JP7765072B2 - Manufacturing method of frame-shaped exterior body - Google Patents

Description

The present invention relates to a method for manufacturing a frame-shaped outer casing that surrounds a container body and has locking pieces on its outer periphery.

The present applicant has proposed the container and container manufacturing method disclosed in Patent Document 1 (hereinafter referred to as the "conventional example").

This conventional container consists of a frame-shaped exterior body with a circumferential groove on its inner surface, and a container body that is attached to this frame-shaped exterior body. The groove engagement pieces on the outer periphery of the container body are engaged within the grooves on the inner surface of the frame-shaped exterior body, so that the groove engagement pieces are supported by the supports provided in the grooves, allowing the frame-shaped exterior body and container body to be attached together without the use of adhesives or the like. Furthermore, this conventional container is configured so that the supports that support the container body protrude toward the inside of the exterior body and are deformable. Therefore, even if a load is applied to the groove engagement pieces due to weight on the container body, causing them to deform, the supports absorb the load on the groove engagement pieces, suppressing deformation of the groove engagement pieces and preventing the container body from falling out of the frame-shaped exterior body.

Japanese Patent Application Laid-Open No. 2020-7005

However, the conventional example also aims to beautify the unattractive, inexpensive container body to create a high-quality container, and to achieve this, a decorated frame-shaped exterior body is used, which achieves the aesthetic appeal of the container.

When adding aesthetic appeal to containers like this, it is preferable to use a frame-shaped exterior body that is decorated on the surface so that the base material is not exposed. However, when using such a frame-shaped exterior body with a decorated surface, the components that form the frame-shaped exterior body must be decorated on both the front and back sides. These components are more expensive than those decorated on one side, resulting in higher costs.

In addition, conventionally, when manufacturing frame-shaped exterior bodies, blank materials have often been used, which are formed by punching out a plate-shaped member into a predetermined shape.

However, when producing a frame-shaped exterior body decorated on both sides, a plate-shaped member decorated on both sides is punched into the desired shape to form a blank. However, the punching process results in the undecorated base material being exposed at the edges (cut surfaces) of such blanks. This means that the exposed edges must be decorated to conceal them, a process that further increases costs.

As such, conventional examples have the problem of high costs when manufacturing a frame-shaped exterior body with decorations on both the front and back sides.

The present invention was developed in consideration of the current state of the prior art, and aims to provide an innovative method for manufacturing frame-shaped exterior bodies that allows for easy and cost-effective manufacturing of frame-shaped exterior bodies.

The gist of the present invention will be explained with reference to the attached drawings.

The method for manufacturing a frame-shaped exterior body 30 surrounding a container body 20 provided with locking pieces 21 on its outer periphery includes a strip-shaped base material forming step of folding an upper part 2 and a lower part 3 of a rectangular plate-shaped base material 1 together onto the inner surface of the base material 1 to form a strip-shaped base material 1' having a groove 4 formed on the inner surface by the lower edge of the upper part 2 and the upper edge of the lower part 3; and a step of folding an upper edge of the lower part 3 disposed on the inner surface of the strip-shaped base material 1' inward to lock the locking pieces 21 of the container body 20. The method for manufacturing a frame-shaped outer casing includes a support part forming process for forming a support part 5 that supports the piece 21, and a frame forming process for folding the strip-shaped base material 1' and joining the longitudinal ends to form the strip-shaped base material 1' into a frame shape, wherein the strip-shaped base material forming process includes an upper part attaching process for attaching the upper part 2 to the inner surface of the base material 1, and a lower part attaching process for attaching the portion of the lower part 3 excluding the upper edge part 3a to the inner surface of the base material 1.

Furthermore, the method for manufacturing a frame-shaped exterior body described in claim 1 includes a groove forming step of forming an upper groove 6 on the inner surface of the base material 1 along the upper edge at a predetermined distance from the upper edge and a lower groove 7 along the lower edge at a predetermined distance from the lower edge of the base material 1, and the band-shaped base material forming step is characterized in that the upper portion 2 of the base material 1 above the upper groove 6 is folded and superimposed on the inner surface along the upper groove 6, and the lower portion 3 of the base material 1 below the lower groove 7 is folded and superimposed on the inner surface of the base material 1 along the lower groove 7.

Furthermore, in the method for manufacturing a frame-shaped exterior body described in claim 2, the upper groove 6 and the lower groove 7 are formed by cutting out a recessed portion of the inner surface of the base material 1.

The method for manufacturing a frame-shaped exterior body described in any one of claims 1 to 3 also includes a fold groove forming step of forming multiple fold grooves 8 perpendicular to the grooves 4 on the inner surface of the strip-shaped base material 1' on which the grooves 4 are provided, and the frame forming step involves folding the strip-shaped base material 1' along the fold grooves 8 and joining the longitudinal ends of the strip-shaped base material 1' to form the strip-shaped base material 1' into a frame shape.

Furthermore, in the method for manufacturing a frame-shaped outer casing described in claim 4, the folding groove 8 is formed by cutting out the inner surface of the belt-shaped base material 1' in a V-shaped or W-shaped cross section.

The method for manufacturing a frame-shaped exterior body described in any one of claims 1 to 5 also relates to a method for manufacturing a frame-shaped exterior body, characterized by including a lid engagement groove forming step of forming a lid engagement groove 9 on the outer surface of the base material 1, into which the outer peripheral edge 41 of the lid body 40 engages.

Furthermore, in the method for manufacturing a frame-shaped exterior body described in claim 6, the lid engagement groove 9 is formed by pressing the outer surface of the base material 1.

The method for manufacturing a frame-shaped exterior body described in any one of claims 1 to 7 also relates to a method for manufacturing a frame-shaped exterior body, characterized by including a base material forming step of punching out the base material 1 from a single thin plate-like member.

Furthermore, in the method for manufacturing a frame-shaped exterior body described in any one of claims 1 to 8, the base material 1 is formed into a rectangular shape in a plan view, and a first joining piece 10 is provided at one longitudinal end, and a second joining piece 11 and a third joining piece 12 that join to the first joining piece 10 are provided at the other longitudinal end.

Furthermore, the present invention relates to a method for manufacturing a frame-shaped outer casing, as described in any one of claims 1 to 9 , characterized in that the substrate 1 is decorated only on its outer surface.

As described above, the present invention provides a revolutionary method for manufacturing frame-shaped exterior bodies, allowing for easy and cost-effective production of frame-shaped exterior bodies.

FIG. 2 is an exploded perspective view showing the food container in the present embodiment. 1 is an explanatory cross-sectional view showing a main part of a food container in this embodiment. FIG. 1 is a process flow diagram of the present embodiment. 1A and 1B are front views showing the substrate after the substrate forming step of this embodiment, where FIG. 1A is a plan view of the inner surface side, and FIG. 1B is a plan view of the outer surface side. 10A and 10B are a front view and an enlarged cross-sectional view showing the base material after a groove forming step and a lid engaging groove forming step of this embodiment. 4 is an explanatory cross-sectional view showing a belt-shaped base material forming step of the present embodiment. FIG. 3A and 3B are a front view and an enlarged cross-sectional view showing a strip-shaped substrate after a strip-shaped substrate forming step of the present embodiment. 10 is an explanatory cross-sectional view showing a support portion forming step of the present embodiment. FIG. FIG. 10 is an explanatory front view showing the strip-shaped substrate after the folding groove forming step of the present embodiment. FIG. 2 is an explanatory plan view showing the state in which the frame-shaped exterior body of the present embodiment is folded. FIG. 2 is a perspective view showing a joint portion of a strip-shaped substrate of the present embodiment. FIG. 10 is a perspective view showing another example of the joint portion of the strip-shaped substrate of the present embodiment. FIG. 2 is an explanatory plan view showing a frame-shaped exterior body of the present embodiment. FIG. 10 is a cross-sectional view of a main part showing another example of a food container in the present embodiment. FIG. 10 is a cross-sectional view of a main part showing another example of the frame-shaped exterior body in the present embodiment.

The preferred embodiment of the present invention will be briefly explained below, illustrating its operation with reference to the drawings.

In the present invention, in the strip-shaped substrate formation process, the upper portion 2 of the substrate 1 is folded and superimposed on the inner surface of the substrate 1, and the lower portion 3 of the substrate 1 is folded and superimposed on the inner surface of the substrate 1, thereby forming the substrate 1 into a strip shape and obtaining a strip-shaped substrate 1'.

In this case, the present invention folds the upper portion 2 and the lower portion 3 toward the inner surface of the base material 1 so that the lower edge of the upper portion 2 and the upper edge of the lower portion 3, which are folded and overlapped on the inner surface of the base material 1, butt together at a predetermined distance. This results in a groove 4 formed on the inner surface of the strip-shaped base material 1' that is as deep as the thickness of the upper portion 2 (lower portion 3).

In this way, the present invention allows a strip-shaped substrate 1' having grooves 4 to be formed simply by bending the upper and lower portions 2 and 3 toward the inner surface of the substrate 1 and overlapping them with the inner surface of the substrate 1. This makes it easier to form the grooves 4 than in conventional cases where the substrate is cut out to form the grooves.

Furthermore, the inner surface of the strip-shaped substrate 1' formed in the manner described above is formed by the outer surfaces of the upper portion 2 and lower portion 3 folded and overlapped onto the inner surface of the substrate 1.

In other words, in the present invention, the inner surface of the substrate 1 before the upper and lower portions 2 and 3 are folded and overlapped is concealed by the folded and overlapped upper and lower portions 2 and 3, and in the strip-shaped substrate 1', the outer surfaces of the folded and overlapped upper and lower portions 2 and 3 become the inner surfaces.

Therefore, when manufacturing a frame-shaped exterior body with decorations on both the inside and outside surfaces, conventional methods require the use of a base material with decorations on both the inside and outside surfaces, and the edge (cut surface) where the base material is exposed through a punching process must also be decorated and concealed. However, with the present invention, if only the outside surface of the base material 1 is decorated, a strip-shaped base material 1' with decorations on the inside and outside surfaces and the edges (upper and lower edges) can be obtained.

Furthermore, in this invention, the upper and lower edges of the base material 1 become the opposing upper and lower surfaces of the groove 4 by folding the upper and lower portions 2 and 3 toward the inner surface of the base material 1 and overlapping them. Therefore, even if the base material is exposed at the edges, it does not detract from the appearance of the frame-shaped exterior body. Therefore, there is no need to decorate or conceal the exposed edges, which results in lower costs compared to conventional methods.

In this way, the present invention provides a revolutionary method for manufacturing frame-shaped exterior bodies that is easier and more cost-effective than conventional methods.

Specific examples of the present invention will be described below with reference to the drawings.

This example is a method for manufacturing a frame-shaped outer casing for a food packaging container, as shown in Figures 1 and 2, which is composed of a lid 40, a container body 20, and a frame-shaped outer casing 30.

Specifically, the process includes a base material forming process, a groove forming process, a lid engagement groove forming process, a strip-shaped base material forming process, a support portion forming process, a folding groove forming process, and a frame molding process, and is carried out according to the process flow shown in Figure 3.

The following describes each of the above steps involved in the manufacturing method of the frame-shaped exterior body 30 of this embodiment.

<Base material formation process>
The base material forming step is a step of punching out the base material 1 from a sheet of thin plate-like material.

Specifically, in this embodiment, a cardboard material approximately 1 to 2 mm thick, decorated on one side with decorative printing using antibacterial ink, is used, and this cardboard material is punched out using a punching device to form a base material 1 that is rectangular in plan view and decorated only on its outer surface (front surface), with a first joining piece 10 on one longitudinal side and a second joining piece 11 and a third joining piece 12 on the other, as shown in Figure 4.

In this embodiment, the thin plate-like member forming the base material 1 is made of paperboard, as described above, taking into consideration factors such as cost, durability, ease of decoration, and environmental impact. However, resin sheets, wooden sheets, etc. may also be used as long as they can form a frame-shaped exterior body 30 that can support the container body 20.

Furthermore, the above materials may be given additional functionality, such as allowing them to be frozen, microwaved, etc.

<Groove formation process>
The groove forming process is a process of forming upper grooves 6 and lower grooves 7 on the inner surface (non-decorative surface) of the base material 1, which has been formed into a predetermined shape in the base material forming process, as folding grooves when the upper portion 2 and lower portion 3 of the base material 1 are folded and overlapped onto the inner surface of the base material 1 in the band-shaped base material forming process described below.

Specifically, in this embodiment, as shown in Figure 5, an upper groove 6 is formed along the upper edge of the substrate 1 at a predetermined distance from the upper edge, and a lower groove 7 is formed along the lower edge of the substrate 1 at a predetermined distance from the lower edge.

In addition, in this embodiment, the upper groove 6 and the lower groove 7 are formed by cutting out a concave shape into the inner surface of the base material 1, as shown in Figure 5. This allows the upper portion 2 and the lower portion 3 to be folded smoothly in the belt-shaped base material forming process described below.

The positions of the upper groove 6 and lower groove 7 can be changed as appropriate depending on the configuration of the container body 20, etc.

The upper groove 6 and lower groove 7 may also be formed by pressing and recessing the outer surface of the substrate 1 using a pressing tool or pressing device such as a roller.

<Lid engagement groove formation process>
The lid engaging groove forming step is a step of forming a lid engaging groove 9 on the outer surface of the base material 1, with which the outer peripheral edge 41 of the lid 40 engages, as shown in FIG.

Specifically, in this embodiment, a pressing tool or pressing device such as a roller is used to press and concave the outer surface of the base material 1, thereby forming a concave lid engagement groove 9 as shown in Figure 5.

The lid engagement groove 9 may be formed by cutting out a notch, similar to the upper groove 6 and lower groove 7 formed in the groove forming process. This lid engagement groove forming process may also be performed before the groove forming process described above.

<Belt-shaped substrate forming step>
The strip-shaped substrate forming process is a process in which the upper portion 2 (the portion above the upper groove 6 of the substrate 1) and the lower portion 3 (the portion below the lower groove 7 of the substrate 1) of the substrate 1 are folded and laminated together onto the inner surface of the substrate 1 to form a strip-shaped substrate 1' having a groove 4 on the inner surface.

Specifically, in this embodiment, as shown in Figure 6, the upper portion 2 of the substrate 1 is folded inward along the upper groove 6 and overlapped with the inner surface, and the lower portion 3 of the substrate 1 is folded inward along the lower groove 7 and overlapped with the inner surface, thereby narrowing the width of the substrate 1 and forming it into a strip-like substrate 1'.

In addition, in this embodiment, the upper portion 2 and lower portion 3 of the substrate 1 are folded and superimposed on the inner surface of the substrate 1 to form the substrate 1' into a strip-shaped substrate. At the same time, as shown in Figure 7, the lower edge of the upper portion 2 (the upper edge of the substrate 1) and the upper edge of the lower portion 3 (the lower edge of the substrate 1) that are folded and superimposed on the inner surface of the substrate 1 form linear grooves 4 (recessed grooves) on the inner surface of the substrate 1'.

In other words, in this embodiment, the strip-shaped substrate 1' and grooves 4 are formed simultaneously in this strip-shaped substrate formation process.

In addition, in this embodiment, by folding and overlapping the upper and lower portions 2 and 3 toward the inner surface of the base material 1, joints 13 are simultaneously formed at both longitudinal ends of the strip-shaped base material 1' by the first joining piece 10, the second joining piece 11, and the third joining piece 12 when forming the strip-shaped base material 1' into a frame.

In this embodiment, the upper and lower portions 2 and 3 of the substrate 1 are folded and superimposed onto the inner surface of the substrate 1 during the strip-shaped substrate formation process, so that the outer surfaces of the upper and lower portions 2 and 3 of the substrate 1 become the inner surfaces of the strip-shaped substrate 1'. As a result, the inner surface of the substrate 1 that has not been decorated is covered by the outer surface of the decorated substrate 1, and both the inner and outer surfaces of the strip-shaped substrate 1' become decorated surfaces.

In addition, the strip-shaped substrate forming process in this embodiment includes an upper portion attachment process in which the upper portion 2, which has been superimposed on the inner surface of the substrate 1, is attached to the inner surface of the substrate 1, and a lower portion attachment process in which the lower portion 3, which has been superimposed on the inner surface of the substrate 1, is attached to the inner surface of the substrate 1.

Specifically, in the lower portion attachment process, the entire lower portion 3 is not attached, but only the portion of the lower portion 3 excluding the upper edge portion 3a is attached to the inner surface of the base material 1.

In the figure, the reference numeral 14 denotes an attachment means, which may be any suitable means such as adhesive, glue, double-sided tape, etc., as long as it can properly attach the upper portion 2 and lower portion 3 to the inner surface of the base material 1.

<Support forming process>
The support portion forming step is a step of forming a support portion 5 that supports the locking piece of the container body 20 by tilting the upper edge portion 3a of the lower piece 3 arranged on the inner surface of the strip-shaped base material 1' inward.

Specifically, in this embodiment, as shown in Figure 8, a jig 50 having a roller 51 and a hook-shaped inclined portion 52 at its tip is used to press the base end of the upper edge 3a of the lower portion 3 with the roller 51 to create a bent crease, while the hook-shaped inclined portion 52 tilts and inclines the upper edge 3a of the lower portion 3, which will become the support portion 5, to form the support portion 5.

<Groove formation process>
The folding groove forming step is a step of forming folding grooves 8 on the inner surface of the strip-shaped base material 1' on which the grooves 4 are formed, the folding grooves 8 being the folding lines when folding the strip-shaped base material 1' into a frame shape.

Specifically, in this embodiment, in order to form the strip-shaped substrate 1' into a rectangular frame shape, folding grooves 8 are formed at four predetermined locations on the strip-shaped substrate 1' so as to intersect perpendicularly with the grooves 4, as shown in Figure 9.

In addition, in this embodiment, as shown in Figure 9, the fold grooves 8 are formed in a V-shape or a W-shape in cross section. Specifically, when formed into a frame shape, the fold grooves 8 formed at the positions that will become one pair of corners arranged diagonally opposite each other are formed in a V-shape, and the fold grooves 8 formed at the positions that will become the other pair of corners are formed in a W-shape.

By forming folding grooves 8 of different shapes in this way, the frame-shaped exterior body 30 of this embodiment can be folded into a flat plate as shown in Figure 10, allowing it to be compact and not take up much space during transportation or storage.

When forming the folded groove 8 in a V-shape, a groove angle of 45° to 120° is preferable, and in this embodiment, a 120° V-groove is formed.

Furthermore, the shape of the fold grooves 8 is not limited to the above, and may, for example, all be W-shaped, or may all be at the same angle (90° or 120°).

Furthermore, the folding structure is not limited to that shown in Figure 10; for example, folding grooves may be added to allow for zigzag folding.

<Frame forming process>
The frame forming step is a step of bending the strip-shaped base material 1' into a frame shape.

Specifically, in this embodiment, the strip-shaped substrate 1' is folded along the fold grooves 8 formed in the fold groove forming process, and the joints 13 provided at the longitudinal ends of the strip-shaped substrate 1' shown in Figure 11 are joined together using an appropriate joining means to form a rectangular frame shape as shown in Figure 13.

Note that the joints 13 are not limited to the configuration shown in this embodiment, and may instead be configured as a dovetail joint as shown in Figure 12. By using such a dovetail joint, it is possible to join the joints 13 together without using any joining means.

In addition, while this example illustrates the formation of a rectangular frame-shaped exterior body, the manufacturing method for the frame-shaped exterior body of this example can also be used to manufacture frame-shaped exterior bodies in other shapes such as triangles, pentagons, or hexagons.

In addition, this example describes the case where a frame-shaped exterior body 30 decorated on both the inside and outside surfaces is manufactured using paperboard material decorated on one side. However, in the method of manufacturing a frame-shaped exterior body in this example, for example, a plain plate-shaped member is used, a strip-shaped base material 1 is formed from the plain base material 1, and decoration such as paint is applied only to the end grain surface of this plain strip-shaped base material 1' (the upper and lower edges of the strip-shaped base material 1'), resulting in a frame-shaped exterior body 30 decorated only on the end grain surface.

The effects of this embodiment, manufactured as described above, are described below.

When manufacturing a frame-shaped exterior body with decorations on both the inside and outside surfaces, the manufacturing method of this embodiment can produce a strip-shaped substrate 1' with decorations on both the inside and outside surfaces by simply decorating the outside surface of the substrate 1.

Furthermore, the upper and lower edges of the base material 1 become the opposing upper and lower surfaces of the groove 4 when the upper portion 2 and lower portion 3 are folded and overlapped onto the inner surface of the base material 1, and are not exposed to the inner surface of the strip-shaped base material 1'. Therefore, even if the base material is exposed at the upper and lower edges of the base material 1 due to punching, the appearance of the frame-shaped outer casing 30 is not marred. Therefore, there is no need to decorate or conceal the exposed upper and lower edges, which results in lower costs compared to conventional methods.

As such, the manufacturing method for a frame-shaped exterior body of this embodiment is a groundbreaking method for manufacturing a frame-shaped exterior body, which allows for easier and more cost-effective manufacturing of frame-shaped exterior bodies compared to conventional methods.

The frame-shaped exterior body 30 of this embodiment, manufactured as described above, is formed in a rectangular frame shape surrounding the periphery of the container body 20, as shown in Figures 1 and 2. The inner surface is provided with grooves 4 into which the locking pieces 21 provided on the outer periphery of the container body 20 can be inserted, and support portions 5 that support the locking pieces 21 inserted into these grooves 4. The upper outer surface is also provided with a lid engagement groove 9 into which the outer periphery 41 of the lid 40 engages. By inserting the locking pieces 21 of the container body 20 into the grooves 4, the locking pieces 21 are supported by the support portions 5, and adhesive or the like is used. The container body 20 can be integrally assembled to this frame-shaped exterior body 30 without the use of a screw. Furthermore, the frame-shaped exterior body 30 of this embodiment is configured so that the support portions 5 can freely protrude and deform inward. As a result, even if a load is applied to the locking pieces 21 due to weight on the container body 20, causing the locking pieces 21 to deform, the support portions 5 will absorb the load on the locking pieces 21 by deforming, suppressing deformation of the locking pieces 21 and preventing the container body 20 from falling out of the frame-shaped exterior body 30.

Regarding the container body 20, this embodiment has been described in the case of a box-shaped (deep dish) container body 20 as shown in Figure 1, but the shape of the container body 20 is not limited to this, and it may be formed, for example, in a flat plate shape as shown in Figure 14. In that case, as shown, the shape of the locking piece 21 may also be configured to be either horizontal (Figure 14(a)) or downwardly sloping (Figure 14(b)).

Furthermore, the frame-shaped exterior body 30 may be configured without the lid engagement groove 9, as shown in Figure 15.

Note that the present invention is not limited to this example, and the specific configuration of each component can be designed as appropriate.

REFERENCE SIGNS LIST 1 Base material 1' Strip-shaped base material 2 Upper portion 3 Lower portion 3a Upper edge portion 4 Groove 5 Support portion 6 Upper groove 7 Lower groove 8 Folding groove 9 Lid engagement groove
10 First joint piece
11 Second joint piece
12 Third joint piece
20 Container body
21 Locking piece
30 Frame-shaped exterior body
40 Lid
41 outer edge

Claims (10)

A method for manufacturing a frame-shaped outer casing that surrounds a container body having a locking piece on its outer peripheral edge, the method comprising: a strip-shaped substrate forming step in which the upper and lower portions of a square plate-shaped substrate are folded and overlapped onto the inner surface of the substrate to form a strip-shaped substrate having a groove on the inner surface formed by the lower edge of the upper portion and the upper edge of the lower portion; a support portion forming step in which the upper edge of the lower portion arranged on the inner surface of the strip-shaped substrate is tilted inward to form a support portion that supports the locking piece of the container body; and a frame-shaped forming step in which the strip-shaped substrate is folded and the longitudinal ends are joined to form the strip-shaped substrate into a frame shape, wherein the strip-shaped substrate forming step comprises an upper portion attaching step in which the upper portion is attached to the inner surface of the substrate, and a lower portion attaching step in which the portion of the lower portion excluding the upper edge portion is attached to the inner surface of the substrate . The method for manufacturing a frame-shaped exterior body according to claim 1 includes a groove forming step of forming an upper groove along the upper edge of the base material on the inner surface of the base material at a predetermined distance from the upper edge and a lower groove along the lower edge of the base material at a predetermined distance from the lower edge, and the band-shaped base material forming step of folding and superimposing the upper portion of the base material above the upper groove along the upper groove onto the inner surface of the base material, and folding and superimposing the lower portion of the base material below the lower groove along the lower groove onto the inner surface of the base material. The method for manufacturing a frame-shaped exterior body according to claim 2, wherein the upper groove and the lower groove are formed by cutting out a recessed portion of the inner surface of the base material. The method for manufacturing a frame-shaped exterior body described in any one of claims 1 to 3 includes a fold groove forming step of forming a plurality of fold grooves perpendicular to the groove on the inner surface of the strip-shaped base material, the fold grooves being perpendicular to the groove, and the frame forming step of folding the strip-shaped base material along the fold grooves and joining the longitudinal ends of the strip-shaped base material to form the strip-shaped base material into a frame shape. The method for manufacturing a frame-shaped exterior body according to claim 4, wherein the folding groove is formed by cutting the inner surface of the belt-shaped substrate in a V-shaped or W-shaped cross section. The method for manufacturing a frame-shaped exterior body according to any one of claims 1 to 5, further comprising a lid engagement groove forming step of forming a lid engagement groove on the outer surface of the base material, into which the outer peripheral edge of the lid engages. The method for manufacturing a frame-shaped exterior body according to claim 6, wherein the lid engagement groove is formed by pressing the outer surface of the base material. The method for manufacturing a frame-shaped exterior body according to any one of claims 1 to 7, further comprising a base material forming step of punching the base material out of a single thin plate-like member. The method for manufacturing a frame-shaped exterior body described in any one of claims 1 to 8, wherein the base material is formed into a rectangular shape in a plan view, has a first joining piece at one longitudinal end, and has a second joining piece and a third joining piece at the other longitudinal end that join to the first joining piece. 10. The method for manufacturing a frame-shaped exterior body according to claim 1, wherein the base material is decorated only on its outer surface.