JPS62208552A - Manufacture of grid for lead-acid battery - Google Patents

Abstract

PURPOSE:To increase corrosion resistance at high temperature by rolling a part or the whole or a perforated lead or lead alloy plate having a casted optional pattern to form a new perforated pattern by spreading the metal into the holes. CONSTITUTION:A part or the whole of a cast perforated plate 1 having a skeleton pattern formed optionally is rolled to form a new skeleton pattern by spreading lead or lead alloy into holes in the cast perforated plate 1. A cast having large grain boundaries is spreaded and the large grain boundaries are changed to fine grain boundaries. Thereby, corrosion resistance is remarkably increased and hardness is also increased.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to improvements in lead-acid batteries, and more particularly to a new method of manufacturing grids for lead-acid batteries.

In the paste-type electrode plate, which is the most commonly used electrode plate for conventional lead-acid batteries, the grid serving as its framework plays an important role as both a paste holder and a current collector. The most popular structure for this grid has been the grid-like grid pattern since ancient times, and it is common to have frame ribs that frame the periphery of the electrode plate and a groove with a small cross-sectional area. be. These were then cast by pouring molten lead (lead alloy) into a mold to form the final bone pattern. Furthermore, with the trend toward maintenance-free construction, the expansion method, which was recognized for its high productivity and developed mainly by using calcium alloys, appeared. By rediscovering the advantages of being able to construct a grid, a method has been developed to form a pole-plate-sized skeleton from a strip-shaped grid by continuous casting.

Problems to be Solved by the Invention However, cast bodies generally have relatively large growth of dendrites and tend to be susceptible to intergranular corrosion. Particularly in recent years, the temperature under the hood of automobiles has continued to rise due to the trend toward more efficient engines, and the tendency for high-temperature corrosion has become noticeable. In addition, new problems have arisen, such as accidents in which even thick frame bones are severed.

Although this tendency is particularly likely to occur in calcium alloys, it has become clear that even antimony alloys, which were conventionally said to be strong at high temperatures, have a similar phenomenon and shorten the battery life.

The present invention aims to achieve its original purpose as a grid that is excellent in high-temperature corrosion while taking advantage of the advantage that casting allows easy formation of arbitrary porous patterns.

Means for Solving the Problems To achieve this objective, the present invention involves rolling a part or all of a cast perforated plate having an arbitrarily formed skeletal pattern, and rolling the perforated plate obtained by casting. The present invention provides a method for manufacturing a grid for a lead-acid battery, which is characterized by forming a new skeletal pattern while spreading a lead alloy in a lead matrix.

This rolling operation deforms the original shape, which is an extremely unreasonable idea compared to the conventional idea of forming the final grid shape by casting. The present invention is based on the idea of breaking through this barrier of common sense and using the shape deformed by rolling as the final grid skeleton pattern.

According to the method of the present invention, a cast body having large grain boundaries is rolled and transformed into fine grain boundaries, and its corrosion resistance and hardness are significantly improved.

Embodiment FIG. 1 is an example of a process of rolling a continuously cast perforated plate by applying the present invention, and is an example of processing using a rolling roller.

In the figure, 1 is a cast continuous belt-shaped perforated plate, 2 is an upper roller for rolling,
3 is the lower roller. Note that rolling may be performed in multiple stages if necessary. Further, in this example, a rectangular concave pattern 4 is provided on the rollers 2 and 3, and protrusions 6 are formed on the new rolled plate 5 from A to B of the conventional skeleton pattern in FIG. The skeleton of the holder is formed continuously in the rolling section.

The above-mentioned concave pattern may be provided on either the upper roller or the lower roller as necessary, or may not be formed if it is not necessary. However, the upper and lower recess patterns do not necessarily have to match. These protrusions help the adhesion of the active material to the skeleton. Additionally, the recess pattern need not match the location of the original cast skeleton. This is because the original skeleton will be rolled and given new dimensions. Furthermore, if a new lattice frame or backbone pattern is formed not only by knurling but also by a concave pattern, it will be convenient for cutting into the next grid shape.

Furthermore, when a continuous cast band is processed, it is efficient to cut it after applying the paste.

On the other hand, when casting is carried out one panel at a time as in the past, it is preferable to cast with smaller lattice meshes in accordance with the rolling rate so that the dimensions after rolling will be the desired dimensions.

From the above, it is clear that the present invention stretches the crystalline structure of the original casting through the processing steps of rolling and stretching, but it is further important to note that this has a remarkable effect on the high-temperature life of the battery. Explain in detail.

Using the rolled grid P according to the present invention and the conventional cast grid Q, an electrode plate for JIS standard 56D23 was created using the same paste.

In addition, the evaluation includes not only the oxidation caused by overcharging but also the stress of expansion of the active material, including complete discharge at a 5-hour rate at 90°C, then leaving it for 8 hours, and charging at a 5-hour rate for 8 hours. A cycle life test was conducted. Note that the grid is 0.
A lead-lucium tin alloy containing a standard tin amount of 0.3 weight ratio was used.

As a result, a noticeable difference appeared between the 15th and 20th cycles, and the third
As shown in the figure, Q showed early deterioration.

When this battery was disassembled at the same time, it was found that in the conventional Grid Q, the electrode plate was deformed into an egg shape, and the internal core was cut off at various places although it was not visible from above the active material, showing signs of intergranular corrosion. It was showing. On the other hand, in P, the active material was sufficiently retained, deformed little, and remained stable for a long period of time. Although this example shows an example of a calcium alloy which has the largest deformation, all alloys can similarly suppress intergranular corrosion during casting.

In other words, the present invention is not a conventional cast body itself, but a new pattern is formed with a completely deformed and delayed structure.
This means that a highly reliable grid with less intergranular corrosion has been realized.

Effects of the Invention As described above, the present invention opens up new possibilities for the application of storage batteries to high-temperature fields, as well as to automobiles that experience high temperatures, and its industrial value is extremely high. be.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the rolling process in an embodiment of the present invention, Fig. 2 A and B are sectional views showing a cast body and a skeleton pattern after application of the present invention, and Fig. 3 is a diagram showing a grid of the present invention and a conventional grid. It is a figure showing the life test result of. 1...Casted continuous strip perforated plate, 2...
・Upper roller, 3...Lower roller, 4...
Concave pattern, 5...Rolled plate, 6...
Projection.

Claims (4)

[Claims] (1) Part or all of a cast perforated plate of lead or lead alloy with an arbitrary pattern is rolled, and a new perforated pattern is formed by extending the metal part into the holes of the perforated plate. Method for manufacturing grids for lead-acid batteries. (2) The lead-acid battery according to claim 1, wherein the rolled porous pattern is formed by rolling at least one side in a mold having a rolling part and an arbitrary pattern of recesses formed in the rolling part. Method of manufacturing grids for use. (3) The method for producing a grid for a lead-acid battery according to claim 1 or 2, wherein the cast perforated plate is a continuous cast body in the form of a long strip. (4) The method for producing a grid for a lead-acid battery according to any one of claims 1 to 3, wherein rolling is performed by passing the cast body between rollers having an arbitrary concave pattern.