US1555626A - Ingot mold - Google Patents

Description

Sept. 29, 1925. 1,555,626

F. A. BLACK INGO'I MOLD Filed June 28, 1922 myzmok A FREQER/CKH. ELHCK ATTORNEYS Patented Sept. 29, 1925.

Nrr' srATEs APPLEIBY BLACK, OF BRIDGEPORT, CONNECTICUT.

moor MOLD.

Application filed June 28, 1922. Serial No. 571,444.

To all whom it may concern:

Be it known that I, FREDERICK APPLEBY BLACK, a citizen of the United States of America, residing in Bridgeport, in the county of Fairfield and State of Connecticut, have invented certain new and useful Improvements in Ingot Molds, of which the following is a specification.

My invention relates to ingot molds, and particularly to the configuration of the walls of the, mold body, the objectof my invention being to so construct the walls of the mold as to progressively and uniformly chill the metal in the mold chamber to the center of the ingot, and thus to avoid segregation, and to prevent the formation of blow holes, gas pockets, etc.

The invention is susceptible of embodiment in molds of various types and shapes, and I have illustrated only certain of the latter in the accompanying drawings, in which- Fig. 1 is a broken side elevation of an ingot mold, more orless diagrammatically shown, and in which my invention is illustratively embodied;

Fig. 2 is a section on the line 2-2, Fig. 1;

Figs. 3, 4c, 5 and 6 are plan views of molds for ingots of different shapes, and in each of which my invention is illustratively em bodied.

Various molds have been hitherto em? view to the eliminationof gas pockets, blow holes, piping, etc. For the most part the attempts to overcome these difiiculties have been in the direction of collapsible molds,

special mold caps and bottoms, inclination of the mold walls, etc. So far as I have been able to ascertain, little or no attention has been paid to the relation of the thickness and shape of the mold walls to the size and shape of the mold chamber. The common practice is to make the Wall of a mold of nniforrhgthiclmess at all points around the entire mold at any given cross section, this thickness being apparently chosen with a view to mechanical strength rather than with a View to the chilling effect of the mold Wall upon the ingot metal. Thus, molds with-walls of 4" thickness are commonly employed for the casting of ingots varying in diameter from 10 to As an incident to this construction, the outer face of the mold wall is substantially parallel to a mold having ployed for the casting of steel ingots with athe inner face thereof. Radiation fins have been somet1mes provided on the exterior of the mold; but these fins have been applied in a somewhat hit-or-miss fashion, to add to the radiating capacity of the wall and without any appreciation of the principles upon which my invention is based, nor have such fins accomplished the results which are sethat in ordinary molds now commonly used,

the hot metal is progressively chilled inward to an extent corresponding substantially to the thickness of the mold wall, followedby a much slower chilling in the middlc of the mold chamber. In other words, a heat interchange occurs between the ingot metal and the mold walls siifiicient to freeze the metal inwardly to an extent corresponding to the thickness of the mold walls, but not suflicient to freeze the metal in the central area of the chamber when the thickness of the mold wall is not equal to at least half the diameter of the chamber. Thus, the metal for an ingot of 12" diameter cast in walls 4- thick is progressively chilled one-thirdof the way inward from several sides of. the mold, while the central area of the ingot chills slowly and remains in objectionably fluid condition with resulting segregation through the absorption of carbon from the solidified outer metal by the still fluid and hot central portion of'the charge, and the formation of gas packets, and blow holes. Moreover, even if an 8 ingot wereto be cast in a mold with 4" wall, the construction of the latter is still objectionable since at the corner of the mold excess heat exchange takes place, and the chilling of the metal is more rapid at the corners than at the sides, so that the freeze does not progress uniformly in all directions toward the mold center.

The ideal mold, according to my, invention, is one in which the size and shape of the mold walls are complementary to the size and shape of the mold chamber, and preferably symmetrical with relation to the center of the latter. In other words, the wall areas at any given cross section through the mold should be co-extensive with and complementary to a like area of the mold chamber extending to the center of the latter, so that the'sum of the cross sectional wall areas should equal the area of the mold' chamber in the plane of the section. Exact construction of the mold in accordance with this principle is impracticable by reason of the structural weakness of the mold wall at the joint between adjacent heat absorbing areas thereof; but the configuration of the mold should approach the theoretical as closely as practically possible.

The principle may be embodied in molds of any usual shape, and in fact makes possible the casting of ingots in shapes hitherto considered impractical.

The chamber of the mold shown in Figs. 1 and.2 is substantially square, with roundedcorners. The four walls A, B, C, D of the mold are substantially triangular in cross section, and substantially correspond in area to the complementary triangular areas a, b, c, d having their apices in register with the central point X of the mold chamber. The correspondence is not exact by reason of the fact that the corners of the chamber are rounded, and the further fact that the structural strength of the mold necessitates webs E, uniting the bases of the triangular sides. To prevent too rapid heat exchange at the corners of the ingot, and to render the chilling of theingot as uniform as possible from all exterior points toward the center of the ingot, the sides of the walls AD are slightly reduced, this reduction being compensated for as closely as possible by the metal in the tie web E. It will be noted, however, that the opposed faces of adjacent areas are so inclined with relation to each other that they intersect substantially at the inner'face of the mold wall-and furthermore, that on inward development of the areas into the mold chamber, these faces substantially coincide.

The same idea may be carried out in an oblong mold, as shown in Fig. 3. In this construction the end walls B and D correspond substantially to the similar walls of the square mold in Fig. 2. The walls G and H, however, While having the same lateral inclination of their sides, are truncated to correspond to the truncated areas 9 and h of the mold chamber.

When a cylindrical ingot is to be cast, a construction such as indicated in Fig. 4 is employed, inwhich the wall of the mold presents, in plan. a star shape. The several rays I correspond in area to the complemene tary inwardly produced areas 'of the mold chamber, and meet at the center point X of the mold. As in the previous constructions, the heat absorbing wall sections I are necesshown in Fig. 6, in which the wall sections 0 correspond to the complementary areas 0 of the mold chamber. In this construction the tie webs P are concave instead of convex, as in Figs. 4 and 5, but serve the same function. It is obvious that the same princi p'le may be applied to molds of, other shapes while obtaining the same advantage.

It will of course be understood that the mold shown in Fig. 1 is more or less diagrammatic, and that I have not illustrated any particular bottom and top constructions which may be employed to advantage in connection with the. present invention to further improve the ingot particularly with respect to piping. These features are not illustrated since the present invention is confined to the body of the mold, which is sufficiently shown to illustrate the principle underlying the present invention.

I have found that ingots cast in molds built according to the present principle, progressively chill or freeze the ingot to its center point. \Vhile the solidification of the ingot as a whole takes place more rapidly than in molds of the type now commonly employed, the center heat of the ingot prevents the outer shell from solidifying too quickly, and thus avoids surface troubles. I have further found that the slag and gas riseto the top of the ingot, and that the troubles of segregation, blow holes, etc, are minimized, if not completely eliminated, and no deearbonization takes place in the surface, or elsewhere in the ingot. The grain of the latter is very fine and granular, perfectly homogeneous, and without gas pockets and blow holes. If the ingot is not stripped too quickly from the mold, it is practically free from piping, and this can'be wholly eliminated by use of appropriate hot tops or sink heads on the mold.

The mold structure is rugged and serviceable, and'will withstand the hard usage of practical operations without injury. It

stands up as well as, if not better than, the

average mold, so far as life is concerned.

Variations in detail will readily occur to those dealing with the problem, and I do not limit my invention to the precise structure shown. I claim- 1. An ingot mold having walls, the cross sectional area of which corresponds substantially to that of the mold chamber in the plane of the section.

2. An ingot mold having wall areas, the

sides of which converge outwardly, and the cross sectional areas of which are substantially equal to the area of the mold chamber in the plane of section. I

3. An ingot mold having wall areas, the sides of which converge outwardly, and the cross sectional areas of which are substantially equal to the area of the mold chamher in theiplane of section, and, reproduced inwardly, meet on converging lines in the mid area of the mold chamber.

4. An ingot mold having Wall areas, the outline of which in cross section is "such that, reproduced inwardly, they define a combined area corresponding substantially to the area of the mold chamber.

5. An ingot mold having wall areas, the outline of which in cross section is such that, reproduced inwardly, they define a combined area corresponding substantially to the area of the mold chamber, the adjacent boundaries of such inwardly produced Wall areas being substantially co-incident.

6. An ingot mold having wall areas, the outline of which in cross section is such that, reproduced inwardly, they define a combined area corresponding substantially to I the area of the mold chamber, the boundaries of such inwardly produced wall areas being convergent, and adjacent boundaries being substantially coincident;

7-. An ingot mold having wall areas, the outline of which in cross section is such that, reproduced inwardly, they define a combined area corresponding substantially to the area of the mold chamber, the boundaries of such inwardly produced wall areas being convergent toward the center of the mold chamber, and adjacent boundaries beingsubstantially coincident.

8. An ingot mold, the walls of which have relative heat absorbing and radiating capacities predetermined to effect progressive solidification of contained molten metal in areas substantially co-terminous laterally and converging to the mold center. i

9. An ingot mold having a wall comprising a series of heat absorbing areas with outwardly converging sides, the outer boundaries of said areas being spaced from the inner face of the mold chamber a distance substantially corresponding to half the 11. An ingot mold having a plurality of wall areas with outwardly converging sides, the angle between 0 posed faces of adjacent areas being such that they intersect substantially at the inner face of the mold.

122. An ingot mold having a plurality of wall areas with outwardly converging. sides, the angle between opposed faces of adjacent areas being such that they intersect substantially at theinner face of the mold, and the cross sectional configuration of such areas being such that, inwardly reproduced, adjacent boundaries of such areas are substantially coincident, and the combined extent of such areas substantially corresponds to the area of the mold chamber.

18. The method of solidifying ingot metal which comprises freezing the same progressively to te ingot center in areas substantially co-terminous laterally and converging to the mold center.-

In testimony whereof I have signed my name to this specification.

FREDERICK APPLEBY BLAoK;

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