JP2003297367A - Storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a storage battery with its lifetime performance enhanced by changing the length of four lattice bars 1b surrounding each mesh 1c of an expand lattice formed on the rotary system so as to make uniform the corrosion. <P>SOLUTION: The storage battery whose electrode plate consists of the expand lattice structured so that a metal sheet 1 is furnished with a number of slits in zigzagged form and elongated in the width direction so as to spread the slits into meshes 1c, and thereby the four lattice bars 1b surrounding each mesh 1c are tied together to accomplish a meshing form, wherein the two opposing ones of the four bars 1b have approximately the same length, and the length of the other bars 1b should be between 102% and 120% of the length of the first named bars 1b. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage battery using an expanded grid made by a rotary method as an electrode plate. 2. Description of the Related Art In some cases, a grid used for an electrode plate of a lead storage battery or the like is manufactured by an expanding method. Also,
The method of manufacturing an expanded lattice by the expanding method is roughly classified into two types, a rotary type and a reciprocating type. [0003] The reciprocating expansion grid is manufactured by vertically moving a stepped die cutter on an intermittently moving metal sheet, cutting the metal sheet sequentially, and expanding the metal sheet in a mesh form. That is, as shown in FIG. 1, a metal sheet 1 made of lead, a lead alloy, or the like is intermittently transported on the flat upper surface of the lower base 2 in the direction of arrow F. On both side surfaces of the lower base 2, a plurality of stepped side surfaces 2a (only four steps are shown in the figure for simplicity) are formed from both sides in a stepwise manner with a constant step as the direction proceeds in the direction of arrow F. ing. Above the lower table 2, an upper table 4 to which a die cutter 3 is attached is arranged. The upper table 4 is actually disposed slightly below the figure, slightly above the metal sheet 1 conveyed on the lower table 2, and moves up and down. Stepped side surfaces 4a similar to the stepped side surfaces 2a of the lower stand 2 are formed on both side surfaces of the upper stand 4, respectively. Further, since the die cutter 3 is fixed to each of the stepped side surfaces 4a of the upper base 4, the die cutter 3 is arranged substantially in a V-shape as a whole. Each of these die cutters 3 has a cutting edge 3a projecting below the lower surface of the upper base 4. Each time the metal sheet 1 is stopped by the intermittent movement, the upper base 4 is lowered and moved up and down once, so that both ends are cut by the cutting edge 3a of each die cutter 3, and the metal sheet 1 is pushed downward. As a result, an expanded grating as shown in FIG. 2 is obtained. That is, the metal sheet 1 has a mesh-like shape in which the both sides of the current collecting frame 1a at the central portion in the width direction are sequentially pushed and spread as a grid bar 1b and connected in a net shape, and each is surrounded by four grid bars 1b. It is processed into an expanded grid having many grids 1c. Current collector 1a
Is a region where the grid 1c is not formed on the metal sheet 1 for current collection of the electrode plate, and an electrode plate ear for connection to a terminal is formed later. However, the expanded lattice shown in FIG. 2 is different from the expanded lattice shown in FIG. 1 and is manufactured by an apparatus in which twelve die cutters 3 are attached to both sides of the upper base 4. In the reciprocating manufacturing method, the operation until the die cutter 3 cuts the metal sheet 1 and pushes and expands the grid bar 1b to form the grid 1c is performed by one vertical movement of the upper base 4. To complete. Therefore, in this reciprocating manufacturing method, each grid 1c is substantially rhombic, and the lengths of the four grid bars 1b surrounding the grids 1c are equal to each other, so that each grid bar 1b can be expanded. The stress is applied evenly. However, in this reciprocating manufacturing method, it is also known that the shape of each square 1c is a substantially parallelogram having long sides and short sides different in length (for example, see Patent Document 1). In this reciprocating method, each grid bar 1b is pushed straight down by the cutting edge 3a of the die cutter 3, so that
When the grid bar 1b is unfolded, the grid bar 1b is not twisted, and therefore has an advantage of excellent life performance when used as an electrode plate of a storage battery. [0006] The expanding lattice, by Daisukatta 3 arranged in substantially V-shaped, for example, each grid 1c on diagonal line indicated by the one-dot chain line L ₁ is formed at a time. When the metal sheet 1 is conveyed a predetermined distance by intermittent movement and the next upper table 4 moves up and down, 1
Each square 1c on diagonal lines indicated by dash-dotted L ₂ are formed at one time. Therefore, in the metal sheet 1, the squares 1c at both ends in the width direction are formed first, and the inner squares 1c are sequentially formed every time the metal sheet 1 intermittently moves. In addition, the cutting edge 3a of each die cutter 3 pushes down two lattice bars 1b arranged substantially in a V shape below each square 1c, and each lattice bar 1b pushed down by the same die cutter 3 has the same row. As a result, they are alternately zigzag along the traveling direction F and are arranged in a line. As shown in FIG. 2, the expanded grid manufactured as described above has grid bars 1 on both sides of a current collecting portion 1a formed at the center of the metal sheet 1 in the width direction.
b is connected in a net shape. When the expanded grid is used as an electrode plate, the current collecting portion 1a is divided into two by a cutting line along the arrow F direction. Therefore, the expanded grid used as the electrode plate has a grid bar 1b connected to one side of the current collecting frame 1a in a net-like manner.
In the method for manufacturing the reciprocating expanded grid, the manufacturing speed is slightly reduced because the metal sheet 1 is conveyed by intermittent movement. [0008] The rotary expansion grid is
First, in the slit forming step, a large number of zigzag-shaped slits are formed on the metal sheet using a disk cutter, and then in the expanding step, the metal sheet is developed in the width direction, and each slit is expanded in a mesh shape. You. That is, in this rotary manufacturing method, first, in the slit forming step shown in FIG. 3, the metal sheet 1 is passed between the upper and lower disk cutter rolls 6 and 6 in which a number of disk cutters 5 are stacked. 1d is formed. As shown in FIG. 4, the disk cutter 5 is a metal disk in which a large number of peaks 5a and valleys 5b are alternately provided on the peripheral surface. Further, a groove 5c that opens to the valley 5b is formed at each of the valleys 5b in the peripheral edge of the front and back surfaces of the disk cutter 5. However, these grooves 5c
Is formed on only one of the front and back surfaces for each valley portion 5b, and the front and back surfaces of adjacent valley portions 5b are formed on different surfaces. As shown in FIG. 5, the disk cutter roll 6 is formed by laminating a large number of the disk cutters 5 coaxially with a spacer 7 interposed therebetween.
Are arranged such that the disk cutters 5 are displaced in the axial direction by a half pitch, and the upper and lower peripheral edges are staggered with each other. The upper and lower disk cutter rolls 6 and 6 are composed of upper and lower disk cutters 5 and 5 having peak portions 5a and 5a.
The valleys 5b, 5b and the valleys 5b rotate in opposite directions synchronously with a phase such that they overlap and mesh with each other. When the metal sheet 1 is passed between the disk cutter rolls 6, 6, a number of slits 1d are formed by the disk cutters 5, as shown in FIG. However, these slits 1d are provided in the valleys 5 of the upper and lower disk cutters 5, 5.
Since the grooves 5c, 5c of the b and 5b are interrupted at the portions facing each other, they are not continuous along the traveling direction F of the metal sheet 1 but are interrupted at regular intervals. Moreover, the slits 1d formed adjacent to the metal sheet 1 in the width direction are formed in a zigzag shape as a whole because the discontinuous portion is shifted by a half pitch in the traveling direction F. And the elongated metal linear portion between the adjacent slits 1d becomes the grid bar 1b,
The discontinuous portion of the slit 1d along the traveling direction F becomes the node 1e. The lattice bars 1b are pressed in the vertical direction when the slits 1d are formed by the ridges 5a of the upper and lower disk cutters 5, so that as shown in FIG. The sheet 1 is plastically deformed so as to protrude vertically from the front and back surfaces. Then, as shown in FIG. 6B, all of the series of lattice bars 1b arranged in the traveling direction F via the joints 1e are pressed upward by, for example, the crests 5a of the lower disk cutter 5, as shown in FIG. As a result, the central portion becomes an upward projection P, and all of the series of grid bars 1b adjacent to the metal sheet 1 in the width direction are pressed downward by the peaks 5a of the upper disk cutter 5. As a result, the central portion becomes a recess H downward. In the above-mentioned rotary type manufacturing method, the case where the slit 1d is formed through the metal sheet 1 between the two disk cutter rolls 6, 6 arranged vertically has been described. The slit 1d can be formed so that the metal sheet 1 is passed between the cutter rolls 6. The metal sheet 1 in which the slits 1d are formed as described above is expanded and spread on both sides in the width direction in the expanding step shown in FIG. 7 to form an expanded lattice. As shown in FIG. 8, an expanded grid generally manufactured by a rotary method has a current collecting portion 1 a provided at the center in the width direction of the metal sheet 1, and a lower forehead portion 1 f at each side end. , 1f, and a large number of mesh-like grids 1c are formed between them. The current collecting amount part 1a and the lower forehead part 1f
This is an area where the grid 1c is not formed in the metal sheet 1, and an electrode plate ear is later formed on the current collecting portion 1a in order to connect to a terminal and collect current. The lower forehead 1f is a lower end of the electrode plate when housed in the battery case. As shown in FIG. 7, the metal sheet 1 has a lower forehead 1 on both sides thereof.
The f and 1f are expanded by further expanding the f and 1f to both sides by the expansion devices 8 and 8, respectively. The unfolding device 8 is a chain device that is disposed on both sides of the transport path of the metal sheet 1 so as to be widened, and the lower forehead portion 1f of the metal sheet 1 transported by the locking portion attached to the chain roller. By being locked, it can be spread diagonally outward. Accordingly, the metal sheet 1 is pulled to both sides in the width direction, the gap between the slits 1d is widened to form a substantially diamond-shaped square 1c, and four grid bars 1b each having substantially the same length surrounding each square 1c. Are connected in a net-like manner to form an expanded lattice. Also, a series of adjacent slits 1d,
The grid bars 1b formed between the spaces 1d are in the same row, and are alternately inclined in a zigzag shape along the traveling direction F and are arranged in a row. When the expanded grating manufactured as described above is used as an electrode plate, the current collecting portion 1a at the center in the width direction is divided into two by a cutting line along the arrow F direction. Therefore, the expanded grid used as an electrode plate is
A grid bar 1b is connected to one side of the current collecting frame 1a in a net shape, and has a lower forehead 1f at this side end. Such a rotary type manufacturing method has an advantage that the speed of manufacturing an expanded grating is faster than that of a reciprocating type since the metal sheet 1 is continuously conveyed and slit formation and development are performed. . However, since each grid bar 1b of the metal sheet 1 is deformed so as to protrude in any of the upper and lower directions by the crests 5a of the disk cutter 5 in the slit forming step, and also forms the grid 1c in the expanding step. Therefore, unlike the case of the reciprocating type in which the cutting and deployment of the grid bar 1b are completed at one time, a strong stress due to the slit forming process and the developing process is received twice. Moreover, in the unfolding process, unlike the reciprocating type in which the lattice bars 1b are pushed downward only by the die cutter 3, these lattice bars 1b are expanded while being twisted through the knot portion 1e. Stress is also applied. For this reason, the expanded lattice produced by the rotary method is liable to crack or break in the lattice bar 1b during production,
There are also drawbacks such as poor yield and reduced life performance. [Patent Document 1] Japanese Patent Application Laid-Open No. 57-90873 [0017] However, the rotary manufacturing method has the advantage that the manufacturing speed of the expanded grating is high and the productivity is high. In spite of the above, strong tension is applied to only a part of the lattice bar 1b surrounding the substantially diamond-shaped square 1c at the time of deployment, so that the lattice bar 1b is likely to be corroded, and the life performance may be reduced. Problems had arisen. That is, as shown in FIG. 7, the metal sheet 1 is stretched from both sides as the metal sheet 1 is conveyed along the traveling direction F, as shown in FIG. , A strong tension E is applied to the lattice bar 1b + inclined toward the outside (in the downward developing direction in FIG. 9). In other words, the grid 1c at the time of development becomes larger as it goes further in the traveling direction F. Therefore, when each of the grids 1c is deformed in this manner, a strong tension E is applied to the lattice bar 1b + which is lowered to the right in FIG.
Is added and becomes fully stretched.
On the other hand, b- is slightly loosened. Then, when a storage battery is manufactured using an expanded grid expanded in a state where the tension applied to the grid bar 1b is non-uniform as an electrode plate, only the grid bar 1b + subjected to the strong tension E progresses faster. As a result, the life performance of the storage battery is reduced. The present invention has been made in order to cope with such a situation. By changing the length of four grid bars surrounding each square of a rotary type expanded grid, corrosion becomes uniform, and the storage battery is manufactured. It is an object of the present invention to provide a storage battery having improved life performance. According to a first aspect of the present invention, a large number of slits are formed in a metal sheet in a staggered manner, and the metal sheet is stretched in the width direction to develop each slit into a square. Thus, in a storage battery using an expanded grid as an electrode plate, which is a grid formed by connecting four grid bars each surrounding these squares in a net shape, opposing ones of the four grid bars surrounding each square are substantially the same. And the length of the other two grid bars is 102% or more and 120% or less with respect to the length of the two grid bars facing each other. According to the first aspect of the present invention, one of the two grid bars facing each other surrounding the grid is longer and the other grid bar is shorter, so that the grids have substantially parallel short sides and long sides having different lengths. It becomes a quadrilateral. Therefore, if the grid bar on the side receiving the strong tension in the expanding process by the rotary type is on the long side, the tension applied to the grid bar on the long side is reduced, and the grid bar on the short side is reduced. The applied tension increases. For this reason, relatively uniform tension is applied to the four grid bars surrounding each grid, so that only some of the grid bars are prevented from being easily corroded, and the life performance of the storage battery is improved. Will be able to do it. Embodiments of the present invention will be described below with reference to the drawings. FIG. 10 shows an embodiment of the present invention, and is a partially enlarged plan view of an expanded lattice in which squares are developed into parallelograms having different long sides and short sides in a rotary developing step. is there. Also in this embodiment, a storage battery using an expanded grid made by a rotary method as an electrode plate will be described. As shown in FIG. 10, the grids 1c of the expanded grid formed by the rotary method have a substantially parallelogram shape except for a substantially triangular shape adjacent to the current collecting frame 1a. That is, each square 1c is composed of four nodes 1e located at each vertex of the parallelogram and four lattice bars 1b connecting the nodes 1e. As shown in FIG. 8, the grids 1c of the conventional expanded grid manufactured by the rotary method are substantially parallelograms having the same length on each side, that is, substantially diamond-shaped, as shown in FIG. For this reason, the lengths of the four lattice bars 1b surrounding the grid 1c were also substantially equal. However,
As shown in FIG. 10, in the expanded lattice of the present embodiment, each grid 1c is a substantially parallelogram having long sides and short sides having different lengths, and four grid bars 1b surrounding the grid 1c. Of the two, the two grid bars 1b + inclined outward (in FIG. 10 in the lower direction of development) are longer at the tip of the progression arrow F of the metal sheet 1 and are more inside at the tip of the progression arrow F (FIG. In 10, the two lattice bars 1b- inclined toward the upper part of the current collecting portion 1a) are formed short.
The longer grid bar 1b + is connected to the shorter grid bar 1b-
Is formed to have a length of 102% or more and 120% or less. As described above, the lattice bar 1b surrounding the square 1c
In order to fabricate expanded lattices having different lengths by a rotary method, for example, the protrusion amount of the disk cutter 5 shown in FIG.
The perimeter along the protruding shape of (i) may be increased). When the slits 1d are formed by the conventional disk cutter 5 in which the protrusions of the peaks 5a are equal to each other, as shown in FIG. Although the lengths of the bars 1b are equal, the lattice bars 1b pressed by the mountain portions 5a having a large protrusion amount also have a large vertical deformation, and are elongated by this deformation. When the metal sheet 1 after the slit forming step is unfolded in the unfolding step, as shown in FIG. 10, the shape of the grid 1c surrounded by the lattice bars 1b having different lengths has the long sides having different lengths. And a substantially parallelogram having short sides. Also, at this time, the longer lattice bar 1b + is set so as to be inclined outward toward the tip of the progress arrow F of the metal sheet 1. The expanded lattice having the above-described structure is arranged such that, in the slit forming step by the rotary method, the longer lattice bar 1b is used.
Although + is greatly deformed, it can be avoided that a large tension is applied since it is already elongated in the unfolding step. Therefore, 2 surrounding each cell 1c
Longer grid bar 1b + and shorter grid bar 1b-
Can make the stresses received in both the slit forming step and the unfolding step substantially equal. The ratio of the length of the longer grid bar 1b + to the shorter grid bar 1b- was determined by examining various types. It has been found that corrosion of steel is effectively suppressed. This is because when the length ratio is less than 102%, there is almost no difference from the conventional expanded grid of the rotary type, and only the longer grid bar 1b + is corroded due to the tension imbalance in the developing process. This is because when the length ratio exceeds 120%, sufficient expansion is not performed in the expansion step, and the longer lattice bar 1b + is in a slack state. Moreover, the length of the longer grid bar 1b + is 106% or more and 115%
In the following case, the difference in the progress of corrosion between the longer grid bar 1b + and the shorter grid bar 1b- can be extremely reduced. In this embodiment, the length of the longer grid bar 1b + surrounding each grid 1c in the expanded grid is 10
The ratio of the amount of corrosion of the two types of lattice bars 1b when the ratio was changed from 0% to 130% was examined. The disk cutter 5 shown in FIG. 4 has the same amount of protrusion of the ridges 5a and the disk cutter 5 has a plurality of sets of protrusions with the protrusions of the ridges 5a increased every other one. Roll 6 was assembled. Then, using these disk cutter rolls 6, slits 1d were formed in the metal sheet 1 by a slit forming step, and expanded by a developing step, thereby producing an expanded lattice. As a result, 100% to 130% of the two longer grid bars 1b + surrounding the respective grids 1c of the expanded grid were manufactured. However, all expanded lattices are 115 mm long, 137 mm wide, and 0.9 mm thick,
Even if the shape of each grid 1c was changed, the size of the grid 1c was adjusted such that the weight per expanded grid was substantially constant. The expanded grids having different shapes of the grids 1c were all filled with the active material, then aged and dried to obtain a positive electrode plate. Then, the positive electrode plate and the negative electrode plate formed by a conventional manufacturing method are combined with a separator mainly composed of microporous polyethylene to lead-acid batteries 55D23 for automobiles (Japanese Industrial Standard JISD5301).
Was prepared. Further, these lead-acid batteries were completed by injecting a predetermined specific gravity and a predetermined amount of dilute sulfuric acid to perform chemical conversion. Then, using these lead-acid batteries, in a 60 ° C. water bath,
The battery was subjected to an overcharge test in which the battery was charged at 4.8 A for 30 days.
After the overcharge test is completed, the lead-acid battery is disassembled, the positive electrode plate is taken out, and the positive electrode plate is thoroughly washed with running water, and then heated to 50 ° C.
After drying in a gas phase for 48 hours, the positive electrode plate was impregnated with an epoxy resin. Then, after cutting the epoxy resin, the cut surface was polished until it became a mirror surface, and the size of the lattice was measured with a stereoscopic microscope to determine the amount of corrosion. The test results are shown in Table 1. [Table 1] As can be seen from Table 1, the lattice bars 1b-
And the length of the lattice bar 1b + is equal (the length ratio is 10
0%), the corrosion amount is 65:35 and there is about a two-fold difference, whereas the length of the grid bar 1b + is
In the case of going from 02% to 120%, the difference in the amount of corrosion decreased with the case of 110% as a peak. If there is a difference in the progress of corrosion between the lattice bars 1b + and 1b-, the previously corroded lattice bar 1b is cut early, but if there is no difference in the amount of corrosion, the progress of corrosion is almost equal. It has the longest life. Therefore, in order to sufficiently increase the service life, the length of the grid bar 1b + is set to 106% or more so that the difference in the amount of corrosion shown in Table 1 can be suppressed to less than 15%.
More preferably, it is within the range of 115% or less. However, in the case where the length of the lattice bar 1b + is 130%, the longer lattice bar 1b + is not fully developed and becomes loose at the time of development, and the thickness of the lattice exceeds a predetermined value. Was not implemented. In addition to the above examples, the size of the expanded lattice, the size of the grid 1c, the alloy composition of the metal sheet 1,
Similar tests were performed by changing the specific gravity of the electrolytic solution and the like. In each case, almost the same results as those in the above example were obtained. As is apparent from the above description, according to the storage battery of the present invention, by changing the length of the four grid bars surrounding each square of the rotary expanded grid, corrosion can be prevented. And the life performance of a storage battery using the expanded grid as an electrode plate can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a conventional example, and is a perspective view schematically showing a manufacturing process of a reciprocating expansion grating. FIG. 2 shows a conventional example and is a plan view of an expanded grating manufactured by a reciprocating method. FIG. 3 is a side view showing a conventional example and showing a slit forming step of an expanding lattice by a rotary method. 4 (a) is a side view, FIG. 4 (b) is a plan view of a disk cutter used in a slit forming step of a rotary type expanding grid, and FIG. It is a (c) partial enlarged side view near an arrow part. 5 shows a conventional example, and is a vertical sectional front view taken along the line AA of FIG. 3. FIG. FIGS. 6A and 6B show a conventional example, and are an enlarged side view of a part (a) and an enlarged plan view of a part of an expanded grating in which slits are formed in a rotary slit forming step. FIG. 7 is a plan view showing a conventional example and showing a step of developing an expanding grid by a rotary method. FIG. 8 shows a conventional example, and is a plan view of an expanded grating manufactured by a rotary method. FIG. 9 shows a conventional example, and is a partially enlarged plan view of an expanded grating being developed in a rotary type developing process. FIG. 10 is a partially enlarged plan view of an expanded lattice in which squares are developed into parallelograms having different long sides and short sides in a rotary developing step. [Description of Signs] 1 Metal sheet 1b Grid bar 1c Square 1d Slit

Claims (1)

Claims: 1. A plurality of slits are formed in a metal sheet in a zigzag pattern, and the metal sheet is stretched in the width direction to develop each slit into grids, thereby enclosing the grids. In a storage battery using an expanded grid, which is a grid formed by connecting grid grids in a grid form, as an electrode plate, opposing ones of the four grid grids that surround each cell are almost the same length, and these are opposed to each other. The length of the other two grid bars is 102 relative to the length of the other two grid bars.
% Or more and 120% or less.