Metal can manufacturing method and metal die set

Abstract

To provide a metal can manufacturing method that can further improve dimensional accuracy of a metal can.SOLUTION: A manufacturing method for a metal can (30) comprises the steps of: preparing a blank can (20); and correcting the blank can (20) by using a metal die set (10) including metal dies (11, 12), to obtain the metal can (30). The correction step for the blank can (20) including: pushing the metal die (12) between the metal dies (11) located in the blank can (20) to separate the metal dies (11); and along with that, bringing at least one corner part (116, 117P, 117Q) of the metal die (11) into contact with a corresponding corner part of the blank can (20) so as to increase a width between side walls (211). The at least one corner part (116, 117P, 117Q) of the metal die (11) has, at least at a part, a curvature radius smaller than a curvature radius of an inner surface of the corresponding corner part of the blank can (20).SELECTED DRAWING: Figure 3C

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a metal can. The present disclosure also relates to a mold set used for manufacturing a metal can from a blank can.

Background Art

[0002] For example, a metal can used as a battery cell case may be manufactured by deep drawing of a metal sheet. However, when manufacturing a metal can by deep drawing, dimensional accuracy defects of the metal can are likely to occur due to springback (canning) during processing. Dimensional accuracy defects of the metal can may be eliminated by applying ironing to the metal sheet during deep drawing.

[0003] In ironing, the clearance between the punch and the die is set smaller than the thickness of the metal sheet which is the material. Then, a metal can thinner than the original thickness of the metal sheet is formed by the punch and the die. When the original thickness of the metal sheet is small, the load applied to the metal sheet in the thickness direction from the punch and the die becomes large, and deformation or damage of the punch and the die may occur. Therefore, it is difficult to apply ironing to the manufacture of a thin-walled metal can.

[0004] Patent Document 1 discloses a technique in which a square can-shaped intermediate molded product is formed from a metal sheet by primary press molding, and then the width of the intermediate molded product is increased by secondary press molding. In secondary press molding, a split punch is disposed inside the intermediate molded product. Then, by pushing a wedge-shaped punch between the split punches, the split punches move in the width direction of the intermediate molded product, and tension acts on the wide side walls of the intermediate molded product. According to Patent Document 1, by applying tension in the width direction in secondary press molding to an intermediate molded product in which canning has occurred in primary press molding, the residual stress of the side wall can be relaxed, canning can be reduced, and the dimensional accuracy of the metal can can be improved.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2009-142851 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] In Patent Document 1, in the secondary press forming which is the correction process of the intermediate molded product, the split punch moves in the width direction of the intermediate molded product, so that tension is applied to the wide side wall and the canning of the side wall is reduced. However, with the technology of Patent Document 1, the canning may not be sufficiently reduced. Therefore, there is a possibility that the dimensional accuracy of the obtained metal can is insufficient.

[0007] An object of the present disclosure is to provide a method for manufacturing a metal can capable of further improving the dimensional accuracy of the metal can. [Means for Solving the Problems]

[0008] 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 peripheral wall, a bottom plate, a first bottom corner portion, and a second bottom corner portion. The peripheral wall has a cylindrical shape. The peripheral wall includes a pair of first side walls, a second side wall, and side corner portions. The pair of first side walls are arranged opposite to each other. The second side wall is connected to each of the first side walls. The side corner portions are arranged between each of the first side walls and the second side wall. The bottom plate closes one axial end of the peripheral wall. The first bottom corner portion is arranged between each of the first side walls and the bottom plate. The second bottom corner portion is arranged between the second side wall and the bottom plate. The blank can has an opening at the other axial end of the peripheral wall. The mold set includes a pair of first molds and a second mold. The pair of first molds are provided corresponding to the pair of first side walls. Each of the first molds includes a first side surface, a second side surface, a side corner portion, a bottom surface, a first bottom corner portion, and a second bottom corner portion. The second side surface is connected to the first side surface. The side corner portion is arranged between the first side surface and the second side surface. The bottom surface is connected to the first side surface and the second side surface. The first bottom corner portion is arranged between the first side surface and the bottom surface. The second bottom corner portion is arranged between the second side surface and the bottom surface. In the step of correcting the blank can, while pushing the second mold axially from the opening side between the first molds arranged in the blank can to separate the first molds from each other, each of the first molds is brought into contact with the corresponding first side wall with the first side surface. At the same time, in the step of correcting the blank can, at least one corner portion among the side corner portion, the first bottom corner portion, and the second bottom corner portion of each of the first molds is brought into contact with the corresponding corner portion among the side corner portion, the first bottom corner portion, and the second bottom corner portion of the blank can, thereby expanding the width between the first side walls. At least one corner portion of each of the first molds has a radius of curvature smaller than the radius of curvature of the inner surface of the corresponding corner portion of the blank can at least in part.

Effect of the Invention

[0009] According to the method for manufacturing a metal can according to the present disclosure, the dimensional accuracy of the metal can can be further improved.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 3D

Figure 3E

Figure 3F

Figure 4

Figure 5

Figure 6

Figure 7A

Figure 7B

Figure 7C

Figure 8

Figure 9

Figure 10

Figure 11

MODE FOR CARRYING OUT THE INVENTION

[0011] The manufacturing method of a metal can according to an 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 peripheral wall, a bottom plate, a first bottom corner portion, and a second bottom corner portion. The peripheral wall has a cylindrical shape. The peripheral wall includes a pair of first side walls, a second side wall, and side corner portions. The pair of first side walls are arranged opposite to each other. The second side wall is connected to each of the first side walls. The side corner portions are arranged between each of the first side walls and the second side wall. The bottom plate closes one axial end of the peripheral wall. The first bottom corner portion is arranged between each of the first side walls and the bottom plate. The second bottom corner portion is arranged between the second side wall and the bottom plate. The blank can has an opening at the other axial end of the peripheral wall. The mold set includes a pair of first molds and a second mold. The pair of first molds are provided corresponding to the pair of first side walls. Each of the first molds includes a first side surface, a second side surface, a side corner portion, a bottom surface, a first bottom corner portion, and a second bottom corner portion. The second side surface is connected to the first side surface. The side corner portion is arranged between the first side surface and the second side surface. The bottom surface is connected to the first side surface and the second side surface. The first bottom corner portion is arranged between the first side surface and the bottom surface. The second bottom corner portion is arranged between the second side surface and the bottom surface. In the step of correcting the blank can, while pushing the second mold axially from the opening side between the first molds arranged in the blank can to separate the first molds from each other, each of the first molds is brought into contact with the corresponding first side wall by the first side surface. At the same time, in the step of correcting the blank can, at least one corner portion among the side corner portion, the first bottom corner portion, and the second bottom corner portion of each of the first molds is brought into contact with the corresponding corner portion among the side corner portion, the first bottom corner portion, and the second bottom corner portion of the blank can, thereby expanding the width between the first side walls. At least one corner portion of each of the first molds has a radius of curvature smaller than the radius of curvature of the inner surface of the corresponding corner portion of the blank can at least in part (the first configuration).

[0012] For example, in a material can formed by deep drawing or the like, canning may occur on its side wall. For example, the side wall of the material can may be partially swollen outward. More specifically, on the side wall of the material can, the opening side may be swollen outward compared to the bottom plate side. On the other hand, in the manufacturing method according to the first configuration, the material can is corrected by a mold set including a pair of a first mold and a second mold. In the correction process, at least one of the side corner portions, the first bottom corner portion, and the second bottom corner portion of the first mold contacts and expands the corresponding corner portion among the side corner portion, the first bottom corner portion, and the second bottom corner portion of the material can. The corner portion of the first mold has a radius of curvature smaller than the radius of curvature of the inner surface of the corresponding corner portion of the material can to be contacted, at least in part. Therefore, the corner portion of the material can is formed such that its radius of curvature becomes smaller than that before the correction process in at least a partial region. That is, in the said region of the corner portion of the material can, the line length after correction in a cross-sectional view perpendicular to the extending direction of the corner portion is larger than the line length before correction. Thereby, the material can flow from the second side wall of the material can toward the corner portion. As a result, even if there is a portion swollen outward on the second side wall of the material can, this swelling is reduced. Therefore, the dimensional accuracy of the metal can can be further improved.

[0013] In the manufacturing method according to the first configuration, in the process of correcting the material can, each side corner portion of the first mold may contact the side corner portion of the material can. In this case, each side corner portion of the first mold can have a radius of curvature smaller than the radius of curvature of the inner surface of the side corner portion of the material can, at least in part (second configuration).

[0014] In the second configuration, in the correction process, each side corner portion of the first mold contacts and expands the side corner portion of the material can. Each side corner portion of the first mold has a radius of curvature that is smaller than the radius of curvature of the inner surface of the side corner portion of the material can at least in part. As a result, at least a partial region of the side corner portion of the material can is formed by the first mold so that the radius of curvature of the inner surface becomes smaller. In this case, the dimensional accuracy of the metal can can be further improved.

[0015] In the manufacturing method according to the second configuration, each side corner portion of the first mold preferably has a radius of curvature that is smaller than the radius of curvature of the inner surface of the side corner portion of the material can in the portion on the opening side (third configuration).

[0016] In the third configuration, each side corner portion of the first mold has a radius of curvature that is smaller than the radius of curvature of the inner surface of the side corner portion of the material can in the portion on the opening side of the material can. That is, the region of the side corner portion of the material can that is formed by the first mold so that the radius of curvature of the inner surface becomes smaller is provided on the opening side of the material can. In this case, the dimensional accuracy of the metal can can be further improved.

[0017] In the manufacturing method according to any one of the first to third configurations, in the process of correcting the material can, each first bottom corner portion of the first mold may contact the first bottom corner portion of the material can. In this case, each first bottom corner portion of the first mold can have a radius of curvature that is smaller than the radius of curvature of the inner surface of the first bottom corner portion of the material can at least in part (fourth configuration).

[0018] In the fourth configuration, in the correction process, each first bottom corner portion of the first mold contacts and expands the first bottom corner portion of the material can. Each first bottom corner portion of the first mold has a radius of curvature that is smaller than the radius of curvature of the inner surface of the first bottom corner portion of the material can at least in part. As a result, the first bottom corner portion of the material can is formed by the first mold so that the radius of curvature of the inner surface becomes smaller in at least a partial region. Also in this case, the dimensional accuracy of the metal can can be improved.

[0019] In the manufacturing method according to any one of the first to fourth configurations, in the step of correcting the material can, each second bottom corner portion of the first mold may contact the second bottom corner portion of the material can. In this case, each second bottom corner portion of the first mold can have a radius of curvature smaller than the radius of curvature of the inner surface of the second bottom corner portion of the material can at least in part (fifth configuration).

[0020] In the fifth configuration, in the correction step, each second bottom corner portion of the first mold contacts and expands the second bottom corner portion of the material can. Each second bottom corner portion of the first mold has a radius of curvature smaller than the radius of curvature of the inner surface of the second bottom corner portion of the material can at least in part. Thereby, the second bottom corner portion of the material can is formed so that the radius of curvature of the inner surface becomes smaller by the first mold in at least a partial region. Also in this case, the dimensional accuracy of the metal can can be improved.

[0021] In the manufacturing method according to any one of the first to fifth configurations, each of the first molds can further include a chamfered surface. The chamfered surface is provided between the side corner portion and the bottom surface (sixth configuration).

[0022] In the sixth configuration, a chamfered surface is provided between the side corner portion and the bottom surface of the first mold. Thereby, in the correction step, the corner portion between the side corner portion and the bottom plate of the material can becomes less likely to contact the first mold. As a result, deformation of the corner portion of the material can is suppressed, and breakage of the corner portion is less likely to occur. Therefore, according to the sixth configuration, the formability of the material can is improved.

[0023] In the manufacturing method according to any one of the first to sixth configurations, the first side surface may be formed such that the portion on the opening side is located outside in the separating direction of the first mold with respect to the portion on the bottom plate side (seventh configuration).

[0024] In the manufacturing method according to the seventh configuration, the first side surfaces of the first mold that contact the first side wall of the material can are each formed such that the portion on the opening side is located outside in the separating direction of the first mold with respect to the portion on the bottom plate side. Therefore, each of the first side surfaces of the first mold first contacts the first side wall on the opening side and preferentially expands the width between the first side walls on the opening side. As a result, the first side wall tilts with respect to the axial direction of the material can such that the width between the two is larger on the opening side and smaller on the bottom surface side. Therefore, even if springback of the first side wall occurs when the first mold separates from the first side wall, the first side wall is likely to be in a state parallel or nearly parallel to the axial direction of the material can. As a result, the dimensional difference between the opening side and the bottom plate side with respect to the width between the first side walls of the corrected material can (metal can) is reduced, and the dimensional accuracy of the metal can can be further improved.

[0025] In the manufacturing method according to any one of the first to seventh configurations, in the step of correcting the material can, the regions of the first side wall that contact the first mold may each be pressed by a pad from the outside of the material can (eighth configuration).

[0026] In the manufacturing method according to the eighth configuration, when correcting the material can, the regions of the first side wall that contact the first mold are each pressed by a pad from the outside of the material can. That is, with the first side wall sandwiched from the inside and outside of the material can, the width between the first side walls is expanded. In this case, the shape accuracy of the first side wall is likely to be ensured.

[0027] The mold set according to the embodiment is used to manufacture a metal can from a material can. The mold set includes a pair of first molds and a second mold. Each first mold includes a top surface, a bottom surface, a first side surface, a surface to be abutted, a second side surface, a side corner portion, a first bottom corner portion, and a second bottom corner portion. The bottom surface is disposed on the opposite side of the top surface. The first side surface connects the top surface and the bottom surface. The surface to be abutted is disposed on the opposite side of the first side surface. The second side surface connects the first side surface and the surface to be abutted. The side corner portion is disposed between the first side surface and the second side surface. The first bottom corner portion is disposed between the first side surface and the bottom surface. The second bottom corner portion is disposed between the second side surface and the bottom surface. The second mold includes a pair of abutting surfaces. The abutting surfaces are surfaces for abutting against the surfaces to be abutted of the respective first molds. The second mold is configured such that the width between the abutting surfaces decreases from one end side in the axial direction to the other end side. The distance between the surface to be abutted of one of the pair of first molds and the surface to be abutted of the other first mold decreases from the top surface side to the bottom surface side corresponding to the width between the abutting surfaces. At least one of the side corner portion, the first bottom corner portion, and the second bottom corner portion corresponds to a corner portion provided on the material can and has a radius of curvature smaller than the radius of curvature of the inner surface of the corresponding corner portion at least in part (ninth configuration).

[0028] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The same or corresponding components in each figure are denoted by the same reference numerals, and the same description will not be repeated.

[0029] <First Embodiment> [Configuration of Mold] FIG. 1 is a perspective view schematically showing a mold set 10 according to the first embodiment. Referring to FIG. 1, the mold set 10 is used to manufacture a metal can from a material can. The mold set 10 includes a pair of first molds 11L and 11R and a second mold 12.

[0030] When the mold set 10 is in use, the first molds 11L and 11R are arranged side by side. The second mold 12 is a mold that is pushed between the first molds 11L and 11R. The second mold 12 is pushed in the vertical direction with respect to the first molds 11L and 11R placed on a horizontal plane, for example. When using the mold set 10, the first molds 11L and 11R and the second mold 12 may be attached to, for example, a press machine or other driving machinery.

[0031] The second mold 12 can approach the first molds 11L and 11R relatively. The second mold 12 is attached to, for example, the slide of a press machine or a hydraulic jack. As the second mold 12 is pushed in, the first molds 11L and 11R move apart from each other. Hereinafter, the direction in which the first molds 11L and 11R move apart is defined as the width direction of the mold set 10, the pushing direction of the second mold 12 is defined as the axial direction of the mold set 10, and the direction perpendicular to the width direction and the axial direction is defined as the depth direction of the mold set 10. The configurations of the first molds 11L and 11R and the second mold 12 will be described respectively. When there is no need to particularly distinguish between the first molds 11L and 11R, they are collectively referred to as the first mold 11.

[0032] Each of the first molds 11L and 11R includes a top surface 111, a bottom surface 112, a first side surface 113, a contact surface 114, two second side surfaces 115, two side corner portions 116, a first bottom corner portion 117P, and two second bottom corner portions 117Q.

[0033] The top surface 111 is the surface disposed on the pushing side of the second mold 12 in each of the first molds 11L and 11R. The bottom surface 112 is disposed on the opposite side of the top surface 111. In the example of the present embodiment, the top surface 111 and the bottom surface 112 are substantially rectangular. The first side surface 113 connects the top surface 111 and the bottom surface 112. In the example of the present embodiment, the first side surface 113 is substantially parallel to the axial direction. The surface to be abutted 114 is disposed on the opposite side of the first side surface 113. The surface to be abutted 114 is connected to the top surface 111. Each of the second side surfaces 115 is connected to the first side surface 113. The second side surfaces 115 connect the first side surface 113 and the surface to be abutted 114, respectively. The second side surfaces 115 are disposed on opposite sides of each other. The bottom surface 112 is connected to the first side surface 113, the surface to be abutted 114, and the two second side surfaces 115.

[0034] The side corner portions 116 are each disposed between the first side surface 113 and the second side surface 115. The first side surface 113 is connected to each of the second side surfaces 115 via the side corner portions 116. The side corner portions 116 each extend in the axial direction.

[0035] The first bottom corner portion 117P is disposed between the first side surface 113 and the bottom surface 112. The first side surface 113 is connected to the bottom surface 112 via the first bottom corner portion 117P. The first bottom corner portion 117P extends in the depth direction. The second bottom corner portions 117Q are each disposed between each of the second side surfaces 115 and the bottom surface 112. Each of the second side surfaces 115 is connected to the bottom surface 112 via the second bottom corner portion 117Q. The second bottom corner portions 117Q each extend in the width direction.

[0036] At least one of the side corner portion 116, the first bottom corner portion 117P, and the second bottom corner portion 117Q is subjected to an R chamfering process. In the example of the present embodiment, the R chamfering process is applied to all of the side corner portion 116, the first bottom corner portion 117P, and the second bottom corner portion 117Q. In this case, the side corner portion 116, the first bottom corner portion 117P, and the second bottom corner portion 117Q have a substantially arc-shaped cross-sectional shape. However, the R chamfering process may also be applied to the corner portions between any two surfaces of each of the first molds 11L and 11R.

[0037] In the example of the present embodiment, the radius of curvature of the side corner portion 116 is constant in its extending direction (axial direction). The radius of curvature of the side corner portion 116 is the radius of curvature in a cross-sectional view obtained by cutting the side corner portion 116 perpendicularly to its extending direction. The radius of curvature of the first bottom corner portion 117P is typically constant in its extending direction (depth direction). The radius of curvature of the first bottom corner portion 117P is the radius of curvature in a cross-sectional view obtained by cutting the first bottom corner portion 117P perpendicularly to its extending direction. The radius of curvature of the second bottom corner portion 117Q is typically constant in its extending direction (width direction). The radius of curvature of the second bottom corner portion 117Q is the radius of curvature in a cross-sectional view obtained by cutting the second bottom corner portion 117Q perpendicularly to its extending direction. In the present embodiment, the radius of curvature of the second bottom corner portion 117Q is the same as the radius of curvature of the first bottom corner portion 117P. However, the radius of curvature of the second bottom corner portion 117Q may be different from the radius of curvature of the first bottom corner portion 117P.

[0038] The second mold 12 includes a pair of abutting surfaces 121 and 122. The abutting surfaces 121 and 122 are surfaces for abutting against the respective abutting surfaces 114 of the first molds 11L and 11R. The abutting surface 122 is disposed on the opposite side of the abutting surface 121.

[0039] Hereinafter, with reference to FIG. 2, the configurations of the first molds 11L and 11R and the second mold 12 will be further described. FIG. 2 is a cross-sectional view (longitudinal sectional view) obtained by cutting the first molds 11L and 11R and the second mold 12 with a plane perpendicular to the depth direction of the mold set 10.

[0040] As described above, the second mold 12 is pushed between the first molds 11L and 11R to separate the first molds 11L and 11R. That is, the second mold 12 functions as a cam driver. Therefore, as shown in FIG. 2, the second mold 12 is configured such that the width between the contact surfaces 121 and 122 decreases from one end side in the axial direction to the other end side. The contact surfaces 121 and 122 approach each other from the base end portion to the tip end portion of the second mold 12. The contact surfaces 121 and 122 are typically inclined surfaces that are inclined with respect to the axial direction. The contact surfaces 121 and 122 are symmetric with respect to the central axis A of the second mold 12.

[0041] The first molds 11L and 11R are cam sliders that move as the second mold 12 is pushed in. Therefore, the distance between the contact surfaces 114 of one of the pair of first molds 11L and the contact surfaces 114 of the other first mold 11R decreases from the top surface 111 side to the bottom surface 112 side corresponding to the width between the contact surfaces 121 and 122 of the second mold 12. The contact surface 114 of the first mold 11L is an inclined surface having substantially the same angle as one of the contact surfaces 121 of the second mold 12. The contact surface 114 of the first mold 11R is an inclined surface having substantially the same angle as the other contact surface 122 of the second mold 12. In the present embodiment, the first molds 11L and 11R are provided symmetrically with respect to the central axis A of the second mold 12.

[0042] The first side surfaces 113 of the first mold 11L and the first side surfaces 113 of the first mold 11R are arranged on both outer sides in the width direction in the mold set 10. In the example of the present embodiment, the distance between the first side surface 113 of the first mold 11L and the first side surface 113 of the first mold 11R is substantially constant in the axial direction.

[0043] [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. 3A to 3F. Although not particularly limited, the metal can to be manufactured is, for example, a battery cell case. The method for manufacturing a metal can according to the present embodiment includes a preparation step and a correction step.

[0044] (Preparation Process) Referring to FIG. 3A, in the preparation process, a material can 20 is prepared. The material can 20 has a bottomed cylindrical shape. The material can 20 includes a peripheral wall 21, a bottom plate 22, two first bottom corner portions 23P, and two second bottom corner portions 23Q.

[0045] The peripheral wall 21 has a cylindrical shape. The peripheral wall 21 typically has a polygonal cylindrical shape. In the example of the present embodiment, the peripheral wall 21 has a square cylindrical shape. More specifically, the peripheral wall 21 is a flat square cylindrical shape. The peripheral wall 21 includes a pair of first side walls 211, a pair of second side walls 212, and four side corner portions 213. Each of the first side wall 211 and the second side wall 212 has a substantially flat shape. The pair of first side walls 211 are arranged opposite to each other. The pair of second side walls 212 are arranged opposite to each other. The second side wall 212 is connected to each of the first side walls 211. Each of the side corner portions 213 is disposed between the first side wall 211 and the second side wall 212. The first side wall 211 is connected to each of the second side walls 212 via the side corner portions 213, respectively. The bottom plate 22 closes one axial end of the peripheral wall 21. The material can 20 has an opening 24 at the other axial end of the peripheral wall 21.

[0046] The first bottom corner portion 23P is disposed between each of the first side walls 211 and the bottom plate 22. Each of the first side walls 211 is connected to the bottom plate 22 via the first bottom corner portion 23P. The second bottom corner portion 23Q is disposed between each of the second side walls 212 and the bottom plate 22. Each of the second side walls 212 is connected to the bottom plate 22 via the second bottom corner portion 23Q.

[0047] The material can 20 is formed of a metal plate. The material can 20 is typically formed by deep drawing. The material can 20 may be formed, for example, by subjecting a metal plate to multiple drawing processes (multi-stage drawing).

[0048] In the blank can 20, canning may occur during the forming process. For example, as shown in FIG. 3A, the second side walls 212 of the blank can 20 may bulge outward respectively. In the example of FIG. 3A, the distance between the second side walls 212 increases from the side corner portions 213 toward the central portion. Also, the distance between the second side walls 212 is larger on the opening 24 side compared to the bottom plate 22 side. That is, in the state before correction, the blank can 20 has a mouth-opening shape in which the portion on the opening 24 side is open in the facing direction (arrangement direction) of the second side walls 212 compared to the bottom plate 22 side.

[0049] The metal plate forming the blank can 20 may be a steel plate. The material of the steel plate is preferably carbon steel, but may also be alloy steel or stainless steel, etc. The steel plate may be a plated steel plate or a non-plated steel plate. Alternatively, the blank can 20 may be formed of a metal plate made of, for example, aluminum, titanium, or copper, or an alloy thereof. The material of the metal plate may be an Ni-based alloy, an Al alloy, or a Ti alloy, etc. The blank 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 cell case, the blank can 20 is preferably formed of a plated steel plate, a stainless steel plate, or an Al alloy plate.

[0050] The plate thickness of the blank can 20 is not particularly limited. The plate thickness of the blank can 20 can be appropriately selected according to, for example, the use of the manufactured metal can. When the metal can is a battery cell case, the plate thickness of the blank can 20 is, for example, 0.1 mm or more and 3.0 mm or less. The plate thickness of the blank can 20 does not necessarily have to be constant throughout. For example, the plate thickness may be different between the peripheral wall 21 and the bottom plate 22.

[0051] (Correction process) In the correction process, the blank can 20 is corrected using the mold set 10 to obtain a metal can.

[0052] Referring to FIG. 3B, in the correction process, first, the first molds 11L and 11R of the mold set 10 are placed inside the material can 20. The pair of first molds 11L and 11R are provided corresponding to the pair of first side walls 211. Each first side surface 113 of the first molds 11L and 11R is arranged inside the material can 20 so as to face the first side wall 211 of the material can 20. The first side surface 113 extends from the bottom plate 22 of the material can 20 to at least the opening 24. A part of the first side surface 113 may protrude outward from the opening 24 of the material can 20. At the start point of correcting the material can 20, the first side surface 113 may be non-contact with the first side wall 211 of the material can 20, or may be in contact with the first side wall 211. Each side corner portion 116 (FIG. 1) of the first molds 11L and 11R is arranged corresponding to the side corner portion 213 (FIG. 3A) of the material can 20. Each first bottom corner portion 117P of the first molds 11L and 11R is arranged corresponding to the first bottom corner portion 23P of the material can 20. Although not shown, each second bottom corner portion 117Q (FIG. 1) of the first molds 11L and 11R is arranged corresponding to the second bottom corner portion 23Q (FIG. 3A) of the material can 20.

[0053] Next, the second mold 12 is axially pushed into the space between the first molds 11L and 11R arranged inside the material can 20 from the opening 24 side, so as to separate the first molds 11L and 11R from each other. When the second mold 12 is pushed into the space between the first molds 11L and 11R, the contact surfaces 121 and 122 of the second mold 12 respectively contact the abutted surfaces 114 of the first molds 11L and 11R, and move the first molds 11L and 11R in opposite directions to each other while sliding on the abutted surfaces 114. The first mold 11L moves toward one first side wall 211 side of the material can 20 as the second mold 12 is pushed in. The first mold 11R moves toward the other first side wall 211 side of the material can 20 as the second mold 12 is pushed in. Although not shown, the mold set 10 may be provided with a slide mechanism for smoothly moving the first molds 11L and 11R.

[0054] While separating the first molds 11L and 11R from each other by pushing in the second mold 12, the first molds 11L and 11R are brought into contact with the first side walls 211 of the corresponding material cans 20 by the first side surfaces 113. Thereby, the width between the first side walls 211 is expanded.

[0055] Referring to FIG. 3C, when the second mold 12 is pushed into the space between the first molds 11L and 11R by a predetermined stroke amount, the second mold 12 stops, and the movement of the first molds 11L and 11R also stops. When the movement of the first molds 11L and 11R stops, the first side walls 211 of the material can 20 are in a state substantially parallel to the axial direction along the first side surfaces 113.

[0056] FIG. 3D is an enlarged partial view of the vicinity of the side corner portion 213 of the corrected material can 20. In FIG. 3D, the side corner portion 116 of the first mold 11 and the side corner portion 213 of the material can 20 are shown in a cross section (transverse section) cut perpendicular to the extending direction of the side corner portions 116 and 213. In FIG. 3D, the material can 20 before correction is shown by a two-dot chain line. In order to explain the deformation state of the side corner portion 213 in the correction process, the material can 20 before correction is illustrated such that the inner surface of the first side wall 211 overlaps with the material can 20 after correction.

[0057] Referring to FIG. 3D, in the example of the present embodiment, at the time before correction of the material can 20, in at least a part of the side corner portion 116 of the first mold 11, the radius of curvature Rps of the side corner portion 116 is smaller than the radius of curvature Rcs of the inner surface of the side corner portion 213 of the material can 20 (Rps < Rcs). The radius of curvature Rps is, for example, 70.0% or less of the radius of curvature Rcs, preferably 50.0% or less, more preferably 30.0% or less. The radius of curvature Rps is preferably as small as possible within the range satisfying 0 < Rps < Rcs. The radius of curvature Rps is, for example, 0.2% or more of the radius of curvature Rcs. The radius of curvature Rps may be 0.1 mm or more.

[0058] The radius of curvature Rps of the side corner portion 116 of the first mold 11 is defined as the radius of a circle passing through three points: the R stops on both sides of the side corner portion 116 and the midpoint of the side corner portion 116 in a cross-sectional view. The side corner portion 116 can include one or more regions having the same radius of curvature Rps. In the side corner portion 116, the region having the same radius of curvature Rps can be specified as follows. First, the radius of curvature of the side corner portion 116 is measured at intervals of 5.0 mm in the extending direction of the side corner portion 116. Then, the range of the measurement points arranged in the extending direction of the side corner portion 116, where the difference between the largest radius of curvature and the smallest radius of curvature is 0.2 mm or less, is defined as the region having the same radius of curvature, and the average value of the radii of curvature obtained in this region is defined as the radius of curvature Rps of this region. In the present embodiment, since the radius of curvature Rps is constant in the extending direction of the side corner portion 116, there is only one region having the same radius of curvature Rps in the side corner portion 116. However, there may be a plurality of regions having the same radius of curvature Rps in the side corner portion 116. In this case, adjacent regions may overlap. When there are a plurality of regions having the same radius of curvature Rps in the side corner portion 116, it is sufficient that Rps < Rcs is satisfied in at least one region.

[0059] The radius of curvature Rcs of the inner surface of the side corner portion 213 of the material can 20 before correction is defined as the radius of a circle passing through three points: the R stops 213a, 213b on both sides of the inner surface of the side corner portion 213 and the midpoint of the side corner portion 213 in a cross-sectional view. The inner surface of the side corner portion 213 includes one or more regions having the same radius of curvature Rcs. In the inner surface of the side corner portion 213, the region having the same radius of curvature Rcs can be specified in the same manner as the side corner portion 116.

[0060] Among the side corner portions 116 of the first mold 11, it is preferable that the length in the extending direction of the region satisfying Rps < Rcs is as large as possible. The length of the region satisfying Rps < Rcs is, for example, 30% or more, preferably 50% or more, of the total length of the material can 20 in the extending direction of the side corner portion 116.

[0061] In the correction process, the side corner portion 116 of the first mold 11 contacts the side corner portion 213 of the material can 20 and pushes the side corner portion 213 outward. As a result, in the side corner portion 213 of the material can 20, the corrected line length becomes larger than the line length before correction. Specifically, in a cross-sectional view of the side corner portion 213, the line length from the R stop 213a on the first side wall 211 side of the inner surface of the material can 20 to the R stop 213b on the second side wall 212 side is enlarged. More specifically, in a cross-sectional view, the inner surface of the side corner portion 213 having a substantially arc shape with a radius of curvature Rcs is deformed by the correction into a side corner portion 213 having a substantially arc shape with a radius of curvature Rps smaller than the radius of curvature Rcs and two straight portions 213c and 213d connected to both ends thereof. The radius of curvature of the inner surface of the side corner portion 213 after correction becomes smaller than the radius of curvature Rcs of the inner surface of the side corner portion 213 before correction.

[0062] FIG. 3E is a partially enlarged view of the vicinity of the first bottom corner portion 23P of the material can 20 after correction. In FIG. 3E, a cross-section (cross-section) obtained by cutting the first bottom corner portion 117P of the first mold 11 and the first bottom corner portion 23P of the material can 20 perpendicular to the extending direction of the first bottom corner portions 117P and 23P is shown. In FIG. 3E, as in FIG. 3D, the material can 20 before correction is shown by a two-dot chain line. To explain the deformation state of the first bottom corner portion 23P in the correction process, the material can 20 before correction is illustrated such that the inner surface of the first side wall 211 and the inner surface of the bottom plate 22 overlap the material can 20 after correction.

[0063] Referring to FIG. 3E, in the example of the present embodiment, at the time before correction of the material can 20, in at least a part of the first bottom corner portion 117P of the first mold 11, the radius of curvature Rpb of the first bottom corner portion 117P is smaller than the radius of curvature Rcb of the inner surface of the first bottom corner portion 23P of the material can 20 (Rpb < Rcb). The radius of curvature Rpb is, for example, 70.0% or less of the radius of curvature Rcb, preferably 50.0% or less, more preferably 30.0% or less. The radius of curvature Rpb is preferably as small as possible within the range satisfying 0 < Rpb < Rcb. The radius of curvature Rpb is, for example, 0.2% or more of the radius of curvature Rcb. The radius of curvature Rpb may be 0.1 mm or more.

[0064] The radius of curvature Rpb of the first bottom corner portion 117P of the first mold 11 is defined as the radius of a circle passing through three points, namely, the R stops on both sides of the first bottom corner portion 117P and the midpoint of the first bottom corner portion 117P in a cross-sectional view. The first bottom corner portion 117P includes one or more regions having the same radius of curvature Rpb. When there are a plurality of regions having the same radius of curvature Rpb in the first bottom corner portion 117P, it is sufficient that Rpb < Rcb is satisfied in at least one region. The region having the same radius of curvature Rpb in the first bottom corner portion 117P can be specified in the same manner as the side corner portion 116 (FIGS. 1 and 3D) of the first mold 11.

[0065] The radius of curvature Rcb of the inner surface of the first bottom corner portion 23P of the stock can 20 before correction is defined as the radius of a circle passing through three points, namely, the R stops 23a and 23b on both sides of the inner surface of the first bottom corner portion 23P and the midpoint of the first bottom corner portion 23P in a cross-sectional view. The inner surface of the first bottom corner portion 23P includes one or more regions having the same radius of curvature Rcb. In the inner surface of the first bottom corner portion 23P, the region having the same radius of curvature Rcb can be specified in the same manner as the side corner portion 116 (FIGS. 1 and 3D) of the first mold 11.

[0066] Of the first bottom corner portion 117P of the first mold 11, the length in the extending direction of the region satisfying Rpb < Rcb is preferably as large as possible. The length of the region satisfying Rpb < Rcb is, for example, 30% or more, preferably 50% or more, of the total length of the stock can 20 in the extending direction of the first bottom corner portion 117P.

[0067] The second bottom corner portion 117Q (FIG. 1) of the first mold 11 and the second bottom corner portion 23Q (FIG. 3A) of the blank can have the same relationship as the first bottom corner portion 117P of the first mold 11 and the first bottom corner portion 23P of the blank can. That is, regarding the first bottom corner portions 117P and 23P, in the above description with reference to FIG. 3E, the first bottom corner portion 117P can be read as the second bottom corner portion 117Q, and the first bottom corner portion 23P can be read as the second bottom corner portion 23Q. In this case, the first side wall 211 can be read as the second side wall 212 (FIGS. 3A and 3D).

[0068] In the correction process, the first bottom corner portion 117P of the first mold 11 contacts the first bottom corner portion 23P of the blank and presses the first bottom corner portion 23P outward. As a result, in the first bottom corner portion 23P of the blank, the line length after correction becomes larger than the line length before correction. Specifically, in a cross-sectional view of the first bottom corner portion 23P, the line length from the R stop 23a on the first side wall 211 side of the inner surface of the blank to the R stop 23b on the bottom plate 22 side is enlarged. More specifically, in a cross-sectional view, the inner surface of the first bottom corner portion 23P having a substantially arc shape with a radius of curvature Rcb is deformed by the correction into a first bottom corner portion 23P having a substantially arc shape with a radius of curvature Rpb smaller than the radius of curvature Rcb and two straight portions 23c and 23d connected to both ends thereof. The radius of curvature of the inner surface of the first bottom corner portion 23P after correction becomes smaller than the radius of curvature Rcb of the inner surface of the first bottom corner portion 23P before correction.

[0069] Similarly, in the correction process, the second bottom corner portion 117Q (FIG. 1) of the first die 11 contacts the second bottom corner portion 23Q (FIG. 3A) of the blank can 20 and presses and expands the second bottom corner portion 23Q outward. As a result, in the second bottom corner portion 23Q of the blank can 20, the corrected line length becomes larger than the line length before correction. Specifically, in a cross-sectional view of the second bottom corner portion 23Q, the line length from the R stop on the second side wall 212 (FIGS. 3A and 3D) side of the inner surface of the blank can 20 to the R stop on the bottom plate 22 side is expanded. More specifically, in a cross-sectional view, the inner surface of the second bottom corner portion 23Q having a substantially arc shape with a curvature radius Rcb is deformed by the correction into a second bottom corner portion 23Q having a substantially arc shape with a curvature radius Rpb smaller than the curvature radius Rcb and two straight portions connected to both ends thereof. The curvature radius of the inner surface of the second bottom corner portion 23Q after correction becomes smaller than the curvature radius Rcb of the inner surface of the second bottom corner portion 23Q before correction.

[0070] Thereafter, the first die 11 and the second die 12 are removed from the blank can 20. At this time, the blank can 20 has an expanded width between the first side walls 211 at least on the bottom plate 22 side as compared with before correction. Through such a correction process, as shown in FIG. 3F, a bottomed cylindrical metal can 30 is manufactured.

[0071] [Effect] In the present embodiment, in the correction process of the blank can 20, the first side walls 211 of the blank can 20 are pressed and expanded in the width direction by the first dies 11L and 11R. Thereby, for example, the residual stress of the peripheral wall 21 when the blank can 20 is formed by deep drawing can be relaxed, and the canning of the peripheral wall 21 generated during the forming of the blank can 20 can be reduced.

[0072] In the manufacturing method according to this embodiment, in the correction process, each side corner portion 116 of the first molds 11L and 11R contacts the side corner portion 213 of the material can 20 and pushes the side corner portion 213 outward. The radius of curvature Rps of each side corner portion 116 of the first molds 11L and 11R is smaller than the radius of curvature Rcs of the inner surface of the side corner portion 213 of the material can 20. Therefore, the side corner portion 213 of the material can 20 is formed so that its radius of curvature becomes smaller than the radius of curvature Rcs before the correction process. As a result, in a cross-sectional view of the side corner portion 213, the linear length from the R stop 213a on the first side wall 211 side to the R stop 213b on the second side wall 212 side of the inner surface of the material can 20 is enlarged compared to before the correction. As a result, the material can flow from the second side wall 212 of the material can 20 toward the side corner portion 213. Further, when the linear length from the R stop 213a to the R stop 213b is enlarged, since the material extends in the circumferential direction of the material can 20, a circumferential tension is generated in the material can 20. As a result, the bulge of the second side wall 212 of the material can 20 (metal can 30) after the correction is reduced. Therefore, the dimensional accuracy of the metal can 30 can be further improved.

[0073] Also, in the manufacturing method according to the present embodiment, in the correction step, the bottom corner portions 117P and 117Q of each of the first molds 11L and 11R come into contact with the bottom corner portions 23P and 23Q of the material can 20, and push the bottom corner portions 23P and 23Q outward respectively. The radius of curvature Rpb of each of the bottom corner portions 117P and 117Q of the first molds 11L and 11R is smaller than the radius of curvature Rcb of the inner surfaces of the bottom corner portions 23P and 23Q of the material can 20 respectively. Therefore, the bottom corner portions 23P and 23Q of the material can 20 are formed such that their radius of curvature becomes smaller than the radius of curvature Rcb before the correction step. As a result, in a cross-sectional view of the first bottom corner portion 117P, the linear length from the R stop 23a on the first side wall 211 side to the R stop 23b on the bottom plate 22 side of the inner surface of the material can 20 is enlarged compared to before the correction. Similarly, in a cross-sectional view of the second bottom corner portion 117Q, the linear length from the R stop on the second side wall 212 side to the R stop on the bottom plate 22 side of the inner surface of the material can 20 is enlarged compared to before the correction. As a result, the material can be made to flow from the side walls 211 and 212 of the material can 20 toward the bottom plate 22. Thereby, the dimensional accuracy of the metal can 30 can be further improved.

[0074] In the example of this embodiment, the radius of curvature Rps of the side corner portion 116 of the first mold 11 is constant in its extending direction. Also, the side corner portion 116 can have a radius of curvature Rps that is smaller than the radius of curvature Rcs of the inner surface of the side corner portion 213 of the stock can 20 throughout. However, the radius of curvature Rps of the side corner portion 116 may vary in the extending direction. Even when the radius of curvature Rps varies in the extending direction, the side corner portion 116 has a radius of curvature Rps that is smaller than the radius of curvature Rcs of the inner surface of the side corner portion 213 of the stock can 20 at least in part. In this case, the radius of curvature Rps in a partial region of the side corner portion 116 may be smaller than the radius of curvature Rcs, and the radius of curvature Rps in other regions of the side corner portion 116 may be substantially equal to the radius of curvature Rcs. From the viewpoint of suppressing canning at the opening 24 of the stock can 20, it is preferable that the side corner portion 116 has a radius of curvature Rps that is smaller than the radius of curvature Rcs in the portion on the opening 24 side. That is, in the side corner portion 116, the region having a radius of curvature Rps that is smaller than the radius of curvature Rcs of the inner surface of the side corner portion 213 of the stock can 20 is preferably provided on the opening 24 side of the stock can 20. In this case, the dimensional accuracy of the obtained metal can 30 can be further improved, and the opening of the stock can 20 can be reduced. Note that the portion on the opening 24 side means the range of the side corner portion 116 that is on the opening 24 side of the central position in the axial direction of the stock can 20.

[0075] In the example of this embodiment, the radius of curvature Rpb of the bottom corner portions 117P and 117Q of the first mold 11 is constant in its extending direction. Also, the bottom corner portions 117P and 117Q can have a radius of curvature Rps that is smaller than the radius of curvature Rcs of the inner surfaces of the bottom corner portions 23P and 23Q of the material can 20 over the entire length. However, the radius of curvature Rpb of the bottom corner portions 117P and 117Q of the first mold 11 may also vary in the extending direction. Even when the radius of curvature Rpb varies in the extending direction, the bottom corner portions 117P and 117Q have a radius of curvature Rpb that is smaller than the radius of curvature Rcb of the inner surfaces of the bottom corner portions 23P and 23Q of the material can 20 at least in part. In this case, the radius of curvature Rpb in a part of the region of the bottom corner portions 117P and 117Q may be smaller than the radius of curvature Rcb, and the radius of curvature Rpb in the other regions of the bottom corner portions 117P and 117Q may be substantially equal to the radius of curvature Rcb.

[0076] <Second Embodiment> FIG. 4 is a perspective view schematically showing the first mold 11 included in the mold set according to the second embodiment. As shown in FIG. 4, the first mold 11 of this embodiment is different from the first mold 11 of the first embodiment in that it further includes a chamfered surface 118. The second mold (not shown) of the mold set according to this embodiment has the same configuration as the second mold 12 of the first embodiment.

[0077] The chamfered surface 118 is provided between the side corner portion 116 and the bottom surface 112 of the first mold 11. The chamfered surface 118 is, for example, an inclined surface that is inclined with respect to the axial direction. The chamfered surface 118 may have a substantially constant gradient. In the example of FIG. 4, the chamfered surface 118 is inclined such that the end on the bottom surface 112 side is located more inward in the width direction than the end on the top surface 111 side. In the example of this embodiment, the chamfered surface 118 is connected to the two side corner portions 116. The chamfered surface 118 extends along the first bottom corner portion 117P adjacent to the bottom surface 112. The chamfered surface 118 is connected to the bottom surface 112 via the first bottom corner portion 117P. The chamfered surface 118 is also connected to the first side surface 113.

[0078] However, the configuration of the chamfered surface 118 is not limited to the example shown in FIG. 4. FIG. 5 is a perspective view showing a modification of the first mold 11 included in the mold set according to the second embodiment. In the example shown in FIG. 5, two chamfered surfaces 118 are provided corresponding to each of the two side corner portions 116. The chamfered surfaces 118 are formed on both sides in the depth direction in the first mold 11 and are respectively connected to the side corner portions 116. The chamfered surfaces 118 are respectively connected to the first side surface 113, the bottom surface 112, and the second side surface 115. In this case, the first bottom corner portion 117P is located between the chamfered surfaces 118 in the depth direction.

[0079] In the first mold 11 of the mold set according to the present embodiment, a chamfered surface 118 is provided between the side corner portion 116 and the bottom surface 112. The chamfered surface 118 is configured such that the end on the bottom surface 112 side is located more inward in the width direction than the end on the top surface 111 side. Therefore, when the first mold 11 is disposed in the material can 20 (FIGS. 3A to 3E) in the correction process, the distance between the chamfered surface 118 and the first side wall 211 of the material can 20 becomes larger on the bottom plate 22 side. Thereby, in the correction process, the portion of the material can 20 on the bottom plate 22 side, particularly the corner between the side corner portion 213 and the bottom plate 22, is less likely to come into contact with the first mold 11. As a result, deformation of the corner of the material can 20 is suppressed, and breakage of the corner is less likely to occur. Therefore, according to the mold set according to the present embodiment, the formability of the material can 20 is likely to be improved.

[0080] <Third Embodiment> FIG. 6 is a longitudinal sectional view schematically showing a mold set 10A according to the third embodiment. As shown in FIG. 6, the mold set 10A according to the present embodiment is different from the mold set 10 according to the first embodiment in the shape of the first side surface 113 of the first mold 11.

[0081] Referring to FIG. 6, the first side surface 113 of the first mold 11 is formed such that the portion on the opening 24 (FIGS. 3A to 3C) side is located outside in the width direction with respect to the portion on the bottom plate 22 (FIGS. 3A to 3C and 3E) side. In the example of the present embodiment, the first side surface 113 is an inclined surface with respect to the axial direction and has a substantially constant gradient. The distance between the first side surface 113 of the first mold 11L and the first side surface 113 of the first mold 11R is larger on the top surface 111 side than on the bottom surface 112 side.

[0082] FIGS. 7A to 7C are schematic views for explaining a method of manufacturing the metal can 30 using the mold set 10A according to the third embodiment. With reference to FIGS. 7A to 7C, a method of manufacturing the metal can 30 using the mold set 10A will be described.

[0083] As shown in FIG. 7A, in the raw material can 20 before correction, due to springback when being formed, the first side wall 211 may be inclined inward of the raw material can 20. In this case, referring to FIG. 7A, in the longitudinal sectional view of the raw material can 20, the first side wall 211 is inclined with respect to the axial direction such that the end on the opening 24 side of the raw material can 20 is located inside the end on the bottom plate 22 side. On the other hand, the first side surface 113 of the first mold 11 is formed such that the portion on the opening 24 side is located outside in the width direction with respect to the portion on the bottom plate 22 side. Therefore, before the start of correction, the interval in the width direction between the first side wall 211 of the raw material can 20 and the first side surface 113 of the first mold 11 is small on the opening 24 side of the raw material can 20 and large on the bottom plate 22 side. At the start of the correction process, the first side surface 113 of the first mold 11 may be in contact with the first side wall 211 of the raw material can 20 on the opening 24 side, but is not in contact on the bottom plate 22 side.

[0084] Referring to FIG. 7B, while separating the first mold 11 by pushing in the second mold 12, by bringing the first side surface 113 of the first mold 11 into contact with the first side wall 211 of the raw material can 20 respectively, the width between the first side walls 211 is expanded. At that time, the first side surface 113 of the first mold 11 presses and expands the raw material can 20 in the width direction while sequentially contacting the first side wall 211 from the opening 24 side toward the bottom plate 22 side.

[0085] Referring to FIG. 7C, the first side wall 211 of the material can 20 is formed by the contact of the first mold 11 such that the end portion of the material can 20 on the opening 24 side is located outside the end portion on the bottom plate 22 side. In the example of the present embodiment, the first side wall 211 is tilted outward of the material can 20 by the first mold 11. More specifically, when the first side surfaces 113 of the first mold 11 are in overall contact with the first side wall 211 respectively, the first side wall 211 is inclined with respect to the axial direction of the material can 20 along the first side surface 113.

[0086] In this case, even if springback of the first side wall 211 occurs when the first mold 11 is separated from the first side wall 211, the first side wall 211 is likely to be in a state parallel or nearly parallel to the axial direction of the material can 20. As a result, the dimensional difference between the opening 24 side and the bottom plate 22 side with respect to the width between the first side walls 211 of the corrected material can 20 (metal can 30) is reduced, and the dimensional accuracy of the metal can 30 can be further improved.

[0087] In the present embodiment, the entire first side surface 113 of the first mold 11 is an inclined surface. However, the shape of the first side surface 113 is not limited to the example of the present embodiment. The first side surface 113 may have a convex curved shape outward in the width direction. Further, the first side surface 113 can 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.

[0088] In the example shown in FIGS. 7A to 7C, in the correction process of the material can 20, the first side surface 113 of the first mold 11 contacts the first side wall 211 of the material can 20 substantially over the entire surface. However, the first side surface 113 of the first mold 11 does not necessarily need to contact the first side wall 211 over the entire surface. For example, the first side surface 113 of the first mold 11 may contact only the region of the first side wall 211 on the opening 24 side.

[0089] <Fourth Embodiment> FIG. 8 is a longitudinal sectional view schematically showing a mold set 10B according to the fourth embodiment. As shown in FIG. 8, the mold set 10B according to the present embodiment is different from the mold set 10 according to the first embodiment in that it further includes a pair of pads 13.

[0090] Referring to FIG. 8, in the correction process of the material can 20, the first mold 11 is disposed inside the material can 20, while the pads 13 are disposed outside the material can 20. The pads 13 are provided in the mold set 10B corresponding to the first mold 11, respectively.

[0091] The pad 13 includes a pressing surface 131. The pressing surface 131 is a surface corresponding to the first side surface 113 of the first mold 11. The pressing surface 131 is configured to be able to sandwich the first side wall 211 of the material can 20 together with the first side surface 113 of the first mold 11. That is, at least a part of the pressing surface 131 has a shape corresponding to the first side surface 113 of the first mold 11. In the example of the present embodiment, substantially the entire pressing surface 131 has a shape corresponding to the first side surface 113 of the first mold 11. Specifically, the pressing surface 131 is substantially parallel to the axial direction as a whole, similar to the first side surface 113 of the first mold 11. However, as described in the third embodiment, when the first side surface 113 includes an inclined surface or a curved surface, the pressing surface 131 also has an inclined shape or a curved shape accordingly.

[0092] In the correction process of the material can 20, the regions of the first side wall 211 of the material can 20 that contact the first mold 11 are each pressed by the pads 13 from the outside of the material can 20. More specifically, when the first mold 11 is separated and the first side wall 211 is expanded by the pushing of the second mold 12, each of the first side walls 211 is sandwiched by the first side surface 113 of the first mold 11 and the pressing surface 131 of the pad 13.

[0093] In the present embodiment, substantially the entire first side wall 211 is pressed from the inside and outside of the material can 20 by the first mold 11 and the pads 13. The pad 13 may move in the width direction together with the first mold 11 until the first mold 11 stops while pressing the first side wall 211.

[0094] In this embodiment, in the correction process of the material can 20, the regions of the first side wall 211 of the material can 20 that come into contact with the first mold 11 are pressed by the pads 13 from the outside of the material can 20, respectively. Therefore, with the first side wall 211 being clamped from both the inside and outside of the material can 20, the width between the first side walls 211 is increased. As a result, it becomes easier to ensure the shape accuracy of the first side wall 211.

[0095] As described in the third embodiment, even when the first side surface 113 of the first mold 11 contacts only the region of the first side wall 211 on the opening 24 side, the pads 13 can be used in the correction process of the material can 20. In this case, the pads 13 also contact the material can 20 from the outside only in the region of the first side wall 211 on the opening 24 side. It is preferable that the pads 13 do not contact the regions of the first side wall 211 of the material can 20 that are not contacted by the first side surface 113 of the first mold 11.

[0096] 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 can be made without departing from the spirit thereof.

[0097] In each of the above-described embodiments, at the time before correcting the material can 20, the radius of curvature Rps of the side corner portion 116 of the first mold 11 is smaller than the radius of curvature Rcs of the inner surface of the side corner portion 213 of the material can 20, and the radius of curvature Rpb of the bottom corner portions 117P and 117Q of the first mold 11 is smaller than the radius of curvature Rcb of the inner surface of the bottom corner portions 23P and 23Q of the material can 20. However, it is sufficient that at least one of the corner portions of the side corner portion 116, the first bottom corner portion 117P, and the second bottom corner portion 117Q of the first mold 11 has a radius of curvature smaller than the radius of curvature of the inner surface of the corresponding corner portion of the material can 20 at least in part. For example, while the side corner portion 116 of the first mold 11 has a radius of curvature Rps smaller than the radius of curvature Rcs of the inner surface of the side corner portion 213 of the material can 20, the radius of curvature Rpb of the bottom corner portions 117P and 117Q of the first mold 11 may be substantially equal to the radius of curvature Rcb of the inner surface of the bottom corner portions 23P and 23Q of the material can 20. In this case, in the step of correcting the material can 20, at least the side corner portion 116 of the first mold 11 contacts the side corner portion 213 of the material can 20 at a portion having a radius of curvature Rps smaller than the radius of curvature Rcs of the side corner portion 213 of the material can 20. Similarly, either one of the bottom corner portions 117P and 117Q of the first mold 11 may have a radius of curvature Rpb smaller than the radius of curvature Rcb of the inner surface of the corresponding bottom corner portion of the material can 20. At this time, the radius of curvature Rpb of the other of the bottom corner portions 117P and 117Q of the first mold 11 is, for example, substantially equal to the radius of curvature Rcb of the inner surface of the corresponding bottom corner portion of the material can 20. Further, the radius of curvature Rps of the side corner portion 116 of the first mold 11 may be substantially equal to the radius of curvature Rcs of the inner surface of the side corner portion 213 of the material can 20. In this case, in the step of correcting the material can 20, at least either one of the bottom corner portions 117P and 117Q of the first mold 11 contacts the corresponding bottom corner portion of the material can 20 at a portion having a radius of curvature Rpb smaller than the radius of curvature Rcb of the corresponding bottom corner portion of the material can 20.

[0098] In each of the above embodiments, an example of the shape of the second mold 12 was presented. However, the shape of the second mold 12 is not limited to the examples in the above embodiments. In each of the above embodiments, the second mold 12 had a trapezoidal shape in a longitudinal cross-sectional view or a front view. However, for example, as shown in FIG. 9, the second mold 12 may have a triangular shape in a longitudinal cross-sectional view or a front view.

[0099] Similarly, the first mold 11 is not limited to the examples in the above embodiments and can have various shapes. For example, in the first mold 11, a part of the side surface arranged on the second mold 12 side may be an inclined contact surface 114 as in the above embodiments, or substantially the entire side surface arranged on the second mold 12 side may be an inclined contact surface 114 as shown in FIG. 10.

[0100] The first mold 11 may include a recessed portion 119 as shown in FIG. 11. The recessed portion 119 is provided, for example, on the first side surface 113 side of the first mold 11 and has a shape that is concave inward in a longitudinal cross-sectional view. In this case, the first side surface 113 is arranged above and below the recessed portion 119. When correcting the material can 20 using the mold set including the first mold 11 shown in FIG. 11, the first side surface 113 contacts the first side wall 211 of the material can 20, and the recessed portion 119 does not contact the first side wall 211. The recessed portion 119 extends, for example, over the entire depth direction. In this case, the side corner portion 116 (FIG. 1) of the first mold 11 is divided vertically by the recessed portion 119. However, the recessed portion 119 may be provided only in a part in the depth direction. In this case, the side corner portion 116 of the first mold 11 extends over the entire axial direction of the material can 20 without being divided. In any case, the side corner portion 116 of the first mold 11 can have a curvature radius Rps that is smaller than the curvature radius Rcs of the inner surface of the side corner portion 213 of the material can 20 at least in part, similar to the above embodiments.

[0101] In each of the above embodiments, in a longitudinal cross-sectional view or a front view of the first mold 11, the first side surface 113 of the first mold 11L and the first side surface 113 of the first mold 11R have symmetrical shapes. It is preferable that the first side surface 113 of the first mold 11L and the first side surface 113 of the first mold 11R have symmetrical shapes, but slight differences in shape or dimensions are allowed. The first side surface 113 of the first mold 11 only needs to be able to substantially or approximately push and expand the first side wall 211 of the material can 20 in the width direction.

[0102] Similarly, the abutted surfaces 114 of the first mold 11L and the abutted surfaces 114 of the first mold 11R preferably have symmetrical shapes in a longitudinal cross-sectional view or a front view of the first mold 11, but may have slightly asymmetrical shapes. The abutting surfaces 121, 122 of the second mold 12 are respectively shaped to correspond to the abutted surfaces 114 of the first mold 11.

[0103] In each of the above embodiments, the second mold 12 is pushed between the first molds 11 at a position in the center of the material can 20 in the width direction. However, the second mold 12 may be pushed between the first molds 11 at a position shifted to one of the first side wall 211 sides from the center in the width direction of the material can 20. If the stroke amounts of the first molds 11 due to the pushing of the second mold 12 are substantially the same, the position where the second mold 12 is pushed is not particularly limited. The abutted surfaces 114 of the first mold 11 are arranged at positions corresponding to the second mold 12.

Example

[0104] 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.

[0105] To confirm the effects of the present disclosure, an analysis by the finite element method (FEM analysis) was performed on the correction of a material can using a mold set having the same shape as the mold set 10B (FIG. 8) including the pair of pads 13 described in the fourth embodiment (Examples 1 to 9). At all side corner portions of the first mold, the radius of curvature Rps was set as shown in Table 1. Each radius of curvature Rps of the side corner portion was constant in its extending direction. At all bottom corner portions (the first bottom corner portion and the second bottom corner portion) of the first mold, the radius of curvature Rpb was set as shown in Table 1. As a comparative example, the radius of curvature Rps of the side corner portion of the first mold was made the same as the radius of curvature Rcs of the side corner portion of the material can, and the radius of curvature Rpb of the bottom corner portion of the first mold was made the same as the radius of curvature Rcb of the bottom corner portion of the material can. The same analysis was also performed on the correction of the material can carried out in the same manner as in Examples 1 to 9 except for this. The basic conditions of the analysis are as follows. · Inner dimensions of the material can (before springback) - Bottom plate: width 147.72 mm × depth 26.25 mm - Opening: width 147.67 mm × depth 26.26 mm - Height: 108 mm · Material of the material can: IF steel · Plate thickness of the material can: 0.3 mm · Chamfered surface of the first mold: None

[0106] In this analysis, the influence of the size relationship between the radius of curvature of the side corner portion and the bottom corner portion of the first mold and the inner surface radius of curvature of the corresponding corner portion of the material can on the canning amount of the material can was investigated. The canning amount is the difference between the distance between the second side walls measured at a position 91 mm in the axial direction from the bottom plate and the distance between the second side walls measured at a position 10 mm in the axial direction from the bottom plate for the metal can obtained by correcting the material can. The distance between the second side walls is the dimension in the depth direction of the metal can. In the correction in this analysis, the side corner portion of the first mold was brought into contact with the side corner portion of the material can, and the bottom corner portion of the first mold was brought into contact with the bottom corner portion of the material can. The analysis conditions and results are shown in Table 1.

[0107]

Table 1

[0108] Referring to Table 1, in Examples 1 to 3, the radius of curvature Rps of the side corner portion of the first mold was smaller than the radius of curvature Rcs of the inner surface of the side corner portion of the material can. In Examples 4 to 6, the radius of curvature Rpb of the bottom corner portion of the first mold was smaller than the radius of curvature Rcb of the inner surface of the bottom corner portion of the material can. In Examples 7 to 9, the radii of curvature Rps and Rpb of the side corner portion and the bottom corner portion of the first mold, respectively, were smaller than the radii of curvature Rcs and Rcb of the inner surface of the corresponding corner portion of the material can. In the comparative example, the radii of curvature Rps and Rpb of the side corner portion and the bottom corner portion of the first mold, respectively, were the same as the radii of curvature Rcs and Rcb of the inner surface of the corresponding corner portion of the material can.

[0109] In Table 1, Rps / Rcs means the ratio (%) of the radius of curvature Rps of the side corner portion of the first mold to the radius of curvature Rcs of the inner surface of the side corner portion of the material can. Similarly, Rpb / Rcb means the ratio (%) of the radius of curvature Rpb of the bottom corner portion of the first mold to the radius of curvature Rcb of the inner surface of the bottom corner portion of the material can. Also, in Table 1, the canning amount is shown as the ratio (%) to the canning amount in the comparative example.

[0110] In Examples 1 to 9, the canning amount was reduced compared to the comparative example in all cases. From this, it was confirmed that by making the radius of curvature of each corner portion of the first mold smaller than the radius of curvature of the inner surface of the corresponding corner portion of the material can (Rps < Rcs and / or Rpb < Rcb), the canning amount of the corrected metal can can be reduced.

[0111] When comparing Examples 1 to 3 with Examples 4 to 6, the canning amount could be reduced more in Examples 1 to 3. From this, it can be seen that by making the radius of curvature Rps of the side corner portion of the first mold smaller than the radius of curvature Rcs of the inner surface of the side corner portion of the material can (Rps < Rcs), the canning amount can be reduced more effectively. From the results shown in Examples 1 to 3, it can be said that the smaller the radius of curvature Rps of the side corner portion of the first mold is with respect to the radius of curvature Rcs of the inner surface of the side corner portion of the material can, the lower the canning amount.

Explanation of Signs

[0112] 10, 10A, 10B: Mold set 11: First mold 111: Top surface 112: Bottom surface 113: First side surface 114: Contact surface 115: Second side surface 116: Side corner portion 117P: First bottom corner portion 117Q: Second bottom corner portion 12: Second mold 121, 122: Contact surfaces 13: Pad 20: Material can 21: Peripheral wall 211: First side wall 212: Second side wall 213: Side corner portion 22: Bottom plate 23P: First bottom corner portion 23Q: Second bottom corner portion 24: Opening 30: Metal can

Claims

1. A method for manufacturing a metal can, comprising: a cylindrical peripheral wall including a pair of first side walls arranged opposite to each other, a second side wall connected to each of the first side walls, and side corner portions arranged between each of the first side walls and the second side wall; a bottom plate closing one axial end of the peripheral wall; a first bottom corner portion arranged between each of the first side walls and the bottom plate; and a second bottom corner portion arranged between the second side wall and the bottom plate, 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 provided corresponding to the pair of first side walls and a second mold, and correcting the blank can to obtain a metal can; comprising: each of the first molds includes a first side surface, a second side surface connected to the first side surface, a side corner portion arranged between the first side surface and the second side surface, a bottom surface connected to the first side surface and the second side surface, a first bottom corner portion arranged between the first side surface and the bottom surface, and a second bottom corner portion arranged between the second side surface and the bottom surface; in the step of correcting the blank can, while pushing the second mold axially from the opening side between the first molds arranged in the blank can to separate the first molds from each other, bringing each of the first molds into contact with the corresponding first side wall with the first side surface, and bringing at least one corner portion of each of the side corner portions, the first bottom corner portion, and the second bottom corner portion of the first mold into contact with the corresponding corner portion of the side corner portion, the first bottom corner portion, and the second bottom corner portion of the blank can, thereby expanding the width between the first side walls; wherein at least a part of each of the at least one corner portion of the first mold has a radius of curvature smaller than the radius of curvature of the inner surface of the corresponding corner portion of the blank can.

2. The manufacturing method according to claim 1, wherein: in the step of correcting the blank can, each of the side corner portions of the first mold contacts the side corner portion of the blank can. The manufacturing method is such that each of the side corner portions of the first mold has a radius of curvature smaller than the radius of curvature of the inner surface of the side corner portion of the material can at least in part.

3. The manufacturing method according to claim 2, The manufacturing method is such that each of the side corner portions of the first mold has a radius of curvature smaller than the radius of curvature of the inner surface of the side corner portion of the material can in the portion on the opening side.

4. The manufacturing method according to claim 1, In the step of correcting the material can, each of the first bottom corner portions of the first mold contacts the first bottom corner portion of the material can, The manufacturing method is such that each of the first bottom corner portions of the first mold has a radius of curvature smaller than the radius of curvature of the inner surface of the first bottom corner portion of the material can at least in part.

5. The manufacturing method according to any one of claims 1 to 4, In the step of correcting the material can, each of the second bottom corner portions of the first mold contacts the second bottom corner portion of the material can, The manufacturing method is such that each of the second bottom corner portions of the first mold has a radius of curvature smaller than the radius of curvature of the inner surface of the second bottom corner portion of the material can at least in part.

6. The manufacturing method according to claim 1, Each of the first molds further includes a chamfered surface provided between the side corner portion and the bottom surface.

7. The manufacturing method according to claim 1, The first side surface is formed such that the portion on the opening side is located outside in the separating direction of the first mold with respect to the portion on the bottom plate side.

8. The manufacturing method according to claim 1, In the step of correcting the material can, the regions of the first side wall that contact the first mold are each pressed by pads from the outside of the material can. Manufacturing method.

9. A mold set used for manufacturing a metal can from a material can, A top surface, a bottom surface disposed on the opposite side of the top surface, a first side surface connecting the top surface and the bottom surface, a contact surface disposed on the opposite side of the first side surface, a second side surface connecting the first side surface and the contact surface, a side corner portion disposed between the first side surface and the second side surface, a first bottom corner portion disposed between the first side surface and the bottom surface, and a second bottom corner portion disposed between the second side surface and the bottom surface. A pair of first molds each including, A pair of contact surfaces for contacting each of the contact surfaces of the first mold, and a second mold configured such that the width between the contact surfaces decreases from one end side in the axial direction to the other end side. Comprising The distance between the contact surface of one of the pair of first molds and the contact surface of the other first mold decreases from the top surface side to the bottom surface side corresponding to the width between the contact surfaces. At least one of the side corner portion, the first bottom corner portion, and the second bottom corner portion corresponds to a corner portion provided on the material can and has a radius of curvature smaller than the radius of curvature of the inner surface of the corresponding corner portion in at least a part thereof. Mold set.

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