US2496991A - Mold for casting storage battery straps - Google Patents

Description

Feb. 7, 1956) c. D. GALLOWAY 294969991 MOLD FOR CASTING STORAGE BATTERY STRAPS Filed Nov. 8, 1946 Patented Feb. 7, 1950 v MOLD FOR CASTING STORAGE BATTERY STRAPS Charles Douglas Galloway, Wyndmoor, Pa., assignor to The Electric Storage Battery Company, a corporation of New Jersey Application November 8, 1946, Serial No. 708,671

3 Claims.

This invention relates to molds and more particularly to molds for casting metal straps on lugs of storage battery plate assemblages.

In my copending application Serial No. 538,564, filed June 3, 1944, now Patent 2,454,051, issued November 16, 1948, entitled Method and apparatus for the manufacture of elements for storage batteries, assigned to the assignee of this application, there is described and claimed a mold having a pair of open cavities in which plate lugs of opposite polarity of assembled storage battery elements may be placed and molten metal poured therearound to form straps. Means are provided for applying heat to the mold adjacent the floors of the cavities after the introduction of the molten metal to superheat the metal and thereby weld the tips of. the lugs to the straps and subsequently for cooling the mold and ejecting the casting.

The present invention is concerned with improvements in molds of the character described in my aforesaid copending application and has for an object to provide molds that are integrally constructed, thereby eliminating possibility of leakage around the floor of the mold.

Further objects of the invention are to provide improved molds specially constructed to promote more uniform distribution of heat; to provide improved molds within which plate connected straps may be cast to exact size without the necessity for trimming; and to provide improved molds adapted to undergo rapid temperature changes, provision being made for limiting or preventing distortion due to such changes.

It is a further object of the invention to provide molds having means for circulating coolant in which the coolant is introduced and discharged through fittings designed to insure permanence against leakage even though the fittings are cooled more rapidly and contract faster than the mold body.

In my copending application Serial No. 708,672, filed November 11, 1946, entitled Apparatus for casting connecting straps on storage battery lugs, likewise assigned to the assignee of this application, there is described and claimed improved apparatus for performing the various steps required to cast straps on battery lugs. A further object of the present invention is to provide molds particularly adapted to be employed in said apparatus.

:In accomplishing these and other objects of the present invention, I have provided improved details of structure, a preferred form of which is shown in. the. accompanying drawing, whereinz.

Figure 1 is a top plan view of a mold embodying features of the present invention a portion being broken away to illustrate details of the construction;

Figure 2 is a side elevational view, partly in section, of the mold shown in Figure 1;

Figure 3 is a vertical sectional view of the mold taken substantially on the line 33 of Figure 1; and

Figure 4 is a side elevational view of a modified form of mold embodying the features of the present invention.

Referring more in detail to the drawing:

There is shown at It] a mold constructed as an integral machined or fabricated shape, preferably of steel, in accordance with the present invention. Although only a single mold is shown, the mold is normally employed in opposed pairs, one mold of each such pair being adapted to receive the positive plate lugs and the other to receive the negative plate lugs of assembled storage battery elements on which connecting straps are to be cast. The use of opposed pairs of molds for casting straps in such fashion is fully illustrated in both of my copending applications hereinbefore referred to.

The mold, l0 has a rectangular floor portion II, around the periphery of which are upstand ing end walls l2 and [3, back wall M and front wall IS. The floor and walls of the mold thus define an open cavity within which lugs of an assemblage of storage battery plates may be inserted and molten metal poured to cast straps thereon. A plate lug inserted within the mold is shown in dot-dash lines at P in Figure 3. The dimensions of the cavity are such as to cast the strap directly to the desired final dimensions, thereby eliminating the need for a trimming operation such as is commonly required. It is to be noted that the back and end walls are substantially vertical, but the front wall flares outwardly, as most clearly shown in Figure 3, to form a lip to facilitate the pouring of metal into the mold when the latter contains the lugs of a battery element. The end walls I2 and I3 preferably are higher than the front and back walls to facilitate entrance of the element into the mold.

A downwardly depending tubular extension I6 is formed integrally with the floor and walls of the mold outwardly of the rear wall M. The bore I! through said tubular extension tapers slightly toward the bottom for about half of its length and the terminal post of the element, which is cast integrally withthe strap,-is formed in thetapered portion. The lower portion of the bore is of uniform diameter and accommodates a vertically slidable ejecting pin [8 which may be actuated upwardly by suitable mechanism, not shown, to eject finished castings from the mold. The upper surface of the ejecting pin also functions as a bottom for the extension [6 during the casting of a strap. The mold may be supported by the extension l6 and the exterior of a portion thereof may be made rectangular, as indicated at l9, Figure 2, to facilitate engagement by suitable support means.

A longitudinally extending heat transfer member depends from the underside of the floor ll. Said member preferably has a series of interruptions in the form of transverse slits 2| (Figure 2) cut therethroughto prevent or limit warping or other distortions due to rapid thermal changes to which the mold is subjected. The heat transfer member may expand or contract a greater amount than the remainder of the mold and such additional expansion and contraction is taken up within the interruptions. Heating elements 22, preferably of the inductive type, are supported in proximity to the heat transfer member and floor by any appropriate means not shown.

The upper surface of the mold floor has interruptions to increase the area of contact between the material of the mold and metal poured into the mold, and thus to furnish better heat transfer. The interruptions are preferably in the form of longitudinal ribs 23 formed integrally with the mold fioor.

The floor of the mold contains a pair of parallel longitudinal ducts 24 (Figure 3) for flow of water or other coolant therethrough for cooling the mold. The ducts are preferably located out of the most direct path between the heat transfer member and the upper surface of the mold floor in order to provide a straight and direct metal path for conducting heat from said member to the lug tips and molten metal in the mold. If the ducts were in the heat conducting path, they would tend to act as a barrier against rapid flow of heat.

The .mold floor has integral extensions .25 at its opposite ends through whichthe ducts 24 pass. The extension at the right is shown in Figures 1 and 2 and the extension at the left, although not shown, is similarly arranged. ,Suitable hollow fittings 26 and 2'! are fitted over and receive the extensions and are brazed or welded thereto for connecting a coolant inlet tube 29 and a discharge tube 28 respectively to the ducts, the tubes extending a short distance into the fittings and being brazed or welded thereto.

When the coolant is applied to the mold, it first chills the inlet tube 29 and the inlet fitting 2! with the result that these elements contract faster than the remainder of the mold. Later, during-the coolingoperation, the discharge fitting is cooled more rapidly than the mold body and therefore contracts at a greater rate. By having the fitting outside'of and surrounding the portion of the mold to which it is attached, such contraction merely shrinks the fittings into tighter engagement with the mold, rather than tending to weaken the connections. This arrangement thus insures the permanence of the connections as well as providing neat and conveniently constructed joining means for the inlet and discharge tubes.

Preferably extensions 30 and'3l are welded to the-.heat transfer member; underneath: the-fitheat longitudinally. There is a greater tendency for the ends of the mold to cool than for the center to cool, since the ends are more exposed. By providing heat transfer members only in the region of the ends, the ends are heated to a greater extent than the mid-portion and thus the tendency of the ends to cool is compensated.

The operation of a mold, constructed as described, is as follows:

Terminal lugs P of assemblages of .storage battery plates are placed in the mold cavity. Ordinarily the lugs of the positive plates and those of the negative plates of an assembled storage battery element are placed in a pair of opposed molds l0 suitably supported and arranged with the front walls l5 facing outwardly. The elements are supported by the tips of the lugs resting on the ribs 23. Molten metal to form an integral strap and connecting post is poured into the mold at the front wall l5, preferably by a pouring device that extends the length of the mold to facilitate distribution of the metal. The molten metal is at a temperature insufiicient to melt the lugs.

Heat is applied to the mold through the heating coil 22, preferably an instant before the metal is poured into the mold in order to remove the chill from the mold that resulted from cooling during a previous cycle of operation. The heat transfer member 20, fioor H and ribs 23 are heated and in turn conduct heat to the molten metal and lug tips. The application of heat is continued and the lug tips are thereby melted and fused with the molten metal that forms the strap. The heat is promptly cut off, preferably before it has had sufficient duration to melt the lugs except at the tips.

Immediately after the .heat is cut off, coolant is passed through the duct 24. The flow of coolant quickly solidifies the strap casting and lugs. The tips ofthe lugs are welded to the casting and the remainder of the lengths of the lugs are mechanicall gripped by the casting, since the latter shrinks on cooling, being at a higher temperature than the lugs.

The ejecting mechanism I8 then operates to eject the finished casting from the mold.

It is apparent that numerous mechanical arrangements and circuits could be employed for introducing the molten metal to the molds, energizing the heating coils, introducing coolant to the duct, and operating the ejecting mechanism. However, the preferred apparatus for performing these various functions is that shown in my copending application Serial .No. 708,672, hereinbefore referred to, and-the mold of the present invention .is'preferably employed as an element in said apparatus:

I have shown and described certain embodiments of the present invention, but it is apparent that the device could be further modified without departing from the spirit of the invention. Therefore, I do. not wish to be'limited to the disclosure set forth, but only by the scope of the appended claims.

I claim:

1. A mold for casting straps on the plate lugs of assembled storage battery elements comprising an integral body member having side walls and a floor forming an open cavity mold adapted to receive said plate lugs and molten metal to form a strap directly on said plate lugs, said floor having at least one rib projecting from its upper surface into the mold cavity to increase the area and depth of contact between the mold and the casting metal received therein, a heat conducting metal extension integrally formed on the under surface of said floor and projecting outwardly therefrom, said metal extension being longitudinally substantially coextensive with said body member and laterally substantially corresponding with the dimension of said plate lugs lengthwise of said plates, and heating coil associated in inductive relation with said extension for generating heat therein.

2. A mold for casting straps on the plate lugs of assembled storage battery elements comprising an integral body member having side walls and a floor forming an open cavity mold adapted to receive said plate lugs and molten metal to form a strap directly on said plate lugs, said floor having a plurality of longitudinally extending ribs projecting from its upper surface into the mold cavity to increase the area and depth of contact between the mold and the casting metal received therein, a heat conducting metal extension integrally formed on the under surface of said floor and projecting outwardly therefrom, said metal extension being longitudinally substantially coextensive with said body member and laterally substantially corresponding with the dimension of said plate lugs lengthwise of said plates, a heating coil associated in inductive relation with said extension for rapidly generating heat therein, at least one duct extending longitudinally through said floor for the flow of coolant to rapidly cool said extension and said mold after heating, and at least one transverse opening in said extension to limit warping of said mold during the changes in temperature produced by the rapid heating and cooling there- 01'.

3. A mold for casting straps on the plate lugs of assembled storage battery elements comprising an integral body member having side walls and a floor'forming an open cavity mold adapted to receive said plate lugs and molten metal to form a strap on said plate lugs, a plurality of ribs projecting from the upper surface of said floor into said mold cavity to increase the area and depth of contact between the mold and the casting metal received therein, a heat conducting metal extension depending from the under surface of said floor and integrally formed therewith, a heating coil associated in inductive relation with said extension for rapidly generating heat therein, said extension lying along the longitudinal axis of said floor and having a gap under the mid-portion of said floor whereb on heating of said extension a greater amount of heat is applied to the end-portions of said mold fioor and said integral ribs than is applied to the midportions thereof.

CHARLES DOUGLAS GALLOWAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 394,461 Copeland 1 Dec. 11, 1888 958,892 Riddell May 24, 1910 1,378,984 Soss May 24, 1921 1,611,911 Hazelett Dec. 28, 1926 1,615,086 Junker Jan. 18, 1927 1,811,292 Barhofi' June 23, 1931 1,959,484 Lund May 22, 1934 2,182,402 Lester Dec. 5, 1939 2,219,868 Dostal Oct. 29, 1940 2,454,051 Galloway Nov. 16, 1948

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