JP2004311110A - Method for manufacturing storage battery grid and storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a storage battery grid having excellent corrosion resistance while maintaining mechanical strength, in which a slab is pressed by a multiple step roll press machine to manufacture a sheet, which in turn is machined through such as expanding machining to manufacture a storage battery grid, and to provide a storage battery using the storage battery grid manufactured by using the above method, having an excellent service life. <P>SOLUTION: The multiple step roll press machine has at least one set of rolls opposing each other having different linear velocities for rolling. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a grid for a storage battery and a storage battery.
[0002]
[Prior art]
The positive and negative plates of a storage battery, for example, a lead storage battery, are filled with a grid made of lead or a lead alloy, which is filled with a paste obtained by pulverizing lead powder mainly composed of lead oxide with dilute sulfuric acid, and after aging and drying, It is produced through a chemical conversion process in which oxidation and reduction reactions are caused electrochemically in dilute sulfuric acid as a liquid to generate lead dioxide on the positive electrode and lead on the negative electrode.
[0003]
The method of producing the lattice includes a casting method of injecting and solidifying a molten metal such as a lead alloy into a mold and a machining method of forming a mesh by punching or expanding a metal sheet made of a lead alloy or the like. There is. In recent years, the latter method, which has excellent productivity, is increasing.
[0004]
As a general method for producing a metal sheet, there are a method by continuous casting, an extrusion method, a rolling method, and the like. In particular, the rolling method using a roll is widely used not only in the field of iron and steel but also in the field of lead storage batteries using non-ferrous metals, for example, lead or a lead alloy because of high productivity.
[0005]
Generally, when a sheet is produced by rolling, a slab formed by continuous casting or forging is continuously passed between a pair of multi-stage roll presses to gradually reduce the thickness. Note that a slab refers to a plate-like metal object having a certain thickness so that a rolled sheet can be easily manufactured.
[0006]
When the slab is rolled and thinned, the crystal of the metal body of the original slab is crushed and finer, and a striped rolled structure appears in the rolling direction, thereby increasing the strength of the sheet. Up to a certain rolling reduction, the strength of the sheet tends to be increased by rolling, and the sheet is easily stretched, so that the workability at the time of cutting and unfolding in the subsequent expanding processing is improved.
[0007]
[Problems to be solved by the invention]
A metal sheet produced by a conventional rolling method, for example, a lattice produced by machining a lead alloy sheet, for example, when an expanded lattice is used for a positive electrode plate of a lead storage battery, a fine crystal structure is formed in the lattice. As a result, breakage and sudden deterioration due to local corrosion along the grain boundaries found in the cast grid did not occur. However, due to the fine crystal structure, the amount of corrosion of the entire lattice is increased, the phenomenon that the lattice is deformed and elongated is observed, and there is a problem that the active material is dropped and the life is short due to short circuit with the counter electrode plate . There is also a method of heat-treating and curing the sheet for the purpose of suppressing deformation, but another problem occurs in that the precipitate generated at that time lowers the corrosion resistance.
[0008]
Further, in order to improve the corrosion resistance of the lead alloy itself, additives and their amounts have been studied, but the method is limited.
[0009]
The problem to be solved by the present invention is to produce a sheet by rolling a slab, and to improve the corrosion resistance while maintaining the mechanical strength of the sheet in a method for producing a grid for a storage battery by machining the sheet. It is an object of the present invention to provide a method for manufacturing a storage battery grid and a storage battery having excellent life performance using the grid.
[0010]
[Means for Solving the Problems]
As means for solving the problems of the present invention, according to claim 1, for a storage battery, a slab is rolled stepwise into a continuous sheet by a multi-stage roll press machine, and the sheet is formed into a grid by a machining method. In the method of manufacturing a lattice,
A linear speed of at least one pair of opposing rolls of the multi-high rolling roll press machine is different.
[0011]
By rolling a pair of opposing rolls with roll presses having different linear velocities, the friction on the slab surface becomes larger than usual, and the slab is processed more strongly, so that the crystals become finer and the strength is improved. On the other hand, since a shear stress is applied to the slab, crystals uniform in the rolling direction are formed in the vicinity of the sheet surface, but crystal grain boundaries having a displaced orientation are generated inside. Therefore, the storage battery grid formed by expanding or punching the rolled sheet manufactured in this manner has a high mechanical strength as a sheet and is excellent in corrosion resistance, so a storage battery having stable life performance can be obtained. It turned out to be obtained.
[0012]
In this case, by setting the linear velocity ratio of the pair of opposing rolls to be equal to or greater than 1.025 and equal to or less than 1.20, the effect of the present invention appears steadily. It was found to be high and excellent in corrosion resistance. That is, when the linear velocity ratio is less than 1.025, the effect of applying shear stress to the slab is not sufficient by changing the linear velocity of a pair of opposing rolls, and the change in the structure of the rolled sheet is small. , Sufficient corrosion resistance cannot be obtained. On the other hand, if it exceeds 1.20, problems such as meandering and cracking of the sheet during rolling occur, and a good sheet cannot be obtained.
[0013]
Here, the linear velocity refers to the linear velocity of the outer peripheral surface of the rolling roller.
[0014]
Further, by setting the total rolling ratio of the sheet formed by the multi-stage rolling roll press step to 70% or more and 95% or less, the effect of changing the linear velocity of a pair of rolls facing each other is obtained. It was found that the strength and corrosion resistance of the grating produced by the processing method were more excellent. In this case, when the rolling ratio is increased, the strength of the rolled sheet is increased, but the structure becomes too fine and easily corroded. On the other hand, when the rolling ratio is lower than 70%, the strength of the sheet decreases. Therefore, by rolling at a rolling ratio of 70% or more and 95% or less, the crystal can be kept relatively large, so that the corrosion resistance is superior to that of a normal rolled sheet having a fine crystal structure, and the strength is at a certain level. It has been found that the shear stress is applied to the sheet by passing the pair of rolls having different linear velocities through different rolls, thereby further improving the corrosion resistance.
[0015]
Here, the rolling ratio (%) is represented by (slab thickness before rolling−sheet thickness after rolling) / slab thickness before rolling × 100.
[0016]
According to a second aspect of the present invention, there is provided a storage battery including a storage battery grid manufactured by the manufacturing method according to the first aspect.
[0017]
By using the grid manufactured by the method of the first aspect, a storage battery having excellent corrosion resistance, high strength of the grid, and a suppressed deterioration rate of the positive grid is obtained.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention resides in a method of obtaining a rolled sheet from a slab by a multi-stage roll press, wherein the sheet is rolled by changing a linear velocity of at least a pair of opposed rolls of the multi-stage roll press. The lattice produced by machining the sheet obtained in this way is excellent in corrosion resistance while maintaining mechanical strength, so that a storage battery using the lattice can have excellent life characteristics. Hereinafter, an embodiment will be described in detail.
[0019]
【Example】
FIG. 1 is a main part side view showing an example of a set of roll presses having different linear velocities of upper and lower rolls of the present invention, where 1a is an upper roll, 1b is a lower roll, and 21 is rolled on the roll. A sheet before 22 and a sheet after rolling are shown, respectively.
[0020]
An example will be described below in order to clarify that by passing the sheet through the roll shown in FIG. 1, the corrosion resistance is significantly improved while maintaining the strength as the sheet.
[0021]
When a slab of about 10 mm made of a Pb-0.06% Ca-1.3% Sn alloy is rolled by a normal eight-stage continuous rolling mill, the linear velocity ratio of a pair of opposing rolls in the third stage Was varied up and down from 1.0 to 1.25. Here the linear speed ratio, the defined at a linear velocity V _{f /} slow roll linear velocity V _s of fast rolls. The average value of the linear velocities of the upper and lower rolls was adjusted so as to be the same as the linear velocities when the linear velocities of the upper and lower rolls were the same so that sagging and breakage did not occur during rolling.
[0022]
On the other hand, the slab thickness and the number of roll stages were adjusted so that the final thickness of the rolled sheet was the same, and the total rolling reduction was changed from 50% to 97%.
[0023]
The rolled sheet produced by combining these two conditions was machined by a conventional rotary expander to produce a lattice. These lattices were filled with paste obtained by plastering a raw material mainly composed of lead oxide with dilute sulfuric acid, aging and drying to prepare an unformed positive electrode plate. By combining this positive electrode plate with a negative electrode plate produced by a conventional method and a separator mainly composed of microporous polyethylene, a 55D23 type lead-acid battery for automobiles specified in JIS D 5301 was produced. A predetermined specific gravity and a predetermined amount of dilute sulfuric acid were injected into the storage battery to form a chemical, thereby completing the storage battery.
[0024]
These batteries were subjected to a light load life test at a test temperature of 75 ° C. according to JID D 5301. The life test was completed after 3,000 cycles, the storage battery was disassembled, and the maximum elongation of the positive electrode plate was examined.
[0025]
FIG. 2 shows the relationship between the linear velocity ratio and the total rolling reduction (%) and the maximum elongation (%) of the positive electrode plate after the life test. In addition, the elongation rate (%) of the positive electrode lattice was represented by a ratio when the elongation rate of a positive electrode plate having a total rolling reduction of 97% and a linear velocity ratio of 1.0 was set to 100%.
[0026]
As shown in FIG. 2, when the linear velocity ratio between the upper and lower rolls was changed in the range of 1.025 or more and 1.2 or less, the elongation of the positive electrode plate during the life test could be suppressed. In particular, the effect was found to be large near 1.1. Further, the effect was more remarkable when the total rolling ratio was in the range of 70% or more and 95% or less. This is because the effect on the change in the microstructure of the rolled sheet by changing the linear velocity of the roll and the effect on the strength of the sheet by changing the total rolling ratio act synergistically, and good results were obtained. Conceivable.
[0027]
However, if the linear velocity ratio exceeds 1.2, problems such as meandering and cracking of the sheet occur, and a rolled sheet in a final state cannot be obtained, and an expanded lattice cannot be produced. On the other hand, when the linear velocity ratio was smaller than 1.025, the effect of changing the velocity ratio was not sufficient, and the improvement in corrosion resistance was slight.
[0028]
On the other hand, when the total rolling ratio exceeded 95%, the entire sheet had a uniform and fine structure, so that the corrosion resistance was poor and the elongation of the positive electrode plate was large. On the other hand, when the total rolling reduction was lower than 70%, since the cast structure remained, elongation of the positive electrode plate due to intergranular corrosion was observed.
[0029]
In this example, a rolled sheet was prepared using a slab of about 10 mm made of a Pb-0.06% Ca-1.3% Sn alloy, but the content of calcium was 0.04% by mass or more and 0.09% by mass. The inventor of the present application has found that the same effect can be obtained for a rolled sheet produced using a slab having a range of not more than 1.0% by mass and a tin content of not less than 1.0% by mass and not more than 2.4% by mass. I have confirmed. Also, the alloy type is not limited to Pb-Ca-Sn, and similar effects can be obtained with other lead alloys, for example, Pb-Sn-based alloys or Pb-Sb-based alloys.
[0030]
Further, in the present embodiment, the lead storage battery is described. However, a storage battery of a system in which a metal slab is rolled to form a continuous sheet, and the sheet is formed into a group of electrode plates using a grid formed by a machining method. It goes without saying that the present invention can be applied without being limited to lead-acid batteries.
[0031]
In the embodiment, the linear speed of the rolls was controlled individually, but the rolling speed was adjusted differently between upper and lower rolls. The effect is obtained.
[0032]
Furthermore, the inventor of the present application has confirmed that this effect is not significantly affected even in the rolling temperature range of 0 ° C to 300 ° C.
[0033]
If the rolling rate per operation exceeds 50%, the friction on the front and back of the sheet becomes too large, and there is a possibility that the sheet is broken. Therefore, it is preferable to perform the operation at a rolling rate of 50% or less per operation.
[0034]
【The invention's effect】
As described in detail above, in the method of producing a sheet by rolling a slab with a multi-stage roll press and manufacturing the lattice by a mechanical processing method such as expanding, a fine structure is formed on the sheet by rolling. Therefore, it has a problem that it is easily corroded and has a short life. On the other hand, according to the present invention, in the multi-stage roll press machine, by changing the linear speed of at least one pair of opposed rolls to perform rolling, a shear stress is applied to the slab or the sheet, so that the vicinity of the sheet surface is provided. In this method, crystal grains uniform in the rolling direction are generated, but crystal grain boundaries having a misaligned orientation are generated therein, and the total rolling ratio of the sheet is set to 70% or more and 95% or less. As a result, the strength of the sheet is maintained, so that a grid having high mechanical strength and excellent corrosion resistance can be obtained, and a storage battery using the grid has excellent life characteristics and its industrial effect is extremely large.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a principal part showing a pair of rolling roll presses having different linear velocities in upper and lower portions.
FIG. 2 is a diagram showing a relationship between a linear velocity ratio and a total rolling reduction and an elongation (%) of a positive electrode plate after a light load life test.
1a Upper roll 1b Lower roll 21 Sheet before processing 22 Sheet after processing

Claims (2)

Rolling the slab stepwise into a continuous sheet by a multi-stage rolling press, in the method of manufacturing a grid for a storage battery, wherein the grid is formed by machining the sheet.
A method of manufacturing a grid for a storage battery, wherein linear speeds of at least one pair of opposed rolls of the multi-high rolling roll press are different. A storage battery comprising a storage battery grid manufactured by the manufacturing method according to claim 1.

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