JPS60115153A - Can bottom welding of enclosed ni-cd battery - Google Patents

Abstract

PURPOSE:To obtain the highly reliable connection part excellent in productivity by burning off a separator existing in the hollow part with a laser beam, while welding a negative collector terminal of the pole plate group to the battery can bottom. CONSTITUTION:Laser light 14 emitted from a laser light oscillator 13 is guided to a welding position by means of a mirror 15 while stopping this down to the beam diameter suitable for welding by means of a lens 16 having the proper focus distance, for being radiated on the negative connector terminal 6. This part is heated up to the temperature proper for welding by means of radiation of laser light 14 having the high energy density, while the negative collector terminal 6 and a part of the battery bottom 9 is melted for being welded. The separator 3 existing in the hollow part 4 is burnt off by the laser light.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealed Ni--Cd battery, and relates to a method for welding a collector terminal of an electrode plate to a bottom of a battery can.

As is well known, the sealed Ni-Cd battery used as a power source for electronic equipment, emergency lights, etc. is a thin plate-shaped battery.

It has a structure in which two electrode plates are wound together with a separator in between (hereinafter referred to as an electrode group) and housed in a cylindrical battery can. Usually, this type of battery has a battery can of e.
The electrode and the lid attached to the battery can via an insulator are the e electrodes, so the e and 0 polar plates are connected to the battery can and lid, respectively, via current collector terminals that are welded to each in advance. has been done.

1 to 4 show the structure of the above-mentioned electrode plate group and battery. FIG. 1 shows a group of electrode plates, where l is an e electrode plate, 2 is an e electrode plate, and 3 is a separator. Figure 2 is a view of the center of the electrode plate group viewed from directly above.
, 0 shows how the separator 3 is present at the beginning of winding of the bipolar plate.

As shown in the drawing, there is a hollow part 4 in the center of the electrode plate group with a diameter of approximately 5 mm, and the separator 3 extends from the tip of the e electrode plate 2 toward the tip of the theta electrode plate 1, approximately in the center of the hollow part 4. In other words, it exists in a shape that crosses the center of the electrode group. This situation arises because the winding method shown in Figure 3) is used. That is, when winding the electrode plate, insert the separator 3 into the slit provided in the center of the winding shaft 5 as shown in the figure.
, then turn the winding shaft 5.

As shown in the rear wheel (just separator 3 and separator 3)
Insert the pole plates 1 and 2 between them, then insert the winding shaft 5/7=
Rotate in the direction indicated. When winding is completed to the end of the electrode plates 1 and 2, the winding shaft 5 is pulled out from the completed electrode plate group (actually, the electrode plate group is moved). The space created by the removal of the winding shaft 5 is the hollow part 4, and therefore, the size and diameter of this part is determined by the diameter of the winding shaft 5.

FIG. 4 is a sectional view taken through approximately the center of the battery, showing the state in which the electrode plate group is housed in a battery can and assembled as a battery. As mentioned above, the θ current collector terminal 6 is welded to the e-electrode plate 1, and the e-collector terminal 6 is also welded to the bottom 8 of the battery can 7.
and are welded at their connecting portions 9. On the other hand, the ■current collector terminal IO is similarly welded to the e-electrode plate 2, and this ■current collector terminal 1
0 is welded to the battery cover 1 at the collapse point 12.

Now, resistance welding has conventionally been used to weld the above-mentioned θ current collector terminal to the bottom 8 of the battery can 7 (hereinafter, this welding will be referred to as "can bottom welding").

Needless to say, resistance welding completes welding in an extremely short time, and the welding equipment itself is relatively inexpensive, so it is a widely used method for assembling mass-produced products. In the case of bottom welding, there are the following problems, which have become a major bottleneck in automatic assembly lines.

FIG. 5 shows a conventional can bottom welding method using resistance welding. Contact the outside of the battery can directly below, and insert the other electrode 12 into the hollow part 4 from the top of the electrode plate group.
Weld by contacting with. The problems mentioned above are as follows.

(1) When inserting one of the welding electrodes 12 into the hollow part 4, as shown in FIG. (The separator 3 is not shown in the hollow part 4 in FIG. 5), so the electrode 12 cannot be easily inserted into the hollow part 4.
It frequently happens that the electrode 12 gets caught and is destroyed.

(2) Since the diameter of the hollow portion 4 is approximately 511II+ and the separator 3 is present inside, the electrode 12 placed here must be as thin as 3 mm at most. Therefore, water cooling of the electrode, which is normally performed, becomes impossible, and as the number of welding increases, the temperature at the tip of the electrode rises.
When it comes into contact with the electrode 12, it melts and adheres to the electrode 12. If such a state occurs, it will be impossible to insert the electrode 12 any further, and even if it is possible, the tip of the electrode will be coated with nylon, which is the material of the separator 3. This makes it impossible or difficult to apply welding current.

Due to the above-mentioned problems, continuous operation is almost impossible, especially in the case of automatic welding equipment, and an effective solution has been desired.

The present invention aims to solve the above-mentioned problems in conventional can bottom welding, and to provide a welding method that provides excellent productivity and a highly reliable connection.

Next, details of the present invention will be described. The basic idea is to use a laser beam, an electron beam, or a charged particle beam that can obtain a high energy density as a heat source for welding, and to insert a welding electrode into the hollow part as in the conventional method. The point is that you can weld without any problems.

FIG. 6 shows a welding method according to the present invention. This is a case of so-called laser welding in which a laser beam is used as a welding heat source, and the laser beam 1 emitted from the laser beam oscillator 13
4 to the welding position using a mirror 15, and then narrowed down to a suitable beam diameter for the welding 1 using a lens 16 having an appropriate focal length, for example, by 0.5 mm in diameter. irradiate on top. This part is heated to a temperature suitable for welding by being irradiated with a laser beam 14 having a high energy density, and a part of the e-collector terminal 6 and the battery can bottom 9 melts, resulting in the desired welding. That is why it is done.

The advantages of adopting such a welding method are as follows. First of all, in the case of resistance welding, the electrode had to be inserted into the hollow part 4 with great difficulty, but laser welding is a so-called non-contact type of welding, and it is necessary to insert the electrode into the hollow part 4. There is no need to make contact with electrodes, etc. It is sufficient to introduce the laser beam 14 into the hollow part 4 from outside the battery can 7.

Of course, if there is something blocking the laser beam before it reaches the connecting portion 9 of the can bottom 8, welding will be impossible.

In the case of can bottom welding, the separator 3 present in the hollow part 4 is a problem as it blocks the laser +l:;I 4, but the separator 3 present in the bottom part is It does not contribute to the purpose of insulating between the bipolar plates 2.1, and is essentially unnecessary. Therefore, there is no problem even if the laser beam burns it out. This is not possible with resistance welding electrodes, but since the laser beam 14 can be used in an appropriate manner (by narrowing it down, it is possible to continuously obtain various energy states), it is easy to burn out the separator 3. How to choose an optical system 1 Therefore, the lens 1 should be selected so as to obtain the most preferable energy density at the connection part 9 between the e-collector terminal 6 and the battery can bottom 8.
Even if the position of the laser beam 6 is fixed, if the beam diameter in the hollow part 4 is sufficient to have sufficient energy density to burn out the separator 3, the laser beam hits this part at the same time as it hits the separator 3. is burned off, so there is no problem with the original can bottom welding. If such an optical system cannot be selected and the laser beam 14 is cut off by the separator 3, the focal point will move, for example, toward the hollow part 4 where the separator 3 is located and towards the color F tc. It is sufficient to move the lens 16 in a similar manner, and finally position the lens 16 so that appropriate welding energy can be obtained at the connecting portion 9. Since the focal point is the part with the highest energy density, it is possible to burn out the separator 3 in two ways.

In laser welding, it is important that the materials to be welded are in sufficient contact with each other.

In particular, when the thickness of the material to be welded is approximately 0.2 to 0.3 mm, as in the case of actual welding, the energy density of the laser beam 14 is high, so the thermal effect is limited and welding can be carried out in an extremely short time.
If there is a gap between the materials to be welded, a hole will be created where the single ζ laser beam 14 hits, and the molten metal will scatter, and no welding will occur. In the case of resistance welding, the materials to be welded were brought into sufficiently close contact by the pressure applied to the two electrodes, but this cannot be expected in the case of laser welding. Even if the gap is as small as 02 to 1) 03, it must be considered a problem. For example, as shown in FIG. By drawing the connecting portion 9 of the electric terminal 6 to the inner surface of the bottom of the battery can to obtain close contact between the two, welding becomes more complete.

EXAMPLE The details of the present invention have been described above, but next we will describe one result of actually applying the present invention to can bottom welding of a sealed N1-Cd battery and examining its effects.

The battery considered was SC size, +200 mAh.
It has a capacity of . The θ current collector terminal 6 welded to the wound electrode plate has a thickness of 5 pcc with a thickness of 8 mm on the surface.
It has an N1 plating of ~10 μm.

e The connecting portion 9 provided at the center of the current collecting terminal 6 has a diameter of approximately 3 mm. On the other hand, the battery can 7 of the other party is made of 5PCB and the thickness of the can bottom 8 is 041R (Ni
The plating has a thickness of 8 to 10 μm.

Regarding the welding device, a C02 gas laser type oscillator 13 was used, and the device having the basic configuration as shown in FIG. 6 was installed in an automatic assembly line. Welding is performed by moving the focus of the beam from the upper part of the hollow part 4 to the lower part, and finally contacting the can bottom 8 and connecting part 2 of the current collecting terminal 6.
Although this was done in such a way as to position it above the center, the beam reached the connecting part 9 with the separator 3 burnt out as originally expected, and the e-collecting terminal 6 and the can bottom 8 were successfully welded.

Note that the welding conditions at this time are: welding energy 1
10 Joule irradiation time is 06 seconds. Welded part is Ni
The plating melted and filled the space between the e-collector terminal 6 and the can bottom 8, and a sample was subjected to a destructive test to examine the welding strength, and the tensile strength was approximately 9 to 13 Kp, indicating that the e-tab connection The container broke in such a way that part of it remained on the bottom of the can.

In addition, when this study was conducted, the work flowed at a tact of 8 seconds, but the line never stopped due to problems caused by welding during the approximately 2 hours of operation (this invention was adopted in an automatic assembly line). It has been proven that this method is possible.

Although text C has described the case of laser welding, it goes without saying that similar effects can be obtained also in the case of electron beam welding, which is the same non-contact type of welding.

As described above, according to the present invention, welding between the e-collector terminal and the bottom of the battery can can be performed reliably and in a short time without using a separator or other hazards as in conventional methods, and there is no variation in battery performance. It has great industrial value as it can be used in automatic battery assembly lines.

[Brief explanation of drawings]

Fig. 1 is a perspective explanatory view showing the wound electrode plate group, Fig. 2 is an explanatory view of the central part of the electrode plate group viewed from directly above, especially showing the separator position II, and Fig. 3 is an explanatory view showing the separator position II. An explanatory diagram showing the situation when winding the electrode plate, Fig. 4 is a cross-sectional view of the central part of the battery, Fig. 5 is an explanatory diagram showing the situation when welding the can bottom by conventional resistance welding, FIG. 6 is an explanatory diagram showing a method for welding the can bottom of a sealed Ni-Cd battery according to an embodiment of the present invention. 1 is an e-electrode plate, 2 is an e-electrode plate, 3 is a separator, 4 is a hollow part, 6 is an e-collection terminal, 7 is a battery can, 8 is a can bottom, 9 is a connection part of an e-collection terminal, 13 is a a laser oscillator, 14 a laser beam;
15 is a mirror, 16 is a lens patent applicant

Claims (1)

[Claims] A laser beam or an electron beam is introduced into the hollow part I in the center of the wound electrode group, thereby burning out the cell/sllator existing in the hollow part and cutting out the center of the electrode plate group. A method for welding the bottom of a sealed N1-Ccl battery, characterized by welding an electrical terminal and the bottom of the battery can.