JP4852869B2 - Method for producing electrode plate current collector for lead acid battery - Google Patents

Description

  The present invention relates to a method for producing a lead sheet used for producing a grid-like current collector of an electrode plate of a lead storage battery by an expanding method, and a multi-stage rolling of a lead sheet of a slab cast body made of lead or a lead alloy The present invention relates to a method for producing a current collector for a lead storage battery that is rolled in stages by a roll.

  The electrode plate of the lead-acid battery is obtained by filling an active material into the grid of a grid-shaped current collector made of lead or a lead alloy. In addition to directly forming lead or a lead alloy in a lattice shape by casting, this current collector is produced by developing a lead sheet made of lead or a lead alloy in a lattice shape by an expanding method. In addition, in this expanding method, a reciprocating method that spreads out from each end of the lead sheet in order by the vertical movement of the die cutter, and a staggered slit formed in the lead sheet by rotating the disc cutter is extended from both sides. For example, there is a rotary system that expands to the grid. In recent years, current collectors are often produced by an expanding method that can improve productivity by continuously producing on a line.

  A continuous rolling method using a rolling roll is usually used for producing a lead sheet used for producing the current collector by the above expanding method. As a general method for producing a metal sheet, there are a continuous casting method, an extrusion method, a rolling method, and the like. Especially, continuous rolling by a rolling roll has high productivity, so that not only steel-related but also non-ferrous metals are used. This is because it is used in many fields.

  A method for producing a lead sheet by a continuous rolling method using a rolling roll will be described with reference to FIG. A cast lead sheet 1a of a slab cast body of lead or lead alloy produced by continuous casting is rolled with a predetermined sheet thickness by continuously passing between a pair of large-diameter rolling rolls 2 and 2 arranged in multiple stages. It is rolled into a lead sheet 1b. Here, the cast lead sheet 1a of the original slab cast body is productive by using a sheet thickness that is 10 times or more that of the rolled lead sheet 1b having a predetermined sheet thickness as a material of the current collector. It is common to increase.

  Conventionally, the rolling reduction of the large-diameter rolling rolls 2 and 2 at each stage is made constant so that the speed adjustment before and after rolling can be easily performed and the balance between stress and heat generation is not easily lost. The rolling reduction ratio of each stage is (d1 − when the sheet thickness of the lead sheet 1 immediately before rolling by the large-diameter rolling rolls 2 and 2 of the stage is d1, and the sheet thickness of the lead sheet 1 immediately after rolling is d2. d2) × 100 / d1. In addition, the large-diameter rolling rolls 2 and 2 of each stage use rolling rolls having a diameter of 20 times or more the sheet thickness of the lead sheet 1 to be rolled, and are rolled at a relatively large reduction ratio of about 30%. I was going. This is because when rolling is performed using the large-diameter rolling rolls 2 and 2 having a large diameter, the crystal structure can be uniformly crushed by giving a substantially uniform strain in the thickness direction. As shown, the crystal structure of the rolled lead sheet 1b can be uniformly refined over the entire thickness direction. In FIG. 4, in order to make the drawing easier to see, the thickness of the lead sheet 1 is shown larger than the actual thickness compared to the diameters of the large-diameter rolling rolls 2 and 2.

  Here, since the current collector produced directly by the casting method has a large crystal structure, a large grain boundary is likely to be generated partially. Therefore, when a lead-acid battery using this current collector for the positive electrode plate is produced and used, the corrosion progresses locally along this large grain boundary, resulting in the breakage of the grid bars and the like. Is likely to occur. However, when the current collector is produced by the expanding method using the lead sheet having the crystal structure uniformly refined as described above, the crystal grain boundaries are also subdivided, so that large corrosion progresses locally. Things will disappear.

  In addition, by directly producing a thin slab cast with a sheet thickness and processing it into a lattice shape by rolling without rolling, the slab cast cannot withstand expansion processing because the crystal structure is large and brittle. There is a risk that the lattice bars will break. However, when a lead sheet whose crystal structure is uniformly refined by the rolling process as described above is used, the strength is improved by the processing strain caused by the rolling, so that it can sufficiently withstand the expansion processing by the expanding method. It becomes like this.

  However, current collectors made using a lead sheet with an evenly refined crystal structure in this way gradually corrode at the grain boundaries that are subdivided as a whole. The amount increases. Moreover, since a lead sheet that has been rolled to a thickness of 1/10 or less of the original slab cast is used, the crystal structure becomes too fine, and the aging at high temperatures and high temperatures has progressed too early. In many cases, aging was reached and the strength decreased. Therefore, in the conventional method of manufacturing an electrode plate current collector for a lead-acid battery using an expanded method, the lattice shape of the current collector is deformed, causing the active material to fall off the electrode plate or causing a short circuit with the counter electrode plate. There was a problem of shortening. That is, this current collector is gradually oxidized from the surface side due to corrosion and changed into lead dioxide having a large volume due to corrosion, so that the current collector itself does not only expand but also the length of the crosspiece. Tensile stress is also applied in the vertical direction. In addition, since the strength decreases due to overaging due to the refinement of the crystal structure, if the corrosion of the current collector progresses to some extent with the use of lead acid batteries, the lattice shape can be maintained against the elongation of the crosspieces. As a result, the grid expands, and the current collector itself expands or undergoes deformation such as warping. Therefore, the active material filled in the grids of the current collector lattice is peeled off and drops, or the electrode plate expands or curves to contact the counter electrode plate or the strap of the counter electrode plate to cause a short circuit.

  In the present invention, by rolling the rolling sheet at a small reduction rate in the initial stage of continuous rolling of the lead sheet to refine only the crystal structure of the surface layer portion, the strength of the deep layer portion is maintained in a high state and the lattice shape is deformed. It is an object of the present invention to provide a method for manufacturing a current collector for a lead-acid battery capable of preventing the occurrence of a long life.

  The invention according to claim 1 is a first step of rolling a lead sheet of a slab cast body made of lead or a lead alloy stepwise with a multi-stage rolling roll to obtain a single rolled sheet, and processing the rolled sheet In the manufacturing method of the electrode plate current collector for a lead storage battery, comprising the second step, the lead sheet has a calcium (Ca) content of 0.04 mass% or more, 0.09 mass% or less, tin ( The content of Sn) is 0.5 mass% or more and 2.4 mass% or less, and the crystal structure of the portion corresponding to the surface layer portion of the rolled sheet is finer than the crystal structure of the portion corresponding to the deep layer portion of the rolled sheet. Yes, the first step repeats rolling at a small reduction rate, and the reduction start sheet thickness, which is the sheet thickness of the lead sheet 1 when starting the first step, is the original cast lead sheet 1a. 80% or more of the sheet thickness of lead It includes four or more rolling processes in which a rolled sheet is rolled at a rolling reduction of 3% or less by a set of rolling rolls until the rolled sheet is rolled to a thickness of 50% with respect to the sheet thickness of the original slab cast body. It is characterized by.

  The method for producing a current collector for a lead-acid battery according to claim 2 is characterized in that the diameter φ of a set of rolling rolls used in a rolling process rolled at a rolling reduction of 3% or less is that of the lead sheet immediately before the rolling. The sheet thickness d is in the range of 0.5d ≦ φ ≦ 5d.

According to the first aspect of the present invention, in a rolled sheet in which the crystal structure of the deep layer portion is not refined as much as the surface layer portion, strength reduction due to overaging in the deep layer portion hardly occurs. Therefore, when this rolled sheet is processed into a grid-like current collector by the expand method and used as a lead storage battery, corrosion from the surface layer portion of the current collector proceeds, but the strength of the deep layer portion is maintained high. Therefore, it is possible to prevent the grid bars or the like from expanding in the length direction or the like due to this corrosion, and it is possible to prevent the current collector from being deformed.
Furthermore, since the slab cast body undergoes rolling with a small reduction ratio of 3% or less over two or more stages in the initial stage of continuous rolling, the strain due to rolling is concentrated on the surface layer compared to a normal reduction ratio of around 30%. As a result, the crushing of crystals in the surface layer portion becomes larger than that in the deep layer portion, and the crystal structure becomes finer. Moreover, if rolling is performed in advance with this small reduction ratio, the crystal structure of the surface layer portion and the deep layer portion will not be uniform even if rolling is performed with the conventional large reduction ratio, and the crystals have already been crushed. The refinement of the crystal structure of the surface layer portion that has become larger is further promoted than in the deep layer portion. And the lead sheet | seat in which the crystal structure of a deep layer part is not refined | miniaturized like a surface layer part becomes difficult to produce the strength fall by the overaging in this deep layer part. Therefore, when this lead sheet is processed into a grid-like current collector by the expand method and used as a lead storage battery, corrosion from the surface layer portion of this current collector proceeds, but the strength of the deep layer portion is maintained high. Therefore, it is possible to prevent the grid bars or the like from expanding in the length direction or the like due to this corrosion, and it is possible to prevent the current collector from being deformed.

  According to the invention of claim 2, since rolling is performed using a roll having a sufficiently small diameter with respect to the sheet thickness immediately before rolling of the lead sheet, if the rolling ratio is the same, the roll is locally compared with a roll having a large diameter. So that the strain can be further concentrated only on the surface layer portion rather than the deep layer portion, and the difference in the degree of refinement of the crystal structure of the deep layer portion and the surface layer portion can be increased. Become.

  Hereinafter, the best embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, in the method of manufacturing a lead-acid battery electrode current collector of this embodiment, a cast lead sheet 1 a of a slab cast body of lead or lead alloy produced by continuous casting is first arranged over 10 stages. Rolling having a predetermined sheet thickness by continuously passing between a pair of small diameter rolling rolls 3 and 3 and then continuously passing between a pair of large diameter rolling rolls 2 and 2 arranged in multiple stages. The lead sheet 1b is obtained.

  The large-diameter rolling rolls 2 and 2 are rolling rolls similar to the conventional example, and are large-diameter rolling rolls whose diameter is 20 times or more the sheet thickness of the lead sheet 1 immediately before rolling in the corresponding stage. Also, the large-diameter rolling rolls 2 and 2 in each stage are set to a comparatively large reduction ratio of about 30% as in the conventional example, and the total including the reduction ratio by the 10-stage small-diameter rolling rolls 3 and 3 is also included. The number of stages is set such that the rolling reduction is the same as in the conventional example. In addition, it is preferable to set the rolling reduction of the large diameter rolling rolls 2 and 2 at each stage to a constant value for speed adjustment before and after rolling, as in the conventional example. Further, in FIG. 1, in order to make the drawing easy to see, the thickness of the lead sheet 1 is shown larger than the actual diameter compared to the diameters of the large diameter rolling rolls 2, 2 and the small diameter rolling rolls 3, 3. The ratio of diameter to thickness is not accurately represented.

  The small-diameter rolling rolls 3 and 3 are small-diameter rolling rolls having a diameter φ in the range of 0.5d ≦ φ ≦ 5d with respect to the sheet thickness d of the lead sheet 1 immediately before rolling in the corresponding stage. That is, the diameter φ of the first stage small-diameter rolling rolls 3 and 3 is in the range of 0.5d ≦ φ ≦ 5d with respect to the sheet thickness d of the cast lead sheet 1a of the slab cast body, and the second stage The diameter φ of the small diameter rolling rolls 3 and 3 is in the range of 0.5d ≦ φ ≦ 5d with respect to the sheet thickness d of the rolled lead sheet 1b rolled by the first stage small diameter rolling rolls 3 and 3. . And the diameter (phi) of the small diameter rolling rolls 3 and 3 of each step | paragraph may use a little different diameter so that all may be set to 2d, for example. However, in this embodiment, the diameter φ of the ten stages of the small diameter rolling rolls 3 and 3 is made common, and the ratio of the diameter φ to the sheet thickness d of the lead sheet 1 immediately before rolling changes within this range. I am doing so.

  The 10-stage small-diameter rolling rolls 3 and 3 have a reduction ratio of 3% or less by the reduction ratio of the small-diameter rolling rolls 3 and 3 in each stage. At this time, the rolling reduction by the small-diameter rolling rolls 3 and 3 at each stage is preferably a constant value of 3% or less for speed adjustment before and after rolling. Therefore, for example, when the reduction ratios by the small-diameter rolling rolls 3 and 3 at each stage are all 3%, the total reduction ratio by the 10-stage rolling process is about 26.3% (= 1− (1−0.03). ) 10). In the following, for the sake of simplicity, it is assumed that the total rolling reduction at 10 stages is 30% (= 3% × 10) when the rolling reduction at each stage is 3%.

  In addition, in this embodiment, the rolling process by the small diameter rolling rolls 3 and 3 was 10 stages, but if it is 2 stages or more, it will not be limited to this stage number. However, the sheet thickness of the rolled lead sheet 1b after two or more stages of rolling by the small-diameter rolling rolls 3 and 3 is less than 50% with respect to the sheet thickness of the cast lead sheet 1a of the original slab casting. must not. Therefore, in this embodiment, since rolling by the small diameter rolling rolls 3 and 3 is started from the beginning of the original cast lead sheet 1a (sheet thickness is 100%), for example, all the reduction ratios of these small diameter rolling rolls 3 and 3 are set. If it is 3%, the number of stages is limited to 16 (total reduction ratio is 48%), and cannot be 17 stages (total reduction ratio is 51%) or more. However, since the actual total rolling reduction is a little smaller, it is explained that the number of stages is limited to be less than the actual number.

  Moreover, in this embodiment, although the rolling process by the small diameter rolling rolls 3 and 3 was started from the beginning of the original cast lead sheet 1a (sheet thickness is 100%), after rolling by the small diameter rolling rolls 3 and 3 was performed. If the sheet thickness of the rolled lead sheet 1b is 50% or more with respect to the sheet thickness of the original cast lead sheet 1a, rolling with another rolling roll may be performed first. For example, assuming that the total rolling reduction by the 10-stage small-diameter rolling rolls 3 and 3 is 30%, after performing the rolling at the rolling reduction of 20% by the large-diameter rolling rolls 2 and 2 first, these 10-stage small-diameter rolling rolls. You may make it perform rolling by 3 and 3. This is because the total rolling reduction so far is 50%. In addition, since the actual total rolling reduction should just be 50% or less, the rolling reduction by the above large diameter rolling rolls 2 and 2 may be a little larger.

  Here, for example, if the reduction ratio by the small diameter rolling rolls 3 and 3 is 3%, the total reduction ratio of the 10-stage small diameter rolling rolls 3 and 3 is 30%, and then the large diameter rolling roll 2 having a reduction ratio of 30%. When 2 is arranged in two stages, the total rolling reduction in the entire rolling process is 90%, and a rolled lead sheet 1b having a thickness of 10% of the sheet thickness of the original cast lead sheet 1a can be obtained. Moreover, what is necessary is just to increase the number of steps of the large diameter rolling rolls 2 and 2 or to adjust a reduction rate, when reducing the reduction rate by the small diameter rolling rolls 3 and 3 or reducing the number of steps. In addition, the reduction rate by the small diameter rolling rolls 3 and 3 and the reduction rate by the large diameter rolling rolls 2 and 2 are different. However, if the reduction ratio of each small-diameter rolling roll 3, 3 is set to a constant value and the reduction ratio of each large-diameter rolling roll 2, 2 is also set to a constant value, the reduction ratio is different only during these rolling steps. Therefore, speed adjustment and the like are relatively easy and do not become a major obstacle.

  According to the manufacturing method of the above embodiment, the cast lead sheet 1a of the slab cast body undergoes rolling at a small reduction rate by the small diameter rolling rolls 3 and 3 in two or more stages at the initial stage of continuous rolling. In rolling by such a small rolling reduction, the processing strain concentrates only on the surface layer portion of the rolled lead sheet 1b, and the crushing of crystals in the surface layer portion becomes larger than that in the deep layer portion, and the crystal structure is also refined. Further, since the small diameter rolling rolls 3 and 3 are sufficiently small diameter rolling rolls with respect to the sheet thickness of the lead sheet 1, the lead sheet 1 is locally applied as compared with the large diameter rolling roll if the rolling reduction is the same. Therefore, the processing strain can be further concentrated only on the surface layer portion. In addition, when rolling at a small reduction rate in advance is performed in this way, only the crystals of the surface layer portion are crushed and the crystal structure is refined. The refinement of the crystal structure by rolling is promoted in the surface layer part rather than in the deep layer part, and the crystal structure of the surface layer part and the deep layer part is not made uniform. Therefore, the rolled lead sheet 1b continuously rolled by the small diameter rolling rolls 3 and 3 and the large diameter rolling rolls 2 and 2 has a nonuniform crystal structure along the thickness direction as shown in FIG. In S, the crystal structure is extremely refined, but the crystal structure of the deep layer portion D is gradually refined.

  If the processing strain is concentrated only on the surface layer portion of the rolled lead sheet 1b by rolling with the small rolling reduction of the small diameter rolling rolls 3 and 3, only this surface portion is unbalanced in the width direction and the length direction regardless of the deep layer portion. There is a risk of stretching. Further, even if the rolled lead sheet 1b that has already been rolled at a large rolling reduction is rolled at a small rolling reduction by the small diameter rolling rolls 3 and 3, the processing strain cannot be sufficiently concentrated only on the surface layer portion. For this reason, the total rolling reduction by the small diameter rolling rolls 3 and 3 is an initial stage of the continuous rolling process and is limited to 50% at the maximum.

  Since the processing strain is given nonuniformly as described above, the degree of refinement differs between the crystal structure of the surface layer portion and the deep layer portion, but this rolled lead sheet 1b is expanded by the expand method as in the conventional product. Etc. can be sufficiently tolerated. However, in this way, in the deep layer portion where the degree of miniaturization is moderate with respect to the surface layer portion, it is difficult for the strength to decrease due to overaging compared to the surface layer portion, so that high strength can be maintained over a long period of time. Therefore, by processing the current collector and using it as a lead storage battery, even if the corrosion of the current collector progresses and the grid bars etc. expand in the length direction etc., this expansion is caused by the high strength of the deep layer. This prevents the current collector from being deformed. By preventing the current collector from being deformed, the active material is prevented from falling off the electrode plate, and a short circuit with the counter electrode plate is prevented, thereby extending the life of the battery.

  In the above embodiment, the case where the small-diameter rolling rolls 3 and 3 are arranged in multiple stages along the rolling direction in the same manner as the large-diameter rolling rolls 2 and 2 is shown. However, as shown in FIG. The rolling may be performed as a planetary mill 4 that is arranged on the circumference of a roll and continuously performs multi-stage rolling at a high speed. However, the planetary mill 4 is usually used by setting the total reduction ratio of one pass to an extremely large value such as 95 to 99%, but here, the reduction ratio by each small diameter rolling roll 3 is 3% or less. It is necessary to set so that the reduction ratio is small.

  Hereinafter, examples will be described in detail while comparing with conventional examples and reference examples.

  In all of these conventional examples, examples and reference examples, a cast lead sheet 1a having a thickness of 10 mm made of a Pb-0.06 mass% Ca-1.3 mass% Sn alloy is used as a slab cast before rolling. did. In addition, the rolled lead sheet 1b rolled to a predetermined sheet thickness by continuous rolling was processed into a grid-like current collector by a rotary method, and the ratio at which breakage occurred during development was examined. Furthermore, the current collector produced in this way was filled with active material, aged and dried to form a positive electrode plate, and this positive electrode plate was a separator mainly composed of a negative electrode plate produced by a conventional method and microporous polyethylene. The lead acid battery (55D23 type) for automobiles was manufactured by injecting a predetermined specific gravity and a predetermined amount of dilute sulfuric acid and performing chemical conversion. Then, using these lead storage batteries, a corrosion (cycle) test at a high temperature (JIS light load life test) was performed, and the maximum elongation of the electrode plate at the end of 3000 cycles was investigated.

[Comparative Example 1]
The manufacturing method of the rolled lead sheet 1b by continuous rolling using only the large-diameter rolling rolls 2 and 2 and the rolling reduction of each stage as 30% is assumed to be a conventional example 1, and the rolling process with a rolling reduction of 30% in the first stage is performed. Examples 1 to 3 and Reference Examples 1 to 2 were changed to a multi-stage rolling process with a rolling reduction of 1 to 10% using the small diameter rolling rolls 3 and 3 (the total rolling reduction was 30% for all). Table 1 shows the results of the investigation of the breaking rate at the time of development and the electrode plate elongation after the corrosion test.

  According to Table 1, in the case of Examples 1 to 3 where the rolling reduction is 1 to 3%, the plate elongation after the corrosion test is 63 to 68 compared to the conventional example 1 of 100. It became a small ratio, and it was confirmed that the elongation of the electrode plate can be sufficiently prevented. However, in Reference Examples 1 and 2 with a rolling reduction of 5 to 10%, the electrode plate elongation after the corrosion test was 90 to 97, which was not significantly different from the conventional example. As a result, it was found that the small rolling reduction needs to be 3% or less.

  In addition, about the fracture | rupture rate at the time of expansion | deployment, in the case of not only Examples 1-3 but Reference Examples 1-2, it becomes a ratio of 100-102 with respect to the case where the prior art example 1 is set to 100. It was confirmed that it could withstand the unfolding process without much difference. In addition, the term “thickness of starting sheet” indicates that the sheet thickness of the lead sheet 1 at the time of starting the process of repeating rolling at a small reduction rate shown in the section of “reducing rate × number of steps” is the original cast lead sheet 1a. The percentage of the sheet thickness is shown in Table 1. In Table 1, since all the percentages are 100%, a small reduction is started from the first stage for this cast lead sheet 1a. It represents that.

[Comparative Example 2]
In Example 3 above, a case where a rolling process with a small reduction ratio of 3% × 10 stages was started from the first stage of continuous rolling was shown, but the original cast lead sheet 1a was first increased to 90 to 40% with a large diameter. After rolling with the rolling rolls 2 and 2 as much as possible and a small number of stages, the manufacturing method which started the rolling process by this 3% x 10 stage small rolling reduction was made into Examples 4-5 and Reference Examples 3-6, Table 2 shows the results of investigation of the breaking rate at the time of development and the electrode plate elongation after the corrosion test. Table 2 also shows the conventional example 1 and the above-described example 3 that serve as a basis for the breaking rate during deployment and the electrode plate elongation after the corrosion test.

  According to Table 2, in the case of Examples 3 to 5 where the rolling start sheet thickness is 100 to 80%, the electrode plate elongation after the corrosion test is 65 to It was confirmed that it was possible to sufficiently prevent the elongation of the electrode plate. However, in Reference Examples 3 to 6 in which the rolling start sheet thickness was 70 to 40%, the electrode plate elongation after the corrosion test was 130 to 160, which was worse than the conventional example. As a result, it was found that the reduction start sheet thickness needs to be 80% or more. That is, in Examples 3 to 5 and Reference Examples 3 to 6, since the small reduction ratio 3% is 10 stages and the total reduction ratio is 30%, the rolled lead sheet 1b after the rolling process of this small reduction ratio is: The sheet thickness needs to be 50% (= 80% -30%) or more with respect to the original cast lead sheet 1a. Moreover, since the electrode plate elongation after the corrosion test of Examples 3 to 5 becomes a smaller ratio as the rolling start sheet thickness is closer to 100%, the rolling process of this small rolling reduction is as early as possible in continuous rolling, It was also found that it is preferable to carry out from the first stage if possible.

  In addition, about the fracture | rupture rate at the time of expansion | deployment, in the case of not only Examples 3-5 but Reference Examples 3-6, it becomes a ratio of 98-102 with respect to the case where Conventional Example 1 is set to 100. It was confirmed that it could withstand the unfolding process without much difference.

[Comparative Example 3]
A manufacturing method in which a rolling process with a small reduction rate of 2% by the small-diameter rolling rolls 3 and 3 from the first stage of continuous rolling is performed over 1 to 32 stages is referred to as Reference Examples 7 to 9 and Examples 6 to 11, and these are developed. Table 3 shows the investigation results of the breaking rate at the time and the electrode plate elongation after the corrosion test. In addition, after the rolling process by these small reduction ratios, rolling was performed with the large diameter rolling rolls 2 and 2 with a maximum reduction ratio and as few stages as possible to obtain a rolled lead sheet 1b having a predetermined sheet thickness. Table 3 also shows the conventional example 1 as a reference for the breaking rate at the time of deployment and the electrode plate elongation after the corrosion test.

  In Reference Example 7 in Table 3, the number of steps in the rolling process with a small reduction rate was only one and the reduction rate was only 2%, so that only a result that was not different from Conventional Example 1 was obtained. On the other hand, in the case of Examples 6 to 11 in which the number of steps in the rolling process with a small reduction ratio is 4 to 24, that is, the total reduction ratio is 8 to 48%, the electrode plate elongation after the corrosion test is the conventional example. When 1 was set to 100, it was a small ratio of 65 to 85, and it was confirmed that elongation of this electrode plate could be sufficiently prevented. However, in the case of Reference Examples 8 to 9 in which the number of steps in the rolling process with a small reduction ratio is 28 to 32, that is, the total reduction ratio is 56 to 64%, the electrode plate elongation after the corrosion test is a ratio of 95 to 109. Thus, it was not much different from the conventional example or worsened. As a result, it was found that the number of stages in the rolling process with a small reduction ratio is insufficient with one stage, and the total reduction ratio needs to be 50% or less.

  In addition, about the fracture | rupture rate at the time of expansion | deployment, not only in Examples 6-11, but in the case of Reference Examples 7-9, it was confirmed that there was no big difference with the prior art example 1, and it can fully endure the expansion | deployment process.

[Comparative Example 4]
The ratio of the diameter of the rolling roll to the sheet thickness of the lead sheet 1 immediately before rolling is 30 to 15, and only the large-diameter rolling rolls 2 and 2 are used. The production method is conventional examples 2 to 3, and the first stage of the rolling process with a rolling reduction ratio of 30% is a rolling reduction ratio of 3% using small diameter rolling rolls 3 and 3 having a diameter to sheet thickness ratio of 10 to 0.2. X 10-stage rolling process (total rolling reduction is 30% for all) The production method changed to Reference Examples 10 to 11 and Examples 12 to 15 and the breaking rate at the time of development and the electrode plate elongation after the corrosion test Table 4 shows the results of the survey.

  According to Table 4, in the case of Examples 12 to 15 in which the ratio of the diameter to the sheet thickness is 5 to 0.5, the electrode plate elongation after the corrosion test is 100 times that of the conventional example 2. Thus, a small ratio of 62 to 70 was confirmed, and it was confirmed that the elongation of the electrode plate could be sufficiently prevented. However, in the case of Reference Example 10 in which the ratio of the diameter to the sheet thickness is 10 or in Reference Example 11 in which the ratio of the diameter to the sheet thickness is 0.2, the electrode plate elongation after the corrosion test is 97 to 97%. The ratio was 98, which was not significantly different from the conventional example. As a result, it was found that the diameters of the small-diameter rolling rolls 3 and 3 need to be within a range of 0.5 to 5 with respect to the sheet thickness of the lead sheet 1 immediately before rolling.

  In addition, about the fracture | rupture rate at the time of expansion | deployment, in the case of not only Examples 12-15 but the case of Reference Examples 10-11 or the prior art example 3, when the prior art example 2 is set to 100, it is 95-101. Thus, it was confirmed that it could withstand the unfolding process without much difference from the conventional one.

[Comparative Example 5]
In this example, a slab casting made of a Pb-0.06 mass% Ca-1.3 mass% Sn alloy was used, but the calcium (Ca) content was 0.04 mass% or more, 0.09 mass%. The same effects as described above were obtained even when a slab cast body having a mass% or less range and a tin (Sn) content of 0.5 mass% or more and 2.4 mass% or less was used.

  Moreover, if the thickness of the cast lead sheet 1a of this slab cast body is also in the range of 4 mm or more and 15 mm or less, the effect of the present invention was confirmed.

  Furthermore, even when the planetary mill 4 shown in FIG. 3 was used, the effect of the present invention could be confirmed.

1 is a side view showing a rolling process of a lead sheet by a continuous rolling method using a small diameter rolling roll and a large diameter rolling roll according to an embodiment of the present invention. 1 is a partial enlarged cross-sectional front view of a continuously rolled lead sheet according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing a rolling process of a lead sheet by a continuous rolling method using a planetary mill and a large diameter rolling roll, showing an embodiment of the present invention. It is a side view which shows a prior art example and shows the rolling process of the lead sheet by the continuous rolling system using only a large diameter rolling roll. It is a partial expanded sectional front view of the lead sheet which showed the prior art example and was rolled continuously.

1 Lead Sheet 2 Large Diameter Roll 3 Small Diameter Roll 4 Planetary Mill

Claims (2)

A first step of obtaining a single rolled sheet by rolling a lead sheet of a slab cast body made of lead or a lead alloy stepwise with a multi-stage rolling roll, and a second step of processing the rolled sheet In the method for producing a lead-acid battery current collector, the lead sheet has a calcium (Ca) content of 0.04% by mass or more and 0.09% by mass or less, and a tin (Sn) content of 0. The crystal structure of the portion corresponding to the surface layer portion of the rolled sheet is finer than the crystal structure of the portion corresponding to the deep layer portion of the rolled sheet, and the first step Is to repeat rolling at a small rolling reduction, and the rolling start sheet thickness, which is the sheet thickness of the lead sheet 1 when starting the first step, is 80% of the sheet thickness of the original cast lead sheet 1a. %, The lead rolled sheet is Lead comprising at least four stages of rolling processes that are rolled at a rolling reduction of 3% or less by a set of rolling rolls until being rolled to a thickness of 50% with respect to the sheet thickness of the cast body A method for producing an electrode plate current collector for a storage battery. The diameter φ of a set of rolling rolls used in a rolling process that is rolled at a rolling reduction of 3% or less is based on the sheet thickness d of the lead sheet immediately before the rolling.
  0.5d ≦ φ ≦ 5d
2. The method for producing an electrode plate current collector for a lead storage battery according to claim 1, wherein the current collector is within the above range.