US1678976A - Method of and apparatus for casting ingots - Google Patents

Description

July 31, 1928.

1,678,976 J. A. DURFEE METHOD OF AND APPARATUS FOR CASTING INGOTS Filed Nov. 20. 1926 2 Sheets-Sheet 1 IN VEN TOR.

. ATTORNEY.

- i ul 31, 1928.

. J. A. DURFEE Y METHOD OF AND APPARATUS FOR CASTING INGOTS Filed Nov. 20. 1926 2 Sheets-Sheet 2 INV'ENTOR. BY Jos bhAM DLLW 'v- TrfiEYh Patented July 31, 1928;

UNITED STATES JOSEPH A. DUBIEE, OF BTEUBENFIILE, OHIO.

METHOD AND 'APPABATUS FOB CASTING INGOTBQ Application flled-llfovember a0, 1926. Serial in. 149,692.

My invention relates to the art of casting metal ingots and particularly to the art of castingsteel ingots and ingots of steel allpgs.

eretofore ingots have been cast in cast iron or steel molds or castings, the metal -duce an ingot mold that may be poured from either being poured into the top of the mold or forced thereinto from the bottomthereof,-

the latter requiring relatively expensive apparatus compared with top poured ingots. When the metal is poured in at the top, occluded bubbles formed, when the stream of molten metal strikes the surface of the molten metal sometimes disposed five or more feet below the pouring spout of the ladle,

depending upon thedepth of the mold, are carried toward the side walls of themold and are there entrapped in the chilled 'metal adj acent'to the mold walls which are usually three or four inches in-thickness.

The 'zone of the ingotadjacent to the surface and commonly known as .the skin usually contains countless bubbles or blowv holes which zone extends inward from the surface about an inch. When the ingot is rolled to form a bloom or slab, the bubbles remain near the surface of the bloom or slaband cause seams on or near the surface which remain in the bar or sheet rolled from the bloom or slabrespectively, with the result that the surface thereof is rough and of weakened structure. v

Gases released from the molten metal at the time of "pouring or later are also entrapped and produce bubbles which also are carried to the side walls by the flowing metal .and there permanently entrapped 1n the chilled metal adjacent to the surface of the x ingot.

' sulphur,

The metalloids such as carbon, manganese, etc..have a tendency to move toward the center of the ingot, the central portion being the last to cool, and therefore are concentrated near the central zones ofthe ingot.

This segregation of the metalloids causes a non-umform'distribution of the metalloids and consequently *the steel of the ingot is not uniform in structure or strength. I

An object of my invention is to produce a method of casting ingots wherein the occluded air bubbles and thereleased gasesare prevented from-coming in contact with the side walls of the mold or accumulating in the vicinity of the side walls thereof.

Another object ofmy invention is. to produce' a process of casting ingots wherein segregation of the metalloids is arrested if not entirely prevented and wherein the isthe top and which will' produce an ingot practically free ofbubbls and in which the metalloids are uniformly distributed.

Another object of my invention is to provide an ingot mold for producing an ingot having the above noted characteristics thatmay beadapted to existing ingot mold. casmgs, thereb usmg specia mold casings. Another object of my invention is to rodu'ce an ingot mold wherein the yiel of usable steel is increased and wherein the quality thereof is superior to that produced eliminating the necessityf'ofin the usually employed mold by the present 7 practice of casting. a These and other objects that will .be niade apparentthroughout the further description of 'my nvention are attained by means of the process and apparatus hereinafter described and illustrated in the accompanying 'drawings,-wherein Figure 1 is a vertical section through an ingot cast inthe usual mold and 'by the present practice of casting; Fig.2 is a similar view of an ingot cast 1n my im rove'd mold and bymy improved process 0 casting;

' Fig. 3 is WYGI'tlCfll section through a'mold embodying features of my invention;

4 Fig. 4 1s a plan view of the mold shown in Fig. 3;

Fig. 5 .is a vertical section through the mold shown in Fig. .3, illustrating the phenomena incident to casting an ingot by my improved process; 1

Fig. 6' 1s a vertical section through an modified form of mold construction;

-Fi 7 is a transverse section taken on the hue VII-VII of Fig. 6;

Fig. 8 is avertical section of a further modification of an ingot mold;

-Fig. 9 is a transverse section line IXIX of Fig. 8; and

Fig. 10 is. a transverse section through a further modification of ,an ingot mold;

Referring to the-drawings, Figs. 1 and 2 represent respectively, an mgotcast in the taken on the no usual moldby thepresent process and an ingot in my improved mold by my improved process. The ingot 11 shows in exaggerated form the bubbles and blowholes 12' that are entrapped near the surface of the ingot and the segregation. of the metalloids 13 near the center is represented by the dots,

the concentration. being greatest near the center of the ingot and near the upper end.

' 4. The mold casing is supported on a base plate 16 and the partition 15 extends from the top to the bottom of the mold and is provided at its lower edges with notches 17, the purpose of which will hereinafter appear.

The walls of mold casings are usually three or four inches in thickness and consequently are not fused by the molten metal poured into the mold. The partition 15 is preferably of the same metal composition as that to be poured in the mold and the thickness of the partition walls is such that thepartition will fuse after it has beefi immersed in the molten metal a predetermined time, the time being determined by the thickness of the plates andthe temperature of the metal.

The partition is preferably spaced about three inches from the side walls of the mold and is centered and supported within the mold by spacers 18 and 19, the latter extending over the upper edges of the mold walls The operation of the process is illustrated in Fig. 5 wherein the mold 14 is shown about half fullof molten metal which is being poured from the spout .of a ladle 21. vWhen 1 the first molten metal was. poured into the moldit flowed under the edges of the partition through the notches 17, and thereafter 'themtal flowing to the side walls of the mold casing was caused first to'descend under the lower edges of the partition and thence upward' between the partition and the side walls of the moldcasin' -The occludedbubbles12 whic are caused by the column of molten metal striking the surface of the molten metal within the mold,

- rise rapidly and the relatively slow down ward movement of the metal within the artition as it flows beneath the under e ges thereof, permits the bubbles to rise clear of the mass before the-metal flows under the partition. Therefore the occluded bubbles are released and cannot come in contact with the side walls of the mold where the metal is first chilled andsolidified.

Because the lower edgesof the partition come first in contact with the molten metal, they are the first to fuse, and the thickness thereof is such that they withstand the heat suflicient time without fusing to maintain a portion of the partition always below the surface of the molten metal as indicated in Igig. 5, and well below the zone of the bubles.

The metal therefore must flow downward before it can rise between the partition and the mold walls, thus clearing it of occluded bubbles due to pouring of the metal. Molten steel, at the temperature at which it is taken from'the furnace, contains gases in solution such as carbonic acid, nitrogen, hydrogen and other elements. When the metal cools, these gases are separated or released in the form of minute bubbles. When metal is poured into the usual ingot mold, gases are released in themetal while the latter is in *a. molten state due to reduction in tempera- These bubblesidiifer from the occluded adjacent the walls, the metal at this pointsolidifies before the bubbles have had opportunity to rise to the surface. It is an obect of my invention to cause uniform cooling of the metal to the temperature at which the gases. are separated or released as the metal is being poured into the mold and to provide suflicient time-for them to rise to the sur-' face before they actually come into the vicinity of the side walls of the mold. By cans ing the metal poured into the mold to descend along and under the partition or gate where they are cooled thereby, its temper-.

ature is reduced to the point where gas bub- ,bles' are formed and before the metal reaches 7 the side walls of the mold the gases are separated and permitted to rise before flowing to the space between the partition and the mold walls or other cooled zones.

The partition, however, may be made of such thickness that it will not fuse until the entire ingothas been cast, and in that event, all the metal flowing to the side walls poured. 'The number, size and her/sore of the mold partition. p

The partition also" reduces the temperature of the molten metal in its immediate vicinity and this action tends to impedesegregation of the metalloids.

An ingot cools first at the sides incontact with the mold walls, the center being the last to solidify.

Such metalloids that have a lower fusion point than the iron, stay in a molten"con dition after the iron molecule has become plastic and the contraction of the iron molecule tends to squeeze the me'talloids towards its hottest side which is in the direction of the center of the ingot. As the metal solidimust flow downward under the fies the metalloids move toward the center of the ingot, and ingots cast under present conditions are found to contain a, greater density of metalloids near the center.

The cooling action of the partition within the mass causes the ingot to be cooled more uniformly, and consequently, the tendency to move the nietalloids to the center is min1- mized, with the result that they are more uniformly distributed throughout the mass Jposed inconcentric spaced relation within the mold casing 14 and centered by spacers 18 and 19. The lower edges are notched to" permit initial-flow of molten metal under the lower edges,"the metal being poured into the inner partition and permitted to flow upward between the partitions and be tween the outer partition and the side wall. In this form, there is an increased refining or bubble eliminating action, and a more uniformly distributed cooling medium tending to arrest segre ation of the metallolds. It will be seen that y proper distribution of the partitions'and the mass of the partitions, substantially uniform cooling can be accomplished and segregation substantially arrested.

Fig. -8, shows a further =modi-ficat1on wherein in place of the two inner partitions shown in 'Fig. 6, metal rods 23 are substituted to cause uniform cooling of the mass.

The rods are supported on a late 24 having an opening 25 through whic the-metal is osition of the rods. may be varied to obtaln uniforni cooling action, and to insure fusion thereof before theingot metal solidifies; The partition 15 functions in the manner of the mold illustrated in Figs. 3, 4' and 5, and may be perforated. I

The partition walls may be made of sheet metal raving openings or perforations or of steel wire gauze as shown in Fig. 10

wherein a cylindrical partition; made of steel, gauze wire is employed. The mainflow of molten metal is beneath the lower edge of the screen, and the coolin action of the screen tends to arrest segreg ion of the metalloids.

It will be understood, that the screens or partitions are preferably made of metal similar to that being poured and that the temperature of the metal is sufiicient to fuse the rods, with the metal of the ingot, the result being "an ingot-of homogeneous structure throughout, substantially free of blowholes and bubbles andof substantially uni-' form composition. By reason of this process, more uniform steel is produced and the yield per ingot is materially-increased.

To assistin the internal cooling action of the devices above described, pieces of metal scrap may be placed in the mold as the pouring progresses, thereby reducing the,

temperature of the metal in the interior of the ingot as it is being poured and causin 1 a substantially uniform cooling action an even distribution of the metalloids.

WVhile I have described my process and have shown several modifications ofthe 2. The process of casting ingots in amold.

which consists in placing a partition within the mold and in pouring molten metalinto the mold on one side of the partition and at a temperature capable of melting the partition before the-metal solidifies and whereby the. metal is caused to-flowunder the sub- 'merged unmelted portion of the partition to the other side thereof. v

3. The process ofv casting ingots in a mold which consists in placing a plurality of screens within the mold for dividing the mold intoa plurality of substantially concentric compartments, and in pouring the molten metal into the inner compartment whereby it is caused to flow underthe 125 screens to the other compartments.

4. The process of casting ingots in a mold which consists in placin within the mold fusible metal and in distrlbuting it throughout the interior of the mold, and in pouring molten metal into the mold at a temperature sufficient to'fuse the fusible metal before the molten metal solidifies.

5. An ingot mold comprising a mold shell of sufficient mass to prevent fusion by the molten metal poured therein and fusible metal supported within the" mold adapted to be fused by the molten metal but constituted to remain intact beneath the surface of the metal durin' the pouring operation.

-6.' An ingot mol comprising a relatively nonfusible mold shell and having fusible cooling metal supported therein adapted to be fused by the molten metal poured into the mold but constituted to remain intact beneat-h the surface of the metal for a, predetermined time during the pouring operation.

7. An ingot mold comprising a mold casing and fusible partitions therein adapted to be fused by the molten metal poured therein but constituted to remain intact below the surface of the metal a predetermined distance during the pouring opcration.

8. An ingot mold comprising a mold casing andfusible metal directing partitions therein. v

9. 'An in otmold comprising a mold casing and a usible partition within the mold for directing molten metal downward to a predetermined point below the surface ofthe metalbefore it reachesthe side walls of the casing. 1

10; An ingot mold comprising a mold casoreen ing and a fusible partition within the mold agaplted to remain intact below. the surface 0 t internally.

11. An ingot mold comprising a mold casing and a fusible cooling agent within'the e metal and toeventually fuse for directing the molten metal and for cooling it mold adapted to remain intact below the 13. An ingot mold comprising a mold casing and a pluralityoffuible partitions dividing' the mold into a plurality of concentric' communicating compartments.

14:. An ingot mold comprising a mold casing and a fusible perforate partition dividing the mold into a plurality of communieating compartments.

15. The process of casting metal ingots in a mold which consists in introducing rela-' tively cold unfused fusible metal members therein for quickly cooling the metal and in pourin the metal into the mold and in contact with the fusible metal members.

.In testimony whereof, I have hereunto subscribed my name this 21st day of Coteber, 1926. I JOSEPH A. DURFEE.

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