US735303A - Method of making metal castings. - Google Patents

Description

PATENTED AUG. 4, 1903.

A. SAUVEUR. METHOD OF MAKING METAL GASIINGS.

APPLIOATION FILED JULY 10, 1902.

N0 MODEL.

THE uokms FETERS 0 morournafwumwcmu, n cy a No. 735,303.

Patented August 4, 1903.

ATENT FFICE ALBERT SAUVEUR, OF CAMBRIDGE, MASSACHUSETTS.

METHOD OF MAKING METAL CASTINGS.

srnolrloA'noiv forming part of Letters Patent No. 735,303, dated August 4., 1903. Application filed July 10, 1902. Serial No. 115,035. (No model.)

a specification tending down into the ingot.

My invention relates to the manufacture of metal castings, and is especially adapted to the manufacture of steel castings, whether of simple ingots which are to be subjected to further mechanical manipulation or of more complex and finished castings for immediate commercial use. In the description which here follows for the most part I confine myself for the purposes of simplicity and brevity to a description of my invention as applied to the casting of steel ingots.

The common practice in making steel ingots has been to pour the molten metal from a large receiving vessel, which is technically called the ladle, into a number of thickwalled cast-iron molds, enough being poured into each mold to fill it up to a prescribed level. Here the metal is allowed to cool, and

when withdrawn from the molds the blocks constitute what are technically termed steel ingots. The cast-iron molds in which the ingots are formed by reason of their high conductivity and large specific capacity for heat draw oi the heat of the molten metal with great rapidity, so that a solid,crust is formed at the sides of the ingot almost immediately. The solidificationthen proceeds inward from the sides and upward from the bottom of the mold. When the mold has been filled to the prescribed depth, the upper surface of the ingot also begins to cool and presently solidifies, forming a bridge over the remaining molten metal within, so that as the cooling and solidification proceeds upward Within the mass of the ingot there is no opportunity for the top layer of metal to collapse downward, because it has already solidified, and consequently a cavity necessarily forms within the ingot a little below the top and ex- This is illustrated in Figure 1 of the drawings, hereto annexed, wherein-= i G is the cast-iron mold, shown in cross-sew -t on.

A is the ingot. b is a line showing approximately the curve of progression of solidification within the ingot.

0 is the top crust or bridge, and d the cavity formed by the cooling and contraction of the metal. This cavity is technically termed a n p p I Smaller cavities and faults, such as blow- .holes, are also formed in the casting in the neighborhood'of the pipe, and, moreover, the castings suffer from the defect known as segregation, which consists inthe collection of impurities in the region surrounding the pipe.

The phenomenon above described is true not only of ingots, but of any steel casting, and therefore it follows that under the present practice some portion of any steel casting is physically unsound. Steel ingots after their formation in the molds are shaped and variously converted into finished articles by means of rolls, hammers, presses, and other machinery known to the modern metalworker; but owing to the presence of the pipe and associated causes of impurity and unsoundness in the ingot the manufacturer is obligedto discard a certain portionof' the metal from the top of each ingot; otherwise the unsound portion of the ingot would carry its imperfection into the finished articles into which the ingot is converted. Recognizing the inevitable imperfection in any steel casting made according to modern practice, manufacturers in making finished castings of steel prevent the presence of a pipe in the finished casting by making an additional cavity on the top of the mold, into which is poured an extra amount of metal, in which the pipe forms, leaving the casting proper free from the defect. This extra amount of metal is usually termed a sinking head,- and the sinking heads are removed from the castings after the same have solidified and cooled. By the practice of my invention the loss occasionedby discarding the piped parts of ingots or the sinking heads of castings will be avoided in great part, as will presently be understood.

My invention consists of the method of casting metal by which the formation of the cavity or pipe is entirely prevented or greatly M which fills the next mold, and so on.

reduced, according to the degree to which my method is practiced. I

Fig. 2 of the drawings annexed hereto illustrates an apparatus by which my method is practiced, showing in vertical cross-section several molds of the simple form adapted to casting of steel ingots. The molds C are placed in series, so that the top level of metal in one mold is above that in the mold next below it in the series. These molds O are placed upon a platform S, which may be movable or not'to suit the convenience of the manufacturer, and each mold is provided with the lip D, which extends over the edge of the mold next below it in series. From a ladle, of which the lip E is shown in the drawings, the metal M is poured in molten condition into the-highest mold of the series, and when this mold is filled the metal flows over the lip Din the stream M, filling the next mold in series and thence forming a stream The result of the above arrangement of the molds and the method of filling one mold by an overflow from the next above it by series is that the metal at the top of each ingot A, which under the old practice solidified and formed a crust or bridge before the metal in the body of the ingot below it had time entirely to solidify, is retained in a molten condition by the passage of the stream of metal across it, so that while the second mold in series is being filled the ingot in the first mold has time to solidify up to the very top. Consequently when the last mold in the series is filled and the metal is allowed to cool in this and all the others in all except the last mold the top will be the last portion to solidify and will then solidify in intimate solid integrity with the rest of the metal in the ingot.

I have only shown three molds to illustrate my method; but it is obvious that the series can be prolonged so as to contain very many more than three molds, this, however, without effecting any alteration in the principle of the method or any substantial change in its practice.

The gist of the invention is that I cause the top of each ingot to remain heated, and therefore liquid, while the metal below solidifies, so that the top solidifies last, thus removing all possibility of the formation of cavities or pipes. If ten molds are used in series and the pipe is confined to the last one, then the amount of loss caused by the piping will be reduced to ten per cent. of what it is underthe present process.

What I claim, and desire to secure by Letters Patent, is-

1. The method of casting metal which consists in filling a mold with molten metal and in retarding the cooling of the upper portion of the mass within the mold until the lower ALBERT SAUVEUR.

Witnesses:

JOSEPH T. BRENNAN, GRACE E. GiBBoNs.

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