JP2004139900A - Manufacturing method of grid base board for battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an economical manufacturing method of a thin and light-weighted grid base board for a battery with high quality by optimally combining a temperature of lead-alloy melting and and that of a casting mold at a book mold casting method. <P>SOLUTION: In the manufacturing method of the grid base board for a battery of manufacturing the grid base board for the battery with a thickness of 0.5 to 1.2 mm by the book mold casting method, the mold is heated so as to have a temperature of 0.7 to 0.9 times as high as the melting point of the lead-alloy, and a molten lead-alloy heated so as to have a temperature of 1.7 to 2 times as high as the melting point of the lead-alloy is poured into the above mold. Afterwards, the book mold is cooled by an air spray when releasing it. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to a method for manufacturing a thin and lightweight battery grid substrate, and more particularly to a method for manufacturing a grid substrate used for lead storage batteries such as automobile batteries and various backup batteries.
[0002]
[Prior art]
Due to recent energy and resource situations, there is a strong demand for lead-acid batteries to be smaller and lighter or have a longer life. To reduce the size and weight, it is effective to improve the utilization rate of the materials used. For that purpose, it is most important to effectively utilize the lattice substrate and improve the utilization rate of the active material.
The grid substrate occupies 30 to 50% by weight of the whole electrode plate although it does not directly affect the charge / discharge reaction of the battery. This lattice substrate has a problem that corrosion progresses with time, and as the corrosion progresses, the lattice substrate gradually does not play a role as a structure or an active material holder.
[0003]
Therefore, recently, the mechanical strength of the lattice substrate has been improved by optimizing the age hardening treatment, and the corrosion resistance has been improved by the development of a new alloy (addition of Ag; JP-A-6-29021, US Pat. No. 5,298,350, US Pat. Patent No. 5,434,025, Ba addition; WO97 / 05732, WO99 / 05732), and a movement to reduce the size and weight of the lattice substrate is coming out.
[0004]
[Problems to be solved by the invention]
A conventional lattice substrate is manufactured by book mold casting, and a plate thickness of 1.3 to 1.8 mm is used. In book mold casting for manufacturing a substrate lattice, a lead alloy melted at 400 to 550 ° C. is poured into a mold (substrate lattice plate thickness: 1.3 to 1.8 mm) heated to 120 to 200 ° C., taken out after solidification, and air cooled. For this reason, a thin substrate having a thickness of 1.2 mm or less cannot be obtained, which has been one of the barriers to battery weight reduction.
[0005]
In order to overcome this wall, the present inventor has conducted intensive studies on the reduction in thickness and weight of lattice substrate production by book mold casting, and as a result, there are two problems, namely, the flow of molten metal during casting and the release agent, that is, In the conventional book mold casting, in particular, since the casting is performed at a temperature of the molten metal of 400 to 550 ° C. and a temperature of the mold of 120 to 200 ° C., the viscosity of the molten lead alloy is high and the flow of the molten metal is not so good. I found out.
Accordingly, the present invention has been made in view of the above-mentioned conventional problems. In book mold casting, a thin and lightweight substrate grid can be manufactured with high quality and economically and advantageously by using an optimal combination of a lead alloy melt temperature and a mold temperature. Develop and provide methods.
[0006]
[Means for Solving the Problems]
The invention of claim 1 of the present application is directed to a method of manufacturing a battery grid substrate by book mold casting, wherein a mold is heated to a temperature 0.7 to 0.9 times the melting point of a lead alloy, A method of manufacturing a battery grid substrate, comprising: casting a lead alloy melt-heated to a temperature 1.7 to 2 times as high as that described above, and then cooling and opening the book mold.
[0007]
According to a second aspect of the present invention, there is provided a method of manufacturing a battery grid substrate for manufacturing a battery grid substrate having a grid thickness of 0.5 to 1.2 mm by book mold casting. After heating to 0.9 times the temperature and casting the lead alloy melted and heated to 1.7 to 2 times the melting point of the lead alloy in the mold, the book mold mold is cooled and opened. Is a method for producing a battery lattice substrate.
[0008]
In the method for producing a battery grid according to claim 1 or 2, it is preferable to cool the book mold after opening the molten lead alloy by air spray.
[0009]
In the present invention, a thin and light-weight substrate having a thickness of 0.5 to 1.2 mm is produced under good quality casting conditions because the flowability is improved by optimizing the combination of the temperature of the lead alloy and the temperature of the mold. It is possible.
[0010]
In the present invention, the reason why the melting temperature of the lead alloy is heated to 1.7 to 2 times the melting point of the alloy is that when the melting point exceeds 2 times the melting point, the solidification rate is slowed down, so This is because burrs increase in the portion, and twice the melting point of the lead alloy becomes the upper limit of the molten metal temperature for achieving a good lattice shape.
On the other hand, when the melting temperature of the lead alloy is less than 1.7 times the melting point of the alloy, the flow of the molten metal is poor, and the molten metal does not reach the bottom lattice of the substrate, so that the molten metal is not cut off, so that the melting occurs. 1.7 times is the lower limit of the molten metal temperature at which a good lattice shape is exhibited.
[0011]
In the present invention, the reason for heating the mold temperature to 0.7 to 0.9 times the melting temperature of the lead alloy is that when the melting temperature exceeds 0.9 times the melting point of the lead alloy, the solidification rate of the molten metal becomes slow. Problems such as leaching of molten metal from gaps and increase of burrs at the lattice portion occur, and the upper limit of the mold temperature is 0.9 times the melting point of the lead alloy.
On the other hand, when the mold temperature is less than 0.7 times the melting point of the lead alloy, the flow of the molten metal is poor, and the molten metal does not turn completely. Become.
[0012]
In the final step of book mold casting, if the cast substrate lattice is removed from the mold before the solidification of the crystal grain boundaries and sub-grain boundaries of the lead alloy in the cast lattice substrate is completed, deformation due to handling etc. will occur and hot cracking will occur. There is. Therefore, hot tearing can be effectively prevented by cooling with air spray when opening the book mold casting mold.
[0013]
Pb-Ca alloys, Pb-Sn alloys, Pb-Ca-Sn alloys, and Pb-Sn alloys obtained by adding one or more of Ag and Ba to these alloys are suitable as the lead alloy applicable to the present invention. However, the present invention is not limited to these lead alloys.
[0014]
Example 1
For a Pb-0.07 wt% Ca-1.3 wt% Sn-0.02 wt% Al alloy (melting point of the alloy is 325 ° C.), a substrate lattice having a middle lattice thickness of 0.6 mm and an outer lattice thickness of 1.0 mm is dug. Using a split book mold mold, casting was performed at a pouring temperature of 580 ° C. (1.8 times the melting point of the lead alloy) and variously changing the mold temperature. In addition, the cooling when opening the mold was air cooling. The result is shown in FIG. In the figure, the vertical axis is the appearance evaluation point, and reference numeral 1 denotes a product in which the vertical lattice and the horizontal lattice of the cast lattice substrate are incompletely formed and the discontinuity is extremely large; Indicates a product in which a part is slightly cut, 4 indicates a product having good appearance, 5 indicates a product in which casting burrs are slightly observed, 6 indicates a product in which casting burrs are large, and the horizontal axis indicates the temperature of the mold.
[0015]
As is clear from FIG. 1, it was found that a good cast product was obtained at a mold temperature of 230 ° C. (0.7 times the melting point of the lead alloy). However, at 300 ° C. or higher (0.92 times the melting point of the lead alloy), the molten metal seeps out of the gap of the mold to generate burrs. There was a discontinuity at the bottom. Therefore, a good condition is a mold temperature of 230 to 290 ° C. (0.7 to 0.9 times the melting point of the lead alloy).
Next, the quality of good cast products was checked by an X-ray transmission test on the lattice substrate manufactured at a mold temperature of 230 to 290 ° C., and it was verified that there was no problem in all.
Subsequently, as a result of performing a hot crack check on the lattice substrate manufactured at a mold temperature of 230 to 290 ° C., in the lattice bending test, a slight crack was observed in a part of the outer lattice of some products. However, this is due to the difference in the degree of cooling of the lattice substrate due to air cooling.
[0016]
Example 2
Book mold casting was performed under the same conditions as in Example 1, and when opening the split book mold mold, cooling was performed by air spray to produce a lattice substrate.
Next, the quality of good cast products was checked by an X-ray transmission test on the lattice substrate manufactured at a mold temperature of 230 to 290 ° C., and it was verified that there was no problem in all.
Subsequently, the lattice substrate manufactured at a mold temperature of 230 to 290 ° C. was subjected to a hot crack check, and as a result, it was confirmed that there was no problem.
Since the grid substrate was cooled by air spray, the grid substrate could be taken out in a relatively short time, and the quality (hot cracking) of the grid substrate taken out was stable.
[0017]
Example 3
Next, the Pb-3.5Wt% Sb-0.03As alloy (the melting point of the alloy was 315 ° C) was cast using the book mold. Casting was carried out at a pouring temperature of 560 ° C. (1.78 times the melting point of the lead alloy) and by changing the mold temperature. When the mold was opened, it was cooled by air spray to produce a substrate lattice. The result is shown in FIG. The vertical axis is the appearance evaluation point, the sign means the same as in FIG. 1, and the horizontal axis is the mold temperature. As is clear from the figure, the favorable mold temperature was about 220 ° C. to 280 ° C. (0.7 to 0.9 times the melting point of the lead alloy).
[0018]
Example 4
A recently developed Pb-0.04 wt% Ca-1.1 wt% Sn-0.008 wt% Ba alloy (having a melting point of 326 ° C.) was cast using the same split book mold. The pouring temperature is 620 ° C (1.9 times the melting point of the lead alloy), casting is performed by changing the mold temperature, and when opening the split book mold mold, it is cooled by air spray to produce a lattice substrate. did. The result was almost the same as the result of Example 1 shown in FIG. 1, and the mold temperature was about 230 ° C. to 290 ° C. (0.7 to 0.9 times the melting point of the lead alloy). .
As a result of performing an X-ray transmission test and a grid bending test on the grid substrate manufactured at a mold temperature of 230 to 290 ° C., it was confirmed that there was no problem.
[0019]
Example 5
Similarly, Pb-0.04wt% Ca-0.6wt% Sn-0.008wtBa-0.03wt% Ag alloy (melting point of the alloy is 325 ° C) was cast using the split mold. . Casting was performed at a pouring temperature of 580 ° C. (1.78 times the melting point of the lead alloy), changing the mold temperature, and cooling by air spray when opening the split book mold mold to produce a lattice substrate. . The results were the same as in FIG. 1, and favorable conditions were a mold temperature of 230 to 290 ° C.
As a result of an X-ray transmission test and a bending test of the lattice substrate manufactured at a mold temperature of 230 to 290 ° C., it was confirmed that there was no problem in quality.
[0020]
Example 6
For the lead alloy of Example 1 (melting point of the alloy is 325 ° C.), various split books in which a substrate lattice having a medium lattice thickness of 0.4 mm to 1.5 mm and an outer lattice thickness of 1.0 mm to 1.8 mm are dug. A grid substrate was manufactured using the same method as in Example 2 using a mold, and as a result of an X-ray transmission test and a bending test for each manufactured grid substrate, a product having a medium grid thickness of 0.4 mm was partially affected by the flow of molten metal. However, it was confirmed that a product having a size of 0.5 mm or more was a good lattice substrate having no problem at all.
[0021]
Example 7
With respect to the lead alloy of Example 4 (the melting point of the alloy was 326 ° C.), the mold temperature was kept at 260 ° C., and the casting was performed while changing the temperature of the molten metal to examine the influence of the temperature of the molten metal. The result is shown in FIG. The vertical axis is the appearance evaluation point, and the horizontal axis is the molten metal temperature. The sign of the appearance evaluation point is the same as that in FIG.
As is clear from the figure, the casting was successfully performed in the range of about 550 to 650 ° C. (1.7 to 2 times the melting point of the alloy).
[0022]
Comparative Example 1
Using a split book mold mold in which a substrate lattice having a middle lattice thickness of 0.6 mm and an outer lattice thickness of 1.0 mm was dug, the pouring temperature of the alloys of Examples 1 to 5 was 450 ° C. (about the melting point of the lead alloy). (1.4 times) and casting was performed at a mold temperature of 150 ° C. As a result, the molten metal does not turn around on the grid substrate due to poor flow of the molten metal, and the grid substrate is cut off, so that the quality as a product cannot be maintained.
[0023]
Reference Example 1
For reference, the lead alloys of Examples 1 to 5 were poured at a temperature of 450 ° C. and a mold temperature using a split book mold mold in which a substrate lattice of 0.9 mm in middle lattice and 1.4 mm in outer lattice was dug. Casting was performed at 150 ° C., and the weights of the products of Examples 1 to 5 were compared. As a result, it was confirmed that the weight of the product of the example was 0.69 times that of the product of the reference example, and the weight was reduced by 31%.
[0024]
A lead-acid battery was assembled using the grid substrate manufactured according to the present invention and the grid substrate of Reference Example 1, and a test was performed in an environment of 75 ° C. according to the light load life specified in JIS D 5301. As a result of the comparison, the lifespan of the grid substrates described in Examples 1 and 3 was 0.1% in comparison with the one described in Reference Example 1 even though the weight of the lattice substrate was reduced by 31%. Nine times, the reduction is only 10%, and when the ones described in Examples 4 and 5 are used, the life is extended to 1.5 times or more, and the material life can be reduced without reducing or improving the life so much. It was confirmed.
[0025]
【The invention's effect】
The present invention heats a book mold casting mold to a temperature 0.7 to 0.9 times the melting point of the lead alloy, and melts and heats the mold to a temperature 1.7 to 2 times the melting point of the lead alloy. This is a method for manufacturing a battery grid substrate, which comprises cooling an open book mold mold after casting the alloy and opening the mold. The grid thickness is 0.5 to 1.2 mm, which is thinner than a conventional grid substrate ( (A miniaturized), lightweight lattice substrate can be provided, and the production can be done by simply changing the engraving of the mold, the conventional book mold casting device can be used as it is, the cost of equipment modification etc. can be reduced, and the material cost (lead alloy (E.g., the amount used) is economically advantageous as it requires only a small amount, and has an industrially superior effect of providing a thin and lightweight substrate grid with excellent quality without problems such as hot cracking. is there.
[Brief description of the drawings]
FIG. 1 is a graph showing the appearance evaluation results of a cast lattice substrate when a mold temperature is changed while a molten metal temperature is kept constant using a lead alloy.
FIG. 2 is a graph showing the appearance evaluation results of a cast lattice substrate in the case where the temperature of a molten metal is fixed and the temperature of a mold is changed using another lead alloy having a different melting point.
FIG. 3 is a graph showing the results of evaluating the appearance of a cast lattice substrate when a molten metal temperature is changed while a mold temperature is kept constant using a lead alloy.

Claims (3)

In a method of manufacturing a battery grid substrate by book mold casting, a mold is heated to a temperature of 0.7 to 0.9 times the melting point of a lead alloy, and the mold is heated to a temperature of 1.7 to 2 times the melting point of a lead alloy. A method of manufacturing a battery grid substrate, comprising: casting a molten and heated lead alloy into a mold; and cooling and opening the book mold. In a battery grid substrate manufacturing method for manufacturing a battery grid substrate having a grid thickness of 0.5 to 1.2 mm by book mold casting, a mold is heated to a temperature of 0.7 to 0.9 times the melting point of a lead alloy. A method of manufacturing a battery grid substrate, comprising: casting a lead alloy melt-heated to a temperature 1.7 to 2 times the melting point of the lead alloy into the mold; and cooling and opening the book mold mold. The method according to claim 1 or 2, wherein cooling is performed by air spray when opening the book mold after casting the molten lead alloy.

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