Composite structure and manufacturing method therefor

Abstract

A composite structure (100) is provided with: a bottom plate (1); and a pair of first side plates (3) erected from side edges of the bottom plate (1). The composite structure (100) is provided with: an outer plate material (10) and an inner plate material (20) which are formed from metal; and a foam body (30) formed from a foam material. The outer plate material (10) has an outer bottom plate part (11), a first outer side plate part (13), an outer surface (10a), and an outer opposing surface (10b). The inner plate material (20) has an inner bottom plate part (21), a first inner side plate part (23), an inner surface (20a), and an inner opposing surface (20b). The foam body (30) is filled between the outer opposing surface (10b) and the inner opposing surface (20b). The outer plate material (10) has an outer uneven part (16) provided on the outer surface (10a). The inner plate material (20) has an inner uneven part (26) provided on the inner surface (20a).

Description

Composite structure and manufacturing method thereof

[0001] The present disclosure relates to composite structures and methods for making same.

[0002] Patent Document 1 discloses an air conditioner cabinet molded from a composite of metal sheet and foam material. A mold consisting of a convex core and a concave upper mold is used for manufacturing. A metal sheet is set in the mold while suspended within the cavity by pins. Foam beads are injected into the cavity on both sides of the metal sheet and heated with steam. The upper mold is then separated from the core, and the product is removed from the mold.

[0003] Publication No. 8-1378

[0004] The beads expand when heated with steam, which increases the contact resistance between the foam material and the mold, making it difficult to release from the mold.

[0005] The cabinet described above is a three-layer box with a metal plate and foam material on both sides. Even if the metal plate and foam material were reversed, i.e., if the structure were a three-layer structure with metal plates on both sides of the foam material, it is believed that the same problem would occur due to the expansion of the beads. Furthermore, it is believed that the contact resistance would be even greater.

[0006] An object of the present disclosure is to provide a composite structure that can be easily demolded and a method for manufacturing the same.

[0007] One aspect of the present disclosure provides a composite structure comprising a bottom plate and a pair of side plates extending from the edges of the bottom plate, the composite structure comprising an outer bottom plate portion constituting the bottom plate, outer plate portions constituting the pair of side plates, outer surfaces of the outer bottom plate portion and the outer plate portions, and an outer facing surface opposite thereto, and made of metal; an inner plate portion constituting the bottom plate, inner plate portions constituting the pair of side plates, inner surfaces of the inner bottom plate portion and the inner plate portions, and an inner facing surface opposite thereto, and made of metal; and a foam molded from a foam material and filled between the outer facing surface and the inner facing surface, wherein the outer plate material has an outer uneven portion provided on the outer surface, and the inner plate material has an inner uneven portion provided on the inner surface.

[0008] According to the above configuration, the composite structure has at least a bottom plate and a pair of side plates, such as a channel or box shape. The composite structure has a three-layer structure in which metal plates are provided on both sides of a foam material, and can be manufactured by, for example, molding.

[0009] When a composite structure is manufactured by molding, the outer surface of the outer panel material and the inner surface of the inner panel material may come into contact with the surface of the mold. This outer surface is provided with external irregularities. Microscopically, the outer surface is in contact with the surface of the mold at the convex portions, while being separated from the surface of the mold at the concave portions. This separated state of the concave portions can be maintained even when the foam material is expanded inside the mold. Because the contact area of ​​the outer surface with the surface of the mold is reduced, the contact resistance is also reduced accordingly. The internal irregularities provided on the inner surface act in the same way. This makes demolding easier.

[0010] The outer uneven portion may be provided on the outer facing surface, the inner uneven portion may be provided on the inner facing surface, and the foam may be engaged with the outer uneven portion and the inner uneven portion.

[0011] According to the above configuration, the bonding strength of the foam to the outer plate material and the inner plate material is improved.

[0012] The outer concave-convex portion and the inner concave-convex portion may be formed by arranging a plurality of concave portions or a plurality of convex portions.

[0013] According to the above configuration, the outer uneven portion can be easily formed on both sides of the outer plate material by, for example, embossing or forging, and the inner uneven portion can be easily formed on both sides of the inner plate material.

[0014] The composite structure may further include a pair of second side plates extending from the edges of the bottom plate, and the pair of side plates and the pair of second side plates may form peripheral plates of a box body.

[0015] According to the above configuration, a box-shaped composite structure that is easy to release from the mold can be provided. The composite structure has a three-layer structure with metal plates on both sides of the foam material, and is excellent in robustness and heat insulation. Structures suitable for transporting cargo that requires temperature control can be efficiently produced.

[0016] Another aspect of the present disclosure is a manufacturing method of a composite structure including a bottom plate and a pair of side plates extending from a peripheral edge of the bottom plate, the method including the steps of: forming, from metal, an outer plate material having an outer bottom plate portion constituting the bottom plate, outer plate portions constituting the pair of side plates, outer surfaces of the outer bottom plate portion and the outer plate portions, and an outer facing surface on the opposite side thereof; forming, from metal, an inner bottom plate portion constituting the bottom plate, inner plate portions constituting the pair of side plates, inner surfaces of the inner bottom plate portion and the inner plate portions, and an inner facing surface on the opposite side thereof; and forming, from metal, an inner plate material having an inner bottom plate portion constituting the bottom plate, inner plate portions constituting the pair of side plates, inner surfaces of the inner bottom plate portion and the inner plate portions, and an inner facing surface on the opposite side thereof; and forming, from metal, a mold including a first mold having a mold recess and a second mold having a mold protrusion, the mold protrusion being in a mold open state in which the mold protrusion is retracted from the mold recess. a step of fitting the outer plate material into the mold recess and fitting the inner plate material outwardly into the mold protrusion; a step of closing the mold with the mold protrusion inserted into the mold recess; a step of filling a cavity formed between the outer and inner opposing surfaces with a foaming material; a step of heating the foaming material to form a foam between the outer plate material and the inner plate material; and a step of opening the mold and removing the composite structure from the mold, wherein in the step of molding the outer plate material, an outer uneven portion is provided on the outer surface, and in the step of molding the inner plate material, an inner uneven portion is provided on the inner surface.

[0017] In the above configuration, the composite structure also has at least a bottom plate and a pair of side plates, such as a channel or box shape. The composite structure is constructed with a three-layer structure in which metal plates are attached to both sides of the foam material, and is manufactured by molding. The outer surface of the outer plate material is in close proximity to the surface of the mold recess. Since the outer surface of the outer plate material is provided with an external concave-convex portion, the convex portion contacts the surface of the mold recess, while the concave portion is spaced apart from the surface of the mold recess. Even when the foam material is heated and expands within the cavity, this spaced-apart state of the concave portions can be maintained. The contact area between the outer surface and the mold is reduced, and contact resistance is correspondingly reduced. The inner surface of the inner plate material and the surface of the mold convex portion also function in a similar manner. This facilitates the process of removing the composite structure from the mold, i.e., demolding.

[0018] The outer uneven portion may be provided on the outer facing surface, and the inner uneven portion may be provided on the inner facing surface, and in the process of heating the foam material, the foam may enter and engage with the outer uneven portion and the inner uneven portion.

[0019] According to the above configuration, the foam and the outer and inner panel materials interlock with each other at the outer and inner uneven portions, preventing relative movement between the outer panel material and the foam, and between the inner panel material and the foam, and as a result, the outer panel material, inner panel material, and foam material can be integrated without separating from each other.

[0020] The outer uneven portion and the inner uneven portion may be provided on a sliding surface of the outer surface or the inner surface that slides against the mold.

[0021] According to the above configuration, demolding can be effectively facilitated.

[0022] The process of forming the outer plate material may include a process of forming a flat blank having the outer bottom plate portion and the outer plate portion in an expanded state, and a process of bending the blank so that the outer plate portion stands upright from the outer bottom plate portion, and the outer uneven portion may be provided on the blank before the process of bending.

[0023] According to the above configuration, the outer uneven portion can be easily formed in the process of molding the outer plate material, and the production efficiency of the outer plate material is improved.

[0024] According to the present disclosure, it is possible to provide a composite structure that can be easily demolded and a method for manufacturing the same.

[0025] 5A ; 6A ; 6B ; 6C ; 6D ; 6E ; 6F ; 6G ; 6H ; 6I ; 6J ; 6J ; 6I ...

[0026] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or corresponding elements are designated by the same reference numerals throughout the drawings, and detailed descriptions thereof will be omitted.

[0027] Referring to Figure 1, a composite structure 100 according to this embodiment has a box shape as a whole and is suitable for use, for example, in transporting luggage. The composite structure 100 has a bottom plate 1, a peripheral plate 2, and a flange 5. The bottom plate 1 and the peripheral plate 2 form a box body that is open upward. The inner surfaces of the bottom plate 1 and the peripheral plate 2 define an internal space 6 capable of storing luggage or the like.

[0028] The bottom plate 1 is, for example, rectangular in plan view. The bottom plate 1 has four edges defining the rectangle: a pair of first edges 1a and a pair of second edges 1b. The pair of first edges 1a are parallel to each other, and the pair of second edges 1b are parallel to each other, with the second edges 1b extending in a direction perpendicular to the first edges 1a. The peripheral plate 2 extends from the edges of the bottom plate 1. The peripheral plate 2 includes a pair of first side plates 3 and a pair of second side plates 4, for a total of four side plates. The pair of first side plates 3 extend from each of the pair of first edges 1a, and the pair of second side plates 4 extend from each of the pair of second edges 1b. A flange 5 is provided on the upper edge of the peripheral plate 2. The flange 5 has a rectangular window frame shape in plan view and defines an upper opening of the box body.

[0029] 1 to 3, the composite structure 100 includes an outer plate material 10 formed from a metal, an inner plate material 20 formed from a metal, and a foam body 30 formed from a foam material, with the foam body 30 sandwiched between the outer plate material 10 and the inner plate material 20. In other words, the composite structure 100 has a three-layer structure in which the metallic outer plate material 10 and the metallic inner plate material 20 are provided on both sides of the foam body 30.

[0030] Steel or aluminum alloy is preferably used as the metal material for the outer panel 10. The same applies to the inner panel 20. The outer panel 10 and the inner panel 20 may be formed from the same metal or different metals. Polyurethane, polystyrene, or polyolefin is preferably used as the foam material for the foam 30.

[0031] The three-layer structure is applied to the entire bottom plate 1 and the peripheral plate 2. That is, the outer plate material 10, the foam 30, and the inner plate material 20 are also a box-like structure that is open upward, just like the finished composite structure 100. The flange 5 is constructed of a two-layer structure of the outer plate material 10 and the foam 30.

[0032] 2, the outer panel 10, the inner panel 20, and the foam 30 are shown in a separated state for the sake of convenience of explanation. As will be described later, the foam 30 is formed integrally with the outer panel 10 and the inner panel 20 by molding. In the manufacturing process of the composite structure 100, the foam 30 of the box body is not handled as a single item.

[0033] The outer plate material 10 has an outer bottom plate portion 11 that constitutes the bottom plate 1, an outer peripheral plate portion 12 that constitutes the peripheral plate 2, and a lower flange portion 15 that constitutes the flange 5. The outer peripheral plate portion 12 includes a pair of first outer plate portions 13 that correspond to the pair of first side plates 3, respectively, and a pair of second outer plate portions 14 that correspond to the pair of second side plates 4, respectively.

[0034] The outer plate material 10 has an outer surface 10a and an outer facing surface 10b opposite the outer surface 10a in the plate thickness direction. The outer surface 10a corresponds to the outer surface of the composite structure 100. The outer surface of the outer bottom plate portion 11 corresponds to the outer surface (lower surface) of the bottom plate 1, and the outer surface of the outer peripheral plate portion 12 corresponds to the outer surface (outer side surface) of the peripheral plate 2.

[0035] The inner plate material 20 has an inner bottom plate portion 21 that constitutes the bottom plate 1, and an inner peripheral plate portion 22 that constitutes the peripheral plate 2. The inner peripheral plate portion 22 includes a pair of first inner plate portions 23 that correspond to the pair of first side plates 3, respectively, and a pair of second inner plate portions 24 that correspond to the pair of second side plates 4, respectively.

[0036] The inner plate material 20 has an inner surface 20a and an inner opposing surface 20b on the opposite side of the inner surface 20a in the plate thickness direction. The inner surface 20a corresponds to the inner surface of the composite structure 100 and defines the internal space 6. The inner surface of the inner bottom plate portion 21 corresponds to the inner surface (top surface) of the bottom plate 1, and the inner surface of the inner peripheral plate portion 22 corresponds to the inner surface (inner side surface) of the peripheral plate 2.

[0037] The foam 30 has a middle bottom plate portion 31 that constitutes the bottom plate 1, a middle peripheral plate portion 32 that constitutes the peripheral plate 2, and an upper flange portion 35 that constitutes the flange 5. The middle peripheral plate portion 32 includes a pair of first middle side plate portions 33 that correspond to the pair of first side plates 3, respectively, and a pair of second middle side plate portions 34 that correspond to the pair of second side plates 4, respectively.

[0038] The foam 30 is filled between the outer surface 10b of the outer plate 10 and the inner surface 20b of the inner plate 20. The foam 30 has an outer surface 30a and an inner surface 30b opposite the outer surface 30a in the plate thickness direction. The outer surface 30a is in close contact with the outer surface 10b, and the inner surface 30b is in close contact with the inner surface 20b.

[0039] The bottom plate 1 is formed by stacking an outer bottom plate portion 11, a middle bottom plate portion 31, and an inner bottom plate portion 21 in this order from the outside to the inside of the composite structure 100 in the thickness direction of the bottom plate 1. The first side plate 3 is formed by stacking a first outer plate portion 13, a first middle plate portion 33, and a first inner plate portion 23 in this order from the outside to the inside of the composite structure 100 in the thickness direction of the first side plate 3. The second side plate 4, the second outer plate portion 14, the second middle plate portion 34, and the second inner plate portion 24 are formed in the same way as the first side plate 3.

[0040] The flange 5 is formed by laminating an upper flange portion 35 of a foam 30 on the upper surface side of the lower flange portion 15 of the outer plate material 10. The upper surface of the lower flange portion 15 is formed by a portion of the outer facing surface 10b, and the lower surface of the upper flange portion 35 is formed by a portion of the outer surface 30a and is in close contact with the upper surface of the lower flange portion 15. The lower surface of the flange 5 as a whole is formed by the outer plate material 10. The upper surface of the flange 5 as a whole is formed by the foam 30 and is positioned at approximately the same height as the upper edge of the inner peripheral plate portion 22 of the inner plate material 20.

[0041] The outer panel 10 has an outer uneven portion 16 provided on the outer surface 10a. The outer uneven portion 16 is configured by forming multiple protrusions 16a on the outer surface 10a. Each protrusion 16a is formed by recessing the outer facing surface 10b toward the outer surface 10a in the thickness direction of the outer panel 10, and is island-shaped. The multiple protrusions 16a are arranged in a specific region of the outer surface 10a. Within the region of the outer surface 10a where the multiple protrusions 16a are arranged, areas where no protrusions 16a are actually formed are recessed toward the outer facing surface 10b in the thickness direction relative to areas where the protrusions 16a are actually formed. Even if only the protrusions 16a are formed on the outer surface 10a, it is possible to provide the outer surface 10a with substantial unevenness.

[0042] The convex portions 16a are formed by a press process (such as embossing) that applies a pressing force to the outer facing surface 10b, as described below. By forming multiple convex portions 16a on the outer surface 10a, multiple concave portions 16b are transferred to the outer facing surface 10b. Each concave portion 16b is formed by recessing the outer facing surface 10b toward the outer surface 10a in the thickness direction of the outer panel 10, resulting in a pond-like shape. Within the region of the outer facing surface 10b where multiple concave portions 16b are arranged, areas where no concave portions 16b are actually formed protrude toward the outer facing surface 10b in the thickness direction relative to areas where the concave portions 16b are actually formed. Even if only the concave portions 16b are formed on the outer facing surface 10b, it is possible to essentially provide concave and convex portions on the outer facing surface 10b. In this way, the outer concave and convex portions 16 are provided on the outer surface 10a, and are simultaneously provided on the outer facing surface 10b.

[0043] The inner plate material 20 has an inner uneven portion 26 provided on the inner surface 20a side. The inner uneven portion 26 is configured by forming multiple protrusions 26a on the inner surface 20a. Each protrusion 26a is formed by recessing the inner opposing surface 20b toward the inner surface 20a in the plate thickness direction of the inner plate material 20. The multiple protrusions 26a are arranged in a specific region of the inner surface 20a. In the region of the inner surface 20a where the multiple protrusions 26a are arranged, substantial unevenness is provided even if only the protrusions 26a are actually formed.

[0044] The convex portions 26a are formed in the same manner as the convex portions 16a. By forming a plurality of convex portions 26a on the inner surface 20a, a plurality of concave portions 26b are transferred to the inner facing surface 20b. Each concave portion 26b is formed by recessing the inner facing surface 20b toward the inner surface 20a in the thickness direction of the inner plate material 20. In the region of the inner facing surface 20b where a plurality of concave portions 26b are arranged, substantial concave and convex portions are formed even if only the concave portions 26b are actually formed. In this way, the inner concave and convex portions 26 are formed on the inner surface 20a, and are simultaneously formed on the inner facing surface 20b.

[0045] When the outer uneven portion 16 is composed of multiple convex portions 16a or concave portions 16b, the arrangement pattern of these convex portions 16a and concave portions 16b may be regular, such as a matrix or a staggered pattern, or may be irregular. The shapes of the convex portions 16a and concave portions 16b are not particularly limited. In addition to the circular shape shown in the figure, other shapes such as an ellipse, a regular polygon, or a star may also be used. The convex portions 16a may be formed on the outer facing surface 10b, and the concave portions 16b may be formed on the outer surface 10a. However, forming the convex portions 16a on the outer surface 10a is advantageous in that it facilitates the contact area reduction effect described below. The region where the outer uneven portion 16 is provided (the region where multiple convex portions 16a or concave portions 16b are arranged) is at least a sliding surface with the mold 50 (see FIG. 7). The same applies when the inner uneven portion 26 is composed of multiple convex portions 26a or concave portions 26b.

[0046] The foam 30 is engaged on its outer surface with the outer uneven portion 16, and on its inner surface with the inner uneven portion 26. An uneven pattern is transferred onto the outer surface 30a of the foam 30 so as to engage with the outer uneven portion 16. An uneven pattern is transferred onto the inner surface 30b of the foam 30 so as to engage with the inner uneven portion 26.

[0047] FIG. 4 shows a method for manufacturing a composite structure according to this embodiment. To manufacture the composite structure 100, first, the outer plate 10 is molded from metal (step S1, see FIG. 5), and the inner plate 20 is molded from metal (step S2, see FIG. 6). Next, while the mold 50 is in an open state, the outer plate 10 and the inner plate 20 are placed in the mold 50 (step S3, see FIG. 7), and the mold 50 is closed (step S4, see FIG. 8). Next, foamed beads 30A are filled into the cavity 53 (step S5, see FIG. 8), and the foamed beads 30A are heated (step S6, see FIG. 9). Next, the mold 50 is opened (step S7, see FIGS. 10A and 10B), and the composite structure 100 is removed from the mold 50 (step S8). This results in the composite structure 100 shown in FIG. 1 being obtained.

[0048] 5A and 6A are explanatory diagrams of the steps (steps S1 and S2) of forming the outer plate material 10 and the inner plate material 20. FIG.

[0049] Referring to FIG. 5A , the shell plate 10 is formed by forming a flat blank 10A having an outer bottom plate 11, an outer peripheral plate 12 (first outer plate 13 and second outer plate 14), and a lower flange 15 in an expanded state. The blank 10A is formed, for example, by punching a sheet material drawn from a metal coil. FIG. 5A is a developed view of the shell plate 10 and also a plan view of the blank 10A of the shell plate 10. Then, by performing a required bending process on the blank 10A, the outer peripheral plate 12 is formed to stand upright from the outer bottom plate 11, and the lower flange 15 is formed to be bent from the outer peripheral plate 12. Furthermore, after the bending process, adjacent two of the four outer plate portions, i.e., the pair of first outer plate portions 13 and the pair of second outer plate portions 14, are welded to each other. This results in the shell plate 10 being formed into a box shape.

[0050] 5A, which is a plan view of the blank 10A, the outer irregularities 16 are formed on the blank 10A before bending. To form the outer irregularities 16 on the outer plate material 10, the outer surface 10a is embossed to form multiple protrusions 16a on the outer surface 10a and multiple recesses 16b on the outer facing surface 10b. In this embodiment, the area where the outer irregularities 16 are formed is, for example, the entire outer bottom plate portion 11 and the outer peripheral plate portion 12.

[0051] Referring to Figure 6A, the forming of the inner plate 20 is similar to that of the outer plate 10. A flat blank 20A is formed, which has an inner bottom plate 21 and an inner periphery plate 22 (a first inner plate 23 and a second inner plate 24) in a developed state. Figure 6 is a developed view of the inner plate 20, and also a plan view of the blank 20A of the inner plate 20. By subjecting this blank 20A to the required bending process, the inner periphery plate 22 is formed so as to stand upright from the inner bottom plate 21. After the bending process, the inner periphery plate 22 is welded in the same manner as the outer plate 10. As a result, the inner plate 20 is formed into a box shape.

[0052] The inner uneven portion 26 is also provided on the blank 20A before bending. To provide the inner uneven portion 26 on the inner plate material 20, the inner surface 20a is embossed to form a large number of convex portions 26a on the inner surface 20a and a large number of concave portions 26b on the inner opposing surface 20b. In this embodiment, the region where the inner uneven portion 26 is provided is, for example, the entire inner bottom plate portion 21 and the inner circumferential plate portion 22.

[0053] Referring to Fig. 5B, as an example, the convex portions 16a and concave portions 16b of the outer concave-convex portion 16 are hemispherical. Therefore, the portion of each convex portion 16a where the protrusion height from the outer surface 10a is greatest (the apex portion of the convex portion 16a) is point-like. In this embodiment, the apex portions of the multiple convex portions 16a are at approximately the same height. Referring to Fig. 6B, the same applies to the convex portions 26a and concave portions 26b of the inner concave-convex portion 26.

[0054] The protruding height of the convex portions 16a of the outer uneven portion 16 (or the depth of the concave portions 16b) is ○○○ to ○○○ μm. When a metal material is used for the outer plate material 10 and the protruding height is set in this manner, the entire sliding surface of the outer plate material 10 can be prevented from being pressed against the mold 50 (see FIG. 8) even when the foam beads 30A (see FIG. 8) expand, thereby achieving the effect of facilitating demolding, as described below. Furthermore, when the protruding height is set in this manner, the presence of the concave portions can be fully felt by stroking the outer uneven portion 16 with one's hand. In other words, the presence or absence of the outer uneven portion 16 can be determined by human sense. The same applies to the protruding height of the convex portions 26a of the inner uneven portion 26 (or the depth of the concave portions 26b).

[0055] FIG. 7 is an explanatory diagram of the process of placing the outer plate material 10 and the inner plate material 20 in the mold 50 (step S3).

[0056] The mold 50 includes a first mold 51 and a second mold 52. The first mold 51 has a mold recess 51A. The second mold 52 has a mold protrusion 52A. The second mold 52 is displaceable relative to the first mold 51. This relative displacement causes the mold 50 to switch between an open state in which the mold protrusion 52A retreats from the mold recess 51A, and a closed state in which the mold protrusion 52A advances into the mold recess 51A. Figure 7 shows the open state of the mold 50. The first mold 51 may be fixed and the second mold 52 may be movable, or vice versa.

[0057] In this embodiment, the relative displacement direction of the first mold 51 and the second mold 52 (i.e., the mold opening / closing direction) corresponds to the direction in which the composite structure 100 is removed from the mold 50 (i.e., the mold release direction), and corresponds to the direction in which the composite structure 100 slides relative to the mold 50 during mold release (i.e., the product sliding direction). In the following description, the mold opening / closing direction, the mold release direction, and the product sliding direction correspond to the up-down direction as illustrated, but these directions can be changed as appropriate to other directions, such as the horizontal direction.

[0058] The first mold 51 has a first main body 51a in the shape of a rectangular box that is open upward, and a shoulder 51b that protrudes outward from the upper end of the first main body 51a. The mold recess 51A is defined by the inner bottom surface and inner circumferential surface of the first main body 51a. The shoulder 51b forms a stepped surface that extends from the upper end of the inner circumferential surface of the first main body 51a to the outside of the first main body 51a.

[0059] In the mold open state, the box-shaped outer plate 10 is fitted into the mold recess 51A. The outer surface 10a of the outer plate 10 is close to the inner surface of the mold recess 51A. The outer surface of the outer bottom plate 11 is close to the inner bottom surface of the mold recess 51A (the inner bottom surface of the first main body 51a), and the outer surface of the outer plate 12 is close to the inner circumferential surface of the mold recess 51A (the inner circumferential surface of the first main body 51a). The lower surface of the lower flange 15 is close to the stepped surface of the shoulder 51b.

[0060] The inner peripheral surface of the mold recess 51A extends upward from the inner bottom surface of the mold recess 51A, i.e., in the mold opening / closing direction, mold release direction, and product sliding direction. As described below, the outer surface of the outer peripheral plate 12 can slide against the inner surface of the mold recess 51A during mold release. That is, of the outer surface 10a of the outer plate material 10, the outer surface of the outer peripheral plate 12 is the sliding surface with the mold 50. In this embodiment, an outer uneven portion 16 is provided on this sliding surface. On the other hand, although the outer surface of the outer bottom plate 11 and the lower surface of the lower flange 15 are close to the surface of the first mold 51, they extend in a direction perpendicular to the mold opening / closing direction and cannot be considered sliding surfaces. However, in this embodiment, the outer uneven portion 16 is also provided on the outer surface of the outer bottom plate 11.

[0061] The second mold 52 has a second main body 52a in the shape of a rectangular box that is open upward, and a flange 52b that protrudes outward from the upper end of the first main body 51a. The mold protrusion 52A is defined by the outer bottom surface and outer peripheral surface of the second main body 52a.

[0062] In the mold open state, the box-shaped inner plate material 20 is fitted onto the mold convex portion 52A. The inner surface 20a of the inner plate material 20 is close to the outer surface of the mold convex portion 52A. The inner surface of the inner bottom plate portion 21 is close to the outer bottom surface of the mold convex portion 52A (the outer bottom surface of the second main body portion 52a). The inner surface of the inner periphery plate portion 22 is close to the outer periphery surface of the mold convex portion 52A (the outer periphery surface of the second main body portion 52a).

[0063] The outer peripheral surface of the mold protrusion 52A extends upward from the outer bottom surface of the mold protrusion 52A, i.e., in the mold opening / closing direction, mold release direction, and product sliding direction. As described below, the outer surface of the inner peripheral plate 22 can slide against the inner surface of the mold protrusion 52A during mold release. That is, of the inner surface 20a of the inner plate material 20, the inner surface of the inner peripheral plate 22 is the sliding surface with the mold 50. In this embodiment, an inner uneven portion 26 is provided on this sliding surface. On the other hand, although the inner surface of the inner bottom plate 21 is close to the surface of the second mold 52, it extends in a direction perpendicular to the mold opening / closing direction and cannot be considered a sliding surface. However, in this embodiment, the inner uneven portion 26 is also provided on the inner surface of the inner bottom plate 21.

[0064] FIG. 8 is an explanatory diagram of the step of closing the mold 50 (step S4) and the step of filling the cavity 53 with foam beads 30A (step S5).

[0065] The state of the mold 50 is switched from a mold open state to a mold closed state by relatively displacing the first mold 51 and the second mold 52. In the mold closed state, the mold protrusion 52A with the inner plate 20 inserted therein enters the mold recess 51A with the outer plate 10 inserted therein. A cavity 53 is formed in the mold 50 between the outer surface 10b of the outer plate 10 and the inner surface 20b of the inner plate 20.

[0066] The flange portion 52b of the second mold 52 is fitted into the shoulder portion 51b of the first mold 51. The lower surface of the flange portion 52b is spaced above the upper surface of the lower flange portion 15 of the shell panel 10, which is supported on the stepped surface of the shoulder portion 51b. The space between the flange portion 52b and the lower flange portion 15 communicates with the space between the outer facing surface 10b and the inner facing surface 20b, and forms part of the cavity 53.

[0067] The mold 50 is provided with a bead port 54 for injecting the foamed beads 30A into the cavity 53. For example, the bead port 54 is a through-hole formed in the flange portion 52b of the second mold 52. Because the inner plate material 20 does not cover the flange portion 52b, this through-hole can easily connect the external space of the mold 50 to the cavity 53. A part or all of the bead port 54 may be provided in the shoulder portion 51b of the first mold 51.

[0068] In the mold closed state, the foam beads 30A are injected into the cavity 53 from the external space of the mold 50 via the bead port 54 using compressed air. As a result, the cavity 53 is filled with the foam beads 30A.

[0069] FIG. 9 is an explanatory diagram of the step of heating the foamed beads 30A (step S6).

[0070] The mold 50 is provided with a steam port 55 for supplying steam to the cavity 53. For example, the steam port 55 is a through-hole formed in the second body portion 52a of the second mold 52. The steam port 55 may also be formed in the first body portion 51a of the first mold 51. Steam is supplied to the cavity 53 through the steam port 55, and the air in the cavity 53 is replaced with the steam. This heats the foamed beads 30A, accelerating their expansion. Note that the mold 50 is heated by a heater (not shown) to accelerate the heating of the foamed beads 30A. After this heating step, the mold 50 and its interior are cooled by water cooling and natural cooling.

[0071] As a result of the heating and cooling processes, the foam 30 is interposed between the outer plate material 10 and the inner plate material 20 and is formed integrally with the outer plate material 10 and the inner plate material 20, thereby forming a multi-layered box-shaped composite structure 100. The foam 30 is fused to the outer facing surface 10b and the inner facing surface 20b to form a middle bottom plate portion 31 and a middle periphery plate portion 32. The foam 30 is fused to the upper surface of the lower flange portion 15 of the outer plate material 10 to form an upper flange portion 35.

[0072] The outer uneven portion 16 is also provided on the outer facing surface 10b that defines the cavity 53. The inner uneven portion 26 is also provided on the inner facing surface 20b that defines the cavity 53. While the foamed beads 30A are being heated, the foamed beads 30A expand and enter the concave portions of the outer uneven portion 16 and the concave portions of the inner uneven portion 26.

[0073] The concave portions of the outer uneven portion 16 on the outer facing surface 10b may be defined as portions where the concave portions 16b are actually formed within a region of the outer facing surface 10b where multiple concave portions 16b are arranged. In cases where convex portions are actually formed on the outer facing surface 10b, the concave portions of the outer facing surface 10b may be defined as portions where the convex portions are not actually formed. The concave portions of the inner uneven portion 26 on the inner facing surface 20b may be defined as portions where the concave portions 26b are actually formed within a region of the inner facing surface 20b where multiple concave portions 26b are arranged. In cases where convex portions are actually formed on the inner facing surface 20b, the concave portions of the inner facing surface 20b may be defined as portions where the convex portions are not actually formed.

[0074] 10A and 10B are explanatory diagrams of the step of opening the mold 50 (step S7) and the step of releasing the mold (step S8).

[0075] By relatively displacing the first mold 51 and the second mold 52, the state of the mold 50 is switched from a mold closed state to a mold open state. The composite structure 100 may remain in the first mold 51 while being fitted inside the mold recess 51A (see FIG. 10A). The composite structure 100 may remain in the mold while being fitted outside the mold protrusion 52A (see FIG. 10B).

[0076] 10A , when the composite structure 100 remains in the first mold 51, the expansion of the foam 30 presses the outer plate material 10 against the inner surface of the mold recess 51A. The composite structure 100 is removed from the first mold 51 in the direction toward the second mold 52 (upward in the drawing). At this time, the outer surface of the outer peripheral plate portion 12 is a sliding surface as described above, and is in sliding contact with the inner surface of the mold recess 51A in an upward direction.

[0077] 10B , when the composite structure 100 remains in the second mold 52, the expansion of the foam 30 presses the inner plate material 20 against the outer surface of the mold protrusion 52A. The composite structure 100 is removed from the second mold 52 in the direction toward the first mold 51 (downward in the drawing). At this time, the inner surface of the inner peripheral plate portion 22 is a sliding surface as described above, and is in sliding contact with the inner surface of the mold protrusion 52A in a downward direction.

[0078] 10A, the inner surface of the inner peripheral plate portion 22 does not slide against the mold 50 during demolding, and in the example shown in Fig. 10B, the outer surface of the outer peripheral plate portion 12 does not slide against the mold 50 during demolding. However, these surfaces are collectively referred to as sliding surfaces in light of the fact that they may slide against the mold 50 depending on the situation.

[0079] In the composite structure 100 according to this embodiment, the outer plate material 10 has an outer uneven portion 16 provided on the outer surface 10a, and the inner plate material 20 has an inner uneven portion 26 provided on the inner surface 20a.

[0080] In the example shown in Figure 10A, due to the presence of the outer uneven portion 16, the outer surface 10a contacts the inner surface of the mold recess 51A at the convex portions, while being separated from the inner surface of the mold recess 51A at the concave portions. Because the contact area of ​​the outer surface 10a with the inner surface of the mold recess 51A is reduced, the contact resistance is also reduced accordingly. This facilitates demolding. In particular, the outer uneven portion 16 is provided on the sliding surface of the outer surface 10a. This makes it easier to achieve the effect of facilitating demolding.

[0081] The protrusions 16a are hemispherical, and therefore the top of each protrusion 16a is point-like, and each protrusion 16a is in almost point contact with the inner surface of the mold recess 51A. The contact area is greatly reduced, making mold release even easier.

[0082] The same applies to the example shown in Figure 10B. Due to the presence of the inner uneven portion 26, the inner surface 20a contacts the outer surface of the mold convex portion 52A at the convex portions, while being separated from the outer surface of the mold convex portion 52A at the concave portions. Because the contact area of ​​the inner surface 20a with the outer surface of the mold convex portion 52A is reduced, the contact resistance is also reduced accordingly. This facilitates demolding. In particular, the inner uneven portion 26 is provided on the sliding surface of the inner surface 20a. This makes it easier to achieve the effect of facilitating demolding.

[0083] The protrusions 26a are hemispherical, and therefore the top of each protrusion 26a is point-like, and each protrusion 26a is in almost point contact with the outer surface of the mold protrusion 52A. The contact area is greatly reduced, making mold release even easier.

[0084] The outer uneven portion 16 is also provided on the outer facing surface 10b of the outer panel 10, opposite the outer surface 10a in the thickness direction. The inner uneven portion 26 is also provided on the inner facing surface 20b of the inner panel 20, opposite the inner surface 20a in the thickness direction. The foam 30 is interposed between the outer facing surface 10b and the inner facing surface 20b, and is engaged with the outer uneven portion 16 and the inner uneven portion 26. The foam 30 engages with the outer panel 10 and the inner panel 20 at the outer uneven portion 16 and the inner uneven portion 26, respectively, preventing relative movement between the outer panel 10 and the foam 30, and between the inner panel 20 and the foam 30. This prevents the outer panel 10, the inner panel 20, and the foam 30 from separating from each other and becoming integrated, improving the bonding strength of the foam 30 to the outer panel 10 and the inner panel 20. Even if no adhesive is used, the three components of the outer panel 10, the foam 30, and the inner panel 20 can be kept firmly joined together.

[0085] The outer uneven portion 16 and the inner uneven portion 26 are formed by arranging a plurality of convex portions 16a, 26a or concave portions 16b, 26b. A press process such as embossing is used for this formation. The outer uneven portion 16 can be easily formed on both sides of the outer plate material 10. The inner uneven portion 26 can be easily formed on both sides of the inner plate material 20. Furthermore, the outer uneven portion 16 and the inner uneven portion 26 can be easily formed during the process of forming the blanks 10A, 20A, improving the production efficiency of the outer plate material 10 and the inner plate material 20. For example, blanks 10A, 20A having the outer uneven portion 16 and the inner uneven portion 26 can be efficiently produced by using a transfer press.

[0086] The composite structure 100 according to this embodiment includes a pair of first side plates and a pair of second side plates, which form the peripheral plate 2 of the box body. This allows for a box-shaped composite structure 100 that is easy to demold. The composite structure 100 has a three-layer structure with metal plates on both sides of the foam material, and is therefore robust and has excellent heat insulation. This allows for the efficient production of structures suitable for transporting cargo that requires temperature control.

[0087] Although the embodiments have been described above, the above configurations can be modified as appropriate within the scope of the present invention.

[0088] The composite structure 100 may be a channel type, in which case the pair of second side plates are omitted and the composite structure 100 mainly includes three plates: a bottom plate and a pair of side plates. In this case, as with the box type, it is possible to facilitate demolding and improve bonding strength.

[0089] For the purpose of achieving easy demolding, the outer uneven portion 16 may be omitted from the outer facing surface 10b. The same applies to the inner uneven portion 26.

[0090] In the above embodiment, the outer uneven portion 16 is provided on the entire sliding surface, but this is just one example. The outer uneven portion 16 may be provided on only a part of the sliding surface. The same applies to the inner uneven portion 26.

[0091] In the above embodiment, as shown in FIG. 5B , the outer concave-convex portion 16 is configured by arranging multiple convex portions 16 a (or concave portions 16 b) of the same shape. However, this is just one example. As shown in FIG. 5C , the multiple convex portions 16 a constituting the outer concave-convex portion 16 a may include multiple first convex portions 16 a 1 having a first protruding height and multiple second convex portions 16 a 2 having a second protruding height lower than the first protruding height, and these first convex portions 16 a 1 and second convex portions 16 a 2 may be formed on the outer surface 10 a. In this case, the multiple concave portions 16 b formed on the outer facing surface 10 b include multiple first concave portions 16 b 1 having a first depth corresponding to the first protruding height and multiple second concave portions 16 b 2 having a second depth corresponding to the second protruding height. The foam 30 may enter both the first concave portions 16 b 1 and the second concave portions 16 b 2. The first protrusion 16a1 slides against the mold 50, while the second protrusion 16a2 can be separated from the mold 50. This reduces the contact area of ​​the shell plate 10 with the mold 50, facilitating demolding while maintaining high bonding strength of the foam 30 to the shell plate 10. As shown in FIG. 5D , a plate portion (e.g., the first outer plate portion 13) constituting the shell plate 10 may be formed of a corrugated plate, thereby providing the outer irregularities 16 on both sides of the plate portion. If the corrugations are sinusoidal, the protrusions 16a make point or line contact with the mold 50, facilitating demolding. The same applies to the inner irregularities 26, which may be modified from the configuration shown in FIG. 6B to the configuration shown in FIG. 5C or 5D .

[0092] The present disclosure may include the following aspects: (Aspect 1) A composite structure comprising a bottom plate and a pair of side plates erected from peripheral edges of the bottom plate, comprising: an outer plate material formed of metal having an outer bottom plate portion constituting the bottom plate, outer plate portions constituting the pair of side plates, outer surfaces of the outer bottom plate portion and the outer plate portions, and an outer facing surface on the opposite side thereof, an inner plate material formed of metal having an inner bottom plate portion constituting the bottom plate, inner plate portions constituting the pair of side plates, inner surfaces of the inner bottom plate portion and the inner plate portions, and an inner facing surface on the opposite side thereof, and a foam formed of a foam material and filled between the outer facing surface and the inner facing surface, wherein the outer plate material has outer irregularities provided on the outer surface, and the inner plate material has inner irregularities provided on the inner surface. (Aspect 2) The composite structure according to Aspect 1, wherein the outer uneven portion is provided on the outer facing surface and the inner uneven portion is provided on the inner facing surface, and the foam is engaged with the outer uneven portion and the inner uneven portion. (Aspect 3) The composite structure according to Aspect 2, wherein the outer uneven portion and the inner uneven portion are formed by arranging a plurality of recesses or a plurality of protrusions. (Aspect 4) The composite structure according to any one of Aspects 1 to 3, further comprising a pair of second side plates standing upright from edges of the bottom plate, and the pair of side plates and the pair of second side plates form peripheral plates of a box body.(Aspect 5) A method for manufacturing a composite structure including a bottom plate and a pair of side plates extending from a peripheral edge of the bottom plate, the method comprising the steps of: forming, from metal, an outer plate material having an outer bottom plate portion constituting the bottom plate, outer plate portions constituting the pair of side plates, outer surfaces of the outer bottom plate portion and the outer plate portions, and an outer facing surface opposite thereto; forming, from metal, an inner bottom plate portion constituting the bottom plate, inner plate portions constituting the pair of side plates, inner surfaces of the inner bottom plate portion and the inner plate portions, and an inner facing surface opposite thereto; fitting, when a mold including a first mold having a mold recess and a second mold having a mold protrusion portion is in an open mold state with the mold protrusion portion retracted from the mold recess, the outer plate material into the mold recess and the inner plate material outwardly into the mold protrusion portion; bringing the mold into a closed mold state with the mold protrusion portion advanced into the mold recess; and filling a cavity formed between the outer facing surface and the inner facing surface with a foaming material. A method for manufacturing a composite structure, comprising the steps of heating the foam material and molding a foam between the outer plate material and the inner plate material, and opening the mold and removing the composite structure from the mold, wherein in the step of molding the outer plate material, an outer uneven portion is provided on the outer surface, and in the step of molding the inner plate material, an inner uneven portion is provided on the inner surface. (Aspect 6) The method for manufacturing a composite structure according to Aspect 5, wherein the outer uneven portion is provided on the outer opposing surface and the inner uneven portion is provided on the inner opposing surface, and in the step of heating the foam material, the foam enters and engages with the outer uneven portion and the inner uneven portion. (Aspect 7) The method for manufacturing a composite structure according to Aspect 5 or 6, wherein the outer uneven portion and the inner uneven portion are provided on surfaces of the outer surface and the inner surface that slide with the mold. (Aspect 8) The method for manufacturing a composite structure according to any one of Aspects 5 to 7, wherein the step of forming the outer plate material includes the steps of forming a flat blank having the outer bottom plate portion and the outer plate portion in an expanded state, and bending the blank so that the outer plate portion stands upright from the outer bottom plate portion, and the outer concave-convex portion is provided on the blank before the step of bending.

[0093] This application claims priority from Japanese Patent Application No. 2023-206908, filed December 7, 2023. Japanese Patent Application No. 2023-206908 is incorporated herein by reference.

[0094] REFERENCE SIGNS LIST 1 bottom plate 2 peripheral plate 3 first side plate 4 second side plate 5 flange 6 internal space 10 outer plate material 10A blank 10a outer surface 10b outer facing surface 11 outer bottom plate portion 12 outer peripheral plate portion 13 first outer plate portion 14 second outer plate portion 15 lower flange portion 16 outer concave-convex portion 16a convex portion 16a1 first convex portion 16a2 second convex portion 16b concave portion 16b1 first concave portion 16b2 second concave portion 20 inner plate material 20A blank 20a inner surface 20b inner facing surface 21 inner bottom plate portion 22 inner peripheral plate portion 23 first inner plate portion 24 second inner plate portion 26 inner concave-convex portion 26a convex portion 26b concave portion 30 foam 30A foam beads 30a Outer surface 30b Inner surface 31 Inner bottom plate portion 32 Inner peripheral plate portion 33 First inner side plate portion 34 Second inner side plate portion 35 Upper flange portion 50 Mold 51 First mold 51A Mold recess 51a First main body portion 51b Shoulder portion 52 Second mold 52A Mold protrusion portion 52a Second main body portion 52b Flange portion 53 Cavity 54 Bead port 55 Steam port 100 Composite structure

Claims

1. A composite structure comprising a bottom plate and a pair of side plates extending from the edges of the bottom plate, comprising: an outer plate material having an outer bottom plate portion constituting the bottom plate, an outer plate portion constituting the pair of side plates, outer surfaces of the outer bottom plate portion and the outer plate portion, and an outer opposing surface opposite thereto, said outer plate material being formed of metal; an inner plate material having an inner bottom plate portion constituting the bottom plate, an inner plate portion constituting the pair of side plates, inner surfaces of the inner bottom plate portion and the inner plate portion, and an inner opposing surface opposite thereto, said inner plate material being formed of metal; and a foam molded from a foaming material and filled between the outer opposing surfaces and the inner opposing surfaces, wherein the outer plate material has an outer uneven portion provided on the outer surface, and the inner plate material has an inner uneven portion provided on the inner surface.

2. The composite structure according to claim 1, wherein the outer uneven portion is provided on the outer facing surface, the inner uneven portion is provided on the inner facing surface, and the foam is engaged with the outer uneven portion and the inner uneven portion.

3. The composite structure according to claim 2, wherein the outer concave-convex portion and the inner concave-convex portion are formed by arranging a plurality of concave portions or a plurality of convex portions.

4. A composite structure according to any one of claims 1 to 3, further comprising a pair of second side panels standing upright from the edges of the bottom panel, the pair of side panels and the pair of second side panels forming peripheral panels of a box body.

5. A method for manufacturing a composite structure having a bottom plate and a pair of side plates standing up from the edges of the bottom plate, comprising the steps of: forming, from metal, an outer plate material having an outer bottom plate portion constituting the bottom plate, an outer plate portion constituting the pair of side plates, outer surfaces of the outer bottom plate portion and the outer plate portion, and an outer opposing surface on the opposite side thereof; forming, from metal, an inner plate material having an inner bottom plate portion constituting the bottom plate, an inner plate portion constituting the pair of side plates, inner surfaces of the inner bottom plate portion and the inner plate portion, and an inner opposing surface on the opposite side thereof; fitting the outer plate material into the mold recess and fitting the inner plate material outwardly into the mold protrusion when a mold including a first mold having a mold recess and a second mold having a mold protrusion is in a mold open state with the mold protrusion retracted from the mold recess; bringing the mold into a mold closed state with the mold protrusion advanced into the mold recess; and filling a cavity formed between the outer opposing surface and the inner opposing surface with a foaming material. A method for manufacturing a composite structure, comprising: a step of heating the foaming material and molding a foam between the outer plate material and the inner plate material; and a step of opening the mold and removing the composite structure from the mold, wherein in the step of molding the outer plate material, an outer uneven portion is provided on the outer surface, and in the step of molding the inner plate material, an inner uneven portion is provided on the inner surface.

6. A method for manufacturing a composite structure as described in claim 5, wherein the outer uneven portion is provided on the outer facing surface and the inner uneven portion is provided on the inner facing surface, and in the process of heating the foaming material, the foam enters and engages with the outer uneven portion and the inner uneven portion.

7. A method for producing a composite structure according to claim 5 or 6, wherein the outer uneven portion and the inner uneven portion are provided on one of the outer surface and the inner surface which slides against the mold.

8. A method for manufacturing a composite structure as described in claim 5 or 6, wherein the step of shaping the outer plate material includes a step of forming a flat blank having the outer bottom plate portion and the outer plate portion in an unfolded state, and a step of bending the blank so that the outer plate portion stands upright from the outer bottom plate portion, and the outer uneven portion is provided on the blank prior to the step of bending.

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