High rigidity corrugated cardboard

Abstract

To provide a high rigidity corrugated cardboard.SOLUTION: A corrugated cardboard is formed by insertion joining, between two pieces of surface materials (paper and others) F, of a corrugated cardboard core CR formed by starting a hinge of every folds (zigzag valley folding A, zigzag ridge-folding B, ridge-folding valley / folding varying C) of a corrugated cardboard core sheet CS formed by applying a line pushing processing of a hinge for all lines of a paper with specified zigzag line Z and a base line L regulated by a gap-free parallel advancing of a parallelogram P, wherein the parallelogram is defined as a unit and is regulated by a line L becoming the base and thereon a hypotenuse having an interior angle θ which is an angle θ smaller than 90 degree, along a base line L and a repetition of a mirror image using the base line as a mirror.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a high-rigidity corrugated board that has high rigidity against out-of-plane (vertical and bending) loads in a corrugated board structure and can be used as the main structural surface material for corrugated board buildings, temporary housing, etc. [Background technology]

[0002] Corrugated cardboard buildings and temporary housing that use them have been attracting particular attention in recent years due to their ease of construction, light weight, low cost, and disaster prevention capabilities. However, they have inherent problems when it comes to the rigidity of their architectural structures. The main reason for this is the fragility of the cardboard that constitutes the bulk of the building. Resolving this problem would also lead to greater use of ecologically compatible paper materials.

[0003] The basic structure of face material corrugated board is a sandwich structure consisting of two face sheets and a core material with unidirectional corrugation. The main purpose of normal corrugated board core material is to protect the internal cargo with cushioning, rather than to maintain rigidity. When so-called honeycomb core is used for the core, high rigidity is maintained, but due to cost restrictions, corrugated material is often used. There is a demand for a low-cost corrugated board structure that is comparable to a honeycomb structure.

[0004] A related concept of sandwich structure, using metal, has been proposed before (Non-Patent Document 1). Assuming that the core material of current corrugated board is called unidirectional corrugation, this sandwich structure using a bidirectional corrugated core material is called Zeta-Core Sandwich. [Prior art documents]

[0005] [Non-patent literature] [Non-patent literature] Miura, K. and Pellegrino, S. Forms and Concepts for Lightweight Structures, Cambridge University Press, 2020, Chapter 7. P.188,Fig.6.31.

[0006] This structural concept was originally proposed for the airframe structure of a supersonic aircraft, and the core material was made of a metal material that can withstand high temperatures, and it was assumed that processing would involve expansion and contraction of the metal, so it cannot be directly applied to paper materials.

[0007] A corrugated board structure is sought for use in corrugated board construction, temporary housing, etc., which essentially has high rigidity against loads perpendicular to its surface and bending rigidity with a minimum amount of material. DISCLOSURE OF THEINVENTION [Means for solving the problem]

[0008] A corrugated cardboard core sheet CS is formed by applying a hinge creasing process to all lines of paper having a zigzag line Z and a baseline L specified by the parallelogram P, which is defined by a parallelogram having a base side L and a hypotenuse side with a smaller interior angle θ on the base side and an angle θ smaller than 90 degrees, and a parallelogram P defined by the parallelogram's translation along the baseline L without gaps and a repetition of its mirror image with the baseline as a mirror.

[0009] All the folds (zigzag valley fold A, zigzag mountain fold B, mountain fold valley fold C) of the cardboard core sheet CS are actuated at hinges to form a cardboard core CR.

[0010] The cardboard is formed by inserting and bonding the cardboard core CR between two sheets of surface material (paper or other) F. Effect of the Invention

[0011] The basic principle of ordinary corrugated board is to form a sandwich structure by inserting a corrugated core material between two sheets of surface paper. However, the corrugated core material is inherently weak against loads perpendicular to the sandwich structure surface. From this point of view, the main purpose is to utilize its cushioning properties, and therefore it is not fully suitable for the purpose of withstanding loads perpendicular to the surface or bending loads.

[0012] Previously, in relation to the sandwich structure used in supersonic aircraft, a sandwich core material was researched and developed that could cool the inside of the structure by adding corrugations in two directions to the core material, which maintains rigidity in two directions and allows the circulation of coolant. It is a composite three-dimensional truss structure made up of a core material and face plates. Although it is a unique idea from a mechanical standpoint, it requires complex processing, and it was thought that it could not be applied to paper materials.

[0013] In fact, as mentioned above, it is extremely difficult to realize a bidirectional corrugation using a metal material, but there is a possible solution using a non-stretchable material such as paper. This is the Developable Dual Corrugated Surface (DDC surface), a solution derived in the process of research and development using a metal material, as described in Non-Patent Document 1.

[0014] Recent research and development has made it possible to produce shapes similar to the core material described above by folding paper appropriately.

[0015] As shown in Figure 1, the DDC surface is defined by a parallelogram P with an interior angle θ of less than 90 degrees on a base side. In a flat state, the DDC surface is composed of a number of parallel zigzag valley fold lines ▲A▼, a number of parallel zigzag mountain fold lines ▲B▼, and parallel, varying horizontal lines ▲C▼.

[0016] On the DDC surface, all folds move in a synchronized and linked manner, which is a one-degree-of-freedom property or constraint. Deformation applied to one part of the elastic body acts similarly to the synapse, the mechanism of information transmission in living organisms. In real elastic bodies, there is a delay in synchronization and the folds are not linked all at once, but the information of the folds applied to one part is transmitted accurately to neighboring regions, albeit with some attenuation.

[0017] The basis for this information can be explained by Maekawa's Theorem, a fundamental origami rule regarding flat folding: "In a flat folding, the difference between the number of mountain folds and the number of valley folds that meet at the intersection of the fold is always 2." Regarding the main topic, since the total number of folds that meet at the intersection is always 4, the possible solutions are limited to 3 mountain folds and 1 valley fold, or 1 mountain fold and 3 valley folds.

[0018] To achieve the state shown in FIG. 1, a sheet of paper with slits as shown in FIG. 2 is prepared. 1. If a specific zigzag line, for example the vertical zigzag line ▲A▼ (slit) on the left end, is pressed using a mold or other tool to create a valley fold (dashed line), the zigzag line will become a valley fold and the peak-valley distribution of the left and right support lines will be determined. 2. As a result of the above operations, the adjacent zigzag line ▲B▼ is changed to a mountain fold (straight line). According to the influence, if this is determined to be a mountain fold, the peak-valley distribution of the left and right support lines ▲c▼, which make the zigzag line a mountain fold, is determined. 3. By alternating the above valley and mountain folds, a core material with a folded structure is generated throughout the entire area up to the right end. 4. The core material is sandwiched between two face materials F1 and F2, and after adjusting the position, they are joined (Figure 3). BEST MODE FOR CARRYING OUT THEINVENTION Example 1

[0019] As shown in the perspective view of Figure 3, the core sheet CS is bonded between two face plates to form a sandwich structure. Figure 4 shows that the face plates and the core sheet form a composite truss structure, which is an effective three-dimensional folded plate structure. [Industrial Applicability]

[0020] In this invention, by mechanically combining corrugated cardboard, which is generally considered to have low strength and rigidity, we provide a simple yet high strength and rigidity structure, which will enable the construction of temporary housing at low cost in the event of a disaster.In addition, the material is highly recyclable, which contributes to ecology. [Brief description of the drawings]

[0021] [Figure 1] : Shows the arrangement of mountain folds and valley folds in the core (developed plan view) [Diagram 2] : Indicates the creasing or slitting positions of the core material (plan view) [Diagram 3] : Structure of the cardboard of the present invention (perspective view). [Figure 4] : Mechanism of the structure composed of the face material and core of the present invention (oblique perspective view). [Explanation of symbols]

[0022] ▲A▼: Valley fold zigzag line ▲B▼: Mountain fold zigzag line ▲C▼: Horizontal fold line (on the drawing) CR: Core CS: Core Sheet F1,F2: Surface plate L: Baseline (Figure 1) M: Mountain fold (solid line) P: Parallelogram unit S: Slit or creasing (dotted line) V: Valley fold (dashed line) Z: Zigzag line (Figure 1) θ: The smallest interior angle of the parallelogram unit

Claims

1. The cardboard core sheet CS is formed by applying a hinge creasing process to all lines of paper having a zigzag line Z and a baseline L specified by a parallelogram P defined by a base side L, a small interior angle θ on the parallelogram, and a hypotenuse side with an angle θ smaller than 90 degrees, and a parallelogram P defined by a gap-free translation along the baseline L and a repetition of a mirror image of the parallelogram with the baseline as a mirror.

2. The cardboard core CR is formed by activating the hinges of all the folds (zigzag valley fold A, zigzag mountain fold B, and varying mountain fold / valley fold C) of the cardboard core sheet CS.

3. The cardboard is formed by inserting and joining the cardboard core CR between two sheets of surface material (paper or other) F.

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