Manufacturing method of metal can and die set

Abstract

To provide a manufacturing method of a metal can which can obtain metal cans having a small curvature radius of each corner part between side walls while inhibiting reduction of a plate thickness.SOLUTION: A manufacturing method includes: a step in which an untreated can (20) is prepared; and a step in which the untreated can (20) is corrected by using a die set (10, 10A) to obtain a metal can (30). The untreated can (20) includes: a pair of first side walls (21); corner parts (23); and a pair of second side walls (22). The die set (10, 10A) includes: a pair of first dies (11); a pair of second dies (12); and a core (13, 13A). In the step in which the untreated can (20) is corrected, in a state where the second side walls (22) are supported by the second dies (12) and the core (13, 13A), each first die (11) is moved relative to the untreated can (20) from an opening (25) side to a bottom plate (24) side while the first die (11) presses the first side wall (21) and the corner parts (23) against the core (13, 13A).SELECTED DRAWING: Figure 2D

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a metal can and a mold set.

Background Art

[0002] In recent years, the spread of electric vehicles including battery electric vehicles (BEVs) and hybrid electric vehicles (HEVs) has been promoted. In electric vehicles, for example, non-aqueous electrolyte secondary batteries are used. In electric vehicles, in general, a plurality of batteries connected to each other are mounted in order to ensure high output and high capacity.

[0003] In electric vehicles and the like, an increase in the size and energy density of batteries is required. By increasing the size of the battery, the number of batteries (number of mounted cells) mounted on an electric vehicle or the like can be reduced. As a result, since the area of the battery case per unit area in the battery mounting space is reduced, an increase in energy density can be expected. For example, when a square cylindrical metal can is used as the battery case, the smaller the radius of curvature of the corner portion between the side walls of the metal can, the more closely the batteries can be arranged, and the loss of the battery mounting space can be reduced.

[0004] A square cylindrical metal can is generally manufactured by deep drawing of a metal plate. For example, as described in Patent Document 1, when manufacturing a metal can, multi-stage deep drawing is performed on a metal plate as a material. In Patent Document 1, by deep drawing, a first intermediate cup body having a substantially elliptical cross section is formed from the metal plate. Next, a second intermediate cup body is formed from the first intermediate cup body by multi-stage redrawing. The second intermediate cup body has a substantially elliptical cross section in which the ratio of the minor axis to the major axis (minor axis / major axis) is smaller than that of the first intermediate cup body. Thereafter, redrawing and multi-stage ironing are performed on the second intermediate cup body to manufacture a square cylindrical metal can.

[0005] In addition to thinning the side walls of a metal can by ironing during deep drawing, the corner portions between the side walls on the outer surface of the metal can may be reduced in diameter. However, it is difficult to apply ironing to the production of thin-walled metal cans. Specifically, in ironing, the clearance between the dies is set to be smaller than the thickness of the metal sheet which is the material. Then, using these dies, a metal can thinner than the original thickness of the metal sheet is formed. When the thickness of the original metal sheet is small, the load applied to the metal sheet in the thickness direction from the die in ironing becomes large, and deformation or damage of the die may occur. Even when manufacturing a large metal can, a large load is likely to be generated on the die, and it may be difficult to apply ironing. When forming a metal can by deep drawing alone without performing ironing, it is difficult to reduce the diameter of the corner portion between the side walls.

[0006] On the other hand, for example, Patent Document 2 discloses a method of manufacturing a three-dimensional molded product by drawing an aluminum resin composite laminate. In Patent Document 2, a corner portion is pressed from the inside to the outside of the three-dimensional molded product by a pressing jig. Patent Document 2 describes that thereby, the radius of curvature of the corner portion can be reduced to less than the thickness of the aluminum resin composite laminate.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] In Patent Document 2, the diameter of the corner portion is reduced by pressing the corner portion with a pressing jig from the inside to the outside of the three-dimensional molded product. However, in this method, there is a possibility that the plate thickness may decrease at the corner portion. In particular, when the three-dimensional molded product is thin, there is a risk of cracking at the corner portion due to the decrease in plate thickness.

[0009] An object of the present disclosure is to provide a method for manufacturing a metal can that can obtain a metal can having a small radius of curvature at the corner portion between side walls while suppressing a decrease in plate thickness.

Means for Solving the Problems

[0010] The method for manufacturing a metal can according to the present disclosure includes a step of preparing a blank can and a step of using a mold set to correct the blank can to obtain a metal can. The blank can includes a pair of first side walls, a corner portion, a pair of second side walls, and a bottom plate. The pair of first side walls are arranged to face each other. The corner portion is provided on both sides of each of the first side walls. The pair of second side walls are each connected to both of the first side walls via the corner portion. The bottom plate seals one axial end of the peripheral wall formed by the first side wall, the corner portion, and the second side wall. The blank can has an opening at the other axial end of the peripheral wall. The mold set includes a pair of first molds, a pair of second molds, and a core. The pair of first molds are arranged outside the blank can and are provided corresponding to the first side walls respectively. The pair of second molds are arranged outside the blank can and face the second side walls respectively. The core is arranged inside the blank can so as to be in contact with the second side wall and have a gap between each of the first side walls. In the step of correcting the blank can, while supporting the second side wall by the second mold and the core, the first mold is moved relative to the blank can from the opening side to the bottom plate side while pressing the first side wall and the corner portion toward the core side by the first mold.

Advantages of the Invention

[0011] According to the method for manufacturing a metal can according to the present disclosure, it is possible to obtain a metal can having a small radius of curvature at the corner portion between side walls while suppressing a decrease in plate thickness.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 2E

Figure 2F

Figure 2G

Figure 2H

Figure 2I

Figure 3A

Figure 3B

Figure 3C

Figure 4

Figure 5

Figure 6

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0013] The method for manufacturing a metal can according to the embodiment includes a step of preparing a blank can and a step of using a mold set to correct the blank can to obtain a metal can. The blank can includes a pair of first side walls, a corner portion, a pair of second side walls, and a bottom plate. The pair of first side walls are arranged to face each other. The corner portion is provided on both sides of each of the first side walls. The pair of second side walls are each connected to both of the first side walls via the corner portion. The bottom plate seals an axial end of the peripheral wall formed by the first side wall, the corner portion, and the second side wall. The blank can has an opening at the other axial end of the peripheral wall. The mold set includes a pair of first molds, a pair of second molds, and a core. The pair of first molds are arranged outside the blank can and are provided corresponding to the first side walls respectively. The pair of second molds are arranged outside the blank can and face the second side walls respectively. The core is arranged inside the blank can in contact with the second side walls and with a gap formed between each of the core and the first side walls. In the step of correcting the blank can, with the second side walls supported by the second molds and the core, the first molds are moved relative to the blank can from the opening side toward the bottom plate side while pressing the first side walls and the corner portion toward the core side by the first molds (the first configuration).

[0014] In the manufacturing method according to the first configuration, a die set including a pair of first dies, a pair of second dies, and a core is used, and for example, a material can obtained by deep drawing is corrected. When correcting the material can, the core is disposed inside the material can in a state of contacting the second side wall of the material can and creating a gap between each of the first side walls of the material can. In the correction process of the material can, with the second side wall of the material can supported by the second die and the core, the first side wall of the material can and the corner portions provided on both sides of each first side wall are pressed against the core side by the first die. Further, the first die moves relative to the material can from the opening side toward the bottom plate side. As a result, the corner portions of the material can are each crushed by the first die, deformed so as to have corners, and reduced in diameter. Therefore, a metal can having a small radius of curvature of the corner portion between the first side wall and the second side wall can be obtained.

[0015] In the manufacturing method according to the first configuration, when reducing the diameter of the corner portion between the first side wall and the second side wall, the first die is pressed against the material can from the outside, and the first side wall and the corner portion are compressed inside the material can. In this case, an increase in the cross-sectional line length of the first side wall and the corner portion is less likely to occur. Therefore, in the first side wall and the corner portion, a reduction in plate thickness due to correction can be suppressed.

[0016] For example, when a bottomed square tube-shaped material can is formed by deep drawing, in this material can, a reduction in plate thickness is likely to occur on the bottom plate side compared to the opening side. In deep drawing, in particular, the plate thickness decreases at the corner portion between the side wall and the bottom plate. On the other hand, in the manufacturing method according to the first configuration, due to the relative movement of the first die with respect to the material can, the first side wall and the corner portion are gradually crushed from the opening side toward the bottom plate side. Therefore, the material of the first side wall can be moved to the bottom plate side, and the degree of reduction in plate thickness on the bottom plate side can be alleviated.

[0017] In the step of correcting the material can, the first die may approach the core so as to press the first side wall and the corner portion against the core side at the opening side, and move relative to the material can toward the bottom plate side (second configuration).

[0018] In the step of correcting the material can, the first mold may contact the open end of the peripheral wall in a state where the distance between the first molds is smaller than the distance between the first side walls and move toward the bottom plate side relative to the material can (third configuration).

[0019] In the manufacturing method according to any one of the first to third configurations, when the radius of curvature of the corner portion before correction is R0 (mm), the radius of curvature of the corner portion after correction is R1 (mm), and the displacement amount of the first side wall due to correction is ΔX (mm), R0, R1, and ΔX may satisfy the following formula (fourth configuration). ΔX≦(R0 - 0.5708R0) - (R1 - 0.5708R1) + 2.0

[0020] According to the fourth configuration, the line length of the portion of the material can that is deformed by the first mold, that is, the first side wall and the corner portions provided on both sides thereof, does not substantially change before and after correction. In this case, not only can the reduction in plate thickness due to correction be suppressed, but also the occurrence of meat excess due to correction and wrinkles resulting therefrom can be suppressed.

[0021] In the manufacturing method according to any one of the first to fourth configurations, the corner portion before correction may have a radius of curvature of 20.0 mm or less (fifth configuration).

[0022] In the manufacturing method according to any one of the first to fifth configurations, the first side wall may be formed of a steel plate. In this case, the first side wall can have a plate thickness of 0.1 mm or more and 2.0 mm or less (sixth configuration).

[0023] Since the steel sheet is of high strength, when ironing is applied to a stock can formed of the steel sheet, the load on the mold is large, and the mold is likely to be deformed or damaged. Therefore, when the stock can is formed of a steel sheet, it is difficult to apply ironing to the stock can. When the steel sheet is thin, it becomes more difficult to apply ironing, and it is difficult to reduce the diameter of the corner portion by ironing. However, in the manufacturing method according to the embodiment, the diameter of the corner portion between the side walls of the stock can can be reduced without applying ironing. That is, the first side wall and the corner portion of the stock can are pressed against the core side by the first mold, so that the corner portion is deformed and its radius of curvature becomes smaller. Therefore, as in the sixth configuration, even if the first side wall continuous with the corner portion is formed of a steel sheet and is as thin as 0.1 mm or more and 2.0 mm or less, it is possible to easily reduce the diameter of the corner portion.

[0024] The mold set according to the embodiment is for correcting a stock can. The stock can includes a pair of first side walls, a corner portion, a pair of second side walls, and a bottom plate. The pair of first side walls are arranged to face each other. The corner portion is provided on both sides of each of the first side walls. The pair of second side walls are each connected to both of the first side walls via the corner portion. The bottom plate seals one axial end of the peripheral wall formed by the first side wall, the corner portion, and the second side wall. The stock can has an opening at the other axial end of the peripheral wall. The mold set includes a core, a pair of first molds, and a pair of second molds. The core includes a pair of first side surfaces and a pair of second side surfaces. The pair of second side surfaces connect the first side surfaces to each other. The core is arranged inside the stock can when the mold set is in use. The pair of first molds respectively correspond to the first side surfaces. The pair of first molds are arranged outside the stock can when the mold set is in use. The pair of second molds respectively correspond to the second side surfaces. The pair of second molds are arranged outside the stock can when the mold set is in use. The first mold is configured to move relative to the stock can from the opening side to the bottom plate side while crushing the first side wall and the corner portion of the stock can toward the first side surface side. The second mold is configured to support the second side wall of the stock can together with the second side surface (seventh configuration).

[0025] The manufacturing method of a metal can according to another embodiment includes a step of preparing a blank can and a step of using a mold set to correct the blank can to obtain a metal can. The blank can includes a pair of first side walls, a corner portion, and a pair of second side walls. The pair of first side walls are arranged to face each other. The corner portion is provided on both sides of each of the first side walls. The pair of second side walls are each connected to both of the first side walls via the corner portion. The mold set includes a pair of first molds, a pair of second molds, and a core. The pair of first molds are arranged outside the blank can. The pair of second molds are arranged outside the blank can. The core is arranged inside the blank can so as to contact the second side wall and have a gap between each of the first side walls. In the step of correcting the blank can, with the second side wall supported by the second mold and the core, the first side wall and the corner portion are pressed toward the core side by the first mold.

[0026] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In these drawings, the same or corresponding components are denoted by the same reference numerals, and the same description will not be repeated.

[0027] <First Embodiment> [Configuration of Mold Set] FIG. 1 is a perspective view schematically showing a mold set 10 according to the present embodiment. Referring to FIG. 1, the mold set 10 is used to correct a rectangular tube-shaped blank can 20. The mold set 10 includes a pair of first molds 11, a pair of second molds 12, and a core 13. The first mold 11 and the second mold 12 are arranged outside the blank can 20 when the mold set 10 is used. The core 13 is arranged inside the blank can 20 when the mold set 10 is used.

[0028] The core 13 has, for example, a substantially rectangular parallelepiped shape or a substantially cubic shape. The core 13 includes a pair of first side surfaces 131 and a pair of second side surfaces 132. The core 13 can further include four corner portions 133.

[0029] In the core 13, one first side surface 131 is arranged on the opposite side of the other first side surface 131. Corner portions 133 are continuously provided on both sides of each first side surface 131. One second side surface 132 is arranged on the opposite side of the other second side surface 132. Each of the second side surfaces 132 connects the first side surfaces 131 to each other. More specifically, each of the second side surfaces 132 is connected to both of the first side surfaces 131 via the corner portions 133.

[0030] In this embodiment, the length between the first side surfaces 131 is greater than the length between the second side surfaces 132. However, the length between the first side surfaces 131 may be less than or equal to the length between the second side surfaces 132. Hereinafter, for the sake of convenience of explanation, with respect to the mold set 10 and the material can 20, the direction in which the first side surfaces 131 are arranged may be referred to as the width direction, and the direction in which the second side surfaces 132 are arranged may be referred to as the depth direction. Also, with respect to the mold set 10 and the material can 20, the direction perpendicular to the width direction and the depth direction may be referred to as the height direction.

[0031] In the example shown in FIG. 1, the core 13 further includes a top surface 134 and a bottom surface 135. The top surface 134 is connected to the side surfaces 131, 132 at one end side in the height direction. The bottom surface 135 is connected to the side surfaces 131, 132 at the other end side in the height direction. Chamfering such as R chamfering or C chamfering may be performed at the corners between the top surface 134 and the side surfaces 131, 132. Similarly, chamfering such as R chamfering or C chamfering may be performed at the corners between the bottom surface 135 and the side surfaces 131, 132.

[0032] A pair of first molds 11 are arranged on both sides of the core 13 in the width direction. In the example of FIG. 1, the first molds 11 are arranged with their positions shifted in the height direction with respect to the core 13. The first molds 11 are arranged on the top surface 134 side of the core 13 in the height direction of the mold set 10. Each of the first molds 11 corresponds to the first side surface 131 of the core 13. Each of the first molds 11 includes a pressing surface 111 and a tip surface 112. The pressing surface 111 is provided on the surface on the core 13 side in each of the first molds 11. The tip surface 112 is connected to the pressing surface 111. It is preferable that chamfering such as R chamfering or C chamfering is performed at the corner between the pressing surface 111 and the tip surface 112.

[0033] A pair of second molds 12 are arranged on both sides of the core 13 in the depth direction. Each of the second molds 12 corresponds to the second side surface 132 of the core 13. Each of the second molds 12 includes a support surface 121. The support surface 121 is provided on the surface on the core 13 side in each of the second molds 12.

[0034] [Method for manufacturing a metal can] Next, a method for manufacturing a metal can using the mold set 10 will be described with reference to FIGS. 2A to 2I. Although not particularly limited, the metal can to be manufactured is, for example, a battery case. The method for manufacturing a metal can according to the present embodiment includes a preparation step and a correction step.

[0035] (Preparation step) Referring to FIG. 2A, in the preparation step, a blank can 20 is prepared. The blank can 20 typically has a bottomed rectangular tube shape. The blank can 20 includes a pair of first side walls 21, a pair of second side walls 22, and four corner portions 23. In the example of FIG. 2A, the blank can 20 further includes a bottom plate 24.

[0036] A pair of first side walls 21 are arranged to face each other. Corner portions 23 are provided on both sides of each of the first side walls 21. The corner portions 23 are continuously provided on each of the first side walls 21. A pair of second side walls 22 are arranged to face each other and connect the first side walls 21 to each other. The second side walls 22 are each connected to both of the first side walls 21 via the corner portions 23.

[0037] The side walls 21, 22 each have a substantially flat shape. The side walls 21, 22 have, for example, a substantially or approximately rectangular shape. Each of the corner portions 23 extends along the side walls 21, 22 between the side walls 21, 22. Each of the corner portions 23 can have a substantially arc shape when viewed in a cross section (transverse section) perpendicular to its extending direction. The side walls 21, 22 and the corner portions 23 form a substantially rectangular tube-shaped peripheral wall in the material can 20.

[0038] The bottom plate 24 seals one axial end of the substantially rectangular tube-shaped peripheral wall. The material can 20 has an opening 25 at the other axial end of the peripheral wall.

[0039] The material can 20 is formed of a metal plate. The material can 20 is typically formed by deep drawing of a metal plate. The material can 20 may be formed, for example, by subjecting a metal plate to multiple drawing processes (multi-stage drawing).

[0040] The metal plate forming the material can 20 may be an aluminum alloy plate or a steel plate. The steel plate includes, for example, a stainless steel plate or a plated steel plate. Alternatively, the material can 20 may be formed of a metal plate made of titanium or copper, or an alloy thereof. The material can 20 only needs to be formed of a metal plate, and its material is not particularly limited. However, when the manufactured metal can is a battery case, the material can 20 is preferably formed of a nickel-plated steel plate or a stainless steel plate.

[0041] The thickness of the blank can 20 is not particularly limited. The thickness of the blank can 20 can be appropriately selected according to, for example, the use of the metal can to be manufactured. When the metal can to be manufactured is a battery case, the thickness of the side walls 21, 22 of the blank can 20 is, for example, 0.1 mm or more and 3.0 mm or less. When the metal can to be manufactured is a battery case and the blank can 20 is formed of a steel plate, the thickness of the side walls 21, 22 is, for example, 0.1 mm or more and 2.0 mm or less. The thickness of the bottom plate 24 may be the same as that of the side walls 21, 22 or different from that of the side walls 21, 22.

[0042] (Straightening process) In the straightening process, the die set 10 is used to straighten the blank can 20 to obtain a metal can. FIGS. 2B, 2D, and 2E are diagrams (longitudinal sectional views) showing cross sections of the die set 10 and the blank can 20 in the straightening process cut along the width direction and the height direction. FIGS. 2C and 2F are diagrams (cross-sectional views) showing cross sections of the die set 10 and the blank can 20 in the straightening process cut by a plane perpendicular to the height direction.

[0043] Referring to FIGS. 2B and 2C, when starting the straightening process, the core 13 of the die set 10 is disposed inside the blank can 20. The core 13 is disposed inside the blank can 20 so as to be in contact with the second side wall 22 of the blank can 20 and to form a gap between each of the core 13 and the first side wall 21. Before the start of the straightening process, the second side surfaces 132 of the core 13 are in contact with the inner surfaces of the second side wall 22 of the blank can 20, respectively. The second side surfaces 132 of the core 13 preferably contact the entire or substantially the entire second side wall 22 of the blank can 20.

[0044] On one hand, the first side surfaces 131 of the cores 13 are respectively opposed to the inner surface of the first side walls 21 of the material can 20 with a gap therebetween. That is, when the distance between the first side surfaces 131 of the cores 13 is the width W0 and the distance between the outer surfaces of the first side walls 21 of the material can 20 is the width W1, the width W1 of the material can 20 is larger than the width W0 of the cores 13 even when subtracting the plate thicknesses of both first side walls 21. The first side surfaces 131 of the cores 13 preferably oppose the whole or substantially the whole of the first side walls 21 of the material can 20. The first side surfaces 131 of the cores 13 are arranged, for example, outside the boundary between the second side wall 22 and the corner portion 23 of the material can 20 in the width direction of the mold set 10. However, at the start point of the correction process, the first side surfaces 131 of the cores do not contact the first side walls 21 of the material can 20. The distance (clearance) between the first side surfaces 131 of the cores and the first side walls 21 of the material can 20 may be, for example, 100% or more and 150% or less of the plate thickness of the first side walls 21.

[0045] When the metal can to be manufactured is a battery case, the width W1 of the material can 20 is, for example, 100.0 mm or more and 400.0 mm or less. However, in the material can 20, when the distance between the first side walls 21 is shorter than the distance between the second side walls 22, the width W1 may be 10.0 mm or more and 50.0 mm or less. When the distance between the second side walls 22 is the depth D1, when the distance between the first side walls 21 is shorter than the distance between the second side walls 22, the depth D1 may be 100.0 mm or more and 400.0 mm or less. When the distance between the first side walls 21 is longer than the distance between the second side walls 22, the depth D1 may be 10.0 mm or more and 50.0 mm or less. The length of the material can 20 in the height direction is, for example, 80.0 mm or more and 130.0 mm or less. However, the dimensions of the material can 20 are not limited thereto.

[0046] In the straightening process, the bottom surface 135 of the core 13 may be in contact with the bottom plate 24 of the material can 20 from the inside. In the present embodiment, the mold set 10 may further include a pressing die 14. The pressing die 14 is disposed outside the material can 20 so as to face the bottom surface 135 of the core 13. The bottom plate 24 of the material can 20 may be supported from the inside and outside by the bottom surface 135 of the core 13 and the pressing die 14. The top surface 134 of the core 13 preferably protrudes outward in the height direction from the opening 25 of the material can 20.

[0047] Continuing with reference to FIGS. 2B and 2C, when starting the straightening process, the first mold 11 of the mold set 10 is disposed outside the material can 20. The first molds 11 are respectively provided corresponding to the first side walls 21 of the material can 20. That is, the first molds 11 are each configured to be able to process the first side walls 21 of the material can 20.

[0048] At the start of the straightening process, the distance between the first molds 11 is larger than the width W1 between the first side walls 21 of the material can 20. The first molds 11 are arranged with a displacement in the height direction (axial direction) with respect to the material can 20. In the present embodiment, each first mold 11 is disposed on the opening 25 side of the material can 20 so that a part thereof faces a part of the first side wall 21 with a gap. At the start of the straightening process, the first molds 11 do not face the portion of the first side wall 21 of the material can 20 on the bottom plate 24 side.

[0049] As shown in FIG. 2C, when starting the correction process, the second mold 12 of the mold set 10 is arranged outside the material can 20. The length of the second mold 12 in the width direction of the mold set 10 is preferably equal to or greater than the width W1 of the material can 20. Each of the second molds 12 faces the second side wall 22 of the material can 20. Each of the second molds 12 is in contact with the outer surface of the second side wall 22 of the material can 20. More specifically, each of the second molds 12 is in contact with the second side wall 22 of the material can 20 by the support surface 121. The second side walls 22 of the material can 20 are supported from the inside and outside by the second side surfaces 132 of the cores 13 and the support surfaces 121 of the second molds 12, respectively. Each of the second molds 12 preferably supports the entire or substantially the entire corresponding second side wall 22 together with the core 13.

[0050] In the correction process, with the second side wall 22 of the material can 20 supported by the second mold 12 and the core 13, the first mold 11 is moved relative to the material can 20 from the opening 25 side to the bottom plate 24 side while pressing the first side wall 21 and the corner portion 23 of the material can 20 toward the core 13 side by the first mold 11. As shown in FIGS. 2B to 2D, in this embodiment, first, the first mold 11 approaches the first side wall 21 of the material can 20. The first mold 11 approaches the core 13 so as to press the first side wall 21 and the corner portion 23 against the core 13 on the opening 25 side, and moves relative to the material can 20 toward the bottom plate 24 side. The first mold 11 moves relative to the material can 20 with the tip surface 112 as the leading end in the traveling direction while pressing the first side wall 21 and the corner portion 23 toward the core 13 side by the pressing surface 111.

[0051] In the example of this embodiment, the first mold 11 moves from the opening 25 side to the bottom plate 24 side of the material can 20. However, the material can 20 may move together with the second mold 12, the core 13, and the pressing mold 14 and be pushed into the first molds 11. In the correction process, the material can 20 may be arranged with the opening 25 facing downward as in this embodiment, or the material can 20 may be arranged with the bottom plate 24 facing downward. The orientation of the material can 20 and the mold set 10 in the correction process is not particularly limited.

[0052] After the movement in the width direction is completed, the first mold 11 may start moving in the height direction (axial direction), or may start moving in the height direction before the movement in the width direction is completed. That is, the first mold 11 may start moving toward the bottom plate 24 side after pressing the first side wall 21 and the corner portion 23 of the material can 20 against the core 13 and sandwiching the material can 20 together with the core 13 on the opening 25 side. Alternatively, the first mold 11 may start moving toward the bottom plate 24 side before the first side wall 21 and the corner portion 23 of the material can 20 are completely pressed against the core 13. In any case, during the correction process, the first side wall 21 and the corner portion 23 of the material can 20 are pressed against the core 13 by the first mold 11. The first mold 11 slides on the material can 20 toward the bottom plate 24 side while pressing the first side wall 21 and the corner portion 23 against the core 13.

[0053] Referring to FIGS. 2D to 2F, in the correction process, with the second side wall 22 of the material can 20 supported by the second mold 12 and the core 13, the first side wall 21 and the corner portion 23 of the material can 20 are pressed against the core 13 side by the first mold 11. The first side wall 21 and the corner portion 23 of the material can 20 are deformed so as to be crushed by the first mold 11 and are sandwiched between the first mold 11 and the core 13. At this time, the support surface 121 of the second mold 12 and the second side surface 132 of the core 13 support the entire second side wall 22 so that the second side wall 22 of the material can 20 does not move in the depth direction of the mold set 10. Further, the pressing mold 14 supports the entire bottom plate 24 so that the bottom plate 24 of the material can 20 does not move in the height direction. The first mold 11 compresses the first side wall 21 and the corner portion 23 of the material can 20 inward in the width direction of the mold set 10 while sliding on the material can 20. Finally, the entire first side wall 21 and the corner portion 23 of the material can 20 are compressed inside the material can 20 by the first mold 11. As a result, the material can 20 is corrected and becomes a bottomed rectangular tubular metal can 30 as shown in FIG. 2G.

[0054] Figure 2H is a cross-sectional view of the raw material can 20 before correction, and is a view showing an enlarged part to be deformed by correction. Figure 2I is a cross-sectional view of the metal can 30 after correction, and is a view showing an enlarged part deformed by correction. In Figure 2I, the raw material can 20 before correction is also shown by a two-dot chain line.

[0055] As shown in Figure 2H, in the raw material can 20 before correction, each corner part 23 continuous with the first side wall 21 has a radius of curvature R0. The radius of curvature R0 is the radius of curvature of the corner part 23 on the outer surface of the raw material can 20. The radius of curvature R0 is the radius of a circle passing through three points, namely, both R stops of the corner part 23 and the midpoint between them. The radius of curvature R0 can be measured, for example, at a position 5.0 mm in the height direction from the opening 25 (Figure 2A) of the raw material can 20.

[0056] When the radius of curvature R0 is excessive, the raw material can 20 may be, for example, oval in plan view. From the viewpoint of ensuring the rectangular shape of the raw material can 20, the radius of curvature R0 is preferably 20.0 mm or less. The radius of curvature R0 is preferably 15.0 mm or less. When the radius of curvature R0 is small, the necessity of reducing the diameter of the corner part 23 by correction is reduced. Therefore, the radius of curvature R0 is, for example, 3.0 mm or more, and preferably 5.0 mm or more.

[0057] Regarding each first side wall 21 and the corner parts 23 on both sides thereof, the line length from the R stop of one corner part 23 (on the second side wall 22 side) to the R stop of the other corner part 23 (on the second side wall 22 side) is defined as L1. The line length L1 is the length measured along the outer surface of the raw material can 20 from the R stop of one corner part 23 to the R stop of the other corner part 23 in the cross-section of the raw material can 20 at the measurement position of the radius of curvature R0. The line length L1 can be divided into the line length L of both corner parts 23 1-1 and the line length L of the first side wall 21 1-2 and can be classified.

[0058] The first side wall 21 and the corner portions 23 on both sides thereof are deformed so as to be crushed in the correction process. As a result, the corner portions 23 are reduced in diameter. When the correction process is carried out, the first side wall 21 and the corner portions 23 on both sides thereof become the straight portions 31, 32 and the corner portions 33 in the corrected metal can 30 as shown in Fig. 2I.

[0059] The straight portions 31 and the corner portions 33 are arranged on both sides of the straight portion 32. The straight portion 31 is connected to the straight portion 32 through each of the corner portions 33. In the metal can 30, each of the corner portions 33 has a radius of curvature R1. The radius of curvature R1 is the radius of curvature of the corner portion 33 on the outer surface of the metal can 30. The corner portion 33 may be an arc shape having a curvature, or may be a pin angle shape having a curvature of 0.

[0060] When the corner portion 33 has a curvature (curvature ≠ 0), the radius of curvature R1 is defined as the radius of a circle passing through the two R stops of the corner portion 33 and the midpoint thereof. This radius of curvature R1 can be measured, for example, at a position 5.0 mm in the height direction from the opening of the metal can 30. The radius of curvature R1 is, for example, 0 mm or more and 10.0 mm or less. When the corner portion 33 is a pin angle shape, the radius of curvature R1 is defined as 0.

[0061] Regarding the straight portions 31, 32 and the corner portions 33, let the line length from the end of one straight portion 31 (the second side wall 22 side) to the end of the other straight portion 31 (the second side wall 22 side) be L2. The end of the straight portion 31 is the portion (Fig. 2H) that was the R stop of the corner portion 23 in the raw material can 20 before correction. The line length L2 is the length measured along the outer surface of the metal can 30 from the end of one straight portion 31 to the end of the other straight portion 31 in the cross section of the metal can 30 at the measurement position of the radius of curvature R1. The line length L2 can be divided into the line length L of the straight portion 31, the line length L of the corner portion 33, and the line length L of the straight portion 32. It is preferable that the line length L2 is substantially or almost equal to the line length L1 (Fig. 2H) of the portion to be deformed in the raw material can 20 before correction. 2-1 the line length L of the corner portion 33 2-2 and the line length L of the straight portion 32 2-3 It can be divided into. It is preferable that the line length L2 is substantially or almost equal to the line length L1 (Fig. 2H) of the portion to be deformed in the raw material can 20 before correction.

[0062] In the straightening process, the width W1 (Fig. 2B) of the material can 20 is reduced by compressing each of the first side wall 21 and the corner portion 23 in the width direction by the first die 11 (Figs. 2B and 2C). As shown in Fig. 2I, when the displacement amount of the first side wall 21 due to straightening is ΔX, ΔX can be expressed by the following formula (1). When the cross section of the material can 20 before straightening and the cross section of the metal can 30 after straightening are overlapped so that their centers coincide, ΔX is the distance from the first side wall 21 of the material can 20 to the straight portion 32 of the metal can 30. The width W0 (Fig. 2B) of the core 13 corresponds to the width W1 (Fig. 2B) of the material can 20 before straightening minus 2ΔX and the plate thicknesses of both first side walls 21. ΔX = R0 - (L 2-1 + R1) ···(1)

[0063] Referring again to Fig. 2H, in the material can 20 before straightening, the line length L 1-1 of each corner portion 23 can be calculated as 1 / 4 × 2πR0. Also, in the material can 20 before straightening, the line length L 1-2 of the first side wall 21 can be calculated by subtracting 2R0 from the depth D1 which is the distance between the second side walls 22. Therefore, the line length L1 of the portion to be deformed in the material can 20 before straightening is expressed by the following formula (2). L1 = 2L 1-1 + L 1-2 = 2(1 / 4 × 2πR0) + (D1 - 2R0) = D1 + 1.1416R0···(2)

[0064] On the other hand, referring to Fig. 2I, in the metal can 30 after straightening, the line length L 2-2 of each corner portion 33 can be calculated as 1 / 4 × 2πR1. Since the depth D1 (Fig. 2H) which is the distance between the second side walls 22 does not substantially change before and after straightening, the line length L 2-3 of the straight portion 32 can be calculated by subtracting 2R1 from D1. Therefore, the line length L2 of the portion after deformation in the metal can 30 is expressed by the following formula (3). L2 = 2L 2-1 + 2L 2-2 + L 2-3 = 2L 2-1 + 2(1 / 4 × 2πR1) + (D1 - 2R1) = 2L 2-1 + D1 + 1.1416R1 ···(3)

[0065] If the line lengths L1 and L2 before and after correction are in the relationship of L1 = L2 + α, or L1 = L2 - β (α and β are constants of 0 or more (mm)), then the line length L of the straight part 31 2-1 can be expressed by the following formula (4-1) or formula (4-2) using formulas (2) and (3). D1 + 1.1416R0 = (2L 2-1 + D1 + 1.1416R1) + α L 2-1 = 0.5708(R0 - R1) - α / 2 ···(4-1) D1 + 1.1416R0 = (2L 2-1 + D1 + 1.1416R1) - β L 2-1 = 0.5708(R0 - R1) + β / 2 ···(4-2)

[0066] Substituting formula (4-1) into formula (1), the displacement amount ΔX in the width direction of the first side wall 21 in the correction process is represented by the following formula (5). ΔX = R0 - (0.5708(R0 - R1) - α / 2 + R1) = (R0 - 0.5708R0) - (R1 - 0.5708R1) + α / 2 ···(5)

[0067] α is the difference between the line length L1 before correction and the line length L2 after correction. When L1 = L2 + α, the line length L2 after correction is less than or equal to the line length L1 before correction. When α is too large, surplus material due to correction is likely to occur. From the viewpoint of suppressing the generation of wrinkles caused by the surplus material, α is preferably, for example, 4.0 mm or less. In this case, from formula (5), the displacement amount ΔX in the width direction of the first side wall 21 in the correction process can satisfy the following formula (6). However, the units of ΔX, R0, and R1 in formula (6) are all mm. ΔX ≦ (R0 - 0.5708R0) - (R1 - 0.5708R1) + 2.0 ···(6)

[0068] In order to more easily suppress the generation of wrinkles caused by excess meat, it is more preferable that α is 2.0 mm or less. That is, the constant 2.0 on the right side of the above formula (6) can be replaced with 1.0.

[0069] When substituting formula (4-2) into formula (1), the displacement amount ΔX in the width direction of the first side wall 21 in the correction process is represented by the following formula (7). ΔX = R0 - (0.5708(R0 - R1) + β / 2 + R1) = (R0 - 0.5708R0) - (R1 - 0.5708R1) - β / 2 ···(7)

[0070] β is the difference between the wire length L1 before correction and the wire length L2 after correction. When L1 = L2 - β, the wire length L2 after correction is equal to or greater than the wire length L1 before correction. The larger β is, the more likely it is that the plate thickness reduction due to correction will occur. From the viewpoint of suppressing the plate thickness reduction, it is preferable that β is, for example, 2.0 mm or less. In this case, from formula (7), the displacement amount ΔX in the width direction of the first side wall 21 in the correction process can satisfy the following formula (8). However, the units of ΔX, R0, and R1 in formula (8) are all mm. ΔX ≧ (R0 - 0.5708R0) - (R1 - 0.5708R1) - 1.0 ···(8)

[0071] It is more preferable that β is 1.0 mm or less. That is, the constant 1.0 on the right side of the above formula (8) can be replaced with 0.5.

[0072] [Effect] In this embodiment, the material can 20 is corrected using the mold set 10. When correcting the material can 20, the core 13 of the mold set 10 is arranged inside the material can 20 in a state of contacting the second side wall 22 of the material can 20 and creating a gap between each of the first side walls 21 of the material can 20. The pair of first molds 11 of the mold set 10 are configured to crush the first side wall 21 and the corner portion 23 of the material can 20 toward the first side surface 131 side of the core 13. Further, the pair of second molds 12 of the mold set 10 are configured to support the second side wall 22 of the material can 20 together with the second side surface 132 of the core 13. Therefore, in the correction process of the material can 20, with the second side wall 22 of the material can 20 supported by the second mold 12 and the core 13, the first side wall 21 and the corner portion 23 of the material can 20 can be pressed against the core 13 side by the first mold 11. As a result, each of the corner portions 23 of the material can 20 is crushed, deformed so as to have a sharp corner, and reduced in diameter. As a result, a metal can 30 having a corner portion 33 with a curvature radius R1 smaller than the original curvature radius R0 can be obtained.

[0073] Since the corner portion 33 of the metal can 30 is reduced in diameter in this way, for example, in an electric vehicle, batteries using the metal can 30 as a battery case can be arranged relatively densely. That is, since the curvature radius R1 of the corner portion 33 of the metal can 30 obtained by correction is smaller than the curvature radius R0 of the original material can 20, for example, compared with the case of using a metal can manufactured only by drawing as a battery case, the voids generated between the arranged batteries can be reduced. Thereby, it is possible to increase the energy density of the battery in an electric vehicle or the like.

[0074] In this embodiment, when reducing the diameter of the corner portion 23 in the correction process, the first mold 11 is pressed against the material can 20 from the outside, and the first side wall 21 and the corner portion 23 are compressed. Therefore, in the correction process, an increase in the line length L1 (surface area) of the first side wall 21 and the corner portion 23 can be suppressed, and a decrease in the plate thickness due to correction can be suppressed. Therefore, even when the plate thickness of the material can 20 is small, the material can 20 can be corrected to reduce the diameter of the corner portion 23.

[0075] Furthermore, in the present embodiment, the pair of first dies 11 of the die set 10 is configured to move from the opening 25 side to the bottom plate 24 side relative to the material can 20 while pressing the first side wall 21 and the corner portion 23 of the material can 20 against the core 13. Therefore, when correcting the material can 20, the material of the first side wall 21 can be moved to the corner portion between the first side wall 21 and the bottom plate 24 by the first die 11. Thus, for example, even if a reduction in plate thickness occurs at the corner portion or the like on the bottom plate 24 side of the material can 20 as a result of deep drawing, the reduction in plate thickness can be eliminated or alleviated through the correction process.

[0076] The first die 11 preferably moves a distance of at least half of the first side wall 21 in the height direction (axial direction) of the material can 20 while pressing the first side wall 21 and the corner portion 23 against the core 13. The greater the moving distance of the first die 11 in the height direction of the material can 20, the more material is supplied from the first side wall 21 to the corner portion on the bottom plate 24 side. Therefore, the reduction in plate thickness at the corner portion between the first side wall 21 and the bottom plate 24 is more likely to be eliminated or alleviated.

[0077] In the present embodiment, the displacement amount ΔX of the first side wall 21 in the correction process preferably satisfies the above-described formula (6) in relation to the radius of curvature R0 of the corner portion 23 of the material can 20 before correction and the radius of curvature R1 of the corner portion 33 of the metal can 30 after correction. In this case, the line length L2 of the deformation completion portion in the metal can 30 after correction does not become too small compared to the line length L1 of the deformation planned portion in the material can 20 before correction. Therefore, excess material due to correction is less likely to occur, and the occurrence of wrinkles in the metal can 30 can be suppressed.

[0078] In the present embodiment, it is preferable that the displacement amount ΔX of the first side wall 21 in the correction process satisfies the above-described formula (8) in relation to the radius of curvature R0 of the corner portion 23 of the raw material can 20 before correction and the radius of curvature R1 of the corner portion 33 of the metal can 30 after correction. In this case, the line length L2 of the deformation completion portion in the metal can 30 after correction does not become too large with respect to the line length L1 of the deformation planned portion in the raw material can 20 before correction. Therefore, a decrease in plate thickness due to correction is less likely to occur, and the occurrence of cracks in the metal can 30 can be suppressed.

[0079] However, since the first side wall 21 and the corner portion 23 are crushed inside the raw material can 20 by the first mold 11, the line length L2 after correction is often approximately the same as or less than the line length L1 before correction. That is, since the first side wall 21 and the corner portion 23 of the raw material can 20 are crushed and it is difficult to apply circumferential tension, a decrease in plate thickness due to correction is unlikely to occur in the first place. Therefore, in the manufacturing method according to the present embodiment, it is preferable to satisfy at least formula (6) among formula (6) regarding the extra thickness and formula (8) regarding the decrease in plate thickness.

[0080] Generally, an aluminum alloy plate is used for the battery case. When aiming to improve the space efficiency of the battery, it is conceivable to adopt a higher-strength steel plate as the material for the battery case instead of the aluminum alloy plate, and make the battery case smaller and thinner than before. On the other hand, since the specific gravity of steel is larger than that of the aluminum alloy, when it is necessary to avoid an increase in the weight of the battery due to the application of the steel plate, a considerable reduction in thickness is required for the battery case. More specifically, since the specific gravity of steel is about three times that of the aluminum alloy, the thickness of the battery case formed of the steel plate is required to be about 1 / 3 or less of the thickness of the battery case formed of the aluminum alloy plate. However, when the steel plate is thin, it is difficult to reduce the diameter of the corner portion by ironing as in the conventional method due to the load on the mold. Also, since the steel plate has high strength, the load on the mold is large, and the application of ironing is difficult.

[0081] In contrast, in this embodiment, without applying ironing, the corner portion 23 between the side walls 21 and 22 of the blank can 20 can be reduced in diameter. That is, when the first side wall 21 and the corner portion 23 of the blank can 20 are crushed by the first mold 11, the radius of curvature R0 of the corner portions 23 on both sides of each first side wall 21 becomes smaller. Therefore, even if the first side wall 21 continuous with the corner portion 23 is formed of a steel plate and the first side wall 21 is as thin as 0.1 mm or more and 2.0 mm or less, the corner portion 23 can be relatively easily reduced in diameter. Further, even when it is difficult to apply ironing because the blank can 20 is large, the corner portion 23 can be reduced in diameter.

[0082] In this embodiment, the metal can 30 can be formed of a steel plate. Since the steel plate has higher strength than an aluminum alloy plate, by adopting the steel plate, the metal can 30 can be made thinner. The side wall of the metal can 30 after correction can also have a plate thickness of, for example, 0.1 mm or more and 2.0 mm or less. Thereby, for example, in an electric vehicle, when arranging batteries using the metal can 30 as a battery case, compared with the case of using a battery case of a general aluminum alloy plate, the ratio of the battery case to the battery mounting space becomes smaller. Therefore, the space efficiency of the battery can be improved.

[0083] However, the use of the metal can 30 is not limited to the case of an in-vehicle battery. The metal can 30 may be used as a case for a stationary battery. The metal can 30 may be used other than as a battery case.

[0084] <Second Embodiment> FIGS. 3A to 3C are schematic diagrams for explaining a method of manufacturing the metal can 30 (FIG. 2G) according to this embodiment. In this embodiment, the mold set 10 for correcting the blank can 20 has substantially the same configuration as that of the first embodiment. However, in this embodiment, the operation of the mold set 10 is different from that of the first embodiment.

[0085] In the first embodiment, the first mold 11 of the mold set 10 approaches the material can 20 in the width direction and moves relatively in the height direction (axial direction). Specifically, in the correction process of the material can 20, the first mold 11 approaches the core 13 to press the first side wall 21 and the corner portion 23 of the material can 20 against the core 13 on the opening 25 side, and moves relatively toward the bottom plate 24 side with respect to the material can 20. In contrast, in the present embodiment, the first mold 11 moves relatively only in the height direction (axial direction) with respect to the material can 20.

[0086] Referring to FIG. 3A, at the start of the correction process, the distance between the first molds 11 is smaller than the distance (width) W1 between the first side walls 21 of the material can 20 in advance. Specifically, the distance between the first molds 11 is smaller than the width W1 between the first side walls 21 of the material can 20 by 2×ΔX (FIG. 2I). The first molds 11 of the metal can 30 are respectively arranged on the opening 25 side of the material can 20 in the height direction (axial direction) so that a part of the tip end surface 112 faces a part of the opening 25 of the material can 20.

[0087] Referring to FIGS. 3B and 3C, in the correction process, with the distance between the first molds 11 being smaller than the width W1 of the material can 20, the first molds 11 contact the opening end of the peripheral wall of the material can 20 and move relatively toward the bottom plate 24 side with respect to the material can 20. As a result, the first side wall 21 and the corner portion 23 (FIGS. 2H and 2I) of the material can 20 are pressed against the core 13 side in order from the opening 25 side toward the bottom plate 24 side, as in the first embodiment.

[0088] Even when the mold set 10 operates as in the present embodiment, the same effects as those in the first embodiment can be achieved. In the case of the present embodiment, since the distance that the first mold 11 of the mold set 10 slides on the first side wall 21 of the material can 20 in the height direction (axial direction) is larger than that in the first embodiment, in the correction process, the material of the first side wall 21 is more likely to gather at the corner portion on the bottom plate 24 side. Therefore, it is possible to more expect the elimination or mitigation of the reduction in the plate thickness at the corner portion between the first side wall 21 and the bottom plate 24.

[0089] <Third Embodiment> FIG. 4 and FIG. 5 are cross-sectional views schematically showing the mold set 10A according to the present embodiment. The mold set 10A has substantially the same configuration as the mold set 10 according to other embodiments. However, the mold set 10A is different from the mold set 10 according to other embodiments in the shape of the core 13A.

[0090] In the mold set 10 according to other embodiments, the corner portions 133 of the core 13 each have a shape that generally follows the corner portions 33 of the corrected metal can 30. That is, the corner portions 133 of the core 13 each have a radius of curvature corresponding to the radius of curvature R1 of the corrected corner portion 33. On the other hand, as shown in FIG. 4, in the mold set 10A according to the present embodiment, the corner portions 133A of the core 13A each have a shape that follows a part of the corner portion 23 of the raw material can 20 before correction. At the start of the correction process, the corner portions 133A of the core 13A are each provided along the portion of the corner portion 23 of the raw material can 20 that is continuous with the second side wall 22. However, the corner portions 133A of the core 13A are not arranged in the portion of the corner portion 23 of the raw material can 20 that is continuous with the first side wall 21. Each corner portion 133A has a radius of curvature corresponding to the radius of curvature R0 (FIG. 2H) of the corner portion 23 before correction.

[0091] Alternatively, as shown in FIG. 5, the corner portions 133A of the core 13A may each be a chamfered portion C between the first side surface 131 and the second side surface 132. In this case, each of the corner portions 133A is an inclined surface inclined with respect to the side surfaces 131 and 132. The inclination angle of the corner portion 133A with respect to the side surfaces 131 and 132 is not particularly limited. An R-chamfering process may be performed on the boundary portion between the corner portion 133A and the first side surface 131. Similarly, an R-chamfering process may be performed on the boundary portion between the corner portion 133A and the second side surface 132.

[0092] Even when performing the correction process of the material can 20 using the mold set 10A according to this embodiment, the same effects as those of other embodiments can be achieved. The first mold 11 of the mold set 10A may operate as described in the first embodiment or may operate as described in the second embodiment. In the case of the mold set 10A according to this embodiment, for example, even when the radius of curvature R0 (FIG. 2H) of each corner portion 23 of the material can 20 before correction is large, it becomes easier to dispose the core 13 inside the material can 20.

[0093] As described above, the embodiments according to the present disclosure have been described. However, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from the spirit thereof.

Example

[0094] Hereinafter, the present disclosure will be described in more detail by way of examples. However, the present disclosure is not limited to the following examples.

[0095] To confirm the effects of the present disclosure, CAE analysis was performed using commercially available analysis software (LS-DYNA, manufactured by JSOL Corporation) on the correction of the material can 20 using the mold set 10 according to the above embodiment, and the thickness reduction rate of the metal can 30 after correction was investigated.

[0096] The dimensions of the material can 20 before correction and the metal can 30 after correction are as follows. · Before correction: D26.5×W148.0×H100.0, R0 = 5.0, [mm] · After correction (target value): D26.5×W144.5×H100.0, R1 = 1.5, ΔX = 1.75, [mm]

[0097] The thickness reduction rate of the metal can 30 after correction is shown in FIG. 6. In FIG. 6, Example 1 is an example in which, as in the first embodiment, the first die 11 of the die set 10 is moved in the width direction to contact the first side wall 21 of the blank can 20 and then slid on the first side wall 21 in the height direction (axial direction). Example 2 is an example in which, as in the second embodiment, the first die 11 is not moved in the width direction and is only slid in the height direction on the first side wall 21 of the blank can 20. FIG. 6 also shows, as a comparative example, the thickness reduction rate of the blank can 20 (deep drawn product) before correction. The thickness reduction rate is obtained by ((thickness of the material) - (thickness of each part after forming)) / (thickness of the material). The thickness of the material is the thickness of the metal sheet before deep drawing. In this analysis, the thickness of the material was set to 0.3 mm. The thickness of each part after forming is, in the case of the comparative example, the thickness of each part of the blank can 20 after deep drawing, and in the case of Examples 1 and 2, the thickness of each part of the metal can 30 obtained by correcting the blank can 20. In FIG. 6, for each of the comparative example and Examples 1 and 2, the maximum value of the measured thickness reduction rate (thickness reduction rate of the thinnest part) is shown. As shown in FIG. 6, the thickness reduction rates of Examples 1 and 2 were lower than the thickness reduction rate of the comparative example. When comparing Examples 1 and 2, the thickness reduction rate of Example 2 was slightly lower than that of Example 1.

[0098] Regarding the comparative example, the radius of curvature R0 of the corner portion 23 between the side walls of the blank can 20, and regarding Examples 1 and 2, the radius of curvature R1 of the corner portion 33 between the side walls in the metal can 30 after correction are shown in FIG. 7. FIG. 7 also shows the radius of curvature of the corner portion on the bottom plate side for each of the comparative example and Examples 1 and 2. Referring to FIG. 7, in each example, the radius of curvature R1 of the corner portion 33 between the side walls was clearly smaller compared to the radius of curvature R0 before correction. In each example, the corner portion between the longitudinal side wall and the bottom plate, that is, the corner portion on the bottom plate side that is continuous with the side wall deformed by the correction, was also deformed and reduced in diameter. Also, in each example, the corner portion between the short-side side wall and the bottom plate was reduced in diameter.

[0099] As described above, according to the manufacturing method according to the present disclosure, it was confirmed that the corner portion 33 between the side walls can be made smaller in diameter while suppressing a decrease in plate thickness. Furthermore, it was confirmed that the corner portion continuous with the side wall deformed by correction among the corner portions on the bottom plate side can also be made smaller in diameter.

Explanation of Signs

[0100] 10, 10A: Die set 11: First die 12: Second die 13, 13A: Core 20: Material can 21: First side wall 22: Second side wall 23: Corner portion 24: Bottom plate 25: Opening 30: Metal can 33: Corner portion

Claims

1. A method for manufacturing a metal can, comprising: a pair of first side walls arranged to face each other, corner portions provided on both sides of each of the first side walls, a pair of second side walls each connected to both of the first side walls via the corner portions, and a bottom plate closing one axial end of the peripheral wall formed by the first side walls, the corner portions, and the second side walls, and preparing a blank can having an opening at the other axial end of the peripheral wall; using a mold set including a pair of first molds arranged outside the blank can and corresponding to the first side walls respectively, a pair of second molds arranged outside the blank can and facing the second side walls respectively, and cores arranged inside the blank can in contact with the second side walls and having a gap with each of the first side walls, and correcting the blank can to obtain a metal can; characterized in that in the step of correcting the blank can, while the second side walls are supported by the second molds and the cores, the first molds are moved relative to the blank can from the opening side to the bottom plate side while pressing the first side walls and the corner portions toward the core side by the first molds.

2. The manufacturing method according to claim 1, wherein in the step of correcting the blank can, the first molds approach the cores so as to press the first side walls and the corner portions toward the core side at the opening side, and move relative to the blank can toward the bottom plate side.

3. The manufacturing method according to claim 1, wherein in the step of correcting the blank can, the first molds contact the open end of the peripheral wall in a state where the distance between the first molds is smaller than the distance between the first side walls, and move relative to the blank can toward the bottom plate side.

4. The manufacturing method according to claim 1, Let the radius of curvature of the corner portion before correction be R ０ (mm), and the radius of curvature of the corner portion after correction be R １ (mm). When the displacement amount of the first side wall due to correction is ΔX (mm), R ０ , R １ , and ΔX satisfy the following formula, a manufacturing method. ΔX ≤ (R ０ −0.5708R ０ ) − (R １ −0.5708R １ ) + 2.0

5. The manufacturing method according to claim 1, wherein the corner portion before correction has a radius of curvature of 20.0 mm or less.

6. The manufacturing method according to claim 1, wherein the first side walls are formed of a steel plate and have a plate thickness of 0.1 mm or more and 2.0 mm or less.

7. A mold set for correcting a material can including a pair of first side walls arranged to face each other, corner portions provided on both sides of each of the first side walls, a pair of second side walls each connected to both of the first side walls via the corner portions, and a bottom plate closing an axial end of a peripheral wall formed by the first side walls, the corner portions, and the second side walls, the material can having an opening at the other axial end of the peripheral wall, including a pair of first side surfaces and a pair of second side surfaces connecting the first side surfaces to each other, a core disposed inside the material can when the mold set is in use, a pair of first molds respectively corresponding to the first side surfaces and disposed outside the material can when the mold set is in use, a pair of second molds respectively corresponding to the second side surfaces and disposed outside the material can when the mold set is in use, and comprising the first mold is configured to move from the opening side to the bottom plate side relative to the material can while crushing the first side wall and the corner portion of the material can toward the first side surface side, the second mold is configured to support the second side wall of the material can together with the second side surface, the mold set.

Images