US1745089A - Ingot mold and ingot - Google Patents

Description

Jap.Y 28. 1930. e G A'n-IMANN l 1,745,089

L mor now mum I maa Apr113,.1929 singin-sunt 1 l Patented Jan. 28, 19304` 'EMIL GATHMANN, or saumons, MAnYLANn moor MOLD AND meow Application tiled April 3, 1929. Serial No. 852,277.

This invention relates to the casting -of vertically-extending mold chamber and of the As is now well known to those familiar with the art, an ingot cast in a vertical moldhaving a uniformly corrugated dodecagonof twelve-sided cross sectional chamber contour is subjectto the formation ofr fewer surface flaws or defects durin solidication than any other form'of in'got Ixeretofore known. An ingot of this t pe, however, in common with other ingots o substantially round or of'oval cross section, is more or less diiiicult to handle requires a greater number of initial mill passesthan are necessary in the Ireduction of a substantially rectangular ingot of thesame maximum cross sectional dimension in order to insure against tearing ofthe vouter structure or skinof the ingot, both at the primary faces thereof and at the corner portions.

By my present invention I obtain the ad. 4 vantages in-'surface solidification characteristie of ingots of the kind having a dodecagon cross section, at the same time retaining the advantages of an ingot of rectangular cross sectlionin reduction of the ingot in the rolling 1m Asis now well known to those familiar with the art, a steel ingot, irrespective ofits physical condition or chemical analysis, when stripped from the mold and placed in the soaking pit or reheating furnace, is merely a surface-chilled casting; and until work is done upon all its surfaces in the reduction 'of the coarse-grained crystals, the ingot in evitably has the Weakness inherent in .castings as compared to forgings. The reduction of in the rolling mill; and, if properly reduced, v

so accomplishedthat no unworked surface portion4 receives appreciable deformation in reduction or working of adjacent portions. In practice this has heretofore been best'aecomplished by making initial reduction asses light, and by 4frequently yturning the ingot. This frequent turning of the ingot has been an expensive procedure andb my improved` contour I largely eliminate the necessity of frequent turnings and so-called babying. or light preliminary passes.

My improvements may be embodied in an Y type of vertical mold--big-end-up, big-en down, or arallel chamber walls for the production o ingots with or without shrink head portions.

In the accompanying drawings:

Figure lshows a vertical'V central section of an ingot mold of the big-end-up type provided with a shrink head casing' constructed 70 in accordance with my invention, the plug for the bottom opening being shownin eleva tion and the stool in section.

v Figure 2 is a side elevation of the exterior of a big-end-up mold embodying'my improve'- l5 ments and of the kind shown in Figure 1.

Figure 3 is a view on an enlarged scale and in section on the line 3 3 of-Figure 1. v Figure 4 is a view on an enlarged scale and in horizontal section of a quarter portion of 80. the mold shown in Figure 3.

Figure 5 is apers ective view of an in ot formed in a mold o thetype shown in Figures 1, 2, and 3. c

Figure 6 is a perspective view on an en- 85 larged scale of the shrink head casing shown in Figure 1 for forming the upper part ofthe ingo Figure 7 shows ,on an enlarged scale a cross section of the ingot shown in Fi re 5.

The mold body A is preferab y made of cast iron or'other heat-absorbing metal of fsuitable character and rests on a stool Bvhavshown as vertically corrugated, both on the 'the horizontal contour and proportions primary walls and at their corner portions, as indicated at C and C', these corrugations producing salients D and Dof the type herelnafter described. In bigj-end-up mold designs, these corrugations preferably A4extend into the necked-in portion of the mold and merge or disappear therein, as shown in Figure 1, and as shown and claimed in my U. S. Patent No. 1,532,741, of April 7 1925.

It should be borne in mind that three prime factors must be considered in designing the cross section of a mold in order that the best results may be obtained.

A. The ingot must be free to solidify without binding or hanging to the matrix walls .of the mold and be allowed to contract inwardy with a minimum of surface stress.

B. The salients and corners ofthe matrix must be of such angular contour that the in got formed in the mold will not easily become overheated and decarburize at its surface portion while in the soaking or reheating pits.

C. Each primary side of the ingot must be relatively narrow and extend in a plane sufficiently outwardly beyond the adjacent corner salient so that in the initial deformation in the rolls, the corner salients will not be unduly worked nor the adjacent unworked sides appreciably stressed.

I have also found that fewer shrinkage cracks occur in the surface of an ingot during its solidification and also during the mill reduction operation when certain definite angular and radial proportions of the corners and adjacent walls of the mold are employed; and my resent invention relates espciallydto eining the cross section ofthe ingot and the chamber of the mold in which it is produced.

In Figures 1 and 2 of the drawings, lugs O and O are shown as being cast integrally with the mold walls at the upper and lower portions thereof, whereby the mold may be lifted and manipulated as desired in setting up a jug and in removing the solidified ingots therefrom.

As shown in Figure 3, the inner walls defining the mold chamber comprise essentially four primary inwardly-bellied or corrugated side walls C, the walls of each oppositely-disposed pair being substantially parallel with each other or rather parallel with lines drawn across the vertexes at the end of the .corrugations; in other words, the walls are so disposed that a tangent passing across' theface of the vertexes of said walls will form an angle of 90 from the tangent passing across the vertexes of each adjacent primary sideI wall. Eight inwardly-arched secondary corner walls C are connected together in pairs by four relatively small outwardlyarched primary corner walls D, the secondary corner walls C being in turn connected to the inwardly-arched primary sidewalls C lines,

by eight relatively small outwardly-arched wall portions'D, which form the apexes of the primary side walls.

The width, or, more specifically, the chord of each of the primary walls C is preferably less than one third of the maximum horizonu tal cross sectional dimension of the ingot mold chamber, this width being designated by d in Figures 3 and 7. e

Referring to Figure 4 of the drawings, which shows on an enlarged scale one quadrant of the mold illustrated in Figure 3, C-C indicate portions of the two adjacent primary side walls of inwardly bellied or arched contour, and R indicates the preferred length of the radius describing each of the walls C, the length of each-radius being greater than the width or chord of each of said walls. The inwardly arched secondary corner walls C which connect the respective primary side walls C to the adjacent corner walls D are preferably described about centers -y by radii R. Each of the centers -y is located within aright angle L included between two lines L-L and Lz--Ll which intersect at the center p froml which the adj acent corner wall D is described. The intersecting lines .L-L and LZ--L2 are respectively parallel to neutral lines of peripheral shrinkage N-N and N-N as shown in Figure 4. It is important for the best contour of mold lchamber that the radii R be struck from centers located between thelines Lv-L and L2-L2 orgin proximity to these as shown at afly, which lines, as stated, intersect at mary. corner walls D are described by the radii 1'. .j

The dotted lines T, which indicate the c0ntour of an old type rectangular mold chamber, are parallel to the lines L -L and LL-L", which lines are located so as to intersect at an angle of 90 one with the other at or about the points p, from which the radii describin the primary corner walls D are swung. uch a contour prevents the formation of reentrant angles at the junction of the secondary corner walls C and the primary corner walls D. This is very important, as such reentrant angles would-tend to obstruct free contraction of the skin of the ingot during solidification within the mold and thus cause tearin of the ingot surface. It will be observed t at the primary side walls C are connected to the adjacent corner walls C by means of outwardly-extending salients D', and that cach of these inwardlybellied corner wall portions C extends at an angle of from 5 to 15 to a tangentconnecting the apexes of a pair of the salients D at the opposite ends of an adjacent primary side wall C, as illustrated in Figures .8, 4, and 7. f

The arc defining the rimary corner walls D subtends an angle o more than 45 and the centers p from which the pri memos@ secondary corner walls C', having a minimum thickness lat the primary corners D, the corners forming the outer contour of the mold walls being shown as preferably described by radii r about the centers p.

The employment of the contour of corrugated mold chamber which permits offres shrinkage during solidication of the outer skin or contacting portions of the solidifying ingot without danger of physical binding of said skin with the mold walls. The ingot produced in such a mold is of such contour that it maybe reheated without danger of corner burning; and the sur-` face of the ingot will be consolidate in rolling mill operations without material elongation of the ingot as a Whole.4 4 f Furthermore, the thickness or heat-absorp-- tive value lof the mold is progressively decreased towards the primary corners so that a substantiallyv uniform-rate of heat yabstraction from the entire mass of ingot metal is obtained; i

Figures 5 and 7 .illustrate graphically an ingot I formed in a mold chamber of the kind shown and described. The outer portion ofthe ingotv consists of inwardl -bellied or arched primary side walls E, w ich are connected to inwardly-bellied or arched secondar corner walls E by outwardly-curved arche, portions or salients F, the secondar corner walls E being connected by outwar ly-arched primary corner walls G.

The ingot l as shownis of the big-endu l Gathmann type provided with a shrink hea portion W,which preferably has acontour similar to that of the ingot body. It should be understood, however, that my improvements may be embodied not only in big-end up but in an type of ingot, whether equipped v with a shrin head portion or not. Y

Figure @illustrates the type of 'shrink head casing S that l preferably employ, the same having an inner and outer contour similar to the contour of the chamber of the mold body, The shrink head casin is preferably supported on top 'of the'mol as shown in Figure l, sov that a portion thereof entends l below the top or the mold andl into the mold i chamber.;

Unless extreme careis taken in rolling, and particularly li ht reduction passes are employed, the roun corru ated in ot hereto` fore known totheA art is requent y' torn at the pprners before any real work has been done''towards reducing'the relatively coarse ad weak structure of the ingotascast. By

.shortening the relative width of theA primary beforementioned radii and angular proportions'produces a' side walls E of the ingot I, the metal'in the neutral axes N-N of the ingot is initially compressed to a greater degree in a transverse direction than is the metal lying in adjacent planes, and thus le'ssens longitudinal flow, and the danger of transverse cracks occurring in the unworked portionsoffthe ingot is greatl reduced. In the rolling of an ingot em odying my. present improvements,

the initial mill passes not only reduce the primary inwardly-bellied side walls E and the secondary corner walls E', but also the primary corner'walls G, lso that the entire surface ofthe coarse crystalline structure of the cast metal is worked and reined or reduced to a forged rectangular structure be-l fore any considerable lelongation of the ingot has taken place. Tearing of the surface of the ingot due 4to elongation strains orfchecks of coarse unworked crystals is thus practically eliminated.

A mold made in accordance with my invention has approximately 18% to 20% greater volume for a given maximum dimensionvof ingot than has an ingot of dodecagon cross section such as is at present widely used, so that it is possible to materially increase the tonnage ofvblooms or billets that may be reduced to specific size in a given number of I nill passes. l

Another advantage obtained'by the employment of my new cross sectional contour over the dodecagon corrugated contour residesy in the lessened number of molds and shrink head casin s required to contain a given charge of moA ten metal. Furthermore, ecause of the fewer openings of the ladle stopper necessary for 'pouring a given heat of steel, there isl less liability .of trouble, particularly from so-called running Stoppers. I lt is Well known to those familiar with the art that the maximum cross section of an ingot is limited by the size of the rolling mill and the height of the ingot by the depth of the soaking pits in which it is to be' treated preliminary to reduction. Hence the 20% increase in the mass of metal in my new ingot over the round corrugated in ot representsA aV quality of the surface ot the finished roduct is superior to that heretofore obtaina le.-

While each of the tour side Walls of the llll charge is considerably increased, while the' v mold dcav-ity vis preferably onty the contour shown, tairly ood results are obtained when i two ot the siewalls are et the contour in inwardly-arched oppositely .disposed prienerally rec- A dicated, the other side walls being otanother4 litt suitable contour.

mary side walls, and with outwardly arched corner walls, connecting said side walls, the radius describing the arc of each of the side walls being of greater length than the chord of said arc, said chord being approximately one third of the maximum width of the chamber, the mold walls diminishing in thickness from the primary side walls towards the outwardly arched corner walls.

2. An ingot mold having a generally rectangular chamber provided with four inwardly-arched oppositely disposed primary sidewalls, and with outwardly arched corner walls connecting said side walls, the radius describing the arc of each of the side walls being of greater length than the chord of said arc, said chord being less than one third of the maximum width of the said mold chamber, the moldl walls diminishing in thickness from the primary side walls towards the outwardly arched corner walls.

3. An ingot mold having a generally rectangular chamber provided with our inwardly-arched relatively narrow primary side walls and four outwardly-arched primary corner walls merging with a plurality of secondary corner walls, which in turn merge with the primary side walls and extend at an angle of from 5 to 15 from said side wallsythe thickness' of the mold walls gradually decreasing from the primary sides towards the corners.

4. A metallic mold having a generally rectangular ingot-forming chamber provided with four inwardly-bellied primar side walls, the radius forming the inwar ly-bellied contour of each of said walls being of greater length than the width of each of said primary side walls, and four widened corners, which are connectedto the primary side walls by inwardly-bellied secondary walls, the radius of each ofwhich is greater than the width of one of said primary walls, the thickness of the mold walls gradimlly decreasing from the primary sides towards the corners.

5. A metallic mold having a generally rectangular ingot-forming cham er provided with four inwardly-curved primary side walls, and four outwardly arched corner walls connecting the side walls, the radius describing the 'inwardly-curved contour of each of said side walls being of greater length than the width of an adjacent primary side Wall, the mold-walls diminishing in thickness from the primary side walls towards the outwardly arched corner walls.

6. A metallic ingot having a generally rectan ular cross sectlon, at least two of the oppositely-disposed primary sides of which are of inwardly-arched contour, the radius describing the arc lor each of said sides being of a length greater than the chord of said arc and the chord being less than one third of the width of the maximum cross section of the ingot.

l7. A metallic in ot havin four inwardlyi bellied primary si e walls,'t e width of each gle of from 5 to 15 from the adjacent pri- 'mary side wall.

8. A metallic ingot having a generally rectangular cross section with four inwardlyarched sides, the radius describing the arc of each of said sides being of a length greater than the chord of the arc of an arched side and the chord being less than one third of the width of the maximum cross section o the ingot.

In testimony whereof, I have hereunto subscribed my name.

EMIL GATHMANN.

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