US1547787A - Shrink-head casing - Google Patents

Description

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F. H. CHAPIN SHRINK HEAD CASING Filed April 20, 1925 2 Shoots-Sheet 1 July 28, 1925. 1,547,787

F. H. CHAPIN SHRINK HEAD CASING Filed April 20, 1925 2 Sheets-Sheet 2 IL/W State of Patented July 28 1925.

UNITED STATES FRED H. GHAPIN, OF CLEVELAND, OHIO,

ASSIGNOB '10 m BOURKE-FULLER 001-- Pm, Or CLEVELAND, OHIO, A OORPOBA 'I'IOI p210. I

sum-1mm CASING.

Application fled April 20, 1085. leriallb. 4,688.

To all whom it may concern:

Be it known that I, Fnao H. Cmrm, a citizen of the United States, residing at Cleveland in the county of Cuyahoga and hio, have invented a certain new and useful Improvement in Shrink-Head Casings, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings.

This invention relates to what are commonly known in the art of ingot casting, as feeders, sink heads, hot tops, or more properly shrink-head casings for ingot molds.

In the casting of steel ingots by the most approved methods, provision is made in the molds for maintaining in a molten condition on the top of the ingot while ,forming, a pool of metal which supplies to the body of the ingot while being formed and solidified a sufiicient amount of molten metal to fill the pipe or vertical cavity which forms or which would otherwise form during the operation. Molds of the Gathmann type are so constructed that the metal solidifies more quickly in the lower portion than in the upper part thereof, so that the so called pipe is eliminated from the lower part of the ingot while being cast and only a small pipe or cavity remains in the upper part of the forming ingot when the pouring operation is completed. Tllls is true to a large extent whether the so called feeders or shrink-head casings are used or not; but it is now a common practice to employ shrink. head casings, inasmuch as they serve to delay the premature freezing or solidification of the to portion of the ingot by maintaining fluid, for a longer time and in a better condition, the

molten metal at the top of the in 0t, and thus the formation of a pipe in t e body of the ingot is further prevented as the liquid steel which descends fills or prevents 3 the formation of a pipe or a shrinkage cavit which would otherwise be formed within the body of the ingot if there were a uniform rate of solidification or freezing throu hout the entire molten mass. In this way e ingot is so cast that only a small product.

g ihpe or cavity remains in the fine e upper part of the ingot being cast, which contains a pool of molten metal, is sometimes called a feeder, sink head, or shrink head; and it is also common in the *baked at a very hi h the ingot after it and the sound art to call the heat-insulating top of the mold or that part which surrounds the pool a feeder or sink head, but this element of the mold is more properly called a shrinkhead casing. It is, in fact, a part of the mold, 1nasmuch as the u per part of the ingot is cast therein, but it is usually separable from the mold proper and made of different material.

Ordinarily heretofore shrink-head casings have been made of refractory material such as fire clay or'fire brick-material which is extremely hard and brittle, having been temperature and havmg a texture whic is quite close. In order to make such casings, special lants have been required; it has not been t e practice to make such casings at steel lants. Thus transportation of the casings as been neccssary and the expense is correspondingly increased. When in use, the fire-clay or firebrick casings have been supported on the molds by some means which allow them to descend into the mold cavity as the ingot shrinks and solidifies. This has been found necessary, as the casing adheres to the top of the ingot and, unless it is allowed to lower with the shrinking ingot, it will be broken and prematurely destroyed. When the casting operation is finished, the easm remains on top of the ingot and is usu- :11 y broken u by hammers or other suitable tools an thus removed from the ingot before the latter is reheated and passed to the rolls for reducing the ingot to the desired sha e. Quite often lumps and finer particles 0 clay remain on the ingot and ecome embedded therein while passing through the rolls, thus making flaws in the rolled product which are sometimes serious.

Shrink-head casings made of fire-clay have rather low heat-insulating qualities, necessitating the loss of a considerable quantity of metal from the top of the ingot where'the pipe or cavity occurs, it being necessary to remove or crop this portion of ortion thereo are rolled into blooms, bil ets, or other shapes.

It is the object of my invention to overcome the defects ordinarily found in shrinktreated with a suitable substance, it w but which will produce casings of greater efficiency because possessing characteristics which entirely eliminate some of the difiiculties heretofore encountered in the use of 01's casings.

I have found that if blast furnace slag is properly prepared and mixed in ordinary waterm ropcr proportions with commercial Portlan cement, it ma be molded into proper shape for use as s rink-head casm and that, if the surface of such a cast Be rendered water-proof or non-absorbent of liquids or gases. This treatment of the casing also prevents the formation and liberation of such gases in the interior of the casing as would produce an endo-thermic aetion in connection with the molten metal contacting'with the casing which would result in what is known in the art as a boil, or such a disturbance in the forming ingot as to. impede or mar the proper casting of the ingot, and the formation of gases in the casing which would crack or break 1t.

' My improvements are illustrated in the accompanying drawings in which Fig. 1 is a perspective view showing the u per portion of an ingot mold and a shr1nk ead casing made in accordance with my invention; Fig. 2 a vertical sectional view of an ingot mold with a shrink-head casing supported in operative relation thereto and thereon the section being taken on the hue 22 of Fig. 6; Fig. 3 a detail in vertical section of a portion of the shrink-head casing show ing how its walls are treated in the manner hereinafter specified; Fig. 4 a central vertical sectional view through the mold and casing, showing how the molten metal rises into the casing during the pouring operation; Fig. 5 a view similar to Fig. 4 showing how the ingot, during shrinkage, draws away from the casing without bodily moving the latter; and Fig. 6 is a top plan view of the ingot mold, with the said shrink-head casing rest-ing thereon.

The rticular shape of the casing is not essenti Various she may be used, but that illustrated in the rawing is preferred. As shown, the casing B is generall rectangular in horizontal cross section. e lower partof the casing is rounded at the four corners thus producing a lower part c which is adapted to enter the mold cavity and shoulders d which are adapted to rest on kill the top of the mold and thus su port the casing. While I prefer to mold t e casing in one integral piece, it may be made in sections. When the mold is of larg size, a sectional casing may be found preferable. The ingot mold A shown herein is of the Gathmann dicated at I.

While heretofore shrink-head casings have ordinarily been made of refractory material,

type, and the ingot therein is insuch as fire clay baked at a high temperature in a special lant generally remote from the steel plant, t e casings made in accordance with my invention are made of relatively low-refracto material, baked or hardened at a relatively low temperature, and may be made at the steel plant, inasmuch as I employ furnace slag as a principal ingredient. of the casing and combine such slagpwith a suitable pro ortion of commercial ortland cement, WllCh is readily obtamab e. s urnace slsu gives the best results, oug open learth or other sla may be used.

' I my application for patent filed April 20, 1925, Lo. 24,684, I have described and claimed the method of preparing, forming and treating the material to produce shrinkhead casings having the desired characteristics. Br1efly stated, the method consists in grindm or crushing ordinary slag taken from t e dump, screening this product through 4 inch mesh to eliminate the large lumps, then mixing the screened slag with commercial cement, preferably in the proportions of about 7 parts by weight of slag to about 1 part by weight of cement, although these proportions may be somewhat varied. By t is treatment, the c mentand slag are thoroughly mixed an blended whlile dry, {151d then a sgiltadble amount of or lnary co w ter is a e to )roducc a stiff moimihF which is then placed in suitable molds and rammed or tamped in the usual way until the desired shape is obtained. The casings are then preheated. or heated at a relativel low temperature in a suitable furnace to about 200 to 250 F. for about .-12 hours. In this way all free moisture eliminated and the setting of the cementl hastened. The cement as it sets acts as a binder and I preferably use commercial Pprtlan cement for such binder, although-other materials mi ht be used for this (purpose with fairly g results; When drie and bakedat'the temperatures specified, the casing is rendered pogous and in cod-condition to receive the im re 'nating i uid'or substance which serves prevent e 0 on an liberation of deleterious gases from the casing when the latter is sub- Lected to the intense heat of the ingot while ingformed. Fo'r'this urposeIpreferabl employ a substance sod as oulac we own to foundry mennna w 0 consists the following 1 10m mgr 1en Aluminum oxide (A1,0,), ferric oxide (Fe,0,), manganese oxide (Mn,0,), calcium oxide (CaO), magnesium oxide The ce'llu ose 1n the goulac 18 that obtained from the dried li nor from the manufacture of sulfihite p p. A non-or anic compound, suc as mggesium fluosihcate,

may also be used instead of goulac. The impregnatin substance ma be applied by spraying, brushing or b i ping the easing into a. bath of the iquit l, whereby all the walls are impregnated to a suitable distance with the impregnating substance. While ood results have been obtained where t e impregnation extends from to inch into the casing walls, it is preferable to impregnate the casing completely, as indicated by the stippling at a: in Figs. 1 and 3. The impregnating material serves not only to prevent the formation and liberation of gases but it also renders the casing as a whole substantially water-proof, so that it will not absorb moisture and thus render the porous casing liable to rupture or spawling through the formation of steam or gases therewithin.

After being thus treated, the casings are baked in a suitable furnace for about 12 hours, the latter being heated to a temperature of from 600 to 800 F. which, it will be observed, is not only a much lower temperature than that employed for burning fire clay but one which will not fuse the slag ingredient of the casings. hen thus baked, the casings are complete and ready for use on the molds.

While I prefer to apply the impregnating substance to the entire exterior of each casing, it may be applied only to the inner walls thereof which come in contact with the molten metal of the forming ingot, and I may apply other forms of water-proofing material to other parts of the casing.

Inasmuch as the interior of each casing is porous and substantially moisture-free, it serves as a heat insulator. and the metal of the forming ingot at the top of the mold is maintained in liquid condition until the forination of the ingot is completed.

While my casing is in use, the hot molten metal which rises in it when the mold is being poured softens the inner walls of the casing. due to the fusion of the slag constituent thereof, and renders them non-adherent to the ingot. so that as the forming ingot shrinks it will draw away from the casing without imparting harmful strains thereto. the inner surface of the casing flowing with the shrinking ingot. This feature of the invention is illustrated in Figs. 4 and 5 of the drawings.

The casing. when in use, is supported at all times on the shoulders (Z and no provision is made for lowering the easing into the mold cavity to accommodate the shrinkage of the solidifying ingot, indicated at I.

By reference to Fig. 4 it will be seen that the ingot has an upper portion '5 within the casing. At the stage illustrated in Fig. 4, the lower endge of the casing comes in contact with a ledge 1 of the ingot, but as the ingot solidifies and shrinks it lowers or pulls without moving the casingr or putting any harmful strain thereon. his is quite an important feature of the invention. F urthermore, the impregnating substance prevents the swelling or spawling of the slag constituent of the casing and thus enables the mgot to free itself during its solidifica- H011 and shrinkage.

My invention, while especially designed for use in connection with molds for forming steel ingots, may be employed in connection with molds of other kinds and with molds for forming other kinds of castings.

It has been stated that the plant for makmg the casings is conveniently located at the steel plant where the slag is found, but it is of course feasible to make the casings in plants remote from the steel plants, although this involves transportation and additional expense. In any event, by using a waste product such as slag in connection with a relatively small percentage of cement or binding material, in casings may be made very much more 0 eaply than can those made of fire clay; and casings made in accordance with my invention possess the beneficial characteristics, set forth hereinbefore, which are not found in casings heretofore employed.

While the slags mentioned hereinbefore will produce casings having the advantages referred to, the best results are obtained by using a slag containing a substantial proportion of magnesia.

In my application for Patent No. 758,594, filed December 29, 1924, I have claimed broadly among other things a shrink-head casing made from a mixture of furnace slag and a binder. I have also claimed broadly a shrink-head casing of refractory material treated or combined with a material capable of preventing the deleterious action of the gas producing constituents of the casing.

Having thus described my invention, what I claim is 1.- A shrink head casing for ingot molds comprising a mixture of furnace slag and a binder and having its inner walls impregnated with a substance which prevents the deleterious action of the gas producing constituents of the mixture.

2. A shrink head casing for ingot molds comprising a mixture of furnace slag and comprising a mixture of blast furnace slag and a binder combined with a substance which prevents the deleterious action of the gas forming constituents of the mixture.

4. A shrink head casing for ingot molds comprising a mixture of furnace slag and cement and which has its inner walls 1mpregnated with a substance which prevents the deleterious action of the gas producing constituents of the mixture, said casing being rendered impervious to moisture throughout its entire exterior.

5. A shrink head casing for ingot molds comprising a mixture of refractory material and a binder, having .its inner walls impregnated with a substance which prevents the deleterious action of the gas producing constituents of the mixture and said casing being also coated throughout its exterior to render it waterproof.

6. A shrink head casing for ingot molds comprising a mixture of last furnace slag and Portland cement, having its inner walls impregnated with a substance which prevents the formation and liberation of gases when the casing is subjected to the intense heat of a forming ingot.

7. Ashrink head casing for ingot molds made of thoroughly blended refractory material and a binder having a porous moisture free interior and water proofed outer walls.

8. A shrink head casing for ingot molds comprising a mixture of last furnace slag and cement and having a porous interior and a water proofed outer surface.

9. A shrink head casing for ingot molds made of blast furnace slag and cement, having an inner wall, the surface of which is fusible and thus non-adherent to the forming in ot to allow the ingot to descend while s rinking without moving the casin 10. A shrink head casing for ingot molds composed of refractory material and a bind er, having inner walls which are fusible to an extent to render them non-adherent to the ingot to thus allow the hot upper end of the formin .ingot to slip downward in the casing whi e the ingot is solidifying and shrinking.

11. A shrink head casin for ingot molds made of a mixture of re ractory material and a binder having its inner walls fusible at a temperature below that of the forming ingot to thus become non-adherent to the ingot and to thus allow the upper end of the ingot to shrink in the mo d'without moving the casing.

12. A shrink head casing for ingot molds made of refractory material and a binder having an inner wall, the surface of which is fusible and thus non-adherent to the forming ingot to thus allow the ingot to descend in the mold while shrinking without moving the casin said inner wall be ing impregnated wit a substance which renders inactive the gas producing constituents of the casing.

13. A shrink head casing made of refractory having a porous,

for ingot molds material and a binder moisture free interior and having its inner wall impregnated with a substance which renders inactive the gas producing constituents of the mixture, the surface of said inner walls being fusible at the temperature of the forming ingot to allow the formin ingot to slip past the casing while shrinking.

14. A shrink head casing for ingot molds made of a mixture of blast furnace slag and cement, impregnated throughout with a substance which renders inactive the gas producing constituents of the mixture, the surface of the inner walls of'the casin being fusible at the tem erature of the orming ingot to allow the forming ingot to slip past the casing without moving it while the ingot is shrinking.

15. shrink-head casing for ingot molds comprising a mixture of furnace slag and cement in about the proportions of seven parts of slag to one part of cement and having its inner wall treated with a substance which prevents the deleterious action of the gas-producing constituents of said casing.

16. A shrink-head casing for ingot molds comprising a mixture of furnace slag and a binder in the proportions of about seven parts of such slag to one art of the binder and having its mner wall treated with a substance which prevents the deleterious action of the gas-producing constituents of the casing.

17. A shrink-head casing for ingot molds comprising a mixture of furnace slag and cement in the proportions of about seven parts of such slag to one part of cement, the said casing having a water-proofed exterior.

18. A shrink-head casin for ingot molds made of a mixture of re actory material and a binder and having an inner wall which is fusible at the temperature. of the molten metal of the ingot and having its exterior water-proofed.

In testimony whereof, I hereunto afiix my signature.

FRED H. CHAPIN.

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