Ingot mold

Feb. 23, 1937.

R. H. STEVENS

INGOT MOLD

Filed Feb. 7, 1935

2,071,906

Sheets-Sheet 1

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Feb. 23, 1937. r. h. stevens 2,071,906

INGOT MOLD Filed Feb. 7, 1935 2 Sheets-Sheet 2

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Patented Feb. 23, 1937

2,071,906

UNITED STATES PATENT OFFICE

2,071,90«

INGOT MOLD

Richard H. Stevens, Baltimore, Md., assignor to Bethlehem Steel Company, a corporation of Pennsylvania

Application February 7,1935, Serial No. 5,348

Claims. (Cl. 22—139)

This invention relates to improvements in ingot molds and ingots and particularly to improvements in the contour of the horizontal cross section of the vertically extended mold chamber 5 and of the ingot formed therein. The improved contour of the chamber of my ingot mold is obtained through the use of a new type of corrugation therein.

Corrugated chamber walls in ingot molds are 10 old, having been employed in casting for many years. As is well known in the art, the object of corrugations in the mold chamber is to increase the perimeter of the ingot cast therein, as the rate of cooling and solidification is to a 15 great extent proportional to the surface area as compared to the cross-sectional area of the ingot. Heretofore, however, in casting ingots of the slab type in molds having corrugations of uniform size and pitch, great difficulty has been ex20 perienced, due to the ingot, during shrinkage, becoming caught at the corrugations, which caused a tendency on the part of the ingot to pull .on the flat side of the mold and caused the mold to try to bulge. This produced a strain on the mold >5 and invariably, after a number of castings, resulted in the cracking of the mold. The pulling also produced 'a strain on the ingot, causing it also to crack.

It is the object of my present invention to pro30 vide an ingot mold with corrugated chamber walls which embody all the well known advantages thereof and at the same time permit freer shrinkage of the ingot by allowing it to slide freely along the chamber walls without sticking ₃- or catching at the corrugations.

To accomplish this purpose I provide the side walls of the ingot-forming chamber with a plurality of corrugations of varying pitch which decrease successively in pitch from the end portions ₄₀ of the side walls toward the center thereof. These corrugations comprise an arcuate portion and a straight portion. It is through varying the length of the straight portions that the variance in the pitch of the corrugations is ob45 tained, as the radii of the arcuate portions are uniform. I preferably provide the end walls of the chamber with corrugations which are of a uniform pitch. The general contour of the whole chamber is so designed as to produce an ingot 50 having walls which are of a generally convex horizontal contour. In addition to the advantage before mentioned, an ingot cast in this mold, due to the convexity of its walls, rolls more quickly and with little or no fishtailing.

The novel features of my invention will be more fully understood from the following description and claims taken with the drawings, in which—

Fig. 1 is a top plan view of an ingot mold constructed in accordance with my invention. 5

Fig. 2 is a side elevation of the ingot mold shown in Fig. 1.

Fig. 3 is a bottom plan view of the ingot mold shown in Fig. 2.

Fig. 4 is a diagrammatic view of one quarter of 10 the top and bottom contours of the mold chamber, and of the contour of an ingot after cooling therein, the latter being indicated by the broken • line.

Figs. 1, 2 and 3 illustrate an ingot mold 16 of ]5 the big-end-down type and of a substantially rectangular or slab type contour. The molding or ingot forming chamber 17, as shown, is slightly concave on all four sides. The side walls 18 of the chamber 17 have corrugations 19, 20, 21, ₂o 22, 23, 24, which vary in size and pitch from the end portions of the side walls 18 toward the center thereof, and the end walls 25 have corrugations 26, 27, 28, 29, all of which will be more clearly observed by reference to Fig. 4. All 25 of the corrugations of the side walls and end walls are connected by outwardly arched portions 30. The end walls 25 are connected to the side walls 18 by outwardly arched corner salients 31. 3θ

The three center corrugations 20, 19 and 20 of the side walls are shown as being of a regular arcuate contour, while all the remaining side wall corrugations comprise arcuate portions 32 and straight portions 33 (Fig. 4). The radii of 35 the arcuate portions 32 are of uniform length, while the straight portions 33 become successively smaller from the ends of the side walls 18 toward the center thereof. By thus varying the length of the straight portions 33 which thereby 40 varies the pitch of the individual corrugations I obtain a mold which permits the cooling ingot to shrink freely and to contract horizontally in the direction of its major cross-section without sticking or catching at the corrugations as illustrated 45 in Fig. 4.

For purposes of illustration I shall now give the details of the various parts embodied in an ingot mold of the big-end-down type having a mold chamber with a bottom dimension of 50 32 x 50 inches, a top dimension of 30½ x 48½ inches, and a length of 84 inches. The thickness of the mold walls is substantially the same at any point in a common horizontal plane, the walls increasing uniformly in thickness from se

3,071,906 the upper to the lower end of the mold. In a mold of the size illustrated the thickness of the walls at their thickest point is:

Side walls, 4 inches at top, 8 inches at bottom. 5 End walls, 3% inches at top, 7½ inches at bottom.

The measurements of the corrugations, taken between the apexes of the outwardly-arched connecting portions 30, are as follows:

The center corrugation 19 is 3½ inches long, and its arcuate portion is described by a radius of 2% inches.

The corrugations 20 are 3% inches long, and their arcuate portions are described by radii of 16 2% inches.

The remaining corrugations 21, 22, 23, 24 are respectively 3¾. 4, 4¼ and 4% inches long. The arcuate portions 32 are all described by radii of 3 inches. Hie straight portions 33 vary in length, 20 becoming shorter in the direction of the center of the mold.

The corrugations 20, 27, 20, 29 of the end walls are all 3¾ inches long, while the arcuate portions of corrugations 20, 27, 20 are all described by 25 uniform radii of 4A inches, and the arcuate portion of the corrugation 20 is described by a radius of 6 inches.

Hie outwardly arched connecting portions 30 are all described by uniform radii of % inch.

The outwardly arched comer portions 31 are described by radii of 1 inch.

Hie side walls 10 taper Inwardly 1 inch from the center to the outer end thereof.

The corrugations 10, 20, 21, 22 and 23 of the 35 side walls and corrugations 26, 27 and 28 of the end walls are all parallel from the upper to the lower end of the mold, while the corrugations 24 of the side wall and 20 of the end wall increase in size toward the lower end of the mold to com40 pensate for and take up the increase in size of the chamber at the lower end.

Molds constructed in accordance with my invention have proved most successful, having substantially if not entirely eliminated most of the 45 defects occurring in molds of the slab type heretofore employed. In actual use they have produced a better ingot with fewer surface defects, and the molds themselves have been found to last many times longer than those heretofore used, due to the elimination of strain on the walls thereof heretofore occurring during the cooling of the ingot on account of the ingot catching or sticking at the corrugations. 5

Although I have described and Illustrated my invention in considerable detail, I do not wish to be limited to the exact and specific details thereof, as shown and described, as it will be obvious that numerous variations thereof might io be constructed without departing from the scope and spirit of my invention.