JPS6326933Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a laser welding device for a battery sealing part.

Recently, welding of thin sheet metals using laser light has been put into practical use, and batteries using this welding for the sealing part between the case and the cap have been developed. 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 mating surface of the battery case and cap, it will cause damage from both sides. Insufficient fusion of the materials may occur, and the mating surfaces of the unwelded parts may become misaligned due to warping of the cap due to localized high heat during welding and upward force due to the expansion pressure of the electrolyte and gas within the battery, resulting in welding. This may cause defects.

This state is shown in FIG. 1, where C shows the fitting surfaces of the battery case 1 and cap 2 in a normal state, and A and B show the cases where the fitting surfaces are misaligned, respectively.

The present invention relates to an apparatus that prevents such displacement of the fitting surfaces and performs welding without a step, and an embodiment thereof will be described below with reference to the drawings.

The battery consists of a stainless steel case 1 and a cap 2. An electrode body (not shown) impregnated with electrolyte is housed in the case, and the rising edge 2' of the cap 2 is fitted to the rear case lip 1'. This mating edge is then laser welded and sealed. The case 1 and the cap 2 constitute a one-polar terminal, and the other-polar terminal 3 is attached to the cap 2 in an insulated manner.

Fig. 3 shows such a battery laser welding device, where 4 is a laser beam emitted from a fixed laser source, 5 is a battery mounting table for setting the battery to be welded in a buried state, and 6 is a material through which the laser beam can be seen. It is a pressing piece made of a flat glass plate, which is pressed and fixed onto the battery to keep the fitting edges of the battery case and cap flush.

During welding, the battery to be welded is first set buried on the battery mounting table 5, and then the pressing piece 6 is provided to press and fix the top surface of the battery, and in this state, the mating edges of the battery are flush with each other. It is maintained. Then, the laser 4 is irradiated from the surface of the pressing piece 6 to the fitting edge portion through the pressing piece 6, and the pressing member 6, the battery, and the battery mounting base 5 are rotated as shown by the arrow when the pressing member 6, battery, and battery mounting base 5 are in a fixed state. The laser beam 4 continuously welds the fitting edges, and the welding is completed by one rotation.

FIG. 4 shows another embodiment, showing the state of welding of the sealing part of a battery having an elliptical planar shape, and the pressing piece 6 used here has two or more pressing pins 7 vertically protruding from the lower surface. The lower surface of the pressing pin 7 is configured to be on the same plane parallel to the lower surface of the pressing piece 6. The lower surfaces of the two pressing pins 7 are brought into contact with the upper surface of the cap 2, and the pressing pins 7 press the cap 2 at two points to keep the fitting edges flush. The mounting base 5 and the pressing piece 6 are set in the same jig, and the pressing pin 7 is designed to press the cap 2 so that the fitting edge is flush with the cap 2. In this case, the pressing piece 6 when irradiating the laser beam 4
The movement of the fixed body between the battery and the battery mounting table 5 is performed in an elliptical shape. Note that the pressing pins that are not in contact with the battery in Figure 4 are used for batteries whose cap area is larger than that of the battery shown in Figure 4, and the four pressing pins are used depending on the shape and size of the battery. Therefore, it is selected appropriately and used for pressing the battery.

Conventionally, in this type of battery, a relief hole is provided in the cap to prevent the negative effects of the expansion pressure generated within the battery due to the high heat during welding.
It is used as a gas vent hole during welding, and also as an electrolyte injection hole after welding, and then this hole is closed.

However, with this method, the sealing work is complicated, and since the electrolyte is impregnated inside the battery, it takes time to pour the liquid, especially when using an electrolyte with poor impregnating properties such as an organic electrolyte. The amount of liquid becomes uneven, which also affects battery performance.

According to the present invention, the top surface of the battery to be welded is pressed and fixed by the pressure piece during welding, so even if the internal pressure of the battery increases due to the heat during welding, the mating surface will not shift and cause welding defects. It is something. As a conventional product, there is a device that presses the top surface of the battery during welding.This device has a notch for laser beam irradiation on the pressing piece, and rotates the battery mounting table while pressing the pressing piece against the top surface of the battery. Although welding is carried out by welding, if the pressure welding is too strong with the pressing piece, the rotation of the battery mounting table will not be smooth, and in the opposite case, the fitting edges will not be completely flush. In addition, the pressing piece required time-consuming machining of a notch.

In this invention, since the pressing piece is made of a material that can be seen through the laser beam, welding can be performed by irradiating the laser beam through the pressing piece while the pressing piece remains pressed and fixed to the complete wall. A battery with a completely welded sealing part is always obtained. Furthermore, since the laser beam is irradiated onto the battery through the pressing piece, there is no need to cut out the pressing piece for laser beam irradiation, and the device can be manufactured easily.

[Brief explanation of drawings]

Figure 1 A, B, and C are views showing the fitted state of the case and cap during welding, Figure 2 is a perspective view of the battery obtained by the present invention, Figure 3 is a perspective view of the present invention, and Figure 4 The figure is a perspective view of another embodiment of the present invention. 1... Case, 2... Cap, 4... Laser light, 5... Battery mounting stand, 6... Pressing piece.

Claims (1)

[Scope of utility model registration request] In a laser welding device for the battery sealing part used when laser welding the mating edge between the battery case and the cap, the battery mounting table on which the battery is set and the top surface of the battery are pressed so that the mating edge remains flush. and a pressing member made of a material through which laser light can be seen, and while the battery is pressed and fixed on the battery mounting table by the pressing member, a laser beam is irradiated from the surface of the pressing member through the pressing member to fix the fitting edge. A laser welding device for a battery sealing part, which performs welding.