US2366289A - Casting ingots - Google Patents

Description

Jan. 2, 1945. A. R. ROWE- cAsTING'INGoT Filed March 28, 1944 5 Sheets-Sheet, 1

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INV ENTOR. ,4A/DREW P. Poe-ere,

Jan. 2, A1941's. A R 'R0WE 2,366,2"89

CASTING INGoT Filed March 28, 1944 3 Sheets- Sheet 2 Jan. 2, 1945. A, R, ROWE 2,366,289

CASTING INGOT Filed March 28, 1944 s sheets-she'et s INVENTOR. Jfrwins-5.15.5. 4 14A/025m' A. PorL-r Patented Jan. 2, 1945 36am -l CASTING'INGOTS Andrew R. Rowe, McKeesport, Pa., assignor to Harbison-Walker Refractorles Company, Pitts' burgli, Pa., a corporation of Pennsylvania Application March 28, 1944, Serial'No. 528,389

(ci. 22gim 12 Claims.

This invention relates to the casting of metallic A ingots, and this application is a continuation in part of my copending application Serial No. 498,- 940, filed August 17, 1943.

The `invention is applicable particularly to the casting of ingots of iron and'steel, for which reason it will be described with particular reference thereto by way of illustration, but not of limitation. The common practice in the casting of such ingots is to teem the molds f rom a ladle which isusually of large capacity and from which the moltei metal is discharged through a relatively large nozzle so that a large stream of molten steel enters the mold under a considerable head. 'I'his is disadvantageous for various reasons. Thus, the relatively great head of the metal causes the stools or the bottoms of the molds to be cut out rather rapidly causing diillculty in removal of the ingots, i. e., so-called stickers, and necessitating premature discarding o-f the molds. Also, it4 produces considerable splashing which may form. a scabby surface on the ingot and thus result in defects in the surface of products wrought from it or necessitate chippingthe ingot with added expense. Particularly, the metal in the mold is churned vigorously and deeply by the en tering stream so that slag and other non-metallic material together with gases released from the metal are forced throughout the body of the metal within the mold. Such materials may not have suiilcientl buoyancy to rise to the surface so small streams the metal would enter the mold under a relatively slight head and would not cut out the stool, splash objectionably, or penetrate the cast metal deeply, thus permitting gases to escape freely and slag or the like to collect at' the surface rather than being churned throughout the metal. Furthermore, it was intended that the float member should rise within the feeder as it was lled.

Experience showed that the hot top of that patent could perform satisfactorily with som'e classes of steels or under some conditions, but

that it was open to serious disadvantages and drawbacks. One of the most serious of those was due to the fact that the float seated closely against the supporting flange of the feeder so that, particularly with ordinary low silicon steels, the float tended to freeze into place in the bottom of the hot top due to the factthat the metal would enter and freeze between the sides of the float and the hotl top walls. Drainage around the side of the float was not contemplated. l 'I'his that undesirable non-metallic matter and blow i holes will be present in the ingot.

Another diiilculty encountered in ordinary casting practice is that of pipe formation. To avoid this it is customary to provide the mold with a. hot top, or feeder, which in any `of its conventional forms constitutes an extension of the mold that acts as a reservoir for a. body of the molten metal to feed the ingot as it freezes and thus to avoid piping by filling the axial shrinkage cavity. Such' hot tops do not, however, avoid the foregoing disadvantages of pouring practice because vthe metal is teemed directly from the nozzle through the feeder into the mold.

In my Patent No. 1,399,798, granted December 13, 1921, I disclosed a means whose object was to reduce the foregoing difficulties and disadvantages. In accordance with that invention, a hot top. or feeder, member was provided around its lower end with an inwardly projecting ange which acted as a continuous iloat. Either the float or the flange was perforated. The underlying concept was that by breaking up the nozzle stream into a plurality of condition was aggravated where the metal teemed was on the low side of the pouring temperature range. Also. as the metal ran through the holes in the float member, it apparently created a downwardly acting suction which tended to 'hold the float member in place. Even though gas escaped freely and slag or the like rose to the metal surface, this tendency for the float to stay or freeze in the bottom of the hot top was objectionable because the hot top and float would break off during and interfere with rolling, and this was aggravated where the perforations were in the shoulder because it then had to be of considerable width. The small clearance between the float and the hot top walls or its seat prevented successful dislodging of the float by means of a bar or-lever. Other disadvantages were that if the ladle was not spotted accurately the stream from the nozzle would tend to pass directly through .one of the holes through the plate or l lug so that the metal would enter the moldv under seat for a refractory the greater part of its normal head pressure, thus partially defeating the'aim of the invention, and also that stickers were commonly encountered. Forthese and related reasons -the hot top of that patent did not satisfactorily achieve its objects under the conditions which prevail in ordinary steel mill practice and therefore it was not adopted commercially. f .l

, In my above-identified copendlng application I have disclosed and claimed a method of and means for reducing or eliminating the troubles encountered with the hot tops of that patent. In

' mold with a hottop.

" before it joins the main body in theaccordance therewith the hot top and float member are so contructed that the metal poured into the hot top enters the mold by flowing around the edges of the float plate and between the plate and its supporting flange, or shoulder.` That is,

an imperforate float plate is used which is substantially smaller in area than the crossv sectional area of the hot top. and it is supported, as in the patented invention, by a continuous shoulder, or flange, at the bottom of the hot top. Either or both the plate and the shoulder may be provided with means for metal to flow into the mold from the space between the edges of the plate within the mola sc that slag and the like is not and the hot top walls. Thus, either or both may be grooved, the plate may be supported by bosses which space it from the flange, or the shoulder along each wall may slope downwardly from each side.

Experience with the hot tops of the foregoing application in the casting of steel ingots in commercial practice has shown that they satisfacentrapped within the body of the metal but rises freely to the surface, and pipe and blow hole formation together with rapid cutting out of the stool and production of scabby or cracked surface are reduced. or avoided, and which avoids Asplashing in and from thehot top during pourifet another object is to provide an ingot hot top having a float member which cooperates to break up the ladle stream for attainment of the foregoing objects but which'does not have the tendency to cause slashing or to be frozen in place which characterized former. hot tops provided with float members.

Other objects will be understood from the following description.

The invention may be described inconnection with the accompanying drawings in which Fig. 1 is a vertical sectionalview through the preferred 'embodiment applied to a small-end-up torily improve the surface quality Aof ingots,

' greatly reduce cutting out of the stools or mold bottoms and the production of stickers, efilciently avoid the troubles encountered with ordinary hot tops, produce ingots of superior quality as compared with ingots poured with ordinary hot tops and as compared with those' ofmy aforesaid patent, and are of general utility. even with the common low silicon steels.

However, the casting of large vsize ingots with the hot tops of that application has shown that although they function satisfactorily, as Just stated, they are open to disfavor because of one result inherent in their construction. Thus, the

hot tops and floats have been constructed to pro-l vide for ready drainage. of metal, to. insure against thefreezing ofthe floats which was encountered with the-patented construction. Experience vhas shown that the metal ilows so quickly into the mold through the passageway in mold; Fig. 2 a plan view of the hot top shownin Fig. 1, without the oat; Fig. 3 a fragmentary showing -on an` enlarged scale of a portion of Fig. 1; Fig. 4 a view similar to Fig. 1 showing the condition after backpouring; Fig. 5 a vertical sectional view of a modified form of 'not top; Fig. 6 a view similar to Fig. 3 of a portion of Fig. 5; Fig. 'Z a view similar to Fig. 5 showing another modified form of thehot'tops provided by the invention; Fig. 8 aplan -view of Fig. '1; Fig. 9 a.'l view similar to Fig. .5 of another form, .taken on line4 III-IX, Fig. l0; Fig. 10a plan view of the *hot top of Fig. 9; .and Fig. 11 aperspectlve of belng broken away ber'provided at its lower end with an interior which the space vbetween the bottom of the plate,

or float member, and the nange is greater than v that between the plate edgeand hot top walls, .that n'o pool of metal accumulates in the hot top until the metal level reaches the oat. Consequently, up to that time the stream of metal from v plate and causes splashing of metal.. This is objectionable for two reasons. First, the splashing of metal from the' hot top creates a serious hazard to the operators on the pouring platform. This necessitates the use of a -longer hot top than would be needed otherwise for some purposes. Second, splashing within the hot top may of the plate and the hot top walls to insure that the plate will risefreely when the ingot is backpoured.

n is among the objects orfana mvenacn to provide ingot casting means which'avoids or rethe. ladle irnpinges'continuouslv upon the float shoulder for supporting afloat plate of su'ch vsize 'as to have its sidesspaceda substantial distance from the. walls of the hot top to provide a passageway for metal. As in the earlier, application also, means are provided whereby the metal `can ow from the said passageway-and enter the mold l in the form of small streams or sheets frombetweenthe plate and its supporting shoulder. In

this invention. however,v the construction is such that. the flow of metal from the passageway between the sides of the float and the hot top walls is throttled, to slow down drainage of metal from the said passageway. In this manner I amv I enabled to maintain the substantial space around the oat plate that is necessary to avoid its being" frozen at the bottom of the lhottop while at the same time causing a pool of metal to form in the hot top during teemingand thereby reducing or d'uces substantially .the troublesA and disadvantages described above.

A particular object is to provide'an ingot feeder, or hot top, and the combination of an ingot which satisfactorily breaks up the stream of metal entering/the mold in such manner as to permit escape of gas from the metal mold and to avoid strong agitation of the body of metal `into, that between the bottom ofthe eliminating splashing.4 This can beaccomplished in various ways. most-suitably by providing either the plate or. the supporting shoulder of the hot top with spaced bosses which support' the plate with its lower edges spaced from the shoulder a distance less than that between the sides of the plate and the hottop walls, whereby to throttle. the flow of metal from the latter passageway Plate' and the shoulder. 1 Having reference now to. the drawings, Fig; 1

shows a feeder inl accordance with the invention 4associated lwith a small-end-up mold l.

The

feeder comprises a tubular hot top member I,

made from fire clay or other refractory material, l which may take any of a variety of forms and be supported on or by the mold in a variety of'ways 'port the hot top, i. e., the lower ends of ribs 3 rest upon the top of the mold and support the hot top properly positioned with respect to the mold opening. At its lower end the hot top is provided with a continuous inwardly extending flange 4 whose upper surface slopes inwardly and downwardly, as seen in Fig. l.

` to the bottom of the hot top that was encoun-- tered with the floats of my said patent is -over- Disposed within thehot top is a refractory im- I perforate float plate 5 which, as shown in Figs. 1 and 3, is of such size as to provide a clearance space a of substantial width between its edges and the hot top walls. The space a provides a passageway for escape of metal teemed into the hot top from the nozzle 6 of a ladle, not shown.' Thus,

metal passed into the feeder flows over plate 5 and passes into the clearance space a.

To provide for flow of metal into the mold plate s rests on bosses 1 formed with shoulder 4 with their top surfaces above theplane f the shoulder, as seen particularly in Fig. 1. In accordance with the invention these bosses support the plate with its lower edges spaced from the underlying shoulmold @I in the manner shown in Fig. l. Metal is then teemed into the hot top from the nozzle 6. The large stream under its normal head strikes plate 5 and flows outwardly thereover to enter the clearance space a between the edges of the der by a distance b which is less than the width a plate and the walls of the hot top whence it drains in relatively thin sheets 8 into the mold. A primary action is that the breaking up of the main stream 9 of the metal by plate 5 into a relatively thin layer which moves over the plate permits at least some portion of gas carried by the metal to escape before the metal enters the mold. This action is further enhanced by the passage of the metal from the feeder in thin sheets, which permits a more ready escape of gas than is possible 'from the large stream 9. 'I'he small streams, or sheets, 8 do not churn up the body of metal I 0 within the mold so that there is little tendency for gas bubbles to be stirred in to the metal as it rises within the'mold. Thus, the feeder acts to reduce or eliminate blow hole formation both by freeing much of the gas carried by the metal before it reaches the main body in the mold, and also by educing or eliminating churning of the main ody.

Furthermore, streams 8 drain into the mold under a'pressure head thatgis? substantially less the surface of the body of metaly I0 within the mold, as shown in Fig. 4. When the metal between the hot top and the mold wall has frozen further metal is poured into the hot top to fill it and provide a reservoir I2 (Fig. 4) of molten' metal for feeding the ingot as solidication progresses, to reduce or eliminate piping.

A major advantage of the present invention, as in the case of that of my copending application, is that the tendency of the float member to freeze come. D

Of primary importance, however, is the throttling action of the relationship described. Thus, the metal flows over plate 5 and enters the relatively wide space a, which may be, for example, 5A; or 1% inch wide. Flow of metalfrom a is retarded, however, by the fact that space b is smaller. This results in promptly building up a pool II of metal in the hot top, which eliminates, or substantially so, splashing in and from the hot top. At the same time the width of dimension a needed to avoid freezing of the plate to' the hot top bottom is maintained, and dimension b is wide enough for rapid drainage of pool II at the end of teeming, to the same end, i. e., so that there will `be no residual metal to freeze and keep the plate from floating upon backpouring. Drainage of pool Il is assisted by the downward slope of shoulder 4, which serves the further advantageous function of throwing the sheets 8 away from the mold walls.

For some purposes I prefer to make the upper surface of plate' 5 dome-fshaped, as shown in Figs. 1, 3 and 4, as this minimizes splashing before pool II forms, and to provide the upper edges of the plate with a fillet I3 to cause the metal to run smoothly from the plate into passageway a.

Various otherA advantages are also conferred.

Thus, by using an imperforate plate spotting of the ladle will not affect the results, contrary to what was encountered with the feeder of my aforesaid patent. The clearance space a of substantial width between the plate and the hot top walls permits `the float plate to be tilted and lifted by tongs from the hot top. after the latter has been filled as shown in Fig. 4, so that it may be .reused with another hot top member 2, thus reducing the expense of hot topping. Or, as may be preferred in some instances it may be allowed to remain in place for the purpose of keeping the body l2 of metal within the hot top molten to .insure maximum reduction of piping.

An advantage of the form of hot top shown in Figs. l1 to 4 is that the operator can view the interior of the mold through the space between an outer wall of the hot top and the adjacent; mold than the head of stream 9 from nozzle 6. Thus,

there is reduced agitation of the body I Il of molten metal within the mold as compared with the stirring which would result if the main stream 9 enters the mold directly. For the' same reason the rate of cutting out Vof the stool 4is reduced substantially, stickers are reduced or eliminated, splashing in the mold of such intensity as to produce scabby surface is avoided, and slag or other non-metallic material carried by the metal in the ladle has full-opportunity to rise to the surface4 of themetal within themold. 'I'hese factors cooperate to improve the ingot quality. f

The ingot is teemed until drainage of pool I I will immerse the lower end of the hot top within wall and thus determine when the metal has been poured to the proper height, which is not possible, or at least not convenient, with some forms of hot tops. v

Various modifications are, of course, permissible without departingfrom the spirit of the invention. For example, 'I now prefer Ato locate bosses 1 at the corners of the hot top to avoid the interference or turbulence that might occur otherwise at the corners by running together of the streams flowing over the sides of plate 5. Also, there may be provided at least two other b osses la, Figs. 1 and 2, disposed centrally of two opposed lengths vof shoulder 4, to provide adequate support in case of damage to one or more of the plate. Thus, Figs. and 6 show a hot top 2p in which a plate Ia is supported above a shoulder la by bosses I4, integral with the plate, which hold the edges of the plate above the shoulder by a distance b which is less than that of the side passageway a. Again, Figs. 7 and 8 show a hot top 2b in which the same a to b relationship is provided, but here plate 5b is supported overra shoulder Ib whose upper surface is hori- 4lrontal and the sides of which are provided with centrally disposed bosses lb.

as applied to small-end-up molds of generally rectangular cross section it is to be understood that it is applicable generally-to ingot casting irrespective of the type of mold or its cross sectional character.

In addition to eliminating the formation of surface scabs the invention otherwise improves the surface quality of ingots. Thus, in ordinary prac,

tice the heavy head of metal from the nozzle coupled with the relatively, small area. of the mold Vopening causes the metal in the mold to surge l upwardly'along the mold sides above the natural level of metal in the mold.. The thin skin of metal forced up the side ofthe mold in this manner freezes so quickly that contraction of it may cause cracks to form which impair the surface of the ingot. Suchcracks may extend asmuch as several inches into the ingot and effect the quality oi products made from it. In the practice of the present invention 'themetal enters the moldunder such a low head pressure that there is little or no tendency for suchsurface cracks to form.

described with reference to an i erforate float plate, it will be uifderstoo'd that hevplate may be perforated without encountering disadvantages of the feeder of ,the aforesaid patent bel causev the feeder of this invention provides forl free drainage of metal around the sides ofthe plate so that the plate can not freeze in the bottom of the feeder. Of course, the hot top should be positionedat such a level in the mold, or the end of the hot top, that when the mold has been filled to its normal height the plate will be above the metal level, as -shown in Fig. 1. and thus willnot be frozen in place during the freezing in of the hot topby solidication of the surface metal between the hot top and the mold. This may be accomplished, if need be, by appropriate.

blocking up of the hot `top by wooden blocks lj,

any case'to avoid hanger cracks,.as shown in F18. 1f A s. 9 and 10 illustrate another modification in which the hot top 2c receives a refractory iloat- -pla lc which is smaller than theopening formed by the shoulder 4c but'which is supported by bosses 1c integral with the shoulder.l A s may be seen from Fig. 10, the distance b between the sides 'of platesel and the edge 'of shoulder 4c is substantially less than the distance s between the; hot top walls and the' sides of the float plate. Hence, and in accorda-nce with the invention, the-v Although the invention has been illustrated Although the invention has been illustrated and s. An mgotcasting metal poured to such a height above the bottom i in accordance with a practice commonly used in top to. provide therebetween s substantial width for molten metal poured into the .hot top. and bosses integral with said shoulderto support said jplate'va'b'ove and lwith its- 'shoulder a distance less Y f .than the widthof said passageway. 70 5. An ingot Vcasting apparatus may be had by bosses formed on' the under side purposes be high enough to support the plateslightlyabove the lower edge of the shoulder, as shown in Fig. 10.

. Another desirable modification is shown in 5 11i This shows the hot top 2d provided with a side of the shoulder and thus to reduce the weight .10 of the hot top, its cost, and shipping charges.l Obl viou'sly, this modiiication is applicable to all forms of hot tops withinthe scope of this invention.

According to the provisions of the patent statutes I have explained the principle and modeof l5 use of my invention and have illustrated and de.

scribed what I now consider to represent its best enibodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specically illustrated and described.

I claim: 1. An ingot casting apparatus comprising a tubular refractory hot top having at its lower end a substantialLv continuous and inwardly projecting shoulder member adapted to support a plate member, a refractory plate member disposed within said hot top with its sides spaced from the walls of the hot top to provide a passageway of substantial width for molten metal 'poured into the hot top-to pass therebetween, and one of said members being provided with means spacing the sides of the plate from said shouldera distance less than the width of said passageway.

2. An ingot casting apparatus comprising a tubular refractory hot 'top provided at its lower eng with a continuous inwardly projecting shoulder member, a. refractory plate-member disposed within said hot top with its sides spaced from the I walls of the hot topv to provide therebetweena passageway of substantial width for molten metal poured into the hot top, and one of said members being provided with bosses for supporting the plate at a distance froml said shoulder less than the width of said passageway.I e

tubular -refractory hot top provided at its lower end with- `9, continuous inwardly projecting and downwardly 'sloping shoulder member, a refractory plate member disposed within said hot top Fifi with its sides spaced from the walls of the hot top to provide therebetween a passageway of substantial width for molten metal poured into the hot top, and said shoulder member being4 provided with spaced bosses for supporting the plate no at a distance from said shoulder less than the width of said passageway. l 4. An ingot. casting apparatus comprising a refractory tubular hot top adapted to be carried by the top of .a mold to form a continuation thereno -1- of, `said hot topv having at its vlower end.v a .con-

tinuous inwardly projecting shoulder,- a refrac- 1. tory plate'member disposed. within Vsaid .hot top with its sides spaced from' me walls of me l not a passageway of sides spaced from the 'All a substantlallycontinuous and inwardlyprojectapparatus `comprising a according, to

fractory tubular hot top adapted to-be carried by the top of a mold, said hot top having at its lower end a continuous inwardly projecting shoulder, a refractory plate member disposed within said hot top with its sides spaced from the walls of the hot top to provide therebetween a passageway of substantial width for molten metal poured into the hot top, and bosses integral with said shoulder at the corners of the hot top to support said plate above the shoulder a distance less than the width of said passageway.

'8. An apparatus according to claim 1, said plate being imperforate and said shoulder sloping downwardly and inwardly from the hot top walls.

9. An apparatus according to claim 2, said plate being imperforate and said shoulder sloping downwardly and inwardly from the hot top walls.

10. An apparatus according 'to claim "l, -said plate being imperforate and said shoulder sloping downwardly and inwardly from the hot top walls.

11. The combination withan ingot mold of a tubular refractory hot top forming a continuation of the mold, said hot top having at its lower end a substantially continuous and inwardly projecting shoulder member, a refractory imperforate plate member .disposed within said hot top with its sides spaced from the walls of the hot top to provide therebetween a passageway of substantial width for molten metal poured into the hot top, and one of said members being provided with vbosses for supporting said plate spaced from said shoulder a distance less than the width of said passageway.

12. That method of casting ingots which comprises supporting from the top of an ingot mold a tubular refractory hot top having at its lower end a .continuous inwardly projecting shoulder.

, disposing in said hot top a refractory plate member with its sides spaced from the hot top walls to provide therebetween a passageway' of substantial Width, supporting said plate at a distance from said shoulder less than the width of said passageway, pouring metal into said hot top to form a pool of the metal therein while permitting metal toow intoV said mold through said passageway and the lesser space between said plate and shoulder, discontinuing pouring and allowing the metal ofA said pool to drain `into the mold, to immerse the lower end of the hot top in the metal, and thereafter pouring further metal into Said hot top t0 ll 1t and oat.

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