Method for manufacturing metal can, and die set

Abstract

A method for manufacturing a metal can (30) includes a step of preparing a material can (20) and a step of obtaining the metal can (30) by reshaping the material can (20) using a die set (10) including dies (11, 12, 13). The material can (20) includes a peripheral wall (21) including side walls (211, 212) and a bottom wall (22). In the step of reshaping the material can (20), the die (13) is pressed into a space between the dies (11, 12) disposed inside the material can (20) to move the dies (11, 12) away from each other, and side surfaces (113, 123) of the dies (11, 12) are brought into contact with the side walls (211, 212), respectively, to increase the width between the side walls (211, 212). The side surfaces (113, 123) are each formed such that a portion on the opening (23) side is positioned outward of a portion on the bottom wall (22) side in a direction in which the dies (11, 12) move away from each other.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a method for manufacturing a metal can. The present disclosure also relates to a die set for use in manufacturing of a metal can.BACKGROUND ART

[0002] Metal cans that are used as, for example, battery cell cases may be manufactured by deep drawing a metal sheet. However, when metal cans are manufactured through deep drawing, springback occurring after the processing is likely to cause poor dimensional accuracy of the metal cans. It is possible that poor dimensional accuracy of metal cans is eliminated by ironing a metal sheet during deep drawing.

[0003] In the ironing, the clearance between the punch and the die is set smaller than the sheet thickness of the metal sheet serving as a raw material. Thus, a metal can having a wall thinner than the sheet thickness of the original metal sheet is formed by the punch and die. If the original metal sheet has a small sheet thickness, the load applied from the punch and die to the metal sheet in the sheet thickness direction will be increased, which may result in deformation or impairment of the punch and die. Therefore, it is difficult to apply ironing to the manufacturing of thin-walled metal cans.

[0004] Patent Literature 1 discloses a technique in which a metal sheet is formed into a rectangular can-shaped intermediate formed article through primary press forming, and then the intermediate formed article is widened through secondary press forming. In secondary press forming, a two-piece punch is disposed in the intermediate formed article. Then, when a wedge-shaped punch is pressed into the two-piece punch, the two-piece punch moves in a width direction of the intermediate formed article, and tension acts on a wide side wall of the intermediate formed article. According to Patent Literature 1, by applying tension in the width direction in secondary press forming to the intermediate formed article in which canning has occurred in primary press forming, it is possible to alleviate the residual stress in the side wall, reduce canning, and improve the dimensional accuracy of the metal can.CITATION LISTPATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2009-142851SUMMARY OF INVENTIONTECHNICAL PROBLEM

[0006] In Patent Literature 1, in the secondary press forming, which is a step of reshaping the intermediate formed article, the two-piece punch moves in the width direction of the intermediate formed article, thereby widening the intermediate formed article. However, springback may occur in side walls of the intermediate formed article that are in contact with the punch when the punch moves away from the side walls. Because the amount of springback after secondary press forming is greater on the opening side than on the bottom wall side, the side walls of the metal can that were in contact with the punch are inclined inward in the width direction after the secondary press forming. As a result, the width between the side walls is smaller on the opening side of the metal can, and the width between the side walls is larger on the bottom wall side. Accordingly, a metal can with favorable dimensional accuracy may not be obtained.

[0007] An object of the present disclosure is to provide a method for manufacturing a metal can with which the dimensional accuracy of the metal can can be improved.SOLUTION TO PROBLEM

[0008] A method for manufacturing a metal can according to the present disclosure includes a step of preparing a material can and a step of obtaining a metal can by reshaping the material can using a die set. The material can includes a peripheral wall and a bottom wall. The peripheral wall has a tubular shape. The peripheral wall includes a first side wall and a second side wall. The second side wall faces the first side wall. The bottom wall closes one end of the peripheral wall in an axial direction of the peripheral wall. The material can has an opening at the other end of the peripheral wall in the axial direction. The die set includes a first die, a second die, and a third die. In the step of reshaping the material can, the third die is pressed in the axial direction from the opening side into a space between the first die and the second die that are disposed inside the material can to move the first die and the second die away from each other, and a side surface of the first die and a side surface of the second die are brought into contact with the first side wall and the second side wall, respectively, to increase a width between the first side wall and the second side wall. The side surfaces are each formed such that a portion on the opening side is positioned outward of a portion on the bottom wall side in a direction in which the first die and the second die move away from each other.ADVANTAGEOUS EFFECTS OF INVENTION

[0009] With the method for manufacturing a metal can according to the present disclosure, it is possible to improve the dimensional accuracy of the metal can.BRIEF DESCRIPTION OF DRAWINGS

[0010] [FIG. 1] FIG. 1 is a schematic perspective view showing a die set according to a first embodiment. [FIG. 2] FIG. 2 is a longitudinal cross-sectional view of dies included in the die set shown in FIG. 1. [FIG. 3A] FIG. 3A is a schematic diagram illustrating a method for manufacturing a metal can according to the first embodiment. [FIG. 3B] FIG. 3B is a schematic diagram illustrating the method for manufacturing a metal can according to the first embodiment. [FIG. 3C] FIG. 3C is a schematic diagram illustrating the method for manufacturing a metal can according to the first embodiment. [FIG. 3D] FIG. 3D is a schematic diagram illustrating the method for manufacturing a metal can according to the first embodiment. [FIG. 3E] FIG. 3E is a schematic diagram illustrating the method for manufacturing a metal can according to the first embodiment. [FIG. 3F] FIG. 3F is a schematic diagram illustrating the method for manufacturing a metal can according to the first embodiment. [FIG. 4A] FIG. 4A is a schematic diagram illustrating manufacturing of a metal can using a die set different from that of the first embodiment. [FIG. 4B] FIG. 4B is a schematic diagram illustrating manufacturing of a metal can using the die set different from that of the first embodiment. [FIG. 4C] FIG. 4C is a schematic diagram illustrating manufacturing of a metal can using the die set according to the first embodiment. [FIG. 5] FIG. 5 is a schematic longitudinal cross-sectional view showing a die set according to a second embodiment. [FIG. 6] FIG. 6 is a schematic longitudinal cross-sectional view showing the die set according to the second embodiment, showing a state different from that shown in FIG. 5. [FIG. 7] FIG. 7 is a schematic longitudinal cross-sectional view showing a die set according to a third embodiment. [FIG. 8] FIG. 8 is a schematic longitudinal cross-sectional view showing the die set according to the third embodiment, showing a state different from that shown in FIG. 7. [FIG. 9] FIG. 9 is a schematic longitudinal cross-sectional view showing a die set according to a modified example of the third embodiment. [FIG. 10] FIG. 10 is a schematic longitudinal cross-sectional view showing the die set according to the modified example of the third embodiment, showing a state different from that shown in FIG. 9. [FIG. 11] FIG. 11 is a schematic longitudinal cross-sectional view showing a die set according to a fourth embodiment. [FIG. 12] FIG. 12 is a schematic longitudinal cross-sectional view showing a die set according to a modified example of the embodiments. [FIG. 13] FIG. 13 is a schematic longitudinal cross-sectional view showing a die set according to another modified example of the embodiments. [FIG. 14] FIG. 14 is a graph showing results obtained in analysis. DESCRIPTION OF EMBODIMENTS

[0011] A method for manufacturing a metal can according to an embodiment includes a step of preparing a material can and a step of obtaining a metal can by reshaping the material can using a die set. The material can includes a peripheral wall and a bottom wall. The peripheral wall has a tubular shape. The peripheral wall includes a first side wall and a second side wall. The second side wall faces the first side wall. The bottom wall closes one end of the peripheral wall in an axial direction of the peripheral wall. The material can has an opening at the other end of the peripheral wall in the axial direction. The die set includes a first die, a second die, and a third die. In the step of reshaping the material can, the third die is pressed in the axial direction from the opening side into a space between the first die and the second die that are disposed inside the material can to move the first die and the second die away from each other, and a side surface of the first die and a side surface of the second die are brought into contact with the first side wall and the second side wall, respectively, to increase a width between the first side wall and the second side wall. The side surfaces are formed such that a portion on the opening side is positioned outward of a portion on the bottom wall side in a direction in which the first die and the second die move away from each other (first configuration).

[0012] In the manufacturing method according to the first configuration, in order to reshape the prepared material can, the third die is pressed between the first die and the second die inside the material can to move the first die and the second die away from each other. As a result, the first die and the second die push apart the first side wall and the second side wall of the material can while the first die and the second die are respectively in contact with the first side wall and the second side wall, and thus tension is applied to the peripheral wall of the material can, thereby alleviating residual stress in the peripheral wall when the material can is formed. At this time, the side surface of the first die that is in contact with the first side wall of the material can and the side surface of the second die that is in contact with the second side wall of the material can are each formed such that a portion on the opening side is positioned outward of the portion on the bottom wall side in a direction in which the first die and the second die move away from each other. Therefore, the side surface of the first die and the side surface of the second die respectively come into contact with the first side wall and the second side wall on the opening side, and preferentially widen the width between the first side wall and the second side wall on the opening side. As a result, the first side wall and the second side wall are inclined with respect to the axial direction of the material can such that the widths between both side walls is larger on the opening side and smaller on the bottom surface side. Therefore, even if springback occurs in the first side wall and the second side wall when the first die and the second die move away from the first side wall and the second side wall, the first side wall and the second side wall are likely to be parallel or nearly parallel to the axial direction of the material can. As a result, the difference between the opening side and the bottom wall side in the width between the side walls of the reshaped material can (metal can) is reduced, improving the dimensional accuracy of the metal can.

[0013] In the manufacturing method according to the first configuration, x / y ≥ 0.00050 may hold true where, for each of the side surfaces, x represents a distance from an end on the opening side to an end on the bottom wall side in the direction in which the first die and the second die move away from each other, and y represents a length from the end on the opening side to the end on the bottom wall side in a direction in which the third die is pressed (second configuration).

[0014] In the second configuration, x / y is an index indicating the degree of inclination of each of the side surface of the first die and the side surface of the second die. When x / y ≥ 0.00050 holds true, the difference between the opening side and the bottom wall side in the width between the side walls of the metal can are more likely to be reduced. Therefore, it is possible to further improve the dimensional accuracy of the metal can.

[0015] In the manufacturing method according to the first or second configuration, in the step of reshaping the material can, a region of the first side wall that comes into contact with the first die may be pressed by a first pad from an outer side of the material can. Similarly, in the step of reshaping the material can, a region of the second side wall that comes into contact with the second die may be pressed by a second pad from the outer side of the material can (third configuration).

[0016] In the third configuration, when the material can is reshaped, the region of the first side wall that comes into contact with the first die is pressed by the first pad from the outer side of the material can, and the region of the second side wall that comes into contact with the second die is pressed by the second pad from the outer side of the material can. That is, the width between the first side wall and the second side wall is increased in a state in which the first side wall and the second side wall are held from the inside and the outside of the material can. In this case, the shape accuracy of the first side wall and the second side wall can be easily ensured.

[0017] In the manufacturing method according to any one of the first to third configurations, in the step of reshaping the material can, the bottom wall may be supported from the inner side of the material can by a support disposed between the first die and the second die (fourth configuration).

[0018] In the fourth configuration, when the material can is reshaped, a portion of the bottom wall between the first die and the second die that move away from each other is supported from the inner side of the material can by the support. In this case, in the step of reshaping the material can, partial deformation of the bottom wall, for example, bulging of the bottom wall toward the inner side of the material can, can be suppressed.

[0019] The die set according to an embodiment is used to manufacture a metal can. The die set includes the first die, the second die, and the third die. The first die includes a first top surface, a first bottom surface, a first side surface, and a first receiving surface. The first bottom surface is disposed on a side opposite to the first top surface. The first side surface connects the first top surface and the first bottom surface. The first receiving surface is disposed on a side opposite to the first side surface. The second die and the first die are disposed side by side. The second die includes a second top surface, a second bottom surface, a second side surface, and a second receiving surface. The second bottom surface is disposed on a side opposite to the second top surface. The second side surface connects the second top surface and the second bottom surface on a side opposite to the first die. The second receiving surface is disposed on a side opposite to the second side surface. The third die includes a first abutting surface and a second abutting surface. The first abutting surface is a surface for abutting against the first receiving surface. The second abutting surface is disposed on a side opposite to the first abutting surface. The second abutting surface is a surface for abutting against the second receiving surface. The third die is configured such that the width between the first abutting surface and the second abutting surface decreases from one end side to the other end side in the axial direction. The distance between the first receiving surface and the second receiving surface decreases from the first top surface and second top surface side toward the first bottom surface and the second bottom surface side in accordance with the width between the first abutting surface and the second abutting surface. The distance between the first side surface and the second side surface is larger on the first top surface and second top surface side than on the first bottom surface and second bottom surface side (fifth configuration).

[0020] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding configurations are denoted by the same reference signs, and repeated descriptions will not be given.<First Embodiment>[Configuration of Die]

[0021] FIG. 1 is a schematic perspective view showing a die set 10 according to a first embodiment. Referring to FIG. 1, the die set 10 is used to manufacture a metal can. The die set 10 includes a first die 11, a second die 12, and a third die 13.

[0022] When the die set 10 is used, the first die 11 and the second die 12 are arranged side by side. The third die 13 is a die that is to be pressed into a space between the first die 11 and the second die 12. The third die 13 is pressed in the vertical direction against the first die 11 and the second die 12, which are disposed on a horizontal surface, for example. When the die set 10 is used, the dies 11, 12, and 13 may be attached to, for example, a press or other driving machines.

[0023] The third die 13 is capable of relatively moving toward the first die 11 and the second die 12. The third die 13 is attached to, for example, a slide, a hydraulic jack, or other components of a press. The first die 11 and the second die 12 move away from each other as the third die 13 is pressed. In the following description of configurations of the dies 11, 12, and 13, the direction in which the first die 11 and the second die 12 move away from each other is the width direction of the die set 10, and the direction in which the third die 13 is pressed is the axial direction of the die set 10.

[0024] The first die 11 includes a top surface 111, a bottom surface 112, a side surface 113, and a receiving surface 114.

[0025] The top surface 111 is a surface of the first die 11 that is disposed on the side where the third die 13 is pressed. The bottom surface 112 is disposed on a side opposite to the top surface 111. The bottom surface 112 is disposed substantially parallel to the top surface 111. In an example of this embodiment, the top surface 111 and the bottom surface 112 have a substantially rectangular shape. The side surface 113 connects the top surface 111 and the bottom surface 112. The receiving surface 114 is disposed on a side opposite to the side surface 113. The receiving surface 114 is connected to the top surface 111. Corners between the side surface 113 and the top surface 111 and / or the bottom surface 112 may be subjected to R chamfering. A corner between the side surface 113 and a surface adjacent to the side surface 113 other than the top surface 111 and the bottom surface 112 may also be subjected to R chamfering. Similarly, a corner between the receiving surface 114 and the top surface 111 may be subjected to R chamfering. A corner between the receiving surface 114 and a surface adjacent to the receiving surface 114 other than the top surface 111 may also be subjected to R chamfering.

[0026] The second die 12 includes a top surface 121, a bottom surface 122, a side surface 123, and a receiving surface 124.

[0027] The top surface 121 is a surface of the second die 12 that is disposed on the side where the third die 13 is pressed. The bottom surface 122 is disposed on a side opposite to the top surface 121. The bottom surface 122 is disposed substantially parallel to the top surface 121. In an example of this embodiment, the top surface 121 and the bottom surface 122 have a substantially rectangular shape. The side surface 123 connects the top surface 121 and the bottom surface 122 on the side opposite to the first die 11. The receiving surface 124 is disposed on a side opposite to the side surface 123, that is, on the first die 11 side. The receiving surface 124 is connected to the top surface 121. Corners between the side surface 123 and the top surface 121 and / or the bottom surface 122 may be subjected to R chamfering. A corner between the side surface 123 and a surface adjacent to the side surface 123 other than the top surface 121 and the bottom surface 122 may also be subjected to R chamfering. Similarly, a corner between the receiving surface 124 and the top surface 121 may be subjected to R chamfering. A corner between the receiving surface 124 and a surface adjacent to the receiving surface 124 other than the top surface 121 may also be subjected to R chamfering.

[0028] The third die 13 includes abutting surfaces 131 and 132.

[0029] The abutting surface 131 is a surface for abutting against the receiving surface 114 of the first die 11. The abutting surface 132 is a surface for abutting against the receiving surface 124 of the second die 12. The abutting surface 132 is disposed on a side opposite to the abutting surface 131.

[0030] Configurations of the dies 11, 12, and 13 will be described in more detail below with reference to FIG. 2. FIG. 2 is a cross-sectional view (longitudinal cross-sectional view) obtained by cutting the dies 11, 12, and 13 along a plane extending along the axial direction and the width direction of the die set 10.

[0031] As described above, the third die 13 is pressed into a space between the first die 11 and the second die 12 to move the first die 11 and the second die 12 away from each other. That is, the third die 13 is a die that functions as a cam driver. Therefore, as shown in FIG. 2, the third die 13 is configured such that the width between the abutting surfaces 131 and 132 decreases from one end side to the other end side in the axial direction. The abutting surfaces 131 and 132 extend toward each other from a base end to a leading end of the third die 13. The abutting surfaces 131 and 132 are typically inclined surfaces that are inclined with respect to the axial direction. The abutting surfaces 131 and 132 are symmetrical with respect to a center axis A of the third die 13.

[0032] The first die 11 and the second die 12 are cam sliders that move as the third die 13 is pressed. Therefore, the distance between the receiving surface 114 of the first die 11 and the receiving surface 124 of the second die 12 decreases from the top surface 111, 121 side toward the bottom surface 112, 112 side in accordance with the width between the abutting surfaces 131 and 132 of the third die 13. The receiving surface 114 of the first die 11 is an inclined surface with substantially the same angle as one abutting surface 131 of the third die 13. The receiving surface 124 of the second die 12 is an inclined surface with substantially the same angle as the other abutting surface 132 of the third die 13. In this embodiment, the receiving surfaces 114 and 124 are symmetrical with respect to the center axis A of the third die 13.

[0033] The side surface 113 of the first die 11 and the side surface 123 of the second die 12 are arranged on both outer sides in the width direction of the die set 10. The distance between the side surface 113 of the first die 11 and the side surface 123 of the second die 12 is larger on the top surface 111, 121 side than on the bottom surface 112, 122 side. The side surface 113 of the first die 11 and the side surface 123 of the second die 12 have shapes symmetrical with respect to the center axis A of the third die 13. Therefore, the side surface 113 of the first die 11 will be mainly described below, and a detailed description of the side surface 123 of the second die 12 will be omitted.

[0034] The side surface 113 of the first die 11 is formed such that a portion on the bottom surface 112 side is positioned inward of a portion on the top surface 111 side in the width direction. In the example of this embodiment, the side surface 113 is an inclined surface with respect to the axial direction, and has a substantially constant gradient. In a longitudinal cross section of the first die 11, x / y > 0 holds true, when x represents a distance in the width direction from an upper end to a lower end of the side surface 113, and y represents a distance in the axial direction from the upper end to the lower end of the side surface 113. It is preferable that x and y are set such that x / y ≥ 0.00050 is satisfied. More preferably, x / y ≥ 0.00075 holds true, and even more preferably, x / y ≥ 0.00100 holds true. Particularly preferably, x / y ≥ 0.00200 holds true.

[0035] The upper end of the side surface 113 is a boundary between the top surface 111 and the side surface 113. When a corner between the top surface 111 and the side surface 113 is chamfered, an intersection Ia of an extension line of the top surface 111 and an extension line of the side surface 113 in a longitudinal cross-sectional view of the first die 11 is defined as the upper end of the side surface 113. On the other hand, the lower end of the side surface 113 is a boundary between the bottom surface 112 and the side surface 113. When a corner between the bottom surface 112 and the side surface 113 is chamfered, an intersection Ib of an extension line of the bottom surface 112 and an extension line of the side surface 113 in a longitudinal cross-sectional view of the first die 11 is defined as the lower end of the side surface 113.[Method for manufacturing metal can]

[0036] Next, a method for manufacturing a metal can using the die set 10 will be described with reference to FIGS. 3A to 3F. Although not particularly limited, a metal can to be manufactured is, for example, a battery cell case. A method for manufacturing a metal can according to this embodiment includes a preparing step and a reshaping step.(Preparing Step)

[0037] Referring to FIG. 3A, a material can 20 is prepared in the preparing step. The material can 20 has a tubular shape having a bottom. The material can 20 includes a peripheral wall 21 and a bottom wall 22.

[0038] The peripheral wall 21 has a tubular shape. The peripheral wall 21 typically has a polygonal tubular shape. In an example of this embodiment, the peripheral wall 21 has a rectangular tubular shape. More specifically, the peripheral wall 21 has a flat rectangular tubular shape. The peripheral wall 21 includes side walls 211, 212, 213, and 214. Each of the side walls 211, 212, 213, and 214 has a substantially flat shape. The side wall 211 connects the opposing side walls 213 and 214. The side wall 212 faces the side wall 211, and connects the side walls 213 and 214 on the side opposite to the side wall 211. The bottom wall 22 closes one end in the axial direction of the peripheral wall 21. The material can 20 has an opening 23 at the other end in the axial direction of the peripheral wall 21.

[0039] The material can 20 is formed from a metal sheet. The material can 20 is typically formed by deep drawing a metal sheet. The material can 20 may also be formed by, for example, performing deep drawing on a metal sheet multiple times (multi-stage drawing).

[0040] The metal sheet for forming the material can 20 may be a steel sheet. The material of the steel sheet is preferably carbon steel, but may also be alloy steel, stainless steel, or the like. The steel sheet may be a plated steel sheet or an unplated steel sheet. Alternatively, the material can 20 may be formed from a metal sheet made of, for example, aluminum, titanium, or copper, or an alloy thereof. The material of the metal sheet may be a Ni-based alloy, an Al alloy, a Ti alloy, or the like. The material of the material can 20 is not particularly limited as long as the material can 20 is formed from a metal sheet. However, when a metal can to be manufactured is a battery cell case, the material can 20 is preferably formed from a plated steel sheet, a stainless steel sheet, or an Al alloy sheet.

[0041] There is no particular limitation on the sheet thickness of the material can 20. The sheet thickness of the material can 20 can be selected as appropriate depending on, for example, the use or the like of the metal can to be manufactured. When the material can is a battery cell case, the material can 20 has a sheet thickness of, for example, 0.1 mm or more and 3.0 mm or less. The sheet thickness of the material can 20 does not necessarily have to be uniform throughout. For example, the peripheral wall 21 and the bottom wall 22 may have different sheet thicknesses.(Reshaping Step)

[0042] In the reshaping step, a metal can is obtained by reshaping the material can 20 using the die set 10.

[0043] Referring to FIG. 3B, in the reshaping step, first, the first die 11 and the second die 12 of the die set 10 are disposed in the material can 20. The first die 11 is disposed in the material can 20 such that the side surface 113 faces the side wall 211 of the material can 20. The second die 12 is disposed in the material can 20 such that the side surface 123 faces the side wall 212 of the material can 20. The side surfaces 113 and 123 extend from the bottom wall 22 of the material can 20 to at least the opening 23. The side surfaces 113 and 123 may partially protrude outward from the opening 23 of the material can 20.

[0044] Before reshaping, the side walls 211 and 212 are inclined toward the inner side of the material can 20 due to springback when the material can 20 is formed. More specifically, in a longitudinal cross-sectional view of the material can 20, the side walls 211 and 212 are inclined with respect to the axial direction of the die set 10 and the material can 20 such that an end on the opening 23 side of the material can 20 is disposed inward of the end on the bottom wall 22 side. On the other hand, the side surface 113 of the first die 11 and the side surface 123 of the second die 12 are each formed such that a portion on the opening 23 side is positioned outward of a portion on the bottom wall 22 side in the width direction. Therefore, before the start of reshaping, the distance in the width direction between one side wall 211 of the material can 20 and the side surface 113 of the first die 11 is smaller on the opening 23 side of the material can 20 and larger on the bottom wall 22 side. Similarly, before the start of reshaping, the distance in the width direction between the other side wall 212 of the material can 20 and the side surface 123 of the second die 12 is smaller on the opening 23 side of the material can 20 and larger on the bottom wall 22 side. At the start of the reshaping step, the side surface 113 of the first die 11 and the side surface 123 of the second die 12 may be in contact with the side walls 211 and 212 of the material can 20 on the opening 23 side, but are not in contact with them on the bottom wall 22 side.

[0045] Next, the third die 13 is pressed in the axial direction from the opening 23 side into the space between the first die 11 and the second die 12 that are disposed inside the material can 20 to move the first die 11 and the second die 12 away from each other. When the third die 13 is pressed into the space between the first die 11 and the second die 12, the abutting surfaces 131 and 132 of the third die 13 respectively abut against the receiving surface 114 of the first die 11 and the receiving surface 124 of the second die 12, and move the first die 11 and the second die 12 in opposite directions while the abutting surfaces 131 and 132 slide over the receiving surfaces 114 and 124. The first die 11 moves toward one side wall 211 of the material can 20 as the third die 13 is pressed. The second die 12 moves toward the other side wall 212 of the material can 20 as the third die 13 is pressed. Although not shown, the die set 10 may be provided with a sliding mechanism for smoothly moving the first die 11 and the second die 12.

[0046] Referring to FIG. 3C, by bringing the side surface 113 of the first die 11 and the side surface 123 of the second die 12 into contact with the side walls 211 and 212 of the material can 20 while moving the first die 11 and the second die 12 away from each other by pressing the third die 13, the width between the side walls 211 and 212 is increased. The side surface 113 of the first die 11 and the side surface 123 of the second die 12 push and widen the material can 20 in the width direction while the side surfaces 113 and 123 are in contact with the side walls 211 and 212 in order from the opening 23 side toward the bottom wall 22 side.

[0047] Referring to FIG. 3D, when the third die 13 is pressed into the space between the first die 11 and the second die 12 by a predetermined stroke amount, the third die 13 is stopped, and movements of the first die 11 and the second die 12 are also stopped. At this time, due to contact with the first die 11 and the second die 12, the side walls 211 and 212 of the material can 20 are in a state in which the end on the opening 23 side of the material can 20 is positioned on the outer side of the end on the bottom wall 22 side. In the example of this embodiment, the side walls 211 and 212 are inclined toward the outer side of the material can 20 by the first die 11 and the second die 12. More specifically, the side surface 113 of the first die 11 and the side surface 123 of the second die 12 are respectively in contact with the side walls 211 and 212 entirely, and thus the side walls 211 and 212 are inclined along the side surfaces 113 and 123 relative to the axial direction of the material can 20.

[0048] Referring to FIG. 3E, the dies 11, 12, and 13 are then removed from the material can 20. At this time, springback occurs in the side walls 211 and 212 of the material can 20. As indicated by arrows in FIG. 3E, due to springback, the side walls 211 and 212 are restored from the state in which they are inclined toward the outer side of the material can 20.

[0049] As shown in FIG. 3F, a tubular metal can 30 having a bottom is produced through such a reshaping step.[Effects]

[0050] For example, if a side surface 911 of a first die 91 and a side surface 921 of a second die 92 are parallel to the axial direction of the material can 20 as in a die set 90 shown in FIGS. 4A and 4B, when the first die 91 and the second die 92 are moved away from each other by pressing a third die 93, the entire side walls 211 and 212 of the material can 20 are uniformly deformed by the side surface 911 of the first die 91 and the side surface 921 of the second die 92. When the first die 91 and the second die 92 stop moving, the side walls 211 and 212 are parallel to the axial direction of the material can 20 along the side surfaces 911 and 921. When the first die 91 and the second die 92 are removed from the inside of the material can 20 as shown in FIG. 4C, the side walls 211 and 212 are inclined toward the inner side of the material can 20 due to springback. As a result, in the metal can 30 obtained by reshaping the material can 20, a difference in dimension occurs between the opening 23 side and the bottom wall 22 side. More specifically, the width between the side walls 211 and 212 on the opening 23 side is smaller than that on the bottom wall 22 side.

[0051] In contrast, in the die set 10 according to this embodiment, the side surface 113 of the first die 11 and the side surface 123 of the second die 12 are each formed such that a portion on the opening 23 side is positioned outward of a portion on the bottom wall 22 side in the direction in which the dies 11 and 12 move away from each other. Therefore, the side surfaces 113 and 123 first come into contact with the side walls 211 and 212 of the material can 20 on the opening 23 side, and preferentially widen the width between the side walls 211 and 212 on the opening 23 side. The side walls 211 and 212 are inclined toward the outer side of the material can 20 by the side surface 113 of the first die 11 and the side surface 123 of the second die 12. As a result, when the first die 11 and the second die 12 are removed from the inside of the material can 20, the side walls 211 and 212 are less likely to be inclined toward the inner side of the material can 20 even when springback occurs in the side walls 211 and 212. That is, the side walls 211 and 212 are likely to be parallel or nearly parallel to the axial direction of the material can 20. Therefore, in the metal can 30 obtained by reshaping the material can 20, a difference in dimension between the opening 23 side and the bottom wall 22 side can be reduced.

[0052] In this embodiment, when the material can 20 is reshaped using the die set 10 in this manner, the side walls 211 and 212 are deformed in anticipation of springback. As a result, it is possible to improve the dimensional accuracy of the metal can 30 obtained from the material can 20.

[0053] In this embodiment, in the step of reshaping the material can 20, the peripheral wall 21 is pushed and widened in the width direction by the first die 11 and the second die 12. This makes it possible to alleviate residual stress in the peripheral wall 21 when the material can 20 is formed by, for example, deep drawing, and to reduce canning of the peripheral wall 21 occurring when the material can 20 is formed.

[0054] For each of the side surface 113 of the first die 11 and the side surface 123 of the second die 12, x / y ≥ 0.00050 preferably holds true, when x represents the distance in the width direction from the end (upper end) on the opening 23 side of the material can 20 to the end (lower end) on the bottom wall 22 side, and y represents the distance in the axial direction from the upper end to the lower end. This makes it possible to further reduce the dimensional difference of the metal can 30 after the reshaping step between the opening 23 side and the bottom wall 22 side, thereby further improving the dimensional accuracy.

[0055] Regarding the inner dimensions of the material can 20 before reshaping, x ≤ W / 2 and y ≥ H hold true, when W represents the maximum length between the side walls 211 and 212 and H represents a length from the bottom wall 22 to the opening 23 in the axial direction. Therefore, the upper limit of x / y is W / 2H. It is sufficient that x / y is W / 2H or less, and for example, x / y ≤ W / 4H may hold true, and preferably x / y ≤ 0.02000 may hold true.

[0056] The metal can 30 manufactured using the manufacturing method according to this embodiment can be used, for example, as a battery cell case. When the metal can 30 is a battery cell case, the material can 20 before reshaping is preferably formed from a steel sheet, in particular, a plated steel sheet or a stainless steel sheet. In general, an aluminum alloy is used as the material for battery cell cases of lithium secondary batteries or the like. By using a steel with a higher strength as the material for the material can 20 and the metal can 30 obtained from the material can 20, it is possible to make the metal can 30 used as a battery cell case smaller and thinner, compared to an aluminum alloy, thereby improving the space efficiency of the battery.<Second Embodiment>

[0057] FIGS. 5 and 6 are schematic longitudinal cross-sectional views showing a die set 10A according to a second embodiment. As shown in FIGS. 5 and 6, the die set 10A according to this embodiment differs from the die set 10 according to the first embodiment in that the die set 10A further includes a first pad 14 and a second pad 15.

[0058] Referring to FIG. 5, in the step of reshaping the material can 20, the first die 11 and the second die 12 are disposed inside the material can 20, whereas the first pad 14 and the second pad 15 are disposed outside the material can 20. The first pad 14 is provided in the die set 10A in correspondence with the first die 11. The second pad 15 is provided in the die set 10A in correspondence with the second die 12.

[0059] The first pad 14 includes a pressing surface 141. The pressing surface 141 is a surface corresponding to the side surface 113 of the first die 11. The pressing surface 141 is configured to clamp the side wall 211 of the material can 20 together with the side surface 113 of the first die 11. That is, at least a portion of the pressing surface 141 has a shape corresponding to the side surface 113 of the first die 11. In an example of this embodiment, substantially the entire pressing surface 141 has a shape corresponding to the side surface 113 of the first die 11. Specifically, like the side surface 113 of the first die 11, the pressing surface 141 is an inclined surface that is inclined entirely with respect to the axial direction of the die set 10A.

[0060] The second pad 15 includes a pressing surface 151. The pressing surface 151 is a surface corresponding to the side surface 123 of the second die 12. The pressing surface 151 is configured to clamp the side wall 212 of the material can 20 together with the side surface 123 of the second die 12. That is, at least a portion of the pressing surface 151 has a shape corresponding to the side surface 123 of the second die 12. In an example of this embodiment, substantially the entire pressing surface 151 has a shape corresponding to the side surface 123 of the second die 12. Specifically, like the side surface 123 of the second die 12, the pressing surface 151 is an inclined surface that is inclined entirely with respect to the axial direction of the die set 10A.

[0061] Referring to FIG. 6, in the step of reshaping the material can 20, a region of the side wall 211 of the material can 20 that comes into contact with the first die 11 is pressed by the first pad 14 from the outer side of the material can 20. Similarly, in the step of reshaping the material can 20, a region of the side wall 212 of the material can 20 that comes into contact with the second die 12 is pressed by the second pad 15 from the outer side of the material can 20. More specifically, when the first die 11 and the second die 12 are moved away from each other by pressing the third die 13, and the side walls 211 and 212 are pushed apart, the side wall 211 is clamped between the side surface 113 of the first die 11 and the pressing surface 141 of the first pad 14, and the side wall 212 is clamped between the side surface 123 of the second die 12 and the pressing surface 151 of the second pad 15.

[0062] In this embodiment, substantially the entire side wall 211 is pressed from the inside and the outside of the material can 20 by the first die 11 and the first pad 14, and substantially the entire side wall 212 is pressed from the inside and the outside of the material can 20 by the second die 12 and the second pad 15. The first pad 14 may move in the width direction together with the first die 11 while pressing the side wall 211 until the first die 11 stops. Similarly, the second pad 15 may move in the width direction together with the second die 12 while pressing the side wall 212 until the second die 12 stops.

[0063] In this embodiment, the first die 11 and the second die 12 are disposed on the inner side of the material can 20, and the first pad 14 and the second pad 15 are provided on the outer side of the material can 20. Therefore, the width between the side walls 211 and 212 can be increased in a state in which the side walls 211 and 212 are clamped from the inside and the outside of the material can 20. As a result, the shape accuracy of the side walls 211 and 212 can be easily ensured.<Third Embodiment>

[0064] FIGS. 7 and 8 are schematic longitudinal cross-sectional views showing a die set 10B according to a third embodiment. As shown in FIGS. 7 and 8, the die set 10B according to this embodiment differs from the die set 10 according to the first embodiment in that the die set 10B further includes a support 16.

[0065] Referring to FIG. 7, the support 16 is disposed in the material can 20 in the step of reshaping the material can 20. The support 16 is disposed between the first die 11 and the second die 12. The support 16 is disposed in the material can 20 in contact with the bottom wall 22 of the material can 20. The bottom wall 22 is supported by the support 16 from the inner side of the material can 20.

[0066] The support 16 may be, for example, a rigid body made of metal. In this case, the support 16 may be connected to the third die 13 via a connecting member 17. The connecting member 17 is a component capable of extending and retracting in the pressing direction (axial direction) of the third die 13. The connecting member 17 may be, for example, a spring, a hydraulic cylinder, or the like. As shown in FIG. 8, when the third die 13 is pressed into the space between the first die 11 and the second die, the connecting member 17 is compressed by the third die 13. The support 16 can more reliably support the bottom wall 22 due to the support 16 being biased by the connecting member 17 toward to the bottom wall 22.

[0067] As shown in FIGS. 9 and 10, the support 16 may be an elastic body made of resin or the like. In this case, when the third die 13 is pressed into the space between the first die 11 and the second die 12, the support 16 is compressed and deformed by the third die 13 in the axial direction. The support 16 can more reliably support the bottom wall 22 due to the load being applied from the third die 13.

[0068] In this embodiment, when the material can 20 is reshaped, a portion of the bottom wall 22 between the first die 11 and the second die 12 is supported by the support 16 from the inside of the material can 20. In this case, in the step of reshaping the material can 20, partial deformation of the bottom wall 22, such as bulging of the bottom wall 22 toward the inner side of the material can 20, can be suppressed.

[0069] Although not shown, the die set 10B according to this embodiment may further include a first pad 14 and a second pad 15 (FIGS. 5 and 6) as in the die set 10A according to the second embodiment.<Fourth Embodiment>

[0070] FIG. 11 is a schematic longitudinal cross-sectional view showing a die set 10C according to a fourth embodiment. As shown in FIG. 11, the die set 10C according to this embodiment differs from the die set 10 according to the first embodiment in that the shapes of the side surface 113 of the first die 11 and the side surface 123 of the second die 12.

[0071] In this embodiment, in a longitudinal cross-sectional view of the die set 10C, the side surface 113 of the first die 11 and the side surface 123 of the second die 12 each have curved shape. The side surfaces 113 and 123 have, for example, a curved shape that protrudes outward from the material can 20. However, as described in the first embodiment, the side surfaces 113 and 123 are formed such that the distance between the side surfaces 113 and 123 is larger on the top surface 111, 121 side than on the bottom surface 112, 122 side. Thus, when a metal can is manufactured using the die set 10C according to this embodiment, the effects described in the first embodiment can also be achieved.

[0072] In this embodiment, regarding each of the side surface 113 of the first die 11 and the side surfaces 123 of the second die 12, when x represents the distance in the width direction from the upper end to the lower end, and y represents the distance in the axial direction from the upper end to the lower end, the ratio between x and y can be set in the same manner as in the first embodiment. The upper end of the side surface 113 is an intersection Ia between an extension line of the top surface 111 and an extension line of the side surface 113 in a longitudinal cross-sectional view of the first die 11. The lower end of the side surface 113 is an intersection Ib between an extension line of the bottom surface 112 and an extension line of the side surface 113 in a longitudinal cross-sectional view of the first die 11. The upper end and the lower end of the side surface 123 of the second die 12 can be defined in the same manner as the upper end and the lower end of the side surface 113 of the first die 11.

[0073] Although not shown, the die set 10C according to this embodiment may further include a first pad 14 and a second pad 15 (FIGS. 5 and 6) as in the die set 10A according to the second embodiment. The pressing surface 141 of the first pad 14 and the pressing surface 151 of the second pad 15 (FIGS. 5 and 6) have shapes corresponding to regions of the side surface 113 of the first die 11 and the side surface 123 of the second die 12 that come into contact with the side walls 211 and 212 of the material can 20 (FIGS. 3A to 3E). When the side surface 113 of the first die 11 and the side surface 123 of the second die 12 have a curved shape as in this embodiment, the pressing surfaces 141 and 151 also have a curved shape.

[0074] The die set 10C according to this embodiment may include a support 16 (FIGS. 7 to 10) in addition to or instead of the first pad 14 and the second pad 15, as in the die set 10B according to the third embodiment.

[0075] Although embodiments according to the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure.

[0076] In the above embodiments, one example of the shape of the third die 13 is presented. However, the shape of the third die 13 is not limited to the example in the above embodiments. In the above embodiments, the third die 13 has a trapezoidal shape in a longitudinal cross sectional view or a front view. However, for example, as shown in FIG. 12, the third die 13 may have a triangular shape in a longitudinal cross-sectional view or a front view. Similarly, the first die 11 and the second die 12 are not limited to the examples in the above embodiments, and may have various shapes. For example, in the first die 11 and the second die 12, portions of their side surfaces disposed on the third die 13 side may be the inclined receiving surfaces 114 and 124 as in the above embodiments, or substantially the entire side surfaces disposed on the third die 13 side may be the inclined receiving surfaces 114 and 124 as shown in FIG. 13.

[0077] In each of the above embodiments, the side surface 113 of the first die 11 and the side surface 123 of the second die 12 are entirely inclined or curved surfaces. However, the shapes of the side surfaces 113 and 123 are not limited to the examples in the above embodiments. The side surfaces 113 and 123 may also be formed by a combination of two or more inclined surfaces, a combination of two or more curved surfaces, or a combination of one or more inclined surfaces and one or more curved surfaces. It is sufficient that, when disposed in the material can 20, the side surfaces 113 and 123 are formed such that a portion on the opening 23 side is positioned outward of a portion on the bottom wall 22 side in the width direction. In other words, it is sufficient that the side surfaces 113 and 123 are configured to preferentially push and widen regions of the side walls 211 and 212 on the opening 23 side in the step of reshaping the material can 20.

[0078] In each of the above embodiments, an example has been described in which, in the step of reshaping the material can 20, the side surface 113 of the first die 11 comes into contact with the side wall 211 of the material can 20 over substantially the entire surface, and the side surface 123 of the second die 12 comes into contact with the side wall 212 of the material can 20 over substantially the entire surface. However, the side surface 113 of the first die 11 and the side surface 123 of the second die 12 do not necessarily need to come into contact with the side walls 211 and 212 over the entire surface. The side surface 113 of the first die 11 and the side surface 123 of the second die 12 may also come into contact with only the regions of the side walls 211 and 212 on the opening 23 side. Even in this case, the regions of the side walls 211 and 212 on the opening 23 side can be pushed and widened toward the outer side of the material can 20 relative to a region on the bottom wall 22 side.

[0079] Even when the side surface 113 of the first die 11 and the side surface 123 of the second die 12 come into contact with only the regions of the side walls 211 and 212 on the opening 23 side, the first pad 14 and the second pad 15 can be used in the step of reshaping the material can 20. In this case, the first pad 14 and the second pad 15 also come into contact with only the regions of the side walls 211 and 212 on the opening 23 side from the outer side of the material can 20. It is preferable that the first pad 14 and the second pad 15 do not come into contact with the regions of the side walls 211 and 212 of the material can 20 that do not come into contact with the side surface 113 of the first die 11 and the side surface 123 of the second die 12.

[0080] In each of the above embodiments, in a longitudinal cross-sectional view or a front view of the first die 11 and the second die 12, the side surface 113 of the first die 11 has a shape symmetrical to the side surface 123 of the second die 12. The side surface 113 of the first die 11 and the side surface 123 of the second die 12 preferably have symmetrical shapes, but slight differences in, for example, the inclination angle or the like are permissible. It is sufficient that the side surface 113 of the die 11 and the side surface 123 of the second die 12 can push and widen the side walls 211 and 212 of the material can 20 in the width direction to substantially or approximately the same extent.

[0081] Similarly, it is preferable that, although the receiving surface 114 of the first die 11 and the receiving surface 124 of the second die 12 also have symmetrical shapes in a longitudinal cross-sectional view or a front view of the first die 11 and the second die 12, they may also have slightly asymmetrical shapes. The abutting surfaces 131 and 132 of the third die 13 are shaped to correspond respectively to the receiving surface 114 of the first die 11 and the receiving surface 124 of the second die 12.

[0082] In each of the above embodiments, the third die 13 is pressed into the space between the first die 11 and the second die 12 at a center position in the width direction of the material can 20. However, the third die 13 may also be pressed into the space between the first die 11 and the second die 12 at a position shifted from the center in the width direction of the material can 20 toward the side wall 211 or the side wall 212. As long as the stroke amount of the first die 11 and the stroke amount of the second die 12 when the third die 13 is pressed are substantially the same, there is no particular limitation on the position where the third die 13 is pressed. The receiving surfaces 114 of the first die 11 and the receiving surface 124 of the second die 12 are disposed at positions corresponding to the third die 13.

[0083] The material can 20 has a rectangular tubular shape having a bottom in the above embodiments. However, the material can 20 may also have, for example, other polygonal tubular shapes (with a bottom), such as a hexagonal tubular shape. The shape of the material can 20 may be changed depending on, for example, the use or the like of the metal can 30 to be manufactured. The size of the material can 20 can also be changed as appropriate depending on, for example, the use or the like of the metal can 30. The material can 20 may be any can including two side walls facing each other.

[0084] In the above embodiments, in the step of reshaping the material can 20, the width between the side walls 211 and 212 is increased by the first die 11 and the second die 12. However, in the step of reshaping the material can 20, the width between the other side walls 213 and 214 can also be increased using the first die 11 and the second die 12. The sizes and the like of the first die 11 and the second die 12 can be changed as appropriate depending on the pair of side walls to be widened.EXAMPLES

[0085] The present disclosure will be described in more detail below with reference to examples. However, the present disclosure is not limited to the following examples.

[0086] In order to confirm the effects of the present disclosure, an analysis using the finite element method (FEM analysis) was carried out on the reshaping of the material can using a die set (without pads) having the same shape as the die set 10 described in the first embodiment. As a comparative example, a similar analysis was performed on the reshaping of the material can using a die set (without pads) having the same shape as the die set 90 shown in FIGS. 4A to 4C. Basic conditions for the analysis are as follows: Inner dimensions of material can (before springback) Bottom wall: Width 147.72 mm × Depth 26.25 mm Opening: Width 147.67 mm × Depth 26.26 mm Height: 108 mm Material: IF steel Sheet thickness: 0.3 mm

[0087] In this analysis, the influence of the degree of inclination of the side surfaces of the first die and the second die, that is, x / y, on the dimensional difference between the opening side and the bottom wall side was studied. The dimensional difference between the opening side and the bottom wall side is the difference between the distance between the side walls measured at a position of 91 mm from the bottom wall in the axial direction and the distance between the side walls measured at a position of 10 mm from the bottom wall in the axial direction, for the metal can obtained by reshaping the material can. The side wall here refers to the side wall widened by the first die and the second die. The results of this analysis are shown in FIG. 14.

[0088] As shown in FIG. 14, the test example in which the side surfaces of the first die and the second die had an inclination, i.e., x / y > 0, had a reduced dimensional difference between the opening side and the bottom wall side compared to the comparative example in which the side surfaces of the first die and the second die had no inclination, i.e., x / y = 0. When x / y ≥ 0.00050 holds true, the dimensional difference between the opening side and the bottom wall side was reduced to 90% or less of that in the comparative example. When x / y ≥ 0.00075 holds true, the dimensional difference between the opening side and the bottom wall side was reduced to 80% or less of that in the comparative example. When x / y ≥ 0.00100 holds true, the dimensional difference between the opening side and the bottom wall side was reduced to 70% or less of that in the comparative example. When x / y ≥ 0.00200 holds true, the dimensional difference between the opening side and the bottom wall side was reduced to 50% or less of that in the comparative example.

[0089] It was confirmed through this analysis that the dimensional accuracy of the reshaped metal can was improved by providing an inclination to the side surfaces of the first die and the second die (x / y > 0). In particular, it was confirmed that when x / y ≥ 0.00050 held true, the dimensional accuracy of the metal can was clearly improved compared to the case where x / y = 0 held true. In order to further improve the dimensional accuracy of the metal can, x / y ≥ 0.00075 preferably holds true, and x / y ≥ 0.00100 more preferably holds true. Particularly preferably, x / y ≥ 0.00200 holds true.REFERENCE SIGNS LIST

[0090] 10, 10A, 10B, 10C:Die set 11:First die 111:Top surface (first top surface) 112:Bottom surface (first bottom surface) 113:Side surface (first side surface) 114:Receiving surface (first receiving surface) 12:Second die 121:Top surface (second top surface) 122:Bottom surface (second bottom surface) 123:Side surface (second side surface) 124:Receiving surface (second receiving surface) 13:Third die 131:Abutting surface (first abutting surface) 132:Abutting surface (second abutting surface) 14:First pad 15:Second pad 16:Support 20:Material can 21:Peripheral wall 211:Side wall (first side wall) 212:Side surface (second side wall) 22:Bottom wall 23:Opening 30:Metal can

Claims

1. A method for manufacturing a metal can, comprising: a step of preparing a material can including: a tubular peripheral wall including a first side wall and a second side wall facing the first side wall; and a bottom wall that closes one end of the peripheral wall in an axial direction of the peripheral wall, the material can having an opening at the other end of the peripheral wall in the axial direction; and a step of obtaining a metal can by reshaping the material can using a die set including a first die, a second die, and a third die, wherein in the step of reshaping the material can, the third die is pressed in the axial direction from the opening side into a space between the first die and the second die that are disposed inside the material can to move the first die and the second die away from each other, and a side surface of the first die and a side surface of the second die are brought into contact with the first side wall and the second side wall, respectively, to increase a width between the first side wall and the second side wall, and the side surfaces are each formed such that a portion on the opening side is positioned outward of a portion on the bottom wall side in a direction in which the first die and the second die move away from each other.

2. The manufacturing method according to claim 1, wherein x / y ≥ 0.00050 holds true where, for each of the side surfaces, x represents a distance from an end on the opening side to an end on the bottom wall side in the direction in which the first die and the second die move away from each other, and y represents a length from the end on the opening side to the end on the bottom wall side in a direction in which the third die is pressed.

3. The manufacturing method according to claim 1, wherein in the step of reshaping the material can, a region of the first side wall that comes into contact with the first die is pressed by a first pad from an outer side of the material can, and a region of the second side wall that comes into contact with the second die is pressed by a second pad from the outer side of the material can.

4. The manufacturing method according to claim 1, wherein in the step of reshaping the material can, the bottom wall is supported from an inner side of the material can by a support disposed between the first die and the second die.

5. A die set for use in manufacturing of a metal can, comprising: a first die including a first top surface, a first bottom surface disposed on a side opposite to the first top surface, a first side surface that connects the first top surface and the first bottom surface, and a first receiving surface disposed on a side opposite to the first side surface; a second die that is disposed side by side with the first die and includes a second top surface, a second bottom surface disposed on a side opposite to the second top surface, a second side surface that connects, on a side opposite to the first die, the second top surface and the second bottom surface, and a second receiving surface disposed on a side opposite to the second side surface; and a third die that includes a first abutting surface for abutting against the first receiving surface and a second abutting surface for abutting against the second receiving surface, the second abutting surface being disposed on a side opposite to the first abutting surface, the third die being configured such that a width between the first abutting surface and the second abutting surface decreases from one end side to another end side in an axial direction, wherein a distance between the first receiving surface and the second receiving surface decreases from the first top surface and second top surface side toward the first bottom surface and the second bottom surface side in accordance with the width between the first abutting surface and the second abutting surface, and a distance between the first side surface and the second side surface is larger on the first top surface and second top surface side than on the first bottom surface and second bottom surface side.

Images