JPS6033591B2 - Laser welding method for battery sealing part - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser welding method for a battery sealing part.

Recently, laser beam welding of thin sheet metals has been put to practical use, and batteries have been developed that use this technique to weld the sealing portion between the case and the cap.

In the case of laser welding, the tip of the laser beam (condensing part) is extremely small, so if you do not make sure that the laser beam is irradiated accurately on the mating surface of the materials, that is, the joint surface of the battery case and the cap, it will cause damage from both sides. Insufficient melting of the material,
In addition, the warping of the cap due to localized high heat during welding and the expansion pressure of the electrolyte and gas within the battery exert an upward force on the cap, causing displacement of the competing surfaces of the unwelded portions, resulting in poor welding. This state is shown in Fig. 1, where A shows the normal state of the mating surface a of the battery case 1 and the cap 2, and the opening shows the competing surface b.
This shows the state in which the two lines are out of alignment. In the present invention, prior to laser welding, approximately V-shaped grooves are formed by punching several places on the upper surface of the saddle mating edge formed by the battery case mouth edge and the rising edge of the cap. At the same time, the competing parts are reinforced to make the joint green smooth, preventing the cap from warping during subsequent welding and pushing the cap up due to the expansion pressure inside the battery, and welding without any deviation on the outer and outer surfaces. The purpose is to

The battery consists of a stainless steel case 1 and a cap 2.
An electrode body (not shown) impregnated with an electrolytic solution is housed in this case, and the rising edge green 2' of the cap 2 is iron-fitted to the rear case opening green.

The case 1 and the cap 2 constitute a one-polar terminal, and the other-polar terminal 3 is insulatively attached to the cap. Next, as shown in Fig. 3, the upper surface of the Tetsugo green is pierced with a punch-like stamping piece 4 having a V-shaped tip to a depth of approximately 0.3 mm.
A V-shaped kerf 5 is formed about the size of a mackerel (about 4 mm wide compared to the height of the rising edge of the cap).

Several stamping pieces 4 may be attached to an annular body (not shown) that matches the iron surface so that the kerfs 5 can be stamped at several locations (four locations in the figure) at the same time.

After the engraving process is completed, case 1 and cap 2 are stamped using a laser beam emitted from a fixed laser source as usual.
Weld the steel surfaces with. In this case, the competing surface of the battery to be welded rotates through the laser beam condensing section, and welding is completed in one rotation. As described above, in the method of the present invention, when the bonded edges of the battery case opening green and the rising circumferential green of the cap are sealed by laser welding, prior to laser welding, the upper surface of the bonded green is stamped at several places to form approximately V. Since a character-shaped cut groove is formed, this stamping forcibly makes the steel plate without any level difference, and at the same time, the case and the cap are caulked together, thereby reinforcing the mating part.

Therefore, warping of the cap due to heat during welding is suppressed, and even if the internal pressure of the battery increases, the bonding surfaces will not shift and weld defects will not occur. Therefore, there is no need for a relief hole for the internal pressure of the battery as in the past, and welding can be performed with the electrode body in the battery pre-impregnated with electrolyte, and there is no need to hold down the cap during welding, making the process easier. The laser welding process is simplified and more reliable, as it is only necessary to add several stamping steps to the upper surface of the iron joint edge.

[Brief explanation of the drawing]

Figure 1 A shows the condition of the metal fitting between the case and the cap during welding. FIG. 2 is a perspective view of a battery produced by the method of the present invention, and FIG. 3 is an enlarged view of the lozenge showing the stamped state of the same battery. 1...Battery case, 2...Cap, 3...Terminal, 4
... Stamp piece (punch), 5 ... V-shaped cut groove. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. After fitting the rising peripheral edge of the cap to the lip of the battery case, punch several places on the upper surface of the fitting edge to form approximately V-shaped grooves, and then the above-mentioned fitting. A laser welding method for battery sealing parts, which is characterized by sealing the edges by laser welding. 2. The laser welding method for a battery sealing portion according to claim 1, wherein the stamping is performed simultaneously using several stamping pieces arranged on a circumference that matches the fitting edge.