JP7406810B2 - Hollow structure and method for manufacturing hollow structure - Google Patents

Description

The present disclosure relates to a hollow structure and a method for manufacturing the hollow structure.

Patent Document 1 discloses a typical lightweight folding container.

As shown in FIG. 13, a typical lightweight folding container 70 includes a tilt plate 71. As shown in FIG. The tilt plate 71 has an outer frame 72 and a plastic cardboard 73 joined to the outer frame 72. The above publication exemplifies insert molding as a method for joining the plastic cardboard 73 to the outer frame 72.

Japanese Patent Application Publication No. 2001-180669

When insert molding the outer frame 72, the injected resin may flow into the plastic cardboard 73. If too much resin flows into the plastic cardboard 73, the amount of resin necessary for molding the outer frame 72 may become insufficient. If this happens, there is a risk that a part of the outer frame 72 may become defective in shape, or that the weight of the swing plate 71, which has a hollow structure, becomes larger than a predetermined weight.

An object of the present disclosure is to provide a lightweight hollow structure in which a resin molded part is suitably formed, and a method for manufacturing the same.

A hollow structure according to one aspect of the present disclosure includes a plate material having a hollow structure, which is a laminate in which a first skin layer, a core layer, and a second skin layer are laminated in this order; a resin molded part disposed along the edge of the resin molded part. The plate material has a proximal portion extending along the resin molded portion. In the proximal portion, at least one of the first and second skin layers is bent to be proximate to the other.

A method for manufacturing a hollow structure according to one aspect of the present disclosure includes forming a plate-shaped core layer having a plurality of cells by molding a first sheet, and forming a second sheet and a second sheet on both sides of the core layer, respectively. 3 sheets are joined to form a laminate having a hollow structure, and the laminate is sandwiched between a first mold and a second mold, and the laminate is sandwiched between the first mold and the second mold. defining a molding space along the edge of the laminate; flowing molten resin into the molding space; and solidifying the molten resin in the molding space to form a molding space along the edge of the laminate. molding a resin molded part along the. At least one of the first mold and the second mold has a pressing protrusion protruding into the molding space, and the pressing protrusion has a tip end surface for pressing the edge of the laminate. has.

FIG. 1 is a perspective view of a hollow structure according to an embodiment. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1. FIG. 2 is an exploded perspective view of a plate included in the hollow structure of FIG. 1; FIG. 2 is a sectional view of a mold device for insert molding and a laminate. FIG. 4B is a cross-sectional view showing a state in which the laminate is sandwiched between the mold apparatus of FIG. 4A. FIG. 4B is a cross-sectional view showing a state in which resin is flowed into the mold device of FIG. 4B. FIG. 2 is a plan view showing a part of the hollow structure of FIG. 1; FIG. 4B is a cross-sectional view showing positioning through-holes included in the laminate of FIG. 4A. 5A is a cross-sectional view showing a part of the stacked body positioned within the mold apparatus through the positioning through hole of FIG. 5A. FIG. FIG. 5B is a cross-sectional view showing a state in which resin is flowed into the mold device of FIG. 5B. FIG. 3 is a cross-sectional view of a mold device and a laminate according to a first modification example. The perspective view which shows the state in the middle of folding the molded 1st sheet of the 1st modification. The perspective view of the core layer of a 1st modification. FIG. 7 is a sectional view of a mold device and a laminate according to a second modification example. The perspective view of the molded 1st sheet of the 2nd modification. FIG. 11 is a perspective view showing a state in which the first sheet of FIG. 10 is being folded; FIG. 7 is a perspective view of a core layer of a second modification example. A diagram showing a typical hollow structure.

In the specification and claims, terms such as "first", "second", etc. are used to distinguish between similar elements and not necessarily in a particular sequential or chronological order. It is not used to represent.

All features disclosed in the specification and/or claims are included in the claims for purposes of the original disclosure and independently of any combination of features in the embodiments and/or claims. are intended to be disclosed separately and independently from each other for purposes of limiting the invention described herein.

The disclosed embodiments should not be considered as limiting the scope of the invention, and features of separate embodiments that perform equivalent or the same function are disclosed within the scope of the amended claims. Can be interchanged between embodiments. Enumeration of a numerical range by endpoints includes all numbers within that range. For example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5.

An embodiment of a hollow structure will be described.

As shown in FIGS. 1 and 2, the hollow structure 10 includes a plate material 11 having a hollow structure and a resin molded part 50. The planar shape of the plate material 11 is, for example, a rectangle. At least a part of the edge of the plate material 11 is integrated with the resin molded part 50. The resin molded part 50 is formed by insert molding the plate material 11 as described later. The hollow structure 10 has a first surface and a second surface opposite to the first surface. The hollow structure 10 has a plurality of recesses 51 arranged at intervals in the resin molded part 50 so as to open on each of the first surface and the second surface. Each recess 51 is, for example, a hole having a circular opening and a bottom.

As shown in FIG. 2, the plate material 11 includes two skin layers 20 and a core layer 30 sandwiched between the two skin layers 20. That is, the plate material 11 is a laminate in which a first skin layer 20, a core layer 30, and a second skin layer 20 are laminated in this order. The plate material 11 has a main body portion 13 having a constant thickness and a connecting portion 14 extending along the edge of the main body portion 13. The thickness S of the resin molded part 50 is substantially equal to the thickness T of the main body part 13.

The connecting portion 14 includes at least one of a proximal portion 21 , a contact portion 22 , and a holding portion 23 . The holding portion 23 is an edge of the plate material 11. The holding portion 23 appears on the outer surface of the resin molded portion 50 so as to sandwich the end (inner edge) of the resin molded portion 50 . The contact part 22 is preferably arranged between the proximal part 21 and the clamping part 23.

Each of the proximal portion 21, the contact portion 22, and the clamping portion 23 extends in a band shape along the resin molded portion 50. The proximal portion 21, the contact portion 22, and the clamping portion 23 may be continuous loops extending all around the outer edge of the main body 13, or may be continuous loops extending along a part of the outer edge of the main body 13. You can.

In the proximal portion 21, at least one of the first and second skin layers 20 is bent so as to be proximate to the other. In the proximal portion 21 of this embodiment, the first and second skin layers 20 are curved in a direction toward each other.

More specifically, the proximal portion 21 includes a first curved surface connected to the outer surface of the main body portion 13, a second curved surface connected to the outer surface of the contact portion 22, and an inclined surface extending between the first and second curved surfaces. and has. The first and second curved surfaces may be curved so as to be convex toward the outside of the plate material 11, or may be curved so as to be concave toward the inside of the plate material 11.

The contact portion 22 is located at a position closer to the outer edge of the plate material 11 than the proximal portion 21, more specifically, at a position adjacent to the resin molded portion 50. That is, the contact portion 22 is located between the resin molded portion 50 and the proximal portion 21 . At the contact portion 22, the first and second skin layers 20 are in contact with the core layer 30. The contact portion 22 may extend all the way around the proximal portion 21 . The contact portion 22 has a third curved surface connected to the outer surface of the proximal portion 21, a fourth curved surface connected to the outer surface of the holding portion 23, and an inclined surface extending between the third and fourth curved surfaces.

The sandwiching part 23 is a part where the resin molded part 50 is sandwiched between two skin layers 20. The holding part 23 may be arranged so as to surround the entire circumference of the contact part 22. The holding portion 23 has a fifth curved surface connected to the outer surface of the contact portion 22 and an inclined surface connected to the fifth curved surface. That is, the proximal portion 21, the contact portion 22, and the clamping portion 23 are smoothly continuous via the curved surface.

In the proximal portion 21, the two skin layers 20 are arranged with a gap between them. This gap, that is, the distance between the two skin layers 20 is in the range of several millimeters (for example, 3 mm) or less.

In the contact portion 22, the core layer 30 sandwiched between the two skin layers 20 is crushed, so the contact portion 22 does not have a hollow structure. The contact portion 22 may be directly adjacent to the resin molded portion 50 with no gap, or may be located at a certain distance from the resin molded portion 50 (for example, by a distance between the skin layer 20 and the resin molded portion 50). or a distance equivalent to the thickness of the main body portion 13).

The skin layer 20 and core layer 30 of the plate material 11 will be explained.

As shown in FIGS. 2 and 3, the core layer 30 of the plate material 11 includes a plurality of cylindrical cells C and a connecting wall 33 extending to connect these cells C. Core layer 30 has a first surface and a second surface. The second surface is the outer surface defined by the connecting wall 33. The plurality of cells C are lined up at predetermined intervals. 2 and 3, the skin layer 20 laminated on the first surface of the core layer 30 is referred to as a first skin layer 20, and the skin layer 20 laminated on the second surface of the core layer 30 is referred to as a second skin layer 20. That's what it means. Each cell C is defined by a disk-shaped end wall 31 and a cylindrical partition wall 32. End wall 31 defines a first surface. The partition wall 32 connects the outer edge of the end wall 31 and the connecting wall 33. Each cell C is open toward the second skin layer 20. The opening of each cell C is closed by the second skin layer 20.

The skin layer 20 and the core layer 30 are made of thermoplastic resin. The thermoplastic resin constituting the skin layer 20 and the core layer 30 is a conventionally well-known thermoplastic resin, and its material is not particularly limited. Examples of thermoplastic resins are polypropylene resins, polyamide resins, polyethylene resins, acrylonitrile-butadiene-styrene copolymer resins, acrylic resins, or polybutylene terephthalate resins. It is preferable that the skin layer 20 and the core layer 30 are made of the same material. The skin layer 20 and core layer 30 of this embodiment are both made of polypropylene resin.

The thickness of the plate material 11 is not particularly limited, but is, for example, 3 mm to 7 mm. The thickness of each of the end wall 31, partition wall 32, and connection wall 33 of the core layer 30 is, for example, 0.1 mm to 0.5 mm. The thickness of the skin layer 20 is, for example, 0.3 mm to 0.6 mm.

A method for manufacturing the hollow structure 10 will be explained.

The method for manufacturing the hollow structure 10 includes a laminate forming step, a positioning step, and an inserting step. In the laminate forming step, a laminate 19 that will become the plate material 11 is formed. In the positioning process, the laminate 19 is positioned prior to the insert process. In the insert process, a resin molded part 50 is molded along the edge of the laminate 19. The laminate forming process can also be performed in advance at a location different from the positioning process and the inserting process, prior to the positioning process and the inserting process.

(Laminated body forming process)
Pull out the first sheet from the first roll sheet. The pulled out first sheet is heated, and while it is in contact with a roll (not shown) having a plurality of cylindrical depressions, the roll is evacuated. As a result, the shapes of the plurality of depressions are transferred to the first sheet. A plurality of cells C are formed in the first sheet by the plurality of depressions. The first sheet having a plurality of cells C becomes the core layer 30.

Next, the second sheet 20 is pulled out from the second roll sheet. The drawn out second sheet is heated and melted, and the melted second sheet 20 is brought into contact with the first surface of the core layer 30 (the end walls 31 of the plurality of cells C) for a predetermined period of time. Thereby, the second sheet 20 is welded to the core layer 30. The second sheet 20 joined to the core layer 30 becomes the first skin layer 20.

Furthermore, the third sheet 20 is pulled out from the third roll sheet. The drawn third sheet 20 is heated and melted, and the melted third sheet 20 is brought into contact with the second surface (connection wall 33) of the core layer 30 for a predetermined period of time. As a result, the third sheet 20 is welded to the core layer 30. The third sheet 20 joined to the core layer 30 becomes the second skin layer 20. Through the above steps, a laminate 19 having a hollow core layer 30 is formed.

The first to third roll sheets may be made of the same material or may be made of different materials. When the first to third roll sheets are made of the same material, at least two of the first to third sheets may be pulled out from one roll sheet. The process of joining the second and third sheets 20 to the core layer 30 may be performed simultaneously or separately.

As shown in FIG. 4A, a mold device 60 for insert molding used in the insert process includes a fixed mold 61 that is a first mold and a movable mold 62 that is a second mold. The molds 61 and 62 have a shape (for example, a rectangle) corresponding to the outer edge of the plate material 11 in plan view.

When viewed in the cross section shown in FIG. 4A, each of the molds 61 and 62 has one or more protruding portions at positions facing each other. When each mold 61, 62 has a plurality of protruding parts, these protruding parts protrude from the same plane within each mold 61, 62.

Each mold 61, 62 has, for example, a first protrusion 63, a second protrusion 64, and a plurality of holding protrusions 65 that protrude from the same plane. The first protruding part 63 and the second protruding part 64 are molds for molding the connecting part 14. A plurality of recesses 51 are formed by the plurality of pressing protrusions 65 .

The first protrusion 63 and the second protrusion 64 extend in a band shape so as to form a continuous loop in plan view. The first protrusion 63 and the second protrusion 64 of this embodiment form a closed rectangular loop in plan view.

Each second protrusion 64 is smoothly continuous with the corresponding first protrusion 63. The protrusion length of each second protrusion 64 is shorter than the protrusion length of the corresponding first protrusion 63. Each first protrusion 63 has a flat top surface for forming the abutting portion 22 . Each first protrusion 63 further has a curved surface that smoothly extends from the top surface toward the inner edge in order to form the proximal portion 21 . Each second protrusion 64 has a curved surface for forming the holding part 23.

The plurality of presser protrusions 65 of each of the molds 61 and 62 are located away from the corresponding first and second protrusions 63 and 64. The protruding lengths of these pressing protrusions 65 are substantially equal to the protruding heights of the corresponding second protrusions 64. Each pressing protrusion 65 has a substantially cylindrical shape. Each pressing protrusion 65 may have a flat end surface for pressing the edge of the laminate 19.

(insert process)
As shown in FIG. 4B, in the insert process, first, the laminate 19 is positioned between the molds 61 and 62. This positioning process will be described later.

Subsequently, the movable mold 62 is moved toward the fixed mold 61. Thereby, the molds 61 and 62 define a molding space P for molding resin between them. At this time, the molds 61 and 62 sandwich the laminate 19 between them.

The portion of the laminate 19 sandwiched between the two first protrusions 63 is crushed. As a result, a proximal portion 21 and a contact portion 22 are formed. The two first protrusions 63 define a molding space P.

When defining the molding space P, the thickness of the gap formed between the two first protrusions 63 is not particularly limited; The thickness dimension can be substantially the same as, or thinner than, the thickness of the material. However, if this gap is too thin, the strength of the plate material 11 will decrease. Therefore, the laminate 19 is preferably crushed to such an extent that the resin does not flow into the core layer 30, that is, to the extent that no gap remains within the core layer 30.

The core layer 30 in the molding space P is compressed by being sandwiched between the second protrusion 64 and the pressing protrusion 65 . In particular, the partition wall 32 buckles more in the portion of the core layer 30 adjacent to the contact portion 22 than in other portions. At this time, the thickness of the laminate 19 inside the molding space P becomes thinner than the thickness of the laminate 19 (main body part 13) outside the molding space P.

As shown in FIG. 4C, the two molds 61 and 62 define a molding space P and, at the same time, define a gate 66 through which molten resin flows. The gate 66 communicates with the molding space P. When looking at a cross section including the gate 66, the presser protrusion 65, and the first protrusion 63 and perpendicular to the edge of the laminate 19, the presser protrusion 65 is connected to the gate 66 in the molding space P. It is located between the first protrusion 63 and closer to the gate 66 than the first protrusion 63 .

The molten resin flows into the molding space P through the gate 66 and flows toward the first protrusion 63 . At this time, the temperature of the molds 61 and 62 is maintained within a certain range by, for example, running water so that it is lower than the temperature of the molten resin. The portion of the laminate 19 disposed in the molding space P includes the portion of the second and third sheets (skin layers) 20 that are in contact with the molds 61 and 62 (including the portion that is in contact with the tip surface of the pressing protrusion 65). ) is melted by the heat of the molten resin. That is, the temperatures of the molds 61, 62 and the molten resin are set so that the portions of the second and third sheets 20 that are in contact with the tip surfaces of the holding projections 65 are not melted by the heat of the molten resin. Ru.

The laminate 19 is held within the molding space P until the injected resin solidifies to some extent. Thereby, the resin molded part 50 is molded in the molding space P along the edge of the laminate 19. Thereafter, the laminate 19 and the resin molded part 50 are removed from the molds 61 and 62. Thereby, the plate material 11 integrated with the inside of the resin molded part 50 is formed.

As shown in FIGS. 1, 2, and 4D, the first protrusion 63 and the second protrusion 64 form the connecting portion 14, that is, the proximal portion 21, the contact portion 22, and the clamping portion 23 on the plate 11. be done.

Specifically, the portion of the plate material 11 sandwiched between the first protrusions 63 becomes the contact portion 22 . A proximal portion 21 is formed at a position adjacent to the contact portion 22 . In the contact portion 22, one or more layers may be irregularly folded over each other, resulting in a gap partially occurring.

The width of the strip-shaped contact portion 22 is not particularly limited. However, if the width of the contact portion 22 is wide, the strength may decrease and the resin molded portion 50 may sag due to its own weight. Therefore, it is better that the width of the contact portion 22 is narrower. For example, the width of the contact portion 22 may be narrower than the width of the resin molded portion 50, the thickness of the main body portion 13, or the width (diameter) of the recessed portion 51.

The resin molded part 50 has a plurality of recesses 51 that are the remains of the plurality of holding protrusions 65 removed. The second and third sheets 20 remaining unmelted in the molding space P are exposed at the bottom of each recess 51, that is, at the portion where the tip end surface of the pressing protrusion 65 was in contact.

Next, a positioning process for positioning the laminate 19 within the mold device 60 will be described.

Prior to the positioning step, as shown in FIG. 5A, a plurality of positioning through holes 12 are formed in the laminate 19 along its outer edge.

As shown in FIG. 5B, the fixed mold 61 has a plurality of positioning convex portions 67 that protrude into the molding space P. The laminate 19 is positioned within the fixed mold 61 by inserting the corresponding positioning convex portion 67 into each positioning through hole 12 of the laminate 19 . The position and number of the positioning through hole 12 and the positioning convex portion 67 can be changed as appropriate. After this positioning, the movable mold 62 is moved toward the fixed mold 61.

As shown in FIG. 5C, the molten resin is allowed to flow into the molding space P with the stacked body 19 positioned. A hole is formed in the resin molded part 50, which is the mark where the positioning convex part 67 was removed. The melted and solidified resin is exposed at the bottom of this hole.

Through the above manufacturing process, the hollow structure 10 having the plate material 11 and the resin molded part 50 is obtained.

The hollow structure 10 can be used for any purpose. The plurality of cells C are not limited to a cylindrical shape, and may be, for example, a conical shape, a prefixed conical shape, a shape in which the prefixes of conical prefixed shapes are combined, a triangular prism shape, or a harmonica shape. Since the hollow structure 10 has a hollow structure including a plurality of cells C, it is lightweight and has excellent heat insulation properties. The hollow structure 10 can be suitably used in applications requiring these characteristics. Further, since the hollow structure 10 includes the resin molded portion 50, it is lightweight and strong, and the hollow portion is sealed. Therefore, it has a heat insulating effect and a water stopping effect. Therefore, the hollow structure 10 can be used, for example, as a folding container for transporting food.

The operation and effects of this embodiment will be explained.

(1) The distance between the two skin layers 20 in the proximal portion 21 is shorter than the distance between the two skin layers 20 in the main body portion 13. Therefore, during insert molding, it is possible to suppress the molten resin from flowing into the inside of the plate material 11 (laminate 19), that is, between the two skin layers 20. If the molten resin flows into the inside of the plate material 11, there may be a shortage of resin to form the resin molded portion 50, and unintended irregularities may occur in the resin molded portion 50. In this regard, in this embodiment, by suppressing the flow of resin into the plate material 11, the hollow structure 10 can be reduced in weight while forming the resin molded part 50 suitably.

(2) In the proximal portion 21, both of the two skin layers 20 are curved in a direction toward each other. This makes it possible to prevent stress from concentrating on one skin layer 20 compared to the case where only one of the two skin layers 20 is curved in a direction approaching the other skin layer 20.

(3) The thickness S of the resin molded part 50 is equal to the thickness T of the main body part 13. Therefore, compared to the case where the resin molded part 50 is thicker than the plate material 11, the plurality of hollow structures 10 can be stacked without gaps.

(4) At the contact portion 22, there is almost no gap between the two skin layers 20. Therefore, it is possible to more effectively suppress the molten resin from flowing into the inside of the plate material 11, that is, between the two skin layers 20 during insert molding.

(5) By integrating the edges of the plate material 11 with the resin molded part 50, the edges of the hollow structure plate material 11 can be sealed. This can prevent foreign matter, such as water, liquid, dust, or dirt, from entering the inside of the plate 11.

(6) The resin molded part 50 has a plurality of recesses 51 arranged in the longitudinal direction. These recesses 51 are marks left when the laminate 19 is pressed by the pressing protrusion 65 during insert molding. This pressing suppresses the skin layer 20 from coming out from the resin molded part 50 during insert molding. Thereby, the melted and integrated resin appears on the surface of the resin molded part 50, so that the aesthetic appearance is maintained.

(7) Since the holding portions 23 sandwich the edges of the resin molded portion 50, the boundary between the plate material 11 and the resin molded portion 50 can be defined by the skin layer 20 (second and third sheets 20).

This embodiment can be modified and implemented as follows. The configurations included in this embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

- In this embodiment, only one of the two skin layers 20 may be curved in the direction approaching the other in the proximal portion 21. Further, in the proximal portion 21 , the skin layer 20 may extend linearly so as to be inclined with respect to the main body portion 13 . That is, the proximal part 21 and the abutting part 22 do not have curved surfaces, and the proximal part 21, which is a flat slope, and the main body part 13 and the abutting part 22, which are flat, intersect to form an angle. You can.

- In the contact portion 22, the core layer 30 does not need to be sandwiched between the two skin layers 20. For example, due to the heat of the resin injected in the insert process, the boundary between the two skin layers 20 and the core layer 30 disappears, and the two skin layers 20 come into direct contact with each other, or the first to third sheets Sometimes they become integrated.

- The hollow structure 10 does not need to include the contact portion 22.

- The proximal portion 21 and the contact portion 22 may extend linearly along the edge of the plate material 11, or may extend curved like a wave.

- The thickness S of the resin molded part 50 may be thinner than the thickness T of the main body part 13, or may be thicker than the thickness T.

- An arbitrary region of the plate material 11 may be embedded in the resin molded part 50, or the entire plate material 11 may be embedded in the resin molded part 50. When embedding the entire plate material 11 (laminated body 19) with the resin molded part 50, after crushing the edge of the laminated body 19 to form the proximal part 21 (and contact part 22), the laminated body 19 is buried. The resin molding portion 50 may be placed in the mold device 60 and insert molded therein.

- The edge of the plate material 11 is not limited to the outer edge of the plate material 11. For example, when the plate material 11 has a through hole penetrating in the thickness direction thereof, the periphery of this through hole becomes the edge of the plate material 11. In this case, it is preferable to mold the resin molded part 50 along the periphery of the through hole, or to arrange a proximal part along the periphery of the through hole. Such a through hole can be used as a handle of the plate material 11, for example.

- The mold device 60 for insert molding may have a suction port instead of the positioning convex portion 67. In this case, the laminate 19 placed in the mold device 60 can be positioned within the mold device 60 by suctioning the laminate 19 from the suction port.

- The arrangement of the fixed mold 61 and the movable mold 62 may be changed. For example, the movable mold 62 may be placed below the laminate 19, and the fixed mold 61 may be placed above the laminate 19. Alternatively, the fixed mold 61 and the movable mold 62 may sandwich the stacked body 19 from the left and right sides. Furthermore, the movable mold 62 may have a positioning convex portion 67.

- The shape of the holding protrusion 65 can be changed. For example, the holding protrusion 65 may be prismatic or conical. Further, the holding protrusion 65 may be continuous with the second protrusion 64. Alternatively, at least one of the molds 61 and 62 may be provided with a through hole, and a pressing member inserted through the through hole may be used as the pressing protrusion 65.

- At least one of the molds 61 and 62 does not need to have at least one of the second protrusion 64 and the pressing protrusion 65. For example, when neither of the molds 61 and 62 has the pressing protrusion 65, the plurality of recesses 51 are not formed in the resin molded part 50. Only one of the molds 61 and 62 may have the pressing protrusion 65. In this case, the recess 51 is formed only on either the first surface or the second surface of the hollow structure 10.

- At least one of the molds 61 and 62 does not need to have the first protrusion 63. For example, when one of the molds 61 and 62 has a first protrusion 63 that protrudes toward the other, "the gap formed between the two first protrusions 63" is defined as "the first protrusion 63 is the gap formed between the mold and the other mold.

- The skin layer 20 and the core layer 30 may be made of different materials, and in particular, different types of thermoplastic resins may be used. For example, if the outer edge of the PP plate is integrated with an elastomeric resin molded part, the impact absorption effect can be improved. Therefore, even if the hollow structure 10 is dropped, it can be made less likely to be damaged.

- The method of forming the plate material 11 (laminated body 19) can be changed. For example, the two skin layers 20 and core layer 30 may be joined via an adhesive layer. The core layer 30 may have a plurality of cells C having a honeycomb structure, for example, as in the first and second modified examples (see FIGS. 6 to 12).

- The planar shape of the plate material 11 can be deformed. For example, the planar shape of the plate material 11 may be circular or elliptical. Further, the plate material 11 may not be a flat plate but may be a partially or entirely curved plate. Furthermore, the resin molded portion 50 may also have a three-dimensional shape along the plate material 11. In this case, the hollow structure 10 can be made into a three-dimensional shape.

- The resin molded part 50 may include a rotation shaft or a bearing for the rotation shaft for rotating the hollow structure 10. In this case, the hollow structure 10 can be used as a side plate of a folding container. Further, the resin molded part 50 may include a fastening part, such as a hook, for attaching to another member. In this case, the strength of the hollow structure 10 as a whole may be improved by integrating the hollow structure 10 with another component, such as a stronger member, via the fastening portion.

- The resin molded part 50 may be a closed loop extending over the entire edge of the plate material 11, or may be an open loop extending along a part of the edge of the plate material 11.

- The plate material 11 and the resin molded part 50 may be of the same color or may be of different colors. Even if the plate material 11 and the resin molded part 50 have different colors, only the bottom of the recess 51 remains without the first to third sheets in the molding space P melting. Since the skin layer 20 (second and third sheets 20) is not exposed on the surface of the resin molded part 50, the appearance is beautiful.

- The core layer 30 (first sheet) may remain undissolved near the boundary between the contact portion 22 and the holding portion 23. The contact portion 22 may include a multilayered portion in which the first sheet is folded so that a plurality of cells C are crushed. Some of these first sheets may not directly touch the injected resin. A portion of the first sheet is not melted by the heat of the molten resin, but is pushed toward the contact portion 22 and remains melted near the contact portion 22. In this case, the melted resin does not reach the contact portion 22. Therefore, when the core layer 30 includes a plurality of layers, the effect of suppressing the resin from flowing into the plate material 11 is high. Since the unmelted core layer 30 (first sheet) is sandwiched between the second and third sheets 20 in the sandwiching portion 23, it is difficult to visually recognize it from the outside. That is, by sandwiching the edge of the resin molded part 50 between the two skin layers 20 (second and third sheets 20), the unmelted core layer 30 can be hidden. Thereby, it is possible to form a clear boundary between the plate material 11 and the resin molded portion 50 while suppressing the inflow of resin into the plate material 11. Therefore, even if the color of the plate material 11 is different from the color of the resin molded part 50, the boundary between the two is unlikely to be disturbed.

- The thickness of the contact part 22, that is, the thickness of the gap between the two first protrusions 63 when defining the molding space P, is the thickness of the first sheet before molding and the second and third sheets 20 stacked together. It may be thinner than the original thickness. In this case, since the contact portion 22 does not have a hollow structure, it is possible to suppress the resin from flowing into the interior of the main body portion 13 . The thickness of the contact portion 22 may be thinner than the thickness of the two skin layers 20 and the partition wall 32 of the core layer 30 stacked together. The partition wall 32 is thinner than the first sheet, the end wall 31, and the connecting wall 33 because it is stretched when the first sheet is vacuumed.

- The core layer 30 may have a honeycomb structure as in the first modification shown in FIGS. 6 to 8. The core layer 30 of the first modification is formed by folding the first sheet 100 molded by a molding die shown in FIG. 7 as shown in FIG. 8 . The first sheet 100 can be formed by a vacuum forming method that utilizes the plasticity of the sheet.

As shown in FIG. 7, the first sheet 100 has a plurality of first bulges 110 and a plurality of second bulges 120. The bulges 110 and 120 extend in a band shape in the X direction. The first bulging portions 110 and the second bulging portions 120 are arranged alternately in the Y direction perpendicular to the X direction. The first bulging portion 110 and the second bulging portion 120 bulge in opposite directions. The first bulging portion 110 and the second bulging portion 120 are located at positions shifted by 1/2 pitch from each other in the X direction.

The first bulging portion 110 has a first bulging surface 110a, a pair of connecting surfaces 110b, and a pair of end surfaces 110c. The first bulging portion 110 has a trapezoidal cross section in the Y direction obtained by dividing a regular hexagon into two by the longest diagonal line. The pair of end surfaces 110c are located at the folding line R. The angle between the end surface 110c and the first bulging surface 110a is approximately 90 degrees.

The second bulging portion 120 has a second bulging surface 120a, a pair of connecting surfaces 120b, and a pair of end surfaces 120c. The second bulging portion 120 has a trapezoidal shape in cross section in the Y direction obtained by dividing a regular hexagon into two by the longest diagonal line. The pair of end surfaces 120c are located at the folding line Q. The angle between the end surface 120c and the second bulging surface 120a is approximately 90 degrees. The length of the second bulging portion 120 in the X direction, that is, the length between the pair of end surfaces 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 surfaces 110c. be. The end surface 120c of the second bulge 120 is located at the center of the first bulge 110 in the X direction. Although the connecting surface 110b of the first bulging portion 110 and the connecting surface 120b of the second bulging portion 120 are separated for convenience of explanation, they have the same configuration.

The first sheet 100 shown in FIG. 7 is sequentially folded along folding lines R and Q. The first sheet 100 is mountain-folded along the folding line R and valley-folded along the folding line Q.

Looking at one first bulge 110, it is valley-folded at the folding line Q located at the center in the X direction, and the first bulge surface 110a on the right side in the X direction and the first bulge surface 110a on the left side in the X direction are mutually connected. come into contact with The folded first bulging portion 110 has a partition wall 32a in which the two first bulging surfaces 110a in contact with each other form a two-layer structure, and a partition wall 32b in which the connecting surface 110b forms a one-layer structure. . The two adjacent end surfaces 110c are lined up flush and form the first wall 34.

Looking at one second bulge 120, by being mountain-folded at the folding line R located at the center of the two adjacent folding lines Q in the X direction, the second bulging surface 120a on the right side in the X direction and the second bulging surface 120a on the right side in the X direction The left second bulging surface 120a abuts against each other. The folded second bulging portion 120 has a partition wall 32 (32a) in which the two second bulging surfaces 120a in contact with each other form a two-layer structure, and a partition wall 32 in which the connecting surface 120b forms a one-layer structure. (32b). The two adjacent end surfaces 120c are lined up flush and form the second wall 35. The partition walls 32a having a two-layer structure may be joined to each other.

- As shown in FIG. 6, when the laminate 19 of the first modification is sandwiched between the molds 61 and 62, the two skin layers 20 and the core layer 30 are separated between the two first protrusions 63. is crushed. As a result, the contact portion 22 includes, in addition to the two skin layers 20, some or all of the partition walls 32 (32a, 32b), the first wall 34, and the second wall 35. In this way, when the core layer 30 includes a plurality of layers, the effect of suppressing the resin from flowing into the main body portion 13 is high, as described above. In particular, the partition wall 32a having a two-layer structure can more effectively suppress the resin from flowing into the main body portion 13.

- The core layer 30 may be modified to have a honeycomb structure, as in the second modified example shown in FIGS. 9 to 12. The core layer 30 of the second modification example is formed by folding the first sheet 200 molded by a molding die shown in FIG. 10 as shown in FIGS. 11 and 12.

As shown in FIG. 10, plane areas 210 and bulging areas 220 are alternately arranged in the longitudinal direction (X direction) of the first sheet 200. Both the flat area 210 and the bulging area 220 extend along the Y direction. The bulging region 220 includes a reference surface 201 that is flush with the plane region 210, and a first bulging portion 221 that bulges out from the reference surface 201 in the Z direction and extends over the entire bulge region 220 in the Y direction. The first bulging portion 221 has a first bulging surface 202 that bulges out from the reference surface 201 in the Z direction, and a connecting surface 203 that extends from the reference surface 201 toward the first bulging surface 202 . The angle between the first bulging surface 202 and the connecting surface 203 is 90°. The length of the first bulging portion 221 in the X direction is equal to the length of the plane region 210 in the X direction, and is twice the bulging height of the first bulging portion 221 .

The bulging region 220 includes a plurality of second bulges 222 that are integrally formed with a first bulge 221 . The second bulges 222 extend in opposite directions on both sides of the first bulge 221 and are arranged in the Y direction. Each second bulging portion 222 includes a second bulging surface 204 bulging from the reference surface 201 , two inclined surfaces 205 extending diagonally from the reference surface 201 to the second bulging surface 204 , and a second bulging surface 204 and a second bulging surface 204 . It has an end surface 206 that intersects with two inclined surfaces 205. The second bulging surface 204 is flush with the first bulging surface 202 . Each second bulging surface 204 extends in the X direction so as to be perpendicular to the first bulging surface 202 extending in the Y direction. A cross section of each second bulging portion 222 taken along a plane perpendicular to the X direction is a trapezoid obtained by dividing a regular hexagon into two by the longest diagonal line. The height of the second bulge 222 is equal to the height of the first bulge 221 . Further, the interval between the second bulges 222 arranged in the Y direction is equal to the width of the second bulge surface 204.

As shown in FIGS. 11 and 12, the first sheet 200 is folded along folding lines R and Q. Specifically, the first sheet 200 is valley-folded along the folding line R between the plane region 210 and the bulging region 220, and the first bulging surface 202 and the connecting surface 203 of the first bulging portion 221 are folded. It folds in a mountain along line Q and contracts in the X direction. Then, the first bulging surface 202 and the connecting surface 203 of the first bulging part 221 overlap, and the end surface 206 of the second bulging part 222 and the plane area 210 overlap, so that one bulging area 220 A prismatic partition body 230 extending in the Y direction is formed. By continuously forming such partitions 230 in the X direction, a hollow plate-shaped core layer 30 is formed.

The core layer 30 of the second modification has a first wall 36 formed by the first bulging surface 202 and the connection surface 203, and a second wall 37 formed by the end surface 206 and the plane region 210. The cell C of the second modified example includes a first cell C1 and a second cell C2. The first cell C1 is a hexagonal column-shaped area defined between two adjacent partition bodies 230. The second cell C2 is a hexagonal column-shaped area defined by folding the second bulging portion 222. The inclined surface 205 and the reference surface 201 become the partition wall 32 of the first cell C1. The second bulging surface 204 and the inclined surface 205 become the partition wall 32 of the second cell C2. The partition wall 32 formed by the contact portions of the second bulging surfaces 204 and the contact portions of the reference surfaces 201 has a two-layer structure.

- As shown in FIG. 9, when the laminate 19 of the second modification is sandwiched between the two first protrusions 63, the two skin layers 20 and the core layer 30 are crushed. In this case, the contact portion 22 includes a plurality of layers constituting a core layer 30 in addition to the two skin layers 20 . In this way, when the core layer 30 includes a plurality of layers, the effect of suppressing the resin from flowing into the plate material 11 is high. In particular, since the partition wall 32 formed by folding the first sheet 200 includes a two-layer structure, it is possible to more effectively suppress the resin from flowing into the plate material 11.

- As shown in the modified example of FIGS. 6 and 9, the plurality of pressing protrusions 65 may be arranged near the outer edge of the laminate 19 sandwiched between the molds 61 and 62. In this case, the recess 51 is formed at a position in contact with the outer edge of the resin molded part 50 or near the outer edge. In other words, the resin molded part 50 has an inner edge connected to the plate material 11 and an outer edge opposite to the inner edge, and the plurality of recesses 51 are located closer to the outer edge than the inner edge of the resin molded part 50. Good too.

When the second protrusion 64 and the pressing protrusion 65 press the laminate 19, the outer edges of the two skin layers 20 may be bent away from each other. When the skin layer 20 bent in this manner comes into contact with the molds 61 and 62, the contact portions may remain irregularly melted. If the skin layer 20 that remains undissolved irregularly appears on the surface of the resin molded part 50, the aesthetic appearance of the hollow structure 10 may be impaired. In this regard, when the pressing protrusion 65 presses the outer edge or the vicinity of the outer edge of the laminate 19, bending of the skin layer 20 can be suppressed.

- The protruding length of the holding protrusion 65, ie, the depth of the recess 51, can be changed. For example, the protruding length of the pressing protrusion 65 (the depth of the recess 51) may be the same as or longer than the thickness of one skin layer 20.

- As shown in the modified example of FIGS. 6 and 9, with the laminate 19 positioned in the mold device 60, from the outer edge (left edge in FIG. 9) of each presser protrusion 65 to the outside (in FIG. 9) The protruding length of each pressing protrusion 65 (the depth of the recess 51) may be longer than the length of the second and third sheets 20 (skin layer 20) extending in the left direction. In this case, even if the second and third sheets 20 pressed by the pressing projections 65 are bent or the bent portions remain unmelted, the second and third sheets 20 will not be exposed on the surface of the resin molded part 50. .

- The maximum length (diameter) of the tip surface of the holding projection 65, that is, the opening length (diameter) of the recess 51, can be changed. For example, the diameter of the pressing protrusion 65 (the diameter of the recess 51) may be longer than the diameter of the cell C (in the case of a honeycomb structure, the longest diagonal of a regular hexagon).

When the first sheet is folded to form the honeycomb-structured core layer 30 as in the first and second modified examples, the hexagonal column shape of the plurality of cells C may be partially distorted or the cells may not be arranged in a straight line. Sometimes. Therefore, the first protrusion 63, the second protrusion 64, and the presser protrusion 65 of each of the molds 61 and 62 may press the area where the partition wall 32 is not uniformly arranged.

Claims (8)

A hollow structure, the hollow structure comprising:
A plate material having a hollow structure, which is a laminate in which a first skin layer, a core layer, and a second skin layer are laminated in this order;
a resin molded part arranged along the edge of the plate material;
Equipped with
The resin molded part is
an inner edge connected to the plate;
an outer edge opposite the inner edge;
a plurality of recesses lined up along the edge of the plate material, the plurality of recesses being located closer to the outer edge than the inner edge of the resin molded part;
The plate material is
A main body portion with a constant thickness,
a proximal portion extending along the resin molded portion ;
a connecting portion disposed between the main body portion and the resin molded portion, the connecting portion including the proximal portion;
a contact portion between the resin molded portion and the proximal portion, where the first and second skin layers abut against the core layer;
a clamping part appearing on the outer surface of the resin molding part so as to sandwich an edge of the resin molding part, the clamping part being located between the resin molding part and the proximal part;
The thickness of the resin molded part is equal to or thinner than the thickness of the main body part,
In the proximal portion, the first and second skin layers are curved toward each other ;
The core layer has a hollow structure formed by molding a first sheet to have a plurality of cells,
The first and second skin layers are second and third sheets respectively bonded to both sides of the core layer,
The second or third sheet is exposed at the bottom of the recess,
The contact portion includes a portion where the first sheet is folded so that the plurality of cells are crushed,
The thickness of the contact portion is thinner than the thickness when the first sheet before molding and the second and third sheets are laminated.
hollow structure. A hollow structure, the hollow structure comprising:
A plate material having a hollow structure, which is a laminate in which a first skin layer, a core layer, and a second skin layer are laminated in this order;
a resin molded part disposed along an edge of the plate material, the resin molded part having a plurality of recesses lined up along the edge of the plate material;
Equipped with
The plate material is
a proximal portion extending along the resin molded portion;
a contact part between the resin molded part and the proximal part, in which the first and second skin layers contact the core layer;
In the proximal portion, the first and second skin layers are curved toward each other;
The core layer has a hollow structure formed by molding a first sheet to have a plurality of cells,
The first and second skin layers are second and third sheets respectively bonded to both sides of the core layer,
The second or third sheet is exposed at the bottom of the recess,
The contact portion includes a portion where the first sheet is folded so that the plurality of cells are crushed,
The thickness of the contact portion is thinner than the thickness when the first sheet before molding and the second and third sheets are laminated,
The depth of the recessed portion is shallower than the adjacent portion and is greater than or equal to the thickness of the first and second skin layers.
hollow structure. A method for manufacturing a hollow structure, the hollow structure comprising:
A plate material having a hollow structure, which is a laminate in which a first skin layer, a core layer, and a second skin layer are laminated in this order;
a resin molded part arranged along the edge of the plate material;
Equipped with
The resin molded part is
an inner edge connected to the plate;
an outer edge opposite the inner edge;
a plurality of recesses lined up along the edge of the plate material, the plurality of recesses being located closer to the outer edge than the inner edge of the resin molded part;
The plate material is
A main body portion with a constant thickness,
a proximal portion extending along the resin molded portion;
a connecting portion disposed between the main body portion and the resin molded portion, the connecting portion including the proximal portion;
a contact portion between the resin molded portion and the proximal portion, where the first and second skin layers abut against the core layer;
a clamping part appearing on the outer surface of the resin molding part so as to sandwich an edge of the resin molding part, the clamping part being located between the resin molding part and the proximal part;
The thickness of the resin molded part is equal to or thinner than the thickness of the main body part,
The manufacturing method includes:
forming the plate-shaped core layer having the plurality of cells by molding a first sheet;
forming a laminate having a hollow structure by bonding a second sheet and a third sheet to both sides of the core layer, respectively;
sandwiching the laminate between a first mold and a second mold to define a molding space between the first mold and the second mold along an edge of the laminate;
Injecting molten resin into the molding space;
Solidifying the molten resin in the molding space and molding the resin molded part along the edge;
including;
Each of the first mold and the second mold has a first protrusion and a second protrusion that define the molding space at positions facing each other,
The protrusion length of the second protrusion is shorter than the protrusion length of the corresponding first protrusion,
The first protruding portion has a flat top surface for forming the abutting portion, and a curved surface extending smoothly from the top surface toward an inner edge so as to form the proximal portion,
The second protrusion has a curved surface for forming the holding part,
The thickness of the gap formed between the first protruding part of the first mold and the first protruding part of the second mold is the same as that of the first sheet before molding and the second and third sheets. Thinner than the thickness of laminated sheets,
Defining the molding space includes crushing the core layer located between the first protrusion of the first mold and the first protrusion of the second mold,
At least one of the first mold and the second mold has a plurality of pressing protrusions that protrude into the molding space so as to mold the plurality of recesses,
In the manufacturing method, each of the pressing protrusions has a tip end surface for pressing the edge of the laminate. A method for manufacturing a hollow structure, the method comprising:
Molding the first sheet to form a plate-shaped core layer having a plurality of cells;
forming a laminate having a hollow structure by bonding a second sheet and a third sheet to both sides of the core layer, respectively;
sandwiching the laminate between a first mold and a second mold to define a molding space between the first mold and the second mold along an edge of the laminate;
Injecting molten resin into the molding space;
Solidifying the molten resin in the molding space and molding a resin molded part along the edge;
including;
Each of the first mold and the second mold has a first protrusion defining the molding space at a position facing each other,
The first protrusion has a flat top surface and a curved surface that smoothly extends from the top surface toward an inner edge,
The thickness of the gap formed between the first protruding part of the first mold and the first protruding part of the second mold is the same as that of the first sheet before molding and the second and third sheets. Thinner than the thickness of laminated sheets,
Defining the molding space includes crushing the core layer located between the first protrusion of the first mold and the first protrusion of the second mold,
At least one of the first mold and the second mold has a plurality of pressing protrusions that protrude into the molding space so as to mold a plurality of recesses lined up along the edge in the resin molded part. has
The protrusion length of the pressing protrusion is shorter than the protrusion length of the first protrusion, and is greater than or equal to the thickness of the second sheet and the thickness of the third sheet,
The manufacturing method, wherein the pressing protrusion has a tip end surface for pressing the edge of the laminate. The first mold when the molten resin is caused to flow into the molding space so that the portions of the second sheet and the third sheet that are in contact with the tip surface are not melted by the heat of the molten resin. and the temperature of the second mold is set lower than the temperature of the molten resin,
The manufacturing method according to claim 3 or 4 . The protrusion length of the pressing protrusion is longer than the thickness of the second sheet and the thickness of the third sheet.
The manufacturing method according to claim 3 . The core layer includes:
a first wall in contact with the second sheet;
a second wall in contact with the third sheet;
A plurality of partition walls extending between the first wall and the second wall and defining the plurality of cells,
At least some of the plurality of partition walls have a two-layer structure,
Defining the molding space means that the first protrusion of the first mold and the first protrusion of the second mold crush the partition wall of the two-layer structure located between them. including,
The manufacturing method according to any one of claims 3 to 6 . Defining the molding space includes the first mold and the second mold defining a gate through which the molten resin flows,
When looking at a cross section including the gate, the presser protrusion, and the first protrusion, the presser protrusion is located between the gate and the first protrusion within the molding space, and disposed at a position closer to the gate than the first protrusion;
The manufacturing method according to any one of claims 3 to 7 .

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