JP2008071619A - Manufacturing method of grid for lead acid storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead acid storage battery having a current collector manufactured by machining process in which welding reliability between a current collecting ear and a strap and productivity can be improved. <P>SOLUTION: The manufacturing method of a grid having a current collecting ear with a thick portion is provided with a process in which a lead or lead alloy sheet having a first thick portion 21 to form a current collecting ear and a second thick portion thinner than the first thick portion is formed, a process in which the second thick portion is expansion or punching worked to obtain a grid precursor sheet, and a process in which the grid precursor sheet is cutting worked. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a grid for a lead storage battery.

  A lead storage battery generally includes a battery case, an electrode plate group, and an electrolytic solution. The electrode plate group generally includes a plurality of positive plates, a plurality of negative plates, and a plurality of separators, and the positive plates and the negative plates are alternately stacked via the separators. In the laminate, a portion called a strap is formed by welding positive electrode plates and negative electrode plates to each other with current collecting ears provided on the respective electrode plates. The positive electrode plate and the negative electrode plate are formed by filling a current collector made of lead or a lead alloy with an active material.

  As a method of forming a strap by welding the electrode plates of the same polarity to each other, a “burner welding method” for giving a lead or lead alloy dissolved in a burner to the current collecting ear portion, The current collecting ear is immersed in molten lead or molten lead alloy in a mold including necessary members such as a strap, a pole column, and a button for connecting cells, and the molten lead or molten lead alloy in the mold is The “cast-on-strap (COS) method” for solidifying is common.

  However, when welding the strap and the current collecting ear, in the “burner welding method”, there is a gap between the strap and the current collecting ear interface due to the current collecting ear not being sufficiently melted. May occur. Further, when the surface of the current collecting ear portion is dirty even in the “COS method”, or when the temperature of the molten lead in the mold is low, as shown in FIG. A positive meniscus 3 that can be formed at the contact boundary cannot be formed, and a negative meniscus 4 may be formed at the contact boundary between the strap 1 and the current collecting ear portion 2 as shown in FIG.

  On the other hand, when the lead alloy composition of the current collecting ear and the lead alloy composition of the strap are different, when the current collecting ear and the strap are immersed in an electrolyte solution, A local battery may be formed and corrosion may occur on either the collecting ear or the strap.

  When a poorly welded part or a local battery as described above occurs, the durability of the current collector ear and the strap deteriorates due to the progress of corrosion starting from the poorly welded part and the corrosion caused by the local battery, leading to lead acid batteries. During the use period of the battery, the strap and the current collecting ear may come off and the capacity of the lead storage battery may be reduced.

  Such a problem is conspicuous in a lead-acid storage battery with a long expected life, and in order to solve such a problem, as described in JP-A-11-45697, Have been proposed, such as a method using an electrode plate group having the same composition as that of the electrode plate, a method in which the current collecting ear portion of the electrode plate group is thicker than the current collector body portion, and the like. However, the method described in Japanese Patent Application Laid-Open No. 11-45697 is for a lead storage battery using a cast grid that is expected to have a relatively long life, such as a stationary lead storage battery. In the cast grid, it is relatively easy to freely design the shape of the current collecting ear portion including the shape of the current collector according to the shape of the mold.

  On the other hand, lead-acid batteries for automobiles and motorcycles that focus on cost reduction are manufactured by machining, specifically expanding or punching, on lead or lead alloy sheets instead of cast grids. In general, a current collector is used. Lead-acid batteries that use these current collectors are rarely required to be as long as stationary lead-acid batteries. However, even these lead-acid batteries for automobiles and two-wheeled vehicles have straps as described above. When the disconnection from the current collecting ear occurs, the capacity of the lead storage battery is reduced.

In order to improve the durability of connection between the strap and the current collecting ear, when applying the technique disclosed in Japanese Patent Application Laid-Open No. 11-45697 to a current collector obtained by machining a sheet, a conventional current collector obtained by machining the sheet is used. The body could not be provided with a thick portion because the sheet thickness itself was uniform.
JP-A-11-45697

  The problem to be solved by the present invention is to provide a lead storage battery in which the reliability of the connection between the current collecting ear and the strap is improved even in a lead storage battery including a current collector manufactured by machining.

  As a means for solving the above-mentioned problem, in claim 1, in a method for manufacturing an expand or a punched grid with a current collecting ear having a thick part, a first thickness portion forming the current collecting ear, Forming a lead or lead alloy sheet having a second thickness portion thinner than the first thickness portion; and expanding or stamping the second thickness portion to obtain a lattice precursor A method for producing a grid for a lead-acid battery comprising a current collecting ear having a thick part, comprising a step of obtaining a sheet and a step of cutting the grid precursor sheet.

  By the above-mentioned method, the same alloy composition of the current collector and the strap can be manufactured. For this reason, the corrosion by the local battery of a current collection ear | edge part and a strap is lose | eliminated. Further, since the current collecting ear part and the strap are integrally formed by the above-described method, the welding failure found in the “burner welding method” at the boundary part between the current collecting ear part and the strap, “COS method”. The negative meniscus seen can be eliminated. Further, since the current collector is expanded or punched, continuous production of the current collector is facilitated as compared with a current collector manufactured by batch processing such as a cast grid. The above-mentioned expanding process is a so-called “rotary expanding process” in which a zigzag slit is engraved in a lead or lead alloy sheet, and then the sheet is expanded, a convex blade is applied to the lead or lead alloy sheet, and the sheet This corresponds to a so-called “reciprocating type expansion process” in which the sheet is developed while chopping up.

  On the other hand, according to the punching process, the production speed is inferior to that of the expanding process, but continuous production becomes easier than casting. Further, the punching has an advantage that the shape of the lattice can be freely designed as compared with the expanding process.

  As described above, the current collecting ear portion of a lead storage battery current collector manufactured by machining lead or a lead alloy sheet is provided with a thick portion thicker than the current collector thickness, and the thick portion Is connected, and the strap is formed, so that the corrosion resistance of the boundary portion between the current collecting ear portion and the strap can be improved. A current collector can be provided.

  In producing the lead or lead alloy sheet, the best mode for carrying out the present invention is to provide a thick part that can be a part of the strap in a part of the sheet.

  FIG. 8 is a view schematically showing the sheet manufacturing method from the side. As shown in FIG. 8, the sheet 10 is usually manufactured by passing a plate-like continuous cast body called a slab 11 having a thickness of several millimeters to several tens of millimeters, generally through a plurality of stages of rollers 12 to obtain a predetermined sheet. It is rolled to a thickness. The rolling with this roller 12 is a conventional method that the entire surface of the sheet has a uniform thickness. Although FIG. 8 shows a method for casting molten slab 11 by pouring molten lead between wheel 13 and belt 14, the method for casting slab 11 is not limited to this method. Moreover, although the roller 12 is drawn as four sets in FIG. 8, the number of sets of the rollers 12 can be arbitrarily determined by the manufacturer. Each time it passes through the roller 12, the thickness of the slab 11 is gradually reduced, and after passing through the roller 12 at the final stage, the sheet 10 has a predetermined thickness.

  For reference, FIG. 9 shows a schematic view of the manufacturing schematic side view of the sheet shown in FIG. 8 as viewed from above.

  FIG. 1 shows a schematic top view of manufacturing the sheet 20 according to the present invention. 1 is different from FIG. 9 in that the third stage and the fourth stage roller 12 'are not one continuous rod-like body, but the middle part thereof is interrupted. That is, the slab 11 is gradually thinned by the first-stage and second-stage rollers 12, and the thickness at the time when the second stage is exceeded is the thickness of the strap integrated with the current collector, that is, the first thickness. This is part 21. While leaving the first thickness portion 21, the thickness of the sheet 20 other than the first thickness portion 21 is the same as the second thickness portion 22 when passing through the fourth roll 12 ′. To do. Although FIG. 1 shows the case of four-stage rolls 12 and 12 ′, as described above, the number of roll stages can be arbitrarily set by the manufacturer, and the roll 12 ′ is limited to the third stage. It is not something.

  As shown in FIG. 2, the sheet 20 manufactured as shown in FIG. 1 is subjected to machining (expanding or punching) on the second thickness portion 22 so as to have a grid-like grid. By making an electric body and cutting the first thickness portion 21 into an arbitrary shape, a current collecting ear portion provided with a strap can be obtained. For example, as shown in FIG. 3, the start position of the square is set according to the design matters such as the paste application area and the separator installation position, and the conditions in the subsequent process such as the paste surface pressing process. The thickness portion 22 can be arbitrarily determined. For this purpose, the grid may be cut so as to be formed on the entire surface of the second thickness portion 22 or may be cut so as to be formed below the position adjacent to the first thickness portion 21. A current collecting ear can also be provided in the second thickness portion 22.

  In addition to the method shown in FIG. 1, as shown in FIG. 4, it is also possible for the roller 12 ′ to be in a state in which the intermediate portion is not interrupted as shown in FIG. 1 and the end is interrupted. . In this case, the shape of the sheet 20 is as shown in FIG. In FIG. 4, the number of stages of the rollers 12, 12 'is arbitrary, and the machining method in FIG. 4 is also arbitrary.

  The method of FIG. 1 and the method of FIG. 4 can be appropriately selected depending on the convenience of the manufacturer, such as the size, shape, and required production speed of the current collector to be manufactured.

  The present invention will be described in detail based on examples.

(Example 1)
A sheet made of Pb-0.08% Ca-0.5% Sn alloy having a thickness of 1.0 mm was used as a current collector by rotary expanding. The size and shape of the current collector were the same for both the product A of the present invention and the conventional product B. However, although the current collecting ear portion of the product A of the present invention has a thick portion having a thickness of 3.9 mm, the current collecting ear portion of the conventional product B has no thick portion. Here, the same current collector was used for both positive and negative electrodes.

  Both the positive and negative electrode plates had a thickness of 1.0 mm, the gap between the electrodes was 1.0 mm, and a microporous polyethylene separator was used as the separator. Both the product A of the present invention and the product B of the prior art had a configuration of 4 positive electrodes and 5 negative electrodes, and the electrolyte was diluted sulfuric acid having a specific gravity of 1.280 at 20 ° C. and injected to a predetermined position in the battery case. The completed test battery was a 36 Ah (5 hR) -12 V open type lead acid battery.

  The product A of the present invention was made into a strap by melting the strap portion integrated with the current collecting ear portion with a burner without using additional lead. In the conventional product B, a lead alloy made of lead alloy having the same composition as the current collector is added to the current collecting ear portion to form a strap.

  These batteries were discharged in a 90 ° C. water bath at 25 A for 1 minute and subjected to a life test with a pattern in which the cells were charged at 2.47 V per cell (maximum current 25 A) for 10 minutes. Here, in order to evaluate the durability of the strap, regardless of the transition of the end-of-discharge voltage of the lead storage battery during the test, a test of 5000 cycles was performed, and after the end of 5000 cycles, the battery was disassembled, and the strap and The connection state with the electric ear was confirmed.

  In each of the tests with 10 batteries, the product A of the present invention showed no disconnection of the current collecting ear from the strap in any polarity of the positive and negative electrodes, whereas the conventional product B In the battery, 7 batteries for the positive electrode and 8 batteries for the negative electrode were found to be disconnected from the current collecting ear.

(Example 2)
A test battery substantially the same as in Example 1 was used. The difference between Example 1 and Example 2 was that the product C of Example 2 of the present invention formed a strap by COS instead of the burner welding of Example 1. Note that the conventional product D to be compared also has a strap formed by COS.

  This battery was subjected to the same test as in Example 1, and the bonding state between the strap and the current collecting ear after 5000 cycles was confirmed.

  In any case, when the test was conducted with 10 batteries each, the product C of the present invention showed no disconnection of the current collecting ear from the strap at any polarity of the positive and negative electrodes. In the positive electrode and the negative electrode, there were 4 batteries, and the current collector ears were removed from the strap.

(Example 3)
A test battery similar to that in Example 1 was used. The difference between Example 1 and Example 3 is that the current collector of Example 1 was subjected to an expanding process, whereas the current collector of Example 3 was subjected to a punching process. A strap was formed by burner welding between the product E of Example 3 and the conventional product F to be compared. However, in the product E of the present invention, no additional lead was used, and in the conventional product F, additional lead having the same composition as the current collector was used.

  This battery was subjected to the same test as in Example 1, and the bonding state between the strap and the current collecting ear after 5000 cycles was confirmed.

  In each of the tests with 10 batteries, the product E of the present invention showed no disconnection of the current collecting ear from the strap in any polarity of the positive and negative electrodes, whereas the conventional product F In the battery, 6 batteries for the positive electrode and 8 batteries for the negative electrode were found to be disconnected from the current collecting ear.

Example 4
A test battery substantially the same as in Example 3 was used. The difference between Example 3 and Example 4 is that the product G of the invention G of Example 4 was not formed by the burner welding of Example 3 but formed a strap by COS. The conventional product H to be compared also has a strap formed by COS.

  This battery was subjected to the same test as in Example 1, and the bonding state between the strap and the current collecting ear after 5000 cycles was confirmed.

  In each of the tests with 10 batteries, the product G of the present invention showed no disconnection of the current collecting ear from the strap in any polarity of the positive and negative electrodes, whereas the conventional product H In the battery, 3 batteries for the positive electrode and 4 batteries for the negative electrode were observed.

  In addition to Examples 1 to 4 described above, the lead-acid battery in which the thickness of the thick part provided in the current collecting ear part, the size and shape of the electrode plate, etc. are variously changed, and the charge / discharge cycle life test, float life test, overcharge Tests, overdischarge tests, neglect tests, etc. were conducted, but in any case, the lead-acid battery using the present invention improved the durability of the connection between the current collecting ear and the strap compared to the conventional lead-acid battery. Results were obtained.

The schematic top view which showed the manufacturing method of the sheet | seat by this invention. Schematic diagram of the sheet manufactured by the method of FIG. The schematic top view which showed the manufacturing method of the grating | lattice by this invention. The schematic top view which showed the manufacturing method of the sheet | seat by this invention. Schematic diagram of the sheet manufactured by the method of FIG. Schematic diagram of positive meniscus strap and current collector ear boundary Schematic diagram of negative meniscus strap and current collector ear boundary The schematic side view which showed the manufacturing method of the sheet | seat. The schematic top view which showed the manufacturing method of the conventional sheet | seat.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Strap 2 Current collecting ear 3 Positive meniscus 4 Negative meniscus 10 Lead or lead alloy sheet 11 Slab 12 Rolling roller 12 'Rolling roller 13 Wheel 14 Belt 15 Upper forehead equivalent 16 Mesh part 17 Disposal part 20 The present invention Sheet 21 according to the invention The first thickness part of the sheet according to the invention 22 The second thickness part of the sheet according to the invention

Claims (1)

In a method for producing an expanded or punched grid with current collecting ears having a thick part,
Forming a lead or lead alloy sheet comprising a first thickness portion forming a current collecting ear and a second thickness portion thinner than the first thickness portion;
Expanding or stamping the second thickness portion to obtain a lattice precursor sheet;
A method for producing a grid for a lead-acid battery comprising a current collecting ear having a thick part, comprising the step of cutting the grid precursor sheet.

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