Bending jig and bending method

Abstract

To provide a bending tool and a bending method that can reduce product costs and weight.SOLUTION: A bending tool 1 is characterized by comprising: a paper-made backing part 11; a paper-made formwork part 12 which is provided on the backing part 11, constitutes at least a part of a conical formwork shape, and folds and raises up four side walls along an inclined surface when the unfolded sheet of a paper box is placed on it and pressed toward the backing part 11; and four flap guiding projection parts 13 which are paper-made projections erected so as to protrude to a position higher than the inclined surface of the paper formwork part 12 at four corners of the conical formwork shape, and push up and fold four flap walls of the paper box and guide and fold them into the inside of a second side wall of the paper box.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a bending jig and a bending method for bending and forming a cardboard box from a developed sheet.

Background Art

[0002] Conventionally, a bending jig for bending and forming a cardboard box having a bottom wall, four side walls, and four flap walls from a developed sheet has been known (see, for example, Patent Document 1). The bending jig described in this Patent Document 1 has a plurality of guide members for guiding the bending of the side walls of the cardboard box erected on a substrate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, the bending jig as described in the above Patent Document 1 is often made of wood, synthetic resin, or metal. The bending jig composed of such materials tends to increase the product cost due to material costs and manufacturing costs, and also tends to be heavy in weight and inconvenient to handle.

[0005] The present invention aims to solve such problems. That is, the present invention aims to provide a bending jig and a bending method capable of suppressing the product cost and weight.

Means for Solving the Problems

[0006] To achieve the above objective, the present invention provides a folding jig for folding and forming a paper box from an unfolded sheet of the paper box, having at least a rectangular plate-shaped bottom wall, four side walls folded up at the four edges of the bottom wall, and a total of four flap walls, one pair for each of the four opposing first side walls, where a pair of side edges intersecting the edges of the first side walls are folded inward into the other opposing pair of second side walls, the folding jig comprising: a paper base portion formed in the shape of a plate larger than the bottom wall; and a mortar provided on the base portion, which has a rectangular frame shape for holding the paper box inside, and has an inclined surface on the upper surface opposite to the base portion that approaches the base portion as it moves toward the inner circumference. The invention is characterized by comprising: a paper formwork portion that constitutes at least a part of the shape of a pot frame, and when the unfolding sheet is placed on the upper surface and pushed toward the base portion such that the bottom wall is located inside the shape of the mortar frame, the formwork portion folds up the four side walls along the inclined surface; and four flap guide projections erected on the base portion or the formwork portion at the four corners of the shape of the mortar frame, projecting to a position higher than the inclined surface in the direction normal to the base portion, and when the unfolding sheet is placed on the formwork portion, the formwork portion pushes up and folds the four flap walls, and when the unfolding sheet is pushed toward, the formwork portion guides the four flap walls toward the inside of the opposing pair of second side walls and folds them toward the inside.

[0007] Furthermore, in order to achieve the above objective, the bending method of the present invention involves placing the unfolded sheet on the bending jig described above, with the four side walls positioned on the inclined surface of the formwork portion and the four flap walls positioned on the four flap guide protrusions Department The invention is characterized by comprising a placement step of placing the sheet in a position such that it is located in a certain position, and a pressing step of pressing the bottom wall of the unfolded sheet toward the base sheet to fold up the four side walls and fold in the four flap walls. [Effects of the Invention]

[0008] The bending jig and bending method described above can reduce product cost and weight. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view showing a bending jig according to the first embodiment. [Figure 2] Figure 1 is a perspective view showing how the distance between the C-shaped frame portions of the bending jig has been changed. [Figure 3] Figures 1 and 2 show the bending jig in an exploded perspective view, with the C-shaped frame portion detached from the base. [Figure 4] Figures 1 to 3 show the C-shaped frame portion as viewed from the backing board side. [Figure 5] This is a plan view showing two different sizes of the unfolded sheet for the paper box to be formed. [Figure 6] This figure shows steps S11 and S12 of the folding method for forming a paper box by folding the unfolded sheet shown in Figure 5. [Figure 7] This figure shows the deformation of the flap wall in step S12, as shown in Figure 6. [Figure 8] This figure shows steps S13 and S14 of the folding method for forming a paper box by folding the unfolded sheet shown in Figure 5. [Figure 9] Figures 1 to 3 are plan views showing the sheet material used to form the bending jig. [Figure 10] This diagram illustrates the process of folding a small-sized cardboard box, specifically the steps of placing the unfolding sheet and pressing it. [Figure 11] This is a perspective view showing a bending jig according to a second embodiment. [Figure 12] This is a plan view showing the sheet material used to form the bending jig shown in Figure 11. [Figure 13] This is a perspective view showing a bending jig used as a reference example. [Figure 14] Figure 13 is a three-view drawing showing the bending jig. [Modes for carrying out the invention]

[0010] Next, an embodiment of a bending jig and a bending method for bending and forming a cardboard box from a developed sheet will be described. First, the first embodiment will be described.

[0011] FIG. 1 is a perspective view showing a bending jig according to the first embodiment.

[0012] The bending jig 1 shown in FIG. 1 is a jig for forming a cardboard box in the shape of a flat rectangular box and made of cardboard. The cardboard box mentioned here is a packing box used for packing articles. The bending jig 1 is a jig made of cardboard as a whole, and includes a base paper part 11, a mold part 12 having a pair of opposing C-shaped frame parts 121, and four flap guide protrusions 13. The base paper part 11 is a rectangular plate-like part, and the mold part 12 is a part that constitutes a part of a mortar-shaped square frame shape with a pair of opposing C-shaped frame parts 121. Further, the four flap guide protrusions 13 are protruding parts erected so as to protrude at the four corners of the mortar frame shape in the mold part 12. In the present embodiment, the C-shaped frame part 121 is configured to be detachably attached to the base paper part 11, and by changing the attachment position, the distance between the C-shaped frame parts 121 can be changed according to the size of the cardboard box to be formed.

[0013] FIG. 2 is a perspective view showing a state in which the distance between the C-shaped frame parts in the bending jig shown in FIG. 1 is changed, and FIG. 3 is an exploded perspective view showing a state in which the C-shaped frame part is detached from the base paper part for the bending jig shown in FIGS. 1 and 2. Further, FIG. 4 is a perspective view of the C-shaped frame part shown in FIGS. 1 to 3 as viewed from the base paper part side. FIG. 5 is a plan view showing two types of large and small developed sheets of the cardboard box to be formed. FIG. 6 is a diagram showing steps S11 and S12 of a bending method for bending the developed sheet shown in FIG. 5 to form a cardboard box, and FIG. 7 is a diagram showing the deformation of the flap wall in step S12 shown in FIG. 6. And FIG. 8 is a diagram showing steps S13 and S14 of a bending method for bending the developed sheet shown in FIG. 5 to form a cardboard box.

[0014] First, prior to the bending jig 1 of the present embodiment, the two types of large and small cardboard boxes B11 and B12 formed by the bending jig 1 will be described while referring to FIGS. 5 to 8. In FIG. 5, the unfolded sheet B11a of the large-sized cardboard box B11 is shown in FIG. 5(A), and the unfolded sheet B12a of the small-sized cardboard box B12 is shown in FIG. 5(B). Further, FIGS. 6 to 8 show how the unfolded sheet B11a shown in FIG. 5(A) is formed into the cardboard box B11 by taking the unfolded sheet B11a of the large size as an example.

[0015] The cardboard boxes B11 and B12 of the present embodiment include rectangular plate-shaped bottom walls B111 and B121, four side walls B112 and B122, four flap walls B113 and B123, a pair of inner doors B114 and B124, and a pair of outer doors B115 and B125.

[0016] The four side walls B112 and B122 are wall portions that are folded up along four sides of the bottom walls B111 and B121, and include a pair of opposing first side walls B112a and B122a and a pair of opposing second side walls B112b and B122b. In the large-sized cardboard box B11, the first side wall B112a is folded up along the short side of the bottom wall B111, and the second side wall B112b is folded up along the long side. On the other hand, in the small-sized cardboard box B12, the first side wall B122a is folded up along the long side of the bottom wall B121, and the second side wall B122b is folded up along the short side.

[0017] The four flap walls B113 and B123 are tongue-shaped wall portions provided at a pair of side edges B112a-1 and B122a-1 that intersect the sides forming the boundaries of the bottom walls B111 and B121 at each of the pair of opposing first side walls B112a and B122a. Each flap wall B113 and B123 is folded inwardly of the pair of opposing second side walls B112b and B122b at these side edges B112a-1 and B122a-1 as shown in FIG. 7. The four flap walls B113 and B123 are thus provided in pairs for each of the first side walls B112a and B122a, for a total of four.

[0018] The pair of inner doors B114 and B124 are wall portions provided continuously with the opposing pair of first side walls B112a and B122a, and are folded after the side walls B112 and B122 are folded up so as to be parallel to the bottom walls B111 and B121. At the boundary between each inner door B114 and B124 and the side walls B112 and B122, there are slit portions B114a and B124a into which the insert tabs B115a and B125a of the outer doors B115 and B125 are inserted.

[0019] The pair of outer doors B115 and B125 are wall sections that are continuous with the opposing pair of second side walls B112b and B122b. After the side walls B112 and B122 are folded up, they are folded so that they overlap with the inner doors B114 and B124 and are parallel to the bottom walls B111 and B121. One of the outer doors B115 and B125 is provided with insertable tongues B115a and B125a, while the other outer door B115 and B125 is provided with recesses B115b and B125b that avoid the insertable tongues B115a and B125a.

[0020] In this embodiment, the paper boxes B11 and B12 are flat rectangular boxes. A flat rectangular box, as referred to here, is a thin box in which the four side walls B112 and B122 extend in a strip-like shape along the four sides of the bottom walls B111 and B121, with the width dimension LB11 being shorter than the length dimensions LB12 and LB13, as shown in Figure 5 for the large-sized paper box B11. The bending jig 1 in this embodiment is a jig for bending and forming such flat rectangular paper boxes B11 and B12 from unfolded sheets B11a and B12a.

[0021] The base portion 11 in this bending jig 1 is a paper part formed in the shape of a rectangular plate that is larger than the bottom wall B111 of the large-sized cardboard box B11. In this embodiment, this base portion 11 has a double wall made of two sheets of corrugated cardboard glued together.

[0022] The formwork section 12 is provided on the base section 11 and is a rectangular frame shape that houses the paper boxes B11 and B12 inside. It has a mortar-shaped upper surface opposite to the base section 11, with an inclined surface that approaches the base section 11 as it moves inward. When forming the paper boxes B11 and B12, as shown in Figure 6, the unfolded sheet B11a (B12b) is placed on the upper surface so that the bottom wall B111 (B121) is located inside the mortar-shaped frame. Furthermore, when the unfolded sheet B11a (B12b) is pressed towards the base section 11 in the pressing direction D11, the formwork section 12 folds its four side walls B112 (B122) in the upright direction D12 along the inclined surface.

[0023] In this embodiment, the formwork section 12 is provided such that the distance between opposing inclined surfaces along the shorter side of one of the two pairs of opposing inclined surfaces forming a mortar-shaped frame can be changed between a large-size opposing distance L11 and a small-size opposing distance L12. Specifically, the formwork section 12 is composed of a pair of opposing C-shaped formwork sections 121 that are detachably attached to the base paper section 11.

[0024] Each C-shaped frame portion 121 comprises a trapezoidal cylindrical portion 121a extending along the short side of the base portion 11, a pair of arm cylindrical portions 121b extending from both ends of the trapezoidal cylindrical portion 121a along the long side of the base portion 11, and an overlapping wall portion 121c that is superimposed on the base portion 11. The trapezoidal cylindrical portion 121a is a portion formed by bending corrugated cardboard into a cylindrical shape so that its cross-section is trapezoidal. The pair of arm cylindrical portions 121b are portions formed by bending corrugated cardboard into a cylindrical shape so that it forms a trapezoidal cylinder continuous with the trapezoidal cylindrical portion 121a at both ends of the trapezoidal cylindrical portion 121a. The overlapping wall portion 121c is a rectangular plate-shaped corrugated cardboard wall portion shown in Figure 4, where the portion folded up into a cylindrical shape with one long side as the boundary is the trapezoidal cylindrical portion 121a, and the portions folded up into a cylindrical shape with each of the pair of short sides as the boundary are the arm cylindrical portions 121b.

[0025] Furthermore, the trapezoidal cylindrical portion 121a of the C-shaped formwork portion 121 has one of the two opposing pairs of first inclined surface portions 121d that form the mortar-shaped inclined surface of the formwork portion 12 on the upper side opposite to the base portion 11. In addition, the pair of arm cylindrical portions 121b have a pair of arm-shaped inclined surface portions 121f that constitute a part of the pair of opposing second inclined surface portions 121e of the two opposing pairs of inclined surface portions.

[0026] Furthermore, each of the opposing pair of C-shaped frame portions 121 is provided with a mounting projection 121g for engaging each C-shaped frame portion 121 with the base portion 11. On the other hand, the base portion 11 is provided with a pair of mounting recesses 111 for large sizes and a pair of mounting recesses 112 for small sizes, so that the mounting position of the C-shaped frame portions 121 can be changed according to the size of the paper boxes B11, B12 to be formed. When the opposing pair of C-shaped frame portions 121 are mounted so that the mounting projection 121g is fitted into the mounting recess 111 for large sizes, the distance between the opposing pair of first inclined surface portions 121d is set to the distance L11 for large sizes (Figure 1). Also, when the opposing pair of C-shaped frame portions 121 are mounted so that the mounting projection 121g is fitted into the mounting recess 112 for small sizes, the distance between the opposing pair of first inclined surface portions 121d is set to the distance L12 for small sizes (Figure 2).

[0027] The formwork section 12, which is composed of such C-shaped formwork sections 121, has a part of the following flattened frame shape. The flattened frame shape referred to here is a thin frame shape in which the height dimension L13 from the base paper section 11 is shorter than the length dimension L14 of each of the four frame sections that make up the rectangular frame shape, i.e., the C-shaped formwork section 121, as shown in Figure 4 where one C-shaped formwork section 121 is extracted.

[0028] Furthermore, the four flap guide projections 13 in the folding jig 1 are paper projections erected on the formwork section 12 so as to protrude higher than the inclined surface of the mortar-shaped formwork section 12 in the normal direction D13 to the base paper section 11 at the four corners of the mortar-shaped formwork section 12. As shown in Figure 6, when the unfolded sheet B11a is placed on the formwork section 12, the four flap guide projections 13 push up and fold the four flap walls B113. Also, when the unfolded sheet B11a is pressed in, the four flap guide projections 13 guide the four flap walls B113 inward toward the opposing pair of second side walls B112b, as shown in Figure 7, and fold them inward.

[0029] Furthermore, the arrangement of the four flap guide protrusions 13 can be changed in accordance with the change in the opposing spacing L11, L12 in the formwork section 12. That is, one pair of the four flap guide protrusions 13 are provided on each C-shaped formwork section 121 so as to be integrated with each of the opposing pairs of C-shaped formwork sections 121.

[0030] Furthermore, each of the four flap guide projections 13 has a flap guide inclined surface 131 formed at its tip, which guides the four flap walls B113 towards the inside of the opposing pair of second side walls B112b. Each flap guide inclined surface 131 is inclined in the same direction as one of the two opposing pairs of inclined surfaces of the formwork section 12, specifically the arm-shaped inclined surface section 121f that abuts against the opposing pair of second side walls B112b and folds up. In addition, each flap guide inclined surface 131 is inclined with a gentler slope than the arm-shaped inclined surface section 121f.

[0031] Figure 9 is a plan view showing the sheet material for forming the bending jig shown in Figures 1 to 3. Figure 9(A) shows the base sheet 11a for forming the base portion 11. Figure 9(B) shows the formwork unfolding sheet 14 with protrusions for forming an integrated object consisting of one C-shaped formwork portion 121 and a pair of flap guide protrusions 13.

[0032] The backing sheet 11a is formed from two sheets of corrugated cardboard. These two backing sheets 11a are then glued together to form the backing section 11. The backing sheet 11a has a pair of backing through holes 111a, which become mounting recesses 111 for large sizes when it becomes the backing section 11, and a pair of backing through holes 112a, which become mounting recesses 112 for small sizes, formed by die-cutting. The die-cut corrugated cardboard pieces are then glued together in pairs and attached to the back surface of the overlapping wall section 121c of the C-shaped frame section 121 to form mounting protrusions 121g.

[0033] The protruding formwork unfolding sheet 14 is a sheet material made of corrugated cardboard and comprises a formwork sheet portion 141 that is folded to form a C-shaped formwork portion 121 and a pair of protruding sheet portions 142 that are folded to form a pair of flap guide protrusions 13. Furthermore, the formwork sheet portion 141 comprises a trapezoidal cylindrical sheet portion 141a that is folded to form a trapezoidal cylindrical portion 121a and a pair of arm cylindrical sheet portions 141b that are folded to form a pair of arm cylindrical portions 121b. In addition, the formwork sheet portion 141 comprises a rectangular plate-shaped overlapping wall sheet portion 141c that becomes an overlapping wall portion 121c.

[0034] The trapezoidal cylindrical sheet portion 141a extends from the long side of the overlapping wall sheet portion 141c and is folded into a cylindrical shape along multiple folds 141a-1 that are aligned with the long side direction of the overlapping wall sheet portion 141c in the in-plane direction D14 of the base paper portion 11 to form the trapezoidal cylindrical portion 121a. The arm cylindrical sheet portion 141b extends from the short side of the overlapping wall sheet portion 141c and is folded into a cylindrical shape along multiple folds 141b-1 that are aligned with the short side direction of the overlapping wall sheet portion 141c in the in-plane direction D14 to form the arm cylindrical sheet portion 141b.

[0035] The protruding sheet portion 142 extends from the base portion of the arm cylinder sheet portion 141b and is folded into a cylindrical shape along multiple folds 142-1 along the short side direction of the overlapping wall sheet portion 141c to form the flap guide projection portion 13. The flap guide projection portion 13 is the part formed when the protruding sheet portion 142 is folded into a cylindrical shape so that a part of its circumferential surface is higher than the second inclined surface portion 121e of the formwork portion 12 in the normal direction D13 of the base sheet portion 11, as shown in Figures 1 and 2.

[0036] Furthermore, the trapezoidal cylindrical portion 121a, the arm cylindrical portion 121b, and the flap guide projection portion 13 are all formed by rolling the leading edge of the corrugated cardboard inward, and then adhesively fixing this leading edge to the wall portion that overlaps with it. The outer walls of the trapezoidal cylindrical portion 121a and the arm cylindrical portion 121b have through holes 15 formed at positions that allow access to the adhesive point on the leading edge, enabling the adhesive work to be performed by inserting a finger into the adhesive point on the inside of the cylinder and pressing down on the adhesive point. These through holes 15 are formed in the projection-equipped formwork unfolding sheet 14 by punching.

[0037] Furthermore, in the formwork section 12, a removal recess 16 is provided on the inner circumference side of one of the two opposing pairs of frame sections in the mortar-shaped formwork section 121. The removal recess 16 is formed as a recess toward the outer circumference side of the mortar-shaped formwork section 12, and as shown in Figure 8, it is the part into which a hand is inserted when the completed paper box B11 is removed from the inside of the mortar-shaped formwork section. The formwork unfolding sheet 14 with protrusions has a recess-forming portion 16a that corresponds to this removal recess 16.

[0038] Next, a folding method for forming a paper box using the folding jig 1 of this embodiment will be described with reference to Figures 6 to 8. Figures 6 to 8 show how, in the folding jig 1, the distance between opposing pairs of C-shaped frame portions 121 is set to the large-size distance L11 (Figure 1), and a large-size paper box B11 is formed.

[0039] First, as shown in Figure 6, a placement step (S11) is performed in which the unfolded sheet B11a is placed on the bending jig 1. In this placement step (S11), the unfolded sheet B11a is placed such that the four side walls B112 are positioned on the mortar-shaped inclined surface of the formwork section 12, and the four flap walls B113 are positioned on the four flap guide protrusions 13. In this state, a pressing step (S12) is performed in which the bottom wall B111 of the unfolded sheet B11a is pressed toward the base paper section 11 in the pressing direction D11. This pressing step (S12) causes the four side walls B112 to be folded up in the upright direction D12 and the four flap walls B113 to be folded in.

[0040] The folding of the flap wall B113 is performed in two stages as the unfolded sheet B11a is pressed in the pressing direction D11, as shown in Figure 7. Specifically, in the first stage (S121), the flap wall B113, which rests on the flap guide projection 13 that protrudes to a position higher than the inclined surface of the formwork 12, is guided by the flap guide inclined surface 131 and folded up in the first folding direction D15 prior to the unfolding of the side wall B112. In the second stage (S122), as the unfolded sheet B11a is pressed further, the side wall B112 is folded up in the upright direction D12, and the flap wall B113 is guided by the flap guide inclined surface 131 in the second folding direction D16 and folded inward into the second side wall B112b.

[0041] Once the side wall B112 is folded up and the flap wall B113 is folded in this way, a rectangular space capable of accommodating articles is partitioned, as shown in Figure 6. Articles are then placed in this rectangular space. After the articles are placed inside, the closing process (S13) and the removal process (S14) shown in Figure 8 are performed. In the closing process (S13), a pair of inner doors B114 are folded inward, and then a pair of outer doors B115 are folded inward over them to close the article storage space. In the closing process (S13), the outer doors B115 are further secured by tape or by attaching a shipping label. This closing process (S13) completes the transformation from the unfolded sheet B11a to the paper box B11. Then, in the subsequent removal process (S14), the paper box B11 with articles inside is removed from the folding jig 1 in the removal direction D17. At this time, the worker places their hands on the exposed portion between the opposing pair of C-shaped frame portions 121 of the paper box B11, or on the exposed portion inside the removal recess 16 of each C-shaped frame portion 121, and pulls the paper box B11 upward in the removal direction D17. In this embodiment, the folding method for forming the paper box B11 by folding is completed with this removal step (S14).

[0042] Up to this point, the folding method has been explained using the large-sized paper box B11 as an example. However, the folding method for the small-sized paper box B12 is the same as that for the large-sized paper box B11, except that the position of the C-shaped frame portion 121 in the folding jig 1 and the way the unfolded sheet B12a is placed are different.

[0043] Figure 10 shows the steps of placing and pressing the unfolding sheet as part of the folding method for small-sized cardboard boxes.

[0044] In the folding method for the small-sized paper box B12, the distance between the opposing pair of C-shaped frame portions 121 in the folding jig 1 is set to the opposing distance L12 for small sizes (Figure 2). In this embodiment, the storage space of the paper box B12 partitioned between the opposing pair of C-shaped frame portions 121 is a rectangular space that is 90° different from that of the large size. That is, in the case of the large size, the storage space of the paper box B11 has the long side direction of the rectangular board-shaped base portion 11 as the longitudinal direction of the storage space and the short side direction as the short side. On the other hand, in the case of the small size, the storage space of the paper box B12 has the long side direction of the base portion 11 as the short side direction of the storage space and the short side direction as the longitudinal direction. In accordance with this storage space, in the placement process (S15) for the small size shown in Figure 10, the unfolded sheet B12a is placed on the folding jig 1 in an orientation that is 90° different from that of the large size. In the subsequent pressing step (S16), when the bottom wall B121 is pressed in the pressing direction D11, the four side walls B122 are folded up in the upright direction D12 and the four flap walls B123 are folded in. In the following closing step, the inner door B124 and outer door B125 are closed and fixed after the contents are placed inside, and in the removal step, the paper box B12 is removed from the folding jig 1, which is the same as in the case of the large size.

[0045] According to the bending jig 1 and bending method of the first embodiment described above, the base portion 11, the mold portion 12, and the flap guide projection portion 13 of the bending jig 1 used for bending and forming the paper boxes B11 and B12 are all made of paper. Therefore, compared to cases where these parts are made of wood, synthetic resin, or metal, material costs and manufacturing costs can be reduced, thereby lowering the product cost, and the weight can also be reduced.

[0046] In this embodiment, the formwork portion 12 is provided with a changeable distance L11, L12 between at least one pair of opposing inclined surfaces (in this embodiment, the first inclined surface portion 121d) of the two pairs of opposing inclined surfaces forming the rectangular mortar frame shape. The arrangement of the four flap guide protrusions 13 can be changed in accordance with the change in the distance L11, L12 between the opposing surfaces in the formwork portion 12. With this configuration, it is possible to form paper boxes B11, B12 of various sizes (in this embodiment, two sizes, large and small) by changing the distance L11, L12 between the opposing surfaces, and costs can be reduced compared to preparing different bending jigs for each size.

[0047] Furthermore, in this embodiment, the formwork portion 12 includes a pair of opposing C-shaped formwork portions 121 that are detachably attached to the base portion 11, each having one first inclined surface portion 121d and a pair of arm-shaped inclined surface portions 121f. The one first inclined surface portion 121d is one of the two opposing pairs of first inclined surface portions 121d. The arm-shaped inclined surface portions 121f are a pair of inclined surface portions that extend from both ends of the one first inclined surface portion 121d and constitute a part of the opposing pair of second inclined surface portions 121e. The four flap guide protrusions 13 are integrally formed two at a time on each of the opposing pair of C-shaped formwork portions 121. With this configuration, the opposing spacing L11, L12 of the first inclined surface portions 121d can be easily changed by changing the spacing between the opposing pair of C-shaped formwork portions 121.

[0048] Furthermore, in this embodiment, the base portion 11 is provided with mounting recesses 111 and 112 at multiple positions corresponding to each interval, for attaching each of the opposing pair of C-shaped frame portions 121 to positions where they face each other at predetermined intervals (in this embodiment, two intervals of different lengths). Each of the opposing pair of C-shaped frame portions 121 is provided with a mounting projection 121g that fits into and locks into the mounting recesses 111 and 112. With this configuration, the opposing intervals L11 and L12 of the first inclined surface portions 121d can be changed even more easily by changing the mounting recesses 111 and 112 into which the mounting projections 121g of the C-shaped frame portions 121 are fitted.

[0049] Furthermore, in this embodiment, each of the four flap guide projections 13 has a flap guide inclined surface 131 formed at its tip, which guides the four flap walls B113, B123 to the inside of the opposing pair of second side walls B112b, B122b. Each flap guide inclined surface 131 is inclined in the same direction as one of the two opposing pairs of inclined surface portions (in this embodiment, the second inclined surface portion 121e). With this configuration, by inclining the flap guide inclined surface 131 in the same direction as the second inclined surface portion 121e, the flap walls B113, B123 can be effectively guided to the inside of the second side walls B112b, B122b that are folded up by the second inclined surface portion 121e.

[0050] Furthermore, in this embodiment, each flap guide inclined surface 131 has a gentler slope than one of the pair of inclined surface portions (in this embodiment, the second inclined surface portion 121e). With this configuration, by making the flap guide inclined surface 131 gentler than the second inclined surface portion 121e in the formwork portion 12, the strength of the tip of the flap guide projection 13, which tends to be protruding and weak, can be improved. In addition, the unfolded sheets B11a and B12a can be stably placed during the placement process (S11).

[0051] Furthermore, in this embodiment, each flap guide inclined surface 131 is inclined in the same direction as the inclined surface portion that contacts and folds up the opposing pair of second side walls B112b and B122b in the paper boxes B11 and B12, among the two opposing pairs of inclined surface portions. With this configuration, prior to folding up the second side walls B112b and B122b, the flap guide inclined surface 131 can effectively guide the flap walls B113 and B123 and fold them inward towards the second side walls B112b and B122b.

[0052] Furthermore, in this embodiment, the base portion 11 is formed by stacking two or more sheets (two in this embodiment) of corrugated cardboard that are larger than the bottom walls B111 and B121 of the paper boxes B11 and B12. With this configuration, deformation of the formwork portion 12 is well suppressed by the base portion 11, thereby improving the strength of the bending jig 1.

[0053] Furthermore, in this embodiment, the formwork portion 12 has a shape in which cylindrical portions formed by folding corrugated cardboard into a cylindrical shape along multiple folds along the in-plane direction D14 of the base paper portion 11 are combined. With this configuration, by constructing the formwork portion 12 from cylindrical portions of corrugated cardboard, the weight of the bending jig 1 can be reduced while improving its strength.

[0054] Furthermore, in this embodiment, the cylindrical portion of the formwork section 12 is formed by rolling the leading end of the corrugated cardboard inward and adhesively fixing the leading end to the wall portion that overlaps with it. The outer wall of the cylindrical portion has a through hole 15 at a position that allows access to the adhesive point on the leading end, which is used to insert a finger into the adhesive point and press down on it to perform the bonding work. With this configuration, the bonding work on the adhesive point of the cylindrical portion of the formwork section 12 can be performed with good workability by inserting a finger into the through hole 15 and pressing down on the adhesive point.

[0055] Furthermore, in this embodiment, each of the four flap guide projections 13 is a portion formed by folding corrugated cardboard into a cylindrical shape along multiple folds in the in-plane direction D14 of the base portion 11. The cylindrical shape of the flap guide projection 13 is defined as a shape in which a part of the circumferential surface is higher than the inclined surface of the formwork portion 12 in the direction D13 normal to the base portion 11. With this configuration, by forming the flap guide projections 13 into a cylindrical shape from corrugated cardboard, the weight of the bending jig 1 can be reduced while improving its strength.

[0056] Furthermore, in this embodiment, the formwork portion 12 is a part in which an extraction recess 16 is provided in at least one pair of frame portions (in this embodiment, the trapezoidal cylindrical portion 121a of the C-shaped formwork portion 121) of the two opposing pairs of frame portions in the mortar-shaped formwork. The extraction recess 16 is formed in the inner circumference portion of the mortar-shaped formwork, recessed toward the outer circumference portion of the mortar-shaped formwork, and is a part into which a hand can be inserted when the completed paper boxes B11 and B12 are removed from the inside of the mortar-shaped formwork. With this configuration, since the formwork portion 12 is a part in which an extraction recess 16 is provided, the completed paper boxes B11 and B12 can be removed from the inside of the formwork portion 12 with good workability.

[0057] Furthermore, in this embodiment, the paper boxes B11 and B12 are flat rectangular boxes in which the four side walls B112 and B122 extend in a strip-like shape along the four sides of the bottom walls B111 and B121, with a width dimension LB11 shorter than the length dimensions LB12 and LB13. The formwork portion 12 has at least a portion of a flat frame shape in which the height dimension L13 from the base portion 11 of each of the four frame portions forming a square frame shape is shorter than the length dimension L14. Generally, flat rectangular boxes like the one described above are often used as paper boxes having a square plate-shaped bottom wall, four side walls, and four flap walls. With the above configuration, such flat rectangular paper boxes B11 and B12 can be formed with good workability using a bending jig 1 equipped with a formwork portion 12 in the shape of a flat frame.

[0058] This concludes the description of the first embodiment. Next, the second embodiment will be described.

[0059] Figure 11 is a perspective view showing a bending jig according to a second embodiment, and Figure 12 is a plan view showing the sheet material for forming the bending jig shown in Figure 11.

[0060] The bending jig 2 of the second embodiment shown in Figure 11 is, like the first embodiment described above, a corrugated cardboard jig for forming a flat rectangular cardboard box. However, unlike the bending jig 1 of the first embodiment, which can accommodate two sizes of cardboard boxes B11 and B12, the bending jig 2 of the second embodiment is specialized for one size. Here, the bending jig 2 of the second embodiment will be described as being used to form the large-sized cardboard box B11 shown in Figure 5(A).

[0061] The bending jig 2 of this embodiment includes a base section 21 with a two-piece structure in which a reinforcing base section 212 of the same shape is superimposed on the back side of a rectangular plate-shaped main base section 211. The bending jig 2 also includes a mold section 22 which is formed integrally with the main base section 211 and constitutes the entire rectangular mortar frame shape, and four flap guide protrusions 23 which are formed integrally with the main base section 211 and the mold section 22 and are positioned at the four corners of the mortar frame shape.

[0062] The formwork section 22 comprises a pair of opposing first frame sections 221 along the short sides of a rectangular plate-shaped base section 21 having a pair of opposing long sides and a pair of opposing short sides, and a pair of opposing second frame sections 222 along the long sides. In both the first frame sections 221 and the second frame sections 222 of this formwork section 22, the height dimension L21 is shorter than the length dimensions L22 and L23, forming a flattened frame shape.

[0063] The first frame portion 221 has a first inclined surface portion 221a that abuts against and folds up against the first side wall B112a of the paper box B11, where the flap wall B113 is provided, and is a cylindrical portion formed by bending corrugated cardboard into a cylindrical shape with a trapezoidal cross-section. The second frame portion 222 has a second inclined surface portion 222a that abuts against and folds up against the second side wall B112b of the paper box B11, and is a cylindrical portion formed by bending corrugated cardboard into a cylindrical shape with a trapezoidal cross-section. The outer walls of both the first frame portion 221 and the second frame portion 222 have through holes 25 formed therein to allow for bonding work to be performed by inserting a finger into the bonding area inside the cylinder and pressing down on the bonding area during the bending process. Furthermore, the first frame portion 221 is provided with a removal recess 26 into which a hand can be inserted when the completed paper box B11 is removed from the inside of the mortar-shaped frame.

[0064] The four flap guide projections 23 are projections erected on the formwork section 22 at the four corners of the mortar-shaped formwork section 22, projecting to a position higher than the first inclined surface section 221a and the second inclined surface section 222a in the normal direction D23 to the base paper section 21. Each flap guide projection 23 has a flap guide inclined surface 231 formed at its tip, and each flap guide inclined surface 231 is inclined in the same direction as the second inclined surface section 222a, but with a gentler slope than the second inclined surface section 222a.

[0065] The bending jig 2 described above is formed from a single reinforcing sheet 212a that forms the reinforcing base 212, and a single main unfolding sheet 24 that forms the main base 211, the formwork section 22, and the four flap guide projections 23. Figure 12(A) shows the reinforcing sheet 212a, and Figure 12(B) shows the main unfolding sheet 24.

[0066] The reinforcing backing sheet 212a is a sheet material made of corrugated cardboard and formed into a rectangular plate shape similar to that of the main backing sheet 211.

[0067] The main unfolding sheet 24 is a sheet material made of corrugated cardboard and includes a base sheet portion 241 that constitutes the main base 211. This base sheet portion 241 is a rectangular plate-shaped part, and the following sheet portions extend from each of the opposing pair of long sides and opposing pair of short sides to be folded and formed into two opposing pairs of frame portions in the formwork portion 22.

[0068] First, a pair of first formwork sheet portions 242, which are folded and formed into a pair of opposing first frame portions 221 in the formwork portion 22, extend from the short side of the base sheet portion 241. Each first formwork sheet portion 242 is folded into a cylindrical shape along multiple folds 242a along the short side of the base sheet portion 241 in the in-plane direction D24 of the base sheet portion 21 to form the first frame portion 221. In addition, the first formwork sheet portion 242 has a recess-forming portion 26a corresponding to the removal recess 26 shown in Figure 11, and through holes 25 for adhesive work are formed by punching.

[0069] Next, a pair of second formwork sheet portions 243, which are folded and formed into a pair of opposing second frame portions 222 in the formwork portion 22, extend from the long side of the base sheet portion 241 in the in-plane direction D24. Each second formwork sheet portion 243 is folded into a cylindrical shape along multiple folds 243a along the long side of the base sheet portion 241 to form the second frame portion 222. Through holes 25 for adhesive work are also formed in the second formwork sheet portions 243 by punching.

[0070] Furthermore, the main unfolding sheet 24 is equipped with four protruding sheet portions 244 that are folded and formed into four flap guide protrusions 23. Extending from the base portion of the second formwork sheet portion 243, these protruding sheet portions 244a are folded into a cylindrical shape along multiple folds 244a that run along the long side of the base sheet portion 241 to form the flap guide protrusions 23. The flap guide protrusions 23 are formed when these protruding sheet portions 244 are folded into a cylindrical shape such that a portion of their circumferential surface is higher than the second inclined surface portion 222a of the formwork portion 22 in the normal direction D23 of the base portion 21, as shown in Figure 11.

[0071] In this embodiment, the above-described bending jig 1 is prepared for each size of the paper box to be formed, and the paper box is formed by bending using a method equivalent to the bending method in the first embodiment described with reference to Figures 6 and 7.

[0072] It goes without saying that, as with the first embodiment described above, the bending jig 2 and bending method of the second embodiment also reduce material costs and manufacturing costs, thereby lowering the product cost, as well as reducing weight.

[0073] This concludes the description of the second embodiment. Next, we will describe some reference examples.

[0074] Figure 13 is a perspective view showing a bending jig for reference, and Figure 14 is a three-view drawing showing the bending jig shown in Figure 13.

[0075] The folding jig 3 of the reference example shown in Figures 13 and 14 is a jig for forming a flat rectangular cardboard box, similar to the first and second embodiments described above. However, unlike the first and second embodiments, the folding jig 3 of this reference example is made of expanded polystyrene. A polystyrene foam with a magnification of 30 times is preferred, such as Eperan PP (a registered trademark of Kaneka Corporation). This folding jig 3, like the folding jig 2 of the second embodiment described above, is a jig specialized for one size. Below, the folding jig 3 of the reference example will be described as being used to fold and form the large-sized cardboard box B11 shown in Figure 5(A).

[0076] The bending jig 3 comprises a base plate portion 31, a mold portion 32 that forms part of a rectangular mortar frame shape, and four flap guide protrusions 33 positioned at the four corners of the mortar frame shape. The base plate portion 31 is a rectangular plate larger than the bottom wall B111 of the paper box B11, and is an H-shaped plate portion in which a pair of opposing short sides are cut out to form a rectangular recess 311.

[0077] The formwork section 32 comprises four first frame sections 321, each extending along the shorter sides of the base plate section 31 other than the rectangular recess 311, and a pair of opposing second frame sections 322, extending along the longer sides of the base plate section 31. In this formwork section 32, the first frame sections 321 and the pair of second frame sections 322 along the shorter sides have a flattened frame shape in which the height dimension L31 is shorter than the length dimensions L32 and L33.

[0078] The first frame portion 321 has a first inclined surface portion 321a that abuts against and folds up against the first side wall B112a of the paper box B11, on which the flap wall B113 is provided, and is a block body formed of expanded polystyrene with a trapezoidal cross-section. The second frame portion 322 has a second inclined surface portion 322a that abuts against and folds up against the second side wall B112b of the paper box B11, and is a block body formed of expanded polystyrene with a trapezoidal cross-section.

[0079] In this formwork section 32, the recessed space extending from the gap between the first frame sections 321, which are arranged with the rectangular recesses 311 in between, to the rectangular recesses 311 is used as an access recess 36 into which a hand can be inserted when the completed paper box B11 is removed from the inside of the mortar-shaped frame.

[0080] The four flap guide projections 33 are projections erected on the base plate portion 31 at the four corners of the mortar-shaped formwork portion 32, projecting to a position higher than the first inclined surface portion 321a and the second inclined surface portion 322a in the normal direction D33 to the base plate portion 31. Each flap guide projection 33 has a flap guide inclined surface 331 formed at its tip, and each flap guide inclined surface 331 is inclined in the same direction as the second inclined surface portion 322a, but with a gentler slope than the second inclined surface portion 322a.

[0081] The bending jig 3 described above is constructed by combining a single base plate portion 31, four first frame portions 321, two second frame portions 322, and four flap guide projections 33, each individually formed from foamed steel, by adhesive bonding. Specifically, the four flap guide projections 33 are bonded to the four corners of the base plate portion 31, and the four first frame portions 321 are bonded to the base plate portion 31 along the short side of the base plate portion 31 between the flap guide projections 33 and the rectangular recesses 311. In addition, the two second frame portions 322 are bonded to the base plate portion 31 along the long side of the base plate portion 31 between two flap guide projections 33. For these bonding processes, for example, double-sided tape is used. The bending jig 3 is formed through this bonding process.

[0082] In this reference example, the above-described bending jig 3 is prepared for each size of the paper box to be formed, and the paper box is formed by bending using a method equivalent to the bending method in the first embodiment described with reference to Figures 6 and 7.

[0083] The bending jig 3 and bending method described above, as in the first embodiment described above, can reduce material costs and manufacturing costs compared to, for example, metal jigs, thereby lowering the product cost. Furthermore, it goes without saying that, according to this reference example, the weight can also be reduced compared to, for example, metal jigs.

[0084] It should be noted that the first and second embodiments described above are merely representative examples, and the bending jigs and bending methods are not limited to these embodiments. In other words, those skilled in the art can implement them in various modified forms according to conventionally known knowledge.

[0085] For example, in the first and second embodiments described above, the following paper boxes B11 and B12 are given as examples of paper boxes to be formed. Specifically, paper boxes B11 and B12 are given as examples, which have bottom walls B111 and B121, side walls B112 and B122, flap walls B113 and B123, inner doors B114 and B124, and outer doors B115 and B125. However, the paper boxes to be formed are not limited to these, and any box having at least a bottom wall, side walls, and flap walls may be an open box without inner or outer doors. An example of using such an open box is to use one open box as an inner box and a slightly larger open box as a lid box.

[0086] Furthermore, in the first embodiment described above, a bending jig 1 is exemplified as an example of a bending jig in which the opposing spacing L11, L12 of the pair of opposing inclined surfaces in the formwork portion 12 can be changed along with the arrangement of each flap guide projection 13. However, the bending jig is not limited to this, and as exemplified in the second embodiment, the opposing spacing of the inclined surfaces and the arrangement of the flap guide projections may remain unchanged. However, as mentioned above, costs can be further reduced by making the opposing spacing L11, L12 of the inclined surfaces and the arrangement of the flap guide projections 13 changeable.

[0087] Furthermore, in the first embodiment described above, as an example of how to change the distance between the opposing inclined surfaces, a method of changing the mounting position of the C-shaped frame portion 121 on the base portion 11 is exemplified. However, the method of changing the distance between the opposing inclined surfaces is not limited to this, and may also be, for example, a method of sliding a sliding part having an inclined surface portion on the base portion. However, as mentioned above, by changing the mounting position of the C-shaped frame portion 121, the distance between the opposing surfaces L11 and L12 can be easily changed. In the first embodiment, two types of mounting positions for the C-shaped frame portion 121 are exemplified to realize two types of distances, long and short, corresponding to two sizes of paper boxes. However, the mounting positions of the changeable C-shaped frame portion 121 are not limited to two types, and any type of mounting position can be set.

[0088] Furthermore, in the first embodiment described above, an example of how the C-shaped frame portion is attached to the base portion is shown in which mounting recesses 111 and 112 are provided on the base portion 11 and a mounting projection 121g is provided on the C-shaped frame portion 121. However, the attachment configuration of the C-shaped frame portion is not limited to this, and any configuration can be adopted. However, as mentioned above, the attachment configuration using the mounting recesses 111 and 112 of the base portion 11 and the mounting projection 121g of the C-shaped frame portion 121 makes it even easier to change the opposing spacing L11 and L12 of the inclined surface portions.

[0089] Furthermore, in the first and second embodiments described above, as an example of a flap guide projection, flap guide inclined surfaces 131 and 231 are provided, which are inclined in the same direction as one of the two pairs of opposing inclined surfaces. However, the flap guide projection is not limited to this, and may be a rod-shaped portion without any inclined surface at its tip. Even if an inclined surface is provided at the tip, the direction of the inclination may be different from that of any of the inclined surfaces in the formwork portion. However, as mentioned above, by providing flap guide inclined surfaces 131 and 231 inclined in the same direction as the inclined surfaces of the formwork portions 12 and 22 at the tips of the flap guide projections 13 and 23, the flap walls B113 and B123 can be guided effectively.

[0090] Furthermore, in the first and second embodiments described above, as an example of a flap guide inclined surface, flap guide inclined surfaces 131 and 231 that are sloped at a gentler gradient than the inclined surface portion of the formwork parts 12 and 22 are shown. However, the flap guide inclined surface is not limited to this, and may have the same gradient as the inclined surface portion of the formwork, or it may have a steeper gradient. However, as mentioned above, by making the flap guide inclined surfaces 131 and 231 sloped at a gentler gradient than the inclined surface portion of the formwork parts 12 and 22, the strength of the tip portions of the flap guide projections 13 and 23 can be improved.

[0091] Furthermore, in the first and second embodiments described above, as an example of a flap guide inclined surface, flap guide inclined surfaces 131 and 231 are shown that are oriented in the same direction as the second inclined surface portions 121e and 222a that fold up the second side walls B112b and B122b of the paper boxes B11 and B12. However, the flap guide inclined surface is not limited to this, and the direction of its inclination may be set independently of the direction of the inclined surface portion in the formwork. However, as mentioned above, by oriented the flap guide inclined surfaces 131 and 231 in the same direction as the second inclined surface portions 121e and 222a, the flap walls B113 and B123 can be guided well and folded inward into the second side walls B112b and B122b.

[0092] Furthermore, in the first and second embodiments described above, a backing portion 11, 21 is exemplified as an example of a backing portion, formed by stacking two or more sheets (specifically two sheets) of corrugated cardboard. However, the backing portion is not limited to this, and may be formed from only one sheet of corrugated cardboard. However, as mentioned above, using a backing portion 11, 21 made of two or more sheets of corrugated cardboard improves the strength of the bending jigs 1, 2.

[0093] Furthermore, in the first and second embodiments described above, formwork sections 12 and 22, which are made up of cylindrical parts formed by folding corrugated cardboard, are shown as an example of formwork sections. However, the formwork section is not limited to this, and as long as it is made of paper and forms at least a part of a rectangular mortar-shaped frame, the material may be cardboard other than corrugated cardboard, and any form other than a combination of cylindrical parts can be adopted. However, as mentioned above, formwork sections 12 and 22 made up of cylindrical parts of corrugated cardboard can improve the strength while keeping the weight of the bending jigs 1 and 2 down.

[0094] Furthermore, in the first and second embodiments described above, an example of a cylindrical corrugated cardboard portion constituting the formwork is shown in which through holes 15 and 25 for adhesive work are formed in its outer wall. However, the cylindrical portion constituting the formwork is not limited to this, and it is also possible to not provide any through holes in its outer wall. However, as mentioned above, the formation of through holes 15 and 25 in the outer wall of the cylindrical portion of the formwork 12 and 22 allows for adhesive work in the cylindrical portion to be carried out with good workability.

[0095] Furthermore, in the first and second embodiments described above, flap guide projections 13 and 23 formed by folding corrugated cardboard into a cylindrical shape are exemplified as examples of flap guide projections. However, the flap guide projections are not limited to these, and the material may be cardboard other than corrugated cardboard, and any shape other than cylindrical can be adopted. However, as mentioned above, forming the flap guide projections 13 and 23 into a cylindrical shape from corrugated cardboard makes it possible to reduce the weight of the bending jigs 1 and 2 while improving their strength.

[0096] Furthermore, in the first and second embodiments described above, as an example of a formwork section, formwork sections 12 and 22 are provided with removal recesses 16 and 26 for removing the paper boxes B11 and B12. However, the formwork section is not limited to this, and may be one without removal recesses, etc. However, as mentioned above, with formwork sections 12 and 22 provided with removal recesses 16 and 26, the completed paper boxes B11 and B12 can be removed from the inside of the formwork sections 12 and 22 with good workability.

[0097] Furthermore, in the first and second embodiments described above, flat rectangular paper boxes B11 and B12 are exemplified as examples of paper boxes to be formed, and formwork parts 12 and 22 having at least a part of a flat frame shape are exemplified as examples of formwork parts. However, the paper boxes and formwork parts to be formed are not limited to such flat shapes, and may be deep rectangular boxes or rectangular frames. However, as mentioned above, considering that flat rectangular boxes are often used as paper boxes having a bottom wall, side walls, and flap walls, bending jigs 1 and 2 that have flat frame-shaped formwork parts 12 and 22 to bend and form flat rectangular paper boxes B11 and B12 are preferred. [Explanation of Symbols]

[0098] 1, 2, 3 Bending jigs 11,21 Mounting board section 11a Backing sheet 12,22,32 Formwork section 13, 23, 33 Flap guide projection 14. Formwork development sheet with protrusions 15,25 Through holes 16, 26, 36 Removal recess 16a, 26a Recessed portion 24 Main Expansion Sheet 31 Base plate section 111,112 Mounting recess 111a, 112a Through-holes in the mounting board 121 C-shaped frame section 121a Trapezoidal cylindrical section 121b Arm barrel part 121c Overlapping wall section 121d,221a,321a 1st slope part 121e, 222a, 322a 2nd slope part 121f Arm-shaped inclined surface part 121g Mounting protrusion 131,231 Flap guide inclined surface 141 Formwork sheet section 141a Trapezoidal cylindrical sheet section 141a-1, 141b-1, 142-1, 242a, 243a, 244a Fold 141b Arm tube seat section 141c Overlay wall sheet section 142,244 Protruding sheet portion 211 Main mounting board 212 Reinforcement cardboard 212a Reinforcement backing sheet 221,321 First section 222,322 Second section 241 Backing sheet portion 242 First formwork sheet section 243 Second formwork sheet section 311 Rectangular recess B11,B12 Paper box B11a, B12a unfolding sheet B111,B121 Bottom wall B112,B122 side wall B112a,B122a 1st side wall B112a-1,B122a-1 side edge B112b,B122b 2nd side wall B113, B123 Flap Wall B114, B124 Inner Door B114a, B124a Slit section B115,B125 Outer door B115a,B125a Insert tongue piece B115b, B125b recessed area LB11 Width Dimension LB12, LB13, L14, L22, L23, L32, L33 Length dimensions D11 Pressing direction D12 Standing direction D13, D23, D33 Normal Direction D14,D24 In-plane direction D15 First folding direction D16 2nd folding direction L11,L12 Opposing distance L13, L21, L31 Height dimensions S11 Placement process S12 Pressing process S13 Closure process S14 Extraction Process S121 Stage 1 S122 Stage 2

Claims

1. A folding jig for folding and forming a paper box from an unfolded sheet of the paper box, having at least four flap walls, one pair for each of the four opposing first side walls, where a pair of side edges intersecting the aforementioned edges of the first side walls are folded inward into the other opposing pair of second side walls, the box having a rectangular plate-shaped bottom wall, four side walls folded up along the four edges of the bottom wall, and a total of four flap walls, one pair for each of the four opposing first side walls, the folding jig for the box having a rectangular plate-shaped bottom wall, four side walls folded up along the four edges of the bottom wall, and a pair of flap walls for each of the four opposing first side walls, one pair for each first side wall and the folding jig for the box having a rectangular plate-shaped bottom wall, four side walls folded up along the four edges of the bottom wall, and a pair of flap walls where the pair of side edges intersecting with the aforementioned edges are folded inward into A paper base portion formed in a plate shape larger than the bottom wall, A paper mold portion is provided on the base portion and has a rectangular frame shape that houses the paper box inside, and at least a part of the mortar-shaped frame has an inclined surface on the upper surface opposite to the base portion that approaches the base portion as it moves toward the inner circumference, and when the unfolded sheet is placed on the upper surface and pushed toward the base portion such that the bottom wall is located inside the mortar-shaped frame, the four side walls are folded up along the inclined surface, These are four flap guide projections erected on the base or formwork portion at the four corners of the mortar-shaped frame, projecting to a position higher than the inclined surface in the direction normal to the base portion, and which, when the unfolding sheet is placed on the formwork portion, push up and fold the four flap walls, and when the unfolding sheet is pushed in, guide the four flap walls inward toward the opposing pair of second side walls and fold them. A bending jig characterized by having the following features.

2. The formwork portion is provided such that the distance between opposing inclined surfaces can be changed for at least one pair of the two pairs of opposing inclined surfaces that form the inclined surface of the mortar frame shape. The bending jig according to claim 1, characterized in that the arrangement of each of the four flap guide protrusions can be changed in accordance with the change in the opposing spacing in the formwork portion.

3. The formwork portion comprises a pair of opposing C-shaped formwork portions that are detachably attached to the base portion, each having one first inclined surface portion in one of the pair of opposing first inclined surface portions, and a pair of arm-shaped inclined surface portions that extend from both ends of the first inclined surface portion and form part of the pair of opposing second inclined surface portions. The bending jig according to claim 2, characterized in that the four flap guide protrusions are integrally formed in pairs on each C-shaped frame portion of the opposing pair of C-shaped frame portions.

4. Each of the four flap guide projections has a flap guide inclined surface formed at its tip that guides the four flap walls toward the inside of the opposing pair of second side walls. The bending jig according to claim 1, characterized in that each of the flap guide inclined surfaces is inclined in the same direction as one of the two pairs of opposing inclined surface portions that make up the inclined surface of the mortar frame shape.

5. The bending jig according to claim 4, characterized in that each of the flap guide inclined surfaces is inclined with a gentler slope than the other pair of inclined surface portions.

6. A placing step of placing the unfolded sheet on the bending jig according to any one of claims 1 to 5 such that the four side walls are positioned on the inclined surface of the formwork portion and the four flap walls are positioned on the four flap guide protrusions, A pressing step in which the bottom wall of the unfolded sheet is pressed toward the base sheet to cause the four side walls to fold up and the four flap walls to fold in, A bending method characterized by comprising the following features.

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