WAVEFORM PRESSURE-BONDED PACKAGE OF A PAPER MEMBER

Abstract

A package is provided which is formed by, with a commodity sandwiched between single-faced corrugated paperboards that are vertically disposed paper members, pressure-bonding together the paper members at the edges of the paper members along the peripheral sides thereof. The edges of the single-faced corrugated paperboards along at least two opposed sides thereof are subjected to waveform bonding by pressure bonding such that a wave shape is formed in the thickness direction of the single-faced corrugated paperboards. The dimensional difference between (i) the length L.sub.1 of the portion of each paper member deflected by sandwiching a commodity, and (ii) the flat-bonding length (imaginary linear distance) L.sub.2 of a respective one of the edges extending parallel to the direction of the length L.sub.1, and each imaginarily bonded flat is absorbed by the waveform bonding, so that, at these edges, the vertical gaps between the single-faced corrugated paperboards are eliminated.

Claims

1. A waveform pressure-bonded package comprising a paper member or paper members, and formed by: with an item to be packaged sandwiched between vertically disposed portions of the paper member that are vertically disposed, or sandwiched between the paper members that are vertically disposed, pressure-bonding together the vertically disposed portions of the paper member or the paper members at edges of the paper member or the paper members along peripheral sides thereof, wherein edges of the paper member or the paper members along at least two opposed sides thereof are subjected to waveform bonding by pressure bonding such that a wave shape is formed in a thickness direction of the paper member or the paper members, and wherein a dimensional difference between (i) a length of each of deflected portions of the paper member or the paper members deflected by sandwiching an item to be packaged, and (ii) a flat-bonding length (imaginary linear distance) of a respective one of parallel-extending edges of the paper member or the paper members extending parallel to a direction of the length of the each of the deflected portions, and each imaginarily bonded flat by flat-bonding is absorbed by the waveform bonding, so that, at the parallel-extending edges, vertical gaps between the vertically disposed portions of the paper member, or between the paper members are eliminated.

2. The waveform pressure-bonded package according to claim 1, wherein the paper members that are vertically disposed comprise two paper members having a first pair of opposed sides and a second pair of opposed sides.

3. The waveform pressure-bonded package according to claim 2, wherein edges of the two paper members along one pair of the first pair of opposed sides and the second pair of opposed sides are subjected to the waveform bonding, and edges of the two paper members along the other pair of the first pair of opposed sides and the second pair of opposed sides are subjected to the flat-bonding.

4. The waveform pressure-bonded package according to claim 2, wherein edges of the two paper members along all of four peripheral sides thereof are subjected to the waveform bonding.

5. The waveform pressure-bonded package according to claim 1, wherein the vertically disposed portions of the paper member comprise portions of one paper member folded into two along a fold line, and wherein edges of the one paper member along two sides thereof that are orthogonal to the fold line and that are opposed to each other are subjected to the waveform bonding, and an edge of the one paper member along one side thereof that is opposed to the fold line is pressure-bonded by the flat-bonding.

6. The waveform pressure-bonded package according to claim 1, wherein the paper member or each of the paper members is a single-faced corrugated paperboard comprising a corrugated medium forming a corrugated flute, and a linerboard bonded to one surface of the corrugated medium, and wherein with portions of the corrugated medium of the single-faced corrugated paperboard constituting the paper member opposed to each other, the single-faced corrugated paperboard is pressure bonded, or with the corrugated media of the single-faced corrugated paperboards constituting the paper members opposed to each other, the single-faced corrugated paperboards are pressure bonded together.

7. A corrugated pressing member having a corrugated pressing surface configured such that when the waveform pressure-bonded package according to claim 1 is formed, the corrugated pressing surface compresses the paper member or paper members so that an edge of the vertically disposed portions of the paper member, or an edge of the paper members that are vertically disposed is subjected to waveform bonding.

8. The corrugated pressing member according to claim 7, comprising a rigid die body having a corrugated top surface; and a low-friction layer disposed on the top surface of the die body, wherein the low-friction layer is used as the pressing surface.

9. The corrugated pressing member according to claim 7, comprising a rigid die body having a corrugated top surface; a cushion layer disposed on the top surface of the die body; and a low-friction layer disposed on a surface of the cushion layer, wherein the low-friction layer is used as the pressing surface.

10. A pressure-bonding device comprising an upper die and a lower die that are configured to move up and down; and opposed corrugated pressing members disposed, respectively on the upper die and the lower die so as to be opposed to each other, and each comprising the corrugated pressing member according to claim 8, wherein the pressure-bonding device is configured such that with the upper die and the lower die separated from each other, the vertically disposed portions of the paper member or the paper members that are vertically disposed are fed between the pressing surfaces of the opposed corrugated pressing members, an item to be packaged is sandwiched between the vertically disposed portions of the paper member or between the paper members, and the upper die and the lower die are moved toward each other until an edge of the paper member or the paper members is compressed by the pressing surfaces of the opposed corrugated pressing members, and is subjected to waveform bonding.

11. A pressure-bonding device comprising an upper die and a lower die that are configured to move up and down; and opposed corrugated pressing members disposed, respectively on the upper die and the lower die so as to be opposed to each other, and each comprising the corrugated pressing member according to claim 9, wherein the pressure-bonding device is configured such that with the upper die and the lower die separated from each other, the vertically disposed portions of the paper member or the paper members that are vertically disposed are fed between the pressing surfaces of the opposed corrugated pressing members, an item to be packaged is sandwiched between the vertically disposed portions of the paper member or between the paper members, and the upper die and the lower die are moved toward each other until an edge of the paper member or the paper members is compressed by the pressing surfaces of the opposed corrugated pressing members, and is subjected to waveform bonding.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1A is a perspective view of a waveform pressure-bonded package comprising single-faced corrugated paperboards according to a first embodiment of the present invention.

[0024] FIG. 1B is a side view of the package of FIG. 1A, when seen from its pressure-bonded edge.

[0025] FIG. 2 is a perspective view of a waveform pressure-bonded package comprising single-faced corrugated paperboards according to a second embodiment of the present invention.

[0026] FIG. 3 is a perspective view of a waveform pressure-bonded package comprising a single-faced corrugated paperboard according to a third embodiment of the present invention.

[0027] FIG. 4 is a perspective view of a pressure-bonding device for forming the waveform pressure-bonded package of the first embodiment, the pressure bonding device including corrugated pressing members having a cushion layer.

[0028] FIG. 5 is a side view of the pressure-bonding device of FIG. 4, the side view showing a state during pressure-bonding by the corrugated pressing members having a cushion layer.

[0029] FIG. 6 is a side view of the pressure-bonding device of FIG. 4, the side view showing a state after pressure-bonding by waveform bonding.

[0030] FIG. 7 is a side view of a pressure-bonding device for forming the package of the first embodiment, the side view showing a state during pressure-bonding by corrugated pressing members having no cushion layer.

[0031] FIG. 8 is a side view of the pressure-bonding device FIG. 7, the side view showing a state after pressure-bonding by waveform bonding.

[0032] FIG. 9A is a perspective view of a package disclosed in Patent Document 1.

[0033] FIG. 9B is a vertical sectional view of the package shown in FIG. 9A.

[0034] FIG. 10 is a perspective view of a package disclosed in Patent Document 2.

[0035] FIG. 11 is a side view showing specific names for dimensions relating to waveform bonding.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of Package

First Embodiment

[0036] FIG. 1A and FIG. 1B show a waveform pressure-bonded package according to a first embodiment of the present invention.

[0037] This package is an envelope-shaped package (i) in which, as paper members, two single-faced corrugated paperboards 1 are used that are each constituted by a corrugated medium forming a corrugated flute and a linerboard bonded to one surface of the corrugated medium, and (ii) which is formed by: [0038] allowing the corrugated media of the two single-faced corrugated paperboards 1 to be opposed to each other; and [0039] with a commodity G that is an item to be packaged, such as a book, sandwiched between the two single-faced corrugated paperboards 1, [0040] pressure-bonding together the two single-faced corrugated paperboards 1 at the edges 2 of the package along two opposed sides of the peripheral sides thereof (these two opposed sides are hereinafter referred to as the first two opposed sides), and at the edges 3 of the package along the other two opposed sides of the peripheral sides thereof (these two opposed sides are hereinafter referred to as the second two opposed sides).

[0041] The edges 2 of the package along the first two opposed sides extend in a conveyance direction defined in a production process of the single-faced corrugated paperboards 1. At the edges 2, the two single-faced corrugated paperboards 1 are subjected to waveform bonding by pressure bonding with an adhesive such that a wave shape is formed in a thickness direction. The adhesive used is not limited if it allows for bonding of paper, and is preferably a vinyl acetate-based emulsion adhesive. The waveform bonding will be described later in detail in the section <pressure-bonding processing>.

[0042] The edges 3 of the package along the second two opposed sides extend in a width direction orthogonal to the conveyance direction of the single-faced corrugated paperboards 1. At the edges 3, the two single-faced corrugated paperboards 1 are subjected to flat-bonding so as to be bonded together flat by normal pressure bonding, that is, by pressing them with flat bars while using an adhesive. The flat-bonding may be performed without using an adhesive by compressing the corrugated paperboards 1 at binding portions so as to be bound together.

Second Embodiment

[0043] FIG. 2 shows a waveform pressure-bonded package according to a second embodiment of the present invention.

[0044] This package is also an envelope-shaped package (i) in which, as paper members, two single-faced corrugated paperboards 1 are used that are each constituted by a corrugated medium forming a corrugated flute and a linerboard bonded to one surface of the corrugated medium, and (ii) which is formed by: [0045] allowing the corrugated media of the two single-faced corrugated paperboards 1 to be opposed to each other; and [0046] with a commodity G that is an item to be packaged, such as a book, sandwiched between the two single-faced corrugated paperboards 1, [0047] pressure-bonding together the two single-faced corrugated paperboards 1 at the edges 2 of the package along two opposed sides (first two opposed sides) of the peripheral sides thereof, and at the edges 3 of the package along the other two opposed sides (second two opposed sides) of the peripheral sides thereof. However, the edges 2 along the first two opposed sides and the edges 3 along the second two opposed sides are both subjected to the waveform bonding.

Third Embodiment

[0048] FIG. 3 shows a waveform pressure-bonded package according to a third embodiment of the present invention.

[0049] This package is also an envelope-shaped package (i) in which, as a paper member, one single-faced corrugated paperboard 1 is used that is constituted by a corrugated medium forming a corrugated flute and a linerboard bonded to one surface of the corrugated medium, but (ii) which is formed by: [0050] folding the one single-faced corrugated paperboard 1 into two along a fold line 4 such that portions of the corrugated medium of the paperboard 1 are opposed to each other; and [0051] with a commodity G that is an item to be packaged, such as a book, sandwiched between the opposed portions of the single-faced corrugated paperboard 1, [0052] pressure-bonding together the opposed portions of the single-faced corrugated paperboard 1 at the edges 2 of the package along two opposed sides thereof orthogonal to the fold line 4, and pressure-bonding together the opposed portions at the edge 3 of the package along one side thereof opposed to the fold line 4 by the flat-bonding.

Pressure-Bonding Processing

Pressure-Bonding Device

[0053] FIG. 4 exemplifies a pressure-bonding device for forming, of the above-described packages, the package of the first embodiment. This pressure-bonding device includes a lower die 11 and an upper die 12 that are configured to move toward and away from each other by their upward and downward movements. Two single-faced corrugated paperboards 1 disposed vertically are fed between the lower die 11 and the upper die 12, and a commodity G that is an item to be packaged is fed between the lower die 11 and the upper die 12 by a conveyer.

[0054] The lower die 11 and the upper die 12 are each provided with pressing members 13 for waveform bonding; and a pair of pressing members 14 for flat-bonding which is disposed to be orthogonal to the pressing members 13. The pressing members 13 on the lower die 11 are vertically opposed to the respective pressing members 13 on the upper die 12, and the pair of pressing members 14 on the lower die 11 is vertically opposed to the pair of pressing members 14 on the upper die 12. As the lower and upper dies 11 and 12 approach each other, the pressing members 13 and 14 pressure-bond the paperboards 1 together.

[0055] In view of a case where the variation range of height of the commodity G is large, as shown in FIGS. 5 and 6, each pressing member 13 comprises a rigid die body 13a having a corrugated top surface; a cushion layer 13b disposed on the top surface of the die body 13a; and a low-friction layer 13c disposed on the surface of the cushion layer 13b, and used as a pressing surface. The cushion layers 13b of the pressing members 13 prevent cracks in the surface layers of the single-faced corrugated paperboards 1 due to excessive tensile forces.

[0056] As for the material of each pressing member 13, the die body 13a may be made of, e.g., monomer cast nylon or metal, and the cushion layer 13b may be formed of, e.g., a sponge or a rubber. Also, the low-friction layer 13c may be formed of, e.g., (i) a fluorine resin adhesive tape comprising a fluorine resin-impregnated glass cloth in which a silicone-based adhesive has been applied onto the back surface of the glass cloth, or (ii) a polyethylene acrylic adhesive tape having a surface formed with ridges extending in a sliding direction.

[0057] When the static friction coefficient and dynamic friction coefficient of each of these tapes were measured, the fluorine resin adhesive tape had an average static friction coefficient of 0.06 and an average dynamic friction coefficient of 0.02, and the polyethylene acrylic adhesive tape had an average static friction coefficient of 0.08 and an average dynamic friction coefficient of 0.03. Therefore, the static friction coefficient of the surface of the low-friction layer 13c is set to 0.1 or less.

[0058] If the variation range of height of the commodity G is small, as shown in FIG. 7 and FIG. 8, the cushion layer 13b may be omitted from each pressing member 13 such that the pressing member 13 comprises a rigid die body 13a having a corrugated top surface; and a low-friction layer 13c disposed on the top surface of the die body 13a, and used as a pressing surface. In this case/arrangement, too, the low-friction layer 13c is an essential element. If the cushion layers 13b of the pressing members 13 are omitted, the device is designed such that even when the lower die 11 and the upper die 12 come closest to each other, a gap is ensured/defined between the opposed pressing surfaces of each pressing member 13 on the upper die 12 and the corresponding pressing member 13 on the lower die 11 so as to prevent the pressing surfaces of the low-friction layers 13c from interfering with each other.

[0059] The pressing members 14 on each of the lower and upper dies 11 and 12 are flat bars having a flat pressing surface, and comprise two pressing members extending parallel to each other so as to correspond to positions in front of and behind each boundary of a continuous package continuously extending in the conveyance direction. A cutting blade member 15 is disposed between the pressing members 14 on the lower die 11 so as to cut and separate the continuous package into individual packages.

[0060] On the upstream side of the lower die 11 and the upper die 12 in the conveyance direction of single-faced corrugated paperboards 1 and commodities G, glue guns 16 are disposed to spray and apply an adhesive onto bonding surfaces of single-faced corrugated paperboards 1. The adhesive used here may be, for example, a vinyl acetate-based emulsion adhesive.

Pressure-Bonding Step

[0061] In order to form the package of the first embodiment using the above-described pressure-bonding device, as shown in FIG. 4, the corrugated media of two single-faced corrugated paperboards 1 disposed vertically are made opposed to each other, an adhesive is sprayed and applied from the glue guns 16 onto the corrugated medium of one of the two single-faced corrugated paperboards 1 at the edges 2, and, with the lower die 11 and the upper die 12 separated from each other, the two single-faced corrugated paperboards 1 are fed between the corrugated pressing surfaces of the pressing members 13 after passing between the pressing surfaces of the pairs of pressing members 14, which are vertically opposed to each other, and a commodity G is sandwiched between the two single-faced corrugated paperboards 1.

[0062] Then, as shown in FIG. 5 or FIG. 7, when the two single-faced corrugated paperboards 1 are conveyed and the lower die 11 and the upper die 12 are moved toward each other, the edges 2 on both sides of the two single-faced corrugated paperboards 1 are each subjected to the waveform bonding by being compressed by the corresponding opposed pressing members 13, and concurrently with this, the edges 3 on the other sides are subjected to the flat-bonding by being compressed by the opposed pairs of pressing members 14.

[0063] The cutting blade member 15, which is configured to move up and down, cuts the superposed single-faced corrugated paperboards 1 so as to be separated from the package continuously extending in the conveyance direction.

[0064] Then, as shown in FIG. 6 or FIG. 8, the lower die 11 and the upper die 12 are separated from each other, and the thus-formed package is taken out of the pressure-bonding device. In the package taken out of the pressure-bonding device, as shown in FIG. 1A, the edges 2 along the first two opposed sides of the single-faced corrugated paperboards 1 have been subjected to the waveform bonding, and the edges 3 along the second two opposed sides thereof have been subjected to the flat-bonding. The method for closing the edges 3 is not limited to flat-bonding using an adhesive if the openings can be sealed, and examples thereof include using an adhesive tape or staples and binding by compression at binding portions.

[0065] In this package, as shown in FIG. 1B, the dimensional difference between (i) the length L1 of the portion of each single-faced corrugated paperboard 1 deflected by sandwiching the commodity G, and excluding bonding margins a for bonding on both sides of the paperboards 1, and (ii) the flat-bonding length (imaginary linear distance) L.sub.2 of a respective one of the edges 2 extending parallel to the direction of the length L.sub.1, and each imaginarily bonded flat is absorbed by the waveform bonding, so that the gaps between the two single-faced corrugated paperboards 1 at the edges 2 are eliminated.

Effect Obtained by Waveform Bonding

[0066] In a waveform pressure-bonded package as described above, when two single-faced corrugated paperboards 1 between which a commodity that is an item to be packaged has now been sandwiched are pressure-bonded together at the edges along the peripheral respective sides, even if the single-faced corrugated paperboards 1 are paper members that do not stretch to a large degree, a dimensional excess of the edges caused by deflection of the single-faced corrugated paperboards 1 is absorbed by the waveform bonding, and thus gaps due to wrinkles are eliminated. Therefore, it is possible to protect the commodity from entry of dust or foreign matter, improve the appearance of the bonded portions, and reliably improve the package quality.

[0067] Also, since the pressing members 13 of the pressure-bonding device each includes the low-friction layer as its pressing surface, this prevents cracks in the surface layers of the single-faced corrugated paperboards 1 due to the waveform bonding, thus improving the package quality.

Others

[0068] While, as an example, the above-described pressure-bonding processing is directed to formation of the package of the first embodiment, the pressure-bonding device can also form the package of the second or third embodiment by appropriately changing the arrangement of the pressing members 13 and 14 and/or the method for supplying a single-faced corrugated paperboard or paperboards 1.

[0069] Also, while, in each of the above embodiments, the package in which a single-faced corrugated paperboard or paperboards are used as a paper member or members, and the pressure-bonding device for pressure-bonding the paperboard(s) were described, the present invention is also applicable to paper members other than the single-faced corrugated paperboard(s). For example, by using the present invention, in a package in which an item to be packaged is sandwiched between two paper members each comprising a single layer, too, it is possible to prevent gaps at the edges.

EXAMPLES

Specific Examples and Evaluation of Waveform Bonding

[0070] For evaluation of specific examples of the waveform bonding, specific names relating to dimensions of portions of a package are shown in FIG. 11. Here, the length of a single-faced corrugated paperboard deflected by sandwiching a commodity is denoted by a thick solid line. The actual or imaginary flat-bonding length of an edge is denoted by a thin broken line, and the waveform bonding length of an edge is denoted by a thick broken line. Corresponding to FIG. 1B, the width dimensions of bonding margins for bonding that are orthogonal to the edge subjected to the flat-bonding or the waveform bonding are denoted by a.

Effect of Parameters of Wave Shape on Bondability and Appearance

[0071] Various packages were actually formed to confirm the effect of parameters (length, number of waves, etc.) of a wave shape on bondability and appearance. The results are shown in Table 1.

[0072] Here, single-faced corrugated paperboards were used that are each constituted by a front linerboard of class LC, 120 g/m.sup.2 and a corrugated medium of E flute of class MC, 115 g/m.sup.2, and that have a size of width 300 mm?conveyance direction 250 mm. The bonding margins a for bonding were set to 8 mm.

[0073] Items to be packaged were used that have a size of width 197 mm x conveyance direction 160 mm x height 25 mm.

[0074] Wave shapes were selected from those shown in Table 2 and Table 3, and used.

[0075] The flat-bonding length (imaginary linear distance) and the waveform bonding length shown in tables inserted below are calculated values, and evaluation was performed using jigs manufactured based on these values.

TABLE-US-00001 TABLE 1 Effects of parameters of corrugated shape on bondability and appearance Length of single-faced 250 corrugated paperboard [mm] Flat-bonding length [mm] 229.6 (Imaginary linear distance) Corrugation bonding length [mm] 231.6 233.6 239.6 Number of waves 2 3 5 10 2 3 5 10 2 3 5 10 Bondability O O O O O O O O O O O O Appearance O O O O ? ? ? ? O O O O [Evaluation criteria] [Bondability] O: No problem ?: No problem [Appearance] O: No problem (Vertical displacement of the material was outstanding) O: No problem (Wrinkles were slightly outstanding)

TABLE-US-00002 TABLE 2 Corrugated shape specification Corrugation bonding Number Pitch of Height of length [mm] of waves wave [mm] wave [mm] 231.6 2 75 5.4 231.6 3 50 3.6 231.6 5 30 2.2 231.6 10 15 1.0 233.6 2 75 7.6 233.6 3 50 5.0 233.6 5 30 3.0 233.6 10 15 1.6 239.6 2 75 12.0 239.6 3 50 8.0 239.6 5 30 4.8 239.6 10 15 2.4 * The size of the single-faced corrugated paperboard in the conveyance direction is fixed to 250 mm.

[0076] In the cases shown in Table 1, the bondability was excellent irrespective of the waveform bonding length and the number of waves.

[0077] In the case of waveform bonding length<length of single-faced corrugated paperboard?2a, wrinkles are likely to occur, but the degree of the wrinkles is small, and thus it is considered that there is no problem.

[0078] Even when a different material and/or a different flute was used with respect to the single-faced corrugated paperboards, a similar tendency was seen. For example, a similar tendency was seen also when using kraft paper of 50 g/m.sup.2?50 m.sup.2; and using, as constituent parts, a front linerboard of class LC, 120 g/m.sup.2 and a corrugated medium of B flute of class MC, 115 g/m.sup.2.

Effect of Difference Between Flat-Bonding and Waveform Bonding on Formable Range

[0079] The effect of the difference in pressure-bonded shape between adhesive-using flat-bonding and waveform bonding on a formable range was confirmed. The results are shown in Table 4.

[0080] Here, single-faced corrugated paperboards were used which are each constituted by a front linerboard of class LC, 120 g/m.sup.2 and a corrugated medium of E flute of class MC, 115 g/m.sup.2, and which have a size of width 300 mm?conveyance direction 250 mm.

[0081] Verification was conducted by using items to be packaged of which the widths were all fixed to 197 mm, and of which the heights and the sizes in the conveyance direction were set to various values as shown in Table 4.

[0082] As for a typical wave shape, the number of waves was set to 3, and d (waveform bonding length?flat-bonding length) was set to 4 mm.

TABLE-US-00003 TABLE 4 Formable ranges of flat-bonding and corrugation bonding Size of commodity in 180 180 160 160 160 160 140 conveyance direction [mm] Height of commodity [mm] 5 10 15 20 25 30 35 Flat-bonding length [mm] 233.8 233.1 232.5 231.2 229.6 227.6 227.2 Corrugation bonding length [mm] 237.8 237.1 236.5 235.2 233.6 231.6 231.2 ? [mm] 0.2 0.9 1.5 2.8 4.4 6.4 6.8 d [mm] 4.0 Bondability Flat-bonding o o o x x x x Corrugation bonding o o o o o o x * ? = Length of single-faced corrugated paperboard-Flat-bonding length-2a d = Corrugation bonding length-Flat-bonding length = 4.0 mm * Length of single-faced corrugated paperboard: 250 mm * Bonding margin for bonding: a = 8 mm [Evaluation criteria] [Bondability] o: No problem x: Not formable

[0083] In case of use of pressing members of flat type, if the height of the commodity is 15 mm or less (? is 1.5 mm or less), sufficient bondability is obtained, whereas if the height of the commodity is 20 mm or more (A is 2.8 mm or more), gaps are generated.

[0084] In case of use of pressing members of waveform type, bonding is impossible under the condition of ??d?2.8 mm, but the formable range is wider than in the flat type.

Conceivable Ranges of Parameters

[0085] The above shows that under the conditions of the sizes and material of the packages actually formed, if the lower limit and the upper limit of the number of waves of waveform bonding are 2 and 10, respectively, and the lower limit and the upper limit of the waveform bonding length are, respectively, the length of the single-faced corrugated paperboard?2a?2.4 mm and the length of the single-faced corrugated paperboard?2a+5.6 mm, the gaps at the edges due to wrinkling are eliminated.

DESCRIPTION OF REFERENCE NUMERALS

[0086] 1: Single-faced corrugated paperboard [0087] 2, 3: Edge [0088] 4: Fold line [0089] 11: Lower die [0090] 12: Upper die [0091] 13: Pressing member [0092] 13a: Die body [0093] 13b: Cushion layer [0094] 13c: Low-friction layer [0095] 14: Pressing member [0096] 15: Cutting blade member [0097] 16: Glue gun