JP2019162830A - Hollow structure and manufacturing method thereof - Google Patents

Abstract

A hollow structure having excellent impact resistance is provided. A hollow structure includes a core layer in which a plurality of cells are juxtaposed, and a pair of skin layers joined to both surfaces of the core layer. The core layer 20 is formed from a sheet material in which one sheet having plasticity is formed into a predetermined shape so as to include an upper wall portion, a lower wall portion 22, and a side wall portion 23. At least one of the wall portions 22 is removed, and the side wall portion 23 is formed with a removed rear edge 23 a in which at least one of the upper wall portion and the lower wall portion 22 is not provided. The skin layer 30 joined to a side of the core layer 20 from which at least one of the upper wall portion and the lower wall portion 22 has been removed is joined to the removed edge 23a. The side wall portion 23 has a two-layer structure including a first side wall portion and a second side wall portion, and is provided with a non-joined portion 23d where the first side wall portion and the second side wall portion are not joined. [Selection diagram] Fig. 1

Description

  The present invention relates to a hollow structure and a manufacturing method thereof.

  The hollow structure has an appropriate strength while being lightweight, and may be used as a component member or building material of various vehicles. Patent Document 1 describes an invention relating to a honeycomb core structure having a hollow structure.

JP 2010-1225637 A

  As shown in FIG. 10 (a), the honeycomb core structure 200 described in Patent Document 1 is formed by stacking a plurality of sheets refracted in a wave shape in the thickness direction. The sheet is formed by connecting a bottom part 201 and a top part 202 through a slope part 203, and the honeycomb core structure 200 has an adhesive layer between the bottom part 201 and the top part 202 of adjacent sheets. It is formed by joining through 204. As shown in FIG. 10 (b), such a honeycomb core structure 200 cut into a predetermined thickness into a plate shape, and a pair of skin layers 300 bonded to both sides thereof can be used as the hollow structure 400. . In the hollow structure 400, the bottom part 201, the top part 202, and the oblique part 203 of the honeycomb core structure 200 serve as side walls that define a plurality of hexagonal columnar cells C, and the pair of skin layers 300 constitute the upper ends of the cells C. And the lower end is sealed.

  In the hollow structure 400 using the honeycomb core structure 200 described in Patent Document 1, a part of the side wall portion of the cell C is firmly joined to the bottom side portion 201 and the top side portion 202 via the adhesive layer 204. Since it has a two-layer structure, it has excellent strength. On the other hand, however, the impact resistance is not sufficient.

  The present invention has been made in order to solve such a conventional problem, and an object thereof is to provide a hollow structure excellent in impact resistance and a method for producing the same.

  In order to solve the above problems, the present invention is a resin hollow structure comprising a core layer in which a plurality of cells are arranged in parallel, and a pair of skin layers bonded to both surfaces of the core layer. The core layer includes a side wall portion standing in the thickness direction to partition the cell, an upper wall portion provided at an upper end edge of the side wall portion, and a lower portion provided at a lower end edge of the side wall portion. A single sheet having plasticity is formed from a sheet material formed into a predetermined shape so as to include a wall portion, and at least one of the upper wall portion and the lower wall portion is removed from the core layer The side wall portion is formed with a removal rear edge where at least one of the upper wall portion and the lower wall portion is not provided, and the upper wall portion and the lower wall portion in the core layer are formed. The skin bonded to the side from which at least one of the Is joined to the removal rear edge of the side wall portion, and the side wall portion has a two-layer structure including a first side wall portion and a second side wall portion, and the side wall portion includes the first side wall portion. And a non-joining part to which the second side wall part is not joined is provided.

  According to said structure, the wall part is not provided in at least any one of the upper end part of the side wall part of a core layer, and a lower end part, but the edge (removal end edge) of a side wall part is formed. And the skin layer joined to the side where the wall portion does not exist is joined to the rear edge of the removal. Therefore, the removal rear edge and the skin layer are joined linearly on at least one surface of the hollow structure. For example, when an impact is applied to one surface of the hollow structure, the impact received on that surface is transmitted to the inside of the hollow structure. When the skin layer on the surface side of the hollow structure is joined linearly to the edge after removal of the core layer, the side wall portion of the core layer is compared to the case where the skin layer is joined to the wall portion of the core layer in a planar shape. And the skin layer is easily deformed. As a result, the impact is easily dispersed and the impact applied to the hollow structure is absorbed.

  Further, the side wall portion (first side wall portion and second side wall portion) of the two-layer structure of the core layer has a non-joined portion where the side wall portions of the two-layer structure are not joined to each other. Therefore, the impact applied to one surface of the hollow structure is also absorbed by the displacement of the first side wall and the second side wall.

  As described above, when an impact is applied to the hollow structure, the shock absorption is increased due to the deformation of the side wall portion or the skin layer of the core layer and the displacement of the side wall portion of the two-layer structure of the core layer. The occurrence of cracks and the like on the surface is suppressed.

  In the above invention, the core layer is formed with a thin portion having a relatively thin thickness by removing at least one of the upper wall portion and the lower wall portion, and the removal rear edge. Is preferably formed in the thin portion.

In the above invention, the skin layer is preferably bonded to the core layer by thermal welding or adhesion.
In order to solve the above problems, the present invention provides a resin-made hollow structure in which a skin layer is bonded to at least one surface of a hollow plate-like core layer in which a plurality of cells are arranged in parallel. A manufacturing method, wherein a sheet material in which a planar region and a bulging region that bulges upward in a polygonal cross section is alternately formed from a single sheet having plasticity, and the sheet material, By removing, the upper surfaces of the adjacent bulging regions are brought into contact with each other, and a side wall portion that divides the plurality of cells having a cylindrical shape and a pair of wall portions provided at both end edges of the side wall portion are removed. A folding step of forming a front core layer, a removal step of removing the wall portion of at least one of the core layers before removal to expose a removal rear edge formed on the side wall portion of the core layer; Join the skin layer to the edge after removal And a bonding step.

  According to said structure, the core layer before removal which has an upper wall part, a lower wall part, and a side wall part is shape | molded by folding one sheet | seat. Therefore, in the core layer before removal, the upper wall portion and the side wall portion, and the lower wall portion and the side wall portion are continuously formed, and the strength is superior to those in which these are not continuously formed. . A removal rear edge is formed on the side wall by removing at least one of the upper wall and the lower wall in the core layer before removal, and a hollow structure is formed by joining a skin layer to the rear edge. Yes. Therefore, in the obtained hollow structure, the skin layer is linearly joined to the rear edge of the removal, and compared with the case where the skin layer is joined to the wall portion of the core layer in a planar shape. The side wall portion and the skin layer are easily deformed. A hollow structure having excellent strength and impact resistance can be obtained. Furthermore, the side wall portion is formed as a two-layer structure in which the upper surfaces of adjacent bulging regions formed in the sheet material are brought into contact with each other. Therefore, the impact applied to one surface of the hollow structure is also absorbed by the shift of the side wall portion of the two-layer structure.

  In the above invention, in the removing step, a part of the wall part of at least one of the core layers before removal is removed to form a thin part having a relatively thin thickness in a part of the core layer. It is preferable that the rear edge of the removal formed on the side wall portion is exposed at the thin portion.

  In order to solve the above problems, the present invention provides a resin-made hollow structure in which a skin layer is bonded to at least one surface of a hollow plate-like core layer in which a plurality of cells are arranged in parallel. A manufacturing method, wherein a sheet material in which a planar region and a bulging region that bulges upward in a polygonal cross section is alternately formed from a single sheet having plasticity, and the sheet material, By removing, the upper surfaces of the adjacent bulging regions are brought into contact with each other, and a side wall portion that divides the plurality of cells having a cylindrical shape and a pair of wall portions provided at both end edges of the side wall portion are removed. A folding step of forming a front core layer; a first joining step of joining an unremoved skin layer to at least one surface of the wall of the pre-removed core layer to form an intermediate; and the removal of the intermediate The front skin layer and the skin layer before removal are joined. Remove the wall portion comprises a removing step of exposing the removed rear end edge which is formed on the side wall of the core layer, and a second bonding step of bonding the skin layer to the removal trailing edge.

  According to said structure, the sheet | seat layer is folded, the core layer before removal which has an upper wall part, a lower wall part, and a side wall part is shape | molded, and the skin layer before removal is joined to the at least one surface Forming the body. Therefore, in the core layer before removal of the intermediate body, the upper wall portion and the side wall portion, the lower wall portion and the side wall portion are respectively formed continuously, and the strength thereof is higher than those in which these are not formed continuously. Are better. By removing at least one of the upper wall portion and the lower wall portion in the intermediate body together with the pre-removal skin layer, a removed rear edge is formed on the side wall portion, and by joining the skin layer to the removed rear edge, the hollow structure is formed. Is formed. Therefore, in the obtained hollow structure, the skin layer is bonded linearly to the rear edge of the removal, and compared with the case where the skin layer is bonded to the wall of the core layer in a planar shape. When an impact is applied to the core layer, the side wall portion and the skin layer of the core layer are easily deformed. A hollow structure excellent in impact resistance can be obtained while having the bending strength of the hollow structure. Furthermore, the side wall portion is formed as a two-layer structure in which the upper surfaces of adjacent bulging regions formed in the sheet material are brought into contact with each other. Therefore, the impact applied to one surface of the hollow structure is also absorbed by the shift of the side wall portion of the two-layer structure.

  In the above invention, in the removal step, a part of the core layer is removed by removing a part of the intermediate skin layer of the intermediate body and a part of the wall portion to which a part of the skin layer before removal is joined. In addition, it is preferable to form a thin portion having a relatively small thickness and to expose a rear edge of the removal formed on the side wall portion at the thin portion.

  According to the present invention, a hollow structure excellent in impact resistance can be obtained.

The perspective view of the hollow structure of a 1st embodiment. The perspective view of the core layer of 1st Embodiment. (A)-(d) is a figure explaining the method to manufacture the hollow structure of 1st Embodiment. (A) is a perspective view of the sheet material which comprises the core layer before removal, (b) is a perspective view which shows the state in the middle of folding of the same sheet material, (c) is a perspective view which shows the state which folded the same sheet material. (A) is a perspective view of the core layer before removal, (b) is a β-β cross-sectional view of (a), and (c) is a γ-γ cross-sectional view of (a). (A), (b) is an expanded sectional view of a hollow structure. (A) is a perspective view of the hollow structure of 2nd Embodiment, (b) is the (sigma)-(sigma) sectional view taken on the line of (a). (A)-(c) is a figure explaining the method to manufacture the hollow structure of 2nd Embodiment. (A) is sectional drawing of the hollow structure of 2nd Embodiment, (b), (c) is sectional drawing of the conventional hollow structure. (A) is a top view of the conventional honeycomb core structure, (b) is a perspective view of a hollow structure using the conventional honeycomb core structure.

Hereinafter, embodiments embodying the present invention will be described. The hollow structure of the present embodiment is applied to, for example, a tatami core material.
(First embodiment)
The hollow structure 10 of 1st Embodiment is demonstrated with reference to FIG.1 and FIG.2.

As shown in FIG. 1, the hollow structure 10 of the present embodiment includes a core layer 20 in which a plurality of cells S are arranged in parallel, a skin layer 30 bonded to the upper surface 20a of the core layer 20, and a core layer. It is comprised as a plate-shaped member provided with the skin layer 40 joined to the lower surface 20b of 20. As shown in FIG. The core layer 20, the skin layer 30, and the skin layer 40 are made of a thermoplastic resin. Moreover, the core layer 20, the skin layer 30, and the skin layer 40 are joined through an adhesive layer made of a thermoplastic resin (not shown). (In FIG. 5 (a) and FIG. 5 (b), it is shown as an adhesive layer 30a.)
The thermoplastic resins constituting the core layer 20, the skin layer 30, and the skin layer 40 are conventionally well-known, and the material is not particularly limited. Examples thereof include polypropylene resin, polyamide resin, polyethylene resin, acrylonitrile-butadiene-styrene copolymer resin, acrylic resin, polybutylene terephthalate resin, and the like. It is preferable that the thermoplastic resin constituting the core layer 20, the skin layer 30, and the skin layer 40 are all the same material. In the present embodiment, all are made of polypropylene resin.

  Moreover, the thermoplastic resin which comprises the contact bonding layer which joins the core layer 20 and the skin layers 30 and 40 is also a conventionally well-known thing, The material is not specifically limited. For example, an olefin type, a polyester type, and a urethane type are mentioned. The adhesive layer is preferably a resin having a lower melting point than the thermoplastic resin constituting the core layer 20, the skin layer 30, and the skin layer 40. In this embodiment, it is composed of a modified polyolefin resin (modified resin) such as a modified polyethylene or a modified polypropylene in which a functional group is introduced into a polyolefin to impart adhesion.

  The thickness of the adhesive layer is preferably 0.1 to 0.5 mm, and more preferably 0.2 to 0.3 mm. When the thickness of the adhesive layer is within this range, sufficient adhesive strength between the core layer 20 and the skin layers 30 and 40 can be obtained. Moreover, while being excellent in the moldability of the hollow structure 10, it is preferable also from a cost viewpoint.

  Note that the pre-removal skin layer 60 described later is also made of a thermoplastic resin made of the same material as the skin layers 30 and 40. An adhesive layer made of a thermoplastic resin having the same configuration as the skin layers 30 and 40 is applied to one surface of the pre-removal skin layer 60, and is bonded to the pre-removal core layer 50 described later via the adhesive layer. Has been.

  As shown in FIG. 2, a plurality of cells S are defined in the core layer 20 so as to be juxtaposed in a direction perpendicular to the thickness direction of the hollow structure 10. The core layer 20 includes a side wall portion 23 that partitions the plurality of cells S, and a lower wall portion 22 that is joined to the lower end edge of the side wall portion 23 so as to close the lower end of the cell S. A wall portion is not provided at the upper end edge of the side wall portion 23, and the upper end of the cell S is opened upward. Therefore, as shown in FIG. 1, in the hollow structure 10, the skin layer 30 bonded to the upper surface 20 a of the core layer 20 is bonded to the upper end edge of the side wall portion 23 of the core layer 20 via an adhesive layer. Will be. On the other hand, the skin layer 40 bonded to the lower surface 20b of the core layer 20 is bonded to the lower wall portion 22 of the core layer 20 via an adhesive layer. The upper end edge of the side wall 23 is a removal rear end edge 23a described later.

  Next, a method for manufacturing the hollow structure 10 will be described with reference to FIGS. The method for manufacturing the hollow structure 10 includes a forming step, a folding step, a first joining step, a removing step, and a second joining step. Specific contents of each step will be described below. In FIG. 3, the manufacturing method of the hollow structure 10 is shown as a series of steps, and in FIG. 4, the folding step is shown.

  As shown in FIG. 4A, in the molding step, the sheet material 100 is formed by heat-molding one thermoplastic resin sheet into a predetermined shape. As shown in FIG. 4A, in the sheet material 100 formed by the forming process, a planar area 110 and a bulging area 120 having a band shape are alternately arranged in the width direction (X direction). In the bulging region 120, a first bulging portion 121 having a cross-section downward groove shape composed of an upper surface and a pair of side surfaces is formed over the entire extending direction (Y direction) of the bulging region 120. The angle formed between the upper surface and the side surface of the first bulge portion 121 is preferably 90 degrees. As a result, the cross-sectional shape of the first bulge portion 121 is a downward U-shape. Further, the width of the first bulging portion 121 (the length of the upper surface in the short direction) is equal to the width of the planar region 110, and the bulging height of the first bulging portion 121 (the length of the side surface in the short direction). ) Is set to be twice as long.

  Further, in the bulging region 120, a plurality of second bulging portions 122 having a trapezoidal shape obtained by dividing the regular hexagon by the longest diagonal line in the bulging region 120 are orthogonal to the first bulging portion 121. Is formed. The bulge height of the second bulge portion 122 is set to be equal to the bulge height of the first bulge portion 121. Further, the interval between the adjacent second bulging portions 122 is equal to the width of the upper surface of the second bulging portion 122.

  The first bulging portion 121 and the second bulging portion 122 are formed by partially bulging the sheet upward using the plasticity of the sheet. The sheet material 100 can be formed from a single sheet by a known forming method such as a vacuum forming method or a compression forming method.

  As shown in FIGS. 4B and 4C, in the folding step, the core material 50 before removal is formed by folding the sheet material 100 configured as described above along the boundary lines P and Q. Is done. Specifically, the sheet material 100 is valley-folded at the boundary line P between the flat region 110 and the bulging region 120 and is folded at the boundary line Q between the upper surface and the side surface of the first bulging portion 121. To compress in the X direction. Then, as shown in FIGS. 4B and 4C, the upper surface and the side surface of the first bulge portion 121 are folded and the end surface of the second bulge portion 122 and the planar region 110 are folded. , One prismatic partition 130 extending in the Y direction with respect to one bulging region 120 is formed. By forming these partition bodies 130 continuously in the X direction, the hollow plate-shaped core layer 50 before removal is formed.

In addition, the thickness of the sheet material 100 forming the core layer 50 before removal is formed thinner than the thickness of the skin layers 30 and 40 and the skin layer 60 before removal.
As shown in FIG. 4C, when the sheet material 100 is compressed, the upper wall portion 21 of the core layer 50 before removal is formed by the upper surface and the side surface of the first bulge portion 121, and the second bulge is formed. The lower wall portion 22 of the core layer 50 before removal is formed by the end face of the portion 122 and the planar region 110.

  As shown in FIG. 5A, in the cell S that is partitioned and formed in the core layer 50 before removal formed by the folding process, there are a first cell S1 and a second cell S2 having different configurations. As shown in FIG. 5B, in the first cell S <b> 1, an upper wall portion 21 having a two-layer structure is provided above the side wall portion 23. Each layer of the upper wall portion 21 of this two-layer structure is joined to each other. Further, an opening (not shown) is formed in the upper wall portion 21 of the two-layer structure due to the thermal contraction of the thermoplastic resin when the core layer 50 before removal is formed. In the first cell S <b> 1, a lower wall portion 22 having a one-layer structure is provided below the side wall portion 23.

  As shown in the partially enlarged view of FIG. 5B, the boundary portion between the side wall portion 23 and the upper wall portion 21 of the first cell S1 is microscopically curved from the side wall portion 23 extending upward in a straight line. However, it is in a state connected to the upper wall portion 21. That is, a curved portion 23 e is formed between the side wall portion 23 and the upper wall portion 21.

  On the other hand, as shown in FIG. 5C, in the second cell S <b> 2, an upper wall portion 21 having a one-layer structure is provided above the side wall portion 23. In the second cell S <b> 2, a lower wall portion 22 having a two-layer structure is provided below the side wall portion 23. The layers of the lower wall portion 22 of this two-layer structure are joined to each other. An opening (not shown) is formed in the lower wall portion 22 of the two-layer structure due to thermal contraction of the thermoplastic resin when the core layer 50 before removal is molded.

  As shown in the partial enlarged view of FIG. 5C, the boundary portion between the side wall portion 23 and the upper wall portion 21 of the first cell S1 is microscopically curved from the side wall portion 23 extending linearly upward. However, it is in a state connected to the upper wall portion 21. That is, a curved portion 23 e is formed between the side wall portion 23 and the upper wall portion 21.

  In addition, as shown in FIG.4 (c), the upper surface and side surface of the 1st bulging part 121 in the upper wall part 21 fold over, and form the 2 layer structure, and the 2nd bulging part in the lower wall part 22 A portion where the end surface 122 and the planar region 110 are folded to form a two-layer structure is an overlapping portion 131.

  In addition, the hexagonal column-shaped region that is partitioned and formed by folding the second bulging portion 122 becomes the second cell S2, and the hexagonal column-shaped region that is partitioned and formed between a pair of adjacent partitions 130 is the first cell S2. One cell S1 is obtained. In the present embodiment, the upper surface and the side surface of the second bulging portion 122 constitute the side wall portion 23 of the second cell S2, and the side surface of the second bulging portion 122 and the second bulging portion 122 in the bulging region 120. The planar portion located between them constitutes the side wall portion 23 of the first cell S1. And the contact part of the upper surface of the 2nd bulging part 122 and the contact part of the said plane parts in the bulging area | region 120 have the 2 layer structure which consists of the 1st side wall part 23b and the 2nd side wall part 23c. The side wall portion 23 is formed. In carrying out such a folding process, it is preferable to keep the sheet material 100 in a softened state by heat treatment.

  As shown in FIG. 5B and FIG. 5C, a side wall portion 23 (first side wall) having a two-layer structure is formed between adjacent first cells S1 and between adjacent second cells S2. Part 23b and second side wall part 23c). The side wall portion 23 of this two-layer structure has a non-joined portion 23d that is a portion that is not thermally welded to the central portion in the thickness direction of the core layer 50 before removal. Therefore, the internal space of each cell S of the core layer 50 before removal communicates with the internal space of another cell S via the non-joining portion 23d between the first side wall portion 23b and the second side wall portion 23c. The non-joining portion 23d is provided in the central portion in the thickness direction of the core layer 50 before removal, that is, in the central portion in the height direction of the side wall portion 23. The upper end portion and the lower end portion of the side wall portion 23 have a two-layer structure. The first side wall part 23b and the second side wall part 23c are thermally welded to each other. 5B, FIG. 5C, FIG. 6A, and FIG. 6B, the two-layer structure of the upper wall portion 21, the lower wall portion 22, and the side wall portion 23 is omitted. As shown.

  As shown in FIG. 5A, the first cells S1 are arranged side by side in a row along the X direction. Similarly, the second cells S2 are arranged side by side so as to form a column along the X direction. The columns of the first cells S1 and the columns of the second cells S2 are alternately arranged in the Y direction orthogonal to the X direction. And by these 1st cell S1 and 2nd cell S2, the core layer 50 before removal has comprised the honeycomb structure as a whole.

  As shown in FIG. 3A, the core layer 50 before removal that includes the upper wall portion 21 and the lower wall portion 22 and in which a plurality of cells S are partitioned by the side wall portion 23 is obtained by the folding process. In addition, the core layer 20 which comprises the hollow structure 10 removes the upper wall part 21 and the upper end part of the side wall part 23 of the core layer 50 before removal in the removal process demonstrated later. Therefore, the side wall part 23 and the lower wall part 22 of the core layer 50 before removal and the side wall part 23 and the lower wall part 22 of the core layer 20 are both represented by the same member number.

  As shown in FIG. 3B, in the first bonding step, the pre-removal skin layer 60 is bonded to the upper surface 50a of the pre-removal core layer 50, and the skin layer 40 is bonded to the lower surface 50b. In the first joining step, flat sheets not subjected to secondary processing (press molding) are joined as the core layer 50 and the skin layer 40 before removal. The same applies to the skin layer 30 in the second bonding step.

  In the first bonding step, the core layer 50 before removal, the skin layer 40, and the skin layer 60 before removal are heated to a predetermined temperature. The heating temperature is set to a temperature that is higher by several degrees C. to tens of degrees C. than the melting point of the adhesive layer in the skin layer 40 and the skin layer 60 before removal. Specifically, the heating temperature is set to be about several degrees C. higher than the melting point of the modified polyolefin adhesive (modified resin) constituting the adhesive layer. This heating temperature is set sufficiently lower than the molding temperature for softening the polyamide resin constituting the core layer 50 before removal, the skin layer 40 and the skin layer 60 before removal. The heating time when the skin layer 40 and the pre-removal skin layer 60 are thermally welded to the pre-removal core layer 50 is set to several seconds to several tens of seconds, and the same portion of the skin layer 40 and the pre-removal skin layer 60 is excessively long. It is not heated for hours. Therefore, the core layer 50 before removal, the skin layer 40, and the skin layer 60 before removal do not reach a high temperature until they are softened and melted, and only the adhesive layer can be softened and melted without strictly controlling the heating temperature.

  When the skin layer 40 and the pre-removal skin layer 60 are aligned with the pre-removal core layer 50, temporarily bonded by applying a predetermined pressure, and then cooled, the skin layer 40 and the pre-removal skin 50 A first intermediate 70 is obtained in which the layer 60 is thermally welded.

  As shown in FIGS. 3B and 3C, in the removal step, the cutting jig T is moved in a direction perpendicular to the thickness direction of the core layer 50 before removal, and the core before removal in the first intermediate body 70. The upper end of layer 50 is removed. Specifically, the cutting jig T is moved toward the upper end portion of the side wall portion 23 of the core layer 50 before removal. The cutting jig T is formed in a thin plate shape with a saw blade provided at the tip, for example, and is heated as necessary. By the removing step, the second intermediate body 80 is obtained in which the upper end portions (upper end portions of the upper wall portion 21 and the side wall portion 23) of the core layer 50 before removal are removed. The second intermediate body 80 includes a core layer 20 and a skin layer 40 bonded to the lower surface 20 b of the core layer 20.

  As shown in FIG. 3C, in the core layer 20 from which the upper end portion of the side wall portion 23 is removed, a removed rear edge 23 a is formed at the upper end edge of the side wall portion 23. Since the cutting jig T is moved in a direction orthogonal to the thickness direction of the core layer 50 before removal, the heights of the plurality of side wall portions 23 formed in the core layer 20 are all substantially the same. Therefore, all the positions in the height direction of the removal rear edge 23a are formed at substantially the same position. In the second intermediate body 80, the upper surface 20a of the core layer 20 is constituted by the removal rear edge 23a.

  Moreover, a part of the side wall part 23 which divides the cell S has a two-layer structure including a first side wall part 23b and a second side wall part 23c, and is thermally welded to the central part in the thickness direction of the core layer 50 before removal. A non-joining portion 23d, which is not a portion, is provided. The upper end portion of the side wall portion 23 removed in the removing step is located near the non-joining portion 23d or a portion of the non-joining portion 23d.

  In the removal step, the cutting jig T is moved toward the upper end portion of the side wall portion 23 to remove the upper end portion of the side wall portion 23. The upper end portion of the side wall portion 23 referred to here is the side wall portion 23 and the upper wall portion. 21 is a boundary portion between the curved portion 23e formed between the side wall portion 21 and the side wall portion 23. By cutting at this position, the removal rear edge 23a becomes linear, and the first side wall part 23b and the second side wall part 23c of the two-layer structure formed thereafter are easily deformed.

  As shown in FIG. 3D, in the second bonding step, the skin layer 30 is bonded to the upper surface 20 a of the core layer 20 in the second intermediate 80. In the second bonding step, the second intermediate 80 and the skin layer 30 are heated to a predetermined temperature as in the first bonding step. The heating temperature and heating time are managed in the same manner as in the first bonding step. By heating the second intermediate 80 and the skin layer 30, the adhesive layer formed on one surface of the skin layer 30 is thermally melted, and the skin layer 30 is thermally welded to the second intermediate 80. A structure 10 is obtained.

Next, the operation of the hollow structure 10 will be described.
In the hollow structure 10, the skin layer 30 is bonded to the upper surface 20 a of the core layer 20. The core layer 20 has a shape in which the upper end portions of the upper wall portion 21 and the side wall portion 23 in the core layer 50 before removal are removed, and a rear removal edge 23 a is formed at the upper end edges of the plurality of side wall portions 23. The positions in the height direction of the plurality of removal rear edges 23a formed through the removal process are all substantially the same position. Therefore, the skin layer 30 and the removal rear edge 23a are joined linearly.

  Moreover, a part of the side wall part 23 of the core layer 20 has a side wall part 23 (a first side wall part 23b and a second side wall part 23c) having a two-layer structure. The layer 20 has a non-joined portion 23d that is not thermally welded to each other at the center in the thickness direction. And the upper end part of the side wall part 23 removed by the removal process is the vicinity upper part of the non-joining part 23d, or the part of the non-joining part 23d.

  When an impact is applied to the upper surface side of the hollow structure 10, the impact received on the upper surface is transmitted to the inside of the hollow structure 10. In the hollow structure 10 of the present embodiment, the skin layer 30 faces the upper wall portion 21 of the core layer 20 because the joint portion between the skin layer 30 and the removal rear edge 23a of the core layer 20 is linear. Compared with the case where it joins in the shape, the side wall part 23 and the skin layer 30 of the core layer 20 become easy to deform | transform. As a result, the impact is easily dispersed and the impact applied to the hollow structure 10 is absorbed.

  Further, in the side wall portion 23 (the first side wall portion 23b and the second side wall portion 23c) of the two-layer structure of the core layer 20, a non-joining portion 23d is provided in the vicinity of the removal rear edge 23a, or the removal rear edge. A non-joining portion 23d is provided in the portion 23a. Therefore, when an impact is applied to the upper surface side of the hollow structure 10, the first side wall portion 23b and the second side wall portion 23c are likely to be displaced. This shift also absorbs the impact.

  As described above, when an impact is applied to the hollow structure 10, the side wall 23 and the skin layer 30 of the core layer 20 are deformed, and the shock absorption is caused by the shift in the side wall 23 of the two-layer structure of the core layer 20. And the occurrence of cracks and the like on the surface of the hollow structure 10 is suppressed.

  On the other hand, the first intermediate body 70 obtained during the manufacturing of the hollow structure 10 has the unremoved skin layer 60 joined to the upper wall portion 21 of the unremoved core layer 50 by thermal welding. The upper wall portion 21 covers the entire upper surface of the core layer 50 before removal, and the skin layer 60 before removal is bonded to the entire surface of the upper wall portion 21 by a surface. On the upper surface of the first intermediate body 70, the core layer 50 before removal and the skin layer 60 before removal are firmly joined. Therefore, when an impact is applied to the upper surface side of the first intermediate body 70, the upper wall portion 21 and the pre-removal skin layer 60 of the core layer 50 before removal that are firmly bonded receive the impact. Therefore, the impact is not easily absorbed, and cracks and the like are likely to occur on the surface of the first intermediate body 70.

  At the upper end portion of the side wall portion 23 of the hollow structure 10, the skin layer 30 is joined via an adhesive layer made of a resin having a melting point lower than that of the thermoplastic resin constituting the skin layer 30. The heating temperature in the second bonding step is set to be several degrees higher than the melting point of the modified polyolefin adhesive (modified resin) constituting the adhesive layer. Therefore, when the skin layer 30 is joined to the rear edge 23a formed on the side wall 23, the low melting point adhesive layer is in a molten state. As shown in FIGS. 6A and 6B, the rear edge 23a after the skin layer 30 is joined by the second joining step has its upper edge penetrated into the adhesive layer 30a of the skin layer 30. It will be joined in the state. In this case, as shown in FIG. 6A, an adhesive layer 30a is interposed between the removal rear edge 23a and the skin layer 30, or as shown in FIG. 6B, the removal rear edge 23a. The adhesive layer 30 a is hardly interposed between the skin layer 30 and the skin layer 30. The skin layer 30 and the post-removal end edge 23a are firmly bonded to each other by joining the rear end edge 23a so as to enter the adhesive layer 30a. Among these states, the bonding strength in the state of FIG. 6A is stronger than that in the state of FIG. 6B. The bonding state between the removal rear edge 23a and the adhesive layer 30a is such that all the removal rear edge 23a is in the state shown in FIG. 6A, or all the removal rear edge 23a is in FIG. In addition to the state shown in b), the removal rear edge 23a in the state shown in FIG. 6A and the removal rear edge 23a in the state shown in FIG. It may be. As described above, the side edge 23 and the skin layer 30 of the core layer 20 are easily deformed even when the rear edge 23 a is firmly bonded by the adhesive layer 30 a of the skin layer 30. In FIGS. 6A and 6B, the adhesive layer 30a is thicker than the skin layer 30 in order to clearly show the joined state of the removed rear edge 23a.

  The hollow structure 10 is manufactured through a first intermediate body 70 in which the skin layer 40 and the pre-removal skin layer 60 are bonded to both surfaces of the core layer 50 before removal formed by folding and forming one sheet material 100. In the core layer 50 before removal formed by folding and forming one sheet material 100, the upper wall portion 21 and the side wall portion 23 are continuous, and the lower wall portion 22 and the side wall portion 23 are continuous. Therefore, in the second intermediate body 80 from which the upper end portion of the first intermediate body 70 is removed, that is, the core layer 20 from which the upper end portion of the core layer 50 before removal is removed, the strength of the lower wall portion 22 and the side wall portion 23 is maintained. ing. Therefore, the hollow structure 10 formed by bonding the skin layer 30 to the first intermediate body 70 has not only excellent impact resistance but also excellent strength.

  In this regard, for example, when the first intermediate body 70 is formed without passing through the folding step, the first joining step, and the removing step, sufficient strength as a hollow structure cannot be obtained. For example, when the layer corresponding to the lower wall portion 22 and the skin layer 40 are bonded to the lower surface of the honeycomb core structure 200 as shown in FIG. 10A, and the skin layer 30 is bonded to the upper surface, the lower wall portion 22 The bonding strength between the layer corresponding to the above and the skin layer 40 becomes weak, and sufficient strength cannot be obtained. Further, in the honeycomb core structure 200 as shown in FIG. 10A, a portion corresponding to the side wall portion 23 is formed by joining and integrating the bottom side portion 201 and the top side portion 202 via the adhesive layer 204. Therefore, the shift between the bottom part 201 and the top part 202 is not allowed, and the impact resistance is lowered.

  Since the hollow structure 10 of the present embodiment is formed through the first joining step, the removing step, and the second joining step from the pre-removal core layer 50 obtained by folding and forming one sheet material 100, the impact resistance is improved. Excellent and strength.

According to this embodiment, the following effects can be obtained.
(1) In the hollow structure 10 of the present embodiment, the removal rear edge 23a is formed on the side wall portion 23 of the core layer 20, and the removal rear edge 23a and the skin layer 30 are joined in a linear shape. Therefore, when an impact is applied from the upper surface side of the hollow structure 10, the side wall portion 23 of the core layer 20 and the skin layer 30 are compared with the case where the skin layer 30 is joined to the upper wall portion 21 of the core layer 20 in a planar shape. The skin layer 30 is easily deformed. As a result, the impact is easily dispersed, and the occurrence of cracks or the like on the surface of the hollow structure 10 is suppressed. A hollow structure 10 having excellent impact resistance is obtained.

  (2) The hollow structure 10 according to the present embodiment has a two-layer structure in which a part of the side wall portion 23 of the core layer 20 includes a first side wall portion 23b and a second side wall portion 23c. The two side wall portions 23c have non-joining portions 23d that are not thermally welded to each other. Therefore, when an impact is applied from the upper surface side of the hollow structure 10, the side wall portion 23 having a two-layer structure is likely to be displaced. This displacement also dissipates the force applied to the upper surface of the hollow structure 10 and absorbs the impact. A hollow structure 10 having excellent impact resistance is obtained.

  (3) The hollow structure 10 of the present embodiment is manufactured through the first intermediate body 70 and the second intermediate body 80. The first intermediate 70 is obtained by joining the skin layer 40 and the pre-removal skin layer 60 to the pre-removal core layer 50 obtained by folding and forming one sheet material 100, and the second intermediate 80 is It is obtained by removing the upper end portion of the first intermediate body 70. Therefore, in the core layer 50 before removal of the first intermediate body 70, the lower wall portion 22 and the side wall portion 23 are formed in a continuous shape. Compared with the honeycomb core structure formed by joining the lower wall portion 22 to the side wall portion 23, the strength is excellent. By manufacturing the hollow structure 10 through the first intermediate body 70 and the second intermediate body 80, the hollow structure body 10 having excellent strength can be obtained.

  (4) In the first bonding step and the second bonding step, the heating temperature and the heating time are not increased until the core layer 50 before removal, the skin layer 40 and the skin layer 60 before removal are softened and melted, and the adhesive layer. It is managed so that only softening and melting can be performed. Therefore, the core layer 50 before removal and the skin layers 40 and 40 are firmly bonded, and the core layer 20 and the skin layer 30 are firmly bonded. In the side wall portion 23 having a double structure that partitions S, a portion that is not joined to a part of the side wall portion 23 can be held. A hollow structure 10 having excellent impact resistance is obtained.

  (5) In the removal step, for example, the thin plate-shaped cutting jig T provided with a saw blade at the tip is moved in a direction perpendicular to the thickness direction of the core layer 50 before removal, and before removal in the first intermediate body 70. The upper end portion of the core layer 50 is cut. Therefore, in the core layer 20, the height of the upper end edge of the side wall part 23, that is, the removal rear end edge 23a is substantially the same. The rear edge 23a after removal of the core layer 20 and the skin layer 30 can be suitably joined.

  (6) In the removing step, the cutting jig T is moved to a boundary portion between the curved portion 23e and the side wall portion 23 formed between the side wall portion 23 and the upper wall portion 21, and the upper end portion of the side wall portion 23 is removed. ing. Therefore, the removal rear edge 23a is linear, and the first side wall part 23b and the second side wall part 23c having a two-layer structure are easily deformed. A hollow structure 10 having excellent strength is obtained.

  (7) The adhesive layer that adheres the core layer 20 and the skin layers 30 and 40 is composed of a modified polyolefin adhesive (modified resin) such as modified polyethylene or modified polypropylene in which a functional group is introduced into the polyolefin to impart adhesion. Has been. Therefore, the peel strength between the core layer 20 and the skin layers 30 and 40 is improved, and the hollow structure 10 having excellent strength can be obtained.

(8) On the lower surface side of the hollow structure 10, the cell S of the core layer 20 is closed by the lower wall portion 22 of the one-layer structure or the lower wall portion 22 of the two-layer structure. Therefore, the adhesion area between the core layer 20 and the skin layer 40 is wide, and the peel strength is excellent.
(Second Embodiment)
The hollow structure 11 of 2nd Embodiment is demonstrated with reference to FIGS. Here, it demonstrates centering on a different part from 1st Embodiment.

  The hollow structure 10 according to the first embodiment has been described as having a flat top surface. As shown in FIG. 7A, the hollow structure 11 of the second embodiment has a recess 12 formed in a part of the upper surface thereof, and the recess 12 is compared with other parts in the hollow structure 11. The thin part is formed with a small thickness. The recess 12 is recessed in a substantially rectangular parallelepiped shape from the upper surface side of the hollow structure 11, and is surrounded by a substantially rectangular bottom surface 12a and four side surfaces 12b.

  As shown in FIG. 7B, the hollow structure 11 of the present embodiment includes a core layer 90 in which a plurality of cells S are arranged in parallel, a skin layer 30 joined to the upper surface 90a of the core layer 90, and The plate-like member includes the skin layer 60 before removal and the skin layer 40 bonded to the lower surface 90 b of the core layer 90. The skin layer 30 and the pre-removal skin layer 60 are joined to the upper surface 90a of the core layer 90 via an adhesive layer (not shown), and the skin layer 40 is joined to the lower surface 90b of the core layer 90 via an adhesive layer (not shown). ing. The skin layer 30 is joined to the upper surface 90a of the core layer 90 to form portions corresponding to the bottom surface 12a and the four side surfaces 12b of the recess 12 of the hollow structure 11, and the skin layer 60 before removal is other than the recess 12 The upper surface 90a of the core layer 90 is joined. The material of the core layer 90, the skin layers 30 and 40, the skin layer 60 before removal, and the material of the adhesive layer are the same as in the first embodiment.

The structure of the hollow structure 11 will be described together with the method for manufacturing the hollow structure 11 shown in FIGS. 8 (a) to 8 (c).
The manufacturing method of the hollow structure 11 is basically the same as that of the hollow structure 10 of the first embodiment. In particular, in the manufacturing method of the hollow structure 11, the molding process, the folding process, and the first joining process are the same as the hollow structure 10 of the first embodiment. Further, a description will be given of the removal process and the subsequent steps for removing the portion corresponding to the recess 12 from the first intermediate body 70.

  As shown in FIG. 8A and FIG. 8B, in the removing step, the portion corresponding to the recess 12 of the hollow structure 11 in the first intermediate body 70 is removed by the cutting jig T. The cutting jig T may be the same as that of the first embodiment, or may be a drill-shaped one that facilitates removal of the recesses, for example. The cutting jig T can be heated and used as necessary.

  As shown in FIG. 8B, the removal step removes a part of the upper wall portion 21 of the core layer 50 before removal and a part of the upper end portion of the side wall portion 23 in the first intermediate body 70 to remove the core layer 90. And the pre-removal skin layer 60 joined to the removed upper wall portion 21 is removed. Thereby, the 2nd intermediate body 81 in which the recessed part 81a was formed in the upper surface side is obtained. The second intermediate 81 includes a core layer 90 with the upper wall portion 21 remaining on the upper surface side, a pre-removal skin layer 60 bonded to the remaining upper wall portion 21, and a skin layer 40 bonded to the lower surface side. ing.

  In the concave portion 81a of the second intermediate body 81, a removal rear edge 23a is formed in a portion where the upper end portion of the side wall portion 23 is removed. The bottom surface of the recess 81a is constituted by a rear edge 23a, and the side wall of the recess 81a is exposed to the edge of the upper wall 21 and the edge of the skin layer 60 before removal. All the positions in the height direction of the removal rear edge 23a formed on the core layer 90 are formed at substantially the same position.

  As shown in FIG. 8C, in the second bonding step, the skin layer 30 is bonded to the recess 81a formed in the second intermediate 81. In the second bonding step of the second embodiment, it is preferable that the heating temperature and the heating time are set slightly higher and longer than those in the first bonding step. Thereby, the adhesive layer formed on one surface of the skin layer 30 is thermally melted, and the skin layer 30 is thermally welded to the recess 81a via the adhesive layer, and the skin layer 30 and the pre-removal skin layer 60 The joints are melted and integrated. As a result, the hollow structure 11 in which the skin layer 30 and the pre-removal skin layer 60 are bonded to the upper surface 90 a of the core layer 90 and the skin layer 40 is bonded to the lower surface 90 b of the core layer 90 is obtained. On the upper surface side of the hollow structure 11, the skin layer 30 covering the recess 12 and the pre-removal skin layer 60 covering a portion other than the recess 12 are continuously and integrally joined.

Next, the operation of the hollow structure 11 will be described except for the same operation as the hollow structure 10.
As shown in FIG. 9A, the hollow structure 11 has a thin portion having a small thickness due to the formation of the recess 12. And in the part corresponding to the recessed part 12 of the hollow structure 11 in the core layer 90, the side wall part 23 cut | disconnected by the removal process is formed. Therefore, although the height of the side wall 23 in the recess 12 is lower than the side wall 23 in the other part than the recess 12, the side wall 23 extends along the thickness direction of the hollow structure 11 like the other parts other than the recess 12. It extends. That is, in the hollow structure 11 of the present embodiment, since the recess 12 is formed in such a manner that a part of the core layer 50 before removal is removed, the core layer 90 is in a state in which the shape of the side wall portion 23 is maintained as it is. Has been.

  On the other hand, as a method of forming the concave portion 12 in the hollow structure 11, after forming the first intermediate body 70 in which the skin layer 40 and the pre-removal skin layer 60 are joined on both surfaces of the pre-removal core layer 50, a part is heated by a heating jig. A method of thermal compression is conceivable. In this case, as shown in FIG. 9B, in the recess 12, the side wall 23 of the core layer 90 is compressed and falls in an oblique direction, or the side wall 23 is compressed as shown in FIG. 9C. Or buckle. For example, when the side wall part 23 falls down, it is possible that the intensity | strength of the hollow structure 11 falls compared with the case where it extends in the thickness direction. Further, it is conceivable that a force to stand up acts on the collapsed side wall portion 23 and the bottom surface 12a of the recess 12 is deformed so as to bulge upward.

  On the other hand, in the hollow structure 11 of the present embodiment, the shape of the side wall portion 23 is maintained in the same shape in the portion other than the concave portion 12 and the concave portion 12, so that the strength is suppressed from being reduced. Deformation in the recess 12 is suppressed.

According to this embodiment, in addition to the above (1) to (8), the following effects can be obtained.
(9) The hollow structure 11 of the present embodiment is partially formed with a recess 12. The recess 12 is formed by bonding the skin layer 30 to a part from which the first intermediate body 70 has been removed in the removing step. Therefore, in the recessed part 12, the side wall part 23 of the core layer 90 extends so as to follow the thickness direction of the hollow structure 11. Since the shape of the side wall portion 23 and the other portions other than the concave portion 12 does not change, the concave portion 12 is prevented from being deformed or the strength is reduced.

  (10) The concave portion 12 of the hollow structure 11 of the present embodiment is formed by removing a part of the first intermediate body 70. Therefore, by adjusting a portion to be removed from the side wall portion 23 of the core layer 50 before removal, the concave portions 12 having different thicknesses can be easily formed. The shape of the hollow structure 11 can be changed as appropriate. A hollow structure 11 having excellent versatility can be obtained.

Each said embodiment can be changed as follows. In addition, the said embodiment and the following modified examples can be applied in combination with each other within a technically consistent range.
-The core layer 50 before removal is not restricted to what is manufactured by the folding process like this embodiment. As long as a plurality of cells are formed by folding one sheet material, the folding mode is not particularly limited. For example, as described in Japanese Patent No. 4368399, the core layer 50 before removal as a honeycomb structure is formed by sequentially folding a three-dimensional structure having a plurality of rows of trapezoidal cross-sections. May be.

  The pre-removal core layer 50 is not formed through the folding step, but may be formed by expanding a plastic sheet material. For example, the core layer 50 before removal may be formed by vacuum forming a sheet material having plasticity and having a shape in which a plurality of cells having a polygonal column shape or a cylindrical shape are expanded. Or you may use as the core layer 50 before removal what formed the bulging area | region and the plane area | region alternately by bending one sheet | seat. In these cases, it is only necessary that the side wall portion 23 of the core layer 50 before removal has a two-layer structure having a non-joined portion. In the first joining step, the pre-removal skin layer 60 is joined to the upper surface of the bulging region, and the skin layer 40 is joined to the lower surface of the planar region. From the obtained first intermediate 70, the removing step, the second joining step. Through these steps, the hollow structures 10 and 11 can be obtained.

  In the above embodiment, the hexagonal columnar cells S are defined in the core layers 20 and 90 (core layer 50 before removal), but the shape of the cells S is not particularly limited. It is good also as polygonal shapes, such as a quadratic prism shape and an octagonal prism shape, and cylinder shape. At that time, cells S having different shapes may be mixed. Further, the cells S may not be adjacent to each other, and a gap (space) may exist between the cells S.

  In the above embodiment, the first intermediate body 70 has the pre-removal skin layer 60 bonded to one surface of the pre-removable core layer 50 and the skin layer 40 bonded to the other surface. It does not need to be joined. When the pre-removal skin layer 60 is not joined, when the hollow structure 10 of the first embodiment is manufactured, in the removal step, the upper wall portion 21 and the upper end portion of the side wall portion 23 of the core layer 50 before removal are removed. become. Moreover, when manufacturing the hollow structure 11 of the second embodiment, in the removing step, a part of the upper wall portion 21 of the core layer 50 before removal and the one sentence upper end portion of the side wall portion 23 are removed, and the obtained second intermediate The skin layer 30 is bonded to the entire upper surface of the body 80. In addition, when the skin layer 40 is not joined to both the hollow structure 10 and the hollow structure 11, the lower surfaces of the hollow structure 10 and the hollow structure 11 are constituted by the lower wall portion 22 of the core layer 20 or the core layer 90.

  In the above embodiment, the skin layers 30 and 40 and the pre-removal skin layer 60 are configured as a single layer structure, but may be configured as a laminate of two or more layers. In this case, the thermoplastic resin may be different in each of two or more layers. For example, at least one of the skin layers 30 and 40 and the pre-removal skin layer 60 may have a three-layer structure. In this case, the hardness of the intermediate layer is relatively high and the hardness of the pair of surface layers sandwiching the intermediate layer is relatively low. By doing so, it becomes possible to adjust the impact resistance of the hollow structures 10 and 11. That is, the relatively soft surface layer can absorb the impact, and the relatively hard intermediate layer can provide rigidity for receiving the impact as a surface.

  When the skin layers 30 and 40 and the pre-removal skin layer 60 are configured as a laminate of two or more layers, the layer structures may be different. Further, only the skin layer 30 and the pre-removal skin layer 60 may have a single layer structure, or only the skin layer 40 may have a single layer structure. In the case of the hollow structure 11 of the second embodiment, the skin layer 30 and the pre-removal skin layer 60 preferably have the same layer configuration.

The thickness of at least one of the skin layer 30, the skin layer 40, and the pre-removal skin layer 60 may be varied.
-The hollow structures 10 and 11 may be affixed with other sheets made of different materials from the skin layers 30 and 40 and the pre-removal skin layer 60. For example, a metal sheet, a fiber reinforced resin sheet, or the like may be attached to the surface of the skin layers 30 and 40 and the skin layer 60 before removal, or may be attached between the core layers 20 and 90.

  -As the thermoplastic resin which comprises the core layer 20.90, the skin layers 30 and 40, and the skin layer 60 before removal, what added various functional resins may be used. For example, it is possible to increase flame retardancy by adding a flame retardant resin to a thermoplastic resin. It is also possible to use the core layer 20.90, the skin layers 30, 40, and the skin layer 60 before removal to which various functional resins are added, and the core layer 20.90, the skin layer. It can also be used for at least one of 30, 40 and the pre-removal skin layer 60.

  The skin layers 30 and 40 and the pre-removal skin layer 60 are bonded to the core layers 20 and 90 via the adhesive layer, but may not be bonded via the adhesive layer. The thermoplastic resin constituting the skin layers 30 and 40 and the pre-removal skin layer 60 and the core layers 20 and 90 are thermally melted by appropriately adjusting the heating temperature and heating time in the first bonding step and the second bonding step. Each may be heat-welded. Moreover, you may mutually join with the adhesive.

  In the removing step, the side wall portion 23 was cut at a boundary portion between the curved portion 23e formed between the side wall portion 23 and the upper wall portion 21 and the side wall portion 23. However, the present invention is not limited to this, and cutting may be performed with the curved portion 23e remaining on the rear edge 23a side.

  -Although the skin layer 60 before removal and the upper wall part 21 are removed and the skin layer 30 is joined to the upper surface 20a of the core layer 20, the hollow structure 10 of 1st Embodiment is not limited to this. The skin layer 60 before removal is joined to the lower surface 50b side of the core layer 50 before removal, the skin layer 60 before removal and the lower wall portion 22 are removed, and the skin layer 40 is joined to the lower surface 20b of the core layer 20. Also good. Further, the pre-removal skin layer 60 is joined to the upper surface 50a and the lower surface 50b of the pre-removal core layer 50, and the pre-removal skin layer 60 and the upper wall portion 21, and the pre-removal skin layer 60 and the lower wall portion 22 are removed. The skin layers 30 and 40 may be bonded to the upper surface 20 a and the lower surface 20 b of the core layer 20.

  -The hollow structure 10 of 1st Embodiment is the direction orthogonal to the thickness direction of the core layer 50 before removal toward the upper end part of the side wall part 23, ie, the core layer 50 before removal in the removal process. It moved so that it might become parallel with respect to the upper surface 50a and the lower surface 50b. Therefore, all the positions in the height direction of the removal rear edge 23a are formed at substantially the same position. For example, the cutting jig T may be moved in a direction inclined with respect to the upper surface 50a and the lower surface 50b of the core layer 50 before removal. In this case, the upper end edge of the removal rear edge 23a is formed to be inclined in one direction. That is, the removal rear edge 23 a is formed so that its height linearly changes in a direction perpendicular to the thickness direction of the hollow structure 10. The skin layer 30 may be joined to the edge 23a after the removal so that the hollow structure 10 in which the skin layer 30 is inclined with respect to the skin layer 40 may be formed. Or you may move the cutting jig T so that a curved surface may be formed with respect to the upper surface 50a and the lower surface 50b of the core layer 50 before removal. In this case, the entire shape of the upper end edge of the removal rear edge 23a is curved upward or downward. That is, the removal rear edge 23 a is formed so that its height changes in a curve in a direction perpendicular to the thickness direction of the hollow structure 10. When the skin layer 30 is bonded to the post-removal end edge 23a, the hollow structure 10 whose upper surface is gently curved is obtained.

Similarly, the hollow structure 11 of the second embodiment may be formed so that the upper surface of the recess 12 is inclined or curved with respect to the lower surface.
-Although the hollow part 11 of 2nd Embodiment formed the one recessed part 12 in the upper surface side, it is not limited to this. A plurality of recesses 12 may be formed on the upper surface side, one or more recesses 12 may be formed on the lower surface side, and one or more recesses 12 may be formed on both surfaces. When forming the plurality of recesses 12, the depth, shape, size, etc. of each recess 12 may be the same or different.

  As the hollow structure, one surface may be configured as the skin layer 30 of the hollow structure 11 and the skin layer 60 before removal, and the other surface may be configured as the skin layer 30 of the hollow structure 10. That is, as the second intermediate body 80, one or more recesses are formed on one surface, and the other surface has the skin layer 60 or the skin layer 40 before removal and the upper wall portion 21 or the core layer 50 before removal. The entire lower wall portion 22 may be removed.

  In each of the above embodiments, the thickness of the sheet material 100 that forms the core layers 20 and 90 and the core layer 50 before removal is thinner than the thickness of the skin layers 30 and 40 and the skin layer 60 before removal. It is not limited to this. The thickness of the sheet material 100 may be the same as the thickness of the skin layers 30 and 40 and the skin layer 60 before removal, and the thickness of the sheet material 100 may be the thickness of the skin layers 30 and 40 and the skin layer 60 before removal. It may be made thicker.

DESCRIPTION OF SYMBOLS 10, 11 ... Hollow structure, 20, 90 ... Core layer, 21 ... Upper wall part, 22 ... Lower wall part, 23 ... Side wall part, 23a ... Rear edge of removal, 23b ... 1st side wall part, 23c ... 1st 2 side wall part, 23d ... non-joining part, 30, 40 ... skin layer, 50 ... core layer before removal, 60 ... skin layer before removal, 100 ... sheet material, S ... cell, S1 ... first cell, S2 ... second cell.

Claims (7)

A resin hollow structure comprising a core layer in which a plurality of cells are arranged inside, and a pair of skin layers bonded to both surfaces of the core layer,
The core layer includes a side wall portion standing in the thickness direction to partition the cell, an upper wall portion provided at an upper end edge of the side wall portion, and a lower wall portion provided at a lower end edge of the side wall portion. As prepared, one sheet having plasticity is molded from a sheet material molded into a predetermined shape,
In the core layer, at least one of the upper wall portion and the lower wall portion is removed, and the side wall portion is not provided with at least one of the upper wall portion and the lower wall portion. An edge is formed,
The skin layer joined to the side of the core layer from which at least one of the upper wall portion and the lower wall portion has been removed is joined to the removed rear edge of the side wall portion,
The side wall portion has a two-layer structure including a first side wall portion and a second side wall portion,
The hollow structure in which the said side wall part is provided with the non-joining part to which the said 1st side wall part and the said 2nd side wall part are not joined. In the core layer, at least one part of the upper wall portion and the lower wall portion is removed to form a thin portion having a relatively thin thickness,
The hollow structure according to claim 1, wherein the removal rear edge is formed in the thin portion.   The hollow structure according to claim 1 or 2, wherein the skin layer is bonded to the core layer by heat welding or adhesion. A method for producing a resin-made hollow structure in which a skin layer is bonded to at least one surface of a hollow plate-shaped core layer in which a plurality of cells are arranged in parallel,
A molding step of molding a sheet material in which plane regions and bulging regions bulging upward in a polygonal cross section are alternately arranged from a single sheet having plasticity;
By folding the sheet material, the upper surfaces of the adjacent bulging regions are brought into contact with each other, and a side wall portion defining the plurality of cylindrical cells, and a pair of walls provided at both end edges of the side wall portion A folding step of forming a pre-removal core layer comprising a portion;
A removing step of removing at least one of the wall portions of the core layer before removal to expose a rear edge of removal formed on the side wall portion of the core layer;
The manufacturing method of a hollow structure provided with the joining process of joining the said skin layer to the said post-removal edge.   In the removing step, a part of the wall part of at least one of the core layers before removal is removed to form a thin part having a relatively small thickness in a part of the core layer. The manufacturing method of the hollow structure of Claim 4 which exposes the removal rear edge formed in the said side wall part. A method for producing a resin-made hollow structure in which a skin layer is bonded to at least one surface of a hollow plate-shaped core layer in which a plurality of cells are arranged in parallel,
A molding step of molding a sheet material in which plane regions and bulging regions bulging upward in a polygonal cross section are alternately arranged from a single sheet having plasticity;
By folding the sheet material, the upper surfaces of the adjacent bulging regions are brought into contact with each other, and a side wall portion defining the plurality of cylindrical cells, and a pair of walls provided at both end edges of the side wall portion A folding step of forming a pre-removal core layer comprising a portion;
A first joining step of joining the pre-removal skin layer to at least one surface of the wall of the pre-removal core layer to form an intermediate;
A removal step of removing the skin layer before the removal of the intermediate body and the wall portion to which the skin layer before removal of the intermediate body is bonded, and exposing a removal rear edge formed on the side wall portion of the core layer;
A manufacturing method of a hollow structure provided with the 2nd joining process of joining the skin layer to the edge after the removal. In the removing step, a part of the pre-removed skin layer of the intermediate body and a part of the wall portion to which a part of the pre-removed skin layer are joined are relatively The method for manufacturing a hollow structure according to claim 6, wherein a thin-walled portion having a small thickness is formed and a rear edge of removal formed on the side wall portion at the thin-walled portion is exposed.