US2545925A - Ingot and mold for making the same - Google Patents

Description

March 1951 E. J. KAUFFMAN, SR 2,545,925

INGOT AND MOLD FOR MAKING THE SAME Filed Nov. 20, 1947 2 Sheets-Sheet 1 INVENTOR famunai Kay/522012, 51:

.BY I QM, M 4

ATTORNEYS March 1951 E. J. KAUFFMAN, sR 2,545,925

INGOT AND MOLD FOR MAKING THE SAME Filed Nov. 20-, 1947 2 Sheets-Sheet 2 INVENTOR W M-: Ma

ATTORNEYS Patented Mar. 20, 1951 UNITED STATES PATENT OFFICE.

2,545,925 I INGOT AND MOLD FOR MAKING THE SAME Edmund J Kauffman, Sr., Girard, Ohio, vassignor to Valley Mould and Iron Corporation, Hubbard, Ohio, a corporation of New York Application November '20, 194?,Serial No. 137,163 12 Claims. (01. 29-187) This invention relates broadly to metallurgy, and more especially to steel ingots and ingot molds for casting the ingots.

'It is well-recognized in the art of steel manufacturing that the proper shape of ingot molds has a very considerable bearing upon the soundness of steel ingots cast within the molds. It has been the practice over a long period of time to avoid extended fiat surf-aces in ingot molds, the molds being provided with rippled surfaces to'facilitate adjustment of the ingot skin or surface in order to relieve to some degree the internal stresses set up within the ingot during solidification and thus avoid cracks and ruptures of the metal which subsequently must be cut out by chipping or scarfing in order to produce sound rolled or forged shapes. The rippled ingot surface may take the form of flutes or corrugations. However, the ingot contour is determined not alone by metallurgical considerations or securing sound ingots, but also physical considerations in that the ingot shape must be such that it can be rolled or forged readily and satisfactorily without lapping or mushrooming so as to produce seams in the steel which also must be .cut out at considerable expense.

yThe above problems are accentuated in the casting of ingots from "wholly deoxidized or killed steels. This is particularly true of the extra high duty steels, such as the lower carbon high nickel, the lower carbon nickel-chromium, the nickel-chromium, molybdenum, and the higher carbon plain steels, all of which seem to be particularly subject to external and in ternal contraction cracks and ruptures.

"It is recognized that the soundness .of a steel ingot is not solely the function of the shape of the ingot but-is considerably affected by other factors, such as composition of the steel, care, and skill used in melting and finishing the steel in the melting furnace, temperature of and speed of teeming the steel into the mold, and initial wall temperature and cooling rate characteristics of the mold walls. By improving the ingot mold shape or contour, the "safety factor of the mold is increased in that sound and satisfactory ingots may be obtained even though the above-listed factors are not so closely controlled as would otherwise benecessary if less favorable ingot mold-contour were employed.

Ingots having a fluted contour are well-known in the art, these ingots having usually a circular :or rectangular cross section. In the cross section of such an ingot, the projections or salients are formed'of radii and the hollows or iiutes are usually formed of radii larger than the salient radii, these curves merging at a tangent point. By varying the two radii, the depth of flute and sharpness of salient have been varied to obtain a shape and cooling rate of the ingot that was intended to produce sound ingots. This @011 struction has been principally an empirical matter, various shapes being tried hoping that a satisfactcry shape could be arrived at. However, as above mentioned, such ingot salients are subject to mushrooming and lapping in the rolls and to being overheated or burned in the soaking pit the contour is not proper even though a substantially sound ingot has been obtained.

I have found that the above-mentioned diili culties can largely be eliminated by determining the radius of the flute salients as a function of the mean diameter of the ingot and by maintaining within limits the depth of the flute, in-

combination with a new and improved ingot eontour. In the form shown of the present invention, the ingot contour comprises convex cylin the present invention may be used with molds having multiple tapers, as well as with molds having a substantially'uniform taper. Adjacent cylindrical surfaces are connected by a substan-' tially lla-t surface tangential to both of the cylind-rical surfaces. Due to the taper of the ingot, these surfaces will have a generally wedgeshape'd outline. The matrix of the ingot mold'is correspondingly shaped, for the purposes of the present invention the contour of the mold and of the ingot produced in the mold being considered the same.

This invention is equally applicable to big-end up or big-end-down ingots and molds.

An object of the present invention is to provide an ingot and ingot mold of improved contour such that the ingot will have improved metallurgical and physical characteristics.

Further objects and objects relating to details of the invention will more definitely appear from the description to follow.

My invention is clearly defined in the appended claims. In the claims, as well as in the description, parts are at times identified by specific names for clarity and convenience, but such nomenclature isto be understood as having the broad est meaning consistent with the context and with In order to extract the ingot from the 3 the concept of my invention as distinguished from the pertinent prior art. The best form in which I have contemplated applying my invention is illustrated in the accompanying drawings forming part of this specification, in which:

Fig. 1 is a vertical section taken through the axis of one form of my ingot mold, an ingot being shown within the mold partially in elevation and partially in section.

Fig. 2 is a horizontal section of the ingot of Fig. 1 taken on the line 2-2 thereof.

Fig. 3 is a diagrammatic cross section of a flute of the ingot of Figs. 1 and 2.

Fig. 4 is another diagrammatic cross section of a flute taken at a point of lesser diameter of the ingot of Figs. 1 and 2.

Fig. 5 is a diagrammatic cross section of a flute of the ingot of Figs. 1 and 2 taken at a point of still less diameter.

Fig. 6 is a somewhat diagrammatic view indicating the rolling characteristics of my ingot.

Fig. 7 is a fragmentary top plan view of the ingot mold shown in Fig. 1.

Fig. 8 is a vertical section taken on the line 8-8 of Fig. 7, indicating a cylindrical salient surface of the mold.

Fig. 9 is a transverse section of an alternative form of ingot and mold, the section through the ingot being taken at a point within the mold to indicate taper of the mold.

Referring now to Fig. 1, a big-end-up ingot mold I5 is formed of cast iron and is generally circular in cross section. With the exception of the contour of the mold matrix, the ingot mold I5 is conventional and need not be further described. A plug IB which may be formed of ceramic material serves to close the bottom end of the ingot mold I5 during the ingot casting operation.

The ingot H, see Figs. 1 and 2, is formed by teeming the mold I5 with molten steel. Upon solidification of the ingot H the outer surface or skin of the ingot will usually be drawn away slightly from the matrix surface of the mold I5 due to initial surface freezing of the skin and contraction of the ingot upon cooling, resulting in; actual deformation of the ingot so that the ingotskin and the-mold matrix no-longer correspond.

The matrix of the mold I5 and the ingot I! are given a contour, the cross section of which is best shown in Figs. 2-5 inclusive. The ingot I1 is generally round and is shown here as provided With 12 flutes, it being common to use a cross section having a number of sides as multiples of four in order to simplify rolling. Thus, ingots are often designed with 12, 16, 20 or 24 sides so as to provide equal bearing on the four sides of the ingot as it is passed through the rolls.

Referring now to Fig, 3, the detailed shape of one of the flutes is shown. The ingot I! is provided with alternating salients I9 and flutes 20. The salients I9 are convex circular arcs formed by radii r. The bottom or central portion of each flute 20 is formed of an arc of radius R. The arcs of the adjacent ingot salients and flute bottoms are connected by substantially straight lines 7., these lines being tangent to both of the arcs. Accordingly, the cross section of the ingot I! will be formed of a series of convexly-curved salients I9 of equal radius with a series of flutes 20 therebetween, the flutes having a bottom formed of a concave arc and the salient arcs and flute bottom arcs being connected by tangents.

The mold I5 and ingot I1 are tapered throughout their length as indicated in Figs. 1 and 2 in order to aid in extraction of the ingot from the mold. Inasmuch as a big-end-up mold and ingot has been shown for purposes of illustration, the successive cross sections from top to bottom of the mold and ingot will decrease in crosssectional area, the flutes becoming smaller but the salients remaining substantially uniform.

The details of two of the successive cross sections are shown in Figs. 4 and 5. Referring to Fig. 4 it will be noted that the ingot salient radius r is maintained substantially constant and the flute bottom radius R is maintained substantially constant. In the form shown, the degree of arc of the salients I9 and bottom of the flute 20 have also been maintained substantially uniform, the entire taper or decreased cross section being provided by substantially uniformly shortening the tangents t.

Referring now to Fig. 5, which shows the extreme small cross section of a flute of the ingot II, it will be noted that the ingot salients l9 still have a substantially constant radius r and the bottoms of the flutes 29 have a substantially constant radius R. The degree of arc of these curves has also been retained substantially uniform but in this case the tangent t has decreased to zero, the convex and concave arcs of the salient and flute now merging at a common point of tangency. In the ordinary case, the taper of the ingot IT and mold I5 will not be carried to the extreme case shown in Fig. 5, but tangents t of appreciable length will be retained.

Considering now the contour of the ingot I1 as a three-dimensional surface, it will be apparent that the ingot surface is formed of a series of convex cylindrical salient surfaces and concave cylindrical flute bottom surfaces, the axes of these surfaces being somewhat inclined to the axis of the ingot according to the degree of taper. This is indicated best in Fig. 8 in which the salient surface of the mold I5 is indicated as a portion of a cylinder of radius r, the axis of the cylinder being inclined to the axis of the mold, as represented by dimension lines a and b.

The adjacent cylindrical surfaces of the sa1i ents and flute bottoms are joined by flat tangent planes generated by the line if of the cross sections. The planes have a wedge-shaped outline and provide the taper for the ingot. Inasmuch as large flat surfaces often cause metallurgical difiioulties in the casting of ingots, these surfaces in the larger diameter molds may be relieved by rippling but are retained substantially flat and tangent to the ingot salient and flute bottom cylindrical surfaces.

In the ingot contour above described and illustrated in Figs. 3-5, the ingot salient arc and flute bottom arc are retained substantially uniform' in both radius and length throughout th lengthof the ingot. It is also contemplated that these arcs may be retained substantially uniform in radius but of varying length from top to bottom of the ingot, the arc lengths being varied in order to adjust the depth of the flute throughout the length of the ingot. In this form, the tangents t are still employed but will not have a constant angularity so as to generate a plane surface from top to bottom of the ingot. The surface genrated by the tangents t in this instance may be a very slightly warped surface which will appear in any cross section as a straight line tangent to the arcs. These warped surfaces are also generally wedge-shaped in outline and are ,Substane QMEQBB tiaily flat and tangent to the cylindrical surfaces of the salients l9 and the bottoms of the flutes 20.

In order to secure the optimum metallurgical and physical characteristics in the ingot I1, the contour above mentioned is employed in combination with definite ingot salient radii r and definite depths of flute, these dimensions varying with the size of the ingot. I have found that the ingot salient radius .1 may conveniently be expressed as a function of the mean roll-contacting diameter of the ingot ll. The mean rollcontacting diameter is determined from the mean of the-roll-contacting diameter D (see Fig. 2) of the ingot at its big end and at its little end. I have found from experience that-the salient radii 1' should be maintained at 6% or less of the mean roll-contacting diameter of the ingot but not less than one-quarter of aninch.

The depth of the flute of an ingot is probably one of the most important metallurgical factors in securing sound ingots free from cracks and voids. However, one limiting factor is determined by the physical characteristics of the ingot in that if excessive flute depth is employed, particularly at the large end of the ingot where the roll pressure is greatest, the salients will tend to lap or mushroom under the rolls, producing seams which must be removed by chipping or scarfing. Accordingly, flute depth must be retained within certain limits.

For convenience in the design of varying sizes of ingots, the flute depth is described herein in terms of angularity rather than by linear depth. Referring to Fig. 3, it will be seen' that the angle A, which is formed between a radius extended through the center of a flute and the line joining the centers of the flute surface and an adjacent salient surface, is a function of the flute depth. It has been found that angle A for best results should be maintained between 50 and 80 in order to obtain the desired metallurgical properties in the ingot and at the same time obtain the desired physical properties of freedom from lapping in the rolls. The angle A need not be constant throughout the length of the ingot but is carefully selected for the big end thereof, this being the critical portion of the ingot during rolling, as above mentioned.

Referring now to Fig. 6, which is a diagrammatic view indicating the action of the rolls on the ingot I1, it will be seen that the tangent t on each side of the salient 19 will serve as a buttress to prevent lapping and mushrooming of the salient under pressure of the rolls. It will be obvious that greater flute depth may be employed in an ingot of this contour without danger of lapping than is possible if the customary reverse curve is used, due to the buttressing action of the tangents t.

While the contour has been described as applied to the ingot, since that is where the contour is significant in determining the ingots metallurgical and physical characteristics, the matrix of the ingot mold I5 is similarly shaped, in order to produce an ingot of the contour described. In the interest of uniform terminology in the claims, the configuration of the matrix surface of the mold is referred to on the basis of being approached from the outside of the mold. Thus, a portion of the matrix surface which forms a salient on the ingot is referred to as a salient on the matrix surface, and a portion of the matrix surface which forms a flute bottom on the ingot is referred to as a flute bottom on the matrix surface.

The above invention is not confined to circular fluted ingots and molds but i also applicable to rectangular and near-round contour ingots and molds. In Fig. 9 a rectangular ingot mold 30 and ingot 3| is shown, the flutes of this ingot and mold being similar to those of the ingot and mold above described. In this instance, the means roll-contacting diameter is the average of the overall length and width at the small and large ends of the ingot. The same considerations and specific limitations obtain with respect to the angle representing depth of the flute, and the salient radius as in the ingot and mold above described.

In addition to the above-discussed advantages of the ingot and mold matrix contour, there is an additional metallurgical advantage in that the salients E9 of the ingot ll, being formed of a cylindrical surface, are uniform throughout the length of the ingot, thus making for metale lurgical uniformity for the entire ingot length which would not be the case if a tapered form of salient were employed.

I claim:

1. A longitudinally tapered fluted ingot mold, cross sections of the matrix surface throughout the fluted portion of which comprise a series of spaced, alternating salient arcs and flute arcs, each salient arc being connected with the adjacent flute arcs by substantially straight lines tangent thereto the arcs of one cross section having radii equal to the radii of corresponding arcs of other cross sections.

2. A longitudinally tapered fluted ingot mold, cross sections of the matrix surface throughout the fluted portion of which comprise a series of spaced, alternating salient arcs and flute arcs, each salient are being connected with the adjacent flute arcs by substantially straight lines tangent thereto, the arcs of one cross section having radii equal to the radii of corresponding arcs of other cross sections and the corresponding arcs of each cross section being equal in length.

3. A longitudinally tapered fluted generally circular ingot mold, the matrix surfaces of which comprise a plurality of cylindrical surfaces forming spaced alternating salients and flute bottoms, the axes of the cylinders defined by such surfaces being at an angle to the axis of the mold, and a substantially flat longitudinally-tapering surface connecting each salient with each adjacent flute bottom, the surfaces being tangent to the salient and the flute bottom.

4. An ingot mold as claimed in claim 3 in which the angle between the flute radius through a flute center and a line connecting the flute center and an adjacent salient center is not less than 50 nor more than 80.

5. An ingot mold as claimed in claim 4 in which the radius of the salients i not in excess of 6% of the mean diameter of the mold and not less than 6. A longitudinally tapered fluted metallic ingot, the outlines of cross sections throughout the fluted portion of which comprise a series of spaced, alternating salient arcs and flute arcs, each salient are being connected with the adjacent flute arcs by substantially straight lines tangent thereto, the arcs of one cross section having radii equal to the radii of corresponding arcs of other cross sections.

7. A longitudinally tapered fluted metallic ingot, the outlines of cross sections throughout the fluted portion of which comprise a series of spaced, alternating salient arcs and flute arcs, each salient are being connected with the adjacent flute arcs by substantially straight lines tangent there, the arcs of one cross section having radii equal to the radii of corresponding arcs of other cross sections, and the corresponding arcs of each cross section being equal in length.

8. A longitudinally tapered fluted generally circular metallic ingot'the fluted surface of which comprises a plurality of cylindrical surfaces forming spaced alternating salients and flute bottoms, the axes of the cylinders defined by such surfaces being at an angle to the axis of the ingot, and a substantially flat longitudinally-tapering surface connecting each salient with each adjacent flute bottom, the surfaces being tangent to the salient and the flute bottom.

9. A metallic ingot as claimed in claim 8 in which the angle between the flute radius through a flute center and a line connecting the flute 2 center and an adjacent salient center is not less than 50 nor more than 80.

10. A metallic ingot as claimed in claim 9 in which the radius of the salient is not in excess of 6% of the main diameter of the ingot and not less than 11. A longitudinally tapered fluted ingot mold, the matrix surface of which comprises a plurality of cylindrical surfaces forming alternating salients and flute bottoms, the axes of the cylinders defined by such surfaces being at an angle to the axis of the mold, and a substantially flat longitudinally-tapering surface connecting each salient with each adjacent flute bottom, the surfaces being tangent to the salient and the flute bottom.

12. A longitudinally tapered fluted metallic ingot the flutedsurface of which comprises a plurality of cylindrical surfaces forming alternating salients and flute bottoms, the axes of the cylinders defined by such surfaces being at an angle to the axis of the ingot, and a substantially flat longitudinally-tapering surface connecting each salient with each adjacent flute bottom, the surfaces being tangent to the salient and the flute bottom.

EDMUND J. KAUFFMAN, Sa.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,767,174 Gathmann June 24, 1930 1,870,365 Kauffman Aug. 9, 1932 2,028,243 Perry Jan. 21, 1936 2,071,906 Stevens Feb. 23, 1937 2,092,551 Gathmann Sept. 7, 1937

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