JPS6077359A - Manufacture of rolled sheet for lead storage battery - Google Patents

Abstract

PURPOSE:To improve the tension resistance and the life characteristic of a lead sheet of a high rolling rata by using effective combinations of rolling temperature and the rolling rate in manufacturing the lead sheet. CONSTITUTION:When manufacturing a rolled sheet for a lead storage battery form a lead plate having a thickness (T0) at least 10 times the thickness (T1) of the rolled sheet to be obtained, the lead plate of T0 thickness is rolled at a temperature of 70-180 deg.C until its thickness becomes 4-7 times the thickness (T1) of the rolled sheet. Following that, rolling is performed at a temperature of 65 deg.C or below until the rolled sheet of T1 thickness is obtained. By the means mentioned above, it is possible to increase the tension resistance of the sheet and to improve the life characteristic of the sheet when it is used for a battery.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing rolled sheets for lead-acid batteries.

Structure of the conventional example and its problems Rolled sheets for lead-acid batteries are generally made by rolling a lead plate under a temperature condition of 20 to 60°C. The lead sort rolled under such conditions forms a fine fibrous rolled structure. In addition, mechanical strength such as tensile strength increases, and in terms of corrosion resistance, it becomes a form of general corrosion, which prevents the grid-like current collector from breaking due to intergranular corrosion. The lead plate phoneme A2 was created.

A method is adopted in which a sheet of a predetermined thickness is formed by passing the coil between rolling rollers multiple times. Here, the rolling rate ρ is the difference in the thickness (io, 1.) before and after rolling (X100) before and after rolling.
A rolled sheet for a lead-acid battery is rolled at a total rolling rate of 80 to 90φ from the thickness TO of the cast lead plate to the final thickness T1 of the rolled sheet. Therefore, it was found that when the total rolling ratio was increased to 90 to 96% or more, the tensile strength decreased.In addition, when a battery using sorto made under such conditions with a large total rolling ratio was subjected to repeated deep discharges, However, there was a drawback that the capacity decreased early.

Therefore, the total rolling ratio is 80-90%, and the maximum is 96%.
If these conditions are not maintained, properties such as tensile strength and battery performance will deteriorate. However, when considering productivity, it is necessary to increase the production speed by making the casting process continuous with the rolling process. The rolling speed can be increased by increasing the number of rotations of the rolling rollers, but it is not possible to dramatically speed up the casting process due to problems with castability. Therefore, it is necessary to increase the thickness of the lead plate material.

For this reason, the rolling ratio in each rolling process is being considered.
Unfortunately, we are not getting enough results.

Purpose of the Invention The present invention provides V,
It is an object of the present invention to provide a rolled notebook for a lead-acid battery that has high tensile strength and completely suppresses early decrease in capacity in terms of battery characteristics.

Structure of the Invention In order to achieve the above object, the present invention provides a method for manufacturing a rolled notebook for a lead-acid battery using a lead plate having a thickness (TO)' which is 10 times or more the thickness (T1) of the rolled sheet to be served. According to the method, rolling from a lead plate (TO) at a temperature 4 to 7 times the thickness of the rolled sheet (T1) is performed at a temperature of 70 to 180°C, and subsequent rolling is performed at a temperature of 65°C or less. It has all the characteristics. This allows for notes on the tensile direction.

It is possible to improve the life characteristics when used in batteries.

Description of examples Hereinafter, one aspect of the present invention will be explained in detail. Thickness: 40mm.

Three rod-shaped lead plates with a width of 80 mm and a length of 5 m were manufactured using a continuous casting machine. These three lead plates were rolled six times to a thickness of 1.0
A rolling sort of throat (A, B, C) was made. The rolling rate is 3
The same conditions were used for books. Further, the temperature conditions during rolling were set as follows.

Note A was rolled for the third time with a thickness of 6, kept at about 100°C by heating, and from the fourth to the final rolling 1.
Then, it was cooled with water to 40°C. For Note B, all six rolling steps were heated to 100°C. Sheet C was cooled to 40° C. during all six rolling steps.

Figure 1 shows the tensile strength of five test pieces obtained from each sheet. As is clear from the figure, the tensile strength of sheet A is higher than that of sheets B and C. The thickness of the cast lead plate was varied from 3 to 50 degrees, and each was water-cooled and rolled at 60°C to a final thickness of 1.0 M.
The tensile strength was also investigated when the sheet tra was made. As is clear from the results shown in Figure 2, the tensile strength I''1
It can be seen that the tensile strength of sheets rolled from lead plates with a thickness of 6 to 10 mm is the highest, and that the tensile strength decreases when the rolling rate is low and, conversely, when the rolling rate is extremely high.From this result, the rolling rate can be determined. If the rolling rate is increased, a fine fibrous rolling structure is formed and the tensile strength increases, but if the rolling rate becomes too high, the fibrous structure becomes even finer and the tensile strength is thought to decrease, so the tensile strength cannot be maximized. It is thought that there is an optimal fibrous rolling structure to achieve this.

Therefore, it is thought that the tensile strength results of the sheets A, B, and C above indicate that even if the rolling rate is increased, rolling at high temperature makes it difficult to form a fine Iva rolling structure. Note A made by the manufacturing method is difficult to form a fine rolled structure when rolled at a high temperature in the third stage, and it is only in the latter three stages that a fine rolled structure is substantially formed. This is thought to be due to rolling. C
In this respect, the rolling rate in the present invention is consistent with the optimum rolling rate shown in the second factor.Since all the rolling operations are carried out at high temperatures, the rolling structure is It is thought that fine graining has progressed and the tensile strength has increased due to the hardness.On the contrary, in 7-C, the fineness has progressed too much and the tensile strength has decreased.

-7-) A, B, and C were each expanded. This was used as a current collector and filled with paste to form an electrode plate. Each notebook used has a voltage of 12V and a capacity of 13V.
I bought 5Ah (D'14711JA, B, Of). Two people discharged this battery to 10.s V, then charged it and
"130% of the discharge capacity was carried out at i2A. This charging and discharging cycle was made into one cycle, and a charge-discharge cycle test was conducted. The cycle life was defined as the time when the discharge capacity became 50 times or less of the capacity of the first cycle.

Figure 3 shows the results of the life characteristics. As is clear from the figure, battery A using sheet A manufactured by the manufacturing method of the present invention is
It has excellent cycle characteristics compared to batteries B and C. This is because Battery C uses Note C rolled at low temperature.
Since the structure of the current collector is extremely fine, corrosion of the current collector progresses uniformly and peels off in the form of a film, which reduces the adhesion between the active material and the current collector and degrades cycle characteristics. Conceivable.

On the other hand, from the observation of the current collector after the completion of the cycle characteristics, no) A
and cH1 Corrosion is progressing uniformly. However, the cycle characteristics of No. A are excellent, and it is presumed that corrosion progresses while maintaining the adhesion between the current collector and the active material, but the detailed mechanism is not clear.

Note B had fins on a part of the grid. It's Kade.

Although not shown in the examples, the JIS overcharge life decreased. From these facts, it is thought that Note B has a thick crystal structure and so-called intergranular corrosion has occurred.

As mentioned above, in the manufacturing method of sheets with a high rolling rate,
Thickness (T,') 4 to 7 times the predetermined sheet thickness (T1)
It is thought that by rolling at a high temperature of 70° C. or higher, the refinement of the rolled structure is completely suppressed.

When rolling is carried out by varying the temperature conditions as in the present invention, the suitable thickness for the final rolling at a temperature of 65°C or lower is 4 to T times the sheet thickness; The effect decreases as the thickness or conversely decreases. This range differs from the results shown in FIG. 2 (5 to 10 times). This seems to be due to the difference between directly rolling a cast plate and the method of the present invention in which the thickness is increased by 4 to 7 times.

On the other hand, when rolling a lead plate T to a thickness T + "E, 7
At temperatures below 0°C, the effect was significantly reduced, and at temperatures below 65°C, no effect was obtained. There was almost no difference in characteristics at temperatures above 70°C, but when the temperature exceeds 180°C, the lead plate becomes too soft and difficult to handle during manufacturing. It's better to do it.

One way to make a high-quality product is to increase the temperature of the lead molten metal and/or the mold temperature during the casting process to produce the lead plate, thereby raising the temperature of the entire cast lead plate. is possible. Furthermore, there is also a method of increasing the temperature using hot air or the like. In the present invention, regardless of the means of high temperature VC.

A similar effect was obtained.

In addition, the last 7-t thickness t from tl. Rolling at 1 is 65
It has been found that excellent properties can be obtained if the temperature is below °C. Therefore, there is no need to use special equipment to lower the temperature to extremely low temperatures (for example, below 5°C). It's ox (
After rolling under high temperature conditions in the ox, it is left to cool naturally or rapidly cooled by water, etc., and then rolled again from 11' to -!
The effect of the present invention can be obtained even if the final rolling is performed at , but from tI to + and from 11' to t. Even if the rolling at step 1 is carried out continuously, the temperature can be sufficiently lowered to 65° C. or lower by water cooling during rolling from t,', so it is not necessary to leave the material in the middle of rolling, especially in the present invention.

Effects of the Invention As described above, the present invention has improved tensile strength and life characteristics by a manufacturing method that most effectively combines the effects of temperature and rolling rate. As a result, the tensile strength of the rolled sheet decreases, and
This rolling note (when used in i7 batteries, it has not been practically put into practical use due to the decrease in life characteristics) However, the present invention makes it possible to increase the rolling rate Vr
In addition to improving productivity, costs can also be reduced.

[Brief explanation of the drawing]

Figure 3 shows the relationship between the thickness of the lead plate before rolling and the tensile strength. Figure 3 is a diagram showing the results of the photodischarge cycle life of batteries JJB and C. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure Sheet Figure 2 Thickness of Glue A Plate in front of Enobu Figure 3 Electric Excretion

Claims (1)

[Claims] A lead plate with a thickness more than 10 times that of the rolled sheet to be obtained is used for several months, and it is heated at a temperature of 0 to 180"C until the thickness of this lead plate becomes 4 to 7 times the thickness of the rolled sheet. Rolled,
A method for manufacturing a rolling sort for lead-acid batteries, which is characterized in that the subsequent rolling harrow is carried out at a temperature of 6°C or less.