JP2020179419A - Drawing apparatus, drawing method, secondary battery manufacturing apparatus, and secondary battery manufacturing method - Google Patents

Abstract

To provide a drawing apparatus and a drawing method which prevent a sheet thickness of a portion with which a punch tip corner part comes in contact from thinning down, prevent cracking and insufficient strength, and can mold a laminate sheet that has a recess and has a stable strength, and to provide a secondary battery manufacturing apparatus and a secondary battery manufacturing method using the laminate.SOLUTION: A recess is molded in a laminate sheet used in a secondary battery. In a state where the laminate sheet is sandwiched between a die and a stripper, the laminate sheet is drawn into a die hole with a first punch having a contour smaller than that of a standing wall of the recess to be molded. Then, the contour part of the recess is drawn with a second punch arranged on the outer diameter side of the first punch.SELECTED DRAWING: Figure 1

Description

The present invention relates to a draw forming apparatus, a draw forming method, a secondary battery manufacturing apparatus, and a secondary battery manufacturing method.

As shown in FIG. 8A, some secondary batteries have a battery element 1 housed in an exterior body 3 made of a laminated sheet 2 (Patent Document 1). The battery element 1 is made of a resin, which is a positive electrode plate having a positive electrode active material formed on the surface of a metal film-shaped foil material and a negative electrode plate having a negative electrode active material formed on the surface of a metal film-shaped foil material. It is a multi-layered structure in which facing each other via a separator formed of the porous material. The electrodes 4 and 5 are projected from the battery element 1.

As shown in FIG. 8B, the laminated sheet 2 is provided with a pair of recesses 6 (6A) and 6 (6B), and a bending line 7 is formed between the recesses 6A and 6B. That is, the sheet 2 is provided with two divided bodies 8 (8A) and 8 (8B). Then, the battery element 1 is fitted into one of the recesses 6, the laminated sheet 2 is folded along the bending line 7, and the divided bodies 8A and 8B are overlapped with each other. As a result, the element storage portion 9 is formed by the overlapping recesses 6A and 6B, and the battery element 1 is stored in the element storage portion 9. Further, the divided bodies 8A and 8B are welded on the outer peripheral side of the element storage portion 9, and the element storage portion 9 is sealed. As a result, a laminated secondary battery in which the battery element 1 is sealed and stored in the exterior body 3 made of the laminated sheet 2 is formed.

As described above, the laminate sheet 2 is formed with recesses 6 (6A, 6B). Such recesses 6A and 6B are formed by deep drawing. FIG. 9 shows a deep drawing die (drawing machine) 10 for deep drawing, and the drawing machine 10 includes a die 11 having a die hole 11a, a punch member 12, a stripper 13, and the like.

In this case, the laminate sheet 2 is placed on the upper surface of the die 11, and the laminate sheet 2 is narrowed down to the die holes 11a by the punch member 12 while maintaining an appropriate clearance between the punch member 12 and the die hole 11a. The laminated sheet 2 is plastically processed into a three-dimensional shape. At this time, the laminate sheet 2 is set so as to slide on the surface of the die so that it can be slid into the die hole.

In such drawing processing, the laminate sheet 2 is plastically deformed while flowing from the periphery of the die hole 11a toward the die hole at the time of drawing. Therefore, the limit drawing ratio (LDR) can be set high, and the recess 6 can be formed.

By the way, a problem when the processing apparatus shown in FIG. 9 is used will be described with reference to FIG. That is, in the device shown in FIG. 7, first, the stripper 13 and the die 11 hold the laminate sheet 2, and in this state, the punch member 12 is lowered to determine a predetermined space between the punch member 12 and the die hole 11a. The laminated sheet is narrowed down to the die holes by the punch member 12 while maintaining the clearance portion of the above.

Japanese Patent No. 4424053

However, in the device shown in FIG. 7, as the drawing depth increases, the thickness of the laminated sheet at the portion where the pressing surface corner portion (punch tip corner portion) of the punch member abuts decreases, and cracks and strength occur in this thin portion. There will be a shortage. In this case, in order to secure the sheet thickness, the plastic deformation region may be expanded by reducing the friction and increasing the amount of the sheet supplied from the peripheral portion.

However, it is difficult to maintain a constant frictional force due to variations in the material of the sheet used and the stains and wear of the mold over time.

In view of the above problems, the present invention has a draw molding apparatus and a draw molding method capable of forming recesses without cracking or insufficient strength with respect to the laminated sheet, and further, molding is performed without cracks or insufficient strength. Provided is a secondary battery manufacturing apparatus and a method for manufacturing a secondary battery using a laminate having a recessed portion.

The draw forming apparatus of the present invention is a draw forming apparatus for forming a recess in a laminate sheet used for a secondary battery, and comprises a die having a die hole, a stripper holding the laminate sheet together with the die, and a punch member. In the state where the laminated sheet is held by the die and the stripper, the laminated sheet is narrowed down to the die hole by the punch member while maintaining a predetermined clearance between the punch member and the die hole. A first punch whose outer shape is smaller than the rising wall of the recess to be molded, and a first punch which is arranged on the outer diameter side of the first punch to draw the outer diameter of the recess after drawing with the first punch. It is equipped with two punches.

According to the draw forming apparatus of the present invention, first, the first punch is used to draw a portion having an outer shape smaller than the concave portion to be formed. As a result, slack can be formed around the region that is the corner of the recess in the final shape. After that, the outer shape of the concave portion is drawn with the second punch. Therefore, when the portion corresponding to the corner portion of the final shape is formed by the second punch, this portion is extended ahead by the first punch, and the area of the plastic deformation region can be expanded. .. As a result, friction with the laminated sheet is reduced at the corners of the second punch, and the supply of the laminated sheet from the peripheral portion is promoted.

The pressing surface of the first punch can be set to be a rectangular or ring-shaped surface, and the pressing surface of the second punch can be set to be a ring-shaped surface. By setting in this way, the element storage portion in which the battery element is housed can be stably molded.

The corner of the die hole and the corner of the first punch are chamfered, and the radius of curvature of the corner of the first punch facing the corner is larger than the radius of curvature of the corner of the die hole. Even so, the corner portion of the first punch facing the corner portion of the die hole may have an R chamfered shape, and the corner portion of the first punch may have a C chamfered shape. By setting in this way, it is possible to increase the gap between the corner portion of the die hole and the corner portion of the first punch, and it becomes a corner portion in the final shape, and the slack around the region can be increased. .. As a result, the sheet thickness of the portion that comes into contact with the corner portion of the second punch can be further increased, and the sheet can be squeezed stably and deeply without causing cracks or insufficient strength.

The secondary battery manufacturing apparatus of the present invention is a secondary battery manufacturing apparatus using the draw forming apparatus, in which the secondary battery is formed by the draw forming apparatus and laminated sheets having a pair of recesses are folded and stacked. The battery element is hermetically stored in an element storage portion composed of a pair of combined recesses.

According to the secondary battery manufacturing apparatus of the present invention, the battery element is stably housed in the element storage portion composed of a pair of recesses formed without causing cracks or insufficient strength, and the secondary battery is stable in strength. Can be manufactured.

The draw forming method of the present invention is a draw forming method for forming a concave portion with respect to a laminated sheet used for a secondary battery, in which a rising wall of a concave portion to be formed is formed while the laminated sheet is held by a die and a stripper. After the laminated sheet is narrowed down into the die holes by the first punch having a smaller outer diameter than that of the first punch, the outer diameter of the concave portion is drawn by the second punch arranged on the outer diameter side of the first punch. ..

According to the draw forming method of the present invention, in order to perform drawing processing at a portion having an outer shape smaller than the concave portion to be formed by the first punch, slack is formed around the corner portion of the concave portion in the final shape. Can be formed. When the portion corresponding to the corner portion of the final shape is formed by the second punch, this portion is extended ahead by the first punch, and the area of the plastic deformation region can be expanded. As a result, friction with the laminated sheet is reduced at the corners of the second punch, and the supply of the laminated sheet from the peripheral portion is promoted.

The secondary battery manufacturing method of the present invention is a secondary battery manufacturing method using the draw forming method.
A laminate sheet having recesses formed by the drawing method is folded, and a pair of recesses are overlapped to form an element storage portion for sealing and accommodating a battery element.

According to the secondary battery manufacturing method of the present invention, the battery element is stably housed in the element storage portion composed of a pair of recesses formed without causing cracks or insufficient strength, and the secondary battery is stable in strength. Can be manufactured.

In the present invention, the area of the plastic deformation region can be expanded, so that the sheet (film) thickness of the portion abutting on the corner portion of the punch member (the corner portion of the punch surface of the second punch) does not become thin. , Stable draw forming can be performed without cracks or insufficient strength. Therefore, it is possible to provide a high quality product (a laminated sheet in which a recess is formed).

The drawing apparatus of the present invention is shown, (a) is a simplified cross-sectional view of a drawing state of a punch member by a first punch, and (b) is a simplified cross-sectional view of a drawing state of a punch member by a second punch. .. It is an enlarged view which shows the relationship between a punch member and a die hole of a die. It is an enlarged view which shows the modification of the 1st punch of a punch member. It is a main part plan view of the laminated sheet after drawing molding. It is a flowchart which shows the process of the draw forming method of this invention. A secondary battery using a laminated sheet processed (molded) by the draw molding apparatus of the present invention is shown, (a) is a plan view, and (b) is a perspective view showing an assembly method. It is a simplified diagram explaining the conventional drawbacks. A secondary battery using a laminated sheet formed by a conventional drawing molding apparatus is shown, (a) is a plan view, and (b) is a perspective view showing an assembly method. It is a simplified sectional view of the main part of the conventional drawing forming apparatus (drawing forming machine).

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6.

FIG. 1 shows a draw molding die of the draw forming apparatus of the present invention, and this draw forming apparatus molds a laminate sheet 22 in which a recess 26 as shown in FIG. 6 (b) is formed. (A) shows a secondary battery using the laminated sheet 22 processed by the draw forming apparatus, and FIG. 6 (b) shows an assembly drawing of the secondary battery.

As shown in FIGS. 6A and 6B, the secondary battery has a battery element 21 housed in an exterior body 23 made of a laminated sheet 22. The battery element 21 is made of a resin, which is a positive electrode plate having a positive electrode active material formed on the surface of a metal film-shaped foil material and a negative electrode plate having a negative electrode active material formed on the surface of a metal film-shaped foil material. It is a multi-layered structure in which facing each other via a separator formed of the porous material. The electrodes 24 and 25 are projected from the battery element 21. The wall thickness of the laminated sheet 22 is set to about 0.05 mm to 0.2 mm.

The laminated sheet 22 is provided with a pair of recesses 26 (26A) and 26 (26B), and a bending line 27 is formed between the recesses 26 and 26. That is, the laminated sheet 22 is composed of two divided bodies 28 (28A) and 28 (28B). Then, the battery element 21 is fitted into one of the recesses 26A, the laminated sheet 22 is folded along the bending line 27, and the divided bodies 28A and 28B are overlapped with each other. As a result, the element storage portion 29 is formed by the overlapping recesses 26A and 26B, and the battery element 21 is stored in the element storage portion 29. Further, the divided bodies 28A and 28B are welded on the outer peripheral side of the element storage portion 29, and the element storage portion 29 is sealed. As a result, a laminated secondary battery in which the battery element 21 is sealed and stored in the exterior body 23 made of the laminated sheet 22 is formed.

As shown in FIG. 1, the draw forming die of the draw forming apparatus includes a die 31 having a die hole 30, a stripper 32 holding the laminate sheet 22 together with the die 31, and a punch member 33. With the laminate sheet 22 held by the die 31 and the stripper 32, the punch member 33 narrows the laminate sheet 22 to the die hole 30 while maintaining a predetermined clearance between the punch member 33 and the die hole 30. .. In FIG. 1, a pair of die holes 30 of the die 31 is provided, and therefore, a pair of punch members 33 are also provided corresponding to the pair.

The punch member 33 is arranged on the outer diameter side of the first punch 33a, which has a smaller outer shape than the rising wall (peripheral surface) 26a (see FIG. 6) of the recess 26 to be formed, and the recess 26. It is provided with a second punch 33b for drawing the outer shape of the above.

The first punch 33a is made of a flat rectangular body, and the second punch 33b is made of a rectangular ring body arranged on the outer peripheral side of the first punch 33a. In this case, when the die hole 30 of the die 31 has a rectangular shape in a plan view, for example, when the length of the long side thereof is 50 mm to 500 mm and the short side thereof is 50 mm to 300 mm, the long side of the first punch 33a is set. The length of the second punch is 30 mm to 480 mm, the short side thereof is 30 mm to 280 mm, the length of the long side of the outer shape of the second punch 33b is 49 mm to 499 mm, the short side of the outer shape is 49 mm to 299 mm, and the second punch The length of the long side of the inner shape of 33b is 30 mm to 480 mm, the short side of the inner shape is 30 mm to 280 mm, and the thickness dimension (difference between the outer shape and the inner shape) of the second punch 33b is 20 mm to 30 mm. When the clearance between the inner surface of the die hole 30 and the outer surface of the second punch 33b is G (see FIGS. 2 and 3), 0.3 mm ≦ G ≦ 2.0 mm.

Further, as shown in FIG. 2, the corner portion (corner portion 33a1) of the first punch 33a and the corner portion (corner portion 33b1) of the second punch 33b are each R-chamfered, and the corners of the die hole 30 of the die 31 are formed. The part (corner part 30a) is also R-chamfered. In this case, the radius of curvature of the corner portion 33a1 of the first punch 33a is R1, the radius of curvature of the corner portion 33b1 of the second punch 33b is R2, and the radius of curvature of the corner portion 30a of the die hole 30 of the die 31 is R3. Occasionally, R1> R3 and R2≈R3. In this case, R1> R3 and 1/5 ≦ R1 / R3 ≦ 1/2. When the drawing depth is D, 1 mm ≦ D ≦ 10 mm.

Further, as shown in FIG. 3, the corner portion (corner portion 33a1) of the first punch 33a may have a C chamfered shape. In this case, the corner portion 33a1 includes a tapered portion 34 and rounded portions 35, 35 at both ends of the tapered portion 34. In this case, the corner portions are C1 to C10, and the radius of curvature of the rounded portions 35 and 35 is 1 mm to 10 mm.

By the way, since the punch member 33 has the first punch 33a and the first punch 33b, the punch member 33 includes a driving means (not shown) for moving the first punch 33a and the second punch 33b up and down, respectively. As each drive means, known and public reciprocating mechanisms such as a cylinder mechanism, a ball screw mechanism, and a linear guide mechanism can be used. Further, these driving means are controlled by control means (not shown). The control means is, for example, a microcomputer in which a ROM (Read Only Memory), a RAM (Random Access Memory), and the like are connected to each other via a bus centering on a CPU (Central Processing Unit). Further, a storage means (not shown) is connected to the control means. The storage means includes an HDD (Hard Disc Drive), a DVD (Digital Versatile Disk) drive, a CD-R (Compact Disc-Recordable) drive, an EEPROM (Electronically Erasable and Programmable Read Only Memory), and the like. The ROM stores programs and data executed by the CPU.

The stripper 32 can also be moved up and down by a vertical movement mechanism (not shown), and as the vertical movement mechanism, a known and public reciprocating mechanism such as a cylinder mechanism, a ball screw mechanism, and a linear guide mechanism should be used. Can be done. Further, this vertical movement mechanism can also be controlled by the above-mentioned control means (not shown).

Next, the process of drawing with the drawing apparatus configured as described above will be described with reference to FIGS. 1 and 5. First, as shown in FIG. 1A, the die 31 and the stripper 32 are in a state of holding the laminated sheet 22 as a work. In this case, the punch member 33 is positioned above the laminated sheet 22.

Next, as shown in step S1 of FIG. 5, the first punch 33a is lowered. After that, the process proceeds to step S2, and it is determined whether or not the drawing process by the first punch 33a is completed (completed). That is, it is determined whether or not the state shown in FIG. 1A is obtained. In the state shown in FIG. 1A, the portion P2 (see FIG. 4) to be punched by the second punch 33b to be performed next can be extended first. Note that P1 in FIG. 4 shows a portion machined (punched) by the first punch 33a, P3 shows the clearance between the second punch 33b and the die hole 30 of the die 31, and P4 shows the die 31.

If the drawing process by the first punch 33a is completed in step S2, the process proceeds to step S3, and if the drawing process by the first punch 33a is not completed, the process waits until the drawing process is completed. In step S3, the second punch 33b is lowered while the first punch 33a is lowered. After that, the process proceeds to step S4, and it is determined whether or not the drawing process by the second punch 33b is completed (completed). That is, it is determined whether or not the state shown in FIG. 1 (b) is obtained.

If the drawing process by the second punch 33b is completed in step S4, the process proceeds to step S5, and if the drawing process by the second punch 33b is not completed, the process waits until the drawing process is completed. In step S5, the first punch 33a and the second punch 33b are raised to end this processing. As a result, the laminated sheet 22 having a pair of recesses 26 (26A) and 26 (26B) as shown in FIG. 6B can be formed.

If the laminated sheet 22 having the pair of recesses 26 (26A) and 26 (26B) is formed in this way, as described above, the laminated sheet 22 is used as shown in FIG. 6A. The next battery can be manufactured.

In the draw forming apparatus of the present invention, first, the first punch 33a is used to draw a portion having an outer shape smaller than the recess 26 to be formed. As a result, slack can be formed around the region to be the corner of the recess 26 in the final shape. After that, the outer shape of the concave portion 26 is drawn by the second punch 33b. Therefore, when the portion corresponding to the corner portion of the final shape is formed by the second punch 33b, this portion P2 (see FIG. 4) is extended ahead by the first punch 33a, and the plastic deformation region. The area of can be expanded. As a result, friction with the laminated sheet 22 is reduced at the corners of the second punch 33b, and the supply of the laminated sheet from the peripheral portions is promoted as shown by arrows A and A shown in FIGS. 2 and 3.

That is, the area of the plastic deformation region can be expanded, so that the sheet (film) thickness of the portion abutting on the corner portion of the punch member 33 (the corner portion of the punch surface of the second punch 33b) does not become thin. It is possible to perform stable draw forming without cracks or insufficient strength, and to provide a high-quality product (laminated sheet 22 in which the recess 26 is formed).

The pressing surface (punch surface) of the first punch 33a can be set to be rectangular, and the pressing surface (punch surface) of the second punch 33 can be set to be a ring-shaped surface. By setting in this way, the element storage portion 29 (the storage portion in which the pair of recesses 26, 26 are overlapped) in which the battery element 21 is housed can be stably molded. Further, the first punch 33a may be formed of a rectangular ring body in which the punch surface is a rectangular ring surface. Even in such a case, the element storage portion 29 in which the battery element 21 is housed can be stably molded. When a rectangular ring body is used as the first punch 33a, its outer shape is the same as that of the first punch 33a whose pressing surface (punch surface) is rectangular, and its inner shape is 30 mm to 280 mm on its short side. The length of the long side of the outer shape of the second punch 33b can be set to 30 mm to 480 mm.

The corner portion 30a of the die hole 30 and the corner portion 32a1 of the first punch 32a are R-chamfered, and the corner of the first punch 33a facing the corner portion 30a rather than the radius of curvature of the corner portion 30a of the die hole 30. Even if the radius of curvature of the portion 33a1 is increased, the corner portion 33a1 of the first punch 33a facing the corner portion 30a of the die hole 30 has an R-chamfered shape, and the corner portion 33a1 of the first punch 33a is formed. May have a C-chamfered shape. By setting in this way, it is possible to make a large gap between the corner portion 30a of the die hole 30 and the corner portion 33a1 of the first punch 33a, which becomes a corner portion in the final shape and increases the slack around the region. Can be taken. As a result, the sheet thickness of the portion abutting on the corner portion of the second punch 33b can be further increased, and the sheet can be squeezed stably and deeply without causing cracks or insufficient strength.

In the secondary battery manufacturing apparatus and the secondary battery manufacturing method of the present invention, a sheet body (laminated sheet 22) having a recess 26 processed with high precision can be supplied, so that a high quality secondary battery can be manufactured. it can.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the embodiment, when punching with the second punch 33b, the first punch 33a is lowered without being raised. However, the second punch 33b may be lowered after the first punch 33a is raised or while the first punch 33a is raised. Further, as the mold device, the die hole 30 may be one, and the punch member 33 may be one correspondingly. The radius of curvature of the corner portion 33a1 of the first punch 33a and the radius of curvature of the corner portion 30a of the die hole 30 of the die 31 may be set to the same dimensions. Here, the same dimension includes a range within the dimensional tolerance.

21 Battery element 22 Laminated sheet 26 Recessed 26a Rising wall 29 Element storage part 30 Die hole 30a Corner part 31 Die 32 Stripper 33 Punch member 33a First punch 33a 1 Corner part 33b Second punch

Claims (7)

In a draw forming device that forms a recess in a laminated sheet used for a secondary battery,
A die with a die hole, a stripper that holds a laminated sheet with this die, and
It is provided with a punch member, and the laminated sheet is narrowed down to the die hole by the punch member while maintaining a predetermined clearance between the punch member and the die hole while the laminated sheet is held by the die and the stripper.
The punch member has a first punch having an outer shape smaller than the rising wall of the concave portion to be formed, and after drawing with the first punch, the punch member is arranged on the outer diameter side of the first punch to form an outer diameter portion of the concave portion. A draw forming apparatus including a second punch for drawing. The draw forming apparatus according to claim 1, wherein the pressing surface of the first punch is a rectangular to ring-shaped surface, and the pressing surface of the second punch is a ring-shaped surface. The corner portion of the die hole and the corner portion of the first punch are R-chamfered, and the radius of curvature of the corner portion of the first punch facing the corner portion is made larger than the radius of curvature of the corner portion of the die hole. The draw forming apparatus according to claim 1 or 2, wherein the drawing apparatus is characterized. Claim 1 or claim 2 is characterized in that the corner portion of the first punch facing the corner portion of the die hole has an R chamfered shape, and the corner portion of the first punch has a C chamfered shape. The draw forming apparatus according to. A secondary battery manufacturing apparatus using the draw forming apparatus according to any one of claims 1 to 4.
The secondary battery is characterized in that the battery element is hermetically sealed and stored in an element storage portion composed of a pair of recesses in which a laminate sheet in which a recess is formed by the drawing molding apparatus is folded and overlapped. Battery manufacturing equipment. In a draw forming method for forming a recess in a laminated sheet used for a secondary battery,
With the laminate sheet held by the die and stripper, the laminate sheet is narrowed down into the die holes with the first punch, which has a smaller outer shape than the rising wall of the recess to be molded, and then the outer diameter side of the first punch. A drawing forming method characterized in that the outer shape of a concave portion is drawn with a second punch arranged in. A method for manufacturing a secondary battery using the draw forming method according to claim 6.
A method for manufacturing a secondary battery, which comprises folding a laminated sheet having recesses formed by the drawing molding method and superimposing a pair of recesses to form an element storage portion for sealing and accommodating a battery element.

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