Method for manufacturing a backrest of a backpack and method for manufacturing a backpack

Abstract

To provide a manufacturing method of a back pad of a backpack and a manufacturing method of a backpack which can keep softness of a cushion material by preventing the cushion material from being crushed.SOLUTION: A manufacturing method of a back pad of a backpack includes the following steps of: thermally molding an exterior fabric 5 so as to form a protrusion 5b protruding from a plane part 5a; thermally molding a cushion material 6 along the plane part 5a and the protrusion 5b; and fusion-cutting the exterior fabric 5 and a back plate 4 in such a state that the cushion material 6 is sandwiched between the exterior fabric 5 and the back plate 4 such that the cushion material 6 is fit to the protrusion 5b.SELECTED DRAWING: Figure 15

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a backrest of a backpack and a method for manufacturing a backpack.

Background Art

[0002] Conventionally, a cushioning material made of a foam such as sponge has been used for the backrest of a backpack such as a schoolbag. Such a backpack is described in, for example, Japanese Patent Application Laid-Open No. 2016-146936 (Patent Document 1). In this publication, when the backrest of the backpack is manufactured, a mold pressing is performed with a cushioning material sandwiched between an outer fabric and a back plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above publication, when the backrest of the backpack is manufactured, a mold pressing is performed with a flat outer fabric placed on a three-dimensional cushioning material. For this reason, the cushioning material is crushed, making the cushioning material hard.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a method for manufacturing a backrest of a backpack and a method for manufacturing a backpack that can maintain the softness of the cushioning material by suppressing the crushing of the cushioning material.

Means for Solving the Problems

[0006] The manufacturing method of the backrest of the backpack of the present invention comprises the following steps. The outer fabric is thermoformed so as to form a convex portion protruding from the flat portion. The cushioning material is thermoformed into a shape along the flat portion and the convex portion. The outer fabric and the back plate are cut while sandwiching the cushioning material between the outer fabric and the back plate so that the cushioning material fits into the convex portion. In the step of thermoforming the outer fabric, when the lower mold for the outer fabric and the upper mold for the outer fabric are clamped together with the outer fabric sandwiched therebetween, The upper-type concave portion for exterior fabric, which is recessed downward from the upper-type flat portion for exterior fabric, receives the lower-type convex portion for exterior fabric that protrudes upward from the lower-type flat portion of the lower mold for exterior fabric. the outer fabric upper mold recess of the outer fabric upper mold receives the outer fabric lower mold protrusion of the outer fabric lower mold The flat portion is formed by the portion of the exterior fabric sandwiched between the lower-type flat portion for exterior fabric and the upper-type flat portion for exterior fabric, and the convex portion is formed by the portion of the exterior fabric sandwiched between the lower-type convex portion for exterior fabric and the upper-type concave portion for exterior fabric. The lower mold protrusion for exterior fabric is configured to surround the lower mold convex portion for exterior fabric when viewed from above. The upper mold depression for exterior fabric is configured to surround the upper mold concave portion for exterior fabric when viewed from below. .

Effect of the Invention

[0007] According to the manufacturing method of the backrest of the backpack of the present invention, it is possible to maintain the softness of the cushioning material by suppressing the cushioning material from being crushed.

Brief Description of the Drawings

[0008]

Figure 1

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Figure 16

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The backpack of this embodiment will be described by taking a schoolbag as an example. In the following, the same or corresponding parts will be denoted by the same reference numerals, and repeated descriptions will not be repeated.

[0010] With reference to FIGS. 1 and 2, the configuration of the backpack R of this embodiment will be described.

[0011] With reference to FIG. 1, the backpack R of this embodiment mainly has a backrest 1, a pair of shoulder straps 2, a fixture 3, a storage portion B, and a lid portion C.

[0012] The backrest 1 is a portion that contacts the user's back when the user carries the backpack R. The pair of shoulder straps 2 are configured to be worn on both shoulders of the user when the user carries the backpack R. The pair of shoulder straps 2 are attached to the backrest 1 by a fixture 3.

[0013] The fixture 3 is fixed to the central portion in the left-right direction at the upper end portion in the up-down direction of the backrest 1. The fixture 3 has a mounting portion 3a capable of receiving the upper end portion of each of the pair of shoulder straps 2. The fixture 3 is fixed to the backrest 1 with the mounting portion 3a directed upward. The upper end portion of each of the pair of shoulder straps 2 is connected to the upper end portion of the backrest 1 by being received in the mounting portion 3a. Therefore, the shoulder strap 2 is attached to the mounting portion 3a so as to face upward from the backpack R.

[0014] Therefore, when the user wears the backpack R, the backpack R is always pulled obliquely upward, and the shoulder belt 2 bends along the user's shoulder, so that the backrest 1 can fit well against the user's back.

[0015] The storage part B has a side surface part B1, a front surface part B2, a bottom surface part B3, and an opening part B4. The side surface part B1 is connected to both the left and right sides of the backrest 1 respectively. The front surface part B2 faces the backrest 1. Both the left and right sides of the front surface part B2 are connected to the side surface part B1. The bottom surface part B3 is connected to the lower ends of the backrest 1, the side surface part B1, and the front surface part B2 respectively. The opening part B4 is provided at the upper ends of the backrest 1, the side surface part B1, and the front surface part B2 respectively.

[0016] The lid part C is connected to the upper end of the backrest 1 so as to be able to open and close the opening part B4. The lid part C is provided so as to be able to cover the opening part B4 and the front surface part B2. Also, the lower end part of each of the pair of shoulder belts 2 is configured to be connectable to a fastener (not shown) provided on the bottom surface part B3. Each of the pair of shoulder belts 2 is made of a thick leather fabric or a synthetic resin fabric.

[0017] Referring to FIG. 2, the configuration of the backrest 1 will be described in more detail.

[0018] The backrest 1 mainly has a back plate 4, an outer fabric 5, and a cushion material 6. The back plate 4 is made of a rigid material such as plastic, for example. The back plate 4 is preferably made of an elastic material. In the present embodiment, the back plate 4 is made of a square plate.

[0019] The exterior fabric 5 is fixed to the back plate 4. The exterior fabric 5 is composed of, for example, a non-woven fabric bonded to the back surface of an artificial leather fabric made of a synthetic resin material. The synthetic resin material is, for example, polyurethane. The exterior fabric 5 is preferably composed of a highly stretchable material. As this stretchability, an elongation of 5% or more is preferable. The exterior fabric 5 is preferably composed of a highly breathable material. The thickness of the exterior fabric 5 is, for example, 1 mm or more and 2 mm or less.

[0020] A cushioning material 6 is sandwiched between the exterior fabric 5 and the back plate 4. The cushioning material 6 is disposed on the back plate 4. The cushioning material 6 is configured to protrude toward the exterior fabric 5 side with respect to the back plate 4. That is, the cushioning material 6 is configured to protrude from the back plate 4 toward the user's back side when the user wears the backpack R.

[0021] The cushioning material 6 is configured such that the thickness increases from the upper part to the lower part of the back plate 4. The cushioning material 6 is configured such that the thicknesses on both the left and right sides of the back plate 4 are larger than the thickness at the center.

[0022] The cushioning material 6 is composed of a single foam. In the present embodiment, the cushioning material 6 is composed of EVA (ethylene-vinyl acetate copolymer resin). Note that the cushioning material 6 may be composed of a polyurethane foam. Note that the cushioning material 6 is not limited as long as it is a material preferable for raising the backrest 1 into an appropriate shape such as a sponge. The maximum thickness of the cushioning material 6 is, for example, 30 mm or more and 50 mm or less. The maximum thickness of the cushioning material 6 is preferably 40 mm, for example.

[0023] With reference to FIGS. 3 to 16, a method for manufacturing the backrest 1 of the backpack R according to the present embodiment will be described. The method for manufacturing the backrest 1 of the backpack R according to the present embodiment includes a step of thermoforming the exterior fabric 5, a step of thermoforming the cushioning material 6, and a step of fusing and cutting.

[0024] Referring to FIGS. 3 to 7, the process of thermoforming the exterior fabric 5 will be described. In the process of thermoforming the exterior fabric 5, a mold M1 for the exterior fabric is used. The mold M1 for the exterior fabric has a lower mold M11 for the exterior fabric and an upper mold M12 for the exterior fabric. The lower mold M11 for the exterior fabric and the upper mold M12 for the exterior fabric are configured to be clamped to each other.

[0025] Referring to FIG. 3, the lower mold M11 for the exterior fabric has a cut surface M11a of the lower mold for the exterior fabric. The cut surface M11a of the lower mold for the exterior fabric constitutes the upper surface of the lower mold M11 for the exterior fabric. The cut surface M11a of the lower mold for the exterior fabric has a flat portion M11a1 of the lower mold for the exterior fabric, a convex portion M11a2 of the lower mold for the exterior fabric, and a protruding portion M11a3 of the lower mold for the exterior fabric. The flat portion M11a1 of the lower mold for the exterior fabric is configured in a planar shape. The convex portion M11a2 of the lower mold for the exterior fabric protrudes upward from the flat portion M11a1 of the lower mold for the exterior fabric. The convex portion M11a2 of the lower mold for the exterior fabric is disposed at the center of the upper surface of the lower mold M11 for the exterior fabric when viewed from above. The protruding portion M11a3 of the lower mold for the exterior fabric protrudes upward from the flat portion M11a1 of the lower mold for the exterior fabric. The protruding portion M11a3 of the lower mold for the exterior fabric is configured to surround the convex portion M11a2 of the lower mold for the exterior fabric when viewed from above.

[0026] Referring to FIG. 4, the upper mold M12 for exterior fabric has an upper mold cut surface M12a for exterior fabric. In FIG. 4, for the sake of convenience of explanation, the lower surface of the upper mold M12 for exterior fabric is arranged on the upper side. The upper mold cut surface M12a for exterior fabric constitutes the lower surface of the upper mold M12 for exterior fabric. The upper mold cut surface M12a for exterior fabric has an upper mold flat portion M12a1, an upper mold concave portion M12a2, and an upper mold depression portion M12a3. The upper mold flat portion M12a1 is configured in a flat shape. The upper mold concave portion M12a2 is recessed downward from the upper mold flat portion M12a1. The upper mold concave portion M12a2 is arranged at the center of the lower surface of the upper mold M12 when viewed from below. The upper mold depression portion M12a3 is recessed downward from the upper mold flat portion M12a1. The upper mold depression portion M12a3 is configured to surround the upper mold concave portion M12a2 when viewed from below.

[0027] Referring to FIG. 5, the exterior fabric 5 is configured in a sheet shape. The exterior fabric 5 is composed of one member.

[0028] Referring to FIG. 6, the lower mold M11 for exterior fabric and the upper mold M12 for exterior fabric are clamped together with the exterior fabric 5 sandwiched therebetween. The exterior fabric 5 covers the lower mold cut surface M11a and the upper mold cut surface M12a for exterior fabric. When the lower mold M11 for exterior fabric and the upper mold M12 for exterior fabric are clamped together, the upper mold concave portion M12a2 receives the lower mold convex portion M11a2. By applying heat and pressure to the exterior fabric 5 by the mold M1 for exterior fabric, the exterior fabric 5 is thermoformed. As a result, a flat portion 5a and a convex portion 5b protruding from the flat portion 5a are formed on the exterior fabric 5. The flat portion 5a is formed by the portion of the exterior fabric 5 sandwiched between the lower mold flat portion M11a1 and the upper mold flat portion M12a1 for exterior fabric. The convex portion 5b is formed by the portion of the exterior fabric 5 sandwiched between the lower mold convex portion M11a2 and the upper mold concave portion M12a2.

[0029] Thermoforming is performed, for example, at atmospheric pressure. The temperature of thermoforming is, for example, 120°C. The time of thermoforming is, for example, 45 seconds.

[0030] In the present embodiment, when the lower mold M11 for exterior fabric and the upper mold M12 for exterior fabric are clamped together, the recess M12a3 in the upper mold for exterior fabric receives the protrusion M11a3 in the lower mold for exterior fabric. For this reason, the exterior fabric 5 is sandwiched between the recess M12a3 in the upper mold for exterior fabric and the protrusion M11a3 in the lower mold for exterior fabric. Thereby, it is possible to suppress the exterior fabric 5 from being pulled inward.

[0031] Referring to FIG. 7, the convex portion M11a2 of the lower mold for exterior fabric is formed so as to curve while spreading outward toward the flat portion M11a1 of the lower mold for exterior fabric. The concave portion M12a2 of the upper mold for exterior fabric is formed so as to curve while spreading outward toward the flat portion M12a1 of the upper mold for exterior fabric. For this reason, in the step of thermoforming the exterior fabric 5, the convex portion 5b is formed so as to curve while spreading outward toward the flat portion 5a.

[0032] Referring to FIGS. 8 to 11, the step of thermoforming the cushion material 6 will be described. In the step of thermoforming the cushion material 6, a mold M2 for cushion material is used. The mold M2 for cushion material has a lower mold M21 for cushion material and an upper mold M22 for cushion material. The lower mold M21 for cushion material and the upper mold M22 for cushion material are configured to be clamped together.

[0033] Referring to FIG. 8, the lower mold M21 for cushioning material has a lower mold section M21a for cushioning material. The lower mold section M21a for cushioning material constitutes the upper surface of the lower mold M21 for cushioning material. The lower mold section M21a for cushioning material has a flat part M21a1 of the lower mold for cushioning material and a recess M21a2 of the lower mold for cushioning material. The flat part M21a1 of the lower mold for cushioning material is configured in a flat shape. The recess M21a2 of the lower mold for cushioning material is recessed downward from the flat part M21a1 of the lower mold for cushioning material. The recess M21a2 of the lower mold for cushioning material is arranged at the center of the upper surface of the lower mold M21 for cushioning material when viewed from above.

[0034] Referring to FIG. 9, the upper mold M22 for cushioning material has an upper mold section M22a for cushioning material. In FIG. 9, for the convenience of explanation, the lower surface of the upper mold M22 for cushioning material is arranged on the upper side. The upper mold section M22a for cushioning material constitutes the lower surface of the upper mold M22 for cushioning material. The upper mold section M22a for cushioning material is configured in a flat shape.

[0035] Referring to FIG. 10, the cushioning material 6 is approximated to the shape of the recess M21a2 of the lower mold for cushioning material. The cushioning material 6 is composed of one member.

[0036] Referring to FIG. 11, the lower mold M21 for cushioning material and the upper mold M22 for cushioning material are clamped together with the cushioning material 6 sandwiched therebetween. Heat and pressure are applied to the cushioning material 6 by the mold M2 for cushioning material, whereby the cushioning material 6 is thermoformed. Thereby, the cushioning material 6 is formed in a shape along the flat part 5a and the convex part 5b of the exterior fabric 5 shown in FIG. 6. It is preferable that the cushioning material 6 is formed in the same shape as the shape of the exterior fabric 5. That is, it is preferable that the cushioning material 6 is formed so as to follow the flat part 5a and the convex part 5b of the exterior fabric 5 without gaps.

[0037] The thermoforming is performed, for example, at atmospheric pressure. The temperature of the thermoforming is, for example, 230 °C. The time of the thermoforming is, for example, 120 seconds.

[0038] Referring to FIGS. 12 to 16, the fusing process will be described. In the fusing process, a fusing die M3 is used. The fusing die M3 has a lower fusing die M31 and an upper fusing die M32. The lower fusing die M31 and the upper fusing die M32 are configured to be clamped together.

[0039] Referring to FIG. 12, the lower fusing die M31 has a lower fusing die surface M31a. Note that the lower fusing die surface M31a constitutes the upper surface of the lower fusing die M31. The lower fusing die surface M31a is configured to be planar.

[0040] Referring to FIG. 13, the upper fusing die M32 has an upper fusing die surface M32a. In FIG. 13, for the sake of convenience of explanation, the lower surface of the upper fusing die M32 is arranged on the upper side. The upper fusing die surface M32a constitutes the lower surface of the upper fusing die M32. The upper fusing die surface M32a has an upper fusing die flat portion M32a1 and an upper fusing die recess M32a2. The upper fusing die flat portion M32a1 is configured to be planar. The upper fusing die recess M32a2 is recessed upward from the upper fusing die flat portion M32a1. The upper fusing die recess M32a2 is arranged at the center of the lower surface of the upper fusing die M32 when viewed from below.

[0041] Referring to FIG. 14, the back plate 4, the cushioning material 6, and the outer fabric 5 are stacked in this order. The cushioning material 6 is stacked on the outer fabric 5 so that the protrusion 6a of the cushioning material 6 aligns with the convex portion 5b of the outer fabric 5. The outer fabric 5 covers the back plate 4 and the cushioning material 6. In the present embodiment, when the cushioning material 6 is placed on the back plate 4 before fusing, the cushioning material 6 is cut in accordance with the outer edge of the convex portion 5b of the outer fabric 5. The cut cushioning material 6 is positioned on the back plate 4, and the outer fabric 5 is placed on the back plate 4 and the cushioning material 6.

[0042] Before the cushion material 6 is fitted into the convex portion 5b in the fusing step, the volume of the shape along the convex portion 5b of the cushion material 6 heat-formed in the step of heat-forming the cushion material 6 is larger than the internal volume of the convex portion 5b of the exterior fabric 5 heat-formed in the step of heat-forming the exterior fabric 5. The shape along the convex portion 5b of the heat-formed cushion material 6 may be, for example, 3.5% larger in each of the vertical and horizontal directions than the convex portion 5b of the heat-formed exterior fabric 5.

[0043] Referring to FIG. 15, the exterior fabric 5 and the back plate 4 are fused in a state where the cushion material 6 is sandwiched between the exterior fabric 5 and the back plate 4 so that the cushion material 6 is fitted into the convex portion 5b. It is preferable that the upper surface of the cushion material 6 is in contact with the lower surface of the exterior fabric 5.

[0044] Referring to FIG. 16, if necessary, the exterior fabric 5 protruding from the back plate 4 is cut off. In this way, the backrest 1 is manufactured.

[0045] Referring to FIGS. 1 and 16, a method for manufacturing the backpack R of the present embodiment will be described.

[0046] The backrest 1 manufactured by the method for manufacturing the backrest 1 of the backpack R of the present embodiment, the fixture 3 to which the pair of shoulder straps 2 are attached, the storage portion B, and the lid portion C are prepared. The fixture 3 to which the pair of shoulder straps 2 are attached, the storage portion B, and the lid portion C are attached to the backrest 1. Thereby, the backpack R is manufactured.

[0047] Next, the effects of the present embodiment will be described.

[0048] According to the method for manufacturing the backrest 1 of the backpack R of the present embodiment, the exterior fabric 5 and the back plate 4 are fused in a state where the cushion material 6 is sandwiched between the exterior fabric 5 and the back plate 4 so that the cushion material 6 is fitted into the convex portion 5b of the exterior fabric 5. By suppressing the cushion material 6 from being crushed, the softness of the cushion material 6 can be maintained.

[0049] In the manufacturing method of the backrest 1 of the backpack R according to this embodiment, the cushion material 6 can be made to fit the shape of the exterior fabric 5 without gaps by thermoforming the cushion material 6 into the same shape as the convex portion 5b of the exterior fabric 5. Therefore, it is possible to suppress variations in the gaps between the exterior fabric 5 and the cushion material 6 and the occurrence of wrinkles due to the gaps caused by the different shapes of the exterior fabric 5 and the cushion material 6. As a result, it is possible to reduce the defect rate due to appearance differences and shorten the inspection time and labor.

[0050] In the manufacturing method of the backrest 1 of the backpack R according to this embodiment, the exterior fabric 5 is thermoformed in advance so as to form the convex portion 5b. When the die pressing is performed with the flat exterior fabric 5 placed on the three-dimensional cushion material 6, the cushion material 6 and the back plate 4 are pulled on the exterior fabric 5. As a result, the backrest 1 warps toward the exterior fabric 5 side. In this embodiment, since the exterior fabric 5 is thermoformed in advance so as to form the convex portion 5b, it is possible to suppress the backrest 1 from warping toward the exterior fabric 5 side in a state where the exterior fabric 5 and the back plate 4 are cut off.

[0051] In the manufacturing method of the backrest 1 of the backpack R according to this embodiment, the cushion material 6 is thermoformed in advance. Therefore, the cushion material 6 can have an appearance with smooth curved roundness compared to the case of a sponge or the like where the cushion material 6 is only cut. Also, the cushion material 6 can have an appearance with a height difference between high and low places compared to the case of a sponge or the like where the cushion material 6 is only cut. Therefore, the degree of freedom in the design of the cushion material 6 can be improved.

[0052] In the manufacturing method of the backrest 1 of the backpack R according to this embodiment, since the cushion material 6 is thermoformed in advance, even when the cushion material 6 is composed of a single member, it is possible to sufficiently ensure the thickness of the cushion material 6.

[0053] In the manufacturing method of the backrest 1 of the backpack R of the present embodiment, since the cushion material 6 is composed of a single member, the assembly of the backrest 1 is easier than in the case where the cushion material 6 is composed of a plurality of members.

[0054] According to the manufacturing method of the backrest 1 of the backpack R of the present embodiment, in the step of thermoforming the exterior fabric 5, the convex portion 5b is formed so as to curve while spreading outward toward the flat portion 5a. If the convex portion 5b is formed so as to stand vertically from the flat portion 5a, a processing line is formed at the boundary between the convex portion 5b and the flat portion 5a. In the present embodiment, since the convex portion 5b is formed so as to curve while spreading outward toward the flat portion 5a, it is possible to suppress the formation of a processing line at the boundary between the convex portion 5b and the flat portion 5a. Thereby, it is possible to reduce the defective rate due to the appearance difference and shorten the inspection time and the inspection labor.

[0055] According to the manufacturing method of the backrest 1 of the backpack R of the present embodiment, before the cushion material 6 is fitted into the convex portion 5b in the step of fusing, the volume of the shape along the convex portion 5b of the cushion material 6 thermoformed in the step of thermoforming the cushion material 6 is larger than the inner volume of the convex portion 5b of the exterior fabric 5 thermoformed in the step of thermoforming the exterior fabric 5. The thermoformed cushion material 6 shrinks as it cools after thermoforming. Therefore, when the volume of the shape along the convex portion 5b of the thermoformed cushion material 6 is the same as the inner volume of the convex portion 5b of the thermoformed exterior fabric 5, a large gap is generated between the cushion material 6 and the exterior fabric 5. In the present embodiment, since the volume of the shape along the convex portion 5b of the thermoformed cushion material 6 is larger than the inner volume of the convex portion 5b of the thermoformed exterior fabric 5, it is possible to suppress the gap between the cushion material 6 and the exterior fabric 5.

[0056] According to the manufacturing method of the backpack R of the present embodiment, an attachment tool 3 to which a pair of shoulder belts 2 are attached, a storage portion B, and a lid portion C are attached to the backrest 1 manufactured by the above manufacturing method. Therefore, it is possible to provide a backpack R that can maintain the softness of the cushion material 6 by suppressing the cushion material 6 from being crushed.

[0057] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Signs

[0058] 1 Backrest, 2 Shoulder belt, 3 Fitting, 4 Back plate, 5 Exterior fabric, 5a Flat part, 5b Convex part, 6 Cushion material, M1 Mold for exterior fabric, M2 Mold for cushion material, M3 Mold for fusing, R Backpack.

Claims

1. A step of thermoforming an exterior fabric so as to form a convex portion protruding from a flat portion; A step of thermoforming a cushioning material into a shape along the flat portion and the convex portion; A step of fusing the exterior fabric and the back plate while sandwiching the cushioning material between the exterior fabric and the back plate so that the cushioning material fits into the convex portion, In the step of thermoforming the exterior fabric, when the lower mold for the exterior fabric and the upper mold for the exterior fabric are clamped together with the exterior fabric sandwiched therebetween, an upper mold recess for the exterior fabric that is recessed downward from the upper mold flat portion for the exterior fabric receives a lower mold convex portion for the exterior fabric that protrudes upward from the lower mold flat portion for the exterior fabric, a depression for the upper mold for the exterior fabric receives a protruding portion for the lower mold for the exterior fabric, the flat portion is formed by a portion of the exterior fabric sandwiched between the lower mold flat portion for the exterior fabric and the upper mold flat portion for the exterior fabric, and the convex portion is formed by a portion of the exterior fabric sandwiched between the lower mold convex portion for the exterior fabric and the upper mold recess for the exterior fabric, The protruding portion for the lower mold for the exterior fabric is configured to surround the lower mold convex portion for the exterior fabric when viewed from above, The depression for the upper mold for the exterior fabric is configured to surround the upper mold recess for the exterior fabric when viewed from below. A method for manufacturing a backrest of a backpack.

2. In the step of thermoforming the exterior fabric, the convex portion is formed so as to curve while spreading outward with respect to the flat portion. The method for manufacturing a backrest of a backpack according to Claim 1.

3. Before the cushioning material fits into the convex portion in the fusing step, the volume of the shape along the convex portion of the cushioning material thermoformed in the step of thermoforming the cushioning material is larger than the internal volume of the convex portion of the exterior fabric thermoformed in the step of thermoforming the exterior fabric. The method for manufacturing a backrest of a backpack according to Claim 1 or 2.

4. A step of manufacturing a backrest of a backpack by the method for manufacturing a backrest of a backpack according to any one of claims 1 to 3, A step of preparing a fixture to which a pair of shoulder straps are attached, a storage portion, and a lid portion, A method for manufacturing a backpack, comprising a step of attaching the fixture to which the pair of shoulder straps are attached, the storage portion, and the lid portion to the backrest.

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