US202530A - Improvement in converting non-chilling - Google Patents

Description

UNITED STATES P T NT OFFICE,

SAMUEL A. FORD, OF ALLEGHENY, PENNSYLVANIA.

INlPROVEMENT lN CONVERTING NON-CHILLlNGlRON lNTO CHlLLlNG-IRON.

Specification forming part of Letters Patent No. 202,530, dated April 16, 1878; application filed December 26, 1877;

To all whom it may concern:

Be it known that I, SAMUEL A. FoRD, of Allegheny, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Process of Treating Non-Chilling Irons and Light Chilling-Irons; and 1 do hereby declare the following to be a full, clear, and exact description thereof.

My invention relates to the conversion of non-chilling into chilling irons; and consists in submitting a charge of melted non-chilling iron to the action of an air-blast for a few moments only--say from one to six minutesthe air-blast being out off either just before or just after the appearance of the carbon-flame, according to the depth of chill required in the product.

In the manufacture of pig metal two processes are commonly followed in the blast-furnace-the one known as the cold-blast and the other as the hot-blast process, and the products are known in the trade as hot-blast iron and cold-blast iron.

The cold-blast iron is low in silicon, and is especially adapted for chill-castings, &c. but its production is limited by the nature of the ore required and the small size of furnaces it is practicable to work to advantage. The hotblast iron, on the contrary, can be produced in any quantities desired, as there is practically no limitation either in quality of ore or size of furnace; but the hot-blast iron is high in silicon, and, though well adapted for the Bessemer process, is a non-chillin g iron, totally unfit for the manufacture of chill-castings.

five to forty dollars per ton, while the hot-blast,

non-chilling iron can be procured at from seventeen to twenty dollars per ton.

The main object of the present invention is to utilize the comparatively cheap hot-blast iron in the manufacture of chill-rolls, car-wheels, chill plows, malleable castings, and under all similar-circumstances where the more expensive coal-blast charcoal chilling-irons are now necessarily used; but the process is equally applicable to the treatment of light chilling-irons where it is desirable to increase the depth of the chill.

I will now proceed to describe my invention, so that others skilled in the art to which it appertains may apply the same.

Having melted the desired quantity of pig iron in a cupola or other suitable furnace, or, if convenient, taking such a charge of molten iron directly from the blast-furnace, I introduce it into a furnace, where it can be treated by an air-blast. For this purpose I prefer a Bessemer converter, wherein I submit the molten metal to the action of the air-blast for a few moments, shutting off the blast either just before or just after the appearance of the carbon-flame,varyin g the time slightly, according to the quality of the metal and the depth of chill required.

If only a small amount of chill is required, I out off the blast just before the carbon of the metal begins to oxidize, which point can be determined by the increased strength of the flame with absence of the brilliant yellow color. When a deep chill is desired, the blow. is continued until the brilliant yellow due to the oxidation of the carbon appears in the flame; but it is cut off before the disappearance of the silicon-flame, or that flame which is seen at the commencement of the blow. The blow, having been carried to the extent indicated according to the desired chill, is then cut off, and the metal poured into a ladle or other suitable vessel, and thence directly into chill-molds, or into sand-molds for the formation of castings, or into pigs, which can be subsequently remelted in a cupola or other suitable furnace for the manufacture of chillcastings. The whole process will usually occupy a space of time varying from one to five min utes; but under some circumstances it may be necessary to continue the blow somewhat longer, especially if the hot-blast iron composing the charge be extremely high in silicon.

The metal thus treated has not lost the qualities of cast-iron, but will be found to have acquired the properties of the cold-blast charcoal chilling-irons. It will be found to be very hard, of great strength, and, if cast in a chill-mold, will when broken, show long white crystals tapering into gray metal. When cast in sand-molds, if the chilling property is not too great, it will exhibit a dark-gray color andclose grain resembling cold -blast charcoaliron but if the chilling property is very high, then the edges of the casting will be slightly chilled and the center of the piece of lightgray color. 7

Having thus described my invention, What I claim, and desire to secure by Letters Patent, is-- The method herein described for converting non-chilling irons into chilling-irons, and for increasing the chilling capacity in light chilling-iron, which consists in subjecting a charge of the melted metalto the action of an airblast for a limited time only, the blow being cut off either immediately before or immediately after the appearance of the carbon-flame, and before the disappearance of the siliconflame, substantially as specified.

In testimony whereof 1, the said SAMUEL A. FORD, have hereunto set my hand.

SAMUEL A. Fonn.

Witnesses:

JAMES I. KAY, F. W. BITTER, Jr.