between the pair of second outer rollers 54 and second inner rollers 55 (see the thick arrows in FIG. 4). As a result, a third fold line L3 that separates the second side wall 17 and the upper outer flap 18 is formed in the second foundation wall 11 (see FIG. 8). After the third fold line L3 is formed, the second drive unit 52 returns (raises) the second arms 51 (second outer rollers 54, second inner rollers 55) to their initial positions.

In Figure 8, as an example, the third fold line L3 is formed at a position corresponding to the maximum height (H1) of the packaging box 1 after sealing. The maximum height (H1) of the packaging box 1 (see also Figure 2) is the height when the distance (H4) obtained by subtracting the maximum height (H3) of the contents 90 from the height (H0) of the foundation walls 10, 11 is approximately equal to half the width (dimension in the flow direction) of the first foundation wall 10. In contrast, the minimum height (H2) of the packaging box 1 (see also Figure 2) is the height when the distance (H4) is approximately equal to the width of the first foundation wall 10. The third fold line L3 may be formed horizontally (left-right and front-back directions) within the range between the minimum height (H2) and the maximum height (H1) of the packaging box 1. The third fold line L3 is formed on the foundation walls 10, 11 in a range excluding the radii of the outer rollers 44, 54 and inner rollers 45, 55 from both lateral ends. In other words, there are small areas near both lateral (left-right and front-back) ends of the foundation walls 10, 11 where the third fold line L3 is not formed. This area where the third fold line L3 is not formed becomes smaller as the diameter (radius) of the outer rollers 44, 54 and inner rollers 45, 55 becomes smaller.

<Cutting process>
After forming the third fold line L3 in the foundation walls 10, 11, the dividing unit 32 makes cuts in the upper side of the four corners of the cylindrical body 3 based on the measurement results of the height measuring unit 30 (dividing process).

Specifically, the conveyor 35 transports the packaging box 1 to the separating unit 32, where it is held by the positioning and holding unit. The four separating arms 61 of the separating unit 32 are positioned outside the four corners of the opening 4 of the packaging box 1 when viewed from above (see Figure 6). The separating drive unit 62 of the separating unit 32 lowers the four separating arms 61 (blades 63, etc.) by a calculated amount (see the hollow arrows in Figure 9). At this time, even if the blades 63 are slightly misaligned with the corners of the opening 4, the blades 63 descend while being guided by the notch 20 of the cylindrical body 3 (while sliding against the hypotenuse of the V) and bite into the cut line 21. A tapered portion 63B is formed on the lower edge of the blade 63, making it easier for the blades 63 to bite into the cut 23A. The blade 63 descends to the position where the third fold line L3 is formed, while breaking the cardboard (core 9A, front liner 9B, back liner 9C) along the first fold line L1. The blade 63 is held in an inclined position and descends while sandwiching the top flaps 16, 18 between itself and two guide rollers 64 (see Figures 6 and 9). The two guide rollers 64 support the top flaps 16, 18 that have been separated by the blade 63 and are attempting to open outward.

As shown in Figures 10 and 11, the separating unit 32 (separating drive unit 62) lowers the blade 63 while maintaining the inclined position, and then moves the blade 63 substantially horizontally to pull it outward (in the radial direction RD) from the cylindrical body 3 while maintaining the inclined position. The blade 63 has a pull-out assist surface 63A that is substantially parallel to the broken first fold line L1. This reduces the amount of movement in the pull-out direction (outward in the radial direction RD) compared to when the blade 63 is simply a rectangular plate. Once the blade 63 is pulled outward from the cylindrical body 3, the separating drive unit 62 returns (raises) the separating arm 61 (blade 63, etc.) to its initial position.

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), dividing the upper flaps 16, 18, which are connected via the first fold line L1, along the first fold line L1. A cut 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 top end of the cylindrical body 3 (the 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 blade 63 breaks the first fold line L1 within the range from the top end of the cylindrical body 3 (the upper edge of the opening 4) to a position corresponding to the minimum height (H2) of the packaging box 1. In a packaging box 1 with a minimum height (H2), the side walls 15, 17 are connected along approximately the lower half of the first fold line L1.

<Folding process>
After the upper flaps 16, 18 are separated, the conveyor 35 transports the packaging box 1 to the folding unit 33, where the packaging box 1 is held by a positioning and holding unit. The folding unit 33 folds the upper flaps 16, 18 separated by the separating unit 32 toward the inside of the cylindrical body 3 along a third fold line L3 (horizontal fold line) (folding process). The folding drive unit 72 of the folding unit 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 an outer folding arm 71 to fold one (e.g., the left) upper outer flap 18 along the third fold line L3 (see FIG. 1). One upper outer flap 18 is superimposed on the surface of the pair of upper inner flaps 16 (see FIG. 12 or 13).

<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 unit 34, where the packaging box 1 is held by a positioning and holding unit. The sealing unit 34 seals the packaging box 1 (sealing process). The sealing drive unit 82 of the sealing unit 34 rotates the sealing folding arm 80 to fold the other upper outer flap 18 along the third fold line L3 (see FIG. 1). Here, when the sealed packaging box 1 reaches its maximum height (H1), the pair of upper outer flaps 18 separated along the first fold line L1 will have their leading ends butted against each other (see FIG. 12). On the other hand, when the packaging box 1 reaches a height other than the maximum height (H1) (e.g., the minimum height (H2)), the leading end of the other upper outer flap 18 will overlap the surface of one of the upper outer flap 18 (see FIG. 13). The attachment portion 81 of the sealing portion 34 attaches adhesive tape T along the butt joint of a pair of upper outer flaps 18 (see Figure 12), or attaches adhesive tape T along the tip of the other upper outer flap 18 (see Figure 13).

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).

In the packaging device 5 described above, the blade 63, which is formed as a blunt plate, is configured to break the cylindrical body 3 along the first fold line L1. With this configuration, even if the blade 63 comes into contact with the cylindrical body 3 at a position offset from the top corner (first fold line L1), because it is not a sharp blade, it is prevented from cutting through a position offset from the first fold line L1. Furthermore, because the blade 63 is not sharp but is formed as a strong plate, damage and wear to the blade 63 can be reduced. This prevents problems such as parts of the blade 63 breaking off and becoming mixed in with the packaging box 1. Furthermore, because the frequency of blade 63 replacement can be reduced, the running costs of the packaging device 5 can be kept low.

Furthermore, with the packaging device 5 described above, the blade 63 descends while being maintained in an inclined position, thereby reducing contact resistance between the blade 63 and the vertical ridge line (first fold line L1) of the cylindrical body 3. This allows the descending blade 63 to cleanly break the vertical ridge line (first fold line L1) of the cylindrical body 3 without crushing the cross section of the cylindrical body 3 along the first fold line L1.

If, after the first fold line L1 breaks, the lowered blade 63 is raised and pulled out of the cylindrical body 3, there is a risk that the packaging box 1 will shift position on the conveyor 35 due to frictional resistance between the broken 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 been lowered to a predetermined position, is held in an inclined position and pulled out approximately horizontally to the outside of the cylindrical body 3 (see Figures 10 and 11), thereby preventing the packaging box 1 from shifting position on the conveyor 35.

In addition, in the packaging device 5 described above, as the blade 63 descends, the guide rollers 64 rotate while contacting the surfaces of the adjacent upper flaps 16, 18 across the first fold line L1 (see Figure 9). With this configuration, the guide rollers 64 can support the upper flaps 16, 18 that tend to collapse outward when the descending blade 63 tears the first fold line L1. This allows the descending blade 63 to align with the vertical ridge line (first fold line L1) of the cylindrical body 3.

In the packaging box 1 according to the first embodiment described above, the packaging device 5 forms a third fold line L3 in the foundation walls 10, 11 (wall portions) according to the height of the contents 90, and then the cylindrical body 3 is torn from the top of the first fold line L1 (vertical ridge line) to the third fold line L3. This configuration eliminates the need to form multiple third fold lines L3 in the foundation walls 10, 11 in advance, and allows the side walls 15, 17 without the third fold line L3 to be formed after the packaging box 1 is sealed. This prevents a decrease in the compressive strength of the sealed packaging box 1. Furthermore, because the first fold line L1 (vertical ridge line) of the cylindrical body 3 is not weakened by perforations or the like, the corners of the cylindrical body 3 can reliably support a load.

Furthermore, with the packaging box 1 according to the first embodiment, the notch 20 is recessed in a V-shape at the corner of the opening 4, so that the blade 63 can enter the notch 20 even if it is positioned slightly off-center from the first fold line L1 of the cylindrical body 3. Furthermore, 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 by the notch 20 to the cut line 21.

Furthermore, with the packaging box 1 according to the first embodiment, the score line 21 is cut downward from the bottom end of the notch 20, allowing the blade 63 guided into the notch 20 to bite into the score line 21. This allows the blade 63 to be reliably guided to the top end of the first fold line L1, allowing the blade 63 to cut a slit into the cylindrical body 3 along the first fold line L1.

[Modification of the first embodiment]
Next, referring to Figures 14 to 18, a brief description will be given of packaging boxes 1 (blanks 1A) according to first to fifth modified examples of the first embodiment. Figures 14 to 18 are plan views showing the blanks 1A of the packaging boxes 1 according to the first to fifth modified examples, in that order. In the description of the first to fifth modified examples, the same reference numerals are used for components that are the same as or correspond to the packaging box 1 (blank 1A) described above, and descriptions thereof will be omitted.

<First and second modified examples>
In the packaging box 1 according to the first embodiment described above, the cutout 20 is recessed in a V-shape, but the present invention is not limited to this. In a packaging box 1 (blank 1A) according to a first modification, as shown in Fig. 14 , the cutout 22 may be formed as a groove (U-shape) of approximately the same width extending downward from the upper edge of the corner of the opening 4, and the score line 21 may be cut downward from the lower end of the cutout 22. Furthermore, as shown in Fig. 15 , for example, in a packaging box 1 (blank 1A) according to a second modification, the cutouts 20 and 22 may be omitted. In this case, the score line 21 is cut downward from the upper end of the foundation walls 10 and 11.

<Third Modification>
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 cutout portion 20. Specifically, the pair of guide fold lines 23 are formed so as to slope away from each other from the lower end of the score line 21 toward the upper end of the foundation walls 10, 11 (the upper edge of the opening 4 of the cylindrical body 3). Note that one guide fold line 23 is formed at the corner of the foundation walls 10, 11 at both ends in the flow direction, and this forms a pair of guide fold lines 23 when the cylindrical body 3 is formed. The guide fold line 23 may be a general-purpose crease or a lead crease, or may be a reverse crease formed by crushing the cardboard in the thickness direction from the front liner 9B side.

In the packaging box 1 (blank 1A) according to the third modified example, for example, if the blade 63 is positioned slightly offset from the score line 21, the descending blade 63 will collide with the upper edge of the opening 4 and fold the leading corners of the top flaps 16, 18 along the guide fold line 23. This allows the blade 63 to enter the score line 21 along the fold at the guide fold line 23, thereby guiding the blade 63 from the score line 21 to the upper end of the first fold line L1. While the pair of guide fold lines 23 extend from the lower end of the score line 21 to the upper end of the foundation walls 10, 11, this is not a limitation and the pair of guide fold lines 23 may not reach the upper end of the foundation walls 10, 11 (not shown). Furthermore, while the pair of guide fold lines 23 extend diagonally upward from the lower end of the score line 21, this is a limitation and the pair of guide fold lines 23 may extend diagonally upward from a position slightly above the lower end of the score line 21 (not shown). In other words, the "lower end of the score line" in the claims does not refer only to the lower end of the score line 21, but also includes the portion slightly shifted upward from the lower end of the score line 21.

<Fourth Modification>
Furthermore, as shown in Fig. 17, the packaging box 1 (blank 1A) according to the fourth modification may have multiple guide fold lines 23 (three in Fig. 17) formed parallel to each other and spaced apart. With this configuration, when the descending blade 63 collides with the upper edge of the opening 4, the triangular region weakened by the multiple guide fold lines 23 can be easily deformed. This provides 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, and it is sufficient that two or more guide fold lines 23 are formed parallel to each other and spaced apart.

<Fifth Modification>
Furthermore, as shown in FIG. 18 , in the packaging box 1 (blank 1A) according to the fifth modification, a triangular region 24 may be formed in the foundation walls 10, 11 (tubular body 3) by a pair of imaginary lines (not actually present, shown as two-dot chain lines in FIG. 18 ) that slope away from each other from the lower end of the score line 21 toward the upper end of the foundation walls 10, 11 (the upper edge of the opening 4 of the tube 3). Here, "implied" refers to a structure in which the cardboard sheet is flattened in the thickness direction, and is indicated by hatching (diagonal lines) in FIG. 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 surface (back liner 9C) of the cardboard sheet. However, the core 9A may also be flattened in the thickness direction from the front surface (front liner 9B) of the cardboard sheet. Note that one imaginary line is formed at the corner of the foundation walls 10, 11 at both ends in the flow direction, forming a pair of imaginary lines when the tube 3 is formed. According to the packaging box 1 (blank 1A) of the fifth modification, the triangular region 24 is weakened by being stepped, and therefore, the same effect as that of the packaging box 1 (blank 1A) of the third to fourth modifications can be obtained. Note that the feature of the packaging box 1 (blank 1A) of the fifth modification (the stepped triangular region 24) may be combined with the packaging box 1 (blank 1A) of the third to fourth modifications (not shown).

Problems with using blunt blades
Incidentally, the cardboard sheet constituting the packaging box 1 (cylindrical body 3) according to the first embodiment (including the first to fifth modified examples; the same applies below) was torn by the blunt blade 63. In consideration of the torn by the blunt blade 63, it is preferable to form the packaging box 1 (cylindrical body 3) from a cardboard sheet that is easy to tear (easily to tear). On the other hand, in consideration of protecting the contents 90 contained in the packaging box 1, it is preferable to form the packaging box 1 (cylindrical body 3) from a cardboard sheet that is difficult to crush.

Furthermore, the blunt blade 63 descends, slightly crushing the upper corners of the cylindrical body 3 (the upper edges of the cutouts 20), while dragging the cardboard sheet around the first fold line L1. For example, if the cardboard sheet is tear-resistant, the cardboard sheet around the first fold line L1 may tear in a strip that spreads horizontally from top to bottom, creating a large hole at the base of the adjacent top flaps 16, 18 (the lower ends of the cut grooves 66) (see Figure 24). In other words, the cut grooves 66 formed along the vertical ridges of the cylindrical body 3 spread from top to bottom, resulting in a groove width that significantly exceeds the thickness of the blade 63 (blade thickness). The hole at the base of the top flaps 16, 18 is visible at the upper corners of the sealed packaging box 1, preventing the contents 90 from being properly packaged and significantly compromising the aesthetic appeal of the packaging box 1.

[Crushing ratio]
Taking the above-mentioned problems into consideration, the packaging box 1 according to the first embodiment is constructed with a cardboard sheet having a breaking ratio (Z) of 0.0039 [N/(m Pa)], or 3.9 [mN/(m Pa)] or more. The breaking ratio (Z) is the ratio of the vertical compressive strength (Y [kN/m]) of the cardboard sheet to the bursting strength (X [kPa]) of the cardboard sheet, and is calculated by the following mathematical formula 1. Note that the "m" at the beginning of the unit in the breaking ratio (Z) = 3.9 [mN/(m Pa)] above is the SI prefix millimeter (10^-3).

The higher the bursting strength (X) of a cardboard sheet, the more difficult it is to break; the lower the bursting strength (X), the easier it is to break. The bursting strength (X) of a cardboard sheet should be measured using the test method specified in JIS P 8131. Furthermore, the higher the vertical compressive strength (Y) of a cardboard sheet, the more difficult it is to crush; the lower the vertical compressive strength (Y), the easier it is to crush. The vertical compressive strength (Y) of a cardboard sheet should be measured using the test method specified in JIS Z 0403-2. There is a certain degree of correlation between the bursting strength (X) and vertical compressive strength (Y) of a cardboard sheet; for example, as the vertical compressive strength (Y) increases, the bursting strength (X) also tends to increase. Therefore, in the above-mentioned formula 1, if the vertical compressive strength (Y) is increased, the bursting strength (X) also increases, so it is estimated that the increase in the crushing ratio (Z) will plateau and the crushing ratio (Z) will not become infinitely large. Furthermore, for example, a corrugated cardboard sheet made from base paper containing a large amount of reinforcing agent may have a higher vertical compressive strength (Y) than a corrugated cardboard sheet made from conventional base paper that does not contain a large amount of reinforcing agent, even though the bursting strength (X) is not significantly different. As a result, the vertical compressive strength (Y) may be higher relative to the bursting strength (X), resulting in a higher crushing ratio (Z). Furthermore, for example, a corrugated cardboard sheet made from base paper containing a large amount of short-fiber recycled paper may have a lower bursting strength (X) than a corrugated cardboard sheet made from conventional base paper that does not contain a large amount of recycled paper, even though the vertical compressive strength (Y) is not significantly different. As a result, the bursting strength (X) may be lower relative to the vertical compressive strength (Y), resulting in a higher crushing ratio (Z).

When breaking the cylindrical body 3 (cardboard sheet) using a blunt blade 63, the ratio (proportion) of the bursting strength (X) and vertical compressive strength (Y) of the cardboard sheet is important in order to prevent the cut groove 66 from spreading from top to bottom. In the packaging box 1 according to the first embodiment, the bursting ratio (Z) is set to 3.9 mN/(m·Pa) or greater, which enables the cylindrical body 3 (cardboard sheet) to be broken properly even with a blunt blade 63.

[verification]
The applicant conducted a test (verification) to confirm that setting the breaking ratio (Z) of a cardboard sheet to 3.9 [mN/(m Pa)] or more is effective for breaking the cardboard sheet using a blunt blade 63. The test to verify the effectiveness of the breaking ratio (Z) set for the cardboard sheet will be described below with reference to FIGS. 19 and 20 . FIG. 19 is a perspective view showing the test cylinder 3A used in the test. FIG. 20 is a diagram showing the results of the test. Note that in the following description and drawings, the units [kPa], [kN/m], and [mN/(m Pa)] for burst strength (X), normal compressive strength (Y), and breaking ratio (Z) may be omitted.

<Test conditions and methods>
For this test (real verification), five sheets of each of a plurality of cardboard sheets (four examples and two comparative examples) with different collapse ratios (Z) were prepared, as shown in Table 1. Each cardboard sheet was conditioned in a humidity-controlled environment specified in JIS P 8111:1998, and this test (real verification) was carried out in the above-mentioned humidity-controlled environment.

Each cardboard sheet was formed with a first fold line L1 and score lines 21, similar to the blank 1A. As shown in Figure 19, the cardboard sheet was folded along the first fold line L1 to create a square-shaped test cylinder 3A similar to the cylinder 3 of the packaging box 1. Five test cylinders 3A were created for each type of cardboard sheet. Note that, as an example, groove-shaped notches 22 of the same width are formed in the four upper corners of the test cylinder 3A, but the notches 22 may be omitted.

In this test (this verification), the upper side of the vertical ridge line (first fold line L1) of each test cylindrical body 3A was broken by the dividing unit 32 (blade 63) of the packaging device 5. The applicant visually observed (inspected) the tearing and cut edges of the test cylindrical bodies 3A (cardboard sheets) broken by the blunt blade 63, and evaluated them based on the observation results using the following three-level scale.
Good: The width of the kerf 66 from top to bottom is approximately the same as the blade thickness.
- Poor: The kerf 66 widens downward, and the groove width greatly exceeds the blade thickness.
Normal: The width of the kerf 66 is intermediate between good and bad.

<Test Results>
The test results of this test (this verification) are shown in Figure 20. In Figure 20, good is indicated by "◯", bad is indicated by "X", and average is indicated by "Δ". Figure 20 also shows a photograph of the kerf 66 formed in the test cylinder 3A.

In the cardboard sheets of Comparative Example 1 (breaking ratio (Z) = 2.0) and Comparative Example 2 (breaking ratio (Z) = 3.8), the cut grooves 66 widened downward, resulting in a groove width that significantly exceeded the thickness of the blade 63. In other words, the cardboard sheets of Comparative Examples 1 and 2 were rated as defective (x). Therefore, if a packaging box 1 were formed using the cardboard sheets of Comparative Examples 1 and 2, unnecessary holes would appear in the upper corners of the packaging box 1, making it impossible to properly package the contents 90 and significantly compromising the aesthetic appeal of the packaging box 1.

In the cardboard sheet of Example 1 (breaking ratio (Z) = 3.9), the slits 66 widen slightly downward, but not as much as the slits 66 in the cardboard sheets of Comparative Examples 1 and 2. In the cardboard sheet of Example 1, the fracture surface on the right side of the slit 66 in the photograph is formed roughly vertically, showing a slight improvement over the slits 66 in the cardboard sheets of Comparative Examples 1 and 2. In other words, the cardboard sheet of Example 1 received a rating of fair (△). Therefore, it is believed that the cardboard sheet of Example 1 is more suitable for breaking using a blunt blade 63 than the cardboard sheets of Comparative Examples 1 and 2. Therefore, when a packaging box 1 is formed using the cardboard sheet of Example 1, unwanted holes are less likely to appear in the upper corners of the packaging box 1, making it possible to properly package the contents 90 while maintaining the aesthetic appeal of the packaging box 1.

In the cardboard sheets of Example 2 (breaking ratio (Z) = 6.1), Example 3 (breaking ratio (Z) = 6.9), and Example 4 (breaking ratio (Z) = 7.2), the cut grooves 66 had a width from top to bottom that was approximately the same as the thickness of the blade 63. In other words, the cardboard sheets of Examples 2 to 4 were rated as good (◯). Therefore, it is believed that the cardboard sheets of Examples 2 to 4 are more suitable for breaking using a blunt blade 63 than the cardboard sheet of Example 1. Therefore, when a packaging box 1 is formed from the cardboard sheets of Examples 2 to 4, the appearance of unwanted holes in the upper corners of the packaging box 1 is suppressed, allowing the contents 90 to be packaged properly while maintaining the aesthetic appeal of the packaging box 1.

<Conclusion>
The test results described above confirm that setting the cardboard sheet's breaking ratio (Z) to 3.9 or higher is effective for breaking cardboard sheets using the blunt blade 63. Although it was not possible to prepare a cardboard sheet with a breaking ratio (Z) of 5.0 or higher in this test (this verification), considering the test results of Example 1 (breaking ratio (Z) = 3.9) and Example 2 (breaking ratio (Z) = 6.1), it is estimated that a cardboard sheet with a breaking ratio (Z) of 5.0 or higher can form a better cut groove 66 than the cardboard sheet of Example 1. Therefore, it is estimated that it is preferable to set the cardboard sheet's breaking ratio (Z) to 5.0 or higher. Furthermore, in this test (this verification), it was not possible to prepare a cardboard sheet with a breaking ratio (Z) of 6.0, but considering the test results of Example 2 (breaking ratio (Z) = 6.1), it is estimated that even a cardboard sheet with a breaking ratio (Z) of 6.0 would produce substantially the same test results as the cardboard sheet of Example 2. Therefore, it is estimated that it is more preferable to set the breaking ratio (Z) of the cardboard sheet to 6.0 or more.

As previously explained, increasing the vertical compressive strength (Y) also increases the bursting strength (X), so it is presumed that the increase in the crushing ratio (Z) reaches a plateau (there is an upper limit to the crushing ratio (Z)). While this test (this verification) was unable to identify an upper limit for the crushing ratio (Z), the applicant confirmed the existence of a cardboard sheet with a crushing ratio (Z) of 10.4. The applicant presumes that no cardboard sheet has a crushing ratio (Z) exceeding 11.0, even if it is made from base paper containing a large amount of reinforcing agent or base paper containing a large amount of short-fiber recycled paper. Since this test yielded better test results as the crushing ratio (Z) increased, it is presumed that a cardboard sheet with a crushing ratio (Z) of 11.0 would produce test results similar to those of the cardboard sheet of Example 4 (crushing ratio (Z) = 7.2). From the above, it is estimated that by setting the breaking ratio (Z) of the cardboard sheet to between 3.9 mN/(m·Pa) and 11.0 mN/(m·Pa), it is possible to properly break the cardboard sheet even with a blunt blade 63. It is estimated that by setting the breaking ratio (Z) to between 5.0 mN/(m·Pa) and 11.0 mN/(m·Pa), and more preferably between 6.0 mN/(m·Pa) and 11.0 mN/(m·Pa), it is possible to properly break the cardboard sheet even with a blunt blade 63.

In the packaging box 1 according to the first embodiment described above, the breaking ratio (Z) [mN/(m·Pa)] is defined as the value obtained by dividing the vertical compressive strength Y [kN/m] of the cardboard sheet by its bursting strength X [kPa], and the breaking ratio (Z) of the cardboard sheet is set to 3.9 [mN/(m·Pa)] or greater. With this configuration, even a blunt blade 63 can break the cylindrical body 3 along the first fold line L1 while suppressing crushing of the cylindrical body 3 (side walls 15, 17). This prevents unnecessary holes from being created in the upper corners of the sealed packaging box 1, allowing for the formation of a proper packaging box 1 with the upper corners securely closed.

[Second embodiment: packaging box]
Next, a packaging box 2 (blank 2A) according to a 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, components that are the same as or correspond to those of the packaging box 1 (blank 1A) according to the first embodiment will be given the same reference numerals, and descriptions thereof will be omitted.

As shown in Figure 21, in the blank 2A of the packaging box 2, a pair of first foundation walls 10 and a pair of second foundation walls 11 are arranged alternately in the flow direction and are connected via folding portions 25 (vertical ridge lines). The pair of first foundation walls 10 and the pair of second foundation walls 11 are folded at the folding portions 25 to form a rectangular cylindrical body 3 (see Figure 22).

<Bending part>
The folding portion 25 has a first fold line L1 formed on the other side (lower) in the row direction and a break assist line 26 formed on one side (upper) in the row direction. The first fold line L1 and the break assist line 26 are arranged side by side on the same straight line along the row direction. The first fold line L1 is formed between the lower end of the foundation walls 10, 11 (cylindrical body 3) and a position corresponding to the minimum height (H2) of the packaging box 2 after sealing. The break assist line 26 is formed between the first fold line L1 and the score line 21. The break assist line 26 is formed longer in the row direction than the first fold line L1.

(Break assist line)
The break assist line 26 has a first break line 27 and a second break line 28. The first break line 27 is formed between the lower end of the score line 21 and the upper end of the second break line 28. The second break line 28 is formed between the lower end of the first break line 27 and the upper end of the first fold line L1. The first break line 27 is formed shorter in the row direction than the second break line 28. As shown in FIG. 22 , when the packaging box 2 is temporarily assembled, the first break line 27 is formed between the corner of the opening 4 of the cylindrical body 3 (more precisely, the bottom of the notch 20) and a position corresponding to the maximum height (H1) of the packaging box 2 after sealing. The second break line 28 is formed between the lower end of the first break line 27 and a position corresponding to the minimum height (H2) of the packaging box 2 after sealing. That is, 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 packaging box 2 after sealing, 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 packaging box 2 after sealing.

As shown in FIG. 21 , the first break line 27 is a perforation consisting of alternating first cuts 27A and first seams 27B. The second break line 28 is a perforation consisting of alternating second cuts 28A and second seams 28B. The first cuts 27A and second cuts 28A are each linear cuts made with a blade in the thickness direction of the cardboard. The first seams 27B and second seams 28B are each uncut portions of the cardboard sheet that connect adjacent cuts 27A and 28A. Note that in this specification, when the first cuts 27A and second cuts 28A are collectively described, they are sometimes simply referred to as "cuts 27A, 28A," and when the first seams 27B and second seams 28B are collectively described, they are sometimes simply referred to as "seams 27B, 28B."

The lengths of the first cut 27A, first seam 27B, second cut 28A, and second seam 28B are set so that the second break line 28 is less likely to break than the first break line 27. The lengths of the cuts 27A, 28A and the seams 27B, 28B are preferably set within the following ranges to satisfy the condition of making the second break line 28 less likely to break. The lengths of the cuts 27A, 28A and the seams 27B, 28B are preferably 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 may be formed shorter than the first cut 27A, and the second seam 28B may be formed longer than the first seam 27B. The relationship between the lengths of the cuts 27A, 28A and the seams 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 seam 28B may be longer than the first seam 27B (not shown). Alternatively, the first seam 27B and the second seam 28B may be the same length, and the second cut 28A may be shorter than the first cut 27A (not shown). Furthermore, the first cut 27A may be longer than the second cut 28A, and the first seam 27B may be longer than the second seam 28B (not shown).

It is sufficient that the first break line 27 and the second break line 28 are each formed of at least one cut 27A, 28A and at least one seam 27B, 28B. Furthermore, if the first break line 27 includes multiple first cuts 27A and multiple first seams 27B, the multiple first cuts 27A may all be the same length or may have different lengths (not shown). Similarly, the multiple first seams 27B may all be the same length or may have different lengths (not shown). Furthermore, if the second break line 28 includes multiple second cuts 28A and multiple second seams 28B, the same applies as the first break line 27.

The pre-assembled packaging box 2 (see Figure 22) is placed at the most upstream position of the conveyor 35 with the contents 90 inside, and is sealed by the packaging device 5 described above. Note that the method for sealing the packaging box 2 (the operation of the packaging device 5) is generally the same as the method for sealing the packaging box 1 according to the first embodiment described above, and therefore a detailed description thereof will be omitted.

Because the lower end position of the first break line 27 corresponds to the maximum height (H1) of the packaging box 2 after sealing, the entire first break line 27 is broken regardless of the height of the packaging box 2 (contents 90). In a packaging box 2 that reaches the maximum height (H1), the side walls 15, 17 are connected by the first fold line L1 and the second break line 28. In contrast, in a packaging box 2 that reaches the minimum height (H2), the entire break assist line 26 is broken, and the side walls 15, 17 are connected only by the first fold line L1. Furthermore, in a packaging box 1 that reaches a height other than the maximum height (H1) and the minimum height (H2), part of the second break line 28 is broken, and the side walls 15, 17 are connected by the first fold line L1 and the remaining unbroken portion of the second break line 28.

In the packaging box 2 according to the second embodiment, the upper portion of the vertical ridgeline, including the boundary between adjacent top flaps 16, 18, is weakened by the break assist lines 26 (first break line 27 and second break line 28). This configuration makes it possible to easily break the cylindrical body 3 along the break assist lines 26, even with a non-sharp blade 63, while preventing the cylindrical body 3 (side walls 15, 17) from being crushed. Furthermore, because the side walls 15, 17 can be formed without the third fold line L3 when the packaging box 2 is sealed, it is possible to achieve the same effects as the packaging box 1 according to the first embodiment, such as preventing a decrease in the compressive strength of the sealed packaging box 2.

In addition, in the packaging box 1 according to this embodiment, the lengths of the cuts 27A, 28A and the seams 27B, 28B are set so 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 that reaches 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 compression strength of the packaging box 1 at its maximum height can be maintained at a high level.

In the packaging box 2 according to the second embodiment, the break assist line 26 includes a first break line 27 and a second break line 28, but the present invention is not limited to this. The second break line 28 may be omitted, and the break assist line 26 may include only the first break line 27 (variant (not shown)). In this case, a first fold line L1 is formed in place of the second break line 28, and the first break line 27 is formed between the lower end of the score line 21 and the upper end of the first fold line L1.

Problems with using blunt blades
Incidentally, when the blunt blade 63 breaks the cylindrical body 3 along the break assist line 26, it descends while being guided (guided) by the slits 27A, 28A. Therefore, if the slits 27A, 28A are extremely short, the slits 27A, 28A cannot guide (guide) the blade 63, and the blade 63 may derail (derail) from the break assist line 26, causing the break to progress. If the blade 63 derails immediately after the first break line 27 begins to break, there is a risk that the deviation due to the derailment will expand when the second break line 28, which is more difficult to break than the first break line 27, breaks. Therefore, in order to properly break the cylindrical body 3 along the break assist line 26, it is important to reliably guide (guid) the descending blade 63 to the first slit 27A of the first break line 27.

[Intersection distance]
Considering the above-mentioned problems, in the packaging box 2 according to the second embodiment, the length (H5) of the first cut 27A (see FIG. 21 ) is set to be equal to or greater than 1/8 of the intersection distance (H6) (see FIG. 23 ), which is the maximum height of the blade 63 that contacts the fractured surface (cut) of the first fracture line 27 (vertical ridge line) ((H5) ≥ (H6)/8). As shown in FIG. 23 , the packaging device 5 has the blade 63 installed in an inclined position. Therefore, the intersection distance (H6) is the length of a vertical line extending vertically upward from a point on the tapered portion 63B that contacts the first fracture line 27 (see the black circle in FIG. 23 ) so as to intersect the blade 63. This vertical line extends approximately parallel to the pull-out assist surface 63A. The intersection distance (H6) can also be considered the maximum length over which the first fracture line 27 can contact the side of the blade 63.

In the packaging box 2 according to the second embodiment described above, the length (H5) of the first cut 27A of the first breaking line 27 is set to at least 1/8 of the intersection distance (H6), which allows the descending blade 63 to be guided (introduced) to the first cut 27A. This makes it less likely for the blunt blade 63 to derail from the break assist line 26, allowing the cylindrical body 3 to be properly broken along the first breaking line 27. The applicant has experimentally confirmed that setting the length (H5) of the first cut 27A to at least 1/8 of the intersection distance (H6) of the blade 63, preferably at least 1/4 of the intersection distance (H6), effectively functions to guide the descending blade 63.

Note that the features of the packaging box 1 according to the first to fifth variants of the first embodiment (notch 22, guide fold line 23, and flattened tiers) may also be applied to the packaging box 2 according to the second embodiment (not shown).

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 butted 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 insular bottom (not shown).

Furthermore, while the packaging boxes 1 and 2 in the first and second embodiments are formed from double-sided corrugated cardboard made of paper, the present invention is not limited to this. The packaging boxes 1 and 2 may also be formed from single-sided corrugated cardboard, double-sided corrugated cardboard, or triple-sided corrugated cardboard, etc.

In the packaging device 5 described above, the second creasing unit 50 is located downstream of the first creasing unit 40, but this is not limiting and the second creasing unit 50 may be located upstream of the first creasing unit 40 (not shown). That is, in the creasing process, the third fold line L3 may be formed in the first foundation wall 10 after the third fold line L3 is formed in the second foundation wall 11. Furthermore, the creasing unit 31 may be configured so that the first creasing unit 40 and the second creasing unit 50 are integrated and form the third fold line L3 on all four side surfaces of the cylindrical body 3 at the same time (not shown).

In addition, in the packaging device 5 described above, one inner roller 45, 55 of the creasing section 31 is configured to face between a pair of outer rollers 44, 54, but the present invention is not limited to this. For example, the outer rollers 44, 54 may be combined into one, with one inner roller 45, 55 facing one outer roller 44, 54 (not shown). Alternatively, for example, the inner rollers 45, 55 may be paired, with one pair of outer rollers 44, 54 facing a pair of inner rollers 45, 55 (not shown). Alternatively, for example, the outer rollers 44, 54 may be combined into one, with the inner rollers 45, 55 paired, with one outer roller 44, 54 facing between a pair of inner rollers 45, 55 (not shown).

In addition, in the packaging device 5 described above, the inner rollers 45, 55 are slightly offset downward relative to the outer rollers 44, 54, but the present invention is not limited to this. The inner rollers 45, 55 may also be positioned facing the outer rollers 44, 54 at the same height (not shown).

In addition, in the packaging device 5 (crisping unit 31) described above, the third fold line L3 is formed horizontally (left-right and front-to-back) within the range between the minimum height (H2) and the maximum height (H1) of the packaging boxes 1 and 2. However, the present invention is not limited to this. For example, the third fold line L3 may be formed horizontally (left-right and front-to-back) within the range between the maximum height (H1) of the packaging boxes 1 and 2 (not shown). In this case, when the packaging boxes 1 and 2 are sealed, the leading edges of the pair of upper outer flaps 18 will be separated from each other (not shown).

In addition, while the blades 63 of the dividing section 32 in the packaging device 5 described above are inclined, the present invention is not limited to this. For example, the four blades 63 may be in a position perpendicular to the first foundation wall 10 or perpendicular to the second foundation wall 11 when viewed from above (not shown). Furthermore, for example, the blades 63 may be in a substantially horizontal position when viewed from the side (front and side) (not shown). In this case, the intersection distance (H6) of the blades 63 is the length of an imaginary vertical line perpendicular to the tip edge of the tapered section 63B (not shown).

In addition, while the packaging device 5 described above has a tapered portion 63B formed on the lower edge of the blade 63 of the dividing section 32, 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 way, if the lower tapered portion 63B becomes worn, the blade 63 can be turned upside down and the upper tapered portion 63B faces downward, eliminating the need to replace the blade 63 with a new one. Alternatively, the tapered portion 63B may be omitted, and the blade 63 may be formed as a plate of approximately uniform thickness (not shown).

In addition, in the packaging device 5 described above, the blade 63 of the dividing unit 32 is formed with a pull-out assist surface 63A, but this is not limited to this, and the pull-out assist surface 63A may be omitted (not shown). Furthermore, the guide roller 64 and roller arm 65 of the dividing unit 32 may be omitted (not shown).

In addition, in the packaging device 5 described above, the sealing unit 34 seals 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 adhered to a pair of upper inner flaps 16 via an adhesive, or the other upper outer flap 18 may be adhered to one upper outer flap 18 via an adhesive (not shown).

Furthermore, while the packaging device 5 described above is provided with a folding unit 33 and a sealing unit 34, the present invention is not limited to this. For example, if an operator performs the sealing work manually, such as by closing the upper flaps 16, 18 and applying adhesive tape T, the folding unit 33 and the sealing unit 34 may be omitted (not shown). Furthermore, while the packaging device 5 described above is provided with a height measuring unit 30, the present invention is not limited to this. For example, if an operator operates the control unit 36 to input the height (H3) of the contents 90, the height measuring unit 30 may be omitted (not shown).

In addition, while the packaging device 5 described above has a configuration in which the height measurement unit 30, creasing unit 31, dividing unit 32, folding unit 33, and sealing unit 34 are fixed, and the packaging box 1 is transported by the conveyor 35, the present invention is not limited to this. For example, a packaging device according to a modified example may omit the conveyor 35, and have the packaging boxes 1 and 2 fixed (not moved), with a movement mechanism that moves each of the units 30-34 (not shown). That is, a packaging device according to a modified example may have a fixed base (not shown) for fixing the packaging box 1, and the movement mechanism may intermittently move each of the units 30-34 over the packaging boxes 1 and 2 fixed to the fixed base.

The above description of the embodiment shows one aspect of the packaging box sealing method according to the present invention, and the technical scope of the present invention is not limited to the above embodiment. The present invention may be modified, substituted, or altered in various ways without departing from the spirit of the technical concept, and the claims include all embodiments that may fall within the scope of the technical concept.

2 Packaging box 2A blank 3 Cylindrical body 4 Opening 5 Packaging device 10 First foundation wall (wall)
11 Second foundation wall (wall part)
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 portion 21 Score line 23 Guide fold line 24 Triangular area 26 Fracture assistance line 27 First fracture line 27A First cut 27B First joint 28 Second fracture line 28A Second cut 28B Second joint 31 Crease portion 32 Separation portion 63 Blade 67 Fracture surface 90 Contents L1 First fold curve (vertical ridge line)
L3 Third fold line (horizontal fold line)

Claims (3)

A method for sealing a packaging box, in which a packaging device (5) changes the height of a cylindrical body (3) having a closed bottom surface according to the height of an item (90) contained in a cardboard packaging box (2), and packages the item in the packaging box,
The packaging device
a score line (L3) formed on the wall portion (10, 11) of the cylindrical body according to the height of the contents contained in the cylindrical body through the opening (4) on the top surface of the cylindrical body, and dividing the wall portion into side walls (15, 17) and upper flaps (16, 18);
a dividing section (32) that divides the upper flap connected via the vertical ridge line by pressing a blade (63) formed in a blunt plate shape against the corner of the opening and lowering the blade (63) along the vertical ridge line from the upper end of the vertical ridge line of the cylindrical body to the horizontal fold line,
The cylindrical body has a score line (21) cut along the vertical ridge at the corner of the opening, and a tear assist line (26) weakening an upper portion of the vertical ridge including the boundary of the adjacent upper flap,
The score line is formed above the position that will be the maximum height (H1) of the packaging box after sealing,
The cardboard sheet has a bursting ratio (Z [mN/(m Pa)]) of 3.9 [mN/(m Pa)] or more, which is the ratio of the normal compressive strength (Y [kN/m]) of the cardboard sheet constituting the cylindrical body to the bursting strength (X [kPa]) of the cardboard sheet;
The break assist line has a first break line (27) formed between the corner of the opening and a position corresponding to the maximum height (H1) of the packaging box after sealing,
The first break line is a perforation in which first cuts (27A) and first seams (27B) are arranged alternately,
A method for sealing a packaging box, characterized in that the length (H5) of the first cut is 1/8 or more of the intersection distance (H6), which is the maximum height of the blade that contacts the fracture surface of the first fracture line. A method for sealing a packaging box according to claim 1, characterized in that the break assist line further includes a second break line (28) formed between the lower end of the first break line and a position corresponding to the minimum height (H2) of the packaging box after sealing. The second breaking line is a perforation in which second cuts (28A) and second seams (28B) are arranged alternately,
3. The method for sealing a packaging box according to claim 2, wherein the lengths of the first cut, the first seam, the second cut, and the second seam are set so that the second break line is more difficult to break than the first break line.