JP7074328B2 - Manufacturing method of hollow structure - Google Patents

Description

The present invention relates to a method for manufacturing a hollow structure .

Since the hollow structure is lightweight and has appropriate strength, it may be used as a component of various vehicles, a building material, or the like. Patent Document 1 describes an invention relating to a honeycomb structure of a hollow structure.

Japanese Patent No. 4408331

The honeycomb structure described in Patent Document 1 is formed by plastically deforming a synthetic resin sheet to form a sheet material having an uneven shape, and folding the sheet material. In the honeycomb structure formed by folding, a part of the side wall that divides the plurality of cells has a two-layer structure, and the closed wall that closes the upper part and the lower part of the plurality of cells also has a two-layer structure. In Patent Document 1, in order to maintain the shape of the folded sheet material and increase the strength of the honeycomb structure, the flat tool during the folding process is heated to heat-weld the closed walls forming the two-layer structure to each other. ing.

By the way, in the honeycomb structure formed in a plate shape, since a plurality of hollow cells are arranged side by side in the direction orthogonal to the thickness direction, sufficient strength may not be maintained against bending applied in the thickness direction. be. In particular, in a honeycomb structure having a side wall portion of a two-layer structure as described in Patent Document 1, breakage may occur starting from the side wall portion of the two-layer structure, and there is still room for improvement in terms of bending strength. There is.

The present invention has been made to solve these conventional problems, and an object of the present invention is to provide a hollow structure having excellent bending strength.

In order to solve the above problems, in the present invention, a sheet material formed from a single synthetic resin sheet so as to have a predetermined uneven shape is folded and molded, and a plurality of cells are arranged side by side inside. A part of the side wall portion which is a hollow structure and is erected in the thickness direction to partition the cell has a two-layer structure including a first side wall portion and a second side wall portion, and the first side wall portion. The second side wall portion and the second side wall portion are joined to each other via a joint portion formed in an intermediate portion in the thickness direction, and the joint portion is formed by adhesion or welding.

According to the above configuration, the side wall portions of the two-layer structure for partitioning the cells are joined at the intermediate portion in the thickness direction of the hollow structure. Therefore, even when a bending force is applied in the thickness direction, bending starting from the side wall portion of the two-layer structure is unlikely to occur. A hollow structure having excellent bending strength can be obtained. The middle portion in the thickness direction means a portion excluding both end edges in the thickness direction.

In order to solve the above problems, the present invention is a hollow structure which is erected in the thickness direction and in which a plurality of cells are partitioned by a side wall portion of a two-layer structure including a first side wall portion and a second side wall portion. A molding step of molding a sheet material having a predetermined uneven shape from one sheet made of synthetic resin, a joint portion forming step of forming a joint portion on the sheet material, and the sheet material. In the folding step, the first side wall portion and the second side wall portion are joined to each other via the joint portion at an intermediate portion in the thickness direction.

According to the above configuration, when the sheet material is folded in the folding step, the first side wall portion and the intermediate portion of the second side wall portion are joined via the joint portion formed on the sheet material. Therefore, the strength at the side wall portion of the two-layer structure is improved, and a hollow structure having excellent bending strength can be manufactured.

In the above configuration, in the joint portion forming step, it is preferable to apply an adhesive to the sheet material to form the joint portion.
In the above configuration, in the molding step, the sheet material may be molded from a sheet made of a thermoplastic resin, and in the joint portion forming step, a part of the sheet material may be heated and melted to form the joint portion. preferable.

In order to solve the above problems, the present invention is a hollow structure which is erected in the thickness direction and in which a plurality of cells are partitioned by a side wall portion of a two-layer structure including a first side wall portion and a second side wall portion. The first side wall portion and the second side wall portion are formed by a molding step of molding a sheet material having a predetermined uneven shape from one sheet made of synthetic resin and folding the sheet material. In the folding step of forming an intermediate having a side wall portion of the two-layer structure to which the portions are abutted, and in the side wall portion of the two-layer structure of the intermediate body, the thickness direction of the first side wall portion and the second side wall portion. It is provided with a joining process for joining the intermediate portion of the above.

According to the above configuration, when the sheet material is folded in the folding step, the first side wall portion and the second side wall portion of the two-layer structure are brought into contact with each other. Further, in the joining step following the folding step, the intermediate portions of the first side wall portion and the second side wall portion are joined to each other by heating the side wall portion of the two-layer structure with a heating jig. Therefore, the strength at the side wall portion of the two-layer structure is improved, and a hollow structure having excellent bending strength can be manufactured.

In the above configuration, in the joining step, it is preferable to heat the side wall portion of the two-layer structure in a state of being sandwiched between heating jigs.
In the above configuration, in the bonding step, it is preferable to bond the side wall portion of the two-layer structure by at least one of ultrasonic bonding, vibration bonding, and high frequency bonding.

According to the present invention, a hollow structure having excellent bending strength can be obtained.

(A) is a perspective view of the hollow structure of the present embodiment, (b) is a β-β line sectional view of (a), and (c) is a γ-γ line sectional view of (a). (A) is a perspective view of the sheet material, (b) is a perspective view showing a state in which the sheet material is being folded, and (c) is a perspective view showing a state in which the sheet material is folded. The schematic diagram which shows an example of a manufacturing apparatus. The figure explaining the joint part. The schematic diagram which shows an example of a manufacturing apparatus. (A) is a perspective view of the sheet material constituting the core layer of the modified example, (b) is a perspective view showing a state in which the sheet material is being folded, and (c) is a perspective view showing a state in which the sheet material is folded. .. FIGS. (A) to (f) are diagrams for explaining an example of changing the joint portion.

Hereinafter, an embodiment embodying the present invention will be described. First, the structure of the hollow structure 10 of the present embodiment will be described with reference to FIG.
As shown in FIG. 1A, the hollow structure 10 of the present embodiment includes a core layer 20 in which a plurality of cells S are arranged side by side, and a skin layer 30 joined to the upper surface 20a of the core layer 20. A skin layer 40 joined to the lower surface 20b of the core layer 20 is provided.

The core layer 20 and the skin layers 30 and 40 are made of a conventionally known thermoplastic resin. Examples of the thermoplastic resin constituting the core layer 20 and the skin layers 30 and 40 include polypropylene resin, polyamide resin, polyethylene resin, acrylonitrile-butadiene-styrene copolymer resin, acrylic resin, polybutylene terephthalate resin and the like. .. The core layer 20 and the skin layers 30 and 40 are preferably made of the same material as a thermoplastic resin, and are made of polypropylene resin in this embodiment.

As shown in FIGS. 1 (b) and 1 (c), the core layer 20 is formed by folding a single sheet material obtained by molding a polypropylene resin sheet into a predetermined shape. The core layer 20 is composed of an upper wall portion 21, a lower wall portion 22, and a side wall portion 23 that is erected between the upper wall portion 21 and the lower wall portion 22 and forms a hexagonal cylindrical wall portion. .. A hexagonal columnar cell S is partitioned inside the core layer 20 by the upper wall portion 21, the lower wall portion 22, and the side wall portion 23.

In the cell S partitioned inside the core layer 20, there are a first cell S1 and a second cell S2 having different configurations. As shown in FIG. 1 (b), the upper end of the first cell S1 is blocked by the upper wall portion 21, and the lower end thereof is opened downward without being blocked. That is, in the first cell S1, the upper surface 20a of the core layer 20 is composed of the upper wall portion 21, and the lower surface 20b is composed of the lower end edge of the side wall portion 23.

On the other hand, as shown in FIG. 1 (c), the lower end of the second cell S2 is closed by the lower wall portion 22, and the upper end thereof is opened upward without being blocked. That is, in the second cell S2, the lower surface 20b of the core layer 20 is composed of the lower wall portion 22, and the upper surface 20a is composed of the upper end edge of the side wall portion 23.

As shown in FIG. 1A, the first cell S1 and the second cell S2 are arranged so that the first cells S1 and the second cells S2 are adjacent to each other in the X direction to form a row. Further, in the Y direction orthogonal to the X direction, the columns of the first cell S1 and the columns of the second cell S2 are arranged alternately.

As shown in FIGS. 1B and 1C, the space between the adjacent first cells S1 and the space between the adjacent second cells S2 are relative to the upper wall portion 21 and the lower wall portion 22. It is formed vertically and is partitioned by a side wall portion 23 having a two-layer structure including a first side wall portion 23a and a second side wall portion 23b. On the other hand, the adjacent first cell S1 and second cell S2 are partitioned by a side wall portion 23 having a one-layer structure formed perpendicular to the upper wall portion 21 and the lower wall portion 22.

As shown in FIGS. 1 (b) and 1 (c), the first side wall portion 23a and the second side wall portion 23b are heat-welded to each other at the upper end edge and the lower end edge thereof. Further, the first side wall portion 23a and the second side wall portion 23b are joined to each other via the joining portion 23c at the intermediate portion in the vertical direction.

The joint portion 23c of the present embodiment is composed of an adhesive layer, and the entire surface of the first side wall portion 23a and the entire surface of the second side wall portion 23b are bonded (bonded) via the joint portion 23c (adhesive layer). .. Therefore, the upper end edge and the lower end edge of the first side wall portion 23a and the second side wall portion 23b are joined via the joining portion 23c, and the portion where the thermoplastic resin is heat-melted and heat-welded coexists. There is.

The material of the adhesive constituting the adhesive layer is conventionally known and is not particularly limited. In the hollow structure 10 of the present embodiment in which the core layer 20 and the skin layers 30 and 40 are made of polypropylene resin, the hot melt adhesive is made of a resin compatible with polypropylene resin. Examples of other hot-melt adhesives include those composed of ethylene-vinyl acetate copolymer (EVA) resin, polyester resin, polyamide resin and the like. The adhesive is a melted adhesive that is cured by heat, light, a chemical reaction, humidity, or the like, and the adherends are fixed to each other by being cured.

The skin layers 30 and 40 are joined to the upper surface of the upper wall portion 21 of the core layer 20 and the lower surface of the lower wall portion 22, respectively. Specifically, the skin layer 30 is joined to the upper end of the upper wall portion 21 of the first cell S1 and the side wall portion 23 of the second cell S2 on the upper surface 20a of the core layer 20. Further, the skin layer 40 is joined to the lower end of the side wall portion 23 of the first cell S1 and the lower wall portion 22 of the second cell S2 on the lower surface 20b of the core layer 20. Therefore, the upper surface of the hollow structure 10 has a two-layer structure including an upper wall portion 21 of the core layer 20 and a skin layer 30 in the first cell S1, and a one-layer structure of only the skin layer 30 in the second cell S2. It is said that. Further, the lower surface of the hollow structure 10 has a one-layer structure consisting of only the skin layer 40 in the first cell S1, and a two-layer structure composed of the lower wall portion 22 of the core layer 20 and the skin layer 40 in the second cell S2. It is said that.

Next, a method for manufacturing the hollow structure 10 of the present embodiment will be described with reference to FIGS. 2 and 3.
The method for manufacturing the hollow structure 10 includes a molding step, a joining portion forming step, a folding step, a joining step, and a skin layer joining step. The molding step is a step of molding the sheet material 100 from the sheet made of thermoplastic resin. The joint portion forming step is a step of applying an adhesive to the sheet material 100 to form a joint portion 23c (adhesive layer). The folding step is a step of forming the core layer 20 by folding the sheet material 100. The joining step is a step of joining the first side wall portion 23a and the second side wall portion 23b of the two-layer structure via the joining portion 23c. The skin layer joining step is a step of joining the skin layers 30 and 40 to both the upper and lower surfaces of the core layer 20 to form the hollow structure 10. Each step for manufacturing these hollow structures 10 is performed in a series of steps by the apparatus T shown in FIG.

First, the apparatus shown in FIG. 3 will be described. FIG. 3 shows the device T as a schematic diagram, in which the left side is the upstream side and the right side is the downstream side. In the device T, in order from the upstream side, a sheet roll 61 around which a sheet made of a thermoplastic resin is wound, a vacuum forming drum 62 for a forming process, a transfer roll 63 for a joining portion forming process, and a folding process. First conveyor 64 for the skin layer joining process, second conveyor 65 for the joining process, sheet rolls 66 and 67 around which the raw material sheets of the skin layers 30 and 40 are wound, and a third for the skin layer joining process. Conveyor 68 is arranged.

As shown in FIG. 3, in the molding step, a sheet made of a thermoplastic resin wound around a sheet roll 61 is supplied to a vacuum forming drum 62, and a sheet material 100 having a predetermined uneven shape formed on the sheet is formed. It is molded. The vacuum forming drum 62 is pivotally supported so as to be rotationally driveable and can be heated to a predetermined temperature. The rotation speed of the vacuum forming drum 62 is set to be equal to the rotation speed of the sheet roll 61. Further, a cylindrical molding die is attached to the outer peripheral portion of the vacuum forming drum 62, and is configured to enable vacuum drawing through a through hole formed in the molding die (not shown). ). The outer peripheral surface of the molding die has an uneven shape formed on the sheet material 100 so that the X direction of the sheet material 100 is along the circumferential direction thereof (first bulging portion 110 and second bulging described below). A concave-convex shape similar to that of the protruding portion 120) is formed.

As shown in FIG. 2A, in the sheet material 100 molded by the molding die, the first bulging portion 110 and the second bulging portion 120 forming a band shape are alternately arranged in the width direction (Y direction). Have been placed. The first bulging portion 110 is formed in a shape protruding upward, and the second bulging portion 120 is formed in a shape protruding downward. The first bulging portion 110 and the second bulging portion 120 are alternately arranged so as to extend in the X direction. The first bulging portion 110 when the sheet material 100 is viewed from above and the second bulging portion 120 when the sheet material 100 is viewed from the bottom have the same shape and are displaced by 1/2 pitch in the X direction. Is formed in.

The first bulging portion 110 is composed of an upper surface 110a, a pair of side surfaces 110b, and a pair of end surfaces 110c, and has a trapezoidal shape obtained by dividing a regular hexagon into two by the longest diagonal line in the Y direction. The pair of end faces 110c are formed at the position of the folding line P shown in FIG. 2A. The angle between the end surface 110c and the upper surface 110a is about 90 °.

On the other hand, the second bulging portion 120 is composed of a lower surface 120a, a pair of side surfaces 120b, and a pair of end faces 120c, and has a trapezoidal shape obtained by dividing a regular hexagon into two by the longest diagonal line. .. The pair of end faces 120c are formed at the position of the folding line Q shown in FIG. 2A. The angle between the end surface 120c and the lower surface 120a is about 90 °. The length of the second bulging portion 120 in the X direction, that is, the length between the pair of end faces 120c is the same as the length of the first bulging portion 110 in the X direction, that is, the length between the pair of end faces 110c. be. The end face 120c of the second bulging portion 120 is located at the center of the first bulging portion 110 in the X direction. The side surface 110b of the first bulging portion 110 and the side surface 120b of the second bulging portion 120 are separated for convenience of explanation, but have the same configuration.

As described above, in the molding step, the first bulging portion 110 and the second bulging portion formed by partially bulging the sheet upward or bulging downward by a vacuum forming method utilizing the plasticity of the sheet. A sheet material 100 having a protrusion 120 is obtained.

As shown in FIG. 3, in the joint portion forming step, the sheet material 100 is transported between the pair of transport rolls 63. The rotation speed of the transfer roll 63 is set to be equal to the rotation speed of the vacuum forming drum 62. Further, a hot melt adhesive (not shown) is sequentially supplied to the surface of the transport roll 63 in a molten state. As a result, the adhesive in a molten state is applied to the surface of the sheet material 100 that has passed between the pair of transport rolls 63. The adhesive is applied as a thin film on the entire upper surface 110a of the first bulging portion 110 on the upper surface of the sheet material 100, and as a thin film on the entire lower surface 120a of the second bulging portion 120 on the lower surface of the sheet material 100. Is applied to.

As shown in FIG. 3, in the folding step, the sheet material 100 to which the adhesive is applied to form the adhesive layer moves to the downstream side in a state where the vertical movement of the sheet material 100 is restricted by the first conveyor 64. Be transported. At this time, the transfer speed by the first conveyor 64 is set to be slower than the rotation speed of the sheet roll 61, the vacuum forming drum 62, and the transfer roll 63 arranged on the upstream side of the first conveyor 64. ing. That is, the transfer speed by the first conveyor 64 is set to be slower than the supply speed of the sheet material 100 that has passed through the transfer roll 63. Further, the first conveyor 64 is provided with a heating device 64a for heating the temperature between the first conveyors 64 to a predetermined temperature. Therefore, when the sheet material 100 is conveyed between the first conveyors 64, the sheet material 100 is folded while being heated and compressed in the downstream direction to form the core layer 20.

As shown in FIGS. 2 (b) and 2 (c), the transfer speed of the first conveyor 64 is set to be slower than the rotation speed of the transfer roll 63 on the upstream side thereof, whereby the sheet is set. The material 100 is sequentially folded along the folding lines P and Q to form the core layer 20. Specifically, as shown in FIG. 2B, the sheet material 100 is mountain-folded along the folding line P and valley-folded along the folding line Q. As shown in FIG. 2 (c), in one first bulging portion 110, the first bulging portion 110 is valley-folded along the folding line Q provided in the central portion in the X direction, and the upper surface 110a on the right side in the X direction and the upper surface on the left side in the X direction are folded. 110a abuts in an upright position. In the folded first bulging portion 110, the side wall portion 23 having a two-layer structure of the core layer 20 is formed by the upper surface 110a on the right side in the X direction and the upper surface 110a on the left side in the X direction, which are in contact with each other in an upright position, and the side surface 110b. As a result, the side wall portion 23 of the one-layer structure of the core layer 20 is formed. At the upper end of the side wall portion 23, an upper wall portion 21 composed of end faces 110c of the adjacent first bulging portions 110 is formed.

Further, in one second bulging portion 120, the fold line P provided at the center of the adjacent fold lines Q in the X direction is folded in a mountain, and the lower surface 120a on the right side in the X direction and the lower surface 120a on the left side in the X direction are in an upright state. Contact with. In the folded second bulging portion 120, the side wall portion 23 having a two-layer structure of the core layer 20 is formed by the lower surface 120a on the right side in the X direction and the lower surface 120a on the left side in the X direction, which are in contact with each other in an upright position, and the side surface 120b. As a result, the side wall portion 23 of the 20 one-layer structure of the core layer is formed. At the lower end of the side wall portion 23, a lower wall portion 22 composed of end faces 120c of adjacent second bulging portions 120 is formed.

In the joint portion forming step, the adhesive in a molten state is applied by the transport roll 63, and in the folding step, the first conveyor 64 is heated by the heating device 64a. Therefore, when the core layer 20 formed by folding passes through the first conveyor 64, the adhesive of the adhesive layer is in a melted state. Further, the core layer 20 heated by the heating device 64a of the first conveyor 64 is pressed by the first conveyor 64. Therefore, the upper end edge and the lower end edge of the side wall portion 23 of the two-layer structure are in a heat-welded state.

As shown in FIG. 3, the core layer 20 obtained by the folding step moves toward the second conveyor 65. The transfer speed by the second conveyor 65 is set to be equal to the transfer speed by the first conveyor 64. Therefore, the folded core layer 20 passes through the second conveyor 65 while maintaining its shape.

The second conveyor 65 is not provided with a heating device. Therefore, the molten adhesive applied to the side wall portion 23 of the two-layer structure in the core layer 20 is cooled and solidified. As a result, the first side wall portion 23a and the second side wall portion 23b forming the two-layer structure are joined via the joining portion 23c formed by cooling and solidifying the adhesive (joining step).

Subsequently, the core layer 20 obtained by the joining step moves toward the third conveyor 68. The transfer speed by the third conveyor 68 is set to be equal to the transfer speed by the second conveyor 65. Further, the third conveyor 68 is also not provided with a heating device. Sheet rolls 66 and 67 around which a sheet made of a thermoplastic resin as a raw material of the skin layers 30 and 40 is wound are arranged in the vicinity of the carry-in port of the third conveyor 68, respectively. An adhesive (not shown) is applied to the sheets wound around the sheet rolls 66 and 67. The adhesive here is also preferably a hot melt adhesive made of a resin compatible with the polypropylene resin, like the adhesive layer constituting the joint portion 23c.

By passing between the third conveyors 68, the sheets wound around the sheet rolls 66 and 67 are sequentially supplied to the upper surface 20a and the lower surface 20b of the core layer 20. In this state, the adhesive applied to the sheets from the sheet rolls 66 and 67 is in a molten state. On the other hand, since the third conveyor 68 is not provided with a heating device, the sheets supplied to the upper surface 20a and the lower surface 20b of the core layer 20 are joined by cooling and solidifying the applied adhesive. As a result, a hollow structure 10 in which the skin layers 30 and 40 are bonded to the upper surface 20a and the lower surface 20b of the core layer 20 via an adhesive layer is obtained.

The operation of the hollow structure 10 will be described with reference to FIG.
The method for manufacturing the hollow structure 10 of the present embodiment includes a joint portion forming step of applying an adhesive to the sheet material 100 before the folding step of folding the sheet material 100. In the joint portion forming step, a hot melt adhesive is applied to the entire contact portion of the side wall portion 23 (first side wall portion 23a and second side wall portion 23b) of the two-layer structure in the core layer 20 formed by folding in the folding step. Is applied. Therefore, as shown in FIG. 4, in the core layer 20 formed by folding the sheet material 100, the first side wall portion 23a and the second side wall portion 23b constituting the two-layer structure are firmly joined via the joint portion 23c. Has been done. When a bending force is applied in the thickness direction of the hollow structure 10, the occurrence of bending of the hollow structure 10 starting from the side wall portion 23 of the two-layer structure is suppressed.

On the other hand, if the first side wall portion 23a and the second side wall portion 23b are only in contact with each other and are not joined, the side wall portion 23 of the two-layer structure is the starting point when a bending force is applied in the thickness direction of the hollow structure 10. It is easy to break. Further, as shown by the dotted line in FIG. 4, for example, when the internal pressure in the cell S is increased for some reason, the first side wall portion 23a and the second side wall portion 23b are pushed between the layers by the internal pressure. It may be deformed so that it can be unfolded. If a bending force is applied in the thickness direction in that state, the strength against bending is further reduced.

According to the hollow structure 10 of the present embodiment and the manufacturing method thereof, the following effects can be obtained.
(1) The hollow structure 10 of the present embodiment is formed by folding and molding a sheet material formed of one sheet made of synthetic resin, and a plurality of cells S are arranged side by side inside. A part of the side wall portion 23 for partitioning the cell S has a two-layer structure including a first side wall portion 23a and a second side wall portion 23b, and the first side wall portion 23a and the second side wall portion 23b have a hollow structure 10. In the middle portion in the thickness direction of the above, the adhesive is joined by a joining portion 23c formed by cooling and solidifying. Therefore, even when a bending force is applied to the hollow structure 10 in the thickness direction, the hollow structure starts from the side wall portion 23 (first side wall portion 23a and second side wall portion 23b) of the two-layer structure. 10 is less likely to break. A hollow structure 10 having excellent bending strength can be obtained.

(2) In the hollow structure 10 of the present embodiment, the first side wall portion 23a and the second side wall portion 23b are joined by forming a joint portion 23c on the entire surface thereof. Therefore, the strength of the first side wall portion 23a and the second side wall portion 23b is improved, and the bending starting from the first side wall portion 23a and the second side wall portion 23b is unlikely to occur. A hollow structure 10 having excellent bending strength can be obtained.

(3) In the hollow structure 10 of the present embodiment, the cells S juxtaposed to the core layer 20 are composed of a first cell S1 and a second cell S2 having different configurations. The upper end of the first cell S1 is closed by the upper wall portion 21, and the lower end thereof is opened downward without being blocked, and the lower end of the second cell S2 is closed by the lower wall portion 22. At the same time, its upper end is open upward without being blocked. Therefore, it is lighter than the core layer in which the upper ends and the lower ends of all cells S are closed. A hollow structure 10 that is not only excellent in bending strength but also lightweight can be obtained. Further, the amount of the thermoplastic resin constituting the hollow structure 10 is small, which is advantageous in terms of cost.

(4) The hollow structure 10 of the present embodiment has the upper surface 110a and the second bulge of the first bulge 110 with respect to the sheet material 100 on which the first bulge 110 and the second bulge 120 are formed. It is manufactured by folding the sheet material 100 through a joining portion forming step of applying a hot melt adhesive to the lower surface 120a of the protruding portion 120. Therefore, by folding and cooling the sheet material 100, the first bulging portion 110 and the second bulging portion 120 can be joined at the joining portion 23c. The work of joining the first bulging portion 110 and the second bulging portion 120 can be easily performed.

(5) The formation of the adhesive layer of the joint portion 23c of the first bulging portion 110 and the second bulging portion 120, that is, the upper surface 110a of the first bulging portion 110 and the lower surface 120a of the second bulging portion 120 is predetermined. This is done by applying a hot melt adhesive with a transport roll 63 heated to a temperature. Therefore, the hot melt adhesive can be easily applied in the form of a thin film. The joint portion 23c can be easily formed.

(6) The hollow structure 10 of the present embodiment is manufactured through a molding step, a joining portion forming step, a folding step, a joining step, and a skin layer joining step, and each step is performed in a series of flows by the apparatus T. There is. Therefore, the hollow structure 10 can be manufactured with excellent productivity and mass productivity, which is advantageous in terms of cost.

(7) The transfer speed of the first conveyor 64 constituting the folding step is slower than the rotation speed of the sheet roll 61, the vacuum forming drum 62, and the transfer roll 63 arranged on the upstream side of the first conveyor 64. It is set to be. That is, the transfer speed of the first conveyor 64 is slower than the supply speed of the sheet material 100 that has passed through the transfer roll 63. Therefore, the sheet material 100 is sequentially folded along the folding lines P and Q. By moving the sheet material 100, the folding step can be easily performed.

(8) A heating device 64a is provided on the first conveyor 64 constituting the folding step. Therefore, the core layer 20 can be folded while keeping the hot melt adhesive in a molten state.

(9) The folded core layer 20 is cooled while passing through the second conveyor 65, so that the adhesive layer is cooled and solidified to form the joint portion 23c. While the shape of the core layer 20 is maintained between the second conveyors 65, the side wall portions 23 of the two-layer structure are joined via the joining portion 23c. The first side wall portion 23a and the second side wall portion 23b of the two-layer structure are firmly joined without being displaced.

The above embodiment can be changed as follows. The above embodiment and the following modified examples can be applied in combination with each other within a technically consistent range.
-In the above embodiment, the joint portion 23c is composed of an adhesive layer, but is not limited thereto. For example, instead of the adhesive layer, it may be composed of a welded layer formed by welding a low melting point film. In this case, in the device T shown in FIG. 3, a roller for supplying the low melting point film may be arranged instead of the transport roll 63 for applying the adhesive. By heat-melting the supplied low melting point film, the first side wall portion 23a and the second side wall portion 23b are heat-welded.

The low melting point film may have a single-layer structure or a multi-layer structure, and the material thereof is not particularly limited. For example, a multilayer structure of different material resins made of polypropylene resin and polyethylene resin, a multilayer structure of the same material such as homopolymer polypropylene resin and random polymer polypropylene resin, and the like can be mentioned.

When the first side wall portion 23a and the second side wall portion 23b are joined by welding, the thermoplastic resin constituting the first side wall portion 23a and the second side wall portion 23b may be joined by heat welding. .. In this case, for example, the transport roll 63 in the apparatus T is heated to a predetermined temperature, and the upper surface 110a of the first bulging portion 110 and the lower surface 120a of the second bulging portion 120 in the sheet material 100 that has passed through the transport roll 63. , The thermoplastic resin constituting the sheet material 100 is in a heat-melted state. When the sheet material 100 passes through the first conveyor 64, it is heated by the heating device 64a and folded in a state where the thermoplastic resin is thermally melted to form the core layer 20. When the core layer 20 passes through the second conveyor 65, the thermally melted thermoplastic resin is cooled and solidified to form a joint portion 23c. That is, the joint portion 23c is composed of a portion (heat-welded portion) in which the thermally melted thermoplastic resin is cooled and solidified on the upper surface 110a of the first bulging portion 110 and the lower surface 120a of the second bulging portion 120. become.

When the joint portion 23c is composed of a heat welding portion, the transfer roll 63 of the apparatus T may be eliminated and the heating temperature of the heating apparatus 64a in the first conveyor 64 may be adjusted. For example, the heating temperature of the heating device 64a is adjusted to a temperature close to the temperature at which the thermoplastic resin constituting the sheet material 100 is thermally melted. As a result, when the thermoplastic resin constituting the upper surface 110a of the first bulging portion 110 and the lower surface 120a of the second bulging portion 120 in the sheet material 100 is partially thermally melted and passes through the second conveyor 65. The thermally melted thermoplastic resin of the upper surface 110a of the first bulging portion 110 and the lower surface 120a of the second bulging portion 120 is cooled and solidified to form the joint portion 23c.

-In the present embodiment, the first side wall portion 23a and the second side wall portion 23b of the two-layer structure are joined by a joining portion 23c formed so as to correspond to the entire surface thereof, but the range of the joining portion 23c includes this. Not limited. For example, as shown in FIG. 7A, the joint portion 23c is provided so as to extend laterally to a part of the side wall portion 23 excluding the upper end edge and the lower end edge in the side wall portion 23 of the two-layer structure. May be good. In that case, the joint portion 23c is a position closer to the center in the vertical intermediate portion of the first side wall portion 23a and the second side wall portion 23b, and is at least the height of the first side wall portion 23a and the second side wall portion 23b. It is preferably provided at a position of about 1/2, and more preferably at a position of at least about 2/3. Here, assuming that the position closer to the center in the vertical intermediate portion of the first side wall portion 23a and the second side wall portion 23b is referred to as a central portion, the joint portion 23c is provided in the central portion. The bending strength of the hollow structure 10 is improved as compared with the case where the hollow structure 10 is provided in an intermediate portion other than the central portion. Further, even if the joint portion 23c is provided only in the central portion, sufficient bending strength can be imparted to the hollow structure 10. It should be noted that each figure shown in FIG. 7 shows a state in which the side wall portion 23 is viewed from the front.

As shown in FIG. 7B, the joint portion 23c may be provided so as to extend laterally to the upper end portion and the lower end portion in the side wall portion 23 of the two-layer structure.
Further, as shown in FIG. 7 (c), the side wall portion 23 may be provided so as to extend in the vertical direction at the side end portion of the side wall portion 23 of the two-layer structure, and as shown in FIG. 7 (d), the side wall portion 23. It may be provided so as to extend in the vertical direction at the central portion in the horizontal direction of the. As shown in FIG. 7 (e), it may be provided in the peripheral portion of the side wall portion 23 of the two-layer structure.

Further, as shown in FIG. 7 (f), it may be provided in a plurality of dots.
The modified examples shown in FIGS. 7 (a) to 7 (f) can be appropriately combined with a plurality of modified examples. For example, the modification shown in FIG. 7 (e) and the modification shown in FIG. 7 (f) may be combined. By doing so, the area of the joint portion 23c is increased, the joint strength of the first side wall portion 23a and the second side wall portion 23b is improved, and the bending strength of the hollow structure 10 is improved.

In order to form the joint portion 23c of each of these modified examples, the portion to which the adhesive is applied may be appropriately adjusted in the joint portion forming step. For example, if a groove is formed in the transport roll 63 for supplying the hot melt adhesive, the hot melt adhesive is applied to the upper surface 110a of the first bulging portion 110 and the lower surface 120a of the second bulging portion 120. It is possible to form a part that is not. Further, instead of supplying the hot melt adhesive from the transport roll 63, for example, the adhesive can be directly applied or sprayed on the sheet material 100.

In the core layer 20, the first side wall portion 23a and the second side wall portion 23b are heat-welded and joined at the upper end edge and the lower end edge by heating in the folding step and the skin layer joining step. .. The joint portion 23c may be provided up to a position overlapping the portions joined by heat welding of the upper end edge and the lower end edge of the first side wall portion 23a and the second side wall portion 23b, or the intermediate portion in the thickness direction. Therefore, the first side wall portion 23a and the second side wall portion 23b may be provided at positions separated from the portions joined by heat welding of the upper end edge and the lower end edge. It suffices that the side wall portion 23 of the two-layer structure is joined at least at the intermediate portion in the thickness direction of the hollow structure 10 to form the joined portion 23c.

At the upper end edge and the lower end edge of the side wall portion 23 of the two-layer structure of the above embodiment, the portion bonded (adhered) via the joint portion 23c by heating in the folding step and the skin layer joining step and the thermoplastic resin. Is hot-melted and heat-welded parts coexist. However, the present invention is not limited to this, and the upper end edge and the lower end edge may not be joined (bonded) or heat welded. That is, the joint portion of the first side wall portion 23a and the second side wall portion 23b is only the portion of the joint portion 23c, and the upper end edge and the lower end edge thereof may not be joined to each other.

In the above embodiment, the core layer 20 in which the first conveyor 64 is folded by the heating device 64a is heated in the folding step, so that the upper end edge and the lower end edge of the side wall portion 23 of the two-layer structure are heat-welded. There is. However, the heating device 64a may be omitted. In this case, the upper end edge and the lower end edge of the side wall portion 23 of the two-layer structure are not heat-welded, and the core layer 20 in which the joint portion 23c is formed in the middle portion of the side wall portion 23 of the two-layer structure can be obtained.

In the sheet material 100 forming the core layer 20, the angle formed by the upper surface 110a and the end surface 110c of the first bulging portion 110 is about 90 °, and in FIG. 2A, the upper surface 110a is formed as a flat surface. There is. Further, the angle formed by the lower surface 120a of the second bulging portion 120 and the end surface 120c is about 90 °, and in FIG. 2A, the lower surface 120a is formed as a flat surface. However, the shapes of the upper surface 110a and the lower surface 120a are not limited to such flat surfaces. For example, the upper surface 110a may bulge in a shape that curves upward, or the lower surface 120a may bulge in a shape that curves downward. For example, when the upper surface 110a has such a shape, the upper surface 110a coated with the adhesive is pressed against each other in a state of forming a two-layer structure during the folding step, and the entire upper surface 110a is easily in good contact with each other. Therefore, by the subsequent cooling and curing of the adhesive, the first side wall portion 23a and the second side wall portion 23b of the two-layer structure are firmly joined on the entire surface thereof. This also applies to the joining of the lower surfaces 120a to each other.

In the above embodiment, the joint portion 23c supplies an adhesive from the transport roll 63 in the joint portion forming step, and after the folding step, the adhesive between the first side wall portion 23a and the second side wall portion 23b is cooled and solidified. Formed. The formation of the joint 23c is not limited to this form. For example, as shown in FIG. 5, the side wall portion 23 of the two-layer structure is heated by the heating jigs 71 and 72, and the thermoplastic resin constituting the first side wall portion 23a and the second side wall portion 23b is thermally melted. You may. In the device T1 shown in FIG. 5, heating jigs 71 and 72 are arranged in place of the second conveyor 65 in the device T shown in FIG. Further, although the transport roll 63 is configured to be able to heat the sheet material 100 by being heated to a predetermined temperature, it is not configured to supply a hot melt adhesive. Therefore, the core layer 20 that has passed through the first conveyor 64 does not have the joint portion 23c of the side wall portion 23 of the two-layer structure.

The method for manufacturing the hollow structure 10 in the apparatus T1 is a molding step of molding the sheet material 100 from one sheet made of synthetic resin, and a first side wall portion 23a and a second side wall portion by folding the sheet material 100. In the folding step of abutting the portions 23b to form the intermediate body 90 having the side wall portion 23 of the two-layer structure, and in the side wall portion 23 of the two-layer structure of the intermediate body 90, the first side wall portion 23a and the second side wall portion 23b. It is provided with a joining step of joining the intermediate portion in the thickness direction of. In the joining step, heating is performed with the side wall portion 23 of the two-layer structure sandwiched between the heating jigs 71 and 72 to form the joining portion 23c and join. The intermediate 90 referred to here is different from the core layer 20 of the above embodiment in that the adhesive layer is not interposed between the first side wall portion 23a and the second side wall portion 23b. However, in other respects, the core layer 20 has a similar configuration.

As shown in FIG. 5, the heating jigs 71 and 72 are arranged on the upper surface 20a side and the lower surface 20b side of the core layer 20 (intermediate body 90) moving on the device T1. It is equipped with a heating jig 72. A plurality of small heating plates 71a are formed at the tip of the heating jig 71, and each heating plate 71a has a shape in which a plurality of pair of flat plate-shaped heating plates are arranged side by side. The pair of flat plate-shaped heating plates are arranged between the thickness separations of the side wall portions 23 having a two-layer structure. In the heating jig 71, in the core layer 20 (intermediate body 90) moving on the device T1, a plurality of small heating plates 71a are arranged at positions corresponding to the portions where the second cells S2 are arranged side by side. It is provided in. As shown in FIG. 5, when the heating jig 71 having such a configuration is moved downward and moved from the upper surface 20a side of the core layer 20 (intermediate body 90) that has passed through the first conveyor 64 to the inside of the second cell S2. , The side wall portion 23 of the two-layer structure formed in the second cell S2 is sandwiched between the pair of heating plates 71a. As a result, the thermoplastic resin constituting the side wall portion 23 is thermally melted by the heat from the heating plate 71a of the heating jig 71. At this time, the heating jig 71 is set so as to be movable according to the core layer 20 moving on the device T1 at a predetermined speed. That is, the heating jig 71 is set to have a transfer speed equal to that of the first conveyor 64. After the side wall portion 23 is thermally melted by the heating jig 71, the heating jig 71 moves upward.

Similarly, a plurality of small heating plates 72a are formed at the tip of the heating jig 72, and each heating plate 72a includes a pair of flat plate-shaped heating plates. The pair of flat plate-shaped heating plates are arranged between the thickness separations of the side wall portions 23 having a two-layer structure. In the heating jig 72, in the core layer 20 (intermediate body 90) moving on the device T1, a plurality of small heating plates 72a are arranged at positions corresponding to the portions where the first cells S1 are arranged side by side. It is provided in. As shown in FIG. 5, when the heating jig 72 having such a configuration is moved upward and moved from the lower surface 20b side of the core layer 20 (intermediate body 90) that has passed through the first conveyor 64 to the inside of the first cell S1. , The side wall portion 23 of the two-layer structure formed in the first cell S1 is sandwiched between the pair of heating plates 72a. As a result, the thermoplastic resin constituting the side wall portion 23 is thermally melted by the heat from the heating plate 72a of the heating jig 72. At this time, the heating jig 72 is set so as to be movable according to the core layer 20 (intermediate body 90) moving on the device T1 at a predetermined speed. After the side wall portion 23 is thermally melted by the heating jig 72, the heating jig 72 moves downward.

The core layer 20 (intermediate 90) in a state where the side wall portion 23 is thermally melted by the heating jigs 71 and 72 is conveyed toward the fourth conveyor 69. Since the fourth conveyor 69 is not provided with a heating device, the heat-melted side wall portion 23 is cooled and solidified, and the joint portion 23c is formed on the first side wall portion 23a and the second side wall portion 23b. As described above, the joining portion 23c can be formed and the first side wall portion 23a and the second side wall portion 23b can be joined by heat welding of the side wall portion 23 using the heating jigs 71 and 72 as the joining step. In FIG. 5, for the sake of clarity, the heating jig 71 is shown larger than the core layer 20 (intermediate 90).

Further, as a joining method of the first side wall portion 23a and the second side wall portion 23b, ultrasonic bonding, vibration bonding, high frequency bonding and the like can be mentioned. In this case, the joint portion 23c can be formed by performing at least one of ultrasonic treatment, vibration treatment, high frequency treatment, and laser treatment on the side wall portion 23 of the two-layer structure of the intermediate body 90.

Specific examples of the high frequency treatment include high frequency induction heating treatment (high frequency welder treatment). By the high-frequency welder treatment, the molecules of the high-frequency heat-generating resin contained in the first side wall portion 23a and the second side wall portion 23b can be vibrated, and the heat generated by the molecular motion can be used for welding to each other. Further, the intermediate 90 is formed from the sheet material containing the high-frequency heat-generating resin, or the intermediate 90 is formed by attaching the film containing the high-frequency heat-generating resin to the sheet material to perform high-frequency welder treatment. You may. Alternatively, the intermediate body 90 is formed from a sheet material containing a metal piece or a high-frequency heating element, or a film containing a metal piece or a high-frequency heating element is attached to the sheet material to form the intermediate body 90 to form a high-frequency welder. It can also be processed.

As a specific method of laser treatment, for example, an intermediate 90 is formed from a sheet material containing an absorbent (black or the like) having a high laser absorption rate, or a film containing an absorbent having a high laser absorption rate is used as a sheet material. It can be attached to the body to form an intermediate body 90 and subjected to laser treatment.

The core layer 20 does not have to be formed through a folding step of folding the sheet material 100. For example, the core layer 80 may be formed from the sheet material 200 as shown in FIG. 6A.

As shown in FIG. 6A, in the sheet material 200, the flat surface regions 210 and the bulging regions 220 forming a band are alternately arranged in the longitudinal direction (X direction) of the sheet material 200. In the bulging region 220, a first bulging portion 221 having a cross-sectional 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 220. The angle between the upper surface and the side surface of the first bulging portion 221 is preferably 90 °, and as a result, the cross-sectional shape of the first bulging portion 221 is a downward U-shape. Further, the width of the first bulging portion 221 (the length in the lateral direction of the upper surface) is equal to the width of the plane region 210, and the bulging height of the first bulging portion 221 (the length in the lateral direction of the side surface). ) Is set to be twice as long.

Further, in the bulging region 220, a plurality of second bulging portions 222 having a trapezoidal shape obtained by dividing a regular hexagon into two by the longest diagonal line are orthogonal to the first bulging portion 221. It is formed. The bulging height of the second bulging portion 222 is set to be equal to the bulging height of the first bulging portion 221. Further, the distance between the adjacent second bulging portions 222 is equal to the width of the upper surface of the second bulging portion 222.

As shown in FIGS. 6A and 6B, the core layer 80 is formed by folding the sheet material 200 configured as described above along the folding lines P and Q. Specifically, the sheet material 200 is valley-folded along the folding line P between the flat surface region 210 and the bulging region 220, and mountain-folded along the folding line Q between the upper surface and the side surface of the first bulging portion 221. Shrinks in the X direction. Then, as shown in FIGS. 6 (b) and 6 (c), the upper surface and the side surface of the first bulging portion 221 are folded, and the end surface of the second bulging portion 222 and the plane region 210 are folded. , A prismatic section 230 extending in the Y direction is formed for one bulging region 220. The hollow plate-shaped core layer 80 is formed by continuously forming the compartments 230 in the X direction.

When the sheet material 200 is folded and formed as described above, the upper wall portion 81 of the core layer 80 is formed by the upper surface and the side surface of the first bulging portion 221, and the end surface and the plane region of the second bulging portion 222 are formed. The lower wall portion 82 of the core layer 80 is formed by the 210.

Further, the hexagonal column-shaped region formed by folding the second bulging portion 222 becomes the second cell S2'in the core layer 80, and the hexagonal column formed between the pair of adjacent compartments 230. The region of the shape becomes the first cell S1'in the core layer 80. In the present embodiment, the upper surface and the side surface of the second bulging portion 222 form the side wall portion 83 of the second cell S2', the side surface of the second bulging portion 222, and the second bulging portion in the bulging region 220. The flat surface portion located between 222 constitutes the side wall portion 83 of the first cell S1'. Then, the contact portion between the upper surfaces of the second bulge portion 222 and the contact portion between the plane portions in the bulge region 220 form a side wall portion 83 having a two-layer structure.

When the adhesive layer is applied by the device T using such a sheet material 200, the adhesive layer is applied to the upper surface of the second bulging portion 222 in the sheet material 200 and the lower surface of the flat surface portion in the bulging region 220. Should be set.

In the method for manufacturing the hollow structure 10 of the present embodiment, the molding step, the joining portion forming step, the folding step, the joining step, and the skin layer joining step are performed in a series of steps by the apparatus T. The present invention is not limited to this, and may be performed by a plurality of devices instead of one device. For example, the molding step and the folding step for forming the sheet material 100 may be performed by different devices, or the folding step and the skin layer joining step may be performed by different devices.

-In the method for manufacturing the hollow structure 10 of the present embodiment, the hot melt adhesive is applied by using the transport roll 63 in the joining portion forming step, but the present invention is not limited to this. An adhesive other than the hot melt adhesive may be applied to the sheet material 100 with a brush or the like, or may be sprayed onto the sheet material 100 with a spray device or the like.

In the joining step in the method for manufacturing the hollow structure 10 of the present embodiment, the skin layers 30 and 40 are joined to the core layer 20 by an adhesive, but are joined by heat welding to the core layer 20. May be good.

In the hollow structure 10 of the present embodiment, hexagonal columnar cells S are partitioned inside the core layer 20, but the shape of the cells S is not limited to this. For example, it may be a polygonal column such as a square column or an octagonal column, or a columnar column.

The skin layers 30 and 40 joined to the hollow structure 10 are not a one-layer structure, but at least one of them may have a multi-layer structure.
-At least one of the skin layers 30 and 40 may be omitted.

-As the thermoplastic resin constituting the core layer 20 and the skin layers 30 and 40, those to which various functional resins are added may be used. For example, it is possible to enhance the flame retardancy by adding a flame retardant resin to the thermoplastic resin. It is also possible to use those in which various functional resins are added to all of the core layer 20 and the skin layers 30 and 40, and to at least one of the core layer 20 and the skin layers 30 and 40. It is also possible to use it.

The technical ideas that can be grasped from this embodiment are described below.
(B) A hollow structure in which a sheet material formed from a single synthetic resin sheet so as to have a predetermined uneven shape is folded and molded, and a plurality of cells are arranged side by side inside. A part of the side wall portion erected in the direction and partitioning the cell has a two-layer structure including a first side wall portion and a second side wall portion joined at both end edges in the thickness direction, and the first side wall portion. And the second side wall portion is joined by adhesion or welding at least in the intermediate portion in the thickness direction.

10 ... Hollow structure, 20, 80 ... Core layer, 23, 83 ... Side wall, 23a ... First side wall, 23b ... Second side wall, 23c ... Joint, 30 ... Skin layer, 40 ... Skin layer, 90 ... Intermediate, 100, 200 ... Sheet material, S ... Cell, S1 ... 1st cell, S2 ... 2nd cell.

Claims (1)

A method for manufacturing a hollow structure in which a plurality of cells are partitioned inside by a side wall portion of a two-layer structure which is erected in the thickness direction and includes a first side wall portion and a second side wall portion.
A molding process of molding a sheet material having a predetermined uneven shape from a single sheet made of synthetic resin, and
A folding step of forming an intermediate having a side wall portion having a two-layer structure in which the first side wall portion and the second side wall portion are in contact with each other by folding the sheet material.
A joining step of joining the first side wall portion and the second side wall portion in the side wall portion of the two-layer structure of the intermediate is provided.
The molding step, the folding step, and the joining step are performed in a series of steps by one device.
The joining step is performed by heating using a heating jig in which a plurality of flat plate-shaped heating plates are arranged side by side at the tip, with the side wall portion of the two-layer structure sandwiched between the heating plates.
The intermediate has a first cell in which one face side of the intermediate is open and the other face side is closed, and one face side of the intermediate is closed and the other face side is closed. The cell comprising the second cell which is open is provided.
The first cell is partitioned by the side wall portion of the two-layer structure so that a plurality of the first cells are adjacent to each other in a row, and the second cell is the two-layer structure. A plurality of the second cells are formed so as to be adjacent to each other in a row, which is partitioned by a side wall portion.
In the joining step, the heating jigs are arranged on one surface side and the other surface side of the intermediate, respectively.
The heating jig on one surface side heats the side wall portion of the two-layer structure that partitions the first cell, and the heating jig on the other surface side heats the second cell. A method for manufacturing a hollow structure in which a hollow structure is heated while sandwiching the side wall portion of the two-layer structure to be partitioned .

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