JP2000107831A - Flat thin bottomed square tubular body, manufacture thereof, manufacturing punch and battery or capacitor using the square tubular body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a manufacturing method of a thin flat bottomed square tubular body by which the manufacture of the small thin flat bottomed tubular body is enabled, punch having novel structure which is used for the manufacturing method, thin bottomed square tubular body having novel structure which is manufactured with the punch and thin secondary cell or a capacitor in which this square tubular body is used as its case. SOLUTION: As a punch at the time of manufacturing an aluminum bottomed square tubular body by inserting an aluminum material to be formed into the cavity of a die and impact extrusion by which this material is backward extruded along the punch 15 from the clearance between a cavity and the punch 15 with the punch 15 forming a bulged-out part 17 in the tip part, the punch 15 in the tip surface of the bulged-out part of which a sheet-shaped projected surface part 18 having a slightly smaller shape than the shape of the bulged-out part is formed is used. The obtained bottomed square tubular body is used for the case of the secondary cell such as a lithium ion cell or the capacitor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an aluminum bottomed rectangular cylinder having a rectangular flat cross section and a uniform thickness on the opposite side by impact extrusion, and a unique structure produced by the method. The present invention relates to a bottomed rectangular cylindrical body made of aluminum and having a flat thin shape having a rectangular cross section and a uniform wall thickness on the opposite side. More specifically, a method of manufacturing by a rectangular extrusion having a rectangular cross section, which can be suitably used for a small case such as a case of a lithium ion secondary battery and the like, by impact extrusion for extruding a rectangular bottomed aluminum cylindrical body having a uniform thickness and backward. The present invention relates to a flat, thin, and uniform-thickness aluminum bottomed rectangular cylinder having a rectangular cross section and a unique structure manufactured thereby. Further, the present invention relates to a punch used for the impact extrusion and a secondary battery or a capacitor such as a lithium ion battery using a bottomed rectangular cylinder having a specific structure manufactured as a case.

[0002]

2. Description of the Related Art As a method of manufacturing a bottomed aluminum cylinder used for a case of a lithium ion battery, a condenser or the like, an impact extrusion method or a deep drawing method is known as a conventional technique. The impact extrusion method includes three methods, a rear extrusion method, a front extrusion method, and a front-rear extrusion method, and the rear extrusion method is used for the method of manufacturing the case.

[0003]

The lithium-ion battery using this aluminum bottomed cylinder as a case has been increasingly miniaturized in a notebook computer or a mobile phone in which the battery is used. There is a demand for further thinning. As a result, the aluminum bottomed rectangular cylinder used as a battery case is required to be further reduced in thickness, and the present inventor has also developed this thin aluminum bottomed rectangular cylinder manufacturing technology in order to respond to the demand. Tried. The appearance of such a thin rectangular cylinder with a bottom is expected not only in a lithium-ion battery but also in a secondary battery such as a nickel-metal hydride battery or an electric double-layer capacitor.

[0004] In view of the above, the inventor of the present invention first tried to manufacture a small rectangular cylinder with a rectangular cross section by the backward extrusion method, which is one of the conventional impact extrusion methods. As a result, the minor axis is 9.0 mm and the major axis is 33.3 mm.
In the case of 0 mm, it was found that the defective rate was high, but it was possible to manufacture. At that time, it was found that the difference in wall thickness between the wall surfaces of the facing rectangular cylinders became large. It was also found that when the short diameter was 6.0 mm and the long diameter was 29.0 mm, it was impossible to form a predetermined shape.

Therefore, the present inventors have proceeded with the development to produce a good product even in such a thin and small rectangular cylinder having a low defect rate and a thinner shape. In addition, it has been found that a desired product can be obtained by simply devising the punch end face. In addition, the resulting small-sized rectangular cylinder with a bottom has a uniform wall thickness, especially between the opposed cylinder wall surfaces, and a unique characteristic at the bottom, compared to a rectangular cylinder produced by the conventional backward extrusion method. Was formed.

As described above, the structure of this punch is also different from the conventional one, and is a novel structure. Further, by using this rectangular cylinder as a case, it has become possible to manufacture a thin lithium ion secondary battery or a condenser, etc., which has never existed before. Therefore, the present invention makes it possible to provide various inventions as described above, and the present invention provides a flat, thin, and bottomed angle which enables the manufacture of a flat, thin, small-sized, bottomed rectangular cylinder. A method of manufacturing a cylindrical body, a punch having a novel structure used therein, a flat thin bottomed rectangular cylinder having a novel structure manufactured thereby, and a thin secondary battery or a capacitor using this square cylindrical body as a case. An object of the present invention is to provide an invention, which is a problem to be solved.

[0007]

Means for Solving the Problems The method adopted by the present invention for achieving the above-mentioned object, which is a method for manufacturing a bottomed rectangular cylinder made of aluminum, comprises inserting an aluminum molding material into a die capacity, This material is extruded rearward along the punch from the gap between the capacity and the punch by a punch with a bulge formed at the tip, and is shock-extruded. A method of manufacturing a cylindrical body, characterized in that a punch having a thin plate-shaped convex portion having a shape slightly smaller than the shape thereof is formed on the front end surface of a bulging portion.

[0008] The bottomed rectangular cylinder as a means for that purpose is obtained by that, and it is a flat thin aluminum cylinder with a rectangular cross section and a flat aluminum wall with a uniform wall thickness. And a new structure having a bottom having a thick portion on the outer periphery of the rectangular bottom surface. further,
The punch, which is a means for achieving this, has the structure as described above, and a secondary battery such as a lithium ion battery or a capacitor uses the above-described square cylinder with a bottom as a case.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The manufacturing method of the present invention will be specifically described with reference to the drawings. However, the present invention is not limited to the specific description, but is based on the claims. It goes without saying that it is something that is grasped.
FIG. 4 shows a method for manufacturing a flat, thin, and aluminum-clad bottomed rectangular cylinder 1 having a rectangular cross section according to the present invention.
First, as shown in FIG.
The aluminum molding material 8 is inserted into the molding material 2, and thereafter, the punch 15 is made to impact (impact into the molding material 8) in the capacity 12.

As a result, as shown in FIG. 4B, the molding material 8 flows along the punch from the gap between the bulging portion 17 slightly larger than the other portion formed at the distal end portion 16 of the punch 15 and the capacity 12 and along the punch. To form a flat thin aluminum bottomed rectangular cylindrical body 1. In this case, according to the present invention, a thin plate-shaped convex portion 18 having a shape slightly smaller than that is formed at the front end surface of the bulging portion 17 at the front end portion of the punch, thereby making it possible to manufacture a small aluminum plate which cannot be manufactured by the prior art. It is now possible to manufacture even the bottomed rectangular cylinder 1 made. In addition, the thickness of the cylindrical portion of the rectangular cylindrical body 1 is also uniform, and uneven thickness can be avoided.

In particular, it is possible to avoid uneven thickness between a pair of opposed cylinder wall surfaces (for example, the 2A2B surface and the 3A3B surface) of the rectangular cylindrical body 1, and the rupture occurs when this rectangular cylindrical body is used for a lithium battery case. I was able to solve the problem that was causing the problem. Although the reason why this problem can be solved is not clear, the formation of the thin plate-shaped convex portion 18 can secure a passage at the periphery of the punch bottom surface when the molding material 8 is extruded along the punch. It is speculated that the material can flow smoothly and evenly. These problems can be better avoided by forming a radial groove 18a extending outward from the center, as shown in FIG. At this time, the grooves can be easily formed by grinding with a grindstone.

The manufactured aluminum bottomed rectangular cylinder 1 has a unique structure in which the punch used at the time of manufacture has a thin plate-shaped convex portion 18 formed on the tip end surface.
It has a unique structure as shown in FIG. 1, which has a bottom 4 having a thick portion 5 on the outer periphery of a rectangular bottom surface and a pair of opposed cylindrical wall surfaces (2A2B, 3A) rising from the bottom 4.
A3B) is an aluminum bottomed rectangular cylindrical body 1 having two pairs of A3B) having a rectangular cross section and a flat, thin and uniform thickness. The punch 15 used at that time also has a unique structure as described above, and the inside of the case of the lithium ion battery using the rectangular cylinder 1 also has the unique structure as described above. The groove 18 is formed in the thin plate-shaped convex portion 18.
When a is formed, it is also transferred to the bottom 4 of the manufactured rectangular cylinder 1, and a groove 4a appears at the bottom.

The aluminum used in the production can be used without particular limitation as long as it is for forging, and it may be aluminum or an alloy thereof, specifically, JIS 1100, 1070, 3
003, 5056, etc., preferably JIS 30
03 is good. It is preferable to use a lubricant at the time of impact extrusion, but it is possible to manufacture a rectangular cylinder even if it is not used. As the lubricant used in this case, there are unsaturated metal salts of carboxylic acid, graphite, zinc stearate and the like, and preferably zinc stearate.

Regarding the overall shape of the rectangular cylinder 1 to be manufactured,
Since its use is primarily in the case of a lithium battery, it is preferable to use a rectangular shape with a substantially elongated cross section, that is, a thin flat rectangular parallelepiped (where l1 is considerably longer than l2). It is not necessary that the corners be formed (that is, the corners are cut) or the corners may be rounded. The surface shape of the surface 3 on the side where the area of the cylindrical portion is small need not be a flat surface, but may be a round spherical surface. The shape of the rectangular cylindrical body is not particularly limited to the above shape, and the cross-section may be elliptical, polygonal, multi-cylindrical, or the like. I just need. Here, the multi-cylindrical body has a structure in which a plurality of cylinders are connected as shown in a cross-sectional view of FIG.

The size is not particularly limited, and may be large. Even in this case, using the manufacturing technique of the present invention is simpler than the conventional technique, so that the flat, thin and uniform thickness can be obtained. Aluminum bottomed cylinders can be manufactured. The size in which the advantages of the present invention can be particularly effectively utilized is that the major axis 11 is 10 to 70 mm and the minor axis 12 is 2 to 10 mm.
In the case of, preferably, the major axis 11 is 20 to 50 mm,
This is the case where the minor diameter 12 is 4 to 10 mm. As is clear from the above, the uniformity of the wall thickness of the cylindrical wall does not need to be uniform over the entire surface of the cylindrical wall, but may be at least uniform between the opposing cylindrical walls.

Next, the shape of the tip of the punch 15 will be described. It is preferable to form a bulging portion 17 at the tip end portion 16 of the punch 15 in order to make the punch 15 and the molded product come off easily, and this is the case in the present invention. The tip of the bulging portion 17 is flat, and the contact with the side surface is preferably chamfered. On the tip plane of the bulging portion 17,
A thin plate-shaped convex portion 18 slightly smaller than the plane and having a substantially similar shape is formed, and its existence is the greatest feature of the present invention. In the present invention, this thin plate-shaped convex portion 18
, The flat and thin aluminum bottomed rectangular cylindrical body having a rectangular cross section can make the wall surface of the opposed cylindrical wall uniform, and at the same time, the presence of the rectangular cylindrical body 1 The bottom surface has a unique structure in which the outer periphery becomes thick.

Regarding the formation of the thin plate-shaped convex portion 18,
It is preferable to cut out from a material integral with the punch material and form it integrally, but it is not limited to this. In other words, they may be separately manufactured and then combined, but it is very difficult to arrange them so as to form a horizontal plane with high precision on the punch, and the former is superior. The thickness is preferably 0.1 to 0.5 mm, and the smaller the area of the small cylindrical wall surface 3 of the rectangular cylindrical body 1 which is a molded product, the larger the thickness. The size is preferably smaller by 0.1 to 5 mm on the entire circumferential surface than the planar shape of the tip of the bulging portion 17, and preferably by 0.5
It is better to be 3 mm smaller. Also in this case, it is preferable that the smaller the surface 3 of the rectangular cylinder 1 that is a molded product is, the larger the surface 3 is.

The pressing pressure at the time of impact extrusion is not particularly limited, but it depends on the size of the molded product. The larger the pressure, the larger the pressure required, the better is 20 to 500 ton / cm ² . Is 80 ~
300 tons / cm ² is good. The material of the die and the punch is not particularly limited, but it is preferable to use cemented carbide, hot die steel, high-speed steel, or the like. Further, the internal structure when used as a case of a secondary battery such as a lithium ion battery or a nickel-metal hydride battery or a capacitor is not particularly limited, and a conventional battery can be used as it is.

[0019]

[Example 1] Continuous annealing at 415 ° C for 2 hours,
Air-cooled JIS 3003 aluminum alloy forming material, namely slag (32.9 × 8.9 × 10.0
mm) with the lubricant zinc stearate 33.0 ×
Insert into a 9.0 × 11.0 mm capacity and remove
5 mm, 1.0 mm from the punch
A wide surface, that is, a cylindrical wall surface (2A.2.
The impact extrusion was carried out at a pressure of 100 ton / cm ² by the backward extrusion method so that the thickness of B) was about 0.6 mm and the thickness of the narrow surface, that is, the surface of the small area (3A.3B) was about 0.8 mm. Carried out.

The thicknesses (a, b) of the 20 aluminum bottomed rectangular cylinders at the mouth, center, and bottom are measured at opposing positions of a pair of opposing cylinder wall surfaces, and the difference is measured. (Ab) was determined and is shown in FIG. 9 and FIG. The result is that the thickness of the wide surface is around 0.6 mm,
The thickness of the narrow surface was about 0.8 mm. FIG. 9 shows the thickness difference (ab) of the wide surface, and FIG. 10 shows the thickness difference (ab) of the narrow surface. FIG. 9 (A)
(B) and (C) show the difference in wall thickness at the mouth, the center, and the bottom in order from the top, and the same applies to FIG. In these figures, the vertical axis represents the difference in wall thickness, and the horizontal axis represents the sample number.

Comparative Example 1 An aluminum prismatic body was manufactured by the backward extrusion method in the same manner as in Example 1 except that a punch having no thin plate-like convex portion 18 was used.
As in Example 1, the difference in wall thickness of a pair of wall surfaces facing each other at the mouth, center, and bottom of the manufactured 20 bottomed rectangular cylinders made of aluminum was determined and displayed in FIGS. 10 and 11. did. The contents displayed in FIGS. 11 and 12 are the same as the contents displayed in FIGS. 9 and 10, respectively.

Comparing the results described in Example 1 and Comparative Example 1, the area of the present invention using the punch 15 formed with the thin plate-shaped convex portion 18 is larger than that of the comparative example not using the same. It becomes apparent at a glance that the wall thickness (wide surface) on the side of the large side has a large variation in wall thickness and lacks uniformity. Also, it can be seen that it occurs at any of the mouth, the center, and the bottom. On the other hand, it was found that there was almost no variation in wall thickness on the cylindrical wall surface (narrow width surface) on the side with a smaller area, and there was no difference between the two. When this rectangular cylinder is used for the case of a lithium battery, it is possible to avoid uneven expansion or case rupture due to an increase in internal pressure due to an external short circuit due to uneven thickness on the side having a particularly large area, which is a problem. It has become something.

Example 2 The size of the slag was 28.9 ×
Impact extrusion was carried out by the backward extrusion method in the same manner as in Example 1 except that the size was set to 5.9 × 10.0 mm and the size of the capacity was made corresponding to the size. In the same manner as in Example 1, a rectangular cylinder having a uniform wall thickness at the position where the pair of cylinder walls face each other at each position was obtained.

Comparative Example 2 Impact extrusion was carried out by the backward extrusion method in the same manner as in Comparative Example 1 except that the size of the slag and the capacity were the same as in Example 2, but a rectangular cylinder could be formed. Did not. In this method, a material of this size could not be formed in a normal shape.

[0025]

According to the present invention, when manufacturing a bottomed rectangular cylinder by the impact extrusion method, a thin plate-shaped convex portion having a shape slightly smaller than the shape is formed on the distal end surface of the bulging portion of the punch distal end portion. Further, it is possible to manufacture a thin bottomed rectangular cylindrical body and a bottomed rectangular cylindrical body without uneven thickness, which cannot be produced by the conventional impact extrusion method.

The manufactured bottomed rectangular cylinder has a unique structure in which the outer circumference of the bottom is thick and has a uniform thickness without uneven thickness between a pair of opposed cylinder walls. ing. As a result, it is possible to avoid the occurrence of uneven expansion due to an increase in internal pressure, which is caused by uneven wall thickness when used in a case of a lithium ion battery or the like, and it is possible to use the case without any trouble.

Also, there is no need to use a special material as the molding material, and the conventional one for impact extrusion can be used as it is, and the manufacturing apparatus requires only a slight modification of the tip of the punch and requires only a simple change. . As described above, the present invention has a remarkable effect.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a bottomed rectangular cylinder of the present invention.

FIG. 2 is a plan view of the bottomed rectangular cylinder of the present invention.

FIG. 3 is a perspective view of the bottomed rectangular cylinder of the present invention.

FIG. 4 is a diagram showing a state before and after a molding material in a die capacity is impact-extruded by a punch. (A) is the state before extrusion. (B) is the state after extrusion.

FIG. 5 is a front view of the punch.

FIG. 6 is a view of the lower surface of the punch.

FIG. 7 is a perspective view of a molding material.

FIG. 8 is a cross-sectional view of the multi-cylinder body cut in a direction orthogonal to the cylinder.

FIG. 9 illustrates the difference in wall thickness measured at the opposed positions of the mouth, the center, and the bottom of the wide surface (2a, 2b) with respect to the rectangular cylinder of 20 samples manufactured in Example 1.
(A), (B), and (C) show the difference in wall thickness of the facing wide surface at the mouth, center, and bottom in order from the top.

FIG. 10 illustrates the difference in wall thickness measured at opposing positions of a mouth, a center, and a bottom of a narrow surface (3a.3b) of 20 samples of a rectangular cylinder manufactured in Example 1. (A), (B) and (C) are the lips in order from the top,
The difference in the thickness of the opposed narrow surfaces at the center and the bottom is shown.

FIG. 11 illustrates a difference in wall thickness measured at a position where a mouth, a center, and a bottom of a wide surface (2a, 2b) are opposed to each other with respect to a rectangular cylinder of 20 samples manufactured in Comparative Example 1. (A), (B) and (C) are the lips in order from the top,
The difference of the thickness of the opposing wide surface in a center part and a bottom part is shown.

FIG. 12 illustrates a difference in wall thickness measured at a position where a mouth, a center, and a bottom of a narrow-width surface (3a.3b) are opposed to each other in 20 rectangular cylinders manufactured in Comparative Example 1. (A), (B) and (C) are the lips in order from the top,
The difference in the thickness of the opposed narrow surfaces at the center and the bottom is shown.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bottomed rectangular cylinder 4 Bottom 5 Bottom thick part 8 Molding material 11 Die 12 Capacity 15 Punch 17 Swelling part 18 Thin plate-shaped convex part

Claims (5)

[Claims] 1. An aluminum bottomed corner having a rectangular thin flat cross-section having a pair of opposed cylindrical wall surfaces rising from the bottom and having a thick portion on the outer periphery of a rectangular bottom surface and having a uniform thickness at the facing surface. Cylindrical body. 2. An aluminum molding material is inserted into the die's capacity, and the material is rectangular in cross section by impact extrusion in which the material is extruded rearward along the punch from the gap between the capitality and the punch by a punch having a bulge formed at the tip. A method of manufacturing a flat, thin, aluminum-clad bottomed cylindrical body having a uniform thickness, wherein a punch having a thin plate-shaped convex surface slightly smaller than its shape is formed on the distal end surface of a bulging portion. A method for producing a bottomed rectangular cylindrical body made of aluminum having a flat and thin section with a rectangular cross section and a uniform wall thickness facing each other. 3. A punch for manufacturing a bottomed rectangular cylindrical body made of aluminum and having a flat and thin rectangular cross section and a uniform wall thickness facing each other by a rear-extrusion impact extrusion method. A punch with a slightly smaller thin plate-like convex surface. 4. An aluminum base angle having a rectangular flat bottom and a thin flat cross section having a pair of opposed cylindrical wall surfaces rising from the bottom and having a thick portion on the outer periphery of the bottom surface of the rectangular shape. A secondary battery having a cylindrical body as a case. 5. An aluminum bottomed corner having a rectangular flat bottom and a flat cross section having a pair of opposed cylindrical wall surfaces rising from the bottom and having a thick portion on the outer periphery of the rectangular bottom surface and having a uniform thickness at the facing surface. A condenser with a cylindrical case.