US1795065A - Ingot mold - Google Patents

Description

Patented M 3,1931

UNITED sTATEs PATENT. OFFICE EDWARD R. WILLIAMS, 0] LATROBE, PENNSYLVANIA, ASSIGNOR TO VULCAN MOLD AND IRON COMPANY, OF LA'IROBE, PENNSYLVfZNIA, A CORPORATION OF PENN- SYLVANIA meow MOLD 1T0.- Drawing.

Iron ingot molds made by the direct metal process or with iron as it comes in the molten state from the blast furnace have a number of disadvantages. The temperature ofthe molten iron from the time it leaves the blast furnace untilit is poured into the mold he'- comes lower which reduces by precipitation the amount of carbon held in solution. This precipitated carbon or kish promotes porosity in the mold casting, particularl at its top. The temperature of the molten lIOIl being comparatively low reduces its fluidity, and unless the mold wall is fairly thick, as

' four inches or more, the metal tends to coldheating and cooling in use. Lar e graphite flakes render the metal relative y weak as comparedwith metal having small graphite flakes.

By melting pig iron in a cupola or a similar re-melting' medium better physical properties are produced than by the direct metal process. The high melting temperature we vailing in the cupola gives the metal better fluidity than the direct metal from a blast furnace has and therefore gives the casting a smoother surface. The cupola method of producing cast iron affords a better control of the melting temperature than is obtainable by the direct metal method, owing to the ease of manipulating the coke ratio in a short eriod of time. Also the cupola method gives better control of the composition of the iron as to the percentage of silicon, phosphorus, carbon and manganese therein. Cupola metal as generally made has a serious disadvantage, particularly when cast as ingot molds of large size. During the melting operation sulphur is absorbed from the fuel to the extent of from .02% to 05%, which pro- Application filed June 22, 1929. Serial No. 373,058.

duces sulphur in the resultant casting of over .05% and sometimes ashigh as 15%, depending on conditions. High sulphur content renders the ingot molds red-short which, if the mold wall has insuflicient structural strength, allows it to crack. Suflicient strucv tural strength is produced only by having the mold wall thicker than is necessary to properly absorb the heat. from the solidifying lngot.

I have discovered that ingot molds made of cupola iron with the sulphur under .05% are highly resistant to cracking even when they have a relatively large sectional area. The low sulphur cupola iron ingot molds therefore fail only by the normal process of growth and tire cracking.

In the preferable practice of my invention I employ a cupola in which the metal charges are melted. A suitable de-sulphurizer such as soda ash is added to the molten metal 1n suflicient quantity to reduce the sulphur content below 05%. The de-sul hurized molten metal is then poured into t e ingot mold in the usual manner.

I claim:

An ingot mold made of cupola cast iron which contains sulphur under .05% and has high resistance to cracking through sudden expansion.

In testimony whereof, I hereunto afiix my signature. Y EDWARD R. WILLIAMS.