JPH1043874A - Cold pressure welding method of metallic foil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the quality and yield by integrating two working processes of the blanking and cold pressure welding of a metallic foil in the manufacture of a rupture-disk type safety valve where the metallic foil is cold pressure welded to a part of a sealed battery container to make an explosion-proof valve. SOLUTION: An intermediate die 3 is provided on a stripper plate 2 of a cold pressure welding die, and a metallic foil stock (c) to be continuously fed by a hoop onto a cutting blade surface of the intermediate die 3 is blanked when a punch is pierced through the intermediate die 3, a blank is depressed by a tip of a punch 1 with an inner side following the cutting blade of the intermediate die 3 as a guide, the metallic foil is positioned on an upper surface of an upper lid (a) on a pressure welding die 4 and cold pressure welded to allow the blanking and the cold pressure welding of the metallic foil stock (c) in one process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for manufacturing a tear-off type safety valve by cold-welding a metal foil used in a sealed secondary battery, and to other cold-welding of a metal foil.

[0002]

2. Description of the Related Art An open type safety valve for a sealed secondary battery uses a metal foil cold-pressed so as to close an air hole formed in an upper lid of a metal container, and this is used as an explosion valve. In the conventional method, the upper lid is first processed by a progressive die. The upper lid is a component forming one surface of the battery container, and is provided with a vent hole for releasing abnormal internal pressure. The metal foil used as the safety valve is blanked from a sheet-like material into a circular or oval shape, and washed and used immediately before cold pressure welding. The metal foil is small and has a thickness of about 0.01 mm to 0.03 mm and a diameter of about 3 mm to 5 mm. In cold pressure welding, first, an upper lid is positioned on a pressure welding die, a metal foil is positioned so as to close a ventilation hole of the upper lid, and pressure bonding is performed by a pressure punch to join.

[0003]

The metal foil to be joined to the battery container as a member of the safety valve is small and has a thickness of 0.0
The size is about 1 mm to 0.03 mm and the diameter is about 3 mm to 5 mm. Such small metal foils may overlap and stick from scratching, cleaning, positioning, and cold welding, may be damaged, may be displaced from the home position by the influence of wind, vibration or static electricity. Problems arise. In the conventional processing method, when punching with a blanking die, it is often stuck in the die, and multiple sheets are often stuck after being discharged from the die. The metal foil may be broken or scratched during handling during cold pressure contact, cleaning or positioning of the metal foil, without noticing this. There are many troubles that occur during ranking, washing, and handling at a predetermined position in a cold press mold. Furthermore, there is also a problem that the metal foil is displaced from the predetermined position due to the influence of vibration, static electricity or wind, etc., between the time when it is positioned in the cold pressure welding mold and the time when pressure is applied by the pressure welding punch. Many.

As a result of these factors, alone or in combination, adversely affecting the cold welding of metal foil, leakage occurs from the cold welding joint, and the tearing pressure as a safety valve deviates from a specified value. There is a problem in that a failure occurs and the reliability and mass production yield of the split-type safety valve by the cold pressure welding method of the metal foil are reduced.

[0005]

In the working method for simultaneously blanking and cold-welding a metal foil according to the present invention, a specially-made cold-welding die to which a blanking mechanism for a metal foil is added was developed and applied. . While the upper mold of the cold pressing mold moves from top dead center to bottom dead center, first blank the metal foil,
Subsequently, it was possible to perform cold pressure welding before reaching the bottom dead center.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION An intermediate die is provided on a stripper plate of a cold pressing die, and when the tip of the punch passes through the cutting edge surface of the intermediate die, the metal foil is blanked and positioned directly on the upper surface of the pressing die. It is pressed down to the upper surface of the metal member and pressurized and cold pressed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given of an example in which a split-type safety valve is provided on a top cover a of a rectangular battery container by a cold pressure welding method of metal foil. FIG. 1 shows the basic structure of the cold pressing mold according to the present invention. Punch 1, Stripper 2, Intermediate die 3, Pressing die 4
Are arranged on the same axis, and the upper lid a
Position. The metal foil material c is configured to be supplied to the gap between the stripper 2 and the intermediate die 3 from the side of the mold.

FIGS. 2, 3, 4 and 5 are cross-sectional views of a cold pressing mold used for actual mass production. The difference from FIG. 1 is that the stripper 2 and the intermediate die 3 are used for mass production. Has been changed to a bush type standard part. 2 is a state in which the upper mold I is at the top dead center position, FIG. 3 is a state in which the upper mold I is lowered from the top dead center position until the lower surface of the intermediate die 3 contacts the upper surface of the upper lid a, and FIG. The mold I descends, and the lower surface of the stripper 2 holds down the metal foil c on the cutting edge surface a,
FIG. 5 shows a state in which the metal foil b is blanked at the tip of the punch 1 and is being pushed down to the lower surface of the intermediate die 3, and FIG. 5 shows a state in which the upper die I is at the bottom dead center position.

The operation of the upper mold I from the top dead center to the bottom dead center will be described in order. The metal foil material c is a band-shaped hoop material, and is continuously supplied from slits provided on both sides of the cutting edge surface A of the intermediate die 3.
Is supplied alone or continuously. When the upper die I descends from the top dead center, first, the lower surface of the intermediate die 3 comes into contact with the upper lid a positioned on the press-contact die 4, and the upper lid a is pressed by the lower surface of the intermediate die 3.

When the descent is further continued, the distance between the lower surface of the stripper 2 and the cutting surface A gradually decreases, and the metal foil material c
Is sandwiched between them. Thereafter, when the tip of the punch 1 passes through the lower surface of the stripper 2 and enters the hole c of the intermediate die 3 at the tip, the metal foil b is blanked from the metal foil material c. The blanked metal foil b is pushed down while being in close contact with the tip of the punch 1, penetrates the hole c of the intermediate die, and reaches the upper surface of the upper lid a positioned on the upper surface of the press-contact die 4. Then, it is cold-pressed so as to close the ventilation hole d of the upper lid, and is completed as a split-type safety valve.

A feature of the cold pressing mold according to the present invention is that when the punch 1 penetrates the intermediate die 3, the metal foil serving as a safety valve is cut from the continuously supplied metal foil material c on the cutting edge surface a. Ranking, and using the inner surface of the through-hole of the intermediate die 3 as a guide, push down with the tip of the punch 1 to
It has a function and a structure which are positioned on the upper surface of the ventilation hole (d) and cold pressed as it is.

[0012]

The effect of the present invention is that the step of blanking the metal foil serving as a safety valve from the metal foil material and the step of cold-pressing the metal foil on the top lid can be processed at the same time. That's a lot solved. In the conventional blanking process, multiple metal foils are stuck together and overlapped, and there is a problem that multiple metal foils are cold-welded as they are, and after cleaning the metal foil after blanking, The problem of scratching during transportation, and the problem of cold welding failure due to the influence of wind and static electricity after positioning at the cold welding position, etc., are solved. Shortening and improvement of processing accuracy are realized,
Mass production processing of safety valves by the cold welding method of metal foil, which has high tearing accuracy and reliability, has become possible.

[Brief description of the drawings]

FIG. 1 is a basic structural diagram of a cold-welding mold according to the present invention.

FIG. 2 is a sectional view of the top dead center position of a mass-produced mold.

FIG. 3 is a cross-sectional view of a contact state between an upper mold and a lower mold of a mass-produced mold.

FIG. 4 is a cross-sectional view of a mold for mass production immediately after blanking of metal foil.

FIG. 5 is a cross-sectional view at a bottom dead center position of a mass-producing mold.

[Explanation of symbols]

 1. Punch 2. Stripper 3. Intermediate die 4. Pressure welding die 5. Spring a. Top lid b. Metal foil c. Metal foil material a. Cutting surface b. Slit c. Hole in intermediate die d. Vent I. Upper type II. Lower mold

Claims (1)

[Claims] 1. When joining a metal foil blanked into an arbitrary shape to a metal member by a cold pressure welding method, while the upper die of the cold pressure welding mold descends from the top dead center to the bottom dead center, First, the metal foil is blanked into a predetermined shape from the metal foil material by the intermediate die provided on the stripper plate, and then the blank of the metal foil is pushed down to the press contact surface of the metal member with the tip of the punch, leading to the bottom dead center. A cold-welding processing method and a cold-welding die used for this.