JPH105907A - Manufacture of bottomed container and its die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the thickness precision of a product by pressing a work, using a punch on which a projecting part with a tapered part becoming higher gradually toward its center from a periphery is provided. SOLUTION: A blank 1 is put into a die 6, and impact extrusion forming is performed by the punch 5. At the tip of the punch 5, the projecting part with the tapered part is provided. The tip of the punch 5 is in a rectangular pyramid shape. On the blank 1, a recessed part with a taper fitting with the projecting part of the punch 5 is provided. Since the blank 1 held in the die 6, is fitted with the punch 5 at the tapered part, at the time of pressing, the axial center of the punch is not shifted, and the flow of the plastic deformation of the blank 1 becomes uniform. The flow of an extrusion is uniformly induced by the tapered part. By a mutually potentiating effect of these two actions, a material is uniformly distributed to each part of a side wall. Even when using the material with large work hardening, the thickness of the side wall becomes uniform.

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 a bottomed container by plastically deforming a metal blank by an impact extrusion method using a punch and a die, and a mold used for the method. An object of the present invention is to provide a manufacturing method suitable for manufacturing an ultra-thin, high-bottomed bottomed container requiring dimensional accuracy and mechanical strength, such as a rectangular or rectangular lithium ion battery or an electrolytic capacitor, and a mold used therefor.

[0002]

2. Description of the Related Art The so-called impact extrusion method of manufacturing a bottomed container by pressing a metal blank such as stainless steel or an aluminum alloy in a mold composed of a punch and a die to plastically deform the blank is highly productive. Therefore it is widely used. The inventor developed this basic technology 35 years ago, and recently, Japanese Patent Publication No. Hei 8-4869 and Japanese Patent Laid-Open No. 6-2698.
Various improvements such as those described in No. 91 have been made, and it has become possible to manufacture thin and tall containers at low cost.
For these bottomed containers, materials based on JIS1070 pure aluminum and JIS3003 aluminum-manganese have been used.

[0003]

However, in recent years, bottomed containers used for lithium ion batteries and electrolytic capacitors have been required to be smaller and lighter and to be sealed by laser welding. High strength is required to prevent deformation of the container due to heat generation due to charging and discharging of JIS 5052 aluminum-magnesium material, which is higher in strength than conventional materials. Large containers are needed. However, these materials have large work hardening, so that the conventional technique of providing unevenness for preventing misalignment on the blank and fitting it to the unevenness provided on the die is sufficient for the side wall portion. The dimensional accuracy of the wall thickness cannot be obtained.

For example, as a rectangular container for a lithium ion battery, a container having a height of 45 mm, a width of 33 mm, and a thickness of 8 mm is used, and the side wall thickness is 0.4 ± 0.04.
Millimeter accuracy is required.
In order to meet such a demand, the thickness of the side wall portion is extremely inadequate by the conventional manufacturing method using only the concave and convex portions for preventing displacement when the blank is pressed and deformed.
Small rectangular (gum-shaped) used especially for portable electronic devices
Since a flat container is preferably used in a lithium ion secondary battery, the wall thickness tends to be non-uniform, so that the wall surface of the container may be inconvenient. There is a problem that sufficient wall thickness accuracy for sealing cannot be obtained, and furthermore, in the case of a flat container, a large bending stress is applied in the thickness direction of a punch having a small thickness, so that the life of the punch is extremely short. There was a drawback.

[0005]

According to the present invention, first, a blank made of a metal material is mounted in a cavity of a die, and the blank is pressed by a punch movable relative to the die. In the method for producing an ultra-thin tall bottomed container by an impact extrusion molding method of plastically deforming a convex portion having a tapered portion that gradually increases from the periphery of the surface toward the center on the surface of the die facing the blank. It is a manufacturing method of pressing using a provided punch, preferably also has a concave portion having a tapered portion gradually deeper from the periphery of the surface toward the center of the surface of the blank facing the punch, the concave and the said This is a manufacturing method of pressing in a state where the protrusions of the punch are fitted with each other.
A mold for impact extrusion molding used in the manufacturing method, wherein a shape of a punch tip surface of the mold is provided with a convex portion having a tapered portion that is sequentially convex from the periphery of the surface toward the center. Mold.

That is, in order to satisfy the requirement of forming the thickness of the side wall of the thin-walled container with high accuracy and uniformity, it is necessary to make the flow of the plastically deformable material uniform at the time of deformation and to prevent the axial position of the punch from oscillating. Is extremely important, and it has been found that the method of the present invention is extremely effective as a means for these two measures. A blank having a concave portion having a tapered portion that gradually becomes deeper from the periphery toward the center can be obtained in advance by, for example, stamping using a separate mold, or a small recess can be made with a punch. In this case, a concave and convex portion for positioning may be provided on the bottom surface of the blank as necessary. Further, it is desirable that the tapered portion remaining at the bottom of the container after the impact extrusion molding is pressed by using another mold as needed to make it flat.

[0007]

The tapered portion at the tip of the punch has a predetermined direction and amount of flow when the blank material is pressed and flows between the die and the punch. For example, when the thickness of the container is about 0.6 mm, the depth is 45 mm and the width is 2 mm.
In the case of a small container having a size of about 2 mm and a length of about 6 mm, or when using a metal having a small work hardening, a container having a sufficiently uniform wall thickness can be formed by this method alone. Furthermore, when the blank is also provided with a tapered portion, the blank held in the die and the punch that presses the blank are fitted through the tapered portion so that the axis of the punch does not swing when the punch is pressed. And the action of guiding each part in the blank in the direction in which it is desired to flow at the time of impact extrusion by a tapered portion adapted to the flow, and the synergistic effect of these two actions results in each part of the side wall The distribution of the materials is more evenly distributed, and the side wall thickness is 0.3 to 0.4 mm and the tolerance is 10% even when a large work hardening material is used which is difficult to perform impact extrusion.
It is possible to stably mass-produce ultra-thin tall bottomed containers within the range.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The shape of the tapered portion does not necessarily have to be a completely flat surface, and the flow is formed by grooves, projections, or curved surfaces in a predetermined direction according to the state of material flow to the side wall of the container. Can be corrected. In addition, the edge of the punch at the intersection of the blank surface and the punch side surface may be chamfered for the purpose of reducing the resistance of the material flow. Further, these irregularities on the bottom surface of the container after the impact extrusion molding may be pressed by another mold to be flat. As the material of the blank, JIS 5000-based aluminum-magnesium alloy, iron, stainless steel such as SUS631 can be suitably used.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 to 5, an embodiment of a method and a method for manufacturing a rectangular container for a lithium ion battery by using a mold will be described. The blank 1 is a JIS 5000-based aluminum-magnesium alloy. As shown in FIG. 1 or FIG. 2, a tapered portion 2 which is gradually concaved from the periphery toward the center is provided on a surface facing the punch to form a concave portion 3. ing. In FIG. 2, a concave portion 4 is further provided on the back surface for positioning the blank. The concave portion 3 provided on the surface facing the punch of the blank may be used when the thickness of the container is large,
The length: width ratio is within 1: 4 and the size is 6 × 22 ×
In the case of a small container of about 45, it may be omitted. As shown in FIG. 3, the tip of the punch 5 fitted into the concave portion 3 of the blank has a quadrangular pyramid shape. FIG. 3 shows a state where the blank 1 is inserted into the die 6 and the punch 5 is fitted through the tapered portion 2. At this time, it is important that the center axis of the die coincides with the center axis of the punch, and that the gap between the side wall of the die and the side wall of the punch has a predetermined width. When a blank having the shape shown in FIG. 2 is used, a projection that fits into the recess 4 is provided on the die. FIG. 4 shows a state in which the material is pressed and plastically deformed to form a thin side wall of the container. FIG. 6 shows the shape of the ultra-thin tall bottomed container formed in this manner. There is as a face. The dimensions of each part of H, W and D of this container are 45, 33, 8.1 mm and 65, 3 respectively.
3,14 mm. The thickness of the side wall of this container was within ± 0.04 mm from the design value of 0.4 mm. In the case of this material, the hardness increases due to work hardening at the time of impact extrusion.
The thickness of the bottom and side wall corners is 0.4 to 0.5
mm, it is possible to obtain a battery in which both characteristics of swelling due to heat generation during charging and discharging and high capacity are balanced.

[0010]

As is apparent from the above description, according to the production method of the present invention and the mold used therein, a high-strength metal ultra-thin tall for a lithium ion battery or the like, which was difficult with the conventional method. With the extremely accurate wall thickness of bottomed containers, tens of millions of units can be mass-produced per month at a high yield, and the dimensional accuracy of the side wall thickness of the container is guaranteed. In the manufacturing process of (1), the sealing by laser welding, which has a significant effect on the quality of the battery, is made easy and reliable, and an extremely excellent effect is also obtained on the improvement of the manufacturing yield of the battery.

[Brief description of the drawings]

1A and 1B are a perspective view and a cross-sectional view of a blank used in the present invention, FIG. 1A is a perspective view, FIG.
Is a cross-sectional view of the YY 'plane

FIG. 2 is a perspective view and a sectional view of another example of a blank used in the present invention.

FIG. 3 is a perspective view of a punch tip of the present invention.

FIG. 4 is a cross-sectional view showing a mounting state of a blank to a mold in the manufacturing method of the present invention.

FIG. 5 is a cross-sectional view showing a deformed state of a blank after impact extrusion in the manufacturing method of the present invention.

FIG. 6 is a perspective view of a metal ultra-thin tall bottomed container manufactured by the manufacturing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Blank 2 Taper part 3 Concave part 4 Concave part 5 Punch 6 Dice 7 Molded container

Claims (7)

[Claims] An ultra-thin impact extrusion molding method in which a blank of a metal material is mounted in a cavity of a die and the blank is plastically deformed by pressing the blank with a punch movable relative to the die. In the method of manufacturing a tall bottomed container, pressing using a punch provided with a convex portion having a tapered portion that sequentially increases from the periphery of the surface toward the center of the surface of the die facing the blank. Characteristic manufacturing method. 2. The punch according to claim 1, wherein a surface of the blank facing the die is provided with a concave portion having a tapered portion that gradually becomes deeper from the periphery of the surface toward the center. A manufacturing method characterized by pressing in a fitted state. 3. The manufacturing method according to claim 1, wherein the shape of the container to be formed is a quadrangular prism using a punch having a quadrangular pyramid at the tip of the punch. 4. The manufacturing method according to claim 1, wherein a concave portion or a convex portion is provided also on a surface of the blank facing the die bottom surface, and a die having a convex portion or a concave portion fitted on the die bottom surface is also provided. Method. 5. The manufacturing method according to claim 1, wherein after the impact extrusion molding, the bottom of the molded bottomed container is pressed by another mold to a flat surface. 6. The method according to claim 1, wherein the first and second embodiments are different from each other.
A mold for impact extrusion molding used in any one of the manufacturing methods, wherein the shape of the punch tip surface of the mold has a convex portion having a tapered portion sequentially convex from the periphery of the surface toward the center. A mold characterized by being provided. 7. A die for impact extrusion molding used in the manufacturing method according to claim 3, wherein the shape of the punch tip surface of the die is gradually convex from the periphery of the surface toward the center. A metal mold provided with a quadrangular pyramid-shaped projection having the following.