JP2021133581A - Hollow structure and its manufacturing method - Google Patents

Abstract

To provide a hollow structure excellent in an appearance shape at a bending part of a surface.SOLUTION: In a hollow structure made of thermoplastic resin having a hollow plate material 11 having a planar core layer 20 provided with a plurality of cells arranged side by side in the interior and a surface layer 32 bonded to at least one major surface of the hollow plate member 11, the cells S are partitioned by a side wall portion 23 extending in the thickness direction of the core layer 20, on the side surface of the hollow plate member 11, a flexure part 16 formed by bending the surface 32 connected to one main surface towards the other main surface is provided, the thickness of the flexure part 16 is thinned by the part bonded to the main surface, in a region adjacent to the flexure part 16 in the hollow plate material 11, the hollow planar material 11 is compressed in the thickness direction, and a thin part 17 in which a thickness of the hollow plate material 11 is thinned in a shape concave on one main surface side from the other main surface side is formed.SELECTED DRAWING: Figure 3

Description

The present invention relates to a hollow structure and a method for producing the same.

Since the hollow structure made of thermoplastic resin is lightweight and has appropriate rigidity, it is widely used in various fields such as furniture, building materials, vehicle interior members, etc. by molding it into various three-dimensional shapes. There is. Patent Document 1 describes that a plastic honeycomb body having a concave-convex shape is used as an interior member of a house or the like.

The interior member described in Patent Document 1 is formed by forming a desired uneven shape by press-molding a plastic honeycomb body made of a thermoplastic resin. The plastic honeycomb body includes a hollow plate-shaped embossed layer, a pair of outer surface layers joined to both main surfaces of the embossed layer, and a fiber layer made of a non-woven fabric joined on one outer surface layer.

In the invention described in Patent Document 1, the die used for press molding is provided with a receiving die having recesses and a plurality of plate-shaped hot blades having different lengths according to the shape of the receiving die. It has a stamp. In press molding, the plastic honeycomb body is placed on the receiving die with the fiber layer facing down, and the pressing die is lowered. The plastic honeycomb body is pushed by a plurality of hot blades and deformed along the shape of the concave portion of the receiving mold to form a concave-convex shape, and the hot blades are on the outer surface layer side where the fiber layers are not joined. A plurality of concave grooves are formed. Around the concave groove, the resin is melted by the hot blade to form a molten side wall, and in the portion other than the concave groove, the hollow portion is held without buckling of the side wall of the plastic honeycomb body.

Japanese Patent No. 2887088

By the way, when an uneven shape is formed on a hollow structure in which a plurality of cells are arranged side by side, a bent portion bent so as to be stretched during press molding is formed on the surface layer (surface layer). The surface layer may become thin at the bent portion. Then, the bent portion of the surface layer is supported by the side wall in the portion where the side wall of the cell exists and its shape is maintained, but in the hollow portion where the side wall of the cell does not exist, the stretched surface layer becomes the hollow portion of the cell. The shape is like a dent. As a result, unevenness is formed on the surface of the bent portion of the hollow structure.

Even in the plastic honeycomb body described in Patent Document 1, when the recess is formed by being pushed by the heat blade of the push die, the fiber layer is bent downward and stretched, so that the fiber layer is bent at the bent portion. , The thickness of the non-woven fabric tends to be thin. In this plastic honeycomb body, although the molten sidewall is formed in the embossed layer by the hot blade, a hollow portion exists in the portion where the side wall of the embossed layer remains without buckling. A dent will be generated in the non-woven fabric. As a result, the appearance shape of the bent portion of the plastic honeycomb body is deteriorated.

Such a problem is particularly remarkable when the depth of the recess is deep and the tensile width of the surface layer at the bent portion is large, or when the bending angle at the bent portion is steep.
The present invention has been made to solve these conventional problems, and an object of the present invention is to provide a hollow structure having a good appearance shape at a bent portion of a surface layer.

In order to solve the above problems, the present invention includes a hollow plate material having a plate-shaped core layer in which a plurality of cells are arranged side by side, and a surface layer joined to at least one main surface of the hollow plate material. A hollow structure made of a thermoplastic resin, wherein the cell is partitioned by a side wall portion extending in the thickness direction of the core layer, and the side surface of the hollow plate material is joined to one of the main surfaces. A bent portion is provided in which the surface layer is bent toward the other main surface, and the thickness of the bent portion is thinner than the portion joined to the main surface. In the region adjacent to the portion, the hollow plate material is compressed in the thickness direction, and a thin-walled portion in which the thickness of the hollow plate material is reduced in a shape recessed from the other main surface side to the one main surface side is formed. It is formed.

The bent portion provided on the side surface of the hollow plate material is formed by bending the surface layer joined to one main surface toward the other main surface. Further, in the core layer, cells are partitioned by side wall portions extending in the thickness direction thereof. Therefore, in the core layer, in the portion where the bent portion of the surface layer is provided, a portion having a side wall portion and a hollow portion having no side wall portion are mixed.

According to the above configuration, in the region of the hollow plate material adjacent to the bent portion of the surface layer, the hollow plate material is compressed in the thickness direction and has a shape recessed from the other main surface side to the one main surface side. A thin wall portion is formed. In the thin-walled portion, since the hollow plate material is compressed, the side wall portion extending in the thickness direction of the core layer is buckled or bent in the middle. As a result, in the thin-walled portion, the density of the thermoplastic resin in the hollow portion is higher than that in the portion other than the thin-walled portion. Therefore, in the bent portion where the side wall portion exists, the surface layer is supported by the side wall portion and its shape is maintained, while the surface layer is recessed toward the hollow portion even in the portion where the side wall portion does not exist. Is suppressed. The formation of irregularities on the surface of the bent portion of the hollow structure is suppressed, and a hollow structure having a good appearance shape at the bent portion of the surface layer can be obtained.

In the above configuration, it is preferable that the inner surface of the bent portion is supported by the side wall portion more than the inner surface of the surface layer other than the bent portion.
According to the above configuration, the side wall portion extending in the thickness direction of the core layer is buckled or bent to have a higher density than the portion other than the thin-walled portion, and is formed on the inner surface of the bent portion adjacent to the thin-walled portion. Has many such side wall portions that are in contact with each other or joined. Since the inner surface of the bent portion is supported by more side wall portions than the inner surface of the surface layer other than the bent portion, the shape of the bent portion can be easily maintained. A hollow structure having a good appearance shape at the bent portion of the surface layer can be obtained.

In order to solve the above problems, the present invention is a method for manufacturing the above-mentioned hollow structure, which includes a joining step of joining the surface layer to the hollow plate material to form an intermediate, and an upper die and a lower die. In the mold, the intermediate body is pressed to form the bent portion and the thin-walled portion, and the upper mold is formed with a first convex portion having a protruding length equal to or larger than the thickness of the hollow plate material. In the lower mold, a second convex portion having a protrusion length smaller than the thickness of the hollow plate material is formed at a position adjacent to the first convex portion when the mold is fastened. The bent portion is formed by pressing the intermediate body with the first convex portion, and the thin-walled portion is formed by pressing the intermediate body with the second convex portion.

According to the above configuration, when the hollow plate material is pressed by the first convex portion formed in the upper mold and having a protruding length equal to or larger than the thickness of the hollow plate material, the surface layer joined to one main surface of the hollow plate material becomes the other. A bent portion is formed by bending so as to be stretched toward the main surface side. At this time, since the other main surface side of the hollow plate material is pressed by the second convex portion which is formed in the lower mold and has a protrusion length shorter than that of the first convex portion, when the bent portion is formed, the vicinity of the bent portion is pressed. , It is in a state of being supported from the other main surface side by the second convex portion. Therefore, even if the surface layer joined to one main surface side is bent so as to be stretched, the bent portion is suppressed from being dented toward the hollow portion of the core layer. It is possible to easily suppress the occurrence of an uneven shape in the bent portion.

In the above configuration, a heating step for heating the hollow plate material and the surface layer is provided, and in the pressing step, the hollow plate material and the surface layer in a heated state are pressed in the mold to form the bent portion and the thin wall portion. It is preferable that the molding of the above is performed at the same time as the joining step.

According to the above configuration, joining of the hollow plate material and the surface layer and molding of the sealing portion and the thin-walled portion can be performed at the same time. The manufacturing process can be simplified and the manufacturing cost can be suppressed.
In the above configuration, the hollow plate material and the surface layer are heated, and in the joining step, the heated surface layer is joined to the heated hollow plate material to form the intermediate body, and the pressing step is performed. Then, it is preferable to press the intermediate body in a heated state in the mold to form the bent portion and the thin-walled portion.

According to the above configuration, in the pressing step, an intermediate in which the surface layer is bonded to the hollow plate material is pressed in a heated state. Therefore, the joining accuracy between the hollow plate material and the surface layer is improved.

According to the present invention, a hollow structure having a good appearance shape at a bent portion of the surface layer can be obtained.

FIG. 3 is a perspective view of a tool box in which a storage plate, which is a hollow structure of the first embodiment, is housed. (A) is a perspective view of the accommodating plate, and (b) is a sectional view taken along line AA in (a). (A) is a perspective view taken along the line BB of FIG. 2 (a), and (b) is a cross-sectional view taken along the line BB of FIG. 2 (a). (A) is a perspective view of the core layer, (b) is a β-β line sectional view in (a), and (c) is a γ-γ line sectional view in (a). (A) is a perspective view of a sheet material constituting the core layer, (b) is a perspective view showing a state in which the sheet material is being folded, and (c) is a perspective view showing a state in which the sheet material is folded. The figure explaining the method of manufacturing a hollow plate material. (A)-(f) is a figure explaining the method of manufacturing the accommodating plate. The partial perspective view of the shelf board which is the hollow structure of 2nd Embodiment seen from the lower surface. (A)-(d) is a figure explaining the method of manufacturing a shelf board. It is a perspective view of the sheet material constituting the core layer of the modified example, (a) is a perspective view of the sheet material constituting the core layer, (b) is a perspective view showing a state in which the sheet material is being folded, (c). ) Is a perspective view showing the folded state of the sheet material. (A) to (d) are diagrams for explaining the accommodation plate of the modified example.

(First Embodiment)
The hollow structure of the first embodiment will be described with reference to FIGS. 1 to 4.
The hollow structure of the first embodiment is used as a storage plate 7 provided inside the tool box 1 for storing tools.

As shown in FIG. 1, the tool box 1 is configured such that a lid portion 3 is rotatably attached to a rectangular parallelepiped main body portion 2. The lid portion 3 is provided with an engaging portion 4, and the main body portion 2 is provided with an engaged portion 5. By engaging the engaging portion 4 with the engaged portion 5, the main body is provided. The portion 2 is closed by the lid portion 3.

On the inner right side of the tool box 1 shown in FIG. 1, a plurality of storage trays 6 are stored in a state in which a plurality of storage trays 6 are stacked in the vertical direction of the main body 2. A storage plate 7 is stored on the left side of the storage tray 6. The accommodating plate 7 is placed on a support portion (not shown) integrally projected on the peripheral wall of the main body portion 2 and supported in a positioned state. The accommodating plate 7 has a configuration for stably accommodating an irregularly shaped and relatively bulky tool such as an electric drill, and the accommodating plate 7 of the present embodiment is provided for accommodating an electric drill. ing. The accommodating plate 7 is formed in a substantially rectangular plate shape of about 25 cm × about 30 cm, and its thickness is about 2 cm.

Here, the upper and lower parts of the accommodating plate 7 mean the upper and lower parts when the electric drill is stored in the tool box 1 in a state where the electric drill can be accommodated in the accommodating plate 7. Then, as shown in FIG. 2, in this state, the surface located above the accommodating plate 7 is referred to as the upper surface 7a, and the surface located below is referred to as the lower surface 7b.

As shown in FIG. 2B, the accommodating plate 7 is formed by shaping a recess 12 into a substantially rectangular plate-shaped hollow plate-like body 10 in which a plurality of cells S are arranged side by side.
First, the structure of the hollow plate-like body 10 constituting the accommodating plate 7 will be described. The hollow plate-like body 10 includes a hollow plate member 11 and decorative layers 32 and 42 as surface layers joined to both main surfaces thereof.

As shown in FIGS. 3A and 3B, the hollow plate material 11 includes a core layer 20 and skin layers 31 and 41 joined to both main surfaces thereof. The core layer 20 and the skin layers 31 and 41 constituting the hollow plate material 11 are made of a conventionally known thermoplastic resin. Examples of the thermoplastic resin constituting the core layer 20 and the skin layers 31 and 41 include polypropylene resin, polyamide resin, polyethylene resin, acrylonitrile-butadiene-styrene copolymer resin, acrylic resin, polybutylene terephthalate resin and the like. .. The core layer 20 and the skin layers 31 and 41 are preferably made of the same material as a thermoplastic resin, and are made of polypropylene resin in this embodiment. Further, the melt mass flow rate (MFR) of the thermoplastic resin material constituting the skin layers 31 and 41 is smaller than the MFR of the thermoplastic resin material constituting the core layer 20.

As shown in FIGS. 4A to 4C, the core layer 20 is formed by folding a single sheet material obtained by molding a sheet made of a thermoplastic resin into a predetermined shape. The thickness of the sheet material constituting the core layer 20 is preferably about 0.3 mm to 1.0 mm, and in the present embodiment, it is about 0.5 mm.

As shown in FIGS. 4A to 4C, the core layer 20 is erected between the upper wall portion 21, the lower wall portion 22, and the upper wall portion 21 and the lower wall portion 22, and has a hexagonal tubular shape. It is composed of a side wall portion 23 constituting a wall portion. A hexagonal columnar cell S is partitioned inside the core layer 20 by the upper wall portion 21, the lower wall portion 22, and the side wall portion 23.

In the cell S partitioned inside the core layer 20, there are a first cell S1 and a second cell S2 having different configurations. As shown in FIG. 4B, the upper end of the first cell S1 is blocked by the upper wall portion 21, and the lower end thereof is opened downward without being blocked. That is, in the first cell S1, the upper surface 20a of the core layer 20 is composed of the upper wall portion 21, and the lower surface 20b is composed of the lower end edge of the side wall portion 23.

On the other hand, as shown in FIG. 4C, the lower end of the second cell S2 is blocked by the lower wall portion 22, and the upper end thereof is opened upward without being blocked. That is, in the second cell S2, the lower surface 20b of the core layer 20 is composed of the lower wall portion 22, and the upper surface 20a is composed of the upper end edge of the side wall portion 23.

As shown in FIG. 4A, the first cell S1 and the second cell S2 are arranged so that the first cell S1 or the second cell S2 are adjacent to each other in the X direction to form a row. Further, in the Y direction orthogonal to the X direction, the rows of the first cell S1 and the rows of the second cell S2 are arranged alternately. That is, the second cell S2 in which the hollow portion is opened upward without closing the upper end and the first cell S1 in which the upper end is closed by the upper wall portion 21 and the hollow portion is not opened upward are Y. It will be arranged alternately in the direction. The core layer 20 has a honeycomb structure as a whole due to the first cell S1 and the second cell S2.

As shown in FIGS. 4 (b) and 4 (c), between the adjacent first cells S1 and between the adjacent second cells S2 are perpendicular to the upper wall portion 21 and the lower wall portion 22. It is formed and is partitioned by a side wall portion 23 having a two-layer structure including a first side wall portion 23a and a second side wall portion 23b. On the other hand, the adjacent first cell S1 and second cell S2 are partitioned by a side wall portion 23 having a one-layer structure formed perpendicular to the upper wall portion 21 and the lower wall portion 22.

As shown in FIGS. 4 (b) and 4 (c), the first side wall portion 23a and the second side wall portion 23b are heat-sealed to each other at the upper end edge and the lower end edge thereof. This is because, in the core layer forming step described later, the folded core layer 20 is heated and the thermoplastic resin is thermally melted at the upper end edge and the lower end edge of the side wall portion 23, so that the first side wall of the two-layer structure is formed. This is because the upper end edge and the lower end edge of the portion 23a and the second side wall portion 23b are joined.

Further, the first side wall portion 23a and the second side wall portion 23b are joined to each other via a joining portion 23c at an intermediate portion in the vertical direction. The joint portion 23c of the present embodiment is composed of an adhesive layer, and the entire surface of the first side wall portion 23a and the entire surface of the second side wall portion 23b are joined (bonded) via the joint portion 23c (adhesive layer). .. This is because the low melting point film made of the hot melt adhesive is supplied in a molten state in the core layer forming step described later, so that the low melting point film is adhered to the first side wall portion 23a and the second side wall portion 23b. This is due to the formation of the joint portion 23c.

Therefore, the first side wall portion 23a and the second side wall portion 23b are formed by heat-melting and heat-sealing the thermoplastic resin with the joint portion 23c bonded via the adhesive layer at the upper end edge and the lower end edge thereof. Is in a state of coexistence.

The material of the adhesive constituting the adhesive layer is conventionally known and is not particularly limited. For example, in the case of the hollow plate-like body 10 of the present embodiment in which the core layer 20 and the skin layers 31 and 41 are made of polypropylene resin, the adhesive is compatible with the polypropylene resin and is more compatible with the skin layers 31 and 41. It is a hot melt adhesive composed of a low melting point resin. Examples of other hot-melt adhesives include those composed of ethylene-vinyl acetate copolymer (EVA) resin, polyester resin, polyamide resin and the like. The adhesive is defined as an adhesive in which the adherends are fixed to each other by being cured by heat, light, a chemical reaction, moisture, or the like.

As shown in FIGS. 3A and 3B, the skin layers 31 and 41 are joined to the upper surface of the upper wall portion 21 of the core layer 20 and the lower surface of the lower wall portion 22, respectively. Specifically, the skin layer 31 is joined to the upper end of the upper wall portion 21 of the first cell S1 and the side wall portion 23 of the second cell S2 on the upper surface 20a of the core layer 20. Further, the skin layer 41 is joined to the lower end of the side wall portion 23 of the first cell S1 and the lower wall portion 22 of the second cell S2 on the lower surface 20b of the core layer 20. Therefore, the upper surface of the hollow plate material 11 has a two-layer structure composed of the upper wall portion 21 of the core layer 20 and the skin layer 31 in the first cell S1, and has a one-layer structure of only the skin layer 31 in the second cell S2. Has been done. Further, the lower surface of the hollow plate material 11 has a one-layer structure consisting of only the skin layer 41 in the first cell S1, and a two-layer structure composed of the lower wall portion 22 of the core layer 20 and the skin layer 41 in the second cell S2. Has been done.

As shown in FIGS. 3A and 3B, the decorative layers 32 and 42 are provided to impart designability to the outer surface of the accommodating plate 7. The decorative layers 32 and 42 are joined to the hollow plate material 11 via adhesive layers (not shown), respectively. The decorative layer 32 is joined to the skin layer 31, and the decorative layer 42 is joined to the skin layer 41.

Examples of the materials of the decorative layers 32 and 42 include conventionally known synthetic resins, synthetic leathers, synthetic fibers, metals, natural leathers, natural fibers, carbon fibers, foam materials and the like. Examples of the form include non-woven fabrics, woven fabrics, knitted fabrics, synthetic resin sheets (for example, smooth stretched sheets made by stretching synthetic resin), metal sheets and the like. Further, from the viewpoint of imparting designability, patterns and characters may be printed or may be composed of fibers of different colors. The decorative layers 32 and 42 of the present embodiment are non-woven fabric sheets. The thickness of the decorative layers 32 and 42 is preferably about 0.3 mm to 1.0 mm, and in the present embodiment, it is about 0.5 mm.

As shown in FIGS. 2A and 2B, a recess 12 recessed downward from the upper surface 7a is formed in a substantially central portion of the accommodating plate 7. The recess 12 is recessed in the shape of an electric drill, and in the present embodiment, the depth of the recess 12 from the upper surface 7a of the accommodating plate 7 is about 4 cm. That is, the recess 12 is recessed more than the thickness of the accommodating plate 7, so that the bottom wall 14 of the recess 12 is located below the lower surface 7b of the accommodating plate 7. The depth of the recess 12 is preferably about 1.5 to 4 times, more preferably about 2 to 4 times, and even more preferably about 2 to 3 times the thickness of the accommodating plate 7. The upper surface 7a and the lower surface 7b of the accommodating plate 7 are formed as flat surfaces except for the recess 12.

As shown in FIGS. 2A and 2B, a side wall 13 and a bottom wall 14 are formed in the recess 12. The pair of side walls 13 facing each other in the recess 12 are formed as steep slopes that incline toward each other toward the bottom. The inclination angle θ1 of the side wall 13 with respect to the upper surface 7a of the accommodating plate 7 is preferably 70 ° or more, more preferably 80 ° or more, and further preferably 85 ° or more. As the inclination angle approaches 90 °, the electric drill can be stably housed in the recess 12.

Further, as shown in FIGS. 3A and 3B, an R-shaped curved portion 15 is formed at the boundary portion between the upper surface 7a and the side wall 13 of the accommodating plate 7 in the recess 12. The radius of curvature of the curved portion 15 is about 1 to 5 mm.

As shown in FIGS. 3 (a) and 4 (a), the accommodating plate 7 is formed so that its longitudinal direction coincides with the X direction of FIG. 4 (a). Therefore, assuming that the curved portion 15 shown on the right side of FIG. 3A is the curved portion 15a, the first cell S1 and the second cell S2 are alternately arranged in the extending direction of the curved portion 15a. .. That is, in the hollow plate material 11 at the curved portion 15a, the second cell S2 having only the skin layer 31 on the upper surface and the first cell S1 having the upper surface having a two-layer structure of the upper wall portion 21 and the skin layer 31 are alternately arranged. Will be there.

The concave portion 12 is a portion formed by pressing the hollow plate-shaped body 10 with the convex portion 81c of the upper mold 81 in the pressing step described later. Therefore, as shown in FIG. 3B, in the portion from the curved portion 15 of the recess 12 to the region 13A of the side wall 13, the upper wall portion 21 of the core layer 20 and the skin layer 31 are melt-integrated in the hollow plate material 11. The side surface of the core layer 20 is sealed in a stretched state. In the portion from the curved portion 15 to the region 13A of the side wall 13, the melt-integrated hollow plate member 11 has a solid state with almost no gap as a whole.

Further, in the portion of the side wall 13 in the region 13B, the hollow plate material 11 includes a portion in which the side wall portion 23 of the core layer 20 is compressed in the thickness direction, an upper wall portion 21, a lower wall portion 22, and a skin layer of the core layer 20. 31 and 41 are in a stretched state in which they are melted and integrated. In the portion of the region 13B, the hollow plate material 11 melted and integrated has a solid state with almost no gap as a whole.

In the portion from the curved portion 15 to the region 13A, the upper wall portion 21 and the skin layer 31 are in a state of being melted and integrated and stretched, whereas in the portion of the region 13B, the side wall portion 23 of the core layer 20 is thick. The portion compressed in the direction, the upper wall portion 21, the lower wall portion 22, and the skin layers 31 and 41 are melt-integrated and stretched. Therefore, the thickness of the melt-integrated hollow plate material 11 from the curved portion 15 to the region 13A is thinner than that of the region 13B.

In the bottom wall 14 of the recess 12, the portion where the side wall portion 23 of the core layer 20 is compressed in the thickness direction, the upper wall portion 21, the lower wall portion 22, and the skin layers 31, 41 of the core layer 20 are melted and integrated. It is in a compressed state. In the bottom wall 14, the hollow plate material 11 has a solid state with almost no gap as a whole. The melt-integrated hollow plate material 11 has the same thickness as the portion of the bottom wall 14 and the portion of the region 13B.

On the other hand, the decorative layer 32 joined to the upper side of the hollow plate material 11 is in a state of being pulled and stretched by downward pressing by the convex portion 81c of the upper die 81 in the pressing process described later. Therefore, as shown in FIG. 3B, the portion of the recess 12 from the curved portion 15 to the region 13A of the side wall 13 is thicker than the portion joined to the skin layer 31 on the upper surface 20a side of the core layer 20. It's getting thinner.

The portion from the curved portion 15 to the region 13A where the decorative layer 32 is stretched and thinned seals the side surface of the core layer 20 together with the portion where the upper wall portion 21 and the skin layer 31 are melted and integrated and stretched. ing. In the accommodation plate 7 which is the hollow structure of the present embodiment, the portion of the decorative layer 32 as the surface layer from the curved portion 15 to the region 13A corresponds to the bent portion referred to in the claims. The bent portion 16 in the decorative layer 32 is bent from the decorative layer 32 joined to one main surface of the hollow plate material 11 toward the other main surface side, and is melt-integrated with respect to the side surface of the core layer 20. It is abutted or joined via the hollow plate material 11. The thickness of the decorative layer 32 joined to the skin layer 31 on the upper surface 20a side of the core layer 20 is about 0.5 mm, whereas the thickness of the bent portion 16 in the decorative layer 32 is about 0.2 mm. Is.

Further, even in the region from the region 13B of the side wall 13 of the recess 12 to the bottom wall 14, the decorative layer 32 is in a stretched state, and the thickness thereof is about the same as the thickness in the region 13A. It is about 0.2 mm.

Similarly, the decorative layer 42 joined to the lower side of the hollow plate material 11 is also in a state of being pulled and stretched by downward pressing by the convex portion 81c of the upper die 81. Therefore, as shown in FIG. 3B, in the portion of the side wall 13 from the region 13B to the bottom wall 14, the decorative layer 42 is more than a portion joined to the skin layer 41 on the lower surface 20b side of the core layer 20. Its thickness is getting thinner. The thickness of the stretched decorative layer 42 in the portion from the region 13B to the bottom wall 14 is about the same as the thickness of the decorative layer 32 in the bent portion 16, and is about 0.2 mm.

In the portion from the region 13B of the side wall 13 of the recess 12 to the bottom wall 14, the hollow plate material 11 that has been melt-integrated is integrated so that the stretched portions of the decorative layers 32 and 42 sandwich the hollow plate material 11. .. Its thickness is thicker than the portion of the side wall 13 in the region 13A, whereby the strength of the recess 12 is maintained.

As shown in FIGS. 3A and 3B, a thin-walled portion 17 having a recessed shape from below is formed in a region of the accommodating plate 7 adjacent to the side wall 13 of the recess 12. The thin portion 17 is formed along the side wall 13 of the recess 12 so as to surround the recess 12 over the entire circumference of the recess 12, and its width L1 is about 1 cm. Further, the lower surface 17a of the thin portion 17 is formed as a flat surface.

The thin-walled portion 17 is a portion formed by pressing the hollow plate-shaped body 10 with the convex portion 82c of the lower mold 82 in the pressing step described later, and the thickness thereof is about half the thickness of the hollow plate-shaped body 10. It is about 1 cm. Therefore, as shown in FIG. 3B, in the thin-walled portion 17, the side wall portion 23 of the core layer 20 is compressed in the thickness direction, and is buckled or bent in the middle of the compression. The side wall portion 23 is buckled or bent at one or two positions in the vertical direction, for example. As a result, in the thin-walled portion 17, the density of the thermoplastic resin in the hollow portion of the core layer 20 is higher than that in the portion other than the thin-walled portion 17. Further, many of these side wall portions 23 are in contact with or joined to the inner surface of the bent portion 16 adjacent to the thin wall portion 17 via the upper wall portion 21 of the hollow plate material 11 and the skin layer 31.

As shown in FIGS. 3A and 3B, end faces 7c are formed at all the ends of the accommodating plate 7. The end face 7c is a portion formed by pressing the hollow plate-shaped body 10 toward the lower mold 82 in the pressing step described later. Therefore, as shown in FIG. 3B, in the end surface 7c, the lower wall portion 22 of the core layer 20 and the skin layer 41 are melted and integrated, and are bent and stretched toward the decorative layer 32 side. It is in a state. Further, the decorative layer 42 is also in a state of being bent and stretched toward the decorative layer 32 side. On the other hand, at all the ends of the accommodation plate 7, the upper skin layer 31 and the decorative layer 32 extend in the horizontal direction without being bent.

A compression portion 20c in which the hollow plate material 11 is compressed in the thickness direction and fused and integrated is formed between the tip portion where the decorative layer 42 is stretched and the decorative layer 32. In the compression unit 20c, the hollow plate material 11 is crushed and compressed in the thickness direction, so that the cell S is deformed to such an extent that its shape cannot be identified. The melt-integrated thermoplastic resin is in a dense state, and is in a solid state with almost no gaps.

As shown in FIG. 3B, the end surface 7c is formed as a steep slope that inclines inward toward the accommodating plate 7 toward the lower side. The inclination angle θ2 of the end surface 7c with respect to the lower surface 7b of the accommodating plate 7 is preferably 70 ° or more, more preferably 80 ° or more, and further preferably 85 ° or more. As the inclination angle approaches 90 °, the accommodating plate 7 can be stably supported by the supporting portion when the accommodating plate 7 is placed on the supporting portion formed so as to project from the peripheral wall of the tool box 1.

Further, an R-shaped curved portion 43 is formed at the boundary portion between the lower surface 7b and the end surface 7c of the accommodating plate 7. The radius of curvature of the curved portion 43 is about 1 to 5 mm.
Next, the operation of the storage plate 7 of the present embodiment will be described.

The accommodating plate 7 is for accommodating an electric drill in a substantially central portion of a hollow plate-like body 10 in which decorative layers 32 and 42 as surface layers are joined to a hollow plate material 11 in which a plurality of cells S are arranged side by side. A recess 12 is formed. The recess 12 is recessed in the shape of an electric drill, and its depth is about 4 cm. Therefore, when the electric drill is housed in the recess 12, the electric drill is stably held in the recess 12 without rattling. Further, at all the end portions of the accommodating plate 7, the end surface 7c in which the lower skin layer 41 and the decorative layer 42 are bent upward is formed as a steep slope. Therefore, the accommodating plate 7 is stably supported on the support portion in the tool box 1.

As shown in FIG. 3B, in the portion from the curved portion 15 of the recess 12 to the region 13A of the side wall 13, the hollow plate material 11 is stretched by melting and integrating the upper wall portion 21 and the skin layer 31 of the core layer 20. The side surface of the core layer 20 is sealed in this state. In the region adjacent to the curved portion 15, the core layer 20 in the vicinity of the recess 12 has a portion in which the side wall portion 23 is compressed in the thickness direction and melted and integrated together with the upper wall portion 21 and the skin layer 31, but the core layer The hollow structure of 20 is still retained. Then, in the core layer 20 in which the hollow structure is retained, the side wall portion 23 may be in a state of being inclined toward the recess 12 side. Even if the side wall portion 23 is in an inclined state, the side wall portion 23 maintains a certain level of strength.

Further, in the portion of the recess 12 from the curved portion 15 to the region 13A of the side wall 13, a bent portion 16 that is pulled and stretched is formed in the decorative layer 32. By stretching the decorative layer 32, a force that dents toward the hollow structure portion of the core layer 20 acts on the bent portion 16. In particular, in the curved portion 15a, since the first cell S1 and the second cell S2 are alternately arranged, the thickness of the upper surface of the hollow plate material 11 is such that the thin portion and the thick portion are alternately arranged. Therefore, in the bent portion 16, the degree of denting differs depending on the thickness of the upper surface of the hollow plate material 11, and a force that causes unevenness on the surface of the bent portion 16 acts.

On the other hand, in the region adjacent to the bent portion 16, a thin-walled portion 17 having a concave shape from below is formed over the entire circumference of the recess 12 so as to surround the recess 12 along the side wall 13 of the recess 12. Has been done. In the thin-walled portion 17, the side wall portion 23 of the core layer 20 is compressed in the thickness direction and buckled or bent in the middle, and the density of the thermoplastic resin in the hollow portion of the core layer 20 is increased in the thin-walled portion 17. It is higher than the other parts. Further, many side wall portions 23 that have been buckled or bent are in contact with or joined to the inner surface of the bent portion 16 via the upper wall portion 21 of the hollow plate material 11 and the skin layer 31.

Therefore, even if a hollow portion remains in the core layer 20 in the region adjacent to the bent portion 16, the bent portion 16 is buckled or bent via the upper wall portion 21 of the hollow plate material 11 and the skin layer 31. It will be supported by the loose side wall portion 23. By being supported by the thin-walled portion 17, even if a force that causes unevenness is exerted on the surface of the bent portion 16, the generation is suppressed. Even if there is a difference in the thickness of the upper surface of the hollow plate material 11 at the bent portion 16 due to the mixture of the first cell S1 and the second cell S2, the appearance shape on the surface of the bent portion 16 Becomes good. Further, in the region adjacent to the bent portion 16, the side wall portion 23 may be in an inclined state at the hollow portion in the core layer 20 in which the hollow structure is retained, but the side wall portion 23 maintains a certain level of strength. Has been done. This also prevents the bent portion 16 from being supported by the side wall portion 23 and causing irregularities on the surface thereof.

As shown in FIG. 3A, in the curved portion 15 extending linearly (for example, the curved portion 15a extending in the substantially vertical direction of the paper surface in FIG. 1), the decorative layer is formed when the recess 12 is formed in the pressing step. The 32 is more easily pulled and stretched at the central portion than both ends of the curved portion 15. Therefore, in the central portion of the curved portion 15, the thickness of the bent portion 16 tends to be thin, and the central portion is more likely to be drawn inward of the cell S than both end portions. In this respect, since the bent portion 16 is in a state of being supported by the thin-walled portion 17 over the entire length of the curved portion 15, the occurrence of unevenness in the central portion of the curved portion 15 is suppressed and the bent portion 16 is linear. It is suppressed that a difference in the appearance shape is generated in the entire extending curved portion 15.

The portion from the region 13B of the side wall 13 of the recess 12 to the bottom wall 14 is formed in a solid state with almost no gap as a whole by compressing the hollow plate material 11 in the thickness direction and melting and integrating them. Therefore, even if some kind of impact is applied to the recess 12, the side wall 13 and the bottom wall 14 of the recess 12 have enough strength to withstand the impact and are not easily affected by the impact. Deformation in the recess 12 is suppressed.

Further, in the region 13A of the side wall 13, the region 13B of the side wall 13, the bottom wall 14, and the compression portion 20c, the hollow plate material 11 is compressed in the thickness direction and fused and integrated to form a solid state with almost no gap. It has become. Therefore, in these portions, the density of the thermoplastic resin is higher than that of the other portions, and the strength is higher than that of the other portions. Further, even in the region adjacent to the curved portion 15 of the boundary portion between the upper surface 7a and the side wall 13 of the accommodating plate 7, there is a portion where the hollow plate material 11 is compressed in the thickness direction and fused and integrated in the vicinity of the recess 12. These portions also have a higher density of the thermoplastic resin than the uncompressed portions and have high strength.

That is, in the accommodating plate 7, the density of the thermoplastic resin increases according to the degree to which the hollow plate material 11 is compressed in the thickness direction. Specifically, the density of the thermoplastic resin is the highest in the side wall 13, the bottom wall 14, and the compression portion 20c, which are the portions where the hollow plate material 11 is most compressed to be almost solid, and the thin portion 17 is the next highest. , The density is the lowest in the portion where the hollow plate material 11 is not compressed.

Next, a method of manufacturing the accommodating plate 7 will be described together with its operation according to FIGS. 5 to 7.
The method for manufacturing the accommodating plate 7 is a core layer forming step of forming the core layer 20 from one sheet material 100, and a first joining step of joining the skin layers 31 and 41 to the core layer 20 to form the hollow plate material 11. , A heating step of heating the hollow plate material 11 and the decorative layers 32 and 42, a second joining step of joining the decorative layers 32 and 42 to the hollow plate material 11 to form the hollow plate-like body 10, the hollow plate-like body 10. It can be divided into a pressing process of forming an intermediate body 50 having a bent portion 16 and a thin-walled portion 17 by pressing in a mold, and a post-processing step of adjusting the shape of the end face of the intermediate body 50 to obtain a storage plate 7.

First, a core layer forming step for forming the core layer 20 and a first joining step for forming the hollow plate material 11 will be described. In the present embodiment, the core layer forming step and the first joining step are carried out in a series of steps by the apparatus T as shown in FIG.

In FIG. 6, the device T is shown as a schematic diagram, with the left side being the upstream side and the right side being the downstream side. In the device T, in order from the upstream side, a sheet roll 61 around which a sheet made of a thermoplastic resin is wound, a vacuum forming drum 62 for forming the sheet material 100, and an adhesive for applying the adhesive to the sheet material 100 are applied. The transfer roll 63, the first conveyor 64 for the core layer forming process, the second conveyor 65 for forming the joint portion 23c on the side wall portion 23 of the core layer 20, and the sheet as the raw material for the skin layers 31 and 41. A wound sheet roll 66, 67 and a third conveyor 68 for the first joining step are arranged.

As shown in FIG. 6, a flat sheet which is a material of the sheet material 100 in the core layer forming step is wound around the sheet roll 61. The sheet unwound from the sheet roll 61 is supplied to the vacuum forming drum 62 and formed into the sheet material 100 having a predetermined uneven shape. The vacuum forming drum 62 is pivotally supported so that it can be driven to rotate and can be heated to a predetermined temperature. The rotation speed of the vacuum forming drum 62 is set to be equal to the rotation speed of the sheet roll 61. Further, a cylindrical molding die is attached to the outer peripheral portion of the vacuum forming drum 62, and is configured to be able to evacuate through a through hole formed in the forming die (not shown). ). The sheet supplied to the vacuum forming drum 62 is shaped into the shape of a forming die attached to the outer peripheral portion thereof, and the sheet material 100 is formed.

As shown in FIG. 5A, in the sheet material 100 formed by the molding die, the first bulging portion 110 and the second bulging portion 120 forming a strip shape are alternately arranged in the width direction (Y direction). Have been placed. The first bulging portion 110 is formed in a shape protruding upward, and the second bulging portion 120 is formed in a shape protruding downward. The first bulging portion 110 and the second bulging portion 120 are alternately arranged so as to extend in the X direction. The first bulging portion 110 when the sheet material 100 is viewed from the top and the second bulging portion 120 when the sheet material 100 is viewed from the bottom have the same shape and are displaced by 1/2 pitch in the X direction. Is formed in.

The first bulging portion 110 is composed of an upper surface 110a, a pair of side surfaces 110b, and a pair of end surfaces 110c, and has a trapezoidal shape obtained by dividing a regular hexagon into two by the longest diagonal line in the Y direction. The pair of end faces 110c are formed at the positions of the folding lines P shown in FIG. 5A. The angle between the end face 110c and the top surface 110a is about 90 °.

On the other hand, the second bulging portion 120 is composed of a lower surface 120a, a pair of side surfaces 120b, and a pair of end surfaces 120c, and has a trapezoidal shape obtained by dividing a regular hexagon into two by the longest diagonal line. .. The pair of end faces 120c are formed at the positions of the folding lines Q shown in FIG. 5A. The angle formed by the end surface 120c and the lower surface 120a is about 90 °. The length of the second bulging portion 120 in the X direction, that is, the length between the pair of end faces 120c is the same as the length of the first bulging portion 110 in the X direction, that is, the length between the pair of end faces 110c. be. The end face 120c of the second bulging portion 120 is located at the center of the first bulging portion 110 in the X direction. The side surface 110b of the first bulging portion 110 and the side surface 120b of the second bulging portion 120 are separated for convenience of explanation, but have the same configuration.

As shown in FIG. 6, the sheet material 100 is transported between the pair of transport rolls 63. The rotation speed of the transfer roll 63 is set to be equal to the rotation speed of the vacuum forming drum 62. Further, a low melting point film (not shown) made of a hot melt adhesive is sequentially supplied to the upstream side of the transport roll 63. As a result, a hot melt adhesive in which the low melting point film is in a molten state is applied to the surface of the sheet material 100 that has passed between the pair of transport rolls 63. The adhesive is applied as a thin film on the entire upper surface 110a of the first bulging portion 110 on the upper surface of the sheet material 100, and as a thin film on the entire lower surface 120a of the second bulging portion 120 on the lower surface of the sheet material 100. Is applied to.

As shown in FIG. 6, the sheet material 100 coated with the adhesive is supplied to the first conveyor 64 for the core layer forming step and formed into the shape of the core layer 20. The sheet material 100 is conveyed to the downstream side by the first conveyor 64 in a state where its vertical movement is restricted. The first conveyor 64 is provided with a heating device 64a for heating the temperature between the first conveyors 64 to a predetermined temperature. Further, the transfer speed of the first conveyor 64 is set to be slower than the rotation speed of the transfer roll 63. As a result, when the sheet material 100 is conveyed between the first conveyors 64, the sheet material 100 is folded while being heated and compressed in the downstream direction to form the core layer 20.

Specifically, as shown in FIGS. 5A and 5B, the sheet material 100 is mountain-folded along the folding line P and valley-folded along the folding line Q. As shown in FIG. 5C, one first bulging portion 110 is valley-folded along a folding line Q provided in the central portion in the X direction, and the upper surface 110a on the right side in the X direction and the upper surface on the left side in the X direction are folded. 110a comes into contact with each other in an upright state. In the folded first bulging portion 110, the side wall portion 23 having a two-layer structure of the core layer 20 is formed by the upper surface 110a on the right side in the X direction and the upper surface 110a on the left side in the X direction that are in contact with each other in the upright state, and the side surface 110b. As a result, the side wall portion 23 of the one-layer structure of the core layer 20 is formed. At the upper end of the side wall portion 23, an upper wall portion 21 composed of end faces 110c of adjacent first bulging portions 110 is formed.

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

The first conveyor 64 is heated by the heating device 64a. Therefore, when the core layer 20 formed by folding passes through the first conveyor 64, the adhesive of the adhesive layer is in a melted state. Further, the core layer 20 heated by the heating device 64a of the first conveyor 64 is pressed by the first conveyor 64. Therefore, the upper end edge and the lower end edge of the side wall portion 23 of the two-layer structure are in a heat-sealed state.

As shown in FIG. 6, the folded core layer 20 moves toward the second conveyor 65. The transfer speed of the second conveyor 65 is set to be equal to the transfer speed of the first conveyor 64. Therefore, the folded core layer 20 passes through the second conveyor 65 while maintaining its shape. When passing through the second conveyor 65, the molten adhesive applied to the side wall portion 23 of the two-layer structure is cooled and solidified. As a result, the first side wall portion 23a and the second side wall portion 23b forming the two-layer structure are joined via the joint portion 23c formed by cooling and solidifying the adhesive. Through the above steps, the core layer 20 is obtained.

The core layer 20 that has passed through the second conveyor 65 moves toward the third conveyor 68. The transfer speed of the third conveyor 68 is set to be equal to the transfer speed of the second conveyor 65. Sheet rolls 66 and 67 around which a sheet made of a thermoplastic resin as a raw material of the skin layers 31 and 41 is wound are arranged in the vicinity of the carry-in port of the third conveyor 68, respectively. An adhesive (not shown) is applied to the sheets wound around the sheet rolls 66 and 67. The adhesive here is also preferably a hot melt adhesive composed of a resin compatible with the polypropylene resin, like the adhesive layer constituting the joint portion 23c.

By passing between the third conveyors 68, the sheets wound around the sheet rolls 66 and 67 are sequentially supplied to both sides of the core layer 20. In this state, the adhesive applied to the sheets from the sheet rolls 66 and 67 is in a molten state. On the other hand, since the third conveyor 68 is not provided with a heating device, the sheets supplied to both sides of the core layer 20 are joined by cooling and solidifying the applied adhesive. As a result, a hollow plate material 11 in which the skin layers 31 and 41 are bonded to both sides of the core layer 20 via an adhesive layer can be obtained.

Next, a heating step for heating the hollow plate material 11 and the decorative layers 32 and 42 will be described.
As shown in FIG. 7A, first, as the hollow plate material 11 used for the accommodating plate 7, the hollow plate material 11 obtained by the apparatus T is cut into a shape larger than that of the accommodating plate 7. For example, a rectangular piece cut into a rectangular shape that is about 50 mm larger in the longitudinal direction and the lateral direction than the size of the accommodating plate 7 is prepared. In FIG. 7, the hollow structure of the hollow plate member 11 is omitted. Further, in FIG. 7, a portion corresponding to the cross-sectional view taken along the line AA of FIG. 2A is shown as a schematic view.

As the decorative layers 32 and 42 used for the storage plate 7, adhesive layers (not shown) are laminated and integrated in advance. The adhesive layer laminated on the decorative layers 32 and 42 is preferably a resin compatible with polypropylene constituting the hollow plate material 11. The decorative layers 32 and 42 are prepared by being cut into a shape larger than the accommodating plate 7, specifically, the same size as the hollow plate material 11.

As shown in FIG. 7B, the hollow plate material 11 and the decorative layers 32 and 42 are heated, respectively. When heating the hollow plate material 11, the hollow plate material 11 is placed in a heating furnace 71 set to a predetermined temperature and held for a predetermined time. Similarly, the decorative layers 32 and 42 are also held for a predetermined time by placing the decorative layers 32 and 42 in the heating furnace 72 set to a predetermined temperature. The temperature inside the heating furnaces 71 and 72 is a thermoplastic resin constituting the hollow plate material 11 and the adhesive layer laminated and integrated with the decorative layers 32 and 42 (in this embodiment, polypropylene or a resin compatible with polypropylene). ) Is set to the extent that it melts.

In the present embodiment, in the heating step, the surface temperature of the hollow plate material 11 held in the heating furnace 71 is adjusted so as to differ depending on the portion. Further, the surface temperatures of the decorative layers 32 and 42 held in the heating furnace 72 are also adjusted so as to be different depending on the parts. This is done by partially installing a shielding material on the surfaces of the hollow plate material 11 and the decorative layers 32 and 42. A plurality of fine holes are formed in the shielding material, and by adjusting the size and number of holes, the surface temperature of the part where the shielding material is installed is adjusted to be lower than the temperature in the heating furnaces 71 and 72. can do. The surface temperature is not limited to the shielding material having holes formed, and may be adjusted by installing a shielding material having no holes formed.

In the subsequent pressing process, the shielding material is installed in a portion other than the portion where the hollow plate material 11 is thin and is press-molded. As shown in FIG. 7D, in the subsequent pressing step, the hollow plate material 11 is press-molded to form a recess 12 and a thin-walled portion 17 in the central portion and a compression portion 20c in the peripheral portion. The body 50 is obtained, but the shielding material is installed in a portion of the intermediate 50 other than the recess 12, the thin portion 17, and the portion corresponding to the compression portion 20c.

By installing the shielding material, the surface temperature of the portion of the hollow plate material 11 in which the crushing width of the core layer 20 is small or hardly crushed is adjusted to be relatively low with respect to the heating temperature in the heating furnace 71. The surface temperature of the portion of the core layer 20 having a large crushing width is adjusted to be relatively high. The surface temperature of the portion of the core layer 20 having the largest crushing width is about the same as the heating temperature in the heating furnace 71. In the accommodating plate 7 of the present embodiment, the recess 12 and the compression portion 20c have the largest crushing width, followed by the thin-walled portion 17 having the largest crushing width, and the other portions are hardly crushed. The method of adjusting the surface temperature of the decorative layers 32 and 42 is the same as that of the hollow plate material 11, and is therefore omitted here.

Next, in the second joining step of joining the decorative layers 32 and 42 to the hollow plate material 11 to form the hollow plate-like body 10, the hollow plate-like body 10 is pressed in the mold to bend the bent portion 16 and the thin-walled portion 17. The pressing process for obtaining the molded intermediate 50 will be described. In the present embodiment, the second joining step and the pressing step are simultaneously performed as one pressing step. Therefore, the intermediate body 50 is formed at the same time as the hollow plate-shaped body 10 is formed.

As shown in FIG. 7C, the dies used in the pressing step (second joining step and pressing step) include an upper die 81 and a lower die 82. The upper mold 81 and the lower mold 82 of the present embodiment are kept at room temperature without being heated as a whole.

The lower mold 82 is formed with recesses 82a and 82b and convex portions 82c. The recess 82a has a rectangular shape when viewed from above. The length in the longitudinal direction is substantially the same as the length in the longitudinal direction of the accommodating plate 7, and the length in the lateral direction thereof is substantially the same as the length in the lateral direction of the accommodating plate 7. The depth of the recess 82a is formed to be slightly shallower than the thickness of the accommodating plate 7.

The recess 82b is a portion for forming the recess 12 of the accommodating plate 7, and has an electric drill shape when viewed from above. The depth of the recess 82b is formed to be about 2 cm deeper than the bottom surface of the recess 82a.

The convex portion 82c is a portion for forming the thin portion 17 of the accommodating plate 7, and has an electric drill shape when viewed from above. The convex portion 82c is formed with a width of about 1 cm over the entire circumference thereof so as to surround the periphery of the concave portion 82b. Further, it is formed with a protruding length of about 1 cm with respect to the bottom surface of the recess 82a.

The size and depth of the recesses 82a and 82b and the size and height of the convex portion 82c are preferably set in consideration of the heat shrinkage of the hollow plate material 11 and the decorative layers 32 and 42. The same applies hereinafter.

The upper mold 81 is formed with recesses 81a and 81b and a convex portion 81c. The recesses 81a and 81b form a rectangular annular shape when viewed from above. The depths of the recesses 81a and 81b are substantially the same as the thickness of the compression portion 51 of the intermediate 50, which will be described later. The recess 81a is a portion for molding the upper surface 7a of the accommodating plate 7 when the upper mold 81 and the lower mold 82 are molded, and the recess 81b is a portion for molding the compression portion 51 of the intermediate body 50. be. That is, as shown by the dotted line in FIG. 7 (c), the recess 81a means a portion located inward from the outer edge of the recess 82a of the lower mold 82 when the mold is fastened, and the recess 81b is the lower mold 82. Refers to a portion located outside the outer edge of the concave portion 82a of the above. Further, the convex portion 81c is a portion projecting to form the concave portion 12 of the accommodating plate 7, and has a top view electric drill shape. The height of the convex portion 81c is formed so as to protrude by about 4 cm from the concave portion 81a.

As shown in FIG. 7C, first, the heated hollow plate material 11 and the decorative layers 32 and 42 are placed on the lower mold 82 in the order of the decorative layer 42, the hollow plate material 11, and the decorative layer 32 from the bottom. Place on. Since the hollow plate material 11 and the decorative layers 32 and 42 are cut into a rectangular shape larger than the accommodating plate 7, both ends in the longitudinal direction and both ends in the lateral direction are recessed when placed on the lower mold 82. It is in a state of protruding outward from 82a.

Further, in the previous heating step, since the surface temperatures of the hollow plate material 11 and the decorative layers 32 and 42 are made different depending on the parts by using the shielding material, the hollow plate material 11 and the decorative layer 32, When the 42 is placed, it is positioned with respect to the molds 81 and 82 according to the respective surface temperatures.

Specifically, the portions other than the concave portion 12, the thin-walled portion 17, and the compression portion 51 of the intermediate body 50 whose surface temperature is adjusted to be low are aligned with the positions of the concave portion 81a of the upper mold 81 and the concave portion 82a of the lower mold 82. .. Further, the portion whose surface temperature is adjusted to be the highest as the portion corresponding to the concave portion 12 of the intermediate body 50 is aligned with the positions of the convex portion 81c of the upper mold 81 and the concave portion 82b of the lower mold 82. Similarly, the portion of the intermediate 50 having the highest surface temperature as the portion corresponding to the compression portion 51 is aligned with the position of the recess 81b of the upper die 81. Further, the portion of the intermediate 50 whose surface temperature is adjusted to be the next highest as the portion corresponding to the thin portion 17 is aligned with the position of the convex portion 82c of the lower mold 82.

That is, the positioning of the hollow plate material 11 and the decorative layers 32 and 42 is performed based on their surface temperatures adjusted in the heating step. In the present embodiment, the height of the space when the mold is fastened is about 2 cm, which is the highest at the positions of the recess 82a of the lower mold 82 and the recess 81a of the upper mold 81. Further, the positions of the convex portion 82c of the lower mold 82 and the concave portion 81a of the upper mold 81 are the next highest, and are about 1 cm. On the other hand, the positions of the concave portion 82b of the lower mold 82 and the convex portion 81c of the upper mold 81 and the position of the concave portion 81b of the upper mold 81 are the lowest, about 3.5 mm. In the portions of the recesses 81a and 82a where the height of the space is the highest when the mold is molded, the portion where the covering material is placed in the previous heating step and adjusted to the lowest surface temperature is arranged, and the height of the space is increased. A shielding material is placed on the next highest concave portion 81a and the convex portion 82c, and a portion adjusted to the next lowest surface temperature is placed on the concave portion 81b, the convex portion 81c, and the concave portion having the lowest space height. In the portion 82b, a portion adjusted to a high surface temperature is arranged without placing a covering material in the previous heating step. On the flip side, in the heating step, the surface temperatures of the hollow plate material 11 and the decorative layers 32 and 42 are adjusted according to the height of the space between the upper mold 81 and the lower mold 82 at the time of mold clamping.

When the hollow plate material 11 and the decorative layers 32 and 42 were placed on the lower mold 82, a part of the thermoplastic resin of the adhesive layer coated on the heated decorative layers 32 and 42 was thermally melted. It is in a state. Therefore, the hollow plate material 11 and the decorative layers 32 and 42 are positioned in a temporarily joined state on the lower mold 82.

As shown in FIG. 7 (d), the upper die 81 is lowered toward the lower die 82 and molded, and the second joining step and the pressing step are performed at the same time. As a result, a hollow plate-like body 10 in which the decorative layers 32 and 42 are joined to the hollow plate material 11 is obtained, and an intermediate body in which the recess 12, the thin-walled portion 17, and the compression portion 51 are formed in the hollow plate-like body 10. 50 is obtained. A plurality of suction holes (not shown) are formed in the upper mold 81 and the lower mold 82, and by sucking the hollow plate material 11 and the decorative layers 32 and 42 at the time of mold clamping, they are brought into close contact with the inside of the molds 81 and 82 in a positioned state. Can be made to. The pressure at the time of pressing and the pressing time may be appropriately set. The hollow plate-like body 10 is formed into the inner surface shapes of the upper mold 81 and the lower mold 82, that is, the shapes of the concave portions 81a, 81b, 82a, 82b, and the convex portions 81c, 82c to form the intermediate body 50.

As shown in FIG. 7 (d), the surface temperature of the convex portion 81c of the upper mold 81 and the concave portion 82b of the lower mold 82 having a height of the space at the time of mold clamping of about 3.5 mm was raised in the heating step. The part adjusted to be the highest is arranged. At the time of mold clamping, when the hollow plate material 11 and the decorative layers 32 and 42 are pushed into the concave portion 82b of the lower mold 82 by receiving the pressing force from the convex portion 81c of the upper mold 81, the concave portion 12 of the intermediate body 50 is formed. Will be done. Since the surface temperature is the highest in the portion where the recess 12 is formed, the polypropylene resin constituting the hollow plate material 11 is thermally melted by molding, and the core layer 20 and the skin layers 31 and 41 are melted and integrated. Become. The hollow plate material 11 pressed downward by the convex portion 81c of the upper die 81 in the molten and integrated state is stretched downward. Similarly, the heated decorative layer 32 is also stretched downward. As a result, in the portion from the curved portion 15 to the region 13A of the side wall 13 shown in FIG. 3B, the decorative layer 32 has a portion corresponding to the recess 81a of the upper mold 81 and the recess 82a of the lower mold 82. The thickness becomes thinner. In this way, in the portion from the curved portion 15 to the region 13A of the side wall 13, the bent portion 16 having a thin decorative layer 32 is formed.

At the positions of the concave portion 81a of the upper mold 81 and the convex portion 82c of the lower mold 82 where the height of the space at the time of mold clamping is about 1 cm, the portion adjusted so that the surface temperature becomes the next highest in the heating step. Is placed. At the time of mold clamping, when the hollow plate material 11 and the decorative layers 32 and 42 are pressed upward by receiving the pressing force from the convex portion 82c of the lower mold 82, the thin portion 17 of the intermediate body 50 is formed. Since the surface temperature of the portion where the thin portion 17 is formed is the second highest after the portion where the recess 12 is formed, a part of the polypropylene resin constituting the hollow plate material 11 is thermally melted. On the other hand, although the hollow portion of the core layer 20 remains, the side wall portion 23 of the core layer 20 is buckled or bent due to the pressing force from the convex portion 82c. The buckled or bent side wall portion 23 abuts or joins the inner surface of the bent portion 16 via the upper wall portion 21 of the hollow plate material 11 and the skin layer 31. As a result, the number of places that support the upper wall portion 21 and the skin layer 31 of the hollow plate material 11 increases. Further, more parts of the lower wall portion 22 and the skin layer 41 of the hollow plate material 11 are also supported. Further, the side wall portion 23 is buckled or bent, so that the density of the thermoplastic resin in the hollow portion of the core layer 20 is increased in the thin-walled portion 17. Therefore, in the portion where the concave portion 12 is formed, the decorative layer 32 is stretched by the pressing by the convex portion 81c, and the bent portion 16 is pulled toward the hollow portion remaining in the thin-walled portion 17. However, the bent portion 16 is supported by the side wall portion 23 of the thin-walled portion 17, and the stretched bent portion 16 is suppressed from being pulled into the hollow portion of the core layer 20.

The surface temperature of the portion where the thin portion 17 is formed is adjusted to be lower than that of the portion where the recess 12 is formed. Therefore, when the decorative layer 32 is bent, the temperature difference between the concave portion 12 and the thin-walled portion 17 becomes large, and the molten state of the thermoplastic resin can be different. As a result, the curved portion 15 is bent with a small R shape.

In the portion where the concave portion 12 is formed, as described above, at the time of molding, the hollow plate material 11 and the decorative layers 32 and 42 receive the pressing force from the convex portion 81c of the upper mold 81 to enter the concave portion 82b of the lower mold 82. Pushed into. At this time, the decorative layer 32 is pulled so as to be pulled into the recess 82b of the lower mold 82. At the time of mold clamping, the suction hole formed in the upper mold 81 exerts a force that pulls the decorative layer 32 side upward, but if the force of pulling into the recess 82b is stronger than the suction force, the curved portion A force that creates a gap between the outer surface of 15 and the upper die 81 acts. As a result, it is conceivable that it is difficult to form the bent portion 16 that follows the shape of the mold. Then, the surface of the bent portion 16 is likely to be uneven. In this respect, the pressing force from the convex portion 82c when the thin-walled portion 17 is formed suppresses the generation of a gap between the outer surface of the curved portion 15 and the upper mold 81, and the appearance shape of the bent portion 16 is improved. Can be molded.

In the recess 81b of the upper mold 81 having a space height of about 3.5 mm at the time of mold clamping, a portion adjusted so that the surface temperature becomes the highest in the heating step is arranged. In this portion, the thermoplastic resin constituting the hollow plate material 11 is thermally melted by the mold clamping, and the core layer 20 and the skin layers 31 and 41 are melt-integrated and sandwiched between the decorative layers 32 and 42. The compressed portion 51 is formed.

The recess 81a of the upper mold 81 and the recess 82a of the lower mold 82, which have a space height of about 2 cm at the time of molding, are provided with portions adjusted so that the surface temperature is the lowest in the heating process. There is. This portion is pushed into the recess 82a of the lower mold 82 by mold clamping. In this portion, since the surface temperature is the lowest, the thermoplastic resin constituting the hollow plate material 11 is hardly melted, the core layer 20 is not deformed in the vertical direction, and the height dimension is maintained. Further, since heat is less likely to be transferred to the inner side wall portion 23 as compared with the upper wall portion 21 and the lower wall portion 22, the side wall portion 23 is not integrated with the upper wall portion 21 and the lower wall portion 22. It maintains its shape and does not deform.

Further, when the lower mold 82 is pushed into the recess 82a by the mold clamping, the decorative layer 42 located below is bent toward the upper decorative layer 32 at the end of the intermediate body 50 and is bent. An R-shaped curved portion 43 is formed on the portion. At this time, the hollow plate material 11 and the decorative layers 32 and 42 are adjusted to the lowest surface temperature, and the portion of the intermediate 50 corresponding to the compression portion 51 is adjusted to the highest surface temperature. Therefore, when the decorative layer 42 located below is bent, the temperature difference between the portion located in the recess 82a of the lower mold 82 and the portion located in the recess 81b of the upper mold becomes large, and the thermoplastic resin is melted. There is a difference in the state. As a result, the curved portion 43 formed on the decorative layer 42 is bent in a small R shape, and the end surface formed by bending the decorative layer 42 upward is formed as a steep slope at the end of the intermediate 50. .. The end face formed by bending the decorative layer 42 upward becomes the end face 7c of the accommodating plate 7. On the other hand, the decorative layer 32 located above is maintained in a state of extending in the horizontal direction without being bent.

As shown in FIG. 7E, the intermediate body 50 is cooled by separating the upper mold 81 from the lower mold 82, and then the intermediate body 50 is taken out from the lower mold 82. In the intermediate 50 obtained through the second joining step and the pressing step, the decorative layers 32 and 42 are joined to both sides of the hollow plate material 11, and the end portion of the portion having a size and shape corresponding to the accommodating plate 7 is formed. The compression portion 51 is formed over the entire circumference. Further, the concave portion 12 is formed in the central portion thereof, and the thin-walled portion 17 is formed so as to surround the concave portion 12. The thickness of the recess 12 and the compression portion 51 of the intermediate body 50 is about 3.5 mm, the thickness of the thin portion 17 is about 1 mc, and the thickness of the other portions is about 2 cm.

Next, a post-processing step of adjusting the shape of the end face of the intermediate body 50 to obtain the accommodating plate 7 will be described.
As shown in FIG. 7 (f), the compression portion 51 formed in the intermediate 50 is cut with a cutting jig (not shown). As shown in FIGS. 3A and 3B, in the cut portion, the hollow plate material 11 was compressed and fused and integrated between the edge of the decorative layer 32 and the edge of the decorative layer 42. A compression unit 20c is interposed. The end face 7c of the accommodating plate 7 is formed by the end edge of the decoration layer 32, the end face of the decoration layer 42, and the compression portion 20c. After that, the cut portion is polished, painted, or the like to adjust the shape of the end face 7c. It is not necessary to use a Thomson blade, a laser, or the like as a cutting jig for cutting the compression portion 51, without polishing, painting, or the like.

The accommodating plate 7 is obtained through each of the above steps.
According to the first embodiment, the following effects can be obtained.
(1) In the accommodating plate 7 of the above embodiment, a bent portion 16 is formed on the side surface of the hollow plate material 11 so that the decorative layer 32 is bent so as to be pulled to reduce the thickness thereof, and the bent portion 16 is formed. In the adjacent region, the hollow plate member 11 is compressed in the thickness direction to form a thin portion 17 having a shape recessed toward the decorative layer 32 side. In the thin-walled portion 17, the side wall portion 23 extending in the thickness direction of the core layer 20 is buckled or bent in the middle, and the density of the thermoplastic resin in the hollow portion is higher than that in the portion other than the thin-walled portion 17. ing.

Therefore, in the bent portion 16, the decorative layer 32 is supported by the side wall portion 23 and the shape of the portion where the side wall portion 23 remains is maintained, while the hollow portion is formed even in the portion where the side wall portion 23 does not exist. It is suppressed that the decorative layer 32 is dented toward. The formation of irregularities on the surface of the bent portion 16 is suppressed, and the accommodating plate 7 having a good appearance shape at the bent portion 16 of the decorative layer 32 can be obtained.

(2) On the inner surface of the bent portion 16, many side wall portions 23 that have buckled or bent in the thin-walled portion 17 abut or join with each other via the upper wall portion 21 of the hollow plate material 11 and the skin layer 31. ..

Therefore, even if a hollow portion remains in the core layer 20 in the region adjacent to the bent portion 16, the bent portion 16 is supported by the side wall portion 23 that has been buckled or bent. The formation of irregularities in the bent portion 16 is suppressed in a state of being supported by the thin portion 17.

(3) The bent portion 16 is supported by the side wall portion 23 that has buckled or bent in the thin-walled portion 17.
Therefore, even when the depth of the recess 12 is deep and the thickness of the bent portion 16 is thin, or when the radius of curvature at the curved portion 15 is small and the bent portion 16 is bent at a steep angle, the bent portion 16 is used. The formation of irregularities is suppressed.

(4) In the portion of the curved portion 15a, the first cell S1 and the second cell S2 are alternately arranged, so that the thickness of the upper surface of the hollow plate material 11 is different in the portion of the bent portion 16. In this respect, even in the curved portion 15a, since the bent portion 16 is supported by the side wall portion 23 that has been buckled or bent, the occurrence of unevenness due to the difference in the thickness of the upper surface is suppressed.

(5) In the recess 12, the core layer 20 is crushed and the shape of the cell S is deformed to the extent that the shape of the cell S cannot be identified. It is a solid state with no gaps.

Therefore, the recess 12 has high strength against impact.
(6) The thin-walled portion 17 is formed on the back side of the accommodating plate 7.
Therefore, the thin portion 17 is not visible from the front side of the accommodating plate 7. The appearance shape is good.

(7) The curved portion 43 formed in the lower part of the end surface 7c of the accommodating plate 7 has an R shape having a radius of curvature of about 5 to 10 mm, and the end surface 7c is formed as a steep slope.
Therefore, when the accommodating plate 7 is placed on the support portion protruding from the peripheral wall of the tool box 1, the accommodating plate 7 can be stably supported by the support portion. In addition, it is possible to prevent dust and dirt from accumulating between the support portion and the accommodating plate 7.

(8) The end surface 7c of the accommodating plate 7 covers the core layer 20 from the side.
Therefore, it is possible to prevent dust, dirt, and the like from entering the cells S arranged side by side in the core layer 20.

(9) The storage plate 7 is made of polypropylene. Since polypropylene has a smaller specific gravity and is excellent in strength as compared with other general-purpose thermoplastic resins, a hollow structure that is lightweight and has excellent impact strength can be obtained.

(10) The method for manufacturing the accommodating plate 7 of the above embodiment includes a joining step of joining the decorative layers 32 and 42 to the hollow plate material 11 to form the hollow plate-like body 10, and an upper mold 81 and a lower mold 82. In the mold, the hollow plate-shaped body 10 is pressed to form an intermediate body 50 having a bent portion 16 and a thin-walled portion 17. Then, in the pressing step, the bent portion 16 is formed by pressing the hollow plate-shaped body 10 with the convex portion 81c of the upper mold 81, and the hollow plate-shaped body 10 is pressed with the convex portion 82c of the lower mold 82 to form a thin wall. The part 17 is molded.

According to such a configuration, the hollow plate-like body 10 is in a state of being supported by the convex portion 82c at the time of press molding, and the decorative layer 32 pushed by the convex portion 81c of the upper mold 81 and stretched downward is the core. The denting toward the hollow portion of the layer 20 is suppressed. The accommodating plate 7 having a good appearance shape can be easily formed.

(11) In the heating step, the hollow plate material 11 and the decorative layers 32 and 42 are heated, and the hollow plate material 11 and the decorative layers 32 and 42 in the heated state are pressed in the mold, and the second joining step and the pressing step are performed. Are done at the same time.

Therefore, the manufacturing process is simplified, which is advantageous in terms of workability and cost.
(12) In the heating step, the parts other than the bent portion 16, the thin-walled portion 17, and the compressed portion 51 are covered with a shielding material and heated.

Therefore, the surface temperature of the bent portion 16, the thin-walled portion 17, and the compressed portion 51 can be relatively higher than that of the other portions. By coating with a shielding material, the surface temperature in the second joining step and the pressing step can be appropriately adjusted. Depending on the surface temperature of the hollow plate material 11 and the decorative layers 32 and 42, the decorative layers 32 and 42 can be easily bent or the hollow plate material 11 can be thinned.

(13) In the pressing step, press molding is performed in a heated state so that the surface temperature of the bent portion 16, the thin-walled portion 17, and the compressed portion 51 becomes higher than the surface temperature of the other portions.
Therefore, the thermoplastic resin constituting the hollow plate material 11 in the bent portion 16, the thin-walled portion 17, and the compression portion 51 melts more than the thermoplastic resin constituting the hollow plate material 11 in the other portions. Easy to be done. By adjusting the heating state so that it differs depending on the part, the function of each part can be exhibited.

(14) In the heating step, the surface temperature of the hollow plate material 11 and the decorative layers 32 and 42 is adjusted by installing a shielding material.
Therefore, in the subsequent second joining step and pressing step, the intermediate 50 can be molded by one press molding without heating the dies 81 and 82. The process is simplified, which is advantageous in terms of workability and cost.

(15) The hollow plate material 11 and the decorative layers 32 and 42 are placed on the lower mold 82 after being preheated in the heating step. At this time, the thermoplastic resin adhesive layer coated on the decorative layers 32 and 42 is in a heat-melted state.

Therefore, the hollow plate material 11 and the decorative layers 32 and 42 are temporarily joined to each other, and the decorative layers 32 and 42 can be accurately positioned with respect to the hollow plate material 11.
(16) In the heating step, the hollow plate material 11 and the decorative layers 32 and 42 are heated in separate heating furnaces 71 and 72, respectively.

Therefore, it is easy to adjust the temperature and control the temperature of each member. In addition, each member can be heated to a homogeneous temperature.
(17) A plurality of suction holes are formed in the molds 81 and 82.

Therefore, at the time of mold clamping, the hollow plate material 11 and the decorative layers 32 and 42 can be brought into close contact with the inside of the molds 81 and 82 in a positioned state. It is possible to suppress the misalignment of the hollow plate material 11 and the decorative layers 32 and 42, and it is possible to manufacture the accommodating plate 7 with high accuracy.

(Second Embodiment)
Next, the hollow structure of the second embodiment and the manufacturing method thereof will be described with reference to FIGS. 8 and 9.

The hollow structure of the second embodiment is used as a shelf board 8 provided inside a bookshelf, a storage shelf, or the like. In the following, with respect to the shelf board 8 and its manufacturing method, the matters common to the storage board 7 of the first embodiment will be omitted, and different matters will be mainly described.

As shown in FIG. 8, the shelf board 8 is formed in a rectangular plate shape by joining decorative layers 32 and 42 made of a non-woven fabric sheet to a hollow plate material 11.
An end face 8c is formed at the end of the shelf board 8 over the entire circumference, and the hollow portion of the hollow plate member 11, that is, the hollow portion of the core layer 20 is sealed by the end face 8c. The end surface 8c is formed as a steep slope that inclines inward toward the shelf plate 8 toward the upper side. The inclination angle θ3 of the end surface 8c with respect to the upper surface 8a of the shelf board 8 is preferably 70 ° or more, more preferably 80 ° or more, and further preferably 85 ° or more. As the inclination angle approaches 90 °, dust and the like are suppressed from accumulating on the end portion of the shelf board 8. An R-shaped curved portion 18 is formed at the boundary between the upper surface 8a and the end surface 8c of the shelf board 8. The radius of curvature of the curved portion 18 is about 1 to 5 mm.

The end face 8c is a portion formed by pressing the hollow plate-shaped body 10 toward the lower mold 92 in the pressing step described later. Therefore, in the end face 8c, the upper wall portion 21, the side wall portion 23, and the skin layer 31 of the core layer 20 are melt-integrated and are in a state of being bent and stretched toward the decorative layer 42 side. .. In the end face 8c, the upper wall portion 21, the side wall portion 23, and the skin layer 31 that are melt-integrated are in a solid state with almost no gap as a whole. At the lower end of the end face 8c, the lower wall portion 22 and the skin layer 41 of the core layer 20 are also melt-integrated together with the upper wall portion 21, the side wall portion 23, and the skin layer 31 to form the compression portion 20c.

On the other hand, the decorative layer 32 is in a state of being pulled and stretched by downward pressing in the pressing process. Therefore, as shown in FIG. 8, the decorative layer 32 of the end face 8c is thinner than the portion joined to the skin layer 31. In the shelf board 8 which is the hollow structure of the present embodiment, the portion of the decorative layer 32 as the surface layer from the curved portion 18 to the end surface 8c corresponds to the bent portion referred to in the claims. The bent portion 19 in the decorative layer 32 is bent from the decorative layer 32 joined to one main surface of the hollow plate material 11 toward the other main surface side, and is melt-integrated with respect to the side surface of the core layer 20. It is abutted or joined via the hollow plate material 11. The thickness of the decorative layer 32 joined to the skin layer 31 is about 0.5 mm, whereas the thickness of the bent portion 19 in the decorative layer 32 is about 0.2 mm.

Further, at the lower end portion of the end surface 8c, the decorative layer 42 is in a state of being pulled downward and stretched, and its thickness is about 0.2 mm or thinner than about 0.2 mm. At the lower end of the end surface 8c, the hollow plate material 11 that has been melt-integrated is integrated so that the stretched portions of the decorative layers 32 and 42 sandwich the hollow plate material 11.

As shown in FIG. 8, in the region adjacent to the end face 8c, a thin-walled portion 17b having a concave shape from below is formed. The thin portion 17b is formed along the end surface 8c over the entire circumference of the shelf board 8. The thickness of the thin portion 17b is about 1 cm, which is about half the thickness of the hollow plate-shaped body 10.

Next, the operation of the shelf board 8 of the present embodiment will be described.
In the end face 8c, the hollow plate material 11 seals the side surface of the core layer 20 in a state where the upper wall portion 21 of the core layer 20 and the skin layer 31 are melted and integrated and stretched. In the region adjacent to the curved portion 18, the hollow structure of the core layer 20 is still retained. Further, the decorative layer 32 is formed with a bent portion 19 that has been pulled and stretched. By stretching the decorative layer 32, a force that dents toward the hollow portion of the core layer 20 acts on the bent portion 19, but the thin portion 17 formed in the region adjacent to the bent portion 19 As a result, the bent portion 16 is supported underneath, and the occurrence of irregularities on the surface of the bent portion 19 is suppressed.

The method for manufacturing the shelf board 8 differs only in the structure of the mold of the first embodiment, and the other steps are common. Therefore, the second and subsequent joining steps will be described with reference to FIG.
As shown in FIG. 9A, the dies used in the pressing step (second joining step and pressing step) include an upper die 91 and a lower die 92. A convex portion 92a is formed on the lower mold 92. The convex portion 92a is a portion for forming the thin-walled portion 17b, and is formed as a ridge having a width of about 1 cm extending in a rectangular shape when viewed from above. Its protruding length is about 1 cm.

The upper mold 91 is formed with recesses 91a and 91b. The recesses 91a and 91b form a rectangular annular shape when viewed from above. The recess 91a is a portion for forming the entire shape of the shelf board 8, and the depth thereof is about 2 cm. The recess 91b is a portion for forming the compression portion 51a of the intermediate body 50a to be described later, and the depth thereof is substantially the same as the thickness of the compression portion 51a.

As shown in FIG. 9A, the heated hollow plate material 11 and the decorative layers 32, 42 are placed on the lower mold 92 in the order of the decorative layer 42, the hollow plate material 11, and the decorative layer 32 from the bottom. Place. In the previous heating step, the hollow plate material 11 and the decorative layers 32 and 42 have different surface temperatures of the hollow plate material 11 and the decorative layers 32 and 42 depending on the portion by using a shielding material. Therefore, it is positioned on the lower mold 92 according to its surface temperature.

As shown in FIG. 9B, the upper die 91 is lowered toward the lower die 92 and molded, and the second joining step and the pressing step are performed at the same time. As a result, a hollow plate-like body 10 in which the decorative layers 32 and 42 are joined to the hollow plate material 11 is obtained, and an intermediate body 50a in which the thin-walled portion 17b and the compression portion 51a are formed on the hollow plate-like body 10 is obtained. Be done.

As shown in FIG. 9B, the recess 91b of the upper mold 81 having a space height of about 3.5 mm at the time of mold clamping was adjusted so that the surface temperature became the highest in the heating step. The part is arranged. At the time of mold clamping, when the hollow plate material 11 and the decorative layers 32 and 42 are pushed into the recess 91a of the upper die 91, the compression portion 51a of the intermediate body 50a is formed in the recess 91b. Since the surface temperature is the highest in the portion where the compression portion 51a is formed, the polypropylene resin constituting the hollow plate material 11 is thermally melted by molding, and the core layer 20 and the skin layers 31 and 41 are melted and integrated. It becomes. The hollow plate material 11 pressed downward by the convex portion 81c of the upper die 81 in the molten and integrated state is stretched downward. Similarly, the heated decorative layer 32 is also stretched downward. As a result, in the portion from the curved portion 18 to the end face 8c shown in FIG. 8, the bent portion 19 having a thin decorative layer 32 is formed.

At the position of the convex portion 92a of the lower mold 92, a portion adjusted so that the surface temperature becomes the next highest in the heating step is arranged. At the time of mold clamping, when the hollow plate material 11 and the decorative layers 32 and 42 are pressed upward by receiving the pressing force from the convex portion 92a of the lower mold 92, the thin portion 17b of the intermediate body 50a is formed. Since the surface temperature of the portion where the thin portion 17b is formed is the second highest after the portion where the compression portion 51a is formed, a part of the polypropylene resin constituting the hollow plate material 11 is thermally melted. On the other hand, although the hollow portion of the core layer 20 remains, the side wall portion 23 of the core layer 20 is buckled or bent due to the pressing force from the convex portion 92a. The buckled or bent side wall portion 23 abuts or joins the inner surface of the bent portion 19 via the upper wall portion 21 of the hollow plate material 11 and the skin layer 31. As a result, the number of places that support the upper wall portion 21 and the skin layer 31 of the hollow plate material 11 increases. Further, more parts of the lower wall portion 22 and the skin layer 41 of the hollow plate material 11 are also supported. Further, the side wall portion 23 is buckled or bent, so that the density of the thermoplastic resin in the hollow portion of the core layer 20 is increased in the thin-walled portion 17b. Therefore, in the end face 8c, even if the bent portion 19 is pulled toward the hollow portion remaining in the thin-walled portion 17b, the bent portion 19 is supported by the side wall portion 23 of the thin-walled portion 17b and stretched. It is suppressed that the bent portion 19 is pulled into the hollow portion of the core layer 20.

As shown in FIG. 9C, the intermediate body 50a is cooled by separating the upper mold 81 from the lower mold 82, and then the intermediate body 50a is taken out from the lower mold 92. As a result, an intermediate 50a in which the compression portion 51a is formed is obtained.

As shown in FIG. 9D, the compression portion 51a formed in the intermediate body 50a is cut with a cutting jig, and if necessary, the cut portion is polished, painted, or the like to adjust the shape of the end face 8c.
According to the first embodiment, the following effects can be obtained in addition to the same effects as those of (1) to (4), (6), (8) to (17) according to the first embodiment.

(18) The end surface 8c of the shelf board 8 is formed as a steep slope that inclines inward toward the shelf board 8 toward the upper side.
Therefore, it is possible to prevent dust and dirt from accumulating on the end portion of the shelf board 8. In addition, the appearance shape can be improved without causing a feeling of unevenness when visually recognized.

The above embodiment can be modified as follows. The above embodiment and the following modified examples can be applied in combination with each other within a technically consistent range.
-The thickness of the thin portions 17 and 17b is not particularly limited. In the above embodiment, it is about 1 cm, but it may be thicker or thinner than this. For example, even in the thin-walled portions 17 and 17b, the hollow plate material 11 may be compressed in the thickness direction to be in a melt-integrated state. When the thickness is small, the density of the thermoplastic resin becomes higher, and the effect of supporting the bent portions 16 and 19 becomes larger. In order to facilitate such an effect, the thickness of the thin portions 17 and 17b is preferably 1/2 or less, more preferably 1/3 or less of the thickness of the hollow plate material 11.

-The width L1 of the thin portions 17 and 17b is not limited to about 1 cm. For example, it may be narrow or wide as shown in FIG. 11 (a).
-In the first embodiment, the lower surface 17a of the thin portion 17 is formed as a flat surface, but the shape is not limited to this. For example, as shown in FIG. 11B, it may be formed as a curved surface that is recessed upward. The same applies to the thin-walled portion 17b of the second embodiment.

Since the thin-walled portions 17 and 17b are formed, the thickness of the lower skin layer 41 and the decorative layer 42 in the thin-walled portion 17 is compared with the portion where the hollow plate material 11 is not compressed in the vertical direction. There may be a thinned part. In this regard, if the lower surface 17a is formed as a flat surface or a gently curved surface as in the housing plate 7 of the first embodiment and the thin-walled portions 17 and 17b of the modified example shown in FIG. 11B, the skin A sudden change in wall thickness in the layer 41 and the decorative layer 42 is suppressed, and extremely thinning is suppressed. As a result, the strength of the skin layer 41 and the decorative layer 42 can be maintained in the thin portions 17 and 17b.

The thin-walled portion 17 in the first embodiment is formed in a region directly in contact with the side wall 13, but is not limited to this. As shown in FIG. 11C, the hollow plate member 11 may be formed in a region adjacent to the bent portion 16 via a portion that is not compressed in the thickness direction. In this case, the side wall 17c in the thin portion 17 may have a steeper slope or a gentle slope than the side wall 13 of the recess 12, and may have the same inclination angle. The same applies to the thin-walled portion 17b of the second embodiment.

-As the hollow plate material 11, the core layer 20 to which the skin layers 31 and 41 are bonded is used, but the hollow plate material 11 is not limited to this. The skin layer 31 or the skin layer 41 may be bonded to only one main surface of the core layer 20, or the skin layers 31 and 41 may not be bonded to any of the main surfaces. good.

-The core layer 20 and the skin layers 31 and 41 may be made of different materials. Further, the skin layer 31 and the skin layer 41 may be made of different materials.
-At least one of the decorative layers 32 and 42 may not be joined. When the decorative layers 32 and 42 are not joined and the hollow plate material 11 is composed of only the core layer 20, the skin layers 31 and 41 are configured as the surface layer according to the claim. In this case, the skin layer 31 joined to one main surface of the core layer 20 is bent so as to be stretched toward the other main surface side, and a bent portion is formed in the skin layer 31.

-The decorative layers 32 and 42 do not have to be non-woven fabric sheets.
-At least one of the decorative layers 32 and 42 does not have to be made of a thermoplastic resin, and may be another conventionally known synthetic resin, synthetic leather, synthetic fiber, metal, natural leather, natural fiber, or the like. ..

-The decorative layers 32 and 42 may be made of different materials and forms.
-The decorative layers 32 and 42 may be made of the same material as the core layer 20.
-In order to increase the rigidity of the storage plate 7 and the shelf plate 8, a thin plate-shaped steel plate may be joined between the skin layer 31 and the core layer 20, between the skin layer 41 and the core layer 20, and the like. Examples of the material of the steel plate include thin metal plates such as aluminum alloys, iron alloys, and copper alloys. The thickness thereof is preferably about 0.05 mm to 0.5 mm. The position for joining the steel plates is preferably provided in a portion other than the recess 12, the thin portion 17, and 17b in consideration of the ease of the pressing process, but is not particularly limited.

-Even if a plurality of metal rods are press-fitted into the core layer 20 or a resin material such as urethane is injected into the cell S of the core layer 20 in order to increase the rigidity of the storage plate 7 and the shelf plate 8. good. When the metal bar is press-fitted, the cross-sectional shape is not particularly limited, and examples thereof include a bar having a circular cross section and a U-shaped cross section, H steel, and L steel. Further, after the metal bar is press-fitted, an adhesive can be injected around the metal bar for further reinforcement.

-In order to increase the rigidity of the accommodating plate 7 and the shelf plate 8, the thermoplastic resins constituting the core layer 20 and the skin layers 31 and 41 are made to contain a material having a high tensile elastic modulus such as carbon fiber and glass fiber. May be good. Further, a reinforcing material such as talc may be added to the thermoplastic resin constituting the core layer 20 and the skin layers 31 and 41.

-As the thermoplastic resin constituting the core layer 20 and the skin layers 31 and 41, those to which various functional resins are added may be used. For example, it is possible to enhance the flame retardancy by adding a flame retardant resin to the thermoplastic resin. In this case, it is also possible to use those in which various functional resins are added to all of the core layer 20 and the skin layers 31 and 41, and at least any of the core layer 20 and the skin layers 31 and 41. It can also be used for that configuration.

The thicknesses of the core layer 20, the skin layers 31, 41, and the decorative layers 32, 42 are not limited to those of the above embodiment, and can be changed as appropriate. Further, the thickness of the sheet material 100 for forming the core layer 20 can be appropriately changed.

-In the accommodation plate 7 of the first embodiment, the side wall 13 of the recess 12 is formed as a steep slope, but it may be formed as a gentle slope. Further, the end surface 7c may also be formed as a gentle slope. Further, the surface facing the side wall 13 of the recess 12 via the thin portion 17 may be a gentle slope as shown in FIG. 11D, or may be a steep slope.

-The shape of the storage plate 7 of the first embodiment is not particularly limited. The depth of the recess 12 may be shallower or deeper than that described above. Further, a concave-convex shape may be formed in addition to the concave portion 12.

-In the accommodating plate 7 of the first embodiment, the thin-walled portion 17 does not have to be formed over the entire circumference of the recess 12. It may be formed in a part thereof. In the portion of the core layer 20 in the vicinity of the recess 12 where the thin-walled portion 17 is not formed, the side wall portion 23 may or may not be buckled.

-In the shelf board 8 of the second embodiment, the thin-walled portion 17b does not have to be formed over the entire circumference of the end portion. For example, it may be formed only at the end on the short side. Also in this case, in the portion where the thin-walled portion 17 is not formed in the core layer 20 in the vicinity of the recess 12, the side wall portion 23 may or may not be buckled.

-In the shelf board 8 of the second embodiment, the end surface 8c is formed as a steep slope, but may be formed as a gentle slope.
-The shape of the shelf board 8 of the second embodiment is not particularly limited. An uneven shape may be formed.

The core layer 20 is not limited to the one formed by folding and molding one sheet material 100. For example, a plurality of strip-shaped sheets are bent at predetermined intervals to form a side wall of a cell, and sheet layers are arranged on both upper and lower sides of the strip-shaped sheets to form an upper wall and a lower wall of the cell. It may be.

In the above embodiment, as the core layer 20, one sheet material 100 is folded and formed to form a honeycomb structure in which hexagonal cells S are partitioned inside the core layer 20, but the core layer 20 is formed. Is not limited to this. For example, the core layer 24 may be formed from the sheet material 200 as shown in FIG. 10 (a).

As shown in FIG. 10A, in the sheet material 200, the flat surface regions 210 and the bulging regions 220 forming a strip shape are alternately arranged in the longitudinal direction (X direction) of the sheet material 200. In the bulging region 220, a first bulging portion 221 having a downward groove-like cross section composed of an upper surface and a pair of side surfaces is formed over the entire extending direction (Y direction) of the bulging region 220. The angle formed by the upper surface and the side surface of the first bulging portion 221 is preferably 90 °, and as a result, the cross-sectional shape of the first bulging portion 221 is downward U-shaped. Further, the width of the first bulging portion 221 (the length in the lateral direction of the upper surface) is equal to the width of the plane region 210, and the bulging height of the first bulging portion 221 (the length in the lateral direction of the side surface). ) Is set to be twice as long.

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

As shown in FIGS. 10A and 10B, the core layer 24 is formed by folding the sheet material 200 configured as described above along the folding lines P and Q. Specifically, the sheet material 200 is valley-folded along the folding line P between the flat surface region 210 and the bulging region 220, and mountain-folded along the folding line Q between the upper surface and the side surface of the first bulging portion 221. Shrinks in the X direction. Then, as shown in FIGS. 10 (b) and 10 (c), the upper surface and the side surface of the first bulging portion 221 are folded, and the end surface of the second bulging portion 222 and the plane region 210 are folded. A prismatic compartment 230 extending in one Y direction is formed for each bulging region 220. The hollow plate-shaped core layer 24 is formed by continuously forming the compartments 230 in the X direction.

When the sheet material 200 is folded and formed as described above, the upper wall portion 25 of the core layer 24 is formed by the upper surface and the side surface of the first bulging portion 221 and the end surface and the plane region of the second bulging portion 222. The lower wall portion 26 of the core layer 24 is formed by the 210.

Further, the hexagonal column-shaped region formed by folding the second bulging portion 222 into a section becomes the second cell S2'in the core layer 24, and the hexagonal column formed between the pair of adjacent compartments 230. The region of the shape becomes the first cell S1'in the core layer 24. In the present embodiment, the upper surface and the side surface of the second bulging portion 222 form the side wall portion 27 of the second cell S2', the side surface of the second bulging portion 222, and the second bulging portion in the bulging region 220. The flat surface portion located between 222 constitutes the side wall portion 27 of the first cell S1'. Then, the contact portion between the upper surfaces of the second bulge portion 222 and the contact portion between the plane portions in the bulge region 220 form a side wall portion 27 having a two-layer structure.

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

-In the present embodiment, the hexagonal columnar cell S is partitioned inside the core layer 20, but the shape of the cell S is not particularly limited. For example, it may have a polygonal shape such as a square columnar shape or an octagonal columnar shape, or a columnar shape. Further, the shape of the cell S may be a prefix cone shape. At that time, cells having different shapes may be mixed. Further, the cells do not have to be adjacent to each other, and a gap (space) may exist between the cells.

-The core layer 20 is not limited to the one in which the pillar-shaped cells S are partitioned. For example, a sheet layer may be joined to both upper and lower surfaces of a core layer having a predetermined uneven shape. Examples of the core layer having such a structure include those described in JP-A-2014-205341. Further, a plastic cardboard having a harmonica-shaped cross section or the like may be used, or plate materials having cylindrical or prefix cone-shaped cells may be integrally formed facing each other.

-In the above embodiment, the core layer forming step and the first joining step are performed in a series of flows by the device T to form the hollow plate material 11, but the hollow plate material 11 may be performed in a separate flow without using the device T. For example, after obtaining the core layer 20 in the core layer joining step, the core layer 20 and the skin layers 31 and 41 may be cut to a predetermined size, and each of them may be heated in a heating furnace to be joined.

-In the above embodiment, the second joining step and the pressing step are performed at the same time, but they may be performed as separate steps. For example, the hollow plate material 11 and the decorative layers 32 and 42 are heated and then joined to form a hollow plate-like body 10, the hollow plate-like body 10 is heated in a heating furnace, and the hollow plate-like body 10 in a heated state is formed. The intermediate bodies 50 and 50a may be formed by pressing in a mold. By doing so, since the decorative layers 32 and 42 are joined to the hollow plate material 11 prior to the pressing process, the positioning is improved and the joining accuracy between the hollow plate material 11 and the decorative layers 32 and 42 is improved.

-The heating temperature in the heating step can be set as appropriate. The material of the thermoplastic resin constituting the core layer 20, the skin layers 31, 41, and the decorative layers 32, 42, and the thermoplastic resin constituting the adhesive layer coated on the skin layers 31, 41 and the decorative layers 32, 42. It can be set as appropriate depending on the material of.

-In the heating step, the hollow plate material 11 and the decorative layers 32 and 42 are heated in separate heating furnaces 71 and 72, respectively, but the present invention is not limited to this. The hollow plate material 11 and the decorative layers 32 and 42 may be heated in the same heating furnace.

-The heating in the heating step may be heating in an open environment instead of heating in the heating furnaces 71 and 72. For example, it may be heated by an IH heater or an infrared heater.

-It is not necessary to use a shielding material when heating in the heating process. If the surface temperatures of the hollow plate material 11 and the decorative layers 32 and 42 can be adjusted so as to differ depending on the portion, the adjusting method is not limited to the method using the shielding material.

-The decorative layers 32 and 42 are pre-coated with an adhesive layer, but the present invention is not limited to this, and an adhesive may be applied at the time of joining.
The upper dies 81 and 91 and the lower dies 82 and 92 used in the second joining step and the pressing step are those having a plurality of suction holes, but the shape of the suction holes is not particularly limited. It may be a slit-shaped suction groove. Moreover, the suction hole can be omitted.

-The second joining step and the pressing step may be performed in a state where the upper dies 81 and 91 and the lower dies 82 and 92 are heated.
-As the die used in the second joining step and the pressing step, a die having a shape different from that of the upper die 81 and the lower die 82 of the above embodiment, or the upper die 91 and the lower die 92 may be used. For example, as shown by the alternate long and short dash line in the lower die 82 of FIG. 7 (d), a lower die provided with a movable die 83 so as to correspond to the position where the thin wall portion 17 is formed may be used. By inserting the movable mold 83 in a state of supporting the lower portion of the bent portion 16, it is possible to suppress the occurrence of unevenness in the bent portion 16.

-In the above embodiment, the storage plate 7 for accommodating the electric drill as the hollow structure and the shelf plate 8 provided inside the bookshelf, the storage shelf, etc. have been described as examples, but the hollow structure is not limited thereto. .. For example, it may be applied to interior members and building materials of automobiles. For example, it can be applied to a luggage board forming the bottom surface of a luggage room provided at the rear of an automobile.

1 ... Tool box, 7 ... Storage plate (hollow structure), 8 ... Shelf plate (hollow structure), 10 ... Hollow plate-like body, 11 ... Hollow plate material, 12 ... Recess, 13 ... Side wall, 14 ... Bottom wall, 16, 19 ... Bending part, 17, 17b ... Thin wall part, 20, 24 ... Core layer, 20c, 20c ... Compressed part, 23, 27 ... Side wall part, 31, 41 ... Skin layer, 32, 42 ... Decorative layer, 50 ... Intermediate, 81, 91 ... Upper mold (mold), 82, 92 ... Lower mold (mold), 100, 200 ... Sheet material, S ... Cell, S1, S1'... First cell, S2, S2 ´… Second cell.

Claims (5)

A hollow structure made of a thermoplastic resin including a hollow plate material having a plate-shaped core layer in which a plurality of cells are arranged side by side, and a surface layer joined to at least one main surface of the hollow plate material. ,
The cell is partitioned by a side wall extending in the thickness direction of the core layer.
A bent portion formed by bending the surface layer joined to one of the main surfaces toward the other main surface is provided on the side surface of the hollow plate material.
The thickness of the bent portion is thinner than that of the portion joined to the main surface.
In the region of the hollow plate material adjacent to the bent portion, the hollow plate material is compressed in the thickness direction, and the thickness of the hollow plate material is recessed from the other main surface side to the one main surface side. A hollow structure characterized in that a thin-walled portion is formed. The hollow structure according to claim 1, wherein the inner surface of the bent portion is supported by more side wall portions than the inner surface of the surface layer other than the bent portion. The method for manufacturing a hollow structure according to claim 1 or 2.
A joining step of joining the surface layer to the hollow plate material to form an intermediate,
A press step of pressing the intermediate to form the bent portion and the thin-walled portion in a mold having an upper mold and a lower mold is provided.
The upper mold is formed with a first convex portion having a protruding length equal to or greater than the thickness of the hollow plate material.
In the lower mold, a second convex portion having a protrusion length smaller than the thickness of the hollow plate material is formed at a position adjacent to the first convex portion when the mold is fastened.
The pressing step is characterized in that the bent portion is formed by pressing the intermediate body at the first convex portion, and the thin wall portion is formed by pressing the intermediate body at the second convex portion. A method for manufacturing a hollow structure. A heating step for heating the hollow plate material and the surface layer is provided.
The third aspect of the present invention is characterized in that the hollow plate material and the surface layer in a heated state are pressed in the mold to form the bent portion and the thin-walled portion at the same time as the joining step. How to make a hollow structure. A heating step for heating the hollow plate material and the surface layer is provided.
In the joining step, the heated surface layer is joined to the heated hollow plate material to form the intermediate.
The method for producing a hollow structure according to claim 3, wherein in the pressing step, the intermediate in a heated state is pressed in the mold to form the bent portion and the thin-walled portion.

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