JP3222988B2 - Manufacturing method of lead storage battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a lead-acid battery, and more particularly to an improvement of a lead-acid battery having a strap configured to use a rolled lead alloy containing minute calcium as a cathode grid. .

[0002]

2. Description of the Related Art In recent years, in a lead storage battery, a continuous cast body of a so-called calcium alloy in which a lead alloy containing a small amount of calcium is added and tin or the like is added to the lead alloy in order to improve liquid reduction characteristics and improve productivity. Slabs) are cold rolled into a sheet shape in multiple stages, developed into a net shape, and used as a grid. That is, a method of manufacturing an electrode plate in which a machined process such as expanding or punching is performed on the rolled sheet to form a continuous network, an active material paste is applied thereto, and the shape of the electrode plate is formed from the continuous body. General. The lugs of the grid, which are the current collectors of these electrode plates, are usually formed from a non-reticulated part continuous with the reticulated body, that is, a rolled sheet.

[0003] The positive and negative electrode plates obtained in this way are collectively welded to a shelf-shaped strap with ears of the same polarity by burning or cast-on method. When a calcium alloy is used for the ear, the melting point is relatively high and the penetration is relatively poor compared to the lead alloy. Burning is often used in which the upper part of the ear protruding in the recess formed by the mold is added to the lead alloy and melted with a burner.

[0004]

In the lead-acid battery having the above-described structure, when the amount of electrolyte decreases during use of the battery, a phenomenon is seen in which the corrosion is rapidly broken at the base of the grid side on the cathode side to the strap. Sometimes. This phenomenon not only deteriorates the performance but also causes sparks in some cases, and in the worst case, the gas remaining inside the battery is ignited and ruptured.

Conventionally, this phenomenon has been attributed to insufficient welding of the alloy or adhesion at the interface, and modification of the interface such as reinforcement of welding energy or application of flux has been studied.
Despite some improvement, corrosion of the part exposed under the strap remained as an issue. An object of the present invention is to sufficiently perform welding of an ear by this burning method, and at the same time, suppress cathodic corrosion at an exposed portion of the ear, and improve the reliability and safety of the battery.

[0006]

As a means for solving the above-mentioned problems, the present invention relates to a case where a negative electrode plate having a roll of a lead alloy containing a small amount of calcium as a lug lug is collectively welded to a strap and used. , Ear thickness T (mm) and depth D of the lower end of the molten nugget (melted and solidified part) at the tip of the ear
The present invention provides a method of manufacturing a lead storage battery, wherein the thickness of the ear is set in a region of T ≧ 1.1−D / 6 in relation to (mm). Here, the rolled body is preferably 8% or more of the thickness of the cast slab before rolling. The thickness of the ear is preferably 1.0 mm or more.

[0007]

According to the present invention, the above-mentioned corrosion phenomenon is caused inside the strap.
In particular, it is related to the structure of the thermal hysteresis layer in which a large grain boundary is formed beyond the original fibrous rolled structure under the influence of heat in the area of the ear. It contributes to corrosion breaks and is further based on the finding that the thermal history layer in question has a deep relationship between the depth of the nugget and the thickness of the ear in the fusion zone. That is, the boundary between the molten nugget and the undissolved portion at the tip of the ear indicates that it is a coexistence region of the solidified melt, and is the tip that gives the thermal history of the ear. The depth D depends on the thermal power of the burner. The greater the thermal power, the shallower the depth D, and the smaller the thermal power, the greater the depth. At this time, the heat is radiated to the lower lattice portion through the ear tissue, and a portion having a large heat history and a portion having a small heat history are formed in the ear. Naturally, near the surface of the ear facing the dissolved layer of added lead is susceptible to thermal history.

In such a situation, the depth N at the upper end of the non-thermal history region can be made shallower than the nugget. This depends on the depth of the nugget and the heat dissipation of the ears. If the nugget depth D is shallow when the ear is thin and heat radiation is small, the tip of the non-heat hysteresis region is located outside the root of the strap. That is, at this time, the risk of corrosion fusing increases.

The area of the present invention is to clarify the thickness of the ear to be adopted when selecting the depth D of the nugget in order to enhance the weldability, and conversely, it is acceptable if the thickness to be used is determined. The position of the nugget depth D, that is, the welding conditions can be determined. The degree of occurrence of large grain boundaries that lead to disconnection due to the above-mentioned thermal history is also affected by the ratio of the thickness of the roll from the original slab.

[0010]

The present invention will be described below in detail with reference to examples. 1 to 3 show examples of the partial structure of the ear welding portion of the strap. FIG. 1 is a diagram illustrating an ideal structure of the present invention. FIG. 2 shows a structure in which the relationship between the thickness T of the ear and the depth D of the molten nugget is at an appropriate limit. FIG. 3 shows an example of a structure that causes a conventional problem that deviates from the proper area of the present invention.
Here, 1 is a negative electrode plate and 2 is a lug of a negative electrode grid,
12m of calcium alloy of 7% calcium-0.3% tin
m is a part of a sheet that has been multi-rolled to 1 mm at a rolling thickness ratio of 8.3% from a cast slab of m. 3 is an inter-cell connector, 4
Is an alloy of a strap, and an antimony alloy or a tin alloy is used. 5 is the boundary of the melted nugget where the tip of the ear has melted and solidified, 6 is the tip of the non-thermal history area that has not undergone thermal history, and 7 is the surface of the ear facing the melted lead. Here, T is the thickness of the ear, D is the depth of the boundary of the melting nugget at the tip of the ear, and N is the depth of the tip of the non-thermal hysteresis region.

FIG. 4 is a diagram for explaining the principle that the ear thickness and the nugget depth D affect the risk of the non-thermal hysteresis region jumping out to the ear-exposed portion. The ear thickness T is T ₁ ; 1.0
mm, T _2; in the 0.75mm constant by changing the welding energy, the result of examining the relationship between the depth N of the tip of the thermal history area, D _1, D ₂ corresponding to T _1, T ₂ In the following, the non-thermal history area will be protruded from the strap. That is, D ₁ and D ₂ correspond to the allowable lower limit value D _lim of the nugget depth D at the ear thicknesses T ₁ and T ₂ .

FIG. 5 shows the thickness T of the ear and the allowable lower limit D _lim.
And the safety area and the danger area in the relationship between T and D. Empirical formula T = 1.1−D / 6
Is divided into a dangerous area K in which the non-heat history area jumps out to the ear-exposed portion and a safety area S with less danger. That is, the safe design area in the burning method that needs to sufficiently dissolve the tip of the ear is T ≧ 1.1.
This is a region of -D / 6. If this region is ignored, there is a possibility of corrosion and fusing.

From a different point of view, conventionally, the ears are simply thinned in order to reduce the weight of the material and rationalize it, and the nugget depth is reduced by increasing the energy in order to increase the welding strength. That is what happened. Furthermore, if ears having a thickness of 1.1 mm or more are used in the drawing, sufficient welding can be freely performed over a wide area up to the nugget depth of zero. However, the depth D of the nugget is 0.5 mm to 3 mm
In view of the above, a battery having wide and stable reliability can be provided by selecting an ear thickness of 1.0 mm or more.

[0014]

As described above, according to the present invention, a design value which can be controlled so that the heat history area of the rolled body, which is a cause of the cathodic corrosion of the special grid ear, does not cross the ear exposed area from the strap is determined. And to improve the reliability and safety of lead-acid batteries.

[Brief description of the drawings]

FIG. 1 is a cross-sectional side view of a main part showing an ideal structure of an ear welding portion of a strap of the present invention.

FIG. 2 is a cross-sectional side view of a main part showing a structure in which a relationship between a thickness T of an ear and a depth D of a molten nugget is at an appropriate limit.

FIG. 3 is a cross-sectional side view of a main part showing a structure of a conventional ear welding portion that causes a problem.

FIG. 4 is a view for explaining the principle that the ear thickness and the nugget depth affect the risk that the non-thermal history area jumps out to the ear-exposed portion.

FIG. 5 is a diagram showing a relationship between an ear thickness and an allowable limit value of a nugget depth, and a safety region and a danger region.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Negative electrode plate 2 Negative grid ear 3 Inter-cell connector 4 Strap alloy 5 Boundary of melted and solidified melting nugget at ear tip 6 Tip of non-thermal hysteresis area 7 Ear surface facing added lead T Ear thickness S D Depth of melting nugget N Depth of tip of non-thermal history area

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaki Okumura 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-2-56853 (JP, A) JP-A-63-237355 (JP, A) JP-A-1-167951 (JP, A) JP-A-5-335509 (JP, A) JP-A-6-349476 (JP, A) JP-A-5-89870 (JP, A) JP-A-63-237354 (JP, A) JP-A-53-115037 (JP, A) JP-A-54-27933 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 2/28 H01M 10/14

Claims (3)

(57) [Claims] When a negative electrode plate having a roll of a lead alloy containing a small amount of calcium as a lug of a grid is collectively welded to a strap by burning, a thickness T (mm) of the lug and a melted and solidified portion of the lug tip are obtained. The thickness of the ear in the region of T ≧ 1.1−D / 6 (where 0.5 ≦ D ≦ 3 ) in relation to the depth D (mm) of the lower end of the lead-acid battery. Manufacturing method. 2. The method for producing a lead storage battery according to claim 1, wherein the rolled body is at least 8% of the thickness of the cast slab before rolling. 3. The method for producing a lead storage battery according to claim 1, wherein the thickness of the ear as the rolled body is 1.0 mm or more.