Square can manufacturing method and square can manufacturing device

Abstract

The invention provides a square can manufacturing method and a square can manufacturing device, which can suppress the occurrence of uneven wall thickness of long side walls without increasing the manufacturing cost. A method for manufacturing a square can includes a drawing and thinning step for performing drawing and thinning processing on a cylindrical portion predetermined portion of an intermediate molded article, and a die and a punch are formed in such a manner that the punch is inserted into a die processing through hole (41a) in a non-loaded state, and the die processing through hole (41a) is inserted into the die processing through hole (41a) in a non-loaded state. A short-side-direction interval (W1) between a long-side-direction center portion of the punch long-side-wall processing portion (42b) and the die long-side-wall processing portion (41c) is narrower than a short-side-direction interval (W2) between two long-side-direction end portions of the punch long-side-wall processing portion (42b) and the die long-side-wall processing portion (41c).

Description

Technical Field

[0001] The present invention relates to a square can manufacturing method and a square can manufacturing device for forming a square can, and in particular to a square can manufacturing method and a square can manufacturing device for a square can used as a shell of a lithium ion battery. Background Art

[0002] Conventionally, as a method for manufacturing a metal square can having a bottom wall and a square cylindrical portion, there is known a method for manufacturing a square can by subjecting a blank to multiple drawing processes or deep drawing and thinning processes (for example, refer to Patent Document 1). Furthermore, it is also known that in the deep drawing and thinning process performed as the final step of such drawing or deep drawing and thinning processes, a punch having a punch processing an outer peripheral surface formed with a roughly rectangular cross-sectional shape and a die having a die processing a through hole formed with a roughly rectangular cross-sectional shape are used in consideration of the outer dimensions, inner dimensions and other shapes of the square cylindrical portion of the final molded product.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-51575 Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, in the square can formed in this way, the applicant has confirmed that when the flatness (ratio of the long side dimension to the short side dimension) of the square cylindrical portion of the square can to be manufactured is high, uneven wall thickness will occur on the long side wall of the square cylindrical portion.

[0008] When a square can is used for a lithium ion battery case or the like which requires a high degree of shape accuracy, such unevenness in the wall thickness of the square cylindrical portion may not be tolerated depending on the intended use of the square can.

[0009] Therefore, the present invention solves these problems, and its object is to provide a square can manufacturing method and square can manufacturing device that can suppress the uneven thickness of the long side walls with a simple structure without increasing the manufacturing cost.

[0010] Solutions for solving problems

[0011] The square can manufacturing method of the present invention is a square can manufacturing method for manufacturing a square can, the square can having: a bottom wall; and a square cylindrical portion, having a pair of long side walls and a pair of short side walls, which can solve the above problem by the following contents, that is, the square can manufacturing method comprises: a drawing and thinning process, the drawing and thinning process is performed on a predetermined portion of the cylindrical portion of the intermediate molded product through a gap between a die-processed inner peripheral surface of a die-processed through hole formed in the die and a punch-processed outer peripheral surface formed on a punch inserted into the die-processed through hole, the die-processed inner peripheral surface being formed to form a gap between the punch-processed outer peripheral surface of the punch inserted into the die-processed through hole, The surface has a die long side wall processing portion for processing the predetermined portion of the long side wall of the intermediate molded product, and the punch processing outer peripheral surface has a punch long side wall processing portion for processing the predetermined portion of the long side wall. The die and the punch are formed as follows: when the punch is inserted into the die processing through hole in a no-load state, the short side direction interval between the central portion of the punch long side wall processing portion and the die long side wall processing portion is narrower than the short side direction interval between the two end portions of the punch long side wall processing portion and the die long side wall processing portion.

[0012] The square can manufacturing device of the present invention is a square can manufacturing device for manufacturing square cans, the square can comprising: a bottom wall; and a square cylindrical portion having a pair of long side walls and a pair of short side walls, which can solve the above problem by the following contents, namely, the square can manufacturing device comprises: a drawing and thinning unit, which performs drawing and thinning processing on a predetermined portion of the cylindrical portion of the intermediate molded product through a gap between a die-processed inner peripheral surface of a die-processed through hole formed in the die and a punch-processed outer peripheral surface of a punch formed in the punch-processed through hole, the die-processed inner peripheral surface having a pair of The die comprises a long side wall processing portion for processing the predetermined portion of the long side wall of the intermediate molded product, the punch processing outer peripheral surface comprises a punch long side wall processing portion for processing the predetermined portion of the long side wall, and the die and the punch are formed so that when the punch is inserted into the die processing through hole in a no-load state, the short side direction interval between the central portion in the long side direction of the punch long side wall processing portion and the die long side wall processing portion is narrower than the short side direction interval between the two end portions in the long side direction of the punch long side wall processing portion and the die long side wall processing portion.

[0013] Effects of the Invention

[0014] According to the present invention, the die and the punch are formed so that when the punch is inserted into the through hole processed by the die in a no-load state, the short-side distance between the central part in the long-side direction of the long-side wall processing part of the punch and the long-side wall processing part of the die is narrower than the short-side distance between the two end parts in the long-side direction of the long-side wall processing part of the punch and the long-side wall processing part of the die. Thus, the unevenness (deviation) in the wall thickness of the long side wall of the formed square can can be suppressed with a simple structure without increasing the manufacturing cost.

[0015] That is, when the flatness (ratio of the long side dimension to the short side dimension) of the through hole processed by the die is high, during the drawing and thinning process, the long side wall processing portion of the die may sometimes bend due to the forming reaction force in a manner such that the central portion in the long side direction of the long side wall processing portion of the die is biased toward the outer side in the short side direction. However, in the present invention, the short side direction interval between the long side wall processing portion of the die and the long side wall processing portion of the punch is set in consideration of the deflection of the long side wall processing portion of the die. Therefore, during the drawing and thinning process in which the long side wall processing portion of the die is deflected due to the forming reaction force, the dimensional difference between the short side direction interval between the long side wall processing portion of the die and the long side wall processing portion of the punch at the two end portions in the long side direction and the short side direction interval between the long side wall processing portion of the die and the long side wall processing portion of the punch at the central portion in the long side direction can be reduced, thereby making the wall thickness distribution of the long side wall of the formed square can more uniform.

[0016] Furthermore, in the present invention, there is no need to implement measures to suppress the deflection of the long side wall processed portion of the die, such as changing the die material to a material with a high Young's modulus such as superhard alloy, which would increase manufacturing costs, thereby suppressing an increase in manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is an explanatory diagram showing a square can which is a final molded product of a square can manufacturing method according to one embodiment of the present invention.

[0018] Figure 2 It is an explanatory diagram showing each step of the square can manufacturing method.

[0019] Figure 3 It is an explanatory diagram showing each step of the square can manufacturing method.

[0020] Figure 4 It is an explanatory diagram showing a drawing and ironing unit.

[0021] Figure 5 It is an explanatory diagram showing the situation during the deep ironing process.

[0022] Figure 6 It is an explanatory diagram showing a state in which a punch of a drawing and ironing unit is inserted into a die processing through hole in a no-load state and a modified example.

[0023] Figure 7 It is an explanatory diagram showing the state of a die and a punch during a drawing ironing process.

[0024] Figure 8 It is an explanatory diagram showing a shape correction unit.

[0025] Fig. 9 It is an explanatory diagram showing a shape correction unit.

[0026] Fig.10 This is an explanatory diagram for explaining the springback phenomenon. DETAILED DESCRIPTION

[0027] Hereinafter, a square can manufacturing method and a square can manufacturing device 10 as one embodiment of the present invention will be described based on the drawings.

[0028] [Square can 60 (final product)]

[0029] First, the square can 60, which is a final molded product manufactured by the square can manufacturing method and the square can manufacturing device 10, is made of a metal such as aluminum. In this embodiment, the square can 60 is used as a shell of a lithium ion battery. Figure 1 As shown, the square tank 60 includes a flat plate-shaped (or substantially flat plate-shaped) bottom wall 61 and a square cylindrical portion 65 .

[0030] like Figure 1 As shown, the bottom wall 61 is formed into a substantially quadrilateral (or quadrilateral) having a pair of bottom long sides 62 and a pair of bottom short sides 63 at its outer edges.

[0031] The bottom long side portion 62 is a portion extending in a straight line (or substantially in a straight line) along the long side direction.

[0032] The bottom short side portion 63 is a portion extending linearly (or substantially linearly) in the short side direction so as to form an angle of 90° with the bottom long side portion 62 .

[0033] A bottom curved corner portion 64 is formed between the bottom long side portion 62 and the bottom short side portion 63. The bottom curved corner portions 64 are smoothly connected to the bottom long side portion 62 and the bottom short side portion 63 and are curved convexly toward the outer peripheral side. In this embodiment, each bottom curved corner portion 64 is formed by bending with the same single R (single curvature radius).

[0034] like Figure 1 As shown, the rectangular cylindrical portion 65 includes a pair of long side walls 66 disposed opposite to each other in the short side direction and a pair of short side walls 67 disposed opposite to each other in the long side direction.

[0035] like Figure 1 As shown, each long side wall 66 is formed in a flat plate shape (or substantially flat plate shape) rising upward from the bottom long side portion 62, and a pair of long side walls 66 are formed parallel to each other.

[0036] like Figure 1 As shown, each short side wall 67 is formed into a flat plate (or substantially flat plate) rising upward from the bottom short side portion 63 at an angle of 90° with the long side wall 66 , and a pair of short side walls 67 are formed parallel to each other.

[0037] A corner wall 68 is formed between the long side wall 66 and the short side wall 67 in an R-shaped manner that rises upward from the bottom curved corner 64, smoothly connects the long side wall 66 and the short side wall 67, and is curved convexly toward the outer peripheral side. In this embodiment, each corner wall 68 is formed by bending with the same single R (single curvature radius).

[0038] [Square can manufacturing method]

[0039] like Figure 2 , Figure 3 As shown, the square can manufacturing method is a method for manufacturing a square can 60, comprising: a blank preparation step of preparing a blank 60A; a stamping step of performing a coining process on a specified portion of the blank 60A; a first drawing step of performing a first drawing process on the blank 60A that has undergone the stamping process; a second drawing step of performing a second drawing process on a cup-shaped first intermediate molded product 60B that has undergone the first drawing process; a drawing and thinning step of performing a drawing and thinning process on a second intermediate molded product 60C obtained by the second drawing process; and a shape correction step of correcting the shape of a third intermediate molded product 60D obtained by the drawing and thinning process.

[0040] Hereinafter, each step of the square can manufacturing method will be described in detail.

[0041] First, if Figure 2 As shown in (a) of FIG. 1 , the blank preparation step is a step of forming a blank 60A as a metal plate by punching a strip plate made of a metal such as aluminum.

[0042] like Figure 2 As shown in (b) of FIG. 1 , the coining step is a step of performing coining processing to reduce the plate thickness by punching a predetermined portion of the blank 60A in the plate thickness direction.

[0043] In the present embodiment, coining is performed to reduce the thickness of the blank 60A by punching the bottom wall portion (a portion to be the bottom wall 61 in the state of the square can 60 as a final molded product) in the thickness direction.

[0044] like Figure 2 As shown in (c) of FIG. 1 , the first drawing step is a step of forming a cup-shaped first intermediate molded product 60B by drawing the blank 60A that has undergone the coining step.

[0045] Specifically, in the first drawing process, while the blank 60A is pressed from the upper side by the blank holder 23 which functions as a wrinkle-proof pressure plate to suppress the formation of wrinkles on the blank 60A, the blank 60A is pressed (pulled) from the upper side into the die-processed through hole 21a formed in the die 21 by the punch 22, thereby plastically deforming the blank 60A to form a cup-shaped first intermediate molded product 60B.

[0046] like Figure 3 As shown in (d) of FIG. 1 , the second drawing step is a step of forming a second intermediate molded product 60C by performing a second drawing process on the first intermediate molded product 60B obtained in the first drawing step.

[0047] Specifically, in the second drawing process, while the first intermediate molded product 60B is pressed from the upper side (inside) by the blank retaining member 33 which functions as a wrinkle-proof pressure plate for suppressing the formation of wrinkles on the second intermediate molded product 60C, the first intermediate molded product 60B is pressed (pulled) into the die-processed through hole 31a formed in the die 31 by the punch 32, thereby plastically deforming the first intermediate molded product 60B to form the second intermediate molded product 60C.

[0048] It should be noted that, during the drawing process, only the punch 32 and (a portion of) the first intermediate molded product 60B are inserted into the die processing through-hole 31 a , and the blank holder 33 is not inserted.

[0049] like Figure 3 As shown in (e), the drawing and thinning process is the following process: through the gap formed in the die processing through hole 41a of the die 41 and the punch 42 inserted into the die processing through hole 41a, the cylindrical portion predetermined portion 65C (the portion that becomes the square cylindrical portion 65 in the state of the final molded product) of the second intermediate molded product 60C is mainly subjected to drawing and thinning to form the third intermediate molded product 60D.

[0050] Note that, in the ironing step, ironing is also performed on a portion of the planned bottom wall portion 61C of the second intermediate molded product 60C (a portion that becomes the bottom wall 61 in the state of the final molded product).

[0051] Specifically, in the deep drawing and thinning process, Figure 5As shown, while the second intermediate molded product 60C is pressed from the upper side (inside) by the blank holder 43 which functions as a wrinkle-proof pressure plate for suppressing the formation of wrinkles on the third intermediate molded product 60D, the punch 42 is moved relative to the die 41 (in the present embodiment, the punch 42 and the blank holder 43 are moved relative to the die 41 which is set in a fixed state), thereby using the punch 42 to press (pull) the second intermediate molded product 60C into the die-processed through hole 41a, and through the gap between the die-processed inner peripheral surface 41b of the die-processed through hole 41a and the punch-processed outer peripheral surface 42a of the punch 42, the second intermediate molded product 60C is plastically deformed to form the third intermediate molded product 60D.

[0052] It should be noted that, during the above-mentioned drawing and ironing process, only the punch 42 and (a portion of) the second intermediate molded product 60C are inserted into the die processing through hole 41 a , and the blank holder 43 is not inserted.

[0053] like Figure 4 , Figure 5 As shown, the die 41 used in the ironing process has a die processing through hole 41a formed to penetrate in the punch moving direction (in the present embodiment, the up-down direction) during the ironing process.

[0054] like Figure 4 , Figure 5 As shown, the die-processed through hole 41a has: a die-processed inner peripheral surface 41b, which is formed as a surface parallel to the punch movement direction (upward and downward direction); and a tapered processing surface 41f, which is formed on the front side (upward side) of the die-processed inner peripheral surface 41b in the punch movement direction (upward and downward direction).

[0055] like Figures 4 to 6 As shown, the die processed inner peripheral surface 41b has: a pair of die long side wall processing parts 41c, which are used to process the long side wall predetermined part 66C of the second intermediate molded product 60C (the part that becomes the long side wall 66 in the state of the final molded product); and a pair of die short side wall processing parts 41d, which are used to process the short side wall predetermined part 67C of the second intermediate molded product 60C (the part that becomes the short side wall 67 in the state of the final molded product).

[0056] like Figure 4 , Figure 6 As shown in (a), each die long side wall processing portion 41c is formed to extend linearly along the long side direction when viewed along the punch moving direction (up and down direction) (when the die 41 is cut through a plane perpendicular to the punch moving direction).

[0057] like Figure 4 , Figure 6As shown in (a), each die short side wall processing portion 41d is formed to extend linearly along the short side direction when viewed along the punch moving direction (up and down direction) (when the die 41 is cut along a plane perpendicular to the punch moving direction).

[0058] In addition, if Figure 4 , Figure 6 As shown in (a), a curved corner portion 41e is formed between the die long side wall processing portion 41c and the die short side wall processing portion 41d, which smoothly connects the die long side wall processing portion 41c and the die short side wall processing portion 41d and is curved toward the outer peripheral side into a convex shape. The curved corner portion 41e functions as a portion for processing the vicinity of the predetermined corner wall portion 68C of the second intermediate molded product 60C (the portion that becomes the corner wall 68 of the square cylindrical portion 65 in the state of the final molded product). In this embodiment, each curved corner portion 41e is formed by bending with the same single R (single curvature radius).

[0059] like Figure 4 , Figure 5 As shown, the tapered processed surface 41f is formed to be inclined so as to decrease in diameter (the width in the long-side direction and the short-side direction becomes narrower) as it goes toward the back side (lower side) in the punch moving direction (up-down direction).

[0060] like Figures 4 to 6 As shown, the punch 42 used in the ironing process has a punch processing outer peripheral surface 42a formed as a surface parallel to the punch moving direction (vertical direction) as the outer peripheral surface facing the inner side surface of the die processing through hole 41a during the ironing process.

[0061] like Figure 4 , Figure 6 As shown in (a), the punch processed outer peripheral surface 42a has: a pair of punch long side wall processing parts 42b, which cooperate with the die long side wall processing part 41c to process the long side wall predetermined part 66C of the second intermediate molded product 60C; and a pair of punch short side wall processing parts 42c, which cooperate with the die short side wall processing part 41d to process the short side wall predetermined part 67C of the second intermediate molded product 60C.

[0062] like Figure 6 As shown in (a), each punch long side wall processing portion 42b has: a processed top 42b-1, located at the outermost side in the short side direction of the punch long side wall processing portion 42b; and an inclined portion 42b-2, formed on both sides of the processed top 42b-1 in the long side direction, and inclined in a manner approaching the inner side in the short side direction as it tends to the outer side in the long side direction. Each punch long side wall processing portion 42b has an overall shape in which its central portion in the long side direction bulges outward in the short side direction than its two ends in the long side direction.

[0063] like Figure 6As shown in (a), the processed top 42b-1 is formed at the center of the long side direction of the punch long side wall processing portion 42b (or near the center of the long side direction). In the present embodiment, the processed top 42b-1 is formed as a portion extending in a straight line along the long side direction when observed along the punch moving direction (up and down direction) (when the punch 42 is cut in section by a plane perpendicular to the punch moving direction).

[0064] It should be noted that, when the processed top portion 42b-1 is formed to extend linearly in a cross-sectional view, the same as in the example Figure 6 Compared with the case where the processed top 42b-1 is formed to be dot-shaped when viewed in cross section as in the modified example shown in (b), the amount of deflection caused in the die long side wall processed portion 41c due to the forming reaction force during deep drawing and ironing can be reduced.

[0065] like Figure 1 As shown, the inclined portion 42b-2 is formed as a portion extending linearly when viewed along the punch moving direction (up and down direction) (when the punch 42 is cut along a plane perpendicular to the punch moving direction).

[0066] like Figure 6 As shown in (a), each punch short side wall processing portion 42c is formed to extend linearly along the short side direction when viewed along the punch moving direction (up and down direction) (when the punch 42 is cut through a plane perpendicular to the punch moving direction).

[0067] In addition, a curved corner portion 42d is formed between the punch long side wall processing portion 42b and the punch short side wall processing portion 42c, which smoothly connects the punch long side wall processing portion 42b and the punch short side wall processing portion 42c and is curved to the outer peripheral side in a convex shape. The curved corner portion 42d functions as a portion for processing the vicinity of the corner wall predetermined portion 68C of the second intermediate molded product 60C in cooperation with the curved corner portion 41e of the die 41. In the present embodiment, each curved corner portion 42d is formed by bending with the same single R (single curvature radius).

[0068] It should be noted that during the drawing and thinning process, the second intermediate molded product 60C is pressed (pulled) into the gap between the die long side wall processing portion 41c and the punch long side wall processing portion 42b, so that the thinning process of thinning the plate thickness is mainly performed on the long side wall predetermined portion 66C of the second intermediate molded product 60C, and the second intermediate molded product 60C is pressed (pulled) into the gap between the die short side wall processing portion 41d and the punch short side wall processing portion 42c, so that the drawing process is mainly performed near the corner wall predetermined portion 68C (and the short side wall predetermined portion 67C) of the second intermediate molded product 60C.

[0069] Here, when the flatness ratio (ratio of the long side dimension to the short side dimension) of the punching through hole 41a is high as in the present embodiment, Figure 7 As shown in (a), during the drawing and ironing process, the die long side wall processing part 41c is bent in a manner such that the central part in the long side direction of the die long side wall processing part 41c is deflected toward the outside in the short side direction due to the forming reaction force. As a result, Figure 6 Compared with the state in which the punch 42 is inserted into the die processed through hole 41a in a no-load state as shown in (a), the short-side direction interval W1 between the die long-side wall processing portion 41c and the punch long-side wall processing portion 42b at the center of the long-side direction of the die long-side wall processing portion 41c is enlarged.

[0070] Therefore, if Figure 7 As shown in (b), in the case where the die long side wall processing portion 41c and the punch long side wall processing portion 42b are formed to extend linearly along the long side direction, and the short side direction intervals W1 and W2 between the die long side wall processing portion 41c and the punch long side wall processing portion 42b are set in a manner that becomes constant, the wall thickness of the long side wall predetermined portion 66C that has undergone deep drawing and thinning processing will become thicker in the central portion in the long side direction, and will become thinner as it approaches the two end portions in the long side direction, and a uniform wall thickness distribution of the long side wall predetermined portion 66C cannot be achieved.

[0071] In contrast, in this embodiment, if Figure 6 As shown in (a), the die long side wall processing portion 41c and the punch long side wall processing portion 42b are configured as follows: when the punch 42 is inserted into the die processing through hole 41a in a no-load state (in other words, the second intermediate molded product 60C is not sandwiched between the die long side wall processing portion 41c and the punch long side wall processing portion 42b, and no molding reaction force is applied to the die 41 and the punch 42), the short side direction interval W1 between the central portion in the long side direction of the punch long side wall processing portion 42b and the die long side wall processing portion 41c is narrower than the short side direction interval W2 between the two end portions in the long side direction of the punch long side wall processing portion 42b and the die long side wall processing portion 41c.

[0072] Therefore, during the drawing and thinning process in which the die long side wall processing portion 41c is bent due to the forming reaction force, the dimensional difference between the short side direction interval W2 between the die long side wall processing portion 41c and the punch long side wall processing portion 42b at the two end portions in the long side direction and the short side direction interval W1 between the die long side wall processing portion 41c and the punch long side wall processing portion 42b in the central portion in the long side direction can be reduced, thereby making the wall thickness distribution of the formed long side wall predetermined portion 66C closer to uniform.

[0073] In addition, if Figure 6As shown in (a), the die 41 and the punch 42 are formed as follows: when the punch 42 is inserted into the die-processed through hole 41a in a no-load state, the short-side direction interval W1 between the central part of the long-side direction of the punch long-side wall processing part 42b and the die long-side wall processing part 41c is narrower than the long-side direction interval W3 between the punch short-side wall processing part 42c and the die short-side wall processing part 41d.

[0074] It should be noted that if Figure 6 As shown in (a) and the like, the die processed inner peripheral surface 41b and the punch processed outer peripheral surface 42a are respectively formed to be line symmetrical in the long side direction and line symmetrical in the short side direction when viewed from the punch moving direction (up and down direction).

[0075] In addition, during the deep drawing and thinning process, the punch 42 is inserted into the die processed through hole 41a in the following manner: the long side wall processing portion 41c of the die on both sides of the punch 42 in the long side direction and the long side wall processing portion 42b of the punch are the same in the long side direction interval W1 and W2, and the short side wall processing portion 41d of the die on both sides of the punch 42 in the short side direction and the short side wall processing portion 42c of the punch are the same in the short side direction interval W3.

[0076] like Figure 3 As shown in (f), the shape correction process is the following process: the short side direction interval between a pair of long side wall predetermined portions 66D (the portions that become the long side walls 66 in the state of the final molded product) of the third intermediate molded product 60D obtained by the deep drawing and thinning process is enlarged (widening processing is performed), and the bottom wall predetermined portion 61D (the portion that becomes the bottom wall 61 in the state of the final molded product) of the third intermediate molded product 60D is flattened (flattening processing is performed to a state close to a flat state), thereby forming a fourth intermediate molded product 60E.

[0077] In the shape correction process, Fig. 9 As shown, the widening and flattening processes are performed by the following process: when the shape correction punch 52 is inserted into the third intermediate molded product 60D, the shape correction punch 52 is moved relative to the die 51 (in the present embodiment, the shape correction punch 52 is moved relative to the die 51 which is fixed), the third intermediate molded product 60D is pressed (pulled) into the die machined through hole 51a by the shape correction punch 52, and the bottom wall predetermined portion 61D of the third intermediate molded product 60D is clamped by the shape correction punch 52 and the bottom wall extrusion member 53.

[0078] Hereinafter, each processing of the shape correction step will be described in detail.

[0079] First, if Figure 8 , Fig. 9As shown, the widening process is performed as follows: by inserting the shape correction punch 52 into the third intermediate molded product 60D supported by the outer supporting member 54, the short side wall pressing portion 52b of the shape correction punch 52 inserted into the third intermediate molded product 60D is used to restrict a pair of short side wall predetermined portions 67D from approaching each other, and the long side wall pressing portion 52c of the shape correction punch 52 inserted into the third intermediate molded product 60D is used to press each long side wall predetermined portion 66D (especially near the central portion in the long dimension direction) toward the outside in the short side direction, thereby pressing and expanding the short side direction interval between a pair of long side wall predetermined portions 66D (especially between the central portions in the long side direction of the long side wall predetermined portions 66D) into a wedge shape.

[0080] By this widening process, even if Fig.10 Even in the case of a so-called canning phenomenon in which the central portion in the longitudinal direction of each long side wall 166 shown is recessed toward the inner side in the lateral direction, the shape can be corrected.

[0081] like Fig. 9 As shown, the short side wall pressing portion 52b is configured as follows: when the shape correction punch 52 is inserted into the third intermediate molded product 60D, the two side portions in the long side direction of each long side wall predetermined portion 66D and each short side wall predetermined portion 67D (the portion that becomes the short side wall 67 in the final molded product state) are pressed from the inside on the opening side of the third intermediate molded product 60D.

[0082] Thus, the short side wall pressing portion 52b performs the following functions: when the shape correction punch 52 is inserted into the third intermediate molded product 60D, it suppresses (limits) the two side portions in the long side direction of a pair of long side wall predetermined portions 66D from approaching each other, and suppresses (limits) the pair of short side wall predetermined portions 67D from approaching each other.

[0083] It should be noted that the short side wall pressing portion 52b can also be designed in a manner such that when the shape correction punch 52 is inserted into the third intermediate molded product 60D, the interval between the two side portions in the long side direction of a pair of long side wall predetermined portions 66D is pressed and expanded into a wedge shape in the short side direction. In addition, the short side wall pressing portion 52b can also be designed in a manner such that the interval between a pair of short side wall predetermined portions 67D is pressed and expanded into a wedge shape in the long side direction.

[0084] like Fig. 9 As shown, the short side wall pressing portion 52b has a tapered portion on the inner side (lower side) in the punch moving direction (up and down direction) that is inclined in a manner that approaches the inner side of the long side direction as it approaches the inner side, thereby facilitating the insertion of the shape correction punch 52 into the third intermediate molded product 60D.

[0085] In addition, in the present embodiment, the short side wall pressing portion 52b is formed by another member that is formed separately from the punch body 52a and fixedly mounted on the punch body 52a, thereby making it easy to adjust the degree of compression of the short side wall pressing portion 52b on the long side wall predetermined portion 66D and the short side wall predetermined portion 67D. However, the short side wall pressing portion 52b may also be formed integrally with the punch body 52a.

[0086] like Fig. 9 As shown, the long side wall pressing portion 52c is configured to press the central portion of each long side wall predetermined portion 66D in the long side direction from the inside on the opening side of the third intermediate molded product 60D when the shape correction punch 52 is inserted into the third intermediate molded product 60D.

[0087] Thus, the long-side-wall pressing portion 52 c has a function of pressing and expanding the interval in the short-side direction between the pair of expected long-side-wall portions 66D.

[0088] like Fig. 9 As shown, the long-side wall pressing portion 52c has a pressing surface whose central portion in the long-side direction is located at a position bulging outward in the short-side direction relative to both end portions in the long-side direction of the pressing surface.

[0089] In addition, if Fig. 9 As shown, the long side wall extrusion portion 52c has a tapered portion on the inner side (lower side) in the punch moving direction (up and down direction) that is inclined in a manner approaching the inner side of the short side direction as it approaches the inner side, thereby making it easy to insert the shape correction punch 52 into the third intermediate molded product 60D.

[0090] In addition, in the present embodiment, the long side wall pressing portion 52c is formed by another member that is formed separately from the punch body 52a and fixedly mounted on the punch body 52a, thereby making it easy to adjust the degree of pressing of the long side wall pressing portion 52c on the long side wall predetermined portion 66D. However, the long side wall pressing portion 52c may also be formed integrally with the punch body 52a.

[0091] It should be noted that, in this embodiment, Fig. 9As shown, the following structure is used for explanation: when the shape correction punch 52 is inserted into the third intermediate molded product 60D, the short side wall side pressing portion 52b and the long side wall extrusion portion 52c are arranged at a position corresponding to the opening side (near the opening) of the third intermediate molded product 60D, but the configuration of the short side wall side pressing portion 52b and the long side wall extrusion portion 52c relative to the third intermediate molded product 60D when the shape correction punch 52 is inserted into the third intermediate molded product 60D is not limited to the above situation. For example, it can also be set as: the short side wall side pressing portion 52b and the long side wall extrusion portion 52c are arranged at a position corresponding to the center of the punch moving direction (up and down direction) of the third intermediate molded product 60D when the shape correction punch 52 is inserted.

[0092] In addition, the number of the short-side wall pressing portions 52b and the long-side wall pressing portions 52c is not limited to Figure 8 , Fig. 9 The quantities shown, for example, except Figure 8 , Fig. 9 In addition to the number shown, short side wall pressing portions 52b and long side wall extrusion portions 52c may be additionally provided at positions corresponding to the vicinity of the center of the punch moving direction (up and down direction) of the third intermediate molded product 60D when the shape correction punch 52 is inserted.

[0093] like Fig. 9 As shown, the outer supporting member 54 is configured to support the flange portion 69D of the third intermediate molded product 60D from the lower side during the widening process, and press the two side portions of the long side wall predetermined portion 66D in the long side direction from the outside on the opening side (near the opening) of the third intermediate molded product 60D.

[0094] Thus, the outer supporting member 54 supports the third intermediate molded product 60D when the shape correcting punch 52 is inserted into the third intermediate molded product 60D, and suppresses (limits) the expansion of both side portions in the long side direction of each expected long side wall portion 66D outward in the short side direction.

[0095] It should be noted that, depending on the embodiment, other support members that support the third intermediate molded product 60D from the outside may be provided at any position instead of the outer support members 54 or in addition to the outer support members 54 .

[0096] The flattening process is as follows: by moving the shape correction punch 52, the bottom wall predetermined portion 61D is clamped by the bottom wall pressing portion 52d of the shape correction punch 52 inserted in the third intermediate molded product 60D and the bottom wall pressing member 53 arranged on the outer side of the bottom wall predetermined portion 61D, and the third intermediate molded product 60D (the bottom wall predetermined portion 61D and a part of the cylindrical portion predetermined portion 65D near the bottom wall predetermined portion 61D) is pressed (pulled) into the die processing through hole 51a by the shape correction punch 52, thereby forming a gap between the die processing inner peripheral surface of the die processing through hole 51a formed in the die 51 and the punch processing outer peripheral surface of the shape correction punch 52 inserted in the die processing through hole 51a, and the vicinity of the connection (bending corner) between the cylindrical portion predetermined portion 65D and the bottom wall predetermined portion 61D of the third intermediate molded product 60D is flattened. Fig. 9 The region R) shown in FIG. 1 is subjected to a drawing and ironing process over the entire circumference thereof, thereby flattening the planned bottom wall portion 61D.

[0097] The pressing surface of the bottom wall pressing portion 52 d of the shape correcting punch 52 that sandwiches the planned bottom wall portion 61D and the pressing surface of the bottom wall pressing member 53 are each formed in a flat shape.

[0098] It should be noted that the bottom wall pressing portion 52d of the shape correcting punch 52 is formed integrally with the punch body 52a, but the bottom wall pressing portion 52d may be constituted by another member formed separately from the punch body 52a.

[0099] In addition, the bottom wall pressing member 53 is supported by a cylinder (not shown), and when pressed downward by the punch (third intermediate molded product 60D) during the flattening process, the bottom wall pressing member 53 moves downward together with the punch (third intermediate molded product 60D), and a moderate punching (pressure) is applied to the bottom wall predetermined portion 61D by sandwiching the bottom wall pressing member 53 and the shape correction punch 52. It should be noted that during the above-mentioned flattening process, the impact when the punch (third intermediate molded product 60D) collides with the bottom wall pressing member 53 is mitigated by the cylinder (not shown).

[0100] It should be noted that in the above-mentioned first drawing process, second drawing process and drawing and thinning process, a device equivalent to the bottom wall extrusion member 53 (and the cylinder) for supporting the outer side (lower side) of the predetermined bottom wall portion is not used, that is, a device for clamping the predetermined bottom wall portion 61D together with the punch moving downward is not used.

[0101] In the shape correction process of the present embodiment as described above, after the shape correction punch 52 is inserted into the third intermediate molded product 60D, the shape correction (widening processing) of the cylindrical portion predetermined portion 65D and the shape correction (flattening processing) of the bottom wall predetermined portion 61D can be performed at the same time through a process (one action) of moving the shape correction punch 52 toward the die 51 and the bottom wall extrusion member 53 side, thereby suppressing the increase in manufacturing burden and improving the shape accuracy of the square can 60.

[0102] In addition, it is also considered that: in the deep drawing process or deep ironing process, the bottom wall predetermined portion of the intermediate molded product is clamped by a punch and a member arranged on the outside of the predetermined portion of the bottom wall to suppress the bulging of the bottom wall to the outside, but in the case of adopting such a structure, the stroke of the punch needs to be designed to be large during the deep drawing process or deep ironing process, and the member arranged on the outside (lower side) of the predetermined portion of the bottom wall also needs to be moved to follow the movement of the punch, which will lead to an increase in device cost and a decrease in manufacturing speed. In contrast, in the present invention, there is no need to adopt such a structure, and the stroke of the bottom wall pressing member 53 can be short, which can avoid an increase in device cost and a decrease in manufacturing speed.

[0103] In addition to the above steps, the square can manufacturing method also includes various steps such as a trimming step of cutting off unnecessary portions near the opening such as the flange of the fourth intermediate molded product 60E obtained in the shape correction step, and a cleaning step.

[0104] [Square can manufacturing device 10]

[0105] Next, the square can manufacturing apparatus 10 will be described below.

[0106] like Figure 2 , Figure 3 As shown, the square can manufacturing device 10 includes a first drawing unit 20 for performing a first drawing process, a first drawing unit 20 for performing a second drawing process, a drawing and ironing unit 40 for performing a drawing and ironing process, and a shape correction unit 50 for performing a shape correction process.

[0107] like Figure 2 , Figure 3 As shown, the first drawing unit 20, the second drawing unit 30 and the drawing and thinning unit 40 include: a die 21, a die 31, a die 41; a punch 22, a punch 23, a punch 24; a blank holder 23, a blank holder 33, a blank holder 43; and various peripheral equipment such as a driving part composed of an actuator, a motor, etc. for driving various parts such as the punch, a supporting member, etc.

[0108] In addition, if Figure 4As shown, the shape correction unit 50 includes a die 51, a shape correction punch 52, a bottom wall pressing member 53, an outer supporting member 54, a driving unit composed of an actuator and a motor for driving the punch and other parts, and various peripheral devices such as a supporting member.

[0109] The specific structures and functions of these parts are as described above.

[0110] The embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the claims. For example, the various structures of the above or below embodiments and modified examples can be arbitrarily combined to form a square can manufacturing method and a square can manufacturing device 10, etc.

[0111] For example, in the above-mentioned embodiment, the following configuration is used for explanation: two drawing processes (or drawing processes) are performed before the drawing process, but the number of drawing processes (or drawing processes) performed before the drawing process may be one, three or more.

[0112] In addition, in the above-mentioned embodiment, the following structure is used for description: the die long side wall processing portion 41c is formed to extend in a straight line along the long side direction, and the punch long side wall processing portion 42b is formed to have an overall shape with its long side center located at a position bulging outward in the short side direction compared with its two end sides in the long side direction. Thus, when the punch 42 is inserted into the die processing through hole 41a in a no-load state, the short side distance W1 between the long side center of the punch long side wall processing portion 42b and the die long side wall processing portion 41c is narrower than the short side distance W2 between the long side end portions of the punch long side wall processing portion 42b and the die long side wall processing portion 41c.

[0113] However, the specific scheme of the long side wall processing parts 41c and 42b is not limited to the above-mentioned method. As long as the interval W1 is narrower than the interval W2 in the above-mentioned state, any method can be used. For example, when the punch long side wall processing part 42b is formed into an overall shape with its center in the long side direction located at a position bulging outward in the short side direction compared with its two end sides in the long side direction, the die long side wall processing part 41c can also be formed into a shape other than the shape extending linearly along the long side direction (for example, an overall shape with its center in the long side direction located at a position bulging outward in the short side direction compared with its two end sides in the long side direction, an overall shape with its center in the long side direction located at a position bulging inward in the short side direction compared with its two end sides in the long side direction).

[0114] In addition, the interval W1 can also be made narrower than the interval W2 in the above-mentioned state by forming the die long side wall processing portion 41c into an overall shape having a center in the long side direction located at a position bulging inwardly in the short side direction compared with the two end sides in the long side direction. In this case, various shapes can be considered as the shape of the punch long side wall processing portion 42b, such as a shape extending linearly along the long side direction, an overall shape having a center in the long side direction located at a position bulging outwardly in the short side direction compared with the two end sides in the long side direction, and an overall shape having a center in the long side direction located at a position bulging inwardly in the short side direction compared with the two end sides in the long side direction.

[0115] In addition, when the punch long side wall processing part 42b is formed into an overall shape having its long side center located at a position bulging outward in the short side direction compared with its long side end sides, the specific scheme of the punch long side wall processing part 42b is not limited to the above embodiment.

[0116] For example, in Figure 6 In the example shown in (a), the processed top 42b-1 is formed as a portion extending linearly in the long side direction when viewed in cross section, but it may also be as shown in Figure 6 As in the modification shown in (b), the processed top portion 42b-1 is a dot-shaped portion when viewed in cross section.

[0117] In addition, Figure 6 In the example shown in (a), the inclined portion 42b-2 is formed as a portion extending linearly in a cross-sectional view, but it may also be as follows Figure 6 As in the modified example shown in (b), the inclined portion 42b-2 is a portion extending in a curved shape when viewed in cross section. In addition, the inclined portion 42b-2 can also be formed as a portion composed of one or more straight lines and one or more curves when viewed in cross section.

[0118] It should be noted that in Figure 6 In the modified example shown in (b), the punch long side wall processing portion 42b is formed in a so-called drum shape in which the entire portion is curved convexly outward in the short side direction in such a way that its center in the long side direction is located at a position that bulges outward in the short side direction compared with its two end portions in the long side direction.

[0119] In addition, similarly, when the die long side wall processing portion 41c is formed to have a processing top (located at the innermost side in the short side direction of the die long side wall processing portion 41c) and an inclined portion (formed on both sides of the processing top in the long side direction and inclined in a manner approaching the outer side in the short side direction as it approaches the outer side in the long side direction), and has an overall shape with its long side center located bulging toward the inner side in the short side direction compared to the two end sides in the long side direction, the processing top of the die long side wall processing portion 41c can also be formed as a portion extending in a straight line along the long side direction when viewed in section, and the processing top of the die long side wall processing portion 41c can also be formed as a point-shaped portion when viewed in section.

[0120] In addition, the inclined portion of the long side wall processing portion 41c of the die can be formed as a portion extending in a straight line when viewed in section. In addition, the inclined portion of the long side wall processing portion 41c of the die can be formed as a portion extending in a curved line when viewed in section. In addition, the inclined portion of the long side wall processing portion 41c of the die can be formed as a portion composed of one or more straight lines and one or more curves when viewed in section.

[0121] In addition, in the above-mentioned embodiment, the die short side wall processing portion 41d and the punch short side wall processing portion 42c are described as being formed to extend linearly along the long side direction, but these processing portions can also be formed in shapes other than this (for example, a curved shape when observed in the punch moving direction).

[0122] In addition, in the above-mentioned embodiment, the case where the die-processed inner peripheral surface 41b and the punch-processed outer peripheral surface 42a are set to be formed as surfaces parallel to the punch movement direction (up and down direction) is described, but the specific scheme of the die-processed inner peripheral surface 41b and the punch-processed outer peripheral surface 42a is not limited to this.

[0123] Description of Reference Numerals

[0124] 10: Square can manufacturing device;

[0125] 20: first drawing unit;

[0126] 21: punch die;

[0127] 21a: punching die to process through holes;

[0128] 22: Punch;

[0129] 23: blank holder;

[0130] 30: second drawing unit;

[0131] 31: punch die;

[0132] 31a: punching die to process through holes;

[0133] 32: Punch;

[0134] 33: blank holder;

[0135] 40: drawing and thinning unit;

[0136] 41: punch die;

[0137] 41a: punching die to process through holes;

[0138] 41b: die processing inner surface;

[0139] 41c: punch die long side wall processing part;

[0140] 41d: die short side wall processing part;

[0141] 41e: curved corner;

[0142] 41f: tapered machining surface;

[0143] 42: Punch;

[0144] 42a: punch processing outer peripheral surface;

[0145] 42b: punch long side wall processing part;

[0146] 42b-1: Processing top;

[0147] 42b-2: inclined portion;

[0148] 42c: punch short side wall processing part;

[0149] 42d: curved corner;

[0150] 43: blank holder;

[0151] 50: shape correction unit;

[0152] 51: punch die;

[0153] 51a: punching die to process through holes;

[0154] 52: Shape correction punch;

[0155] 52a: Punch body;

[0156] 52b: short side wall pressing portion;

[0157] 52c: long side wall extrusion portion;

[0158] 52d: bottom wall extrusion portion;

[0159] 53: bottom wall extrusion member;

[0160] 54: Outer supporting member;

[0161] 60: Square can (final product);

[0162] 61: Bottom wall;

[0163] 62: bottom long side;

[0164] 63: bottom short side;

[0165] 64: bottom curved corner;

[0166] 65: Square cylindrical part;

[0167] 66: long side wall;

[0168] 67: short side wall;

[0169] 68: corner wall;

[0170] 60A: blank;

[0171] 60B: first intermediate molded product;

[0172] 60C: Second intermediate molded product;

[0173] 61C: bottom wall predetermined portion;

[0174] 65C: cylindrical portion predetermined portion;

[0175] 66C: long side wall predetermined portion;

[0176] 67C: short side wall predetermined portion;

[0177] 68C: corner wall predetermined portion;

[0178] 60D: The third intermediate molded product;

[0179] 61D: bottom wall predetermined portion;

[0180] 65D: cylindrical portion predetermined portion;

[0181] 66D: long side wall predetermined portion;

[0182] 67D: short side wall predetermined portion;

[0183] 69D: flange portion;

[0184] 60E: Fourth intermediate molded product.

Claims

1. A method for manufacturing a square can, the method comprising manufacturing a square can, the square can comprising: a bottom wall; and a square cylindrical portion having a pair of long side walls and a pair of short side walls, the method comprising: The square can manufacturing method includes a drawing and ironing step, wherein the drawing and ironing step performs a drawing and ironing process on a predetermined portion of a cylindrical portion of an intermediate molded product through a gap between a die-processed inner peripheral surface of a die-processed through hole formed on a die and a punch-processed outer peripheral surface formed on a punch inserted into the die-processed through hole. The die processing inner peripheral surface has a die long side wall processing portion for processing a predetermined long side wall portion of the intermediate molded product. The punch processed outer peripheral surface has a punch long side wall processing portion for processing the predetermined long side wall portion. The die and the punch are formed such that, when the punch is inserted into the die-processed through hole in a no-load state, the short-side distance between the central portion of the punch's long-side wall processing portion and the die's long-side wall processing portion is narrower than the short-side distance between the two end portions of the punch's long-side wall processing portion and the die's long-side wall processing portion.

2. The method for manufacturing a square can according to claim 1, characterized in that: The punch long side wall processing portion comprises: a processing top, located at the outermost side in the short side direction of the punch long side wall processing portion; and an inclined portion, formed on both sides of the processing top in the long side direction, inclined in a manner approaching the inner side in the short side direction as it approaches the outer side in the long side direction. The punch long side wall processing portion has an overall shape in which its central portion in the long side direction bulges outward in the short side direction.

3. The method for manufacturing a square can according to claim 2, characterized in that: The processed top portion is a portion extending linearly in the long-side direction when viewed in cross section.

4. The method for manufacturing a square can according to any one of claims 1 to 3, characterized in that: The die processing inner peripheral surface has a die short side wall processing portion for processing a predetermined short side wall portion of the intermediate molded product. The punch processed outer peripheral surface has a punch short side wall processing portion for processing the short side wall predetermined portion. The die and the punch are formed such that, when the punch is inserted into the die-processed through hole in a no-load state, the short-side direction interval between the central portion of the punch long-side wall processing portion and the die long-side wall processing portion is narrower than the long-side direction interval between the punch short-side wall processing portion and the die short-side wall processing portion.

5. A square can manufacturing device, the square can manufacturing device is a square can manufacturing device for manufacturing square cans, the square can comprises: a bottom wall; and a square cylindrical portion having a pair of long side walls and a pair of short side walls, the square can manufacturing device is characterized in that: The square can manufacturing device comprises: a drawing and ironing unit for performing drawing and ironing on a predetermined portion of a cylindrical portion of an intermediate molded product through a gap between a die-processed inner peripheral surface of a die-processed through hole formed in the die and a punch-processed outer peripheral surface formed in a punch inserted into the die-processed through hole, The die processing inner peripheral surface has a die long side wall processing portion for processing a predetermined long side wall portion of the intermediate molded product. The punch processed outer peripheral surface has a punch long side wall processing portion for processing the predetermined long side wall portion. The die and the punch are formed such that, when the punch is inserted into the die-processed through hole in a no-load state, the short-side distance between the central portion of the punch's long-side wall processing portion and the die's long-side wall processing portion is narrower than the short-side distance between the two end portions of the punch's long-side wall processing portion and the die's long-side wall processing portion.

Images