JPWO2020129984A1 - Hollow structure and manufacturing method of hollow structure - Google Patents

Abstract

The hollow structure is a plate material having a hollow structure, and is arranged along the edge of the plate material, which is a laminated body in which the first skin layer, the core layer, and the second skin layer are laminated in this order. It is provided with a resin molded portion. The plate material has a proximity portion extending along the resin molding portion. At the proximity portion, at least one of the first and second skin layers is bent so as to be close to the other.

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. 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 of joining the plastic cardboard 73 to the outer frame 72.

Japanese Unexamined Patent Publication No. 2001-180669

When the outer frame 72 is insert-molded, the injected resin may flow into the inside of the plastic cardboard 73. If the resin flows excessively into the plastic cardboard 73, the amount of the resin required for molding the outer frame 72 may be insufficient. Then, a part of the outer frame 72 may have a poor shape, or the weight of the hollow plate 71 may become heavier than a predetermined weight.

An object of the present disclosure is to provide a lightweight hollow structure in which a resin molded portion is preferably formed and a method for producing the same.

The hollow structure according to one aspect of the present disclosure is a plate material having a hollow structure, which is a laminated body in which a first skin layer, a core layer, and a second skin layer are laminated in this order, and the plate material. It is provided with a resin molded portion arranged along the edge of the. The plate material has a proximity portion extending along the resin molding portion. At the proximity portion, at least one of the first and second skin layers is bent so as to be close to the other.

The method for producing a hollow structure according to one aspect of the present disclosure is to form a plate-shaped core layer having a plurality of cells by molding a first sheet, and to form a plate-shaped core layer having a plurality of cells, and to form a second sheet and a second sheet on both sides of the core layer, respectively. The three sheets are joined to form a laminated body having a hollow structure, and the laminated body is sandwiched between the first mold and the second mold, and is sandwiched between the first mold and the second mold. To define a molding space along the edge of the laminate, to allow the molten resin to flow into the molding space, and to solidify the molten resin in the molding space to solidify the molten resin to form the edge. Including molding a resin molding portion along the above. At least one of the first mold and the second mold has a pressing protrusion that protrudes into the molding space, and the pressing protrusion is a tip surface for pressing the end edge of the laminated body. Has.

The perspective view of the hollow structure which concerns on embodiment. FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. An exploded perspective view of a plate material included in the hollow structure of FIG. FIG. 3 is a cross-sectional view of a mold device and a laminate for insert molding. FIG. 4 is a cross-sectional view showing a state in which the laminated body is sandwiched between the mold devices of FIG. 4A. FIG. 4B is a cross-sectional view showing a state in which resin has flowed into the mold apparatus of FIG. 4B. The plan view which shows a part of the hollow structure of FIG. FIG. 6 is a cross-sectional view showing a through hole for positioning included in the laminated body of FIG. 4A. FIG. 5A is a cross-sectional view showing a part of a laminated body positioned in the mold apparatus through the positioning through hole of FIG. 5A. FIG. 5B is a cross-sectional view showing a state in which resin has flowed into the mold apparatus of FIG. 5B. FIG. 3 is a cross-sectional view of a mold apparatus and a laminated body according to the first modification. The perspective view which shows the state in the process of folding the molded 1st sheet of the 1st modification example. The perspective view of the core layer of the 1st modification example. The cross-sectional view of the mold apparatus and the laminated body which concerns on the 2nd modification example. The perspective view of the molded 1st sheet of the 2nd modification example. FIG. 3 is a perspective view showing a state in which the first sheet of FIG. 10 is being folded. The perspective view of the core layer of the 2nd modification example. The figure which shows a typical hollow structure.

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

All features disclosed in the specification and / or claims are the scope of the claims for the purposes of the original disclosure and independently of the combination of features in the embodiments and / or claims. It is intended to be disclosed separately and independently of each other for the purpose of limiting the inventions described in.

The disclosed embodiments should not be considered as limiting the scope of the invention, and features of equivalent or separate embodiments performing the same function are disclosed within the amended claims. It can be exchanged between embodiments. The enumeration of numerical ranges by endpoints includes all numbers within that range. For example, 1 to 5 include 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5.

An embodiment of the hollow structure will be described.

As shown in FIGS. 1 and 2, the hollow structure 10 includes a plate member 11 having a hollow structure and a resin molding portion 50. The planar shape of the plate member 11 is, for example, a rectangle. At least a part of the edge of the plate material 11 is integrated with the resin molding portion 50. The resin molding portion 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 portion 50 so as to open on each of the first surface and the second surface. Each recess 51 is, for example, a hole that both have 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 laminated body in which the first skin layer 20, the core layer 30, and the second skin layer 20 are laminated in this order. The plate member 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 portion 50 is substantially equal to the thickness T of the main body portion 13.

The connecting portion 14 includes at least one of a proximity portion 21, a contact portion 22, and a holding portion 23. The sandwiching portion 23 is an edge of the plate member 11. The sandwiching portion 23 appears on the outer surface of the resin molding portion 50 so as to sandwich the end (inner edge) of the resin molding portion 50. The contact portion 22 may be arranged between the proximity portion 21 and the sandwiching portion 23.

Each of the proximity portion 21, the contact portion 22, and the sandwiching portion 23 extends in a strip shape along the resin molding portion 50. The proximity portion 21, the contact portion 22, and the sandwiching portion 23 may be a continuous loop extending over the entire circumference of the outer edge of the main body portion 13, or may extend along a part of the outer edge of the main body portion 13. You may.

At the proximity portion 21, at least one of the first and second skin layers 20 is bent so as to be close to the other. In the proximity portion 21 of the present embodiment, the first and second skin layers 20 are curved in a direction approaching each other.

More specifically, the proximity portion 21 is an inclined surface extending between the first curved surface connected to the outer surface of the main body portion 13, the second curved surface connected to the outer surface of the contact portion 22, and the first and second curved surfaces. And have. 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 recessed toward the inside of the plate material 11.

The contact portion 22 is located closer to the outer edge of the plate member 11 than the proximity portion 21, and more specifically, at a position adjacent to the resin molding portion 50. That is, the contact portion 22 is located between the resin molding portion 50 and the proximity portion 21. In 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 over the entire circumference of the proximity portion 21. The contact portion 22 has a third curved surface connected to the outer surface of the proximity 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 portion 23 is a portion in which the resin molding portion 50 is sandwiched between the two skin layers 20. The sandwiching portion 23 may be arranged so as to surround the entire circumference of the contact portion 22. The sandwiching 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 proximity portion 21, the contact portion 22, and the sandwiching portion 23 are smoothly continuous with each other via the curved surface.

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

In the abutting portion 22, since the core layer 30 sandwiched between the two skin layers 20 is crushed, the abutting portion 22 does not have a hollow structure. The abutting portion 22 may be directly adjacent to the resin molding portion 50 so as not to have a gap, or may be slightly separated from the resin molding portion 50 (for example, the skin layer 20 in the main body portion 13). It may be arranged with a distance corresponding to the thickness of the main body 13 or a distance corresponding to the thickness of the main body 13.

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

As shown in FIGS. 2 and 3, the core layer 30 of the plate material 11 includes a plurality of columnar cells C and a connecting wall 33 extending so as to connect the cells C. The core layer 30 has a first surface and a second surface. The second surface is an outer surface defined by the connecting wall 33. The plurality of cells C are arranged at predetermined intervals. In FIGS. 2 and 3, the skin layer 20 laminated on the first surface of the core layer 30 is referred to as the first skin layer 20, and the skin layer 20 laminated on the second surface of the core layer 30 is referred to as the second skin layer 20. That is. Each cell C is defined by a disc-shaped end wall 31 and a cylindrical partition wall 32. The end wall 31 defines the 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 a thermoplastic resin. The thermoplastic resin constituting the skin layer 20 and the core layer 30 is conventionally known, and the material thereof 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. The skin layer 20 and the core layer 30 are preferably made of the same material. The skin layer 20 and the core layer 30 of the present 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, the partition wall 32, and the connecting 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 described.

The method for manufacturing the hollow structure 10 includes a laminate forming step, a positioning step, and an insert step. In the laminate forming step, the laminate 19 to be the plate material 11 is formed. In the positioning step, the laminated body 19 is positioned prior to the insert step. In the insert step, the resin molding portion 50 is molded along the edge of the laminated body 19. The laminate forming step may be performed in advance at a place different from the positioning step and the insert step prior to the positioning step and the insert step.

(Laminate body forming process)
Pull out the first sheet from the first roll sheet. The drawn first sheet is heated and evacuated to the roll in a state of being in contact with a roll having a plurality of columnar recesses (not shown). As a result, the shapes of the plurality of recesses are transferred to the first sheet. Due to the plurality of depressions, a plurality of cells C are formed on the first sheet. The first sheet having the plurality of cells C is the core layer 30.

Next, the second sheet 20 is pulled out from the second roll sheet. The drawn 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 (end walls 31 of a plurality of cells C) for a predetermined time. As a result, 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.

Further, 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 (connecting wall 33) of the core layer 30 for a predetermined 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. By the above steps, the laminated body 19 having the core layer 30 having a hollow structure is formed.

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

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

Looking at 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 projecting portions, these projecting portions project from the same plane in each mold 61, 62.

Each mold 61, 62 has, for example, a first projecting portion 63, a second projecting portion 64, and a plurality of pressing protrusions 65 projecting from the same plane. The first protruding portion 63 and the second protruding portion 64 are molds for forming the connecting portion 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 a plan view. The first protruding portion 63 and the second protruding portion 64 of the present embodiment form a rectangular closed loop in a 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 protruding portion 63 has a flat top surface for forming the abutting portion 22. Each first protruding portion 63 further has a curved surface that extends smoothly from the top surface toward the inner edge in order to form the proximity portion 21. Each second protruding portion 64 has a curved surface for forming the sandwiching portion 23.

The plurality of pressing protrusions 65 included in the molds 61 and 62 are located at positions separated from the corresponding first and second protruding portions 63 and 64. The protrusion length of these pressing protrusions 65 is substantially equal to the protrusion height of the corresponding second protrusion 64. Each pressing protrusion 65 has a substantially columnar shape. Each pressing protrusion 65 may have a flat tip surface for pressing the edge of the laminated body 19.

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

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

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

When the molding space P is defined, the thickness of the gap formed between the two first protruding portions 63 is not particularly limited, but the first sheet before molding and the second and third sheets are overlapped with each other. It can be substantially the same as or thinner than the thickness dimension of the case. However, if this gap is too thin, the strength of the plate material 11 will decrease. Therefore, the laminated body 19 may be crushed to the extent that the resin does not flow into the core layer 30, that is, to the extent that no gap remains in the core layer 30.

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

As shown in FIG. 4C, the two molds 61 and 62 define the molding space P and at the same time define the gate 66 for allowing the molten resin to flow in. The gate 66 communicates with the molding space P. When the cross section including the gate 66, the holding protrusion 65 and the first protruding portion 63 is viewed and the cross section orthogonal to the edge of the laminated body 19 is viewed, the holding protrusion 65 is connected to the gate 66 in the molding space P. It is located between the first protruding portion 63 and closer to the gate 66 than the first protruding portion 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 temperatures of the molds 61 and 62 are kept within a certain range by running water, for example, so as to be lower than the temperature of the molten resin. The portion of the laminated body 19 arranged in the molding space P includes a portion of the second and third sheets (skin layer) 20 in contact with the molds 61 and 62 (a portion in contact with the tip surface of the pressing protrusion 65). ), It is melted by the heat of the molten resin. That is, the temperatures of the dies 61 and 62 and the molten resin are set so that the portions of the second and third sheets 20 in contact with the tip surface of the pressing protrusion 65 are not melted by the heat of the molten resin. NS.

The laminate 19 is held in the molding space P until the inflowed resin solidifies to some extent. As a result, the resin molding portion 50 is molded in the molding space P along the edge of the laminated body 19. After that, the laminate 19 and the resin molding portion 50 are removed from the molds 61 and 62. As a result, the plate material 11 integrated with the inside of the resin molding portion 50 is formed.

As shown in FIGS. 1, 2 and 4D, the first protruding portion 63 and the second protruding portion 64 form a connecting portion 14, that is, a proximity portion 21, a contact portion 22, and a holding portion 23 on the plate material 11. Will be done.

Specifically, the portion of the plate material 11 sandwiched between the first protruding portions 63 becomes the contact portion 22. A proximity portion 21 is formed at a position adjacent to the contact portion 22. In the abutting portion 22, one or more layers may be irregularly folded and overlapped to partially create a gap.

The width of the band-shaped contact portion 22 is not particularly limited. However, if the width of the contact portion 22 is wide, the strength is lowered and the resin molded portion 50 may hang down due to its own weight. Therefore, the width of the contact portion 22 should be narrow. 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 recess 51.

The resin molding portion 50 has a plurality of recesses 51, which are traces of pulling out the plurality of pressing protrusions 65. The second and third sheets 20 remaining unmelted in the molding space P are exposed at the bottom of each recess 51, that is, the portion where the tip surface of the pressing protrusion 65 is in contact.

Next, a positioning step of positioning the laminated body 19 in the mold apparatus 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 laminated body 19 along the outer edge thereof.

As shown in FIG. 5B, the fixed mold 61 has a plurality of positioning protrusions 67 protruding into the molding space P. The laminated body 19 is positioned in the fixed mold 61 by inserting the corresponding positioning convex portion 67 into each positioning through hole 12 of the laminated body 19. The positions and numbers of the positioning through holes 12 and the positioning protrusions 67 can be appropriately changed. After this positioning, the movable mold 62 is moved toward the fixed mold 61.

As shown in FIG. 5C, with the laminated body 19 positioned, the molten resin is allowed to flow into the molding space P. A hole is formed in the resin molding portion 50, which is a trace of the positioning convex portion 67 being pulled out. At the bottom of this hole, the resin solidified after melting is exposed.

By going through the above manufacturing steps, a hollow structure 10 having a plate material 11 and a resin molding portion 50 can be 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 prefix conical shape, a shape in which prefixes of the prefix conical shape 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 insulating properties. The hollow structure 10 can be suitably used for applications requiring these characteristics. Further, since the hollow structure 10 includes the resin molded portion 50, it is lightweight and has high strength, and the hollow portion is sealed. Therefore, it has a heat insulating effect and a water blocking effect. Therefore, the hollow structure 10 can be used, for example, in a folding container for transporting food.

The operation and effect of this embodiment will be described.

(1) The separation distance between the two skin layers 20 in the proximity portion 21 is shorter than the separation distance between the two skin layers 20 in the main body portion 13. Therefore, it is possible to prevent the molten resin from flowing into the inside of the plate material 11 (laminated body 19), that is, between the two skin layers 20 during insert molding. If the molten resin flows into the plate material 11, the resin for forming the resin molding portion 50 may be insufficient, and the resin molding portion 50 may have unintended irregularities. In that respect, in the present embodiment, by suppressing the inflow of the resin into the plate material 11, the weight of the hollow structure 10 can be reduced while the resin molding portion 50 is suitably formed.

(2) In the proximity portion 21, both of the two skin layers 20 are curved in the direction of approaching each other. As a result, stress can be prevented from being concentrated on one skin layer 20 as compared with the case where only one of the two skin layers 20 is curved in the direction approaching the other skin layer 20.

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

(4) In 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 edge of the plate material 11 with the resin molding portion 50, the edge of the plate material 11 having a hollow structure can be sealed. This makes it possible to prevent foreign substances such as water, liquid or dust, and dust from entering the inside of the plate material 11.

(6) The resin molding portion 50 has a plurality of recesses 51 arranged in the longitudinal direction thereof. These recesses 51 are traces left for pressing the laminated body 19 with the pressing protrusion 65 during insert molding. This pressing prevents the skin layer 20 from coming out of the resin molding portion 50 during insert molding. As a result, the resin integrated by melting appears on the surface of the resin molding portion 50, so that the aesthetic appearance is maintained.

(7) Since the sandwiching portion 23 sandwiches the edge of the resin molding portion 50, the boundary between the plate material 11 and the resin molding 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 the present embodiment and the following modified examples can be combined with each other within a technically consistent range.

-In the present embodiment, in the proximity portion 21, only one of the two skin layers 20 may be curved in a direction approaching the other. Further, in the proximity 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 proximity portion 21 and the contact portion 22 do not have a curved surface, and the proximity portion 21 which is a flat slope and the main body portion 13 and the contact portion 22 which are flat surfaces intersect so as to form an angle. You may.

-In the contact portion 22, the core layer 30 may not be sandwiched between the two skin layers 20. For example, the heat of the resin that has flowed in during the insert process eliminates the boundary between the two skin layers 20 and the core layer 30, causing the two skin layers 20 to come into direct contact with each other, or the first to third sheets. May become integrated.

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

The proximity portion 21 and the contact portion 22 may extend linearly along the edge of the plate member 11, or may extend while being curved like a corrugation.

The thickness S of the resin molding portion 50 may be thinner than the thickness T of the main body portion 13 or may be thicker than the thickness T.

-Any region of the plate material 11 may be embedded in the resin molding portion 50, or the entire plate material 11 may be embedded in the resin molding portion 50. When the entire plate material 11 (laminated body 19) is embedded in the resin molding portion 50, the laminated body 19 is formed after the edge portion of the laminated body 19 is crushed to form the proximity portion 21 (and the contact portion 22). The resin molding portion 50 may be insert-molded by arranging it in the mold apparatus 60.

-The edge of the plate 11 is not limited to the outer edge of the plate 11. For example, when the plate material 11 has a through hole penetrating in the thickness direction thereof, the peripheral edge of the through hole becomes the edge of the plate material 11. In this case, the resin molding portion 50 may be molded along the peripheral edge of the through hole, or the proximity portion may be arranged along the peripheral edge 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 laminated body 19 can be positioned in the mold device 60 by sucking the laminated body 19 arranged in the mold device 60 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 arranged below the laminated body 19, and the fixed mold 61 may be arranged above the laminated body 19. Alternatively, the fixed mold 61 and the movable mold 62 may sandwich the laminated body 19 from the left and right. Further, the movable mold 62 may have a positioning convex portion 67.

-The shape of the pressing portion 65 can be changed. For example, the pressing protrusion 65 may be prismatic or conical. Further, the pressing protrusion 65 may be continuous with the second protruding portion 64. Further, a through hole may be provided in at least one of the dies 61 and 62, and the 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 have to have at least one of the second protruding portion 64 and the pressing protrusion 65. For example, when both the dies 61 and 62 do not have the pressing protrusion 65, a plurality of recesses 51 are not formed in the resin molding portion 50. Only one of the molds 61 and 62 may have the pressing protrusion 65. In this case, the recess 51 is formed on only one of the first surface and the second surface of the hollow structure 10.

-At least one of the molds 61 and 62 does not have to have the first protrusion 63. For example, when one of the molds 61 and 62 has a first protruding portion 63 that protrudes toward the other, the “gap formed between the two first protruding portions 63” is the “first protruding portion”. 63 becomes a "gap formed between 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, when the outer edge of the PP plate is integrated with the elastomeric resin molded portion, the shock absorbing effect can be improved. Therefore, even if the hollow structure 10 is dropped, it can be made difficult 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 the 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 modifications (see FIGS. 6 to 12).

-The planar shape of the plate material 11 can be deformed. For example, the planar shape of the plate member 11 may be circular or elliptical. Further, the plate material 11 may not be a flat plate but may be a partially or wholly curved plate. Further, the resin molding 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 molding portion 50 may include a rotation shaft for rotating the hollow structure 10 or a bearing of the rotation shaft. In this case, the hollow structure 10 can be used as a side plate of the folding container. Further, the resin molded portion 50 may be provided with a fastening portion for attaching to another member, for example, a hook. In this case, the strength may be improved as a whole by integrating the hollow structure 10 with another component, for example, a member having higher strength via the fastening portion.

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

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

-The core layer 30 (first sheet) may remain undissolved near the boundary between the contact portion 22 and the sandwiching portion 23. The contact portion 22 may include a portion in which the first sheet is folded to form a multi-layered portion so that the plurality of cells C are crushed. Some of these first sheets may not come into direct contact with the injected resin. A part of such a first sheet is pushed toward the abutting portion 22 without being melted by the heat of the molten resin, and remains undissolved near the abutting 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 inflow of the resin 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 see from the outside. That is, the core layer 30 that remains undissolved can be hidden by sandwiching the edge of the resin molded portion 50 between the two skin layers 20 (second and third sheets 20). As a result, it is possible to form a clear boundary between the plate material 11 and the resin molding portion 50 while suppressing the inflow of the resin into the plate material 11. Therefore, even if the color of the plate material 11 is different from the color of the resin molding portion 50, the boundary between the two is less likely to be disturbed.

The thickness of the contact portion 22, that is, the thickness of the gap between the two first protruding portions 63 when the molding space P is defined, is such that the first sheet before molding and the second and third sheets 20 are overlapped with each other. It may be thinner than the thickness. In this case, since the contact portion 22 does not have a hollow structure, it is possible to prevent the resin from flowing into the main body portion 13. The thickness of the abutting portion 22 may be thinner than the thickness of the two skin layers 20 and the partition wall 32 of the core layer 30 overlapped. 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 evacuated.

-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 the molding die shown in FIG. 7 as shown in FIG. The first sheet 100 can be molded by a vacuum forming method utilizing the plasticity of the sheet.

As shown in FIG. 7, the first sheet 100 has a plurality of first bulging portions 110 and a plurality of second bulging portions 120. The bulging portions 110 and 120 extend in a band shape in the X direction. The first bulging portion 110 and the second bulging portion 120 are alternately arranged 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 is a trapezoid whose cross section in the Y direction is obtained by dividing a regular hexagon into two by the longest diagonal line. The pair of end faces 110c are at the positions of the folding lines R. The angle formed by the end surface 110c and the first bulging surface 110a is about 90 °.

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 is a trapezoid obtained by dividing a regular hexagon into two by the longest diagonal line in the shape of the cross section in the Y direction. The pair of end faces 120c are at the positions of the folding lines Q. The angle formed by the end surface 120c and the second bulging 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 connection surface 110b of the first bulge 110 and the connection surface 120b of the second bulge 120 are separated for convenience of explanation, but have the same configuration.

The first sheet 100 shown in FIG. 7 is sequentially folded along the 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 bulging portion 110, the first bulging surface 110a on the right side in the X direction and the first bulging surface 110a on the left side in the X direction are valley-folded along the folding line Q located in the central portion in the X direction. Contact. The folded first bulging portion 110 has a partition wall 32a in which 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 faces 110c are arranged so as to be flush with each other to form the first wall 34.

Looking at one second bulging portion 120, the second bulging surface 120a on the right side in the X direction and the X direction are formed by being mountain-folded by 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 left side comes into contact with each other. In the folded second bulging portion 120, the partition wall 32 (32a) in which the two second bulging surfaces 120a in contact with each other form a two-layer structure and the partition wall 32 in which the connecting surface 120b forms a one-layer structure. (32b) and. The two adjacent end faces 120c are arranged so as to be flush with each other to 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 sandwiched between the two first protrusions 63. And are crushed. As a result, the abutting 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. As described above, when the core layer 30 includes a plurality of layers, the effect of suppressing the inflow of the resin into the main body 13 is high as described above. In particular, the partition wall 32a having a two-layer structure can more effectively suppress the inflow of the resin into the main body 13.

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

As shown in FIG. 10, in the first sheet 200, the plane region 210 and the bulging region 220 are alternately arranged in the longitudinal direction (X direction) of the first sheet 200. The plane region 210 and the bulge region 220 both extend along the Y direction. The bulging region 220 includes a reference plane 201 that is flush with the plane region 210, and a first bulging portion 221 that bulges from the reference plane 201 in the Z direction and extends over the entire bulging region 220 in the Y direction. The first bulging portion 221 has a first bulging surface 202 that bulges 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 formed by 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 twice the bulging height of the first bulging portion 221.

The bulge region 220 includes a plurality of second bulge portions 222 integrally formed with the first bulge portion 221. The second bulging portion 222 extends in opposite directions on both sides of the first bulging portion 221 and is arranged in the Y direction. Each of the second bulging portions 222 has a second bulging surface 204 bulging from the reference surface 201, two inclined surfaces 205 extending obliquely from the reference surface 201 to the second bulging surface 204, and the second bulging surfaces 204 and 2. It has an end surface 206 that intersects the 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 orthogonal to the first bulging surface 202 extending in the Y direction. The cross section of each second bulging portion 222 cut by a plane orthogonal to the X direction is a trapezoid obtained by dividing a regular hexagon into two by the longest diagonal line. The bulge height of the second bulge portion 222 is equal to the bulge height of the first bulge portion 221. Further, the distance between the second bulging portions 222 arranged in the Y direction is equal to the width of the second bulging surface 204.

As shown in FIGS. 11 and 12, the first sheet 200 is folded along the 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 of the first bulging portion 221 and the connecting surface 203 are folded. Fold it along the line Q and shrink it in the X direction. Then, the first bulging surface 202 and the connecting surface 203 of the first bulging portion 221 are folded, and the end surface 206 of the second bulging portion 222 and the plane region 210 are folded, so that the one bulging region 220 is covered. A prismatic compartment 230 extending in the Y direction is formed. The hollow plate-shaped core layer 30 is formed by continuously forming the compartments 230 in the X direction.

The core layer 30 of the second modification has a first wall 36 formed by the first bulging surface 202 and the connecting surface 203, and a second wall 37 formed by the end surface 206 and the plane region 210. The cell C of the second modification includes the first cell C1 and the second cell C2. The first cell C1 is a hexagonal column-shaped region formed between two adjacent compartments 230. The second cell C2 is a hexagonal column-shaped region in which the second bulging portion 222 is folded to form a section. The inclined surface 205 and the reference surface 201 serve as a partition wall 32 of the first cell C1. The second bulging surface 204 and the inclined surface 205 serve as a partition wall 32 of the second cell C2. The partition wall 32 formed by the contact portion between the second bulging surfaces 204 and the contact portion between 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 the core layer 30 in addition to the two skin layers 20. As described above, when the core layer 30 includes a plurality of layers, the effect of suppressing the inflow of the resin 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 inflow of the resin into the plate material 11.

As shown in the modified examples of FIGS. 6 and 9, the plurality of pressing protrusions 65 may be arranged near the outer edge of the laminated body 19 sandwiched by the dies 61 and 62. In this case, the recess 51 is formed at a position in contact with the outer edge of the resin molded portion 50 or near the outer edge. In other words, the resin molding portion 50 has an inner edge connected to the plate material 11 and an outer edge on the opposite side of the inner edge, and the plurality of recesses 51 are located closer to the outer edge than the inner edge of the resin molding portion 50. May be good.

When the laminated body 19 is pressed by the second protrusion 64 and the pressing protrusion 65, the outer edges of the two skin layers 20 may be bent so as to be separated from each other. When the skin layer 20 bent in this way comes into contact with the molds 61 and 62, the contacted portion may remain undissolved irregularly. If the skin layer 20 that remains irregularly melted appears on the surface of the resin molded portion 50, the appearance of the hollow structure 10 may be spoiled. In that respect, when the pressing protrusion 65 presses the outer edge or the vicinity of the outer edge of the laminated body 19, the bending of the skin layer 20 can be suppressed.

The protruding length of the pressing protrusion 65, that is, the depth of the recess 51 can be changed. For example, the protruding length of the pressing protrusion 65 (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 examples of FIGS. 6 and 9, in a state where the laminated body 19 is positioned in the mold device 60, it is outward (in FIG. 9) from the outer edge (left end edge in FIG. 9) of each holding protrusion 65. The protruding length (depth of the recess 51) of each pressing protrusion 65 may be longer than the length of the second and third sheets 20 (skin layer 20) extending to the left). In this case, even if the second and third sheets 20 pressed by the pressing protrusion 65 are bent or the bent portion remains undissolved, the second and third sheets 20 are not exposed on the surface of the resin molded portion 50. ..

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

When the first sheet is folded to form the core layer 30 having a honeycomb structure as in the first and second modification examples, the hexagonal columns of the plurality of cells C are partially distorted or do not line up in a straight line. It may happen. Therefore, the first protruding portion 63, the second protruding portion 64, and the pressing protrusion 65 of the molds 61 and 62 may push the region where the partition wall 32 is not uniformly arranged.

Claims (14)

It is a hollow structure, and the hollow structure is
A plate material having a hollow structure, which is a laminated body in which a first skin layer, a core layer, and a second skin layer are laminated in this order.
A resin molded portion arranged along the edge of the plate material and
With
The plate material has a proximity portion extending along the resin molding portion and has a proximity portion.
In the proximity portion, at least one of the first and second skin layers is bent so as to be close to the other.
Hollow structure. In the proximity portion, the first and second skin layers are curved in a direction approaching each other.
The plate material has a contact portion between the resin molded portion and the proximity portion, in which the first and second skin layers are in contact with the core layer.
The hollow structure according to claim 1. The core layer has a hollow structure in which the first sheet is molded so as to have a plurality of cells.
The first and second skin layers are second and third sheets bonded to both sides of the core layer, respectively.
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 hollow structure according to claim 2. The plate material is
The main body with a constant thickness and
It is a connecting portion arranged between the main body portion and the resin molding portion, and has a connecting portion including the proximity portion.
The thickness of the resin molded portion is equal to or thinner than the thickness of the main body portion.
The hollow structure according to any one of claims 1 to 3. The plate material has a holding portion that appears on the outer surface of the resin molding portion so as to sandwich the edge of the resin molding portion.
The sandwiching portion is located between the resin molding portion and the proximity portion.
The hollow structure according to any one of claims 1 to 4. The resin molded portion has a plurality of recesses arranged along the edge of the plate material.
The hollow structure according to any one of claims 1 to 5. The resin molded portion has an inner edge connected to the plate material and an outer edge opposite to the inner edge.
The plurality of recesses are located closer to the outer edge than the inner edge of the resin molded portion.
The hollow structure according to claim 6. It is a method of manufacturing a hollow structure.
Forming the first sheet to form a plate-shaped core layer having a plurality of cells,
To form a laminate having a hollow structure by joining the second sheet and the third sheet on both sides of the core layer, respectively.
The laminated body is sandwiched between the first mold and the second mold, and a molding space is defined between the first mold and the second mold along the edge of the laminated body.
Inflowing the molten resin into the molding space and
By solidifying the molten resin in the molding space and molding the resin molding portion along the edge.
Including
At least one of the first mold and the second mold has a pressing protrusion projecting into the molding space.
A manufacturing method in which the pressing protrusion has a tip surface for pressing the edge of the laminated body. The first mold when the molten resin is allowed to flow into the molding space so that the portions of the second sheet and the third sheet 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 8. The protruding 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 8 or 9. At least one of the first mold and the second mold has a protrusion that projects toward the other and has a protrusion that defines the molding space.
The thickness of the gap formed by the protrusion between the mold and the other mold is thinner than the thickness when the first sheet before molding and the second and third sheets are laminated.
The manufacturing method according to claim 9 or 10. Defining the molding space comprises crushing the core layer with the protrusions.
The manufacturing method according to claim 11. The core layer is
The first wall in contact with the second sheet and
The second wall in contact with the third sheet and
It has a plurality of partition walls extending between the first wall and the second wall, and a partition wall defining the plurality of cells.
At least a part of the plurality of partition walls has a two-layer structure.
Defining the molding space comprises crushing the partition wall having a two-layer structure by the protrusion.
The manufacturing method according to claim 11 or 12. Defining the molding space includes defining a gate through which the first mold and the second mold allow the molten resin to flow in.
When the cross section including the gate, the pressing protrusion and the protruding portion is viewed, the pressing protrusion is located between the gate and the protruding portion in the molding space, and is located from the protruding portion. Is also placed near the gate,
The manufacturing method according to any one of claims 11 to 13.

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