JP2002331309A - Method for bending and forming thin plate, manufacturing method for die and sealed secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a thin plate excellent in manufacturing efficiency and a forming die therefore, and a manufacturing method for a sealed secondary battery. SOLUTION: The bending work comprises a preliminary bending step which performs bending from the bending base point of hemming potions 6a, 6b by a punch 12 and an opposed die 13 after the tip end of the punch 12 forming No.1 press die is held in the position where the tip end does not press a bending base point of hemming portions 6a, 6b, and an acute angle bending step which acutely forms hemming portions 6a, 6b against the side wall of a cylinder 1 by pressing in the side wall direction of the cylinder 1 by the die 19 which forms No.2 press die against hemming portions 6a, 6b bent in the preliminary bending step.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bending a thin plate, a mold used for the method, and a method for manufacturing a sealed secondary battery using the same.

[0002]

2. Description of the Related Art In recent years, as electronic devices such as personal computers and mobile phones have become smaller, lighter, and cordless, their driving power sources are smaller, lighter, have a higher energy density, and can be repeatedly charged and discharged. The demand for the next battery is increasing. As this kind of sealed secondary battery, for example, one using lithium, a lithium alloy, or the like as a negative electrode active material, and using an oxide, sulfide, or selenide such as vanadium, titanium, molybdenum, or niobium as a positive electrode active material It has been known. Recently, lithium ion secondary batteries using carbon as the negative electrode active material and lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide as the positive electrode active material have been developed and commercialized.

[0003] In addition to coins and cylinders, secondary batteries have a rectangular shape due to demands for thinner and space-saving devices.
There is also a growing demand for sealed secondary batteries, such as oval, that have excellent volume efficiency when stored.

[0004] As an example of the form of this sealed secondary battery, as shown in FIG. 2, a battery container is formed by subjecting a predetermined portion of a laminated plate obtained by laminating a plastic layer to both surfaces of an aluminum thin plate to deep-drawing or the like. Forming a concave part,
The laminated plates 2 and 3 are bent so that the plastic layers of the opposed portions are in close contact with each other, and the close contact portions are heat-sealed to form a closed container 1.
Are also used. In this case, a power generating element (not shown), an electrolytic solution (not shown), and the like required as a secondary battery are housed in the sealed container 1 formed by the facing laminate plates 2 and 3, and are placed from one side. The positive electrode and the negative electrode extend outside.

[0005] In this case, the laminated portions 2a, 4b, 5
Each of a and 5b is required to have a hermeticity with a predetermined strength so as not to leak the internal electrolytic solution and the like to the outside. For this reason, a certain bonding area is required. However, as shown in FIG. 1, if the area of the mating portions 4a, 4b, 5a, and 5b spreads out in a plane, it is not preferable for downsizing the battery. From these circumstances, as shown in FIG.
Edge bending portions 6a and 6b are formed by bending the a and b. As a result, even if the bonding area is the same, the spread area is reduced and the battery is downsized. The formation of the edge bent portions 6a and 6b also contributes to an increase in the shape strength of the battery.

Next, a description will be given of a method of forming the edge bent portions 6a and 6b by bending the mating portions 4a, 4b, 5a and 5b where the opposing laminate plates 2 and 3 are in close contact.

FIGS. 5 (a) to 5 (c) and FIGS. 6 (a) to 6 (c) are schematic views showing a bending process. Since the bending process is formed by a bending erecting step and a bending forming step, FIGS. 5A to 5C illustrate a bending erecting step, and FIGS. 6A to 6C illustrate a bending forming step. Is shown.

In the bending and erecting step, first, a work W is set on a work guide 42 provided on a die 41 which is a fixed side of a first press device (not shown) (a). By lowering the movable work holder 43 and the punch 44, the work W is first restrained by the work holder 43 and the knockout 45. Further, the work W moves in the die 41 as the punch 44 descends while pressing the work W, and the edge bending portions 6a and 6b are bent and rise (b). Further, the edge bending portions 6a and 6b are raised at right angles along the side surface of the punch 44 by pressing from the side surface direction of the die 41 (c). FIG. 5D is an enlarged view of the punch 44 and the edge bending portions 6a and 6b at that time. The tip of the punch 44 is in close contact with the raised inner diameter of the edge bending portions 6a and 6b.

Next, as shown in FIGS. 6 (a) to 6 (c), the work W, the end of which has been formed in the bending and erecting step, is moved to the work table on the fixed side of the second press device. It is placed at a position facing the work holder 53 on the movable side between the inclined dies 52, which are the predetermined positions of 51 (a). Next, the work holder 53 is lowered to move the work W to the work table 5.
1 (b). Further, the inclined die 52 is actuated in the direction of the work W, and the work W is pressed in the shape of the inclined surface of the inclined die 52 to perform side processing, thereby forming a right-angled rising portion of the work W into a predetermined shape (c). .

[0010] At the time of these processes, the bending and erecting step is a forming process in which the ambient temperature is 100 ° C to 140 ° C and the processing time is 5 seconds. On the other hand, in the bending process, the ambient temperature is room temperature, and the processing time is 10 seconds.

[0011]

However, in the above-described molding process, the processing time is different between the bending erecting process and the bending process. Therefore, when the manufacturing process is formed in a series of lines, a waiting time is required when the process proceeds to the bending process after the bending and erecting process.

Further, the laminate sheet material used as the laminate plate is significantly weaker in material strength than the metal sheet material, and thus is easily deformed by an external force.
The punch in the bending and erecting process is working while pressing the work. Therefore, as shown in FIG. 5C, the position of the punch 44 needs to be outside the rising position of the edge bending portions 6a and 6b of the closed container 1. Furthermore, the shape must be sufficient to withstand the processing load. Therefore, the outer dimensions after the bending and erecting step are the sum of the rising positions of the edge bending portions 6a and 6b of the closed container 1 and the width of the punch 44. As a result, a gap corresponding to the shape of the punch 44 is formed between the closed container 1 and the edge bending portions 6a and 6b. Therefore, in the bending process, the edge bending portions 6a and 6b are easily deformed by pressing the inclined die from the side,
This has been a cause of failures such as crushing, root swelling downward, and liquid leakage from the sealed container 1. Further, a change with time after molding is likely to occur.

Further, since the bending position is located outside the sealing portion of the closed container in terms of shape, the external dimensions cannot be made smaller than the bending position.

The present invention has been made based on these circumstances, and an object of the present invention is to provide a method of forming a thin plate having excellent production efficiency, a mold used therefor, and a method of manufacturing a sealed secondary battery using the same. .

[0015]

According to the means of the present invention,
In a method of bending and forming a thin plate in which a joining portion of a peripheral edge of a container formed of a thin plate is fixed in advance and the joining portion is subjected to a bending process using a press die to form an edge bent portion, After the tip of the punch forming the first press die is held at a position that does not press the bending base point of the edge bending portion, bending is performed from the bending base point of the edge bending portion by the die facing the punch. The preliminary bending step to be performed, and the edge bending portion bent in the preliminary bending step is pressed toward the side wall of the container by a die forming a second press die, and the edge bending portion is the container. And forming an acute angle with respect to the side wall of the thin plate.

Further, according to the means of the present invention, there is provided a method for bending and forming a thin plate, wherein the pre-bending step and the acute-angle bending step have the same processing time.

Further, according to the means of the present invention, there is provided a method for bending and forming a thin plate, wherein both the preliminary bending step and the acute angle bending step are warm working.

According to the means of the present invention, the thin plate comprises:
A method of bending a thin plate, wherein a laminate layer of a plastic film is formed on a thin aluminum plate, and the laminated portions are fused with each other at the joining portion.

Further, according to the means of the present invention, in a state where the joining portion of the peripheral edge of the container formed of a thin plate is fixed in advance, the joining portion is subjected to press working using a punch and a die to bend the metal. In the mold, a side shape of the punch facing the container is similar to a side wall portion of the container, and the other side shape is formed to have a shape having a minimum angle that can be formed by the punch, and The tip is formed in a minimum R shape, and at the time of bending, the edge is bent by the die while the punch is held at a position where the punch tip does not press the container. It is a mold.

Further, according to the means of the present invention, the above-mentioned method for bending and forming a thin plate is used when forming the edge bent portion by bending a joint portion of a peripheral edge of a container formed of a thin plate. This is a method for manufacturing a secondary battery.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method for bending and forming a thin plate according to the present invention will be described for forming an edge bent portion by bending a mating portion of a sealed secondary battery.

The sealed secondary battery shown in FIG. 1 before the bending process of the joining portion and the sealed secondary battery shown in FIG. 2 after the bending process are the same as those described in the section of the conventional example. Therefore, the drawings and the reference numerals are used, and the overlapping description is omitted.

The sealed container 1 of the sealed secondary battery is formed by a combination of laminated plates 2 and 3 which are formed by forming a concave portion 1a by subjecting a part of the laminated sheet material to deep drawing and forming a concave portion 1a. . Opposite laminate plates 2, 3
Is a plate-like laminate plate 2 on one side, and the other is a box-like laminate plate 3 formed by deep drawing. The flat plate surfaces at the ends of the laminate plate 3 form the mating portions 4a and 4b, and come into close contact with the mating portions 5a and 5b of the flat laminate plate 2 to form edge bending portions 6a and 6b along the longitudinal direction. ing. The opposing laminate plates 2 and 3 are formed by laminating nylon on one surface and polypropylene on the other surface, respectively, of an aluminum thin plate.
It is about 0.1 mm.

For example, pure aluminum having a purity of 99.3% or more is used for aluminum as a material of the aluminum thin plate, or JIS standard A3003 (Mn content is 1. 0 to
1.5% by weight and a Si content of 0.6% by weight or less).

As shown in FIG. 1, in the sealed secondary battery (work W) before bending, the opposing flat plate-shaped laminated plate 2 and box-shaped laminated plate 3 are joined to each other at the joints 4a, The polypropylene layers 4b, 5a, and 5b are joined to each other by heat fusion so as to be in close contact with each other. Thereafter, the thin plate is processed by the bending and forming method of the present invention described later, and as shown in FIG.
a and 6b are formed. The edge bending portions 6a, 6b
Are raised in the thickness direction of the sealed secondary battery, and the rising height is at least as large as or smaller than the thickness of the sealed secondary battery.

Although not shown, a power generating element, an electrolyte, and the like necessary for a secondary battery are housed in a sealed container 1 formed by heat-sealing the facing laminate plates 2 and 3. In addition, a positive electrode terminal 7 and a negative electrode terminal 8 connected to the power generating element extend from the inside of the sealed container 1 to the outside.

However, as shown in FIG. 1, in the state of the work W, since the occupied area of the laminate plates 2 and 3 is the occupied area of the work W, it was temporarily used as a secondary battery. In such a case, the occupied area becomes large, which is not preferable in the case of mounting on a small portable device. In addition, since it is flat even in terms of strength, it is easy to bend, and furthermore, it is difficult to seal the seal for a long period of time by using only the seal by heat fusion.

From these circumstances, the joining portion 4 which is heat-sealed.
Edge bending portions 6a and 6b are formed by performing bending by press working on a, 4b, 5a and 5b.

FIGS. 3 (a) to 3 (c) and FIGS. 4 (a) to 4 (c) are schematic views of a main part showing the bending process of the present invention applied to the formation of the edge bending portions 6a and 6b. It is.

The bending process of the present invention is roughly performed by using a first press die and a second press die in a preliminary bending step and a subsequent acute angle bending step. In the pre-bending step and the subsequent acute-angle bending step, different molds are used, and the structure of each mold will be described each time a processing step is described. 3 (a) to 3 (c) are explanatory views of the preliminary bending step, and FIGS. 4 (a) to 4 (c) are explanatory views of the acute angle bending step.

First, the pre-bending process will be described. A predetermined position is defined between a punch 12 which moves down in cooperation with the work holder 11 and a knockout 14 which is provided on the fixed die 13 and moves downward during processing. The work W formed by the two laminate plates 2 and 3 is placed at a predetermined position by the work transfer arm 15. The shape of the surface of the punch 12 facing the workpiece W is formed in a shape similar to the facing surface of the workpiece W of the closed container 1, and also has a function of guiding the workpiece W. (A).

When the punch 12 is lowered by control means (not shown), the tip of the work holder 11 comes into contact with the work W, and the surface of the punch 12 facing the work W reaches a position where it follows the side wall of the work W (b).

Thereafter, when the punch 12 further lowers by a predetermined amount, the work W is knocked out 14 and the work holder 1 is moved.
It descends while being restrained by 1 and the punch 12. As a result, preliminary bending is performed to minimize the gap between the closed container 1 and the edge bending portions 6a and 6b (c).

FIG. 3 (d) shows the bends 6a, 6b at that time.
FIG. 4 is an explanatory diagram showing a relationship between an operation state of the punch b and the punch 12; Assuming that the thickness of the bent portions 6a and 6b is t, the inner position of the bent portion from the bottom of the bent portions 6a and 6b (the base point of bending).
If the distance to H is H, the relationship of H = t + α holds.

Here, α is a variable and is a value for determining a bending base point that changes depending on the shape of the work W. By minimizing the value of α, deformation to the work W during bending can be minimized. When the α dimension is increased, the bending base point approaches the closed container 1 side, but the work W is easily deformed, and the value of α has a limit value depending on the shape of the work W.

As an example, when α is set to 0.2 when the thickness t of the bent plate is 0.2, good bending with a radius of the inner diameter of bending of 0.1R can be obtained.

The tip of the punch 12 comes into contact with the edge bending portions 6a and 6b as it descends. However, when the punch 12 enters the inside of the die, the rising of the edge bending portions 6a and 6b starts to be formed. The work retainer 11 is sandwiched from both sides by the raised edge bending portions 6a and 6b, and the front end portion is not in contact with the edge bending portions 6a and 6b. Therefore, since the rising inner portions of the edge bending portions 6a and 6b are not pressed, there is no damage. That is, the tip of the punch 12 has the smallest R shape, and the tip of the punch 12 has the edge bent portions 6a, 6a.
After being held at a position where b is not pressed, it is bent by the fixed die 13 with the roots of the edge bending portions 6a and 6b as bending base points.

These pre-bending steps are warm working at a temperature of 100 ° C. to 140 ° C. for about 5 seconds.

Next, the pre-bent work W is subjected to the next step, acute angle bending. As shown in FIGS. 4 (a) to 4 (c), the mold used for the acute angle bending process is as follows.
A swing die 19 that is displaced by a predetermined angle about a rotation shaft 18 by a linear cam 17 is provided opposite the movable-side work holder 11a. The swing die 19 has a knockout 13.

In the acute angle bending, the workpiece W preliminarily bent is placed at a predetermined position of the mold by the work transfer arm 15. In addition, the shape of the surface of the punch 12 facing the work W is formed in an approximate shape to the surface of the work W facing the closed container 1 and also has a function of guiding the work W (a).

When the work holder 11a and the linear cam 17 are lowered, first, the work W is restrained by the work holder 11a and the knockout 13, and the edge bending portions 6a and 6b of the work W are firstly held.
Rises at a right angle. (B).

Further, when the linear cam 17 descends, it comes into contact with the swing die 19 accordingly. As a result, the tip of the swing die 19 is displaced toward the knockout 13 centering on the rotation shaft 18 and presses the edge bending portions 6a and 6b of the work W against the side wall of the closed container 1, and becomes an acute angle with respect to this side wall. The edge bent portions 6a and 6b are bent to such a predetermined angle to form an acute angle bent portion (f).

The sharp bending process is warm working, the ambient temperature is 100 ° C. to 110 ° C., and the processing time is about 5 seconds.

As described above, since both the pre-bending step and the subsequent acute-angle bending step can be performed in a processing time of 5 seconds, a production line in which the two steps are continuously arranged is used. Processing can be performed efficiently without waiting time. Thereby, productivity can be increased.

Also, since the sealed secondary battery can be bent from the root of the sealed container, it is possible to form the sealed container with a minimum gap between the bent container and the bent portion, thereby minimizing the outer width of the sealed secondary battery. Miniaturization has become possible.

Further, accurate bending can be performed without damaging the bending base point during the bending.

[0047]

According to the present invention, when bending a thin plate, the processing time can be shortened and the bending accuracy can be stabilized.

Further, the outer shape of the sealed secondary battery can be formed to the minimum size by these bending processes.

[Brief description of the drawings]

FIG. 1 is a perspective view of a sealed secondary battery before bending.

FIG. 2 is a perspective view of a sealed secondary battery after bending.

FIGS. 3A to 3C are explanatory views of a preliminary bending step of the present invention. (D) is an explanatory view showing the relationship between the edge bending portion and the work holder during processing.

FIGS. 4 (a) to 4 (c) are illustrations of an acute-angle bending step of the present invention.

FIGS. 5A to 5C are schematic views showing a conventional bending process. (D) is an enlarged view of the punch and the edge bending part at the time of processing.

FIGS. 6A to 6C are schematic views showing a conventional bending process.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Closed container, 2, 3 ... Laminate board, 6a, 6b ... Edge bending part, 11 ... Work presser, 12 ... Punch, 13 ... Fixed die, 14 ... Knockout, 15 ... Work transfer arm,
16 ..., 17 ... linear cam, 18 ... rotating shaft, 19 ... swing type die

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // B21D 53/00 B21D 53/00 DF term (reference) 4E063 AA01 AA02 BA01 CA05 DA01 DA06 KA02 MA16 MA30 5H011 AA09 CC10 DD03 DD06 DD26 KK03 5H029 AJ14 BJ04 CJ03 CJ06 CJ28 CJ30 DJ02 EJ01 EJ12 HJ12

Claims (6)

[Claims] 1. A bending method for forming a thin plate by forming a bent portion by performing a bending process using a press die on the matching portion in a state where a joining portion of a peripheral edge of a container formed of the thin plate is fixed in advance. In the method, after the bending process, the tip of the punch forming the first press die is held at a position where the bending starting point of the edge bending portion is not pressed, the die facing the punch is formed by the die facing the punch. A pre-bending step of bending from a bending base point, and pressing the edge bending portion bent in the pre-bending step in a direction of a side wall of the container by a die forming a second press die, thereby forming the edge. Forming a bent portion at an acute angle with respect to the side wall of the container. 2. The processing time of the pre-bending step and the acute-angle bending step are the same.
A method for bending and forming a thin plate as described above. 3. The method according to claim 1, wherein both the preliminary bending step and the acute-angle bending step are warm working. 4. The thin plate according to claim 1, wherein a laminated layer of a plastic film is formed on an aluminum plate, and the laminated portion is formed by fusing the laminated layers together. Method. 5. A mold for performing bending by press working using a punch and a die on the matching portion in a state where a matching portion of a peripheral edge of a container formed of a thin plate is fixed in advance, wherein: The side surface shape facing the container is similar to the side wall portion of the container, the other side shape is formed in a shape having a minimum angle that the punch can form, and the tip of the punch has a minimum R shape. A die formed by bending the edge bending portion of the container by the die in a state where the punch is held at a position where the container is not pressed by the tip of the punch at the time of bending. 6. The method of bending a thin plate according to claim 1, wherein the edge bent portion is formed by bending a joining portion of a peripheral edge of a container formed of the thin plate. A method for producing a sealed secondary battery.