Bending structure of corrugated board and manufacturing method thereof

Abstract

Provided are a bending structure of a corrugated board, a method for manufacturing the same, and a corrugated board product having the bending structure, whereby springback generated during bending can be reduced and the shape of a corner can be stabilized. The corrugated board is provided with a first lining board, a second lining board and core paper, a decorative sheet is pasted on the outer surface of the first lining board, the corrugated board is provided with a cut part which is formed by cutting the second lining board and the core paper and is composed of a first bevel edge part and a second bevel edge part, when the corrugated board is bent, the cut surfaces of the first bevel edge part and the second bevel edge part abut against each other, the first lining board and the decorative sheet form a corner part, and the second lining board and the decorative sheet form a corner part. The cut-in portion has a shape in which the distance between the first and second bevel edge portions becomes smaller from the second panel toward the first panel, and a groove or a tangent portion disposed in the extension direction of the cut-in portion and provided at the bottom of the cut-in portion is provided on the surface of the first panel on the opposite side of the surface on which the decorative sheet is provided. The groove opens in the width direction orthogonal to the extending direction of the cut-in portion, and the tangent portion has a shape in which one tangent and the other tangent are separated in the width direction.

Description

Technical Field

[0001] The invention relates to a bending structure of a corrugated paperboard and a manufacturing method of the bending structure of the corrugated paperboard. Background Art

[0002] Patent Document 1 below describes a packaging cushioning material in which a V-shaped groove is provided in a corrugated cardboard material composed of a front liner, a core paper, a middle liner, and a back liner. The corrugated cardboard material is formed into a substantially L-shaped cross-sectional shape by bending the V-shaped groove so that the groove walls are in contact with each other.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Utility Model Application Laid-Open No. 5-75168 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] In the bending structure of the corrugated cardboard described in Patent Document 1, when the cardboard is bent in a manner such that the groove walls are in contact with each other, the lining plate is compressed on the inner surface side of the corner formed by the bending, so that springback occurs after the corrugated cardboard is bent, and a force is exerted to displace the side walls in directions away from each other, resulting in a problem of difficulty in maintaining the corner in a bent state.

[0008] When the corner formed by bending the corrugated cardboard is viewed from the outside, the corner is formed by forcibly compressing the backing sheet of the corrugated cardboard, and there are problems such as the shape of the ridge line of the corner being disordered in a meandering manner along the extension direction, or the apex of the corner being an arc shape lacking sharpness, or the shape of the corner being unstable.

[0009] The object of the present invention is to provide a corrugated cardboard bending structure capable of reducing springback generated when the corrugated cardboard is bent and stabilizing the shape of the corner, a corrugated cardboard product having the bending structure, or a method for manufacturing the corrugated cardboard bending structure.

[0010] Solutions for solving the above technical problems

[0011] The above technical problem is solved by the following corrugated cardboard bending structure, which is a corrugated cardboard bending structure having a first liner, a second liner and a core paper sandwiched between the first liner and the second liner, a decorative sheet is attached to the outer surface of the first liner, and the corrugated cardboard has a cutting portion consisting of a first oblique edge portion and a second oblique edge portion, and the cutting portion is a shape formed by cutting the second liner and the core paper, when the corrugated cardboard is bent, the cutting surface of the first oblique edge portion abuts against the cutting surface of the second oblique edge portion, and the first liner and the decorative sheet form a corner, The cut-in portion is a shape in which the interval between the first bevel portion and the second bevel portion becomes smaller from the second lining plate toward the first lining plate, and a groove or tangent portion arranged along the extension direction of the cut-in portion is provided on the surface of the first lining plate opposite to the surface on which the decorative sheet is provided, and the groove or tangent portion is provided at the bottom of the cut-in portion composed of the first bevel portion and the second bevel portion, and the groove is a shape that is open in the width direction orthogonal to the extension direction of the cut-in portion, and the tangent portion is a shape in which one tangent and another tangent are separated in the width direction.

[0012] The above technical problems are solved by the following method for manufacturing a bending structure of a corrugated cardboard, which is a method for manufacturing a bending structure of a corrugated cardboard having a first liner, a second liner and a core paper sandwiched between the first liner and the second liner, wherein a decorative sheet is attached to the outer surface of the first liner, and the method for manufacturing the bending structure of the corrugated cardboard comprises: a process of cutting off the second liner and the core paper of the corrugated cardboard to form a cut-in portion consisting of a first oblique side portion and a second oblique side portion; and a process of forming a groove or a tangent portion arranged along the extension direction of the cut-in portion on the surface of the first liner opposite to the surface on which the decorative sheet is provided, wherein the cut-in portion is a shape in which the interval between the first oblique side portion and the second oblique side portion decreases from the second liner toward the first liner, the groove is provided at the bottom of the cut-in portion consisting of the first oblique side portion and the second oblique side portion, the groove is a shape in which it is open in the width direction orthogonal to the extension direction of the cut-in portion, and the tangent portion is a shape in which one tangent and another tangent are separated in the width direction.

[0013] The above technical problem is solved by a coffin made of corrugated cardboard with the above bending structure or a corrugated cardboard product with the above bending structure.

[0014] In the bending structure of the corrugated cardboard, the corrugated cardboard product having the bending structure, or the manufacturing method of the bending structure (hereinafter referred to as the bending structure, etc.), the springback when the corner is bent is reduced, the winding of the ridge line of the corner is reduced, the apex of the corner becomes sharp, and the shape of the corner is stable.

[0015] In the folding structure of the corrugated cardboard, etc., the concave groove can be formed into a shape obtained by removing a predetermined width from a material constituting the first liner.

[0016] In the folding structure of the corrugated cardboard, the width of the groove can be set to 0.3 to 3 mm.

[0017] In the folding structure of the corrugated cardboard, etc., the depth of the groove can be set to 10 to 50% of the thickness of the first liner.

[0018] In the folding structure of the corrugated cardboard, etc., the first oblique side portion and the second oblique side portion may be fixed by an adhesive.

[0019] In the folding structure of the corrugated cardboard, it is preferred that the groove provided on the surface of the first lining board opposite to the surface provided with the decorative sheet has a cutting line provided along the extending direction of the groove. According to this configuration, the meandering of the ridgeline of the corner can be further reduced.

[0020] According to the present invention, there can be provided a corrugated cardboard bending structure capable of reducing the springback generated when the corrugated cardboard is bent and stabilizing the shape of the corner, a corrugated cardboard coffin having the bending structure, corrugated cardboard furniture, or a method for manufacturing a corrugated cardboard bending structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a front view showing an example of a folding structure of a corrugated cardboard.

[0022] Figure 2 yes Figure 1 An enlarged view of the portion surrounded by the dot-dash line.

[0023] Figure 3 is a front view showing another example of the bending structure of the corrugated cardboard, which is equivalent to Figure 1 An enlarged view of a portion of the area enclosed by the dot-dash line.

[0024] Figure 4 It is a schematic diagram showing Figure 3 A diagram showing the compression produced when the bending structure of the corrugated cardboard is bent.

[0025] Figure 5 is a front view showing another example of the bending structure of the corrugated cardboard, which is equivalent to Figure 1 An enlarged view of a portion of the area surrounded by the dot-dash line.

[0026] Figure 6 This is a front view showing a state where the corrugated cardboard is bent around the cut portion.

[0027] Figure 7 This is a front view showing the folding structure of the corrugated cardboard of Example 1.

[0028] Figure 8 yes Figure 7 An enlarged view of the portion surrounded by the dot-dash line in FIG.

[0029] Fig. 9 is a front view showing the bending structure of the corrugated cardboard of Example 3, and is a view showing the equivalent Figure 7 An enlarged view of a portion of the area surrounded by the dot-dash line.

[0030] Fig.10 is a front view showing the bending structure of the corrugated cardboard of Comparative Example 1, and is a view showing the equivalent Figure 7 An enlarged view of a portion of the area surrounded by the dot-dash line.

[0031] Fig.11 This is a photograph of the corner of the test piece of Example 1 taken from above.

[0032] Fig.12 This is a 3D model of the corner area of ​​the test piece of Example 1.

[0033] Fig.13 This is a photograph of the corner of the test piece of Example 2 taken from above.

[0034] Fig.14 This is a 3D model of the corner area of ​​the test piece of Example 2.

[0035] Fig.15 This is a photograph of the corner of the test piece of Example 3 taken from above.

[0036] Fig.16 Yes Fig.15 A magnified photo of a portion of the.

[0037] Fig.17 This is a photograph of the corner of the test piece of Comparative Example 1 taken from above.

[0038] Fig.18 Yes Fig.17 A magnified photo of a portion of the.

[0039] Fig.19 This is a 3D model of the corners and surrounding areas of the test piece of Comparative Example 1.

[0040] Fig. 20 This is a diagram of an embodiment of the corrugated cardboard bending structure of the present invention. DETAILED DESCRIPTION

[0041] The following describes the folding structure of corrugated cardboard of the present invention, the embodiment of the manufacturing method of the folding structure, and the use example of the folding structure of corrugated cardboard. The embodiments shown below are only limited examples of the embodiments of the present invention, and the technical scope of the present invention is not limited to the exemplified embodiments.

[0042] [Bending structure of corrugated cardboard]

[0043] exist Figure 1 and Figure 2 An embodiment of a bending structure of a corrugated cardboard (hereinafter referred to as a bending structure) is shown in FIG. The bending structure 1a of this embodiment is applicable to a corrugated cardboard having a first liner 11, a second liner 12, and a core paper 21 (first core paper) sandwiched between the first liner 11 and the second liner 12. Figure 1 As shown, the corrugated cardboard 41 has a double-layer structure including a second core paper 212 and a third liner board 13 .

[0044] The first liner 11, the second liner 12, and the third liner 13 are made of a known material that constitutes a normal corrugated cardboard. The first liner 11, the second liner 12, and the third liner 13 are made of cardboard. The thickness of the first liner 11, the second liner 12, and the third liner 13 is not particularly limited, and is, for example, 0.2 to 2 mm.

[0045] The core paper 21 is a sheet material called corrugated that has been processed into a corrugated shape. When a corrugated cardboard with one core paper 21 is set as a single-layer structure, and a corrugated cardboard with two or more core papers is set as a multi-layer structure, the number of layers of the corrugated cardboard applicable to the bending structure is not limited, and it can be either a single layer or a multi-layer. The bending structure of this embodiment is applicable to a corrugated cardboard with a double-layer structure.

[0046] The thickness of the core paper is not particularly limited, and is, for example, 0.3 to 6.0 mm. The thickness of the core paper refers to the distance between the top apex and the bottom apex of the corrugation.

[0047] The decorative sheet 31 is attached to the outer surface of the first liner 11. The first core paper 211 is fixed to the inner surface of the first liner 11. The second liner 12 is fixed to the first core paper 211. Furthermore, the second core paper 212 is fixed to the second liner 12, and the third liner 13 is fixed to the second core paper 212. The inner surface of the third liner 13 becomes the inner surface of the corrugated cardboard.

[0048] The corrugated cardboard 41 has a cut-in portion 14 formed of a first bevel portion 141 and a second bevel portion 142. The cut-in portion 14 is a shape obtained by cutting out the second liner 12 and the first core paper 211. The first bevel portion 141 and the second bevel portion 142 are shapes obtained by also cutting out the third liner 13 and the second core paper 212. The cut-in portion 14 is a shape in which the interval between the first bevel portion 141 and the second bevel portion 142 decreases from the second liner 12 toward the first liner 11, and has an inclined surface that slopes downward toward the vertex of the corner. When the cut-in portion 14 is viewed from the front, the first bevel portion 141 and the second bevel portion 142 form a V-shaped groove. In addition, in Figure 1In the embodiment, the first oblique side portion 141 and the second oblique side portion 142 are formed by cutting the corrugated cardboard with a cutter. Figure 1 In , the surface through which the tool passes is indicated by a dotted line. Figure 2 The same will be true in the future.

[0049] If one end of the corrugated cardboard is Figure 4 The corrugated paperboard 41 is bent along the cut-in portion 14 by rotating in the direction indicated by the arrow. Figure 6 As shown, the cut surface of the first oblique side portion 141 abuts against the cut surface of the second oblique side portion 142, and the first liner 11 and the decorative sheet 31 form a corner 42. An adhesive is applied to the inner surface side of the corrugated cardboard to fix the corner 42. As the adhesive, a known hot melt adhesive can be preferably used.

[0050] In the bending structure of the present embodiment, a groove 151 arranged along the extension direction of the cut-in portion 14 is provided on the surface of the first lining plate 11 on the opposite side of the surface on which the decorative sheet 31 is provided. The groove 151 is provided at the bottom 152 of the cut-in portion 14 formed by the first oblique side portion 141 and the second oblique side portion 142. The groove 151 is a shape that is open in the width direction orthogonal to the extension direction of the cut-in portion 14. The above-mentioned groove 151 is a straight line extending along the extension direction of the cut-in portion 14 by removing the raw material constituting the first lining plate 11 by a predetermined width. When removing the raw material by a predetermined width, it is sufficient to form a plurality of parallel tangent lines and remove the raw material along the tangent lines.

[0051] The width of the groove 151 can be set to 0.3 to 3 mm. The width of the groove 151 is preferably set to be greater than 0.4 mm, and more preferably set to be greater than 0.8 mm. The width of the groove 151 is preferably set to be less than 2 mm, and more preferably set to be less than 1.5 mm. The depth of the groove 151 is made smaller than the thickness of the first lining plate 11. The depth of the groove 151 can be set to 10 to 50% of the thickness of the first lining plate. If the depth of the groove 151 exceeds the above range, when the first bevel portion 141 is brought into contact with the second bevel portion 142, the decorative sheet is sometimes damaged near the apex of the bending portion, resulting in damage to the beauty of the bending structure.

[0052] Preferably, the two side surfaces forming the groove 151 extend in the thickness direction of the first liner, and are substantially square when the groove is viewed from the front. If the two side surfaces forming the groove extend in an inclined manner so as to be substantially triangular when viewed from the front, this may cause the decorative sheet to break at the vertex of the corner when the corrugated cardboard is bent to form a corner.

[0053] In the bending structure 1a of this embodiment, Fig. 20It is clear that the groove 151 is a shape that is open in the width direction that is orthogonal to the extension direction of the cut-in portion. When the corrugated cardboard 41 is bent along the cut-in portion 14, the first lining plate 11 and the decorative sheet 31 are bent along the groove 151. When bending a corrugated cardboard that only has the cut-in portion 14 but no groove 151, the inner surface of the corrugated cardboard is compressed and becomes a cause of rebound. By providing the groove 151, the compression of the inner surface of the corrugated cardboard is reduced, and the rebound generated when the corrugated cardboard is bent is reduced. In addition, the meandering of the ridge line of the corner formed when the corrugated cardboard 41 is bent is reduced, and a corner with a ridge line extending in a straight line can be formed. In addition, the phenomenon that the inner surface of the corrugated cardboard is compressed when the corrugated cardboard is bent is mainly caused when the inner surface of the corrugated cardboard is compressed. Figure 6 The area marked C in the figure is produced.

[0054] [Second embodiment]

[0055] exist Figure 3 and Figure 4 A bending structure according to a second embodiment is shown. The bending structure 1 b of this embodiment is different from the bending structure 1 a described above in that the bending structure 1 b includes a tangent portion 16 instead of the concave groove 151 described above.

[0056] In the bending structure 1b of the present embodiment, a tangent portion 16 arranged along the extending direction of the cut-in portion 14 is provided on the surface of the first lining plate 11 on the opposite side to the surface on which the decorative sheet 31 is provided. The tangent portion 16 is provided at the bottom 152 of the cut-in portion 14 formed by the first oblique side portion 141 and the second oblique side portion 142. The tangent portion 16 is shaped such that one tangent line 161 and another tangent line 162 are separated in the width direction. The width and depth of the tangent lines 161 and 162 can be set to be the same as those of the above-mentioned groove 151. The number of tangent lines is not particularly limited, as long as it is two or more.

[0057] It is preferable that the tangent line of the tangent line portion 16 is formed so as to descend downward.

[0058] When the corrugated cardboard 41 is bent along the cut-in portion 14, the first liner 11 and the decorative sheet 31 are bent along the cut-line portion 16. Figure 4 As shown by the middle arrow, the compressed area of ​​the inner surface of the corrugated cardboard 41 is limited to the inner side of the outermost tangent lines 161 and 162, and the inner surface of the corrugated cardboard 41 is compressed toward the inner side of the tangent lines 161 and 162. As a result, regularity is generated in the compressed area of ​​the inner surface of the corrugated cardboard, so that the above area is along the extension direction of the tangent part 16. As a result, the rebound generated when the corrugated cardboard is bent can be reduced. In addition, the meandering of the ridgeline of the corner formed when the corrugated cardboard 41 is bent is reduced, and a corner with a straight-line extending ridgeline can be formed.

[0059] [Third embodiment]

[0060] exist Figure 5 The bending structure of the third embodiment is shown. The bending structure 1c of the present embodiment is different from the above-mentioned bending structure 1a in that the concave groove 151 of the bending structure 1a further includes a cutting line 153.

[0061] The cutting line 153 is provided along the extending direction of the groove 151. The width of the cutting line 153 is smaller than the width of the groove 151. The width of the cutting line 153 is not particularly limited, and can be set to 0.01 to 0.3 mm, for example. The depth of the cutting line 153 is not allowed to penetrate the first liner 11. The depth of the cutting line 153 is not particularly limited, and can be set to 8 to 22% of the thickness of the first liner, for example.

[0062] Providing the cut line 153 in the groove 151 can prevent the decorative sheet from being broken near the apex of the corner when the corrugated cardboard is bent, and can further reduce the meandering of the ridgeline of the corner compared to the bending structure 1a having the groove 151.

[0063] [Modifications]

[0064] The groove 151, the tangent line 162 and the cut-in line 153 may be as follows Figure 1 As shown in the figure, the convex or concave part of the corrugated paper 21 is arranged along the concave and convex part, and the convex or concave part of the corrugated paper 21 can also be arranged as shown in the figure. Figure 7 As shown, the corner 42 is arranged in a direction intersecting the convex or concave portion. When the cut-in portion 14 is arranged in the direction along the convex or concave portion and the corrugated cardboard is bent, a part of the convex or concave portion cut at the first oblique side portion 141 and the second oblique side portion 142 appears in a manner along the extension direction of the cut-in portion. According to this structure, when the corrugated cardboard is bent, the contact area between the first oblique side portion 141 and the second oblique side portion 142 becomes smaller, and the shape of the corner 42 is difficult to stabilize. By applying the above-mentioned bending structures 1a, 1b, 1c, even when the groove 151, the tangent line 162 and the cut-in line 153 are arranged in the direction along the convex or concave portion, the shape of the corner 42 is easy to stabilize.

[0065] [Method for manufacturing a folded structure of corrugated cardboard]

[0066] The above-mentioned bending structure can be manufactured, for example, as described below. That is, a method for manufacturing a bending structure of a corrugated cardboard, which is a method for manufacturing a bending structure of a corrugated cardboard having a first liner 11, a second liner 12, and a core paper 21 sandwiched between the first liner 11 and the second liner 12, wherein a decorative sheet 31 is attached to the outer surface of the first liner 11, and the method for manufacturing a bending structure of the corrugated cardboard comprises: a step of cutting off the second liner 12 and the core paper 21 of the corrugated cardboard to form a cut-in portion 14 consisting of a first oblique edge portion 141 and a second oblique edge portion 142; and on the surface of the first liner 11 opposite to the surface on which the decorative sheet 31 is provided, A process for forming a groove 151 or a tangent portion 16 arranged along the extension direction of the cut-in portion 14, wherein the cut-in portion 14 is a shape in which the interval between the first bevel portion 141 and the second bevel portion 142 becomes smaller from the second lining plate 12 toward the first lining plate 11, the groove 151 is provided at the bottom 152 of the cut-in portion 14 composed of the first bevel portion 141 and the second bevel portion 142, the groove 151 is a shape open in the width direction orthogonal to the extension direction of the cut-in portion 14, and the tangent portion 16 is a shape in which a tangent 161 and another tangent 162 are separated in the width direction.

[0067] The cut-in portion 14 can be formed on the inner surface side of the corrugated cardboard by a known method. For example, the cut-in portion 14 can be formed by a cutting device having a rotating knife having a cross-sectional shape corresponding to the cross-sectional shape of the cut-in portion. After the cut-in portion 14 is formed, a plurality of tangents are formed at the bottom of the cut-in portion 14. The first liner 11 between one tangent 161 and another tangent 162 can be easily removed by applying an external force. Thus, the groove 151 can be formed. The width or depth of the groove 151 can be adjusted by the interval between one tangent 161 and another tangent 162. The depth of the groove 151 can be adjusted by the depth of the tangent. If the first liner 11 surrounded by one tangent 161 and another tangent 162 is not removed and remains as it is, it becomes the tangent portion 16.

[0068] In the case where the corrugated cardboard has a multi-layer structure with multiple core papers, the first oblique edge portion 141 and the second oblique edge portion 142 are the shapes of the liner boards other than the first liner board 11, such as the first core paper 211, the second core paper 212 and the third core paper, and the second liner board 12, the third liner board 13 and the fourth liner board, which are cut off. If the first liner board is damaged or cut when forming the cut-in portion, the shape of the corner after bending will be affected. Therefore, when forming the cut-in portion 14, it is preferred not to cut the first liner board 11. In addition, the number of liner boards and the number of core papers vary according to the number of layers of the corrugated cardboard.

[0069] A cutting line 153 is provided at the bottom portion of the groove 151. The cutting line 153 can be formed by, for example, a cutter having a width smaller than that of the groove 151 or the cutting portion 16.

[0070] [Example of use]

[0071] The above-mentioned bending structure of the corrugated cardboard can be preferably used for corrugated cardboard products that require beautiful corners formed by bending the corrugated cardboard. Examples of such corrugated cardboard products include coffins made of corrugated cardboard; tool boxes for storing tools therein; gift boxes for storing food such as snacks or electronic devices such as mobile phones; other containers; or furniture made of corrugated cardboard such as cupboards, beds, tables, chairs or cabinets. In the above-mentioned corrugated cardboard products, sometimes the ridges of the corners formed by bending the corrugated cardboard are meandering, or the apex of the corners is not a right angle but an arc with a relatively large radius, which indeed gives the corrugated cardboard a cheap appearance. In the corrugated cardboard products to which the above-mentioned bending structure of the corrugated cardboard is applied, the appearance of the corners is close to a right angle, and even if it is made of corrugated cardboard, it can be finished to an appearance close to that of a wooden product.

[0072] [Example]

[0073] The following is a more specific description of the present invention by way of examples. The following examples are merely limited examples, and the technical scope of the present invention is not limited to the examples.

[0074] [Example 1]

[0075] Made by the following method Figure 7 and Figure 8 The bending structure 1d shown. The bending structure 1d has the same structure as the bending structure 1c ( Figure 5 ) has the same structure. However, in the bending structure 1d, the cutting portion 14 is arranged in a direction intersecting with the extension direction of the convex or concave portion of the concave-convex corrugation constituting the core paper 21. A V-shaped cutting portion 14 is formed on a double-layer structure corrugated cardboard 41 to which a decorative sheet 31 with a thickness of 60 μm is attached, and a groove 151 is formed at the bottom 152 of the cutting portion 14 composed of a first oblique side portion 141 and a second oblique side portion 142. At the bottom part of the groove 151, a cutting line 153 is provided along the extension direction of the groove 151. The width of the opening of the cutting portion 14 is 20 mm, the angle formed by the second oblique side portion 142 and the first liner 11 is 45°, and the angle formed by the first oblique side portion 141 and the first liner 11 is 135°.

[0076] The width of the groove 151 is 1 mm, and the depth of the groove 151 is 40% of the thickness of the first lining plate 11. The depth of the cutting line 153 is 16.6% of the thickness of the first lining plate.

[0077] The thickness of the first liner 11 is 0.6 mm, the thickness of the second liner 12 is 0.3 mm, and the thickness of the third liner 13 is 0.6 mm. The thickness of the first core paper 211 and the second core paper 212 are 4 mm respectively. The overall thickness of the corrugated cardboard is about 10 mm.

[0078] In the folded structure 1d of the corrugated cardboard produced in the above manner, the corrugated cardboard 41 is folded with the cutout portion 14 as the center. A hot melt adhesive is applied to the inner surface of the folded corrugated cardboard 41 to fix the corner. A photograph of the corner of the corrugated cardboard 41 folded in this way is shown in FIG. Fig.11 In addition, a 3D digitizer (COMET L3D25M manufactured by ZEISS) was used to take a single shot of the folded corrugated cardboard test piece to obtain 3D coordinate data. Fig.12 A 3D model of the corner of the test piece created based on the acquired three-dimensional coordinate data is shown.

[0079] [Example 2]

[0080] Except for omitting the cutting line, the cutting part and the groove extending along the extending direction of the cutting part are formed on the corrugated cardboard in the same manner as in Example 1, and the bending structure of Example 2 is manufactured. Figure 1 and Figure 2 However, the cutout portion is different in that it extends in a direction intersecting with the extending direction of the convex and concave portions forming the corrugations.

[0081] The corrugated cardboard with the bent structure produced in the above manner is bent with the cut-in portion as the center. A hot melt adhesive is applied to the inner surface of the bent corrugated cardboard to fix the corner. A photograph of the corner of the corrugated cardboard bent in this way is shown in FIG. Fig.13 In addition, a 3D digitizer (COMET L3D25M manufactured by ZEISS) was used to take a single shot of the folded corrugated cardboard test piece to obtain 3D coordinate data. Fig.14 The 3D model of the corner of the test piece created based on the acquired three-dimensional coordinate data is shown.

[0082] [Example 3]

[0083] The inner surface of the corrugated cardboard used in Example 1 is cut twice with an inclined flat knife to form a cut-in portion 14g having a first oblique edge portion 141g and a second oblique edge portion 142g on the corrugated cardboard. The front end of the inclined flat knife is made to reach the middle of the first liner 11. Thus, a groove 159 having an inclined oblique edge and having a substantially triangular shape in front view is provided at the bottom of the cut-in portion 14g on the first liner 11. In this way, a Fig. 9The bending structure of the embodiment 3 shown. In addition, the cutouts are provided so as to intersect with the extending direction of the convex and concave portions forming the corrugations.

[0084] For the bending structure of the corrugated cardboard manufactured in the above manner, the corrugated cardboard is bent with the cut-in portion as the center. A hot melt adhesive is applied to the inner surface of the bent corrugated cardboard to fix the corner. Fig.15 and Fig.16 A photograph showing the corner of the corrugated cardboard thus bent.

[0085] [Comparative Example 1]

[0086] In the same manner as in Example 1, except that the cut line and the recess are omitted, the cut portion 14 is formed on the corrugated cardboard, and a stripe 158 is formed on the bottom 152 of the cut portion 14 using a cutting knife to set the starting point of the bend at the corner. The depth of the cut line is 0.2 mm. Fig.10 The folded structure 1f of Comparative Example 1 is shown. In addition, the cutout portion 14 is provided so as to intersect with the extending direction of the convex portions and concave portions forming the corrugations.

[0087] For the folded structure 1f of the corrugated cardboard produced as described above, the corrugated cardboard is folded with the cut-in portion as the center. A hot melt adhesive is applied to the inner surface of the folded corrugated cardboard to fix the corner. Fig.17 and Fig.18 A photograph of the corner of the corrugated cardboard bent in this way is shown. In addition, a 3D model of the corner of the test piece of the bent corrugated cardboard was made in the same manner as above. Fig.19 The produced 3D model is shown.

[0088] In the bending structures of the corrugated cardboard of Examples 1, 2, and 3, the springback generated when the corrugated cardboard is bent along the cut-in portion is extremely small, and the corner portion can be formed with a small force. On the other hand, in the bending structure of the corrugated cardboard of Comparative Example 1, the springback generated when the corrugated cardboard is bent along the cut-in portion is strong, and if the hand is released, the corrugated cardboard bent at the cut-in portion opens. As a result, the application of the adhesive becomes extremely complicated.

[0089] In the bending structures of the corrugated paperboards of Embodiments 1, 2 and 3, as Figures 11 to 16 As shown in FIG. 1 , the apex of the corner is bent sharply compared to the bending structure of the corrugated cardboard of Comparative Example 1. Figures 17 to 19 As shown, compared with the bending structures of the corrugated paperboards of Examples 1 to 3, the angle of the apex of the corner portion is bent more bluntly. Fig.12 and Fig.14 and Fig.19It is clear from the comparison that, when assuming the radius of a circle tangent to the vertex of the bent portion, the radius of the imaginary circle in the bent structures of Examples 1 and 2 is significantly smaller than the radius of the imaginary circle in the bent structure of Comparative Example 1. In addition, the fact that the vertex of the corner is sharp means that the vertex of the corner appears to be closer to 90 degrees in appearance observed with the naked eye.

[0090] In the bending structure of the corrugated paperboard of Examples 1 and 2, as Fig.11 and Fig.13 As shown in FIG. 1 , there is no damage to the decorative sheet around the apex of the corner, and the corner maintains a beautiful appearance. Fig.11 and Fig.13 In the embodiment, the ridge part reflects light and appears white. On the other hand, in the bending structure of the corrugated board of Comparative Example 1, Fig.18 As shown in "B" in the figure, the breakage of the decorative sheet was observed, which was believed to be caused by the decorative sheet being stretched around the apex of the corner. Fig.15 and Fig.16 As shown, in the folded structure of the corrugated cardboard of Example 3, damage of the decorative sheet was also observed around the apex of the corner. In Example 3, the decorative sheet was damaged in a wide range extending along the ridgeline of the corner.

[0091] In the bending structure of the corrugated paperboard of Comparative Example 1, Fig.18 As shown in "A" in the figure, the ridgeline of the corner becomes a shape that meanders left and right, and the beauty of the corner is significantly damaged. On the other hand, in the bending structure of the corrugated cardboard of Example 1, Example 2 and Example 3, as shown in the figure, Fig.11 and Fig.13 as well as Fig.15 As shown, the ridges at the corners extend in a straight line along the extension direction of the grooves, and the meandering of the ridges at the corners cannot be observed with the naked eye. When the ridges are traced with fingers, it can be perceived that the bending structure of the corrugated cardboard of Example 1 is less meandering than the bending structures of the corrugated cardboards of Examples 2 and 3, and the ridges extend in a straight line.

[0092] Description of Reference Numerals

[0093] 1 a Bending structure

[0094] 1 b bending structure

[0095] 1 c bending structure

[0096] 111st lining

[0097] 12 2nd lining plate

[0098] 41 Corrugated cardboard

[0099] 31 Decorative sheet

[0100] 21 core paper

[0101] 141 1st hypotenuse

[0102] 142 2nd hypotenuse

[0103] 14 Cutting section

[0104] 151 grooves

[0105] 152 bottom

[0106] 159 grooves

[0107] 16. Tangent

[0108] 161 Tangent

[0109] 162 Tangent.

Claims

1. A bending structure of a corrugated board, characterized in that: The invention relates to a folding structure of a corrugated cardboard having a first liner, a second liner and a core paper sandwiched between the first liner and the second liner. A decorative sheet is attached to the outer surface of the first lining plate. The corrugated paperboard has a cut-in portion consisting of a first oblique edge portion and a second oblique edge portion, and the cut-in portion is a shape formed by cutting out the second liner and the core paper. When the corrugated cardboard is bent, the cut surface of the first oblique side portion abuts against the cut surface of the second oblique side portion, and the first lining plate and the decorative sheet form a corner. The cut-in portion is shaped such that the interval between the first oblique side portion and the second oblique side portion decreases from the second lining plate toward the first lining plate. A groove or a tangent portion arranged along the extending direction of the cut-in portion is provided on the surface of the first lining plate opposite to the surface on which the decorative sheet is provided. The groove or tangent portion is provided at the bottom of the cut-in portion formed by the first oblique side portion and the second oblique side portion. The groove is open in a width direction perpendicular to the extending direction of the cut-in portion. The tangent line portion has a shape in which one tangent line and another tangent line are separated in the width direction.

2. The bending structure of the corrugated board according to claim 1, characterized in that: The groove is a shape obtained by removing a predetermined width from a raw material constituting the first lining plate.

3. The bending structure of the corrugated board according to claim 1 or 2, characterized in that: The width of the groove is 0.3-3 mm.

4. The bending structure of the corrugated board according to claim 1 or 2, characterized in that: The depth of the groove is 10 to 50% of the thickness of the first lining plate.

5. The bending structure of the corrugated board according to claim 1 or 2, characterized in that: The first oblique side portion and the second oblique side portion are fixed by an adhesive.

6. The bending structure of the corrugated board according to claim 1 or 2, characterized in that: The groove provided on the surface of the first lining plate opposite to the surface on which the decorative sheet is provided is provided with a cutting line provided along the extending direction of the groove.

7. The bending structure of the corrugated board according to claim 1 or 2, characterized in that: The corrugated paperboard is a multi-layer structure having multiple core papers. The first oblique side portion and the second oblique side portion have shapes obtained by cutting off a plurality of core papers and liner sheets other than the first liner sheet.

8. A corrugated cardboard product, characterized in that: It has the bending structure as claimed in claim 1 or 2.

9. A method for manufacturing a bending structure of a corrugated paperboard, characterized in that: The invention relates to a method for manufacturing a folding structure of a corrugated cardboard having a first liner, a second liner and a core paper sandwiched between the first liner and the second liner. A decorative sheet is attached to the outer surface of the first lining plate. The method for manufacturing the folding structure of the corrugated paperboard comprises: a step of cutting off the second liner and the core paper of the corrugated paperboard to form a cut-in portion consisting of a first oblique side portion and a second oblique side portion; and a step of forming a groove or a tangent portion arranged along the extending direction of the cut-in portion on the surface of the first liner opposite to the surface on which the decorative sheet is provided. The cut-in portion is shaped such that the interval between the first oblique side portion and the second oblique side portion decreases from the second lining plate toward the first lining plate. The groove is provided at the bottom of the cut-in portion formed by the first oblique side portion and the second oblique side portion. The groove is open in a width direction perpendicular to the extending direction of the cut-in portion. The tangent line portion has a shape in which one tangent line and another tangent line are separated in the width direction.

10. The method for manufacturing a bending structure of a corrugated paperboard according to claim 9, characterized in that: The groove is formed by removing a predetermined width from a raw material constituting the first lining plate.

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