Method for manufacturing battery case

Abstract

To provide a method for manufacturing a battery case that can simplify a manufacturing process while suppressing damage to a workpiece during processing.SOLUTION: In manufacturing a battery case, a plate-like steel sheet A made of metal is clamped between a molding die 18 with a cavity part 24 and a wrinkle holding part 20, and when the steel sheet A is pushed toward the cavity part 24 side in a core part 22, a pad part 28 in the cavity part 24 is pushed into a recess 42 in the core part 22 so that an expansion part AA is formed on a predetermined wall part of the steel sheet A on the side opposite to the core part 22. By moving a movable part 38 movable relative to the molding die 18, the expansion part AA is extended, and by pressing the movable part 38 against a forming surface part 24A of the cavity part 24 with the steel sheet A in between, the steel sheet A is provided with a corner part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a battery case. [Background technology]

[0002] Patent Document 1 below discloses an invention relating to a multi-stage forming method for deep-drawn prismatic iron cans. In this forming method, damage to the workpiece during processing is suppressed by setting the rate of increase in height of the drawn can at each position from the long side to the short side of the drawn can to a predetermined value or less in the multi-stage drawing process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-056530 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as mentioned above, if the height increase rate of the drawn can is set in a specified drawing process, it may become necessary to increase the number of drawing processes depending on the shape of the product, which may complicate the manufacturing process.

[0005] In consideration of the above, an object of the present invention is to provide a method for manufacturing a battery case that can simplify the manufacturing process while suppressing damage to the workpiece during processing. [Means for solving the problem]

[0006] The manufacturing method for a battery case according to the first aspect involves clamping a metal plate-shaped workpiece between a mold having a cavity portion and a wrinkle suppressor, and when the workpiece is pressed toward the cavity portion with a core portion, the convex portion provided in the cavity portion is pressed into the concave portion provided in the core portion, thereby forming a bulge portion that bulges out on the opposite side of the core portion from a predetermined wall portion of the workpiece, and extending the bulge portion by moving a movable portion that is movable relative to the mold, and forming a corner portion in the workpiece by pressing the movable portion against the molding surface portion of the cavity portion or the molding surface portion of the core portion through the workpiece.

[0007] According to the battery case manufacturing method of the first aspect, a metal plate-shaped workpiece is sandwiched between a forming die with a cavity formed therein and a blank holder, and then, by performing a so-called drawing process in which the workpiece is pressed into the cavity by the core, a storage portion for storing a battery cell can be formed in the battery case.

[0008] However, in the above-described drawing process, it is conceivable that a load may be locally applied to the workpiece depending on the shape of the product, such as when the product has corners, etc. To prevent this, it may be necessary to divide the drawing process into multiple stages, which may complicate the manufacturing process.

[0009] Here, in this embodiment, when the workpiece is pushed toward the cavity portion by the core portion, the convex portion provided in the cavity portion is pushed into the concave portion provided in the core portion, thereby forming a bulge portion that bulges out on the opposite side of the core portion from a specified wall portion of the workpiece, i.e., a specified wall portion of the above-mentioned storage portion.

[0010] Then, by moving the movable part that is movable relative to the molding die, the bulge formed in the workpiece is extended, and by pressing the movable part against the molding surface part of the cavity part or the molding surface part of the core part through the workpiece, a corner part is formed in the workpiece.

[0011] In this manner, in this aspect, by forming a bulge in the workpiece, a deformation allowance is ensured when forming a corner in the workpiece, and it is possible to suppress localized load on the workpiece when forming the corner in the workpiece. Also, in this aspect, by forming a bulge in the workpiece, it is possible to form a corner in the workpiece without performing the drawing process in multiple stages.

[0012] A second aspect of the method for manufacturing a battery case is the same as the first aspect, except that the bulge is formed along the peripheral edge of a portion of the workpiece that will become the bottom wall of the battery case.

[0013] According to the manufacturing method of the battery case of the second aspect, a bulge portion, which is a deformation allowance when forming a corner in the workpiece, is formed along the peripheral portion of the part of the workpiece that will become the bottom wall portion of the battery case, thereby making it possible to prevent cracks and the like from occurring in the bottom wall portion of the battery case, which is the manufactured product.

[0014] A third aspect of the manufacturing method for a battery case is the same as the first or second aspect of the manufacturing method for a battery case, except that the position of the movable part is set so that the corners are right-angled when viewed from the thickness direction of the part of the workpiece that will become the bottom wall of the battery case, and the distance between the tops of adjacent corners is 0.5 m or more and 3 m or less.

[0015] According to the manufacturing method of the battery case of the third aspect, the position of the movable part is set so that the corner formed in the workpiece is right-angled when viewed in the thickness direction of the part of the workpiece that will become the bottom wall of the battery case. That is, in this aspect, the workpiece is processed so that the bottom wall of the battery case is rectangular. Note that the right-angled shape mentioned above includes not only a shape in which the tip of the corner is right-angled, but also a shape in which the tip is an arc-shaped corner with a small diameter.

[0016] In this embodiment, the position of the movable part is set so that the distance between the tops of adjacent corners is 0.5 m to 3 m when viewed in the thickness direction of the portion of the workpiece that will become the bottom wall of the battery case. This makes it possible to prevent cracks and other problems from occurring in the workpiece during the manufacture of a battery case having a rectangular bottom wall with a side length of 0.5 m to 3 m. [Effects of the Invention]

[0017] As described above, the method for manufacturing a battery case according to the present invention has the excellent effect of being able to simplify the manufacturing process while suppressing damage to the workpiece during processing. [Brief explanation of the drawings]

[0018] [Figure 1] 1A and 1B are schematic diagrams showing the configuration of a battery case molded by a battery case manufacturing method according to a first embodiment, in which (A) is a cross-sectional view of the battery case (a cross-sectional view showing the state cut along line 1A-1A in (B)), and (B) is a plan view of the battery case. [Figure 2] 1A to 1D are plan views schematically showing the molding process of a battery case by a manufacturing method of a battery case according to a first embodiment, where (A) shows a first state, (B) shows a second state, (C) shows a third state, and (D) shows a fourth state. [Figure 3] 1A to 1D are cross-sectional views schematically showing the molding process of a battery case by a manufacturing method of a battery case according to a first embodiment, where (A) shows a first state, (B) shows a second state, (C) shows a third state, and (D) shows a fourth state. [Figure 4] 10A to 10D are plan views schematically showing the molding process of a battery case by a manufacturing method of a battery case according to a second embodiment, where (A) shows a first state, (B) shows a second state, (C) shows a third state, and (D) shows a fourth state. [Figure 5]10A to 10D are cross-sectional views schematically showing the molding process of a battery case by a manufacturing method of a battery case according to a second embodiment, where (A) shows a first state, (B) shows a second state, (C) shows a third state, and (D) shows a fourth state. [Figure 6] 10A to 10C are plan views schematically showing the molding process of a battery case by a manufacturing method for a battery case according to a modified example of the second embodiment, where (A) shows the second state, (B) shows the third state, and (C) shows the fourth state. [Figure 7] 10A to 10C are cross-sectional views schematically showing the molding process of a battery case by a manufacturing method for a battery case according to a modified example of the second embodiment, where (A) shows the second state, (B) shows the third state, and (C) shows the fourth state. DETAILED DESCRIPTION OF THE INVENTION

[0019] First Embodiment A first embodiment of a method for manufacturing a battery case according to the present invention will be described below with reference to FIGS. 1 to 3. First, the configuration of a "battery case 10 (hereinafter referred to as case 10)" manufactured by the method for manufacturing a battery case according to this embodiment will be described with reference to FIG. 1. Note that arrow X, as appropriately shown in each drawing, indicates one side of the longitudinal direction of case 10, arrow Y indicates one side of the lateral direction of case 10, and arrow Z indicates one side of the height direction of case 10. Furthermore, hereinafter, unless otherwise specified, the longitudinal direction of case 10 will be simply referred to as the longitudinal direction, the lateral direction of case 10 will be simply referred to as the lateral direction, and the height direction of case 10 will be simply referred to as the height direction. Note that one of the longitudinal direction, lateral direction, and height direction is perpendicular to the remaining two directions.

[0020] As shown in Figures 1(A) and 1(B), the case 10 is made of steel plate and includes a storage section 10A that forms the main part of the case and houses multiple battery cells 12, and a flange section 10B that forms one side of the case in the height direction.

[0021] The storage section 10A is box-shaped with one side open in the height direction and includes a bottom wall portion 10A1 that forms the other side in the height direction, has a thickness direction as the height direction, and is rectangular when viewed from the height direction, a pair of side wall portions 10A2 that extend in the longitudinal direction and are spaced apart from each other in the short direction, and a pair of side wall portions 10A3 that extend in the short direction and are spaced apart from each other in the longitudinal direction.

[0022] Furthermore, when viewed from the height direction, the "corners 10A4" of the storage section 10A are right-angled, and the distance between the tops of adjacent corners 10A4 in the longitudinal or lateral direction is set to be 0.5 m or more and 3 m or less. Note that the right-angle shape mentioned above includes not only a shape in which the tip of the corner 10A4 is a right angle, but also a shape in which the tip is a small-diameter arc.

[0023] A plurality of battery cells 12 are arranged in series in the longitudinal direction within the housing section 10A. The battery cells 12 may be all-solid-state batteries or secondary batteries containing an electrolyte solution.

[0024] Next, the configuration of press molding device 16 (hereinafter referred to as device 16) used to manufacture case 10 will be described. Note that the directions of press molding device 16 will follow the directions of case 10 when case 10 is molded by press molding device 16. In other words, the lower side of device 16 in the height direction is one side of case 10 in the height direction, and the upper side of device 16 in the height direction is the other side of case 10 in the height direction.

[0025] 3(A), it includes a "forming die 18," a "wrinkle holder 20," and a "core 22." The forming die 18 is formed of metal in a rectangular parallelepiped shape, and forms the storage section 10A of the case 10 and includes a "cavity 24" that is open on one side in the height direction.

[0026] In addition, a recess 26 recessed toward the other side in the height direction is formed in the central portion of the bottom surface portion 24A1, which constitutes the other side in the height direction of the "molding surface portion 24A" of the cavity portion 24, and a "pad portion 28" serving as a protrusion is provided within this recess 26.

[0027] Pad portion 28 is made of metal and has a rectangular plate shape when viewed in the height direction, and is movable in the height direction by cylinder 30. Pad portion 28 can be placed in a protruding state in which a molding surface 28A on one side in the height direction is positioned to one side in the height direction relative to bottom surface 24A1 of cavity portion 24, and a contained state in which molding surface 28A is positioned on the same plane as bottom surface 24A1. In the contained state, a spacer 32 is interposed between pad portion 28 and molding die 18.

[0028] On the other hand, the blank holder 20 is made of metal and has a plate shape with its thickness direction as its height direction, and as shown in Fig. 2(A) , it has a through hole 34 through which the housing 10A can be inserted. When the case 10 is molded, the "steel plate A" as the workpiece is sandwiched between the periphery of the cavity 24 in the molding die 18 and the periphery of the through hole 34 in the blank holder 20.

[0029] Returning to Figure 3(A), the core portion 22 comprises a metal main body portion 36 which constitutes its main part, and four "movable portions 38", and is shaped as a rectangular cuboid when viewed from the height direction overall.

[0030] More specifically, the main body 36 is movable in the height direction relative to the forming die 18 by a cylinder (not shown), and recesses 40 are formed at each of the four corners of the main body 36 when viewed in the height direction. Each of these recesses 40 houses a movable portion 38.

[0031] The movable part 38 is generally in the shape of a quadrangular prism that extends in the height direction and is rectangular when viewed in the height direction, and can be moved between a first position where it fits into the recess 40 and a second position away from the main body part 36 by a movement mechanism such as a cylinder (not shown) (see FIG. 2). In other words, the movable part 38 is movable relative to the forming die 18 and the main body part 36.

[0032] Furthermore, when the movable part 38 is in the first position, an end face 38A on the other height direction side of the movable part 38 is located on the other height direction side of the end face 36A on the other height direction side of the main body part 36, with a predetermined gap being maintained in the height direction between the end face 38A and the end face 36A. In other words, when the movable part 38 is in the first position, a "recess 42" is provided in the portion of the core part 22 on the other height direction side.

[0033] On the other hand, when the movable portion 38 is in the second position, the end surface 38A is located on the same plane as the end surface 36A. The end surface 36A of the main body 36 has the same shape as the pad portion 28 when viewed from the height direction, and the pad portion 28 is arranged so that it entirely overlaps the end surface 36A when viewed from the height direction.

[0034] (Actions and Effects of This Embodiment) Next, the operation and effects of this embodiment will be described.

[0035] A method for manufacturing the case 10 using the device 16 according to this embodiment will be described below. In the method for manufacturing the case 10 according to this embodiment, as shown in Figures 2(A) and 3(A), first, a "steel plate A" as a workpiece is clamped between a forming die 18 having a cavity 24 formed therein and a blank holder 20.

[0036] Then, as shown in Figures 2(B) and 3(B), by performing a so-called drawing process in which the steel plate A is pressed into the cavity portion 24 by the core portion 22, it is possible to form the storage portion 10A in the case 10 in which the battery cell 12 is stored.

[0037] In the above-described drawing process, depending on the shape of the manufactured product, such as if the manufactured product has corners, it is conceivable that a load may be locally applied to the steel sheet A. To prevent this, it may be necessary to divide the drawing process into multiple stages, which may complicate the manufacturing process.

[0038] Here, in this embodiment, as shown in Figures 2(C) and 3(C), when the steel plate A is pressed toward the cavity portion 24 by the core portion 22, the protruding pad portion 28 provided in the cavity portion 24 is pressed into the recess 42 provided in the core portion 22, thereby forming a "bulge portion AA" that bulges out on the opposite side of the core portion 22 from a predetermined wall portion of the steel plate A, i.e., the portion that becomes the bottom wall portion 10A1 of the storage portion 10A.

[0039] 2(D) and 3(D), the movable part 38, which is movable relative to the forming die 18, is moved while the pad part 28 is in a housed state, thereby extending the bulge part AA formed in the steel plate A. At this time, the movable part 38 is pressed against the forming surface part 24A of the cavity part 24 via the steel plate A, thereby forming a corner part 10A4 in the steel plate A, and the forming of the case 10 is completed.

[0040] As described above, in this embodiment, by forming the bulge portion AA in the steel sheet A, a deformation allowance is ensured when forming the corner portion 10A4 in the steel sheet A, and it is possible to suppress localized load on the steel sheet A when forming the corner portion 10A4 in the steel sheet A. Furthermore, in this embodiment, by forming the bulge portion AA in the steel sheet A, it is possible to form the corner portion 10A4 in the steel sheet A without performing the drawing process in multiple stages.

[0041] Furthermore, in this embodiment, as shown in FIG. 2(C), a bulge portion AA, which is a deformation allowance when forming a corner portion 10A4 in the steel plate A, is formed along the peripheral portion of the portion of the steel plate A that will become the bottom wall portion 10A1 of the case 10, thereby preventing cracks and the like from occurring in the bottom wall portion 10A1 of the manufactured case 10.

[0042] In this embodiment, the case 10 can be molded by moving the core portion 22 once relative to the molding die 18, and therefore the case 10 can be considered to be molded in one step.

[0043] In this way, the manufacturing method of the battery case according to this embodiment can simplify the manufacturing process while suppressing damage to the steel plate A during processing.

[0044] Second Embodiment A second embodiment of the method for manufacturing a battery case according to the present invention will be described below with reference to Figures 4 and 5. Note that the same components as those in the first embodiment described above are designated by the same reference numerals, and their description will be omitted.

[0045] The method for manufacturing a battery case according to this embodiment has a first feature in that preforming is performed using a "forming die 50" and a "core portion 52." A second feature is that corners 10A4 of the case 10 are formed by a "core portion 54" and a "movable portion 56."

[0046] In detail, as shown in Figures 4(A) and 5(A), the molding die 50 is formed of metal in a rectangular parallelepiped shape as a whole, and is provided with a "cavity portion 58" that is used to preform the storage portion 10A of the case 10 and is open on one side in the height direction.

[0047] Furthermore, a "protrusion 50A" protruding from bottom surface 58A1 to one side in the height direction is provided in a central portion of bottom surface 58A1 that constitutes the other height-wise side portion of "molding surface 58A" of cavity 58. This protrusion 50A has a rectangular shape with four sides recessed toward the center of molding die 50 when viewed in the height direction.

[0048] The core portion 52 is made of metal and has a rectangular parallelepiped shape when viewed from the height direction. A recess 60 is formed in the center of the molding surface portion 52A on the other side of the core portion 52 in the height direction, into which the protrusion 50A fits.

[0049] Furthermore, the molding surface portions 52B on one longitudinal side and the other longitudinal side of the core portion 52 and the molding surface portions 52C on one lateral side and the other lateral side of the core portion 52 are convex and concave toward the center of the core portion 52 when viewed from the height direction.

[0050] 4(B) and 5(B), the core portion 54 has a rectangular parallelepiped shape when viewed in the height direction, and unlike the core portion 22, does not have a movable portion 38. The core portion 54 is movable in the height direction relative to the molding die 18 by a cylinder (not shown).

[0051] Four movable parts 56 are provided for the forming die 18, and each is shaped like a block when viewed from the height direction, with recesses 56A formed therein into which corners 54A of the core part 54 are fitted. The movable parts 56 can be moved by a movement mechanism such as a cylinder (not shown) between a first position at which they are spaced a predetermined distance from the core part 54, and a second position in which they are in contact with the core part 54 via the steel plate B (see FIG. 5). In other words, the movable parts 56 are movable relative to the forming die 18 and the core part 54.

[0052] In this embodiment, the pad portion 28 and the core portion 54 have the same shape when viewed from the height direction, and the pad portion 28 is arranged so that it completely overlaps with the core portion 54 when viewed from the height direction.

[0053] 4(A) and 5(A), in the manufacturing method according to this embodiment, a "steel plate B" as a workpiece is clamped between a forming die 50 having a cavity 58 formed therein and a blank holder 20, and the steel plate B is pressed into the cavity 58 by the core 52, thereby preforming the accommodation portion 10A. At this time, the protrusion 50A provided in the cavity 58 is pressed into the recess 60 provided in the core 52, thereby forming a "bulge BA" that bulges outward from a predetermined wall portion of the steel plate B, i.e., a portion that will become the bottom wall 10A1 of the accommodation portion 10A, on the opposite side to the core 52.

[0054] At this time, a bulge BB is formed in the steel plate B along the molding surface portion 52B and the molding surface portion 52C of the core portion 52.

[0055] Next, as shown in Figures 4(B) and 5(B), the core portion 52 is pulled out from the preformed portion of the steel plate B as described above, and the core portion 54 is pushed into this portion, thereby extending the bulge portion BB formed in the steel plate B.

[0056] Next, as shown in Figures 4(C) and 5(C), the pad portion 28 is pressed against the core portion 54 via the steel plate B, thereby moving the bulging portion BA of the steel plate B to the side of the core portion 54.

[0057] Then, as shown in Figures 4(D) and 5(D), the movable part 56 is pressed against the core part 54 via the steel plate B, thereby extending the bulge part BA formed in the steel plate B and forming a corner part 10A4 in the steel plate B, thereby completing the molding of the case 10.

[0058] As described above, the method for manufacturing a battery case according to this embodiment also provides the same functions and effects as those of the first embodiment described above.

[0059] <Derivative example of the second embodiment> A modified example of the second embodiment of the method for manufacturing a battery case according to the present invention will be described below with reference to FIGS.

[0060] The manufacturing method of the battery case according to this modification is characterized in that the pad portion 28 and the movable portion 56 are divided into a plurality of parts.

[0061] 7(A), the pad section 28 includes a first pad section 28B that forms the central portion of the pad section 28 when viewed in the height direction, and a plurality of second pad sections 28C that are arranged around the first pad section 28B. The first pad section 28B and the plurality of second pad sections 28C can each move independently in the height direction.

[0062] 6(A), the movable portion 56 includes a first movable portion 56B that is movable in the longitudinal direction and a second movable portion 56C that is movable in the lateral direction. Also, as shown in FIG. 6(C), when the movable portion 56 is in the second position, a side surface 56B1 of the first movable portion 56B facing the core portion 54 and a side surface 56C1 of the second movable portion 56C facing the core portion 54 are orthogonal to each other when viewed from the height direction.

[0063] In the manufacturing method according to this modification, after preforming the accommodation portion 10A shown in Figures 4(A) and 5(A), the core portion 54 is pressed into the preformed portion of the steel plate B, as shown in Figures 6(A) and 7(A), thereby extending the bulge portion BB formed in the steel plate B. In addition, the first pad portion 28B is pressed against the core portion 54 via the steel plate B.

[0064] Next, as shown in Figures 6(B) and 7(B), the second pad portion 28C is pressed against the core portion 54 via the steel plate B, thereby moving the bulge portion BA of the steel plate B toward the side of the core portion 54.

[0065] Then, as shown in Figures 6(C) and 7(C), the side surface 56B1 of the first movable part 56B and the side surface 56C2 of the second movable part 56C are pressed against the core part 54 via the steel plate B, thereby extending the bulge portion BA formed in the steel plate B and forming a corner portion 10A4 in the steel plate B, thereby completing the molding of the case 10.

[0066] As described above, the manufacturing method of the battery case according to this modified example also achieves the same functions and effects as those of the above-described embodiment 2. Furthermore, in this modified example, the pad portion 28, which is divided into multiple parts, and the movable portion 56, which is divided into multiple parts, extend the bulge portion BA formed on the steel plate B, thereby further improving the accuracy with which the corner portion 10A4 is formed into a predetermined shape.

[0067] In the above-described embodiment, the corner 10A4 of the case 10 was formed using a movable part, but depending on the shape of the case 10, a movable part may also be used to form the corner at the boundary between the bottom wall 10A1 and the side wall 10A2 of the case 10 or the corner at the boundary between the bottom wall 10A1 and the side wall 10A3.

[0068] In the above-described embodiment, the movable part is displaced by a moving mechanism, but the configuration for moving the movable part is not limited to this. For example, the movable part may be moved by transmitting a driving force from the molding die 18 to the movable part via an intervening member. Furthermore, the direction in which the movable part moves is not limited to the longitudinal direction, lateral direction, or height direction, and may be set to a direction inclined relative to these directions. [Explanation of symbols]

[0069] 10 Battery case 10A1 Bottom wall 10A4 Corner 18 Molding mold 20 Wrinkle holder 22 Core 24 Cavity 24A Molding surface part 28 Pad part (convex part) 38 Moving parts 42 recess 50 mold 50A convex part 52 Core 52A Molding surface part 56 Moving parts 58 Cavity 58A Molding surface part 60 recess A Steel plate (work material) AA bulge B Steel plate (work material) BA bulge

Claims

1. A metal plate-shaped workpiece is sandwiched between a forming die having a cavity and a blank holder, When the core portion presses the workpiece toward the cavity portion, a convex portion provided in the cavity portion is pressed into a concave portion provided in the core portion, thereby forming a bulging portion that bulges out toward the opposite side of the core portion with respect to a predetermined wall portion of the workpiece, extending the bulging portion by moving a movable portion that is movable relative to the molding die; a corner portion is formed in the workpiece by pressing the movable portion against the molding surface portion of the cavity portion or the molding surface portion of the core portion through the workpiece; A manufacturing method for a battery case.

2. The bulge is formed along a peripheral edge of a portion of the workpiece that will become a bottom wall of the battery case. The method for manufacturing the battery case according to claim 1 .

3. the position of the movable part is set so that the corners are right-angled when viewed from the plate thickness direction of the portion of the workpiece that will become the bottom wall of the battery case, and so that the distance between the tops of the adjacent corners is 0.5 m or more and 3 m or less. The method for manufacturing the battery case according to claim 1 or 2.

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