US1156093A - White-metal casting and the method of making same. - Google Patents

Description

CHARLES PACK, OF NEW YORK, N. Y., ASSIGNOR TO DOEHLER DIE CASTIN COMPANY,

. v A CORPORATION OF NEW YORK.

WHITE-METAL CASTING AND THE METHOD OF MAKING SAME.-

1,156,993. No Drawing.

To all w/wm it may concern Be it known that I, CHARLES PACK, a citizen of the United States, residing at the borough of Brooklyn, city of New York,

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county of Kings, and State of New York, have invented certain new and useful Improvements in White-Metal Castings and the Method of Making Same, of which the following is a specification.

The invention relates to a white metal casting and the method by which said casting is made, and more particularly to a cast .ing made from an aluminum alloy.

Heretofore in the art of making castings of aluminum alloys by. what is known as the pressure die casting process, great difiiculty has been encountered due in partto the high fusing point of'aluminum and of the ordinary commercial aluminum alloys; in part to the difficulties in producing a machinecapable of casting such alloys, and in part due to the high shrinkage of the alloy in the molds which resulted in the formation of superficial or deep-seated cracks in the finished castings.

I have discovered that a tough, sound casting of an aluminum alloy maybe made in metal molds by bringing the solidifying point nearer the eutectic point of the alloy through an increase in the percentage of copper over that which is generally recognized as being the highest percentage which can be successfully used in commercial castings, and by maintaining conditions throughout the casting process which will result in the chilling of the casting. I have discovered that a casting made in accordance with my improved process or method has sufficiently high tensile strength; is free from cracks, and has a hard chilled superficial stratum imparting to the casting good wearing properties.

The invention consists primarily in a method of making finished white metal castings consisting in alloying from 80 to 91 per cent. of aluminum with from 20 to 9 per cent. of copper and delivering the molten alloy to a metallic mold maintained at a temperature below the fusing point of the alloy; and in the casting produced by this process; all as hereinafter set forth and described and more particularly pointed out Spe'cification of Letters Patent, Patented Oct, 12, 1915, Application filed June 19, 1914. Serial No; $46,197.

tions of these metals varying accordingto the percentage of copper with castings.

larger in dimensions and more complicated in their configuration. The alloy containing the highest percentage of copper which I have-been able to use successfully has been I composed of 20 parts of copper and 80 parts of aluminum.

The metal alloys which I employ are therefore richer. in copper than the alloy which is ordinarily recognized as being the the size and character of the casting to be i most desirable for commercial castings, and while theoretically an aluminum alloy containing from 20 to 9 per cent. of copper would be too brittle for commercial castings,

nevertheless, I have found that if this alloy is cast under certain conditions, the commercial castings not only are lacking in that brittleness which would make them undesirable, if cast in sand, but-the quality of the castings is much superior v to castings of aluminum alloys containing a lower percentage of co dper. This I attribute to the fact that the solidifying point of the alloy is brought nearer the eutectic point by the use of a higher percentage of copper thus permitting casting at lower temperatures and reducing the shrinkage of the casting in the mold. Furthermore, by casting alloys composed of copper and aluminum, in which the percentage of the aluminum will range from 80 to 91 per cent. in metal molds maintained at a temperature below the eutectic point of the alloy, a chilled casting is secured and by reason of the reduced shrinkage of the metal, this casting is sound or without cracks. Furthermore, a rapid chillsolidification shrinkage so as to avoid excessive contraction of the" metal while in the in my method are readily handled in charging the mold, and that they flow readily in pouring. These conditions practically adapt an alloy of this characterto the production of finished castings or castings made to a fixed dimension or size. As l have heretofore stated in larger and more complicated castings, I increase the proportion of copper.

Inasmuch as by my experiments I have determined that the percentage of copper may be varied from 9 to 20 per cent., it is not my intention to limit the invention of any specific percentage of. copper, except that no less than 9 per cent. of copper shall be used and no more than 20 per cent, my invention contemplating the use of copper in proportions between these two limits.

Having described the invention what I claim as new and desire to have protected bv Letters Patent is 1. The herein described method of producing finished white metal castings consist-v ing in alloying from S0 to 91 parts of aluminum with from 20 to 9 parts of copper, and pouring the molten alloy in a metallic mold maintained at a temperature below the fusmes es ing point of the alloy, whereby the surface of the casting is chilled, and drawing the casting from the mold immediately following the solidification shrinkage whereby excessive contraction of the casting in the mold 1 is avoided.

2. Ihe herein described method of producing finished white metal castings consisting in alloying from 80 to 91 parts of aluminum drawing the casting from the mold immediately following the solidification shrinkage whereby excessive contraction of the casting.

in the mold is avoided.

3. A finished, pressure die cast white metal casting composed of an alloy of from 80 to 91 parts of aluminum and from 20 to 9 parts of copper having a chilled outer stratum or surface.

In witness whereof I hereunto afiix my signature in the presence of two subscribing witnesses this 10th day of June, 1914.

CHARLES PACK.

Witnesses C; CLAmse FRANCK, JUDITH PARDEE.