US2242703A - Ingot mold and ingot - Google Patents

Description

Patented May 20, 1941 i a I UNITED STATES PATENT OFFICE Emil Gathmann, Baltimore, Md., assignor to Gathmann Research Incorporated, Catonsville, Md., a corporation of Maryland Application February 1, 1941, Serial No. 377,030

4'Claims.

This invention relates to ingot molds and ingots and more particularly to big-end-up molds and ingots having necked-in portions at their lower ends as shown, for example, in my prior United States Patents 1,188,751 of June 27, 1916; 1,570,473 of January 19, ,1926; 1,573,486 of February 16, 1926; 1,660,037 of February 21, 1928; and 2,047,098'of July 7, 1936, and others well known in the art.

The bottom contour in a general way common to the molds disclosed in the aforementioned patents has been employed in the production of many millions of tons of ingots which, in addition to the attribute of soundness of a high percentage of the ingot metal, have had the advantage of being easily handled in rolling, particularly durin the initial roll passes.

In the production of high quality steels, the industry has accepted as necessary the cropping of varying amounts of metals at both ends of ingots in order to remove unsound metal characteristicallyv present in the ingot end portions. An object of the present invention is to reduce the, unsoundness of the metal at the bottom ends of ingots of the class referred to above, or to confine the unsoundness to a zone nearer the ingot bottom, the concave arcs having radii at least twice as long asthe radii of the arcs defining the convex portions of the bottom contour.

Illustrative embodiments of the invention are shown in the accompanying drawing, in which:

- and Figure 4 is va vertical sectional view of an ingot embodying the invention.

A mold M shown as an example of the various kinds of molds in which the invention may be .embodied is formed of suitable heat absorbing .material'such as cast iron and is provided with the usual lifting lugs L. The mold is formed with a big-end-up chamber which is fluted or corrugated in horizontal cross section as shownin Figure 2, but it will be understood that the invention may be embodied in molds having other cross sectional contours, such for example as the cross sectional contours disclosed in the extreme bottom end of the ingot than heretofore has been possible, so as to permit removal of any unsound metal with a minimum croppage loss.

It is generally consideredthat the solidification of ingot metal progresses from the mold walls into the body of the ingot along lines at right angles to the mold walls. Thus, in the solidification extending into the ingot from a perfectly flat mold bottom, or a mold bottom a large portion of which is concave, the formation of the dendritic crystals grows upwardly and inwardly to such a great extent as to interfere with the lines of freezing from the relatively more vertical mold sidewalls. Such interference apparently is the cause of the formation of-the porous ingot structure often found in zones above the bottom of the ingot as much as five or eight per cent of the ingot height. I have found that. these porous metal zones may be largely reduced and confined nearer the extreme bottom. of the ingot by providing a necked-in ingot bottom contour the dominant portion of which is concave in vertical section and which is connected to the ingot side surfaces by a convex portion of considerably lesser extent. The best results have been obtained with ingots whose concave bottom portions are defined by arcs at least twice as long as the arcs defining theconvex portions of the prior patents previously referred to herein.- The several fluted portions or corrugations merge with each other to form a side wall I extending continuously around the ingoteforming chamber;

The bottom of the mold is formed with a centrally disposed bottom opening 2.

The side wall I merges at its bottom with a necked-in wall portion N terminating at the bottom opening 2. In accordance with the invention the necked-in portion comprises a conlong as thevradius R this relation having been found best in practice for molds of the size disclosed. The .relative lengths of the radii R and R and the locations of their centers is such that the arcuate length of the convex part 4 is not less than twice as great as the arcuate length of the concave part 3. It appears that the lines of freezing extending inwardly from the predomiwell up into the ingot body, are so dispersed as to avoid interference with other'lines of freezing 50 that such limited porous ingot metal as is produced occurs only at or below the level of the concave mold part 3 and the corresponding convex ingot part. However, the relation be- .tween the curvatures of the mold wall parts 3 and portions of the necked-in bottoms are now preferred, but the specific relations may be varied in accordance with variations in mold and ingot sizes. Such variations may be made within the wall portion 4 intersects but is not tangent to the wall of the bottom opening 2. Such an arrangement, more fully described in my prior Patent 2,047,098,, is desirable in order to avoid the formation of a protuberance extending around and just above the mold bottom opening and which would be vulnerable to the cutting action of the molten ingot metal when the mold is being teemed.

I Figure 4 shows an ingot I formed by casting in a mold of the kind shown in Figures 1, 2 and 3. Its surface contour is similar or complementary to the mold chamber wall contour and accordingly the several portions of the ingot surface are designated by primed numerals corresponding to the unprimed numerals designating the respectively complementary portions of the mold walls. Thus, the ingot side surface as a whole is designated l, the convex portion of the necked-in bottom N is designated 3', and the concave portion of the necked-in bottom is designated d. The relative arcuate lengths of the portions 35 and t and the relative lengths of their radii correspond respectively to the relative arcuate lengths and relative lengths of the radii of the mold wall portions 3 and 4.

As to molds and ingots of the size shown and described herein, the disclosed relative curvatures and arcuate extents of the concave and convex scope of the invention as defined in the claims.

I claim:

1. An ingot mold having a vertically-extending chamber defined by a wall which is neckedin at the bottom, the necked-in portion of the wall comprising a concave part which merges with the mold wall proper and a convex part connected to the concave part, the arcuate length of said convex part beingnot less than twice as great as the arcuate length of said concave part.

2. An ingot mold having a vertically-extend ing chamber defined by a wall which is necked in at the bottom, the necked-in portion of the'wall comprising a concave part which merges with the mold wall proper and a convex part connected to the concave part, said convex part being struck by a radius at least twice the length of the radius describing the concave part, and the arcuate length of said convex part being not less than twice as great as the arcuate length of said concave part.

3. An ingot of big-end-up contour having a vertically extendin surface terminating at its lower portion in a concavo-convex contour, the arcuate length of the concave portion being not less than twice as great as the arcuate length of said convex portion.

4. An ingot of blg-end-up contour having a vertically extending surface terminating at its lower portion in aconcavo-convex contour, the concave portion being described by a radius at least twice the length of the-radius describing the convex portion, and the arcuate length of said concave portion being not less than twice as great as the arcuate length of said convex portion.

EMIL GATHMANN.

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