JPS6061162A - Casting method of grid body for lead storage battery - Google Patents

Abstract

PURPOSE:To produce efficiently a grid body having high quality by providing a projecting part to a casting groove for the lug part of the grid body, making the sectional area in the longitudinal direction thereof correspondent with the increase or decrease in the sectional area in the longitudinal direction of the casting groove and performing casting without coating a mold coating material to the projecting part. CONSTITUTION:The sectional area in the longitudinal direction of a projecting part 6' provided to a casting groove 5 for a lug part with the mating surfaces 1 of a casting mold for casting a grid body is increased or decreased in a positive correlation in accorcance with the increase or decrease in the sectional area in the longitudinal direction of the groove 5 to unify, for example, the width W1 of the part 6' with respect to the width W2 of the groove 5 to about 23%. A mold coating material 8 such as cork is coated on the mating surfaces 1 subjected to preheating prior to pouring and thereafter only the material 8 on the part 6'is chipped off and the surfaces 1 are butted and a molten metal is cast into the mold. Not only the lug part of the grid body but also the entire part of the grid are thus uniformly and quickly cooled and solidified and the grid body having high quality without crack and burn is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application Page 2 The present invention relates to an improvement in the casting method for grid bodies for lead-acid batteries.

Conventional Structures and Problems The molds for lattice bodies for lead-acid batteries are generally mated molds, in which a pair of molds are formed with corresponding lattice-shaped grooves on one side of the molds facing each other, and the two molds are joined by butting each other. There is.

FIG. 1 shows one of the pair of molds. In the figure, 1 is a mold mating surface, 2 is a vertical lattice groove, 3 is a horizontal lattice groove, 4 is a frame groove, and 6 is an ear casting groove, hereinafter referred to as an ear forming groove. Casting is performed using a mating mold made of a suitable material such as cast iron, and after the fixed mold and movable mold are closed together, molten lead or lead alloy (hereinafter referred to as hot water) is poured from the pouring hole provided in the mold. ), and after cooling and solidifying it, the mold is opened and the product, the lattice, is taken out. In this case, the frame ribs, horizontal lattices, and vertical lattices are all thin, and are cooled and solidified relatively uniformly.

However, the ears of the lattice body are generally rectangular, and their volume is much larger than that of the horizontal and vertical lattices, and the amount of hot water injected is large. Therefore, if you just apply a coating agent such as cork powder, the cooling and
Solidification is not promoted uniformly, and heat remains near the boundary line between the frame bones connecting the horizontal and vertical grids and the ears (hereinafter referred to as the boundary) or near the center of the ears, resulting in cracks.

A defect called discoloration occurred, and the strength of the affected area was significantly reduced, making it brittle9 and causing the edges to break. On the other hand, in order to improve this problem, a band-shaped protrusion 6 is formed along the length direction of the ear forming groove at the center of the groove as shown in Fig. 2, and a coating agent is applied to the protrusion 6. A casting method has been proposed in which the heat remaining in the vicinity of the center of the ear is quickly radiated by casting without molding, thereby preventing cracking or discoloration of the ear. This casting method significantly reduced cracks and discoloration that occur near the center of the ear, and improved castability. However, in the boundary portion 7, in order to improve the moldability of the ear portion, improve the physical strength, and improve the voltage characteristics of the battery, the boundary portion 7 is formed into a circular arc with a large radius and has a sloped thickness that connects to the frame rib. The curving boundary is the part where the frame bones, which have a larger cross-sectional area than the horizontal and vertical lattices, and the ears, which have a significantly larger cross-sectional area, come into contact. Therefore, the volume of the boundary area is extremely large, and the cooling of the protrusions that are provided evenly is delayed compared to areas other than the boundary area, resulting in cracks and cracks due to residual heat.
Due to the discoloration, the strength decreased, and as a result, bending occurred at the boundary.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks and aims to efficiently produce high-quality lattices. Of the grooves, the ear forming groove is provided with a protrusion whose longitudinal cross-sectional area increases or decreases in a positive correlation with the increase or decrease in the longitudinal cross-sectional area of the ear cut. This method is characterized by casting without applying a mold coating agent. According to this casting method, the cross-sectional area of the protrusion is increased even in the part where the ear forming groove is wider or deeper than other parts and has an increased cross-sectional area, and cooling is delayed when pouring hot water. As a result, the amount of heat dissipated is large, and cooling proceeds at a uniform speed throughout the entire grid, including the ears. Therefore, it is possible to efficiently produce high-quality lattice bodies that do not crack or burn due to residual heat.

DESCRIPTION OF EMBODIMENTS An embodiment of the casting method of the present invention will be described below. FIG. 3 shows the ear forming portion of the mold used in the casting method of the present invention. In this figure, the protrusion 6' has a circular arc near the boundary according to the circular arc at the boundary of the ear forming groove, and the width W2 of the ear forming groove.
On the other hand, the width W1 of the protrusion is.

Approximately 23 inches at any location on the ear.

FIG. 4 shows a cross section of the groove taken along the line AA' shown in FIG. 3. The mold was preheated to 180 to 200°C before pouring hot water, and a coating agent 8 such as cork was applied to the mating surfaces of the mold as shown in Figure 6 to provide heat retention and release effects. Scrape off only the coating agent on 6' as shown in Figure 6.

After that, hot water is poured into the mold space formed by butting the cylindrical molds together. Cooling of the hot water starts immediately after pouring into the mold, but the heat of the hot water is easily absorbed into the mold body through the exposed protrusion 6' of the mold, and the increase in the cross-sectional area of the protrusion 6' causes the boundary Cooling progresses quickly in the parts as well, and not only the ears but the entire grid are cooled and solidified uniformly and quickly at the same speed. Therefore, a high quality lattice body can be efficiently obtained without cracking or burning.

In addition, when finishing the lattice body as an electrode plate and creating a group of electrode plates, there is a step of inserting the ears of the lattice body into a comb-tooth jig. A method has also been adopted in which the thickness of a portion of the grid body is changed to match the thickness of the other lattice body ears. In this case, a change in cross-sectional area occurs due to a change in depth in the ear forming groove of the mold, but by changing the cross-sectional area due to a change in the height of the protrusion, a similarly high-quality lattice body can be obtained efficiently. be able to.

Figure 7 shows the change in the width of the protrusion relative to the width of the ear groove in a mold in which the depth of the ear groove and the width of the protrusion are constant, and the incidence of lattice defects due to cracking and discoloration at the ear. and its influence on castability. As is clear from the figure, as the width of the protrusion increases with respect to the width of the ear forming groove, the defect rate rapidly decreases, and when the width ratio is 20%, the defect rate becomes 30% or less. 20
%, the defective rate gradually decreases, but the castability gradually decreases, albeit by 7%, and when the width ratio exceeds 40%, the decrease in castability becomes remarkable. Therefore, the width of the protrusion relative to the ear forming groove is 20~
40 salary is suitable. Fig. 8 shows the influence of changes in the cross-sectional area in the longitudinal direction of the protrusion relative to the area of one area in the longitudinal direction of the ear forming groove on the incidence of lattice defects due to cracking and discoloration at the ear and on castability. show.

This change in cross-sectional area also shows the same tendency as the width, and for the same reason, the cross-sectional area of the protrusion relative to the ear forming groove is 1.5 to 3.
6% is suitable.

Effects of the Invention: According to the casting method of the present invention, even if the mold has any groove shape for the ears, not only the ears but the entire grid can be uniformly and quickly cooled and solidified, and there is no cracking or fading due to heating. A lattice body of good composition and high quality can be efficiently obtained.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing one of a pair of molds used in the conventional casting method, Fig. 2 is an enlarged view of -J% section of the kerf, and Fig. 3 is a plan view showing one of a pair of molds used in the conventional casting method.
The figure is an enlarged view of the main part of the cut groove of the mold used in the example of the present invention,
Figure 4 is a cross-sectional view taken along the line A-A' in Figure 3, Figure 5 is a cross-sectional view when the mold coating is applied to the mold mating surface, and Figure 6 is a cross-sectional view when the mold coating is removed from the protrusion. Figure 7 is a characteristic diagram showing the relationship between the ratio of the width of the protrusion to the width of the selvedge groove, the lattice failure rate, and castability, and Figure 8 is the relationship between the cross-sectional area of the selvedge groove. It is a characteristic diagram which shows the relationship between the ratio of the cross-sectional area of a protrusion, a lattice failure rate, and castability. 1... Mold mating surface, 2... Vertical lattice groove,
3... Horizontal lattice groove, 4... Frame bone groove, 5...
...Ear groove, 6...Protrusion, 7...
... Boundary part, 8... Coating agent. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 4
Figure 5 Figure 6 Figure 7 Figure 8

Claims (3)

[Claims] (1) Among the lattice casting grooves of a pair of molds, the longitudinal cross-sectional area of the ear groove increases or decreases in a positive correlation with the increase or decrease in the longitudinal cross-sectional area of the ear casting groove. A method for casting a lattice body for a lead-acid battery, characterized in that, after providing a protrusion to which no coating agent is applied, molten lead or a lead alloy is injected into a mold space formed by butting both molds together. (2) The method for casting a grid for a lead-acid battery according to claim 1, wherein the width of the protrusion is 20 to 40% of the width of the ear casting groove. (3) The cross-sectional area of the projection in the longitudinal direction is 1.5 to 3.6% of the cross-sectional area of the groove in the longitudinal direction. Casting method for grids for lead-acid batteries.