JP2651207B2 - Lead Welding Method for Leaded Battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for welding a lead body in a battery with a lead body.

<Conventional technology> A battery with a lead body is used as a power supply for a power failure backup of an electronic device or the like. In order to perform a stable operation for a long period of time, a terminal surface of a battery such as a cylindrical battery or a flat battery is used. A configuration is employed in which a lead for current extraction is directly welded by resistance welding, laser welding, or the like.

When resistance welding is used, generally, a pair of welding electrodes are pressed from above a lead body adhered to the short side of the battery, and a fixed type welding machine or an AC welding machine is used. A method has been adopted in which a lead body is spot-welded to a battery terminal surface with a welding current.

<Problems to be Solved by the Invention> By the way, when the welding electrode is pressed against the lead body and resistance welding is performed, variations in the electrode shape, the pressing force, and the like are inevitable. When welding is performed with a constant welding current as in the above-described conventional method, the welding strength changes due to such variations, and therefore, the lead cannot be reliably welded to the battery terminal surface. There's a problem.

That is, in this type of welding electrode, an R is generally attached to the tip of the electrode so that the tip of the R intensively contacts the surface to be welded. Since this R gradually increases due to wear due to use, the contact area between the electrode and the lead body surface also increases. The contact area also changes depending on the pressing force of the electrode on the lead body. And, for example, when the contact area is widened, it is necessary to increase welding energy by increasing welding current or the like in order to secure welding strength. However, in the above-described conventional method, such control cannot be performed. Therefore, variations in welding strength cannot be avoided.

On the other hand, when the lead body is to be welded to the electric terminal surface with unnecessarily large welding energy, the battery performance deteriorates due to heat generation accompanying the welding. Such performance deterioration is particularly problematic when, for example, a thin lead plate of about 0.3 mm thickness is welded to the negative electrode terminal surface of a coin-shaped lithium battery having a thickness of 5 mm or less, and heat is generated inside the battery on the negative electrode terminal surface due to heat generation. The located negative electrode lithium is melted and scattered in a boiling state, and this may damage the separator and cause a short circuit inside the battery.

For this reason, from the viewpoint of reliability, the welding method of the lead body when using a flat type battery such as a coin type lithium battery is as follows.
At present, laser welding must be used.

The present invention relates to a method for welding a lead body, which can perform high strength resistance welding of a lead body to a battery terminal surface and can reduce thermal influence on the inside of a battery, irrespective of variations such as R and pressing force at the tip of a welding electrode. The purpose is to provide.

<Means for Solving the Problems> That is, according to the present invention, in a battery with a lead body formed by resistance welding a lead body to a terminal surface of the battery, a constant-power welding power source is used to keep a calorific value in a welded portion constant. And a method for welding a lead body in a battery with a lead body.

The constant power source described above measures the welding voltage and welding current in the welded portion successively during the energization period, and sets the welding voltage and welding current so that the power value (that is, the calorific value) calculated as the product thereof becomes a constant value. It is a power supply that controls the welding current and the welding current in a feedback manner to keep the heat value at the welded portion constant.

And, if this constant power source is used, for example, during the operation, the contact resistance between the welding electrode and the lead body is decreased due to an increase in the contact area between the welding electrode and the lead body. The welding current is adjusted to increase automatically.

<Operation> By making the calorific value at the welded portion constant by the constant power source as described above, a constant amount of heat is given to the welded portion during the energization period regardless of variations in the electrode shape, the pressing force, and the like. As a result, stable welding can be performed, and variations in welding strength can be prevented.

<Example> An example of the present invention will be described below.

In FIG. 1, one end of a stainless steel lead plate 3 having a thickness of 0.2 mm is placed on the negative electrode terminal surface 2 of a CR2032 type flat lithium battery 1, and a distance t is set from above the one end.
A pair of welding electrodes 4a and 4b made of chromium copper, which were separated only by pressure, were pressed into contact with each other, and the lead plate 3 was resistance-welded to the negative electrode terminal surface 2 as described below, thereby producing a battery with a lead body of the present invention. still,
The above distance t was 4.5 mm.

That is, FIG. 2 shows an electric circuit of the entire apparatus including a constant power supply and an example, which is used to make the calorific value at the welding portion of the lead plate 3 with the negative electrode terminal surface 2 constant. In this example, the power from the industrial three-phase AC power supply is
After being converted into direct current by a full-wave rectifier rectifier circuit 5 composed of a combination of rectifiers such as diodes, it is input to a power transistor unit 6 composed of a combination of a smoothing capacitor and a power transistor. The power is converted into two-phase AC power, further converted to DC through a step-up transformer 7 and further through a rectifier circuit 8, and then applied between a pair of welding electrodes 4a and 4b.

On the other hand, the power transistor section 6 is connected to a control circuit 11 via a drive circuit 9 for driving the power transistor.
(For example, the frequency of the output power is changed by phase control), and the output power value is adjusted.

Further, the control circuit 11 is connected to a heat generation amount setting unit 10 and an arithmetic circuit 12. Of these, a desired heat value at the welded portion is set in the heat value setting unit 10, for example, converted into a power value. The arithmetic circuit 12 includes a current at the welded portion (from the rectifier circuit 8 to the welding electrode 4).
a, 4b), and a current detector 13 for measuring a voltage (voltage between the welding electrodes 4a, 4b) V, and a voltage detector
Each of the fourteen outputs is input, these welding currents and welding voltages are sequentially taken in at appropriate timings, and a power value IV obtained by multiplying these values is calculated. From this calculated value, the heat value Q at the welded portion is obtained according to Joule's law Q = IV. In addition, the above-mentioned voltage V is a welding electrode.
The measurement was performed with the voltage detection terminal of the voltage detection unit 14 attached between 4a and 4b.

The control circuit 11 compares the power value calculated by the arithmetic circuit 12 with the power value set by the heat generation amount setting unit 10, and if the power values are different, appropriately adjusts the output power of the power transistor unit 6. Then, it functions so that the calculated power value matches the set power value. In this way, in such a manner, the calorific value of the welding electrodes 4a and 4b is feedback-controlled so as to match the calorific value set by the calorific value setting unit 10.

In addition, as the constant power source, in addition to the above, for example,
As shown in the figure, the power from the two-phase AC power supply is
After being rectified through 16 and stored in a large-capacity capacitor 17, the power from the large-capacity capacitor 17 to the welding electrodes 4 a and 4 b is transferred to the welding electrode 4 a by a power transistor 18 connected to the welding electrode side of the capacitor. In accordance with the value (product of the current value and the voltage value), the control circuit 19, the heat generation amount setting unit 20, the arithmetic circuit 21, the current detection unit 22, and the voltage detection unit 23
A configuration may be used in which feedback control is performed by a control unit configured by combining the above so that the amount of heat generated at the welded portion is made constant.

Then, using a constant power supply as described above, the energizing time is 6 m
With pulse output of sec and welding condition of welding power 3680W,
Also, the pressing force of the welding electrodes 4a, 4b to the lead plate 3 is 2kg, 4k.
g, 6kg, and the R of the tip of the welding electrodes 4a, 4b is 0.3 mm,
The batteries were changed to 0.5 mm, 0.7 mm, and 0.9 mm, and various kinds of batteries with lead bodies were manufactured by using pulse welding of the lead plate 2 and the battery terminal surface under various conditions.

On the other hand, under the same welding conditions except that a conventional capacitor-type welding machine and an AC-type welding machine were used, the welding current was kept constant and the lead body was welded to the battery terminal surface to produce various batteries with lead terminals. Produced.

Then, with respect to the batteries with lead terminals manufactured by the above three welding methods, the presence or absence of flying of the negative electrode lithium inside the batteries and the tensile strength of the lead body were examined.

These results are as shown in Table 1. This result is an average value of three batteries for each leaded battery. The pressing force (kg) indicates a pressure applied to the tip of the welding electrode.

From the above results, by using the welding method of the present application, the range of effective welding conditions is expanded, and as a result, even when the area of the welded portion changes due to, for example, abrasion of the welding electrode or variation in the pressing force, It can be seen that welding with high welding strength can be performed without adversely affecting the inside of the battery.

<Effects of the Invention> As described above, according to the method of the present invention, when the lead body is welded to the battery terminal surface by resistance welding, there is no thermal effect on the inside of the battery due to welding and the welding has high welding strength. Can be performed, and a method for welding a lead body in a highly reliable battery with a lead body can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a state where a lead body is welded to a terminal surface of a flat battery, FIG. 2 is an electric circuit diagram of an apparatus used in the method of the embodiment, and FIG. 3 is an electric circuit diagram of another apparatus. . 1 flat battery, 3 lead, 4a, 4b welding electrode, 5, 8, 16 rectifier circuit, 10, 20 heating value setting section, 1
1,19 ... control circuit, 12,21 ... arithmetic circuit, 13,22 ... current detector, 14,23 ... voltage detector.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hidenori Nakura 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (56) References JP-A-1-265449 (JP, A) Sho-63-152166 (JP, U) Sho-sho 61-19057 (JP, U) Sho-sho 63-152166 (JP, U)

Claims (1)

(57) [Claims] 1. A battery with a lead body formed by resistance welding a lead body to a terminal surface of a battery, wherein the resistance welding is performed by using a constant power welding power source and keeping a calorific value at a welding portion constant. A method for welding a lead body in a battery with a lead body.